JPH10273385A - Apparatus for pulling single crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for pulling a single crystal so as to afford an always stable holding state even when the objective cross-sectional shape of the dislocation-free crystal at the holding position is any one. SOLUTION: This apparatus for pulling a single crystal comprises tip members 3 of holding means, occupying regions thereof brought into contact with the surface of the crystal when holding the crystal and provided with each bag 4 made of a metal manifesting the flexibility at the ambient temperature when holding the crystal and plural granular materials 7, enclosed in the bag 4 made of the metal and having the higher melting point than that of the single crystal in the apparatus for pulling the single crystal according to the Czochraslki process in order to hold the dislocation-free crystal part after achieving the dislocation-free state by the Dash neck method with the holding means 1 and grow the single crystal while pulling the single crystal with a driving means.

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 for a large diameter semiconductor single crystal pulling furnace, and more particularly to a single crystal pulling apparatus for a large diameter semiconductor single crystal pulling furnace.

[0002]

2. Description of the Related Art As one method of manufacturing a silicon crystal used as a semiconductor crystal, for example, there is a so-called CZ (Czochralski) method of manufacturing by pulling a single crystal. This is to heat and melt the bulk polycrystalline silicon in a crucible in an inert gas chamber furnace, and after contacting the seed single crystal with this molten silicon, while cooling,
The seed crystal is slowly raised while rotating, and once grown under the seed crystal, the crystal is squeezed narrowly (seeding) to cause dislocations to cross the crystal side surface to form a dislocation-free region (dash neck method). This is a method in which dislocation single crystals are pulled up and grown.

A single crystal pulling apparatus has been used for pulling a single crystal. This device mainly has a configuration in which a wire having a fixed attachment portion for a seed crystal at its lower end is wound while rotating in the axial direction thereof.

[0004]

In recent years, in order to increase the efficiency of semiconductor device manufacturing in accordance with the increase in the size of semiconductor devices due to the increase in the amount of circuit integration, single crystals have a large diameter of, for example, 16 inches or more. The diameter tends to increase. Therefore, the weight of the pulled single crystal is also increased. However, in the pulling of the seed crystal portion by the wire of the pulling device as described above, there is a limit in the load resistance, and it is impossible to pull a heavy single crystal.

Therefore, the head is formed by expanding the diameter above the single crystal below the seed crystal and then reducing the diameter, and forming a plurality of catcher arms for engaging and clamping the narrow portion of the head at equal angular intervals. A device having an elevating shaft has been considered. In this method, a plurality of catcher arms are closed and clamped to each other to grip a constricted portion at the upper portion of the single crystal.

[0006] The pinching of the constricted portion by the catcher arm is usually performed by the following operation.
That is, while maintaining the relative position of the catcher arm relative to the single crystal head constant, while maintaining the pulling of the single crystal wire at a predetermined rising speed, the catcher arm is
Close in a relative positional relationship such that the tip faces a lower position than the contact position on the constricted portion predetermined to be clamped in advance, and after the closed state, raise the catcher arm's rising speed faster than the rising speed of the single crystal. As a result, the constricted portion is caught at the predetermined contact position at the tip of the catcher arm, and an engaged / nipped state is obtained.

However, when the constricted portion of a single crystal is gripped by such a catcher arm, the cross-sectional shape of the constricted portion varies from one single crystal to another, for example, a crystal habit line protruding at substantially equal intervals appears. In many cases, the initial contact state of the distal end of each catcher arm with the constricted portion is not uniform.

For example, when catching a constricted portion, some of the plurality of catcher arms are clamped in a state where they hit the protruding portion of the crystal habit line, and the ends of the other catcher arms float from the constricted portion. Due to the unstable pinching state, the constriction was loose between the catcher arms during the catching of the constriction and during the subsequent pulling operation, and it was on the ridge of the crystal habit line. The tip position of the catcher arm may shift from the raised portion to a lower flat portion.

A shock to the entire single crystal due to rattling or slipping due to the non-axiality of the cross-sectional shape of the constricted portion such as the bulge of the habit line generated during the catching or pulling operation is a problem. It adversely affects the growth of the crystal and hinders the production of a good large-diameter single crystal.

[0010] In view of the above problems, the present invention provides a single crystal pulling apparatus capable of always obtaining a stable holding state regardless of the cross-sectional shape of a target gripping position of a dislocation-free crystal. For the purpose of providing.

[0011]

In order to achieve the above object, a single crystal pulling apparatus according to the first aspect of the present invention comprises:
A single crystal pulling apparatus by the Czochralski method of holding a dislocation-free crystal portion after achieving dislocation-free by the dash neck method and continuing the crystal growth, and holding means for holding a dislocation-free crystal, and the crystal Driving means for moving the gripping means in a state in which the crystal is gripped in the pulling direction, the gripping means having a tip member occupying an area in contact with the surface of the crystal when the crystal is gripped, The member is provided with a metal bag showing flexibility at an ambient temperature when the crystal is gripped, and a plurality of granular substances having a higher melting point than the single crystal contained in the metal bag. .

[0012] In the single crystal pulling apparatus according to the second aspect of the present invention, in the single crystal pulling apparatus according to the first aspect, when the single crystal is Si, the granular material is Si.
C, and the metal bag is made of stainless steel.

According to the present invention, there is provided a single crystal in which a dislocation-free crystal after achieving dislocation-free by the dash neck method is gripped by gripping means, and a single crystal is grown while pulling up the gripping means in this crystal gripping state by driving means. It is a lifting device. Note that dislocation-free by the dash neck method here means dash (D
ash), which is based on a dislocation-free growth method. After a seed single crystal is brought into contact with molten silicon, the crystal is squeezed from the seed crystal once to narrow (seed squeezing) and grow so that dislocations cross the side of the crystal. This forms a dislocation-free region.

Further, the gripping means of the present invention comprises: a metal bag which is flexible at a peripheral temperature when the crystal is gripped; A tip member including a plurality of granular substances having a melting point higher than that of the single crystal included therein.

In such a configuration of the present invention, at the time when the crystal is to be gripped by the gripping means, the metal bag of the distal end member has flexibility, and the plurality of granular substances contained in the bag are formed of It has fluidity independent of each other in the bag, regardless of the ambient temperature. Therefore, when the tip member of the gripping means catches and holds the single crystal, the tip member abuts on the crystal, and the load acts from the granular material on the abutting side through the metal bag to the surrounding granular material. It is sequentially transmitted and diffused to the substance.

According to the transmission / diffusion of the load action, each granular material moves in the peripheral direction. However, the gripping pressure between the crystal surface and the gripping means and the regulation from the peripheral direction of the bag cause the entire granular material to move. The movement stops when the reaction is balanced.
At this time, the contact portion of the tip member with the crystal has a contact surface deformed into a shape corresponding to the crystal surface shape.

Therefore, the contact by the tip member is a surface contact by the contact surface changed into a shape corresponding to the shape of the opposing crystal surface regardless of the shape thereof, so that the conventional catcher arm tip is used. The gripping state is much more stable than in the case of point contact, and the single crystal is pulled well.

The pulling weight increases as the pulling of the single crystal progresses. However, in order to prevent the tip member from crushing too much, the load exerts a pressure equal to or higher than a certain pressure, for example, when the single crystal is gripped. After about twice the weight of the crystal, the thickness of the metal bag and the particle size of the particulate matter are adjusted so that the tip member does not deform any more.
The design such as the filling amount of the particles is appropriately selected.

As the metal bag of the tip member, any material may be used as long as it is made of a metal exhibiting flexibility at the ambient temperature when the crystal is gripped. On the other hand, the granular material contained in the bag is a single crystal. It is sufficient that the material does not melt without being affected by a higher melting point, that is, around the peripheral temperature at the start of pinching of the constricted portion.

For example, when pulling up Si as a single crystal, if the ambient temperature at the time of gripping the crystal is around 800 ° C., the tip member may have a melting point higher than that of Si in the stainless steel bag. And a large number of SiC granular substances having a high content.

The thickness of the coating metal of the tip member in the present invention is required to be flexible when gripping the crystal, and the thickness of the coating metal is broken by a load action to expose the substance therein. It is necessary to set the thickness to be sufficient to prevent the occurrence.

Further, as the gripping means of the present invention, for example, a configuration basically including a plurality of catcher arms as in the related art can be used. What is necessary is just to provide the tip member of this invention in the lower end of each catcher arm. In this case, the device can be designed by attaching the tip member to the lower end of the existing catcher arm by using an appropriate attachment means, so that the device design is simple. The distal end member may be attached to the lower end of the catcher arm by welding and fixing the metal bag to the lower end, or may be configured to be detachable and replaceable by using any attaching means.

The gripping position of the gripping means of the present invention may be any position of the single crystal which grows after the dislocation-free state is achieved. Since it is determined according to the diameter of the crystal, a desired single crystal holding position and its diameter are set in advance. Of course, similarly to the conventional case, the head may be formed by expanding and reducing the diameter of the single crystal after achieving the dislocation-free state, and the constricted portion under the head may be sandwiched.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION As an example of an embodiment of the present invention, a stainless steel bag filled with SiC particles and sealed is used as a tip member, and a plurality of catcher arms are provided as gripping means. Fig. 1 shows a single crystal pulling device
Shown in In the present embodiment, a case will be described as an example where a single crystal head is formed after dislocation-free under a seed crystal is achieved and a constricted portion under the head is gripped.

First, a stainless steel bag 4 having a particle injection port 5 having a thickness of about 0.5 mm to 5 mm and a volume of about 1 ml to 20 ml and having a bag that can be hermetically sealed by screwing a screw cap 6 is used. And mold it.

The stainless steel bag 4 is fixed to a portion facing the constricted portion by welding the lower end portion 2 of the catcher arm 1 to be described later by welding a part of the region, and then a particle size of several μm A few mm of SiC particles 7 are filled and sealed with a screw cap 6. Assume that the attachment of the distal end member 3 to the lower end 2 of the catcher arm 1 has been completed by the above operation.

Of course, the attachment of the tip member 3 is not limited to the method of welding and fixing the stainless steel bag 4 to the lower end portion 2 of the catcher arm 1 as in this embodiment, but can be attached and detached using appropriate attachment means. It is good. Also,
The sealing of the stainless steel bag 4 after filling the particles 7 is not limited to the above-mentioned screw type, and any sealing method may be used as long as the particles 7 do not spill out of the stainless steel bag 4 during the work of pinching and pulling the end crystals.

As shown in FIG. 1, after the seed crystal 14 is brought into contact with the molten silicon in the crucible 20, the pulling device pulls up the wire 11 with a hoisting device (not shown) and sets a predetermined rotation speed. This is for a semiconductor single crystal pulling furnace by the Czochralski method in which a single crystal is grown under the seed crystal 14 by slowly raising the seed crystal 14 while rotating the wire 11 around the axis. This apparatus forms a constricted portion 16 of a head portion 15 composed of an enlarged diameter portion and a reduced diameter portion on a single crystal grown below a seed crystal 14, and then connects the constricted portion 16 to the lower end of three or more catcher arms. The portion is held in the radial direction to advance the crystal pulling.

In this lifting device, three or more catcher arms 1 are pivotally supported at their upper ends by a suspending portion (gripping means) 13 so as to be arranged at equal angular intervals from each other. As described above, the tip end members 3 each having the stainless steel bag 4 filled with the SiC particles 7 are attached to the catcher arm 1 at the lower end portion 2 as described above. Hanging part 13
The opening and closing of each of the catcher arms 1 is performed by the rotation control of the upper end portion about the pivot portion at.

The suspending portion 13 includes the wire 11 coaxially and moves in the axial direction by a driving device (driving means) (not shown) without mechanically interfering with the pulling of the seed crystal 14 of the wire 11. Is what is done. Along with the axial movement of the suspension unit 13 by the driving device, the catcher arms 1 are simultaneously moved in the crystal pulling direction.

The single crystal pulling operation in the large diameter semiconductor single crystal pulling furnace of the pulling apparatus having the above-described configuration will be described below. First, as an initial arrangement, each catcher arm 1
Is held in the open state by the driving device. In this initial arrangement, the hoisting device is controlled to bring the seed crystal 14 held by the carbon seed chuck 12 at the lower end of the wire 11 into contact with the molten silicon (melt rotation speed 0.1 to 15 rpm) in the crucible 20. Let it.

Thereafter, while the pulling wire 11 is rotated in the axial direction at a predetermined rotational speed of about 10 rpm, the hoisting device is simultaneously controlled to raise the seed crystal 14 to a predetermined ascending speed of about 3.0 m.
The wire 11 is pulled up so as to rise at m / min. By this rise, a dislocation-free single crystal having a diameter of about 5 mm grows at the lower end of the seed crystal 14.

Next, the diameter of the single crystal is increased by controlling the hoisting device to reduce the ascending speed to about 0.5 mm / min. After the diameter is increased to about 50 mm, the rate of rise is set to about 1.0 mm / min, and the diameter of the single crystal is reduced. The single crystal head 15 is formed by the above operation. After the single crystal has been reduced to a diameter of about 30 mm, the hoisting device is further controlled to reduce the ascending speed to about 0.5 mm / min to increase the single crystal diameter to the product diameter (400 mm). As the diameter increases, the constriction 1
6 are formed. In practice, such single crystal diameter control is performed by, for example, measuring the diameter of the single crystal with the lapse of time using a light reflection method or the like, and controlling the driving of each driving device based on the data. It is performed by a computer or the like using a program for adjusting the ascending and rotating speeds, that is, a so-called automatic diameter control system.

After the constricted portion 16 is formed, the hanging portion 13 is driven by controlling the driving systems so that the single crystal pulling is continued while maintaining the predetermined rising speed by the diameter control system. Move the catcher arm 1 to the closed state. At this time, the relative position of each catcher arm 1 with respect to the single crystal is such that the position of the lower end 2 of the catcher arm (and the tip member 3) facing the single crystal in the closed state is the lower end of each catcher arm of the constricted portion 16. 2 is a position below a contact position determined to be sandwiched. Accordingly, the relative distance between the distal end members 3 of the lower ends 2 of the catcher arms corresponds to the diameter of the constricted portion 16 at the predetermined contact position, and has a slight gap with respect to the surface of the opposing constricted portion 16.

Next, the moving speed of the hanging portion 13 in the upper axis direction by the driving device is increased, and the moving speed of the catcher arm 1 in the closed state with respect to the liquid level in the crucible 20 in the upper axis direction is changed to the single crystal head. The rising speed of the part 15 with respect to the liquid level in the crucible 20 is increased. By this speed control, the tip member 3 of the lower end portion 2 of each catcher arm in the closed state moves the single crystal head 1
5 and moves in the upward direction, and comes into contact with a predetermined contact position of the constricted portion 16. That is, each tip member 3
When viewed from above, the single crystal head 15 relatively moves downward so as to drop, and catches the constricted portion 16 at the predetermined contact position.

At this time, the constricted portion 16 side of the stainless steel bag 4 of the tip member 3 has flexibility, and when the constricted portion 16 is caught, it is subjected to a load action and bends. Si located on the constricted part 16 side
The light is transmitted to the C particles 7. Furthermore, SiC on the stainless steel bag 7 side
The load action transmitted to the particles 7 is sequentially transmitted and diffused to the surrounding SiC particles 7 adjacent thereto.

According to the transmission and diffusion of the load action, each S
The iC particles 7 move in the peripheral direction, but move when the whole reaction of the particles 7 is suspended against the clamping pressure between the constricted portion 16 and the lower end 2 of the arm and the regulation of the stainless bag 4 from the peripheral direction. Stops. At this time, a contact surface deformed into a shape corresponding to the constricted portion surface shape is formed at a contact portion of the distal end member 3 with the constricted portion 16.

When a stable gripping state is obtained by the surface contact of the distal end member 3 of the lower end portion 2 of the catcher arm, the driving device is suspended so that the pulling at a predetermined rotation and a rising speed is continued. The crystal pulling operation is advanced while controlling the movement in the upper axis direction of the crystal 13.

As described above, according to the single crystal pulling apparatus of the present embodiment, when the constricted portion 16 is caught, the impact applied to the tip member 3 is absorbed by the transmission and diffusion of the load action to the SiC particles 7. At the same time, the contact portion is deformed into a surface shape corresponding to the surface shape of the constricted portion 16 and a sandwiched state by surface contact is obtained, so that no matter what cross-sectional shape the constricted portion 16 has, In pulling a semiconductor single crystal having a diameter, a favorable pulling operation can be performed with a stable gripping state at all times.

The holding means of the present invention is not limited to the structure including the catcher arm as shown in the above embodiment, but is a mechanism capable of mechanically grasping and pulling a single crystal. As long as the tip member can be provided in the contact region with the crystal, it can be widely used.

Further, in the above embodiment, the single crystal head is formed immediately after dislocation-free under the seed crystal, and the constricted portion under this head is used as the gripping position. However, the present invention is not limited to this. Alternatively, the pinching may be performed when the diameter of the single crystal further increases.

[0042]

As described above, according to the present invention, even in pulling a large-diameter single crystal, a stable gripping state can always be obtained in accordance with the shape of the target gripping position of the dislocation-free crystal. There is an effect that it can be performed.

[Brief description of the drawings]

1A and 1B are explanatory views showing a holding device according to an embodiment of the present invention, wherein FIG. 1A is a schematic configuration diagram of the device, and FIG. 1B is a partially enlarged view of the vicinity of a lower end of a catcher arm in FIG. .

[Explanation of symbols]

 1: Catcher arm 2: Lower end of catcher arm 3: Tip member 4: Stainless steel bag 5: Particle inlet 6: Screw cap 7: SiC particle 11: Wire 12: Seed chuck 14: Seed crystal 15: Single crystal head 16: Constriction

Claims (2)

[Claims] An apparatus for pulling a single crystal by the Czochralski method, in which a dislocation-free crystal portion after achieving dislocation-free by a dash neck method and crystal growth is continued, wherein a grip for holding a dislocation-free crystal is provided. Means, and a driving means for moving the gripping means in a state of gripping the crystal in the pulling direction, wherein the gripping means includes a tip member occupying an area in contact with a surface of the crystal when gripping the crystal. The tip member includes a metal bag showing flexibility at an ambient temperature when the crystal is gripped, and a plurality of granular substances having a higher melting point than the single crystal contained in the metal bag. A single crystal pulling apparatus, comprising: 2. The single crystal pulling apparatus according to claim 1, wherein when the single crystal is Si, the granular material is SiC, and the metal bag is made of stainless steel.