JPH0263292B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of forming an aluminum layer formed on a semiconductor wafer into a predetermined pattern by etching.

<Prior Art> A conventional method will be explained with reference to FIGS. 2 and 3.

FIG. 2 is a cross-sectional view of each step of the most common method using a resin resist.

First, a resist 30 is applied to the aluminum layer 20 formed on the semiconductor wafer 10, and the resist 30 is exposed and developed in a predetermined pattern (second
(see figure a). Then, the semiconductor wafer 10 is immersed in an etching solution to perform etching. Then, since isotropic etching is performed, a part of the resist 30 may be peeled off from the aluminum layer 20, and a pattern having a trapezoidal cross section as shown in FIGS. 2b and 2c may be formed. Such a pattern has the disadvantage that it is easy to break because it is thin, and the precision of the pattern is not very good.

In order to solve this problem, there is a method of using a rubber-based negative resist as the resist, as shown in FIG. Rubber-based negative resists are resists that use natural or synthetic rubber as a basic material, and have the property of being more easily softened during development processing than resin-based negative resists.

First, the resist 30 is exposed to a predetermined pattern.
Develop (see Figure 3a). Then, half etching is performed to remove about half of the aluminum layer 20 in the thickness direction (see FIG. 3b). Baking the half-etched semiconductor wafer 10,
The resist 30 remaining on the semiconductor wafer 10 is softened and the resist 30 is transferred to the aluminum layer 20.
(See Figure 3c). Then, perform etching again.

<Problems to be Solved by the Invention> However, the above-mentioned conventional example has the following problems.

That is, even if the resist 30 is softened by baking after half-etching, the resist 30 may not be able to adhere to the aluminum layer 20 (see A shown in FIG. 3c). Then, as shown in FIGS. 3d and 3e, only one side of the pattern of the aluminum layer 20 is formed to be thin.

The present invention was created in view of the above circumstances, and
It is an object of the present invention to provide a method for manufacturing a semiconductor device that can improve the precision of aluminum wiring formed by etching an aluminum layer.

<Problems to be Solved by the Invention> A method for manufacturing a semiconductor device according to the present invention includes a step of applying a rubber-based negative resist based on natural or synthetic rubber to an aluminum layer formed on a semiconductor wafer, and A method for manufacturing a semiconductor device comprising the steps of: developing the semiconductor wafer into a predetermined pattern; and etching the aluminum layer by immersing the semiconductor wafer in an etching solution. After taking it out and performing resist development and heat treatment again, the etching process is continued.

<Operation> When, for example, about half of the aluminum layer has been removed, the semiconductor wafer is taken out from the etching solution. Then, the semiconductor wafer is subjected to resist development and heat treatment again. Thereafter, the etching process is continued again.

<Example> Hereinafter, an example according to the present invention will be described with reference to the drawings.

FIG. 1 is a cross-sectional view of each step of a method for manufacturing a semiconductor device according to an embodiment of the present invention.

A rubber-based negative resist 30 is applied to the aluminum layer 20 formed on the semiconductor wafer 10, and the rubber-based negative resist 30 is exposed to light in a predetermined pattern. (See Figure 1a).

Note that the rubber-based negative resist herein refers to a photoresist that is based on natural or synthetic rubber and contains a photocrosslinking agent such as a bisazide type, such as OMR-83 manufactured by Tokyo Ohka.

After the semiconductor wafer 10 is heat-treated at, for example, 140 to 160° C., it is etched by being immersed in an etching solution containing phosphoric acid as a main component. This etching process consists of two steps. First, etching is performed until about half of the exposed aluminum layer 20 is removed (see FIG. 1b). Then, the portions of the aluminum layer 20 where the rubber-based negative resist 30 remains become in a so-called undercut state. In this state, the semiconductor wafer 10
Remove it from the etching solution and wash it.

Thereafter, the rubber-based negative resist 30 attached to the semiconductor wafer 10 is reproduced and heat treated.
When the image is reproduced and the heat treatment is performed, the rubber-based negative resist 30 is softened, and the overhanging portion of the rubber-based negative resist 30 sags down and comes into close contact with the aluminum layer 20 again (see FIG. 1d). .

After the overhanging rubber-based negative resist 30 is in close contact with the aluminum layer 20, the semiconductor wafer 10 is immersed in the etching solution again to remove the remaining aluminum layer 20 and form an aluminum pattern (see FIG. 1e). ).

Once the aluminum layer 20 has been formed into a predetermined pattern, the semiconductor wafer 10 is removed from the etching solution and the remaining rubber-based negative resist 3 is removed.
0 is removed (see Figure 1f).

<Effects of the Invention> In the semiconductor device manufacturing method according to the present invention, the semiconductor wafer is taken out from the etching solution during the etching process and the rubber-based negative resist is reproduced, so that some peeling may occur during the etching process. The rubber-based negative resist re-swells and softens, so that it wraps around and adheres to the aluminum layer again.

Therefore, according to the present invention, there is less overetching due to resist peeling, and the precision of aluminum patterns, such as aluminum wiring, can be improved.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of each step of a method for manufacturing a semiconductor device according to an embodiment of the present invention, and FIGS. 2 and 3 are cross-sectional views of each step of a conventional method of manufacturing a semiconductor device. 10...Semiconductor wafer, 20...Aluminum layer, 30...Rubber-based negative resist.

Claims (1)

[Claims] 1 A step of applying a rubber-based negative resist based on natural or synthetic rubber to an aluminum layer formed on a semiconductor wafer, a step of developing the resist into a predetermined pattern, and a step of immersing the semiconductor wafer in an etching solution. A method for manufacturing a semiconductor device comprising a step of etching an aluminum layer, characterized in that the semiconductor wafer is taken out of the etching solution during the etching step, the resist is developed and heat treated again, and then the etching treatment is continued. A method for manufacturing a semiconductor device.