JPH01181533A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To prevent an occurrence of cracks to an insulating film by forming an insulation layer that covers a step on a substrate having a step, and by exposing an insulation layer to a gas plasma containing either nitrogen or O-based elements. CONSTITUTION:A first plasma CVD-SiO2 film 2 is formed on a substrate 6 in which wiring 1 is formed. On the entire surface of the substrate in which this film 2 is formed, an apply film forming solution is applied. The solution is evaporated, and a silicate-based compound film 3 is left on the substrate as an applied film. Following this, for example, hardening processing is performed in an oxygen plasma to form a silicate-based compound film 3a, and further a second plasma CVD-SiO2 film 4 is formed as an insulation film between layers. On it, wiring 5 is formed. Exposing insulation layers 2. 4 whose steps are coated to plasma enables the surfaces of insulation layers 2, 4 to be planarized at low temperatures, and for a hardening processing of the applied film 3, reaction can the promoted in a plasma at a low temperature. This makes it possible to prevent occurrences of cracks to an insulation layer or line disconnections of a wiring layer.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention relates to a method of manufacturing a semiconductor device, and in particular, the present invention relates to a method for manufacturing a semiconductor device, and in particular, a method for flattening an insulating film covering a stepped portion such as a wiring formed on a substrate. Regarding the method.

(Prior Art) In manufacturing a semiconductor device, an insulating film is usually formed on a semiconductor element or wiring to maintain insulation from other regions. In this case, the wiring and semiconductor elements are usually
Since there are steps, the surface of the insulating film covering the wiring and the semiconductor element becomes uneven. Among the irregularities of the insulating film, particularly at the corners, more stress is applied than to other parts, which may cause problems such as cracks in the insulating film and failure to maintain insulation properties.

This problem is particularly noticeable in multilayer wiring structures that have been used in recent years as semiconductor devices have become larger in capacity and more highly integrated. That is, when forming a semiconductor device with the multilayer interconnection structure, wiring layers and interlayer insulating films are repeatedly laminated, and due to the repetition, steps become steep, and a large amount of physical stress is applied to the insulating film. Furthermore, in some cases, disconnection may occur in the wiring.

In order to avoid the above-described problem, the uneven surface of the insulating film is flattened to prevent physical stress from occurring in the insulating film. As the flattening method, resist etching back method and bias sputtering method are mainly used. However, the former method has become difficult to control as semiconductor devices become smaller and smaller, and the latter method has the drawback of damaging the device.

Therefore, as a method different from the above two methods, a method of flattening the step by a coating method using fluidity of a liquid has become popular.

The coating film formed by the above-mentioned coating method is obtained by coating wiring and semiconductor elements with an insulating film, then spin-coating a coating film-forming solution in which a silicon compound is dissolved in a solvent onto the insulating film, and then removing the solvent by heat treatment. The film is formed by volatilizing it and then curing the film.

However, the heat treatment cannot be carried out at high temperatures in view of the effects on semiconductor elements and the like, and the solvent is not sufficiently volatilized. Therefore, there are problems with moisture resistance, such as the moisture contained in the coating film reacting with residual elements of the gas used in the etching process and corroding the wiring or semiconductor elements.

For this reason, the TA layer structure is not used alone as an interlayer insulating film, but rather has a TA layer structure in which a coated film such as a bladder CVD 1ffl film/coated film/plasma CVD insulating film is sandwiched between other insulating films. The thermal expansion coefficients (α) of the coated films are different, and in particular, when the wiring layer is an aluminum alloy and the insulating film is an SiO2 film formed by plasma CVD, the coefficients of thermal expansion (α) differ by two digits. Therefore, even if an interlayer insulating film with a laminated structure is formed, thermal stress is generated between the wiring layer and the insulating film during heat treatment to harden the coating film, which may cause cracks in the insulating film, which poses a problem. ing.

(Problems to be Solved by the Invention) The present invention provides that, in the above-described conventional method of covering wiring or semiconductor elements with an insulating film, the unevenness of the insulating film is flattened,
Moreover, this was done in view of the problem that cracks may occur in the insulating film. That is, the present invention provides a semiconductor device in which an insulating film covering a stepped portion such as a wiring layer and a coating film formed on this insulating film are formed at a low temperature to prevent cracks from occurring in the insulating film. The purpose is to provide a manufacturing method.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention provides a step of forming an insulating layer covering at least the stepped portion on a substrate having a stepped portion on the surface; A method of manufacturing a semiconductor device is provided, which includes a step of exposing a layer to a gas plasma containing oxygen, nitrogen, or an O group element.

(Function) According to the present invention, by exposing the insulating layer covering the stepped portion to plasma, the surface of the insulating film can be flattened at a low temperature, and no cracks will occur in the insulating film.

In addition, the hardening treatment of the coating film can accelerate the reaction in plasma at low temperatures, making it possible to improve moisture resistance.

For example, when the coating film is a silicon compound such as Si(OH)4, a dehydration condensation reaction occurs between 5i-OH-0H-8t, and the 5t-0-3i network is widened to increase the effectiveness of the coating film. As this progresses, moisture resistance can be improved. In this case, the processing temperature is 400°C or higher for the heat treatment to be effective (in this case, cracks occur in the insulating film); can be done. Further, since stress is not applied to the wiring, there is no possibility of disconnection.

This means that when the coating film is exposed to plasma, Si
This is because -OH or O-H bonds are activated by plasma energy and are highly reactive.

Therefore, according to the present invention, a coating film with good flatness and moisture resistance can be formed at low temperatures. Moreover, this prevents cracks from occurring in the insulating layer or disconnection from the wiring layer.

(Example) Hereinafter, an example of the present invention will be described in detail using the drawings. FIG. 1 is a sectional view of the process.

First, as shown in FIG. 1(a), the first
A plasma vcVD-8LO2 film (2) is formed. Next, as shown in FIG. 1(b), the plasma CVD-8i0
2. A coating film forming solution containing a silicate compound is applied to the entire surface of the substrate on which the film (2) is formed, and then the solvent of the coating film forming solution is evaporated under reduced pressure to form a silicate compound curtain (3) as a coating film. Leave it on the board. Here, as the coating film forming solution, a solution in which a silicon compound is dispersed or dissolved in a solvent can be used. Subsequently, as shown in FIG. 1(C), a silicate compound film (3a) which has been hardened in oxygen plasma is formed. Here, after the silicate compound film (3a) is formed, it may be etched to make the entire surface more flat.

Furthermore, although this example shows an example in which the silicate compound film (3) is entirely cured, the effect can also be obtained by curing only the surface of the coating film such as the silicate compound film (3).

In this case, the substrate temperature is 300"C1, the oxygen pressure is I Torr
.

By plasma treatment for 30 minutes, the coating film has a depth of about 20 mm from its surface.
We were able to maintain tightness until 00A. In particular, since the thickness of the coating film on the protrusions was about 500 Å, the coating film on the protrusions was extremely well modified.

Furthermore, as shown in FIG. 1(d), the second plasma CVD-8
An i02 film (4) is formed as an interlayer insulating film, and an (n+1)th aluminum wiring (5) as shown in FIG. 1(e) is further formed thereon.

The n-th aluminum wiring (1
) is a line and space pattern with an aluminum width of 2μ, a space width of 2μ■, and an aluminum thickness of 1μ, and '! B1 plasma CVD-3i02 film (2) film thickness 0
．． The coating film (
3), the first plasma CVD-5i02
The incidence of cracks in film (2) was 30%.

After that, the substrate temperature was further increased from room temperature to 300°C, and the oxygen pressure was
When the coating film (3) is cured by oxygen brosma treatment with TorrSRF power of 800W and treatment time of 60 minutes,
No cracks occur in the CVD-3i02 film (2).

It is desirable that the film quality of the coating film formed according to the present invention be as close as possible to the first or second insulating film in order to suppress the influence of stress generated between the coating film and the first or second insulating film.

In order to compare the film quality, the etching rates of both films were investigated and the results will be explained below.

Figure 2 shows the coating film when the substrate temperature is changed during the hardening treatment of the coating film ((^) heat treatment, (B) plasma treatment)
and plasma CVD-8io2 film (C).

Here, the plasma treatment is performed in an oxygen (O2) atmosphere,
Oxygen pressure I Torr, RF output 800Wll! The processing conditions were 60 minutes. In addition, plasma CVp-S
The etching rate of the i02 film was almost constant regardless of the substrate temperature, and it was found that when the substrate temperature was around 300°C, the etching rates of both were almost the same.

Furthermore, when comparing the etching speed after hardening of the coating film when heat treatment is performed (A) and when plasma treatment according to the present invention is performed (B), for example,
The etching rate at 00''C was almost the same as when the heat treatment was performed at 600°C or higher.

For these reasons, coating films cured by plasma treatment are better than those cured by heat treatment by plasma CVD.
It is inferred that the film quality is close to that of the -8i02 film.

Furthermore, from FIG. 2, it can be seen that the etching rate of the coating film subjected to plasma treatment is slower than that of the case of ordinary heat treatment at the same substrate temperature, and the film is denser. Therefore, it can be seen that, at the same substrate temperature, plasma treatment has lower hygroscopicity than heat treatment.

This became clear by using a mass spectrometer to measure the relative amount of water released when the coating film was heated after immersing the coating film in boiling water for about 30 minutes.

That is, the substrate temperature is 300°C and the oxygen pressure is I Torrs.
The coating film formed under the conditions of RF, 800 W, and 60 minutes of processing time was comparable to the plasma CVD-5i02 film, and its hygroscopicity was significantly improved to about 1/10 compared to the film cured by heat treatment.

In the above embodiments, the coating film was exposed to oxygen plasma, but the same effect can be obtained by exposing it to oxygen, nitrogen, or gas plasma containing Group 0 elements such as argon, helium, and neon. Further, the coating film forming solution may be any material as long as it hardens when exposed to plasma, but preferably one containing silicon (SL) and oxygen (0).

Further, if the substrate is subjected to heat treatment immediately before or while the coating film is exposed to plasma, the time for curing treatment can be shortened and throughput can be improved.

Further, in the above embodiment, an example of an insulating film having a silicate compound film formed on the surface was used as the coating film, but in the present invention, a chemical vapor phase coating using an organosilicon compound such as tetraethoxysilane (TEOS) as a raw material is used. It also includes a case where a thin film is formed by a growth method and an insulating film in which organic groups such as 5i-R (alkyl group) and 5t-OR (alkoxy group) are present is modified. For example, using TEOS as a raw material, plasma C
In the VD method, the substrate temperature increases to ~
When a film is deposited at a low temperature of 400° C., ethoxy groups and organic groups as side reaction products remain in the film. In this case, film deposition and film modification by plasma treatment are performed alternately. As in the above example, it is possible to form a dense film with no organic groups in the film by repeating film deposition and modification of the film by plasma treatment until a predetermined film thickness is achieved while completely removing organic groups. can.

Further, in the above embodiment, a wiring pattern is formed on the substrate as a substrate having a stepped portion on the surface. can also be applied.

[Effects of the Invention] As described above, according to the present invention, it is possible to flatten the surface of the insulating layer covering the stepped portion of the wiring of the substrate at a low temperature, thereby reducing the influence on the insulating layer or the wiring during the process. Can be suppressed.

[Brief explanation of the drawing]

Fig. 1 is a process sectional view showing one embodiment of the present invention;
The figure is a characteristic diagram for explaining the present invention in detail. 1.5... Wiring, 2... First insulating layer, 3...
... Coating film, 4... Second insulating layer, 6...
substrate.

Claims (3)

[Claims] (1) A step of forming an insulating layer covering at least the step portion on a substrate having a step portion on the surface, and a step of exposing the insulating layer to a gas plasma containing oxygen, nitrogen, or an O group element. A method for manufacturing a semiconductor device, including: (2) forming a first insulating layer covering at least the step portion on a substrate having a step portion on the surface; forming a coating film on the first insulating layer; and forming a coating film on the first insulating layer; A claim comprising the steps of: planarizing the surface of the substrate on which is formed; thereafter, exposing at least the coating film to plasma; and forming a second insulating layer on the planarized coating film. Item 1. A method for manufacturing a semiconductor device according to item 1. (3) A step of forming an insulating layer covering at least the step portion on a substrate having a step portion on the surface by gas decomposition in a gas phase, and a step of exposing at least the surface of the insulating film to plasma. A method of manufacturing the semiconductor device described above.