KR20180010483A - Eching composition for etching a polysilicon and method for manufacturing a semiconductor device - Google Patents

Abstract

The purpose of the present invention is to provide a polysilicon etchant composition which allows an etched polysilicon film to have excellent surface roughness by providing excellent etching rates. Provided are a polysilicon etchant composition comprising 0.1-30 wt% of quaternary alkyl ammonium hydroxide, 0.001-5 wt% of a fluoro-based surfactant, 0.1-20 wt% of an antioxidant and residual water, and a semiconductor device manufactured by using the same.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of manufacturing a polysilicon etchant,

The present invention relates to a polysilicon etchant composition and a method of manufacturing a semiconductor device using the same.

Semiconductor devices are required to operate at high speeds and to have a large storage capacity. In response to this demand, the manufacturing technology of the semiconductor device is being developed in the direction of improving the degree of integration, reliability, and response speed.

In the above-described semiconductor device, polysilicon is used as a material for forming a gate electrode, a capacitor electrode, a plug, an etch mask, and the like, and is used in a wide variety of applications. For this purpose, a method of forming a film using polysilicon and a method of removing a formed polysilicon film have been developed variously.

The method of removing the polysilicon film can be roughly divided into a dry etching process and a wet etching process. The wet etching process is a process of etching using a chemical etching solution, and an etching process is performed by immersing the object to be removed in an etching solution.

As a conventional polysilicon etchant, Korean Patent Laid-Open No. 10-2011-0044214 discloses a process for producing an etchant comprising the steps of (A) tetramethylammonium hydroxide, (B) hydroxylamine, and (C) carbon dioxide (CO ₂ ) and / or tetramethylammonium carbonate Which is an alkaline aqueous solution having a pH of 13 or more.

Korean Patent Laid-Open Publication No. 10-2013-0007419 discloses a silicon etching solution containing a combination of ammonia and at least one specific basic compound selected from the group consisting of a hydroxylamine compound, a basic organic compound and a metal-containing basic compound Lt; / RTI >

However, since the compositions have to be etched at a high temperature, the etchant components are rapidly changed due to the volatilization and decomposition of the etchant components. Therefore, the compositions have a disadvantage that they have a large change in etching rate and can not secure a desirable surface roughness due to an excessive etching rate .

Korean Patent Publication No. 10-2011-0044214 Korean Patent Publication No. 10-2013-0007419

Disclosure of Invention Technical Problem [8] The present invention has been made to solve the above-

It is an object of the present invention to provide a polysilicon etchant composition which provides an excellent etching rate even when etching is performed at room temperature and allows the etched polysilicon film to have excellent surface roughness.

It is another object of the present invention to provide a polysilicon etchant composition capable of uniformly removing a film quality at a high speed even when only a predetermined thickness of a polysilicon film is removed to provide a uniform and excellent surface roughness.

It is another object of the present invention to provide an efficient method of manufacturing a semiconductor device using the above-mentioned polysilicon etchant composition.

According to the present invention,

The present invention provides a polysilicon etchant composition comprising 0.1 to 30% by weight of quaternary alkyl ammonium hydroxide, 0.001 to 5% by weight of a fluorinated surfactant, 0.1 to 20% by weight of an antioxidant and a residual amount of water, based on the total weight of the composition.

In addition,

And a step of etching the polysilicon film using the polysilicon etchant composition of the present invention.

The polysilicon etchant composition of the present invention provides an excellent etching rate even when etching is performed at room temperature, and provides an effect that the etched polysilicon film has excellent surface roughness.

In addition, the polysilicon etchant composition of the present invention uniformly removes the film quality at a high speed even when only a predetermined thickness of the polysilicon film is removed, thereby providing a film having uniform surface roughness.

Further, the polysilicon etchant composition of the present invention improves the reliability of the process for the subsequent process based on the above-described effects, thereby improving the quality and productivity of the semiconductor device.

Further, the present invention provides an efficient method for manufacturing a high-quality semiconductor device by using the above-mentioned polysilicon etchant composition.

According to the present invention,

The present invention relates to a polysilicon etchant composition comprising 0.1 to 30% by weight of quaternary alkyl ammonium hydroxide, 0.001 to 5% by weight of a fluorinated surfactant, 0.1 to 20% by weight of an antioxidant and water in a residual amount relative to the total weight of the composition.

Hereinafter, the components of the etchant composition will be described in detail.

Fourth grade Alkylammonium hydroxide

The quaternary alkyl ammonium hydroxide used in the present invention may be represented by the general formula [N (R) ₄ ] ⁺ OH ^- (R is an alkyl group having 1 to 4 carbon atoms). Examples of the quaternary alkyl ammonium hydroxide represented by the general formula include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide and the like. Among these quaternary ammonium hydroxides, tetramethylammonium hydroxide (hereinafter referred to as "TMAH") is particularly preferably used.

These quaternary alkyl ammonium hydroxides may be included in an amount of 0.1 to 30 wt%, more preferably 0.3 to 12 wt%, and even more preferably 0.5 to 10 wt% based on the total weight of the composition. When the content of the quaternary alkyl ammonium hydroxide is lower than the above range, the etching rate of the polysilicon is lowered. When the content of the quaternary alkyl ammonium hydroxide is more than the above range, no further increase in the etching rate is observed

Fluoric surfactant

The fluorinated surfactant means a hydrocarbon surfactant containing a perfluoroalkyl group in the main chain or side chain of a compound containing a hydrophilic group and a hydrophobic group. Particularly, it is more preferable that all hydrogen bonded to carbon contained in the hydrophobic group is substituted with fluorine.

Examples of the fluorine-based surfactant include anionic fluorine surfactants including perfluoroalkylcarboxylic acid salts, perfluoroalkylsulfuric acid salts, and perfluoroalkylphosphates; A cationic fluorine surfactant including a perfluoroalkylamine salt and a perfluoroalkyl quaternary ammonium salt; An amphoteric fluorine surfactant including perfluoroalkyl carboxybetaine and perfluoroalkyl sulfobetaine; And nonionic fluorine surfactants such as perfluoroalkylpolyoxyethylene and fluorinated alkyl esters. These surfactants may be used alone or in combination of two or more. Of these, a fluorocarbon-based compound comprising a nonionic system of perfluoroalkylpolyoxyethylene and a perfluorinated alkyl ester is preferably used.

The term "perfluoroalkyl" as used herein means a C1-C10 linear or branched alkyl group in which all of the hydrogen bonded to the carbon atom is substituted with fluorine.

The fluorosurfactant may be included in an amount of 0.001 to 5.0% by weight, more preferably 0.005 to 1.0% by weight, and still more preferably 0.01 to 0.5% by weight based on the total weight of the composition. If the amount of the fluorinated surfactant is less than 0.001 wt%, the effect of lowering the surface tension of the silicon surface is insignificant and the uniform etching effect is lowered. If the fluorinated surfactant is more than 5.0 wt%, the effect of lowering the surface tension is not further increased, It is not economically preferable.

Antioxidant

The antioxidant in the present invention captures the dissolved oxygen present in the etchant to inhibit oxygen from reacting with the polysilicon surface to form an oxide film, thereby smoothly etching the polysilicon film by hydroxyl groups even at room temperature do.

Examples of the antioxidant in the present invention include hydroxylamine compounds such as hydroxylamine, dimethylhydroxylamine, diethylhydroxylamine and isopropylhydroxylamine; Carbohydrazide, ascorbic acid, 4-methyl-1-aminopiperazine, 1,3-dimethyl-5-pyrazolone (1,3-dimethyl -5-pyrazolone, hydroquinone, methylethylketoxime, 1,3-dimethyl-5-pyrazolone, Urazole, 1,2 , 4-triazolidine-3,5-dione).

The antioxidant may be included in an amount of 0.1 to 20 wt%, more preferably 0.5 to 5.0 wt%, and still more preferably 0.5 to 1.0 wt% based on the total weight of the composition. When the antioxidant is contained in an amount of less than 0.1% by weight, the effect of suppressing oxidation of the silicon surface is reduced by trapping dissolved oxygen in the etching solution. When the amount exceeds 20% by weight, the oxygen trapping effect is not further increased, It is not preferable.

water

The water contained in the etchant composition of the present invention is not particularly limited, but deionized water is preferred. More preferably, it is preferable to use deionized water having a resistivity value of water (i.e., the degree of removal of ions in water) of 18 M? / Cm or more. Water is included as a balance such that the total weight of the composition is 100% by weight.

The etchant composition of the present invention may further contain conventional additives such as corrosion inhibitors used in this field in addition to the above-mentioned components.

The etchant composition of the present invention can be manufactured by a conventionally known method, and preferably has a purity for semiconductor processing.

The polysilicon etchant composition is used in a polysilicon film etch process. At this time, the polysilicon film etching method can be performed by a method commonly known in the art. For example, etching may be performed using deposition, spraying, or deposition and spraying in a batch type of etching apparatus or a single type of etching apparatus. In this case, the temperature may be 20 to 70 ° C, preferably 20 to 50 ° C. If the etching equipment is operated under a clean room environment in which the temperature is kept constant, the polysilicon film can be etched even at room temperature without additional heating desirable. That is, it is preferable to prevent a temperature variation occurring when the heating apparatus is used and a non-uniform etching caused by the influence thereof.

The immersion and spraying time can be generally from 30 seconds to 10 minutes, preferably from 1 to 5 minutes. However, these conditions are not strictly applied and can be selected by those skilled in the art as being convenient or suitable.

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. However, the following examples and comparative examples are provided for illustrating the present invention, and the present invention is not limited by the following examples, and various modifications and changes may be made.

Example  1 to 15 and Comparative Example  1 to 7: Polysilicon Etchant  Preparation of composition

The etchant compositions of Examples 1 to 15 and Comparative Examples 1 to 7 were prepared according to the compositions shown in Table 1 below.

Furtherance
(weight%) 4 water-alkylammonium oxide Fluoric surfactant Antioxidant Other
(content) water TMAH ^{1 )} TEAH ^{2 )} TBAH ^{3 )} PFAS ^{4 )} PFAP ^{5 )} PFEO ^{6 )} A-1 ⁷⁾ A-2 ⁸⁾ A-3 ⁹⁾ Example 1 One - - 0.1 - - One - - Balance Example 2 3 - - - 0.1 - One - - Balance Example 3 5 - - - - 0.1 - One - Balance Example 4 - One - - 0.1 - - One - Balance Example 5 1.5 - - - - 0.05 - - 0.5 Balance Example 6 - 2 - 0.05 - - - - 0.5 Balance Example 7 - - 3 - 0.05 - One - - Balance Example 8 2 - - - - 0.05 - One - Balance Example 9 One - - 0.2 - - - - One Balance Example 10 10 - - - 0.01 - - - 1.5 Balance Example 11 - 2 - 0.5 - - 0.5 - - Balance Example 12 3 - - - - 0.2 5.0 - - Balance Example 13 - - 5 0.05 - 0.05 2.0 Balance Example 14 2 - - - 0.02 - 0.3 0.2 Balance Example 15 - 0.5 - - - 0.1 - 0.5 - Balance Comparative Example 1 0.05 - - 0.1 - - - 0.5 - Balance Comparative Example 2 - 0.1 - - - - 0.2 - - Balance Comparative Example 3 2 - - - 0.2 - - 0.05 - Balance Comparative Example 4 - - - 0.05 - - 0.5 - - Balance Comparative Example 5 - - - - 0.01 - 15 - - Balance Comparative Example 6 10 - - - - - 10 - - TMAC ^{10 )} (10) Balance Comparative Example 7 10 - - - - - - - - NH ₄ OH (4) Balance 1) TMAH: tetramethylammonium hydroxide
2) TEAH: tetraethylammonium hydroxide
3) TBAH: tetrabutylammonium hydroxide
4) PFAS: Perfluoroalkylsulfate (PFAS)
5) PFAP: perfluoroalkylphosphate (PFAP)
6) PFEO: perfluoroalkylpolyoxyethylene (PFE)
7) A-1: Diethylhydroxylamine
8) A-2: Carbohydrazide
9) A-3: Hydroquinone
10) TMAC: A mixed aqueous solution of tetramethylammonium carbonate and tetramethylammonium hydrogencarbonate

Test Example : Etch characteristics  evaluation

(One) On polysilicon  About Etching  Speed rating

A wafer having polysilicon deposited to a thickness of 150 ANGSTROM on a silicon wafer was cut into a size of 2 X 2 cm to prepare a specimen. The specimens were immersed in a constant temperature bath at 25 DEG C for 1 minute containing the etchant compositions of the Examples and Comparative Examples.

Then, the specimens were taken out, washed with water, dried using nitrogen, and then the film thickness of polysilicon was measured using an Elipsometer (FE5000S; manufactured by Ostuka), and the etching rate of the polysilicon film Respectively. The etching rate was evaluated according to the following criteria, and the results are shown in Table 2 below.

<Evaluation Criteria of Etching Rate>

◎: etching rate of 80 Å / min or more

O: etching rate of 40 to less than 80 Å / min

DELTA: etching rate less than 40 A / min

Х: Not etched

(2) Of polysilicon Surface roughness  evaluation

The surface roughness of the specimen used for the etching rate evaluation was analyzed using AFM. The evaluation criteria were as follows. The results are shown in Table 2 below.

&Lt; Surface roughness evaluation standard &

◎: RMS less than 10 Å

?: RMS 10 to less than 15 A

?: RMS 15 to less than 20 Å

Х: RMS 20 Å or more

Polysilicon etching rate Surface roughness Example 1 ○ ◎ Example 2 ◎ ○ Example 3 ◎ ○ Example 4 ○ ◎ Example 5 ◎ ◎ Example 6 ◎ ◎ Example 7 ○ ◎ Example 8 ◎ ○ Example 9 ○ ◎ Example 10 ◎ ○ Example 11 ○ ◎ Example 12 ○ ○ Example 13 ◎ ○ Example 14 ○ ◎ Example 15 ○ ◎ Comparative Example 1 △ ◎ Comparative Example 2 △ △ Comparative Example 3 △ △ Comparative Example 4 X ◎ Comparative Example 5 X ◎ Comparative Example 6 ◎ X Comparative Example 7 ◎ X

As shown in Table 2, it was confirmed that the etching solution compositions of Examples 1 to 15 exhibited excellent properties in both the etching rate of polysilicon and the surface roughness.

On the other hand, in the case of the etching solution compositions of Comparative Examples 1 to 7 which contained no component of the composition of the present invention or whose components were out of the range of the composition ratios, the etching composition showed an insufficient effect on at least one of the etching rate and the surface roughness.

Claims (6)

0.1 to 30% by weight of quaternary alkyl ammonium hydroxide, 0.001 to 5% by weight of a fluorinated surfactant, 0.1 to 20% by weight of an antioxidant and water in a residual amount based on the total weight of the composition. The method according to claim 1,
Wherein the quaternary alkyl ammonium hydroxide is a compound represented by the following Formula 1:
[Chemical Formula 1]
[N (R) ₄ ] ⁺ OH ^-
remind R is an alkyl group having 1 to 4 carbon atoms. The method according to claim 1,
Wherein the fluorine-based surfactant is at least one selected from the group consisting of an anionic fluorine surfactant, a cationic fluorine surfactant, an amphoteric fluorine surfactant, and a nonionic fluorine surfactant. Composition. The method according to claim 1,
The fluorosurfactant may be selected from the group consisting of perfluoroalkylcarboxylic acid salts, perfluoroalkylsulfuric acid salts, perfluoroalkylphosphates, perfluoroalkylamine salts, perfluoroalkyl quaternary ammonium salts, perfluoroalkylcarboxybetaines, perfluoroalkylsulfobetaines, Alkyl polyoxyethylene, alkylpolyoxyethylene, and perfluorinated alkyl ester. &Lt; RTI ID = 0.0 &gt; 8. &lt; / RTI &gt; The method according to claim 1,
The antioxidant may be at least one selected from the group consisting of hydroxylamine compounds, Carbohydrazide, Ascorbic acid, 4-Methyl-1-aminopiperazine, 1,3-dimethyl- 5-pyrazolone, 1,3-dimethyl-5-pyrazolone, hydroquinone, methylethylketoxime, 1,3-dimethyl- ), And Urazole (1,2,4-triazolidine-3,5-dione). The polysilicon etchant composition according to claim 1, A method for manufacturing a semiconductor device, comprising the step of etching a polysilicon film using the polysilicon etchant composition of claim 1.