JP3704467B2 - Manufacturing method of semiconductor device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of manufacturing a semiconductor device in which individual components of an optical pickup are integrated.
[0002]
[Prior art]
In recent years, in the field of optical discs such as CDs and CD-ROMs, there has been a demand for incorporation into personal computers and the like and for portable devices. Therefore, the downsizing and thinning of the optical pickup, which is a key part of the optical disk recording / reproducing apparatus, has become a major technical issue. Accompanying this, the movement to integrate individual components such as a semiconductor laser, a light receiving element, a mirror, and a diffraction grating constituting the optical pickup has been activated, and the optical pickup has been reduced in size and thickness by various methods.
[0003]
FIG. 6A shows a configuration of an optical pickup in which individual components are not integrated. FIG. 6B shows a configuration example of an optical pickup simplified by an integrated device (laser diode hologram unit: hereinafter referred to as LDHU) in which individual components are integrated. As shown in FIG. 6A, in the case of an optical pickup in which individual components are not integrated, the semiconductor laser 101, the prism 102, the mirror 103, the lens 104, and the light receiving element 105 must be provided individually. It was difficult to reduce the size and thickness. On the other hand, in the case of the optical pickup shown in FIG. 6B, since the LDHU 1 in which the semiconductor laser, the light receiving element, and the prism are integrated is used, the optical pickup is made small and thin, and the optical adjustment is simple. And cost reduction.
[0004]
The basic configuration of the LDHU 1 will be described below with reference to FIGS. 2 and 3 that are used as diagrams of the present invention.
[0005]
FIG. 2A shows the basic configuration of LDHU1. The LDHU 1 has a unique configuration in which the light receiving element 2 with a built-in micromirror is installed in a thin package 3 and the hologram optical element 4 is integrated, and the downsizing of the optical pickup is realized. FIG. 2B shows an enlarged view of the light receiving element 2 with a built-in micromirror. The micromirror built-in light receiving element 2 has a configuration in which a micromirror 21, a semiconductor laser 22, and a light receiving unit 23 are provided on a semiconductor substrate 24 used as a light receiving element body. The micromirror 21 is constituted by a (111) crystal plane formed on the surface of the semiconductor substrate 24 by anisotropic etching. The semiconductor laser 22 is mounted with high accuracy inside the semiconductor substrate 24, specifically, in a recess having one side as a surface on which the micromirror 21 is formed. The light receiving unit 23 is a light receiving pattern formed on the surface of the semiconductor substrate 24.
[0006]
The emitted light (optical signal) from the semiconductor laser 22 is raised by the micromirror 21, then dispersed by the hologram optical element 4, and condensed on an optical disk (not shown) by a lens (not shown). On the other hand, the reflected light from the optical disk is condensed on the light receiving unit 23 on the semiconductor substrate 24 through the same optical path.
[0007]
3A is a cross-sectional view taken along the line AA of FIG. 2B, and FIG. 3B is an enlarged view of the micromirror 21 portion of FIG. 3A. The micromirror 21 utilizes a (111) crystal plane that forms an angle of 45 ° with a semiconductor substrate 24 of a silicon (100) single crystal substrate (hereinafter referred to as a silicon (100) 9 ° off substrate) with an off angle of 9 °. Is formed. This (111) crystal plane is obtained by anisotropic etching of a silicon (100) 9 ° off substrate. The semiconductor laser 22 is disposed on an LD stage (laser diode stage) 25 formed on the semiconductor substrate 24. The LD stage 25 is formed in a recess having one side as a micromirror 21 forming surface.
[0008]
As described above, the micromirror 21 is required to have a function of reflecting an optical signal from the semiconductor laser 22 serving as a light source of the optical disk device and raising it upward. For this reason, the roughness of the surface of the micromirror 21 has a great influence on the optical pickup characteristics, and there is a possibility that the stability of the recording / reproducing function on the optical disk may be hindered. Therefore, the micromirror 21 requires a very flat mirror surface in order to play a role as an optical component.
[0009]
FIG. 7 shows an outline of a process for forming the micromirror 21 by a conventional manufacturing method. 7A to 7D respectively show a plan view of the micromirror built-in light receiving element 2 in each manufacturing process and a cross-sectional view taken along the line CC in the plan view.
[0010]
First, a silicon oxide film 26 is formed on the surface of a silicon (100) 9 ° off substrate to be the semiconductor substrate 24 (see FIG. 7A). Next, a part of the silicon oxide film 26 is opened by etching to form a mask pattern 110 (see FIG. 7B). Further, a recess 28 is formed in the region of the mask pattern 110 of the semiconductor substrate 24 by anisotropic etching (see FIG. 7C). The inclined surface 29 which becomes the side surface of the concave portion 28 is formed of a (111) crystal plane, and one of the inclined surfaces is used as the micromirror 21. Thereafter, a convex portion is formed as the LD stage 25 in the concave portion 28 by a plurality of anisotropic etchings (see FIG. 7D).
[0011]
As described above, the flatness of the micromirror 21 affects optical pickup characteristics such as tracking, focus servo, and jitter. Therefore, it is important how the (111) crystal plane can be stably and flatly formed by anisotropic etching.
[0012]
Therefore, in order to obtain a flat (111) crystal plane as a micromirror, the conventional method uses a rectangular mask pattern 110 shown in FIG. 8 as a mask pattern during anisotropic etching. Furthermore, by using a solution obtained by adding alcohol to an aqueous potassium hydroxide solution as an anisotropic etching solution, the amount of shaving of the silicon oxide film as a mask material was reduced, and a flat 45 ° micromirror surface was formed. .
[0013]
[Problems to be solved by the invention]
However, since the mask pattern 110 used in the conventional method is formed in a darkroom process, the angle of the mask pattern 110 with respect to the crystal orientation <110> direction of the semiconductor substrate 24 as shown in FIG. A shift, a minute chip of the mask pattern 110 as shown in FIG. 10 (indicated by 110a in the figure), a decrease in linearity due to overetching, or the like occurs.
[0014]
For example, when there is an angle shift in the arrangement of the mask pattern 110, as shown in the enlarged view of a portion 111 in FIG. 9A shown in FIG. Etching proceeds in only one direction (in the direction shown). For this reason, after the anisotropic etching, streak-like irregularities 112 are formed on the (111) crystal plane to be a micromirror. An arrow 114 indicates the etching direction toward the (111) crystal plane. Further, even when the mask pattern 110 has a chip 110a, a step 115 (see FIG. 10B) or the like is formed. Thus, in the conventional method, stable production of the micromirror 110 is difficult due to the problem that the flatness of the micromirror 21 is significantly deteriorated.
[0015]
Furthermore, when forming the LD stage 25 for installing the semiconductor laser 22, a plurality of anisotropic etchings are required. However, as the number of etchings increases, the mask pattern material by the anisotropic etching solution is used. The linearity of the mask pattern 110 decreases due to erosion or the like. For this reason, the flatness deterioration of the micromirror 21 after anisotropic etching is unavoidable.
[0016]
Japanese Patent Laid-Open No. 10-144554 proposes a method using a silicon (100) substrate having no off-angle as a method for forming a 45 ° micromirror on a silicon substrate by anisotropic etching. . This conventional method uses a silicon substrate having the crystal orientation <100> direction or <110> direction as an orientation flat (100) crystal surface as the substrate surface, and has an angle of 45 ° with the substrate surface (110) A recess having a crystal face exposed on the side surface is formed. Here, a solution obtained by adding isopropyl alcohol to potassium hydroxide or ethylene / diamine / procatechol is used as the anisotropic etching solution. However, the above publication does not mention the flatness of the 45 ° micromirror surface.
[0017]
In order to solve these problems, the present invention provides a semiconductor device capable of stably forming a micromirror having a very flat (111) crystal plane on a semiconductor substrate by anisotropic etching. An object is to provide a manufacturing method.
[0018]
[Means for Solving the Problems]
  In order to achieve the above object, a method of manufacturing a semiconductor device according to claim 1 of the present invention forms a first mask pattern on a semiconductor substrate and selectively etches a part of the semiconductor substrate. First stepAnd a second step of forming a second mask pattern on the semiconductor substrate in a state where the first mask pattern is disposed, and performing anisotropic etching at least twice.In the method of manufacturing a semiconductor device including the above, in the first step, as the first mask pattern, at least a part of the opening contour shape is a polygon, and at least one set of two adjacent sides of the polygon Is arranged on one side of a region divided by the intersecting line between the (111) crystal plane including the contacts on the two sides and the semiconductor substrate surface, and (100), (110), (111) crystals When the etching rate for the surface is R (100), R (110), and R (111), an anisotropic etching solution in which R (111) is smaller than R (100) and R (110) is used. Anisotropic etching of the semiconductor substrateThe anisotropic etchant used in the second step has an etching rate ratio R (110) / R (111) between the (110) crystal plane and the (111) crystal plane used in the first step. It is set to be smaller than the anisotropic etching liquid to be obtained and to be smaller as the number of anisotropic etching increases.It is characterized by that.
[0019]
According to this method, etching in the <110> direction progresses equally, starting from the contact points on the two sides in the first mask pattern and opposite to each other across the starting point. Therefore, after anisotropic etching, one (111) crystal plane defined by the contact point (starting point) appears in a certain region.
[0020]
  As a result, it is possible to greatly suppress the decrease in flatness of the (111) crystal plane caused by mask pattern angular deviation, mask-shaped micro defects, etc., and to form an extremely flat (111) crystal plane stably. it can.Also, according to this method, R (110) / R (111) decreases as the number of anisotropic etchings increases, so that R (111) increases relatively. That is, a plurality of (111) crystal planes existing after anisotropic etching in the first step can be reduced by anisotropic etching in the second step. Furthermore, in the second step, the etching rate of the mask pattern material is also reduced, so that the mask pattern is prevented from being collapsed during etching. Thereby, a flat (111) crystal plane can be stably formed.
[0021]
Furthermore, a method of manufacturing a semiconductor device according to a second aspect of the present invention is the method according to the first aspect, wherein the angle on the side not including the opening formed by each of the two sides and the intersection line is set to 0 °. Larger than 5 ° and less than 5 °.
[0022]
When the mask pattern has a pointed shape at the starting point (the contact point of the two sides), the area where a flat (111) crystal plane is obtained is narrowed, but as in this method, the two sides and the intersection line By setting the angle that does not include the opening portion formed by the angle of 5 ° or less, a flat (111) crystal plane can be obtained in a sufficient region.
[0023]
  According to a third aspect of the present invention, there is provided a method for manufacturing a semiconductor device, comprising: forming a first mask pattern on a semiconductor substrate; and selectively etching a part of the semiconductor substrate.And a second step of forming a second mask pattern on the semiconductor substrate in a state where the first mask pattern is disposed, and performing anisotropic etching at least twice.In the method of manufacturing a semiconductor device including the above, in the first step, as the first mask pattern, at least a part of the opening contour shape is a curve, and the curve is the surface of the semiconductor substrate (111). A mask pattern having a shape in contact with the line of intersection with the crystal plane is formed, and the etching rates for the (100), (110), and (111) crystal planes are R (100), R (110), and R (111) In this case, the semiconductor substrate is anisotropically etched using an anisotropic etching solution in which R (111) is smaller than R (100) and R (110).The anisotropic etchant used in the second step has an etching rate ratio R (110) / R (111) between the (110) crystal plane and the (111) crystal plane used in the first step. It is set to be smaller than the anisotropic etching liquid to be obtained and to be smaller as the number of anisotropic etching increases.It is characterized by that.
[0024]
According to this method, it is possible to obtain the same effects as those of the inventions of claims 1 and 2 by optimally setting the curvature radius of the curve.
[0028]
  Claims of the invention4A method for manufacturing a semiconductor device according to claim 1 is provided.3In the method according to any one of the above, the semiconductor substrate is formed of a silicon single crystal, and the anisotropic etching solution includes at least potassium hydroxide and water, and the concentration of potassium hydroxide. Is 10 wt% or more and 40 wt% or less.
[0029]
According to this method, an etching rate and anisotropy suitable for mass production can be obtained.
[0030]
  Claims of the invention5A method for manufacturing a semiconductor device according to claim 1 is provided.4In the method described in any one of the above, an anisotropic etchant containing no alcohol is used.
[0031]
According to this method, since alcohol is not added to the anisotropic etching solution, composition variation of the anisotropic etching solution due to evaporation of the alcohol can be suppressed. Thereby, the variation in etching depth and etching shape can be greatly reduced.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the present embodiment, a method of manufacturing a micromirror built-in light receiving element (semiconductor device) constituting an integrated device (laser diode hologram unit: hereinafter referred to as LDHU) in which individual components of an optical pickup are integrated will be described.
[0033]
Since the configuration of the LDHU 1 shown in FIG. 2A and the configuration of the micromirror built-in light receiving element 2 shown in FIG. 2B are as described in the prior art, they are omitted here. To do. Further, the details of the micromirror 21 of the micromirror built-in light receiving element 2 shown in FIGS. 3A and 3B are also as described in the prior art.
[0034]
Next, a method of stably forming the flat micromirror 21 will be described with reference to the manufacturing process diagram of the micromirror 21 shown in FIG. 4A to 4E respectively show a plan view of the micromirror built-in light receiving element 2 in each manufacturing stage and a cross-sectional view taken along the line B-B of the plan view.
[0035]
First, a silicon oxide film 26 is formed on the surface of a silicon (100) 9 ° off substrate to be the semiconductor substrate 24 (see FIG. 4A). Next, a part of the silicon oxide film 26 is opened by etching to form a mask pattern 27 (see FIG. 4B). Further, in the semiconductor substrate 24, a recess 28 is formed in the region of the mask pattern 27 by anisotropic etching (see FIG. 4C). A slope 29 that is a side surface of the recess 28 is formed to be a (111) crystal face, and one of these slopes is used as the micromirror 21. Thereafter, a convex portion is formed as the LD stage 25 in the concave portion 28 by a plurality of anisotropic etchings (see FIG. 4D). Thereafter, the semiconductor laser 22 is placed on the LD stage 25, and the light receiving section 23 is patterned to complete the micromirror built-in light receiving element 2 (see FIG. 4E).
[0036]
Next, the mask pattern 27 used when forming the micromirror 21 will be described in detail.
[0037]
FIG. 1A shows a state where a mask pattern 27 for forming a micromirror used in the present embodiment is provided on a semiconductor substrate 24 and anisotropic etching is performed. As shown in the figure, the mask pattern 27 is a pentagonal pattern in which one side to be a micromirror forming portion of a conventional rectangular mask pattern (see FIG. 8) is a polygonal line. That is, in the micromirror forming portion of the mask pattern 27, a mountain-shaped pattern shape having an apex (hereinafter referred to as a starting point) 27a at the center is adopted instead of a straight line shape. For anisotropic etching, an anisotropic etching solution containing potassium hydroxide as a main component is used.
[0038]
An enlarged view of 30 parts (a part of the micromirror forming part) shown in FIG. 1A is shown in FIG. As shown in this enlarged view, the micromirror forming portion of the mask pattern 27 includes two regions 27b and 27c that cross a plurality of (111) crystal planes of the semiconductor substrate 24 in different directions with the starting point 27a as a boundary. have. By providing such two regions, a flat (111) crystal plane centered on the starting point 27a can be obtained in a constant region even when the mask pattern 27 has an angular shift.
[0039]
Here, the following two points can be cited as conditions for stably obtaining a flat (111) crystal plane by anisotropic etching.
[0040]
(1) An opening of the mask pattern 27 exists on one side with respect to an intersection line 35 (see FIG. 1C) between the surface of the semiconductor substrate 24 and the (111) crystal plane passing through the starting point 27a. .
[0041]
(2) R (111) is sufficiently smaller than R (100) and R (110)
Use anisotropic etchant.
[0042]
Note that R (111), R (100), and R (110) are etching rates of the anisotropic etching liquid with respect to the (111), (100), and (110) crystal planes.
[0043]
Further, in the present embodiment, potassium hydroxide without adding alcohol to the anisotropic etching solution in order to improve the etching rate in the <110> direction and obtain a flat (111) crystal plane in a wider range. An aqueous solution was used. In this anisotropic etching solution, the potassium hydroxide concentration is 40 wt% or less, and the etching rate is R (100)> R (110)> R (111). Also, R (111) was almost a value of 0.
[0044]
In the anisotropic etching under the conditions as described above, etching in the <110> direction (indicated by the arrow 31 in FIG. 1 (b)) is performed in the opposite directions across the starting point 27a. move on. Therefore, a plurality of (111) crystal planes traversed by the micromirror forming portion of the mask pattern 27 are aggregated into one (111) crystal plane defined by the starting point 27a. Therefore, after anisotropic etching, as shown in FIG. 1A, a flat mirror surface composed of the (111) crystal plane centering on the starting point 27a appears in a certain region. Although the uneven portion 33 is formed in a part of the micromirror 21 after the etching, an extremely flat (111) crystal plane 34 centering on the starting point 27a can be stably obtained over a wide range. In FIG. 1B, an arrow 32 indicates etching in the <111> direction.
[0045]
Further, the improvement of the etching rate in the <110> direction is effective in suppressing unevenness (see FIG. 10) on the (111) crystal plane caused by minute defects generated in the mask pattern.
[0046]
Here, the inclination 36 of the micromirror forming portion with respect to the intersection line 35 between the surface of the semiconductor substrate 24 and the (111) crystal plane shown in FIG. 1C is the mask pattern in the darkroom process for forming the mask pattern 27. It is determined by the angle deviation amount of 27. For the purpose of cheaper production costs, the mechanical angular deviation when an aligner is used for alignment of mask pattern formation is about 2 ° at the maximum with respect to the orientation flat of the substrate. Therefore, by setting the inclination 36 of the mask pattern 27 to about 3 °, the micromirror 21 having a flat (111) crystal plane can be produced with a high yield even when an aligner which is an inexpensive facility is used. In this embodiment, the inclination 36 is set to about 3 °. However, the present invention is not limited to this, and a flat (111) crystal plane can be obtained in a sufficiently wide region as long as it is larger than 0 ° and not larger than 5 °. Can do.
[0047]
In the micromirror built-in light receiving element 2, it is required to form a convex portion that becomes the LD stage 25 as an installation base of the semiconductor laser 22. Therefore, after the first anisotropic etching step performed for forming the micromirror 21, a second anisotropic etching step for forming the LD stage 25 is further required. In the second anisotropic etching step, it is necessary to perform anisotropic etching at least twice.
[0048]
In the second anisotropic etching step, a mask pattern for forming a convex portion is further formed on the semiconductor substrate 24 while leaving the mask pattern 27 remaining. As the anisotropic etching solution used in the second anisotropic etching step, a potassium hydroxide aqueous solution having a lower concentration than that used in the first step is used. Furthermore, in the anisotropic etching performed at least twice in the second step, a potassium hydroxide aqueous solution having a lower concentration is used as the anisotropic etching solution each time the number of times is increased.
[0049]
Thus, a flatter micromirror surface can be obtained by diluting the anisotropic etching solution each time the number of times increases. This is because R (110) / R (111) is decreased by diluting the potassium hydroxide aqueous solution, so that R (111) is relatively increased, and the etching rate of the silicon oxide film that is the mask pattern material is increased. It is thought that this is due to the decrease in. That is, a plurality of (111) crystal planes existing on the micromirror surface after the first anisotropic etching step are reduced in the second anisotropic etching step due to the difference in anisotropy of the anisotropic etching solution used. As a result, the flatness of the micromirror can be improved.
[0050]
In addition, since the etching rate of the mask pattern material (here, the silicon oxide film) is reduced by diluting the potassium hydroxide aqueous solution, the mask pattern collapse that occurs during the second anisotropic etching step is suppressed. This also leads to improvement in the flatness of the micromirror.
[0051]
In addition, the etching rate and anisotropy suitable for mass production are acquired by setting the density | concentration of potassium hydroxide aqueous solution between 10 wt%-40 wt%.
[0052]
Further, in the present embodiment, the mask pattern 27 in which the micromirror forming portion has a mountain shape is used as the mask pattern, but the shape is not limited to this. Usable mask patterns include, for example, a mask pattern 36 in which the number of starting points of the micromirror forming portion is increased as shown in FIG. 5A, or a micromirror forming portion as shown in FIG. 5B. Even if the mask pattern 37 having a curved shape is used, the same effect can be obtained.
[0053]
When the mask pattern 36 is used, the flat (111) crystal plane formed around the starting point 36a is hindered by the (111) crystal plane formed from the other starting points 36b and 36c. Accordingly, when the etching time is lengthened, the concavo-convex portion 33 moves to the flat (111) crystal plane 34 region, and the flatness of the micromirror 21 may be lowered. For this reason, it is necessary to set the etching time optimally.
[0054]
On the other hand, the mask pattern 37 is not provided with a clear starting point due to the curved shape, but the same effect as the mask pattern 27 can be expected by optimizing the radius of curvature.
[0055]
【The invention's effect】
As described above, according to the method for manufacturing a semiconductor device of the present invention, when a (111) crystal plane is formed by selectively etching a part of a silicon (100) single crystal substrate, a mask pattern is formed. (111) crystal plane deterioration due to the angle deviation and the micro defect of the mask shape can be greatly suppressed, and an extremely flat (111) crystal plane can be stably formed.
[0056]
Further, even when performing anisotropic etching a plurality of times, the concentration of potassium hydroxide is decreased as the number of etchings is increased, so that the difference in anisotropic etching rate in the <110> direction can be utilized to achieve flatness. This also has the effect that a stable micromirror region can be obtained.
[0057]
Furthermore, the composition of the aqueous solution of potassium hydroxide alone is not added to the anisotropic etching solution, and the composition variation of the etching solution due to the evaporation of the alcohol is suppressed, and the variation in the etching depth and the etching shape is greatly increased. There is also an effect that it can be reduced.
[Brief description of the drawings]
FIG. 1A is an explanatory view showing the state of anisotropic etching performed for forming a micromirror in a method for manufacturing a micromirror built-in light receiving element according to an embodiment of the present invention; ) And (c) are enlarged views of the micromirror forming part of (a).
2A is a perspective view showing a configuration of a laser diode hologram unit provided with the light receiving element with a built-in micromirror, and FIG. 2B is a perspective view showing a configuration of the light receiving element with a built-in micromirror. FIG.
3A is a cross-sectional view taken along the line AA of FIG. 2B, and FIG. 3B is an enlarged view showing a micromirror part of FIG.
FIGS. 4A to 4E are process diagrams showing manufacturing steps of the light receiving element with a built-in micromirror according to the method of the present invention. FIGS.
FIGS. 5A and 5B are explanatory views showing the state of anisotropic etching performed for forming a micromirror using another mask pattern. FIGS.
FIG. 6A is a plan view showing a schematic configuration of an optical pickup in which individual parts are not integrated, and FIG. 6B is an optical pickup including a laser diode hologram unit in which individual parts are integrated. It is a top view which shows schematic structure of these.
7A to 7D are process diagrams showing a manufacturing process of a micromirror built-in light receiving element according to a conventional method.
FIG. 8 is a plan view showing a state in which a mask pattern used in a conventional manufacturing method is formed on a semiconductor substrate.
FIG. 9A is an explanatory diagram showing a state of an angle shift of a mask pattern that occurs when forming a micromirror by a conventional method, and FIG. 9B is a micromirror forming portion of FIG. FIG.
FIG. 10 is an explanatory diagram showing a state of a micro defect of a mask pattern generated when a micromirror is formed by a conventional method.
[Explanation of symbols]
1 Laser diode hologram unit
2 Micromirror built-in light receiving element (semiconductor device)
21 Micromirror
27 Mask pattern (first mask pattern)
29 Slope ((111) crystal plane)
35 Intersection line
36 mask pattern (first mask pattern)
37 Mask pattern (first mask pattern)

Claims (5)

Forming a first mask pattern on the semiconductor substrate and selectively etching a part of the semiconductor substrate; and forming a first mask pattern on the semiconductor substrate on which the first mask pattern is disposed. A second step of forming a mask pattern of 2 and performing anisotropic etching at least twice or more ,
In the first step, as the first mask pattern, at least a part of the opening contour shape is a polygon, and at least one set of two adjacent sides of the polygon includes the contact points of the two sides. (111) disposed on one side of a region divided by a line of intersection between the crystal plane and the semiconductor substrate surface;
Furthermore, when the etching rates for the (100), (110), and (111) crystal planes are R (100), R (110), and R (111), R (111) becomes R (100) and R (100 110) using an anisotropic etchant that is smaller than 110), and anisotropically etching the semiconductor substrate ;
The anisotropic etchant used in the second step has an etching rate ratio R (110) / R (111) between the (110) crystal plane and the (111) crystal plane that is different from that used in the first step. A method of manufacturing a semiconductor device, characterized in that the semiconductor device is smaller than an isotropic etchant and is set to be smaller each time the number of anisotropic etchings is increased .   2. The method of manufacturing a semiconductor device according to claim 1, wherein an angle of each of the two sides and the intersecting line that does not include an opening is greater than 0 ° and equal to or less than 5 °. . Forming a first mask pattern on the semiconductor substrate and selectively etching a part of the semiconductor substrate; and forming a first mask pattern on the semiconductor substrate on which the first mask pattern is disposed. A second step of forming a mask pattern of 2 and performing anisotropic etching at least twice or more ,
In the first step, as the first mask pattern, at least part of the opening contour shape is a curve, and the curve is in contact with the intersection line between the semiconductor substrate surface and the (111) crystal plane. Forming a mask pattern of
Furthermore, when the etching rates for the (100), (110), and (111) crystal planes are R (100), R (110), and R (111), R (111) becomes R (100) and R (100 110) using an anisotropic etchant that is smaller than 110), and anisotropically etching the semiconductor substrate ;
The anisotropic etchant used in the second step has an etching rate ratio R (110) / R (111) between the (110) crystal plane and the (111) crystal plane that is different from that used in the first step. A method of manufacturing a semiconductor device, characterized in that the semiconductor device is smaller than an isotropic etchant and is set to be smaller each time the number of anisotropic etchings is increased . The semiconductor substrate is formed of silicon single crystal,
One addition, the anisotropic etchant, at least include potassium hydroxide and water, and any one of claims 1-3, wherein the concentration of potassium hydroxide is less than 10 wt% or more 40 wt% The manufacturing method of the semiconductor device as described in any one of Claims 1-3. The method of manufacturing a semiconductor device according to any one of claims 1-4, characterized by using an anisotropic etchant that does not contain alcohol.

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