JP2514674B2 - Single crystal pulling device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a single crystal pulling apparatus for producing a silicon single crystal doped with a high concentration of antimony.

[Prior Art] Generally, a high-concentration antimony-doped silicon single crystal has been conventionally used as a silicon substrate for manufacturing an epitaxial planar transistor.
For example, a (111) plane silicon wafer having a low resistivity of 0.018 Ωcm or less is used.

On the other hand, with the recent miniaturization of CMOS LSI patterns, a so-called MOS epitaxial technique in which an epitaxial layer is formed on a substrate as a measure against latch-up and the epitaxial layer is used as an element active region is spreading, As a substrate used for this, a silicon wafer having a resistivity of 0.02 to 0.03 Ωcm and a (100) plane doped with high concentration of antimony or arsenic tends to be frequently used.

Further, in any of the above wafers, the crystal diameter has recently been increased (125,150 mmφ, etc.), and there is a strong demand for a more perfect dislocation-free crystal in order to improve the yield.

By the way, in the production of these high-concentration antimony-doped single crystals, the segregation coefficient of antimony in silicon is 0.023, which is smaller than that of other dopants. The antimony concentration in the silicon melt during pulling must be fairly high. For example, in order to pull up a crystal having a resistivity of 0.015 Ωcm, it is necessary to raise the antimony concentration to about 1% in the silicon melt.

[Problems to be solved by the invention]

However, in the temperature range of the silicon melt (1400 ° C or higher), since the vapor pressure of antimony is high, the antimony vaporized during pulling up is converted into a furnace inner wall or a quartz crucible as a simple substance or a compound such as an oxide. Easily deposited and adhered on the inner surface of the upper part. In particular, the deposits attached to the inner surface of the upper part of the quartz crucible eventually fall into the silicon melt and attach to the crystal growth interface to cause dislocations, which causes the inhibition of single crystallization.

The present invention has been made in view of the above circumstances, and an object thereof is to evaporate on an inner surface of an upper portion of a quartz crucible when a silicon single crystal highly doped with antimo is manufactured. It is an object of the present invention to provide a single crystal pulling apparatus which can be prevented and can prevent dislocation caused by the fall of the evaporated material into the silicon melt, thereby improving the production efficiency.

[Means for solving problems]

In order to achieve the above object, the present invention, in a single crystal pulling apparatus for pulling and growing a high concentration antimony-doped silicon single crystal by the Czochralski method,
A heater for heating the quartz crucible is provided around the quartz crucible, a heat insulator is provided around the heater, and an upper end of the graphite susceptor holding the quartz crucible is provided with an inner diameter of an upper end portion of the graphite susceptor. An annular plate made of graphite of the same diameter is placed in direct contact with the quartz crucible, and the outer peripheral part of the annular plate projects outward from the graphite susceptor and is close to the heat retaining body. Between the protruding portion of the annular plate, which protrudes outward from the graphite susceptor, and the heater, heat conduction for directly transmitting radiant heat from the heater to the protruding portion of the annular plate. It is characterized in that a space is formed. Further, above the quartz crucible,
It is characterized in that a cooling cylinder for cooling the single crystal being pulled is provided.

[Work]

In the single crystal pulling apparatus of the present invention, since the outer peripheral portion of the annular plate protruding outward from the graphite susceptor is provided close to the heat retaining body provided around the heater, the annular ring The plate is fully heated. Further, since a heat conduction space for directly transmitting the radiant heat from the heater to the protruding portion of the annular plate is formed between the protruding portion of the annular plate and the heater, the radiant heat from the heater may be some member or the like. Without being blocked by
It is efficiently propagated to the protruding portion of the annular plate. Then, the thus heated annular plate is placed on the upper end of the graphite susceptor in a state of being in direct contact with the quartz crucible,
The heat of the annular plate is easily transferred to the quartz crucible. Then, the upper portion of the quartz crucible is sufficiently heated through the annular plate, so that the evaporation of the vapor on the inner surface of the upper portion of the quartz crucible is prevented. Further, since the annular plate is made of the same graphite as the graphite susceptor, heat is easily transferred between the annular plate and the graphite susceptor, which allows the annular plate and the graphite susceptor to come into direct contact with each other. The crucible is heated uniformly throughout.
In addition, a cooling cylinder for cooling the single crystal being pulled is provided above the quartz crucible, so that heat from the heater or heat retaining body is not transferred to the single crystal being pulled more than necessary. Moreover, the crystal surface is not roughened by thermal decomposition and the yield of single crystals does not decrease.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. The present embodiment relates to a single crystal pulling apparatus for pulling and growing a silicon single crystal doped with high concentration antimony.

In the figure, reference numeral 1 is a furnace main body, and a quartz crucible 2 is provided at a substantially central portion of the furnace main body 1. The quartz crucible 2 is attached to a lower shaft 4 which is movable up and down and rotatable via a graphite susceptor 3, and an upper edge portion of the quartz crucible 2 is provided so as to project above the upper end surface of the graphite susceptor 3 by a predetermined length. Has been. On the upper end surface of the graphite susceptor 3, a graphite annular plate 5 having the same diameter as the inner diameter of the upper end portion of the graphite susceptor 3 is fitted on the outer periphery of the upper edge portion of the quartz crucible 2 and The quartz crucible 2 is placed in direct contact with the quartz crucible 2. A heater 7 for controlling the temperature of the silicon melt 6 in the quartz crucible 2 is installed around the quartz crucible 2, and a heat insulating tube (heat insulating tube) is provided between the heater 7 and the furnace body 1. Body 8 is arranged. further,
The outer peripheral portion 5a of the annular plate 5 projects outward from the graphite susceptor 3 and is provided close to the heat retaining cylinder 8.

In addition, the radiant heat from the heater 7 is directly projected between the protruding portion 5b of the annular plate 5 protruding outward from the graphite susceptor 3 and the heater 7. A heat conduction space S that is transmitted to the portion 5b is formed, and this heat conduction space S is formed.
Does not impede the heat transfer that takes place through the heat conducting space S.

A cooling cylinder 10 for cooling the single crystal 9 being pulled is vertically provided at the neck of the furnace body 1, and the single crystal 9 is held inside the cooling cylinder 10 and the neck of the furnace body 1. A wire 11 for pulling up is hung so that it can be raised and lowered and rotated.
Reference numeral 12 is a sight window formed in the shoulder of the furnace body 1 for monitoring the boundary between the surface of the silicon melt 6 and the single crystal 9 being pulled up.

When pulling a silicon single crystal using the single crystal pulling apparatus configured as described above, first, the air in the furnace body 1 is sufficiently replaced with argon gas, and the silicon crucible 2 is stored in advance. After melting the raw material by the heater 7, the temperature of the melted silicon melt 6 is maintained at a temperature suitable for pulling a single crystal, and a predetermined amount of antimony is added into the silicon melt 6. In this state, similarly to the conventional case, the wire 11 is lowered, the seed crystal held at the lower end of the wire 11 is immersed in the silicon melt 6, and then the quartz crucible 2 and the seed crystal are rotated in opposite directions. ,
By pulling up the seed crystal, the single crystal 9 is sequentially grown at the lower end of this seed crystal.

In this case, as described above, antimony in the silicon melt 6 evaporates, but the outer peripheral portion 5a of the annular plate 5 protruding outward from the graphite susceptor 3 is provided with the heat insulating cylinder 8 provided around the heater 7. Since the circular plate 5 is provided close to
It is heated sufficiently. In addition, the graphite susceptor 3 of the annular plate 5
Between the protruding portion 5b protruding further outward and the heater 7,
Since the heat conduction space S for directly transmitting the radiant heat from the heater 7 to the protruding portion 5b of the annular plate 5, the radiant heat from the heater 7 is not blocked by any member or the like, and the annular plate 5 Is efficiently propagated to the protruding portion 5b. The ring plate 5 thus sufficiently heated is placed on the upper end of the graphite susceptor 3 while being in direct contact with the quartz crucible 2, so that the heat of the ring plate 5 is transferred to the quartz crucible 2. easy. Since the upper portion of the quartz crucible 2 is sufficiently heated through the annular plate 5, it is possible to prevent antimony from depositing or adhering to the inner surface of the upper portion of the quartz crucible 2 as a simple substance or a compound such as an oxide. To be done. Therefore, this evaporated material does not drop into the silicon melt 6 and the silicon single crystal being pulled does not have dislocation.

Further, since the annular plate 5 is made of the same graphite as the graphite susceptor 3, heat is easily transferred between the annular plate 5 and the graphite susceptor 3, and thus the annular plate 5 and the graphite susceptor 3 are separated from each other. The quartz crucibles 2, which are in direct contact with each other, are uniformly heated as a whole. Further, since the cooling cylinder 10 for cooling the single crystal 9 being pulled is provided above the quartz crucible 2,
The heat from the heater 7 and the heat insulation cylinder 8 is not transferred to the single crystal 9 being pulled more than necessary, and the crystal surface is not roughened due to thermal decomposition and the yield of the single crystal is not reduced.

For example, using a quartz crucible 2 with an inner diameter of 14 inches,
Using a graphite circular plate 5 with a diameter of 357 mm, an outer diameter of 460 mm, and a thickness of 10 mm, melt 30 kg of polycrystalline silicon, set it to a temperature at which it can be pulled, and add antimony to obtain a silicon single crystal with a diameter of 125 mm. I raised it. At this time, during pulling the single crystal,
On the inner surface of the upper part of the quartz crucible 2, almost no precipitate was scattered and a single crystal having no dislocation was obtained until the end. On the other hand, when the annular plate 5 of the present invention was not used and the other conditions were the same as in the present example, the yellow-brown fluffy deposits adhered to the upper part of the quartz crucible, and As for the dislocation single crystal, only about 1/3 to 1/2 of the expected pulling weight was obtained.

In this example, the silicon single crystal doped with antimony has been described, but [Oi] (interstitial oxygen concentration in the silicon single crystal) is low (1.5 × 10 ¹⁸ atoms).
It can be applied to the pulling of a silicon single crystal (less than / cc) and has the same effect.

〔The invention's effect〕

As described above, according to the present invention, in a single crystal pulling apparatus for pulling and growing a high concentration antimony-doped silicon single crystal, a heater for heating the quartz crucible is provided around the quartz crucible. A heat insulator is provided around the upper end of the graphite susceptor that holds the quartz crucible, and a graphite annular plate having the same diameter as the inner diameter of the upper end of the graphite susceptor is in direct contact with the quartz crucible. And the outer peripheral portion of the annular plate projecting outward from the graphite susceptor and provided close to the heat retaining body, and the annular plate projecting outwardly projecting from the graphite susceptor. A heat conduction space for directly transmitting the radiant heat from the heater to the protruding portion of the annular plate is formed between the portion and the heater. Can be obtained. That is, since the outer peripheral portion of the annular plate protruding outward from the graphite susceptor is provided close to the heat retaining body provided around the heater, the annular plate is sufficiently heated, and Since a heat conduction space for directly transmitting radiant heat from the heater to the protruding portion of the annular plate is formed between the protruding portion of the plate and the heater, radiant heat from the heater is blocked by some member or the like. In this way, the circular plate is efficiently propagated to the protruding portion of the circular plate, and the circular plate is sufficiently heated. The fully heated annular plate is placed on the upper end of the graphite susceptor in direct contact with the quartz crucible, so the heat of the annular plate is easily transferred to the quartz crucible, thus Is heated sufficiently, it is possible to prevent the deposition of antimony vaporized material on the inner surface of the upper part of the quartz crucible, and to prevent the formation of dislocations caused by the fall of this vaporized material into the silicon melt. It has an excellent effect that the production efficiency can be improved. Further, since the annular plate is made of the same graphite as the graphite susceptor, heat is easily transferred between the annular plate and the graphite susceptor, which allows the annular plate and the graphite susceptor to come into direct contact with each other. The crucible is heated uniformly throughout. Further, by providing a cooling cylinder for cooling the single crystal being pulled above the quartz crucible, heat from the heater or the heat retaining body can be transferred to the single crystal being pulled more than necessary. In addition, an excellent effect that the crystal surface is not roughened due to thermal decomposition and the yield of the single crystal is not lowered can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention. 2 ... Quartz crucible, 3 ... Graphite susceptor, 5 ... Annular plate, 5a ... Outer periphery, 5b ... Projection, 7 ... Heater, 8 ...
… Insulating cylinder (insulator), 9 …… single crystal, 10 …… cooling cylinder, S
...... Heat conduction space.

Claims (2)

(57) [Claims] 1. A single crystal pulling apparatus for pulling and growing a silicon single crystal (9) doped with high concentration antimony by the Czochralski method, wherein the quartz crucible (2) is surrounded by the quartz crucible (2). A heater (7) for heating is provided, and a heat insulator (8) is provided around the heater (7), and the graphite susceptor (3) holding the quartz crucible (2) is attached to the upper end of the graphite susceptor (7). An annular plate (5) made of graphite having the same diameter as the inner diameter of the upper end of 3) is placed in direct contact with the quartz crucible (2), and the outer peripheral part of the annular plate (5) ( 5a) protrudes outward from the graphite susceptor (3) and is provided close to the heat retaining body (8), and protrudes outward from the graphite susceptor (3) of the annular plate (5). The heater (7) is provided between the protrusion (5b) and the heater (7). Radiant heat directly al, circular ring plate (5) single crystal pulling apparatus characterized by heat conducting spatial tell protrusion (5b) (S) are formed of. 2. A single crystal pulling apparatus according to claim 1, wherein a cooling cylinder (10) for cooling the single crystal (9) being pulled is provided above the quartz crucible (2). ) Is provided, the single crystal pulling apparatus.