JP2014083824A - Method for manufacturing liquid discharge head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To further miniaturize a liquid discharge head.SOLUTION: A method for manufacturing the liquid discharge head provided with a silicon substrate having a liquid supply port includes the steps of: (a) forming a groove so as to enclose the outside of an opening of the liquid supply port in the rear surface of the silicon substrate; (b) forming etching protective walls at least on the side and bottom surfaces of the groove; (c) forming a rear surface protective film on the rear surface of the silicon substrate; and (d) performing crystal anisotropic etching treatment to the silicon substrate using the rear surface protective film as an etching mask and forming the liquid supply port inside the etching protective wall. When the rear surface opening width of the liquid supply port is defined as X, the thickness of the silicon substrate is defined as Z, and the depth of the groove is defined as Z, Zsatisfies Z<Zand Z≥Z-(X/2)×tan54.7°.

Description

  The present invention relates to a method for manufacturing a liquid ejection head that performs recording on a recording medium by ejecting a liquid according to an inkjet method.

  A liquid discharge head mounted on an ink jet recording apparatus performs recording by discharging droplets from discharge ports by various methods and attaching the droplets to a recording medium such as recording paper. In particular, a liquid discharge head that uses heat as energy for discharging liquid can easily realize high-density multi-nozzle formation, high resolution, high image quality, and high-speed recording.

  In recent years, in the manufacture of a liquid discharge head, a silicon substrate is processed in which the opening width of a liquid supply port is suppressed in order to reduce the size and density of the substrate. For example, Patent Document 1 discloses that a silicon substrate having a non-through lead hole has a crystal anisotropy using an etchant whose etching rate on the vertical (100) plane is faster than the etching rate on the lateral (110) plane. It is disclosed that etching is performed to form a liquid supply port. As a result, it is possible to form the liquid supply port while suppressing the spread of the width in the lateral direction, and it is possible to reduce the opening of the liquid supply port of the silicon substrate and efficiently form the liquid supply port.

JP2011-755A

  However, in the case of the method described in Patent Document 1, in the crystal anisotropic etching process, in order to shorten the etching time in the lateral (110) plane, a non-penetrating guide port is formed deeply with respect to the silicon substrate. It is necessary and processing takes time. In addition, when the opening width on the surface of the silicon substrate is wide, the processing time for crystal anisotropic etching is extended, so that the etching in the lateral (110) plane proceeds, and the opening size inside the silicon substrate may vary. In this case, it is difficult to realize further downsizing of the liquid discharge head because the size must be determined in consideration of variations in the opening size.

  An object of the present invention is to realize further downsizing of the liquid discharge head.

A method for manufacturing a liquid discharge head according to the present invention is a method for manufacturing a liquid discharge head including a silicon substrate having a liquid supply port,
(A) forming a groove so as to surround the outside of the opening of the liquid supply port on the back surface of the silicon substrate;
(B) forming an etching protection wall on at least a side surface and a bottom surface of the groove;
(C) forming a back surface protective film on the back surface of the silicon substrate;
(D) performing a crystal anisotropic etching process on the silicon substrate using the back surface protective film as an etching mask, and forming the liquid supply port inside the etching protective wall,
Wherein the back surface opening width X ₃ of the liquid supply port, Z ₁ the thickness of the silicon substrate, if the depth of the groove is defined as Z _2, Z ₂ is, Z ₂ <Z ₁ and Z ₂ ≧ Z ₁ - (X ₃ satisfy the /2)×tan54.7°.

  According to the present invention, further downsizing of the liquid discharge head can be realized.

FIG. 5 is a perspective view, a cross-sectional view, and a back view of a liquid discharge head manufactured by the method according to the present invention. It is sectional drawing which shows the dimension prescription | regulation in the liquid supply port formation of this invention. It is sectional drawing which shows an example of the manufacturing process of the liquid discharge head which concerns on this invention. It is sectional drawing which shows an example of the manufacturing process of the liquid discharge head which concerns on this invention. It is sectional drawing which shows an example of the manufacturing process of the liquid discharge head which concerns on this invention. It is sectional drawing which shows an example of the manufacturing process of the liquid discharge head which concerns on this invention.

A method for manufacturing a liquid discharge head according to the present invention is a method for manufacturing a liquid discharge head including a silicon substrate having a liquid supply port,
(A) forming a groove so as to surround the outside of the opening of the liquid supply port on the back surface of the silicon substrate;
(B) forming an etching protection wall on at least a side surface and a bottom surface of the groove;
(C) forming a back surface protective film on the back surface of the silicon substrate;
(D) performing a crystal anisotropic etching process on the silicon substrate using the back surface protective film as an etching mask, and forming the liquid supply port inside the etching protective wall,
Wherein the back surface opening width X ₃ of the liquid supply port, Z ₁ the thickness of the silicon substrate, if the depth of the groove is defined as Z _2, Z ₂ is, Z ₂ <Z ₁ and Z ₂ ≧ Z ₁ - (X ₃ satisfy the /2)×tan54.7°.

  According to the present invention, the opening size of the back surface of the liquid supply port and the opening size inside the silicon substrate can be defined, and further reduction in the size of the substrate for the liquid discharge head is realized by suppressing etching in the lateral (110) plane. Can do.

  As an example of a liquid discharge head manufactured by the method according to the present invention, an ink jet head is shown in FIG. The liquid discharge head manufactured by the method according to the present invention is not limited to the inkjet head. FIG. 1A is a perspective view of an ink jet head. FIG. 1B is a cross-sectional view of the inkjet head of FIG. FIG. 1C is a bottom view of the ink jet head of FIG.

  As shown in FIG. 1B, the ink jet head manufactured by the method according to the present invention includes a surface protective film 5, an ink flow path 14, and an ejection port 15 on the surface of the silicon substrate 1. In the silicon substrate 1, an ink supply port 4 for supplying ink to the ink flow path 14 and the discharge port 15 is formed. An etching protection wall 2 is formed on the inner wall of the ink supply port 4. A back surface protective film 3 is formed on the back surface of the silicon substrate 1.

  Further, as shown in FIG. 1C, in the inkjet head manufactured by the method according to the present invention, an etching protection wall 2 is formed inside the silicon substrate 1 so as to surround the outer periphery of the opening of the ink supply port 4. Has been. The etching protection wall 2 is formed perpendicular to the back surface of the silicon substrate 1 from the back surface of the silicon substrate 1 toward the front surface of the silicon substrate 1 so as to surround the outside of the opening of the ink supply port 4.

In the method of manufacturing a liquid discharge head according to the present invention, when the back surface opening width of the liquid supply port is defined as X ₃ , the thickness of the silicon substrate is defined as Z ₁ , and the depth of the groove is defined as Z ₂ , Z ₂ is Z ₂ < Z ₁ and _{Z 2 ≧ Z 1 - (X} 3 and satisfies the /2)×Tan54.7. Hereinafter, the crystal anisotropic etching process for the opening width of the back surface of the silicon substrate in the stage before the liquid supply port is formed will be described with reference to the drawings. FIG. 2 is a cross-sectional view of the liquid discharge head showing the stipulations relating to the formation of the liquid supply port.

As shown in FIG. 2A, when the crystal anisotropic etching process is performed on the back surface opening width X ₂ of the silicon substrate back surface 6, the etching proceeds at an angle of 54.7 ° with respect to the silicon substrate 1 surface. An opening is formed anisotropically. That is, when etching is performed from the back surface 6 of the silicon substrate, the opening width is gradually narrowed as the etching proceeds toward the surface of the silicon substrate 1. Therefore, the depth that can be etched is determined by the back surface opening width X ₂ of the back surface 6 of the silicon substrate. For example, when the back surface opening width of the silicon substrate back surface 6 is X ₂ and the thickness of the silicon substrate 1 is Z ₁ , the back surface opening width X ₂ of the silicon substrate back surface 6 necessary for penetrating the silicon substrate 1 by etching is as follows: (1).

X ₂ ≧ 2 × (Z _{1 /} tan 54.7 °) (1)
For example, when Z ₁ = 700 μm, X ₂ ≧ 991 μm can be obtained from the above equation (1).

On the other hand, in the present invention, as shown in FIG. 2B, a back surface opening width X ₃ is defined on the back surface 6 of the silicon substrate, and a groove 8 is formed outside thereof. The groove 8 is formed perpendicular to the silicon substrate back surface 6 so as to surround the outside of the opening of the liquid supply port. In order to perform etching with a width of the back surface opening width X ₃ , it is necessary to form the groove 8 to a depth that allows opening to the surface of the silicon substrate 1. If the depth of the groove is Z ₂ , the necessary Z ₂ can be expressed by the following formula (2).

_{Z 2 ≧ Z 1 - (X} 3 /2)×tan54.7° (2)
For example, when X ₃ = 500 μm and Z ₁ = 700 μm, Z ₂ ≧ 347 μm can be determined from the equation (2). Note that Z ₂ <Z ₁ . Further, X ₃ ≦ 2 × (Z _{1 /} tan 54.7 °) is preferable. X ₃ represents the maximum width of the opening of the liquid discharge port. Thus, by defining the back surface opening width X ₃ and the thickness Z ₁ of the silicon substrate 1, it is possible to define the minimum depth of the groove 8 required to prevent the etching in the lateral direction.

Moreover, in this invention, it is preferable to include the process of forming an etching sacrificial layer on the said silicon substrate surface before the said process (d). In this case, as shown in FIG. 2C, an etching sacrificial layer having an etching sacrificial layer width X ₁ narrower than the back surface opening width X ₃ is formed on the surface of the silicon substrate 1. By defining the etching sacrificial layer width X ₁ with respect to the back surface opening width X ₃ , the depth Z ₂ of the groove 8 changes. Z ₂ necessary in this case can be expressed by the following formula (3).

Z ₂ ≧ Z ₁ − {(X ₃ −X ₁ ) / 2} × tan 54.7 ° (3)
For example, when X ₁ = 100 μm, X ₃ = 500 μm, and Z ₁ = 700 μm, Z ₂ ≧ 418 μm can be obtained from the above equation (3). Note that X ₁ <X ₃ and Z ₂ <Z ₁ . X ₁ represents the maximum width of the etching sacrificial layer. Further, if the expression (3) is satisfied, the expression (2) is satisfied.

Furthermore, in this invention, it is preferable to include the process of forming a lead hole in the said silicon substrate back surface before the said process (d). In this case, as shown in FIG. 2D, a distance X ₄ narrower than the back surface opening width X ₃ described in FIG. 2B is defined in the silicon substrate 1 to form the leading hole 9. In FIG. 2D, the etching protection wall 2 is formed in the groove 8 satisfying the expression (3). When performing crystal anisotropic etching with the etching protection wall 2 formed, the etching of the lateral direction (110) plane is suppressed and etching time is required. However, the etching time is shortened by forming the lead hole 9. can do. The required depth Z ₃ of the leading hole 9 can be expressed by the following formula (4).

_{Z 3 ≧ Z 1 - (X} 4 /2)×tan54.7° (4)
For example, when X ₄ = 300 and Z ₁ = 700, Z ₃ ≧ 488 μm can be obtained from the equation (4). Note that X ₃ > X ₄ and Z ₁ > Z ₃ . Thus, by defining the distance X ₄ between the leading holes having a width narrower than the back surface opening width X ₃ , the minimum depth of the leading hole 9 required to open the liquid supply port can be defined. .

  Although the depth of the groove and the depth of the leading hole in the present invention have been described above, the width of the groove and the leading hole can be arbitrarily selected depending on the forming method and the like. Further, as will be described later, the etching protection wall may be removed when the crystal anisotropic etching process is completed, or may be left as it is.

  Next, an embodiment of a method for manufacturing a liquid discharge head according to the present invention will be described. The method according to the present invention is not limited to these embodiments.

[First embodiment]
A method for manufacturing the liquid ejection head according to the first embodiment will be described with reference to FIGS. 3 and 4 are sectional views of the liquid ejection head in each step.

As shown in FIG. 3A, an etching sacrificial layer 16, a surface protective film 5, an energy generating element (not shown), and a logic circuit (not shown) are disposed on the surface of the silicon substrate 1. The thickness Z ₁ of the silicon substrate 1, the formula (2) is not particularly limited if it meets, for example 100μm or more, it is possible to 1000μm or less. The material of the etching sacrificial layer 16 is not particularly limited as long as it is a material that is etched by the crystal anisotropic etching process. For example, Al or the like can be used. The etching sacrificial layer 16 width X ₁ preferably satisfies the above formula (3), but can be, for example, 10 μm or more and 500 μm or less. The thickness of the etching sacrificial layer 16 is not particularly limited, but may be, for example, 0.01 μm or more and 1.0 μm or less. The material of the surface protective film 5 is not particularly limited as long as the material has resistance to the crystal anisotropic etching process. For example, SiO ₂ , SiN, SiC or the like can be used. These may use only 1 type and may use 2 or more types together. Although the thickness of the surface protective film 5 is not specifically limited, For example, it can be 0.01 micrometer or more and 1.0 micrometer or less. The energy generating element is not particularly limited, and for example, an electrothermal conversion element or a piezoelectric element can be used. The logic circuit is not particularly limited as long as it functions as a circuit.

  Next, as shown in FIG. 3B, a resist mask 7 is formed on the back surface 6 of the silicon substrate. As a material for the resist mask 7, a positive resist can be used. As the positive resist, for example, “IP5700” (trade name, manufactured by Tokyo Ohka Kogyo Co., Ltd.) can be used as a commercial product. The method for forming the resist mask 7 is not particularly limited. For example, the resist mask 7 can be formed by applying the material of the resist mask 7 by a spin coating method, and then selectively exposing and developing.

Next, as shown in FIG. 3C, grooves 8 are formed in the silicon substrate 1. The groove 8 is formed so as to surround the outside of the opening of the liquid supply port 4 to be formed later on the back surface 6 of the silicon substrate. The depth Z ₂ of the groove 8 is not particularly limited as long as the expression (2) is satisfied, but may be, for example, 20 μm or more and 960 μm or less. The width of the groove 8 is not particularly limited, but can be, for example, 1.0 μm or more and 100 μm or less. The back surface opening width X ₃ of the liquid supply port is not particularly limited as long as the formula (2) is satisfied, but may be set to, for example, 100 μm or more and 1400 μm or less. The method of forming the groove 8 is not particularly limited, but can be formed by, for example, dry etching or laser. As the dry etching, an etching method using plasma such as RIE (reactive ion etching) can be used. For example, SF ₆ or CF ₄ can be used as the etching gas. These may use only 1 type and may use 2 or more types together. The side wall of the groove 8 is preferably formed perpendicularly to the back surface 6 of the silicon substrate from the viewpoint of obtaining a stable opening size.

  Next, as shown in FIG. 3D, the resist mask 7 is removed, and the back surface 6 of the silicon substrate is exposed. The method for removing the resist mask 7 is not particularly limited, but when a positive resist is used as the material of the resist mask 7, the removal can be performed with a positive resist removing solution.

  Next, as shown in FIG. 3E, the etching protection wall 2 is formed in the groove 8, and the back surface protective film 3 is formed on the silicon substrate back surface 6. From the viewpoint of having sufficient durability in the crystal anisotropic etching treatment in the process described later, the etching protective wall 2 and the back surface protective film 3 are preferably crystal anisotropic etching resistant films. The material of the etching protection wall 2 is not particularly limited as long as it is a material having resistance to crystal anisotropic etching. Examples thereof include thermoplastic resin materials containing soluble polyimide fillers (commercially available products such as HIMAL (trade name, manufactured by Hitachi Chemical Co., Ltd.)), epoxy resin materials, and the like. These may use only 1 type and may use 2 or more types together. As the material for the back surface protective film 3, the same material as the material for the etching protection wall 2 can be used.

  The method for forming the etching protection wall 2 is not particularly limited, but the etching protection wall 2 can be formed by, for example, applying the material for the etching protection wall 2 by spin coating, slit coating, or the like, and then baking and curing in an oven. As a method for completely filling the groove 8 with the material for the etching protection wall 2 as in the present embodiment, there is a method in which the material for the etching protection wall 2 is applied by a spin coating method or the like and then the vacuum state is applied. . By filling the etching protective wall 2 in the groove 8, the substrate can be reliably protected from the crystal anisotropic etching process. In the present invention, it is not necessary to completely fill the etching protective wall 2 in the groove 8 as in the embodiment described later, and it is sufficient that the etching protective wall 2 is formed on at least the side surface and the bottom surface of the groove 8. Although the formation method of the back surface protective film 3 is not specifically limited, For example, after apply | coating the material of the back surface protective film 3 by a spin coat method, a slit coat method, etc., it can form by baking and hardening in oven.

  In addition, as in the present embodiment, the formation of the etching protection wall 2 and the formation of the back surface protection film 3 are preferably performed simultaneously from the viewpoint of not increasing the number of steps. Therefore, the material of the etching protection wall 2 and the material of the back surface protective film 3 are preferably the same. The film thickness of the etching protection wall 2 is not particularly limited as long as it can stop the etching by the crystal anisotropic etching process, and can be, for example, 1.0 μm or more and 100 μm or less. The film thickness of the back surface protective film 3 is not particularly limited as long as it can stop the etching by the crystal anisotropic etching process, and can be, for example, 1.0 μm or more and 100 μm or less.

  Next, as shown in FIG. 3F, a resist mask 7 is formed on the back surface protective film 3. As a material for the resist mask 7, a positive resist can be used. As the positive resist, for example, “IP5700” (trade name, manufactured by Tokyo Ohka Kogyo Co., Ltd.) can be used as a commercial product. The method for forming the resist mask 7 is not particularly limited. For example, the resist mask 7 can be formed by applying the material of the resist mask 7 by a spin coating method, and then selectively exposing and developing.

  Next, as shown in FIG. 3G, a part of the back surface protective film 3 is removed, and a part of the back surface 6 of the silicon substrate is exposed. For example, a part of the back surface protective film 3 can be removed by dry etching using the resist mask 7 as an etching mask. A part of the exposed back surface 6 of the silicon substrate becomes a crystal anisotropic etching surface in a process described later.

  Next, as shown in FIG. 3H, the resist mask 7 is removed. The method for removing the resist mask 7 is not particularly limited, but when a positive resist is used as the material of the resist mask 7, the removal can be performed with a positive resist removing solution. Thereby, a part of the silicon substrate back surface 6 and the back surface protective film 3 are exposed.

Next, as shown in FIG. 4A, a flow path mold member 10, a flow path forming member 11 and an etching protection film 12 are formed on the surface of the silicon substrate 1. As a method of forming the flow path mold member 10, the flow path forming member 11, and the etching protective film 12, a method that is usually used in a method of manufacturing a liquid discharge head can be used. A leading hole 9 is formed in the back surface 6 of the silicon substrate. The number of leading holes 9 is not particularly limited. If the leading holes 9 form two depth Z ₃ guide holes 9 preferably satisfies the formula (4). The depth Z ₃ of the leading hole 9 can be set to 30 μm or more and 980 μm or less, for example. Also, when the leading holes 9 form two, distance X ₄ between the leading holes 9 preferably satisfies the formula (4). The distance X ₄ between the leading holes 9 can be set to 40 μm or more and 1340 μm or less, for example. The width of the leading hole 9 is not particularly limited, but can be, for example, 10 μm or more and 100 μm or less. The leading hole 9 can be formed using a laser.

  Next, as shown in FIG. 4B, the liquid supply port 4 is formed, and the etching sacrificial layer 16 is removed. The formation of the liquid supply port 4 and the removal of the etching sacrificial layer 16 are performed by performing a crystal anisotropic etching process on the silicon substrate 1 using the back surface protective film 3 as an etching mask. The crystal anisotropic etching treatment can be performed using TMAH (tetramethylammonium hydroxide) or the like. In the method according to the present invention, since the etching in the lateral direction is suppressed by the etching protection wall 2 in the crystal anisotropic etching process, only the inside of the etching protection wall 2 is etched. Thereby, the liquid supply port 4 is formed inside the etching protection wall 2, and a part of the surface protection film 5 and the etching protection wall 2 are exposed.

Next, as shown in FIG. 4C, a part of the exposed surface protective film 5 is removed. As a method for removing a part of the surface protective film 5, for example, dry etching is exemplified. No particular limitation is imposed on the etching gas, may be used, for example a mixed gas of CF ₄ and O ₂ or the like. In this embodiment, the etching protection wall 2 and the back surface protection film 3 that have finished the role of etching protection are left, but they may be removed as in the second embodiment described later. However, the number of processes can be reduced by not removing these, and since the Si surface on which the etching protection wall 2 is formed is not exposed, dissolution of Si due to the type of ink can be prevented. On the other hand, when removing the etching protection wall 2 and the back surface protection film 3, it can be removed by, for example, chemical dry etching.

  Next, as shown in FIG. 4D, the flow path mold member 10 and the etching protective film 12 are removed, and the liquid flow path 14 and the discharge port 15 are formed. Thereby, the liquid discharge head is completed. For removing the etching protective film 12, although it depends on the material of the etching protective film 12, for example, xylene or the like can be used. For example, methyl lactate or the like can be used to remove the flow path mold member 10 depending on the material of the flow path mold member 10. The flow path mold 10 can be removed by elution from the liquid supply port 4 and the discharge port 15 by immersing in, for example, methyl lactate at 40 ° C. and applying ultrasonic waves.

[Second Embodiment]
A method for manufacturing a liquid ejection head according to the second embodiment will be described with reference to FIGS. 5 and 6 are cross-sectional views of the liquid discharge head in each step.

  The steps shown in FIGS. 5A to 5D can be performed in the same manner as the steps shown in FIGS. 3A to 3D of the first embodiment.

Next, as shown in FIG. 5E, the etching protection wall 2 was formed on the side surface and the bottom surface of the groove 8, and the back surface protective film 3 was formed on the silicon substrate back surface 6. As materials for the etching protection wall 2 and the back surface protection film 3, SiO ₂ , SiN, or the like can be used. These may use only 1 type and may use 2 or more types together. A method for forming the etching protection wall 2 and the back surface protection film 3 is not particularly limited, and for example, plasma CVD can be used. By using plasma CVD, the etching protection wall 2 and the back surface protection film 3 can be formed more easily than the method of completely filling the material of the etching protection wall 2 in the groove 8 as in the first embodiment. it can. The film thickness of the etching protective wall 2 and the back surface protective film 3 is not particularly limited as long as it is a film thickness that can be protected from etching in the crystal anisotropic etching process, but for example, 0.1 μm or more and 5.0 μm or less. 1.0 μm or more and 2.0 μm or less is preferable. The width of the groove 8 after the etching protection wall 2 is formed is preferably 0.1 μm or more and 100 μm or less. In this embodiment, the etching protective wall 2 and the back surface protective film 3 are formed simultaneously, but the etching protective wall 2 and the back surface protective film 3 may be formed separately.

  The processes shown in FIGS. 5 (f) to (h) and FIG. 6 (a) can be performed in the same manner as the processes shown in FIGS. 3 (f) to (h) and FIG. 4 (a) of the first embodiment. .

  Next, as shown in FIG. 6B, the liquid supply port 4 is formed, and the etching sacrificial layer 16 is removed. The formation of the liquid supply port 4 and the removal of the etching sacrificial layer 16 are performed by performing a crystal anisotropic etching process on the back surface 6 of the silicon substrate using the back surface protective film 3 as an etching mask. The crystal anisotropic etching process can be performed using TMAH or the like. As a result, a part of the surface protective film 5 and the etching protective wall 2 are exposed. The etching protection wall 2 functions to suppress lateral etching when the liquid supply port 4 is formed, so that only the inside of the etching protection wall 2 is etched. In this embodiment, since the etching protection wall 2 is formed on the side surface and the bottom surface of the groove 8, the etching protection wall 2 remains in the liquid supply port 4 in the form of burrs. The etching protection wall 2 that has finished the role of this etching protection can be removed in a later step.

Next, as shown in FIG. 6C, a part of the exposed surface protection film 5, the etching protection wall 2 and the back surface protection film 3 are removed. By finally removing the etching protection wall 2 and the back surface protection layer 3, it can be avoided that these remain as thin-film dust. An example of a method for removing these is dry etching. As an etching gas for dry etching, for example, a mixed gas of CF ₄ and O ₂ can be used. Thereby, the silicon substrate back surface 6 and the etching protection wall trace 13 are exposed.

  The step shown in FIG. 6D can be performed in the same manner as the step shown in FIG. Thereby, the liquid discharge head is completed.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

Example 1
A method for manufacturing the liquid discharge head according to the first embodiment is shown in FIGS.

  As shown in FIG. 3A, an etching sacrificial layer 16, a surface protective film 5, an energy generating element (not shown), and a logic circuit (not shown) are arranged on the surface of the silicon substrate 1. Al was used as the material of the etching sacrificial layer 16. SiN was used as the material of the surface protective film 5.

  Next, as shown in FIG. 3B, a resist mask 7 was formed on the back surface 6 of the silicon substrate. The resist mask 7 was formed by applying a positive resist (trade name: IP5700, manufactured by Tokyo Ohka Kogyo Co., Ltd.) onto the silicon substrate back surface 6 by spin coating, and selectively exposing and developing.

Next, as shown in FIG. 3C, grooves 8 were formed in the silicon substrate 1. Specifically, using the resist mask 7 as an etching mask, a groove 8 having a width of 10 μm and a depth of 418 μm was formed perpendicularly to the silicon substrate back surface 6 by dry etching. RIE was used for dry etching. SF ₆ and CF ₄ were used as the etching gas. The depth (Z ₂ ) of the groove 8 is calculated from the above equation (3) from the etching sacrificial layer 16 width (X ₁ ) 100 μm, the back surface opening width (X ₃ ) of 500 μm, and the silicon substrate thickness (Z ₁ ) 700 μm. Asked to meet.

  Next, as shown in FIG. 3D, the resist mask 7 was removed, and the back surface 6 of the silicon substrate was exposed. A positive resist remover was used to remove the resist mask 7.

  Next, as shown in FIG. 3E, the etching protection wall 2 was formed in the groove 8, and at the same time, the back surface protective film 3 was formed on the silicon substrate back surface 6. A thermoplastic resin material containing a soluble polyimide filler was applied onto the back surface 6 of the silicon substrate by a spin coating method, and then the vacuum resin was applied to completely fill the groove 8 with the thermoplastic resin material. Thereafter, the thermoplastic resin material was baked in an oven and cured to form the etching protective wall 2 and the back surface protective film 3. The film thickness of the back surface protective film 3 was 1.5 μm. The etching protection wall 2 and the back surface protection film 3 are anti-crystalline anisotropic etching films.

  Next, as shown in FIG. 3 (f), a resist mask 7 was formed on the back surface protective film 3. The resist mask 7 was formed by applying a positive resist (trade name: IP5700, manufactured by Tokyo Ohka Kogyo Co., Ltd.) onto the back surface protective film 3 by spin coating, and selectively exposing and developing.

  Next, as shown in FIG. 3G, a part of the back surface protective film 3 was removed, and a part of the silicon substrate back surface 6 was exposed. Specifically, a part of the back surface protective film 3 was removed by dry etching using the resist mask 7 as an etching mask.

  Next, the resist mask 7 was removed as shown in FIG. A positive resist remover was used to remove the resist mask 7.

Next, as shown in FIG. 4A, the flow path mold member 10, the flow path forming member 11 and the etching protective film 12 were formed on the surface of the silicon substrate 1. The method of forming the flow path mold member 10, the flow path forming member 11, and the etching protective film 12 is omitted for the sake of convenience. Further, two leading holes 9 were formed on the back surface 6 of the silicon substrate. The leading hole 9 was formed using a laser. The width of the leading hole 9 was 20 μm, the depth was 489 μm, and the distance between the leading holes 9 was 300 μm. The distance (X ₄ ) between the leading holes 9 and the depth (Z ₃ ) of the leading holes 9 are calculated from the above formula (4) from the back surface opening width (X ₃ ) of 500 μm of the liquid supply port and the thickness (Z ₁ ) 700 μm of the silicon substrate. ).

  Next, as shown in FIG. 4B, the liquid supply port 4 was formed, and the etching sacrificial layer 16 was removed. Formation of the liquid supply port 4 and removal of the etching sacrificial layer 16 were performed by performing crystal anisotropic etching using TMAH using the back surface protective film 3 as an etching mask. As a result, a part of the surface protective film 5 and the etching protective wall 2 were exposed. Note that the etching protective wall 2 has a function of suppressing lateral etching when the liquid supply port 4 is formed, so that only the inside of the etching protective wall 2 is etched.

Next, as shown in FIG. 4C, a part of the exposed surface protective film 5 was removed. A part of the surface protective film 5 was removed by dry etching. As the etching gas, a mixed gas of CF ₄ and O ₂ was used.

  Next, as shown in FIG. 4D, the flow path mold member 10 and the etching protective film 12 were removed, and the liquid flow path 14 and the discharge port 15 were formed. Thereby, the liquid discharge head was completed. The etching protective film 12 was removed with 100% xylene. The flow path mold 10 was immersed in methyl lactate heated to 40 ° C. and subjected to 200 KHz / 200 W ultrasonic waves to be eluted from the liquid supply port 4 and the discharge port 15 and removed.

(Example 2)
A method for manufacturing a liquid ejection head according to the second embodiment is shown in FIGS.

  The steps shown in FIGS. 5A to 5D were performed in the same manner as the steps shown in FIGS. 3A to 3D of Example 1.

  Next, as shown in FIG. 5E, the etching protection wall 2 was formed on the side surface and the bottom surface of the groove 8, and the back surface protective film 3 was formed on the silicon substrate back surface 6. The etching protection wall 2 and the back surface protection film 3 were formed by depositing SiN with a thickness of 1.5 μm using plasma CVD. The etching protection wall 2 and the back surface protection film 3 are anti-crystalline anisotropic etching films.

  The steps shown in FIGS. 5F to 5H and FIG. 6A were performed in the same manner as the steps shown in FIGS. 3F to 3H and FIG.

  Next, as shown in FIG. 6B, the liquid supply port 4 was formed, and the etching sacrificial layer 16 was removed. Formation of the liquid supply port 4 and removal of the etching sacrificial layer 16 were performed by performing crystal anisotropic etching using TMAH using the back surface protective film 3 as an etching mask. As a result, a part of the surface protective film 5 and the etching protective wall 2 were exposed. Note that the etching protective wall 2 has a function of suppressing lateral etching when the liquid supply port 4 is formed, so that only the inside of the etching protective wall 2 is etched. Further, since the etching protection wall 2 was formed on the side surface and the bottom surface of the groove 8, the etching protection wall 2 remained in the liquid supply port 4 in the form of burrs.

Next, as shown in FIG. 6C, a part of the exposed surface protective film 5, the etching protective wall 2 and the back surface protective film 3 were removed. These were removed by dry etching. As the etching gas, a mixed gas of CF ₄ and O ₂ was used. Thereby, the silicon substrate back surface 6 and the etching protection wall trace 13 were exposed.

  The step shown in FIG. 6D was performed in the same manner as the step shown in FIG. Thereby, the liquid discharge head was completed.

DESCRIPTION OF SYMBOLS 1 Silicon substrate 2 Etch protection wall 3 Back surface protection film 4 Liquid supply port 5 Surface protection film 6 Silicon substrate back surface 7 Resist mask 8 Groove 9 Leading hole 10 Flow path mold material 11 Flow path forming member 12 Etch protection film 13 Etch protection wall mark 14 Liquid flow path 15 Discharge port 16 Etching sacrificial layer

Claims (10)

A method of manufacturing a liquid discharge head comprising a silicon substrate having a liquid supply port,
(A) forming a groove so as to surround the outside of the opening of the liquid supply port on the back surface of the silicon substrate;
(B) forming an etching protection wall on at least a side surface and a bottom surface of the groove;
(C) forming a back surface protective film on the back surface of the silicon substrate;
(D) performing a crystal anisotropic etching process on the silicon substrate using the back surface protective film as an etching mask, and forming the liquid supply port inside the etching protective wall,
Wherein the back surface opening width X ₃ of the liquid supply port, Z ₁ the thickness of the silicon substrate, if the depth of the groove is defined as Z _2, Z ₂ is, Z ₂ <Z ₁ and Z ₂ ≧ Z ₁ - (X ₃ a method for manufacturing a liquid discharge head that satisfies /2)×Tan54.7. Before the step (d), the method includes (e) forming an etching sacrificial layer on the silicon substrate surface,
When the etching sacrificial layer width is defined as X ₁ , X ₁ and Z ₂ are X ₁ <X ₃ , Z ₂ <Z ₁ and Z ₂ ≧ Z ₁ − {(X ₃ −X ₁ ) / 2} × tan 54 The method for manufacturing a liquid discharge head according to claim 1, wherein the liquid discharge head satisfies a condition of 0.7 °. The method for manufacturing a liquid discharge head according to claim _1, wherein X ₃ ≦ 2 × (Z _{1 /} tan 54.7 °) is satisfied.   4. The method of manufacturing a liquid discharge head according to claim 1, wherein the etching protection wall is a film of anti-crystal anisotropic etching. 5.   The method of manufacturing a liquid ejection head according to claim 1, wherein the step (b) and the step (c) are performed simultaneously.   6. The method of manufacturing a liquid ejection head according to claim 1, further comprising: (f) a step of forming a leading hole in the back surface of the silicon substrate before the step (d).   The method of manufacturing a liquid discharge head according to claim 6, wherein the leading hole is formed by a laser. In the step (f), two leading holes are formed,
Distance X ₄ between the guide holes, if the depth of the guide hole is defined as Z _3, are X ₄ and _{Z 3, X 3> X 4} , Z 1> Z 3 and Z ₃ ≧ Z ₁ - ( method for manufacturing a liquid discharge head according to claim 6 or 7 satisfy X ₄ /2)×tan54.7°.   The method for manufacturing a liquid discharge head according to claim 1, wherein the groove is formed by dry etching.   10. The method of manufacturing a liquid ejection head according to claim 1, wherein a side wall of the groove is formed perpendicular to the back surface of the silicon substrate.

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