JPH05259066A - Positive photoresist removing liquid and manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To easily remove a side wall protection deposit film and to protect a conductive layer against corrosion by a method wherein positive type photoresist is removed with a water solution which contains a compound selected from aromatic cyclic phenols and aromatic cyclic carboxylic acid and organic amine. CONSTITUTION:A CVD oxide film 2 is formed on an Si substrate 1, and a TiW layer 3, a CVD-NW layer 4, and an Al-Si-Cu layer 5 are formed thereon, a positive type photoresist 6 is applied thereon and exposed to light for the formation of a resist mask. A water solution which contains aromatic cyclic phenol or preferably 2, 3-pyridine diol, aromatic cyclic carboxylic acid or preferably p-toluic acid, organic amine, and preferably tetramethyl ammonium hydroxide is used as positive photoresist, removing solution. The removing solution is excellent to remove a positive type photoresist, side wall protecting deposit film and high in after-corrosion preventing properties, so that it hardly corrodes wiring material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positive photoresist stripping solution that can be used in an etching process during the manufacture of semiconductor devices, and more specifically, to a positive photoresist that is formed during dry etching of wiring materials with chlorine-based gas. A positive photoresist remover used for removing the resist sidewall protection deposited film without corroding the wiring material, and the positive photoresist removes the positive photoresist from the conductive layer by the positive photoresist remover. The present invention relates to a method for manufacturing a semiconductor device, including the steps of:

[0002]

2. Description of the Related Art In an etching process in a semiconductor device manufacturing process, after forming a mask of a required photoresist, a conductive layer in a non-mask region is etched to form a wiring pattern, and then a photoresist on the wiring pattern is formed. A process of removing unnecessary resist layers including layers by a stripping solution is required. There are negative type photoresists and positive type photoresists,
2. Description of the Related Art In recent years, positive photoresists, which are advantageous for highly precise fine pattern formation due to high density of integrated circuits, have been mainly used.

Conventionally, as the etching technique, a chemical etching technique using a chemical agent has been widely used, but recently, a dry etching technique capable of finer etching with a higher density has become mainstream. Also,
Anisotropic dry etching using a chlorine-based gas is widely used for dry etching of the conductive layer.

In the dry etching of the conductive layer with chlorine-based gas using such a positive photoresist as a mask, the sidewall protection deposited film of the positive photoresist is utilized to enable anisotropic etching. There is a problem that it is less likely to be peeled off as compared with a normal positive photoresist. In addition, the chlorine radicals and ions taken into the side wall protective deposition film, when left in the air after completion of etching, generate acid due to moisture absorption and corrode the wiring material. This is usually called after-corrosion (Se
miconductor World 1991,1
1, p62-66) This after-corrosion is an Al-Si or Al- that has been widely used as a wiring material in recent years.
It is often observed in alloys such as Si-Cu.

Conventionally, as a typical method of preventing such after-corrosion, there is a method of repeating ultrapure water cleaning immediately after dry etching to wash away chlorine radicals and ions. However, with this method, it is difficult to completely remove chlorine ions and radicals from the sidewall protection deposited film. As a result, aftercorrosion often occurs due to residual chlorine radicals and ions.

Therefore, in order to completely prevent after-corrosion, it is indispensable to completely remove the side wall protective deposition film. Generally, an acidic stripping solution or an alkaline stripping solution is used for removing the side wall protective deposition film.
A stripping solution prepared by mixing a phenol compound, a chlorine-based solvent, and an aromatic hydrocarbon with alkylbenzene sulfonic acid is known as a typical acidic stripping solution.
It can be seen that removal of the sidewall protection deposited film requires considerable difficulty even if heated above 00 ° C. Further, since these acidic stripping solutions have low solubility in water, after the stripping operation, they must be rinsed with an organic solvent having good compatibility with water and rinsed with water, which also complicates the process. is there. on the other hand,
A stripping solution consisting of an organic amine and various organic solvents is known as a typical alkaline stripping solution, but this stripping solution also protects the side wall even when heated to 100 ° C. or higher as in the case of the above acidic stripping solution. Detachment of the deposited film requires considerable difficulty, and although these alkaline stripping solutions are water-soluble, they can be washed immediately after stripping, but the alkaline components corrode wiring materials. is there. As described above, the side wall protective deposition film cannot be completely stripped by any of the stripping solutions, so that after-corrosion is often observed due to residual chlorine radicals and ions.

In addition to these methods, there is known a method of removing the resist residue after plasma ashing with an alkaline aqueous solution containing tetramethylammonium hydroxide. In this method, a conductive layer composed of a substrate containing aluminum is formed. There was a problem of being severely corroded.

As described above, in order to prevent after-corrosion, there is a demand for a positive photoresist stripping solution that can easily strip the sidewall protective deposited film and does not corrode the conductive layer made of a substrate containing aluminum.

As a result of intensive studies conducted by the present inventors to improve the problems of the conventional stripping solutions for positive photoresist, the aromatic ring phenol compounds and aromatic ring carboxylic acid compounds are used. Side wall protection of a positive photoresist formed by dry etching with a chlorine-based gas, the stripper for a positive photoresist comprising an aqueous solution containing at least one compound selected from the group and an organic amine It has been found that they have extremely excellent properties, such as peeling property against deposited film, after-corrosion prevention property, non-corrosion property against wiring material, and workability. The present invention has been completed based on such findings.

[0010]

DISCLOSURE OF THE INVENTION The present invention provides a stripping solution for a positive photoresist comprising an aqueous solution containing an organic amine and at least one compound selected from the group consisting of an aromatic ring phenol compound and an aromatic ring carboxylic acid compound. It is provided. Further, the present invention provides a method for manufacturing a semiconductor device including a step of removing the positive photoresist described above using the above-mentioned stripping solution, and a semiconductor device manufactured by the method.

The stripping solution for positive photoresist according to the present invention is capable of stripping a sidewall protective deposited film of an organic amine aqueous solution and various non-corrosive properties of an aromatic ring phenol compound or an aromatic ring carboxylic acid compound for a wiring material. And is capable of manufacturing high-precision circuit wiring.

The present invention will be described in detail below. Examples of the aromatic cyclic phenol compound used in the present invention include phenol, o-cresol, m-cresol, p-cresol, resorcinol, 2,3-pyridinediol,
4,6-dihydroxypyrimidine, m-nitrophenol and the like can be mentioned. These may be used alone or in combination of two or more. In terms of preventing corrosion of the wiring material, 2,3-pyridinediol gives good results.

Examples of the aromatic cyclic carboxylic acid compound used in the present invention include benzoic acid, o-toluic acid, m-toluic acid and p-toluic acid. These may be used alone or in combination of two or more.

Examples of the organic amine used in the present invention include trimethyl-2-hydroxyethyl-ammonium hydroxide and tetramethylammonium hydroxide. These may be used alone or in combination of two or more. By containing a saccharide in the stripping solution of the present invention, the noncorrosiveness of the wiring material can be further improved. Examples of the saccharide include sorbitol, sucrose, starch and the like. This saccharide can be used alone or in combination of two or more kinds. Sorbitol, which contains less impurities, is an example of a preferred one.

A preferred method for preparing the stripping solution according to the present invention is 0.5% by weight or more and less than 60% by weight, preferably 2 to 50% by weight of an organic amine aqueous solution, and an aromatic ring phenol compound and an aromatic ring carboxylic acid. At least one compound selected from the group consisting of compounds is blended at an arbitrary ratio so that the pH of the liquid is 8 or more and less than 12, preferably 9.5 to 11
A stripping solution is prepared so that That is, an appropriate mixing ratio is determined by considering the concentration of the selected organic amine aqueous solution and its alkali strength, and the balance between the added amount of the selected aromatic cyclic phenol compound and aromatic cyclic carboxylic acid compound and its acid strength. .. If the pH of this liquid is less than 8, the peeling ability of the sidewall protection deposited film is lowered, and if the pH is 12 or more, the conductive layer containing Al is easily corroded. If the content of the organic amine is less than 0.5% by weight, the peeling ability of the sidewall protective deposited film is lowered, and if it is 60% by weight or more, problems such as high viscosity and coloring occur.

In addition, the amount of saccharides added for the purpose of improving the noncorrosiveness of the wiring material is 1% by weight.
It is preferably not less than 7% by weight, more preferably 4 to 5% by weight. 1% by weight
If the amount is less than the above, the effect of preventing corrosion of the conductive layer containing Al is not sufficiently exhibited, and if it is 7% by weight or more, the effect of preventing corrosion does not change any more and is meaningless.

Other components that can be incorporated into the stripping solution according to the present invention include known surfactants such as softanol (Japan) for reducing surface tension or preventing redeposition of resist on a substrate. Catalytic chemical industry), Unidyne (Daikin industry), Surflon (Asahi glass), as a corrosion inhibitor to further reduce the corrosion of the conductive layer containing Al, for example, aterite (Asahi Denka industry), ERI-300 ( Sanyo Kasei Kogyo) and sunhibitor (Sanyo Kasei Kogyo) can be added. Hereinafter, the present invention will be described in more detail with reference to Examples of the present invention together with Comparative Examples.

[0018]

【Example】

Example 1 100 g of 2.38 wt% tetramethylammonium hydroxide aqueous solution containing 3 g of 2,3-pyridinediol
It was dissolved in g to prepare a stripping solution having a pH of 10.40. Example 2 1.5 g of 2,3-pyridinediol and 1.75 g of m-toluic acid were dissolved in 100 g of a 2.38 wt% tetramethylammonium hydroxide aqueous solution to give a pH of 1.
A stripping solution of 0.50 was prepared. Example 3 3.5 g of m-toluic acid was dissolved in 100 g of a 2.38 wt% tetramethylammonium hydroxide aqueous solution to prepare a stripping solution having a pH of 10.37. Example 4 3.4 g of m-toluic acid was dissolved in 100 g of a 2.38 wt% tetramethylammonium hydroxide aqueous solution to prepare a stripping solution having a pH of 9.47. Example 5 7.5 g of m-toluic acid was dissolved in 100 g of a 5.09 wt% tetramethylammonium hydroxide aqueous solution to prepare a stripping solution having a pH of 10.47.

Example 6 3.5 g of o-toluic acid and 7.1 g of sorbitol were dissolved in 100 g of a 2.38 wt% tetramethylammonium hydroxide aqueous solution to prepare a stripping solution having a pH of 10.50. Example 7 2.38 g of 3.5 g of o-toluic acid and 7.1 g of sucrose
A stripping solution having a pH of 10.4 was prepared by dissolving it in a wt% tetramethylammonium hydroxide aqueous solution. Example 8 6.2 g of o-toluic acid and 7.1 g of sorbitol were dissolved in 100 g of a 4.87 wt% trimethyl-2-hydroxyethylammonium hydroxide aqueous solution to prepare a stripping solution having a pH of 10.49.

The stripping solution prepared in each of these examples was used to strip the side wall protective deposited film of the positive photoresist as described above, and the stripped state of the side wall protective deposited film and the corrosiveness of the wiring material. And the occurrence situation of after-corrosion was evaluated. In the evaluation test, the following two types of substrates were used, and a film thickness meter, an optical microscope and a scanning electron microscope (SEM) were used.

Substrate Preparation Example 1 A CVD oxide film (film thickness: 450) which is an insulating film is formed on a Si substrate.
0 Å) is formed on the first layer metal film TiW layer (film thickness: 600 Å), second layer metal film CVD-W layer (film thickness: 5000 Å), third layer metal film Al. -Si
-Cu layer (film thickness: 8000Å-Si content: 1% by weight,
Cu content: 0.5% by weight) was formed in order. Then Al
A positive photoresist was applied (coated) on the —Si—Cu layer, exposed and developed to form a resist mask. This positive photoresist is mainly composed of a novolac resin and has a film thickness of 18000Å. Then, after post-baking at 140 ° C. for 30 minutes, the conductive layer not covered with the resist mask (non-mask area)
Was removed by dry etching using a chlorine-based gas. Subsequently, after passing through an ashing step, the resist other than the sidewall protective deposition film was removed and ultrapure water cleaning was performed.

FIG. 1 schematically shows the structure of the semiconductor immediately after the conductive layer is formed. In this figure, a CVD oxide film (2) which is an insulating film is formed on a Si substrate (1), and a TiW layer (3) which is a first-layer metal film and a CVD film which is a second-layer metal film are formed thereon. -W layer (4), Al that is the third layer metal film-
The Si-Cu layer (5) is sequentially formed. In this example, the CVD oxide film (2) has a film thickness of 4500Å, the first layer metal film (3) has a film thickness of 600Å, and the second layer metal film (4) has a film thickness of 5000.
Å, the third layer metal film (5) is 8000 Å. Also, A
In the 1-Si-Cu layer (5), the Si content is 1
A material having a wt% and a Cu content of 0.5 wt% was used.

In FIG. 2, a third layer metal film, Al-Si-, is used.
It is shown that a positive photoresist (6) is applied (coated) on the Cu layer (5) and exposed to form a resist mask. In this example, the positive photoresist (6) is mainly composed of novolac resin,
The film thickness is 18000Å. After forming a resist mask, baking was performed at 140 ° C. for 30 minutes.

FIG. 3 shows a state immediately after the conductive layer is etched and the region not covered with the mask (non-masked region) is removed by dry etching using a chlorine-based gas. In this figure, the side wall protective deposition film (7) is formed on the surface of the conductive layer.

FIG. 4 shows the structure after removing most of the resist that has been the mask by ashing. A sidewall protective deposition film (7) is present on the surface of the patterned conductive layer.

FIG. 5 shows a state after cleaning with ultrapure water for preventing after-corrosion. This figure shows that the side wall protective deposition film (7) falls on the surface of the conductive layer and is difficult to peel off.

Substrate preparation example 2 A CVD oxide film (film thickness: 450) which is an insulating film is formed on a Si substrate.
0 Å) on which a TiW layer (film thickness: 4000 Å) which is the first layer metal film and an Al-Si which is the second layer metal film are formed.
Layers (film thickness: 7200Å · Si content: 1% by weight) were sequentially formed. Next, a positive photoresist was applied (coated) on the Al-Si layer, exposed and developed to form a resist mask. This positive photoresist is mainly composed of novolac resin and has a film thickness of 18000Å
Is. Then, after post-baking was performed at 140 ° C. for 30 minutes, the conductive layer (non-mask region) not covered with the resist mask was removed by dry etching using a chlorine-based gas. Subsequently, after passing through an ashing process, the resist other than the sidewall protective deposition film was removed and ultrapure water cleaning was performed.

Experimental Example 1 The substrate prepared in Example 1 of the substrate was immersed in 100 g of the stripping solution prepared in Example 1 at 23 ° C. for 1 minute and then washed with water to remove the side wall protective deposited film and corrosiveness of the wiring material. Was evaluated. The sidewall protective deposited film was peeled off, and no corrosion of the patterned conductive layer surface was observed. Figure 6
Shows schematically the state of the substrate prepared in Example 1 of substrate preparation, and FIG. 7 shows the state after treatment with the stripping solution prepared in Example 1.

Experimental Example 2 The substrate prepared in Example 1 of the substrate was immersed in 100 g of the stripping solution prepared in Example 3 at 23 ° C. for 1 minute and then washed with water to remove the side wall protective deposited film and corrode the wiring material. The sex was evaluated. The sidewall protective deposited film was peeled off, and no corrosion of the patterned conductive layer surface was observed.

Experimental Example 3 The substrate prepared in Example 2 of the substrate was immersed in 100 g of the stripping solution prepared in Example 3 at 23 ° C. for 1 minute and then washed with water to remove the side wall protective deposited film and corrode the wiring material. The sex was evaluated. The sidewall protective deposited film was peeled off, and no corrosion of the patterned conductive layer surface was observed.

Experimental Example 4 The substrate prepared in Example 1 of the substrate was immersed in 100 g of the stripping solution prepared in Example 5 at 23 ° C. for 1 minute and then washed with water to remove the side wall protective deposited film and corrode the wiring material. Was evaluated. The sidewall protective deposited film was peeled off, and no corrosion of the patterned conductive layer surface was observed.

When each of the substrates processed in Experimental Examples 1 to 4 was allowed to stand in a high humidity atmosphere at 23 ° C. for 17 hours, no occurrence of after-corrosion was observed in any of them.

Comparative Example 1 The substrate prepared in Example 1 of substrate preparation was immersed in 100 g of a commercially available acidic stripping solution at 110 ° C. for 10 minutes, washed with isopropyl alcohol, and then washed with water to remove the side wall protective deposited film and the wiring material. The corrosiveness was evaluated. The sidewall protection deposited film was not peeled off.

Comparative Example 2 The substrate prepared in Example 1 for preparing a substrate was immersed in 100 g of a commercially available alkaline stripping solution at 100 ° C. for 5 minutes and then washed with water.
The peeling state of the sidewall protection deposited film and the corrosiveness of the wiring material were evaluated. The sidewall protection deposited film was not peeled off.

Comparative Example 3 The substrate prepared in Example 1 of the substrate was immersed in 100 g of a 2.38% by weight aqueous solution of tetramethylammonium hydroxide at 23 ° C. for 1 minute and then washed with water to remove the sidewall protective deposited film. And the corrosiveness of the wiring material was evaluated. The sidewall protection deposited film was peeled off, but the conductive layer was about 200
0Å Corroded.

As can be seen from the above results, the stripping solution for a positive photoresist according to the present invention has a releasability of the positive photoresist formed at the time of dry etching with a chlorine-based gas from the sidewall protection deposited film. It has excellent properties such as excellent anti-corrosion property and non-corrosion property for wiring material. Moreover, the stripping solution of the present invention is nonflammable, and to the human body and environment,
It has excellent advantages such as no adverse effects.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a cross section of a semiconductor device after film formation.

FIG. 2 is an explanatory view showing a cross section of a semiconductor device after lithography.

FIG. 3 is an explanatory diagram showing a cross section of a semiconductor device after dry etching.

FIG. 4 is an explanatory view showing a cross section of the semiconductor device after ashing.

FIG. 5 is an explanatory view showing a cross section of a semiconductor device after a water washing treatment for rust prevention.

FIG. 6 is an explanatory diagram showing a cross section of the semiconductor device created in substrate creation example 1;

FIG. 7 is an explanatory view showing a cross section of a semiconductor device after being treated with a chemical according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Si substrate 2 CVD oxide film 3 1st layer metal film 4 2nd layer metal film 5 3rd layer metal film 6 Positive photoresist 7 Side wall protection deposition film

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical indication 7735-4M H01L 21/88 D (72) Inventor Tsuyoshi Matsui 2355 Kihara, Miura-mura, Inashiki-gun, Ibaraki Japan Texa In Su Instruments Co., Ltd. (72) Inventor Masao Miyazaki 1-7-1 Inari, Soka-shi, Saitama Kanto Chemical Co., Ltd. Central Research Laboratory (72) Inventor Kiyoto Mori 1-7-1 Inari, Soka-shi, Saitama Kanto Central Research Institute of Chemical Co., Ltd.

Claims (9)

[Claims] 1. A stripping solution for a positive photoresist, comprising an aqueous solution containing at least one compound selected from the group consisting of an aromatic ring phenol compound and an aromatic ring carboxylic acid compound and an organic amine. . 2. The stripping solution for a positive photoresist according to claim 1, wherein the aromatic cyclic phenol compound is a compound selected from the group consisting of phenol, cresol, resorcinol and 2,3-pyridinediol. 3. The positive photoresist stripper according to claim 1, wherein the aromatic cyclic carboxylic acid compound is a compound selected from the group consisting of benzoic acid, o-toluic acid, m-toluic acid and p-toluic acid. liquid. 4. The stripping solution for positive photoresist according to claim 1, wherein the organic amine is a compound selected from the group consisting of trimethyl-2-hydroxyethylammonium hydroxide and tetramethylammonium hydroxide. 5. The stripping solution for positive photoresist according to claim 1, which further contains a saccharide. 6. The stripping solution for a positive photoresist according to claim 1, wherein the sugar is selected from the group consisting of sorbitol, sucrose and starch. 7. The content of the organic amine is 0.5% by weight.
The stripping liquid for positive photoresist according to claim 1, which has a pH of 8 to less than 12 and a pH of 8 to 12 inclusive. 8. A step of forming a conductive layer made of a substrate containing at least aluminum in a predetermined region on a semiconductor substrate, and forming a required mask on the conductive layer using a positive photoresist to form a non-mask region. A step of dry etching the conductive layer, a step of removing the positive photoresist on which the mask is formed by ashing, and a stripping solution for a positive photoresist according to any one of claims 1 to 7. And a step of peeling the side wall protective deposition film of the positive type photoresist formed at the time of dry etching from the conductive layer. 9. A semiconductor device manufactured by the manufacturing method according to claim 8.