JPH03196522A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To form a gentle stair-shaped stepped section by conducting photoengraving only once at first and then repeating side-etching and etching in the depth direction. CONSTITUTION:The mask material 1 of an uppermost layer is patterned, a second semiconductor layer 2 is etched while using the mask material 1 as a mask, and a first semiconductor layer 3 is etched in desired depth while employing these mask material 1 and second semiconductor layer 2 as masks. The second semiconductor layer 2 is under-etched in the cross direction in desired quantity, and the first semiconductor layer 3 is etched in desired depth while using the second semiconductor layer 2 as a mask. A process in which the second semiconductor layer 2 is side-etched and the first semiconductor layer 3 is etched in desired depth while employing the second semiconductor layer 2 as a mask is repeated. Accordingly, a gentle stair-shaped stepped section can be formed to the first semiconductor layer 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a semiconductor device, and particularly to a method of forming a step on the surface of a semiconductor layer.

[Conventional technology]

FIGS. 2(-) to 2(f) are process cross-sectional views showing a conventional method of forming this type of step. In this figure, 11a to 1
1c is a patterned resist pattern, and 12 is a semiconductor layer in which a step is formed.

Next, a method for forming this step will be explained.

When forming a step on the surface of the semiconductor layer 12, it is necessary to make the step portion gentle for convenience of the process. Conventionally, this method involves repeating photolithography and etching in a stepwise manner so that each step becomes smaller. Specifically, as shown in FIG. 2(a), first, a resist is applied to the semiconductor layer 1.
2, and photolithography is performed to form a resist pattern lla. Subsequently, as shown in FIG. 2(b), the semiconductor layer 12 is etched to form a first step. Thereafter, as shown in FIG. 2(e), a new resist layer 11b is formed by photolithography. Thereafter, using the resist batten 11b as a mask, etching is performed as shown in FIG. 2(d) to form a second level difference. Furthermore, as shown in FIG.
12 etching steps are repeated to form a plurality of steps.

[Problem to be solved by the invention]

As described above, in the conventional method of forming steps, photolithography is repeatedly performed when etching steps, so the process is extremely long.

An object of the present invention is to solve the above-mentioned problems and to provide a method for manufacturing a semiconductor device that can form a gentle step with a simple process.

[Means to solve the problem]

A method for manufacturing a semiconductor device according to the present invention includes a step of depositing a second semiconductor layer on the first semiconductor layer, and further depositing a mask material on the second semiconductor layer.

After performing desired patterning on the mask material, using this mask pattern as a mask, patterning a second semiconductor layer using a liquid or gas that does not etch the first semiconductor layer and the mask material; Using the semiconductor layer as a mask, etching the first semiconductor layer to a desired depth using a liquid or gas that does not etch the second semiconductor layer and the mask material, followed by not etching the first semiconductor layer and the mask material. etching the second semiconductor layer in the lateral direction using a liquid or gas; using the second semiconductor layer as a mask, etching the first semiconductor layer using a liquid or gas that does not etch the second semiconductor layer or the mask material; The first semiconductor layer is etched stepwise by repeating etching to a desired depth, etching in the lateral direction and etching in the depth direction.

[Effect]

In this invention, the uppermost layer mask material is punctured, and the second semiconductor layer is etched using this as a mask,
Using these mask materials and the second semiconductor layer as a mask, the first semiconductor layer is etched to a desired depth, and then the second semiconductor layer is etched by a desired amount, that is, etched laterally. Using the second semiconductor layer as a mask, the first
After etching the semiconductor layer to a desired depth and side-etching the second semiconductor layer, repeat the process of etching and sowing the first semiconductor layer to a desired depth using this second semiconductor layer as a mask. As a result of this process, the first semiconductor layer is etched in a gradual stepwise manner.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

1(a) to 1(g) are process cross-sectional views of a method for manufacturing a semiconductor device showing an embodiment of the present invention.

In FIG. 1, 1 is a SiN film that is a mask material, 2 is an InP layer that is a second semiconductor layer, and 3 is an InGaAs layer that is a first semiconductor layer.

First, the 5iNW 41 is patterned by dry etching with CF4 using a resist (not shown) as a mask so as not to etch the InP layer 2 (see Fig. 1(a).
)). Subsequently, using the SiN film 1 as a mask, the In2 layer 2 is patterned by etching with HCI without etching the InGaAs layer 3 (FIG. 1(b)).

Then, using In2 layer 2 as a mask, remove In2 with dilute sulfuric acid.
GaAs3 is etched to a desired depth and patterned (Fig. 1 (C1)). Then, the In2 layer 2 is further under-etched with HCI (Fig. 1 (d)). Subsequently, the under-etched InP layer 2 is masked. as I
The nGaAs layer 3 is etched to a desired depth with dilute sulfuric acid (FIG. 1(e)). Furthermore, after under-etching the In2 layer 2 (FIG. 1(f)), the InGaAs layer 3 is etched to a desired depth. Etch (Fig. 1(g)). In this way, by repeatedly under-etching the InP layer 2 and etching the InGaAs layer 3, the InGaAs layer 3 is etched.
The As layer 3 can be etched in a gradual stepwise manner.

〔Effect of the invention〕

As explained above, the present invention includes a process of depositing a second semiconductor layer on a first semiconductor layer, further depositing a mask material on the second semiconductor layer, and applying desired patterning to the mask material. After that, a step of patterning the second semiconductor layer using a liquid or gas that does not etch the first semiconductor layer and the mask material using this mask coating as a mask, and a step of patterning the second semiconductor layer using the mask coating and the second semiconductor layer as a mask. etching the first semiconductor layer to a desired depth using a liquid or gas that does not etch the second semiconductor layer and the mask material, followed by a second step using a liquid or gas that does not etch the first semiconductor layer and the mask material; A step of laterally etching the second semiconductor layer, using the second semiconductor layer as a mask and etching the first semiconductor layer to a desired depth using a liquid or gas that does not etch the second semiconductor layer or the mask material. The first semiconductor layer is etched stepwise by repeating these horizontal etching and depth etching processes, so photolithography is only performed once at the beginning, and then side etching and depth etching are performed. By repeating this etching, a gradual step-like step can be formed. Therefore, the effect of significantly shortening the process can be obtained.

[Brief explanation of drawings]

FIG. 1 is a process sectional view showing an embodiment of the semiconductor device manufacturing method of the present invention, and FIG. 2 is a process sectional view showing a conventional semiconductor device manufacturing method. In the figure, 1 is a SiN film, 2 is a 1nPJii film, and 3 is an I
It is an nGaAs layer.

Claims (1)

[Claims] A step of depositing a second semiconductor layer on the first semiconductor layer and further depositing a mask material on the second semiconductor layer, and after performing desired patterning on the mask material, the mask pattern is used as a mask. patterning the second semiconductor layer using a liquid or gas that does not etch the first semiconductor layer and the mask material; using the mask pattern and the second semiconductor layer as a mask, patterning the second semiconductor layer and the mask; etching the first semiconductor layer to a desired depth using a liquid or gas that does not etch the material, and then etching the second semiconductor layer using a liquid or gas that does not etch the first semiconductor layer and the mask material. a step of laterally etching the layer; and a step of etching the first semiconductor layer to a desired depth using the second semiconductor layer as a mask and using a liquid or gas that does not etch the second semiconductor layer and the mask material. A method for manufacturing a semiconductor device, comprising the steps of: etching the first semiconductor layer in a stepwise manner by repeating etching in the lateral direction and etching in the depth direction.