JPS61242983A - Production of semiconductor single crystal rod - Google Patents

Abstract

PURPOSE:To eliminate the cutting loss in the slicing of wafers and to improve the yield in the growth of a single crystal rod by pulling-up process of floating zone process, by inclining the seed crystal rod from the principal crystal orientation by a necessary angle. CONSTITUTION:In the growth of a single crystal rod by the pulling-up process or floating zone process, the seed crystal having a crystal axis deviated slightly from the <100> or <111> plane is used as the seed. The deviation is 4+ or -2 deg. from the <100> plane or 3+ or -1 deg. from the <111> plane. A wafer having principal plane inclined from the <100> or <111> plane by 4 deg. or 3 deg. can be produced by slicing the single crystal rod grown from the seed crystal nearly perpendicularly to the axis of growth.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing semiconductor single crystal rods, such as silicon, germanium, compound semiconductor single crystal rods, etc., by a pulling method or a floating zone method. The present invention relates to a method using a seed crystal with a specified crystal orientation.

A method of growing single crystal bars of silicon, germanium, etc. by the Czochralski method is well known, and a method of growing a single crystal rod of silicon, germanium, etc. by the Czochralski method is also known. (LEC method) is also well known. The floating zone method (FZ method) is known as a method for growing silicon single crystals, especially when the purpose is to achieve high purity.

In these cases, single crystal rods usually have a main growth axis e.g. <1
After being pulled up along the 00> or (111) direction, the wafers are cut into wafers and subjected to processes such as etching and mirror polishing to be used for processing semiconductor devices.

Depending on the target semiconductor device, this single crystal wafer may have a crystal plane whose main surface is slightly inclined from the (100) or (111) plane, in other words, the main growth axis. 4° for (100) crystal wafers, (1
11) For crystalline wafers, a tilt of 3" is required. In this case, when cutting the wafer from a single crystal bar, the crystal orientation of the wafer is of course tilted by 4° or 3° from the main axis, respectively. It is necessary to cut - this oblique cutting is accompanied by a loss of single crystal, e.g.

When a single crystal with diameter d is cut at a cutting angle of 4°, the cutting loss is expressed as L=d tan4@.

When d is 150 mm, L is 10.5 m+, and when d is 200 mm, L is 14.0 mm. This loss increases as the diameter of the wafer increases, and the impact on the cost of the product is extremely large.

. In order to solve the above-mentioned disadvantages, the present invention provides a crystal tilted by 4 degrees from the (100) orientation, which is the most demanding in semiconductor devices, and a crystal tilted by 3 degrees from the (111) orientation. This was done as a result of various studies on how to obtain a good crystal orientation, and is based on the knowledge that this objective can be achieved by using the seed crystal rod itself at a required angle from the main crystal orientation. In other words, in the method of growing single crystal rods by the pulling method or the floating zone method, the direction of the crystal axis is <i
This method of manufacturing a semiconductor single crystal rod is characterized in that a seed crystal having an orientation slightly tilted from the oo> orientation or the (111) orientation is used.

Slightly tilting from the (100) direction or (111) direction means ±2'' with a center of 4 degrees, respectively.
If the slope is outside these ranges, it will be tilted in the <100> direction or (11) as in the conventional method.
1) There is no significant difference in yield compared to the method of pulling and cutting using a seed crystal that is precisely cut within ±30' from the orientation.

Next, the present invention will be described in more detail using a method of pulling a silicon single crystal rod as an example. First, as shown in Figure 1, (00
1) Silicon single crystal with main axis (001)
A seed crystal rod with a thickness of 110 m 1 x 10 ++ and a length of 60 m + was produced by cutting it at an angle of 4 inches toward the (100) direction.Next, this was fixed to the seed holding part of the pulling machine and placed in a quartz crucible. A silicon single-crystal rod with a diameter of 125 m was grown by lifting it into a plug immersed in molten silicon.When this silicon single-crystal rod was cut almost perpendicular to the growth axis to cut out wafers, all wafers were (0013
It was tilted 4@ in the (100) direction, and there was no cutting loss at all. As shown in Figure 2, this slope is determined by the distances a, b, b', C
It was clearly recognized that there is a relationship between a(b"b'(c).

Further, during this crystal growth, striations caused by impurity unevenness had a concentric circular shape with respect to the crystal growth axis. On the other hand, as in the conventional method, a crystal rod grown by pulling the crystal growth axis in the (100) ± 30' direction,
No concentric striations were observed in the wafer cut at an angle of 4° from the main axis, which clearly differed from the one according to the present invention.

In addition, in the above example, even when using a seed crystal whose crystal axis direction is tilted by 3 degrees from the (III) direction, the intervals between the habit lines are different, and concentric striations are observed. A single crystal rod was obtained.

In the method of the present invention, when pulling and growing a single crystal rod of silicon, germanium, etc. from a melt using a seed crystal using the Czochralski method, the method of the present invention can be used to grow a single crystal rod of silicon, germanium, etc. from a melt using a liquid confinement method (LEC method). This method is advantageously applied when pulling and growing a compound semiconductor rod such as, for example, a silicon single crystal rod using the floating zone single crystal growth method.

According to the method of the present invention, a seed crystal that is slightly tilted from the (100) direction or the (111) direction is used as the seed crystal used in the pulling method from the melt or the floating zone method. By doing so, a single crystal rod having the desired crystal orientation can be obtained, so that there is no cutting loss when cutting out the wafer, and single crystal wafers can be manufactured with a high yield.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the crystal axis direction of a seed crystal according to the present invention, and FIG. 2 is a cross-sectional view showing the spacing between habit lines of a single crystal rod in an example. Patent applicant: Shin-Etsu Semiconductor Co., Ltd. 011 in Figure 1 Figure 2

Claims (1)

[Claims] 1) A seed crystal whose crystal axis direction is slightly inclined from the <100> direction or the <111> direction, in a method of growing a single crystal rod by a pulling method or a floating zone method. A method for manufacturing a semiconductor single crystal rod, characterized by using. 2) The method according to claim 1, characterized in that a seed crystal whose crystal axis direction is tilted by 4° or ±2° from the <100> orientation is used. 3) The method according to claim 1, characterized in that a seed crystal whose crystal axis direction is tilted by 3° or ±1° from the <111> orientation is used.