JP2019163362A - Glass substrate cleaning liquid - Google Patents

Abstract

To provide a glass substrate cleaning liquid in which precipitation of dissolved products is suppressed.SOLUTION: This invention relates to a glass substrate cleaning liquid containing (A) a hydrogen fluoride, (B) a hydrogen fluoride salt, (C) an alkylene polyamine polycarboxylic acid in which the total number of a carboxyl group and a hydroxy group is an odd number (where, the number of hydroxy group(s) may be 0), and (D) water.SELECTED DRAWING: None

Description

The present invention relates to a glass substrate cleaning liquid.

In the manufacturing process of a polysilicon thin film transistor (TFT), when a contact hole is formed in an insulating layer, dry etching is performed in order to increase etching processing accuracy. After the dry etching is completed, etching residues are generated on the sidewalls of the contact holes and silicon oxide films are generated on the bottoms, which need to be removed.

Patent Document 1 discloses a method of using a mixed solution of HF and NH4F (buffered hydrofluoric acid (BHF)) as a cleaning solution for such etching residue and oxide film. However, when BHF is used, there is no problem in the cleaning property of the etching residue and oxide film, but there is a problem that the deposit is generated due to the deposition of the dissolved matter and clogs the filter of the cleaning treatment tank. .

International Publication No. 99/44227

An object of this invention is to provide the washing | cleaning liquid of the glass substrate which suppressed precipitation of a melt.

The present inventors have found that when a specific alkylene polyamine polycarboxylic acid is used for BHF, precipitation of a dissolved substance can be suppressed during cleaning of a glass substrate, and the present invention has been completed.

That is, the present invention relates to (A) hydrogen fluoride, (B) hydrogen fluoride salt, (C) an alkylene polyamine poly having a total sum of carboxyl groups and hydroxyl groups (provided that the hydroxyl groups may be 0). The present invention relates to a glass substrate cleaning solution containing carboxylic acid and (D) water.

(A) Component 1-5 wt%, (B) component 10-50 wt%, (C) component 0.2-5 wt%, and (D) component 30-85 wt% Is preferred.

It is preferable that the hydrogen fluoride salt (B) is ammonium fluoride.

The component (C) is preferably diethylenetriaminepentaacetic acid and / or 1,3-diamino-2-propanoltetraacetic acid.

The cleaning liquid is preferably a substrate whose glass substrate has a silicon semiconductor and is used for removing an oxide film on the silicon surface.

The cleaning liquid is preferably used for removing etching residues or silicon oxide films generated by dry etching of contact holes.

(C) It is preferable not to contain chelating agents other than a component substantially.

Since the cleaning liquid of the present invention contains a specific chelating agent in the cleaning liquid containing BHF, precipitation of dissolved matter can be suppressed.

(A) shows a schematic cross-sectional view of a polysilicon TFT after dry etching, and (b) shows a schematic cross-sectional view of the polysilicon TFT after applying the cleaning liquid of the present invention.

In the glass substrate cleaning liquid of the present invention, (A) hydrogen fluoride, (B) hydrogen fluoride salt, (C) the sum of carboxyl groups and hydroxyl groups is an odd number (however, the hydroxyl groups may be 0). An alkylene polyamine polycarboxylic acid and (D) 30 to 85% by weight of water are contained. When the cleaning liquid of the present invention is used, the precipitation of the melt can be suppressed. Here, the melt can be a glass melt or a composite with silicon.

The content of hydrogen fluoride (A) in the cleaning liquid is preferably 1 to 5% by weight, more preferably 2 to 5% by weight. If it is less than 1% by weight, the oxide film removal rate and etching residue removal property are insufficient, and if it exceeds 5% by weight, the oxide film removal rate and the glass dissolution rate tend to be too large to be controlled. Hydrofluoric acid can be used as the hydrogen fluoride source, but the content is the content of hydrogen fluoride.

The hydrogen fluoride salt is not particularly limited as long as it is used together with hydrogen fluoride and has a buffering action, and examples thereof include ammonium fluoride and ammonium hydrogen fluoride. An aqueous solution of hydrogen fluoride can be used as the source of hydrogen fluoride, but the content is the content of hydrogen fluoride.

The content of the hydrogen fluoride salt (B) in the cleaning liquid is preferably 10 to 50% by weight, more preferably 15 to 40% by weight. If it is less than 10% by weight, the oxide film removal rate and the etching residue removal property are insufficient, and if it exceeds 50% by weight, the oxide film removal rate and the glass dissolution rate tend to be too large to be controlled.

The alkylene polyamine polycarboxylic acid (C) is a compound having an alkylene chain, one or more amino groups, and two or more carboxyl groups in the molecule, and the sum of the carboxyl groups and hydroxyl groups is an odd number. The number of hydroxyl groups may be 0, but is preferably 1 to 3 when contained. The alkylene may be monoalkylene or polyalkylene. Specifically, (c-1) an alkylene polyamine polycarboxylic acid containing an odd number of carboxyl groups, or (c-2) an alkylene polyamine polycarboxylic acid containing an even number of carboxyl groups and an odd number of hydroxyl groups. Etc. It is preferable that a chelating agent other than (C) such as (c-1) or (c-2) is substantially not contained in that the effect of suppressing precipitates may be reduced.

In the alkylene polyamine polycarboxylic acid (c-1) containing an odd number of carboxyl groups, the number of carboxyl groups is an odd number of 3 or more, but 3 or 5 is preferable. The number of amino groups is not particularly limited, but is preferably 2-5. Examples of the alkylene polyamine include diethylenetriamine, dipropylenetriamine, and tetraethylenepentamine. Specific examples of the component (c-1) include diethylenetriaminepentaacetic acid (DTPA) and tetraethylenepentaminepentaacetic acid. Of these, DTPA is preferable from the viewpoint of availability.

In the alkylene polyamine polycarboxylic acid (c-2) containing an even number of carboxyl groups and an odd number of hydroxyl groups, the number of carboxyl groups is an even number of 2 or more, but 2, 4 and 6 are preferred. The number of amino groups is not particularly limited, but is preferably 2-5. Specific examples of the component (c-2) include 1,3-diamino-2-propanoltetraacetic acid (DPTA-OH), which is preferable in that stable ability is obtained.

The content of the alkylene polyamine polycarboxylic acid (C) in the cleaning liquid is preferably 0.2 to 5% by weight, and more preferably 1 to 3% by weight. If the amount is less than 0.2% by weight, the effect of suppressing the precipitate is insufficient, and if it exceeds 5% by weight, there is not necessarily a malfunction in capacity, but it takes time to dissolve the component (C) and is uneconomical.

As water (D) that can be used in the present invention, pure water or ultrapure water can be preferably used. The content of water (D) in the cleaning liquid is preferably 30 to 85% by weight, but more preferably 50 to 80% by weight. If it is less than 30% by weight, the oxide film removal rate and the glass melting rate become so large that it cannot be controlled. If it exceeds 85% by weight, the oxide film removal rate and the etching residue removal property become insufficient.

In addition to the components (A) to (D), components generally used as a glass substrate cleaning solution can also be added to the cleaning solution of the present invention. For example, surfactants, antifoaming agents, anticorrosives, organic solvents and the like can be mentioned. Each of these components may be used alone or in combination of two or more.

The cleaning liquid of the present invention is applied to a glass substrate. The glass substrate as an object to be cleaned is not particularly limited, and examples thereof include a glass substrate having a silicon semiconductor, and an insulating layer such as a silicon nitride film, a silicon oxide film, a silicon oxynitride film, or a silicon nitride oxide film is formed. Also good. Specific examples include a glass substrate for display, and examples of the glass substrate for display include a glass substrate for TFT liquid crystal display and a glass substrate for organic EL display.

The cleaning liquid of the present invention is suitably used for removing the oxide film on the silicon semiconductor surface. Furthermore, for example, when a contact hole is formed in an insulating layer in a manufacturing process of a display, for example, a polysilicon TFT, if dry etching is performed in order to increase the etching processing accuracy, an etching residue is generated after the dry etching is completed. It remains or an oxide film is formed on the bottom of the contact hole, that is, on the silicon surface. The cleaning liquid of the present invention can remove these efficiently. FIG. 1A is a schematic cross-sectional view of a polysilicon TFT after dry etching, in which an etching residue 6 is generated on the side wall of the contact hole 5 and an Si oxide film 7 is generated on the bottom of the contact hole 5. When the cleaning liquid of the present invention is applied, the etching residue 6 and the Si oxide film 7 are removed as shown in FIG. Note that although FIG. 1 shows a stacked mode of a silicon nitride film and a silicon oxide film, the insulating layer is not limited to this. For example, a silicon oxynitride film, a silicon nitride oxide film, or the like may be used, and a single layer may be used instead of a stacked layer.

The etching rate of SiO ₂ at 24 ° C. of the cleaning agent of the present invention is not particularly limited and can be appropriately changed while adjusting the concentration. For example, when used for cleaning contact holes, excessive etching of the hole side wall is suppressed. However, from the viewpoint of sufficiently removing the oxide film at the bottom of the hole, 200 to 40 nm / min is preferable.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated, this invention is not limited to a following example. Hereinafter, “%” means “% by weight” unless otherwise specified.

Hereinafter, the compounding components used in Examples and Comparative Examples will be described.
A 55% HF aqueous solution was used as the hydrogen fluoride source, and a 40% NH ₄ F aqueous solution was used as the ammonium fluoride.

(Chelating agent)
(C-1) Diethylenetriaminepentaacetic acid (DTPA)
(C-2) 1,3-diamino-2-propanoltetraacetic acid (DPTA-OH)
Malonic acid citrate ethylenediaminetetraacetic acid (EDTA)
Ethylenediamine-N, N'-disuccinic acid (EDDS)
N, N, N ′, N′-ethylenediaminetetrakis (methylenephosphonic acid) hydrate (EDTMP)
2-phosphono-1,2,4-butanetricarboxylic acid (PBTC)

Examples 1-9 and Comparative Examples 1-12
HF, NH 4 _F, a chelating agent, and water were mixed so that the content described in Table 1-2, to prepare a cleaning solution. The following tests were conducted using these cleaning solutions.

<Glass substrate cleaning test>
10 g of the cleaning solution is put in a resin cup, and the temperature is adjusted to 40 ° C. while stirring, and the glass substrate for a liquid crystal display cut into 2 × 2 cm (P-Si for the silicon semiconductor, silicon nitride film for the insulating layer, silicon oxide film) And a rotor were added and stirred for 3 hours. After completion of the stirring treatment, the substrate was removed, and the treatment liquid was left at room temperature overnight (about 16 hours). The appearance of the cleaning liquid after standing was visually observed and evaluated according to the following evaluation criteria. The results are shown in Tables 1-2.
(Liquid appearance)
○: Neither turbidity nor precipitation is observed compared with the cleaning solution before the test. X: Turbidity or precipitation is observed compared with the cleaning solution before the test.

<SiO ₂ etching rate>
A plasma TEOS film was produced as a SiO ₂ film by plasma CVD using TEOS (Si (OC ₂ H ₅ ) ₄ ) and oxygen gas. About each of the liquid before the washing test (before treatment) and the liquid after the washing test (after treatment), the optical interference type film thickness measuring device (Dainippon Screen Mfg. Co., Ltd., VM-1000) is used as a washing liquid at 24 ° C. The plasma TEOS film was immersed, the film thickness before and after the immersion was measured, and the etching rate was calculated from the immersion time and the amount of film thickness reduction. The results are shown in Tables 1-2.

From the results of Tables 1 and 2, in the treatment liquids of Comparative Examples 1 to 12 that do not contain the component (C-1) such as the component (c-1) and the component (c-2), the liquid appearance evaluation in the cleaning test is performed. It was x and the precipitation of the dissolved material could not be suppressed. On the other hand, in the treatment liquids of Examples 1 to 9 using the component (c-1) or the component (c-2), the liquid appearance evaluation in the washing test is all good, and the precipitation of the dissolved matter can be suppressed. confirmed.

1 Glass substrate 2 P-Si
3 SiN
4 SiO ₂
5 Contact hole 6 Etching residue 7 Si oxide film

Claims (7)

(A) hydrogen fluoride,
(B) hydrogen fluoride salt,
(C) A cleaning solution for a glass substrate containing an alkylene polyamine polycarboxylic acid having an odd sum of carboxyl groups and hydroxyl groups (however, the hydroxyl group may be 0), and (D) water. The component (A) contains 1 to 5% by weight, the component (B) is 10 to 50% by weight, the component (C) is 0.2 to 5% by weight, and the component (D) is 30 to 85% by weight. Item 5. A glass substrate cleaning liquid according to Item 1. The glass substrate cleaning liquid according to claim 1 or 2, wherein the hydrogen fluoride salt (B) is ammonium fluoride. The glass substrate cleaning solution according to any one of claims 1 to 3, wherein the component (C) is diethylenetriaminepentaacetic acid and / or 1,3-diamino-2-propanoltetraacetic acid. The glass substrate cleaning liquid according to any one of claims 1 to 4, wherein the glass substrate is a substrate having a silicon semiconductor, and the oxide film on the silicon surface is removed. The glass substrate cleaning liquid according to any one of claims 1 to 5, for removing an etching residue or a silicon oxide film generated by dry etching of a contact hole. (C) Cleaning liquid of the glass substrate in any one of Claims 1-6 which does not contain chelating agents other than a component substantially.

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