JPH1046369A - Method for etching silicon, production of silicon member and etched single crystal silicon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an etching method of silicon by which generation of projection and roughness is prevented, a manufacturing method of a silicon member and etched single crystal silicon. SOLUTION: Silicon is etched by using an etchant added with a chelating agent. In this case, the chelating agent combines with metal ions and dissolved silicon itself in the etchant to prevent the metal ions and dissolved silicon from attaching to an etching surface and generating projection. Otherwise, silicon is etched by using the etchant added with ketone or aldehyde. In this case, hydrogen is consumed by reacting with ketone or aldehyde to restrain generation of bubbles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for etching silicon, a method for manufacturing a silicon member, and an etched single crystal silicon.

[0002]

2. Description of the Related Art As one of the typical techniques of micromachining, a three-dimensional structure is formed by etching a single crystal silicon wafer with an alkaline aqueous solution.

Alkaline aqueous solutions such as potassium hydroxide, sodium hydroxide, ethylenediamine, and tetramethylamine hydroxide are used for anisotropic etching because the rate at which silicon dissolves in them varies depending on the crystal orientation. For example, when potassium hydroxide is used, the (100) plane becomes (111).
The etching rate is 1/100 or less compared to the surface,
The (100) plane can be etched leaving the (111) plane.

[0004] However, when a substance that hinders etching adheres to the silicon surface, a pyramid-shaped projection may be formed in a direction not etched (for example, a (100) plane) from the silicon surface (see FIG. 4). As a countermeasure to prevent the occurrence of such pyramid-shaped projections, conventionally, adhesion of dirt or the like has been performed by vigorous stirring.

[0005] Further, since there is local unevenness in the etching rate, the etched surface tends to be rough (unevenness) (see FIG. 5). In some cases, isopropyl alcohol or the like is added to adjust the etching shape, but in that case, roughening is more likely to occur. Therefore, conventionally, the relationship between roughness and the concentration of an aqueous solution or the like has been examined, and the concentration at which roughness is least likely to be generated has been used, or the roughness has been suppressed by vigorous stirring.

One of the causes of the roughness is that bubbles of hydrogen generated by etching adhere to the surface of silicon, and the circulation of the etching solution in the vicinity thereof is deteriorated, so that the concentration locally changes. It is considered that the etching rate is different between the portion where is attached and the portion where it is not attached.

Therefore, as a conventional countermeasure against roughness, there is a method in which the generation of bubbles is kept as it is by using an etching solution concentration with a small change in etching rate, or physical bubbles are removed by stirring. 4 and 5 are external perspective views of a silicon substrate formed by a conventional etching method.

[0008]

However, the above-described conventional example is particularly difficult to manufacture complicated and fine structures.
Since the circulation of the etching solution by stirring is not detailed,
Protrusions are likely to occur in portions that do not come into contact with the flow of the etchant, and bubbles are not effectively removed. For this reason, there has been a problem that the concentration of the etching solution in the microstructure is far from the optimum value.

It is an object of the present invention to solve the above-mentioned problems and to provide a method for etching silicon, a method for manufacturing a silicon member, and an etched single-crystal silicon in which projections and roughness are prevented.

[0010]

Means for Solving the Problems In order to achieve the above object, a method of etching silicon according to the present invention is a method of etching silicon with an alkaline aqueous solution, the method comprising etching with an etchant obtained by adding a chelating agent to an alkaline aqueous solution. It is.

[0011] In addition to the above structure, the silicon etching method of the present invention preferably uses ethylenediaminetetraacetic acid as a chelating agent.

According to the method of etching silicon of the present invention, in the etching method of etching silicon with an alkaline aqueous solution, etching is performed with an etchant obtained by adding a ketone to an alkaline aqueous solution.

[0013] In addition to the above constitution, in the silicon etching method of the present invention, it is preferable that the ketone ratio is 1% to 30%.

[0014] The silicon etching method of the present invention is an etching method for etching silicon with an alkaline aqueous solution, wherein the etching is performed with an etchant obtained by adding an aldehyde to an alkaline aqueous solution.

[0015] In addition to the above constitution, in the silicon etching method of the present invention, it is preferable that the ratio of aldehyde is 1% to 30%.

According to the method of manufacturing a silicon member of the present invention, in a method of manufacturing a silicon member by etching single crystal silicon with an alkaline aqueous solution, etching is performed with an etching solution obtained by adding a chelating agent to an alkaline aqueous solution.

In addition to the above constitution, in the method for producing a silicon member of the present invention, it is preferable to use ethylenediaminetetraacetic acid as a chelating agent.

The method for manufacturing a silicon member according to the present invention is a method for manufacturing a silicon member by etching single crystal silicon with an alkaline aqueous solution, wherein the etching is performed with an etchant obtained by adding a ketone to an alkaline aqueous solution.

In addition to the above structure, in the method for manufacturing a silicon member of the present invention, it is preferable that the ratio of ketone is from 1% to 30%.

In the method for manufacturing a silicon member according to the present invention, in the method for manufacturing a silicon member by etching single crystal silicon with an alkaline aqueous solution, it is preferable to perform etching with an etchant obtained by adding an aldehyde to an alkaline aqueous solution.

In addition to the above structure, in the method for manufacturing a silicon member according to the present invention, it is preferable that the ratio of aldehyde is 1% to 30%.

The etched single-crystal silicon of the present invention is obtained by performing anisotropic etching by etching a single-crystal silicon having a specific orientation to be etched with an etching solution obtained by adding a chelating agent to an aqueous alkali solution.

In addition to the above structure, the etched single crystal silicon of the present invention preferably uses ethylenediaminetetraacetic acid as an chelant.

The etched single-crystal silicon of the present invention is obtained by performing anisotropic etching by etching a single-crystal silicon having a specific orientation to be etched with an etching solution obtained by adding a ketone to an alkaline aqueous solution.

In addition to the above structure, the etched single crystal silicon of the present invention preferably has a ketone ratio of 1% to 30%.

The etched single-crystal silicon of the present invention is obtained by etching an anisotropic single-crystal silicon in a specific orientation by etching with an etchant obtained by adding an aldehyde to an alkaline aqueous solution.

In addition to the above structure, the etched single-crystal silicon of the present invention has an aldehyde ratio of 1% to 30%.
It is preferable that

When silicon is etched using an etchant to which a chelating agent has been added, metal ions in the etchant and the dissolved silicon themselves are combined with each other, and these may adhere to the etched surface and cause projections. Prevent beforehand.

When silicon is etched using an etching solution to which ketone or aldehyde is added, generation of bubbles is suppressed by hydrogen being consumed by reacting with ketone or aldehyde. Ketones and aldehydes that have reacted with hydrogen are converted to alcohols. Chemical formula (1)
Indicates a reaction between ketone and hydrogen. R represents an alkyl group. Replacing one R in the molecular formula of ketone with H means the case of aldehyde.

[0030]

Embedded image

Although newly generated alcohol is added to the etching solution, isopropyl alcohol is sometimes added to adjust the etching shape.
Alcohol does not hinder etching. As a result,
It is possible to realize a method for etching silicon, a method for manufacturing a silicon member, and provision of etched single-crystal silicon in which the occurrence of protrusions and roughness is prevented.

[0032]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a conceptual diagram showing an embodiment of an etching apparatus to which the silicon etching method of the present invention is applied.

As shown in FIG. 1, a hot water container 2 is arranged on the stirrer main body 1. The heater 4 of the temperature controller 3 and the etching solution container 5 are accommodated in the hot water container 2 and are filled with water 6.

In the etching solution container 5, a substrate holder 7 is provided.
The silicon substrate 8 and the stirrer 9 held in the
And it is filled with the etching liquid 10. As the etching solution 10, for example, a solution obtained by adding a chelating agent to an alkaline aqueous solution is used.

When the silicon substrate 8 is etched using such an etching apparatus 11, the etching solution 10 contains a chelating agent, and the chelating agent is mixed with the metal ions in the etching solution 10 and the dissolved silicon itself. Join. The bond with the chelating agent prevents metal ions from adhering to the etched surface and forming projections.

Although a chelating agent is used for the etching solution 10, a ketone or an aldehyde may be used instead of the chelating agent. In this case, hydrogen is consumed by reacting with the ketone or aldehyde to suppress the generation of bubbles, and the phenomenon that the etching rate locally changes around the bubbles is suppressed. Is prevented. In addition, it is particularly effective when producing a silicon member having a complicated and fine structure in which bubbles cannot be effectively removed by stirring of the stirrer 9. As a result, it is possible to obtain silicon, a silicon member, or single-crystal silicon in which projections and roughness are prevented.

[0038]

【Example】

(Specific Example 1) An etching solution obtained by adding 50 g of ethylenediaminetetraacetic acid (EDTA) as a chelating agent to a solution having a composition of 33% potassium hydroxide, 47% water, and 20% isopropyl alcohol was added to the etching apparatus 11 shown in FIG. When the (100) silicon substrate 8 was etched by heating to 60 ° C., a silicon substrate 8a etched smoothly as shown in FIG. 2 was obtained. In the figure, reference numeral 8b denotes a structure formed by anisotropic etching. FIG. 2 is an external perspective view of single-crystal silicon etched by the etching method of the present invention.

(Specific Example 2) 33% of potassium hydroxide, water 4
7% solution of isopropyl alcohol 20%
When the silicon substrate 8 was etched by the etching apparatus 11 shown in FIG. 1 using an etching solution containing 10% of acetone, which is a kind of ketone, a silicon substrate 8c etched substantially smoothly was obtained. Further, when this etching solution was stirred by a stirrer, a smooth silicon substrate having no unevenness was obtained. In the figure, reference numeral 8d denotes a structure formed by anisotropic etching. FIG. 3 is an external perspective view of the single crystal silicon etched by the etching method of the present invention.

Comparative Example 1 33% potassium hydroxide, 4 water
When an etching solution having a composition of 7% and isopropyl alcohol 20% is heated to 60 ° C. by the etching apparatus 11 shown in FIG. 1 to etch the (100) silicon substrate 8,
As shown in FIG. 4, a silicon substrate 8f having pyramid-shaped protrusions (micropyramids) 8e scattered on the surface was obtained. 8g in the figure is a structure formed by anisotropic etching. FIG. 4 is an external perspective view of the silicon substrate when etched by a conventional etching method.

Comparative Example 2 33% potassium hydroxide, water 4
When an etching solution having a composition of 7% and isopropyl alcohol 20% is heated to 60 ° C. by the etching apparatus 11 shown in FIG. 1 to etch the (100) silicon substrate 8,
As shown in FIG. 5, a silicon substrate 8i having irregularities 8h scattered on the substrate surface was obtained. In the figure, reference numeral 8j denotes a structure formed by anisotropic etching. FIG. 5 is an external perspective view of the silicon substrate when etched by a conventional etching method.

As described above, according to the present invention, the use of an etching solution obtained by adding a chelating agent, ketone or acetaldehyde to an alkaline aqueous solution may cause projections to be formed on an etched surface by anisotropic etching of silicon. The occurrence of protrusions can be prevented by preventing metal ions or silicon from re-adhering to the substrate. In particular, it is effective when manufacturing a silicon member having a complicated and fine structure (for example, a silicon bench for an SMT element) in which bubbles are not effectively removed by stirring.

[0043]

In summary, according to the present invention, the following excellent effects are exhibited.

By performing anisotropic etching using an etching solution in which a chelating agent, ketone or acetaldehyde is added to an aqueous alkali solution, a method of etching silicon, a method of manufacturing a silicon member, and a method of etching a silicon member in which projections and roughness are prevented. The provision of the single crystal silicon can be realized.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing an embodiment of an etching apparatus to which a silicon etching method of the present invention is applied.

FIG. 2 is an external perspective view of single-crystal silicon etched by the etching method of the present invention.

FIG. 3 is an external perspective view of single crystal silicon etched by the etching method of the present invention.

FIG. 4 is an external perspective view of a silicon substrate formed by a conventional etching method.

FIG. 5 is an external perspective view of a silicon substrate formed by a conventional etching method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stirrer main body 2 Hot water container 3 Temperature controller 4 Heater 5 Etching liquid container 7 Substrate holder 8 Silicon substrate 9 Stirrer 10 Etching liquid

Claims (18)

[Claims] 1. An etching method for etching silicon with an alkaline aqueous solution, wherein the etching is performed with an etching solution obtained by adding a chelating agent to the alkaline aqueous solution. 2. The method according to claim 1, wherein ethylenediaminetetraacetic acid is used as the chelating agent. 3. An etching method for etching silicon with an alkaline aqueous solution, wherein the etching is performed with an etching solution obtained by adding ketone to the alkaline aqueous solution. 4. The method for etching silicon according to claim 3, wherein the ratio of the ketone is from 1% to 30%. 5. An etching method for etching silicon with an alkaline aqueous solution, wherein the etching is performed with an etching solution obtained by adding an aldehyde to the alkaline aqueous solution. 6. The method according to claim 1, wherein the proportion of the aldehyde is 1% to 30%.
6. The method for etching silicon according to claim 5, wherein 7. A method for manufacturing a silicon member, which is manufactured by etching single crystal silicon with an aqueous alkali solution,
A method for producing a silicon member, characterized by etching with an etching solution obtained by adding a chelating agent to the above alkaline aqueous solution. 8. The method according to claim 7, wherein ethylenediaminetetraacetic acid is used as the chelating agent. 9. A method for manufacturing a silicon member, which is manufactured by etching single crystal silicon with an aqueous alkali solution,
A method for manufacturing a silicon member, characterized by etching with an etching solution obtained by adding a ketone to an alkaline aqueous solution. 10. The method for producing a silicon member according to claim 9, wherein the ratio of the ketone is from 1% to 30%. 11. A method for manufacturing a silicon member by etching single crystal silicon with an alkaline aqueous solution, wherein the etching is performed with an etchant obtained by adding aldehyde to the alkaline aqueous solution. 12. The ratio of the aldehyde is from 1% to 30%.
The method of manufacturing a silicon member according to claim 11, wherein the amount is up to%. 13. An etched single crystal silicon in which a specific orientation is etched, wherein anisotropic etching is performed by etching with an etching solution obtained by adding a chelating agent to an alkaline aqueous solution. 14. The etched single crystal silicon according to claim 13, wherein ethylenediaminetetraacetic acid is used as the chelating agent. 15. Single-crystal silicon etched in a specific direction, wherein the single-crystal silicon is anisotropically etched by etching with an etchant obtained by adding a ketone to an alkaline aqueous solution. 16. The etched single crystal silicon according to claim 15, wherein the proportion of the ketone is from 1% to 30%. 17. An etched single crystal silicon, wherein anisotropic etching is performed by etching with an etching solution obtained by adding an aldehyde to an alkaline aqueous solution, in the single crystal silicon etched in a specific direction. 18. The ratio of the aldehyde is from 1% to 30%.
18. The etched single crystal silicon of claim 17 up to%.