JP3642691B2 - Single crystallization automatic discrimination method and semiconductor single crystal manufacturing apparatus using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an automatic determination method for single crystallization of a semiconductor crystal in a seed process of a semiconductor single crystal manufacturing method by a CZ method (Czochralski method), and a semiconductor single crystal manufacturing apparatus configured using this method.
[0002]
[Prior art]
An apparatus using a CZ method is known as an apparatus for manufacturing a single crystal of a semiconductor such as silicon. In this CZ method, rod-shaped polycrystalline silicon is crushed and put into a quartz glass crucible and melted. A seed crystal (seed) as a core is suspended in the melt and immersed in the melt, and the seed crystal is slowly rotated. While pulling up, a single crystal is grown from the tip of the seed crystal.
[0003]
By the way, when the single crystal pulling process in the CZ method is subdivided, the seed crystal is immersed in the melt and the seed crystal is grown from the tip of the seed crystal, and the dislocation of the single crystal is made subsequent to the seed process. In order to achieve this, it can be divided into a neck process in which the crystal diameter is narrowed and a predetermined distance is raised, and a body process in which a large single crystal as a product is stably grown following the neck process. When shifting from the seed process to the neck process, it is necessary to accurately determine whether or not the single crystal has stably grown from the tip of the seed crystal in the seed process.
[0004]
Conventionally, the determination of the single crystallization of the silicon crystal for the transition from the seed process to the neck process is performed by the operator looking into the crucible through the transparent window and the seam line (crystal habit line) peculiar to the single crystal on the crystal surface. Appearance was confirmed by visual inspection.
[0005]
FIGS. 15A and 15B show examples of images when the seam line appears and does not appear. In these drawings, 1 is a seed crystal, 2 is a melt surface of polycrystalline silicon heated and melted, 3 is a meniscus of a silicon crystal grown from the tip of the seed crystal 1, and 4 is a seam line appearing on the crystal surface. . Conventionally, by manually confirming that a seam line 4 indicating single crystallization as shown in FIG. 15A has appeared on the crystal surface, it is manually controlled so as to shift from the seed process to the neck process. It was. The number of seam lines appearing on the crystal surface is a specific number determined by the crystal orientation.
[0006]
[Problems to be solved by the invention]
However, the conventional method for visually confirming the appearance of the seam line as described above has the following technical problems.
(1) Visual confirmation is extremely burdensome for the operator.
(2) It is difficult to automate the transition timing from the seed process to the neck process.
(3) Since it takes time for the single crystal to grow and the seam line to appear after the seed crystal is immersed in the melt, it is necessary for the operator to perform monitoring at regular intervals.
(4) If the timing of monitoring does not match, it will be left as it is despite the appearance of seam lines, leading to a decrease in throughput, an increase in power consumption, and deterioration of members.
[0007]
The present invention has been made to solve the technical problems as described above. By detecting the appearance of a seam line by image processing, it is possible to automatically determine single crystallization of a semiconductor crystal in a seed process. It is an object of the present invention to provide an automatic single crystallization discrimination method and a semiconductor single crystal manufacturing apparatus configured using this method.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, an automatic single crystallization discrimination method according to claim 1 of the present invention is a semiconductor single crystal manufacturing method according to the CZ method. In crystallization determination, the seed crystal and the melt surface portion are photographed by the imaging means, and a horizontal reference position line for distance measurement set in advance in the photographed image and the lowermost end portion of the meniscus of the semiconductor crystal photographed by the imaging means, Is calculated by image processing, and is detected as the appearance of a seam line indicating single crystallization when the distance falls below a preset threshold value.
[0009]
In such a configuration, the appearance of a seam line indicating single crystallization is automatically detected from the change in the distance between the horizontal reference position line set in the captured image and the lowermost end of the meniscus of the semiconductor crystal. It is possible to automatically determine whether or not single crystallization of the semiconductor crystal has been achieved.
[0010]
The method for automatically determining single crystallization according to claim 2 of the present invention is a method for manufacturing a semiconductor single crystal by a CZ method. In the method for determining single crystallization of a grown crystal for transition from a seed process to a neck process, an imaging means is used. The seed crystal and the melt surface portion are photographed, and an image of the seed crystal and the melt surface portion in a state where the seam line appears is prepared as a comparison pattern in advance, and the seed crystal and the melt surface portion photographed by the imaging means are prepared. Appearance of a seam line indicating single crystallization is detected by performing pattern matching between the captured image and the comparison pattern.
[0011]
With such a configuration, it is possible to automatically detect the appearance of a seam line indicating single crystallization by pattern matching between a captured image of the seed crystal and the melt surface portion and a comparison pattern, and the single crystal of the semiconductor crystal It is possible to automatically determine whether or not conversion has been achieved.
[0012]
According to a third aspect of the present invention, there is provided a method for automatically determining a single crystallization according to a third aspect of the present invention, in the method for manufacturing a semiconductor single crystal by the CZ method. The seed crystal and the melt surface portion are photographed, and the number of pixels of the meniscus portion of the semiconductor crystal in the photographed images of the seed crystal and the melt surface portion photographed by the imaging means is counted by image processing. When the threshold value is exceeded, it is detected as the appearance of a seam line indicating single crystallization.
[0013]
With such a configuration, it is possible to automatically detect the appearance of a seam line indicating single crystallization from the change in the number of pixels of the meniscus portion of the semiconductor crystal in the photographed images of the seed crystal and the melt surface portion, It is possible to automatically determine whether or not single crystallization of the semiconductor crystal has been achieved.
[0014]
According to a fourth aspect of the present invention, there is provided an automatic single crystallization discrimination method according to a method of manufacturing a semiconductor single crystal by a CZ method, wherein an imaging means is used for determining single crystallization of a grown crystal for shifting from a seed process to a neck process. The seed crystal and the melt surface part are photographed, a measurement line is set in advance on the photographed image so as to cross the meniscus part of the semiconductor crystal, and the meniscus in the photographed image of the seed crystal and the melt surface part photographed by the imaging means is set. Measure the change in luminance at the intersection point where the outer line and the measurement line intersect,
When the luminance change exceeds a predetermined threshold, it is detected as the appearance of a seam line indicating single crystallization.
[0015]
With such a configuration, it is possible to automatically detect the appearance of a seam line indicating single crystallization from the change in luminance at the intersection point where the outer line of the meniscus and the measurement line intersect, and the single crystallization of the semiconductor crystal It can be automatically determined whether or not is achieved.
[0016]
The semiconductor single crystal manufacturing apparatus according to claim 5 of the present invention is a semiconductor single crystal manufacturing apparatus based on the CZ method, and includes an imaging means for imaging a seed crystal and a melt surface portion in a crucible through a fluoroscopic window, and a captured image in advance. The distance between the set horizontal reference position line for measuring the distance and the lowest end of the meniscus of the semiconductor crystal in the captured image taken by the imaging means is calculated by image processing, and the distance is preset. An automatic single crystallization discriminating apparatus for detecting the appearance of a seam line indicating single crystallization when the threshold value is below the threshold value, and a processing step of the semiconductor single crystal manufacturing apparatus according to the discrimination result of the single crystallization automatic discriminating apparatus. It is configured by providing a control means for automatically shifting from the seed process to the neck process.
[0017]
In such a configuration, the appearance of a seam line indicating single crystallization is automatically detected from the change in the distance between the horizontal reference position line set in the captured image and the lowermost end of the meniscus of the semiconductor crystal. Thus, it is possible to obtain a semiconductor single crystal manufacturing apparatus that can automatically determine whether or not single crystallization of a semiconductor crystal has been achieved and shift from a seed process to a neck process.
[0018]
In the semiconductor single crystal manufacturing apparatus according to claim 6 of the present invention, in the semiconductor single crystal manufacturing apparatus based on the CZ method, an imaging means for photographing the seed crystal and the melt surface portion in the crucible through the transparent window, and a seam line appear in advance. An image of the seed crystal and the melt surface portion in the prepared state is prepared as a comparison pattern, and a pattern matching is performed between the captured image of the seed crystal and the melt surface portion taken by the imaging means and the comparison pattern. An automatic single crystallization discriminating device for detecting the appearance of a seam line indicating crystallization, and a process of the semiconductor single crystal manufacturing apparatus is automatically shifted from the seed process to the neck process according to the discrimination result of the single crystallization automatic discriminating apparatus. It comprises by providing a control means.
[0019]
With such a configuration, it is possible to automatically detect the appearance of a seam line indicating single crystallization by pattern matching between a captured image of the seed crystal and the melt surface portion and a comparison pattern, and the single crystal of the semiconductor crystal It is possible to obtain a semiconductor single crystal manufacturing apparatus that can automatically determine whether or not the conversion has been achieved and shift from the seed process to the neck process.
[0020]
The semiconductor single crystal manufacturing apparatus according to claim 7 of the present invention is a semiconductor single crystal manufacturing apparatus based on the CZ method, imaging means for imaging the seed crystal and the melt surface portion in the crucible through the fluoroscopic window, and imaging by the imaging means. The number of pixels of the meniscus portion of the semiconductor crystal in the photographed image of the seed crystal and the melt surface portion is counted by image processing, and a seam line indicating single crystallization is displayed when the number of pixels exceeds a predetermined threshold value. A single crystallization automatic discrimination device that detects as an appearance, and a control means that automatically shifts the processing process of the semiconductor single crystal manufacturing apparatus from the seed process to the neck process according to the discrimination result of the single crystallization automatic discrimination apparatus It is a thing.
[0021]
With such a configuration, it is possible to automatically detect the appearance of a seam line indicating single crystallization from the change in the number of pixels of the meniscus portion of the semiconductor crystal in the photographed images of the seed crystal and the melt surface portion, It is possible to obtain a semiconductor single crystal manufacturing apparatus that can automatically determine whether or not single crystallization of a semiconductor crystal has been achieved and shift from a seed process to a neck process.
[0022]
The semiconductor single crystal manufacturing apparatus according to claim 8 of the present invention is a semiconductor single crystal manufacturing apparatus according to the CZ method, wherein an imaging means for imaging a seed crystal and a melt surface portion in a crucible through a fluoroscopic window, and a captured image in advance. A measurement line that crosses the meniscus portion of the semiconductor crystal is set, and a change in luminance at the intersection point where the outline of the meniscus in the photographed image of the seed crystal and the melt surface portion taken by the imaging means intersects the measurement line A single crystallization automatic discriminating device that detects the appearance of a seam line indicating single crystallization when the luminance change exceeds a predetermined threshold, and a semiconductor according to the discrimination result of the single crystallization automatic discriminating device It comprises a control means for automatically shifting the processing process of the single crystal manufacturing apparatus from the seed process to the neck process.
[0023]
With such a configuration, it is possible to automatically detect the appearance of a seam line indicating single crystallization from the change in luminance at the intersection point where the outer line of the meniscus and the measurement line intersect, and the single crystallization of the semiconductor crystal Thus, it is possible to obtain a semiconductor single crystal manufacturing apparatus that can automatically determine whether or not has been achieved and shift from the seed process to the neck process.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
1 to 5 show a first embodiment of a silicon single crystal manufacturing apparatus configured by applying the present invention. 1 is an overall configuration diagram of a silicon single crystal manufacturing apparatus, FIG. 2 is a diagram illustrating an example of a circuit configuration of a single crystallization automatic discrimination apparatus in FIG. 1, FIG. 3 is a diagram illustrating a monitor screen for explaining operations, and FIG. FIG. 5 is a diagram showing a change characteristic of the distance from the lower edge of the monitor screen to the lowest end of the silicon crystal meniscus.
[0025]
In the first embodiment, as shown in FIG. 3, the gap between the lower end edge of the screen on the monitor screen 26 in which the seed crystal 1 and the melt surface 2 are photographed and the lowermost end portion of the meniscus 3 of the silicon crystal. The distance L is calculated by image processing, and when the distance L is equal to or less than a preset threshold value, it is detected that the seam line 4 indicating single crystallization has appeared. In the first embodiment, the horizontal reference position line for measuring the distance L is set at the lower end edge of the monitor screen 26. However, if the horizontal reference position line is below the meniscus 3, Any position on the monitor screen may be set.
[0026]
In FIG. 1, 11 is a crucible made of quartz glass, 12 is a graphite heater arranged around it, 13 is a crucible rotating mechanism, and 14 is a crucible raising / lowering mechanism.
[0027]
The crucible 11 is surrounded by a vacuum vessel 15, and a seed crystal elevating mechanism 16 composed of a motor, a winding drum and the like is installed at the upper end of the neck of the vacuum vessel 15, and the stainless steel connected to the elevating mechanism 16. A seed chuck 18 for holding the seed crystal 1 is attached to the tip of the wire 17 made of the metal. A seed crystal rotating mechanism 19 is provided below the seed crystal lifting mechanism 16, and the seed crystal lifting mechanism 16 is rotated by the seed crystal rotating mechanism 19 to be suspended from the tip of the wire 17. The seed crystal 1 can be rotated.
[0028]
A transparent quartz glass see-through window 20 is formed on the shoulder of the vacuum vessel 15, and image pickup means such as a CCD camera 21 is installed in the crucible 11 in this window portion. The CCD camera 21 obtains a photographed image as shown in FIG. 3 by photographing the seed crystal 1 and the melt surface 2 from obliquely upward when pulling up the silicon single crystal.
[0029]
Reference numeral 22 denotes a camera control unit, reference numeral 23 denotes a monitoring television monitor for displaying a photographed image of the CCD camera 21, and reference numeral 24 denotes single crystallization by image processing from the photographed image of the CCD camera 21 sent via the camera control unit 22. An automatic single crystallization discriminating device 25 for detecting the appearance of seam lines, 25 is a crucible rotating mechanism 13, a crucible lifting / lowering mechanism 14, a seed crystal lifting / lowering mechanism 16, a seed crystal rotating mechanism 19, etc. This is a single crystal pulling control device for comprehensively performing operation, temperature control of the heater 12, and the like.
[0030]
The single crystallization automatic discrimination device 24 has a circuit configuration as shown in FIG.
That is, in FIG. 2, reference numeral 241 denotes a video signal sent from the CCD camera 21 with a predetermined threshold value V. _S Comparator for pulsing and outputting at 240, a pulse width discriminating circuit for removing a pulse signal having a pulse width equal to or less than a predetermined pulse width, and a signal 243 for extracting a horizontal synchronizing signal (H signal) from a video signal Reference numeral 244 denotes a V signal extraction circuit that extracts a vertical synchronization signal (V signal) from the video signal, 245 denotes an H signal pulse counter that counts an H signal pulse output from the H signal extraction circuit 243, and 246 denotes a horizontal scanning line. The horizontal scanning line l corresponding to the lower edge of the screen of the monitor screen 26 (see FIG. 3) is counted by counting the number. _n A horizontal scanning line counter 247 for detecting the position of the V signal, 247 is a delay circuit for delaying the V signal pulse output from the V signal extraction circuit 244 for a short time, and 248 is an OR circuit.
[0031]
Reference numeral 249 denotes a count value holding circuit that reads and temporarily holds the H signal count value of the H signal pulse counter 245, and 250 calculates an average value of the H signal count value for each rotation of the silicon crystal in order to eliminate a detection error. An average value calculation circuit 251 indicates a distance L between the lower end edge of the monitor screen 26 and the lowermost end portion of the meniscus 3 of the silicon crystal from the averaged H signal count value output from the average value calculation circuit 250. Calculated and the distance L is a preset threshold value L ₀ This is a determination circuit that determines that a seam line 4 indicating single crystallization has appeared on the crystal surface when the following occurs.
[0032]
Next, the detection operation of the seam line 4 in the first embodiment having the above configuration will be described. First, rod-like polycrystalline silicon as a raw material is put into a crucible 11 crushed into a block shape and melted by heating with a heater 12. The seed crystal 1 is held by the seed chuck 18 at the tip of the wire 17 and suspended in the crucible 11.
[0033]
When the manufacture of the silicon single crystal is started in this state, the wire 17 is lowered downward by the seed crystal lifting mechanism 16, and the tip of the seed crystal 1 suspended from the tip of the wire 17 is the many in the crucible 11. At the same time, the seed crystal rotating mechanism 19 and the crucible rotating mechanism 13 are driven, and the seed crystal 1 crucible 11 starts rotating slowly at a predetermined speed in the opposite direction or in the same direction. Is done. This starts the seeding process.
[0034]
The CCD camera 21 images the seed crystal 1 and the melt surface 2 through the transparent window 20, and the video signal is sent to the camera control unit 22 for monitoring as a monitor screen 26 as shown in FIG. The image is displayed on the television monitor 23 and sent to the single crystallization automatic discrimination device 24.
[0035]
An example of the waveform of the video signal sent from the CCD camera 21 is shown in FIG. In this video signal, H is a horizontal synchronizing signal (H signal), V is a vertical synchronizing signal (V signal) appearing every 1/60 seconds, and the horizontal scanning line l in FIG. ₁ ~ L _Three , L _n Is the horizontal scanning line l in the monitor screen 26 of FIG. ₁ ~ L _Three , L _n It shall be corresponding to each.
[0036]
As apparent from the monitor screen 26 of FIG. 3, when the seam line 4 appears on the surface of the silicon crystal meniscus 3, the seam line 4 portion protrudes downward from the screen. The distance L between the edge and the lowermost end of the meniscus 3 of the silicon crystal is reduced accordingly. Therefore, by monitoring this distance L, it is possible to detect whether or not a seam line 4 indicating single crystallization has appeared. The single crystallization automatic discrimination device 24 shown in FIG. 2 obtains this distance L by image processing, and the value is a predetermined threshold value L. ₀ It is detected that the seam line 4 indicating single crystallization has appeared when it becomes smaller.
[0037]
That is, the video signal sent from the CCD camera 21 is input to the comparator 241, the H signal extraction circuit 243, and the V signal extraction circuit 244 of the single crystallization automatic discrimination device 24 of FIG. The comparator 241 has a predetermined threshold V as shown in FIG. _S To determine the signal level, and as shown in FIG. _S The above signal part is 1, threshold V _S The following signal part is converted to 0 and output.
[0038]
The output pulse of the comparator 241 is sent to the pulse width discriminating circuit 242, and after removing a pulse signal having a predetermined pulse width or less as noise, it is sent to the reset terminal R of the H signal pulse counter 245 via the OR circuit 248, and the H signal It acts to reset the pulse counter 245.
[0039]
On the other hand, the H signal extraction circuit 243 extracts the H signal (see FIG. 4A) from the video signal to generate an H signal pulse, and supplies it to the count terminal C of the H signal pulse counter 245 and the horizontal scanning line counter 246. send. The H signal pulse counter 245 counts the H signal pulse every time it arrives. On the other hand, the horizontal scanning line counter 246 counts the H signal pulses, and the scanning line l corresponding to the preset lower end edge of the monitor screen 26 is counted. _n An output pulse is generated when it coincides with the scanning line number N.
[0040]
As is apparent from the above operation, the horizontal scanning line l intersecting the seam line 4 from the upper end position of the screen on the monitor screen 26 of FIG. _Three Since the pulse is always output from the comparator 241 as shown in FIG. 4B up to the position of, the H signal pulse counter 245 continues to be reset by this pulse, and the horizontal scanning line l _Three The count value is always 0 until the position is reached.
[0041]
The scanning position is the horizontal scanning line l _Three Since the horizontal scanning line only crosses the portion of the melt surface 2 of polycrystalline silicon after passing the position of, a pulse is not output from the comparator 241 as shown in FIG. As a result, the H signal pulse counter 245 is not reset, and the H signal pulse counter 245 _Three Subsequent H signal pulses are sequentially counted.
[0042]
On the other hand, the horizontal scanning line counter 246 counts the H signal pulses output from the H signal extraction circuit 243, sequentially counts the number of horizontal scanning lines of the video signal, and the count value is set in advance. Horizontal scanning line l corresponding to the lower end position of the monitor screen 26 _n When it coincides with the scanning line number N, an output pulse is generated. As a result, the count operation of the H signal pulse counter 245 is stopped.
[0043]
Therefore, the count value of the H signal pulse counter 245 at the time when the counting operation is stopped by the output pulse of the horizontal scanning line counter 246 is the horizontal scanning line l in the monitor screen 26 of FIG. _Three Horizontal scanning line l corresponding to the bottom edge of the screen from the position _n The total number of horizontal scanning lines included in the above is shown. Since the video signal sent from the CCD camera 21 is a television signal of 1 field 1/60 seconds and 1 frame 1/30 seconds, the count value of the H signal pulse counter 245 is the monitor screen of FIG. Horizontal scan line 1 at 26 _Three It indirectly represents the distance L from the bottom edge of the screen.
[0044]
When the horizontal scanning for one screen is completed and a V signal for vertical synchronization is sent into the video signal as shown in FIG. 4A, the V signal extraction circuit 244 extracts this, and the V signal is extracted. Output a pulse. The count value hold circuit 249 reads the count value of the H signal pulse counter 245 by this V signal pulse, and temporarily stores and holds it. Further, the V signal pulse is delayed for a short time by the delay circuit 247, and then sent to the reset terminal R of the H signal pulse counter 245 via the OR circuit 248. The H signal pulse counter 245 is reset and the count value is set. Return to zero.
[0045]
The H signal pulse counter 245 repeats the above operation for each screen of the video signal sent from the CCD camera 21, and each time the distance from the lower end edge of the monitor screen 26 to the lowermost end portion of the meniscus 3 of the silicon crystal. L is output as the number of horizontal scanning lines.
[0046]
By the way, the seed crystal 1 suspended from the wire 17 is slowly rotated by the seed crystal rotation mechanism 19 at a predetermined rotation speed. For this reason, the position of the seam line 4 in the monitor screen 26 of FIG. 3 also rotates slowly according to the rotation of the seed crystal 1. Accordingly, the distance L from the lower edge of the screen 26 of the monitor screen 26 to the seam line 4 also changes according to the rotational position of the seam line 4 and pulsates accordingly. Therefore, in order to prevent such erroneous detection due to rotation, the average value calculation circuit 250 calculates an average value per rotation of the seed crystal 1, and uses this average value as a measurement distance L as a distance determination circuit 251 in the subsequent stage. Send to.
[0047]
The distance determination circuit 251 includes the number of horizontal scanning lines that give the measurement distance L sent from the average value calculation circuit 250 and a predetermined distance L set in advance. ₀ For example, as shown in FIG. 5, the measured distance L is the threshold distance L. ₀ Smaller than t ₁ It is determined that a seam line 4 indicating single crystallization has appeared at that time, and a seam line detection output is generated. This detection output is sent to the single crystal pulling control device 25 of FIG.
[0048]
When the single crystal pulling control device 25 receives the detection output of the seam line, the single crystal pulling control device 25 controls the operations of the crucible rotating mechanism 13, the crucible lifting mechanism 14, the seed crystal lifting mechanism 16, and the seed crystal rotating mechanism 19, from the seed process to the neck process. The process is automatically transferred to.
[0049]
As described above, in the case of the first embodiment, the distance L between the lower end edge of the monitor screen 26 and the lowermost end portion of the meniscus 3 of the silicon crystal is calculated by image processing, and this distance L is defined. Distance L ₀ When the value is smaller than that, it is determined that the seam line 4 has appeared, and a detection output is generated. For this reason, it is possible to automatically detect whether or not the silicon crystal has become a single crystal, and by using this detection result to control the silicon single crystal manufacturing equipment, the transition from the seed process to the neck process is automated. can do.
[0050]
Note that the above monitoring is continued even after single crystallization is achieved, for example, t in FIG. ₂ As shown at the time, the distance L between the bottom edge of the monitor screen 26 and the seam line 4 is the specified distance L. ₀ If the length is longer than that, it is desirable that a warning be issued if single crystallization is broken.
[0051]
[Second Embodiment]
FIG. 6 shows a second configuration example of the single crystallization automatic discrimination device 24 for the second embodiment. The overall configuration of the silicon single crystal manufacturing apparatus is the same as that shown in FIG.
[0052]
In the second embodiment, as shown in FIG. 7, a photographed image of the seed crystal 1 and the melt surface 2 in a state where a seam line indicating single crystallization appears is prepared as a comparison pattern P in advance. Then, by comparing the comparison pattern P with the seed crystal 1 photographed by the CCD camera 21 and the photographed image of the melt surface 2 portion, it is detected whether or not a seam line 4 indicating single crystallization has appeared. It is what you do.
[0053]
In FIG. 6, reference numeral 261 denotes a binarization circuit that converts a photographed image taken by the CCD camera 21 into a binary image, and 262 denotes a frame image storage unit that stores and stores a photographed image for one frame converted into a binary image. Reference numeral 263 denotes a comparison pattern storage unit that stores in advance a comparison pattern P as shown in FIG. 7 that is a criterion for the appearance of seam lines. Reference numeral 264 denotes a captured image stored in the frame image storage unit 262 and a comparison pattern storage unit 263. This is a pattern matching unit that performs pattern matching with the comparison pattern P and detects the appearance of a seam line when the two patterns match.
[0054]
Next, the operation of the single crystallization automatic discrimination device 24 of FIG. 6 will be described.
The video signal photographed by the CCD camera 21 is converted into a binary image by the binarization circuit 261 and sent to the frame image storage unit 262. The frame image storage unit 262 stores and stores an image for one frame of the seed crystal 1 and the melt surface 2 portion as shown in FIG. 8 converted into the binary image.
[0055]
A captured image composed of binary images stored in the frame image storage unit 262 is sent to the pattern matching unit 264, and is pattern-matched with a comparison pattern P as shown in FIG. If the two patterns match, it is determined that the seam line 4 has appeared in the silicon crystal, and a detection output of the seam line 4 is generated and sent to the single crystal pulling control device 25 in FIG.
[0056]
When receiving the detection output of the seam line, the single crystal pulling control device 25 controls the operation of the crucible rotating mechanism 13, the crucible lifting mechanism 14, the seed crystal lifting mechanism 16, and the seed crystal rotating mechanism 19, from the seed process to the neck process. The process is automatically transferred to.
[0057]
As described above, in the case of the second embodiment, the appearance of the seam line 4 is detected by pattern matching between the captured image and the comparison pattern. For this reason, it is possible to automatically detect whether or not the silicon crystal has become a single crystal, and by using this detection result to control the silicon single crystal manufacturing equipment, the transition from the seed process to the neck process is automated. can do.
[0058]
In the example of FIG. 6, the case where the captured image is converted into a binary image is illustrated for the sake of simplicity. However, a multi-value quantization circuit is used instead of the binarization circuit 261, and the captured image is converted into 3 images. It may be converted into a multi-valued image having a value or higher. When converted to a multi-valued image, pattern matching takes time, but detection accuracy is improved accordingly.
[0059]
In the case of the second embodiment as well, the above monitoring is continued even after the single crystallization is achieved once, and if the pattern matching results do not match, an alarm is given that the single crystallization has broken. It is desirable to make it emit.
[0060]
[Third Embodiment]
FIG. 9 shows a third configuration example of the single crystallization automatic discrimination device 24 for the third embodiment. The overall configuration of the silicon single crystal manufacturing apparatus is the same as that shown in FIG.
[0061]
In the third embodiment, as shown in FIG. 10, in the monitor screen 26 in which the seed crystal 1 and the melt surface 2 portion are photographed, the silicon crystal meniscus 3 and seam line 4 portions shown by hatching are shown. The total number of pixels is counted, and when the number of pixels exceeds a predetermined threshold value, the appearance of the seam line 4 is detected.
[0062]
In FIG. 9, reference numeral 271 denotes a multi-value conversion circuit for converting a video signal into a multi-value image. The image area separating unit 273 for separating the pixels counts the number of pixels of the separated meniscus 3 portion and the seam line 4 portion, and 274 compares the counted number of pixels with a preset threshold value. It is a pixel number comparison unit that detects the appearance of the seam line 4.
[0063]
Next, the operation of the single crystallization automatic discrimination device 24 of FIG. 9 will be described.
A video signal photographed by the CCD camera 21 is converted into a multi-value image by a multi-value conversion circuit 271 and sent to an image region separation unit 272. The image region separation unit 272 performs image analysis on the sent multi-valued image using various characteristics such as luminance difference and color difference, and the region in each part of the seed crystal 1, the melt surface 2, the meniscus 3, and the seam line 4. To separate. This region separation result is sent to the pixel number counting unit 273. The pixel number counting unit 273 counts the number of pixels included in the meniscus 3 and the seam line 4 shown by hatching in FIG. 10 using the region separation result, and sends the counted number to the pixel number comparing unit 274.
[0064]
The pixel number comparison unit 274 compares the number of transmitted pixels with a preset threshold value, and determines that the seam line 4 has appeared when the number of transmitted pixels is greater than the threshold value. , Generate seam line detection output. That is, in FIG. 10, when the seam line 4 appears, the area of the hatched portion increases as the seam line 4 appears and protrudes outward, and the number of pixels increases accordingly. Become. Therefore, the change in the number of pixels when the seam line 4 appears and when it does not appear is as shown in FIG. 11, for example, and a dotted line C without a seam line and a solid line D with a seam line. If the threshold value of the pixel number comparison unit 274 is set per intermediate position, the appearance of the seam line 4 can be detected from the change in the number of pixels.
[0065]
The detection output of the seam line output from the pixel number comparison unit 274 is sent to the single crystal pulling control device 25 of FIG. When the single crystal pulling control device 25 receives the detection output of the seam line, the single crystal pulling control device 25 controls the operation of the crucible rotating mechanism 13, the crucible lifting mechanism 14, the seed crystal lifting mechanism 16, and the seed crystal rotating mechanism 19, so that the bottleneck from the seeding process. The process is automatically transferred to the process.
[0066]
As described above, in the case of the third embodiment, the appearance of the seam line 4 is detected from the change in the number of pixels of the captured image. For this reason, it is possible to automatically detect whether or not the silicon crystal has become a single crystal, and by using this detection result to control the silicon single crystal manufacturing equipment, the transition from the seed process to the neck process is automated. can do.
[0067]
In the case of the third embodiment as well, the above monitoring is continued even after single crystallization is achieved. If the number of pixels falls below the threshold value, the single crystallization is broken. It is desirable to be configured to issue an alarm.
[0068]
[Fourth Embodiment]
FIG. 12 shows a fourth configuration example of the single crystallization automatic discrimination device 24 used in the third embodiment. The overall configuration of the silicon single crystal manufacturing apparatus is the same as that shown in FIG.
[0069]
In the fourth embodiment, as shown in FIG. 13, a measurement line E that crosses the meniscus 3 portion of the silicon crystal is set in advance on the photographed image, and the measurement line E and the outline of the meniscus 3 are The change in luminance at the intersecting point P is measured, and the appearance of the seam line 4 is detected from the change.
[0070]
That is, when the change in luminance at the intersection P position where the measurement line E and the outline of the meniscus 3 intersect is measured for a rotating single crystal, a seam line 4 indicating single crystallization appears in FIG. Thus, every time the seam line 4 intersects the photometric line E, the peak luminance Bmax is generated. Therefore, by detecting this peak luminance Bmax, it is possible to detect the appearance of the seam line 4 indicating single crystallization.
[0071]
In FIG. 12, reference numeral 281 denotes a luminance measuring circuit for measuring the luminance at the intersection P position where the measurement line E and the outline of the meniscus 3 intersect, 282 is a peak luminance detecting circuit for detecting the peak luminance Bmax, and 283 is a peak luminance Bmax and base. A luminance difference calculation circuit 284 that calculates a luminance difference ΔB with respect to the luminance B is a luminance difference determination circuit that detects the appearance of the seam line 4 indicating single crystallization when the luminance difference ΔB exceeds a predetermined threshold value. .
[0072]
Next, the operation of the single crystallization automatic discrimination device 24 of FIG. 12 will be described.
The video signal photographed by the CCD camera 21 is sent to the intersection position luminance measurement circuit 281 and the luminance at the intersection P as shown in FIG. 14 is measured. The peak luminance detection circuit 282 detects the peak luminance Bmax from the measured luminance and sends it to the luminance difference calculation circuit 283.
[0073]
The luminance difference calculation circuit 283 calculates a luminance difference ΔB between the peak luminance Bmax and the base luminance B and sends it to the luminance difference determination circuit 284. The luminance difference determination circuit 284 compares the luminance difference ΔB with a predetermined threshold value, determines that a seam line 4 indicating single crystallization has appeared when the threshold value exceeds the threshold value, and outputs a detection output of the seam line. Occur. This detection output is sent to the single crystal pulling control device 25 of FIG.
[0074]
1 receives the detection output of the seam line, and controls the operation of the crucible rotating mechanism 13, the crucible lifting mechanism 14, the seed crystal lifting mechanism 16, and the seed crystal rotating mechanism 19, The process is automatically shifted from the seed process to the neck process.
[0075]
As described above, in the case of the fourth embodiment, the appearance of a seam line is detected from the change in luminance at the intersection point where the measurement line and the outline of the meniscus intersect. For this reason, it is possible to automatically detect whether or not the silicon crystal has become a single crystal, and by using this detection result to control the silicon single crystal manufacturing equipment, the transition from the seed process to the neck process is automated. can do.
[0076]
Even in the case of the fourth embodiment, the above monitoring is continued even after the single crystallization is achieved, and the single crystallization is broken if the luminance difference is below the threshold value. It is desirable to be configured to issue an alarm.
[0077]
【The invention's effect】
As described above, according to the first aspect of the present invention, the single crystallization is performed from the change in the distance between the horizontal reference position line set in the photographed image and the lowest end of the meniscus of the semiconductor crystal. Since the appearance of the seam line to be shown can be detected, it is not necessary for the operator to visually confirm the occurrence of the seam line as in the prior art, and the burden on the operator can be reduced. In addition, it is possible to automate the transition timing from the seed process to the neck process, and because the monitoring timing does not match as in the case of visual confirmation, the confirmation of the appearance of seam lines is delayed, the throughput decreases, the power used It is possible to eliminate the increase in the amount and the deterioration of the member.
[0078]
According to the second aspect of the present invention, since the appearance of a seam line indicating single crystallization can be detected by pattern matching between the photographed image of the seed crystal and the melt surface portion and the comparison pattern, the claim The same effect as that of the invention described in item 1 can be obtained.
[0079]
According to the third aspect of the present invention, it is possible to detect the appearance of a seam line indicating single crystallization from the change in the number of pixels of the meniscus portion of the semiconductor crystal in the photographed images of the seed crystal and the melt surface portion. Therefore, the same effect as that of the first aspect of the invention can be achieved.
[0080]
When the invention according to claim 4 of the present invention, it is possible to detect the appearance of a seam line indicating single crystallization from the change in luminance at the intersection point where the outline of the meniscus of the semiconductor crystal and the measurement line intersect. The same effects as those of the first aspect of the invention can be achieved.
[0081]
According to the invention described in claim 5 of the present invention, the appearance of a seam line indicating single crystallization from the change in the distance between the horizontal reference position line set in the photographed image and the lowermost end of the meniscus of the semiconductor crystal. A single crystal manufacturing apparatus capable of detecting and automating the transition from the seed process to the neck process can be obtained. This eliminates the need for the operator to visually confirm the appearance of the seam line as in the past, and can automate the transition timing from the seed process to the neck process, as well as monitoring in the case of visual confirmation. Because the timing does not match, confirmation of the appearance of seam lines is delayed, which can reduce the throughput, increase the amount of power used, and cause deterioration of components. A crystal manufacturing apparatus can be provided.
[0082]
According to the invention described in claim 6 of the present invention, the appearance of a seam line indicating single crystallization is detected by pattern matching between the photographed image of the seed crystal and the melt surface portion and the comparison pattern, and from the seed process to the neck process. It is possible to obtain a single crystal manufacturing apparatus that can automate the transition of the above. Therefore, the same effect as that of the fifth aspect of the invention can be achieved.
[0083]
According to the seventh aspect of the present invention, the appearance of a seam line indicating single crystallization is detected from the change in the number of pixels of the meniscus portion of the semiconductor crystal in the photographed images of the seed crystal and the melt surface portion, and the seed A semiconductor single crystal manufacturing apparatus capable of automating the transition from the process to the neck process can be obtained. Therefore, the same effect as that of the fifth aspect of the invention can be achieved.
[0084]
According to the eighth aspect of the present invention, the appearance of a seam line indicating single crystallization is detected from the change in luminance at the intersection point where the outline of the meniscus of the semiconductor crystal and the measurement line intersect, and the bottleneck from the seed process is detected. A semiconductor single crystal manufacturing apparatus capable of automating the transition to the process can be obtained. Therefore, the same effect as that of the fifth aspect of the invention can be achieved.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram showing a first embodiment of a silicon single crystal manufacturing apparatus configured by applying the present invention.
FIG. 2 is a diagram showing a circuit configuration example of the single crystallization automatic discrimination device in FIG. 1;
FIG. 3 is a diagram illustrating a monitor screen for explaining the operation of the first embodiment;
4 is a waveform diagram for explaining the operation of the single crystallization automatic discrimination apparatus of FIG. 2; FIG.
FIG. 5 is a diagram illustrating a change characteristic of a distance from a lower end edge of a monitor screen to a lowermost end portion of a meniscus of a silicon crystal.
FIG. 6 is a diagram showing a circuit configuration example of a single crystallization automatic discrimination device used in the second embodiment.
FIG. 7 is a diagram illustrating an example of a comparison pattern.
FIG. 8 is a diagram illustrating a monitor screen for explaining the operation of the second embodiment;
FIG. 9 is a diagram showing a circuit configuration example of a single crystallization automatic discrimination apparatus used in the third embodiment.
FIG. 10 is a diagram illustrating a monitor screen for explaining the operation of the second embodiment;
FIG. 11 is a diagram illustrating a change characteristic of the number of pixels of a meniscus portion of a silicon crystal.
FIG. 12 is a diagram illustrating a circuit configuration example of a single crystallization automatic discrimination device used in the fourth embodiment;
FIG. 13 is a diagram illustrating a monitor screen for explaining the operation of the fourth embodiment;
FIG. 14 is a diagram illustrating an example of a state of change in luminance at an intersection position where an interface between a semiconductor crystal and a melt surface intersects with a measurement line;
FIG. 15 shows an example of a photographed image of a seed crystal and a melt surface portion. (A) is a diagram showing an example of a photographed image when a seam line appears, and (b) is a seam line. It is a figure which shows the example of the picked-up image when no has appeared.
[Explanation of symbols]
1 seed crystal
2 Melt surface
3 Meniscus
4 Seam line
11 crucible
16 Seed crystal lifting mechanism
17 wire
18 Seed chuck
19 Seed crystal rotation mechanism
20 Perspective window
21 CCD camera (imaging means)
22 Camera control unit
23 TV monitor
24 Single crystallization automatic identification device
25 Single crystal pulling control device (control means)

Claims (8)

In the method for producing a semiconductor single crystal by the CZ method,
When determining the single crystallization of the growth crystal for the transition from the seed process to the neck process, the seed crystal and the melt surface part are photographed by the imaging means,
The distance between the horizontal reference position line for distance measurement set in advance in the photographed image and the lowest end of the meniscus of the semiconductor crystal photographed by the imaging means is calculated by image processing,
An automatic single crystallization discriminating method, characterized in that it is detected as the appearance of a seam line indicating single crystallization when the distance is equal to or less than a preset threshold value. In the method for producing a semiconductor single crystal by the CZ method,
When determining the single crystallization of the growth crystal for the transition from the seed process to the neck process, the seed crystal and the melt surface part are photographed by the imaging means,
Prepare an image of the seed crystal and the melt surface part in the state where the seam line appeared in advance as a comparison pattern,
A method for automatically determining a single crystallization, wherein the appearance of a seam line indicating single crystallization is detected by performing pattern matching between a seed crystal photographed by an imaging means, a photographed image of a melt surface portion, and the comparison pattern. . In the method for producing a semiconductor single crystal by the CZ method,
When determining the single crystallization of the growth crystal for the transition from the seed process to the neck process, the seed crystal and the melt surface part are photographed by the imaging means,
The number of pixels of the meniscus portion of the semiconductor crystal in the photographed image of the seed crystal and melt surface portion photographed by the imaging means is counted by image processing,
An automatic single crystallization discriminating method characterized by detecting the appearance of a seam line indicating single crystallization when the number of pixels exceeds a predetermined threshold value. In the method for producing a semiconductor single crystal by the CZ method,
When determining the single crystallization of the growth crystal for the transition from the seed process to the neck process, the seed crystal and the melt surface part are photographed by the imaging means,
Set a measurement line that crosses the meniscus part of the semiconductor crystal in advance on the photographed image,
Measure the change in luminance at the intersection point where the measurement line intersects the outer line of the meniscus in the photographed image of the seed crystal and melt surface portion photographed by the imaging means,
An automatic single crystallization discriminating method comprising detecting when a change in luminance exceeds a predetermined threshold as an appearance of a seam line indicating single crystallization. In a semiconductor single crystal manufacturing apparatus using the CZ method,
An imaging means for photographing the seed crystal and the melt surface portion in the crucible through the transparent window;
The distance between the horizontal reference position line for distance measurement set in advance in the captured image and the lowermost end of the meniscus of the semiconductor crystal in the captured image captured by the imaging means is calculated by image processing, An automatic single crystallization discriminating device for detecting the appearance of a seam line indicating single crystallization when the distance is equal to or less than a preset threshold;
A semiconductor single crystal manufacturing apparatus, comprising control means for automatically shifting a processing process of a semiconductor single crystal manufacturing apparatus from a seed process to a neck process according to a determination result of the single crystallization automatic determination apparatus. In a semiconductor single crystal manufacturing apparatus using the CZ method,
An imaging means for photographing the seed crystal and the melt surface portion in the crucible through the transparent window;
An image of a seed crystal and a melt surface portion in a state where a seam line appears in advance is prepared as a comparison pattern, and a pattern matching between the captured image of the seed crystal and the melt surface portion photographed by the imaging means and the comparison pattern is prepared. A single crystallization automatic discrimination device that detects the appearance of a seam line indicating single crystallization by performing
A semiconductor single crystal manufacturing apparatus, comprising control means for automatically shifting a processing process of a semiconductor single crystal manufacturing apparatus from a seed process to a neck process according to a determination result of the single crystallization automatic determination apparatus. In a semiconductor single crystal manufacturing apparatus using the CZ method,
An imaging means for photographing the seed crystal and the melt surface portion in the crucible through the transparent window;
The number of pixels of the meniscus portion of the semiconductor crystal in the photographed images of the seed crystal and the melt surface portion photographed by the imaging means is counted by image processing, and single crystallization is performed when the number of pixels exceeds a predetermined threshold value An automatic single crystallization discriminating device for detecting the appearance of a seam line indicating
A semiconductor single crystal manufacturing apparatus, comprising control means for automatically shifting a processing process of a semiconductor single crystal manufacturing apparatus from a seed process to a neck process according to a determination result of the single crystallization automatic determination apparatus. In a semiconductor single crystal manufacturing apparatus using the CZ method,
An imaging means for photographing the seed crystal and the melt surface portion in the crucible through the transparent window;
A measurement line that crosses the meniscus portion of the semiconductor crystal is set in advance on the photographed image, and the intersection point between the measurement line and the outer line of the meniscus in the photographed image of the seed crystal photographed by the imaging means and the melt surface portion A single crystallization automatic discrimination device that measures a change in luminance at a position and detects the appearance of a seam line indicating single crystallization when the luminance change exceeds a predetermined threshold;
A semiconductor single crystal manufacturing apparatus, comprising control means for automatically shifting a processing process of a semiconductor single crystal manufacturing apparatus from a seed process to a neck process according to a determination result of the single crystallization automatic determination apparatus.

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