JP3674736B2 - Method for producing plate-like single crystal - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plate-like single crystal in which dislocation generation is suppressed using a metal semiconductor and a compound semiconductor as materials, and a method for producing the same.
[0002]
[Prior art]
Single crystals made of metal semiconductors such as silicon and germanium or compound semiconductor materials such as GaAs, GaP, InP, and InAs for use in integrated circuits have been conventionally produced by vapor deposition, solution methods, melt methods, etc. The bulk single crystal is formed by means for growing a single crystal from a melt, or by means of growing a single crystal in a cylindrical shape, such as temperature gradient solidification of the melt in a sealed tube.
[0003]
Such bulk single crystals require defects or dislocation-free single crystals that hinder the movement of minority carrier electrons and holes and degrade semiconductor properties, and generate thermal strain due to temperature gradient during single crystal growth. In addition, in the case of a pulling method for growing a bulk single crystal having a large diameter using a seed (seed crystal), in order to prevent propagation of edge dislocation from the seed, In the growth process, a narrow necking region is provided to release edge dislocations on the crystal surface.
[0004]
[Problems to be solved by the invention]
However, in such a means for growing a single crystal in a columnar shape, dislocations not released by the necking 11a in FIG. 4 and dislocations generated during the subsequent growth cannot be removed. Further, since the bulk single crystal region 11b has a large diameter, the generated edge dislocations 12 have a long growth distance until they are released on the surface of the crystal body, and new dislocations may proliferate in a branched manner during that time. There is a problem that the effective area of the bulk single crystal 11 is limited.
[0005]
That is, the conventional technique for growing large-diameter bulk single crystals has the following problems.
(1) When a single crystal is grown, edge dislocations are generated due to thermal strain, and the edge dislocations are easily proliferated.
(2) Necking must be formed to prevent propagation of edge dislocations from the seed.
(3) A long single crystal growth distance is usually required before the generated edge dislocations are released on the crystal surface, and the edge dislocations tend to proliferate during that time.
[0006]
In view of such problems of the prior art, the present invention suppresses the propagation of edge dislocations as much as possible by releasing the generated edge dislocations on the crystal surface at a short growth distance, resulting in less utilization of edge dislocations. It aims at obtaining a single crystal body with high.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a method for producing a single crystal by growing it into a plate shape, wherein dislocations generated in an oblique direction with respect to the growth direction of the plate single crystal are produced. A method for producing a plate-like single crystal characterized in that the density of dislocations not released in parallel to the plate surface is reduced to 100 pieces / cm ² or less, and the dislocation of the plate-like single crystal is also eliminated. A method for producing a plate-like single crystal characterized in that the density is a dislocation density not parallel to the (100) plane of the single crystal, and the plate-like single crystal is a metal semiconductor or a compound semiconductor, A method for producing a plate-like single crystal, a method for producing a plate-like single crystal characterized in that the plate-like single crystal is a GaAs semiconductor, and also dividing a rectangular parallelepiped space with slits A single crystal using a mold with a fixed space There is provided a method of manufacturing a plate-like single crystal, characterized in that grown.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
When growing a plate-like bulk single crystal, even if dislocations occur, edge dislocations with an angle that is not parallel to the growth direction of the plate-like single crystal have a shorter growth distance proportional to the plate thickness as the plate thickness decreases. Thus, a single crystal having almost no dislocations can be obtained. In other words, dislocations can be released to the crystal surface at a short growth distance by making the bulk single crystal into a plate shape and growing the single crystal with an angle between the direction of the dislocation line and the plane orientation of the plate. As a result, a bulk single crystal in which dislocation is suppressed can be obtained.
[0009]
For the single crystal growth means of the present invention, the conventional vertical temperature gradient solidification method (VGF method) or the vertical or horizontal Bridgman method for moving the melt vessel with a stepwise gradient in temperature distribution is used. However, a plate-shaped single crystal can be obtained relatively easily by using a mold having a space in which a rectangular parallelepiped space is divided by slits.
[0010]
FIG. 1 is a schematic perspective view of an apparatus for producing a plate-like single crystal according to the present invention, partially cut away.
[0011]
In this manufacturing apparatus A, a mold 1 is formed by combining long graphite materials having a rectangular cross section and two parallel bottomed cavities 2 having a long rectangular cross section in the vertical direction. The crucible 3 for converging the mold 1 is made in the shape of a cylindrical container so that an inert gas can be introduced into the crucible 3 and set in a growth furnace (not shown) equipped with a heater so that it can be moved up and down. It is.
[0012]
The mold 1 is molded or assembled using a graphite material or other materials according to the desired material and dimensions of the plate-like single crystal. The material of the crucible 3 is a reaction with the plate-like single crystal to be grown. It is preferable that a material having a low thermal conductivity is used. The heating temperature range may be moved up and down without moving the crucible 3 up and down.
[0013]
When the single crystal is formed, the seed 4 is preliminarily converged in the cavity 2 of the mold 1, and the growth raw material 5 is placed in contact with the seed 4.
[0014]
The seed 4 is a single crystal, the crystal orientation is arbitrary, and there can be any number of dislocations. As the growth raw material 5, a plate material cut from a single crystal or polycrystalline raw material may be arranged so as to contact the seed 4 as it is, or the melt of the growth raw material 5 is poured into the cavity 2 of the mold 1. It may be used in a state of being solidified in a state in which the seed 4 is blended with, or in a molten state in which the growth raw material 5 is poured.
[0015]
The crucible 3 in which the mold 1 charged with the seed 4 and the growth raw material 5 is set in this way is further set in the growth furnace, and the crucible 3 is moved downward, or the growth temperature range of the growth furnace is increased upward. Depending on the movement, it is possible to grow the plate-like bulk single crystal in one direction in a state of becoming the single crystal of the seed 4 while melting the growth raw material 5.
[0016]
With such a manufacturing apparatus A, as shown in FIG. 2, a plate-like bulk single crystal 6 comprising a dislocation-free region 7b grown in the direction indicated by the arrow through a dislocation release region 7a close to the seed 4 is obtained. . In a plate-like single crystal, the generated dislocations can be released and eliminated at an early stage on the plane or side of the plate-like body, except for dislocations parallel to the (100) plane of the crystal. That is, the direction of dislocation in the single crystal is regulated, for example, so that the single crystal of the compound semiconductor has an inclination of 35.3 ° with respect to the crystal plane (100). By doing so, it is possible to control the dislocation direction and release the dislocation at an early stage.
[0017]
In FIG. 3, which is an enlarged view of the dislocation release region of FIG. 2, the dislocation 8a that grows at an angle, that is, obliquely, from the seed 4 to both plane directions of the plate-like bulk single crystal 6 is released to both planes. Disappear. Dislocations 8b that grow parallel to both planes and at an angle with respect to the crystal growth direction (arrow direction in the figure), that is, obliquely, are released to the side edges of both planes and disappear. That is, in the dislocation 8a that grows at an angle in both plane directions, the dislocation 8b that is released to the crystal surface earlier as the angle is closer to the right angle, and grows parallel to both planes and at an angle with respect to the crystal growth direction. Is released at the side end face of the bulk single crystal 6 earlier as the angle becomes a dislocation in a direction close to a right angle. That is, the dislocations 8a and 8b are released at a shorter growth distance as the growth direction of the dislocations 8a and 8b is closer to the longitudinal direction of the bulk single crystal 6, so that the dislocation-free bulk single crystal 6 is efficiently obtained. be able to.
[0018]
According to the single crystal growth method of the present invention, the growth raw material 5 connected to the seed 4 is melted in one direction and then solidified by a method such as slow cooling, so that the melting in the longitudinal direction (crystal growth direction) is achieved. The dislocation density by EPD (etching pit detection method) of the (100) plane of the crystal after 1 mm from the formed portion can be set to 100 pieces / cm ² or less. For example, in the case of a GaAs semiconductor, the bulk single crystal obtained in this way is used as a chip by cleaving the (100) plane in the <110> direction.
[0019]
[Example 1]
The apparatus shown in FIG. 1 was used. The mold 1 was made of Nippon Carbon Hydrocarbon, and the dimensions of the two cavities 2 were 1 mm in length, 10 mm in width, and 100 mm in depth, respectively. At the bottom of the mold 1, a dislocation density by EPD of 100,000 pcs / cm ² is preliminarily formed of a GaAs single crystal having a crystal plane (100), a growth orientation <110>, a thickness of 1 mm, a width of 10 mm, and a length of 20 mm. Set seeds. Then, a GaAs melt is poured as a growth raw material until the total length including the seed reaches 100 mm, then the top of the crucible 3 is heated to 1300 ° C. and the bottom is heated to 1200 ° C. After melting 80 mm of the raw material for growth, the crucible 3 was moved down at a speed of 10 mm / hour in a temperature gradient of 10 ° C./cm to solidify the melt.
[0020]
About the obtained bulk single crystal plate material, the dislocation density was measured by EPD. As a result, the dislocation density of the part that was not melted did not change, but from the melted part, the dislocation density was 100 pieces / cm ² or less for the (100) plane of the crystal 1 mm ahead in the longitudinal direction.
[0021]
[Example 2]
A template was prepared in the same manner as in Example 1, set in a crucible, a similar GaAs single crystal plate was set as a seed, and a GaAs melt was poured as a growth material. Similarly, the raw material for growth above the seed was melted 80 mm in the longitudinal direction, and then the crucible was moved at a rate of 10 ° C./hour to cool and solidify the melt.
[0022]
The resulting bulk single crystal plate material was measured for dislocation density by EPD. As a result, the dislocation density of the seed portion that was not melted did not change, but from the melted portion, the dislocation density was 100 pieces / cm ² or less for the (100) plane of the crystal 1 mm ahead in the longitudinal direction. .
[0023]
[Example 3]
A template was prepared in the same manner as in Example 1. A GaAs single crystal plate having a dislocation density of 100,000 pieces / cm ² , a crystal plane (100), a growth orientation <110>, a length of 100 mm, a width of 10 mm, and a thickness of 1 mm was set as a mold without using a seed. The mold is set in the above-mentioned hydrocarbon crucible, the upper part of the crucible is heated to 1300 ° C., the bottom part is heated to 1200 ° C., leaving the lower 20 mm, and the upper 80 mm is melted, and then in a temperature gradient of 10 ° C./cm The crucible was moved down at a speed of 10 mm / hour to solidify the melt.
[0024]
The resulting bulk single crystal plate was measured for dislocation density by EPD. As a result, the dislocation density in the part that was not melted did not change, but the dislocation density was 100 or less per cm ² on the (100) plane of the crystal 1 mm and beyond in the longitudinal direction from the melted part.
[0025]
[Example 4]
A template was prepared in the same manner as in Example 3, a similar GaAs single crystal plate was set, and by using the same heating without using a seed, the lower 20 mm was left, and the upper was melted 80 mm in the longitudinal direction. It was cooled at the speed of time and solidified into its original shape.
[0026]
The resulting bulk single crystal plate was measured for dislocation density by EPD. As a result, the dislocation density in the part that was not melted did not change, but the dislocation density was 100 or less per cm ² on the (100) plane of the crystal 1 mm and beyond in the longitudinal direction from the melted part.
[0027]
【The invention's effect】
As explained above, according to the present invention, necking is not required as in the case of a conventional cylindrical bulk single crystal, and even if dislocation occurs, it can be extinguished with a very short growth distance. A dislocation-free bulk single crystal can be obtained efficiently. The present invention can be effectively applied to a metal semiconductor or a compound semiconductor, and in particular, has an effect that it can be accurately applied in the case of a GaAs semiconductor. By using a mold having a cavity with a rectangular cross section, it is possible to easily grow a single crystal into a plate shape.
[Brief description of the drawings]
FIG. 1 is a partially cut perspective view showing an apparatus for producing a plate-like single crystal according to the present invention.
FIG. 2 is a schematic perspective view of a plate-like bulk single crystal produced by the production apparatus of FIG.
FIG. 3 is an enlarged perspective view of a main part of FIG. 2;
FIG. 4 is a schematic perspective view of a bulk single crystal produced by a conventional manufacturing apparatus.
[Explanation of symbols]
A Manufacturing apparatus 1 Mold 2 Cavity 3 Crucible 4 Seed 5 Growth raw material 6 Bulk single crystal 7a Dislocation release region 7b Dislocation free region 8a, 8b Dislocation

Claims (5)

A method for producing a single crystal by growing it into a plate shape, wherein dislocations generated in an oblique direction with respect to the growth direction of the plate single crystal are released to the surface of the plate single crystal and eliminated, A method for producing a plate-like single crystal, wherein the density of non-parallel dislocations is 100 pieces / cm ² or less. 2. The method for producing a plate-like single crystal according to claim 1, wherein the density of dislocations in the plate-like single crystal is a dislocation density not parallel to the (100) plane of the single crystal. The method for producing a plate-like single crystal according to claim 1 or 2, wherein the plate-like single crystal is a metal semiconductor or a compound semiconductor. The method for producing a plate-like single crystal according to any one of claims 1 to 3, wherein the plate-like single crystal is a GaAs semiconductor. The method for producing a plate-like single crystal according to any one of claims 1 to 4, wherein the single crystal is grown into a plate shape using a mold having a space obtained by dividing a rectangular parallelepiped space with slits.

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