JPS5828828A - Chemical vapor deposition film forming apparatus - Google Patents

Abstract

PURPOSE:To easily prevent contamination of semiconductor substrate by particles of by-product generated at the upper surface of susceptor with simple structure in regard to a CVD film forming apparatus for forming the oxide film (SiO2) and nitride film (Si3N4) and polycrystalline silicon film (Poly-Si) etc. on the semiconductor substrate such as silicon wafer with the chemical vapor deposition (CVD) method. CONSTITUTION:The aluminum plate 3 is fitted by screw on the resistor heating type heater block 1 and the quartz plate 6 which provides the same thermal expansion coefficient as that of deposited oxide film and the thickness of several millimeters is further formed thereon at the specified position. The susceptor is formed in the double layers with the aluminium plate 3 and quartz plate 6, the wafer 4 is formed on such susceptor. This susceptor depositing the wafer is sent under the laminer flow nozzle 5 spraying the reaction gas for generating SiO2 and thereby the oxide film is deposited on the wafer 4 and quartz plate 6 by the chemical vapor deposition. Since the thermal expansion coefficients of the deposited SiO2 and said quartz plate 6 are almost equal, any distortion is not applied on the deposited SiO2 and generation of particles of SiO2 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an oxide film (SiO) or a nitride film (S1) on a semiconductor substrate such as a silicon wafer in the manufacturing process of a semiconductor device.
This relates to a CVD film forming apparatus for forming materials such as 3N4) and polycrystalline silicon (Poly-Si) by chemical vapor deposition (CVD). It is an object of the present invention to easily prevent the semiconductor substrate from being contaminated by particles.

In the conventional CVD film forming apparatus (hereinafter abbreviated as the apparatus),
For example, a susceptor for holding a semiconductor substrate (hereinafter abbreviated as wafer) such as a silicon wafer and heating it to a predetermined temperature, and a susceptor provided opposite to the susceptor for supplying source gas and gear gas to the surface of the wafer. There is a device with a structure having a nozzle.

A commonly used device of this type will be explained with reference to FIG.

As shown in FIG.
A wafer 4 is installed on a metal substrate of a hot plate, for example, generally an aluminum substrate 3 (hereinafter abbreviated as an Al plate), which is fixed by screws 2 to the soil of a heater block 1 in which a heater 8 is buried. . Here Si
Silane gas (SiH) that generates O2, oxygen gas (O2
) and the like are ejected from a laminar flow nozzle 5 consisting of a plurality of slit-shaped nozzles together with gear gas (N2) via pipes S and O, respectively. When the susceptor in which the wafer 4 is heated and supported is passed under the nozzle 5, an oxide film is deposited on the wafer 4 and the Al plate 3 by chemical vapor deposition.

However, since the Al plate 3 has a high thermal conductivity, it can heat and support the wafer 4 well, but since there is a large difference in thermal expansion coefficient from the estimated SiO2, it is difficult to cool the Al plate 3 after the estimation. Due to the thermal disturbance, the deposited SiO2 layer on the Al plate 3 is strained and cracked, and SiO2 particles having a size of several microns to several tens of microns are generated. From this, if we repeat the estimation, the entire surface of the Al plate 3 will be covered with the SiO2 particles. Then, for the purpose of estimating a predetermined oxide film thickness, when the wafer 4 is placed on the Al plate 3 covered with the SiO2 particles, the SiO2 particles attached to the susceptor are removed from the Ueno-4. They are caught on the edges or thrown up by the reaction gas, and adhere to and stain the surface of the oxide film on the wafer 4.

When an oxide film contaminated in this way is applied to the manufacturing process of a semiconductor device, the particles become defects or foreign matter in the oxide film, making it impossible for the oxide film to perform its intended function, resulting in pattern defects, etc. of the semiconductor device. This has a significant impact on yield and quality.

Furthermore, if the cumulative amount of SiO2 deposited on the Al plate 3 increases, the Al plate 3 is periodically cleaned with an etching solution of SiO2. This is dangerous work that involves radical chemical reactions with aluminum (Ae).

The purpose of this project is to provide an apparatus that eliminates the above-mentioned problems that plague the conventional method, prevents the generation of SiO2 particles, and deposits an oxide film with a uniform thickness. An embodiment thereof will be described below with reference to the drawings.

An embodiment of the present invention is shown in FIG. 2. In this way, the Ae plate 3 is fixed to the top of the heater block 1 for resistance heating with screws 2, and the oxide film and heat Quartz plates 6 having a thickness of several mm and having substantially equal expansion coefficients are stacked at a predetermined position.

In this way, the susceptor is constructed in two layers with the Al plate 3 and the quartz plate 6, and the wafer 4 is placed on the top of the susceptor, and the SiO
An oxide film is deposited on the wafer 4 and the quartz plate 6 by chemical vapor deposition by passing the oxide film under the laminar flow nozzle 5 which blows out a reaction gas that generates 2.

In this case, S deposited on the quartz plate 6 other than on the wafer 4
Even when a thermal disturbance occurs due to cooling of the susceptor, the estimated coefficient of thermal expansion of SiO2 is almost equal to that of the quartz plate 6, so no strain is added to the deposited SiO2 layer, and the SiO2 particles can be prevented from occurring. Note that in FIG. 2, heaters, S, and O are the same pipes as in FIG. 1.

Note that, as in the above embodiment, the Al plate 3, which has a higher conductivity than quartz, is inserted between the quartz plate 6 and the heater block 1 for heating and maintaining it, so that the heater block 1 The heat can be efficiently and uniformly conducted to the stone pod plate 6 to maintain a uniform temperature distribution, which prevents the generation of SiO2 particles and facilitates the estimation of an oxide film with a uniform thickness. .

In addition, to remove the accumulated SiO2 on the quartz plate 6, it is sufficient to periodically etch and clean only the quartz plate 6 using a hydrofluoric acid (HF) etching solution. It is easy to maintain the equipment and the maintenance of the equipment is saved.

In this example, the case where a CVD oxide film (SiO2) was formed was explained, but other CVD nitride films (Si3
In the case of forming a film such as N4) or a CVD polycrystalline silicon film (Poly-8i), the same effect can be obtained by providing a plate having approximately the same coefficient of thermal expansion as the film body.

As is clear from the description of the above embodiments, the present invention easily prevents the semiconductor substrate from being contaminated by reaction product particles.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a conventional chemical vapor deposition film forming apparatus;
The figure is a sectional view of a chemical vapor deposition film forming apparatus which is an embodiment of the present invention. 1...Heater block, 2...Screw, 3...Aluminum substrate, 4...Semiconductor substrate, 5...Lamina flow nozzle ,6・
...Quartz plate.

Claims (3)

[Claims] (1) The substrate holding part of the susceptor for holding and heating the semiconductor substrate on which the chemical vapor deposited film is to be formed is made of a member having a coefficient of thermal expansion approximately equal to that of the deposited film. A chemical vapor deposition film forming device characterized by: (2) The chemical vapor deposition film forming apparatus according to claim 1, characterized in that a good thermal conductor is interposed between the member constituting the holding surface and the heating section. (3) The chemical vapor deposition film forming apparatus according to claim 1, wherein the member constituting the holding surface is made of quartz.