JP2018192719A - Substrate for liquid discharge head and liquid discharge head - Google Patents

Abstract

To inhibit oxidation of a heating resistor from its upper surface and its lower surface in a substrate for a liquid discharge head.SOLUTION: A substrate 10 for a liquid discharge head has: a substrate 101; electrode wiring 103 disposed on the substrate 101; an interlayer dielectric film 104 disposed on the electrode wiring 103; a heating resistor 106 disposed on the interlayer dielectric film 104; and a protection layer 107 disposed on the heating resistor 106. An upper surface of the interlayer dielectric film 104 is flattened. An oxidation inhibition layer 109 is disposed below the heating resistor 106.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a substrate for a liquid discharge head that discharges liquid, and more particularly to a substrate for a liquid discharge head that discharges liquid by thermal energy and a liquid discharge head.

  Ink-jet heads used in so-called thermal-type ink-jet printers that use thermal energy are required to have higher speed and longer life, and as a result, the amount of change in resistance value over time of the heating resistors used in ink-jet heads is suppressed. Is required. In order to increase the speed of the operation of the ink jet head, it is necessary to increase the resistance value of the heating resistor used in the ink jet head (high resistance). However, as the resistance of the heating resistor increases, the amount of change in the resistance value increases. . In addition, the amount of change in the resistance value of the heating resistor also increases as the life of the inkjet head increases. One of the causes that the amount of change in the resistance value of the heating resistor increases is that the heating resistor is oxidized by moisture or oxygen.

  In the invention described in Patent Document 1, it is said that the oxidation from the back surface of the heating resistor can be suppressed by forming a silicon nitride antioxidant layer divided immediately below the heating resistor.

JP 2004-90291 A

  However, in order to drive a high-resistance heating resistor with a long life, it is required to further suppress changes in the resistance value of the heating resistor, so from both sides of the surface (upper surface) and back surface (lower surface) of the heating resistor. It is necessary to suppress the oxidation of.

  If the divided silicon nitride is formed as in the invention described in Patent Document 1, a step is generated in the ink protective layer, so that moisture or oxygen derived from the ink or the like enters from the side wall of the step, and from the upper surface of the heating resistor. The effect of oxidation becomes larger. In order to perform normal ink ejection over a long period of time, it is required to suppress such oxidation and suppress a change in resistance value of the heating resistor.

  In view of the above problems, an object of the present invention is to provide a liquid discharge head substrate and a liquid discharge head capable of suppressing the oxidation from the upper surface and the lower surface of a heating resistor and stably discharging liquid over a long period of time. It is.

The substrate for a liquid discharge head of the present invention for solving the above-described problems is
A base, an electrode wiring disposed on the base, an interlayer insulating film disposed on the electrode wiring, a heating resistor disposed on the interlayer insulating film, and the heating resistor A protective layer disposed on the
The interlayer insulating film has a flat upper surface, and an oxidation suppression layer is disposed below the heating resistor.

  When the oxidation suppression layer is made of a material having a higher resistance value (volume resistivity) than that of the heating resistor, it may be disposed on the lower surface of the heating resistor. When the oxidation suppression layer is made of a material having a resistance value lower than that of the heating resistor, it may be disposed on the lower surface of the heating resistor. Further, the oxidation suppression layer may be disposed apart from the heating resistor.

  The electrode wiring disposed apart from the heating resistor may also serve as the oxidation suppression layer.

  The liquid discharge head of the present invention includes any one of the liquid discharge head substrates described above.

  According to the present invention, it is possible to provide a liquid discharge head substrate and a liquid discharge head that can suppress oxidation from the upper surface and the lower surface of the heating resistor and can stably discharge liquid over a long period of time.

(A) is a top view which shows an example of the board | substrate for inkjet heads based on Example 1 of this invention, (b) is sectional drawing in A-A 'shown to (a). (A)-(j) is an example of the manufacture flow of the board | substrate for inkjet heads based on Example 1 of this invention. (A) is a top view which shows an example of the board | substrate for inkjet heads based on Example 2 of this invention, (b) is sectional drawing in A-A 'shown to (a). (A)-(e) is an example of the manufacture flow of the board | substrate for inkjet heads based on Example 2 of this invention. (A) is a top view which shows an example of the board | substrate for inkjet heads concerning Example 3 of this invention, (b) is sectional drawing in A-A 'shown to (a).

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. However, the components described in the embodiments and examples of the present invention are merely examples, and are not intended to limit the scope of the present invention.

(Embodiment 1)
FIG. 1A is a plan view of an inkjet head substrate 10 (liquid ejection head substrate) according to Embodiment 1 of the present invention, and FIG. 1B is a cross-sectional view taken along AA ′ of the plan view. FIG. FIG. 1A is a plan view including only a layer below the heating resistor 106 shown in FIG.

  In the following cross-sectional views, the direction in which the base 101 is present is the downward direction. That is, the lower direction in the cross-sectional view is referred to as the lower (direction) in the inkjet head substrate 10 and the opposite direction is referred to as the upper (direction). The term “lower” or “upper” means that it is below or above, directly or between other members.

  As shown in FIG. 1B, an inkjet head substrate 10 includes a base 101, a first interlayer insulating film 102, an electrode wiring 103, a second interlayer insulating film (interlayer insulating film) 104, and a plug. A film 105, a heating resistor 106, and an ink protective layer (protective layer) 107 are provided. Furthermore, the inkjet head substrate 10 may include an anti-cavitation film 108 on the ink protective layer 107. Note that the inkjet head substrate 10 includes a plurality of configurations including the above-described elements, and only two configurations are shown in FIG. 1. Since both configurations are common, one configuration will be described. .

  A driving element made of a semiconductor element such as a switching transistor for selectively driving the heating resistor 106 is formed on the substrate 101 made of Si. However, since the drive elements are not directly related in the present invention, for simplicity, the drive elements are not shown here, and only the base 101 is shown.

  On the substrate 101, for example, a first interlayer insulating film 102 made of an oxide layer having a planarized upper surface mainly composed of silicon oxide (SiO) is disposed. An electrode wiring 103 made of, for example, aluminum (Al) is disposed on the first interlayer insulating film 102 by patterning. The thickness of the electrode wiring 103 is, for example, 1000 nm.

  On the electrode wiring 103, for example, a second interlayer insulating film 104 having a planarized upper surface mainly composed of SiO is disposed. The second interlayer insulating film 104 is formed so as to embed the entire electrode wiring 103. The thickness of the second interlayer insulating film 104 is, for example, 1500 nm in the upper part from the electrode wiring 103.

  An oxidation suppression layer 109 is disposed on the second interlayer insulating film 104. A heating resistor 106 is patterned on the oxidation suppression layer 109. The heating resistor 106 is mainly composed of tantalum silicon nitride (TaSiN) having a thickness of 20 nm, for example. In addition, as shown in FIG. 1A, for example, six plug films 105 that electrically connect the heating resistors 106 and the electrode wirings 103 are arranged per one heating resistor 106.

  On the heating resistor 106, for example, an ink protective layer 107 mainly composed of silicon nitride (SiN) having a thickness of 200 nm is disposed. On the ink protective layer 107, for example, a cavitation resistant layer 108 made of tantalum (Ta) having a thickness of 200 nm is disposed.

(Oxidation suppression layer material)
The oxidation suppression layer 109 is a layer that suppresses the permeation of oxygen or moisture from below the heating resistor 106 and is a material having a lower oxygen or moisture permeability than SiO normally used as an interlayer insulating layer. Good. The oxidation suppression layer 109 is a metal film such as silicon (Si), titanium (Ti), aluminum (Al), tantalum (Ta), tungsten (W), or a nitride (SiN) containing at least one of these metals. TiN, AlN, TaN, WN, etc.).

  Note that the oxidation suppressing layer formed of an insulating material (such as silicon or silicon nitride) having a resistance value larger than that of the heating resistor may be in contact with the heating resistor. That is, the oxidation suppression layer formed of a material having a higher volume resistivity than the material forming the heating resistor may be in contact with the heating resistor. On the other hand, the oxidation suppression layer formed of a conductive material having a resistance value smaller than that of the heating resistor is preferably arranged apart from the heating resistor as described in the second embodiment.

  According to the above configuration, since the upper surface of the second interlayer insulating film 104 is flattened, the oxidation suppression layer 109 formed thereon is also formed with a flat upper surface. As a result, the ink protective layer 107 disposed on the oxidation suppression layer 109 with the heating resistor 106 interposed therebetween is also formed as a highly flat layer. Since the ink protective layer 107 is formed with a reduced step, it is possible to eliminate or reduce the stepped side wall portion where the film thickness is thin and the film quality is poor. Therefore, the ink protective layer 107 disposed on the upper surface of the heating resistor 106 can prevent oxygen and moisture from entering from the upper surface direction of the heating resistor 106.

  Further, an oxidation suppression layer 109 is disposed on the lower surface of the heating resistor 106 (that is, between the upper surface of the second interlayer insulating film 104 and the heating resistor 106). Therefore, it is possible to prevent oxygen and moisture from entering from the lower surface direction of the heating resistor 106. Thus, oxidation from the upper surface and the lower surface of the heating resistor 106 is suppressed. As a result, a change in the resistance value of the heating resistor 106 with time can be suppressed.

(Embodiment 2)
The inkjet head substrate 20 according to the second embodiment will be described with reference to FIGS. FIG. 3A is a plan view showing a layer below the heating resistor 106 in FIG. In the inkjet head substrate 20, the oxidation suppression layer 109 is disposed inside the interlayer insulating film so as to be separated from the heating resistor 106.

  As shown in FIG. 3B, a first interlayer insulating film 102 is disposed on a substrate 101 made of Si, as in the first embodiment, and an electrode wiring 103 is further disposed thereon.

  On the electrode wiring 103, for example, a second interlayer insulating film 104 having a planarized upper surface mainly composed of SiO is disposed. The second interlayer insulating film 104 is formed so as to embed the entire electrode wiring 103. The thickness of the second interlayer insulating film 104 is, for example, 1250 nm in the portion above the electrode wiring 103.

  On the second interlayer insulating film 104, for example, an oxidation suppression layer 109 made of titanium nitride (TiN), which is a conductive material having a thickness of 200 nm and having a higher conductivity than the heating resistor 106, is a plug film. A region for forming 105 is opened and patterned. The reason for opening the region where the plug film 105 is formed is as follows. That is, since TiN, which is the material of the oxidation suppression layer 109, is conductive, electricity easily flows to the oxidation suppression layer 109 when it is in contact with the plug film 105, so that a desired amount of heat generated by the heating resistor 106 cannot be secured. Because there is a fear. As the material of the oxidation suppression layer 109, the same material as that described in Embodiment 1 can be used.

  On the oxidation suppression layer 109, for example, a third interlayer insulating film (interlayer insulating film) 110 having a planarized upper surface mainly composed of SiO is disposed. The thickness of the third interlayer insulating film 110 is, for example, 250 nm. The third interlayer insulating film 110 is preferably not a coating film such as SOG (spin-on-glass) but a film that hardly contains moisture formed by CVD or the like.

  On the third interlayer insulating film 110, for example, a heating resistor 106 mainly composed of TaSiN is patterned with a thickness of 20 nm, for example. Note that the plug film 105 connecting the heating resistor 106 and the electrode wiring 103 is disposed at six locations for each heating resistor 106 as shown in FIG. The oxidation suppression layer 109 is patterned so as not to contact the plug film 105.

  On the heating resistor 106, for example, an ink protective layer 107 mainly composed of SiN is disposed with a thickness of 200 nm, for example. On the ink protective layer 107, an anti-cavitation layer 108 made of Ta, for example, is disposed with a thickness of 200 nm, for example.

  Even in the configuration as in the second embodiment, the same effect as in the first embodiment can be obtained. Furthermore, according to the configuration of the second embodiment, the possibility that the resistance value of the heating resistor 106 is affected by the arrangement of the oxidation suppressing layer 109 in contact with the heating resistor 106 can be eliminated. That is, among the materials used for the oxidation suppression layer 109, a material having a resistance value lower than that of the heating resistor (having high conductivity) bypasses the current and flows to the oxidation suppression layer 109, and the heating resistor is sufficient. A calorific value cannot be obtained. However, by providing the heating resistor 106 and the oxidation suppression layer 109 apart from each other as in the second embodiment, it is possible to prevent current from flowing through the oxidation suppression layer 109. Thereby, the choice of the material of an oxidation suppression layer will increase.

(Embodiment 3)
An inkjet head substrate 30 according to Embodiment 3 will be described with reference to FIGS. FIG. 5A is a plan view showing a layer below the heating resistor 106 in FIG. In the third embodiment, the electrode wiring and the oxidation suppression layer are shared.

  As shown in FIG. 5B, a first interlayer insulating film 102 is disposed on a substrate 101 made of Si, as in the first embodiment.

  A patterned electrode wiring 103 made of, for example, an Al metal film is disposed on the first interlayer insulating film 102. In this case, the opening width (separation distance) L of the two electrode wirings 103 located below the region where the heating resistor 106 is formed is as narrow as possible, for example, 1000 nm. This is to narrow a region where the first interlayer insulating film 102 is not covered with the electrode wiring 103, that is, a region where the first interlayer insulating film 102 is exposed. The thickness of the electrode wiring 103 is, for example, 1000 nm. By forming the electrode wiring 103 in this way, the function of the oxidation suppression layer can be achieved.

  On the electrode wiring 103, for example, a second interlayer insulating film 104 having a planarized upper surface mainly composed of SiO is disposed. The second interlayer insulating film 104 is formed so as to embed the entire electrode wiring 103. The thickness of the second interlayer insulating film 104 is, for example, 1500 nm in the upper part from the electrode wiring 103. The second interlayer insulating film 104 is also preferably a film that hardly contains moisture formed by CVD or the like.

  On the second interlayer insulating film 104, a heating resistor 106 mainly composed of TaSiN, for example, is patterned with a thickness of 20 nm, for example. Note that, as shown in FIG. 5A, six plug films 105 for connecting the heating resistor 106 and the electrode wiring 103 are arranged for one heating resistor 106. The electrode wiring 103 is arranged so that the opening width of the electrode wiring 103 below the heating resistor 106 is 1000 nm, and the region covering the first interlayer insulating film 102 is widened. In order for the electrode wiring 103 to also function as an oxidation suppression layer, when the inkjet head substrate 30 is viewed in plan, the area where the heating resistor 106 and the electrode wiring 103 connected thereto are overlapped is defined as the heating resistance. The area of the body 106 is preferably half or more.

  On the heating resistor 106, for example, an ink protective layer 107 mainly composed of SiN is disposed with a thickness of 200 nm, for example. On the ink protective layer 107, an anti-cavitation layer 108 made of Ta, for example, is disposed with a thickness of 200 nm, for example.

  Even in the configuration as in the third embodiment, the same effect as in the first embodiment can be obtained. Furthermore, according to the configuration of the third embodiment, since the electrode wiring 103 formed of a metal film also serves as the oxidation suppression layer 111, the structure becomes simpler.

  An ink jet recording head (liquid ejection head) can be manufactured by forming an orifice plate and an ink supply port on the ink jet head substrate having the configuration described in the first to third embodiments. The orifice plate has a conventionally known configuration, and has an ink flow path that also serves as a foaming chamber and an ink discharge port that communicates with the ink flow path on the anti-cavitation film of the inkjet head substrate. In addition, the ink supply port may be configured to penetrate the inkjet head substrate and communicate with the ink flow path. Part of the ink supplied to the foaming chamber is foamed by being given thermal energy from the heating resistor, and the ink near the ink ejection port is ejected as ink droplets by the pressure during foaming. In the present invention, since oxidation from the upper surface and the lower surface of the heating resistor can be suppressed at the same time, a liquid discharge head capable of stably discharging liquid over a long period of time is provided.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited only to these Examples, It can change within the scope of the present invention.

Example 1
As shown in FIG. 2A, a switching transistor (not shown) was formed on a substrate 101 made of Si, and a first interlayer insulating film 102 was formed thereon by using SiO. Next, the upper surface of the first interlayer insulating film 102 was planarized by the CMP method. On top of that, Al was formed to a thickness of 1000 nm by a sputtering method, and an electrode wiring 103 was formed by patterning using photolithography and etching.

  As shown in FIG. 2B, SiO is deposited to a thickness of 3000 nm by the CVD method, and the SiO surface is flattened using the CMP method as shown in FIG. A second interlayer insulating film 104 having a thickness of 1500 nm was formed. Next, as shown in FIG. 2D, a 200 nm SiN film was formed by the CVD method to form an oxidation suppression layer 109.

  Next, as shown in FIG. 2E, through holes 121 reaching the electrode wiring 103 were formed in the second interlayer insulating film 104 and the oxidation suppression layer 109 by patterning using photolithography and etching.

  Next, as shown in FIG. 2F, a plug film 105 was formed by filling the through hole 121 with W by a CVD method.

  Next, as shown in FIG. 2G, the plug film 105 on the oxidation suppression layer 109 was removed by CMP until the upper surface of the oxidation suppression layer 109 was exposed.

  Next, as shown in FIG. 2 (h), a TaSiN layer to be the heating resistor 106 was formed to a thickness of 20 nm by sputtering.

  Next, as shown in FIG. 2I, the heating resistor 106 was patterned using photolithography and etching.

  Next, as shown in FIG. 2J, a 200 nm SiN film was formed as an ink protective layer 107 on the heating resistor 106 by a CVD method. Further, a 200-nm-thick Ta film was formed thereon as a cavitation-resistant layer 108 by a sputtering method, and the inkjet head substrate 10 was manufactured.

  An ink jet recording head was manufactured by forming an orifice plate and an ink supply port on the ink jet head substrate 10 having the structure of the first embodiment. When ink was ejected, the resistance value of the heating resistor 106 showed a stable value, and stable ejection over a long period of time was realized.

(Example 2)
After forming up to the electrode wiring 103 as in Example 1, a second interlayer insulating film 104 was formed by depositing SiO to a thickness of 2500 nm by the CVD method and planarizing it by the CMP method. The thickness of the second interlayer insulating film 104 from the upper surface of the electrode wiring 103 was 1250 nm. Next, an oxidation suppression layer 109 was formed as shown in FIG. 4A by depositing TiN as a conductive material to a thickness of 200 nm and patterning by sputtering.

  Next, as shown in FIG. 4B, a SiO film was formed to a thickness of 500 nm by a CVD method to form an insulating film 110. Next, as shown in FIG. 4C, the upper surface of the insulating film 110 was flattened by CMP to form a third interlayer insulating film 110.

  Next, as shown in FIG. 4D, through holes 121 reaching the electrode wiring 103 were formed in the second interlayer insulating film 104 and the third interlayer insulating film 110 by patterning. Next, in the same manner as described with reference to FIG. 2F, the plug film 105 was formed by filling the through hole 121 with W by the CVD method.

  Next, as shown in FIG. 4E, the plug film 105 on the third interlayer insulating film 110 was removed by CMP until the surface of the third interlayer insulating film 110 was exposed. Next, a 20 nm thick TaSiN film to be the heating resistor 106 was formed by sputtering and patterned. A 200 nm SiN film was formed thereon as an ink protective layer 107 by a CVD method. On top of this, Ta was deposited to a thickness of 200 nm as a cavitation-resistant layer 108 by a sputtering method to produce an inkjet head substrate 20 as shown in FIG.

  An orifice plate and an ink supply port are formed on the inkjet head substrate 20 having the configuration of the second embodiment, and when the ink is ejected, it is confirmed that the resistance value of the heating resistor 106 shows a stable numerical value, and the ejection is performed for a long time. Was realized. It was also confirmed that the initial resistance value of the heating resistor 106 was not affected.

Example 3
The manufacturing method of Example 3 is basically the same as that of FIGS. 2A to 2J except for the step of FIG. Specifically, as in the first and second embodiments, a switching transistor (not shown) is formed on a substrate 101 made of Si, and SiO is stacked to form a first interlayer as shown in FIG. An insulating film 102 was formed. After planarizing the upper surface by CMP, Al was deposited to a thickness of 1000 nm by sputtering, and electrode wiring 103 was formed by patterning.

  When forming the electrode wiring 103, the distance between the two electrode wirings 103 at a position below the region where the heating resistor 106 is formed on the surface was set to 1000 nm. This is to narrow a region where the first interlayer insulating film 102 is not covered with the electrode wiring 103, that is, a region where the first interlayer insulating film 102 is exposed.

  Next, as shown in FIGS. 2B and 2C, a second interlayer insulating film 104 is formed by forming a SiO layer with a thickness of 3000 nm by the CVD method and planarizing the upper surface by the CMP method. Formed.

  Next, through holes 121 were formed in the second interlayer insulating film 104 by patterning (the state where the oxidation suppression layer 109 in FIG. 2E is not present). Next, a plug film 105 made of W was formed so as to fill the through hole by the CVD method (the state in which there is no oxidation suppression layer 109 in FIG. 2F).

  Next, the plug film 105 on the second interlayer insulating film 104 was removed by CMP until the surface of the second interlayer insulating film 104 was exposed (in a state where the oxidation suppression layer 109 in FIG. 2G was not present). . Next, 20 nm of TaSiN to be the heating resistor 106 was formed by sputtering and patterned (state without the oxidation suppression layer 109 in FIG. 2I). A 200 nm SiN film was formed thereon as an ink protective layer 107 by a CVD method. A 200 nm thick Ta film was formed thereon as a cavitation resistant layer 108 by sputtering (the state in which the oxidation inhibiting layer 109 in FIG. 2 (j) was not present).

  An orifice plate and an ink supply port are formed on the ink jet head substrate having the configuration of the third embodiment, and when the ink is ejected, it is confirmed that the resistance value of the heating resistor 106 shows a stable value, and the ejection is performed for a long time. Realized. In addition, it could be formed with a simple structure as compared with Example 1 and Example 2.

10, 20, 30 Substrate 101 for inkjet head (liquid ejection head) Base 102 First interlayer insulating film 103 Electrode wiring 104 Second interlayer insulating film (interlayer insulating film)
105 Plug film 106 Heating resistor 107 Ink protective layer (protective layer)
108 Anti-cavitation film 109 Oxidation suppressing layer 110 Third interlayer insulating film (interlayer insulating film)
111 Oxidation suppression layer (electrode wiring)

Claims (9)

A base, an electrode wiring disposed on the base, an interlayer insulating film disposed on the electrode wiring, a heating resistor disposed on the interlayer insulating film, and the heating resistor A liquid ejection head substrate having a protective layer disposed on
A substrate for a liquid discharge head, wherein the interlayer insulating film has a flat upper surface, and an oxidation suppression layer is disposed below the heating resistor.   2. The liquid discharge head substrate according to claim 1, wherein the oxidation suppression layer is made of a material having a higher resistance value than the heating resistor and is disposed on a lower surface of the heating resistor.   2. The liquid discharge head substrate according to claim 1, wherein the oxidation suppression layer is made of a material having a higher volume resistivity than a material forming the heating resistor, and is disposed on a lower surface of the heating resistor. .   The substrate for a liquid discharge head according to claim 1, wherein the oxidation suppression layer is formed of silicon or silicon nitride.   The liquid discharge head substrate according to claim 1, wherein a plurality of the heating resistors are disposed on the oxidation suppression layer.   The substrate for a liquid ejection head according to claim 1, wherein the oxidation suppression layer is disposed apart from the heating resistor.   The liquid discharge head substrate according to claim 6, wherein the electrode wiring also serves as the oxidation suppression layer.   The liquid discharge head substrate according to claim 6, wherein the oxidation suppression layer is formed of at least one of titanium, aluminum, tantalum, and tungsten, or a nitride containing at least one of these metals. A liquid discharge head comprising the liquid discharge head substrate according to claim 1.

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