Patent Application
20250170827
The present embodiment relates to a device manufacturing method, a head manufacturing method, a piezoelectric device, a liquid discharge head, and a liquid discharge apparatus.
Attempts have been made to use piezoelectric devices that vibrate thin films in various fields. The piezoelectric device is used, for example, in medicine, industry, and the like, and is used among them, for example, in a liquid discharge head.
As a liquid discharge apparatus using the liquid discharge head, a liquid discharge apparatus using a thermal system (or a bubble system) and a piezoelectric system is known.
The thermal system has a small size, high density, and ultra-low cost as main characteristics (advantages), and is widely used in inkjet printers for offices, small office home office (SOHO), and homes. A major reason for the small size, high density, and ultra-low cost is a simple structure and complementary metal oxide semiconductor (MOS) (CMOS) on-chip (a CMOS can be formed on the same substrate as a droplet discharge thermal element). In contrast, the thermal system has a disadvantage that a degree of freedom in ink and driving durability are lower than those of the piezoelectric system, and is slightly behind in commercial and industrial printers.
The piezoelectric system has main characteristics (advantages) of high driving force (high viscosity and large droplet discharge), high degree of freedom in ink, and high driving durability, and is widely used in inkjet printers for commercial and industrial use. Although this is also used in inkjet printers for offices, SOHO, and homes, this is significantly inferior in cost competitiveness to the thermal system.
In a piezoelectric system liquid discharge apparatus, a piezoelectric material of lead zirconate titanate (PZT) is usually used, and is usually formed at high temperature of about 850° C. In an optical device or an ultrasonic device, a CMOS integrated piezoelectric element using PZT or another piezoelectric material formed at temperature lower than this temperature has been proposed.
For example, Patent Literature 1 discloses a droplet discharger including a substrate including a nozzle surface, an electronic component integrated with the substrate, a nozzle-forming layer on the nozzle surface of the substrate, and a piezoelectric actuator on the nozzle-forming layer, and discloses that the electronic component includes a CMOS electronic component integrated with the substrate. An object of Patent Literature 1 is to reduce acoustic crosstalk between piezoelectric droplet dischargers and achieve a larger number of nozzles.
Patent Literature 1 discloses that the piezoelectric body is formed of one or a plurality of piezoelectric materials that can be processed at temperature lower than 450° C. Patent Literature 1 points out that integrated electronic components (for example, CMOS electronic components) deteriorate when the temperature exceeds 300° C. or 450° C., and discloses that using a piezoelectric material that can be processed at temperature lower than 450° C. enables processing of a piezoelectric actuator and integration of electronic components.
Although a piezoelectric system liquid discharge head is required to have excellent piezoelectric characteristics with a large driving force, a CMOS integrated piezoelectric element that enables this is not put into practical use, and there is no example of putting this on the market. From the viewpoint of management of a manufacturing step, the viewpoint of securing various characteristics of the obtained liquid discharge apparatus, and the like, it has been difficult to implement a liquid discharge head using the CMOS integrated piezoelectric element. For example, when the formation temperature of the piezoelectric element is lowered as in Patent Literature 1, there has been a disadvantage that a piezoelectric performance (driving force) of the piezoelectric element is significantly deteriorated or this does not function as the piezoelectric element. In contrast, when the formation temperature of the piezoelectric element is increased, a disadvantage arises that the CMOS element is deteriorated.
Also when a technology of driving and vibrating the piezoelectric element in the liquid discharge head is to be applied to other applications, it is desired to implement the CMOS integrated piezoelectric element. In this case, it is required that a CMOS operation may be performed and excellent piezoelectric characteristics are obtained.
Therefore, an object of the present embodiment is to provide a piezoelectric device including a CMOS element and a piezoelectric element on the same substrate, and achieving both the CMOS operation and excellent piezoelectric characteristics.
In a device manufacturing method for manufacturing a piezoelectric device, the device manufacturing method includes: forming a CMOS element on a first surface of a substrate; forming a piezoelectric element over the first surface of the substrate on which the CMOS element is formed; forming a first insulating film in a region where the piezoelectric element is formed when forming the CMOS element or the piezoelectric element, forming a lower electrode layer, a piezoelectric layer, an upper electrode layer, and a second insulating film on the first insulating film when forming the piezoelectric element; forming a CMOS wiring layer of the CMOS element and a piezoelectric wiring layer of the piezoelectric element after forming the CMOS element and the piezoelectric element on the substrate; and forming a void in the substrate from a second surface opposite to the first surface of the substrate after forming the CMOS wiring layer and the piezoelectric wiring layer on the substrate.
A piezoelectric device includes: a substrate having a void; a CMOS element on a first surface of the substrate; and a piezoelectric element on the first surface of the substrate, the piezoelectric element including: a lower electrode layer having a first surface on the first surface of the substrate; a piezoelectric layer having a first surface on a second surface opposite to the first surface of the lower electrode layer; an upper electrode layer having a first surface on a second surface opposite to the first surface of the piezoelectric layer; a first insulating film on the first surface of the lower electrode layer; and a second insulating film on the second surface of the upper electrode layer, the second insulating film having a thickness thicker than the first insulating film.
According to the present embodiment, it is possible to provide a piezoelectric device including a CMOS element and a piezoelectric element on the same substrate and achieving both a CMOS operation and excellent piezoelectric characteristics.
A more complete appreciation of embodiments of the present disclosure and many of the attendant advantages and features thereof can be readily obtained and understood from the following detailed description with reference to the accompanying drawings.
The accompanying drawings are intended to depict embodiments of the present disclosure and should not be interpreted to limit the scope thereof. The accompanying drawings are not to be considered as drawn to scale unless explicitly noted. Also, identical or similar reference numerals designate identical or similar components throughout the several views.
In describing embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of this specification is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents that have a similar function, operate in a similar manner, and achieve a similar result.
Referring now to the drawings, embodiments of the present disclosure are described below. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.
Hereinafter, a piezoelectric device, a liquid discharge head, a liquid discharge apparatus, a method of manufacturing the piezoelectric device, and a method of manufacturing the liquid discharge head according to the present embodiment will be described with reference to the drawings. The present embodiment is not limited to the embodiments described below, and changes such as other embodiments, additions, modifications, and deletions can be made within the scope that can be conceived by those skilled in the art, and any aspect is included in the scope of the present embodiment as long as the function and effect of the present embodiment are achieved.
When a CMOS element and a piezoelectric element are formed on the same substrate (for example, a Si substrate), it is required to first form the CMOS element and then form the piezoelectric element from the viewpoint of step management to avoid contamination of a semiconductor manufacturing line with heavy metals, alkalis, and the like. In this case, in order to secure (maintain) various characteristics of the previously formed CMOS, it is required to form the piezoelectric element at temperature lower than formation temperature of the CMOS.
In contrast, when the formation temperature of the piezoelectric element is lowered, piezoelectric performance (driving force) of the piezoelectric element is significantly deteriorated, or the piezoelectric element does not function as the piezoelectric element. Therefore, it has been difficult to implement a piezoelectric device using a CMOS integrated piezoelectric element. That is, it has been difficult so far to implement the piezoelectric device in which the CMOS integrated piezoelectric element in which an operation of the CMOS element is secured and excellent piezoelectric characteristics of the piezoelectric element are secured is arranged.
When the piezoelectric device is used as a liquid discharge head or the liquid discharge apparatus, it has been difficult so fat to implement the liquid discharge head or a liquid discharge apparatus including the CMOS integrated piezoelectric element in which the operation of the CMOS element is secured and a droplet discharge operation is secured. The CMOS integrated piezoelectric element refers to a configuration in which the CMOS element and the piezoelectric element are arranged on the same substrate.
If the CMOS element can be manufactured on the same substrate as the piezoelectric element, an area of electrode wiring and electrode mounting can be reduced, and a chip area of the piezoelectric element can be significantly reduced. In this case, for example, the chip area of the piezoelectric element is about 1/10. Since the number of components can also be reduced, it becomes possible to provide a small, high-density, and low-cost liquid discharge apparatus by a piezoelectric system.
However, in order to obtain the piezoelectric element with high driving force (high performance) that can discharge droplets, formation temperature of about 850° C. is usually required, and this breaks the previously formed CMOS element. The breakdown of the CMOS element specifically is, for example, an operation failure due to a threshold voltage shift of a P-channel metal oxide semiconductor (PMOS) and an N-channel metal oxide semiconductor (NMOS), elution or disconnection of metal wiring, a crack or dielectric breakdown of an insulating layer, and the like. In contrast, when the formation temperature of the piezoelectric element is made lower than usual, the piezoelectric element does not exhibit desired piezoelectric performance (piezoelectric characteristics).
In order to form the CMOS element and the piezoelectric element on the same substrate, an appropriate devise is required, and the inventor of the present embodiment conducted intensive studies. When the piezoelectric element is formed after the CMOS element is formed, it is considered that the piezoelectric element is required to be formed at the formation temperature of, for example, 500° C. or lower in order to avoid a damage to the wiring (for example, metal wiring and an interlayer insulating film) to the CMOS element. However, when the piezoelectric element is formed at such formation temperature, the piezoelectric characteristics are deteriorated.
Therefore, after forming the CMOS element, the piezoelectric element was formed at formation temperature in a predetermined range before forming the CMOS wiring. When appropriately studying manufacturing conditions, a configuration in which a desired CMOS operation can be performed and excellent piezoelectric characteristics can be obtained also when the CMOS element and the piezoelectric element are formed on the same substrate was found.
In order to form the CMOS element and the piezoelectric element on the same substrate and enable a more excellent CMOS operation and excellent piezoelectric characteristics, it is also required to devise a manufacturing method. Although the manufacturing method will be described later in detail, in the manufacturing method of the present embodiment, for example, measures are taken such as changing the order of steps in a conventional manufacturing method. In the manufacturing method of the present embodiment, after the CMOS element is formed, the piezoelectric element is formed, and then wiring to the CMOS element is formed. This makes it possible to avoid damage to the CMOS element and the wiring to the CMOS element. In such manufacturing method, for example, a predetermined relationship occurs in thicknesses of insulating films.
A piezoelectric device according to the present embodiment includes a CMOS element and a piezoelectric element formed on the same substrate, the piezoelectric element including a lower electrode layer, a piezoelectric layer, and an upper electrode layer, the substrate including a void on a side opposite to the piezoelectric layer across the lower electrode layer, the piezoelectric device includes a first insulating film on a lower side of the lower electrode layer and a second insulating film on an upper side of the upper electrode layer, the first insulating film under the piezoelectric layer thinner than the second insulating film above the piezoelectric layer.
According to the present embodiment, it is possible to provide the piezoelectric device including the CMOS element and the piezoelectric element on the same substrate and achieving both the CMOS operation and excellent piezoelectric characteristics. The piezoelectric device of the present embodiment can secure various characteristics of the CMOS element, and can obtain excellent piezoelectric characteristics having excellent driving force while maintaining the CMOS element operation.
In the piezoelectric device in this example, a CMOS element 120 and a piezoelectric element 160 are formed on the same silicon substrate 100. The silicon substrate 100 may be a P-type substrate or an N-type substrate. In this example, the P-type substrate is used.
The CMOS element 120 in this example includes an N well 111, a gate oxide film 113, a gate electrode 114, a source electrode 116a, a drain electrode 116b, and a substrate electrode 117. In this example, the CMOS element 120 and a wiring layer are distinguished from each other, and a portion including the CMOS element 120 and a part of the wiring layer is made a CMOS component 140.
The N well 111 is a CMOS well. The CMOS well may be an N well or a P well. In this example, N well is used.
A field oxide film 112 is an element isolation insulating film. It is possible that the CMOS element 120 includes the field oxide film 112 or not.
The CMOS is formed of a combination of the NMOS and PMOS. In the drawings in this example, only the PMOS is illustrated and that related to the NMOS is omitted for convenience.
A sidewall 115 is formed on the gate electrode 114, and the sidewall 115 is omitted in
The source electrode 116a, the drain electrode 116b, and the substrate electrode 117 are formed by, for example, high-concentration impurity ion implantation, and may be referred to as an impurity diffusion layer and the like. In the drawing, the source electrode 116a and the drain electrode 116b may be reversed.
As the wiring layer, a contact hole 132, metal wiring 135, and an interlayer insulating film are illustrated in the drawing. The interlayer insulating film is formed between the metal wiring 135 and the metal wiring 135. A reference sign of the interlayer insulating film is herein omitted.
The wiring layer can have, for example, a multilayer structure. For example, it is possible to sequentially form a contact hole, a first layer of metal wiring (metal 1), an insulating interlayer film (interlayer film 1), a through hole, a second layer of metal wiring (metal 2), . . . , an insulating interlayer film (interlayer film n), a through hole, an n-th layer of metal wiring (metal n), and the like to form the wiring layer. In this example, the metal wiring 135 includes two layers.
The contact hole 132 is provided to obtain electrical contact with the gate electrode 114, the source electrode 116a, the drain electrode 116b, and the substrate electrode 117. The through hole is provided to obtain electrical contact between the metal wiring and the metal wiring.
As metal used for the wiring, for example, an aluminum-based material can be used. A copper-based material having low resistance and withstanding higher temperature can also be used. In the present embodiment, there is no limitation, and other materials can be used as appropriate.
As the insulating interlayer film, a silicon oxide film by a chemical vapor deposition (CVD) method is generally used. A silicon nitride film having high moisture resistance is also often used as an alternative layer or an additional layer. In the present embodiment, there is no limitation, and other films can be used as appropriate.
The piezoelectric element 160 in this example includes a lower electrode layer 161, a piezoelectric layer 162, and an upper electrode layer 163. The piezoelectric element 160 is coupled to the CMOS element 120 via the metal wiring 135. In the drawing, the metal wiring 135 and the lower electrode layer 161 are coupled to each other, but there is no limitation, and the metal wiring 135 and the upper electrode layer 163 may be coupled to each other.
In the drawing, a displacement portion 175 is indicated by a broken line. The displacement portion 175 is a region where the piezoelectric element 160 is not formed, and is a portion that is significantly deformed and displaced when a voltage is applied to the piezoelectric element 160. When the displacement portion 175 is deformed, a vibration region 181 vibrates.
As the lower electrode layer 161 and the upper electrode layer 163, for example, platinum (Pt) can be used, but there is no limitation, and a conductive metal material and the like can be used. The lower electrode layer 161 and the upper electrode layer 163 may be made of the same material or different materials.
The lower electrode layer may be referred to as a first electrode and the like, and the upper electrode layer may be referred to as a second electrode and the like. The lower electrode layer may be a common electrode and the upper electrode layer may be an individual electrode, or the lower electrode layer may be an individual electrode and the upper electrode may be an individual electrode.
For example, lead zirconate titanate (PZT) or potassium sodium niobate (KNN) can be used for the piezoelectric layer 162. It is preferable to use PZT for the piezoelectric layer 162.
A method of forming the piezoelectric layer 162 is not particularly limited, and can be appropriately selected. In the case of PZT, a sol-gel method or a sputtering method is common, but a chemical vapor deposition (CVD) method may be used, and the method is not limited thereto.
The silicon substrate 100 includes a void 190 on the side opposite to the piezoelectric layer 162 with the lower electrode layer 161 interposed therebetween. Since the void 190 is provided, the vibration region 181 can vibrate. When the piezoelectric device is the liquid discharge head or the liquid discharge apparatus, the void 190 is a liquid chamber. The void 190 is, for example, a cylindrical opening opened in the silicon substrate 100.
When a drive voltage is applied between the lower electrode layer 161 and the upper electrode layer 163, mechanical deformation occurs in the piezoelectric layer 162. When vibration at a predetermined frequency is generated due to periodic variation of the drive voltage, the vibration region 181 vibrates to generate an ultrasonic wave or to discharge droplets in a case of the liquid discharge head.
The piezoelectric device of the present embodiment may include a through hole that penetrates the piezoelectric element 160 and communicates with the void 190; in this case, the piezoelectric element 160 is formed around the through hole. The through hole thus formed can be a nozzle hole that discharges liquid when the piezoelectric device is the liquid discharge head.
The piezoelectric device of this example includes a first insulating film 171 on a lower side of the lower electrode layer 161 and a second insulating film 172 on an upper side of the upper electrode layer 163. The first insulating film 171 under the piezoelectric layer 162 is thinner than the second insulating film 172 above the piezoelectric layer 162. Although the method of manufacturing the piezoelectric device will be described later in detail, in the present embodiment, the CMOS element 120 and the piezoelectric element 160 are formed on the silicon substrate 100, and then the wiring layer is formed. By manufacturing in such order, the first insulating film 171 under the piezoelectric layer 162 becomes thinner than the second insulating film 172 above the piezoelectric layer 162. It is defined “under the piezoelectric layer” and “above the piezoelectric layer” in order to clarify a place where the thicknesses of the insulating films are compared with each other.
The method of manufacturing the piezoelectric device of the present embodiment is different from the conventional manufacturing method of forming the wiring layer for the CMOS element and then forming the piezoelectric element. In the method of manufacturing the piezoelectric device of the present embodiment, after the CMOS element is formed, the piezoelectric element is formed, and then the wiring layer is formed. In a case of the manufacturing method as in the present embodiment, the second insulating film 172 (upper insulating film) is thicker than the first insulating film 171 (lower insulating film) for the reason described below. For example, the second insulating film 172 is manufactured to be several times thicker than the first insulating film 171.
When the CMOS element and the piezoelectric element are manufactured on the same substrate, and the wiring layer for the CMOS element is further formed after the piezoelectric element is formed, a layer for forming the interlayer insulating film is formed also on the piezoelectric element at the same time when the interlayer insulating film in the wiring layer for the CMOS element is formed. Together with a protective insulating film of the piezoelectric element, the insulating film on the piezoelectric element becomes thicker. For this reason, in the present embodiment, the second insulating film (upper insulating film) is thicker than the first insulating film (lower insulating film); in other words, the first insulating film is thinner than the second insulating film. Although described a little with reference to
At that time, it is considered that vibration is also possible by making the first insulating film thicker than the second insulating film. However, if it is attempted to make the first insulating film thicker than the second insulating film, the layer for forming the interlayer insulating film is formed also on the piezoelectric element at the same time when the interlayer insulating film in the wiring layer for the CMOS element is formed, so that a total thickness of the insulating film in the vibration region increases. Therefore, when it is attempted to make the first insulating film thicker than the second insulating film, the total thickness of the insulating film in the vibration region increases, an excellent displacement amount cannot be secured, and excellent piezoelectric characteristics cannot be obtained. In particular, in a case of a nozzle plate vibration system liquid discharge head, it is difficult to perform an excellent droplet discharge operation.
The nozzle plate 251 (nozzle vibration plate) includes the first insulating film 171 (lower insulating film), piezoelectric element 160, the second insulating film 172 (upper insulating film), and layers such as a resin layer over the second insulating film 172. In order to obtain desired vibration characteristics, the film thickness, rigidity, film stress, dimensions (for example, the width of the diaphragm and the like) and the like of each layer are preferably formed precisely in advance to be designed and manufactured. Especially, the thickness of each layers are controlled precisely to obtain the desired vibration characteristics.
The first insulating film 171 and the second insulating film 172 can be appropriately selected, and for example, a silicon oxide film, a silicon nitride film, a laminated film of the silicon oxide film and the silicon nitride film, and the like can be used. As the first insulating film 171 and the second insulating film 172, for example, a silicon oxide film by a CVD method is generally used. A silicon nitride film having high moisture resistance is also often used as an alternative layer or an additional layer. In the present embodiment, there is no limitation, and other films can be used as appropriate.
A portion including the first insulating film 171, the second insulating film 172, and the piezoelectric element 160 in the vibration region 181 may be referred to as a diaphragm and the like. The diaphragm is a portion that affects piezoelectric characteristics, and the piezoelectric characteristics are affected by not only characteristics (piezoelectric characteristics, rigidity, various dimensions, and the like) of the piezoelectric element 160 but also the film thicknesses and materials of the first insulating film 171 and the second insulating film 172.
The piezoelectric device of the present embodiment can be used not only for the liquid discharge head but also for various purposes. Although the present embodiment has been obtained in the process of developing the liquid discharge apparatus, an application range of the technology of the present embodiment is not limited to the liquid discharge apparatus. The piezoelectric device of the present embodiment can be made the piezoelectric device having a higher driving force than that of the conventional piezoelectric device, and the application range thereof is not limited to the liquid discharge apparatus. The piezoelectric device according to the present embodiment can be applied to a wide variety of small devices, functional devices, and the like, such as a micro infusion pump that precisely transports a small amount of liquid, an optical system (deflection) device such as a projector, an ultrasonic (generation, detection, vibration) system device, a hearing aid, for example. In addition, for example, application to a medical ultrasonic diagnostic apparatus and the like is possible.
In this example, the piezoelectric layer 162 is formed into a dome shape. In this example, an interlayer insulating layer 178 is provided on the upper side of the upper electrode layer 163. The second insulating film 172 also has a function of protecting a signal line 179. For example, the piezoelectric elements 160 are arranged in an array, and the respective piezoelectric elements 160 are electrically coupled to each other by the signal line 179. In this example, the central axis of the piezoelectric element 160 is indicated by O. The void 190 is, for example, a cylindrical opening opened in the silicon substrate 100.
In this manner, in the present embodiment, the shape and the like of the piezoelectric layer in the piezoelectric element can be appropriately changed. Also in the example illustrated in
Next,
That is, the diaphragm 380 in
Next,
The displacement portion 175 indicated by a broken line in the drawing is a portion that deforms more than other portions at the time of driving (at the time of bending). Configurations of the first insulating film 171, the piezoelectric element 160, the second insulating film 172, and the displacement portion 175 affect various vibration characteristics. Although not described in detail, it is designed in consideration of a film thickness, rigidity, an internal stress, various dimensions (width, length, shape, and the like), and the like of the first insulating film 171, the piezoelectric element 160, the second insulating film 172, and the displacement portion 175. It has been found that they significantly affect various vibration characteristics, and appropriate pre-design is required through simulation and short-loop experiment.
When the diaphragm is vibrated by the piezoelectric system, it is required to make one of the upper insulating film and the lower insulating film thick (thin). When they have the same thickness, it is not possible to vibrate. Therefore, in
The piezoelectric device of the present embodiment can be suitably applied to the liquid discharge head.
The liquid discharge head of the present embodiment is provided with the piezoelectric device of the present embodiment, and includes the through hole that penetrates the piezoelectric element 160 and communicates with the void 190. The void 190 is supplied with liquid, and the through hole is a nozzle hole (nozzle) that discharges the liquid. The piezoelectric element 160 is formed around the nozzle hole.
According to the present embodiment, it is possible to obtain the liquid discharge head including the CMOS element and the piezoelectric element on the same substrate and achieving both the CMOS operation and droplet discharge operation. The liquid discharge head of the present embodiment can secure various characteristics of the CMOS element, and can obtain piezoelectric performance (driving force) that enables discharge of droplets while maintaining the CMOS element operation.
Before describing an example of the liquid discharge head of the present embodiment, a discharge system in the liquid discharge head will be described.
In the example illustrated in
Since the diaphragm 280 includes the nozzle, this may be referred to as a nozzle plate and the like. In this manner, since the diaphragm including the nozzle (nozzle plate) vibrates to discharge the liquid, the discharge system in the example illustrated in
In contrast, in the conventional discharge system illustrated in
In the conventional discharge system, a voltage (drive voltage) is applied to the piezoelectric element 260 to vibrate the diaphragm 280 as indicated by arrows in the drawing, and the ink in the individual pressure chamber 291 is pressurized. Thus, the ink is discharged from the nozzle 250.
In the conventional discharge system, a large pressurizing force is required to discharge the ink, and the piezoelectric element is required to have high piezoelectric performance (high driving force). Although a bulk (solid) lead zirconate titanate (PZT) element has been widely used for the piezoelectric element so far, in recent years, piezoelectric performance of a thin film PZT has been improved, and the thin film PZT has been widely used. It has been recently found that a non-lead potassium sodium niobate (KNN) material exhibits high piezoelectric performance, and utilization thereof has started. A method of pressurizing the ink has a complicated discharge mechanism such as using pressure resonance, but a detailed description thereof is herein omitted.
Conventionally, the liquid discharge apparatus of the conventional discharge system illustrated in
It is considered that the problems in workability of PZT can be solved by the recent practical application of the thin film PZT element, and the problems in mounting the electrode can be solved by applying an improved method of mounting the electrode of a thermal head. It has been found that, when the thin film PZT element and the improved method of mounting the electrodes of the thermal head are applied to the example illustrated in
Specifically, for example, in the example illustrated in
In the nozzle plate vibration system, since an inertia force of fluid in the vicinity of the nozzle can be used because the nozzle plate including the nozzle directly vibrates, it is considered that the ink can be discharged with a low driving force as compared with the conventional discharge system. The inventor of the present embodiment confirmed through simulations and demonstration experiments that droplets can be discharged even when the driving force of the diaphragm is reduced to about several tenth part of that of the conventional discharge system in the nozzle plate vibration system. However, there are still many unclear points in the discharge principle, and the detailed description thereof is herein omitted.
As described in the description of the piezoelectric device, it is necessary to appropriately contrive to form the CMOS element and the piezoelectric element on the same substrate, and the inventor of the present embodiment conducted intensive studies. The method of manufacturing the piezoelectric device of the present embodiment is different from the conventional manufacturing method in which the piezoelectric element is formed after the wiring layer for the CMOS element is formed. In the method of manufacturing the piezoelectric device according to the present embodiment, after the CMOS element is formed, the piezoelectric element is formed, and then the wiring layer is formed. By doing so, the CMOS element and the piezoelectric element can be formed on the same substrate, the CMOS operation can be performed, and the excellent piezoelectric characteristics can be obtained.
In contrast, it was found that, even when the piezoelectric device in which the CMOS element and the piezoelectric element are formed on the same substrate, the piezoelectric device that can perform the CMOS operation was applied to the liquid discharge head, an excellent droplet discharge operation could not be performed by the conventional discharge system. Therefore, intensive studies were conducted, and a condition was found that both a desired CMOS operation and the droplet discharge operation can be achieved by forming the CMOS element, then forming the piezoelectric element at formation temperature set in a predetermined range before forming the CMOS wiring, and combining the same with a nozzle plate vibration system. The content specifically studied is a relationship with the piezoelectric characteristics and a relationship with the droplet discharge operation in the nozzle plate vibration system with the formation temperature of the piezoelectric element as a parameter. This study result will be described in a manufacturing method, examples, and the like.
The liquid discharge head of the present embodiment includes the CMOS element and the piezoelectric element on the same substrate, and can achieve both the CMOS operation and the excellent droplet discharge operation.
According to the present embodiment, it is possible to obtain advantages of a thermal system while maintaining advantages of the piezoelectric system. In the piezoelectric system, advantages such as a high driving force (high viscosity, large droplet), a high degree of freedom in ink, and high driving durability are easily obtained, but it has been conventionally difficult to simultaneously obtain advantages of the thermal system such as small size, high density, and low cost. By implementing the liquid discharge head including the CMOS element and the piezoelectric element on the same substrate as in the present embodiment, the above-described advantages can be obtained by further adopting the nozzle plate vibration system.
In the present example, as illustrated in the drawing, the through hole that penetrates the piezoelectric element 160 and communicates with the void 190 is included, and the through hole is the nozzle hole 150 that discharges liquid. The void 190 to which the liquid is supplied may be referred to as a liquid chamber, an individual chamber, and the like.
The piezoelectric element 160 is formed around the nozzle hole 150. When the displacement portion 175 is deformed, the vibration region 181 vibrates. A portion including the first insulating film 171, the second insulating film 172, and the piezoelectric element 160 in the vibration region 181 may be referred to as the diaphragm or nozzle plate. In this example, when the piezoelectric element 160 is driven, the nozzle plate vibrates, and droplets are discharged from the nozzle hole 150. In this manner, the liquid discharge head of the present example discharges the droplets by the nozzle plate vibration system.
The diaphragm containing the piezoelectric element 160 is a portion that significantly affects the droplet discharge characteristics. The droplet discharge characteristics are affected not only by the characteristics (piezoelectric characteristics, rigidity, various dimensions, and the like) of the piezoelectric element 160 but also by the film thickness, material, and the like of the first insulating film 171 (lower insulating film) and the second insulating film 172 (upper insulating film).
The ink liquid contact film 176 is provided at the site in contact with the liquid. The ink liquid contact film 176 is provided, for example, in the channel, and is provided, for example, on an inner wall of the void 190 (liquid chamber) or an inner wall of the nozzle hole 150. By including the ink liquid contact film 176, elution of various materials due to ink contact, deterioration in adhesion between the materials, and the like can be prevented.
As the ink liquid contact film 176, for example, a metal oxide film such as TaOx and HfOx having high liquid contact resistance (ink resistance) can be used. As the ink liquid contact film 176, in addition to the above, a laminated film or a mixed film of the above-described metal oxide film and the silicon oxide film (SiOx) can be used. In order to enable smooth ink introduction into the ink channel, a material having high lyophilic property (ink-philic property, hydrophilic property) is more appropriate, and using such laminated film or mixed film as the ink liquid contact film 176 enables smooth ink introduction. For the above-described reason, in the present example, a mixed film of Ta2O5 and SiO2 is formed on an entire surface of the actuator using an atomic layer deposition (ALD) method.
In a case of the nozzle plate vibration system as in the present embodiment, it is not essential to make the void 190 a closed space, and there also is an advantage that the device configuration and the method are simplified. For example, as illustrated in
In contrast, the closed space as in the conventional discharge system has an advantage that the ink introduction is facilitated using a capillary phenomenon. From this viewpoint, the nozzle plate vibration system might be disadvantageous in terms of ink introduction in some cases. In consideration of this, it might be preferable to use a lyophilic (ink-philic, hydrophilic) material as the ink liquid contact film 176.
In the present example, the nozzle water-repellent film 177 (water-repellent film) is provided on the surface on the side on which the liquid is discharged. By using the nozzle water-repellent film 177, water repellency of the surface on the droplet discharge side of the nozzle plate can be enhanced, and ink dischargeability is improved. By using the nozzle water-repellent film 177, ink retention and ink adhesion on the surface of the nozzle plate can be prevented.
As the nozzle water-repellent film 177, for example, a polymer material having high liquid repellent property (ink repellent property and water repellent property), such as perfluorodecyltrichlorosilane (FDTS) or fluorotetrahydrooctyldimethylchlorosilane (FOTS), can be used.
In this example, FOTS is uniformly formed on the surface of the nozzle plate using a (molecular vapor deposition) MVD method. There is a case where this film is formed on a portion other than the surface of the nozzle plate (for example, in the nozzle hole, in the ink liquid chamber), and measures for removing the same might be taken, but the detailed description thereof is omitted. Durability against a mechanical stress at the time of nozzle wiping (nozzle surface cleaning) is also required, so that it is also important to obtain strong adhesion with a base material.
As in the present example, the liquid discharge head using the ink liquid contact film 176 and the nozzle water-repellent film 177 has excellent ink filling property (introduction of ink into the ink channel) and excellent ink liquid contact durability. This also has stable and excellent ink discharge characteristics, and maintains cleanliness of the surface of the nozzle plate and has high durability. In this example, the liquid discharge head of a higher quality can be obtained.
Next, the method of manufacturing the piezoelectric device and a method of manufacturing the liquid discharge head of the present embodiment will be described. A method of manufacturing a piezoelectric device according to the present embodiment includes
In the conventional manufacturing method, when the CMOS element and the piezoelectric element are formed on the same substrate, wiring (for example, metal wiring and interlayer insulating film) to the CMOS element has been damaged when forming the piezoelectric element, and the CMOS operation has not been normally performed. When the piezoelectric element is formed after the CMOS element is formed, it is considered to be required to form the piezoelectric element at the formation temperature of, for example, 500° C. or lower in order to avoid damage to the wiring to the CMOS element. However, it was found that, when the piezoelectric element was formed at such formation temperature, the piezoelectric characteristics were significantly deteriorated, and the droplet discharge operation could not be performed even by the nozzle plate vibration system.
In the present embodiment, after the CMOS element is formed on the substrate on which the nozzle hole for droplet discharge is formed, the piezoelectric element and the wiring are created in an appropriate order under an appropriate condition. As a result, it is possible to obtain the piezoelectric device including the CMOS element and the piezoelectric element on the same substrate and achieving both the CMOS operation and the excellent piezoelectric characteristics.
According to the present embodiment, it is possible to provide the liquid discharge head having advantages of a piezoelectric system such as high output (high viscosity, large droplets), high degree of freedom in ink, and high driving durability, and advantages of a thermal system such as small size, high density, and low cost.
When the CMOS element and the piezoelectric element are formed on the same substrate, it is required to consider the viewpoint of step management to avoid contamination of a semiconductor manufacturing line with heavy metals, alkalis, and the like. Therefore, it is required to first form the CMOS element and then form the piezoelectric element. In consideration of the above, the CMOS element forming step is performed first, and the piezoelectric element forming step is performed later.
When the piezoelectric element is formed on the same substrate as the CMOS element, it is required to form the piezoelectric element at temperature lower than the formation temperature of the CMOS element in order to secure various characteristics of the CMOS element. The piezoelectric element such as a PZT thin film element is usually formed at temperature of about 850° C. When this is formed at temperature lower than the formation temperature of the CMOS element, for example, 750° C., the piezoelectric characteristics (piezoelectric constant, piezoelectric displacement amount, and driving force) are significantly deteriorated.
In general, when manufacturing a CMOS integrated functional device, the wiring to the CMOS element is formed, and then a portion of the functional device is manufactured. However, the wiring to the CMOS is usually manufactured at temperature of about 300° C. to 400° C. in many cases, and is at most about 500° C. or lower. Therefore, when the piezoelectric element is formed after the wiring to the CMOS element is formed, the wiring is damaged, and the functional device cannot perform the CMOS operation.
Although it varies depending on the material of the wiring to the CMOS element, the material of the interlayer insulating film, and the manufacturing method thereof, the wiring to the CMOS element is usually manufactured at around 350° C. in many cases. Therefore, when the piezoelectric element is formed after the wiring is formed, the piezoelectric element needs to be subjected to heat treatment with a light load of about 500° C. or lower in order to prevent elution or disconnection of the wiring, cracking or dielectric breakdown of the interlayer insulating film, and the like. However, when the piezoelectric element is manufactured at low temperature, the excellent piezoelectric characteristics cannot be obtained.
Therefore, in the present embodiment, by performing the wiring layer forming step after the piezoelectric element forming step, the formation temperature region of the piezoelectric body can be made higher than the formation temperature at the wiring layer forming step and the step can be performed in a temperature region lower than that at the CMOS element forming step. For this reason, the wiring layer forming step is performed after the piezoelectric element forming step.
In the manufacturing method of the present embodiment, it is preferable to appropriately adjust the relationship between the formation temperature at the CMOS element forming step and the formation temperature at the piezoelectric element forming step.
A design rule and a manufacturing process of the CMOS element significantly differ depending on a requirement of a desired circuit. A final high-temperature heating step (for example, heat treatment for impurity diffusion) in the CMOS operation, particularly the CMOS element forming step that affects the threshold voltage, is conventionally performed with a heat history at 900° C. for 30 minutes or longer in many cases. After the CMOS element is formed, if a heat history of the same degree or greater than this is applied, the CMOS element is difficult to maintain the various characteristics. For example, the threshold voltage of the CMOS element significantly deviates from a specification value, and the circuit no longer operates. In consideration of the above, the formation temperature of the piezoelectric element is also studied.
For example, at the piezoelectric element forming step, it is preferable to form the piezoelectric element at temperature lower than the temperature of the final high-temperature heat treatment out of the high-temperature heat treatments for forming the CMOS element. By doing so, deterioration in CMOS element can be prevented.
The final high-temperature heat treatment out of the high-temperature heat treatments for forming the CMOS element can be appropriately selected, and examples thereof include, for example, the final high-temperature heat treatment that affects a CMOS characteristic value (threshold voltage and the like) and the final high-temperature heat treatment that adjusts the CMOS characteristic value (threshold voltage and the like). In addition, the final high-temperature heat treatment out of the high-temperature heat treatments for forming the CMOS element includes a heat treatment for impurity diffusion when forming NMOS or PMOS source electrode and drain electrode in the CMOS element.
Examples of the final high-temperature heat treatment out of the high-temperature heat treatments for forming the CMOS element include, for example, a heat treatment for impurity diffusion when forming NMOS or PMOS source electrode and drain electrode in the CMOS element. Therefore, in the piezoelectric element forming step, it is preferable to form the piezoelectric element at temperature lower than the temperature of the heat treatment for impurity diffusion at the time of forming the NMOS or PMOS source electrode and drain electrode in the CMOS element. By doing so, deterioration in CMOS element can be prevented.
At the piezoelectric element forming step, it is more preferable to form the piezoelectric element at temperature lower by 100° C. or more than the temperature of the final high-temperature heat treatment (for example, the heat treatment for impurity diffusion) performed at the CMOS element forming step. In this case, it is possible to further reliably prevent the operation of the CMOS element from becoming defective.
The CMOS element is usually formed at 900° C. or higher in many cases. When the same degree of heat history is added after the CMOS is formed, CMOS characteristics change (deteriorate). A particularly large influence is a change in threshold voltage. As a result of studies, it was found that, when the piezoelectric element was formed at 750° C. or lower after the CMOS element was formed, this threshold voltage hardly changed. In a case of temperature lower by about 100° C. than the formation temperature of the CMOS element, for example, 800° C., the threshold voltage slightly changed, but it was also found that the operation was generally performed.
For this reason, as described above, it is more preferable to form the piezoelectric element at temperature lower by 100° C. or more than the temperature of the final high-temperature heat treatment (for example, the heat treatment for impurity diffusion) performed at the CMOS element forming step, it is more preferable to form the piezoelectric element at 750° C. or lower, and it is still more preferable to form the piezoelectric element at temperature of 800° C. or lower. By doing so, the CMOS operation can be prevented from becoming defective.
At the piezoelectric element forming step, it is more preferable to form the piezoelectric element at temperature of 500° C. or higher. In this case, it is possible to prevent the piezoelectric characteristics from becoming defective. At the piezoelectric element forming step, it is still more preferable to form the piezoelectric element at temperature of 500° C. or higher and 800° C. or lower. In this case, the CMOS operation can be prevented from being defective, and the piezoelectric characteristics can be prevented from being defective.
First, the CMOS element forming step is performed (S100). As a next step, there is an option of forming the piezoelectric element before or after the wiring layer (S201). When the piezoelectric element is formed before the wiring layer, this is an example included in the present embodiment.
When the piezoelectric element is formed before the wiring layer, the formation temperature of the piezoelectric element is appropriately adjusted. When the formation temperature of the piezoelectric element is 800° C. or lower (YES at S202) and 500° C. or higher (YES at S203), the liquid discharge head obtained by a piezoelectric element forming step A (S110a) and a wiring layer forming step (S120) can achieve both the CMOS operation and the droplet discharge operation at a high level. This is (a) a preferred example.
When the formation temperature of the piezoelectric element is higher than 800° C. (No at S202), the liquid discharge head obtained by a piezoelectric element forming step B (S110b) and the wiring layer forming step (S120) can achieve both the CMOS operation and the droplet discharge operation, but the CMOS operation is deteriorated. This is (b) a poor example. When the formation temperature of the piezoelectric element is higher than 800° C., it is considered that the CMOS element is affected.
When the formation temperature of the piezoelectric element is lower than 500° C. (No at S203), the liquid discharge head obtained by a piezoelectric element forming step C (S110c) and the wiring layer forming step (S120) can achieve both the CMOS operation and the droplet discharge operation, but the liquid discharge operation is deteriorated. This is (c) a poor example. When the formation temperature of the piezoelectric element is lower than 500° C., it is considered that the piezoelectric element cannot be sufficiently heated, and the droplet discharge operation is affected.
In a case of NO at S201, that is, when the wiring layer is formed before the piezoelectric element as in the conventional technology, this is a comparative example not included in the present embodiment. In this case, after the CMOS element is formed, the wiring to the CMOS element is formed (S210). Thereafter, the piezoelectric element is formed; when the formation temperature of the piezoelectric element is 500° C. or lower (YES at S205), the liquid discharge head obtained by a piezoelectric element forming step D (S110d) and a wiring layer forming step of the piezoelectric element (S220) has a defective droplet discharge operation (d). This is because the formation temperature of the piezoelectric element is low, so that the piezoelectric element that can obtain the excellent droplet discharge operation cannot be formed.
In a case of NO at S201, when the formation temperature of the piezoelectric element is higher than 500° C. (in a case of NO at S205), the CMOS operation of the liquid discharge head obtained by a piezoelectric element forming step E (S110e) and the wiring layer forming step of the piezoelectric element (S220) is defective (e). This is because the formation temperature of the piezoelectric element is high, so that the CMOS element is deteriorated.
In the drawings, the piezoelectric element forming steps A to E perform the same process except that the formation temperature of the piezoelectric element is different. At the wiring layer forming step (S120) in the drawing, wiring to the CMOS element and wiring of the piezoelectric element are formed.
In the manufacturing method of the present embodiment, the first insulating film 171 is formed in a region where the piezoelectric element 160 is formed, and the lower electrode layer 161, the piezoelectric layer 162, the upper electrode layer 163, and the second insulating film 172 are formed on the first insulating film 171. As described above, since the CMOS element forming step, the piezoelectric element forming step, the wiring layer forming step, and the void forming step are performed in this order, the thickness of the first insulating film 171 (lower insulating film) under the piezoelectric layer 162 is thinner than the thickness of the second insulating film 172 (upper insulating film) above the piezoelectric layer 162.
The step of forming the first insulating film 171 may be included in the CMOS element forming step or the piezoelectric element forming step. In addition, the step of forming the first insulating film 171 may be separated as an insulating film forming step and the like. The step of forming the second insulating film 172 is herein included in the piezoelectric element forming step, but there is no limitation, and the step of forming the second insulating film 172 may be separated as an insulating film forming step or the like.
At the piezoelectric element forming step, a method of forming the piezoelectric layer can be appropriately selected, and examples thereof include, for example, a sol-gel method, a sputtering method, and a chemical vapor deposition (CVD) method.
For example, when a PZT piezoelectric element is formed by the sol-gel method, this is usually formed by sintering at temperature of about 850° C., but when this is formed at 750° C. or lower, piezoelectric characteristics might be deteriorated in some cases. However, in a case of the nozzle plate vibration system, sufficient droplet discharge characteristics can be obtained. Even in a case of forming by the sputtering method or the CVD method, when the formation temperature is lowered, deterioration in piezoelectric characteristics is expected; however, in a case of the nozzle plate vibration system, sufficient droplet discharge characteristics are obtained.
The method of manufacturing the piezoelectric device according to the present embodiment may include a step of forming the through hole that penetrates the piezoelectric element 160 and communicates with the void 190. The step of forming the through hole can be performed, for example, at the void forming step. The formed through hole can be made the nozzle hole 150 in a case where the piezoelectric device is applied to the liquid discharge head.
By forming the nozzle hole 150 that penetrates the piezoelectric element 160, the piezoelectric element 160 is formed around the nozzle hole 150. As a result, the nozzle plate vibration system liquid discharge head can be obtained.
After the void forming step, a liquid contact film and water-repellent film forming step of forming a liquid contact film at a site in contact with the liquid of the substrate, and a water-repellent film on a surface on a side on which the liquid is discharged may be performed. As a result, the liquid discharge head illustrated in
Example of Method of Manufacturing Piezoelectric Device and Method of Manufacturing Liquid Discharge Head Hereinafter, an example of the method of manufacturing the piezoelectric device and the method of manufacturing the liquid discharge head will be described with reference to
First, an active region in which the CMOS element is arranged is formed.
The CMOS is formed of the combination of the NMOS and PMOS, but only the PMOS is illustrated in the drawing, and that related to the NMOS is omitted for convenience. This step is not particularly limited, but is performed with a heat history at about 900° C. or higher, for example, and is usually performed at 1000° C. or higher in many cases.
Therefore, important CMOS characteristics (CMOS operation) such as the threshold voltage are designed in consideration of the heat history up to the step of
As the first insulating film 171, a silicon oxide film by a CVD method is generally used. A silicon nitride film having high moisture resistance is also often used as an alternative layer or an additional layer. In the present embodiment, there is no limitation, and other examples can be used as appropriate.
The gate electrode 114 is illustrated as an activated impurity diffusion region. The channel region 118 is subjected to threshold voltage matching.
In
As the first insulating film 171, for example, a laminated film of a silicon oxide film and a silicon nitride film can be used. In the present embodiment, since the configuration of the insulating film can be appropriately selected, there is no limitation, and is illustrated in a simplified manner in the drawings.
As the second insulating film 172, for example, a silicon oxide film can be used, but there is no limitation. The first insulating film 171 may be referred to as a lower insulating film because this is provided on a lower side of the piezoelectric element 160, and the second insulating film 172 may be referred to as an upper insulating film because this is provided on an upper side of the piezoelectric element 160.
In this example, the metal wiring 135 includes two layers, but the present embodiment is not limited thereto. An appropriate CMOS process design rule may be appropriately applied to the number of layers of wiring and the process according to a specification of a desired CMOS component. In this example, the laminated film of the silicon oxide film and the silicon nitride film is used as the uppermost interlayer insulating film.
As described above, the CMOS element and the piezoelectric element can be formed on the same substrate. In the state illustrated in
The second insulating film 172 is the upper insulating film on the upper side of the piezoelectric element 160. The second insulating film 172 may have a laminated structure. For example, when the protective insulating film of the piezoelectric element and the interlayer insulating film are made of different materials, it can be said that the second insulating film 172 has the laminated structure. In this case, the second insulating film 172 includes the protective insulating film of the piezoelectric element and the interlayer insulating film.
The diaphragm (vibration region 181) is formed of, for example, the first insulating film 171, the piezoelectric element 160, and the second insulating film 172. The diaphragm may further include a resin film (nozzle water-repellent film, ink liquid-repellent film, and the like) and the like thereon. In order to obtain desired vibration characteristics, the film thickness, rigidity, film stress, dimensions (for example, the width of the diaphragm and the like) and the like of each layer are preferably formed precisely in advance to be designed and manufactured.
Next, a liquid discharge device and a liquid discharge apparatus (liquid discharge apparatus) according to the present embodiment will be described. An example of the liquid discharge apparatus according to the present embodiment will be described with reference to
The liquid discharge apparatus is a serial type apparatus, and a carriage 403 reciprocally moves in a main scanning direction by a main scan moving unit 493. The main scan moving unit 493 includes a guide 401, a main scan motor 405, a timing belt 408, and the like. The guide 401 is bridged between a left side plate 491A and a right side plate 491B to moveably hold the carriage 403. The main scan motor 405 reciprocally moves the carriage 403 in the main scanning direction via the timing belt 408 bridged between a drive pulley 406 and a driven pulley 407.
The carriage 403 mounts the liquid discharge device 440. A head 404 according to the present embodiment and a head tank 441 form the liquid discharge device 440 as a single unit. The head 404 of the liquid discharge device 440 discharges liquid of each color, for example, yellow (Y), cyan (C), magenta (M), and black (K). The head 404 includes a nozzle array including multiple nozzles 11 arrayed in row in a sub scanning direction perpendicular to the main scanning direction. The head 404 is mounted to the carriage 403 so that ink droplets are discharged downward.
The liquids stored in liquid cartridges 450 are supplied to the head tank 441 by a supply unit 494 to supply the liquids stored outside the head 404 to the head 404.
The supply unit 494 includes a cartridge holder 451 serving as a filling part to mount the liquid cartridges 450, a tube 456, a liquid feeder 452 including a liquid feed pump, and the like. The liquid cartridge 450 is detachably attached to the cartridge holder 451. The liquid is fed from the liquid cartridge 450 to the head tank 441 by the liquid feeder 452 via the tube 456.
The liquid discharge apparatus includes a conveyor 495 to convey a sheet 410. The conveyor 495 includes a conveyance belt 412 as a conveyor and a sub scan motor 416 to drive the conveyance belt 412.
The conveyance belt 412 attracts the sheet 410 and conveys the sheet 410 to a position facing the head 404. The conveyance belt 412 is an endless belt stretched between a conveyance roller 413 and a tension roller 414. Attraction of the sheet 410 to the conveyance belt 412 may be applied by electrostatic adsorption, air suction, or the like.
The conveyance belt 412 rotates in the sub scanning direction as the conveyance roller 413 is rotationally driven by the sub scan motor 416 via the timing belt 417 and the timing pulley 418.
At one side in the main scanning direction of the carriage 403, a maintenance unit 420 to maintain the head 404 in good condition is disposed on a lateral side of the conveyance belt 412.
The maintenance unit 420 includes, for example, a cap 421 to cap a nozzle face of the head 404 and a wiper 422 to wipe the nozzle face. The nozzle face is a surface of the head 404 on which the multiple nozzles 11 are formed.
The main scan moving unit 493, the supply unit 494, the maintenance unit 420, and the conveyor 495 are mounted to a housing that includes the side plate 491A, the side plate 491B, and a rear-side plate 491C.
In the liquid discharge apparatus thus configured, the sheet 410 is conveyed on and attracted to the conveyance belt 412 and is conveyed in the sub scanning direction by the cyclic rotation of the conveyance belt 412.
The head 404 is driven in response to image signals while the carriage 403 moves in the main scanning direction, to discharge a liquid to the sheet 410 stopped, thus forming an image on the sheet 410.
In this manner, since this apparatus includes the liquid discharge head according to the present embodiment, a high-quality image can be stably formed.
Next, another example of the liquid discharge device 440 according to the present embodiment is described with reference to
The liquid discharge device 440 includes a housing, the main scan moving unit 493, the carriage 403, and the head 404 among components of the liquid discharge apparatus. The side plate 491A, the side plate 491B, and the rear-side plate 491C configure the housing.
The liquid discharge device 440 may be configured to further attach at least one of the above-described maintenance unit 420 and the supply unit 494 to, for example, the side plate 491B of the liquid discharge device 440.
Next, still another example of the liquid discharge device 440 according to the present embodiment is described with reference to
The liquid discharge device 440 includes the head 404 to which a channel part 444 is attached and a tube 456 connected to the channel part 444.
The channel part 444 is disposed inside a cover 442. Instead of the channel part 444, the liquid discharge device 440 may include the head tank 441. A connector 443 electrically connected with the head 404 is provided on an upper part of the channel part 444.
In the above-described embodiments, the “liquid discharge apparatus” includes the head or the liquid discharge device and drives the head to discharge a liquid. The liquid discharge apparatus may be, for example, an apparatus capable of discharging a liquid to a material to which liquid can adhere or an apparatus to discharge liquid toward gas or into liquid.
The liquid discharge apparatus may include devices to feed, convey, and eject the material on which liquid can adhere. The liquid discharge apparatus may further include a pretreatment apparatus to coat a treatment liquid onto the material, and a post-treatment apparatus to coat a treatment liquid onto the material, onto which the liquid has been discharged.
The “liquid discharge apparatus” may be, for example, an image forming apparatus to form an image on a sheet by discharging ink, or a three-dimensional fabrication apparatus to discharge a fabrication liquid to a powder layer in which powder material is formed in layers to form a three-dimensional fabrication object.
The liquid discharge apparatus is not limited to an apparatus to discharge liquid to visualize meaningful images, such as letters or figures. For example, the liquid discharge apparatus may be an apparatus to form meaningless images, such as meaningless patterns, or fabricate three-dimensional images.
The above-described term “material onto which liquid can adhere” represents a material on which liquid is at least temporarily adhered, a material on which liquid is adhered and fixed, or a material into which liquid is adhered to permeate. Examples of the “material on which liquid can adhere” include recording media, such as paper sheet, recording paper, recording sheet of paper, film, and cloth, electronic component, such as electronic substrate and piezoelectric element, and media, such as powder layer, organ model, and testing cell. The “material on which liquid can adhere” includes any material on which liquid can adhere, unless particularly limited.
Examples of the “material on which liquid can adhere” include any materials on which liquid can adhere even temporarily, such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramic, construction materials (e.g., wallpaper or floor material), and cloth textile.
Examples of the “liquid” include ink, treatment liquid, DNA sample, resist, pattern material, binder, fabrication liquid, and solution or liquid dispersion containing amino acid, protein, or calcium.
The “liquid discharge apparatus” may be an apparatus to relatively move the head and a material on which liquid can adhere. However, the liquid discharge apparatus is not limited to such an apparatus. For example, the liquid discharge apparatus may be a serial head apparatus that moves the head or a line head apparatus that does not move the head.
Examples of the “liquid discharge apparatus” further include a treatment liquid coating apparatus to discharge a treatment liquid to a sheet to coat the treatment liquid on the surface of the sheet to reform the sheet surface and an injection granulation apparatus in which a composition liquid including raw materials dispersed in a solution is injected through nozzles to granulate fine particles of the raw materials.
The “liquid discharge device” is an assembly of parts relating to liquid discharge. The term “liquid discharge device” represents a structure including the head and a functional part(s) or mechanism combined to the head to form a single unit. For example, the “liquid discharge device” includes a combination of the head with at least one of a head tank, a carriage, a supply unit, a maintenance unit, and a main scan moving unit to form a single unit.
Examples of the “single unit” include a combination in which the head and one or more functional parts and units are secured to each other through, e.g., fastening, bonding, or engaging, and a combination in which one of the head and the functional parts and units is movably held by another. The head may be detachably attached to the functional part(s) or unit(s) each other.
For example, as a liquid discharge device 440, there is a liquid discharge device in which the head 404 and the head tank 441 form a single unit, as in the liquid discharge device 440 illustrated in
In another example, the head and the carriage may form the liquid discharge device as a single unit.
In still another example, the liquid discharge device includes the head movably held by a guide that forms part of a main scan moving unit, so that the head and the main scan moving unit form a single unit. Like the liquid discharge device 440 illustrated in
In still another example, a cap that forms a part of the maintenance unit may be secured to the carriage mounting the head so that the head, the carriage, and the maintenance unit form a single unit to form the liquid discharge device.
Like the liquid discharge device 440 illustrated in
The main scan moving unit may be a guide only. The supply unit may be a tube(s) only or a loading unit only.
The pressure generator used in the “head” is not limited to a particular type of pressure generator. The pressure generator is not limited to the piezoelectric actuator (or a laminated-type piezoelectric element) described in the above-described embodiments, and may be, for example, a thermal actuator that employs a thermoelectric transducer element, such as a thermal resistor, or an electrostatic actuator including a diaphragm and opposed electrodes.
The terms “image formation”, “recording”, “printing”, “image printing”, and “fabricating” used herein may be used synonymously with each other.
Hereinafter, the present embodiment will be described more specifically with reference to examples, but the present embodiment is not limited to these examples.
The liquid discharge head illustrated in
As the piezoelectric layer, PZT formed by a sol-gel method was used. The formation temperature of the CMOS element was set to 850° C. and 900° C., and the evaluation was performed using the formation temperature of PZT as a parameter. The formation temperature of the CMOS element and the formation temperature of PZT are illustrated in Tables 1 and 2. Here, the formation temperature of the CMOS element is the temperature in the impurity diffusion heat treatment (
As illustrated in Tables 1 and 2, the liquid discharge heads of both the nozzle plate vibration system (
The evaluation was made on the operation of the CMOS element, the piezoelectric characteristics (displacement amount) of the piezoelectric element, the droplet discharge operation, and the compatibility of the CMOS operation and the discharge operation.
The evaluation of the operation of the CMOS element was determined based on whether the CMOS circuit normally operates in a case where both the CMOS circuit and the piezoelectric element are formed as in the present embodiment, as in a case where only the CMOS circuit is formed. Specific evaluation criteria are as follows.
The piezoelectric characteristics of the piezoelectric element were evaluated based on whether or not a desired diaphragm displacement amount was obtained at a predetermined applied voltage. The evaluation criteria are as follows.
The evaluation criteria are as follows.
The evaluation of the droplet discharge operation was determined by whether or not a predetermined ink droplet (amount) can obtain a desired or higher ink discharge speed at a predetermined applied voltage. The evaluation criteria are as follows.
The evaluation criteria are as follows.
According to the above results, for example, the following can be said.
Comparing Examples 1 to 4 with Comparative Examples 1 and 2, in a case where the CMOS element formation temperature is 850° C., when the piezoelectric element formation temperature is in a range of 500° C. to 750° C., by combining with the nozzle diaphragm system, it is possible to achieve both the CMOS operation and the droplet discharge operation. As in Examples 2 and 3, when the piezoelectric element formation temperature is in the range of 600° C. to 700° C., the compatibility between the CMOS operation and the droplet discharge operation is further improved.
Comparing Examples 5 to 9 with Comparative Example 3, in a case where the CMOS element formation temperature is 900° C., when the piezoelectric element formation temperature is in the range of 500° C. to 800° C., both the CMOS operation and the droplet discharge operation can be achieved by combining with the nozzle diaphragm system. As in Examples 7 and 8, when the piezoelectric element formation temperature is in the range of 600° C. to 750° C., the compatibility between the CMOS operation and the droplet discharge operation is further improved.
In Examples 4 and 9, the droplet discharge operation was low, and an applied voltage higher than a predetermined voltage was required, but since a stable compatible operation was achieved, it was regarded as acceptable.
The above-described Examples and Comparative Examples are examples of results when verifying the liquid discharge head. As described in the above-described embodiment, in the liquid discharge head of the present embodiment, it is essential that the formation temperature of the piezoelectric element satisfies a predetermined requirement and that the piezoelectric element is of the nozzle plate vibration system. In the liquid discharge heads obtained in Comparative Examples 1 to 5 and 10, the formation temperature of the piezoelectric element did not satisfy the predetermined requirement, and in the liquid discharge heads obtained in other Comparative Examples, since the conventional discharge system was adopted instead of the nozzle plate vibration system, it was not possible to achieve both the CMOS operation and the discharge operation.
It is considered that the tendency similar to that of the above-described liquid discharge head can be obtained when the piezoelectric device is verified. When the piezoelectric device is manufactured under the temperature condition similar to that in Comparative Examples 1 to 5 and 10 described above, the example included in the present embodiment is obtained and it is considered that both the CMOS operation and the piezoelectric characteristics can be achieved. However, the CMOS operation is at a level of barely acceptable, and is inferior to that in other examples (for example, there is a site that does not operate).
Aspects of the present embodiment are, for example, as follows.
<1> A piezoelectric device including:
A device manufacturing method for manufacturing a piezoelectric device, the device manufacturing method includes:
In the device manufacturing method according to aspect 1, the forming the first insulating film forms the first insulating film to be thinner than the second insulating film, and the first insulating film is closer to the first surface of the substrate than the second insulating film.
The device manufacturing method according to aspect 1, further includes: heat treatment for impurity diffusion for forming a NMOS source electrode and a drain electrode or a PMOS source electrode and a drain electrode in the CMOS element at a first temperature,
In the device manufacturing method according to aspect 3, the second temperature is lower by 100° C. or more than the first temperature.
In the device manufacturing method according to aspect 4, the forming the piezoelectric element forms the piezoelectric element at the second temperature of 800° C. or lower.
In the device manufacturing method according to aspect 5, the forming the piezoelectric element forms the piezoelectric element at the second temperature of 500° C. or higher and 800° C. or lower.
In the device manufacturing method according to aspect 1, the forming the piezoelectric element using a sol-gel method, a sputtering method, or a chemical vapor deposition (CVD) method to form the piezoelectric layer.
The device manufacturing method according to aspect 1, further includes: forming a through hole penetrating through the piezoelectric element and communicating with the void after forming the void.
A head manufacturing method for manufacturing a liquid discharge head, the head manufacturing method includes: the device manufacturing method according to aspect 8; and forming the void in the substrate as a liquid chamber; forming the through hole as a nozzle hole from which a liquid in the liquid chamber is discharged.
The head manufacturing method according to aspect 9, further includes: forming a liquid contact film on an inner surface of the liquid chamber; and forming a water-repellent film on a nozzle surface on which the nozzle hole is formed.
A piezoelectric device comprising:
The piezoelectric device according to aspect 11 further includes: a through hole penetrating through the piezoelectric element and communicating with the void, wherein the piezoelectric element is around the through hole.
A liquid discharge head includes: the piezoelectric device according to aspect 12, wherein the void has a liquid chamber accommodating a liquid, and the through hole has a nozzle hole from which the liquid in the liquid chamber is discharged.
In the liquid discharge head according to aspect 13, wherein the substrate includes: a liquid contact film on an inner surface of the liquid chamber, and a water-repellent film on a nozzle surface on which the nozzle hole is formed.
A liquid discharge apparatus includes: the liquid discharge head according to aspect 13; and at least one of: a head tank storing a liquid to be supplied to the liquid discharge head; a carriage mounting the liquid discharge head; a supply unit configured to supply the liquid to the liquid discharge head; a maintenance unit configured to maintain the liquid discharge head; or a main scan moving unit configured to move the liquid discharge head in a main scanning direction, combined with the liquid discharge head to form a single unit.
The above-described embodiments are illustrative and do not limit the present invention. Thus, numerous additional modifications and variations are possible in light of the above teachings. For example, elements and/or features of different illustrative embodiments may be combined with each other and/or substituted for each other within the scope of the present invention. Any one of the above-described operations may be performed in various other ways, for example, in an order different from the one described above.
This patent application is based on and claims priority to Japanese Patent Application No. 2022-118758, filed on Jul. 26, 2022, in the Japan Patent Office, the entire disclosure of which is hereby incorporated by reference herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-118758 | Jul 2022 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2023/056938 | 7/5/2023 | WO |
