JPS58127328A - Etching method for insulating protection film of semiconductor substrate - Google Patents

Abstract

PURPOSE:To remove stains from an insulating protection film and to improve the shape of a stage, by making a window in the film by a dry-etching processing, and then subjecting the same to immersion processing with an HF water solution. CONSTITUTION:The result of analysis of a semiconductor substrate just after a window is opened in an insulating protection film by a dry-etching processing is indicated by a broken line 1, while the result of analysis of the surface of the semiconductor substrate which is subjected to an immersion processing for a short time thereafter with an HF water solution is indicated by a broken line 2. The comparison between these broken lines 1 and 2 shows that C, F, Mg, Na, K, etc. are reduced more in the substrate subjected to the additional immersion processing than in the substrate not subjected thereto, and that the additional immersion processing with the HF water solution is effective for removing stains on the surface. In practice the substrate subjected to the immersion processing with the HF water solution is excellent in the bonding property with an Al film or an Al alloy film, the corners of a staged part are chamfered, and the coating property of the Al film or the Al alloy film is also excellent.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention processes an 81 oxide film on a semiconductor substrate by a dry etching process M1. Concerning the method of etching by.

General KP (I) is used as an insulating protective film for semiconductor integrated circuits.
J) Diffused S (oxidized 11 (P2O film)) is used. After opening the K window in this insulating II film (PEIG film), a 5! film or a MU! alloy film is used as an electrode or wiring material. It is vapor-deposited and interconnects between each element under the insulation insulation film.Here, the bonding between the Muj film or the Aj alloy film and each element where the window is opened is good (low electrical resistance). ) is important.Also, when opening the ai oxide film,
There is a step, but even at this step there is a muj membrane or mu! It is important that the alloy film has good coverage and does not break.

By the way, opening a window in this insulating protective film (P2O film) is as follows:
Since very fine processing (2 to 4 .mu.m) is required, a dry etching method using CX'In (7 Leon) type gas plasma is used. Dry etching processing not only enables microfabrication, but compared to conventional etching processing that uses a water bath solution (for example, aqueous hexachloric acid solution), dry etching processing does not require waste fluid, is non-polluting, and can be automated. It has the following advantages.

However, when the opening of the insulating protective film is subjected to dry etching, components of the reactive gas or reaction products adhere to the semiconductor substrate and are diffused in a shallow manner. This phenomenon can be clarified by performing engineering M5 analysis or the like to identify the components or reaction products that have adhered or diffused.

An example of the analysis results is shown in Figure 1. It has been revealed that if these deposits or reaction products remain on the semiconductor substrate, the bonding properties between the substrate and the MJW# where the window is opened will be compromised (the electrical resistance will be high).

Also, the cross-sectional shape of the window opened by dry etching is at an angle of 80 to 90 degrees, as shown in Figure 2, and is very courier, so it is 1 mm! Alternatively, the coverage of the Mj alloy film is poor, and there is a high risk of wire breakage at the stepped portion. Photoresist 1
is a covering material for patterning the 81 oxide film 2.

In order to eliminate these drawbacks, one insulating film (PaGI[)
After the t-dry etching treatment, it is very effective to immerse the material in an aqueous H4F (heptonic acid) solution for a short time.

It was confirmed that gas components or reaction products adhering to the semiconductor substrate were completely removed by the immersion treatment in the 111 aqueous solution.

In addition, B (the corner of the step part of the oxide film opening part is chamfered,
Muj or mu! It was also confirmed that the coverage of the alloy film was improved. The present invention thus provides an insulating protective film (PEG).
After opening the window by dry etching the film), HIF
This is a method of etching an insulating protective film of a semiconductor substrate, which is characterized by immersion treatment in an HF aqueous solution.

Next, the present invention will be explained in detail. Figure 3 shows an insulating protective film (
An example of an analysis result of a semiconductor substrate immediately after dry etching (pse film) to open a window is shown as a broken line 1, and an example of an analysis result of a semiconductor substrate that has been subsequently immersed in a HIFHF aqueous solution for a short time is shown as a broken line 2. Shown. In Fig. 3, as shown in the circle, analysis result example 2 with addition of immersion treatment with HF aqueous solution has a lower C (carbon) t' (fluorine) t Mrt than analysis result example 1 without immersion treatment.
(Magnesium) 9Ma (sodium), K (potassium), etc. are reduced, and it can be understood that adding HF aqueous solution immersion treatment is very effective in removing surface contamination. In fact, products subjected to such VcHIF aqueous solution immersion treatment have good bonding properties with MujH1h or Muj alloy films (
It was confirmed that the electrical resistance was low.

In addition, Fig. 4 (1) shows the cross-sectional shape of the window opening after HIF water bath treatment.The corners of the stepped portions are chamfered to improve the coverage of the muj membrane or the muj alloy. It can be understood.

As explained above, the present invention effectively removes contamination and improves the shape of steps on a semiconductor substrate by immersing Pf3Gm used as an insulating film in a semiconductor integrated circuit in an HF aqueous solution. It's easy to do.

Although the embodiment has been described using a Psa film in which phosphorus is diffused as the insulating protective film, it goes without saying that the present invention can also be applied to an S(oxide) film containing an element other than phosphorus, or a simple 8(oxide) film.

[Brief explanation of the drawing]

FIG. 1 shows an example of the surface analysis results immediately after dry etching the insulation protection Jll (P2O film) to open a window, and FIG. 2 shows the cross-sectional shape of the window at that time. Third
The figure shows an example of surface analysis results comparing cases where HF aqueous solution immersion treatment was performed after dry etching and cases where HF aqueous solution immersion treatment was not performed. FIG. 4 shows the cross-sectional shape when immersed in an HF aqueous solution. In FIG. 2, a semiconductor substrate is shown. Applicant Suwa Seikosha Co., Ltd. Agent Patent Volume Volume 1 Figure 1 Figure 2

Claims (1)

[Claims] 111 Step of forming an S<oxide film as a protective film (2)
1 above S (coating process of photoresist covering the oxide film and fogging process 131 process of etching the above-mentioned conductor substrate with plasma gas). After the third process, HP (hetamine acid) A method for etching an insulating protective film of a semiconductor substrate, the method comprising immersing a semiconductor substrate in a water bath.