JPH09315882A - Device for producing semiconductor single crystal and production of semiconductor single crystal therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a single crystal excellent in oxide film dielectric strength characteristics by simply performing the temp. gradient control of a semiconductor single crystal grown with a CZ (Czochralski) method and particularly inhibiting the generation of as-grown defects. SOLUTION: In this device, a shielding cylinder placed so as to encircle single crystal silicon 7 during pulling-up is divided into a first shielding cylinder section 4, a second shielding cylinder section 5 and a third shielding cylinder section 6 to form a telescopic shielding cylinder. A wire 8 wound around a wind-up reel 10 is fastened to the third shielding cylinder section 6 to extend/contract the shielding cylinder by rotating the wind-up reel 10. Also, the first shielding cylinder section 4 is fixed to elevating/lowering rods 3 to elevating/lowering the shielding cylinder by vertically moving the rods 3. At the time of pulling up the single crystal silicon 7, an optional part of the shielding cylinder is contracted by driving the wind-up reel 10 to subject a specific region of the single crystal silicon 7 to heat insulation by using overlapping parts of the shielding cylinder with each other and to reduce the temp. gradient of the single crystal silicon 7 at the time of passing it through the temp. region of 1,200 to 1,000 deg.C.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a semiconductor single crystal manufacturing apparatus and a semiconductor single crystal manufacturing method by the Czochralski method.

[0002]

2. Description of the Related Art High-purity single crystal silicon is mainly used for a substrate of a semiconductor element, and a Czochralski method (hereinafter referred to as a CZ method) is generally used as a manufacturing method thereof. FIG. 8 is a partial vertical cross-sectional view showing an example of the semiconductor single crystal manufacturing apparatus by the CZ method, which is provided with a shield cylinder that surrounds the semiconductor single crystal to be grown. Inside the main chamber 1, a graphite crucible 18 is placed on the upper end of a crucible shaft 17 that can be rotated and moved up and down, and a cylindrical heater 16 and a heat insulating cylinder 19 are installed around the graphite crucible 18.

A quartz crucible 1 housed in a graphite crucible 18.
4 was loaded with massive polycrystalline silicon, which was heated by a heater 16
Is heated and melted to form a melt 20. Seed chuck 21
The seed crystal attached to is immersed in the melt 20, and the seed chuck 21 is pulled up while the seed chuck 21 and the graphite crucible 18 are rotated in the same direction or opposite directions to grow the single crystal silicon 7.

In the upper chamber 2 connected to the main chamber 1, a graphite shielding cylinder 22 extending to the vicinity of the melt 20 is installed so that it can be raised and lowered by an elevating mechanism (not shown). The shield cylinder 22 controls the flow of the inert gas introduced from above the upper chamber 2 and shields the radiant heat from the heater 16, the melt 20, etc., and covers the entire temperature range of the single crystal silicon 7 being pulled. Cooling or keeping warm. This facilitates crystallization,
The productivity of the single crystal silicon 7 is improved.

[0005]

Radiant heat radiated from the hot zone parts including the heater 16 to the single crystal silicon 7 being pulled is blocked by the shield cylinder 22. Therefore, the temperature gradient in the radial direction and the axial direction of the single crystal silicon 7 in the vicinity of the solid-liquid interface becomes large, and crystallization becomes easy, so that the pulling rate of the single crystal silicon 7 can be increased and the productivity can be improved. However, it is impossible to arbitrarily change the thickness of the shield cylinder 22 according to the temperature environment in the furnace, and it is not possible to adjust the degree of cooling or heat retention at a desired portion of the single crystal silicon 7 being pulled. Therefore, the following problems occur. (1) When the single crystal silicon 7 passes through the temperature range of 1200 ° C. to 1000 ° C., this temperature range is not gradually cooled, so that the as-grown defect density cannot be sufficiently reduced,
This causes deterioration of the oxide film withstand voltage characteristic. (2) When melting the polycrystalline silicon loaded in the quartz crucible 14, in order to avoid interference between the lower end of the shielding cylinder 22 and the polycrystalline silicon, the elevating mechanism is driven to move the upper portion of the shielding cylinder 22 into the upper chamber 2. It has a structure to be stored in. For this reason, it is necessary to provide a storage space in the upper chamber 2, and the overall height of the upper chamber 2 becomes long.

The present invention has been made by paying attention to the above-mentioned conventional problems. The temperature gradient of a semiconductor single crystal grown by the CZ method is easily controlled, and in particular, the generation of as-grown defects is suppressed. An object of the present invention is to provide a semiconductor single crystal manufacturing apparatus and a semiconductor single crystal manufacturing method capable of obtaining a semiconductor single crystal having excellent oxide film breakdown voltage characteristics.

[0007]

In order to achieve the above object, a semiconductor single crystal manufacturing apparatus according to the present invention is a semiconductor single crystal manufacturing apparatus by the CZ method, which comprises a shield cylinder surrounding a semiconductor single crystal being pulled, It is characterized in that the shielding cylinder can be raised and lowered and can be vertically expanded and contracted.

In the semiconductor single crystal manufacturing apparatus, specifically, the shield cylinder is divided into a plurality of telescopic types, and the wire wound around the winding reel is connected to the inner shield cylinder and the outer shield is shielded. The cylinder is hooked on the elevating rod, the shield cylinder is expanded and contracted by the rotation of the winding reel, and the shield cylinder is moved up and down by the vertical movement of the elevating rod.

Further, in the method for manufacturing a semiconductor single crystal according to the present invention, the semiconductor single crystal manufacturing apparatus described above is used to drive the winding reel to shrink an arbitrary portion of the shielding cylinder and to cause a portion of the shielding cylinder to overlap. It is characterized in that a specific portion of the semiconductor single crystal is kept warm to reduce the temperature gradient when the single crystal passes through the temperature range of 1200 ° C to 1000 ° C.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a semiconductor single crystal production apparatus and a semiconductor single crystal production method for easily controlling the thermal history of a semiconductor single crystal pulled by the CZ method with a shield cylinder. In this manufacturing apparatus, the shielding cylinder that surrounds the semiconductor single crystal being pulled is movable up and down and expands and contracts, so that the thermal history can be controlled by surrounding any part of the semiconductor single crystal with any thickness. You can

Specifically, since the shield cylinder is of a telescopic type and the wire wound around the winding reel is connected to the inner shield cylinder, when the wire is rewound, the shield cylinder extends and the wire is wound up. For example, the shield tube is shortened. As a result, the thickness of the shield cylinder in the radial direction changes. Also,
When the shield cylinder is contracted, the movable range of the shield cylinder in the vertical direction becomes large.

When a semiconductor single crystal is grown using the above-described semiconductor single crystal manufacturing apparatus, by extending the shield cylinder, the semiconductor single crystal being pulled can be shielded or insulated from heat in a wide range in the axial direction. If the cylinder is shortened to have an arbitrary length and moved to an arbitrary height, a desired portion of the semiconductor single crystal being pulled can be locally kept warm. Further, it is also possible to change the heat retaining part according to the thermal environment in the furnace. Particularly, in the straight body process, when the winding reel is driven so that an arbitrary portion of the shield cylinder is shortened, the shield cylinders are partially overlapped with each other, and the heat retaining effect on the semiconductor single crystal is increased. Therefore, the single crystal is 1
By arranging the overlapping portion of the shielding cylinder at a portion where the temperature is 200 ° C. to 1000 ° C., the temperature gradient when passing through this temperature region can be reduced, and as-grow
The occurrence of n defects is suppressed.

Next, an embodiment of the semiconductor single crystal manufacturing apparatus according to the present invention will be described with reference to the drawings. The same components as those described in the above-mentioned conventional technique are designated by the same reference numerals, and the description thereof will be omitted.

FIG. 1 is a partial vertical sectional view showing a schematic structure of a semiconductor single crystal manufacturing apparatus. The upper chamber 2 attached to the upper end of the main chamber 1 is provided with two lifting rods 3 that move up and down by a lifting mechanism (not shown), and the first shield cylinder 4 is hooked at the lower end of the lifting rod 3. . As shown in FIG. 2, the first shielding cylinder 4 has two protrusions 4a on the outer circumference of the upper end of the cylinder and a flange 4b on the inner circumference of the lower end. The first shield cylinder 4 is hooked on the elevating rod 3 by the protrusion 4a. A second shielding cylinder 5 having flanges at the upper and lower ends is slidably fitted inside the first shielding cylinder 4, and a third shielding tube 5 having flanges at the upper and lower ends is inside the second shielding cylinder 5.
The shield cylinder 6 is slidably inserted. The lifting rod 3, the first shield cylinder 4, the second shield cylinder 5, and the third shield cylinder 6 are graphite or graphite coated with silicon carbide, or Mo.
Etc., and may be used in combination.

The third shielding cylinder 6 encloses the single crystal silicon 7 with a predetermined gap kept from the single crystal silicon 7. A wire 8 is connected to the upper end of the third shielding cylinder 6, and the wire 8 is wound around a winding reel 10 via a pulley 9. A pulley 11 is attached to the upper surface of the upper chamber 2 coaxially with the winding reel 10.

FIG. 3 is a sectional view taken along the line AA of FIG. FIG.
For convenience of explanation, the lifting rod 3, the wire 8, the pulley 9, and the winding reel 10 are shown on the same plane. However, as shown in FIG. 3, the lifting shaft rod 3 is actually perpendicular to the wire 8. Since it is installed in the direction of, it does not interfere. On the upper surface of the upper chamber, the take-up reel 1
A pulley 11 mounted coaxially with 0 and a drive pulley 12 directly connected to a motor (not shown) are installed, and the drive pulley 12 rotates the pulley 11 via a belt 13 to wind the pulley 11. Reel 10 rotates.
Although one wire 8 is connected to the third shielding cylinder 6 in FIGS. 1 and 3, the present invention is not limited to this, and two to three wires are connected to the third shielding cylinder 6. Alternatively, each of these wires may be individually wound by a winding reel. Further, the motor may be directly connected to the winding reel.

When the winding reel 10 is rotated to wind the wire 8, the third shield cylinder 6 is first pulled up, and subsequently the second shield cylinder 5 and the first shield cylinder 4 are sequentially pulled up, so that they are mutually separated. It will be in an overlapping state. Also, the wire 8
When the winding reel 10 is rotated in the direction for rewinding, the third shielding cylinder 6 and the second shielding cylinder 5 descend, and the upper end of the second shielding cylinder 5 is hooked on the lower end of the first shielding cylinder 4. After that, only the third shielding cylinder 6 continues to descend. The third shield cylinder 6 stops descending when its upper end is hooked on the lower end of the second shield cylinder 5. At this time, the shielding cylinder is in the maximum expanded state.

Next, a method of manufacturing a semiconductor single crystal according to the present invention will be described in the order of manufacturing steps. (1) Raw Material Melting Step As shown in FIG. 4, the quartz crucible 14 is loaded with massive polycrystalline silicon 15 and heated by a heater 16 to be melted. At this time, the winding reel 10 is driven to wind up the wire 8 so that the first shielding cylinder 4, the second shielding cylinder 5, and the third shielding cylinder 6 overlap each other, and then the elevating rod 3 is appropriately lowered. Let As a result, each shielding cylinder is made of polycrystalline silicon 15
Since the upper surface of the quartz crucible 14 can be covered and the quartz crucible 14 can be fixed at a position with high thermal efficiency while avoiding the interference between each shielding cylinder and the polycrystalline silicon 15,
Is rapidly melted.

(2) Shoulder process As shown in FIG. 5, the first shielding cylinder 4, the second shielding cylinder 5, and the third shielding cylinder
The elevating rod 3 is lifted to the upper limit while the shielding cylinders 6 overlap each other. The winding reel 10 is driven as the lifting rod 3 rises, and the wire 8 is wound. As a result, the heat of the heater 16 is radiated to the shoulder 7a of single crystal silicon without being blocked by the shield cylinder.

(3) Straight-body process At the beginning of the straight-body process, the radiation heat of the heater 16 to the single crystal silicon 7 being grown should not be interrupted while preventing the heat from being dissipated upward in the furnace as in the case of melting the raw materials. Therefore, as shown in FIG. 6, the first shielding cylinder 4, the second shielding cylinder 5, and the third shielding cylinder 6 are made to overlap each other. At this time, the lifting rod 3
It is desirable to lower the wire and rewind the wire 8 to install each shielding cylinder at a position slightly higher than the shoulder 7a of the single crystal silicon 7.

As the single crystal silicon 7 grows, the elevating rod 3 is gradually raised. As the lifting rod 3 rises, the first shielding cylinder 4 rises, and then the second shielding cylinder 5 rises. At this time, the position of the third shielding cylinder 6 is not changed. As a result, the entire shield cylinder expands as shown in FIG.
The shielding cylinder 5 and the third shielding cylinder 6 partially overlap each other. This overlapping portion is a predetermined position of the single crystal silicon 7, that is, the temperature region of the single crystal silicon 7 is 1200 ° C. to 100 ° C.
This is the part where the temperature becomes 0 ° C. The above-mentioned part is connected to the second shielding cylinder 5 and the third
By surrounding it with the shield cylinder 6, this part is gradually cooled, and the temperature gradient becomes smaller than that of other parts.

(4) Tail Process and Cooling Process In forming the tail 7c, the temperature of the straight body 7b is set to 100.
After the temperature has dropped to 0 ° C. or lower, the lifting rod 3 is raised while gradually winding the wire 8 as shown in FIG. 7. Straight body 7b
Is surrounded by each shielding tube to block radiant heat and to be cooled quickly. As the single crystal silicon 7 rises, each shielding cylinder is also raised to the upper limit position of the elevating rod 3.

(5) At the time of disassembling the in-furnace product When the pulling of the single crystal silicon is completed and the in-furnace product is disassembled, the winding reel 10 is driven as in the shoulder process shown in FIG. The wire 8 is wound up by the wire and the lifting rod 3 is raised to the upper limit position. As a result, the dismantling work can be performed quickly without being obstructed by the shield cylinder.

[0024]

As described above, according to the present invention, since the shield cylinder surrounding the semiconductor single crystal being pulled is of the telescopic type and can be expanded and contracted and moved up and down, the following effects can be obtained. (1) The heat insulating effect is increased by partially shortening and overlapping the shielding cylinder, and the temperature gradient of the semiconductor single crystal when passing through this portion becomes small. By gradually cooling the temperature range of 1200 ° C. to 1000 ° C. in the single crystal by this method, it is easy to reduce the as-grown defect density, and it is possible to manufacture a high-quality semiconductor single crystal having excellent oxide film breakdown voltage characteristics. it can. Also, by raising and lowering the shielding tube,
It is possible to adjust the slow cooling part according to the thermal environment in the furnace. (2) If the shielding tube is contracted, the movable range in the vertical direction becomes large. When the raw material polycrystal is loaded, when the shoulder tube process and the in-furnace product disassembly are performed, the shield tube does not hinder the work if the shield tube is contracted and raised. Further, if the shortened shield cylinder is lowered to the vicinity of the upper end of the raw material polycrystal, it becomes possible to shorten the raw material melting time, reduce the heater input power, and extend the useful life of the in-furnace product.

[Brief description of drawings]

FIG. 1 is a partial vertical cross-sectional view showing a schematic configuration of a semiconductor single crystal manufacturing apparatus, showing a shape of a shielding cylinder in a straight body process.

FIG. 2 is a perspective view of a first shielding cylinder.

FIG. 3 is a sectional view taken along line AA of FIG. 1;

FIG. 4 is a partial vertical cross-sectional view showing the position and shape of the shielding cylinder in the raw material melting step.

FIG. 5 is a partial vertical cross-sectional view showing the position and shape of the shielding cylinder during the shoulder process and disassembling the product in the furnace.

FIG. 6 is a partial vertical cross-sectional view showing the position and shape of the shielding cylinder at the beginning of the straight body process.

FIG. 7 is a partial vertical cross-sectional view showing the position and shape of the shielding cylinder in the tail process and the cooling process.

FIG. 8 is a partial vertical cross-sectional view showing an example of a conventional semiconductor single crystal manufacturing apparatus.

[Explanation of symbols]

 1 Main Chamber 2 Upper Chamber 3 Lifting Rod 4 First Shielding Cylinder 5 Second Shielding Cylinder 6 Third Shielding Cylinder 7 Single Crystal Silicon 8 Wire 9, 11 Pulley 10 Reel for Winding

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Makoto Kamokawa 2612 Shinomiya, Hiratsuka-shi, Kanagawa Komatsu Electronic Metals Ltd.

Claims (3)

[Claims] 1. A semiconductor single crystal manufacturing apparatus according to the Czochralski method, comprising a shield cylinder surrounding a semiconductor single crystal being pulled, wherein the shield cylinder is vertically movable and vertically expandable and contractible. Single crystal manufacturing equipment. 2. The semiconductor single crystal manufacturing apparatus according to claim 1, wherein the shield cylinder is divided into a plurality of pieces to form a telescopic type, and the wire wound around the winding reel is connected to the inner shield cylinder and is connected to the outer shield tube. An apparatus for manufacturing a semiconductor single crystal, wherein a shield cylinder is hooked on an elevating rod, the shield cylinder is expanded and contracted by rotation of the winding reel, and the shield cylinder is elevated and lowered by vertical movement of the elevating rod. 3. The semiconductor single crystal manufacturing apparatus according to claim 2, wherein the winding reel is driven to shrink an arbitrary portion of the shield cylinder, and the specific portion of the semiconductor single crystal is kept warm at the overlapping portion of the shield cylinder. And the single crystal is 1200 ° C. to 1000 ° C.
A method for manufacturing a semiconductor single crystal, which comprises reducing a temperature gradient when passing through the temperature region of 1.