Laminate substrate, liquid discharge head, and manufacturing method of laminate substrate

Abstract

To provide a laminate substrate in which variation in hole diameter is suppressed at a boundary between a silicon substrate and a silicon oxide film.SOLUTION: A laminate substrate includes a silicon substrate 20, and a silicon compound film 110 laminated on the silicon substrate 20. The silicon compound film 110 has an open hole 115, and the silicon substrate 20 has a hole 135 communicating with the open hole 115. In at least a part of the hole 135 in a depth direction, the diameter of the hole 135 is made to be smaller than the diameter of the open hole 115 on a surface contacting the silicon substrate 20, thereby realizing a laminate substrate in which variation in hole diameter is suppressed.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a laminated substrate, a liquid ejection head, and a method for manufacturing the laminated substrate. [Background technology]

[0002] 2. Description of the Related Art Patent Document 1 describes a liquid ejection head used in inkjet printers and the like, in which liquid ejection holes are formed in a silicon single crystal substrate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-91272 A Summary of the Invention [Problem to be solved by the invention]

[0004] As the droplet size of the discharged liquid in the liquid discharge head increases, the diameter of the liquid discharge hole and the thickness of the discharge port forming substrate are also decreasing. In such a situation, it has been found that the finish of the side surface of the liquid discharge hole has a large effect on the discharge performance. In order to improve the finish of the side surface of the liquid discharge hole, there is a method of forming a silicon oxide film on the surface of a silicon substrate described in Patent Document 1. However, the silicon oxide film is likely to cause a change in the diameter of the liquid discharge hole at the boundary with the silicon substrate, and there is a possibility that the flow resistance of the liquid discharge hole is increased. In addition, not limited to the application to the liquid discharge head, when a hole is provided in a laminated substrate of a silicon substrate and a silicon oxide film, it is preferable to suppress the change in the diameter of the hole as much as possible at the boundary between the silicon substrate and the silicon oxide film.

[0005] An object of the present invention is to provide a laminated substrate in which change in diameter of a hole at the boundary between a silicon substrate and a silicon oxide film is suppressed, and a method for manufacturing the same. [Means for solving the problem]

[0006] In order to achieve the above object, according to one aspect of the present invention, there is provided a laminated substrate comprising a silicon substrate and a silicon compound film laminated on the silicon substrate, the silicon compound film having a through hole, the silicon substrate having a hole communicating with the through hole, and the diameter of the hole in at least a portion of the depth direction of the hole is smaller than the diameter of the through hole at a surface in contact with the silicon substrate.

[0007] According to another aspect of the present invention, there is provided a method for manufacturing a laminated substrate having a silicon substrate and a silicon compound film laminated on the silicon substrate, the method comprising: a step of forming a through hole in the silicon compound film of the laminated substrate; and a step of forming a hole in the silicon substrate, the through hole communicating with the through hole in the silicon compound film, wherein a by-product is generated in the step of forming the through hole, and a part of the by-product adheres to a side wall of the through hole in the silicon compound film, the step of forming the hole is performed in a state where the by-product adheres to the side wall of the through hole, and the method further comprises a step of removing the by-product after the formation of the through hole and the hole. Effect of the Invention

[0008] According to the present invention, it is possible to provide a laminated substrate in which the change in diameter of a hole at the boundary between a silicon substrate and a silicon oxide film is suppressed, and a method for manufacturing the same. [Brief description of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view showing a configuration of a liquid ejection head according to an embodiment of the present invention. [Diagram 2] 2 is a partial cross-sectional view of a laminated substrate of the liquid ejection head shown in FIG. [Diagram 3] 7A to 7C are partial cross-sectional views showing a process of forming a liquid ejection hole according to a comparative example. [Figure 4] 5A to 5C are partial cross-sectional views showing a process of forming a liquid ejection hole according to the embodiment of the present invention. [Diagram 5] 5A to 5C are partial cross-sectional views showing possible shapes of liquid ejection holes in the embodiment. [Figure 6] FIG. 11 is a partial cross-sectional view showing a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] A laminated substrate 111 according to an embodiment of the present invention will be described with reference to Figures 1 to 5. The embodiment is merely an illustration of the present invention, and is not intended to limit the scope of the present invention to this embodiment. The laminated substrate of the embodiment shown below is applied to a liquid ejection head using a piezoelectric element, but can also be applied to a liquid ejection head using a heat generating resistor element or an electrothermal conversion element. The liquid to be ejected is not limited to ink, as long as it can be ejected from the liquid ejection head.

[0011] In the following explanations and drawings, the Z direction refers to the direction in which the silicon substrate and the silicon compound film (silicon oxide film) are stacked, or the depth direction of the through hole or hole. Any direction perpendicular to the Z direction is called the X direction. A direction perpendicular to both the Z direction and the X direction is called the Y direction. The diameter refers to the dimension in the XY plane, and the radial direction refers to the direction from the central axis of the hole to the outer periphery of the hole in the XY plane, and in the case of a hole or through hole with a circular cross section, the diameter is equal to the diameter in the XY plane.

[0012] (Configuration of liquid ejection head) FIG. 1 is a cross-sectional view showing a main part (part) of an ink ejection head 1 of a printer after manufacture according to an embodiment of the present invention. The actuator substrate 10a is made of silicon. The actuator substrate 10a supports a vibration membrane 60 via a protective film 40 and an insulating film 50. The vibration membrane 60 is bonded to an insulating film 70. The insulating film 70 forms one surface of a cavity 80, and defines the cavity 80 together with a connection portion 10b and a silicon substrate 20. Ink is supplied to the cavity 80 through a through hole 30 penetrating the actuator substrate 10a in the Z direction, and a liquid flow path 35 penetrating the protective film 40, the insulating film 50, the vibration membrane 60, and the insulating film 70 in the Z direction. A piezoelectric element 45 is disposed between the protective film 40 and the insulating film 50. A cavity 85 is formed on the opposite side of the protective film 40 to the piezoelectric element 45. The silicon substrate 20 and the silicon compound film 110 form a laminated substrate 111. The silicon substrate 20 has a liquid ejection hole 90 communicating with the cavity 80. An ejection port 100 through which ink is ejected is formed on the most downstream side in the ejection direction of the liquid ejection hole 90. The diameter of the ejection port 100 is determined by the amount of ink ejected, and is generally about 5 μm to 50 μm. By applying a drive voltage from a power source (not shown) to the piezoelectric element 45, the vibration membrane 60 vibrates, and the cavity 80 repeatedly expands and contracts. By pressurizing the ink in the cavity 80, the ink passes through the liquid ejection hole 90 and is ejected from the ejection port 100.

[0013] (Shape and composition of liquid ejection holes) 2 is an enlarged view of part A in FIG. 1, showing a partial cross-sectional view of the laminated substrate 111. FIG. 2(a) shows a silicon compound film 110, a through-hole 115 in the silicon compound film 110, a silicon substrate 20, and a through-hole 135 in the silicon substrate 20 in this embodiment. The cross-sections of the through-hole 115 and the through-hole 135 at any position in the Z direction are approximately circular. The through-hole 115 communicates with the through-hole 135 to form a liquid discharge hole 90. The central axes of the through-hole 115 and the through-hole 135 are approximately aligned. The silicon compound film 110 is made of SiO, SiO2, Si3N4, SiN x, SiC, SiON, SiOC, SiCN, SiOCN, and particularly preferably a silicon oxide film. In this embodiment, the silicon compound film 110 is described as being a silicon oxide film. The through-hole 135 in the silicon substrate 20 is an example of a hole, and the hole may be a recess having a bottom. The through-hole 135 is formed by a Bosch process of the silicon substrate 20 using the silicon compound film 110 as a mask. The Bosch process refers to a dry etching process in which isotropic etching, formation of a sidewall protective film, and anisotropic etching are repeated.

[0014] The diameter of the through hole 115 in the silicon oxide film 110 increases monotonically as it moves away from the boundary surface with the silicon substrate 20. Since the silicon oxide film 110 is located outside the silicon substrate 20, that is, on the downstream side in the ink ejection direction, at least the downstream side of the liquid ejection hole 90 has a relatively smooth tapered side. A protrusion 120 that protrudes inward of the through hole 135 is formed on the boundary surface with the silicon oxide film 110 of the silicon substrate 20. The protrusion 120 is made of silicon.

[0015] FIG. 2(b) shows the silicon compound film 110 and the through hole 117 of the silicon compound film 110, and the silicon substrate 20 and the through hole 137 of the silicon substrate 20 in the comparative example. The through hole 117 communicates with the through hole 137 to form the liquid discharge hole 150. The central axes of the through hole 117 and the through hole 137 are roughly aligned. The through hole 137 is formed by the Bosch process of the silicon substrate 20, as in the example. In the comparative example, the side etching amount of the silicon substrate 20 directly below the silicon compound film 110 is large, and a large protrusion 140 of the silicon oxide film is formed. The side etching amount refers to the amount of etching in the radial direction. The protrusion 140 hardly changes even if the Bosch process is continued, which causes an increase in the liquid path resistance of the liquid discharge hole. Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples.

[0016] (Comparative Example) Fig. 3 shows the process of forming the liquid discharge hole 150 of the comparative example. The diameter of the discharge hole was set to be a circle with a diameter of φ20 μm. First, as shown in Fig. 3(a), photoresist was applied to provide a resist mask 160 on which a pattern of the through hole 117 to be formed in the oxide film 110 by photolithography was formed.

[0017] Next, as shown in FIG. 3(b), the silicon oxide film 110 was etched through the resist mask 160 to form a through hole 117 in the silicon oxide film 110. In general, etching of a silicon oxide film is performed using a mixed gas of C4F8 gas (octafluorocyclobutane gas), CF4 gas, and Ar gas. At this time, after the through hole 117 is formed, a by-product 170 enters the through hole 117 and is deposited on the bottom of the through hole 117, that is, on the silicon substrate 20. The by-product 170 means a mixture of an etching by-product and a deposition film containing carbon and fluorine. The C4F8 gas is used to improve the straightness of the etching of the silicon oxide film 110. However, in the comparative example, the C4F8 gas was not used in order to explain the effect of the embodiment. That is, the etching gas was a mixed gas of CF4 gas and Ar gas that does not contain C4F8 gas.

[0018] The conditions for etching the silicon oxide film 110 were as follows. In general, in etching the silicon oxide film 110, the etching gas pressure is controlled in the range of 0.1 Pa to 5 Pa, the etching gas flow rate is controlled in the range of 10 sccm to 1000 sccm, and the power applied to the coil is controlled in the range of 1000 W to 2000 W. In the comparative example, the etching gas pressure, which is a mixed gas of CF4 gas and Ar gas, was 0.3 Pa, the etching gas flow rate was 200 sccm, and the power applied to the coil was 1500 W. It was confirmed in a test other than the comparative example that the film thickness of the by-product 170 in the comparative example was small and below the measurement limit.

[0019] Next, as shown in FIG. 3(c), the Bosch process was performed through the resist mask 160 and the through hole 117 until the through hole 137 was provided in the silicon substrate 20. SF6 gas was used as the etching gas, and C4F8 gas was used as the coating gas. Then, as shown in FIG. 3(d), the resist mask 160 was removed. The diameter of the liquid discharge hole 150 in the silicon substrate 20 became larger than the diameter of the opening of the through hole 117 in the silicon oxide film 110 at the boundary surface with the silicon substrate 20. In other words, the cross-sectional area of ​​the liquid discharge hole 150 in the silicon substrate 20 became larger than the cross-sectional area of ​​the opening of the silicon oxide film 110 at the boundary surface with the silicon substrate 20. Therefore, the protrusion 140 was formed. The radial length of the protrusion 140 was about several μm. However, especially when the diameter of the liquid discharge hole 150 in the silicon substrate 20 is about 50 μm or less and a highly viscous liquid is discharged, the protrusion 140 causes an increase in the flow resistance of the liquid discharge hole 150. This increase in flow path resistance affects the meniscus vibration of the liquid, making the liquid ejection unstable.

[0020] The conditions of the Bosch process are as follows. In the Bosch process, SF6 gas is generally used as the etching gas and C4F8 gas is generally used as the protective film coating gas. In the etching process and the protective film forming process, the gas pressure is controlled in the range of 0.1 Pa to 50 Pa and the gas flow rate is controlled in the range of 50 sccm to 1000 sccm. The etching process time is controlled between 5 and 20 seconds, and the protective film forming process time is controlled between 1 and 10 seconds. In order to increase the etching rate in order to shorten the required time, the gas pressure is set to 10 Pa or more, the gas flow rate is set to 500 sccm or more, and the etching step time is set to 5 seconds or more. In the comparative example, SF6 gas and C4F8 gas are used as in the general Bosch process, and the gas pressure is controlled to 10 Pa, the gas flow rate is set to 700 sccm, the etching step time is controlled to 10 seconds, and the coating step time is controlled to 5 seconds, forming a flow path with high verticality.

[0021] (Example) Fig. 4 shows a process for forming a liquid discharge hole 90 according to the embodiment. The diameter of the discharge hole was set to be a circle with a diameter of φ20 μm. First, as shown in Fig. 4(a), a resist mask 165 having a pattern of a through hole 115 to be formed in the oxide film 110 was provided in the same manner as in Fig. 3(a).

[0022] Next, as shown in FIG. 4(b), the silicon oxide film 110 was etched through the resist mask 165 to form a through hole 115 in the silicon oxide film 110. In order to facilitate the generation of the by-product 171, the flow rate of the C4F8 gas contained in the etching gas was set to 100 sccm. Therefore, a larger amount of the by-product 171 than the by-product 170 shown in FIG. 3(b) was deposited on the silicon substrate 20, the sidewalls of the resist mask 165 and the silicon oxide film 110, and on the resist mask 165. The etching conditions for the silicon oxide film in the embodiment were as follows: the pressure of the etching gas, which is a mixed gas of C4F8 gas, CF4 gas, and Ar gas, was 0.3 Pa, the flow rate of the etching gas was 200 sccm, and the power applied to the coil was 1500 W. The flow rate of the C4F8 gas in the etching gas was set to 100 sccm as described above. Note that even if the flow rate of the C4F8 gas is made larger than 100 sccm, the effect is low. In general, in order to increase the amount of by-products 171 produced, it is preferable to keep the flow rate of the C4F8 gas in the entire area of ​​the through-hole 115 at 30 sccm or more and 100 sccm or less.

[0023] Next, as shown in FIG. 4(c), a through hole 137 was formed in the silicon substrate 20 by the Bosch process. In the embodiment, as in the general manufacturing method, a flow path with high verticality was formed by using SF6 gas and C4F8 gas, setting the gas pressure to 3 Pa, the gas flow rate to 300 sccm, the etching process time to 3 seconds, and the protective film forming process time to 1 second. At this time, the by-product 171 attached to the upper surface of the resist mask 165 and the upper surface of the silicon substrate 20 is removed, but the by-product 171 attached to the side walls of the resist mask 165 and the silicon oxide film 110 remains (hereinafter referred to as the side wall residual portion 175). The side wall residual portion 175 prevents the gas for etching the silicon substrate 20 from contacting the surface of the silicon substrate 20. If the radial thickness of the side wall residual portion 175 is large, the diameter of the liquid discharge hole 90 directly below the side wall residual portion 175 becomes small. Therefore, the radial length of the protrusion 140 (see FIG. 3) can be reduced, and can also be reduced to zero.

[0024] 4(d), the resist mask 165 and the remaining sidewall portion 175 were removed. A protruding portion 120 of the silicon substrate was formed at the interface between the silicon substrate 20 and the silicon oxide film 110. The length of the protruding portion 120 was approximately 0.1 μm or more.

[0025] Generally, when a hole is formed in a silicon substrate by the Bosch process, a periodic recessed structure consisting of multiple continuous recesses called scallops is formed in the depth direction Z. To explain the shape of the scallops, the dimensions are defined as follows (see Figure 2). L1 (scallop period): the length in the Z direction of each of the continuous recesses formed on the side walls of the liquid discharge holes 90, 150 of the silicon substrate 20 L2 (scallop amplitude): the maximum value of the radial depth of each of the continuous recesses formed on the sidewall of the liquid discharge holes 90, 150 of the silicon substrate 20 In both the comparative example and the embodiment, the Bosch process was controlled so that the shape of each scallop was uniform, and L1 and L2 were almost constant. The shape of the sidewall of the liquid discharge hole 150 in the comparative example was a scallop period L1 of about 5 μm and a scallop amplitude L2 of about 1 μm, as shown in FIG. 2(b). The shape of the sidewall of the liquid discharge hole 90 in the embodiment was a scallop period L1 of about 0.4 μm and a scallop amplitude L2 of about 0.1 μm, as shown in FIG. 2(a).

[0026] Due to the reduction in the scallops in the embodiment, the maximum diameter W1 of the liquid discharge hole 90 in the silicon substrate 20 is smaller than the diameter W2 of the liquid discharge hole 90 in the surface of the silicon oxide film 110 that contacts the silicon substrate 20, or the maximum cross-sectional area of ​​the liquid discharge hole 90 in the silicon substrate 20 is smaller than the minimum cross-sectional area of ​​the liquid discharge hole 90 in the silicon oxide film 110. The advantages of this are as follows:

[0027] The liquid ejection head has a large number of liquid ejection holes 90. For good liquid ejection, it is desirable to make the overall shape of each liquid ejection hole 90 within a certain tolerance range after accumulating design tolerances. The sum of the tolerances becomes smaller when the scallops are reduced. One example of a parameter related to the overall shape is the diameter of the liquid ejection hole 90 on the surface of the silicon oxide film 110 that contacts the silicon substrate 20, and the variation in the diameter between the liquid ejection holes 90 becomes smaller when the scallops are reduced. Then, since the flow resistance in each liquid ejection hole 90 is reduced and the meniscus vibration is stabilized, the supply of ink to the entire liquid ejection head is stabilized even when the ejection interval is short, and it is expected that the refill performance of the ink to the liquid ejection holes 90 for continuous ejection is improved. According to the embodiment, good results were obtained in a test in which ink was ejected onto a recording medium without gaps, and the liquid ejection was stabilized and the printing quality was improved compared to the comparative example.

[0028] The through-hole 90 of the silicon substrate 20 is not limited to a cross-sectional shape extending perpendicularly from the substrate surface. For example, as shown in FIG. 5(a), the diameter of the liquid discharge hole 200 of the silicon substrate 20 may be formed so as to increase with increasing distance from the silicon oxide film 110 in the Z direction. Also, as shown in FIG. 5(b), the liquid discharge hole 210 may be formed so that the central axis of the liquid discharge hole 210 in the silicon substrate 20 is not perpendicular to the boundary surface between the silicon substrate 20 and the silicon oxide film 110. Even in these two cases, it was confirmed that the protrusion 140 disappears and the protrusion 120 is formed by the side wall remaining portion 175, which is a feature of the embodiment, and that the effect of printing in the embodiment remains unchanged.

[0029] (Modification) 6A and 6B show the steps of forming the liquid ejection holes 220 according to the modified example. First, as shown in Fig. 6A, a resist mask 167 having a pattern of through holes to be formed in the oxide film 110 was provided in the same manner as in Fig. 4A.

[0030] Next, in this modification, as shown in FIG. 6(b), the silicon oxide film 110 was etched through the resist mask 167 to form a through hole 118 in the silicon oxide film 110. The etching conditions for the silicon oxide film 110 used in this modification are a pressure of 0.3 Pa for the etching gas, which is a mixed gas of C4F8 gas, CF4 gas, and Ar gas, a flow rate of the etching gas of 200 sccm (including a flow rate of 30 sccm for C4F8 gas), and a power of 1500 W applied to the coil. By-products 172 were deposited on the silicon substrate 20, the side walls of the resist mask 167 and the silicon oxide film 110, and on the resist mask 167, but the amount of deposition was less than that of the by-products 171 shown in FIG. 4(b). This is because the flow rate of the C4F8 gas was changed from 100 sccm to 30 sccm.

[0031] Next, as shown in FIG. 6(c), a through hole 138 was formed in the silicon substrate 20 by the Bosch process. In the modified example, a highly vertical flow path was formed by using SF6 gas and C4F8 gas, setting the gas pressure to 10 Pa, the gas flow rate to 500 sccm, the etching process time to 6 seconds, and the protective film forming process time to 3 seconds. At this time, the by-products 172 attached to the upper surface of the resist mask 167 and the upper surface of the silicon substrate 20 are removed, but the by-products 172 attached to the side walls of the resist mask 167 and the silicon oxide film 110 remain, forming the side wall residual portion 176. The scallops on the side surface of the silicon substrate 20 of the liquid discharge hole 220 have a scallop period L1 of 0.8 μm and a scallop amplitude L2 of 0.2 μm, which is larger than the scallops on the side surface of the silicon substrate 20 of the liquid discharge hole 90 of the embodiment, but smaller than the scallops on the side surface of the silicon substrate 20 of the liquid discharge hole 150 of the comparative example.

[0032] Next, as shown in FIG. 6(d), the resist mask 167 and the sidewall remaining portion 176 were removed. A protruding portion 121 of the silicon substrate was formed at the boundary surface between the silicon substrate 20 and the silicon oxide film 110. Since the radial length of the sidewall remaining portion 176 is smaller than the radial length of the sidewall remaining portion 175, the radial length of the protruding portion 121 is smaller than the radial length of the protruding portion 120, and is about 0.1 μm or less. The maximum value W5 of the diameter of the liquid discharge hole 220 of the silicon substrate 20 is larger than the minimum value W4 of the diameter of the liquid discharge hole 220 of the silicon oxide film 110, and the minimum value W3 of the diameter of the liquid discharge hole 220 of the silicon substrate 20 is smaller than the minimum value W4 of the diameter of the liquid discharge hole 220 of the silicon oxide film 110. Alternatively, the maximum value of the cross-sectional area of ​​the liquid discharge hole 220 in the silicon substrate 20 is larger than the minimum value of the cross-sectional area of ​​the liquid discharge hole 220 in the silicon oxide film 110, and the minimum value of the cross-sectional area of ​​the liquid discharge hole 220 in the silicon substrate 20 is smaller than the minimum value of the cross-sectional area of ​​the liquid discharge hole 220 in the silicon oxide film 110. In other words, the diameter or cross-sectional area of ​​the through hole of the liquid discharge hole 220 in the silicon substrate 20 has a dimensional tolerance in both the larger and smaller directions compared to the opening of the silicon oxide film 110 at the boundary surface with the silicon substrate 20.

[0033] As a result of performing an ink ejection test using the liquid ejection hole 220 shown in FIG. 6(d), it was confirmed that the meniscus vibration was stabilized, the ink ejection was stabilized, and the print quality was improved, compared to the case where the liquid ejection hole 150 according to the comparative example was used. However, since the scallops in the example were smaller than those in this modified example, these effects were superior in the example. Since the scallops in the modified example were larger than those in the example, the number of times that the cycle of forming the individual scallops in order to form the through-hole 138 in the silicon substrate 20 was repeated was reduced. Therefore, it is advantageous in that the process of forming the through-hole 138 is simple and can be completed in a short time.

[0034] The disclosure of the embodiments of the present invention includes the following configurations and methods. (Configuration 1) A silicon substrate and a silicon compound film laminated on the silicon substrate, the silicon compound film has a through hole, the silicon substrate has a hole communicating with the through hole, A laminated substrate, wherein the diameter of the hole in at least a portion in a depth direction of the hole is smaller than the diameter of the through hole in a surface in contact with the silicon substrate. (Configuration 2) A silicon substrate and a silicon compound film laminated on the silicon substrate, the silicon compound film has a through hole, the silicon substrate has a hole communicating with the through hole, A laminated substrate, wherein a cross-sectional area of ​​the hole in at least a portion in a depth direction of the hole is smaller than a cross-sectional area of ​​the through-hole at a surface in contact with the silicon substrate. (Configuration 3) 3. The laminated substrate according to claim 1 or 2, wherein the hole is a through hole penetrating the silicon substrate. (Configuration 4) The silicon compound film is SiO, SiO2, Si3N4, SiN x 4. The laminated substrate according to any one of claims 1 to 3, comprising one or more of the following: SiC, SiON, SiOC, SiCN, and SiOCN. (Configuration 5) 4. The laminated substrate according to any one of configurations 1 to 3, wherein the silicon compound film is a silicon oxide film. (Configuration 6) 6. The laminated substrate according to any one of configurations 1 to 5, wherein the diameter of the hole over the entire area in the depth direction of the hole is smaller than the diameter of the through-hole at the surface in contact with the silicon substrate. (Configuration 7) 7. The laminated substrate according to any one of configurations 1 to 6, wherein a diameter of the hole in a portion in the depth direction of the hole is smaller than a diameter of the through hole in a surface in contact with the silicon substrate. (Configuration 8) 8. A liquid ejection head comprising the laminated substrate according to claim 1. (Method 1) A method for manufacturing a laminated substrate having a silicon substrate and a silicon compound film laminated on the silicon substrate, comprising the steps of: forming a through hole in the silicon compound film of the laminated substrate; forming a hole in the silicon substrate, the hole communicating with the through hole in the silicon compound film; a by-product is generated in the step of forming the through hole, and a part of the by-product adheres to a side wall of the through hole in the silicon compound film; the step of forming the hole is performed in a state where the by-product adheres to the side wall of the through hole, The method for manufacturing a laminated substrate further comprises a step of removing the by-product after the through holes and the holes are formed. (Method 2) The silicon compound film is SiO, SiO2, Si3N4, SiN x , SiC, SiON, SiOC, SiCN, SiOCN. (Method 3) The method for producing a laminated substrate according to method 1, wherein the silicon compound film is a silicon oxide film. (Method 4) the hole in the silicon substrate is formed by dry etching that repeats isotropic etching, formation of a sidewall protective film, and anisotropic etching; 4. The method for manufacturing a laminated substrate according to any one of Methods 1 to 3, wherein the diameter of the hole in at least a part of the hole in the depth direction is smaller than the diameter of the through hole in the surface in contact with the silicon substrate. (Method 5) the hole in the silicon substrate is formed by dry etching that repeats isotropic etching, formation of a sidewall protective film, and anisotropic etching; 5. The method for manufacturing a laminated substrate according to any one of Methods 1 to 4, wherein the cross-sectional area of ​​the hole in at least a portion of the depth direction of the hole is smaller than the cross-sectional area of ​​the through hole in the surface in contact with the silicon substrate. (Method 6) 6. The method for manufacturing a multilayer substrate according to any one of Methods 1 to 5, wherein the through-holes in the silicon compound film are formed by etching with a gas containing octafluorocyclobutane gas. (Method 7) 7. The method for producing a multilayer substrate according to any one of Methods 1 to 6, wherein a flow rate of the octafluorocyclobutane gas is 30 sccm or more and 100 sccm or less. [Explanation of symbols]

[0035] 20 Silicon substrate 110 Silicon Compound Film 111 Laminated substrate 115 Through hole 135 holes

Claims

1. A silicon substrate and a silicon compound film laminated on the silicon substrate, The silicon compound film has a through hole, the silicon substrate has a hole communicating with the through hole, A laminated substrate, wherein the diameter of the hole in at least a portion in a depth direction of the hole is smaller than the diameter of the through hole in a surface in contact with the silicon substrate.

2. The laminated substrate according to claim 1 , wherein the hole is a through hole penetrating the silicon substrate.

3. The silicon compound film is SiO, SiO 2 , Si 3 N 4 , SiN x , SiC, SiON, SiOC, SiCN, SiOCN.

4. The laminated substrate according to claim 1 , wherein the silicon compound film is a silicon oxide film.

5. The laminated substrate according to claim 1 , wherein the diameter of the hole is smaller over the entire area in the depth direction than the diameter of the through hole at a surface in contact with the silicon substrate.

6. The laminated substrate according to claim 1 , wherein a diameter of the hole in a portion in the depth direction of the hole is smaller than a diameter of the through hole in a surface in contact with the silicon substrate.

7. A silicon substrate and a silicon compound film laminated on the silicon substrate, The silicon compound film has a through hole, the silicon substrate has a hole communicating with the through hole, A laminated substrate, wherein a cross-sectional area of ​​the hole in at least a portion in a depth direction of the hole is smaller than a cross-sectional area of ​​the through-hole at a surface in contact with the silicon substrate.

8. A liquid ejection head comprising the laminated substrate according to claim 1 .

9. A method for manufacturing a laminated substrate having a silicon substrate and a silicon compound film laminated on the silicon substrate, comprising the steps of: forming a through hole in the silicon compound film of the laminated substrate; forming a hole in the silicon substrate, the hole communicating with the through hole in the silicon compound film; a by-product is generated in the step of forming the through hole, and a part of the by-product adheres to a side wall of the through hole in the silicon compound film; the step of forming the hole is performed in a state where the by-product adheres to the side wall of the through hole, The method for manufacturing a laminated substrate further comprises a step of removing the by-product after the through holes and the holes are formed.

10. The silicon compound film is SiO, SiO 2 , Si 3 N 4 , SiN x 10. The method of claim 9, further comprising one or more of the following: SiC, SiON, SiOC, SiCN, and SiOCN.

11. The method for manufacturing a multilayer substrate according to claim 9 , wherein the silicon compound film is a silicon oxide film.

12. the hole in the silicon substrate is formed by dry etching that repeats isotropic etching, formation of a sidewall protective film, and anisotropic etching; 10. The method for manufacturing a multilayer substrate according to claim 9, wherein a diameter of the hole in at least a part in a depth direction of the hole is smaller than a diameter of the through hole in a surface in contact with the silicon substrate.

13. the hole in the silicon substrate is formed by dry etching that repeats isotropic etching, formation of a sidewall protective film, and anisotropic etching; 10. The method for manufacturing a multilayer substrate according to claim 9, wherein a cross-sectional area of ​​the hole in at least a portion in a depth direction of the hole is smaller than a cross-sectional area of ​​the through-hole in a surface in contact with the silicon substrate.

14. The method for manufacturing a multilayer substrate according to claim 9 , wherein the through-holes in the silicon compound film are formed by etching using a gas containing octafluorocyclobutane gas.

15. The method for manufacturing a multilayer substrate according to claim 14, wherein a flow rate of the octafluorocyclobutane gas is 30 sccm or more and 100 sccm or less.

Images