JPS59228721A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To easily separate a mask from a photo-resist film by a method wherein the photo-resist film and a mask are brought into a close contact with each other through a sticking prevention film, the photo-resist film is then exposed, and the developing treatment is effected after removing the sticking prevention film. CONSTITUTION:An oxide film 2 is formed on the surface of a wafer 1, on which film 2 a photo-resist film 3 is formed. A sticking prevention film 8 consisting of, for example, Freon resin is formed on the film 3 and a mask 4 is superposed thereon. Thereafter, an exposure to a square ultraviolet radiation 7 is effected on the film 3 by means of an irradiation from above the mask 4. The mask 4 is then separated from the semiconductor wafer. At this time, the sticking prevention film has been formed on the film 3, both of which can be therefore easily separated by a small force. Subsequently, the film 3 is removed in the manner of dissolution and is subjected to a development treatment. Furtheremore, the oxide film 2, which is exposed from a window 3a, is removed by etching, thereby forming a window 2a. Then, the wafer 1 is selectively etched.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a method for manufacturing a semiconductor device, and more particularly to an improvement in a photolithography process using a contact method using a photoresist film.

BACKGROUND ART One of the important processes in manufacturing semiconductor devices is a photolithography process. For example, selective diffusion of impurities,
Mesa etching on semiconductor wafers.

Selective etching of an insulating film such as an oxide film is necessary as a pre-process for vapor deposition of ohmic metal, and selective etching of ohmic metal is necessary for power supply patterning after vapor deposition of ohmic metal. be. The photolithography process described above is carried out for selective etching.

Figures 1 to 5 show force i-plane diagrams of each stage of etching on a semiconductor wafer to explain the selective diffusion of impurities and the selective etching process of the oxide film, which is a pre-process of mesa etching of the semiconductor wafer. .

Hereinafter, the process will be explained step by step. First, a semiconductor wafer of one conductivity type made of silicon is used, and an oxide film 2 is formed on its surface (FIG. 1). Subsequently, a photoresist film 3 is formed on the e-oxide film 2. Note that the photoresist film 3 undergoes a photochemical reaction when irradiated with ultraviolet rays,
Becomes insoluble in solvents. When irradiated with ultraviolet rays, a so-called negative-type material undergoes a photochemical reaction and becomes soluble in solvents. There is a so-called positive type, but below we will explain it as a negative type (Fig. 2). Next, a mask 4 is brought into close contact with the photoresist film 3. In this mask 4, a mask pattern 6 made of an opaque material such as chromium or chromium oxide is formed on the lower surface of a transparent glass substrate 5, and the mask pattern 6 is brought into close contact with the photoresist film 3. In this state, parallel ultraviolet rays 7 are irradiated from above the mask 4 to expose the photoresist film 3. Due to this exposure, the portion of the photoresist film 3 directly under the mask pattern 6 is not altered due to a photochemical reaction, but the photoresist film 3 other than the portion directly under the mask pattern 6 undergoes a photochemical reaction and is resistant to the solvent. Becomes insoluble. In order to visually show this alteration, the entire village is shown in many dots (Figure 3).

Next, when the mask 4 is removed and the whole is immersed in a solvent or the solvent is sprayed onto the photoresist film 3 and developed, only the portion of the photoresist film 3 directly under the mask pattern 6 is dissolved and removed. Window holes 3a are formed in the photoresist film 3 in a pattern 1ii': opposite to the mask pattern 6 (FIG. 4). Subsequently, when the whole is immersed in an etching solution or exposed to plasma, only the oxide film 2 exposed from the window hole 3a is etched away, and a window hole 2a having the same pattern as the scattering hole 3a is formed. (Figure 5 1).

After this, the remaining photoresist film 3 is removed,
When heated in a gas containing high temperature impurities, impurities can be selectively diffused, and when immersed in etching solution or exposed to etching plasma, the semiconductor wafer 1 is selectively etched to form mesa grooves. be done.

By the way, in the method of exposing the photoresist film 3 with the mask 4 in close contact with it, the photoresist film 3
In order to improve the adhesion between the photoresist film 3 and the mask 4, the atmosphere is made vacuum and both are suppressed.
The photoresist film 3 and the mask 4 are in a fairly strong adhesive state, and it is easy to separate the photoresist film 3 and the mask 4 after exposure unless a considerable force is applied to the two.
@So-called sticking occurred. Also,
If you force a pair of tweezers between the two to forcefully separate them, the photoresist film 3 and mask 4 will be damaged, and if you forcefully separate them, the photoresist film 3 will be transferred to the mask 4. That also happened.

DISCLOSURE OF THE INVENTION Therefore, an object of the present invention is to provide a manufacturing method that allows a photoresist film and a mask to be easily separated with a small force after completion of exposure using a contact exposure method.

In summary, this invention involves forming an anti-sticking film on the surface of a photoresist film, exposing the photoresist film and a mask in close contact with each other through the anti-sticking film, and immediately or removing the anti-sticking film. It is characterized in that it is then subjected to development processing.

In other words, if an anti-sticking film is formed on the surface of the photoresist film, even when exposed with a mask closely attached,
Since the photoresist film and the mask do not become adhesive, they can be easily separated with a small force after exposure.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

6 to 12 show cross-sectional views of semiconductor wafers at various stages for explaining the manufacturing method according to the present invention.

First, a semiconductor wafer l is prepared, and an oxide film 2 is placed on its surface.
(Figure 6). Subsequently, a photoresist film 3 is formed on the oxide film 2 (FIG. 7).

The above steps are similar to those in the conventional FIGS. 1 and 2.

Next, the anti-sticking film 8 is entirely formed on the photoresist@3. This anti-sticking film 8 may be formed of, for example, a fluorocarbon resin or the like to a thickness of about 10,000× (FIG. 8). Subsequently, a mask 4 is superimposed on the anti-sticking film 8, and parallel ultraviolet rays 7 are irradiated from above the mask 4 to expose the photoresist film 3. Even with this exposure stinking prevention film 8, there is no problem at all (FIG. 9). Next, the mask 4 and the semiconductor wafer are separated. At this time, since the anti-sticking film 8 is formed on the photoresist film 3, no sticking development occurs and the film can be easily separated with a small force (FIG. 10). Next, the anti-sticking film 8 is dissolved and removed using trichloride, and then the pig photoresist film 3 is developed to dissolve and remove the unaltered photoresist film 3 under the surface of the mask pattern 6, thereby forming a window. A hole 3a is formed (FIG. 11). Furthermore, the oxide film 2 exposed from the window hole 3a
is removed by etching to form a window hole 2a (FIG. 12). Thereafter, the remaining photoresist film 3 is dissolved and removed, impurities are selectively diffused through the window holes 2a, and the entire semiconductor wafer 1 is selectively etched.

In the above embodiment, the photolithography of the oxide film 2 has been described, but the present invention can also be applied to the photolithography of a nitride film or other insulating film, or an ohmic metal such as aluminum.

Furthermore, in the above embodiment, the anti-sticking film ε3 is formed of a fluorocarbon resin and is removed before the development of the photoresist film 3.
If it can be dissolved in a solvent of C.

Development processing can be performed immediately.

BRIEF DESCRIPTION OF THE PRESENT INVENTION FIGS. 1 to 5 are cross-sectional views of a semiconductor wafer at each stage to explain a conventional oxide film photolithography process.

FIGS. 6 to 12 are for explaining an oxide film photolithography process according to an embodiment of the present invention.
FIG. 3 is a cross-sectional view of a semiconductor wafer at each stage.

l... Semiconductor wafer, 2... Oxide film, 3... Photoresist film, 4...Mask, 7... Ultraviolet rays, 8... Anti-sticking film.

103

Claims (1)

[Claims] A step of forming a photoresist film on the surface of the 48 body, a step of forming an anti-sticking film on the photoresist film, and exposing the semiconductor wafer by bringing it into close contact with a mask. A method for manufacturing a semiconductor device, comprising: a step of separating the semiconductor wafer 1 from a mask and developing a photoresist film.