Patent Application
20210070048
The present invention relates to a liquid discharge head substrate, a method of manufacturing the same, a liquid discharge head, and a liquid discharge apparatus.
A liquid discharge head is widely used as a part of a printing apparatus that prints information such as characters or images on a sheet-shaped printing medium such as a sheet or a film. Japanese Patent Laid-Open No. 2016-137705 describes a method of forming a wiring structure on a semiconductor substrate where a circuit element is formed, and forming a heat generation element on the wiring structure, thereby forming a liquid discharge head substrate. The wiring structure includes a plurality of wiring layers, and its upper surface is planarized every time each wiring layer is formed.
PTL 1: Japanese Patent Laid-Open No. 2016-137705
In a liquid discharge head substrate, the liquid discharge characteristic of a heat generation element is determined by the thickness of an insulating layer between the heat generation element and a conductive member immediately below it. Heat dissipation from the heat generation element to the conductive member decreases if the thickness of this insulating layer is larger than a design value, making a liquid discharge amount larger than the design value. On the other hand, heat dissipation from the heat generation element to the conductive member increases if the thickness of this insulating layer is smaller than the design value, making the liquid discharge amount smaller than the design value. In a manufacturing method described in Japanese Patent Laid-Open No. 2016-137705, the heat generation element is formed on the uppermost wiring layer. An upper surface is planarized each time a wiring layer is formed, and thus an upper wiring layer has lower flatness. It is therefore difficult to form the liquid discharge head substrate such that the thickness of the insulating layer between the heat generation element and the conductive member immediately below it conforms to the design value over an entire wafer, making it impossible to improve performance of the liquid discharge head substrate sufficiently. An aspect of the present invention provides a technique for improving the performance of the liquid discharge head substrate.
According to some embodiments, a method of manufacturing a liquid discharge head substrate is provided. The method includes forming a first substrate that includes a semiconductor element and a first wiring structure; forming a second substrate that includes a liquid discharge element and a second wiring structure; and bonding the first wiring structure and the second wiring structure such that the semiconductor element and the liquid discharge element are electrically connected to each other after the forming the first substrate and the second substrate.
Further features of the present invention will become apparent from the following description of exemplary embodiments (with reference to the attached drawings).
Embodiments of the present invention will now be described with reference to the accompanying drawings. The same reference numerals denote the same elements throughout various embodiments, and a repetitive description thereof will be omitted. The embodiments can appropriately be changed or combined. A liquid discharge head substrate will simply be referred to as a discharge substrate hereinafter. The discharge substrate is used for a liquid discharge apparatus such as a copying machine, a facsimile apparatus, or a word processor. In the embodiments below, a heat generation element is treated as an example of a liquid discharge element of a discharge substrate. The liquid discharge element may be an element such as a piezoelectric element or the like capable of applying energy to a liquid.
An example of the arrangement of a discharge substrate 100 according to the first embodiment will be described with reference to
The discharge substrate 100 includes a base 110, a wiring structure 120, a heat generation element 130, a protective film 140, an anti-cavitation film 150, and a nozzle structure 160. The base 110 is, for example, a semiconductor layer of silicon or the like. A semiconductor element 111 such as a transistor and an element isolation region 112 such as LOCOS or STI are formed in the base 110.
The wiring structure 120 is positioned on the base 110. Using a flat bonding surface 121 as a boundary, the wiring structure 120 is divided into a wiring structure 120a below the bonding surface 121 and a wiring structure 120b above the bonding surface 121. The wiring structure 120a includes an insulating member 122 and conductive members 123 to 125 of a plurality of layers inside the insulating member 122. The conductive members 123 to 125 of the plurality of layers are stacked. The conductive member 123 of a layer closest to the base 110 is connected, by plugs, to the semiconductor element 111 and the like formed in the base 110. The conductive members positioned in adjacent layers of the plurality of layers are connected to each other by plugs.
The wiring structure 120b includes an insulating member 126, and conductive members 127 and 128 of a plurality of layers inside the insulating member 126. The conductive members 127 and 128 of the plurality of layers are stacked. The conductive member 128 of a layer farthest from the base 110 is connected to the heat generation element 130 by a plug. The conductive member 127 and the conductive member 128 are connected to each other by a plug.
Each of the conductive members 123 to 125, 127, and 128 may partially include a dummy pattern. The dummy pattern is a conductive pattern which is not electrically connected to the semiconductor element 111 and does not contribute to signal transfer or power supply. Each of the conductive members 123 to 125, 127, and 128 may be formed by a barrier metal layer and a metal layer. The barrier metal layer is formed by, for example, tantalum, a tantalum compound, titanium, or a titanium compound and suppresses diffusion or interaction of a material included in the metal layer. The metal layer is formed by copper or an aluminum compound and is lower than the barrier metal layer in resistance.
As shown in
The heat generation element 130 is positioned in the upper part of the wiring structure 120. The side surfaces of the heat generation element 130 contact the insulating member 126. The upper surface of the heat generation element 130 is on the same plane as the upper surface of the wiring structure 120, that is, the upper surface of the insulating member 126. The semiconductor element 111 and the heat generation element 130 are electrically connected to each other by the wiring structure 120 (more specifically, by the conductive members included in the wiring structure 120). The heat generation element 130 is formed by, for example, tantalum or a tantalum compound. Instead of this, the heat generation element 130 may be formed by polysilicon or tungsten silicide.
The conductive member 128 of a layer closest to the heat generation element 130 out of the conductive members 123 to 125, 127, and 128 of the plurality of layers includes a conductive portion immediately below the heat generation element 130. The liquid discharge characteristic of the heat generation element 130 is determined by the thickness of a region 126a of the insulating member 126 between this conductive portion and the heat generation element 130. Heat dissipation from the heat generation element 130 to the conductive members decreases if the thickness of this insulating layer is larger than a design value, making a liquid discharge amount larger than the design value. On the other hand, heat dissipation from the heat generation element 130 to the conductive members increases if the thickness of this insulating layer is smaller than the design value, making the liquid discharge amount smaller than the design value. The region 126a can also be referred to as a heat accumulation region.
The protective film 140 is positioned on the wiring structure 120 and the heat generation element 130. The protective film 140 covers at least the upper surface of the heat generation element 130 and also covers the upper surface of the wiring structure 120 in this embodiment. The protective film 140 is made of, for example, SiO, SiON, SiOC, SiC, or SiN and protects the heat generation element 130 from liquid erosion. In this embodiment, the both surfaces of the protective film 140, that is, the surface on the side of the heat generation element 130 and the surface opposite to it are flat. It is therefore possible to sufficiently ensure the coverage of the heat generation element 130 even if the protective film 140 is thin, as compared with a case in which the protective film has a step. Energy transfer efficiency to a liquid improves by thinning the protective film 140, making it possible to implement both a reduction in power consumption and an improvement in image quality by stabilizing foaming.
The anti-cavitation film 150 is positioned on the protective film 140. The anti-cavitation film 150 covers the heat generation element 130 across the protective film 140. The anti-cavitation film 150 is formed by, for example, tantalum, and protects the heat generation element 130 and the protective film 140 from a physical shock at the time of liquid discharge.
The nozzle structure 160 is positioned on the protective film 140 and the anti-cavitation film 150. The nozzle structure 160 includes an adherence layer 161, a nozzle member 162, and a water-repellent material 163. A channel 164 and an orifice 165 of a discharged liquid are formed in the nozzle structure 160.
Then, a method of manufacturing the discharge substrate 100 will be described with reference to
Subsequently, a structure shown in
Subsequently, a structure shown in
Subsequently, a structure shown in
Subsequently, a structure shown in
The substrate 200 is formed as described above. In this embodiment, the substrate 200 includes the conductive members 123 to 125 of three layers. However, the number of layers of the conductive members is not limited to this, and it may be one, two, or four or more. In addition, each conductive member may have a single damascene structure or a dual damascene structure. The wiring structure of the substrate 200 becomes the wiring structure 120a of the discharge substrate 100. The insulating member 122 of the wiring structure 120a is formed by the insulating layers 201, 203, 204, and 205. The upper surface of the substrate 200 (a surface on the side opposite to the base 110) is flat.
The upper limit value of a temperature at which metal materials of the plug 202, the conductive members 123, 124, and 125, and the like included in the wiring structure 120a are not influenced by melting or the like will be referred to as a critical temperature. The critical temperature can change depending on the type of metal material and may be, for example, 400° C., 450° C., or 500° C. The substrate 200 is formed such that the highest temperature in thermal histories received by the metal materials included in the wiring structure 120a during the manufacture of the substrate 200 becomes lower than the critical temperature (for example, lower than 400° C., lower than 450° C., or lower than 500° C.).
The thermal history about a certain portion of a semiconductor device means a temperature transition of the portion in a manufacturing step of the semiconductor device including a time when the portion is formed. For example, a certain member is formed at a substrate temperature of 400° C., and then a substrate including the portion is processed at a substrate temperature of 350° C. In this case, the portion has a thermal history of 400° C. and 350° C.
Then, as shown in
The protective film 140 is formed by, for example, a silicon insulator of silicon dioxide, silicon nitride, silicon carbide, or the like. The protective film 140 may be annealed at a high temperature in order to improve the humidity resistance of the protective film 140. In general, the insulator improves in humidity resistance as a temperature used for annealing is high. A wiring structure has not been formed yet at this point, and thus it is possible to anneal the protective film 140 at a temperature equal to or higher than the critical temperature (for example, 400° C. or higher, 450° C. or higher, or 500° C. or higher, and more specifically, 650° C.). Before the heat generation element 130 is formed, the upper surface of the protective film 140 may be planarized by the CMP method or the like. Instead of annealing, plasma processing may be performed on the heat generation element 130. In this embodiment, the humidity resistance of the protective film 140 is high, increasing the life of the discharge substrate 100.
The heat generation element 130 is formed by, for example, tantalum or a tantalum compound. The heat generation element 130 may be annealed at the temperature equal to or higher than the critical temperature (for example, 400° C. or higher, 450° C. or higher, or 500° C. or higher, and more specifically, 650° C.). This makes it possible to improve the resistance value of the heat generation element 130 and save power of the discharge substrate 100. The heat generation element 130 crystalizes by annealing the heat generation element 130 at the temperature equal to or higher than the critical temperature, making it possible to stabilize the initial characteristic of the heat generation element 130. The heat generation element 130 may be formed by polysilicon higher than tantalum or the tantalum compound in resistance. A high-temperature process is needed in order to form the heat generation element 130 by polysilicon. It is possible, however, to form the heat generation element 130 at the temperature equal to or higher than the critical temperature as described above. In addition, it is possible to select a material that cannot be used at a temperature lower than the critical temperature as a material of the heat generation element 130.
A wiring conductive member may be formed in the same layer as the heat generation element 130. In this case, the heat generation element 130 may not be annealed at the temperature equal to or higher than the critical temperature. The protective film 140 and the heat generation element 130 may be annealed separately or simultaneously. At least one of the protective film 140 and the heat generation element 130 is annealed at the temperature equal to or higher than the critical temperature.
Subsequently, a structure shown in
Subsequently, as shown in
Subsequently, as shown in
The substrate 300 is formed as described above. In this embodiment, the substrate 300 includes the conductive members of two layers. However, the number of layers of the conductive members is not limited to this, and it may be one, or three or more. In addition, each conductive member may have a single damascene structure or a dual damascene structure. The wiring structure of the substrate 300 becomes the wiring structure 120b of the discharge substrate 100. The insulating member 126 of the wiring structure 120b is formed by the insulating layers 302, 304, and 306. The upper surface of the substrate 300 (a surface on the side opposite to the base 301) is flat.
The substrate 300 is formed such that the highest temperature in a thermal history received by the heat generation element 130 or the protective film 140 becomes equal to or higher than the critical temperature, and the highest temperature in thermal histories received by metal materials included in the wiring structure 120b during the manufacture of the substrate 300 becomes lower than the critical temperature. The metal materials included in the wiring structure 120b are, for example, the plugs 303 and 305, and the conductive members 127 and 128.
In a manufacturing method of forming a wiring structure on a base that includes a semiconductor element and forming a heat generation element thereon, the heat generation element is formed on the uppermost wiring layer. An upper surface is planarized each time a wiring layer is formed, and thus an upper wiring layer has lower flatness. In contrast, in the above-described method of manufacturing the substrate 300, the insulating layer 302 in which the insulating member 126 is closest to the protective film 140 and the heat generation element 130 is formed prior to other insulating layers of the wiring structure 120, and thus the flatness of this insulating layer 302 is high. As a result, it becomes easier to form the substrate 300 such that the thickness of the region 126a in the insulating layer 302 conforms to a design value over an entire wafer, improving discharge performance of the heat generation element 130.
Then, as shown in
Subsequently, the entire base 301 is removed as shown in
The respective steps of the above-described manufacturing method may be performed by a single manufacturer or a plurality of manufacturers. The substrate 200 and the substrate 300 may be bonded to each other after, for example, one manufacturer forms the substrate 200 and the substrate 300, and another manufacturer prepares the substrate 200 and the substrate 300 by purchasing them. Instead of this, one manufacturer may form the substrate 200 and the substrate 300, and then this manufacturer may instruct another manufacturer to bond them.
An example of the arrangement of a discharge substrate 500 and a manufacturing method thereof according to the second embodiment will be described with reference to
Subsequently, as shown in
The discharge substrate 500 shown in
An example of the arrangement of a discharge substrate 600 according to the third embodiment will be described with reference to
An example of the arrangement of a discharge substrate 700 and a manufacturing method thereof according to the fourth embodiment will be described with reference to
As in the first embodiment, as shown in
More specifically, as shown in
An example of the arrangement of a discharge substrate 800 and a manufacturing method thereof according to the fifth embodiment will be described with reference to
As shown in
The temperature sensor 801 is used to measure the temperature of the heat generation element 130 and detect whether ink is discharged correctly. The temperature sensor 801 is formed by a conductive material such as titanium or a titanium compound whose heat resistance change ratio is not high. The temperature sensor is positioned closer to the heat generation element 130 than a conductive member 128 of a layer closest to the heat generation element 130 out of a plurality of conductive members in a wiring structure 120.
Before the temperature sensor 801 is formed, the upper surface of the insulating layer 802 is planarized by CMP or the like. Heat of the heat generation element 130 is transferred to the temperature sensor 801 via the insulating layer 802. It is therefore possible to improve the accuracy of the temperature sensor 801 by forming the thickness of the insulating layer 802 accurately. Another underlayer does not exist between the insulating layer 802 and the heat generation element 130, making it possible to form the insulating layer 802 having a uniform thickness accurately in a wafer surface. The temperature sensor 801 is formed before the conductive members in the wiring structure are formed, and thus the temperature sensor 801 may be annealed at a temperature equal to or higher than a critical temperature (for example, 400° C. or higher, 450° C. or higher, or 500° C. or higher).
An example of the arrangement of a discharge substrate 900 and a manufacturing method thereof according to the sixth embodiment will be described with reference to
As shown in
The discharge substrate 900 also includes the protective film 901 between the heat generation element 130 and a wiring structure 120, making it possible to suppress oxygen contained in the wiring structure 120 and a base 110 from being supplied to the heat generation element 130. This further suppresses oxidation of the heat generation element 130, implementing the long life of the discharge substrate 900.
An example of the arrangement of a discharge substrate 1200 and a manufacturing method thereof according to the seventh embodiment will be described with reference to
A method of manufacturing the discharge substrate 1200 will be described. As shown in
Then, as shown in
An example of the arrangement of a discharge substrate 1300 and a manufacturing method thereof according to the eighth embodiment will be described with reference to
A method of manufacturing the discharge substrate 1300 will be described below. As shown in
Subsequently, as shown in
The medium P is pressed by a paper press plate 1605 in the carriage moving direction and is fixed to a platen 1606. The liquid discharge apparatus 1600 reciprocates the liquid discharge head 1510 and performs liquid discharge (printing in this example) on the medium P conveyed on the platen 1606 by a conveyance unit (not shown).
The liquid discharge apparatus 1600 confirms the position of a lever 1609 provided on the carriage 1620 via photocouplers 1607 and 1608, and switches the rotational direction of the driving motor 1601. A support member 1610 supports a cap member 1611 for covering the nozzles (liquid orifices or simply orifices) of the liquid discharge head 1510. A suction unit 1612 performs recovery processing of the liquid discharge head 1510 by sucking the interior of the cap member 1611 via an intra-cap opening 1613. A lever 1617 is provided to start recovery processing by suction, and moves along with movement of a cam 1618 engaged with the carriage 1620. A driving force from the driving motor 1601 is controlled by a well-known transfer mechanism such as clutch switching.
A main body support plate 1616 supports a moving member 1615 and a cleaning blade 1614. The moving member 1615 moves the cleaning blade 1614, and performs recovery processing of the liquid discharge head 1510 by wiping. A control unit (not shown) is also provided in the liquid discharge apparatus 1600, and controls driving of each mechanism described above.
A liquid from the liquid supply path 1503 is stored in a common liquid chamber 1504, and supplied to each nozzle 1500 through the corresponding channel 1505. The liquid supplied to each nozzle 1500 is discharged from the nozzle 1500 in response to driving of the heater 1506 corresponding to the nozzle 1500.
The liquid discharge apparatus 1600 further includes a head driver 1705, motor drivers 1706 and 1707, a conveyance motor 1709, and a carrier motor 1710. The carrier motor 1710 conveys the liquid discharge head 1708. The conveyance motor 1709 conveys the medium P. The head driver 1705 drives the liquid discharge head 1708. The motor drivers 1706 and 1707 drive the conveyance motor 1709 and the carrier motor 1710, respectively.
When a driving signal is input to the interface 1700, it can be converted into liquid discharge data between the gate array 1704 and the MPU 1701. Each mechanism performs a desired operation in accordance with this data, thus driving the liquid discharge head 1708.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Applications No. 2017-028421, filed Feb. 17, 2017 and No. 2017-219330, filed Nov. 14, 2017, which are hereby incorporated by reference herein in their entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2017-028421 | Feb 2017 | JP | national |
| 2017-219330 | Nov 2017 | JP | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 16342097 | Apr 2019 | US |
| Child | 17100260 | US |
