JP2783626B2 - Single crystal manufacturing equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a single crystal typified by silicon, germanium, etc., and more particularly to a method for producing a single crystal by a continuous pulling method to which a pulling method (Czochralski method) is applied. The present invention relates to an apparatus for producing a crystal.

(Prior Art) At present, silicon, germanium, and the like are known as semiconductors widely used industrially as devices such as integrated circuits (ICs) and large-scale integrated circuits (LSIs).

Single crystals such as silicon and germanium used in the semiconductor industry use a polycrystal as a raw material, create a molten zone by induction heating on a polycrystal rod, move it from the seed crystal side, and float it to grow a single crystal. Floating Zone
(Hereinafter abbreviated as FZ method) or a pulling method (Czochralski) in which a polycrystal is placed in a crucible and heated and melted, and a seed crystal is immersed in a melt and pulled up to grow a single crystal of a round bar.
Method, hereinafter abbreviated as CZ method).

These production methods are selected according to the use of the single crystal, the single crystal manufactured by the FZ method is used for high resistivity applications, and the single crystal manufactured by the CZ method is used for low to medium resistivity applications.
In recent years, one electronic circuit has become smaller and smaller due to advances in LSI manufacturing technology. On the other hand, the area of a single crystal wafer to be processed has been increased to increase the number of circuits formed in the wafer in one process. By doing so, the cost per circuit is reduced. For this reason, single crystal manufacturing technology is constantly required to have a large diameter, and at the same time,
A method of increasing the length of one single crystal has been pursued in order to increase the productivity per unit time during the production of a single crystal. The above-mentioned CZ method not only has the advantage that a large-diameter single crystal ingot can be easily obtained, but also has a technical improvement such as automatic diameter control and semi-continuation by recharging of the raw material polycrystal, and the FZ method has a low cost. The fact is that it surpasses the law.

Conventional single-crystal production by the CZ method, in the case of silicon, for example, places polycrystalline silicon as a raw material or polycrystalline silicon and a dopant (additive) in a quartz crucible supported by a support stand in a chamber. After that, under an argon atmosphere, the raw material was melted by a heater arranged around the quartz crucible, and a thin seed crystal made of silicon single crystal was attached to a chuck of a pulling device provided above the crucible, and Is immersed in the raw material melt in the crucible, and then pulled up at a predetermined speed while rotating the pulling shaft relatively to the crucible. Then, a single crystal grows sequentially at the lower end of the seed crystal attached to the pulling shaft. When a dopant is added, a single crystal ingot having a desired resistance value can be obtained depending on its concentration.

A method of continuously pulling a single crystal by such a CZ method is already known. However, according to the continuous pulling method, the dopant concentration in the pulling direction can be made uniform and the surface of the molten liquid can be improved. Can be kept constant, and the yield of the manufactured single crystal can be improved.

JP-B-59-33,551 (JP-A-57-179,096) discloses a method for producing a single crystal by a continuous pulling method. In this manufacturing method, first, as shown in FIG. 10, the tip of a seed crystal 2 attached to a pulling shaft 1 is immersed in a raw material melt 3, and while controlling the temperature and / or pulling speed of the melt 3, Raise the pulling shaft 1. At this time, the diameter gradually increases continuously from the lower end of the seed crystal 2. A so-called cone portion 30 is formed, and a straight body portion 31 of the single crystal C1 is grown continuously from the cone portion 30. When the pulling of the required length is completed, the temperature and / or pulling speed of the melt 3 is controlled again to reduce the shape of the lower end of the single crystal C1 to form a tail portion 32, and the tail portion 32 is formed. The dash portion 33 having a further reduced diameter is formed continuously. This dash part
33 is used as it is as a seed crystal for the second single crystal C2 (see FIG. 11).

By successively repeating this operation, a single crystal having a small-diameter portion formed at the lower end is continuously produced. In the state shown in FIG. A side surface of the single crystal C2 is supported by a supporting device 4 which rotates in accordance with the pulling shaft 1 and moves at the same speed as the pulling shaft 1. Next, as shown in the figure, single crystal C1 and single crystal C2
Is cut by the laser cutting device 6 to recover the single crystal C1. In addition, the second and subsequent single crystals
In order to collect C2, C3, C4..., It is configured in the same manner as the support device 4 and rotates in synchronization with the pulling shaft 1 and the center axis coincides with the pulling shaft 1, and moves at the same speed as the pulling shaft 1. Is provided, and the n-th single crystal Cn and the (n + 1) -th single crystal Cn cooperate with the support device 4 described above.
By supporting +1, it is possible to recover a single crystal while performing continuous pulling (see FIGS. 13 and 14).

However, according to such a conventional method for manufacturing a single crystal, a dash portion and a cone portion are formed at the rear end of the seed crystal, and then the straight body is grown. When the straight body grows to a desired length, a tail is formed.Therefore, in manufacturing a straight body that can be commercialized as a single crystal, a dash, a cone, and a tail are formed before and after the straight body. In this case, the yield is low and the cycle time is long.

The present invention has been made in view of such problems of the related art, and has provided a single crystal manufacturing apparatus capable of cutting and removing a straight body portion of a single crystal while pulling the same. The purpose of the present invention is to improve the material yield and to increase the productivity.

(Means for Solving the Problems) The present invention for achieving the above object melts raw materials,
In a single crystal manufacturing apparatus for growing a single crystal at the rear end of the seed crystal by immersing the seed crystal in the melt and pulling up the seed crystal, a straight body of the single crystal is gripped and First clamping means for pulling up the single crystal at a speed; cutting means positioned above the first clamping means for cutting the straight body of the single crystal while moving in synchronization with the pulling speed; An apparatus for producing a single crystal, comprising: a second clamping means positioned above the means for gripping a single crystal above a cutting position.

In addition, between the first clan means and the cutting means, at least during cutting of the single crystal, it moves in close proximity to the single crystal to be pulled in synchronization with the pulling speed, and cuts off the cutting position and the surface of the melt. Preferably, shielding means is provided.

(Function) In the present invention thus configured, a straight body having a desired length is formed at the rear end of the seed crystal, pulled up, and the vicinity of the straight body to be cut is used as the first clamping means. To raise the first clamping means in synchronization with the lifting speed,
If the straight body is cut by the cutting means in this state, a single crystal of a desired length can be obtained without forming a small diameter portion in the single crystal. Since all of the cut straight body portions can be provided as products, the product yield can be improved and the cycle time can be reduced. When the first clamping means rises to a predetermined position, the second clamping means grips the upper end of the single crystal straight body part, while releasing the holding of the straight body part by the first clamping means, and the second clamping means moves at a predetermined rising speed. The single crystal is pulled up with. Hereinafter, by repeating this operation, only the straight body can be continuously cut and taken out.

Further, according to the apparatus for producing a single crystal provided with the shield means between the cutting means and the first clamp means, it is possible to prevent chips of the single crystal by the cutting means from dropping into the molten liquid, Dislocation of the pulled single crystal can be prevented and the quality can be stabilized.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

1 is an overall sectional view showing an embodiment of the present invention, FIG. 2 is a sectional view showing a clamping means of the embodiment, FIG. 3 is a sectional view showing a cutting means of the embodiment, and FIG. IV-IV in Fig. 3
Sectional views along the line, FIGS. 5 to 9 are process diagrams for explaining the operation of the embodiment.

As shown in FIG. 1, the single crystal manufacturing apparatus of this embodiment
Chamber consisting of heating chamber 11 and pulling chamber 12
Has 10 A graphite crucible 13 and a quartz crucible 14 supported by a graphite pan are provided in the heating chamber 11, and the graphite crucible 13 and the quartz crucible 14 are rotated by a driving device 16 via a rotating shaft 15. It has become. A heater 17 is provided around the graphite crucible 13 and the quartz crucible 14 formed in a substantially cylindrical shape so as to melt the raw material contained in the quartz crucible 14. The heater 17 can be used either by a resistance heating method or by an induction heating method. It is preferable to use a heater.

In the quartz crucible 14, an annularly formed partition wall 18 is provided, whereby the quartz crucible 14 is partitioned into a melting zone 19 and a solidification zone 20, but is opened at the lower edge of the partition wall 18. Both zones 19, 20 via a communication port (not shown)
Are communicating. Raw material is supplied to the melting zone 19 from a raw material supply device (not shown) via a nozzle 22. In addition,
The annular partition 18 can be omitted.

“23” is a heat insulating plate for preventing heat dissipation from the heater 17.

A pulling device 24 is provided above the pulling chamber 12, and is configured to rotate the pulling wire 1, which is a pulling shaft, and to move up and down. A chuck 25 is attached to the tip of the pulling wire 1, and this chuck 25
After the seed crystal 2 is gripped, the pulling device 24 is driven to lower the pulling wire 1 until the tip of the seed crystal 2 is immersed by a predetermined amount in the melt 3 in the crucible 14 made of quartz. If you raise while controlling the pulling speed,
The single crystal C grows at the lower end of the seed crystal 2.

In this embodiment, the first clamping means 4 is provided in the heating chamber 11 at a position where the grown single crystal C is cooled to a predetermined temperature. Also, the lifting chamber 12
The cutting means 6 and the second clamping means 5 are provided above the cutting means 6. These first and second clamping means
The mounting positions of 4, 5 and the cutting means 6 are not limited to the positions shown in FIG. 1, and the single crystal C is cooled to such an extent that the pulled single crystal C can be gripped by the clamping means 4. It may be set at a certain position, and can be appropriately changed according to the shape, structure, and the like of the chamber 10.

As shown in FIG. 2, the first and second clamping means 4 and 5 each include a gripper 41 for gripping the side surface of the single crystal C, and a rotation drive unit for rotating the single crystal by rotating the gripper. 42
And a lifting drive unit 43 that raises and lowers the entire clamp means in synchronization with the lifting device 24.

The grip portion 41 has a rotating frame 44, and the rotating frame 44 is rotatably attached to an elevating frame 45 described later via a bearing 46. The rotating frame 44 is provided with a plurality of gripping pads 47 that move radially and that do not rotate with respect to the rotating frame. This grip pad 47
Is formed in a shape corresponding to the side surface of the single crystal C whose tip is pulled up. In the present embodiment, four grip portions 41 are provided with a phase of 90 °. A gear 48 having a male screw formed on the support shaft of the gripping pad 47 and a female screw screwed to the male screw is provided rotatably without moving forward and backward with respect to the rotating frame 44. The gear 48 is connected to a drive shaft 51 of a motor 50 via another gear 49. Therefore, when the motor 50 is operated, the gear
48 and 49 rotate, whereby the grip pad 47 moves forward and backward.

Teeth 52 are formed on the outer periphery of the side surface of the rotating frame 44, and a gear 53 that meshes with the teeth 52 is attached to the lifting frame 45 via bearings 54, 54. A drive shaft 56 of a motor 55 is fitted into the gear 53, and the motor 55
Is operated, the rotating frame 44 rotates via the gear 53.

Since the rotating frame 44 rotates relative to the lifting frame 45, power is supplied to the motor 50 attached to the rotating frame 44 by the trolley 57.

The motor 58 constituting the lifting drive unit 43 is
And a gear 61 fitted to the drive shaft 59, and a gear 61 meshing with the gear 60 are rotatably supported by the lifting frame 45 via bearings 62 and 63, and the gear 61 has an internal thread. The female screw is formed so as to screw with a male screw formed in the axial direction of the fixed shaft 64. Fixed shaft 64
Are set up substantially vertically on both sides thereof along the single crystal C to be pulled in the chamber 10.

The rotation speed of the motor 58 is configured to be controlled in synchronization with the pulling speed of the pulling device 24 described above.

Further, a cutting means 6 is provided between the clamping means 4 and 5. In this embodiment, as shown in FIG. 4, the frame 65 is provided so as to be able to move up and down along the fixed shafts 66, 66 by the same mechanism as the lifting drive unit 43 of the clamp means 4, 5 described above. “67” is this elevating motor. As shown in FIG. 3, a support frame 69 for rotatably supporting the blade 68 is attached to the frame 65 via a ball screw 70 so as to be able to advance and retreat with respect to the single crystal C. Further, the screw shaft 71 that engages with the ball screw 70 is configured to be rotated by the motor 72.
On the other hand, the blade 68 includes pulleys 73 and 74 and a belt 75
, And further by a motor 79 via bevel gears 76, 77. “79” is a counter weight. The rotational speed of the motor 67 is configured to be controlled in synchronization with the pulling speed of the pulling device 24 described above. That is, the blade 68 cuts the single crystal in a state where it is relatively stopped with respect to the single crystal C.

Further, in the present embodiment, above and below the cutting means 6,
Other clamping means 80 and 81 having the same mechanism as the clamping means 4 and 5 described above are provided (see FIG. 1). This is because by firmly holding both ends of the cut portion of the single crystal C to be cut, vibration at the time of cutting is further reduced and absorbed, and propagation to the surface of the melt 3 is prevented. Therefore, in some cases, these clamp means 80 and 81 can be omitted.

Further, in the manufacturing apparatus according to the present embodiment, the shielding means 83 is provided in a bottleneck part that separates the heating chamber 11 and the pulling chamber 12. The shield means 83 is configured to rise and fall in synchronization with the pulling speed of the single crystal, that is, the pulling speed of the pulling device 24 or the pulling speed of the first clamp means 4. It is divided in the circumferential direction so as to move forward and backward. The specific structure of such a shield means 83 can be configured, for example, in the same manner as the grip pad 47 described above and the grip portion 41 that moves the grip pad 47 forward and backward. Further, it is preferable to provide a suction means for sucking and removing the collected chips. By providing such a shield means 83 below the cutting means 6, it is possible to prevent chips generated during cutting of the single crystal C from dropping into the molten liquid 3, thereby preventing the single crystal C from being lifted. Prevention of dislocations in the crystal and stabilization of quality can be achieved.

Further, in the single crystal manufacturing apparatus according to the present embodiment, a take-out chamber 84 is formed on one side of the chamber 10, and an opening / closing valve 85 is provided between the single chamber and the pulling chamber 12. The pulling chamber 12 includes this pulling chamber.
A transfer device 87 for holding the single crystal cut at 12 and mounting it on the elevating table 86 is provided. The elevating table 86 on which the single crystal C is mounted by the transfer device 87 is lowered with the open / close valve 85 opened, and the other transfer device 89 is
And used for the next step. “88” is a drive source for moving the lifting table 86 up and down. In addition, transfer equipment
As 87 and 89, it is preferable to use an industrial robot or the like.

Next, a case where a single crystal is manufactured using the above-described single crystal manufacturing apparatus will be described. The manufacturing apparatus of the present invention can be applied to metal crystals and metal oxide crystals in addition to silicon crystals, germanium crystals, and gallium-arsenic crystals.

First, a predetermined amount of raw material (polycrystalline silicon and, if necessary, dopants such as phosphorus and boron to be added thereto when manufacturing a silicon single crystal) are supplied from a raw material supply device to a quartz crucible.
It is supplied to the melting zone 19 in 14 and the heater 17 is operated to be melted. The raw material dissolved in the melting zone 19 flows through the communication port of the annular partition wall 18 to the solidification zone 20. If the crucible 14 is filled with the molten liquid 3 before starting the pulling, the raw material can be supplied to both the solidification zone 20 and the melting zone 19. When pulling up, an argon gas is blown into the heating zone 11 to make the heating zone 11 a reduced pressure argon atmosphere or a normal pressure argon atmosphere. Heating zone 11 for gallium-arsenic crystals
Nitrogen gas is blown into the inside to make the heating zone 11 a pressurized nitrogen atmosphere.

Next, the seed crystal 2 having a predetermined plane orientation is attached to the chuck 25 of the pulling shaft 1, and the pulling device 24 is operated to lower the pulling shaft 1 until the lower end of the seed crystal 2 is immersed in the melt 3.

At the beginning of the pulling, as shown in FIG. 5, the pulling speed is set to be high and / or the melt temperature is raised to narrow the diameter of the single crystal, and dislocations are expelled to the surface of the single crystal. Dislocation. Subsequently, the single crystal C having a desired diameter is grown by lowering the pulling speed and / or the melt temperature. In this case, it is preferable to rotate the quartz crucible 14 by the driving device 16 and also rotate the pulling shaft 1 to stir the molten liquid 3 and make the temperature uniform.

As shown in FIG. 6, when the single crystal C has grown to a desired length, the first clamping means 4 holds the straight body 31 of the single crystal and the second clamping means 5 Hold the upper end of the. Further, the upper and lower ends of the portion to be cut are gripped by the clamps 80 and 81, and the seal pad of the shield 83 is brought into contact with or close to the single crystal. At this time,
Each of the first and second clamping means 4 and 5, the clamping means 80 and 81, the cutting means 6, and the shielding means 83 is a lifting device.
It is rising at a speed synchronized with 24. Next, from this state, the single crystal is cut by rotating the blade 68 of the cutting means 6. At this time, chips of the single crystal tend to fall into the crucible 14, but the shielding means is provided below the cutting means 6.
Since the shield pad 83 is placed with the shield pad in contact with or close to the single crystal, chips are collected by the shield means 83.

Although not shown in FIGS. 5 to 9, during the pulling operation of the present embodiment, the nozzle
The raw material is supplied to the melting zone 19 of the quartz crucible 14 via 22 so that the liquid level of the molten liquid 3 is always kept constant.

Next, as shown in FIG.
68 is separated from the single crystal C, and the clamping means 80, 81
And the shield means 83 is released. At this time, the first clamp means 4 is rising at the same speed as the pulling device 24, while the second clamp means 5 is rising at a slightly faster speed than the first clamp means and rises to a predetermined position. Then, it is transferred to the lifting table 86 by the transfer device 87 and taken out from the door 90.

On the other hand, the single crystal gripped by the first clamp means 4 continues to be pulled up, but as shown in FIG. 8, when it rises to a predetermined position, the second clamp means 5 descends to raise the upper end of the single crystal. The single crystal is gripped, and the first clamping means 4 releases the single crystal instead. At this time, the second clamping means 5
Rises at the same speed as the rising speed of the first clamping means 4, and the pulling of the single crystal C is continued. When the upper end of the single crystal rises to the upper end of the pulling chamber 12 as shown in FIG. 9, the operation shown in FIG. 6 is repeated.

According to the manufacturing apparatus of the present embodiment configured as described above, a single crystal having a desired length can be automatically and continuously obtained without forming a small-diameter portion in the single crystal. Since all straight body parts can be provided as products,
The product yield is improved, and the cycle time can be reduced. Further, the shield means can prevent chips of the single crystal by the cutting means from falling into the melt, thereby preventing dislocation of the pulled single crystal and stabilizing the quality. .

The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention.

(Effects of the Invention) As described above, according to the present invention, it is possible to continuously pull up only the straight body portion without forming a small-diameter portion in a single crystal, thereby improving the material yield. And at the same time increase productivity.

[Brief description of the drawings]

1 is an overall sectional view showing an embodiment of the present invention, FIG. 2 is a sectional view showing a clamping means of the embodiment, FIG. 3 is a sectional view showing a cutting means of the embodiment, and FIG. FIG. 3 is a sectional view taken along the line IV-IV of FIG. 3, FIGS. 5 to 9 are process diagrams for explaining the operation of the embodiment, and FIGS. 10 to 14 are sectional views showing a conventional manufacturing apparatus. DESCRIPTION OF SYMBOLS 1 ... Pulling shaft, 2 ... Seed crystal, 3 ... Melt, 4 ... 1st clamp means, 5 ... 2nd clamp means, 6 ... Cutting means, 31 ... Straight body part, 83 ... Shielding means, C: single crystal,

Claims (2)

(57) [Claims] An apparatus for producing a single crystal, comprising: melting a raw material; immersing the seed crystal in the melt; and raising the seed crystal to grow a single crystal at the rear end of the seed crystal. A first clamping means for gripping the straight body of the single crystal and pulling up the single crystal at a predetermined speed; and a straight body of the single crystal positioned above the first clamping means and moved in synchronization with the pulling speed. An apparatus for producing a single crystal, comprising: cutting means for cutting a portion; and second clamping means for holding a single crystal located above the cutting means and above the cutting position. 2. The method according to claim 1, further comprising: moving between the first clamping means and the cutting means in synchronization with the pulling speed at least during the cutting of the single crystal, in close proximity to the single crystal to be pulled. 2. The apparatus for producing a single crystal according to claim 1, further comprising a shield means for shielding the crystal.