JPS60132344A - Semiconductor device - Google Patents

Abstract

PURPOSE:To improve the productivity subject to excellent flatness producing no dirts at all by a method wherein, in a semiconductor device with multilayered wiring structure, an interlayer insulating film covering a metal wiring is composed of three layer films comprising the first insulating skin film, a liquefied oxide film as the second insulating film and the third insulating film. CONSTITUTION:A flattened semiconductor device with multilayered wiring structure is composed of an insulating film 2 formed on a silicon substrate 1, a wiring metal 3 such as aluminium, the first insulating film 4 formed by CVD growing process, plasma process etc. a liquefied oxide film as the second insulating film 8, the third insulating film 6 formed by CVD growing process etc. and a surface wiring 7. Through these procedures, the liquefied oxide film 8 may be made thicker upon the lower layered metal wiring 3 to prevent a crack from happening since the first insulating film 4 is formed preventing the lower layered metal wiring 3 from directly sticking to the liquefied oxide film 8. Besides, any gas etc. released from the dioxide silicon film 7 may be minimized since the liquefied oxide film 8 is covered with the third insulating film 6.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a semiconductor device, and more particularly to a semiconductor device with a flattened multilayer wiring structure.

(Prior Art) The need for semiconductor devices to have a flat structure arises mainly to prevent wire breakage in multilayer wiring structures, and various techniques have been put into practical use.

One such technique is the technique of applying a liquefied oxide film. This technology uses a spin code to apply a mixture containing liquid 7-licon dioxide onto a wafer, and then bakes the wafer surface, which flattens the wafer surface with the remaining silicon dioxide film and prevents disconnections in the wiring layer formed on top of it. Become.

This method has the advantage of being simpler than other methods such as quenching or bias sputtering.

However, the method using the liquid silicon dioxide film has the following drawbacks.

(1) When a silicon film is formed directly on a wiring layer such as aluminum, the silicon dioxide film near the wiring layer becomes too thick, resulting in cracks, shorting the upper layer wiring, and losing its function as an insulating film. There is a drawback.

(2) When depositing upper layer wiring such as aluminum on a silicon dioxide film formed from liquid silicon dioxide,
Unless the deposition conditions are restricted, a problem arises in that the reliability and productivity of the semiconductor device are reduced.

For example, in recent years aluminum has been deposited by sputtering due to its strength against electromigration, and in this case, it is necessary to perform reverse sputtering on the semiconductor substrate surface immediately before aluminum sputtering to improve through-hole conductivity. , it is necessary to heat the semiconductor substrate in order to maintain uniform film quality such as coverage and duplex size for the step difference in aluminum that flops.

When such a process is applied, gas (mainly hydrogen gas) is released from the silicon dioxide film formed by the liquefied oxide film coating method. For this reason, the degree of vacuum in the sputtering apparatus decreases, and the sputtered aluminum film in this state is not preferable because it adversely affects the quality of the semiconductor device, such as electromer 4 crease stains and step coverage. Furthermore, the gas release causes severe contamination within the device, which increases the frequency of cleaning the device, resulting in a decrease in productivity.

(3) In the liquefied oxide film coating method, a mixture of an alcohol solvent and silanol, etc. is usually spin coated) Ll, 400-4
A silicon dioxide film is formed by betaening at a temperature of 50'C, and the composition of the liquefied oxide film mixture is 90%.
Since the above solvents are alcohol-based solvents, they tend to dry easily, and the silanol and the like become a source of dust, so there are problems in that sufficient care must be taken when handling them, including the coating equipment.

(Objective of the Invention) An object of the present invention is to provide a semiconductor device having a multilayer interconnection structure which is free from the problem of deterioration in quality and yield due to the generation of dust, has good flatness, and has excellent productivity.

(Structure of the Invention) A semiconductor device of the present invention is a semiconductor device having a multilayer wiring structure, wherein an interlayer insulating film forming the multilayer wiring structure is formed on a first insulating film and the first insulating film. It has a three-layer structure including a second insulating film with excellent surface flattening properties and a third insulating film formed on the second insulating film.

(Example) Examples of the present invention will be described below with reference to the drawings.

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

In FIG. 1, 1 is a silicon substrate on which various elements have been formed after ion implantation or diffusion of impurities and other processes, 2 is an insulating film formed on the surface of the silicon substrate,
For example, it is a silicon oxide film that captures the silicon substrate l,
It also has a thickness gt-sufficient to prevent its inversion. 3 is a wiring metal such as aluminum. Also, 4 is CV
The first insulating film is formed by a D growth method, a plasma method, etc., and the thickness of the insulating film may be 500A or more.

5 is a second insulating film which is a liquefied oxide film, and 6 is C like 4.
A third insulating film 7 is formed by VD growth or the like, and 7 is an upper layer wiring formed on the third insulating film.

In this embodiment, the interlayer insulating film enclosing the metal wiring 3 is not a single layer of liquefied oxide film but a first insulating film 4. Second insulating film 8. Third
The second insulating film 8, which has a large planarizing effect, is sandwiched between two insulating films.

That is, since the first insulating film 4 is formed without directly attaching the liquefied oxide film to the lower metal wiring 3, the liquefied oxide film does not liquefy at the lower metal wiring, unlike when the liquefied oxide film is directly attached. This prevents the oxide film from becoming thick and causing cracks, which will cause poor insulation and the porosity phenomenon.

Furthermore, since a third insulating film is formed on the liquefied oxide film 8 to cover the liquefied oxide film, gas release from the silicon dioxide film formed by the liquefied oxide film coating method in subsequent processes is reduced. be able to. Further, the generation of dust from the silicon dioxide film formed by the liquefied oxide film coating method can be suppressed.

FIG. 2 is a sectional view of another embodiment of the invention.

The structure of the embodiment shown in FIG. 2 is the same as the first embodiment, but the difference is that the second insulating film 6 with excellent surface flattening properties located in the middle of the three-layer structure of the present invention is liquefied. The insulating film is not a silicon dioxide film formed by an oxide film coating method, but is made of an organic substance.

Similarly to the first embodiment, a silicon oxide film 2. Lower layer metal wiring 3. A first insulating film 4 is formed. Next, polyimide resin 5 which is an organic insulator
is coated on the first insulating film 4 using a spin code and beta-coated to form a planarized and dense film. Polyimide resin has low volatility and is dense, so there is no problem of dust generation.

Further, 6 is a third insulating film formed on the polyimide resin, which can protect the polyimide resin film and stabilize subsequent processes. Reference numeral 7 indicates an upper layer metal wiring formed on the three-layer interlayer insulating film of this embodiment, and if necessary, a first insulating film 4 and a polyimide resin 5 are formed as in the case of the upper layer metal wiring holder and the lower layer wiring. Furthermore, an insulating film may be formed on the polyimide resin 5 if necessary.

As explained above, according to the second embodiment of the present invention, it is possible to obtain a semiconductor device having a multilayer wiring structure that has better insulation and flatness than the first embodiment, and is less likely to generate gas or dust. It will be done.

Note that the first thing. As the third insulating film, a silicon oxide film or a silicon nitride film is generally used, but an alumina film can also be used. Note that even if the first and third insulating films are of the same type,
In addition, different types may be used and can be selected depending on the necessary conditions.

However, if they are of the same type, production equipment and processes can be simplified.

(Effect of the invention) As explained above, according to the present invention, like the conventional example,
There is no problem of quality or yield deterioration due to generation of dust or gas emission, semiconductor devices with good flatness, excellent electrical properties, and multilayer wiring structure can be obtained, and they are highly productive as they can be produced using normal manufacturing equipment. This effect can also be obtained.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views of embodiments of the present invention. l...Semiconductor silicon substrate, 2...Silicon oxide film, 3...Metal wiring (lower layer), 4...
...Insulating film, 5...Polyimide resin, 6
...Insulating film, 7...Metal wiring (upper layer)
, 8...Liquid oxide film. 1st peak 20

Claims (4)

[Claims] (1) In a semiconductor device having a multilayer wiring structure, an interlayer insulating film forming the multilayer wiring structure includes a first insulating film and a second insulating film having excellent surface flattening properties formed on the first insulating film. an insulating film formed on the second insulating film, and a third insulating film formed on the second insulating film.
A semiconductor device comprising a three-layer structure of insulating films. (2) The semiconductor device according to claim (1), wherein the second insulating film having excellent surface flattening properties is an insulating film made of an organic substance. (3) The semiconductor device according to claim (1) or (2), wherein the first and third insulating films are of the same type. (4) The semiconductor device according to claim (1) or (2), wherein the first and third insulating films are different types of insulating films.