JPS5941773B2 - Vapor phase growth method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a vapor phase growth apparatus for growing a thin film such as an insulating film on a substrate surface in a semiconductor device manufacturing process.

In the manufacturing process of semiconductor devices, a vapor phase growth method using plasma has been put into practical use as a method for growing a surface-protecting insulating film, such as a silicon nitride film, on the surface of a semiconductor integrated circuit wafer at a low temperature.

Such a vapor phase growth apparatus has a reaction tube 1 as shown in FIG.
A reaction gas inlet 2 and an exhaust port 3 are provided on one side of the reaction tube 1 and an exhaust port 3 is provided on the other side, a heating element 4 is provided on the outer periphery of the reaction tube 1, and plasma generation electrodes 5a and 5b are arranged facing each other inside. The electrodes are alternately connected in common, and the common connection line is connected to a high frequency power source 6 to form a reaction region T.
Note that the wafer 8 has a plasma generation electrode 5a in the reaction region 7,
5b, respectively. Monosilane (SiH4) diluted with argon (Ar), for example, is used as a reaction gas in the reaction tube 1, which is evacuated from the exhaust port 3 to reduce the pressure.
A mixed gas of NH and ammonia (NHs) is introduced from the gas inlet 2 to generate plasma in the reaction region □, thereby growing a Si3N4 film on the surface of the wafer 8. By the way, the quality of the Si3N4 film grown with such an apparatus depends on the purity of the reaction gas, the gas mixture ratio, the high frequency power, etc., and is also greatly influenced by the frequency. That is, at low frequencies (for example, 400 KH2), the tensile stress of the Si3N4 film is small and cracks are less likely to occur in the film, but there is a problem in that the adhesion to the base is poor and the moisture resistance is poor. On the other hand, when the frequency is high (for example, 13.56 MH2), although the moisture resistance is excellent, there is a problem that cracks are likely to occur. Therefore, as a means of obtaining a Si□N4 film with good film quality, the frequency of the high-frequency power source 6 may be changed from 13.56MH2 to 400MHz during film formation.
A method has also been proposed in which the film is formed by changing the frequency from KH2 to 13.56MH2 multiple times, but in such a method, as the frequency changes, the matching correction and high frequency power etc. are adjusted to suit each frequency. It must be well controlled, and complication of the equipment and film-forming process is unavoidable.

The present invention has been made in view of the above-mentioned points, and its purpose is to provide a vapor phase growth apparatus that can easily form a thin film with good film quality. In a vapor phase growth apparatus, a plasma generating section excited at a predetermined frequency is provided in a reaction tube to serve as a reaction region for film formation, and a plasma generating section excited at a predetermined frequency is installed in the reaction tube side of the reaction gas inlet of the reaction region. This is where another excited plasma generation region is located.

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

FIG. 2 is a conceptual diagram of main parts for explaining the structure of the vapor phase growth apparatus according to the present invention, and the same parts as in FIG. 1 are given the same reference numerals.

In the figure, reference numeral 1 denotes a reaction tube made of quartz, and a reaction gas inlet 2 is provided on one side of the reaction tube 1, that is, the left side in the figure, and an exhaust port 3 is provided on the other side. In addition, a heating element 4 is disposed on the outer periphery of the reaction tube 1 on the exhaust port 3 side, and plasma generation electrodes 5a and 5b are arranged facing each other inside, and these electrodes are alternately connected in common, and the common connection line is is connected to a high frequency power source 6 to constitute a reaction region 7. A wafer 8 is attached to the plasma generation electrodes 5a and 5b in the reaction area 7. Although such a configuration is the same as that of a conventional vapor phase growth apparatus using plasma, the vapor phase growth apparatus according to the present invention further includes another plasma generation region 9 disposed on the reaction gas inlet 2 side of the reaction region 7. It has been set up. The configuration of the plasma generation region 9 is such that plasma generation electrodes 11 and 12 connected to a high frequency power source 10 different from the high frequency power source 6 are arranged facing each other, and a heating element 1 is placed on the outer periphery of the reaction tube 1 on the gas inlet 2 side.
3 is installed. Naga plasma generation electrodes 11, 12
is made of mesh-like aluminum (A), for example. In such a configuration, the wafer 8 is attached to the plasma generation electrodes 5a and 5b in the reaction region 7, and the pressure inside the reaction tube 1 is reduced by exhausting air from the exhaust port 3. Then, a reactive gas is introduced into the reaction tube 1 from the reactive gas inlet and caused to flow between the plasma generation electrodes 11 and 12, and plasma is generated in the plasma generation region 9 by the high frequency electric field applied between these electrodes. The reaction gas is excited in advance at the frequency of the high frequency power source 10 and then allowed to flow into the reaction region 7. Further, the pre-excited reaction gas is applied to the reaction region 7 and then excited at the frequency of the high-frequency power source 6 applied between the plasma generation electrodes 5a and 5b to remove the wafer 8.
A thin film is grown on the surface. At this time, high frequency power supply 1
By selecting and setting the frequency, high frequency output, etc. of the 0 and 6 hexagrams under different conditions, the conventional reaction area 7
Substantially the same effect as in the case where the frequency of the high frequency power source 6 applied between the plasma generating electrodes 5a and 5b is changed during film formation can be obtained. As a result, a thin film of good quality was deposited on the wafer 8.
It can be grown on the surface. Now, to describe the specific conditions for growing, for example, a Si3N4 film on the surface of the wafer 8, first, after reducing the pressure inside the reaction tube 1,
The heating element 4 is controlled to set the temperature in the reaction region 7 to, for example, about 400°C, and the heating element 13 is used to lower the temperature of the plasma generation region 9 than the temperature of the reaction region 7 (for example, from room temperature to 300°C) setting. In addition, the high frequency power supply 10 has a frequency of 13.56 MHz and 1 output of 200, for example.
W to 1KW, and the high frequency power supply 6 has a frequency of 400K, for example.
The Hz1 output is set to about 0.5 W/wafer, and a mixed gas of SiH4 and NH3 diluted with Ar, for example, is flowed from the reaction gas inlet 2 at a pressure of about 0.5 to 1 T0rr and onto the surface of the wafer 8. Grow a Si3N4 film. The Si3N4 film grown under these conditions has excellent moisture resistance and is free from cracks. In the above-mentioned embodiment, a reaction gas inlet 2 and an exhaust port 3 were provided at both ends of the reaction tube 1, and one plasma generation region 9 was provided on the reaction gas inlet 2 side of the reaction region 7. I mentioned the case,
The plasma generation region is not limited to one. For example, an exhaust port and a reaction region are configured near the center of the reaction tube, and reaction gas inlets are provided at both ends of the reaction tube, and the reaction region and each reaction gas are introduced. Of course, it is also possible to arrange plasma generation regions between the mouth and the mouth.

As is clear from the above description, according to the present invention, a thin film with excellent film quality can be easily grown on the surface of a semiconductor wafer, and it greatly contributes to the improvement of semiconductor device manufacturing technology.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram of main parts for explaining the structure of a conventional vapor phase growth apparatus, and FIG. 2 is a conceptual diagram of main parts for explaining the structure of a vapor phase growth apparatus according to the present invention. DESCRIPTION OF SYMBOLS 1... Reaction tube, 2... Reaction gas inlet, 3... Exhaust port, 4, 13... Heating element, 5a, 5b, 11, 12
... Electrode for plasma generation, 6, 10 ... High frequency power supply, 7 ... Reaction area, 8 ... Semiconductor wafer, 9 ...
Plasma generation area.

Claims (1)

[Scope of Claims] 1. In a vapor phase growth method in which a plurality of power sources with different frequencies are used as power sources for excitation of a reaction gas to excite the reaction gas and form a desired film on a substrate to be processed, A first plasma generation region excited at a first frequency and a second plasma generation region excited at a second frequency are provided closer to the reaction gas inlet than the first plasma generation region, and the second plasma generation region is excited at a second frequency. A vapor phase growth method characterized in that film formation is performed by placing the substrate within a first plasma generation region. 2. In a reduced pressure reaction tube having a reaction gas inlet and an exhaust port, a plurality of first electrode groups arranged opposite to each other and having a wafer attached to the surface thereof and alternately connected in common; a first high frequency power source that applies a first high frequency between the first electrode groups; a second electrode that is disposed opposite to the first electrode group on the reaction gas inlet side; a second high-frequency power source that applies a second high-frequency wave different from the first high-frequency wave between the electrodes, and a first plasma generation region excited at the first frequency is a wafer processing region;
A vapor phase growth apparatus characterized in that a second plasma generation region excited at the second frequency is provided on the reaction gas inlet side of the reaction region.