JPH03239337A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To maintain the offset amount between a first recess and a second recess constant at all times by a method wherein a lozenge insulating film is formed on a substrate and a specific side-end edge part of the insulating film is removed sequentially to form the first recess and the second recess. CONSTITUTION:An insulating film 2 of a lozenge pattern is formed; a second photoresist layer 4 having a pattern in a desired shape is formed on a substrate 1. One part of the insulating film 2 is left on the sidewall on one side of the second photoresist layer 2; the GaAs substrate 1 is etched by using the pattern as a mask; a first recess 6 is formed. Then, the insulating film 2 is etched and removed; the GaAs substrate 1 is etched again to form a second recess 7. The recess is an offset two-stage recess in which individual central positions of an upper-stage recess part and a lower-stage recess part are dislocated. Thereby, a minute gate can be formed; a self-alignment operation can be executed; an offset amount can be maintained always constant.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of manufacturing a semiconductor device having a two-stage recess structure.

[Conventional technology]

FIG. 3 is a cross-sectional view showing steps in a conventional method for manufacturing a semiconductor device having a two-stage recess structure. In the same figure, (1
) is a GaAs substrate, (3) and (4) are photoresist layers, and (5) is a gate metal layer. The figures will be explained below.

First, a first photoresist layer (3) is formed on a GaAs substrate (1), and a desired pattern is formed on the layer by photolithography as shown in FIG. 3(a). Next, using the photoresist layer (3) as a mask, the GaAs substrate (1) is etched with tartaric acid to form a first recess (6) as shown in FIG. 3(b). Next, after removing the photoresist layer (3), a second photolettuce scrap (4) is formed, and a part of the layer covering the first recess (6) is coated with photolithography. A desired pattern is formed as shown in FIG. next,
Tartaric acid creates the first recess (
Form a second recess (7) narrower than 5). Next, as shown in FIG. 3(e), after forming a gate metal layer (5) by vapor deposition, lift-off is performed to form a second photoresist layer (4) and a gate metal layer (5) thereon.
As shown in FIG. 3(f), only the gate metal layer (5) in the recess is left.

[Invention or problem to be solved]

In the conventional manufacturing method, when forming the second recess (7), the first recess (7) is formed in the photo linking process.
6), it is difficult to maintain the offset amount between the first and second recesses (the amount of deviation in the center position of the first and second recesses) constant. Ta.

This invention was made in order to solve the problem as described in L, and eliminates the need for alignment between the second recess and the first recess when forming the second recess, that is, enables self-alignment, The object of the present invention is to obtain a method for manufacturing a semiconductor device having a two-stage recess structure that always has a constant offset acid.

(Means for Solving the Problems) A method for manufacturing a conductor device according to the present invention includes forming a diamond-shaped insulating film on a semiconductor substrate, and then forming a diamond-shaped insulating film on one side edge of the insulating film. The remaining insulating film portion is removed to form a first recess in the semiconductor substrate, and then one side edge portion of the insulating film is removed to form a second recess in the semiconductor substrate. A two-stage recess structure is formed in a semiconductor substrate.

[Effect]

In the method for manufacturing a semiconductor device according to the present invention, by forming a diamond-shaped insulating film, alignment is not required when forming the second recess, and the amount of offset between the first and second recesses is always maintained constant. .

〔Example) Hereinafter, one embodiment of the present invention will be described with reference to FIG.

FIGS. 1(a) to 1(j) are cross-sectional views showing the main steps of the manufacturing method, in which (2) is an insulating film made of silicon oxide, silicon nitride, or the like. Note that the same reference numerals as in Figure 3 indicate the same or corresponding parts as those in the garden.

First, as shown in Figure 1(a), for example, about 6004 m
An insulating film (2) with a thickness of about lp, m is formed on an aAs substrate (1)-, ) with a thickness of about 0.
．． The first photoresist layer (3
), and a mask of the desired shape is formed on that layer using conventional exposure techniques. Next, reactive ion etching (RIRE) using sulfur fluoride (SF) was performed from an oblique direction at an angle θ with respect to the vertical direction.
), the insulating film (2) is formed into a diamond-shaped pattern. Note that the ion beam black angle θ is selected to be approximately 30° to 45°, for example.

Also, if the mask length is M and the film J'7d of the insulating film (2), M-d tan O is the width of the first recess formed in the subsequent process, that is, the recess shown in FIG. 1(f). Determine the width W.

Next, after removing the I-th photoresist 1 to layer (3),
Apply a second photoresist to the entire surface by aCt, mask alignment, exposure, and development to form a pattern of the desired shape as shown in FIG. 1(c).
) is formed on the substrate (1,). Next, the second photoresist layer (4) is heated to 140°C or higher to thermally deform it as shown in FIG. After that, reactive ion beam etching was performed using SF, as shown in Fig. 1(e).
As shown in FIG. 2, a portion of the insulating film (2) is left on one side wall of the second photoresist layer (4). and,
Using this pattern as a mask, tartaric acid was applied to the GaAs substrate (
1) to form a first recess (6) as shown in FIG. 1(f). Note that, for example, a first recess (6) is formed in the epitaxial region with a thickness of about 5000 Å, which is generated in the substrate (1) at an impurity concentration of 1017/C[11'.
When forming a recess, the depth of the recess is about 2000λ.

After forming the first recess, as shown in No. 11' Etch the GaAs substrate (1) again with tartaric acid, as shown in Figure 1 (
11), a second recess (7) is formed.

This recess is an offset two-stage recess in which the centers of the L-stage recess portion and the lower-stage recess portion are shifted from each other. Note that the depth of this recess is about 2000λ deeper than the first recess.

Next, as shown in FIG. 1(i), after forming a gate metal layer (5) by vapor deposition, as shown in FIG. 1(j), lift-off is performed to form a second photoresist layer. The second gate metal layer (5) is removed, leaving only the gate metal layer (5) formed within the second recess (7).

Next, another embodiment of the present invention will be described using FIG. 2. In the figure, the same reference numerals as in figure ff11 indicate the same or corresponding parts as in that figure.

First, as shown in FIG. 2(a), a GaAs substrate (1) is
An insulating film (2) made of silicon nitride is formed on L, and with the exception of a part of the film, 3 i + + is implanted from an oblique direction at 300 KcV and an implantation depth of 0.25 gm using a focused ion beam (FIB) method. X] Inject to a concentration of Q+4/C113.

Next, as shown in FIG. 2(b), only the ion implantation region is removed using 10%II(,Q).The subsequent steps are as shown in FIG.
Since the steps are the same as those in c) to (j), the explanation will be omitted.

In each of the above-described embodiments, a two-stage recess structure is formed by forming a diamond-shaped insulating film (2), thereby making it possible to form a finer gate than in the conventional method. Also, the first
In FIG. 2(j) and FIG. 2(j), for example, if the train electrode is provided on the left side with respect to the gate metal layer (5), a field effect transistor with high train breakdown voltage can be obtained.

(Effects of the Invention) As described above, according to the present invention, it is possible to manufacture a semiconductor device having a two-stage recess structure in which self-alignment is possible and the amount of offset is always maintained constant.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the main steps of a method for manufacturing a semiconductor device according to an embodiment of the present invention, and FIG. 2 is a sectional view showing the main steps of a method for manufacturing a semiconductor device according to another embodiment of the invention. FIG. 3 is a cross-sectional view showing each step of a conventional method for manufacturing a semiconductor device. In the figure, (1) is a semiconductor substrate, (2) is an insulating film, (
4) is a resist layer, (5) is an electrode, (6) is a first recess, and (7) is a second recess. In each drawing, the same reference numerals indicate the same or corresponding parts. Agent Masu Oiwa Yuyu 1 Figure (1) JP-A-3 239337 (4) Figure (2) Wataku 2 Figure (1) Condolences (2) (2)

Claims (1)

[Claims] (1) A first step of forming, on a portion of the substrate, a diamond-shaped insulating film whose opposite side edges extend in a direction forming a desired angle with respect to the vertical direction of the semiconductor substrate; a second step of forming a resist layer on the substrate around the substrate in close contact with the substrate; a third step of removing the film and forming a first opening in the resist layer; a fourth step of forming a first recess in the substrate through the first opening; and a fourth step of forming a first recess in the substrate through the first opening. a fifth step of forming a second opening in the resist layer by removing a portion of the film; and a sixth step of forming a second recess in the substrate through the second opening. , a seventh step of forming an electrode in the second recess, and a method for manufacturing a semiconductor device.