JPH0633962U - Semiconductor single crystal manufacturing equipment - Google Patents

Abstract

(57) [Abstract] [Purpose] To minimize disturbance of heat balance in the circumferential direction and disturb the flow of an inert gas in a single crystal manufacturing apparatus equipped with a radiation screen that surrounds a pulled single crystal above the vicinity of the melt. Instead, allow direct observation of the area around the inner wall of the crucible. [Structure] A viewing window 3 is provided in the upper chamber 2, and an observation window 12 is provided on a flange 11a above the radiation screen.
Is provided and the inside of the furnace is observed through the observation window 3 and the observation window 12. The observation window 12 is arranged in the horizontal direction θ with respect to the observation window 3.
The quartz glass is provided at a position shifted by (θ = 10 to 80 °), and the quartz glass is fitted into the flange 11a directly or through a window frame made of graphite, and the quartz glass has a single or multi-layered structure. Even if the observation window 12 is made small, it is possible to observe the inside of the furnace sufficiently, and by suppressing the heat loss from the observation window 12, it is possible to minimize the loss of heat balance and disturb the flow of the inert gas. Never.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a semiconductor single crystal manufacturing apparatus by the Czochralski method.

[0002]

[Prior art]

 The Czochralski method (hereinafter referred to as the CZ method) of pulling a cylindrical single crystal from a raw material melt in a crucible is used as one of the methods for producing a silicon single crystal which is a basic material of a semiconductor integrated circuit. . In the CZ method, a crucible installed in a chamber of a single crystal manufacturing apparatus is filled with a polycrystal as a raw material, the raw material is heated and melted by a heater provided on the outer periphery of the crucible, and then the seed is attached to a seed chuck. The crystal is immersed in the melt, and the seed chuck is pulled up while the seed chuck and the crucible are rotated in the same direction or opposite directions to grow a single crystal. In such a single crystal manufacturing apparatus, as a means of increasing the pulling rate of the single crystal and preventing contamination by impurities to improve dislocation-free single crystal, a radiation screen is provided around the single crystal pulling region. It is known to arrange. The radiation screen is a heat shield surrounding the single crystal pulling region, and is generally a conical tube having a lower end opening diameter smaller than an upper end opening diameter. The radiant screen blocks the radiant heat applied to the single crystal from the melt, heater, crucible, etc., and also draws up the inert gas introduced from above the chamber and guides it around the single crystal, and the peripheral portion from the center of the crucible. By forming a gas flow to reach the lower part of the chamber, it has the function of eliminating the gas that impedes single crystallization, such as the cooling of the single crystal and the vaporization of silicon oxide from the melt and metal vapor generated from the graphite crucible. I have it.

During the melting of the raw material polycrystal and the subsequent pulling up of the single crystal, interference between the radiation screen and the quartz crucible due to deformation of the quartz crucible, adhesion of the raw material polycrystal to the inner wall of the quartz crucible, and crucible temperature. Various problems may occur, such as crystal growth at the contact surface between the melt and the quartz crucible, which is caused by the decrease in the temperature. The radiant screen has the effect of improving the quality and productivity of the single crystal, but the installation of the radiant screen encloses the area around the single crystal pulling region, so the crucible and the surroundings of the crucible cannot be monitored. The occurrence of trouble cannot be detected. As a technology to solve this problem, an observation window consisting of a graphite cylinder covered with quartz glass is provided on the annular rim at the upper end of the radiation screen, and a viewing window provided on the chamber ceiling wall and an observation window provided on the radiation screen. There is disclosed a proposal by Jitsukai Sho 63-162869, which makes it possible to observe the crucible, the melt surface, the peripheral edge of the single crystal, and the heater through. In addition, an opening is provided in the conical cylinder of the radiation screen, and the boundary between the inner wall surface of the crucible and the melt can be observed through the viewing window provided in the chamber ceiling wall and the opening provided in the radiation screen. The proposal by Japanese Utility Model Laid-Open No. 2-57962 or Japanese Utility Model Laid-Open No. 2-61963 is disclosed.

[0004]

[Problems to be solved by the device]

 However, the above conventional technique has the following problems. In other words, (1) In the proposal by Shokai 63-162869, a relatively large observation window consisting of a graphite cylinder covered with quartz glass was provided in the annular rim at the top of the radiation screen, so The heat balance is lost, and stagnation of the inert gas can occur in the graphite cylinder. Therefore, the flow of exhaust gas is disturbed, which hinders stable growth of the single crystal. Further, the structure of the radiant screen becomes complicated, resulting in an increase in cost. (2) In the proposals by the actual flat plate 2-57962 or the flat plate 2-61963, the heat balance in the circumferential direction in the furnace is lost because the mounting plate at the upper end of the radiation screen or the conical tube has an opening. Since the flow of the inert gas changes at the opening, stable growth of the single crystal is hindered. The present invention has been made focusing on the above-mentioned conventional problems, and it is possible to directly observe the crucible and the surroundings of the crucible without disturbing the flow of exhaust gas by minimizing the disturbance of the heat balance in the circumferential direction. It is an object of the present invention to provide an apparatus for producing a semiconductor single crystal that can be manufactured.

[0005]

[Means for Solving the Problems]

 In order to achieve the above object, a semiconductor single crystal manufacturing apparatus according to the present invention comprises a crucible for filling a raw material of a semiconductor single crystal, a heater for melting the raw material in the crucible surrounding the crucible, and the melted raw material. In a single crystal manufacturing apparatus in which a seed crystal is dipped in and the single crystal is pulled up, and a radiation screen surrounding the single crystal is placed above the vicinity of the melt, a viewing window is provided at the top of the chamber and the radiation screen The observation window is provided at a position horizontally deviated from the observation window by 10 to 80 °. In such a configuration, the observation window provided on the radiation screen is the observation window from the outside of the chamber and the observation window. At least the inner wall of the crucible, the outer peripheral portion of the melt, and the inner peripheral surface of the heater can be directly observed through the window. The observation window provided on the radiation screen shall be one or more heat-resistant transparent plates fitted directly into the holes formed in the radiation screen, or the observation window provided on the radiation screen shall be the radiation window. One or a plurality of heat-resistant transparent plates may be fitted into the holes formed in the screen through a window frame made of black lead or graphite coated with silicon carbide.

[0006]

[Action]

 According to the above configuration, in the single crystal manufacturing apparatus including the radiation screen surrounding the single crystal above the vicinity of the melt, the viewing window is provided in the upper part of the chamber, and the radiation screen is arranged in the horizontal direction with respect to the viewing window. Since the observation window is provided at a position displaced by 10 to 80 ° from the inside, it is possible to directly observe at least the inner wall of the crucible, the outer peripheral portion of the melt and the inner peripheral surface of the heater from the outside of the chamber through these two windows. It is easy to observe the crucible and the surroundings of the crucible that were blocked by the radiation screen. By displacing the positions of the two windows and observing the inside of the furnace from diagonally above, it is possible to observe the inside of the furnace sufficiently even if the observation window is made small. The heat-resistant transparent plate attached to the observation window was fitted directly into the holes formed in the radiant screen or via a graphite window frame, so there was minimal disruption of the heat balance in the circumferential direction inside the furnace. In addition, the flow of inert gas is not disturbed. Further, the temperature of the end surface of the heat-resistant transparent plate on the crucible side is maintained at 800 ° C. or higher to prevent the evaporation of the vapor generated from the melt or the like, so that the visibility can be secured.

[0007]

【Example】

 An embodiment of a semiconductor single crystal manufacturing apparatus according to the present invention will be described below with reference to the drawings. 1 is a partial cross-sectional view showing a schematic configuration of a semiconductor single crystal manufacturing apparatus, and FIG. 2 is a cross-sectional view taken along the line AA of FIG. In these figures, 1 is a main chamber, 2 is an upper chamber, and a viewing window 3 made of quartz glass is installed in the upper chamber 2 for observing the inside of the furnace from the outside. A quartz crucible 5 is fitted into a graphite crucible 4 installed in the main chamber 1, and a silicon single crystal 7 is pulled up from a silicon melt 6 stored in the quartz crucible 5. 8 is a crucible shaft, 9 is a graphite heater, 10 is a heat insulating cylinder, and a radiation screen 11 is fixed to the upper surface of the heat insulating cylinder 10. The radiant screen 11 is a heat shield surrounding the single crystal pulling region, is a conical cylinder whose lower end opening has a diameter smaller than that of the upper end opening, and is provided with an annular flange 11a at the periphery of the upper end opening. ing. An English glass is fitted into a hole provided in the flange 11a to form an observation window 12.

FIG. 2 shows the viewing window 3 projected on the AA cross-sectional view of FIG. 1, and the viewing window 3 is indicated by a two-dot chain line. In the figure, the observation window 12 is provided at a position horizontally displaced from the observation window 3 by an angle θ, for example, at a position displaced by 30 °, and is observed obliquely from above through the observation window 3 and the observation window 12. As a result, even if the area of the observation window 12 is small, the inner wall of the quartz crucible 5, the outer peripheral portion of the melt 6 and the inner peripheral surface of the graphite heater 9 can be directly observed. An example of the size of the observation window 12 is 32 × 60 mm. The shape of the observation window 12 is not limited to a rectangle, but may be a square or a circle.

FIG. 3 and FIG. 4 are enlarged views of the P portion of FIG. 1, showing an embodiment of the observation window according to claim 3. In FIG. 3, a quartz glass 13 having the same thickness as that of the flange 11a is fitted in the stepped hole provided in the flange 11a of the radiation screen. If the size of the observation window 12 is about 32 × 60 mm, the amount of heat escaping from this window is small and the quartz glass 13 is difficult to cool. Therefore, silicon oxide or the like that evaporates from the melt is fused in one batch to grow the quartz glass 13. Will not adhere to. However, since the vaporized substance may be deposited on the quartz glass 13 when continuously used for growing several batches, it is preferable to use a quartz glass having a multilayer structure. That is, as shown in FIG. 4, the observation window is composed of four glass windows 14, 15, 15, and 16, and the evaporation from the melt or the like is made on the lower side, that is, on the melt side of the quartz glass by providing thermal resistance. It is possible to prevent adherence to 16. An example of the temperature measurement result in the vicinity of the quartz glass on the melt side when pulling the single crystal is about 800 ° C in the case of FIG. 3 and about 900 ° C in the case of FIG.

5 to 10 are enlarged views of the P portion of FIG. 1, and show an embodiment of the observation window according to claim 4. As shown in FIG. 5, when the radiant screen 11 has a three-layer structure and a heat insulating material such as carbon felt which is easy to stand up is used for the intermediate layer 11b, it is made of graphite in the stepped hole provided in the flange 11a. Alternatively, a graphite window frame 11c coated with SiC is fitted to suppress the fuzziness of the intermediate layer 11b, and then quartz glass is fitted into the window frame 11c. FIG. 5 shows that when the quartz glass 13 having the same thickness as that of the flange 11a is fitted, FIG. 6 shows that the window frame 11d is fitted only to the upper part from the step of the stepped hole provided in the flange 11a, The case where a quartz glass 13 having the same thickness as the flange 11a is fitted is shown. In this case, since the lower portion of the quartz glass 13 is in direct contact with the lower layer of the radiation screen having the three-layer structure, which has a high temperature, the high temperature can be maintained, and the vaporized substances from the melt or the like adhere to the quartz glass 13. The prevention effect is greater. FIG. 7 shows a case in which the four quartz glass plates 14, 15, 15, 16 shown in FIG. 4 are fitted in the window frame 11c, and the effect of preventing the evaporation of a vapor or the like from the melt to the quartz glass 16 is prevented. Is big.

8 to 10 show the window frame 11c fitted in the stepped hole provided in the flange 11a, and the quartz glass is fitted only in the upper part from the step of the window frame 11c. A depression is formed on the lower side of the. If the depth of the recess is several mm, the retention of inert gas does not occur. Since this structure does not have a stepped portion in the quartz glass, the cost of the quartz glass can be reduced. FIG. 8 shows the case where one piece of quartz glass 17 is used, and FIG. 9 shows the case where the two pieces of quartz glass 18, 15 are used. Further, in FIG. 10, a spacer 20 is sandwiched between two pieces of quartz glass 19 and 15 to form a space, and the effect of a multi-layer structure is provided, and the cost reduction effect is great.

[0012]

[Effect of device]

 As described above, according to the present invention, in the single crystal manufacturing apparatus having the radiation screen surrounding the single crystal pulled up near the melt, the observation window is provided on the upper part of the chamber and An observation window was installed at a position horizontally displaced from the viewing window by 10 to 80 °, and the periphery of the inner wall of the crucible could be directly observed from the outside of the chamber through these two windows, so that it was blocked by the radiation screen. The situation around the inner wall of the crucible, which had been used in the past, could be easily observed, and various problems such as adhesion of the raw material polycrystal to the inner wall of the crucible and crystal growth at the contact surface of the melt and the crucible could be found at an early stage. Can take measures. Since the positions of the two windows are offset from each other and the inside of the furnace is observed obliquely from above, the inside of the furnace can be observed sufficiently even if the observation window is made small, and the heat loss from the observation window is minimized. Therefore, the heat balance in the circumferential direction is minimized and the flow of inert gas is not disturbed. Further, the temperature of the end surface of the heat-resistant transparent plate such as quartz glass on the side of the crucible is kept at 800 ° C. or higher, and the adherence of evaporative substances generated from the melt or the like is prevented, so that the visibility can be secured.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing a schematic configuration of a semiconductor single crystal manufacturing apparatus.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is an enlarged view of part P of FIG. 1, showing a first embodiment of an observation window according to claim 3;

FIG. 4 is an enlarged view of part P of FIG. 1, showing a second embodiment of the observation window according to claim 3.

5 is an enlarged view of part P of FIG. 1, showing a first embodiment of the observation window according to claim 4. FIG.

6 is an enlarged view of part P of FIG. 1, showing a second embodiment of the observation window according to claim 4. FIG.

FIG. 7 is an enlarged view of part P of FIG. 1, showing a third embodiment of the observation window according to claim 4.

8 is an enlarged view of part P of FIG. 1, showing a fourth embodiment of the observation window according to claim 4. FIG.

9 is an enlarged view of part P of FIG. 1, showing a fifth embodiment of the observation window according to claim 4. FIG.

10 is an enlarged view of part P of FIG. 1, showing a sixth embodiment of the observation window according to claim 4. FIG.

[Explanation of symbols]

1 Main Chamber 2 Upper Chamber 3 View Window 4 Graphite Crucible 5 Quartz Crucible 6 Silicon Melt 7 Silicon Single Crystal 9 Graphite Heater 11 Radiation Screen 11a Flange 11c, 11d Window Frame 12 Observation Window 13, 14, 15, 16, 17, 17, 18 , 19 Quartz glass

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Noboru Furuichi 2612 Shinomiya, Hiratsuka City, Kanagawa Prefecture Komatsu Electronic Metals Co., Ltd.

Claims (4)

[Scope of utility model registration request] 1. A crucible for filling a raw material of a semiconductor single crystal, a heater for melting the raw material in a crucible around the crucible, and a pulling mechanism for pulling the single crystal by immersing the seed crystal in the melted raw material. In a single crystal manufacturing apparatus in which a radiation screen that surrounds the periphery of the single crystal is disposed above the vicinity of the melt, a viewing window is provided in the upper part of the chamber,
1 horizontally on the radiant screen with respect to the viewing window
An apparatus for manufacturing a semiconductor single crystal, wherein an observation window is provided at a position deviated from 0 to 80 °. 2. The observation window provided on the radiation screen allows direct observation of at least the inner wall of the crucible, the outer peripheral portion of the melt and the inner peripheral surface of the heater from the outside of the chamber through the observation window and the observation window. The semiconductor single crystal manufacturing apparatus according to claim 1, wherein 3. The semiconductor window according to claim 1, wherein the observation window provided on the radiation screen is one in which one or a plurality of heat-resistant transparent plates are directly fitted into holes formed in the radiation screen. Single crystal manufacturing equipment. 4. The observation window provided on the radiation screen is one or a plurality of heat-resistant transparent plates through a window frame made of graphite or silicon carbide coated graphite in a hole formed in the radiation screen. The semiconductor single crystal manufacturing apparatus according to claim 1, wherein the semiconductor single crystal manufacturing apparatus is fitted with.