JPS59217693A - Apparatus for pulling semiconductor single crystal - Google Patents

Abstract

PURPOSE:To suppress the fluctuation of the atmosphere in the furnace chamber caused by the operation of a valve, in an apparatus for pulling a semiconductor crystal grown under reduced pressure, by attaching a pair of switchable inlets of inert gas at the top of the pulling chamber and under the shut-off valve, respectively. CONSTITUTION:The inert gas inlet 11 is attached to the top of the pulling chamber 5, and the other inlet 12 is attached to the connecting path 3 under the shut-off valve 4. Either the inlet 11 or 12 is selected with the selector valve 13. The inside of the pulling apparatus is maintained to a reduced pressure by evacuating through the exhaust port 16 attached to the bottom of the furnace chamber 1. Maintaining the evacuated state, (i) the shut-off valve 4 is opened (as shown by dotted line), the inlet 12 is closed, the inlet 11 is opened, and the single crystal 9 is grown from the molten liquid 18 in the crucible 2 by conventional process; and when a required amount of the single crystal 9 is formed, (2) the crystal is pulled up completely in the pulling chamber 5, the valve 4 and the inlet 11 are closed, the inlet 12 is opened, the door 10 is opened, and the single crystal is taken out of the pulling chamber 5.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a semiconductor crystal pulling machine for growing a semiconductor single crystal in a reduced pressure inert gas atmosphere, and particularly relates to a semiconductor crystal pulling machine for growing a semiconductor single crystal in a vacuum inert gas atmosphere. This article relates to a semiconductor crystal pulling machine that improves the adverse effects caused by changes in the reduced pressure inert gas atmosphere inside the furnace chamber due to the opening and closing of the shut-off valve installed in the chamber. Problem] The above-mentioned type of pulling machine generally allows an appropriate amount of inert gas to flow in from both the observation window installed on the ceiling of the furnace chamber and the upper part of the pulling chamber, which are communicated with each other during crystal growth. Both the furnace chamber and the pulling chamber were placed in a reduced pressure inert gas atmosphere, but when the shutoff valve was closed when taking out the single crystal after crystal growth, the inert gas crab that was being supplied from the top of the pulling chamber Since the inert gas does not flow into the furnace chamber, the flow of inert gas inside the furnace chamber is disturbed, and more vaporized substances from inside the crucible adhere to the walls of the furnace chamber, and the degree of vacuum inside the furnace chamber increases, causing evaporation from inside the crucible. This causes problems such as an increase in the number of materials dying9, and a change in the temperature of the melt in the crucible! In order to keep the trend constant, it may be possible to increase the amount of inert gas inflowing from the observation window, but this would increase the turbulence of the inert gas flow and cause the sand 1 observation window to become dirty. It also becomes.

[Purpose of the invention]

The present invention was made in order to solve the above-mentioned drawbacks, and it is a semiconductor unit that further suppresses changes in the reduced pressure inert gas atmosphere in the furnace chamber due to the opening and closing of the shutoff valve. A crystal pulling machine is available for use.

[Summary of the invention]

In order to achieve the above object, the present invention provides an inert gas inlet also below the shut-off valve, and when the shut-off valve is closed, the inert gas is injected from the upper part of the pulling chamber into the shirt. 1. The inert gas is configured to flow in from an inlet provided below the off valve.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. In the figure, 1 is a furnace chamber, and a crucible 2 is provided inside the furnace chamber 1, and the crucible 2 is heated by a heater (not shown). A communication passage 3 is provided on the ceiling of the furnace chamber 1, and a shutoff valve 4 is provided above the communication passage 3. A pull-up chamber 5 is formed on either side of the shut-off valve 4, and a drive section 7 for rotating and raising/lowering the pull-up shaft 6 is provided in the upper part of the pull-up chamber 5. At the front of the pulling chamber 5 (right side in the figure), an sio for attaching a seed crystal 8 to the lower end of the pulling shaft 6 and for taking out the pulled single crystal 9 is installed so as to be airtightly closed. The upper part of the pulling chamber 5 and the communication passage 3 below the shut-off valve 4 are connected to the first. The second inlets 11, 12 are opened, respectively, and the switching valves 1. ? By switching, a predetermined flow rate of inert gas is alternately introduced from an inert gas supply property (not shown).

An observation window 14 is provided on the ceiling of the 111f furnace, and inside this observation window 14, 15 ports of inert gas θ:L are poured. At the lower part of the furnace chamber 1, an exhaust port 16 is provided to bring the inside of the furnace chamber 1 and the pulling chamber 5 into a reduced pressure state. In addition, 17 is an opening/closing valve for reducing the pressure in the pulling chamber 5 to J.W. in order to open the door 1O-1.

Next, the operation of this pulling machine will be explained.

When pulling a single crystal, 1 closes the valve 10 and the on-off valve 17, moves the shut-off valve 4 at t8m as shown by the imaginary line, communicates the furnace chamber 1 and the pulling chamber 5, and exhausts the air from the drain 16. , the switching valve 13 is turned off to allow inert gas to flow in from the first inlet port 11 . Incidentally, inert scum is allowed to flow into the fabric from the inlet 15 inside the observation window 14.

The amount of inert gas flowing through the first inlet 11 and the inlet 15 is set at an appropriate ratio to the amount of exhaust from the exhaust port 16, and the pressure inside the furnace chamber 1 and the pulling chamber 5 is reduced to a predetermined level. It is designed to keep it in good condition.

The flow of inert gas flowing in from the inlet port 11.15 has the role of preventing evaporated matter from the melt 18 from sticking to the observation window 14 of the furnace chamber 1 and the inner wall of the pulling chamber 5. are doing.

By the way, if for some reason you remove the seed crystal 8 with the melt 1B still in the crucible 2 and take it out of the machine after pulling the single crystal 9, As shown in the figure, the nM packed crystal 8 or single crystal 9 is separated from the melt 18 and lifted into the pulling chamber 5, the shutoff valve 4 is closed, and the door 10 is opened while the inside of the furnace chamber 1 is shut off from the atmosphere.

At this time, the inert gas from the first inlet 11 in the upper part of the pulling chamber 5 cannot flow into the furnace chamber 1 because the shutoff valve 4 is closed. Therefore, as the temperature of , the evaporated matter tends to adhere to the inner wall of the furnace chamber 1, and the flow of inert gas decreases, causing the temperature inside the furnace chamber 1 to change, and the temperature of the melt 18 to change with this force. This may cause problems such as

Therefore, in this lifting machine, before the above-mentioned shut-off valve 4 is closed (Ef'+), after (d), and (C), the switching valve 13 is switched as shown in the figure in conjunction with the closing of the shut-off valve 4. By this switching, the inert gas inflow from the first inlet port 11 is stopped, and instead, the inert gas flows in from the second inlet port 12 below the shut-off valve 4. ?: The amount of inert gas inflow from the furnace chamber J2 is determined by the flow rate adjustment valve that does not indicate "", so it is kept the same as the amount of inflow from the first δ11 population 11. υi of inert gas for 1 [person jq
(4. If there is no change in the case before or after closing the shutoff valve 4, and if the second inlet 12 is opened into the communication path 3 as shown in the figure, the There is almost no need to change the flow of waste.Therefore, regardless of whether the shutoff valve 4 is opened or closed, the inside of the furnace chamber 1 is maintained at the desired reduced pressure inert gas atmosphere, and the above-mentioned vote counting does not occur. After closing the shutoff valve 4, the door 10
When opening, since the pulling chamber l is in a reduced pressure state, the opening/closing valve 17 is used to make the inside of the pulling chamber l equal to the atmospheric pressure before opening. [Effects of the Invention] As described above. According to the present invention, during the pulling of a single crystal, the furnace chamber and the pulling chamber are placed in a predetermined reduced pressure inert gas atmosphere, and after the shirt opening valve is closed, the furnace chamber is kept in a state where there is almost no change during pulling. By placing the steel in a predetermined reduced-pressure inert gas atmosphere, it is possible to maintain good pulling over a long period of time while suppressing problems such as deposition of evaporated substances and temperature changes due to changes in the furnace chamber atmosphere.

[Brief explanation of drawings]

The drawing is a schematic longitudinal sectional side view showing an embodiment of a semiconductor single crystal pulling machine according to the present invention. 1... Furnace chamber, 2... Crucible, 3... Communication passage, 4...
... Shutoff valve, 5... Pulling o, 6... Pulling shaft, 7... Drive section, 8... Seed crystal, 9... Koto crystal, 10... Door, 11 ,12.15...Inlet, 1
3...Switching valve. 14... View, side window, 16... Exhaust port, 17... Opening/closing valve, 18... Melt liquid. Patent Attorney Takehiko Suzue Continued from page 1 0 Inventor Masato Matsuda Inventor Toshiba Ceramics Co., Ltd. Oguni Factory, 78 Ogunimachi, Nishiokitama-gun, Yamagata Prefecture Applicant Toshiba Ceramics Co., Ltd. Tokyo 1-26-2 Nishi-Shinjuku, Shinjuku-ku

Claims (3)

[Claims] (1) Inert gas is introduced from the observation window provided on the ceiling of the furnace chamber and the upper part of the pulling chamber formed above the furnace chamber through a shut-off valve, and In a semiconductor single crystal pulling machine that performs crystal growth in a reduced-pressure inert gas atmosphere, an inert gas inlet is also provided below the shut-off valve, and the inert gas is removed from the upper part of the pulling chamber. A semiconductor single crystal pulling machine, characterized in that the inflow and the inflow from the inlet can be alternately switched. (2) A half- and four-body crystal pulling machine according to claim (1), wherein the inlet is opened in a communication path between the lamp chamber and the pulling chamber. (3) The switching is configured to be performed in conjunction with opening and closing of the shutoff valve. A semiconductor single crystal pulling machine according to claim (1) or (2).