JPH02244628A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To enable the etching process to be performed during the wetetching process of the next lower layer by a method wherein, after making a hole in the thin film on an upper layer by reactive dryetching process, the resist surface is irradiated with oxygen plasma. CONSTITUTION:A photoresist film 6 is patterned so as to make a hole in a double structured protective film formed on a PSG film 4 as a lower layer and an Si nitride film 5 as an upper layer covering an Al bonding pad 3 formed on an Si oxide film 2 on an Si substrate 1. Next, a hole is made in the film 5 by reactive ion etching process using the film 6 as a mask. Next, the surface of the substrate 1 is irradiated with oxygen plasma (a) meeting the requirements of 100-500W for 1-5 minutes. Later, a hole is made in the film 4 by wetetching process. Through these procedures, the even etching process can be performed avoiding the sticking of bubbles during the wetetching process.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of opening holes in a thin film when manufacturing a semiconductor device.

(Prior art) In recent years, as the miniaturization of semiconductor devices has progressed, the reliability has increased.
Therefore, a thin film having a two-layer structure is often used as a protective film on the semiconductor surface.

Figure 2 shows the bonding pad part J- of a conventional semiconductor device.
FIG. 3 is a cross-sectional view showing the step of opening holes in the protective film.

In FIG. 2, 1 is a silicon substrate, 2 is a silicon oxide film, 3 is an amyl bonding pad, 4 is a phosphosilicate glass (hereinafter referred to as PSG) film, 5 is a silicon nitride film, and 6 is a photoresist film.

Next, we will explain the opening of the protective film.
The photoresist film 6 is patterned to open holes in the 2M structure protective film whose layer is formed from the silicon nitride film 5 (FIG. 2(a)). Next, using this photoresist film 6 as a mask, a 1-layer silicon nitride film is opened by reactive ion etching using CF and gas (see Fig. 2).
b)) Next, holes are opened in the lower PSG film 4 by wet etching using a hydrofluoric acid etching solution (see Fig. 2).
c)) Then, the photoresist film 6 is removed. In the second step described above, holes were formed in the two-layered protective film.

(Problems to be Solved by the Invention) However, in the conventional hole-opening method described in 1-1, when opening the first-layer silicon nitride film, the resist surface is altered by reactive ion etching, and the next lower layer P S When wet etching the G film, air bubbles tend to adhere to the areas where holes should be opened, making it difficult to uniformly etch the PSG film, and in some cases, the PSG film may remain due to insufficient etching. There was also a problem that caused wire bond failure.

The present invention solves the problems of the conventional art as described in 1.
It is an object of the present invention to provide a method for manufacturing a semiconductor device that enables uniform openings in a thin film having a layered structure.

(Means for Solving the Problems) In order to achieve the L multilayer structure of the present invention, a method for manufacturing a semiconductor device includes opening holes in a two-layer thin film formed on a conductive substrate E using a photoresist as a mask. In this case, after opening the upper thin film by reactive ion etching and before wet etching the lower layer, a step of irradiating the surface of the resist mask with oxygen plasma is carried out.

(Function) Therefore, according to the present invention, the surface layer of the photoresist film that has changed in quality during the reactive dry etching of the upper thin film is removed by irradiation with oxygen plasma, so that when the next wet etching of the lower layer is performed, the surface layer of the photoresist film is removed. Uniform etching is possible without the adhesion of air bubbles.

(Embodiment) FIG. 1 is a cross-sectional view showing the step of opening a protective film of a bonding pad l- of a semiconductor device in an embodiment of the present invention. In FIG. 1, 1 is a silicon substrate, 2 is a silicon oxide film, 3 is an amyl bonding pad, 4 is a PSO film, 5 is a silicon nitride film, and 6 is a photoresist film.

Next, the step of opening holes in the protective film will be explained. First, the lower layer covering the aluminum bonding pad 3 formed on the silicon oxide film 2-1 of the silicon substrate 1 is the PSG film 4-1.
The photoresist film 6 is patterned to open holes in the two-layer protective film whose upper layer is made of silicon nitride [5] (FIG. 1(a)).

Next, using this photoresist film 6 as a mask, the upper silicon nitride film 5 is opened by reactive ion etching using CF4 gas (FIG. 1(b)).
The surface of the semiconductor substrate is irradiated with oxygen plasma at 50 W for 5 minutes (FIG. 1(C)). After that, the lower PSG film 4 is etched by wet etching using a hydrofluoric acid etching solution.
A hole is drilled (Fig. 2(d)). Finally, photoresist
Remove 1I6. Through the steps described above, the openings in the two-layered protective film are completed.

Note that the oxygen plasma irradiation was performed at 100 to 500 W;
Do this for 1 to 5 minutes.

(Effects of the Invention) As is clear from the above embodiments, the present invention is capable of forming pores in a two-layer thin film by reactive dry etching, and then irradiating oxygen plasma onto the resist mask surface to remove the altered resist film. Since the surface layer is removed, when the next lower layer wet etching is performed, bubbles do not adhere and uniform etching is possible, and wire pound defects that occur due to insufficient lower layer etching can be eliminated. have

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the process of opening a protective film on a bonding pad 1- of a semiconductor device according to an embodiment of the present invention, and FIG. It is a sectional view showing a process. 1...Silicon substrate, 2...Silicon oxide film,
3...Amilponding pad. 4... PSG film, 5... Silicon nitride film. 6... Photoresist film. Patent applicant Matsushita Electronics Co., Ltd.

Claims (1)

[Claims] When opening holes in a two-layer thin film formed on a semiconductor substrate using a photoresist as a mask, a hole opening process is performed using reactive ion etching, and then oxygen plasma is irradiated on the resist surface at 100 to 500 W for 1 to 5 minutes. 1. A method for manufacturing a semiconductor device, comprising a step of forming a hole by wet etching.