JPH11176799A - Equipment and method for etching silicon substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce variations in etching depth in a silicon substrate, by a method wherein an etchant is jetted to the silicon substrate via a tool having an opening part. SOLUTION: A silicon substrate 12 forming a pattern is placed on a tool 5 fixing a silicon substrate. Next, a fixing hook 3 is hooked on an end face of a silicon etching bath 9. Next, a fixing hook connection part 2 is slid and the tool 1 having the opening part is set at a specified position from the silicon substrate 12. Next, a KOH aqueous solution is inputted to a KOH injection position 10 in the silicon etching bath 9, and next a KOH aqueous solution is jetted from an etchant jetting nozzle 11 provided upwardly of the tool 1 having an opening part. The KOH aqueous solution is jetted, and simultaneously the tool 5 fixing the silicon substrate 12 is rotated at a specified rotation speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for etching a silicon substrate.

[0002]

2. Description of the Related Art Conventionally, as described in Japanese Patent Application Laid-Open No. 1-290226, an etching solution is ejected from a large number of injection ports to a silicon substrate with respect to depth variations when a silicon substrate is etched. There is a way.

Another method of suppressing such variations in etching depth is to set a silicon substrate in a jig, then immerse the jig in an etching tank, and then rotate the jig about the center of the silicon substrate. There is a way.

[0004]

However, in the former method, the pressure of the etching solution differs for each injection port, and the etching progress speed varies within the substrate surface.

In the latter method, since the rotation distance is different between the peripheral portion of the silicon substrate and the central portion of the silicon substrate, the peripheral portion of the silicon substrate is more etched than the central portion of the silicon substrate. There are drawbacks. In other words, when a pattern is formed on a silicon substrate and etching is performed, the traveling speed of the peripheral portion of the silicon substrate becomes faster than the traveling speed of the central portion of the silicon substrate, and the etching depth inevitably varies by 5 microns. This variation did not change even when the rotation speed of the silicon substrate was changed, and could not be reduced.

An object of the present invention is to provide an apparatus and a method for etching a silicon substrate which can reduce the variation in etching depth in the surface of the silicon substrate.

[0007]

According to a first aspect of the present invention, there is provided a silicon substrate etching apparatus for supplying an etching liquid to a silicon substrate via a jig having an opening disposed opposite to the silicon substrate. It is characterized by having.

According to a second aspect of the present invention, in the etching apparatus for a silicon substrate according to the first aspect, a mechanism for changing a distance between the jig having the opening and the silicon substrate is provided. .

According to a third aspect of the present invention, there is provided a silicon substrate etching apparatus according to the first aspect, further comprising a mechanism for changing a rotation speed when the silicon substrate is rotated.

According to a fourth aspect of the present invention, there is provided a method for etching a silicon substrate, comprising the step of supplying an etching solution to the silicon substrate via a jig having an opening disposed opposite to the silicon substrate. I do.

According to a fifth aspect of the present invention, in the method for etching a silicon substrate according to the fourth aspect, an alkaline aqueous solution is used as the etching solution.

Therefore, the apparatus and method for etching a silicon substrate according to the present invention can reduce the variation in etching depth in the silicon substrate surface. The reason will be described with reference to FIG. FIG. 5 is a diagram showing the flow of the etching liquid by the above etching apparatus. When the etching liquid is jetted to the silicon substrate 12 through the jig 1 having an opening, the etching liquid flows from the opening of the jig as shown by a solid line. For this reason, the etching liquid flows as indicated by the dotted line in portions other than the jig opening. As a result, since the opening is located corresponding to the central portion of the silicon substrate, the etching is promoted in the central portion of the substrate, while the etching is not promoted in the peripheral portion of the substrate, and the opening in the silicon substrate surface is reduced. Of the etching depth can be reduced.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments.

(Embodiment 1) FIG. 1 is a cross-sectional view of a jig 1 having an opening and its attached parts in the present invention, FIG. 2 is a top view thereof, and FIG. 3 is a perspective view thereof. The jig 1 having an opening was made of Teflon, and had a diameter of 20 cm and an opening diameter of 5 cm. Also, a fixed hook connection part 2 is formed on a part of the end face of the jig, and a part of the fixed hook 3 for fixing to the silicon etching tank 9 is cut off, passed through the fixed hook connection part 2, and provided with an opening. 1 is configured to slide up and down.

FIG. 4 is a perspective view of a silicon etching apparatus according to the present invention.

The jig 1 having an opening is set on the end surface of the silicon etching tank 9 by the fixing hook 3. The jig 5 for fixing the silicon substrate 12 is made of Teflon, and the rotation speed of the shaft 6 can be changed by a motor and a gear mechanism. The motor and the gear mechanism were housed in a motor box 8 and a gear box 7, respectively. The etching liquid injection port 11 is located above the jig 1 having an opening, and the silicon substrate 12 is
The etching liquid is jetted out. (Embodiment 2) FIG. 6 is a process chart of a silicon substrate etched using the etching apparatus of the present invention.

(1) Silicon Thermal Oxidation Step (FIG. 6A) A silicon substrate 12 having a plane orientation of (110) was used, and both sides were polished to a thickness of 280 μm. The silicon substrate 12 was heated at 1100 ° C. for 1 hour in an oxygen atmosphere containing water vapor to perform thermal oxidation, thereby forming an SiO ₂ oxide film 13 with a thickness of 1 μm on the entire surface.

(2) Pattern Forming Step (FIG. 6B) A resist 14 is formed on one surface of the silicon substrate 12 to a thickness of about 1 μm by spin coating, and is exposed and developed to a predetermined pattern to form a resist pattern. Was formed.

Thereafter, the oxide film 13 was etched as shown.

The etching conditions are as follows: a mixture of 50 wt% of hydrofluoric acid and 40 wt% of ammonium fluoride solution 6 is maintained at 20 ° C.
Minutes.

(3) Resist stripping step (FIG. 6 (c)) In order to strip the resist 14, the etching conditions are set to 30.
The resist 14 was stripped by immersing the mixed solution in a volume ratio of 98 wt% sulfuric acid 4 to 90 wt% or more with respect to 1 wt% of hydrogen peroxide solution for 20 minutes.

A pattern was formed on the silicon substrate 12 by the method described above.

Next, a method of processing the silicon substrate 12 using the etching apparatus will be described with reference to FIG.

A jig 5 for fixing the silicon substrate is provided with a silicon substrate 12 having a pattern formed by the process shown in FIG.
Put on. Next, the fixing hook 3 is connected to the silicon etching tank 9.
Hook on the end face of Next, the fixing hook connection part 2 is slid, and the jig 1 having the opening is attached to the silicon substrate 1.
The position is 2 to 3 cm. Next, an 80 ° C., 35% KOH aqueous solution is introduced into the silicon etching tank 9 up to the KOH injection position 10, and then 80 ° C., 35% from the etching liquid injection port 11 provided above the jig 1 having an opening. K
Spout OH aqueous solution. Simultaneously with the jetting of the KOH aqueous solution,
The jig 5 for fixing the silicon substrate 12 is rotated at a rotation speed of 2 rpm.
Rotate at m.

With the above etching method, 90
As a result of performing silicon etching for 20 minutes and measuring the etching depth, the etching depth was 150 microns and the variation was 5 microns in the range when measured at 20 points in the silicon substrate surface.

Example 3 In Example 2, a substrate having a plane orientation (110) was used as a silicon substrate for measuring an etching depth. In the third embodiment, KOH etching was performed under the same conditions as in the first embodiment using a silicon substrate having a plane orientation (100). As a result of measuring the etching depth, the etching depth was 200 microns in 20-point measurement within the silicon substrate surface, and the variation was 2 microns in the range.

FIG. 7 shows the distance between the silicon substrate 12 and the jig 1 having the opening in the (100) plane silicon substrate, and the relationship between the distance and the variation of the etching depth in the silicon substrate surface. It is. From FIG. 7, it can be seen that the closer the distance is, the smaller the variation in etching depth in the substrate surface becomes. When the rotation speed was 2 rpm and the distance was 0.5 cm, the etching depth variation in the substrate surface was 2.1 microns. In the case where the rotation speed of the substrate is constant, if the distance between the silicon substrate 12 and the jig 1 having the opening is short, KOH concentrates on the central portion of the substrate, so that the etching speed of the central portion of the substrate is increased. The etching rate in the central part of the substrate catches up with the etching rate in the peripheral part of the substrate, and the variation in the etching depth in the substrate surface is reduced.

FIG. 8 shows the rotational speed of the jig 5 for fixing the silicon substrate on the (100) plane silicon substrate,
3 shows a relationship between variations in etching depth in a silicon substrate surface. FIG. 8 shows that the lower the rotation speed, the smaller the in-plane variation of the substrate. When the rotation speed of the substrate was 0.5 rpm, the variation in the etching depth in the substrate surface was 2.1 microns. The lower the rotation speed of the substrate, the lower the etching speed of the peripheral portion of the substrate. Since the KOH etching solution is concentrated and discharged to the central portion of the substrate, the variation in the etching progress rate between the central portion of the substrate and the peripheral portion of the substrate is reduced.

From Examples 2 and 3, the same K
It can be seen that even with the OH etchant, the etching rate of the silicon substrate changes depending on the plane orientation of the silicon substrate, and as a result, the variation in the etching depth within the silicon substrate surface changes. By the processing method using the apparatus, it is possible to cope with etching of a silicon substrate having any plane orientation.

[0030]

As described above, according to the present invention, the etching liquid is concentrated on the central portion of the substrate to promote the etching of the central portion of the substrate, thereby suppressing the variation in the etching speed from the peripheral portion of the substrate. This has the effect of reducing depth variations. Also, by changing the distance between the jig having the opening and the jig for fixing the silicon substrate, and changing the rotation speed of the jig for fixing the silicon substrate, the etching speed of the central portion and the peripheral portion of the silicon substrate is changed. Is possible, and even in a silicon substrate having a different plane orientation, there is an effect that variation in etching rate is suppressed and variation in etching depth is reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a jig having an opening of the present invention and an attached part thereof.

FIG. 2 is a top view of a jig having an opening according to the present invention.

FIG. 3 is a perspective view showing a jig having an opening according to the present invention.

FIG. 4 is a perspective view of the etching apparatus of the present invention.

FIG. 5 is a view showing a state in which a silicon substrate is etched using a jig having an opening according to the present invention.

FIG. 6 is an explanatory view of a processing step of a silicon substrate, which has been etched using the etching method of the present invention.

FIG. 7 is a diagram showing a relationship between a silicon substrate rotation speed and a variation in etching depth in a substrate surface in the etching apparatus of the present invention.

FIG. 8 is a diagram showing a distance between a silicon substrate and a jig and a variation in etching depth in a substrate surface in the etching apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Jig which has an opening 2 Fixed hook connection part 3 Fixed hook 4 Cutting part 5 Jig which fixes a silicon substrate 6 Axis 7 Gear box 8 Motor box 9 Silicon etching tank 10 KOH injection position 11 Etching liquid injection port 12 Silicon Substrate 13 Oxide film 14 Resist

Claims (5)

[Claims] 1. An apparatus for etching a silicon substrate, comprising: a mechanism for supplying an etching solution to the silicon substrate via a jig having an opening disposed opposite to the silicon substrate. 2. The silicon substrate etching apparatus according to claim 1, further comprising a mechanism for changing a distance between the jig having the opening and the silicon substrate. 3. An apparatus for etching a silicon substrate according to claim 1, further comprising a mechanism for changing a rotation speed when said silicon substrate is rotated. 4. A method for etching a silicon substrate, comprising the step of supplying an etchant to the silicon substrate via a jig having an opening arranged opposite to the silicon substrate. 5. The method for etching a silicon substrate according to claim 4, wherein an alkaline aqueous solution is used as said etching solution.