JPS6027119A - Vapor growth device of semiconductor - Google Patents

Abstract

PURPOSE:To supply a stable gas flow into a growing reaction tube by making exhaust gas pressure prior to be supplied actually equal to the pressure of gas in the growing reaction tube. CONSTITUTION:Gas, quantity of the flow is controlled by a mass flow controller or flow meters 20, 21, 22 or 23, is exhausted outside a device by closing switch valves 24, 25 or 26 and opening switch valves 27, 28 or 29. At this time, the gas pressure in an exhaust pipe 30 is detected by a pressure gage 31 and is controlled by a gas pressure controller 32 equal to the pressure detected by a pressure gage 34 in a growing reaction tube 33. In this case, the gas pressure prior to be supplied is equal to the gas pressure in the growing reaction pipe and stable quantity of gas flow can be maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor vapor phase growth apparatus, and particularly to a semiconductor vapor phase growth apparatus for supplying doping gas, composition control gas, and other feed gases between a growth substrate and a growth layer, or between growth layers in semiconductor vapor phase growth. This invention relates to a semiconductor vapor phase growth apparatus that eliminates gas flow rate fluctuations during input.

Various devices using semiconductors require growth layers that have a multilayer structure with a complex impurity distribution, and in which the type, composition, and concentration of impurities change sharply between the growth layers. In vapor phase growth, the most important thing to achieve these is that the gas flow rate supplied to the growth region changes rapidly and immediately returns to a steady state.

In conventional vapor phase growth apparatuses, for example, doping gas is introduced into the growth reaction tube using a switching valve. In this case, since there is generally a difference between the doping gas pressure and the gas pressure in the growth reaction tube, gas flow rate fluctuations occur when the switching pulp is opened and closed. If a mass flow controller (electronic flow rate control) is used, the flow rate will be controlled to be constant even if the gas pressure fluctuates, but it will take several minutes for it to become completely stable. . Also,
When using a float meter, the flow rate varies with pressure. Therefore, the flow rate of the doping gas fed into the growth reaction tube differs from the set value, and the concentration change between the growth layers becomes slow or abnormal depending on the flow rate fluctuation.

The same is true for the composition control gas and other gases to be supplied, and the steepness between the substrate and the growth layer and between the growth layers becomes slow, and compositional fluctuations occur.

FIG. 1 is a schematic diagram of a conventional vapor phase growth apparatus using the pyrolysis method. The doping gas, composition control gas, and other gases are discharged from the growth reaction tube 11 by closing the switching pulps 5.6 and 7 and opening the switching pulps 8.9 and 10. Meter 1.2.
3 and 4 set the flow rate. Then pulp 8.9 and l.

When 5.6 and 7 are opened, a doping gas, a composition control gas and other gases are introduced into the growth reaction tube 11 to form a growth layer having a desired impurity concentration and composition on the substrate 12. After passing through the growth region, the gas introduced into the growth reaction tube passes through the exhaust gas treatment device 14 through the gas exhaust port 13 and is discharged all at once.

In such a conventional device, the gas in each line is switched from the discharge state to the supply state into the reaction tube by the combined operation of the switching valves 5 and 8, (5 and 9, and 7 and 10), but in this case, Since there is a difference between the gas pressure at the time of discharge and the gas pressure inside the growth reaction tube 11, the gas flow rate supplied to the growth region varies. The flow rate change based on this temporary pressure fluctuation not only impairs the steepness of the interface between the growth layers, but also causes a problem in that it is impossible to control the doping concentration and composition immediately after switching.

SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor vapor phase growth apparatus that eliminates the drawbacks of the conventional apparatus described above and allows a stable gas flow rate to be supplied into a growth reaction tube.

According to the present invention, when a doping gas, a composition control gas, and other gases are fed into a growth reaction tube in the vapor phase growth of semiconductors by a switching pulp, the exhaust gas pressure of the gases before being fed is controlled during the growth reaction tube. A semiconductor vapor phase growth apparatus is obtained, which is characterized in that the gas pressure in the reaction tube is maintained at substantially the same pressure.

The present invention will be explained below with reference to an example in which the present invention is applied to pyrolysis vapor phase growth. FIG. 2 is a schematic diagram showing a first embodiment of the present invention. By closing mass flow controllers 25 and 26 and opening 27, 28 and 29, the gas is discharged to the outside of the apparatus.
Vc is detected and the gas pressure is controlled by the gas pressure regulator 32 to be the same as the gas pressure inside the growth reaction tube 33 detected by the pressure gauge 34. In this case, doping gas, composition control gas, and other gases are introduced into the growth reaction tube 33 by opening and closing the switching valves 24 and 27, 25 and 28, and 26 and 29, respectively. At this time, the pressure of the gas to be fed before feeding and the gas pressure inside the growth reaction tube are the same, so an extremely stable gas flow rate is maintained. Although controlled by a system pressure gauge and pressure regulator, it is also possible to control each line separately.

FIG. 3 is a schematic diagram showing a second embodiment of the present invention. In this embodiment, the outlet for temporarily exhausting the gas introduced before growth is connected to the downstream part 53 of the plate 52 in the growth reaction tube 51. In this case, the gas pressure automatically becomes equal to the pressure inside the reaction tube, and the switching valves 45, 48, 46, 49, 47, and 50 switch the doping gas, composition control gas, and other gases into the growth reaction tube 51. When switching by a combination operation, the pressure of the fed gas before feeding and the gas pressure inside the growth reaction tube automatically become the same pressure, and an extremely stable gas flow rate is maintained even during the switching. Although the figure shows a structure in which the growth substrate 52 is connected to the downstream part 53, the exhaust connection is made so that the gas pressure is the same as the gas pressure inside the growth reaction tube between the substrate and the processing equipment. In the place where it becomes No. 1. Anywhere is fine.

Figure 4 shows the change in flow rate when the doping gas is switched. Solid line 1 shows the case when a mass flow controller is used in the conventional method, solid line 2 shows the case when a float meter is used, and the flow rate with the device of the present invention is shown. The broken line 3 shows the case where The vertical axis indicates the flow rate set by flowing gas into the exhaust line.
It was set to 0%.

According to the present invention, in a semiconductor vapor phase growth apparatus, a stable gas flow rate is supplied into the growth reaction tube.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an example of a conventional vapor phase growth apparatus, FIGS. 2 and 3 are schematic diagrams of two embodiments of the vapor phase growth apparatus of the present invention, and FIG. 4 is a schematic diagram of an example of a conventional vapor phase growth apparatus. It is a flow rate change diagram in which the horizontal axis is time (minutes) and the vertical axis is a ratio (ch) to a set value when gases are switched for the growth apparatus and the vapor phase growth apparatus of the present invention. 20.21.22.23 and 41,42.43°44
...Mass flow controller or float meter, 24.25.26.27.2B, 29° and 4
5, 46, 47.48, 49.50...Switching valve, 30...Temporary exhaust pipe, 31...
Exhaust gas pressure gauge, 32... Exhaust system gas pressure regulator, 33.51... Growth reaction tube, 34...
- Gas pressure gauge in the growth reaction tube, 35.54...
・Exhaust gas treatment equipment.

Claims (1)

[Claims] Doping gas and composition control gas 9j in the growth reaction tube
A semiconductor vapor phase growth apparatus in which gas and other gases are fed by a switching valve, is provided with a structure in which the exhaust gas pressure of the gas before being fed is made to be substantially the same pressure as the gas pressure in the growth reaction tube. A semiconductor vapor phase growth apparatus characterized by: