JPH098037A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE: To deposit a flat film on an irregular board and make a board surface flat only by a deposition process by casting a lamp beam of a specified wavelength on a semiconductor board and forming a relatively thick film is recessed part when compared to a projecting part by a CVD method while raising a board temperature of a recessed part when compared with a projecting part. CONSTITUTION: A lamp beam of a specified wavelength is cast on a semiconductor board wherein a projecting part A and a recessed part B are formed and a relatively thick film 6 is formed in the recessed part B when compared with the projecting part A by a CVD method while raising a board temperature of the recessed part B when compared with the projecting part A. For example, a silicon oxide film 6 which becomes a layer insulation film is formed by vacuum chemical vapor growth method by lamp heating on an irregular semiconductor board with a step of 600nm by using silane gas and nitrogen suboxide gas as raw gas. In the process, a maximum strength wavelength of the lamp beam is set for 1.2μm and the recessed part B is heated so that its temperature is higher than that of the projecting part A, and the silicon oxide film 6 is deposited about 1000nm thick in the recessed part B and about 400nm thick in the projecting part A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a semiconductor device in which a flat insulating film or a polycrystalline silicon film is formed on a substrate having unevenness by using lamp heating.

[0002]

2. Description of the Related Art As the degree of integration of LSI has increased, it has become necessary to stack wiring in multiple layers. However, in order to prevent disconnection at the step portion of each wiring, a technique for flattening an interlayer insulating film is required. ing.

Conventionally, as a method of flattening an interlayer insulating film, so-called reflow is performed in which phosphorous glass (phosphorus-doped silicon oxide film) is deposited at a low temperature and the substrate surface is smoothed by utilizing viscous flow due to subsequent high temperature heat treatment. Or a so-called CMP (Chemical Mechanical) method for flatly polishing an uneven interlayer insulating film as shown in FIG.
The chemical polishing method is used.

In the planarization method of the interlayer insulating film using the CMP method, first, as shown in FIG. 5A, a first electrode as a lower electrode of a capacitor is formed on a silicon substrate 1 on which a silicon oxide film 2 is formed. A polycrystalline silicon film 3, a capacitive insulating film 4, and a second polycrystalline silicon film 5 as an upper electrode are formed. Next, as shown in FIG. 5B, a silicon oxide film 6A having a film thickness equal to or larger than the step of the unevenness is deposited on the substrate having such unevenness, and thereafter, as shown in FIG. The silicon oxide film 6A is polished flat by the CMP method.

On the other hand, in Japanese Unexamined Patent Publication No. 1-91441, laser light is used as a heat source and a mask is used in which a pattern is drawn so that the laser light is incident only on the concave portion of the substrate. A method is used in which a thin film is selectively deposited only on the concave portion, and then a thin film is deposited on the entire surface of the substrate by lamp light CVD, thereby performing planarization.

[0006]

However, the above-mentioned conventional techniques have the following problems, respectively. First, the reflow method using phosphor glass requires a high temperature of about 800 ° C. as a reflow temperature. In a semiconductor device whose design rule is submicron or less, it is necessary to make the junction depth of the source and drain extremely shallow in order to suppress the short channel effect of the field effect transistor. When the high temperature reflow process that causes the thermal diffusion of arsenic and boron) occurs, there is a problem that it is impossible to suppress the short channel effect. Further, there is a problem in that the manufacturing cost increases because two steps, that is, the step of depositing the interlayer insulating film and the reflow step are required.

Further, in the CMP method, since the polishing step can be performed at room temperature, there is no problem of thermal diffusion of the dopant which is a problem in the above-mentioned reflow step, but substrate damage or dust generation which may occur in the polishing step. There was a problem. Further, since it includes two steps, that is, the step of depositing the interlayer insulating film and the step of polishing, there is a problem that the manufacturing cost is increased like the reflow step described above.

Further, Japanese Patent Laid-Open No. 1-91 which uses laser light.
In the method of No. 441, since a mask in which a pattern is drawn so that laser light can be irradiated only on the concave portion of the substrate,
High-precision technology equivalent to that of exposure equipment such as steppers is required. Further, since the laser beam is swept for each silicon substrate, the number of processed wafers per unit time becomes extremely small. These give rise to the problem of increased manufacturing costs.

In view of the above problems, it is an object of the present invention to provide a method for manufacturing a semiconductor device which solves these problems and has a reduced manufacturing cost.

[0010]

According to a method of manufacturing a semiconductor device of the present invention, lamp light having a predetermined wavelength is irradiated onto a semiconductor substrate having a convex portion and a concave portion so that the substrate temperature of the concave portion is higher than that of the convex portion. However, it is characterized in that a relatively thick film is formed in the concave portion as compared with the convex portion by the CVD method.

[0011]

Next, embodiments of the present invention will be described with reference to the drawings. 1A and 1B are sectional views of a semiconductor chip for explaining an embodiment of the present invention.

First, as shown in FIG. 1A, a silicon oxide film 2 having a film thickness of 200 nm and a patterned first film having a film thickness of 600 nm to be a lower electrode of a capacitor are formed on a silicon substrate 1.
Polycrystalline silicon film 3 and this first polycrystalline silicon film 3
Then, a capacitive insulating film 4 having a thickness of 5 to 10 nm and a second polycrystalline silicon film 5 having a thickness of 200 nm as an upper electrode are formed so as to cover the. In this case, the step between the concave portion B and the convex portion A on the silicon substrate is 600 nm. Further, in the present invention, there is no limitation on the dimension of the pattern and the dimension between the patterns.

On a semiconductor substrate having such irregularities,
The silicon oxide film that becomes the interlayer insulating film by heating the lamp,
For example, low pressure chemical vapor deposition is performed using silane gas and nitrous oxide gas as source gases. At this time, the maximum intensity wavelength of the lamp light is set to 1.2 μm, and the concave portion B on the silicon substrate 1 is formed into the convex portion A. Heat to a higher temperature than
By depositing a silicon oxide film 6 having a film thickness of about 1000 nm on the concave portion B and depositing a silicon oxide film 6 having a film thickness of about 400 nm on the convex portion A, as shown in FIG. Turn into.

The principle of film formation capable of achieving such flattening will be described with reference to FIG. When the semiconductor substrate is heated by lamp light, the substrate temperature depends on the reflectance of the substrate surface,
In particular, the lamp light largely depends on the reflectance at the wavelength where the intensity is maximum. When a pattern is drawn on the semiconductor substrate, the reflectance is different inside and outside the pattern, and it is difficult to heat because the absorption amount of light is small in the area with high reflectance, and conversely, the absorption of light in the area with low reflectance Due to the large amount, it is easily heated. In addition, since the reflectivity greatly changes depending on the wavelength and the film thickness / film structure, it is possible to select a wavelength such that the reflectivity at the concave portion on the semiconductor substrate becomes small and the reflectivity at the convex portion becomes large. Is. Therefore, by setting the lamp light so as to maximize the light intensity at the wavelength as described above and heating the semiconductor substrate having irregularities, the substrate temperature is made relatively high at the concave portions and relatively low at the convex portions. It becomes possible.

FIG. 2 shows the results of obtaining the wavelength dependence of the light reflectance in the convex portion A and the concave portion B of the silicon substrate shown in FIG. 1 (a). In the wavelength range from about 1.15 to 1.3 μm, the reflectance of the convex portion A is higher than that of the concave portion B. Even if a silicon oxide film is deposited on the convex portion A and the concave portion B to a thickness of about 1000 nm, the change in the reflectance is small and the magnitude relationship between the convex portion A and the concave portion B is not reversed. I understand. Therefore, about 1.2μ
By heating the silicon substrate with the lamp light such that the wavelength of m becomes maximum intensity, the silicon oxide film 6 is formed while maintaining the temperature of the concave portion B higher than that of the convex portion A. Can be deposited. Since the deposition rate by the low pressure chemical vapor deposition largely depends on the growth temperature, it is possible to deposit a relatively thin silicon oxide film on the convex portion A and a relatively thick silicon oxide film on the concave portion B.

A predetermined wavelength, that is, 1. in the embodiment.
In order to obtain a lamp light of 2 μm, for example, as shown in FIG. 3, a halogen lamp 13 is provided on a chamber 11 having a source gas introduction pipe 14, and a wavelength of 1.2 μm is provided between the lamp 13 and the silicon substrate 1. The interference filter 12 that transmits the light is provided. This interference filter selectively transmits only light in a specific wavelength range by utilizing the interference of light from a thin film, and is made of a non-metal multi-layer film or a metal-non-metal multi-layer film by a vacuum deposition method or the like. Is possible.

Further, as shown in FIG. 4, the halogen lamp 13
The light 15 of A may be split by the spectral prism 16. Halogen lamp light 15 has a peak at a wavelength of 1 μm,
Although it spreads to 3 μm, the lamp light 15 is irradiated to the spectral prism 16, and the transmitted light 15A is transmitted to the slit plate 1.
The silicon substrate 1 is irradiated via 7. By changing the relative angle between the lamp light 15 and the spectral prism 16, only the light having the desired wavelength can be irradiated onto the silicon substrate 1. The silicon substrate 1 may be moved in the horizontal direction in order to irradiate the lamp light uniformly.

In the above embodiment, the case where the silicon oxide film 6 is deposited as the interlayer insulating film by the low pressure chemical vapor deposition by the lamp heating has been described. However, other insulating films such as a silicon nitride film and a silicon oxynitride film, A polycrystalline silicon film or the like may be deposited by using lamp light having an appropriate wavelength.

In the above embodiment, the thin film is deposited by low pressure chemical vapor deposition by lamp heating. However, if lamp heating is used as the thin film forming method, atmospheric pressure chemical vapor deposition method or thermal oxidation method is used. Alternatively, a thermal nitriding method, a thermal oxynitriding method, or the like may be used.

Further, although the formation of the interlayer insulating film has been described in the above embodiment, the method of the present invention is not limited to this, and a step of depositing a flat film on a substrate having irregularities, such as embedding an insulating film in trench element isolation. Can be applied to.

[0021]

As described above, according to the present invention, the semiconductor substrate is heated by irradiating the lamp light of the predetermined wavelength,
By depositing a relatively thick thin film on the concave portion of the substrate and a relatively thin thin film on the convex portion of the substrate, it becomes possible to deposit a flat film.

Moreover, since the substrate surface can be flattened only by the deposition process, the process is simplified and the manufacturing cost can be reduced. Further, since a reflow process is not required, there is no need for high temperature reflow heat treatment. Therefore, thermal diffusion of the dopant atoms in the substrate can be reduced, so that the source / drain junction depth can be made shallow, and the device can be miniaturized and highly integrated. Further, since there is no need for the CMP process, it is possible to avoid the problems of substrate damage and dust generation that may occur in the polishing process. Further, by applying the method to the formation of the interlayer insulating film of the multi-layered wiring, it is possible to prevent disconnection of the upper wiring. In addition, the high integration of the device can be achieved by realizing the multilayer wiring. As described above, the present invention greatly contributes to high integration of elements, improvement of reliability, and reduction of manufacturing cost.

[Brief description of drawings]

FIG. 1 is a sectional view of a semiconductor chip for explaining one embodiment of the present invention.

FIG. 2 is a diagram showing the relationship between the wavelength of light and the reflectance for explaining the principle of film deposition in the present invention.

FIG. 3 is a configuration diagram of a lamp heating type film forming apparatus used in Examples.

FIG. 4 is a configuration diagram for explaining separation of lamp light used in an embodiment.

FIG. 5 is a cross-sectional view of a semiconductor chip for explaining a conventional example.

[Explanation of symbols]

 1 Silicon Substrate 2 Silicon Oxide Film 3 First Polycrystalline Silicon Film 4 Capacitance Insulating Film 5 Second Polycrystalline Silicon Film 6,6A Silicon Oxide Film 11 Chamber 12 Interference Filter 13,13A Halogen Lamp 14 Gas Inlet Tube 15 Lamp Light 16 Spectral prism 17 Slit plate

Claims (1)

[Claims] 1. A semiconductor substrate on which a convex portion and a concave portion are formed is irradiated with a lamp light of a predetermined wavelength, and the substrate temperature of the concave portion is increased as compared with the convex portion by a CVD method, so that the concave portion is relatively comparatively compared with the convex portion. A method of manufacturing a semiconductor device, which comprises forming a thick film.