Patent Application
20220016886
The present invention relates to a liquid ejection head that ejects liquid and a method for manufacturing the liquid ejection head.
There are liquid ejection heads that form liquid chambers by having an ejection port formation member in which ejection ports are formed provided on one surface of a liquid ejection head substrate provided with ejection elements (hereinafter referred to as an ejection element substrate) and that are configured to eject liquid in the liquid chambers from the ejection ports by driving the ejection elements. For use in a liquid ejection head of this type, there is known an ejection element substrate having an interlayer insulating film stacked on a silicon substrate to insulate components such as the ejection elements and electric wiring connected thereto. Supply ports and liquid channels to supply liquid to the liquid chambers are formed in the interlayer insulating film and the silicon substrate. Also, to suppress erosion by liquid, a liquid-resistant film may be formed on the face of the ejection element substrate that comes into contact with liquid. Depending on the type of the liquid such as ink, a silicon oxide (SiO) film used as an interlayer insulating film particularly has the risk of being eroded by liquid, and thus it is desirable that the surface of contact with liquid be covered with a liquid-resistant film.
Japanese Patent Laid-Open No. 2018-187789 discloses an ejection element substrate in which the surface of the interlayer insulating film of the ejection element substrate is covered with an insulating film that has a good adhesive property with respect to the ejection port formation member and in which the inner surfaces of the supply ports communicating with the ejection ports are covered with a liquid-resistant film using atomic layer deposition (ALD).
In the manufacturing of the ejection element substrate in Japanese Patent Laid-Open No. 2018-187789, an insulating film which is liquid-resistant and has an adhesive property with respect to the ejection port formation member is formed on the surface of the interlayer insulating film provided on the silicon substrate, and then, supply ports and liquid channels to communicate with the liquid chambers are formed. Next, using ALD, a liquid-resistant film such as a titanium oxide (TiO) film is formed on the insulating film and the inner surfaces of the supply flow channels. Further, the film on the region outside the supply ports is removed by etching. This etching is performed such that overlap portions between the film formed by ALD and the insulating film may be left by a width of several micrometers around the opening portions of the supply ports. The formation of the overlap portions makes it possible to help prevent liquid such as ink from intruding into the interlayer insulating film.
As described, the ejection element substrate disclosed in Japanese Patent Laid-Open No. 2018-187789 needs to have film overlaps formed around the supply ports as described earlier in order to help prevent intrusion of liquid into the interlayer insulating film. This calls for a large area around the supply ports, which may increase the overall area of the element substrate.
The present invention provides a liquid ejection head including a liquid ejection head substrate provided with an ejection element that generates energy for ejecting liquid, an ejection port formation member in which an ejection port through which to eject liquid is formed, and a liquid chamber which is formed between the liquid ejection head substrate and the ejection port formation member and houses liquid to be ejected through the ejection port, the liquid ejection head substrate comprising: a substrate; an insulating film stacked on the substrate to insulate the ejection element; a communication port formed in the substrate and the insulating film in such a manner as to communicate with the liquid chamber; and a liquid-resistant insulating film that has an adhesive property with respect to the ejection port formation member, covers a surface of the insulating film at a side where the ejection port formation member is provided, and includes a first portion which is partially in contact with the ejection port formation member and a second portion which covers an inner surface of the communication port formed in the insulating film, the first and second portion being provided in such a manner as to be continuous with each other.
The present invention can provide a reliable liquid ejection head capable of reducing erosion by liquid while suppressing upsizing.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
An embodiment of the present invention is described below with reference to the drawings. It should be noted, however, that the following description is not intended to limit the scope of the present invention.
As shown in
Liquid supply flow channels 18a and liquid collection flow channels 18b formed in the ejection element substrate 10 are flow channels extending in the ejection port row direction (the Y-direction). Each liquid supply flow channel 18a and each liquid collection flow channel 18b communicate with the pressure chambers 23 via individual supply ports 39a and individual collection ports 39b (see
The configuration of the ejection element substrate 10 according to the present embodiment is described below using
In the ejection element substrate 10, the individual supply port 39a and the individual collection port 39b are formed at both sides of the ejection elements 31 as communication ports communicating with the pressure chamber 23. The individual supply port 39a provided on one side of the ejection elements 31 communicates with the liquid supply flow channel 18a formed from the back surface side (the lower surface side in
The individual ports 39 each include an opening portion 391 formed in the interlayer insulating film 37 provided on the substrate 11 and an opening portion 392 formed in the substrate 11. These opening portions 391, 392 are each formed by dry etching performed from the front surface side of the substrate 11.
The ejection port formation member 12 made of resin is provided on the front surface of the ejection element substrate 10 in such a manner as to adhere to the front surface (the upper surface in
In the above liquid ejection head 1 having the ejection element substrate 10 and the ejection port formation member 12, the ejection element substrate 10 and the ejection port formation member 12 need to adhere to each other favorably. It is also necessary to reduce the risk of the interlayer insulating film 37 inside the individual ports 39 being eluted by coming into contact with liquid such as ink. Thus, the present embodiment is configured such that a liquid-resistant insulating film 38 (a coating film) continuously covers the surface of the ejection element substrate 10 and the inner surfaces of the individual ports 39 formed in the interlayer insulating film 37, except for portions above the ejection elements 31 and the electrode pad portions 16 (see
In the present embodiment, the liquid-resistant insulating film 38 is formed of silicon carbonitride (SiCN), silicon oxycarbonitride (SiOCN), silicon oxycarbide (SiOC), or a stack film thereof. Thus, the liquid-resistant insulating film 38 can protect the interlayer insulating film 37 from liquid, including ink. Furthermore, since SiCN, SiOCN, and SiOC exhibit a good adhesive property with respect to the ejection port formation member 12, the liquid-resistant insulating film 38 also functions as an adhesion improvement layer.
In the present embodiment, by containing a carbon atom C, the liquid-resistant insulating film 38 can have liquid resistance. From the perspective of liquid resistance, the liquid-resistant insulating film 38 preferably contains 5 at. % or greater carbon atoms C. It is also preferable that the liquid-resistant insulating film 38 has higher liquid resistance against liquid such as ink than the interlayer insulating film 37.
In the present embodiment, as long as the liquid-resistant insulating film 38 is a silicon compound such as, for example, SiCN, SiOCN, or SiOC, the liquid-resistant insulating film 38 can exhibit a good adhesive property with respect to the ejection port formation member 12, which is made of resin. Also, as to the adhesive property of the liquid-resistant insulating film 38, the liquid-resistant insulating film 38 is preferably joined to the ejection port formation member 12 more strongly than the interlayer insulating film 37 does.
Thus, the present embodiment can achieve a simpler manufacturing process than a comparative example to be described later, in which an adhesion improvement layer formed on the surface of an interlayer insulating film and a liquid-resistant film formed inside individual ports are formed separately. In the comparative example to be described later, an overlap portion which is an overlap between the liquid-resistant film and the adhesion improvement film needs to be formed around each individual port, which is a factor in increasing the distance between the individual port and the ejection element 31. By contrast, in the present embodiment, the liquid-resistant insulating film is continuously formed, and therefore the overlap portions formed in the comparative example are unnecessary. Thus, the present embodiment makes it possible to have a shorter distance between each individual port and the ejection elements 31 than in the comparative example and therefore to make the liquid ejection head 1 compact. Owing to the short distance between each individual port 39 and the ejection elements 31, liquid flow resistance in the liquid ejection head 1 can be reduced. Furthermore, since no consideration needs to be taken as to forming overlap portions, the design flexibility for the liquid ejection head 1 improves.
The liquid ejection head 1 in the present embodiment has a configuration which is used for a liquid ejection apparatus using the liquid circulation method. Specifically, the liquid supply flow channel 18a and the liquid collection flow channel 18b of the liquid ejection head 1 are respectively connected to an apparatus-side supply flow channel and an apparatus-side collection flow channel provided in the liquid ejection apparatus. Then, liquid in a liquid storage part of the liquid ejection apparatus is supplied to the liquid supply flow channel 18a of the liquid ejection head 1 via the apparatus-side supply flow channel, and liquid that has flowed into the liquid supply flow channel 18a passes through the individual supply port 39a and flows into the pressure chamber 23. Part of the liquid that has flowed into the pressure chamber 23 is ejected from the ejection port 13 by driving of the ejection element 31, and the rest of the liquid returns to the liquid storage part via the individual collection port 39b, the liquid collection flow channel 18b, and the apparatus-side collection flow channel. Such a liquid-circulating liquid ejection apparatus that ejects liquid while circulating liquid can reduce sedimentation of a color material and the like contained in the liquid and therefore maintain favorable liquid ejection performance. Also, in the above embodiment, a distance L1 from the individual supply port 39a to the ejection elements 31 and a distance L1 from the individual collection port 39b to the ejection elements 31 are shortened. Thus, flow resistance that liquid experiences in flowing from the individual supply port 39a to the individual collection port 39b is reduced, which enables smooth liquid circulation.
Next, the configuration of and a method for manufacturing the liquid ejection head 1 according to the present embodiment are described in more concrete terms through a first example and a second example. In the following description, to clarify the characteristics of these examples, a comparative example to these examples is described first, and then each of the first and second examples is described next.
The configuration of and a method for manufacturing a liquid ejection head 100 of a comparative example to the examples are described with reference to
An interlayer insulating film 37 made of silicon oxide (SiO) and 1 to 2 μm thick was formed on a substrate 11 having driving elements (not shown) for driving ejection elements 31 and wiring (not shown) for driving the driving elements. Next, openings were formed in parts of the interlayer insulating film 37 using dry etching to form through-holes. Next, electrode plugs (not shown) were formed using tungsten to fill the through-holes. Note that the electrode plugs serve to electrically connect the driving elements in the lower layer to the ejection elements 31 to be formed in the upper layer.
After that, the ejection elements 31 were formed using a cermet material made of TaSiN. Specifically, the ejection elements 31 were formed with a thickness of 15 nm and a size of 15 μm in a planar direction. Dry etching using photolithography and chlorine was used for the formation of the ejection element 31. Next, using plasma CVD, an insulating protection film (not shown) made of SiN was formed with a thickness of 200 nm to cover the ejection element 31. Although the film thickness of the insulating protection film was set to 200 nm here from the perspective of insulation, the protection film may have a smaller film thickness as long as it is 100 nm or greater, and further, 100 nm or greater and 500 nm or less from the perspective of heat transfer to liquid.
Next, a cavitation-resistant layer 35 was formed on the insulating protection film. This cavitation-resistance layer was formed by three layers, namely a Ta layer, an Ir layer, and a Ta layer, stacked in this order from the front surface side (the upper surface side in
Then, the cavitation-resistant layer 35 was subjected to patterning. In this patterning of the cavitation-resistant layer formed on the entire front surface of the substrate 11, portions of the cavitation-resistant layer which were located above the ejection elements 31 were left, and a portion of the cavitation-resistant layer located elsewhere was removed by dry etching. The stack structure shown in
Next, an adhesion improvement layer 36 having an adhesive property with respect to the ejection port formation member 12 was formed using CVD on the entire surface of the interlayer insulating film 37, with a thickness of 150 nm (see
Next, dry etching was performed to form the individual ports 39 (the individual supply ports 39a and the individual collection ports 39b) in the interlayer insulating film 37 and the substrate 11, from the front surface (the upper surface in
Thereafter, using ALD, a titanium oxide (TiO) film 40 resistant to liquid such as ink was formed with a thickness of 100 nm on exposed portions in the substrate 11 and the interlayer insulating film 37. In other words, the TiO film 40 was formed on the back surface of the substrate 11, the inner surfaces of the liquid flow channels 18, the inner surfaces of the individual ports 39, and the front surface of the interlayer insulating film 37.
The TiO film 40 formed on the substrate 11 and the interlayer insulating film 37 was removed by wet etching using buffered hydrofluoric acid, except for the portions of the TiO film 40 formed on the inner surfaces of the individual ports 39 and the inner surfaces of the liquid flow channels 18. This wet etching was performed to form overlap portions 40a where the TiO film 40 overlaps with the adhesion improvement layer 36 formed on the front surface of the interlayer insulating film 37 by a distance of 5 μm, to make sure to leave the TiO film 40 formed on the inner surfaces of the individual ports 39.
After that, as shown in
As shown in
Next, the first example of the present invention is described. The following describes a method for manufacturing the liquid ejection head 1 shown in
In this example, after the patterning of the cavitation-resistant layer 35, Au pad portions shown in
After the formation of the opening portions 391 of the individual ports 39, as shown in
Although a 150-nm-thick SiOCN film was formed on the surface of the interlayer insulating film 37 in the formation of the liquid-resistant insulating film 38 in this example, the formation of the liquid-resistant insulating film 38 is not necessarily limited to this example. The formation of the liquid-resistant insulating film 38 may be carried out so that a SiOCN film with a thickness of 100 nm or greater may be formed on the inside of the individual ports 39. In addition, although plasma CVD was used to form the liquid-resistant insulating film 38, other film formation methods, such as ALD, may be used instead. If the SiOCN film forming the liquid-resistant insulating film 38 contains 5 at. % or greater carbon atoms C, it is possible to drastically decrease film thinning (a decrease in the film thickness) of the liquid-resistant insulating film 38 due to contact with liquid. In this example, the content of carbon atoms C was 10 at. %. The liquid-resistant insulating film 38 was thus formed in this example, continuously covering the front surface of the interlayer insulating film 37 and the inner surfaces of the individual ports 39.
Next, as shown in
Next, as shown in
Next, using a method similar to that in the comparative example, an ejection port formation member 12 was provided on the front surface (the upper surface in
Next, the second example of the present invention is described. The first example above has a configuration such that, in the ejection element substrate 10, only the interlayer insulating film 37 which is liable to elution upon contact with liquid such as ink is covered with the liquid-resistant insulating film 38 such as a SiOCN film. By contrast, the second embodiment has a configuration such that the inner surfaces of the liquid flow channels 18 (the liquid supply flow channel 18a and the liquid collection flow channel 18b) formed in the substrate 11 are also covered with a film with liquid resistance.
The processing up to
Next, using a method similar to the comparative example, an ejection port formation member 12 was provided on the front surface of the ejection element substrate 10A to form pressure chambers 23 communicating with the individual ports 39 between the ejection element substrate 10A and the ejection port formation member 12. The liquid ejection head 1A of the second example was thus completed.
Like the first example, this example makes it possible to have a shorter distance between the individual ports 39 and the ejection elements 31 and therefore to make the liquid ejection head 1A compact. Furthermore, this example allows not only the interlayer insulating film 37 but also the substrate 11 to be protected from liquid, which makes it possible to fabricate the liquid ejection head 1A with higher reliability.
Further, since the formation of the TiO film 41 using ALD and the etch-back are additionally performed in the second example, part of the substrate 11 can also be covered with a liquid-resistant film, which makes it possible to fabricate the liquid ejection head 1A with higher reliability.
(Comparisons Among First and Second Examples and Comparative Example)
Now, comparisons are made among the first example, the second example, and the comparative example. As shown in
While the comparative example uses two kinds of films, namely the adhesion improvement layer 36 and the TiO film 40, to protect the interlayer insulating film 37, the first example uses only one kind of film, namely the liquid-resistant insulating film 38, for protection against liquid. This configuration enables simplification of the manufacturing process and reduction in the manufacturing costs.
Furthermore, the second example forms the TiO film 41 using ALD and performs etch-back to cause the TiO film 41 to protect the substrate 11 from liquid as well, which makes it possible to fabricate a liquid ejection head with higher reliability.
In the above embodiment and examples, the individual supply ports 39a and the individual collection ports 39b are formed at both sides of the ejection elements 31 so that liquid supplied from the individual supply ports 39a to the pressure chambers 23 but not ejected through the ejection ports 13 may be collected from the individual collection ports 39b. However, the present invention is not limited to such a configuration. The present invention is applicable to a liquid ejection head having a configuration such that liquid is supplied from two individual ports provided at both sides of the ejection element to the pressure chambers. The present invention is also applicable to a liquid ejection head having a configuration such that an individual port communicating with a pressure chamber is formed only on one side of the ejection element so that liquid is supplied to the pressure chamber from the one individual port.
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 Application No. 2020-120678 filed Jul. 14, 2020, which is hereby incorporated by reference wherein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-120678 | Jul 2020 | JP | national |
