JPH0582657A - Semiconductor device - Google Patents

Abstract

PURPOSE:To enhance the reliability of the title device by eliminating that a photoresist pattern used to open a through hole is collapsed near the stepped part of a lower-layer interconnection. CONSTITUTION:A semiconductor substrate is provided with the following: a composite insulating film, as an insulating film, which is composed of a combination of a plurality of kinds of insulating films 3, 4, 5; and a pigment-containing coating film 6, as one constituent element of the composite insulating film, which contains a pigment which absorbes the wavelength of light used for photolithographic exposure. Thereby, since a through hole having a desired opening shape can be obtained in the composite insulating film, an effect that the high density of the title device is achieved can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring circuit formation of a semiconductor device, and more particularly to a method of opening an insulating film for electrically connecting different layer wirings.

[0002]

2. Description of the Related Art As shown in FIG. 5, a conventional semiconductor device has a first wiring 21 for forming an electronic circuit between elements on a semiconductor substrate on which elements such as transistors and resistors are formed.
Is formed, the first insulating film 23 is formed on the upper layer of the first wiring 21, and the second wiring 22 is formed on the upper layer of the first insulating film 23. The first insulating film 23 is usually formed by combining films of several kinds of materials. A second insulating film 24 is formed on the upper layer of the second wiring 22, a silicon oxide-containing solution is applied to the upper layer of the second insulating film 24, and a coating formation film 26 obtained by firing at low temperature is formed. Further, a third insulating film 25 is formed thereover. A composite film (hereinafter referred to as a composite insulating film) including a second insulating film 24, a coating forming film 26, and a third insulating film 25 for electrically connecting the second wiring 22 and the third wiring above the second wiring 22. ). As a procedure, a positive type photoresist film 27 is formed on the third insulating film 25 by a coating method, the other region is masked so that the light is applied only to the region which is opened from above, and the exposure liquid is developed. Thus, the photoresist film 27 in the photosensitive area is removed. Then, a desired opening shape was opened during composite mounting by dry etching using an etching gas.

[0003]

In this conventional semiconductor device, the step of the second insulating film 24 formed by the first wiring 21 defines the shape of the second wiring 22. First wiring 2
5, FIG. 6, FIG. 8 is a cross-sectional view in the case where an opening is formed in the composite insulating film on the second wiring 22 that is positioned so as to overlap with 1 so as to straddle the edge of the first wiring 21. The figure is shown in FIG. FIG. 5 is a cross-sectional view after the opening-shaped pattern is exposed from above the photoresist film 27. The desired exposure area is the first photosensitive area 2 exposed by the incident light from above.
8 The second wiring 2 immediately above the edge of the first wiring 21
Since 2 is curved with a step, incident light at the time of exposure is reflected on the surface of the second wiring 22 to form a second photosensitive region 29 in the photoresist film 27. FIG. 6 is a cross-sectional view after removing the photoresist film on the photosensitive portion with a developing solution.
Since the second photosensitive area 29 is formed outside the first photosensitive area 28, the photoresist opening 30 after development becomes larger than the desired shape, and the edge 31 of the photoresist opening is the edge 31 of FIG. It becomes irregular as shown in the later plan view. FIG. 8 is a diagram after opening the composite insulating film by dry etching. When dry etching is performed through the photoresist openings 30 which are larger than the desired opening shape and are irregularly formed, the composite insulating film is opened larger than desired, and when the opening is larger than the second wiring 22, the first insulating film is formed. Since the insulating film 23 is also etched, the cross-sectional shape is significantly deteriorated and the reliability of the wiring is reduced. Normally, in order to avoid unintended etching of the first insulating film, the second wiring 22 is enlarged as shown in FIG. 9 so that the edge 31 of the irregular photoresist opening is protruded from the second wiring 22. I try not to. When an opening of 3 μm square is to be formed in the composite insulating film, the size of the second wiring 22 must be increased by 3 μm in consideration of the increase of the opening of 3 μm due to reflection at the time of exposure. It was a big obstacle to high density.

[0004]

The semiconductor device of the present invention comprises:
A composite insulating film composed of a combination of a plurality of insulating films is provided, and a dye-containing coating forming film containing a dye that absorbs the wavelength of light used for photolithography exposure is provided as one component of the composite insulating film. Have

[0005]

The present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of an embodiment of the present invention.
A first wiring 1 for forming an electronic circuit between the elements is formed on a semiconductor substrate 20 on which the elements are formed.
A first insulating film 3 made of a silicon oxide film or a silicon nitride film is formed on the upper layer, and a second wiring 2 is formed on the upper layer of the first insulating film 3. A second insulating film 4 made of a silicon oxide film or a silicon nitride film is formed on the second wiring 2. A dye-containing coating forming film 6 is formed by applying a silicon oxide-containing solution in which a yellow dye, which is a yellow dye that is a mixture of titanium oxide and lead oxide, is mixed to the upper layer of the second insulating film 4 and firing at a low temperature.
On top of that, a third layer of silicon oxide film or silicon nitride film is formed.
The insulating film 5 is formed. A composite film composed of the second insulating film 4, the dye-containing coating forming film 6 and the third insulating film 5 (hereinafter referred to as dye-containing) in order to electrically connect the second wiring 2 and the upper third wiring. (Referred to as a composite insulating film). As a procedure, a positive type photoresist film 7 is formed on the third insulating film 5 by using a coating method, and the other region is masked so that the light is exposed only from above and exposed, and then developed. The photoresist film in the photosensitive area is removed by a liquid. Figure 2
[Fig. 3] is a diagram showing a path of light at the time of exposure. Incident light from above sensitizes the photoresist film in the photosensitive area 8 and does not sensitize the photoresist film in the non-photosensitive area 9. Incident light passes through the transparent insulating film and the surface of the second wiring 2 Reflect on. Most of the reflected light passes through the photosensitive area 8 again, but in the vicinity of the step portion, it travels in the direction of the reflected light path 10 in the non-exposed area, and a mercury oscillation line having a wavelength of 435 nm is used for exposure.
The reflected light traveling toward the reflected light path 10 in the non-photosensitive region has a wavelength of 4
Since it is absorbed when passing through the dye-containing coating forming film 6 containing titanium yellow which is a dye that absorbs the 35 nm band, the photoresist film in the non-photosensitive internal reflection light path 10 is only the photosensitive region 8, A photoresist shape can be obtained.

Next, a second embodiment of the present invention will be described with reference to the drawings.

FIG. 3 is a view showing a cross section of the second embodiment and a light path at the time of exposure, and FIG. 4 is a plan view corresponding to FIG.

The process up to the formation of the dye-containing composite insulating film is the same as that of the first embodiment, and therefore its description is omitted. FIG. 3 shows two first wires 1
2 shows a case where an opening for electrically connecting the second wiring 2 and the third wiring is formed by using the negative type photoresist 11 among the two. The negative photoresist 11 solidifies when exposed to light. After the incident light is reflected on the surface of the second wiring 2 near the step of the first wiring 1 during exposure,
When the reflected light travels to the reflected light path 10 in the non-photosensitive region in the negative photoresist film 11, the dye-containing coating forming film 6 absorbs the reflected light before reaching the photoresist film 11, so that the non-photosensitive region is absorbed. No. 9 is not exposed and can obtain a desired shape.

[0010]

As described above, according to the present invention, the coating forming film in the composite insulating film contains a dye that absorbs the wavelength of light used during exposure, so that the surface of the second wiring 2 during exposure is exposed. Since the reflected light at 1 can be absorbed by the dye-containing coating forming film, there is an effect that a desired opening shape can be obtained even in the vicinity of a complicated lower layer shape having many steps. Since the desired opening shape can be obtained, it is not necessary to make the second wiring 22 large, which has been conventionally made large in order to avoid unintended etching of the first insulating film 23, and it is possible to make the second wiring 22 small and reduce the reliability. There is an effect that the density can be increased without the need.

[Brief description of drawings]

FIG. 1 is a sectional view of a first embodiment of the present invention.

FIG. 2 is a diagram showing a light path at the time of exposure according to the first embodiment of the present invention.

FIG. 3 is a sectional view of a second embodiment of the present invention.

FIG. 4 is a plan view corresponding to FIG.

FIG. 5 is a cross-sectional view of a conventional example after exposure.

FIG. 6 is a sectional view after development of FIG.

FIG. 7 is a plan view corresponding to FIG.

FIG. 8 is a cross-sectional view after dry etching of FIG.

FIG. 9 is a plan view of a conventional example in which a second wiring is enlarged.

[Explanation of symbols]

 1,21 First wiring 2,22 Second wiring 3,23 First insulating film 4,24 Second insulating film 5,25 Third insulating film 6 Dye-containing coating forming film 7,27 Positive type photo Resist film 8 Photosensitive region 9 Non-photosensitive region 10 Reflected light path in non-photosensitive region 11 Negative photoresist film 12 Photoresist opening 20 Semiconductor substrate 26 Coating film 28 First photosensitive region 29 Second photosensitive region 30 Photoresist Opening 31 Edge of photoresist opening

Claims (2)

[Claims] 1. A semiconductor device having a composite insulating film composed of a combination of a plurality of types of insulating films, wherein a dye that absorbs a wavelength of light used for exposure of photolithography is used as one component of the composite insulating film. A semiconductor device having a dye-containing coating film. 2. The semiconductor device according to claim 1, wherein the dye-containing film is mixed with a titanium compound.