JP2804543B2 - Method for manufacturing semiconductor device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a semiconductor device in which the adhesion of a positive resist to an interlayer insulating film is improved to improve the quality of products.

(Prior Art) FIG. 2 is a manufacturing process diagram of a 1-Mbit DRAM semiconductor element using boro-phosphosilicate glass (hereinafter referred to as BPSG) as a conventional interlayer insulating film.

First, a lower pattern 22 is formed on a silicon wafer 21 by a conventional method.
To form Next, a BPSG film 23 as an interlayer insulating film is subjected to normal pressure CVD.
8000 ° C is generated by the apparatus, and an annealing treatment (BPSG flow) is performed in a diffusion furnace at 950 ° C. in an N ₂ atmosphere for crystallizing the formed film (FIG. 2a). A contact window for electrical connection between the lower pattern 22 of the BPSG film 23 and the upper pattern (not shown) is formed by the following photolithography process.

As shown in FIG. 2 (b), a positive resist 24 is coated at 12000.degree., Mask alignment and exposure are performed by a stepper, and a tetramethylene ammonium hydroxide (TMAH) -based developer, specifically, a trade name NSD-TD (Tokyo, Japan) Resist pattern 24a by wet development (2nd
Figures b, c, d). In the drawing, reference numeral 25 denotes a mask, and 26 denotes ultraviolet rays.

Using the obtained resist pattern 24a as a mask, a wet-etched portion (usually 4000 ° etching) indicated by reference numeral 27 using an HF-based etchant and a dry-etched portion 28 using a RIE dry etcher are formed by a conventional method, and the resist is removed. Contact window 29 on BPSG film 23
Are opened (FIGS. 2, e, f, g).

(Problems to be Solved by the Invention) However, in the method described above, the adhesion between the interlayer insulating film of the BPSG film and the positive resist applied thereon is not sufficient, and as a result, during the subsequent processing, In the wet development in the photolithography process, the developer penetrates between the BPSG film and the positive resist and causes peeling of the resist. As a result, there is a problem that side etching occurs in the contact window at the time of wet etching, and an opening larger than necessary is obtained.

An object of the present invention is to prevent the peeling of the resist at the time of the wet development and the unnecessary side etching of the contact window at the time of the wet etching, which are caused by insufficient adhesion between the interlayer insulating film and the positive resist. With the goal.

(Means for Solving the Problems) The present invention relates to a method of manufacturing a semiconductor device using a BPSG, phosphosilicate glass (hereinafter, PSG), or borosilicate glass (hereinafter, BSG) film as an interlayer insulating film. Prior to the formation of a positive resist, a processing step such as washing with hot acid hydrogen peroxide or hot sulfuric acid is introduced, and then photolithography and etching for forming a contact window pattern are performed.

(Operation) In the present invention, the above-mentioned BPSG, PSG, BSG interlayer insulating film is subjected to a treatment with hot sulfuric acid or the like prior to the formation of a positive resist, so that the glass surface characteristics of the surface of the interlayer insulating film have some characteristics. It is thought that this causes a change, which contributes to the improvement of the adhesion to the positive resist.

(Embodiment) An embodiment of the present invention will be described with reference to FIG. As described in the above conventional example, first for the generation of the BPSG film,
Using a normal pressure CVD apparatus, a BPSG film 3 was formed at a temperature of 400 ° C. in an O ₂ atmosphere SiH ₄ and B ₂ H ₆ gas on a silicon wafer 1 on which a lower pattern 2 was formed in advance at 8000 °. Thereafter, in order to crystallize the BPSG film 3, annealing (BPSG flow) was performed in a diffusion furnace at 950 ° C. for 15 minutes under N ₂ gas conditions (FIG. 1a). BP
After the SG flow, the silicon wafer 1 supported by the wafer carrier 12 is immersed for 5 minutes in the processing tank 9 containing the H ₂ SO ₄ / H ₂ O ₂ liquid 10 heated to 125 ° C. by the heater 11. (Fig. 1b). Next, the silicon wafer 1 was lifted out of the processing tank 9 and thoroughly rinsed with pure water 14 in a pure water tank 13 and dried (FIG. 1c). With respect to the dried silicon wafer 1, a contact window was formed in the same manner as described above. That is, as shown in FIG.
A positive resist 4 was applied on the SG film 3 at 12000 °. Next, using a stepper exposure machine, the positive resist 4 was irradiated with ultraviolet rays 6 of 435 nm through the glass mask 5, the portions of the positive resist 4 irradiated with the ultraviolet rays 6 were exposed, and a resist pattern 4a was formed with a wet developing solution. (FIG. 1f).

Using the obtained resist pattern 4a as a mask, etching is performed with a hydrofluoric acid 5% + ammonium fluoride 95% etching solution by a conventional method, a wet etching portion (4000 °) indicated by reference numeral 7, and CHF ₃ / O ₂ by a RIE dry etcher.
A dry etching portion 8 was formed by etching with gas, the resist was removed, and a contact window 9 was opened in the BPSG film 3 (FIGS. 1 g, h, and i).

The properties of the thus obtained example products are shown in the table below. Note that the comparative examples in the table are those in which the above-mentioned hot sulfuric acid-hydrogen peroxide treatment is not performed.

According to the above table, it is clear that the resist drastically decreases during the development and the side etch amount is remarkably reduced in the examples.

In the present invention, in the above-described interlayer insulating film processing,
The temperature of hot sulfuric acid and hot sulfuric acid-hydrogen peroxide is approximately 70
A sufficient effect was observed at 10 ° C for 10 minutes. Of course, it is preferable to raise the temperature in order to shorten the processing time.

The upper limit of the temperature is not particularly limited in the case of sulfuric acid, but in the case of mixed hydrogen peroxide, the temperature is preferably 150 ° C. or lower in consideration of its boiling point (150 ° C.) to avoid evaporation.

 The mixing ratio of hydrogen peroxide is preferably about 1/25 by volume.

Next, the improvement of the adhesion to the interlayer insulating film was effective for almost all currently used resists. Specific examples include ONPR-800, TSMR-8800 (trade names, manufactured by Tokyo Ohka Kogyo) and MP-1400 (manufactured by Shipley).

(Effects of the Invention) As described in detail above, according to the present invention, after the flow of forming BPSG, PSG, and BSG on the lower pattern, heat H ₂ SO ₄ or H
_Since a treatment step such as ₄ SO ₄ / H ₂ O ₂ cleaning is introduced, the adhesion between the interlayer insulating film and the positive resist becomes extremely strong. As a result, the resist peeling during wet development with photolithography, the resist peeling during wet etching, and the amount of side etching can be reduced, so that the above-mentioned problems can be solved and the quality can be stabilized and the yield can be improved.

[Brief description of the drawings]

FIG. 1 is a process diagram of an embodiment of the present invention, and FIG. 2 is a process diagram of a conventional method. 1 ... silicon wafer, 2 ... lower pattern, 3 ... BP
SG film, 4 ... Positive resist, 5 ... Mask, 6 ... Ultraviolet, 7 ... Wet etch, 8 ... Dry etch,
9: treatment tank, 10: H ₂ SO ₄ / H ₂ O ₂ , 11: heater
14 ... Pure water.

Claims (1)

(57) [Claims] 1. A method of manufacturing a semiconductor device using boro-phosphosilicate glass, phosphosilicate glass, or borosilicate glass as an interlayer insulating film of an element, wherein the surface of the interlayer insulating film is formed after the interlayer insulating film is formed and before a positive resist is applied. Treating the product with hot sulfuric acid or hot sulfuric acid-hydrogen peroxide.