JP2016030380A - Substrate for liquid discharge head and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate for a liquid discharge head which achieves refill characteristics and strength of a division wall located between supply passages.SOLUTION: An embodiment of the invention relates to a substrate for a liquid discharge head including: a silicon substrate having a first surface and a second surface at the opposite side of the first surface; a discharge energy generation element disposed on the first surface of the silicon substrate; and supply passages penetrating through the first surface and the second surface of the silicon substrate. Each supply passage comprises: a first opening part opening on the first surface; a second opening part leading to a second surface side opening of the first opening part; and a third opening part which leads to a second surface side opening of the second opening part and opens on the second surface. The second surface side opening of the second opening part is wider than the first surface side opening of the second opening part. The third opening part has a side wall which is substantially perpendicular to a substrate surface.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a liquid discharge head substrate and a method for manufacturing the same.

  As described in Patent Document 1, there is a liquid discharge head in which two liquid supply paths are arranged symmetrically with respect to the discharge port in order to stably make the direction of the droplet flying from the discharge port perpendicular. As a method of forming such a liquid discharge head, there is a method of performing a two-stage etching process on a silicon substrate. In Patent Document 1, first, a concave portion (common supply path) serving as a common liquid chamber is formed in the substrate by crystal anisotropic etching, and then a plurality of independent supply paths are formed at the bottom of the concave portion by dry etching. .

JP 2012-45924

  Here, in order to increase the number of chips that can be obtained from one wafer, it is conceivable to form a common supply path in the vertical direction by dry etching or the like. However, when the common supply path is formed in the vertical direction and the interval between the adjacent common supply paths is reduced, the side walls separating the common supply paths become thinner, and the strength of the side walls, particularly the strength of the base portion of the side walls, where durability is required. May become insufficient. Further, if the side walls are formed thick in order to increase the side wall strength, the volume (volume) of the common supply path may be reduced and the refill characteristics may be insufficient.

  Therefore, an object of the present invention is to provide a liquid discharge head substrate that can easily achieve both the refill characteristics and the strength of the side wall (particularly the base portion) of the supply path.

The present invention
A silicon substrate having a first surface and a second surface opposite to the first surface; an ejection energy generating element disposed on the first surface of the silicon substrate; and the first surface of the silicon substrate. A liquid discharge head substrate having a supply path penetrating the first surface and the second surface,
The supply path is
A first opening opening in the first surface;
A second opening leading to an opening on the second surface side of the first opening;
A third opening leading to the opening on the second surface side of the second opening and opening in the second surface;
Consisting of
The opening on the second surface side of the second opening is wider than the opening on the first surface side of the second opening,
The third opening is a substrate for a liquid discharge head, having a side wall that is substantially perpendicular to the substrate surface.

  According to the configuration of the present invention, it is possible to provide a liquid discharge head substrate that can easily achieve both the refill characteristics and the strength of the side wall (particularly the base portion) of the supply path.

FIG. 3 is a partially cut perspective view illustrating a configuration example of a liquid discharge head according to an embodiment of the present invention. It is typical process sectional drawing for demonstrating the method to etch a board | substrate. It is typical process sectional drawing for demonstrating the method to etch a board | substrate. It is typical process sectional drawing for demonstrating the method to etch a board | substrate. It is process sectional drawing for demonstrating the manufacturing process of one Embodiment (or Example 1) of this invention. It is process sectional drawing for demonstrating the manufacturing process of one Embodiment (or Example 2) of this invention. It is process sectional drawing for demonstrating the manufacturing process of one Embodiment (or Example 3) of this invention. It is process sectional drawing for demonstrating the manufacturing process of one Embodiment of this invention.

  A liquid ejection head substrate according to an embodiment of the present invention includes a silicon substrate having a first surface (also referred to as a front surface) and a second surface (also referred to as a back surface) opposite to the first surface; A discharge energy generating element disposed on the first surface of the silicon substrate; and a supply path penetrating the first surface and the second surface of the silicon substrate. The supply path includes a first opening that opens to the first surface, a second opening that communicates with an opening on the second surface side of the first opening, and the second opening A third opening that communicates with the opening on the second surface side and opens on the second surface. In addition, the opening on the second surface side of the second opening is wider than the opening on the first surface side of the second opening, and the third opening is substantially the same as the substrate surface. Has side walls that are vertical.

  According to the configuration of the present embodiment, it is possible to provide a liquid discharge head substrate that can easily achieve both the refill characteristics and the strength of the supply path. More specifically, according to the configuration of the present invention, since the silicon substrate portion is left at the base portion of the side wall (including the partition wall), it is possible to easily increase the strength of the base portion of the side wall where durability is required. Since the three openings are formed in a substantially vertical direction, the supply path volume can be easily increased. Therefore, both the refill characteristics and the partition wall strength between the supply paths can be easily achieved. Further, by providing a second opening between the first opening and the third opening, when pressure is applied to the substrate (for example, when nozzle formation is performed using a tenting technique). Since the pressure applied to the corners of the third opening is easily dispersed, the durability can be improved.

  Hereinafter, this embodiment will be described with reference to the drawings.

  The liquid discharge head including the substrate for the liquid discharge head according to the present invention is a combination of a printer, a copying machine, a facsimile having a communication system, a word processor having a printer unit, and various processing apparatuses. It can be mounted on a recording device. By using this liquid discharge head, recording can be performed on various recording media such as paper, thread, fiber, leather, metal, plastic, glass, wood, and ceramic. In the present invention, “recording” means not only giving an image having a meaning such as a character or a figure to a recording medium but also giving an image having no meaning such as a pattern. Further, the term “liquid” is to be interpreted widely, and is applied to a recording medium to form an image, a pattern, a pattern, or the like, process the recording medium, or process ink or recording medium. It shall refer to the liquid provided. Here, as the treatment of the ink or the recording medium, for example, the fixing property is improved by coagulation or insolubilization of the coloring material in the ink applied to the recording medium, the recording quality or coloring property is improved, and the image durability is improved. Say that.

  In the following description, an inkjet recording head substrate will be described as a main application example of the present invention, but the scope of the present invention is not limited to this. Further, the liquid discharge head substrate can be applied to the manufacture of a liquid discharge head for biochip manufacturing and electronic circuit printing as well as an inkjet recording head substrate.

  FIG. 1 is a schematic perspective sectional view showing a configuration example of a liquid discharge head including the liquid discharge head substrate of the present embodiment. The liquid discharge head shown in FIG. 1 includes a liquid discharge head substrate and a flow path forming member 6 formed on the liquid discharge head substrate.

  The liquid discharge head substrate includes a silicon substrate 1 and an energy generating element 2 that generates energy for discharging the liquid formed on the first surface (front surface) 1A of the silicon substrate 1. The silicon substrate 1 has a supply path 30 as a through-hole penetrating the first surface and the second surface (back surface) 1B opposite to the first surface, and the supply path 30 is a first opening. It comprises a part 3, a second opening 4 and a third opening 5. The first opening 3 communicates with the first surface, the second opening 4 communicates with the opening of the first opening (the opening on the second surface side), and the third opening 5 communicates with the second surface. It leads to the opening of the opening (the opening on the second surface side) and the second surface. The opening on the second surface side of the second opening 4 is formed wider than the opening on the first surface side of the second opening. The side wall of the second opening 4 is inclined with respect to the direction perpendicular to the substrate surface. That is, the second opening 4 is formed by a side wall formed in an oblique direction with respect to the vertical direction of the substrate surface. A cross section of the second opening 4 by a plane parallel to the substrate surface gradually widens from the first surface toward the second surface. Moreover, the side walls of the first opening 3 and the third opening 5 are formed in a direction substantially perpendicular to the substrate surface. In the present invention, “substantially perpendicular” includes an allowable manufacturing error range, for example, a range of 86 ° to 94 ° with respect to the substrate surface.

  The supply path 30 has a role of supplying a liquid such as ink from the second surface side toward the first surface side. Further, it can be considered that the second opening 4 and the third opening 5 function as a common supply path in the liquid discharge head substrate shown in FIG. The first opening 3 can be regarded as an independent supply path that leads to the common supply path.

  In FIG. 1, the discharge energy generating elements 2 are formed in a row at a predetermined pitch, and the opening (first surface side opening) of the first opening 3 as an independent supply path is the discharge energy generating element. The two rows are arranged in rows on both sides.

  The flow path forming member 6 forms a discharge port 8 and a liquid flow path 7 communicating with the discharge port 8. A liquid such as ink supplied from the supply path to the liquid flow path 7 flies from the discharge port 8 by the discharge energy generated by the discharge energy generating element 2 and is applied to the recording medium.

  Embodiments of a manufacturing method will be described below with reference to the drawings.

(Embodiment 1)
5 and 6 are schematic process cross-sectional views for explaining the process in the manufacturing method of the present embodiment. 5 and 6 are cross-sectional process diagrams of portions corresponding to the cross-sectional portion shown in FIG.

  This embodiment has the following processes. (1) A step of performing etching from the first surface side to form the first opening. (2) A step of etching from the second surface side to form the third opening. (3) A step of performing etching from the first opening or the third opening to connect the first opening and the third opening to form the second opening. The order of the steps (1) and (2) is not particularly limited.

  First, as shown in FIG. 5A, a silicon substrate 101 having a first surface (front surface) and a second surface (back surface) opposite to the first surface is prepared. A plurality of ejection energy generating elements 102 are arranged on the first surface of the silicon substrate 101. A protective layer 103 and a seed layer (not shown) are formed on the first surface of the silicon substrate 101.

  Next, as shown in FIG. 5B, an etching mask material is disposed on the protective layer 103, and the etching mask material is patterned into a desired pattern using a photolithography technique, so that the first etching mask 104 is formed. Form. The first etching mask 104 has a first opening pattern corresponding to the opening pattern of the independent supply path. The protective layer 103 is etched through the first etching mask 104 to expose the substrate surface. The second etching mask 105 has a second opening pattern corresponding to the opening pattern of the common supply path.

  As the etching mask material, for example, a positive resist can be used, and specifically, iP5700 (trade name, manufactured by Tokyo Ohka Kogyo Co., Ltd.) can be given. A second etching mask 105 is also formed on the second surface by the same method.

  Next, as shown in FIG. 5C, the silicon substrate is etched from the first surface side through the first etching mask 104 to form the first opening 113.

  The first opening 113 is preferably formed in a direction substantially perpendicular to the substrate surface. That is, the side wall of the first opening 113 is preferably formed substantially perpendicular to the substrate surface. In addition, the etching for forming the first opening 113 is not particularly limited, and isotropic etching and anisotropic etching are exemplified. As isotropic etching, reactive ion etching is preferable, and reactive ion etching using a Bosch process is more preferable. As anisotropic etching, crystal anisotropic etching is preferable. Further, it is preferable that reactive ion etching using a Bosch process is used as etching for forming the first opening, and the first opening is formed in a direction substantially perpendicular to the substrate surface.

  The depth (distance in the substrate thickness direction, d3 in FIG. 1) of the first opening 113 is, for example, not less than 50 μm and not more than 150 μm.

  Next, as shown in FIG. 5D, a tape is attached on the first surface of the silicon substrate 101 to form an etching stop layer A. The tape can be made of a material that is not easily damaged by the etching gas. As a material for the tape, for example, a positive resist can be used, and specifically, an isopropyl tape (trade name, manufactured by Sumitomo Chemical Co., Ltd.) can be used.

  Next, as shown in FIG. 5E, the silicon substrate is etched from the second surface side through the second etching mask 105 to form a third opening 115. The third opening 115 is formed in a direction substantially perpendicular to the substrate surface. That is, the side wall of the third opening 115 is formed substantially perpendicular to the substrate surface.

  Examples of the etching for forming the third opening 115 include crystal anisotropic etching and reactive ion etching using a Bosch process. Among these, reactive ion etching using a Bosch process is preferable.

  The depth (distance in the substrate thickness direction, d5 in FIG. 1) of the third opening 115 is, for example, not less than 425 μm and not more than 575 μm.

  Next, as shown in FIG. 5 (f), the silicon substrate is etched from the third opening 115, the third opening 115 is spatially communicated with the first opening 113, and the second opening A portion 114 is formed. Thereby, the supply path as a through hole is formed. The opening on the second surface side of the second opening is formed wider than the opening on the first surface side of the second opening.

  The second opening is preferably formed such that a cross section of the second opening by a plane parallel to the substrate surface gradually widens from the first surface toward the second surface. In addition, the side wall of the second opening is preferably formed in an oblique direction with respect to the direction perpendicular to the substrate surface. Moreover, it is preferable that the opposing side wall of the second opening is formed in a symmetrical shape inclined with respect to the vertical direction of the substrate surface. In addition, all the side walls of the second opening are in relation to the substrate surface so that a cross section of the second opening by a plane parallel to the substrate surface gradually widens from the first surface toward the second surface. It is preferable to form it diagonally.

  The angle between the substrate surface and the side wall of the second opening is preferably 50 ° or more and 80 ° or less. The angle between the substrate surface and the side wall of the second opening is a cross section of the second opening by a plane that passes through the opening center on the second surface side of the second opening and is perpendicular to the substrate surface. , A line connecting the first surface side end portion (first end portion) and the second surface side end portion (second end portion) of the side wall, and the substrate surface (second surface) Can be defined as the angle formed by

  The supply path preferably has a portion where the side wall end on the second surface side of the first opening coincides with the side wall end on the first surface side of the second opening. In other words, the supply path preferably has a portion where the side wall end on the second surface side of the first opening and the side wall end on the first surface side of the second opening are connected.

  The supply path preferably has a portion where the side wall end on the first surface side of the third opening coincides with the side wall end on the second surface side of the second opening. That is, the supply path preferably has a portion where the side wall end on the first surface side of the third opening is connected to the side wall end on the second surface side of the second opening. More preferably, the side wall end on the first surface side of the third opening coincides with the side wall end on the second surface side of the second opening.

  As the etching for forming the second opening 114, it is preferable to use crystal anisotropic etching or reactive ion etching using a Bosch process. FIG. 5 shows an example in which the second opening 114 is formed from the third opening 115 using reactive ion etching using a Bosch process. When the second opening is formed by crystal anisotropic etching, a protective film can be appropriately provided on a necessary portion such as a side wall of the third opening or a side wall of the first opening.

  Note that a method of performing etching so that the opening width becomes narrower in the etching progress direction by using reactive ion etching using the Bosch process will be described in detail below.

  The depth (distance in the substrate thickness direction, d4 in FIG. 1) of the second opening 114 is, for example, 100 to 150 μm.

  The ratio of the depth of the second opening 114 to the depth of the third opening 115 is preferably 100: 525 to 150: 475, and more preferably 115: 510 to 135: 490. . The ratio of the depth of the first opening 113 to the depth of the second opening 114 is preferably 125: 100 to 75: 150, and more preferably 110: 135 to 90: 115.

  The ratio of the cross-sectional area A at the upper end (first surface side end) and the cross-sectional area B at the lower end (second surface side end) in the cross section of the second opening by a plane parallel to the substrate surface. Is preferably 676: 100 to 201: 100, and more preferably 547: 100 to 237: 100.

  Next, as shown in FIG. 5G, the etching stop layer A is removed, and the first etching mask 104 and the second etching mask 105 are removed.

  In the embodiment shown in FIG. 6, the silicon substrate is etched from the first opening 113 to form the second opening 114, and the first opening 113 communicates spatially with the third opening 115. Let At this time, as the etching progresses from the first opening 113, the etching is performed so that the opening width is widened to form the second opening 114. In the embodiment shown in FIG. 6, the order of the step of forming the first opening 113 and the step of forming the third opening 115 are reversed from the order of the embodiment shown in FIG. 5.

  The steps from FIG. 6A to FIG. 6B are the same as the steps from FIG. 5A to FIG.

  Next, as shown in FIG. 6C, the silicon substrate is etched from the second surface side through the second etching mask, and the third opening 115 is formed in a direction substantially perpendicular to the substrate surface. To do.

  Next, as illustrated in FIG. 6D, a tape is attached on the second surface of the silicon substrate 101 to form an etching stop layer B.

  Next, as shown in FIG. 6E, the silicon substrate is etched from the first surface side to form a first opening 113.

  Next, as shown in FIG. 6 (f), the silicon substrate is etched from the first opening 113 to form the second opening 114, and the first opening 113 is changed to the third opening 115. Spatial communication. Thereby, the supply path as a through hole is formed.

  As etching for forming the second opening 114, isotropic etching is preferably used. As the isotropic etching, reactive ion etching can be preferably exemplified. In particular, it is preferable to use reactive ion etching using a Bosch process.

  Note that details of a method of etching so that the opening width is widened in the etching progress direction by using reactive ion etching using the Bosch process will be described later.

  Next, as shown in FIG. 6G, the etching stop layer B is removed, and the first etching mask 104 and the second etching mask 105 are removed.

  According to this embodiment, it is possible to obtain a liquid discharge head substrate that can easily achieve both the refill characteristics and the strength of the partition walls between the supply paths. According to this embodiment, even when the discharge port density is increased to increase the number of chips that can be obtained from one wafer, the strength of the partition can be increased because the substrate portion remains at the base of the partition. In addition, since the third opening is formed in a substantially vertical direction, the supply path volume can be increased. Therefore, both the refill characteristics and the partition wall strength between the supply paths can be easily achieved.

  In the present embodiment, a plurality of first openings communicate with one third opening. In the form shown in FIG. 5, one second opening communicates with one third opening, and a plurality of first openings communicate with one second opening. doing. In the form shown in FIG. 6, a plurality of second openings communicate with one third opening, and one first opening for each of the plurality of second openings. Each part communicates.

(Embodiment 2)
FIG. 7 is a schematic process cross-sectional view for explaining a process in the manufacturing method according to another embodiment of the present invention. FIG. 7 is a sectional process diagram of a portion corresponding to the sectional portion shown in FIG.

  This embodiment has the following processes. (1) A step of performing etching from the first surface side to form the first opening. (2) A step of performing etching from the first opening to form the second opening. (3) A step of performing etching from the second opening to form the third opening.

  Hereinafter, this embodiment will be described with reference to FIG. In this embodiment, the supply path is formed by etching from the first surface of the silicon substrate.

  The process shown in FIG. 7A is the same as the process shown in FIG.

  As shown in FIG. 7B, an etching mask 104 is formed on the first surface of the silicon substrate 101. Further, an etching stop layer C is formed on the second surface of the silicon substrate 101.

  Next, as shown in FIG. 7C, etching is performed from the first surface side through the etching mask 104 to form the first opening 113.

  The etching for forming the first opening 113 is not particularly limited, and isotropic etching and anisotropic etching are exemplified. As isotropic etching, reactive ion etching is preferably exemplified, and reactive ion etching using a Bosch process is more preferred. As anisotropic etching, crystal anisotropic etching is preferably mentioned. Further, it is preferable that reactive ion etching using a Bosch process is used as etching for forming the first opening, and the first opening is formed in a direction substantially perpendicular to the substrate surface.

  Next, as shown in FIG. 7D, etching is performed from the first opening to form the second opening 114.

  As etching for forming the second opening 114, isotropic etching is preferably used. As the isotropic etching, reactive ion etching can be preferably exemplified. In particular, it is preferable to use reactive ion etching using a Bosch process.

  Next, as shown in FIG. 7E, the third opening 115 is formed by etching from the second opening 114.

  As the etching for forming the third opening 115, it is preferable to use reactive ion etching using crystal anisotropic etching or a Bosch process. When the third opening is formed by crystal anisotropic etching, a protective film can be appropriately provided on a necessary portion such as the side wall of the second opening or the side wall of the first opening.

  Next, as shown in FIG. 7F, the etching stop layer C is removed, and the first etching mask 104 is removed.

  According to the present embodiment, the liquid discharge head substrate of the present embodiment can be easily manufactured by etching from the first surface side.

  In the form shown in FIG. 7, one second opening communicates with one third opening, and one first opening communicates with one second opening. .

  In the embodiment shown in FIG. 7, there is no concept of an independent supply path or a common supply path as shown in FIGS. 5 and 6, one first opening, one second opening, and one third. A plurality of supply paths formed of the openings are formed. However, also in the manufacturing method of this embodiment, as shown in FIG. 8, a supply path in which a plurality of independent supply paths are connected to one common supply path can be formed. This can be achieved by adjusting the arrangement pattern of the openings of the etching mask, adjusting the etching conditions of the first opening, the etching conditions of the second opening, or the like.

(Embodiment 3)
This embodiment is a manufacturing method in which a supply path is formed by etching from the second surface, contrary to the method of the second embodiment described with reference to FIG.

  This embodiment has the following processes. (1) A step of etching from the second surface side to form the third opening. (2) A step of etching from the third opening to form the second opening. (3) A step of etching from the second opening to form the first opening.

  First, an etching mask is formed on the second surface of the silicon substrate. An etching stop layer is formed on the first surface of the silicon substrate.

  Next, etching is performed from the second surface side through an etching mask to form a third opening. Examples of the etching for forming the third opening include crystal anisotropic etching and reactive ion etching using a Bosch process. Among these, it is preferable to use reactive ion etching using a Bosch process.

  Next, etching is performed from the third opening to form the second opening. Examples of the etching for forming the second opening include reactive ion etching using crystal anisotropic etching or a Bosch process. Among these, reactive ion etching using a Bosch process is preferable.

  Next, etching is performed from the second opening to form the first opening. The etching for forming the first opening is not particularly limited and includes isotropic etching and anisotropic etching. As isotropic etching, reactive ion etching is preferably exemplified, and reactive ion etching using a Bosch process is more preferred. As anisotropic etching, crystal anisotropic etching is preferably mentioned. In addition, it is preferable to form the first opening in a direction substantially perpendicular to the substrate surface by using reactive ion etching using a Bosch process.

  Next, the etching stop layer is removed, and the etching mask is removed.

  According to the present embodiment, the liquid discharge head substrate of the present embodiment can be easily manufactured by etching from the second surface side.

  In the present embodiment as well, a supply path composed of one first opening, one second opening, and one third opening can be formed, and one common supply path can be formed. A supply path connecting a plurality of independent supply paths can be formed.

(Reactive ion etching using the Bosch process)
As described above, the method for forming the first opening, the second opening, and the third opening includes reactive ion etching using a Bosch process. In reactive ion etching, etching is performed using accelerated ions, and a reactive ion etching apparatus includes a plasma generation apparatus that generates ions and a reaction chamber that performs etching. For example, when an ICP (inductively coupled plasma) dry etching apparatus capable of generating high density ions is used, the silicon substrate can be etched vertically by alternately performing coating and etching. As the etching gas, for example, SF ₆ gas can be used, and as the gas for forming the passivation layer, for example, C ₄ F ₈ gas or CHF ₃ gas can be used. In this embodiment, the supply path is preferably formed by dry etching using an ICP plasma apparatus, but a dry etching apparatus having a plasma source of another method may be used. For example, an apparatus having an ECR (electron cyclotron resonance) ion source can be used.

  Further, with reference to FIG. 2, conditions for reactive ion etching using the Bosch process will be described. The Bosch process is a technique in which etching is performed by repeatedly performing an etching step and a passivation layer forming step as shown in FIGS. First, as shown in FIG. 2A, the silicon substrate is etched to form a first etching groove. Next, a first passivation layer is formed in the first etching groove to protect the wall surface of the first etching groove. Next, as shown in FIG. 2C, the bottom of the first passivation layer is etched to expose a region to be the next etching start surface. Next, as shown in FIG. 2D, the silicon substrate exposed by etching the first passivation layer is etched to form a second etching groove. Then, as shown in FIG. 2E, a second passivation layer is formed in the second etching groove. Thus, the silicon substrate can be etched by repeating the etching process and the passivation layer forming process. Then, by controlling the respective conditions of the etching step and the passivation layer forming step, the opening can be formed in a direction substantially perpendicular to the substrate surface, or the opening widens in the etching progress direction. Or can be formed to be narrow.

When the opening is formed in the vertical direction, the etching time is preferably set to 10 seconds or more and 20 seconds or less per cycle, and the passivation layer forming time is preferably set to 1 second or more and 10 seconds or less per cycle. Regarding the vacuum degree of the reactive ion etching at this time, the gas pressure (absolute pressure) is preferably set to 0.1 Pa or more and 50 Pa or less. The flow rate of SF ₆ gas is preferably set to 50 sccm or more and 1000 sccm or less, and the flow rate of C ₄ F ₈ is preferably set to 50 sccm or more and 1000 sccm or less. In particular, in order to achieve a high vacuum, the gas pressure is preferably set to 0.5 Pa or more and 10 Pa or less.

  A method of forming the opening so that the opening width becomes wider with respect to the etching progress direction will be described with reference to FIG. 3A to 3C are the same as the steps in FIGS. 2A to 2C, the description thereof will be omitted. In the etching step shown in FIG. 3D, the opening width (or opening area) of the second etching groove is increased by making the etching time longer than when the opening shown in FIG. 2 is formed in the vertical direction. Can do. When etching is performed so that the opening width increases toward the etching progress method, the passivation layer formation time is set to 1 second or more and 10 seconds or less per cycle, and the etching time is set to 10 seconds or more and 30 seconds or less per cycle. It is preferable. In addition, by appropriately selecting etching conditions such as gas pressure and ion species, the opening can be formed so that the opening width is widened in the etching progress direction.

  A method of forming the opening so that the opening width becomes narrower in the etching progress direction will be described with reference to FIG. 4A to 4B are the same as the steps in FIGS. 2A to 2B, and the description thereof is omitted. In FIG. 4C, the area where the silicon substrate is exposed is reduced by shortening the etching time of the passivation layer compared to the case shown in FIG. Further, in FIG. 4D, the opening time (opening area) of the second etching groove is reduced by shortening the etching time as compared with the case shown in FIG. By proceeding the etching in this way, the opening can be formed so that the opening width becomes narrower in the etching progress direction. When etching is performed so that the opening width becomes narrower toward the etching progress method, the passivation layer formation time is set to 5 to 20 seconds per cycle, and the etching time is set to 5 seconds or more and 20 seconds or less per cycle. Is preferred. In addition, by appropriately selecting etching conditions such as gas pressure and ion species, the opening can be formed so that the opening width becomes narrower in the etching progress direction.

  In the above description, reactive ion etching using the Bosch process has been described as an example. However, the present invention is not limited to the Bosch process. For example, it is possible to set conditions by changing the coil power and the platen power so that the inclined etching with respect to the substrate surface is possible and the process is set in the same way.

  Examples of the present invention will be described below. In addition, this invention is not limited to the following Example.

Example 1
A present Example is described with reference to Fig.5 (a)-(g).

  First, as shown in FIG. 5A, a silicon substrate 101 having a first surface (front surface) and a second surface (back surface) opposite to the first surface was prepared. A plurality of ejection energy generating elements 102 are arranged on the first surface of the silicon substrate 101. A protective layer 103 is formed on the first surface of the silicon substrate 101. Specifically, the ejection energy generating element is made of TaSiN, the protective layer is made of SiO, and the seed layer is made of gold.

  Next, as shown in FIG. 5B, an etching mask material is arranged on the protective layer 103 using a positive resist, and the etching mask material is patterned into a desired pattern using a photolithography technique. A first etching mask 104 was formed. IP5700 (trade name, manufactured by Tokyo Ohka Kogyo Co., Ltd.) was used as an etching mask material. A second etching mask 105 was also formed on the second surface by the same method.

  Next, as shown in FIG. 5C, the silicon substrate is etched from the first surface side by reactive ion etching using a Bosch process through the first etching mask 104, and the first opening 113 is formed. Formed. Specifically, the first opening 113 was formed to a depth of 100 μm from the first surface with respect to the thickness of 725 μm of the silicon substrate 101. The first opening 113 was formed in a direction perpendicular to the substrate surface.

In the reactive ion etching using the Bosch process at this time, the etching step and the passivation layer forming step were repeated a plurality of times. The formation time of the passivation layer was 5 seconds per cycle, and the etching time was 15 seconds per cycle. The reactive ion etching conditions were such that the gas pressure (absolute pressure) was 5 Pa, the SF ₆ gas flow rate was 500 sccm, and the C ₄ F ₈ gas flow rate was 500 sccm.

  Next, as shown in FIG. 5 (d), a tape was affixed on the first surface of the silicon substrate 101 to form an etching stop layer A. As the tape, a material that is not easily damaged by the etching gas can be used. As the material of the tape, a positive resist is used, and specifically, an Icros tape (trade name, manufactured by Sumitomo Chemical Co., Ltd.) is used.

  Next, as shown in FIG. 5E, the silicon substrate is etched from the second surface side by reactive ion etching using a Bosch process through the second etching mask 105, and the third opening 115 is formed. Formed. The third opening 115 was formed with a depth of 400 μm from the second surface. The third opening 115 was formed in a direction perpendicular to the substrate surface.

In the reactive ion etching using the Bosch process at this time, the formation time of the passivation layer was set to 5 seconds per cycle, and the etching time was set to 15 seconds per cycle. The reactive ion etching conditions were such that the gas pressure (absolute pressure) was 5 Pa, the SF ₆ gas flow rate was 500 sccm, and the C ₄ F ₈ gas flow rate was 500 sccm.

  Next, as shown in FIG. 5F, the silicon substrate is etched from the third opening 115 by reactive ion etching using a Bosch process to form the second opening 114, and the third opening The portion 115 is communicated with the first opening 113. Thereby, the supply path as a through-hole was formed.

In the reactive ion etching using the Bosch process at this time, the etching time is made shorter than the etching time when the opening is formed in the vertical direction like the first opening and the third opening. Set to. By setting the etching process time in this manner, the opening width can be gradually reduced as etching progresses toward the first surface. More specifically, the formation time of the passivation layer was 10 seconds per cycle, and the etching time was 10 seconds per cycle. The reactive ion etching conditions were such that the gas pressure (absolute pressure) was 5 Pa, the SF ₆ gas flow rate was 500 sccm, and the C ₄ F ₈ gas flow rate was 500 sccm.

  Next, as shown in FIG. 5G, the etching stop layer A was removed, the first etching mask 104 and the second etching mask 105 were removed, and a liquid discharge head substrate was obtained.

(Example 2)
In Example 2, the silicon substrate was etched from the first opening 113 to form the second opening 114, and the first opening 113 was communicated with the third opening 115. In the second embodiment, the order of the process of forming the first opening 113 and the process of forming the third opening 115 is reversed from the order of the first embodiment.

  Hereinafter, Example 2 will be described with reference to FIGS.

  Since FIGS. 6A to 6B are the same steps as FIGS. 5A to 5B of the first embodiment, description thereof will be omitted.

  Next, as shown in FIG. 6C, the silicon substrate was etched by reactive ion etching using a Bosch process to form a third opening 115. The third opening 115 was formed in the silicon substrate (thickness: 725 μm) at a depth of 400 μm from the second surface in a direction perpendicular to the substrate surface.

  Next, as shown in FIG. 6D, a tape was attached on the second surface of the silicon substrate 101 to form an etching stop layer B. As the tape, Icros tape (trade name, manufactured by Sumitomo Chemical Co., Ltd.) was used.

  Next, as shown in FIG. 6E, the silicon substrate was etched from the first surface side by reactive ion etching using a Bosch process to form a first opening 113. The first opening 113 was formed at a depth of 100 μm from the first surface of the silicon substrate and in a direction perpendicular to the substrate surface.

  Next, as shown in FIG. 6 (f), the silicon substrate is etched from the first opening 113 by reactive ion etching using a Bosch process, and the first opening 113 is changed to the third opening 115. The second opening 114 was formed by communication. Thereby, the supply path as a through-hole was formed.

At this time, the reactive ion etching using the Bosch process is such that the etching time is longer than the etching time for forming the opening in the vertical direction like the first opening and the third opening. Set to. By setting the etching time in this way, it can be processed into a shape in which the opening width gradually increases as the etching progresses to the second surface side. More specifically, the formation time of the passivation layer was set to 5 seconds per cycle, and the etching time was set to 25 seconds per cycle. The reactive ion etching conditions were such that the gas pressure (absolute pressure) was 5 Pa, the gas flow rate of SF ₆ was 500 sccm, and the flow rate of C ₄ F ₈ was 500 sccm.

  Next, as shown in FIG. 6G, the etching stop layer B was removed, the first etching mask 104 and the second etching mask 105 were removed, and a liquid discharge head substrate was obtained.

(Example 3)
In Example 3, the supply path was formed by etching from the first surface of the silicon substrate. Hereinafter, Example 3 will be described with reference to FIGS.

  First, as shown in FIG. 7A, first, a silicon substrate on which an etching resistant mask layer was formed was prepared. Next, as shown in FIG. 7B, an etching mask 104 having a desired opening pattern was formed on the first surface of the silicon substrate 101. Moreover, the tape was affixed on the 2nd surface of the silicon substrate, and the etching stop layer C was formed. As the tape, Icros tape (trade name, manufactured by Sumitomo Chemical Co., Ltd.) was used. Next, as shown in FIG. 7C, the silicon substrate was etched by reactive ion etching using a Bosch process from the first surface side through the etching mask 104 to form the first opening 113. . The depth of the first opening 113 was 100 μm from the first surface. The etching conditions were the same as when the first opening of Example 1 was formed. Next, as shown in FIG. 7D, the second opening 114 was formed by reactive ion etching using a Bosch process. The depth of the second opening 114 was 225 μm from the end (bottom) of the first opening 113. The etching conditions were the same as when the second opening was formed in Example 2. Next, as shown in FIG. 7E, the silicon substrate was etched from the bottom of the second opening by reactive ion etching using a Bosch process to form a third opening 115. The etching conditions were the same as when the third opening in Example 1 was formed. Next, as shown in FIG. 7F, the etching mask 104 and the etching stop layer C were removed to obtain a liquid discharge head substrate.

DESCRIPTION OF SYMBOLS 1 Silicon substrate 2 Discharge energy generating element 3 1st opening part 4 2nd opening part 5 3rd opening part 101 Silicon substrate 102 Discharge energy generating element 103 Protective layer 104 Etching mask (1st etching mask)
105 Etching mask (second etching mask)
113 First opening 114 Second opening 115 Third opening A, B, C Etching stop layer

Claims (22)

A silicon substrate having a first surface and a second surface opposite to the first surface; an ejection energy generating element disposed on the first surface of the silicon substrate; and the first surface of the silicon substrate. A liquid discharge head substrate having a supply path penetrating the first surface and the second surface,
The supply path is
A first opening opening in the first surface;
A second opening leading to an opening on the second surface side of the first opening;
A third opening leading to the opening on the second surface side of the second opening and opening in the second surface;
Consisting of
The opening on the second surface side of the second opening is wider than the opening on the first surface side of the second opening,
The substrate for a liquid discharge head, wherein the third opening has a side wall substantially perpendicular to the substrate surface.   The liquid discharge head substrate according to claim 1, wherein a cross section of the second opening portion by a plane parallel to the substrate surface gradually increases from the first surface toward the second surface.   3. The liquid discharge head substrate according to claim 1, wherein a side wall of the second opening is inclined with respect to a direction perpendicular to the substrate surface.   An angle of the line connecting the first end on the first surface side and the second end on the second surface side in the side wall of the second opening with respect to the second surface is 50 ° or more. The substrate for a liquid discharge head according to claim 1, wherein the substrate is 80 ° or less.   5. The liquid discharge head substrate according to claim 1, wherein the first opening has a side wall that is substantially perpendicular to the substrate surface. 6.   The said supply path has the part which the side wall edge part by the side of the 2nd surface of said 1st opening part and the side wall edge part by the side of the 1st surface of said 2nd opening part are connected. 6. The liquid discharge head substrate according to any one of 5 above.   The said supply path has a part which the side wall edge part by the side of the 1st surface of the said 3rd opening part and the side wall edge part by the side of the 2nd surface of the said 2nd opening part are connected. 7. The liquid discharge head substrate according to any one of 6 above.   The liquid discharge head substrate according to claim 1, wherein a plurality of the first openings communicate with one third opening.   The one second opening communicates with one third opening, and the plurality of first openings communicate with one second opening. A substrate for a liquid discharge head according to 1.   The plurality of second openings communicates with one third opening, and the one first opening communicates with each of the plurality of second openings. The liquid discharge head substrate according to claim 8.   The one second opening communicates with one third opening, and the one first opening communicates with one second opening. 8. The liquid discharge head substrate according to any one of items 1 to 7. It is a manufacturing method of the substrate for liquid discharge heads according to any one of claims 1 to 11,
(1) etching from the first surface side to form the first opening;
(2) etching from the second surface side to form the third opening;
(3) performing etching from the first opening or the third opening, communicating the first opening and the third opening, and forming the second opening;
Manufacturing method of substrate for liquid discharge head having   The method of manufacturing a substrate for a liquid discharge head according to claim 12, wherein the step (3) is a step of forming the second opening by performing isotropic etching from the first opening.   The method for manufacturing a substrate for a liquid discharge head according to claim 13, wherein the isotropic etching is reactive ion etching using a Bosch process.   The step (3) is a step of forming the second opening by performing reactive ion etching using crystal anisotropic etching or a Bosch process from the third opening. Manufacturing method of substrate for liquid discharge head. It is a manufacturing method of the substrate for liquid discharge heads according to any one of claims 1 to 11,
(1) etching from the first surface side to form the first opening;
(2) etching from the first opening to form the second opening;
(3) etching from the second opening to form the third opening;
Manufacturing method of substrate for liquid discharge head having   The method for manufacturing a substrate for a liquid discharge head according to claim 16, wherein the etching in the step (2) is isotropic etching.   The method for manufacturing a substrate for a liquid discharge head according to claim 16, wherein the etching in the step (2) is reactive ion etching using a Bosch process.   The method for manufacturing a substrate for a liquid discharge head according to claim 17 or 18, wherein the etching in the steps (1) and (3) is reactive ion etching using a Bosch process. It is a manufacturing method of the substrate for liquid discharge heads according to any one of claims 1 to 11,
(1) etching from the second surface side to form the third opening;
(2) etching from the third opening to form the second opening;
(3) etching from the second opening to form the first opening;
Manufacturing method of substrate for liquid discharge head having   21. The method for manufacturing a substrate for a liquid discharge head according to claim 20, wherein the etching in the step (2) is reactive ion etching using a Bosch process.   The method for manufacturing a substrate for a liquid discharge head according to claim 20 or 21, wherein the etching in the steps (1) and (3) is reactive ion etching using a Bosch process.

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