JPH06103674B2 - Method and apparatus for adjusting angle of semiconductor single crystal ingot. - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method and an apparatus for correctly determining a crystal orientation when a semiconductor single crystal ingot is cut into a specific crystal orientation.

A semiconductor single crystal is a semiconductor such as GaAs, InP or Si. Some are made by the Czochralski method, while others are made by the horizontal Britzmann method.

Si is often pulled up by the Czochralski method (CZ). <
Pull up in the 100> direction and the <111> direction. A cylindrical ingot is obtained.

GaP and GaAs are also sometimes grown by the Czochralski method. It is called liquid-encapsulated Czochralski method (LEC) because high pressure is applied to the liquid surface using liquid capsule B ₂ O ₃ .

By the Czochralski method, single crystal ingots of <100> direction and <111> direction can be obtained.

A thin slice of an ingot is called a wafer.
The plane orientation of this is (100), (111), etc.
0) There are many wafers.

The ingots grown by the CZ method and LEC method have a circular cross section. To obtain a (100) wafer, an ingot grown in the <100> direction may be sliced at right angles to the growth direction.

In the case of III-V group such as GaAs single crystal, the Horizontal Bridgman method is often used. This is a method in which a raw material is put in a semi-cylindrical boat, sealed in a quartz tube, and horizontally moved in a furnace having a temperature distribution to gradually solidify the raw material in the boat. This is a method in which thermal stress is less likely to occur. Therefore, a high quality single crystal with few dislocations can be obtained.

However, the horizontal Britzmann method cannot grow into an arbitrary method. Can only grow in the <111> direction. Moreover, the grown ingot does not have a cylindrical cross section. It is a semi-cylindrical cross section.

Therefore, if you want to obtain a (100) wafer, do not cut it at right angles to the longitudinal direction of the ingot. It will be cut in a direction that makes an angle of 54.7 ° with the longitudinal direction of the ingot.

It does not mean that the direction is always 54.7 ° and that it may be in any direction. There are only three directions equivalent to (100). In practice, only one of these directions is effective to reduce material loss.

In general, this direction is the direction in which the line of intersection between the cut surface and the free surface of the ingot (the portion corresponding to the chord of the semi-cylindrical cross section) is orthogonal to the longitudinal direction.

In order to be able to cut in such a direction, from the growth direction,
It must be grown so that the [100] direction exists in the direction of 54.7 ° above the slope or 54.7 ° below the slope.

In other words, the orientation around the growth direction must also be specified.

An example is given. The growth method is <111>, and within the vertical plane including this direction, <100> is formed in the direction forming 54.7 ° with <111>.
Is diagonally downward. Then, <001> and <010> are positioned obliquely upward and symmetrical with respect to the vertical plane. It is shown in FIG.

Then, the direction of the normal to the free surface of the crystal is <11>.
It means that.

This is an example of an ideal case.

Thus, the single crystal ingot grown by the HB method has a difficult problem.

Of course, the present invention can also be applied to a single crystal produced by the CZ method and LEC method of the present invention. However, since the ingot of the HB method involves a difficult problem, the ingot made by the HB method will be mainly described below.

(B) Conventional technology If the growth direction is the <111> direction, there is always a deviation from this direction. There is also rotation around the growth direction. In the above example, the free surface cannot always be the <11> plane.

Therefore, the crystal orientation is determined as follows.

Supporting the ingot, the inner blade slicer has a thickness of 0.3 ~
A device that cuts a 1.0 mm wafer is sometimes called a slicer.

The slicer has a mounting block that supports the ingot. Attach the ingot to the mounting block via the spacer.

The spacer is a simple disk such as carbon or gypsum.
The ingot is fixed to the spacer with an epoxy adhesive. The mounting block can rotate about a vertical axis or about a horizontal axis.

However, the range of rotation about the vertical axis is limited. This is the problem.

FIG. 5 is a schematic diagram of a conventional slicer device. This is only a diagram for explaining the degree of freedom of movement. It does not correspond to the actual shape of the slicer.

The mounting block 10 has its rear end pivotally connected to a rotary base 12 by a horizontal shaft 11. The rotating base 12 is a vertical axis
It is connected to the fixed base 14 by means of 13.

The mounting block 10 can rotate about a horizontal axis 11. However, it can only rotate downward. Horizontal line l
And the angle h between the axis h of the mounting block 10 and Y
And Y can be arbitrarily set in the range of 0 to 60 °.

Although not shown here, there is a device for arbitrarily setting the tilt angle Y. This can be easily constructed by a circular arc groove and a bolt.

The wide range of the tilt angle Y is 0 to 60 ° because the ingot by the HB method can be sliced. This is because it takes a tilt angle of 54.7 ° to cut a (100) wafer from an HB method ingot grown in the <111> direction.

The rotating base 12 can rotate around a vertical axis 13. It is a horizontal rotation. This rotation is called X rotation, and the rotation angle is represented by X. This is custom.

The center of horizontal rotation is 0 °, and ± X _m can be rotated back and forth. −
Is an _{X m} ~ + X _m. The larger the maximum rotation angle X _m, may provide any direction for any Ingotsuto.

However, it is mechanically difficult to increase X _m . Therefore, the conventional X _m has a narrow angle of about 7 °. The horizontal rotation range is 14 °. Vertical tilt range is narrower than 60 °.

The small X _m has a mechanical problem, but the horizontal adjustment may not be as large as the vertical adjustment.

The end of the ingot 1 is cut and fixed to the spacer. At this time, the cut surface is appropriately selected, and the rotation angle around the mounting block axis h is appropriately selected. If these choices are adequate, then almost no horizontal angle adjustment is necessary. Therefore, X _m is small.

However, since it is an ingot before it is examined by X-ray diffraction, details of the crystal orientation cannot be known. Cutting the end of the ingot is not always appropriate. When fixed to the spacer,
Rotation about the axis h is not always appropriate.

Therefore, as in the conventional slicer device, the horizontal rotation angle range of ± 7 ° may be too narrow.

The slicer device has a mechanism for rotating the inner blade in addition to the ingot support mechanism for supporting the ingot.

The blade surface Σ of the inner peripheral blade is constant. This is called the cut surface Σ. The blade surface is Y = 0, X =
When 0, it is a surface orthogonal to the mounting block axis h.

The direction of the axis h when Y = 0 and X = 0 is referred to as a reference horizontal line l.

The cutting plane Σ and the reference horizontal line 1 are at a right angle. This relationship is unchanged.

The tip of the ingot is put into the inner circumference of the inner peripheral blade, the blade is translated in the cutting plane Σ, and a thin piece is cut out from the ingot. This is an azukato wafer.

Then, send the entire ingot support mechanism a fixed distance,
Cut the tip of the ingot again with the inner blade.

As a preparatory step for slicing, the orientation of the ingot must be determined. If a (100) wafer is required, the horizontal rotation angle X and the tilt angle Y are adjusted so that the cutting plane Σ and the (100) plane are parallel to each other. This is shown in FIG.

Fix the ingot 1 to the spacer 2 and adjust the angle roughly. For example, X = 0 and Y = Y ₀ . In the case of HB ingot, Y ₀ is about 55 °. Also in this case, the [100] direction of the ingot is included in the vertical plane Y, and Y + 5
It is necessary to fix it so that it is at an angle of about 4.7 °. Here, the vertical plane Y is a vertical plane that includes the ingot axis h (which is also the mounting block axis) when the ingot is moved up and down in the direction of the tilt angle Y. The fact that Y is positive means that it is facing obliquely downward.

At X = 0, Y = Y ₀ , one ingot is sliced by the inner blade. This is a wafer for orientation determination.

The wafer is cleaved along with the cleavage. Cleavage plane (011),
(01) appears.

This is shown in FIGS. 7 and 8. If the wafer surface is {100}
If this is the case, this plane is parallel to the normal <011> standing on the cleavage plane. However, this is not the case because the wafer surface is offset from {100}. In the <011> direction, the angle formed by the wafer surface is A.

Similarly, the angle formed by the normal to the cleavage plane (01) and the wafer surface is B. If the wafer surface is {100},
Both A and B are 0, but not so A and B are 0
Not.

Then, the horizontal angle and the tilt angle may be adjusted so that A and B become 0. Adjust the horizontal angle and tilt angle by Δ
Let X and ΔY. The relationship between this and A and B is obtained.

As shown in FIG. 3, an origin O is located on the surface of the ingot cut out from the orientation determination wafer, and this surface Σ becomes the XY plane.
Consider a coordinate system in which X faces vertically downward.

The ingot axis h is in the XZ plane and the angle with the axis is
Y ₀ .

The <100> direction is close to the Z-axis direction. But not the same.
It is assumed that the difference about the X axis is ΔX and the difference about the Y axis is ΔY.

The <01> direction is close to the Y-axis direction. But they do not match.
Let OR be the projection of <01> on the Σ plane, that is, the XY plane. The angle between OR and <01> is B. Let θ be the angle between OR and OY.

The <0> direction is close to the X axis direction. But they do not match.
Let OQ be a projection of <0> on the XY plane. OQ and <
The angle formed by 0> is A. The angle between OQ and OX is θ.

ΔY is mainly caused by the deviation A of <0> from the X axis. This is the weight of cos θ and contributes to ΔY.

The deviation B of <01> from the Y axis is also included in ΔY. This is because the orthonormal OR affects ΔY by the amount of θ forming the Y axis.

A positive value of B affects the direction of making ΔY negative. The contribution of this is −Bsinθ.

After all, it means ΔY = A _cos θ−B _sin θ (1). This is the tilt angle. The horizontal rotation angle is the same, but since the ingot is tilted by Y _0, it is 1 / _cos Y ₀
Enter the coefficient.

ΔX = (B _cos θ + A _sin θ) / _cos Y ₀ (2). This is the angle of deviation between the <100> direction and the Z-axis direction. Then, by finely adjusting the ingot azimuth by -ΔX around the X axis and -ΔY around the Y axis, the Z axis and the <100> direction can be matched. That is, <100
It is possible to make the> direction and the cutting plane Σ orthogonal. In this state, the second and subsequent wafers may be cut with the inner blade. It is possible to obtain a wafer whose cutting plane Σ is the (100) plane.

(C) Problems of the conventional technology However, there are cases where it is not as simple as that. This is because the rotation angle range in the X direction is limited.

For example, it is assumed that a test wafer is cut out, the angle is measured, and B = 5 ° A = 2 ° θ = 3 ° Y ₀ = 55 °. Substituting this into equation (2) gives ΔX = 8.9 ° (3). This is outside the adjustment range because the adjustment range of X is ± 7 °.

That is, it cannot be adjusted by the conventional X and Y direction adjusting mechanism.

In such a case, remove the ingot from the spacer and
The ingot was rotated around the axis and glued again to the spacer.

As described above, it is necessary to re-install it. It was annoying.

(D) Configuration In the present invention, in order to solve such a problem, the ingot can be rotated around the ingot axis (mounting block axis) line h.

That is, the spacer has hitherto been attached directly to the mounting block. Instead of this, in the present invention, a mounting jig is inserted in the middle so that the spacer and the mounting block can relatively rotate about the axis.

The slicer device has an ingot support mechanism and a blade rotation mechanism as described above. Conventionally, the ingot support mechanism only allows rotation in the Y direction and the X direction, but in the present invention, rotation about the ingot axis h is also allowed.

FIG. 1 shows a schematic perspective view of an ingot slicer device of the present invention.

The ingot 1 is bonded to the spacer 2.

The spacer 2 is fixed to the first mounting jig 3.

The second mounting jig 4 is mounted on the mounting block 10.

The first mounting jig 3 is combined with the second mounting jig 4 so as to be rotatable in the axial direction.

That is, the mounting jigs 3 and 4 are fixed by the set screw 5, but can be removed by loosening the set screw 5.

FIG. 2 shows an exploded perspective view of a mounting jig portion.

The rear end of the first attachment jig 3 is a conical convex portion 6 and the outermost end is the head 7.

Correspondingly, a conical recess 8 is formed in the front part of the second mounting jig 4. Further, screw holes 9 are formed in the radial direction.

The conical protrusion 6 and the head 7 of the first mounting jig 3 are fitted into the conical recess 8 of the second mounting jig 4. The set screw 5 is screwed into the screw hole 9. Hold the head 7 with the set screw 5. In this way, the first and second attachment jigs 3 and 4 are fixed to each other.

On the contrary, when the set screw 5 is loosened, the second mounting jig 4 can be rotated about the first mounting jig 3 and the axis h.

Other points are the same as the conventional ones.

The mounting block 10 can rotate vertically about a horizontal axis 11. The rotation angle Y is, for example, 0 to 60 °.

The rotary base 12 can rotate horizontally around a vertical axis 13. The rotation angle X is −X _m to + X _m , and X _m is about 7 °.

The mounting block ingot axis h when X = 0 and Y = 0 is set as the reference horizontal line 1. The cutting surface Σ of the inner peripheral blade is set so as to be perpendicular to the reference horizontal line 1.

(E) Action The ingot can be rotated around the ingot axis h. Therefore, it is possible to adjust the angle in the H direction in addition to the angle adjustment in the X direction and the Y direction.

As is clear from the arrangement of FIG. 3, the angles ΔX and ΔY of the deviation of <100> from the Z axis have a correlation with the rotation in the H direction. As long as the h axis is in the XZ plane, the minute rotation ΔH in the H direction is
There is no secondary effect on ΔY. However, ΔH has the effect of _sin Y ₀ ΔH = −ΔX (4) with respect to ΔX. This is clear from FIG.

That is, when the range of ΔX is insufficient, the required rotation can be obtained by ΔH.

For example, if the adjustable range of ΔX is 7 ° and the required Δ
Let X be 8 °. 1 ° shortage. The lack of 1 ° can be compensated for by the rotation of ΔH. In other words, it only needs to rotate 1 / _sin Y ₀ degrees around the h axis.

It's not just about making up for the shortfall. The opposite idea is possible.

By rotating ΔH, the wafer surface (100) is brought closer to the direction perpendicular to the Z axis, and the insufficient ΔX and ΔY are corrected by re-adjusting ΔX and ΔY.

It is possible to go further and omit the adjustment of ΔX and just adjust ΔH and ΔY.

(F) Example A GaAs single crystal was grown in the <111> direction by the horizontal Britzmann method. This ingot was attached to the slicer of the present invention. It is attached via the attachment jigs 3 and 4. Rotation about the h-axis is possible.

This ingot was set to a horizontal rotation angle X = 0 ° and an inclination angle Y = 55 °. This comes from having to cut at 54.7 ° to take a (100) wafer from <111>. This was cut with an inner peripheral blade.
A test wafer having a plane parallel to the cutting plane Σ was obtained.

This is cleaved and has a normal line perpendicular to <100> (01)
The (0) face was brought out. The angles B and A formed by the wafer surface Σ and the normals to these surfaces were measured. Further, the deviation angle θ from the Y axis in the <01> direction was also measured. As a result, B = 5 ° A = 2 ° θ = 3 ° (5) When the angles of ΔX and ΔY for canceling these deviations are calculated from (1) and (2), ΔX = 8.8 ° (6) ΔY = 1.73 ° (7). This adjustment cannot be made because the settable range of ΔX is 7 °.

Therefore, based on the method of the present invention, the set screws 5 of the first and second attachment jigs 3 and 4 were loosened, and the ingot 1 was rotated about the h-axis. Set screw 5 was retightened. X direction, Y
Only the H direction was adjusted without adjusting the direction. And again,
The test wafer was cut off. The second wafer was also cleaved and the deviation angle was measured. As a result, B = 2 ° A = 2 ° θ = 1 ° (8)

ΔX = 3.6 ° ΔY = 1.96 ° (9) is calculated. If it is 3.6 °, it is less than 7 ° and can be adjusted. Therefore, such rotation was performed to cut the wafer. As a result, a wafer having a {100} orientation was obtained.

This adjusts the H direction, the X direction, and the Y direction. Two
It is a degree adjustment. The angle ΔH around the h-axis is 3.6 °.

Furthermore, it is easier to see if the value of (5) is displayed or H
= 6.08 ° rotation, B = 0.0171 ° A = 2 ° θ = −0.489 ° (10) Then, ΔX = 0 and ΔY = 2 °. Therefore, the {100} wafer can be immediately cut out by rotating ΔH = 6.08 ° and ΔY = 2 ° after the value of (5) is known from the first test wafer.

Such a thing is understood immediately when the effect of the rotation ΔH about the h axis on B and θ is considered. As is apparent from FIG. 3, ΔB ′ = − _sin Y ₀ ΔH (11) Δθ ′ = − _cos Y ₀ ΔH (12). To set ΔX to O, set B in equation (2) to B ₀ + Δ
Replace θ with θ ₀ + Δθ 'in B', sin θ ≒ πθ / 18
Approximate 0, cos θ ≈ 1, If B ₀ is B of the first test wafer.
As is the case with A, I omitted the suffix "0" because A is unchanged.

From (11) to (13) Becomes Since B ₀ = 5 °, A = 2 °, θ ₀ = 3 °, and Y ₀ = 55 °, ΔH = 6.083.

(G) Effect When the semiconductor ingot is attached to the mounting block of the slicer and sliced into a wafer by the inner peripheral blade, the angle adjustment becomes easy.

Even when the range of the rotation angle X in the horizontal direction is narrow and limited, the relative orientation between the mounting jigs and the rotation of the ingot around the axis can cut the wafer in the desired orientation. .

There is no need to remove the ingot from the spacer and glue it again.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram of a semiconductor ingot slicer device of the present invention. FIG. 2 is an exploded perspective view of only the portion of the ingot and the first and second mounting jigs. FIG. 3 shows that the rotation ΔH about the ingot axis h is ΔX,
Explanatory drawing which shows the effect which it has on (DELTA) B and (DELTA) (theta). FIG. 4 is a diagram explaining an ideal example of the orientation of an ingot grown in the <111> direction by the HB method. FIG. 5 is a schematic configuration diagram of a conventional ingot slicer device. FIG. 6 is an explanatory view when a GaAs ingot of the HB method grown in the <111> direction is inclined by 55 ° and a wafer is cut out. FIG. 7 is a diagram showing the definition of the tilt angle A between the normal line <011> of the cleaved surface of the cut wafer and the wafer surface. Fig. 8 shows the normal line <01> of the cleavage plane of the cut wafer.
FIG. 6 is a diagram showing the definition of a tilt angle B of the wafer surface. 1 ... Ingot 2 ... Spacer 3 ... First mounting jig 4 ... Second mounting jig 5 ... Set screw 6 ... Conical convex portion 7 ... Head 8 ... Conical concave portion 9 ... Screw hole 10 …… Mounting block 11 …… Horizontal axis 12 …… Rotary base 13 …… Vertical axis 14 …… Fixed base l …… Reference horizontal line Σ …… Cut plane h …… Ingot mounting block axis X …… Horizontal rotation angle Y …… Inclination angle H …… Rotation angle around h axis O …… Origin of coordinates OX …… Horizontal rotation center line OY …… Inclination center line OZ …… Half line parallel to l and perpendicular to Σ OR …… Projection of <01> on Σ plane OQ …… Projection of <0> on Σ plane θ …… An angle between OR and OY B …… Angle between <01> and OR A …… <0> And the angle between OQ

Claims (2)

[Claims] 1. A tilt and rotation about a horizontal axis Y, a horizontal rotation about a vertical axis X, an arbitrary tilt angle Y ₀ in a range and an arbitrary horizontal rotation in a limited range. It is composed of an ingot support mechanism having a mounting block 10 that can be fixed at an angle X ₀ , and a blade rotation mechanism that faces the mounting block 10 and holds the inner peripheral blade within a cutting plane Σ having a certain orientation and rotates it. A mounting block for a slicer device of a semiconductor single crystal ingot in which a wafer is cut out from an ingot without rotating an ingot by rotating a blade.
10, the second mounting jig 4 and the first mounting jig which are rotatable about the axis relative to each other
The mounting jig 3 is attached, the semiconductor single crystal ingot is fixed to the end surface of the first mounting jig 3 by the spacer 2, the proper horizontal rotation angle X ₀ and tilt angle Y ₀ are set, and the position where the ingot is rotated to this angle Then, the ingot is cut with an inner peripheral blade to obtain a test wafer, and the angles A and B formed by the cleavage direction and the wafer surface and the angle θ formed by the cleavage direction and the Y axis or X axis are measured. Is adjusted to 0 to adjust the rotation angle H about the ingot axis h, the minute rotation angle ΔY of the tilt angle Y, and the minute rotation angle ΔX in the horizontal direction, or the rotation angle H about the ingot axis h and the tilt angle Y are small. A method for adjusting an angle of a semiconductor single crystal ingot, wherein a desired wafer surface orientation and a blade cutting surface Σ are made parallel by adjusting a rotation angle ΔY. 2. A fixed base 14 and a rotary base provided on the fixed base 14 via a vertical shaft 13 so as to be rotatable in a horizontal direction and fixed at an arbitrary horizontal rotation angle X ₀ within a limited range. 12, a mounting block 10 provided on a rotary base 12 via a horizontal shaft 11 and can be tilted in the vertical direction, and can be fixed at an arbitrary inclination angle Y ₀ within a limited range, and fixed to the mounting block 10. The second mounting jig 4 and the first mounting jig 3 which are connected in series to the second mounting jig 4 and can be relatively rotated around the ingot axis h and can be fixed at an arbitrary rotation angle H.
And an ingot support mechanism composed of a spacer 2 for fixing the ingot 1 to the end surface of the first mounting jig 3 and a cutting surface Σ of a certain orientation for cutting the ingot provided so as to face the mounting block 10. A semiconductor characterized by comprising an inner peripheral blade to be held and a blade rotating mechanism for supporting and rotating the inner peripheral blade, and rotating the blade to rotate the ingot and cut the wafer from the ingot. Angle adjustment device for single crystal ingot.