JPH04354122A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To stably form an upward expanding sectional shape of a contact window without using control etching, regarding a method of forming a contact window to a substratum in a multilayered constitution insulating layer composed of a plurality of insulating films formed in order on the substratum. CONSTITUTION:By etching wherein masks 7B, 8B are arranged at each time of forming insulating films 2, 3, windows 2b, 3b exposing a substratum 1 in a contact window forming part are formed in the following manner. The window 2b to be formed in the insulating film 2 whose formation order is n-th (first in figure) is so constituted that the window 3b to be formed in the (n+1)th (second in figure) insulating film 3 is contained in the almost flat region of the insulating film 3 in the region of the window 2b so as to have margin. The window 3b to be formed in the insulating film 3 whose formation order is last is constituted so as to have a size conformed to the bottom part of a contact window 5.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of forming a contact window to a base in a multilayer insulating layer consisting of a plurality of insulating films sequentially formed on the base. Regarding.

[0002] In the manufacture of semiconductor devices, contact windows are sometimes formed in the multilayer insulating layer. In that case,
As the contact window becomes deeper due to the increase in the thickness of the insulating layer,
In order to ensure step coverage of the electrode formed on the insulating layer, it is desirable that the cross-sectional shape of the contact window expands upward.

0003

2. Description of the Related Art FIGS. 3A and 3B are cross-sectional views showing a conventional method for forming the contact window in the multilayer insulating layer, in order of steps, and show a case in which the number of insulating films is two. In the figure,
1 is a base, 2 is a first insulating film, 3 is a second insulating film, 4 is a multilayer insulating layer consisting of the first insulating film 2 and the second insulating film 3;
5 is a contact window, and 6 is an electrode.

First, as shown in FIG. 3(a), a first insulating film 2 is formed on a base 1, and a mask 7A is provided on the first insulating film 2.
The insulating film 2 is etched, and a window 2a of a size corresponding to the bottom of the contact window is formed in the first insulating film 2 as shown in FIG. 3(b).
Open the day. The window 2a exposes the base 1.

Next, as shown in FIG. 3(c), a second insulating film 3 is formed on the first insulating film 2 including the window 2a region to form a multilayer insulating layer 4, and a mask 8A is provided thereon. Then, the second insulating film 3 is etched, and the second insulating film 3 is etched as shown in FIG. 3(d).
A window 3a larger than the hole 2a is formed in the insulating film 3. that time,
The second insulating film 3 within the window 2a is removed to expose the base 1 again, but the first insulating film 2 exposed around the window 2a is not removed as much as possible. As a result, a contact window 5 whose cross-sectional shape expands upward is formed.

Therefore, the electrode 6 formed on the multilayer insulating layer 4 and connected to the base 1 through the contact window 5 is as shown in FIG.
Step coverage of the contact window 5 is ensured as shown in (e).

[0007]

[Problems to be Solved by the Invention] However, in the above-mentioned conventional method, the first insulating film 2 often cannot act as an etching stopper during etching to open the window 3a in the second insulating film 3. Control etching is required to prevent the insulating film 2 from being over-etched, in which the etching is stopped in anticipation. This has the problem of making the cross-sectional shape of the contact window 5 unstable, which greatly affects the shape of the electrode 6.

Therefore, the present invention relates to a method of manufacturing a semiconductor device, and in particular, to a method of forming a contact window in a multilayer insulating layer as described above, the present invention relates to a method of forming a contact window in a multilayer insulating layer as described above, and a cross-sectional shape of the contact window that expands upward without using controlled etching. The purpose of the present invention is to provide a method that can stably form .

[0009]

[Means for Solving the Problems] Fig. 1 is a process-order sectional view for explaining the principle of the present invention, and corresponds to Fig. 3 illustrating a conventional example. Therefore, as in the case of the conventional example, the case where the number of insulating films is two is shown, and in the figure, the same reference numerals as in FIG. 3 indicate the same objects.

Referring to FIG. 1, in order to achieve the above object, the method for manufacturing a semiconductor device according to the present invention includes a multilayer insulating layer consisting of a plurality of insulating films 2 and 3 sequentially formed on a base 1. 4, when forming the contact window 5 to the base 1, windows 2b and 3b are formed to expose the base 1 in the contact window forming portion by etching using masks 7B and 8B for each insulating film 2 and 3 formed. The window 2b opened in the insulating film 2 whose formation order is nth (first in the figure) is n+
The window 3b opened in the first (second in the figure) insulating film 3 is
It is characterized by having a size that fits within the region of the former window 2b in a substantially flat region of the latter insulating film 3 with some margin left.

The window 3b opened in the insulating film 3 which is the last in the formation order (the second in the figure) is the contact window 5.
It should be sized to match the bottom of the.

0012

[Operation] According to the above structure, the window 3b opened in the insulating film 3
Since the area of the window 2b opened in the insulating film 2 is made to fit within the above-mentioned almost flat area of the insulating film 3 with a margin, control etching is not required, and the cross-sectional shape of the contact window is made to expand upward. It is possible to form it stably.

By matching the size of the window 3b to the bottom of the contact window 5, the size of the bottom of the contact window 5 can be secured. The above explanation is 2 or 3
In this case, the number of insulating films shown by is 2, but if the number is 3
Even in the above cases, a desired contact window can be stably formed by doing the same.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of manufacturing a semiconductor device to which contact window formation according to the present invention is applied will be described below with reference to step-by-step cross-sectional views of FIG.

In this embodiment, the semiconductor device includes a bipolar transistor, a poly-Si wiring, and a poly-Si wiring in the same layer.
It has a resistive element, and in order to introduce silicide to reduce the resistance of the poly-Si wiring, the insulating layer forming the contact window to the poly-Si resistive element has a multilayer structure.

In FIG. 2, FIG. 2(a) shows the Si substrate 2.
1 shows a state in which a bipolar transistor 20 and a poly-Si resistance element 11 are formed. In the figure, 22 is a field oxide film, 23 is a base, 24 is an emitter, 25 is a poly-Si wiring for leading out the base, 26 is a poly-Si film for leading out the emitter, and the poly-Si resistance element 11 is a field oxide film. The poly-Si wiring 25 is formed on the same layer as the poly-Si wiring 25 . In addition, in order to separate the poly-Si film 26,
An SiO2 insulating film 12 is provided to cover the i-wire 25 and the poly-Si resistance element 11.

The contact window according to the present invention is formed to lead out from the poly-Si resistive element 11, and the contact window is formed for the purpose of leading out from the poly-Si resistive element 11 and the SiO2 insulating film 12.
correspond to the base 1 and first insulating film 2 in FIG. 1 described above.

After this, referring to FIG. 1(b), a window is opened in the SiO2 insulating film 12 by etching with a mask to expose the poly-Si wiring 25 and the poly-Si resistive element 11, and the portion is etched. Silicide 27 is formed. At this time, the size of the window 12b exposing the poly-Si resistive element 11 is made the same as the window 2b explained in FIG. Silicide 27
is for reducing the resistance of the poly-Si wiring 26.

Next, referring to FIG. 1(c), a SiO2 insulating film 13 is formed by CVD. This SiO2 insulating film 13 covers the exposed portions of the poly-Si wiring 25 and the poly-Si film 26, and corresponds to the second insulating film 3 in FIG. 1 with respect to the contact window of interest. Therefore, S
The iO2 insulating films 12 and 13 constitute a multilayer insulating layer 14 corresponding to the multilayer insulating layer 4 in FIG.

Next, referring to FIG. 1(d), windows are opened in the SiO2 insulating film 13 by masked etching to form contact windows to the poly-Si wiring 25 and the poly-Si film 26, and the poly-Si A contact window 15 to the resistive element 11 is formed. The contact window 15 corresponds to the contact window 5 in FIG.
The size of window 13b that opens in Figure 3 is the same as window 3b explained in Figure 1.
Do the same as. Therefore, although the contact window 15 is formed in the multilayer insulating layer 14, control etching is not required for etching the SiO2 insulating film 13, and the upwardly expanding cross-sectional shape is stable.

Next, referring to FIG. 1(e), the base 2
Electrode 28 connected to 3, Electrode 2 connected to emitter 24
9. An electrode 16 connected to the poly-Si resistive element 11 is also formed to complete the semiconductor device. Here, the electrode 16
corresponds to the electrode 6 in FIG.

[0022]

As described above, the present invention relates to a method of manufacturing a semiconductor device, and particularly, a method for manufacturing a semiconductor device, in which a multilayer insulating layer consisting of a plurality of insulating films sequentially formed on a base, is provided with a contact to the base. Regarding the method of forming a window, there is provided a method that can stably form a cross-sectional shape that expands upward in a contact window without using controlled etching, and has the effect of enabling stable manufacture of the contact window. .

[Brief explanation of the drawing]

[Fig. 1] Process-order cross-sectional diagram for explaining the principle of the present invention

[Figure 2] Process order cross-sectional diagram for explaining the example

[
Figure 3: Process-order cross-sectional diagram to explain the conventional method

[Explanation of symbols]

1 Underlayer 2 First insulating film 2a, 2b Window 3 in first insulating film 3 Second insulating film 3a, 3b Window 4 in second insulating film Multilayer insulating layer 5 Contact window 6 Electrode 7A, 7B, 8A, 8B Mask for window opening etching 11 Poly-Si resistance element (base) 12 SiO2 insulating film (first insulating film) 12b
Window 13 opened in SiO2 insulation film (first insulation film)
SiO2 insulating film (second insulating film) 13b SiO2
Window 14 in the insulating film (second insulating film) Multilayer insulating layer 15 Contact window 16 to the poly-Si resistor element 20 Electrode 20 connected to the poly-Si resistor element Bipolar transistor 21 Si substrate 22 Field oxide film 23 Base 24 Emitter 25 Poly-Si wiring 26 for leading out the base Poly-Si film 27 for leading out the emitter Silicide 28 Electrode 29 connected to the base 29 Electrode connected to the emitter

Claims (2)

[Claims] [Claim 1] A multilayer insulating layer (4) consisting of a plurality of insulating films (2, 3) sequentially formed on a base (1).
When forming a contact window (5) to the base (1), a mask (
7B, 8B) to expose the base (1) in the contact window forming part by etching (2b, 3b).
) and whose formation order is nth (2)
The window (2b) that opens in is the n+1th insulating film (3)
The manufacturing of a semiconductor device characterized in that the window (3b) opened in the first window (3b) is sized to fit in a substantially flat area of the latter insulating film (3) within the area of the former window (2b) with a margin. Method. 2. The window (3b) formed in the insulating film (3) that is last in the formation order is sized to match the bottom of the contact window (5). A method of manufacturing the semiconductor device described above.