JP2010076979A - Measurement method and system during manufacturing semiconductor single crystal by fz method, and control method and system during manufacturing semiconductor single crystal by fz method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a measurement method and measurement system for measuring crystallization interface of a semiconductor single crystal in an initial stage of a cone part forming process for enlarging the crystal diameter from a seed necking process of an FZ (Floating Zone) method, and to provide a control method and a control system. <P>SOLUTION: In an initial stage of a cone part 24 forming process for enlarging the crystal diameter from a seed necking process of an FZ method for manufacturing a semiconductor single crystal, the diameter of the crystallization interface 22 of the semiconductor single crystal crystallized at the inside of a heating coil is measured through arithmetic processing of triangulation using the parallax between a first camera 12 arranged at a position having a height different from that of the crystallization interface 22 and a second camera 14 arranged at a position having the same height as that of the first camera 12 and having an optical axis parallel to the first camera 12, with respect to the crystallization interface 22. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method and system for growing a semiconductor single crystal by FZ method (floating zone method or floating zone melting method), and more particularly to a method and system for improving control accuracy in automation of semiconductor single crystal production by FZ method. .

  When manufacturing a semiconductor single crystal by the FZ method, one end of a raw material rod made of semiconductor polycrystal is melted by a heating device made of an induction heating coil and fused to a seed crystal having a target crystal orientation, and then a seed drawing Integrating with the seed crystal while making no transition, and moving the raw material rod relative to the heating device relative to the axial direction, and at the same time, the melting portion from the fusion portion to the other end of the raw material rod By gradually moving it toward a single crystal, a single semiconductor crystal is obtained.

  FIG. 9 and FIG. 10 show an example of processes from fusing (seeding) a semiconductor raw material rod to a seed crystal to forming a single crystal (straight body portion) having a target diameter, a cone portion, and a target diameter.

  In the figure, first, the tip of a tapered semiconductor raw material rod 110 such as silicon is heated and melted by an induction heating coil 114 to form a melting zone 111 (FIG. 9A), and fused with the seed crystal 116. (FIG. 9B). Thereafter, a narrowed portion 113 having a diameter of about 3 mm for making no transition is formed (FIG. 9C). Subsequently, the semiconductor raw material rod 110 is gradually moved downward, and the formation of the cone portion 112 which is gradually crystallized by increasing the diameter is started (FIG. 10D). Then, the diameter of the cone portion 112 is further enlarged (FIG. 10 (e)), and when the maximum diameter portion reaches the target diameter, the single crystal 127 continues to grow while maintaining the diameter and has the target length. A single crystal rod is formed (FIG. 10 (f)).

  Conventionally, with regard to the above-described processes for seeding, seeding, and further until the maximum diameter of the cone portion is about 30 mm, while manually observing the melting zone, the moving speed of the raw material rod and the induction heating coil In the cone forming process and the straight body growing process after the maximum diameter of the cone reaches about 30 mm, the image is being monitored by a monitor such as a camera. The moving speed of the raw material rod and the heating output of the induction heating coil were automatically controlled based on the data.

  The reason why the process until the diameter of the cone part is about 30 mm is not automated is that the small melting zone is hidden behind the induction heating coil when the diameter of the cone part is less than 30 mm, and from the horizontal direction. This is because monitoring cannot be performed. Therefore, in this process, an operator observes the melted portion obliquely from above, and manually adjusts the moving speed of the raw material rod and the heating output of the induction heating coil based on the shape and the like. However, when observing the melted part obliquely from above, the positional relationship is shifted compared to the observation from the horizontal direction, so much experience is required before the adjustment can be performed successfully. It was.

In order to solve such problems, Patent Documents 1 and 2 disclose a configuration in which the diameter of the cone portion is detected from a predetermined angle obliquely upward or obliquely below that does not visually interfere with the induction heating coil. .
Japanese Patent No. 3601280 Japanese Patent No. 4016363

  However, the crystallization interface of the semiconductor single crystal gradually moves downward from the drawing step of the FZ method to the cone portion forming step. In this case, for example, when the camera is installed obliquely downward from the crystallization interface and the crystallization interface that is obliquely above is viewed, the semiconductor single crystal in the above-described process increases the diameter while approaching the camera. . When only one camera is used here, it cannot be judged whether the change in the measured value of the diameter is due to the approach of the semiconductor single crystal or the expansion of the diameter, and the obtained measured value is an accurate value. There was a problem that it cannot be said.

  Therefore, in order to solve the above problem, a diameter calculation method, a diameter calculation system, and a diameter control method using the same that accurately calculate the diameter of the crystallization interface of the semiconductor single crystal from the drawing step of the FZ method to the cone forming step And a diameter control system.

  In order to achieve the above object, a surveying method for manufacturing an FZ method semiconductor crystal according to the present invention is as follows. First, a cone portion forming step is first performed to increase the crystal diameter from the seed drawing step of the FZ method for manufacturing a semiconductor single crystal. The diameter of the crystallization interface of the semiconductor single crystal that is crystallized inside the heating coil is set to the same height position as the first camera and the first camera arranged at a height position different from the crystallization interface. Surveying is performed through triangulation calculation processing using parallax with respect to the crystallization interface between the second camera having an optical axis parallel to the first camera.

  Second, the second camera is obtained by translating the first camera to a position where the second camera is provided while keeping the optical axis direction constant.

  3rdly, in the said triangulation calculation process, while measuring the said diameter, the height position of the said crystallization interface is measured, The FZ method semiconductor crystal of Claim 1 or 2 characterized by the above-mentioned Surveying method.

  The FZ method semiconductor single crystal manufacturing control method according to the present invention measures the diameter and height position of the crystallization interface using the above-described semiconductor crystal surveying method during FZ method semiconductor single crystal manufacture. Measuring a zone length of a melting zone of a semiconductor raw material rod that is a raw material of the semiconductor crystal melted and heated by the heating coil, and the diameter and the zone length are designed in advance for each predetermined time. The moving speed of the semiconductor raw material rod and the output of the heating coil are controlled so as to be long.

  On the other hand, the surveying system for manufacturing the FZ method semiconductor single crystal according to the present invention firstly includes a heating coil at the initial stage of the cone portion forming process for expanding the crystal diameter from the seed drawing process of the FZ method for manufacturing a semiconductor single crystal. A first camera disposed at a height position different from the crystallization interface for photographing the crystallization interface of the semiconductor single crystal crystallized inside and outputting the first image data, and the same height as the first camera A second camera which is disposed at a position and has an optical axis parallel to the first camera and which captures the crystallization interface and outputs second image data, and on the first image data and the second The left and right ends of the crystallization interface on the image data are detected, and the distance between the left and right ends of the crystallization interface is determined by triangulation calculation using parallax between the first camera and the second camera. Surveying means for measuring as the diameter of the interface; It is characterized in that.

  Second, the second camera is obtained by translating the first camera to a position where the second camera is provided while keeping the optical axis direction constant.

Thirdly, the surveying means measures the diameter and measures the height position of the crystallization interface.
Further, the control system for manufacturing the FZ method semiconductor single crystal according to the present invention calculates the diameter and height position of the crystallization interface by the semiconductor crystal surveying system for manufacturing the FZ method semiconductor single crystal described above, and at the same time, the heating system Measuring means for measuring a zone length of a melting zone of a semiconductor raw material rod which is a raw material of the semiconductor crystal melted and heated by a coil, and a design diameter and a design zone in which the diameter and the zone length are designed in advance for each predetermined time It is characterized by having a control means for controlling the moving speed of the semiconductor material rod and the output of the heating coil so as to be long.

  According to the surveying method and surveying system at the time of manufacturing the FZ method semiconductor crystal according to the present invention, the control method and control system at the time of manufacturing the FZ method semiconductor single crystal, the heating coil from the drawing process of the FZ method to the initial stage of forming the cone part Even when image measurement is performed on the diameter of the crystallization interface of the semiconductor single crystal formed inside from an oblique direction, the diameter can be accurately measured as in the case of image measurement from the horizontal direction. Further, in the process of calculating the diameter of the crystallization interface by image measurement, the height of the crystallization interface can also be calculated, so that the semiconductor raw material rod was formed inside the heating coil of the zone length of the melting zone formed by heating and melting. The length of the component can also be accurately measured. Therefore, it is possible to control the semiconductor crystal growth with high accuracy in the above-described steps. Further, since it is possible to use a single camera for image measurement, it is not necessary to align the optical axes of the cameras in parallel, and there is no fear of optical axis deviation, so that the reliability of image measurement is improved.

  The diameter control system by this method can be applied in all processes from the seed drawing process to the condensation bottom part forming process, but the melting zone is inside the heating coil and cannot be monitored from the horizontal direction. This is particularly effective during the period up to the initial stage of the cone portion forming step in which the diameter of the crystallization is 30 mm or less.

  Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. However, the components, types, combinations, shapes, relative arrangements, and the like described in this embodiment are merely illustrative examples and not intended to limit the scope of the present invention only unless otherwise specified. .

  A surveying method for manufacturing an FZ method semiconductor crystal according to the present embodiment is the semiconductor crystallized inside the heating coil in the initial stage of the cone portion forming step for expanding the crystal diameter from the seed drawing step of the FZ method for manufacturing a semiconductor single crystal. A diameter of the crystallization interface of the single crystal is set to a first camera arranged at a height position different from the crystallization interface, and an optical axis arranged at the same height position as the first camera and parallel to the first camera. FIG. 1 shows a surveying system at the time of manufacturing an FZ method semiconductor crystal that implements the surveying using a triangulation calculation process using a parallax with respect to the crystallization interface with a second camera having the above. FIG. 1A is a schematic diagram of a surveying system, and FIG. 1B is a schematic diagram showing an optical system in a plan view. The process of the FZ method to which the surveying system of the present embodiment is applied is as described in the above prior art, but silicon or the like is used as the material at the initial stage of the cone part forming process for expanding the crystal diameter from the seed drawing process of the FZ method. The semiconductor material to be formed includes a semiconductor raw material rod 18, a melting zone 20, a crystallization interface 22, a cone portion 24, and a narrowed portion 26 from above, which are shown in FIGS. 9 (c) to 10 (d) in the above-described prior art. It corresponds to the state up to.

  The surveying system 10 includes a first camera 12, a second camera 14, and image processing units 16a and 16b and an arithmetic processing unit 16c that constitute surveying means. The first camera 12 and the second camera 14 are arranged at the same height and lower than the lower end of the heating coil 28 (may be higher). More specifically, the first camera 12 and the second camera 14 are arranged at positions where the heating coil 28 does not interfere with the field of view of the crystallization interface 22 formed inside the heating coil 28 and can be visually recognized. Is done.

  As shown in FIG. 1B, it is assumed that the optical axes of the first camera 12 and the second camera 14 are parallel to each other, and the distance d between the focal points of the first camera 12 and the second camera 14 is known. Further, the horizontal orientations of the first camera 12 and the second camera 14 are oriented such that the crystallization interface 22 enters between the optical axis of the first camera 12 and the optical axis of the second camera 14. Further, the first camera 12 and the second camera 14 are also known to have an elevation angle θ (see FIGS. 1A and 2B) directed toward the crystallization interface 22 side. 14 have the same focal length f. It is assumed that the distance from the crystallization interface 22 of the first camera 12 and the second camera 14 is sufficiently larger than the diameter of the crystallization interface 22. Thereby, the first camera 12 and the second camera 14 can be regarded as being able to visually recognize the left end 22a and the right end 22b of the same crystallization interface 22. Here, the imaging surfaces (not shown) of the first camera 12 and the second camera 14 are arranged on the same plane and form a common image coordinate S (see FIGS. 1B and 2). And Further, the origin of the image coordinates S of the first image data 30 and the optical axis of the first camera 12 coincide, and the origin of the image coordinates S of the second image data 32 and the optical axis of the second camera 14 coincide.

  The first camera 12 is connected to the image processing unit 16a, and the second camera 14 is connected to the image processing unit 16b. The image processing units 16a and 16b are connected to a control unit 44 (see FIG. 4) described later. The image processing units 16a and 16b are connected to the arithmetic processing unit 16c. When the image processing units 16a and 16b receive survey command signals from the control unit 44, which will be described later, the shutters of the first camera 12 and the second camera 14 are actuated, and the crystallization interface 22 is used as the subject to capture images of each camera. The image processing unit 16 a inputs the first image data 30 from the first camera 12, and the image processing unit 16 b inputs the second image data 32 from the second camera 14.

  The image processing unit 16a performs binarization processing or the like on the first image data 30, detects the left end 22a and the right end 22b of the crystallization interface 22 on the first image data 30, and the left end on each image coordinate S The first coordinate data 16d indicating the coordinates of 22a and the right end 22b is output to the arithmetic processing unit 16c. Similarly, the image processing unit 16b performs binarization processing or the like on the second image data 32, detects the left end 22a and the right end 22b of the crystallization interface 22 on the second image data 32, and each image coordinate S The second coordinate data 16e indicating the upper left 22a and right end 22b coordinates is output to the arithmetic processing unit 16c. The arithmetic processing unit 16c performs triangulation calculation based on the first coordinate data 16d and the second coordinate data 16e input from the image processing units 16a and 16b, and calculates the diameter of the crystallization interface and its height position.

  FIG. 2 shows a conceptual diagram of triangulation calculation. FIG. 2A is a conceptual diagram viewed from above, and FIG. 2B is a conceptual diagram viewed from the side surface direction. Consider an image coordinate S (imaging plane) having a horizontal direction as an X axis and a Y axis perpendicular to the X axis (inclined at an angle θ from the vertical direction).

As shown in FIG. 2 (a), the first camera 12 and the second camera 14 has a common optical axis O, and the focal point _{O L} of the first camera 12 as the origin, the focus _{O R} of the second camera 14 O _L from the X axis direction d (focal distance between) and only moved position. Then, the left end 22a and the right end 22b on the image coordinate S are projected onto the target coordinate T having the same normal line as the plane coordinate S and forming a plane including the left end 22a and the right end 22b. By calculating the above coordinates, the diameter and height position of the crystallization interface 22 can be calculated.

For example, when the measurement position P on the target coordinates T (the left end 22a of the crystallization interface 22) is photographed, the first left end on the first image data 30 is Q _L (X _L , Y _L ), and the second image data 32 the second leftmost top _{Q R (X R, Y R} ) is given coordinates. Focus _{O L} of the first camera 12, the focal point _{O R} and the measuring position _{P (X P, Y P)} of the second camera 14 by connecting it triangle, performs triangulation. Here, since the first camera 12 is the focal length f of the second camera 14 is the same, the line segment connecting O _L and O _R, a line segment connecting the Q _L and Q _R of the image coordinates S are parallel Become. Therefore, it is possible to utilize the fact and triangle _PO L _{O R} and _PQ L _{Q R} is similar determine coordinates of _{P (X P, Y P)} .

の関係が得られる。よって、［数１］から

が得られる。これが左端２２ａのターゲット座標Ｔ上のＸ軸方向の座標となる。同様に右端２２ｂについてもＸ軸方向の座標を算出し、両者の差分を取ることにより、晶出界面２２の直径が算出されることとなる。 Focusing on the length of the base of the _triangle, O _L B: a _{AX R: X L A = BO} R. That is,

The relationship is obtained. Therefore, from [Equation 1]

Is obtained. This is the coordinate in the X-axis direction on the target coordinate T of the left end 22a. Similarly, the diameter of the crystallization interface 22 is calculated by calculating the coordinate in the X-axis direction for the right end 22b and taking the difference between the two.

の関係から、

となる。なお、左端２２ａ及び右端２２ｂは同じ高さなので、いずれの計測位置を用いてＹ_Ｐを求めてもよい。 On the other hand, the Y coordinate (tilt angle θ from the vertical direction) is

From the relationship

It becomes. Since left 22a and right edge 22b are the same height, it may be obtained Y _P using any measurement position.

の式に従って算出される。これにより加熱コイルの上端の高さをｈ１（既知の値）とすると、溶融帯の加熱コイル内部に隠れた部分の下ゾーン長は、ｈ１−ｈとなる。よって演算処理部１６ｃは晶出界面２２の直径を示す直径データ２３と、下ゾーン長の長さを示す下ゾーン長データ２５ａを算出することができる。こうして演算処理部１６ｃを介して測量されたこれらのデータは後述の制御部４４に出力される。 Here, the distance between each camera and the left end 22a and the right end 22b of the crystallization interface 22 to be measured is considered. Since the first camera 12 and the second camera 14 are arranged at a position sufficiently longer than the diameter of the crystallization interface from the crystallization interface as described above, the left end observed from the first camera 12 and the second camera 14 It can be considered that 22a and the right end 22b do not move back and forth with respect to the first camera 12 and the second camera 14 by the manufacturing process. Further, the line segment connecting the left end 22a and the right end 22b passes through the rotation axis 24a of the semiconductor single crystal (cone portion 24) and can be considered to be parallel to the line segment O _R O _L (see FIG. 1B). ). Therefore, the length of the perpendicular extending from P (X _P , Y _P ) to the line segment O _R O _L can be r (constant), and this can be used as a known value. Therefore, as shown in FIG. 2B, since the first camera 12 and the second camera 14 are shooting at an elevation angle θ, the height h of the crystallization interface 22 is

It is calculated according to the following formula. Thus, assuming that the height of the upper end of the heating coil is h1 (known value), the lower zone length of the portion hidden inside the heating coil of the melting zone is h1-h. Therefore, the arithmetic processing unit 16c can calculate the diameter data 23 indicating the diameter of the crystallization interface 22 and the lower zone length data 25a indicating the length of the lower zone length. These data thus measured through the arithmetic processing unit 16c are output to the control unit 44 described later.

  Next, FIG. 3 shows a control method at the time of manufacturing an FZ semiconductor crystal incorporating the surveying method at the time of manufacturing the FZ method semiconductor crystal, and a camera arrangement of the control system 40 embodying the control method. FIG. 4 and FIG. 5 are flowcharts of the control system 40, respectively.

  The control method at the time of manufacturing the FZ semiconductor crystal is to measure the diameter and the height position of the crystallization interface 22 by using the semiconductor crystal surveying method at the time of manufacturing the FZ method semiconductor single crystal, and also by the heating coil 28. The zone length of the melting zone 20 of the semiconductor raw material rod 18 which is the raw material of the semiconductor crystal melted and heated is measured, and the diameter and the zone length become the designed diameter and designed zone length designed in advance for each predetermined time. As described above, the moving speed of the semiconductor raw material rod 18 and the output of the heating coil 28 are controlled, and the control system 40 embodying the control is a surveying system 10, a measuring unit 42, and a control unit 44 serving as a control means. Etc. Further, in the control system 40, as shown in FIG. 4, the high-frequency current is output to the upper shaft motor 46 that controls the speed at which the semiconductor raw material rod 18 is fed to the heating coil 28 and the heating coil 28 that performs induction heating. An oscillator 48 to be adjusted and a lower shaft motor 50 for pulling down the semiconductor single crystal (cone portion 24, throttle portion 26) crystallized below the heating coil 28 at a predetermined speed. Furthermore, it has an upper shaft rotation motor 47 that rotates the semiconductor raw material rod 18 at a predetermined rotation speed, and a lower shaft rotation motor 51 that rotates the semiconductor single crystal at a predetermined rotation speed.

  The measurement unit 42 includes a third camera 42a, an image processing unit 42b, and an arithmetic processing unit 42d. As shown in FIG. 3, the third camera 42 a is disposed in the horizontal direction at a position higher than the upper end of the heating coil 28. The image processing unit 42b is connected to the control unit 44 and the third camera 42a, and the image processing unit 42b operates the shutter of the third camera 42a when the survey command signal is input from the control unit, and heats the melting zone 20 A portion exposed above the coil 28 is photographed, and the photographed image is output to the image processing unit 42b as the third image data 42c. The image processing unit 42b detects the upper end of the molten zone 20 on the third image data 42c, that is, the elution interface 18a of the semiconductor raw material rod 18 by binarization processing or the like, and uses the coordinates as third coordinate data 42e to calculate the processing unit 42d. Output to.

  Here, it is assumed that the positional relationship between the third camera 42a and the heating coil 28 is known. The distance from the semiconductor material rod 18 of the third camera 42a is assumed to be sufficiently larger than the diameter of the semiconductor material rod 18. Further, since the distance between the third camera 42a and the rotation center axis of the semiconductor raw material rod 18 is constant, the height of the portion of the molten zone 20 exposed at the top of the heating coil 28 is the third image output by the third camera 42a. Only the vertical component of the data 42c needs to be calculated.

  The calculation processing unit 42d calculates the upper zone of the portion exposed above the heating coil 28 of the melting zone 20 by calculating with the coordinate in the height direction of the elution interface 18a on the third image data and the above-described mathematical expression. The length is calculated and output to the control unit 44 as the measured upper zone length data 25b. Note that the arithmetic processing unit 42d can also measure the diameter of the elution interface 18a and output it to the control unit 44 in the same manner as described above.

  Thus, the upper zone length of the portion exposed upward from the heating coil 28 of the melting zone 20 is measured via the third camera 42a, and the melting zone 20 is heated via the first camera 12 and the second camera 14 described above. Since the lower zone length of the portion formed inside the coil 28 can be measured, the zone length of the molten zone 20 is obtained by adding the upper zone length and the lower zone length from the FZ method drawing process to the initial cone forming process. Can be surveyed.

  The control unit 44 is connected to the surveying system 10, and when the control unit 44 outputs a survey command signal to the surveying system 10 every predetermined time, the diameter data 23 of the crystallization interface 22 calculated from the surveying system 10 and the lower zone length Data 25a is input every predetermined time. The control unit 44 is also connected to the measurement unit 42. When the control unit 44 outputs a survey command signal to the measurement unit 42 at predetermined time intervals, the upper zone length data 25b calculated from the measurement unit 42 is output at predetermined time intervals. Entered. In the control unit 44, the upper zone length data 25a and the lower zone length data 25b are added to obtain the zone length data 25 of the molten zone 20. Here, the predetermined time interval refers to an interval obtained by equally dividing the time from the seed drawing step of the FZ method to the initial stage of the cone portion forming step for expanding the crystal diameter by a considerable number.

  In addition, the storage medium (not shown) disposed in the control unit 44 stores design diameter data of the crystallization interface 22 and design zone length data for each predetermined time. The design diameter data and the design zone length data for each predetermined time can be read, and the difference between the diameter data 23 and the zone length data 25 is calculated.

  The control unit 44 is connected to the upper shaft motor 46 via the PID calculator 46a, and differentially amplifies the difference between the value of the input diameter data 23 and the value of the design diameter data, and the upper part via the PID calculator 46a. The feeding speed of the semiconductor material rod 18 of the shaft motor 46 can be controlled. Here, when the value of the diameter data 23 is larger (smaller) than the value of the design diameter data, the control unit 44 outputs a command to lower (increase) the driving speed of the upper shaft motor 46 to the upper shaft motor 46, and the semiconductor material Control is performed to decrease (increase) the feeding speed of the rod 18 toward the heating coil 28. The control unit 44 is connected to the upper shaft rotation motor 47 through a PID calculator 47a. In this embodiment, the control unit 44 outputs a constant current to the upper shaft rotation motor 47 to The rotation speed is kept constant, and the rotation speed of the semiconductor material rod 17 is kept constant.

  The control unit 44 is connected to the lower shaft motor 50 via the PID computing unit 50a. In the present embodiment, the control unit 44 outputs a constant current to the lower shaft motor 50 to keep the driving speed of the lower shaft motor 50 constant. The pulling rate of the semiconductor single crystal is kept constant. Further, the control unit 44 is connected to the lower shaft rotation motor 51 via the PID computing unit 51a. In this embodiment, the control unit 44 outputs a constant current to the lower shaft rotation motor 51 to rotate the rotation speed of the lower shaft rotation motor 51. Is kept constant, and the rotation speed of the semiconductor single crystal is kept constant.

  The control unit 44 is connected to an oscillator 48 that adjusts the output of the heating coil 28 via a PID calculator 48a, and differentially amplifies the difference between the input zone length data 25 and the design zone length data, thereby causing a PID calculator. The heating output of the oscillator 48 can be controlled via 48a. Here, when the value of the zone length data is smaller (larger) than the value of the design zone length data, the control unit 44 issues a command to increase (decrease) the high-frequency current of the oscillator 48 so that the zone length becomes longer (shorter). Output to the oscillator 48 and control to increase (decrease) the heating output of the heating coil 28 is performed.

  Here, the control of the diameter of the crystallization interface 22 and the control of the zone length of the melting zone 20 affect each other. Therefore, the control of the upper shaft motor from the control unit 44 is performed so that the control of the diameter and the control of the zone length are alternately repeated (the control of the diameter is performed first) to bring the design diameter and the design zone length at a predetermined time closer. 46 and control to converge the output to the oscillator 48 within a certain range in a self-consistent manner.

  The production of a semiconductor single crystal by the FZ method is performed in a high-temperature chamber that is shielded from the outside air. Therefore, in the surveying system 10 and the control system 40 according to the present embodiment, it is necessary to provide outside the chamber so that the first camera 12 and the second camera 14 do not melt. FIG. 6 shows the first camera 12 and the second camera 14 provided outside the chamber, and the camera plate 56 for holding them.

  The outer wall (not shown) of the chamber is provided with a transparent viewing window 52 and a flange 54 that seals outside air while holding the viewing window 52 so that the inside can be viewed from the outside. The camera plate 56 is a relay plate 58 fixed to the flange 54, an L-shaped plate 60 fixed to the relay plate 58, and a camera mounting plate mounted with the first camera 12 and the second camera 14 and held by the L-shaped plate 60. 62. Any member may be used as long as it has a certain rigidity, such as stainless steel, and it is preferable that the entire camera plate 56 has sufficient rigidity even when the members are assembled. Further, it is also preferable to use a ceramic having a small thermal expansion coefficient in order to suppress a change in dimensions due to a temperature change.

  The relay plate 58 is formed with a through hole 58a formed through the screw 54 (not shown) so as to correspond to the screw hole 54a formed in the flange 54. Therefore, the relay plate 58 is fixed to the flange 54 by inserting a screw (not shown) into the through hole 58a and screwing the screw (not shown) into the screw hole 54a.

  In the L-shaped plate 60, a horizontal member 60 a forming an L-shape is mounted on the horizontal portion of the relay plate 58, and a vertical member 60 b holds the camera mounting plate 62. A first elongated hole (not shown) is formed in the longitudinal direction of the horizontal member 60a, and a first screw hole (not shown) is formed at a position corresponding to the elongated hole (not shown) of the relay plate 58. And the 1st screw hole (not shown) and the 1st long hole (not shown) are connected and the 1st screw (not shown) which screws both together is provided. Thereby, the L-shaped plate 60 can be slid in the horizontal direction with respect to the relay plate 58 by loosening the first screw (not shown), and is fixed to the relay plate 58 at a predetermined position by screwing.

  Similarly, a second elongated hole (not shown) is formed in the vertical member 62b that contacts the L-shaped plate 60 of the camera mounting plate 62, and the second elongated hole (not illustrated) of the vertical member 60b of the L-shaped plate 60 is formed. A second screw hole (not shown) is formed in the corresponding portion, and a second screw (not shown) that connects the second screw hole (not shown) and the second elongated hole (not shown) to screw them together. Is provided. Thereby, the camera mounting plate can be slid in the vertical direction with respect to the L-shaped plate 60 by loosening the second screw (not shown), and the camera mounting plate 62 is fixed to the predetermined position of the L-shaped plate 60 by screwing. In FIG. On the horizontal member 62a of the camera mounting plate 62, the first camera 12 and the second camera 14 are mounted with a constant distance (the distance between the focal points is d) and directed in the same optical axis direction. Further, for example, when the camera mounting plate 62 is fixed by one second screw (not shown), the first camera 12 and the first camera 12 are changed by changing the mounting angle of the vertical member 62b to the vertical member 60b of the L-shaped plate 60. 2 The elevation angle toward the heating coil in the chamber of the camera 14 can be adjusted.

  In the present embodiment, the first camera 12 and the second camera 14 can be realized by using the same camera. FIG. 7 shows a modification in the case where a single camera is used. FIG. 8 shows a schematic diagram of a control system 90 to which the modification of FIG. 7 is applied and a surveying system 80 constituting the control system 90. As shown in FIG. 8, the control system 90 is basically similar to the control system 40 described above, but the surveying system 80 constituting the control system 90 includes a fourth camera 64, a stepping motor 66, a slide stage 68, and a PLC control unit. 70, a motor controller 72, an image processing unit 74, and an arithmetic processing unit 76.

  As shown in FIG. 7, the fourth camera 64 has a stepping motor 66 that rotates at a predetermined rotation angle for each pulse attached to a ball screw 68c that is a rotating shaft, and a helicoid type on a slide stage 68 that can slide the position relative to the ball screw 68c. Mounted on. When this modification is applied to the camera mounting plate 62 described above, the slide stage 68 may be mounted on the horizontal member 62 a of the camera mounting plate 62.

  The PLC control unit 70 is interposed between the image processing unit 74 and the control unit 44 and is also connected to the motor controller 72. When receiving a survey command signal from the control unit 44, the PLC control unit 70 outputs a shooting command signal to the image processing unit 74 when the slide stage 68 is in either the first position 68a or the second position 68b. At the same time, the address data 69a indicating the first position 68a of the slide stage 68 or the address data 69b indicating the second position 68b at a distance d from the first position 68a is output to the motor controller 72 to the motor controller 72.

  The motor controller 72 manages the address on the stepping motor 66, and the present address data 69c and the address data 69a indicating the first position 68a input from the PLC control unit 70, or the address data 69b indicating the second position 68b, It is assumed that a pulse having the number of steps corresponding to the difference between the current address data 69c can be updated for each pulse and output to the driver of the stepping motor 66. Note that the motor controller 72 performs calibration at the time of activation, rotates the stepping motor 66, and conveys the slide stage 68 to the first position 68a.

  The PLC control unit 70 outputs a shooting command signal to the image processing unit 74, and the image processing unit 74 first acquires the first image data 64a from the fourth camera 64 at the first position 68a as described above. Thereafter, the PLC control unit 70 outputs the address data 69b of the second position 68b located at a distance d apart to the motor controller 72, and the motor controller 72 takes the difference between the current address data 69c and the address data 69b, A pulse having the number of steps corresponding to the difference is sent to a driver (not shown) of the stepping motor 72, the stepping motor 72 is rotated, and the fourth camera 64 is conveyed to a second position 68b that is separated from the first position 68a by d. . The PLC control unit 70 reads the current address data 69c on the stepping motor 66 indicated by the motor controller 72. If the address value matches the address data 69b indicating the second position 68b, the PLC control unit 70 again returns to the image processing unit 74. The image processing unit 74 obtains the second image data 64 b from the fourth camera 64 by outputting a shooting command signal.

  The image processing unit 74 binarizes each time the first image data 64a and the second image data 64b are input to detect the left end 22a and the right end 22b of the crystallization interface 22, respectively, and the first coordinate data as described above. 74 a and the second coordinate data 74 b are output to the arithmetic processing unit 76.

  When the first coordinate data 74a and the second coordinate data 74b are input, the calculation processing unit 76 performs the same calculation as the calculation processing unit 16c described above, and the diameter data 23 of the crystallization interface 22 and the lower zone length data 25a. Is output to the control unit 44.

  When acquiring each image data after the next predetermined time, since the fourth camera 64 is in the second position, the second image data 64b is acquired first using the same method as described above, and then the first data is acquired. It is only necessary to control so as to be able to.

  As described above, according to the present embodiment, the diameter of the crystallization interface 22 of the semiconductor single crystal formed in the heating coil 28 is measured from an oblique direction from the drawing process of the FZ method to the initial stage of the cone part forming process. Even in this case, the diameter can be measured with high accuracy in the same manner as the image measurement from the horizontal direction. Furthermore, in the process of calculating the diameter of the crystallization interface 22 by image measurement, the height of the crystallization interface 22 can also be calculated, so that the heating coil 20 having a zone length of the melting zone 20 formed by heating and melting the semiconductor raw material rod 18 is obtained. The length of the component formed inside can also be accurately measured. Therefore, it is possible to control the semiconductor crystal growth with high accuracy in the above-described steps. Further, since it is possible to use a single camera for image measurement, it is not necessary to align the optical axes of the cameras in parallel, and there is no fear of optical axis deviation, so that the reliability of image measurement is improved.

  In the present embodiment, the description has been made focusing on the FZ method from the drawing process to the initial stage of the cone portion forming process, but in both the first camera 12 and the second camera 14, the crystallization interface 22 is formed below the heating coil 28. However, since it is possible to take a picture, the present invention can also be applied to the process after the initial stage of the cone part forming process.

  Combining the surveying method, surveying system, and the above surveying method when manufacturing the FZ method semiconductor crystal, which can easily control the diameter of the crystallization interface of the semiconductor crystal that appears from the FZ method squeezing process to the cone part forming process with a simple configuration. It can be used as a control method and a control system when manufacturing the FZ method semiconductor crystal.

It is a schematic diagram which shows the camera arrangement | positioning of the surveying system which concerns on this embodiment. It is a conceptual diagram of the triangulation of the survey system which concerns on this embodiment. It is a schematic diagram which shows the camera arrangement | positioning of the control system which concerns on this embodiment. It is a block diagram of the control system concerning this embodiment. It is a flowchart of the control system which concerns on this embodiment. It is the schematic diagram which mounted the camera which comprises the surveying system which concerns on this embodiment on the camera plate. It is a schematic diagram which shows the modification of the surveying system which concerns on this embodiment. It is a block diagram in the modification of the control system which concerns on this embodiment. It is a schematic diagram which shows the manufacturing process of the FZ method semiconductor single crystal which concerns on a prior art. It is a schematic diagram which shows the manufacturing process of the FZ method semiconductor single crystal which concerns on a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ......... Surveying system, 12 ......... First camera, 14 ......... Second camera, 16a ......... Image processing unit, 16b ......... Image processing unit, 16c ......... Calculation processing unit, 18 ... ... Semiconductor raw material rod, 20 ......... Melting zone, 22 ......... Crystal interface, 24 ......... Cone part, 26 ......... Throttle part, 28 ...... Heating coil, 30 ......... First image data, 32... Second image data 40... Control system 42... Measurement unit 44 44 Control unit 46 Upper shaft motor 47 Upper shaft rotation motor 48 ... Oscillator, 50 ......... Lower shaft motor, 51 ......... Lower shaft rotation motor, 52 ......... Peeping window, 54 ...... Flange, 56 ...... Camera plate, 58 ...... Relay plate, 60 ... … L-shaped plate, 62 camera mounting plate, 64 ……… Camera, 66 ……… Steppin Motor, 68 ......... Slide stage, 70 ... PLC control unit, 72 ......... Motor controller, 74 ......... Image processing unit, 76 ......... Calculation processing unit, 80 ...... Surveying system, 90 ... ... Control system, 110 ... Semiconductor rod, 111 ... Melting zone, 112 ... Cone, 113 ... Squeezed part, 114 ... Induction heating coil, 116 ... Seed crystal, 127 ... ...... Single crystal.

Claims (8)

The diameter of the crystallization interface of the semiconductor single crystal that is crystallized inside the heating coil in the initial stage of the cone forming step for expanding the crystal diameter from the seed drawing step of the FZ method for manufacturing a semiconductor single crystal,
The crystallization of a first camera arranged at a height position different from the crystallization interface and a second camera arranged at the same height position as the first camera and having an optical axis parallel to the first camera. A surveying method at the time of manufacturing an FZ method semiconductor crystal, wherein the surveying is performed through a triangulation calculation process using parallax with respect to an interface.   2. The FZ method semiconductor device according to claim 1, wherein the second camera is obtained by translating the first camera to a position where the second camera is provided while maintaining a constant optical axis direction. 3. Survey method at the time of crystal production.   3. The surveying method for manufacturing an FZ method semiconductor crystal according to claim 1, wherein, in the triangulation calculation processing, the diameter is measured and the height position of the crystallization interface is measured.   Using the semiconductor crystal surveying method during the manufacture of the FZ method semiconductor single crystal according to claim 3, the diameter and height position of the crystallization interface are measured, and the semiconductor crystal melted and heated by the heating coil is measured. The zone length of the melting zone of the semiconductor raw material rod as a raw material is measured, and the moving speed of the semiconductor raw material rod is such that the diameter and the zone length become a designed diameter and a designed zone length designed in advance for each predetermined time. And an output of the heating coil, and a control method at the time of manufacturing an FZ method semiconductor single crystal. First image data is output by photographing the crystallization interface of the semiconductor single crystal that is crystallized inside the heating coil in the initial stage of the cone forming process for expanding the crystal diameter from the seed drawing process of the FZ method for manufacturing a semiconductor single crystal. A first camera disposed at a different height from the crystallization interface;
A second camera disposed at the same height as the first camera, having an optical axis parallel to the first camera, photographing the crystallization interface and outputting second image data;
The left and right ends of the crystallization interface on the first image data and the second image data are detected, and the crystallization interface is obtained by triangulation calculation using parallax between the first camera and the second camera. Surveying means for measuring the distance between the left end and the right end of the crystallizing interface as a diameter of the crystallization interface;
A surveying system for manufacturing an FZ method semiconductor single crystal.   6. The FZ method semiconductor device according to claim 5, wherein the second camera is obtained by translating the first camera to a position where the second camera is provided while keeping the optical axis direction constant. Surveying system when manufacturing crystals.   The surveying system according to claim 5 or 6, wherein the surveying unit measures the diameter and surveys the height position of the crystallization interface. The diameter and height position of the crystallization interface are calculated by the semiconductor crystal surveying system at the time of manufacturing the FZ method semiconductor single crystal according to claim 7, and at the same time, the semiconductor crystal is melted and heated by the heating coil. Measuring means for measuring the zone length of the melting zone of the semiconductor raw material rod;
Control means for controlling the movement speed of the semiconductor raw material rod and the output of the heating coil so that the diameter and the zone length become the designed diameter and the designed zone length designed in advance for each predetermined time;
A control system for manufacturing an FZ method semiconductor single crystal.

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