JP2013043437A - Method of manufacturing flow path plate of liquid ejection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a flow path plate of a liquid ejection apparatus that can flatly process a sidewall of a through-hole.SOLUTION: There is provided the method of manufacturing the flow path plate of the liquid ejection apparatus having: a through-hole which penetrates one surface and the other surface of a silicon substrate whose plane direction is {110}; and a flow path which is formed at the side of the one surface and connected with the through-hole. The method of manufacturing the flow path plate includes: a mask forming process of forming a first mask on the one surface of the silicon substrate and forming a second mask on the first mask; a through-hole forming process of forming the through-hole by performing etching including, at least partially, dry etching through the second mask; and a sidewall processing process of performing crystal anisotropic etching for the through-hole through the first mask after removing the second mask, and then processing a sidewall of the through-hole so that a sidewall surface of the through-hole is formed of a plane of plane direction {111} of the silicon substrate.

Description

The present invention relates to a method for manufacturing a flow path plate of a liquid ejection device. In particular, the present invention relates to a method of manufacturing a flow path plate of a liquid ejection device that ejects liquid by an inkjet method or a bubble jet (registered trademark) method.

As an image forming apparatus such as a printer, a facsimile, a copying apparatus, and a multifunction machine of these, for example, an ink jet type liquid ejecting apparatus is known. The liquid ejection apparatus performs recording by ejecting ink droplets as a recording liquid onto a recording medium such as recording paper using an ink ejection head as a recording head.

A configuration example of such a liquid discharge apparatus is shown in FIG. FIG. 7A is a perspective view illustrating a schematic configuration of the liquid ejection device 30, and FIG. 7B is a cross-sectional view taken along the line BB illustrated in FIG. 7A. The liquid ejection device 30 illustrated in FIG. 7 includes a flow path plate 31, a vibration plate 32 bonded to the lower surface of the flow path plate 31, and a nozzle plate 33 bonded to the upper surface of the flow path plate 31. The lower surface of the vibration plate 32 includes a drive unit 34 for driving the vibration plate 32, and liquid such as ink is supplied from a chamber (liquid chamber) (not shown) provided in the drive unit 34 to the supply plate of the vibration plate 32. After being supplied to 32a and passing through the flow path 31a of the flow path plate 31, it is discharged from the nozzle 33a. For the nozzle plate 33 and the channel plate 31, for example, a silicon single crystal substrate is used in order to realize high-precision fine processing, and processing is performed using the MEMS technology. For example, in a conventional method of manufacturing a liquid ejection device, a nozzle or 33a of an ink ejection head is formed by so-called DRIE, in which holes or grooves are formed by repeating an etching process and a process of forming a polymer of a fluorine compound on a sidewall after the etching process. And there is one that forms the flow path 31a (see, for example, Patent Document 1).

JP 2005-224903 A

Dry etching techniques such as DRIE are considered useful because of their high anisotropy and high processing speed, and are commonly used in silicon processing. In dry etching such as DRIE, when viewed on a large scale of mm (millimeters) or more, it can be considered that the side walls of the groove portions forming the nozzles 33a and the flow paths 31a are processed substantially flatly. However, when the sidewall is viewed on a finer scale, various shapes unique to dry etching may be formed.

FIG. 8 is a schematic diagram for explaining an example of a sidewall shape of a groove portion generated by dry etching. As illustrated in FIG. 8, the shape of the side wall 52 (52a to 52d) of the groove 51 formed in the substrate 50 changes due to the processing conditions. FIG. 8 shows an example in which scallop (FIG. 8A), bowing (FIG. 8B), taper (FIG. 8C), tilt (FIG. 8D), etc. are generated. . As described above, the side wall 52 of the groove 51 is actually a non-flat surface, and a processing trace due to dry etching may remain. Further, conventionally, after etching from one surface of the substrate 50, etching is further performed from the other surface of the substrate 50 to form a through hole (not shown) penetrating the front and back of the substrate 50. It was. Also in this case, since etching proceeds from both surfaces of the substrate 50, a processing mark having a shape like a step may remain on the side wall.

However, in the flow path plate 31 for sending the liquid to the nozzle 33a, it is advantageous that the side wall of the flow path 31a is flat in order to improve the flight characteristics of the liquid. Therefore, in the above-described conventional method for manufacturing a liquid ejection device, the side walls of the holes or grooves forming the nozzles and flow paths have low flatness, which may reduce the liquid flight characteristics.

Accordingly, the present invention has been made in view of the above circumstances, and a main object thereof is to provide a technique capable of processing the side wall of the through hole flatly while forming the through hole by dry etching. .

The present invention includes the following inventions. According to one embodiment of the present invention, there is provided a method for manufacturing a flow path plate of a liquid ejection apparatus, wherein a through-hole penetrating one surface and the other surface of a silicon substrate whose surface orientation is {110}, and the one surface A flow path plate of a liquid ejection device formed on a side and connected to the through hole, wherein a first mask is formed on the one surface of the silicon substrate, A mask forming step of forming a second mask on one mask, a through hole forming step of performing etching including dry etching at least partially through the second mask to form the through hole, and the second mask Is removed, crystal anisotropic etching is performed on the through-hole through the first mask, and the side wall surface of the through-hole is configured by a plane of the plane orientation {111} of the silicon substrate. Side wall processing for processing the side wall of the through hole Characterized in that it comprises a step.

As another aspect of the present invention, the method further includes a stopper layer forming step of forming a stopper layer on the other surface of the silicon substrate, and a protective layer forming step of forming a protective layer on the stopper layer, In the hole forming step, the through hole may be formed using the stopper layer as an etching stopper.

As another aspect of the present invention, a third mask forming step of forming a third mask on the other surface of the silicon substrate, and a portion corresponding to the through hole are removed by etching the third mask. A step of exposing the silicon substrate, and a step of forming a protective layer on the third mask and the other surface of the silicon substrate, wherein the protective layer is formed in the through hole forming step. The through hole may be formed by using it as an etching stopper.

The second mask and the third mask may be formed such that the opening area of the third mask includes the opening area of the second mask.

The first mask, the third mask, and the stopper layer may each be a silicon oxide film formed on the one surface or the other surface by thermally oxidizing the silicon substrate.

The second mask and the protective layer may be a photoresist film formed on the one surface and the other surface of the silicon substrate, respectively.

The crystal anisotropic etching may be wet etching using a TMAH aqueous solution.

ADVANTAGE OF THE INVENTION According to this invention, the technique which can process the side wall of a through-hole flatly can be provided, forming a through-hole by dry etching.

It is a top view of the flow-path board of a liquid discharge apparatus. It is sectional drawing in the AA of the flow-path board shown in FIG. It is process sectional drawing for demonstrating the manufacturing method of the flow-path board of the liquid discharge apparatus which concerns on one Embodiment of this invention. It is process sectional drawing for demonstrating the manufacturing method of the flow-path board of the liquid discharge apparatus which concerns on one Embodiment of this invention. It is process sectional drawing for demonstrating the manufacturing method of the flow-path board of the liquid discharge apparatus which concerns on one Embodiment of this invention. It is process sectional drawing for demonstrating the manufacturing method of the flow-path board of the liquid discharge apparatus which concerns on one Embodiment of this invention. It is a figure which shows schematic structure of a liquid discharge apparatus, (A) is a perspective view of a liquid discharge apparatus, (B) is sectional drawing of the BB line shown to (A). It is a schematic diagram for demonstrating the side wall shape of the groove part formed by dry etching.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments described below, and various modifications can be made without departing from the technical idea. In the drawings, the scale may be exaggerated for explanation, and the scale may be different from the actual one.

(Flow path plate of liquid discharge device)
First, the flow path plate of the liquid ejection apparatus according to the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a plan view of a flow path plate 100 of the liquid ejection device. FIG. 2 is a cross-sectional view taken along the line AA of the flow path plate 100 shown in FIG. The flow path plate 100 includes a through hole 3 that penetrates one surface 1 a and the other surface 1 b of the silicon substrate 1, and a flow path 5 that is connected to the through hole 3. The flow path plate 100 may correspond to the flow path plate 31 of the liquid ejection device 30 illustrated in FIG. Further, the flow path plate 100 may include elements other than the through hole 3 and the flow path 5. Although not shown, the surface of the silicon substrate 1 and the side wall surface of the through hole 3 may be covered with a silicon oxide film (SiO ₂ ) or the like.

As the silicon substrate 1, a single crystal substrate having both surface orientations {110} can be used. One surface 1a of the silicon substrate 1 is a surface facing the diaphragm (see FIG. 7), and the other surface 1b of the silicon substrate 1 is a surface facing the nozzle plate (see FIG. 7). Although there is no restriction | limiting in particular in the thickness of the silicon substrate 1, For example, it is good to set it as the range of 100 micrometers-1000 mm, More preferably, it is good to set it as the range of 200 micrometers-700 micrometers.

The through hole 3 is a hole for connecting each nozzle of the nozzle plate (see FIG. 7) and the flow path 5. There is no restriction | limiting in the opening dimension of the through-hole 3, What is necessary is just to set suitably for every product specification. The through hole 3 is formed substantially perpendicular to the substrate surface, and the side wall of the through hole 3 has a substantially flat surface constituted by the surface orientation {111} of the silicon substrate 1. The plan view shape of the opening of the through hole 3 is a polygonal shape, and is typically a parallelogram. Although the details will be described later, the planar shape of the opening of the through hole 3 is substantially surrounded by a facet surface having a plane orientation {111} having a lower etching rate than other crystal planes in crystal anisotropic etching. Because.

The flow path 5 is a liquid passage that guides liquid such as ink pressurized by the vibration plate (see FIG. 7) to the through hole 3. There is no restriction | limiting in the width | variety and depth of the flow path 5, and what is necessary is just to set suitably for every product specification. The side walls of the flow path 5 are preferably formed substantially perpendicular to the substrate surface. The shape, number, layout, and the like of the through holes 3 and the flow paths 5 are examples, and are not limited to those illustrated in FIG.

The liquid ejected by the liquid ejecting apparatus using the flow path plate 100 according to the present invention is not particularly limited, and examples thereof include printing ink, electronic material, nanoimprint resist, and cell-containing liquid.

(Manufacturing method of flow path plate of liquid ejection device)
Next, a method for manufacturing the flow path plate 100 of the liquid ejection apparatus according to an embodiment of the present invention will be described with reference to FIGS.

Example 1
3 and 4 are process cross-sectional views for explaining a method for manufacturing the flow path plate 100 of the liquid ejection apparatus according to the first embodiment of the present invention. Hereinafter, description will be made in the order of steps.

(1) Thermal oxidation (see FIG. 3A)
A silicon substrate 1 made of a silicon single crystal having both surface orientations {110} is prepared. The silicon substrate 1 is thermally oxidized to form a silicon oxide film as a first mask 11 on one surface 1a of the silicon substrate 1 and a silicon oxide film as a stopper layer 12 on the other surface 1b. The thicknesses of the first mask 11 and the stopper layer 12 are not particularly limited, but may be in the range of 0.1 μm to 1 μm. More preferably, it is good to set it as the range of 0.3 micrometer-0.7 micrometer. The first mask 11 is patterned and functions as a mask when performing crystal anisotropic etching described later. The stopper layer 12 functions as an etching stopper when performing dry etching described later.

The first mask 11 and the stopper layer 12 are not limited to the silicon oxide film, and may be formed using, for example, a metal material having excellent alkali resistance. The first mask 11 and the stopper layer 12 may be formed using a material having a desired selection ratio in consideration of a selection ratio in dry etching and crystal anisotropic etching described later. For example, when forming the 1st mask 11 and the stopper layer 12 using a metal material, it is good to form into a film by well-known methods, such as a vapor deposition method, a sputtering method, CVD method, according to material.

(2) Patterning of the first mask 11 (see FIG. 3B)
A photoresist (not shown) is applied, exposed, and developed on the first mask 11 to pattern the photoresist. Using the patterned photoresist (not shown) as a mask, the first mask 11 is etched to pattern the first mask 11. A region where a part of the first mask 11 is removed and the one surface 1a of the silicon substrate 1 is exposed is a region corresponding to a through hole 3 and a flow path 5 formed in a process described later. The etching of the first mask 11 can be performed by, for example, RIE (Reactive Ion Etching).

(3) Double-sided resist placement (see Fig. 3 (C))
Photoresist is disposed on each side of the silicon substrate 1. Typically, it arrange | positions by coating methods, such as a spin coat method. Thus, the second mask 13 is formed on one surface 1a of the silicon substrate 1, and the protective layer 14 is formed on the other surface 1b. The second mask 13 is patterned and functions as a mask when dry etching described later is performed. The protective layer 14 reinforces the stopper layer 12 and functions as a mask for protecting the back surface. Photoresist application may be performed in any order on the one surface 1a and the other surface 1b, but is preferably performed first on the other surface 1b. By forming the protective layer 14 on the other surface 1b, the back surface of the silicon substrate 1 (corresponding to the other surface 1b) is applied on the stage of the coating apparatus or the exposure machine when the photoresist is applied on the one surface 1a side. This is because the silicon substrate 1 can be held by chucking the entire surface, and the photoresist on one surface 1a can be patterned while the flatness of the silicon substrate 1 is maintained. Thereby, the patterning of the second mask 13 can be performed with high accuracy. Although there is no restriction | limiting in the film thickness of the photoresist to apply | coat, For example, it is good to set it as the range of 1 micrometer-50 micrometers. More preferably, it is good to set it as the range of 3 micrometers-30 micrometers. If the thickness is less than 1 μm, the protective layer may be insufficient. If the thickness is greater than 50 μm, it may be difficult to form a photoresist in such a thick film shape. The photoresist is not limited to coating, and a film-like dry resist may be laminated.

The protective layer 14 is not limited to a photoresist, and may be formed using, for example, a protective film for manufacturing a semiconductor, a metal material having high chemical resistance, or the like.

(4) Patterning of the second mask 13 (see FIG. 3D)
The photoresist to be the second mask 13 is exposed and developed to pattern the photoresist. A region where a part of the second mask 13 is removed and the one surface 1a of the silicon substrate 1 is exposed is a region corresponding to a through hole 3 formed in a process described later. On one surface 1a of the silicon substrate 1, a first mask 11 and a second mask 13 are sequentially formed from the silicon substrate side. Note that three or more masks may be formed on one surface 1a of the silicon substrate 1 in consideration of the selection ratio in dry etching and crystal anisotropic etching described later, and the masks to be formed are limited to two layers. Is not to be done. However, it is preferable to use a two-layer mask as described above from the viewpoint of simplifying the manufacturing process.

(5) Dry etching (see FIG. 4A)
Using the second mask 13 as a mask, the silicon substrate 1 is etched by dry etching. The dry etching is preferably plasma etching, and for example, RIE or DRIE (Deep-RIE) can be used. Etching is started from one surface 1a of the silicon substrate 1, and etching is performed until the stopper layer 12 is exposed, thereby forming a through hole 3 penetrating the one surface 1a and the other surface 1b. At this time, the side wall 16 of the through hole 3 is not limited to the tapered shape illustrated in FIG. 4A, and may have a shape like the side wall 52 illustrated in FIG. 8, for example. After the dry etching, the second mask 13 and the protective layer 14 are removed. In the etching for forming the through-hole 3, dry etching may be used for at least a part. For example, a combination of dry etching and wet etching, a combination of processing such as dry etching and grinding, etc. are all performed by dry etching. It may be a thing. In particular, from the viewpoint of production efficiency, it is preferable to perform all of the through holes 3 by dry etching.

In dry etching, the surface of the silicon substrate 1 to be etched (corresponding to the one surface 1a) is irradiated with high-density plasma, so that the temperature of the silicon substrate 1 rises. A cooling helium (He) gas is supplied to the back surface (corresponding to the other surface 1b) of the silicon substrate 1 for the purpose of stabilizing the process by suppressing the temperature rise of the silicon substrate 1. When the stopper layer 12 is thin, the stopper layer 12 may disappear during the dry etching process, but even if the stopper layer 12 disappears by providing the protective layer 14, the cooling He gas leaks into the etching reaction chamber. Can be prevented. By using such a dry etching method, the side wall 16 of the through hole 3 is formed to be substantially perpendicular to the surface to be etched of the silicon substrate 1 while forming the through hole 3 by one etching. It becomes possible.

However, generally, the processing by dry etching has high productivity, but as described above with reference to FIG. 8, a shape peculiar to dry etching is formed on the side wall 16 of the through hole 3 formed by dry etching. Sometimes. Therefore, the present invention removes processing marks peculiar to dry etching seen in the side wall 16 of the through-hole 3 by crystal anisotropic etching, which will be described later, and the side wall 18 substantially constituted by a crystal plane having a specific plane orientation. A through-hole 3 having the following is formed.

(6) Crystal anisotropic etching (see FIG. 4B)
After removing the second mask 13 and the protective layer 14, the silicon substrate 1 is etched by crystal anisotropic etching using the first mask 11 as a mask, and the sidewalls of the through holes 3 and the flow paths 5 are formed. Crystal anisotropic etching is etching that utilizes the property that etching in a specific crystal direction is difficult to proceed as compared with other crystal directions. For example, a TMAH (4-methyl ammonium hydroxide) aqueous solution or a KOH (potassium hydroxide) aqueous solution can be used. In particular, as will be described later, it is preferable to perform crystal anisotropic etching with a TMAH aqueous solution. By using the TMAH aqueous solution or the KOH aqueous solution, it is possible to prevent the etching from proceeding to the crystal direction of the plane orientation {111} almost as compared with the etching for the other plane orientation. By using such crystal anisotropic etching, it is possible to form the through hole 3 in which the side wall 18 is substantially constituted by the facet surface of the plane orientation {111} and the flow path 5 connected to the through hole 3. it can.

According to a preferred aspect of the present invention, the crystal anisotropic etching may be performed with a TMAH aqueous solution. The KOH aqueous solution has a higher selectivity for the first mask 11 in the etching in the direction perpendicular to the substrate than the TMAH aqueous solution, but the selectivity for the first mask 11 is lower in the side etching than the TMAH aqueous solution. Therefore, it may be necessary to perform etching using a multilayer mask in order to perform a desired sidewall processing of the through hole 3. Therefore, the manufacturing process may be complicated. On the other hand, the TMAH aqueous solution has lower selectivity with respect to the first mask 11 in etching in the direction perpendicular to the substrate than the KOH aqueous solution, but has higher selectivity with respect to the first mask 11 in side etching than the KOH aqueous solution. Therefore, when the side wall processing of the desired through hole 3 is performed, the side wall processing of the through hole 3 and the formation of the flow path 5 can be performed with the first mask 11 of one layer. Therefore, the flow path plate 100 can be manufactured with a two-layer mask (the first mask 11 and the second mask 13) which is the minimum number of layers throughout the manufacturing process. In crystal anisotropic etching, when a facet surface having a plane orientation {111} appears, the etching can be substantially stopped. Therefore, a side wall surface (side wall 18) substantially perpendicular to the surface to be etched of the silicon substrate 1 is formed. It becomes possible to form the through-hole 3 having.

As described above, the shape peculiar to the dry etching seen in the side wall 16 (see FIG. 4A) of the through-hole 3 is substantially removed when the facet surface having the plane orientation {111} appears by being removed by the crystal anisotropic etching. Etching stops. Therefore, the etched side wall 18 shown in FIG. 4B is substantially constituted by a facet surface having a surface orientation {111}, and each surface has high flatness. Simultaneously with the processing of the side wall surface of the through hole 3, the etching proceeds to one surface 1 a of the silicon substrate 1, and the flow path 5 connected to the through hole 3 can be formed. Note that in this specification, the plane orientation is represented as {110}, but this is represented by (110) and includes a plane orientation equivalent to (110) due to the symmetry of the crystal structure.

As described above, the through-hole 3 and the flow path 5 having the side wall 18 substantially formed of the facet surface having the plane orientation {111} are formed. In a silicon substrate having a plane orientation {110} as the principal plane, when the silicon substrate is viewed from the crystal orientation of the plane orientation {110} (in this embodiment, a plan view), the plane with the plane orientation {111} is the principal plane of the silicon substrate. There is also a plane with a plane orientation of {111} in the direction of 70.5 ° with this. Therefore, the planar view shape of the opening of the through hole 3 is a polygon, typically a parallelogram having an acute angle of 70.5 °. Depending on the conditions of crystal anisotropic etching, it may not be a parallelogram, but may be a polygon having four intersection lines between the main surface of the silicon substrate and the surface of the plane orientation {111} on its side, Such a form may be sufficient.

The state substantially constituted by the plane orientation {111} means that when the planar view shape of the opening of the through-hole 3 is a polygon, four sides of the polygon are the principal plane of the silicon substrate and the plane orientation {111 } Is preferably represented by a line of intersection of the planes.

(7) Removal of first mask 11 and stopper layer 12 (see FIG. 4C)
By removing the first mask 11 and the stopper layer 12, the flow path plate 100 including the through holes 3 and the flow paths 5 is formed as illustrated in FIG. A step of performing thermal oxidation or the like later to form a silicon oxide film (not shown) on one side 1a, the other side 1b of the silicon substrate 1 and the side wall of the through hole 3 may be included.

As described above, according to the method of manufacturing the flow path plate 100 of the liquid ejection apparatus according to the first embodiment of the present invention, the through hole 3 is formed by etching including dry etching using at least two masks. By performing crystal anisotropic etching on the through-hole 3, the side wall surface of the through-hole 3 can be constituted by the plane of the silicon substrate {111}. After the through hole 3 is formed, the side wall surface of the through hole 3 can be processed into a substantially vertical and flat shape by crystal anisotropic etching using the first mask 11. As a preferred embodiment of the first embodiment of the present invention, a desired flow path plate 100 is manufactured in a simple process by using a two-layer mask and employing crystal anisotropic etching with high mask selectivity. Can do. According to the first embodiment of the present invention, by forming the flow path plate 100 having the through-hole 3, it is possible to provide a liquid ejection device with improved liquid flight characteristics.

(Example 2)
Next, with reference to FIG.5 and FIG.6, the manufacturing method of the flow-path board 100 of the liquid discharge apparatus which concerns on Example 2 of this invention is demonstrated. 5 and 6 are process cross-sectional views for explaining a method for manufacturing the flow path plate 100 of the liquid ejection apparatus according to the second embodiment of the present invention. Hereinafter, the description will be made in the order of steps, but the description of the same contents as those of the method for manufacturing the flow path plate 100 of the liquid ejection apparatus according to the first embodiment of the present invention described above with reference to FIGS. 3 and 4 will be omitted. I will do it.

(1) Thermal oxidation (see FIG. 5 (A))
A silicon substrate 1 made of a silicon single crystal having both surface orientations {110} is prepared. Similarly to the first embodiment, the silicon substrate 1 is thermally oxidized to form a silicon oxide film as the first mask 11 on one surface 1a of the silicon substrate 1 and a silicon oxide film as the third mask 15 on the other surface 1b. Similar to the first embodiment, the first mask 11 and the third mask 15 are not limited to the silicon oxide film, and may be formed by a known method using, for example, a metal material having excellent alkali resistance. The thickness of the first mask 11 and the third mask 15 is not particularly limited, but may be in the range of 0.1 μm to 1 μm, and more preferably in the range of 0.3 μm to 0.7 μm. The first mask 11 and the third mask 15 function as masks when performing crystal anisotropic etching described later.

(2) Patterning of the first mask 11 and the third mask 15 (see FIG. 5B)
A photoresist (not shown) is applied, exposed, and developed on the first mask 11 to pattern the photoresist (not shown). Using the patterned photoresist as a mask, the first mask 11 is etched and patterned. A region where a part of the first mask 11 is removed and the one surface 1a of the silicon substrate 1 is exposed is a region corresponding to a through hole 3 and a flow path 5 formed in a process described later. Etching of the first mask 11 can be performed by RIE (Reactive Ion Etching), for example, as in the first embodiment.

Similarly to the patterning of the first mask 11, a photoresist (not shown) is applied, exposed, and developed on the third mask 15, the photoresist is patterned, and the patterned photoresist is used as a mask. The third mask 15 is etched and patterned. A region 15b (hereinafter referred to as an opening region 15b) in which a part of the third mask 15 is removed and the other surface 1b of the silicon substrate 1 is exposed is a region corresponding to a through hole 3 formed in a process described later. It becomes.

(3) Double-sided resist placement (see Fig. 5 (C))
Photoresist is disposed on each side of the silicon substrate 1. Typically, it arrange | positions by coating methods, such as a spin coat method. As a result, like the first embodiment, the second mask 13 is formed on one surface 1a of the silicon substrate 1 and the protective layer 14 is formed on the other surface 1b. The second mask 13 functions as a mask when performing dry etching described later. Further, the protective layer 14 not only reinforces the third mask 15 and functions as a mask for protecting the back surface, but also functions as an etching stopper when performing dry etching described later. Although there is no restriction | limiting in the film thickness of the photoresist to apply | coat, For example, it is good to set it as the range of 1 micrometer-50 micrometers. More preferably, it is good to set it as the range of 3 micrometers-30 micrometers. If the thickness is less than 1 μm, the protective layer may be insufficient. If the thickness is greater than 50 μm, it may be difficult to form a photoresist in such a thick film shape. The photoresist is not limited to coating, and a film-like dry resist may be laminated.

Note that the protective layer 14 is not limited to a photoresist, as in Example 1, and may be formed using, for example, a protective film for semiconductor manufacturing, a metal material with high chemical resistance, or the like.

(4) Patterning of second mask 13 (see FIG. 5D)
The photoresist to be the second mask 13 is exposed and developed and patterned. A region 13 a (hereinafter, referred to as an opening region 13 a) where a part of the second mask 13 is removed and the one surface 1 a of the silicon substrate 1 is exposed is included in the region corresponding to the through hole 3 or the through hole 3. It becomes an area to be done. The opening region 13a of the second mask 13 may be formed in substantially the same shape and substantially the same position as the opening region 15b of the third mask 15 that faces the one surface 1a and the other surface 1b of the silicon substrate 1, respectively. However, as shown in FIG. 5D, the opening area 13a may be formed smaller than the opening area 15b of the third mask 15 in the range where the opening area 13a is included in the opening area 15b. Further, in the range in which the opening region 13a is included in the opening region 15b, the center of the opening region 13a of the second mask 13 may be different from the center of the opening region 15b of the third mask 15 in plan view. . This makes it possible to form the size of the opening of the through hole 3 in accordance with the opening region 15 b of the third mask 15 when performing crystal anisotropic etching described later. Thus, the first mask 11 and the second mask 13 are sequentially formed on the one surface 1a of the silicon substrate 1 from the silicon substrate side.

(5) Dry etching (see FIG. 6A)
Using the second mask 13 as a mask, the silicon substrate 1 is etched by dry etching as in the first embodiment. At this time, the protective layer 14 functions as an etching stopper. The dry etching is preferably plasma etching as in the first embodiment. For example, RIE or DRIE (Deep-RIE) can be used. Etching is started from one surface 1a of the silicon substrate 1, and etching is performed until the protective layer 14 is exposed, thereby forming the through hole 3 penetrating the one surface 1a and the other surface 1b. As already described, in dry etching, the opening size may be different between the etching start side and the etching end side, or the opening position may be different. FIG. 6A shows a case where the so-called reverse tapered shape is processed. The side wall 16 of the through-hole 3 is not limited to the tapered shape illustrated in FIG. 6A, and may have a shape like the side wall 52 illustrated in FIG. At this time, if the second mask 13 is formed so as to be included in the opening region 15 b corresponding to the opening of the through hole in which the opening region 13 a is originally formed, the side wall 16 of the through hole 3 is The through hole 3 is formed so as to be contained inside the opening region 15b. And the desired through-hole 3 can be obtained after the crystal anisotropic etching mentioned later by matching the opening area 15b with the size and / or position of the through-hole to be originally formed. In the second embodiment, for example, the shape of the side wall 16 of the through hole 3 is grasped in advance in consideration of the shift between the opening region 13a and the opening region 15b due to the influence of the taper as a process parameter, and based on this, the third mask 15 is obtained. May be determined, and the third mask 15 may be patterned in the above-described process. After the dry etching, the second mask 13 and the protective layer 14 are removed.

(6) Crystal anisotropic etching (see FIG. 6B)
After removing the second mask 13 and the protective layer 14, the silicon substrate 1 is etched by crystal anisotropic etching using the first mask 11 and the third mask 15 as a mask. For crystal anisotropic etching, the same method as in Example 1 can be used. Therefore, as in Example 1, it is preferable to perform crystal anisotropic etching using a TMAH aqueous solution from one surface 1a of the silicon substrate 1 using a single first mask 11. Further, in the second embodiment, the etching solution can be passed through the opening region 15b of the third mask 15, so that the etching can be uniformly advanced to the entire side wall 16 of the through hole 3. As a result, the processing marks peculiar to dry etching seen on the side wall 16 of the through hole 3 shown in FIG. 6A are removed by the mask having the minimum number of layers, and as shown in FIG. Etching is allowed to proceed to the position masked by the mask 15, and when the facet surface with the surface orientation {111} appears, the etching can be substantially stopped. Accordingly, similarly to the first embodiment, it is possible to form the through hole 3 and the flow path 5 having the side wall 18 substantially constituted by the facet surface having the surface orientation {111}. This can be processed in accordance with the size of the opening region 15b of the third mask 15. Therefore, according to the second embodiment, the side wall 18 of the through hole 3 can be processed to be substantially vertical and flat with respect to the etched surface of the silicon substrate 1, and the through hole 3 can be formed with a desired size and pitch. It can be easily formed.

(7) Removal of first mask 11 and third mask 15 (see FIG. 6C)
By removing the first mask 11 and the third mask 15, the flow path plate 100 including the through holes 3 and the flow paths 5 is formed as illustrated in FIG. A step of forming a silicon oxide film (not shown) on one side 1a, the other side 1b and the side wall of the through hole 3 by performing thermal oxidation or the like may be included.

As described above, according to the method for manufacturing the flow path plate 100 of the liquid ejection apparatus according to the second embodiment of the present invention, after the through-hole 3 is formed by one etching, the first surface 1a of the silicon substrate 1 is further layered. By performing crystal anisotropic etching using the first mask 11, the side wall surface of the through hole 3 can be processed so as to be constituted by the plane of the plane orientation {111} of the silicon substrate. Furthermore, the patterning of the third mask 15 makes it possible to uniformly etch the entire side wall 16 of the through hole 3 and process the through hole 3 to a desired size. Therefore, according to the method for manufacturing the flow path plate 100 of the liquid ejection apparatus according to the second embodiment, the side wall 18 of the through-hole 3 included in the flow path plate 100 is flattened by a simple manufacturing process as in the first embodiment. In addition, the through hole 3 can be formed in a desired size while being processed substantially vertically.

As described above, as described in Example 1 and Example 2, according to the method for manufacturing the flow path plate 100 of the liquid ejection device according to the embodiment of the present invention, the side wall surface of the through hole 3 can be formed by a simple manufacturing process. Since it can be processed flat and substantially vertically, it is possible to reduce the manufacturing cost of the flow path plate 100 provided with the through-holes 3 and to provide a highly accurate liquid ejection apparatus with improved liquid flight characteristics. .

DESCRIPTION OF SYMBOLS 1 ... Silicon substrate, 3 ... Through-hole, 5 ... Flow path, 11 ... 1st mask, 12 ... Stopper layer, 13 ... 2nd mask, 14 ... Protective layer, 15 ... 3rd mask, 30 ... Liquid discharge apparatus, 31 , 100 ... flow path plate

Claims (7)

A liquid ejection apparatus comprising: a through-hole penetrating one surface and the other surface of a silicon substrate having a surface orientation of {110}; and a flow path formed on the one surface side and connected to the through-hole. A flow path plate manufacturing method comprising:
Forming a first mask on the one surface of the silicon substrate and forming a second mask on the first mask; and
A through hole forming step of forming the through hole by performing etching including dry etching at least in part via the second mask;
After removing the second mask, crystal anisotropic etching is performed on the through hole through the first mask, and the side wall surface of the through hole is aligned with the plane orientation {111} of the silicon substrate. A side wall processing step for processing the side wall of the through-hole so as to constitute;
A method for manufacturing a flow path plate of a liquid ejection device. A stopper layer forming step of forming a stopper layer on the other surface of the silicon substrate;
A protective layer forming step of forming a protective layer on the stopper layer,
The method for manufacturing a flow path plate of a liquid ejection device according to claim 1, wherein the through hole is formed using the stopper layer as an etching stopper in the through hole forming step. A third mask forming step of forming a third mask on the other surface of the silicon substrate;
Etching the third mask to remove a portion corresponding to the through hole to expose the silicon substrate;
A protective layer forming step of forming a protective layer on the third mask and the other surface of the silicon substrate,
The method for manufacturing a flow path plate of a liquid ejection device according to claim 1, wherein the through hole is formed using the protective layer as an etching stopper in the through hole forming step.   The flow of the liquid ejecting apparatus according to claim 3, wherein the second mask and the third mask are formed so that the opening region of the third mask includes the opening region of the second mask. Road board manufacturing method.   The first mask, the third mask, and the stopper layer are silicon oxide films formed on the one surface or the other surface by thermally oxidizing the silicon substrate, respectively. A method for manufacturing a flow path plate of a liquid ejection device according to any one of 2 to 4.   The liquid according to claim 2, wherein the second mask and the protective layer are photoresist films formed on the one surface and the other surface of the silicon substrate, respectively. Manufacturing method of flow path plate of discharge device. 7. The method for manufacturing a flow path plate for a liquid ejection apparatus according to claim 1, wherein the crystal anisotropic etching is wet etching using a TMAH aqueous solution.

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