JP3861548B2 - Carbon heater - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a carbon heater suitable for use in a bottom heater that heats a quartz crucible for storing a semiconductor melt from below, particularly in a semiconductor single crystal pulling apparatus.
[0002]
[Prior art]
A semiconductor single crystal pulling apparatus using a CZ method (Czochralski method) has been put into practical use as an apparatus for manufacturing a semiconductor single crystal such as silicon (Si) or gallium arsenide (GaAs). In this semiconductor single crystal pulling apparatus, as shown in FIG. 1, a carbon susceptor 2 is disposed inside a chamber 1, and a semiconductor melt L is stored in a quartz crucible 3 disposed above the carbon susceptor 2, A predetermined single crystal growth temperature is obtained by a cylindrical carbon heater 4 (side heater) in which the semiconductor melt L is disposed around the quartz crucible 3 and a substantially disk-shaped carbon heater 5 (bottom heater) disposed below the quartz crucible 3. The semiconductor single crystal C is sequentially pulled up by the pull-up wire 5 while being heated.
[0003]
FIG. 2 is a front view of the bottom heater 5. The bottom heater 5 includes a heater main body 5a formed in a disk shape, and a pair of terminal portions 5b and 5c provided so as to protrude left and right from the heater main body 5a. It is composed of A circular hole 5d is formed in the center of the heater body 5a, and slits 5e and 5e having a predetermined depth and a predetermined width from the outer peripheral side toward the central point O with respect to the central point O at predetermined angles. Are formed, and a plurality of slits 5f, 5f,... Having a predetermined depth and a predetermined width are formed between the slits 5e, 5e,. .
[0004]
In this way, the slits 5e, 5e,... And the slits 5f, 5f,... Are alternately formed in the heater body 5a, so that the heater body 5a has straight portions 5g, 5g,. The bent portions 5h, 5h, ... and the outer bent portions 5i, 5i, ... are alternately formed, and the straight portions 5g, 5g, ... are indicated by the respective terminal portions 5b, 5c as indicated by arrows. Is a portion where the passage path of the applied current supplied to the bottom heater 5 is linear, and the passage section of the applied current is bent at the bent portions 5h, 5h,..., 5i, 5i,. The applied current is alternated between the straight portions 5g, 5g,... And the bent portions 5h, 5h,..., 5i, 5i,. It flows alternately in the approaching direction, and the applied current flows in this way. It allows the quartz crucible 3 in which the heater main body 5a is disposed above and generally evenly heating can be heated without unevenness.
[0005]
[Problems to be solved by the invention]
By the way, in the conventional bottom heater 5, the applied current concentrates in the bent portions 5h, 5h,..., 5i, 5i,. In order to become high, deterioration of the said site | part is remarkable compared with another site | part. Therefore, the life of the high current density portion dominates the life of the bottom heater 5, and even if the other portions are not deteriorated, the high current density portion, that is, the bent portions 5h, 5h, ..., 5i, 5i, ... The bottom heater 5 had to be replaced in accordance with the deterioration.
[0006]
The present invention has been made in view of the above-described problems, and has the following objects.
(1) Achieving a long life by suppressing deterioration.
(2) Suppresses concentration of applied current.
(3) To improve the maintainability of the semiconductor single crystal pulling apparatus.
[0007]
[Means for Solving the Problems]
The carbon heater of the present invention is formed in a substantially disk shape so that a quartz crucible for storing semiconductor melt is heated from below, and the applied current flows alternately in a direction away from the center of the disk and a direction approaching the center of the disk. A carbon heater in which straight portions and bent portions are alternately formed,
The thickness of the bent portion is formed by thickened relative to so that the linear portion of the cross-sectional area is relatively increased in the bent portion applied current the current density is increased to concentrate to the straight portion This solves the above problem.
The present invention, the width of the slit formed toward the disk center from the outer peripheral side between the straight portions adjacent to each other, concentration relaxation of the applied current in the inside of the inner bent portion of the disc center side of the bent portion as means and is narrower the closer to the disk center, or the width of the slit formed toward the outer circumferential side of a disk centered between the straight portions adjacent to each other, a disc of the bent portion Means that are formed so as to be farther away from the center of the disk can be employed so that the concentration of the applied current on the inner side of the outer bent portion on the side farther from the center is alleviated .
The carbon heater resistance value setting method of the present invention is the above-described carbon heater resistance value setting method, wherein the overall resistance value of the carbon heater is set in advance,
The overall resistance value can be adjusted by increasing the thickness of the bent portion and reducing the resistance value by reducing the thickness of the linear portion.
In order to achieve the above object, in the present invention, as a first means, in a carbon heater composed of a plurality of straight portions and at least one bent portion, the cross-sectional area of the bent portion is relatively set with respect to the straight portion. Adopt a means to increase.
[0008]
Further, as a second means, the quartz crucible for storing semiconductor melt is formed in a substantially disk shape so as to be heated from below, and the applied current alternates between a direction away from the center of the disk and a direction approaching the center of the disk. In the carbon heater in which the straight portions and the bent portions are alternately formed so as to flow, means for relatively increasing the cross-sectional area of the bent portion with respect to the straight portions is adopted.
[0009]
As a third means, in the second means, a means is adopted in which the width of the slit formed from the outer peripheral side toward the disk center between the adjacent linear portions is narrowed toward the disk center.
[0010]
As a fourth means, in the second or third means, a means is formed in which the width of the slit formed from the center of the disk toward the outer peripheral side between the adjacent straight portions is increased as the distance from the center of the disk increases. adopt.
[0011]
As a fifth means, in each of the above means, as a specific means for relatively increasing the cross-sectional area of the bent portion relative to the straight portion, a means for relatively increasing the thickness of the bent portion relative to the straight portion. Is adopted.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a carbon heater according to the present invention will be described with reference to the drawings. FIG. 3 is a front view and a partial cross-sectional view showing the configuration of the present embodiment. The bottom heater 10 (carbon heater) of the present embodiment is different from the conventional bottom heater 5 described above only in the configuration of the heater main body 10a. Therefore, in the following description, the configuration of the heater main body 10a will be described in detail. explain.
[0013]
This heater body 10a is similar to the conventional bottom heater 5 in that it is formed in a substantially disc shape, but the applied current inside the conventional bent portions 5h, 5h,..., 5i, 5i,. .., 10i, 10i,... Are thicker than the straight portions 10g, 10g,.
[0014]
In this case, since the overall resistance value of the bottom heater 10 is defined in advance as one of the design parameters, the conventional bent portions 5h, 5h, .., 5i, 5i,..., 10i, 10i,.. The thickness of 10 g,... Is adjusted by making it thinner than the conventional straight portions 5 g, 5 g,.
[0015]
Thus, by setting the thickness of the bent portions 10h, 10h,..., 10i, 10i,... Relative to the thickness of the straight portions 10g, 10g,. Without changing the cross-sectional area of the bent portions 10h, 10h,..., 10i, 10i,. Therefore, an increase in current density inside the bent portions 10h, 10h,..., 10i, 10i,... Can be suppressed without changing the design parameters, so that the bent portions 10h, 10h,. It is possible to extend the life of the bottom heater 10 by suppressing the deterioration of 10i, 10i,.
[0016]
Further, the width of the conventional slits 5e, 5e,... Is constant, but the slits 10e, 10e,... Of the present embodiment are slightly deeper toward the back (closer to the center point O). Is narrowed. By forming the slits 10e, 10e,... In this way, the bending rate of the current path at the inner bent portions 10h, 10h,... Located on the hole 10d side is reduced, so that the inner bent portions 10h, 10h,. ... Is less concentrated on the inner side (slits 10e, 10e,...).
[0017]
Further, the slits 10f, 10f,... Of the present embodiment are formed so as to increase in width toward the back (away from the center point O) as opposed to the slits 10e, 10e,. The outer bent portions 10i, 10i,... Located on the outer peripheral side have a shape in which the two bent portions a1, a1,... And the straight portions a2, a2,. By forming the outer bent portions 10i, 10i,... In such a shape, the bending rate of the current path is smaller than that of the conventional outer bent portions 5i, 5i,. The concentration of the applied current on the inner side (slits 10f, 10f,...) Of 10i,.
[0018]
【The invention's effect】
As described above, the carbon heater according to the present invention has the following effects.
(1) According to the present invention, the concentration of the applied current in the bent portion can be suppressed, so that the lifetime of the bent portion can be suppressed and the life of the single crystal can be increased. It is possible to improve the maintainability of the upper device.
(2) Further, according to the present invention, since the bending rate of the current path in the bent portion is reduced, the concentration of the applied current on the inner side of the bent portion is alleviated, thereby suppressing the deterioration of the bent portion and extending the life. it is Ru can.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an outline of a semiconductor single crystal pulling apparatus.
FIG. 2 is a front view showing a bottom heater for a conventional semiconductor single crystal pulling apparatus.
FIG. 3 is a front view and a partial sectional view showing a bottom heater according to an embodiment of the present invention.
[Explanation of symbols]
10 …… Bottom heater (carbon heater)
10a: Heater body 10b, 10c: Terminal portion 10d: Holes 10e, 10f ... Slit 10g ... Linear portion 10h ... Inner bent portion (bent portion)
10i ...... Outer bending part (bending part)

Claims (4)

A quartz crucible for storing semiconductor melt is formed in a substantially disk shape so as to be heated from below, and a linear part and a bent part so that the applied current flows alternately in a direction away from the center of the disk and a direction approaching the center of the disk. Is a carbon heater formed alternately,
The thickness of the bent portion is formed by thickened relative to so that the linear portion of the cross-sectional area is relatively increased in the bent portion applied current the current density is increased to concentrate to the straight portion A carbon heater characterized by that. Width of slit formed towards the disk center from the outer peripheral side between the straight portions adjacent to each other, as the concentration of the applied current in the inside of the inner bent portion of the disc center side is alleviated of the bent portion The carbon heater according to claim 1 , wherein the carbon heater is narrower as it approaches the center of the disk. Width of slit formed toward the outer circumferential side of a disk center between the straight portions adjacent to each other, concentrating the applied current in the inside of the outer bent portion of the side away from the disk center is alleviated of the bent portion The carbon heater according to claim 1 , wherein the carbon heater is formed so as to be farther away from the center of the disk. A carbon heater resistance value setting method according to any one of claims 1 to 3,
  Set the overall resistance value of the carbon heater in advance,
  A resistance value setting method for a carbon heater, characterized in that the overall resistance value is adjusted by increasing the thickness of the bent portion and thereby decreasing the resistance value, thereby reducing the thickness of the linear portion. .

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