JPS6113617A - Vapor growth method - Google Patents

Abstract

PURPOSE:To prevent generation of crystal dislocation in a semiconductor substrate by a method wherein the temperature of the circumferential part of the supporting member which is heated up to the highest temperature is detected, the temperature is properly controlled, the distribution of temperature is made uniform, and the temperature is raised at the prescribed temperature gradient. CONSTITUTION:First, a supporting member 4 is high frequency-heated by applying a current on a coil 8, and the above is controlled in such a manner that temperature is raised at the prescribed gradient, the temperature of the circumference 4 of the supporting member 4 is detected 10, it is compared with the set value, and a power source 9 is controlled and adjusted in accordance with the comparison value. According to this constitution, the temperature difference of the supporting member 4 when temperature is going up can be precisely controlled, there is no partial rise in temperature even when the speed of rise in temperature is increased to 3.5 deg.C/sec, a uniform heating can be performed and a slip, which is a crystal dislocation, is not generated on a substrate when a vapor growth method is performed subsequently.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a vapor phase growth method for growing a vapor phase on a semiconductor substrate.

[Technical background of the invention and its problems]

Generally, when growing a vapor phase on the surface of a semiconductor substrate (hereinafter referred to as a wafer), the wafer is placed in a mounting groove on a susceptor, and the wafer is indirectly heated by heating the susceptor. A gas phase is grown on the surface.

However, in the past, due to the temperature difference between the wafer and the susceptor, the wafer was thermally deformed and could not receive heat evenly from the susceptor, resulting in the occurrence of slip, which is crystal dislocation.

Therefore, in order to ensure that the wafer can receive heat uniformly from the susceptor, various methods have been devised for the wafer mounting groove of the susceptor, or the back surface of the blade is heated by the susceptor and the surface thereof is heated by an infrared lamp. Measures have been devised to minimize the temperature difference between the susceptor and the wafer.

However, in the former case, high precision in groove processing is required, and in the latter case, temperature control between the front and back sides of the wafer is complicated, and the reality is that sufficient improvement cannot be made.

As a result of intensive research into the causes of crystal dislocations in semiconductor substrates, the inventors of the present application have found that the main cause is a large difference in temperature distribution within the plane of the semiconductor substrate. moreover,
The difference in temperature distribution is caused by the fact that the heating structure of the support is designed to make the entire surface of the support uniform when the temperature is maintained at a constant temperature during vapor phase growth. It has been found that this is due to the fact that the temperature distribution of the support becomes uneven when strong thermal energy is supplied, and the outer peripheral side of the support becomes high temperature.

It has also been found that crystal dislocations are also related to the degree of etching (etching rate) of the surface of the semiconductor substrate performed immediately before vapor phase growth.

[Purpose of the invention]

The present invention was made in view of the above-mentioned circumstances, and its purpose is to avoid being affected by the groove shape of the support or to heat the semiconductor substrate from the opposite side of the support. The present invention aims to provide a vapor phase growth method that can prevent crystal dislocations in a semiconductor substrate.

[Summary of the invention]

In order to achieve the above-mentioned object, the present invention detects the temperature at the outer periphery of the support where the highest temperature is reached and controls the heating temperature of the support before vapor phase growth based on the detected value. This is to prevent crystal dislocation of the semiconductor substrate by preventing excessive temperature rise, and raising the temperature at a predetermined temperature gradient while suppressing variations in the temperature distribution within the plane of the semiconductor substrate as small as possible.

Further, the etching rate of the etching performed immediately before vapor phase growth is set to 0.06 μm/min, so that a highly efficient vapor phase growth layer with almost no crystal dislocations can be obtained.

[Embodiments of the invention]

Hereinafter, the present invention will be described with reference to an embodiment shown in the drawings. FIG. 1 shows a vapor phase growth apparatus, and 1 in the figure is a pace. A bell jar 2 is placed on this base 1, and a reaction chamber 3 is configured. A susceptor 4 as a support is provided in the reaction chamber 3, and a plurality of wafers 5 as semiconductor substrates are placed on the susceptor 4 (not shown).
is placed. The susceptor 4 has a hollow rotating shaft 6
A reactant gas supply pipe 1 is inserted into the rotary shaft 6 . Further, a work coil 8 is provided opposite to the lower part of the susceptor 4, and this work coil 8 is electrically connected to a high frequency power source 9.

The outer periphery of the susceptor 4 is larger than the inner periphery due to contact with the reaction gas during the vapor phase growth process and is easily cooled. Therefore, by adjusting the distance between the susceptor 4 and the work coil 8, the outer periphery can be heated strongly. The entire surface of the susceptor 4 is made to have a uniform temperature. In addition, the above Belljar 2
A photosensor 10 is provided above the susceptor 4, and this photo sensor 10 detects the temperature of the outer peripheral portion of the susceptor 4. This photosensor 10 is a comparator 11
It is connected to the high frequency power supply 9 via. The comparator 11 compares the output value sent from the photosensor 10 with a set value A, and controls the output of the high frequency power source 9 according to the comparison value.

In addition, 12 in the figure is a monitoring window 12 formed in the bell jar 2.

However, when performing vapor phase growth on wafer 5...
A high frequency power source is applied to the work coil 8 to heat the susceptor 4, thereby indirectly heating the welding material 15 to a predetermined temperature. In the process of raising the temperature of the susceptor 4 and wafer 5, in order to heat them to a predetermined temperature as quickly as possible, a higher power is applied to the work coil than when only maintaining the predetermined temperature during vapor phase growth. 8, and the temperature is controlled to rise at a predetermined gradient as shown in the upper right 9 portion H1 of the temperature curve H shown in FIG.

The temperature increase gradient is controlled by detecting the temperature at the outer circumference of the susceptor 4 by a photosensor 10, and sending its output value to a comparator 11, which sets a set value A that changes in relation to the output value and time. This is performed by PID adjusting the output of the high frequency power supply 9 according to the comparison value.

By the way, as mentioned above, during vapor phase growth, the outer circumferential side of the susceptor 4 is cooled the most by the reaction gas ejected from the supply pipe 7, so by adjusting the distance between the work coil 8 and the susceptor 4, The sides are heated more strongly. Note that the degree to which the outer circumferential side is strongly heated is such that the temperature of the susceptor 4 reaches a predetermined vapor phase growth temperature and the entire surface of the susceptor 4 becomes uniform while supplying low power compared to the temperature raising process. It is defined as follows. Therefore, when the temperature rises when strong power is supplied to the work coil 8, the outer circumferential side becomes considerably hotter than the inner circumferential side. When temperature increase control is performed by detecting the temperature on the outer circumferential side, the temperature on the outer circumferential side is not controlled, and even though the outer circumferential side has reached a temperature along a predetermined temperature increase gradient, Stronger power was supplied without being detected, creating a larger temperature gradient in the radial direction of the susceptor 4, which caused crystal dislocations to occur within the wafers 5.

However, as described above, the present invention detects the temperature on the outer circumferential side of the susceptor 4, which is the highest temperature, and controls the temperature increase accordingly. The difference can be precisely controlled, and the heating rate was conventionally set at 0.3°C/sec.
Even when the temperature was increased to 5° C./sec, no crystal dislocation was observed in the vapor-phase grown layer that was subsequently grown.

Note that FIG. 2 shows the transition of the temperature of the susceptor 4 according to the present invention, and the transition from temperature increase to constant temperature is accurately performed, but conventionally, the temperature of the highest temperature part of the susceptor 4 is was not detected, there was a delay in the detected value, resulting in an overshoot of 0 as shown in Figure 3.
Because temperature changes occur in a short period of time, this is also the case with wafer 5...
This was the cause of crystal dislocations.

Furthermore, in order to improve the quality of the vapor-phase grown layer prior to vapor-phase growth, the surface of the wafer 5 is etched with hydrogen chloride when the temperature of the wafer 5 has stabilized at, for example, 1150°C. Slip occurs on the wafers 5 depending on the degree of . Generally, etching is carried out at an etching rate of about 0.1 .mu.m/min, but as a result of various experiments, it has been found that when the etching rate is set to 0.06 .mu.m/min or less, no slip occurs on the wafers 5.

Further, the S-R curve of the vapor-phase grown layer after the temperature increase control and etching described above is as shown in FIG.
It can be seen that the resistance distribution of wafer 5 and the vapor growth layer is steep and there is no problem.

As described above, by detecting the temperature on the outer peripheral side of the susceptor 4 and controlling the temperature increase, the temperature of the susceptor 4 can be made more uniform, and the entire surface of each wafer 5 can be heated more uniformly.
This suppresses the occurrence of crystal dislocations in the wafer 5, and further reduces the etching rate by hydrogen chloride on the surface of the wafer 5 to 0.06 μm prior to vapor phase growth.
If the heating time is less than 1 minute, the occurrence of slips and drops, which are crystal dislocations of the wafer 5, can be more reliably prevented.

It should be noted that the present invention is not limited to the above-mentioned embodiment, and it goes without saying that various modifications can be made within the scope of the invention.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to uniformly heat a semiconductor substrate, and it is possible to reliably prevent slips, which are crystal dislocations, from occurring in the semiconductor substrate.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a schematic configuration diagram showing a vapor phase growth apparatus, FIGS. 2 and 3 are graphs showing temperature rise and cooling curves of a susceptor, and FIG. The figure is a graph showing an SR curve showing evaluation of a grown layer. 4... Susceptor (support body), 5... Wafer (semiconductor substrate). Applicant's representative Patent attorney Takehiko Suzue Time Figure 3 JP-A-Sho Gl-13617 (5)

Claims (2)

[Claims] 1. When a semiconductor substrate is placed on a heated support and vapor phase growth is performed on the surface of the semiconductor substrate, the heating temperature increase of the support before vapor phase growth is detected, and the temperature of the outer periphery of the support is detected. and control based on the detected value. 2. When a semiconductor substrate is placed on a heated support and vapor phase growth is performed on the surface of the semiconductor substrate, the heating temperature increase of the support before vapor phase growth is detected, and the temperature of the outer periphery of the support is detected. and controlling the etching of the semiconductor substrate surface when the support reaches a predetermined temperature based on the detected value.
A vapor phase growth method characterized by performing vapor phase growth after etching at an etching rate of 0.06 μm/min or less.