JPH05194078A - Apparatus for pulling up silicon single crystal - Google Patents

Abstract

PURPOSE:To suppress the growth of facet and improve the distribution of resistivity in the cross section of a silicon single crystal. CONSTITUTION:The objective apparatus for the pulling-up of a silicon single crystal is provided with a quartz crucible 11 for holding molten silicon 12, a pulling mechanism 14 for pulling up a silicon single crystal rod 13 from the molten silicon 12 and a screen 15 covering exclusively the lower end of the silicon single crystal rod 13 pulled up with the pulling mechanism 14. Since the upper part of the silicon single crystal rod 13 is not covered by the screen 15, the grown crystal at the upper part of the rod is heated by the radiant heat from the whole liquid surface in the quartz crucible 11 to keep the temperature of the growing interface at a high temperature. The facet growth on the pulled-up silicon single crystal rod 13 is suppressed and the distribution of resistivity in the cross section is improved by this process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for pulling single crystal silicon by the Czochralski method.

[0002]

2. Description of the Related Art A conventional single crystal silicon pulling apparatus is disclosed in, for example, Japanese Examined Patent Publication No. 57-40119. This device covers the space in contact with the melt, crucible and crucible receiver with a conical screen during crystal pulling.

This screen prevents radiation of heat from the silicon melt to the growing silicon rod, and also prevents reaction with carbon monoxide from carbon parts such as heaters and crucible receivers.

[0004]

However, in such a conventional apparatus for pulling up single crystal silicon, when pulling up antimony-doped single crystal silicon, for example, oxides from which antimony is evaporated fall down and the single crystal is removed. Crystals collapsed and facet growth occurred, resulting in large variations in the resistivity distribution in the cross section.

Therefore, the present inventor found out that facet growth can be prevented by not keeping the grown crystal warm but keeping it warm to prevent the temperature of the growth interface from being drastically lowered. Therefore, the present invention is to provide a pulling apparatus for single crystal silicon having an improved resistivity distribution in a cross section.

[0006]

SUMMARY OF THE INVENTION The present invention provides a single crystal silicon pulling apparatus including a quartz crucible for holding a crystal melt and a pulling mechanism for pulling a single crystal silicon rod from the crystal melt. The single crystal silicon pulling apparatus is provided with a screen that covers only the lower end portion of the single crystal silicon rod pulled up by the pulling mechanism.

[0007]

In the single crystal silicon pulling apparatus according to the present invention, the screen covers only the lower end portion of the single crystal silicon rod, and the upper end portion of the silicon rod is not covered by the screen. The crystal grown on the upper end side is warmed by the radiant heat from the entire liquid surface of the quartz crucible, and the temperature of the growth interface is kept high. As a result, facet growth in the pulled single crystal silicon rod is suppressed, and the resistivity distribution in the cross section is improved.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a single crystal silicon pulling apparatus according to an embodiment of the present invention.

As shown in this figure, a silicon melt 12 is held in a quartz crucible 11, and a pulling mechanism 14 for pulling up a single crystal silicon rod 13 is arranged above the quartz crucible 11. Has been done. The quartz crucible 11 and the pull-up mechanism 14 have the same structure as those conventionally known, and the quartz crucible 11 is rotatable and is heated by a heater.

A conical screen 15 is disposed above the silicon melt 12 and close to the surface of the melt, and a single crystal silicon rod 13 is directed upward through a lower end opening 15A of the screen 15. It is a structure that can be raised. In this case, the lower end opening 15A has a diameter larger than that of the conventional device (for example, 145 mm) to define a predetermined gap with the outer peripheral surface of the single crystal silicon rod 13.

The height of the screen 15 is lower than the upper end of the inner wall of the quartz crucible 11 (for example, 3).
5 mm) and is suspended from and supported by the ring support 17 by the three wires 16 or rods made of tantalum. The screen 15 is made of molybdenum.

Therefore, in this apparatus, the single crystal silicon rod 13 is pulled up from the silicon melt 12 in the quartz crucible 11 under atmospheric pressure (100 l / min) by the pulling mechanism 14 holding the seed crystal. It is a thing. Therefore, the evaporation product does not fall on the liquid surface or the growth interface and the single crystal is not broken. In this case, the pulling speed of the single crystal silicon rod 13 is the maximum speed when the single crystal silicon is solidified. Alternatively, the temperature should be raised at the temperature of the last minute to solidify. The central part of the grown crystal is completely maintained in a convex state and is pulled up. This prevents the antimony atoms from being abruptly aligned at the same position when pulling the antimony-doped single crystal silicon. Then, the temperature of the growth interface of this grown crystal is maintained at a high temperature. By maintaining the temperature of the grown crystal without cooling it rapidly, facet growth is prevented.

2 to 4 show the results of pulling single crystal silicon by this pulling apparatus. That is, antimony doping is 4 inches, and the growth orientation is <111> silicon pulling. In the case of FIG. 2, the lifting speed is 1.2-
It is 1.4 mm / min, and in the case of FIG. 3, it is 1.1 mm / min.
As shown in FIG. 2, when vertical strut striation observation is performed on a portion 70 mm from the TOP of the pulled single crystal silicon rod 13, facet growth disappears completely in the portion 30 to 70 mm from the TOP. When the slice resistivity and RRG (in-plane resistivity distribution) measurement in this case are performed, the measurement results are as shown in FIG. In addition, as shown in FIG.
As for the portion of 0 to 250 mm, as a result of vertical striation observation, facet growth with a width of 20 mm is observed in the central portion. The RRG shown in FIG. 4 is represented by {(peripheral resistivity-center resistivity) / center resistivity} × 100.

[0014]

According to the present invention, facet growth can be suppressed when pulling single crystal silicon, and the in-plane resistivity distribution can be improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a schematic configuration of a single crystal silicon pulling apparatus according to an embodiment of the present invention.

FIG. 2 is a view showing vertical striations of a single crystal showing an example of a pulling result using the pulling apparatus according to the embodiment of the present invention.

FIG. 3 is a diagram showing longitudinal striations of a single crystal showing an example of a result of pulling using the pulling apparatus according to the embodiment of the present invention.

FIG. 4 is a graph showing a resistance distribution measurement result in the case of FIG. 2 in pulling up using the pulling up device according to the embodiment of the present invention.

[Explanation of symbols]

 11 Quartz crucible 12 Crystal melt 13 Single crystal silicon rod 14 Pulling mechanism 15 Screen

Claims (1)

[Claims] 1. A single crystal silicon pulling apparatus comprising a quartz crucible for holding a crystal melt and a pulling mechanism for pulling a single crystal silicon rod from the crystal melt. An apparatus for pulling up single crystal silicon, comprising a screen that covers only the lower end of the single crystal silicon rod.