JPH0791149B2 - Single crystal silicon swing width detection method in CZ furnace - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a single crystal silicon swing width detection method in a CZ furnace, which is used for a single crystal silicon oscillation prevention control in the CZ furnace.

(Prior art and its problems) In recent years, as the capacity of CZ furnaces has increased, wire systems that are less susceptible to microvibrations and that can set the furnace height low,
That is, a method is mainly adopted in which a seed crystal is hung on the tip of a wire through a jig and the generated single crystal silicon is raised while winding the wire.

However, in the above wire system, the single crystal silicon is likely to swing due to misalignment between the rotation center of the wire (in other words, the rotation center of the single crystal silicon) and the rotation center of the crucible (in other words, the rotation center of the silicon solution). Due to this, deterioration of the single crystal occurs, and in the worst case, polycrystallization and deterioration (deformation) of the shape occur.

Therefore, it is necessary to perform rocking prevention management of the single crystal sinchon in the CZ furnace, and for that purpose, a swing width detection means of the single crystal silicon in the CZ furnace is required, but conventionally, a simple and suitable means is available. It was not suggested.

In addition, as a method of measuring the swing width (shake width) of an object,
A method of performing image processing with a two-dimensional camera and obtaining the displacement of a reference point of an object (such as the center of rotation in the case of a rotating body) is generally used. Due to the large scale, a single-crystal silicon swing width detecting device using a two-dimensional camera has not been put into practical use. The present invention has been made under the above circumstances.

(Means for Solving Problems) The present invention employs the following technical means for solving the above problems.

That is, the two high-intensity points are grasped by a one-dimensional CCD camera arranged toward the inside of the CZ furnace during single crystal growth, the intermediate point between the two high-intensity points is repeatedly detected, and the intermediate point within a certain period of time is detected. This is a detection method in which the displacement width of a point is converted into a length and the length is grasped as the swing width of single-crystal silicon in a furnace.

(Foundation of Invention and Data Processing) Hereinafter, the present invention will be described in detail with reference to the drawings.

Figure 1 is a schematic diagram of the CZ furnace during the growth of single crystal silicon.
Is a CZ furnace chamber, 2 is a crucible which is rotatably arranged in the CZ furnace chamber 1, 3 is a silicon melt in the crucible 2, 4 is a wire hanging toward the center of the crucible 2, and 5 is a wire 4. The seed crystal attached to the lower end of the seed crystal and the single crystal silicon 6 attached to the seed crystal 5 and grown.

When the CCD camera 7 is placed in the CZ furnace having the above structure,
A boundary portion between the surface of the single crystal silicon 6 and the silicon melt 3 can be grasped as a high brightness portion. For example, one-dimensional CC
According to the D camera, it is recognized as a belt-shaped ring 8 (hereinafter referred to as "fusion ring").

Therefore, when the one-dimensional CCD camera that runs the scanning line R in the diameter direction of the fusion ring 8 is used,
As shown in FIG. 2B, two points passing through the fusion ring 8 can be grasped as high brightness A and B.

The present invention is realized by grasping the high brightness A and B and performing the data processing shown in FIG.

That is, the single crystal silicon can be regarded as always swinging, and there is a swing width at that time and at that time. Therefore, in the present invention, the swing width is grasped as having one swing width within a certain time, and this is corrected during the actual operation.

For example, when there are two states shown in FIG. 4 (one is shown by a solid line and the other is shown by a virtual line), first, the respective intermediate points C = (a + b) / 2 and C ′ = (a ′ + b ′). Ask for / 2,
The swing width is calculated from these numerical values. Specifically, C, C ′, C ″, etc. are obtained within a fixed time, Max-Min of these numerical values is obtained, and this is multiplied by a length conversion constant K to obtain L = (Max-Min) × K. Is calculated, and the roundness correction amount C is further added to make (LC) the swing width.

(Example) A one-dimensional CCD camera is installed in a single crystal silicon manufacturing apparatus equipped with a crucible, and the luminance distribution is taken into a memory of a microcomputer through an interface for A / D converting the voltage of each element in the camera, The intermediate point C is calculated every 0.5 seconds from the brightness distribution data stored in the memory, and the intermediate point 2
When 0 pieces are regarded as one lot, the above-mentioned data processing is performed to obtain the runout width, and the operation is performed while correcting the runout width, the runout can be monitored and corrected easily at all times, and the quality is deteriorated (polycrystallization). ), Loss due to shape deterioration (deformation) is reduced, and the yield of single crystal silicon production is 5
It was confirmed that it improved by%.

(Effects of the Invention) As described above, the present invention is a method for detecting the swing width of single crystal silicon using a one-dimensional CCD camera, and therefore the device is small and suitable for practical use. It is possible to quickly correct the shake of single crystal silicon using
This leads to improved quality. In addition, there is an advantage that it can be used when creating an index of furnace accuracy (deviation between the wire core and the crucible core).

[Brief description of drawings]

Fig. 1 shows a schematic view of the CZ furnace, Fig. 2 (1) is an explanatory view of the fusion ring, Fig. 2 (2) is the brightness distribution of the fusion ring as seen by a one-dimensional CCD camera, and Fig. 3 is the book. FIG. 4 is a flow chart of the invention, and is an explanatory diagram of how to set an intermediate point. 6 …… Single crystal silicon 7 …… CCD camera A, B …… High brightness point

Claims (1)

[Claims] 1. A two-dimensional high-intensity point is grasped by a one-dimensional CCD camera arranged toward the inside of a CZ furnace during single crystal growth, and an intermediate point between the two high-intensity points is repeatedly detected, and within a fixed time. A method for detecting a single crystal silicon swing width in a CZ furnace, which comprises converting a displacement width of the intermediate point into a length and grasping the length as a swing width of the single crystal silicon in the furnace.