阅读说明：本技术 一种硅蚀刻剂及其应用 (Silicon etchant and application thereof ) 是由 蔡墨勋 于 2020-01-07 设计创作，主要内容包括：本发明是关于一种具有高硅/二氧化硅蚀刻选择比的硅蚀刻剂及其应用。所述的硅蚀刻剂包含至少一个缩酮类化合物和至少一个四级铵氢氧化物,以该硅蚀刻剂的总重量计,该缩酮类化合物所占的重量百分比是20～99重量％,该四级铵氢氧化物所占的重量百分比是0.1～10重量％。(The invention relates to a silicon etchant with high silicon/silicon dioxide etching selectivity ratio and application thereof. The silicon etchant comprises at least one ketal compound and at least one quaternary ammonium hydroxide, wherein the ketal compound accounts for 20-99 wt% of the total weight of the silicon etchant, and the quaternary ammonium hydroxide accounts for 0.1-10 wt%.)

1. A silicon etchant, characterized by: the silicon etchant comprises at least one ketal compound and at least one quaternary ammonium hydroxide, wherein the ketal compound accounts for 20-99 wt% of the total weight of the silicon etchant, and the quaternary ammonium hydroxide accounts for 0.1-10 wt%.

2. The silicon etchant according to claim 1, wherein: the ketal compounds account for 60-90 wt% of the total weight of the silicon etchant.

3. The silicon etchant of claim 1, wherein the ketal-based compound has the following general structural formula:

wherein R is¹、R²、R³And R⁴Can be independently the same or different straight chain or branched alkyl with 1-6 carbon atoms.

4. The silicon etchant according to claim 1, wherein: the ketal compounds comprise: 2,2-dimethyl-1,3-dioxolane-4-methanol, 2-dimethyl-1,3-dioxolane-4-ethanol, 2-dimethyl-1, 3-dioxolane-4-methylchloride and 2,2-dimethyl-1, 3-dioxolane-4-methylamine.

5. The silicon etchant according to claim 1, wherein: the quaternary ammonium hydroxide has R⁵R⁶R⁷R⁸N⁺OH^-In the general formula (II), wherein R⁵、R⁶、R⁷And R⁸Can be independently the same or different straight chain or branched alkyl with 1-4 carbon atoms or alcohol with 1-4 carbon atoms.

6. The silicon etchant according to claim 1, wherein: the quaternary ammonium hydroxide comprises: tetramethylammonium hydroxide, tetraethylammonium hydroxide, ethyltrimethylammonium hydroxide, and 2-hydroxyethyltrimethylammonium hydroxide.

7. The silicon etchant according to claim 1, wherein: the silicon etchant also comprises an aqueous medium.

8. The silicon etchant according to claim 7, wherein: the aqueous medium is water.

9. The silicon etchant according to claim 1, wherein: the silicon etchant is a silicon etchant having a silicon/silicon dioxide etch selectivity greater than 500: 1.

10. The silicon etchant according to claim 1 to 9, wherein: the silicon etchant is applied to the silicon pattern etching procedure of semiconductor nano-process.

11. A method of etching a silicon pattern, comprising: the method for etching a silicon pattern uses the silicon etchant according to claims 1 to 9.

12. The method of etching a silicon pattern according to claim 11, wherein: the etching method of the silicon pattern is applied to the etching procedure of the semiconductor nano process.

Technical Field

The invention relates to a silicon etchant with high silicon/silicon dioxide etching selectivity ratio and application thereof. In particular, the silicon etchant having a high silicon/silicon dioxide etching selectivity ratio comprises at least one ketal-based compound and at least one quaternary ammonium hydroxide, and the silicon/silicon dioxide etching selectivity ratio is greater than 500. The silicon etchant with high silicon/silicon dioxide etching selectivity is applied to the silicon pattern etching procedure of semiconductor nano-process.

Background

In the semiconductor advanced nano-fabrication process, a silicon pattern etching process with a small line width is required, and a silicon dioxide insulating layer and a dielectric layer structure are required to be protected, so that a special silicon etchant is required to be used in the semiconductor advanced nano-fabrication process.

The conventional silicon etchant comprises quaternary ammonium, organic amine and polyol, but this type of silicon etchant corrodes silicon dioxide, and thus cannot protect silicon dioxide insulating layer and dielectric layer structure, and thus cannot be applied to silicon pattern etching process in semiconductor nano-fabrication process.

The silicon etchant used in the etching procedure of the semiconductor nano-process at present cannot effectively protect the silicon dioxide insulating layer and the dielectric layer structure, so that the effect of etching silicon patterns with micro line width cannot be achieved in more advanced processes, the process yield is too low, and the industrial requirements cannot be met. In view of the above, the development of a silicon etchant with high etching selectivity is a technical field in which research and development are needed in the semiconductor industry.

Disclosure of Invention

In view of the background of the invention described above, it is a first object of the present invention to provide a silicon etchant having high silicon/silicon dioxide (Si/SiO) in order to meet industrial requirements₂) The selectivity of etching can effectively protect the silicon dioxide insulating layer and the dielectric layer structure, and can be applied to the silicon pattern etching procedure of semiconductor nano-process.

Specifically, the silicon etchant provided by the invention has a selectivity ratio of more than 500:1 silicon/silicon dioxide etching; the silicon etchant comprises at least one ketal compound and at least one quaternary ammonium hydroxide; based on the total weight of the silicon etchant, the ketal compound accounts for 20-99 wt%, and the quaternary ammonium hydroxide accounts for 0.1-10 wt%. Preferably, the ketal compound accounts for 60 to 90 wt%.

One of the ketal compounds of the invention has the following structural general formula: wherein R is¹、R²、 R³And R⁴Can be independently the same or different straight chain or branched alkyl with 1-6 carbon atoms.

Preferably, the ketal compound of the invention further comprises 2,2-Dimethyl-1,3-dioxolane-4-methanol (acetonide, 2,2-Dimethyl-1,3-dioxolane-4-methanol), 2,2-Dimethyl-1,3-dioxolane-4-ethanol (2,2-Dimethyl-1,3-dioxolane-4-ethanol), 2,2-dimethyl-1, 3-dioxolane-4-methylchloride (4-Chloromethyl-2,2-dimethyl-1,3-dioxolane) and 2,2-dimethyl-1, 3-dioxolane-4-methanamine (2,2-dimethyl-1, 3-dioxolane-4-methanamine).

The quaternary ammonium hydroxides of the present invention have R⁵R⁶R⁷R⁸N⁺OH^-In the general formula (II), wherein R⁵、R⁶、R⁷And R⁸Can be independently the same or different straight chain or branched alkyl with 1-4 carbon atoms or alcohol with 1-4 carbon atoms.

A second object of the present invention is to provide a method for etching a silicon pattern using the silicon etchant according to the first object of the present invention. The silicon etchant has high silicon/silicon dioxide (Si/SiO)₂) The etching selection ratio can effectively protect the silicon dioxide insulating layer and the dielectric layer structure, reduce the corrosion damage of the silicon dioxide insulating layer and the dielectric layer structure in the etching process and is very suitable for being applied to the advanced nano-manufacturing process of semiconductors to etch silicon patterns with micro line width.

Specifically, the silicon etchant described above is for silicon/silicon dioxide (Si/SiO)₂) The etch selectivity is greater than 500: 1. Preferably, the silicon etchant described above is silicon/silicon dioxide (Si/SiO)₂) The etching selectivity is over 1000: 1.

Detailed Description

The foregoing and other aspects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments, as illustrated in the accompanying drawings. In order that the invention may be fully understood, specific steps and components thereof will be set forth in the following description. It will be apparent that the invention may be practiced without limitation to specific details that are within the skill of one of ordinary skill in the art. In other instances, well-known components or steps have not been described in detail so as not to unnecessarily obscure the present invention. While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment.

According to a first embodiment of the present invention, the present invention provides a silicon etchant, which comprises at least one ketal compound and at least one quaternary ammonium hydroxide, wherein the ketal compound accounts for 20 to 99 wt% and the quaternary ammonium hydroxide accounts for 0.1 to 10 wt% of the total weight of the silicon etchant.

In a preferred embodiment, the silicon etchant of the present invention comprises, based on the total weight of the silicon etchant, 60 to 90 wt% of the ketal compounds.

In one embodiment, one of the ketal compounds of the present invention has the following general structural formula: wherein R is¹、R²、R³And R⁴Can be independently the same or different straight chain or branched alkyl with 1-6 carbon atoms.

In a preferred embodiment, the ketal compounds of the invention comprise: 2,2-Dimethyl-1,3-dioxolane-4-methanol (glycerol acetonide, 2, 2-dimehyl-1, 3-dioxolane-4-methanol), 2,2-Dimethyl-1,3-dioxolane-4-ethanol (2, 2-dimehyl-1, 3-dioxolane-4-ethane), 2,2-Dimethyl-1, 3-dioxolane-4-methylchloride (4-Chloromethyl-2, 2-dioxolane-1, 3-dioxolane), and 2,2-Dimethyl-1,3-dioxolane-4-methylamine (2,2-Dimethyl-1, 3-dioxolane-4-methanamine).

The above-mentioned 2,2-Dimethyl-1,3-dioxolane-4-methanol (glycerol acetonide, 2,2-Dimethyl-1,3-dioxolane-4-methanol) has the following structural formula.

The 2,2-dimethyl-1,3-dioxolane-4-ethanol (2,2-dimethyl-1,3-dioxolane-4-ethanol) has the following structural formula.

The 2,2-dimethyl-1,3-dioxolane-4-methyl chloride (4-Chloromethyl-2,2-dimethyl-1,3-dioxolane) has the following structural formula.

The 2,2-dimethyl-1,3-dioxolane-4-methylamine (2,2-dimethyl-1,3-dioxolane-4-methylamine) has the following structural formula.

In one embodiment, the quaternary ammonium hydroxides of the present invention have R⁵R⁶R⁷R⁸N⁺OH^-In the general formula (II), wherein R⁵、R⁶、R⁷And R⁸Can be independently the same or different straight chain or branched alkyl with 1-4 carbon atoms or alcohol with 1-4 carbon atoms.

In a preferred embodiment, the quaternary ammonium hydroxides of the present invention comprise: tetramethylammonium Hydroxide (TMAH), tetraethylammonium Hydroxide (TEAH), Ethyltrimethylammonium Hydroxide (ETMAH), and 2-hydroxyethyltrimethylammonium Hydroxide (2-hydroxyethyltrimethylammonium Hydroxide).

In one embodiment, the silicon etchant further comprises an aqueous medium. Preferably, the aqueous medium is water.

In a representative embodiment, the silicon etchant of the present invention comprises the ketal compounds described above, the quaternary ammonium hydroxide described above, and water. Wherein the ketal compound accounts for 20 to 99 weight percent of the total weight of the silicon etchant, the quaternary ammonium hydroxide accounts for 0.1 to 10 weight percent of the total weight, and the quaternary ammonium hydroxide is not more than one hundred weight percent of the total weight, and only water needs to be supplemented until the total weight is one hundred percent.

In one embodiment, the silicon etchant of the present invention is a silicon on silicon dioxide (Si/SiO)₂) A silicon etchant having an etch selectivity greater than 500: 1.

In a preferred embodiment, the silicon etchant of the present invention is a silicon on silicon dioxide (Si/SiO)₂) Silicon etchant with etching selectivity ratio of more than 1000:1

In one embodiment, the silicon etchant of the present invention is applied to a silicon pattern etching process in a semiconductor nano-fabrication process.

According to a second embodiment of the present invention, there is provided a method of etching a silicon pattern using the silicon etchant according to the first embodiment of the present invention. The silicon etchant has high silicon/silicon dioxide (Si/SiO)₂) The etching selection ratio can effectively protect the silicon dioxide insulating layer and the dielectric layer structure, reduce the corrosion damage of the silicon dioxide insulating layer and the dielectric layer structure in the etching process and is very suitable for being applied to the advanced nano-manufacturing process of semiconductors to etch silicon patterns with micro line width.

The following examples are experiments conducted according to the contents of the above embodiments, and are therefore provided as a detailed description of the present invention.

The first example is as follows: etch rate testing of silicon etchants and silicon/silicon dioxide (Si/SiO)₂) Method for evaluating etching selectivity

The test of the etching rate of the silicon etchant is carried out in an environment with the temperature of 60 ℃. The test samples were each a silicon (a-Si) film having an amorphous silicon (a-Si) film on the surface and a thickness ofThe wafer (wafer) and the surface being silicon dioxide (SiO)₂) Film of a thickness ofAs a measure of silicon (Si) etch rate and silicon dioxide (SiO)₂) Test samples of etch rate. The experimental procedure for measuring the etch rate is as follows: firstly, an ellipsometry thickness gauge is used for respectively measuring the initial film thickness X of the thin film on the surface of the wafer sampleCompletely soaking the wafer sample in an etchant at 60 ℃ to perform wafer surface film etching for 2-60 minutes, immediately taking out the wafer after the time is up, fully cleaning the wafer with pure water, and measuring by using an ellipsometer to obtain the film thickness Y of the etched wafer surface film

The formula for calculating the etching rate is as follows

Using the above experimental methods and calculations, silicon etchant pairs of silicon (Si) and silicon dioxide (SiO), respectively, can be obtained₂) The etching rate of (3).

Finally, the etching rate of Si is divided by SiO₂The etching rate of (A) to (B) can be adjusted to obtain silicon/silicon dioxide (Si/SiO) of the silicon etchant₂) The selectivity of the etching.

According to the experimental method described in the first example, the silicon/silicon dioxide (Si/SiO) etching solutions of the silicon etchants described in examples 1 to 6 and comparative examples 1 to 5 were performed, respectively₂) Evaluation of etching selectivity. Silicon etchant composition, silicon (Si) etching rate, and silicon dioxide (SiO) used in examples 1 to 6 and comparative examples 1 to 5₂) Etch rate and silicon/silicon dioxide (Si/SiO)₂) The etching selection ratio is shown in table one.

Watch 1

1.MEA：Monoethanolamine

2.EG：Ethylene glycol

As shown in the Table I, examples 1 to 6 are the experimental results of the silicon etchant containing ketal compound and quaternary ammonium hydroxide according to the present invention, which is silicon/silicon dioxide (Si/SiO)₂) The etching selectivity ratio is more than 500; particularly, when the percentage by weight of the acetonide of the silicon etchant is 60% or more, the silicon etchant has silicon/silicon dioxide (Si/SiO)₂) The etching selectivity is greater than 1000. In contrast, comparative examples 1 to 4 are experimental results of conventional silicon etchants not containing ketal compounds, which are silicon/silicon dioxide (Si/SiO)₂) The etching selectivity ratio is less than 500; comparative example 5 is a control experiment using a silicon etchant with less than 20% by weight of acetone glycidol, which is silicon/silicon dioxide (Si/SiO)₂) The etching selectivity is less than 500; accordingly, the silicon etchant containing 20-99 wt% of ketal compounds and 0.1-10 wt% of quaternary ammonium hydroxide provided by the present invention has improved silicon/silicon dioxide (Si/SiO) compared to the conventional silicon etchant₂) Efficacy of selection ratio. Secondly, since the silicon etchant of the present invention has silicon/silicon dioxide (Si/SiO) of more than 500₂) The etching selectivity is very suitable for the silicon pattern etching with tiny line width in the advanced semiconductor nano-process.

While the present invention has been described with reference to the specific examples, it should be understood that the scope of the present invention is not limited thereto, and various changes and modifications may be made without departing from the spirit and scope of the present invention. In addition, the abstract and the title of the invention are provided for assisting the search of patent documents and are not intended to limit the scope of the invention.