JP2007176761A - Manufacturing method and manufacturing device for silicon single crystal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method productively manufacturing a silicon single crystal while eliminating the formation of a tail portion. <P>SOLUTION: The pulling of the silicon single crystal S is substantially stopped without extremely changing the thermal history of the silicon single crystal S by raising a crucible 4 filled with a raw material melt liquid M at the same speed as that of the pulling speed of the silicon single crystal S after growing a straight barrel portion S1 of the silicon single crystal S. The silicon single crystal S is separated from the raw material melt liquid M in the state of nontransition in a state where a shape of a growing face of the silicon single crystal S is a protruded shape facing downward by separating the silicon single crystal S from the raw material melt liquid M. As a result, the silicon single crystal wherein the formation of the tail portion is eliminated can be carried out by reproductively performing the nontransition separation of the silicon single crystal S from the raw material melt liquid M. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a silicon single crystal manufacturing technique using the Czochralski method (hereinafter referred to as CZ method), and more particularly to a technique for manufacturing a silicon single crystal with high productivity by omitting the formation of a tail portion.

  In the CZ method, a polycrystalline silicon raw material is heated and melted in a crucible to produce a raw material melt, a seed crystal is immersed in the liquid surface of the raw material melt, and then a pulling wire holding the seed crystal is used. The silicon single crystal is pulled up by gradually winding up. At that time, first, a cone part (diameter enlarged part) gradually expanded from the contact part with the seed crystal is grown, and when the crystal diameter reaches a target diameter, a straight body part (constant diameter part) having a constant diameter. Grow. Then, when the length of the straight body part reaches a predetermined length, the silicon single crystal is separated from the raw material melt.

  When the silicon single crystal is separated from the raw material melt, if the separation is simply performed, a rapid temperature drop occurs at the lower end of the silicon single crystal, which is the separation site. As a result, slip transition occurs in the pulled silicon single crystal, and the single crystallization rate is greatly reduced.

  Therefore, normally, after the growth of the straight body portion of the silicon single crystal, the diameter is gradually narrowed and the silicon single crystal is melted in the raw material in a state where the contact area between the silicon single crystal and the raw material melt is sufficiently small. By separating from the liquid, the occurrence of slip transition is prevented. This narrowed portion with a reduced diameter is called a tail portion.

  However, the tail portion is an unnecessary portion that is cut off during wafer processing because the diameter is not constant. Therefore, it is desirable to shorten or omit the tail forming process in order to increase the productivity of the silicon single crystal.

  There are already several techniques for shortening or omitting the process of forming the tail portion of a silicon single crystal, and one of them is a method of putting a silicon single crystal into a melt and then separating the silicon single crystal from the melt. (Patent Document 1).

However, the prior art described in the above-mentioned document has a problem in that foreign matter is likely to be involved when the silicon single crystal is put into the melt, resulting in a decrease in yield.
JP 11-335197 A

  The problem to be solved by the present invention is that a silicon single crystal manufacturing method and manufacturing apparatus capable of manufacturing a silicon single crystal with high productivity by omitting the formation of the tail portion, and a program for the manufacturing apparatus and To provide a recording medium on which the program is recorded.

  In order to solve the above-mentioned problems, the manufacturing method of the present invention has grown the straight body portion of the silicon single crystal and then entered the raw material melt of the silicon single crystal at the same speed as the pulling speed of the silicon single crystal. The crucible was raised, and then the silicon single crystal was separated from the raw material melt.

  According to this manufacturing method, after growing the straight body portion of the silicon single crystal, the crucible containing the raw material melt is increased at the same speed as the pulling speed of the silicon single crystal that is being grown. By substantially stopping the pulling of the silicon single crystal without greatly changing the thermal history, and separating the silicon single crystal from the raw material melt in that state, the lower end surface of the silicon single crystal, that is, the raw material melt Thus, it becomes possible to separate the silicon single crystal from the raw material melt in a non-transitional state.

  The manufacturing apparatus of the present invention includes a crucible driving mechanism for moving up and down a crucible containing a raw material melt, a single crystal pulling mechanism for pulling a silicon single crystal while growing it from the raw material melt in the crucible, and a silicon single crystal The crucible drive mechanism and the single crystal so that the silicon single crystal is separated from the raw material melt. And a control device that controls the operation of the pulling mechanism.

  According to this manufacturing apparatus, the manufacturing method of the present invention can be easily implemented. That is, after growing the straight body of the silicon single crystal, the crucible containing the raw material melt is increased at the same rate as the pulling speed of the silicon single crystal being grown to greatly change the thermal history of the silicon single crystal. In this state, the pulling of the silicon single crystal is substantially stopped, and in this state, the silicon single crystal is separated from the raw material melt, so that the shape of the lower end surface of the silicon single crystal becomes a downward convex shape. The single crystal can be separated from the raw material melt in a non-transitional state.

  The program of this invention is a program for implement | achieving the said control apparatus with which the manufacturing apparatus of this invention is provided using a computer.

  The recording medium of the present invention is a computer-readable recording medium that records the program of the present invention.

  According to the manufacturing method and the manufacturing apparatus of the present invention, after the straight body portion of the silicon single crystal is grown, the crucible containing the raw material melt is increased at the same speed as the pulling speed of the growing silicon single crystal. Accordingly, the pulling of the silicon single crystal is substantially stopped without significantly changing the thermal history of the silicon single crystal, and in this state, the silicon single crystal is separated from the raw material melt, thereby The shape of the end face, that is, the interface with the raw material melt, has a downward convex shape, so that the silicon single crystal can be separated from the raw material melt in a non-transitional state, so the tail portion is omitted and the productivity is high. A silicon single crystal can be manufactured.

  According to the program of the present invention, the control device provided in the manufacturing apparatus of the present invention can be easily realized by installing the program in a computer.

  According to the recording medium of the present invention, the control device provided in the manufacturing apparatus of the present invention can be easily realized by installing the program recorded on the computer.

  Hereinafter, the best mode for carrying out the present invention will be described.

  1 to 6 are schematic cross-sectional views showing an example of a manufacturing apparatus (manufacturing apparatus of the present invention) used when manufacturing a silicon single crystal by the manufacturing method of the present invention. Moreover, FIGS. 1-6 is also a series of process drawings which show the manufacturing process in the manufacturing method of this invention.

  The manufacturing apparatus 1 includes a pulling furnace 2, a crucible support shaft 3 provided through the center of the bottom of the pulling furnace 2, a quartz crucible 4 loaded on the upper end of the crucible support shaft 3, A heater 5 arranged concentrically inside the main water-cooling chamber 2b of the pulling furnace 2 to heat the crucible 4 and its periphery from the surroundings, and a crucible support shaft drive mechanism (crucible drive) that moves the crucible support shaft 3 up and down Mechanism) 6, a seed chuck 8 holding the seed crystal 7, a pulling wire 9 for supporting the seed chuck 8, a wire winding mechanism (single crystal pulling mechanism) 10 for winding the pulling wire 9, and a crucible And a control device 11 that controls the operation of the support shaft drive mechanism 6 and the wire winding mechanism 10.

  The control device 11 has all the basic elements of a computer such as a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and an input / output interface. A control program according to the present invention is installed in the ROM. The CPU generates various control signals by executing arithmetic processing while using the RAM as a work area in accordance with a control program installed in the ROM. This control device 11 controls the operations of the crucible support shaft drive mechanism 6 and the wire winding mechanism 10, and further the operations of the heater 5, vacuum pump (not shown), Ar gas supply system (not shown), and the like. A silicon single crystal is manufactured by the manufacturing apparatus 1.

  When a silicon single crystal is manufactured by the manufacturing apparatus 1, first, as shown in FIG. 1, a silicon polycrystal raw material P, which is a silicon single crystal raw material, is filled into the crucible 4 side.

  Next, as shown in FIG. 2, after the upper part of the main water cooling chamber 2b of the pulling furnace 2 is sealed with the upper water cooling chamber 2a, a vacuum pump (not shown) is operated to exhaust gas pipe 12 of the bottom water cooling chamber 2c. Ar gas is supplied from the port of the upper water cooling chamber 2a while exhausting more, and the inside of the pulling furnace 2 is replaced with an Ar atmosphere. Thereafter, the heater 5 is operated to melt the silicon polycrystalline raw material P filled in the crucible 4 to obtain a raw material melt M.

  Next, by pulling up the pulling wire 9 by the wire winding mechanism 10, the seed crystal 8 attached to the seed chuck 8 is lowered to the surface of the silicon melt M and immersed as shown in FIG. Thereafter, the pulling wire 9 is gradually wound by the wire winding mechanism 10 to pull up the silicon single crystal S as shown in FIG. 4, and the silicon single crystal S grows into a cone portion (expanded portion) S0. When the target diameter is reached through the process, the straight body part (constant diameter part) S1 is grown.

  When the straight body portion S1 reaches the set length, the crucible support shaft drive mechanism 6 starts to raise the crucible support shaft 3, thereby speeding up the silicon single crystal S as shown in FIG. Then the crucible 4 is raised.

  When the crucible 4 rises to a predetermined height, the crucible support shaft drive mechanism 6 raises the crucible support shaft 3 and the wire take-up mechanism 10 winds the pull-up wire 9. Thereafter, the crucible support shaft 3 is lowered by the crucible support shaft drive mechanism 6 to lower the crucible 4, and the silicon single crystal S is separated from the raw material melt M as shown in FIG.

  FIGS. 7A to 7D show the process of changing the shape of the growth surface (interface with the raw material melt) of the silicon single crystal S. FIG. The growth surface of the silicon single crystal S when growing the straight body portion S1, that is, the shape of the interface with the raw material melt M is an upward convex shape as shown in FIG. 4 starts to increase at the same speed as the pulling speed of the silicon single crystal S, the pulling of the silicon single crystal S substantially stops (the crucible 4 and the silicon single crystal S stop moving relative to each other in the vertical direction). The upward convex shape of the growth surface of the single crystal S is gradually relaxed as shown in FIG. When this substantially stopped state is maintained for a predetermined time, the shape of the growth surface of the silicon single crystal S gradually changes to a downward convex shape as shown in FIG. Then, the growth surface of the silicon single crystal S is separated from the raw material melt M in a state in which the shape of the growth surface of the silicon single crystal S is a downward convex shape, so that the undulation of the raw material melt M is suppressed as much as possible. Made. Since the undulation of the raw material melt M associated with the separation of the silicon single crystal S is small, the silicon single crystal S can be separated from the raw material melt M while the silicon single crystal S is kept in a transitionless state.

  As described above, according to this manufacturing method, after growing the straight body portion S1 of the silicon single crystal S, the same speed as the pulling speed of the silicon single crystal S in which the crucible 4 containing the raw material melt M is grown is grown. , The pulling up of the silicon single crystal S can be substantially stopped without significantly changing the thermal history of the silicon single crystal S. In this state, the silicon single crystal S from the raw material melt M can be stopped. By performing the separation, the shape of the growth surface (lower end surface) of the silicon single crystal S can be made a downward convex shape, so that the silicon single crystal S can be separated from the raw material melt M in a non-transitional state, and silicon Transfer-free separation of the single crystal S from the raw material melt M can be performed with good reproducibility.

  In the above example, the rise of the crucible 4 and the silicon single crystal S is stopped, and then the crucible 4 is lowered to separate the silicon single crystal S from the raw material melt M. Alternatively, the silicon single crystal S may be further lifted to separate it.

Sectional drawing which shows the example of the form of the manufacturing apparatus used when manufacturing a silicon single crystal with the manufacturing method of this invention Sectional drawing which shows the example of the form of the manufacturing apparatus used when manufacturing a silicon single crystal with the manufacturing method of this invention Sectional drawing which shows the example of the form of the manufacturing apparatus used when manufacturing a silicon single crystal with the manufacturing method of this invention Sectional drawing which shows the example of the form of the manufacturing apparatus used when manufacturing a silicon single crystal with the manufacturing method of this invention Sectional drawing which shows the example of the form of the manufacturing apparatus used when manufacturing a silicon single crystal with the manufacturing method of this invention Sectional drawing which shows the example of the form of the manufacturing apparatus used when manufacturing a silicon single crystal with the manufacturing method of this invention (A)-(d) is explanatory drawing which shows the process of the shape change of the growth surface of a silicon single crystal.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Manufacturing apparatus 2 Pulling furnace 3 Crucible support shaft 4 Crucible 5 Heater 6 Crucible support shaft drive mechanism (crucible drive mechanism)
7 Seed crystal 8 Seed chuck 9 Pulling wire 10 Wire winding mechanism (single crystal pulling mechanism)
11 Controller M Silicon melt S Silicon single crystal S1 Straight body

Claims (4)

A method for producing a silicon single crystal by the Czochralski method,
After growing the straight body portion of the silicon single crystal, the crucible containing the raw material melt of the silicon single crystal is raised at the same speed as the pulling speed of the silicon single crystal, and then the silicon single crystal is extracted from the raw material melt. A method for producing a silicon single crystal, wherein the crystal is separated. An apparatus for producing a silicon single crystal by the Czochralski method,
A crucible drive mechanism for moving the crucible containing the raw material melt up and down;
A single crystal pulling mechanism for pulling up while growing a silicon single crystal from the raw material melt in the crucible;
After growing the straight body portion of the silicon single crystal, the crucible drive mechanism and A control device for controlling the operation of the single crystal pulling mechanism;
An apparatus for producing a silicon single crystal, comprising:   The program for implement | achieving the said control apparatus with which the manufacturing apparatus of Claim 2 is provided using a computer.   A computer-readable recording medium on which the program according to claim 3 is recorded.

Images