JPH09221382A - Device for pulling up single crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for pulling up a single crystal with which the use of easily producible doping agents is possible and the easy execution of the control of the timing for supplying the doping agents and the amts. of the doping agents to be supplied is possible. SOLUTION: A doping agent supplying mechanism 80 which supplies the doping agents Dp to a crucible has a pair of belt wheels 92, 93 which are arranged to be spaced from each other, a belt 95 which is spread at these belt wheels 92, 93, a stepping motor which rotationally drives the belt wheel 92 and many containers 99 which are circumferentially disposed at the belt 95 and in which the doping agents Dp are respectively stored.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single crystal pulling apparatus, and more particularly to a single crystal pulling apparatus having an improved supply of a dopant.

[0002]

2. Description of the Related Art The CZ method has been conventionally known as one of the methods for growing a semiconductor single crystal such as silicon (Si) or gallium arsenide (GaAs). In this CZ method, a semiconductor raw material is used as a semiconductor melt in a crucible, and a semiconductor single crystal is pulled up from this semiconductor melt and grown.

As one of the CZ methods, a method has been proposed in which a crucible is replenished with a granular semiconductor raw material in the process of growing a semiconductor single crystal. In addition, the semiconductor melt,
A dopant containing boron (B) (when making a p-type silicon single crystal), phosphorus (P) (when making an n-type silicon single crystal), etc. is added as necessary to keep the resistance in the growth axis direction constant. Is added.

Since it is necessary to supply only an appropriate amount of this doping agent at an appropriate timing, in the conventional single crystal pulling apparatus, for example, the doping agent supply as disclosed in Japanese Patent Application Laid-Open No. 2-18377 is used. The mechanism is used. This doping agent supply mechanism uses a large number of doping agent chips having the same shape, the same weight, and the same concentration. A cylinder for loading a large number of the doping agent chips in a row and one doping agent chip pushed out from the cylinder. It consists of a piston.
Therefore, an appropriate amount of the dopant can be supplied by extruding an appropriate number (for example, one) of the dopant chips at an appropriate timing.

[0005]

However, in such a single crystal pulling apparatus, there is a problem that it is difficult to manufacture a dopant chip having the same shape, the same weight and the same concentration.

In view of the above circumstances, the present invention provides a single crystal pulling apparatus which can use a dopant which is easy to manufacture and which can easily control the timing and the amount of the dopant supplied. The purpose is to do.

[0007]

In the first invention of the present invention, a crucible for storing a semiconductor raw material, a heater for heating the crucible to turn the semiconductor raw material into a semiconductor melt, and a semiconductor single crystal from the semiconductor melt. A single crystal pulling mechanism for pulling the single crystal, a raw material supply mechanism for supplying a granular semiconductor raw material to the crucible, and a doping agent supply mechanism for supplying a doping agent to the crucible, wherein the doping agent supply mechanism is A pair of belt wheels that are spaced apart from each other, a belt that is stretched around the belt wheel, and a rotation drive mechanism that rotationally drives the belt,
A plurality of containers are provided around a rotating belt, each container containing a doping agent. Therefore, when supplying the dope, for example, an equal amount of granular dope is put in each container, the belt is rotated by the rotation drive mechanism, and the containers are turned one by one at the folded portion of the belt at an appropriate timing. Make it fall.

In the second aspect of the present invention, the plurality of containers are
It is characterized in that the capacities are equal to each other and are circumferentially provided around the belt at regular intervals. Therefore, when each container is filled with the same amount of the doping agent, an equal amount of the doping agent is placed in each container. Further, since each container is provided around the belt at regular intervals, it is possible to supply an equal amount of the doping agent each time the belt is rotated by an equal angle.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 4, the single crystal pulling apparatus 100 according to the present embodiment is a crucible 3 for storing a semiconductor raw material such as a granular semiconductor raw material Sc1 and heating for heating the crucible 3 to be a semiconductor melt Sc2. Vessel 4, single crystal pulling mechanism 5 for pulling up semiconductor single crystal Sc3 from semiconductor melt Sc2, heat shield 6 for heat insulation arranged around heater 4, and crucible for supporting crucible 3 so that it can be driven up and down. An elevating mechanism 7, a crucible 3, a heater 4, a single crystal pulling mechanism 5, a heat shield 6, an airtight container 8 in which the crucible elevating mechanism 7 is contained, and a raw material supply mechanism 70 for supplying the granular semiconductor raw material Sc1 to the crucible 3. , And a doping agent supply mechanism 80 for supplying the doping agent Dp to the crucible 3.

The crucible 3 is made of substantially hemispherical quartz (SiO2).
Made of an outer crucible 11 made of quartz, and an inner crucible 12 made of cylindrical quartz (SiO 2) standing upright inside the outer crucible 11. A plurality of communication holes 13 that communicate with each other are formed.

The heater 4 heats and melts a raw material obtained by crushing a lump of a polycrystalline semiconductor or a granular semiconductor raw material Sc1 as a semiconductor raw material in the outer crucible 11 to keep the resulting semiconductor melt Sc2 warm. In the embodiment, a resistance heater is used.

The crucible raising / lowering mechanism 7 includes a susceptor 15 on which the outer crucible 11 is placed, a shaft 16 for freely raising and lowering the susceptor 15, and an ascending / descending / rotating drive mechanism for freely raising / lowering and rotating the shaft 16. (Not shown). The elevating / rotating drive mechanism includes, for example, a hydraulic cylinder and an electric motor.

The raw material supply mechanism 70 includes a granular semiconductor raw material Sc.
1 is stored and supplied, and the granular semiconductor raw material Sc
1. Raw material supply pipe 71 for allowing 1 to flow down naturally and supplying it to the crucible 3.
have.

The doping agent supply mechanism 80 penetrates the lid portion of the airtight container 8 and the inner crucible 12 inside the outer crucible 11 of the crucible 3.
Supply pipe 81 arranged toward the outer side of the hopper, and a hopper 8 connected to and connected to the upper end of the supply pipe 81 of the dopant.
2 and a doping agent charging machine 90 for charging the doping agent Dp to the hopper 82.

As shown in FIG. 1, the dope depositing machine 90 has a body frame 91 extending in the horizontal direction, and a pair of belt wheels 92 arranged and supported at both ends of the body frame 91 in the extending direction. , 93, a belt 95 stretched around the belt wheels 92, 93, and a rotary drive mechanism that rotationally drives the belt 95, and the one step (left side of FIG. 1) rotationally driving the stepping wheel shown in FIG. A motor 97, a control mechanism 98 for driving and controlling the stepping motor 97, and a plurality of containers 99, which are provided around the outer peripheral surface of the belt 95 as shown in FIG. 1 and each store a dope Dp, are provided.

The belt pulleys 92, 93 have a large number of teeth provided on the outer peripheral surface thereof, and the belt 95 has teeth formed on the inner peripheral surface thereof so as to fit with the teeth of the belt pulleys 92, 93. It is a thing. Further, container mounting plates 95a are formed on the outer peripheral surface of the belt 95 at regular intervals d in the circumferential direction. When each container 99 is located above the body frame 91,
It has a bucket shape with its open end facing upwards, and is made of the dopant Dp.
And a joining plate portion 99b that is projectingly provided at the lower end of the container body 99a and is bolted to the corresponding container mounting plate 95a. Also, each container 9
The container bodies 99a of 9 have the same volume, and
As will be described later, it has a capacity for storing an appropriate amount of the dopant Dp.

The control mechanism 98 shown in FIG. 2 drives and controls the stepping motor 97 shown in FIG. 2 so that the dope Dp is introduced into the hopper 82 from the container 99 shown in FIG. 1 at a timing described later.

In the present embodiment, the dopant Dp is high in an element called a dopant such as boron (B) (when making a p-type silicon single crystal) or phosphorus (P) (when making an n-type silicon single crystal). It is a large number of silicon particles added at a concentration.

Further, as the granular semiconductor raw material Sc1 shown in FIG. 4, for example, polycrystalline silicon granules deposited in a granular form from a gas raw material by a thermal decomposition method are preferably used.

Next, a method of forming the semiconductor single crystal Sc3 by using the above single crystal pulling apparatus 100 will be described.

First, a raw material obtained by crushing a lump of a polycrystalline semiconductor as a semiconductor raw material, and an appropriate amount of grains or lumps of a doping agent such as the doping agent Dp are put in the outer crucible 11. Airtight container 8
The inside is evacuated by a vacuum pump or the like to be in a vacuum state, and the airtight container 8
An inert gas such as argon (Ar), which is an atmospheric gas, is introduced therein. Then, the shaft 16 is rotated on the horizontal plane at a constant angular velocity about the axis, whereby the outer crucible 1
While rotating 1 at a constant angular velocity, the heater 4 is energized to heat the raw material in the outer crucible 11 to a temperature equal to or higher than the single crystal growth temperature, and the raw material is melted to form a semiconductor melt Sc2.

After all the raw materials become the semiconductor melt Sc2, the inner crucible 12 is placed in the outer crucible 11 to obtain the double-structured crucible 3. After that, the electric power of the heater 4 is adjusted to keep the vicinity of the central liquid surface of the semiconductor melt Sc2 at the single crystal growth temperature, and the seed crystal Sc4 suspended by the pulling shaft 5a of the single crystal pulling mechanism 5 is used to melt the semiconductor. After being soaked in the liquid Sc2, the seed crystal Sc4 is pulled upward in the vertical direction.
A semiconductor single crystal Sc3 is grown using 4 as a nucleus. Here, after the seed crystal Sc4 is made dislocation-free, the diameter of the semiconductor single crystal Sc3 is gradually increased to a semiconductor single crystal Sc3 having a predetermined diameter, and after the semiconductor single crystal Sc3 becomes the predetermined diameter, The semiconductor single crystal Sc3 is formed while maintaining the diameter.

In this crystal growth process, the dopant D
supply amount p1 of p, supply amount m2 of granular semiconductor raw material Sc1,
And the raising and lowering of the crucible 3 by the crucible raising and lowering mechanism 7 are controlled as follows. (See Fig. 3)

That is, from the time when the semiconductor single crystal Sc3 of FIG. 4 approaches the constant diameter portion until the semiconductor single crystal Sc3 is pulled up by a predetermined distance, the crucible 3 is the semiconductor melt S accompanying the formation of the semiconductor single crystal Sc3.
The liquid level of c2 is continuously increased by the amount of decrease.

When the crucible 3 is stopped, the continuous supply of the granular semiconductor raw material Sc1 from the raw material supply pipe 71 of the raw material supply mechanism 70 to the outside of the inner crucible 12 in the outer crucible 11 is started. As shown in FIG. 3, the supply amount m2 is gradually increased at the beginning of the supply, and when the supply amount m2 is in balance with the growth amount (pulling amount) of the semiconductor single crystal Sc3 in FIG.
An amount corresponding to the pulling weight of c3 is continuously supplied as shown in FIG.

When the continuous supply of the granular semiconductor raw material Sc1 is started, the concentration of the dopant in the crucible 3 shown in FIG. 4 is lowered. Therefore, in order to keep the concentration constant, the dopant supply mechanism 80 is used to dope the crucible 3. Replenish agent Dp.

The behavior of the doping agent supply mechanism 80 will be described below. First, as shown in FIG. 1, the same amount of granular dope agent Dp is preliminarily provided in each vessel 99 of the dope agent feeder 90 of the dope agent supply mechanism 80, which is located above the main body frame 91. Put in each. Since the respective containers 99 have the same volume, by putting the volume of the doping agent Dp in the respective vessels 99, even if the particles of the doping agent Dp are not uniform, the same volume can be easily applied to the respective vessels 99. A doping agent Dp can be added.

Therefore, when the continuous supply of the granular semiconductor raw material Sc1 is started, the control mechanism 98 of the doping agent dosing machine 90 shown in FIG. 2 starts the rotation control of the stepping motor 97. When the stepping motor 97 is driven, the belt 95 is rotationally driven via the belt wheel 92 shown in FIG. 1, and each container 99 containing the doping agent Dp moves to the hopper 82 side. Then, the top of the container 99 reaches the folded-back portion of the belt 95 and falls down, and all the doping agent Dp previously contained in the container 99 is put into the hopper 82. This doping agent Dp flows down through the doping agent supply pipe 81 shown in FIG. 4, and from the lower end thereof, the outer crucible 1 of the crucible 3.
It is supplied to the outside of the inner crucible 12 in 1.

The timing of supplying the doping agent Dp is such that the amount by which the weight of the semiconductor single crystal Sc3 is increased depends on the container 9 in FIG.
This is done at the time when the required amount of one dopant Dp is reached.

Further, the subsequent container 99 is a semiconductor single crystal S
Every time the amount of increase in the pulling weight of c3 reaches the required amount of the doping agent Dp for one container 99, an equal amount of the doping agent Dp is charged into the hopper 82.

Therefore, the doping agent supply mechanism 80 can supply an appropriate amount of the doping agent Dp at an appropriate timing. Further, every time the stepping motor 97 is rotated at an equal angle, that is, every time the belt 95 is rotated at an equal angle, the succeeding container 99 reaches the folded portion of the belt 95, and the doping agent Dp is introduced. Drive control is easy. Furthermore, the granular dope agent Dp that can be used in the dope agent supply mechanism 80 may have irregular particle sizes, and thus can be easily manufactured.

As described above, the semiconductor single crystal Sc3 having a high crystallinity can be formed.

It should be noted that the granular semiconductor raw material Sc1 may be gallium arsenide (GaAs) instead of the polycrystalline silicon granules. In this case, the dopant Dp contains zinc (Zn), silicon (Si) or the like.

[0034]

According to the first aspect of the present invention, when the doping agent is supplied, an equal amount of the doping agent is put in each container, and the belt is rotated by the rotation driving mechanism so that one container is provided. By making each of the belts fall over at the folded portion, a proper amount of the doping agent can be supplied at a proper timing. Further, since the dope agent is put in the container, it is possible to use, as the dope agent, for example, a granular dope agent having a nonuniform particle size for easy production.

According to the second aspect of the present invention, in addition to the above-mentioned effects, by putting the volume of the doping agent in each container, an equal amount of the doping agent can be put in each container. Therefore, the filling of the dope with each container is easy. Further, since the same amount of the doping agent can be supplied each time the belt is rotated by an equal angle, it is easy to control the timing of supplying the doping agent.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of a doping agent supply mechanism of a single crystal pulling apparatus of the present invention.

2 is a plan view of the doping agent supply mechanism of FIG. 1. FIG.

FIG. 3 is a diagram showing a transition of a supply amount of a dopant and a supply amount of a granular semiconductor raw material and a behavior of a crucible in a crystal growth process.

4 is an overall view of the single crystal pulling apparatus of FIG.

[Explanation of symbols]

 3 Crucible 4 Heater 5 Single crystal pulling mechanism 70 Raw material supply mechanism 80 Dope agent supply mechanism 92 Belt wheel 93 Belt wheel 95 Belt 97 Stepping motor (rotational drive mechanism) 99 Container Dp Dopant agent Sc1 Granular semiconductor raw material (semiconductor raw material) Sc2 Semiconductor melt Sc3 Semiconductor single crystal 100 Single crystal pulling apparatus

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hisashi Furuya 1-5-1, Otemachi, Chiyoda-ku, Tokyo Sanritsu Material Silicon Co., Ltd. (72) Inventor Michio Kita 1-297 Kitabukuro-cho, Omiya-shi, Saitama Address Mitsubishi Materials Corporation, Research Institute

Claims (2)

[Claims] 1. A crucible for storing a semiconductor raw material, and a heater for heating the crucible to turn the semiconductor raw material into a semiconductor melt.
A single crystal pulling mechanism including a single crystal pulling mechanism for pulling a semiconductor single crystal from the semiconductor melt, a raw material supplying mechanism for supplying a granular semiconductor raw material to the crucible, and a doping agent supplying mechanism for supplying a doping agent to the crucible. A device, wherein the doping agent supply mechanism is a pair of belt wheels arranged apart from each other, and a belt stretched around the belt wheel,
An apparatus for pulling a single crystal, comprising: a rotation driving mechanism for rotating the belt; 2. The single crystal pulling apparatus according to claim 1, wherein the plurality of containers have the same volume and are provided around the belt at regular intervals.