JP2953548B2 - Method and apparatus for producing silicon single crystal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicon single crystal manufacturing apparatus capable of automatically detecting dislocations with a one-dimensional or two-dimensional camera when manufacturing a silicon single crystal by the Czochralski method.

[0002]

2. Description of the Related Art In the Czochralski method (CZ method), polycrystalline silicon is charged into a quartz crucible provided in a chamber, heated and melted by a heater, and a seed crystal is immersed in the silicon melt. By rotating and pulling, a single crystal is grown under the seed crystal to produce a columnar silicon single crystal.

When a silicon single crystal is manufactured by such a CZ method, a reaction between a silicon melt and a quartz crucible generates SiO gas, and this SiO gas precipitates and adheres to the upper inner wall of the chamber. Then, when the attached precipitate falls into the silicon melt during the pulling of the silicon single crystal and adheres to the silicon single crystal, dislocation occurs in the silicon single crystal. In the case of dislocations, the dislocation density is 100 co / cm
³ or more cases.

[0004] As described above, dislocations may always occur in the silicon single crystal being pulled, and when dislocations occur, the silicon single crystal is no longer a silicon single crystal after the location where the dislocations occur. Cannot be used as a product. In particular, in recent years, it has been required to use dislocation-free materials in order to improve the quality of semiconductor devices.

[0005] In addition, the silicon single crystal being manufactured has a structure shown in FIG.
As shown in FIG. 5, a linear seam 21 protruding from the surface is formed along the axial direction. When dislocations occur, as shown in FIG.
Disappears. This is because the crystal lattices are regularly arranged in the dislocation-free silicon single crystal 8, but are irregularly arranged in the case of dislocations.

[0006] Therefore, in conventional silicon single crystal production, the observer constantly monitors the linear seam through a viewing window provided at the top of the chamber to monitor whether or not dislocations have occurred. I was trying to do it.

[0007]

However, during the production of the above-described conventional silicon single crystal, the observer must constantly monitor for the presence or absence of dislocations. The attendant work could not be performed, and there was a problem that not only the work efficiency of the worker was poor but also the cost increased. Furthermore, since the detection of dislocations may be delayed, there is a problem that appropriate processing cannot be performed later.

Accordingly, an object of the present invention is to provide a silicon single crystal manufacturing apparatus capable of automatically detecting dislocations by a one-dimensional or two-dimensional camera and enabling unmanned operation during operation.

[0009]

According to the first aspect of the present invention, a seam formed on the surface of a silicon single crystal being pulled up from a viewing window provided in a chamber is imaged by an imaging means, and the imaging is performed. The number of seams detected per unit time is determined in advance based on the luminance signal by the means, the rotation data of the seed crystal input to the rotation data setting unit, and the orientation data of the seed crystal input to the orientation data setting unit. Calculated
The calculated number and the unit time in the luminance signal
The number of seams generated per hit is compared with the calculated number and brightness.
This is a method for manufacturing a silicon single crystal having a configuration in which a number difference in the degree signal is generated and when the number difference is continuous, it is determined to be dislocation.

According to a second aspect of the present invention, in a silicon single crystal manufacturing apparatus for pulling and manufacturing a silicon single crystal by the Czochralski method, the surface of the silicon single crystal being pulled from an observation window provided in a chamber is provided. Imaging means for imaging the seam formed in the worm, a rotation data setting unit for inputting rotation data of the seed crystal, an azimuth data setting unit for inputting azimuth data of the seed crystal, the rotation data setting unit and the azimuth data setting A calculating unit for previously calculating the number of seams detected per unit time based on the output signal from the unit, further comprising: a calculation number from the calculation unit; and the number of seams in the luminance signal by the imaging unit. compare, shea configuration and the number difference number difference occurs in several of the calculated number of the luminance signal is provided with a dislocation and a determination unit when the continuous An apparatus for producing a con single crystal.

[0011]

When the actual rotation data of the seed crystal is input to the rotation data setting unit and the direction data of the seed crystal is input to the direction data setting unit and driven, a cylindrical silicon single crystal is formed as the seed crystal at the lower end of the pulling shaft. Manufactured. At the same time, in the determination unit,
Based on the luminance signal from the CCD camera, the actual rotation of the seed crystal, and the azimuth of the seed crystal, it is determined whether there is a dislocation state or a non-dislocation state. In the determination of the dislocation state or the non-dislocation state, when the number difference between the luminance signal and the calculation signal occurs within a unit time and they are consecutive, it is determined to be the dislocation state, and the others are determined to be the non-dislocation state. When it is determined that the dislocation state is present, the notification unit and the display unit are driven to notify the worker, and are stored in the storage unit.

Therefore, when dislocations are generated when the silicon single crystal is pulled, it is automatically detected.
Unmanned operation during the operation of silicon single crystal production is made possible, and other attendant work becomes possible for the observer who has been restrained by monitoring in the past, thereby improving work efficiency and reducing costs.

[0013]

An embodiment of the present invention will be described below with reference to the drawings. In this example, the orientation of the seed crystal was <100>, and the rotation speed of the pulled seed crystal was 20 rpm /
A case in which a silicon single crystal having a diameter of 6 inches is pulled and manufactured in a minute will be described.

An apparatus 1 for producing a silicon single crystal according to this embodiment
As shown in FIG. 1, an annular heat insulator (not shown) is provided in the chamber 2 and an annular heater 3 is provided inside the heat insulator. A quartz crucible 4 whose periphery is protected by a protective material is disposed in the heater 3 so as to be vertically movable and rotatable by a rotating shaft 5. A melt 6 of silicon polycrystal is accommodated in the quartz crucible 4, and a pulling shaft 7 provided with a seed crystal at a lower end is provided above the quartz crucible 4 so as to move up and down and to be able to reverse the quartz crucible 4. . Then, the seed crystal provided on the pulling shaft 7 is gradually pulled up while being immersed in the melt 6, thereby producing a columnar silicon single crystal 8.

Further, a viewing window 9 is provided at an upper portion of the chamber 2, and a one-dimensional C for measuring the silicon single crystal 8 being pulled from the viewing window 9 is provided outside the viewing window 9.
A CD camera 10 (imaging means) is provided. This C
The CD camera 10 is set so that the measurement area A is directed to a point where the width of the silicon single crystal 8 can be most easily measured, as shown by a two-dot chain line in FIG. That is, the measurement point A is set on the outer surface near the center of the silicon single crystal 8 including the boundary portion between the silicon single crystal 8 and the melt 6, and is thus formed around the boundary portion of the silicon single crystal 8. The outer end of the fusion ring 20 is included.
The fusion ring 20 is a ring that looks bright due to the generation of solidification latent heat during the growth of the silicon single crystal 8. In other words, the measurement area A of the CCD camera 10 is set so that the seam 21 that protrudes from the surface during the pulling of the silicon single crystal 8 and that is formed linearly along the axial direction can be measured. Then, the output from the CCD camera 10 is obtained as a luminance signal K as shown in FIG. F of the luminance signal K shown in FIG.
0, and the central depression S is due to the seam 21. The fusion ring 20 is bright, and the seam 21 protrudes from the surface, so that it becomes dark due to refraction.

The CCD camera 10 is connected to a calculation unit 15 and a determination unit 16 of a microcomputer 14 via an A / D converter 11, as shown in FIG. The calculation unit 15 is connected to a rotation data setting unit 12 for inputting the actual result of the rotation data of the seed crystal, and an orientation data setting unit 13 for inputting the orientation data of the seed crystal. The calculating unit 15 stores the signal pattern of the seam 21 at a certain time based on the rotation result of the seed crystal and the orientation of the seed crystal, and the seam 21 pattern is stored in the silicon single crystal 8 per unit time.
The number of passes through the center is calculated back.
Is connected to a judging unit 16 for judging a dislocation state or a non-dislocation state based on the luminance signal K from the CCD camera 10 and the calculation signal from the calculation unit 15. In the determination unit 16,
This is a configuration in which a notification unit 17, a display unit 18, and a storage unit 19 are connected.

In such an apparatus for manufacturing the silicon single crystal 8, the actual result of the rotation data of the seed crystal is input to the rotation data setting unit 12 in advance, and the orientation data of the seed crystal is input to the orientation data setting unit 13 for driving. Then, the seed crystal at the lower end of the pulling shaft 7 is gradually pulled up while being immersed in the melt 6 while rotating in the opposite direction to the quartz crucible 4, thereby producing a columnar silicon single crystal 8. At the same time, the seam 21 of the silicon single crystal 8 being pulled by the CCD camera 10 is imaged, and the luminance signal K is input to the calculating unit 15 and the determining unit 16, and the calculating unit 1
In 5, the number of times the pattern of the seam 21 passes through the center of the silicon single crystal 8 per unit time is calculated backward based on the actual rotation of the seed crystal and the orientation of the seed crystal.

The determination section 16 determines whether a dislocation state or a non-dislocation state is present, based on the luminance signal K from the CCD camera 10 and the calculation signal from the calculation section 15. In the determination of the dislocation state or the non-dislocation state, when the difference between the luminance signal K and the calculation signal occurs within a unit time and they are consecutive, it is determined to be the dislocation state, and the others are determined to be the non-dislocation state.

When it is determined that the dislocation is in the dislocation state, the notification unit 17 and the display unit 18 are driven to notify the worker and stored in the storage unit 19.

Therefore, when dislocations are generated when the silicon single crystal is pulled, it is automatically detected.
Unmanned operation during the operation of silicon single crystal production is made possible, and other attendant work becomes possible for the observer who has been restrained by monitoring in the past, thereby improving work efficiency and reducing costs.

The CCD camera is not limited to a one-dimensional CCD camera, but a two-dimensional CCD camera can be used.

[0022]

As described above, according to the present invention,
Since dislocations can be automatically detected when pulling a silicon single crystal, unmanned operation during the operation of silicon single crystal production is possible, and a supervisor who has been restrained by conventional monitoring can perform other incidental work. In addition, work efficiency can be improved and costs can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a silicon single crystal manufacturing apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic block diagram of a dislocation automatic detection unit.

FIG. 3 is a front view showing measurement points of a CCD camera at the time of no dislocation.

FIG. 4 is a diagram showing a luminance signal without dislocation obtained from a CCD camera.

FIG. 5 is a front view showing measurement points of the CCD camera at the time of dislocation.

FIG. 6 is a diagram showing a luminance signal at the time of dislocation obtained from a CCD camera.

[Explanation of symbols]

 Reference Signs List 1 silicon single crystal manufacturing apparatus 2 chamber 8 silicon single crystal 9 viewing window 10 CCD camera (imaging means) 12 rotation data setting unit 13 azimuth data setting unit 16 determination unit 17 notification unit 18 display unit 19 recording unit 21 seam K luminance signal

Claims (2)

(57) [Claims] 1. A seam formed on a surface of a silicon single crystal being pulled up from a viewing window provided in a chamber is imaged by an image pickup means, and a luminance signal by the image pickup means and a seed inputted to a rotation data setting section are taken. The number of seams detected per unit time is calculated in advance based on the crystal rotation data and the seed crystal orientation data input to the orientation data setting unit.
The calculated number and the unit of the luminance signal
Comparing the number of seams generated per time with the calculated number and the number in the luminance signal , and determining that dislocations are present when the number difference is continuous. Single crystal production method. 2. An imaging apparatus for manufacturing a silicon single crystal by pulling and manufacturing a silicon single crystal by the Czochralski method, wherein an image of a seam formed on a surface of the silicon single crystal being pulled from a viewing window provided in a chamber is taken. Means, a rotation data setting unit for inputting rotation data of the seed crystal, an azimuth data setting unit for inputting azimuth data of the seed crystal, and a unit based on output signals from the rotation data setting unit and the azimuth data setting unit. Detected per hour
A calculating unit for calculating the number of seams in advance , further comprising comparing the calculated number from the calculating unit with the number of seams in the luminance signal by the imaging unit, and calculating the calculated number and the luminance signal. A production unit for a silicon single crystal, comprising: a determination unit that determines that a dislocation has occurred when a number difference occurs in the number and the number difference continues.