JP3812573B2 - Semiconductor crystal growth method - Google Patents

Description

The present invention relates to a method for growing a semiconductor crystal by a vertical Bridgman method. Various methods are known for growing semiconductor crystals. In the case of Si single crystal, the Czochralski method is most effective. Most Si single crystals are made by this method. The raw material is placed in a crucible and heated from around by a heater to form a melt, and the seed crystal is hung from above and seeded, and the seed crystal is pulled up while rotating to pull up the single crystal. The diameter of a single crystal is often less than half that of a crucible. The Czochralski method is a typical crystal growth method and is widely used in addition to Si.
In the case of a compound semiconductor such as GaAs and InP, special vaporization for preventing dissociation of the V group is necessary because the vapor pressure of the V group element is high. Typical methods are the horizontal Bridgman method and the liquid-sealed Czochralski method.

  In the horizontal Bridgman method, raw materials are put into a semicircular cross-section boat, which is put into one space of a long quartz tube partitioned by an intermediate partition, and sealed with As and P in the other space. This is put into a furnace with a temperature gradient and grown. A seed crystal is placed on one end of the boat. The whole is heated to a high temperature to melt the raw material, and then gradually cooled from the seed crystal side. A single crystal with the same orientation as the seed crystal grows laterally. Since the growth direction is horizontal, there is a limitation of being horizontal.

  The Bridgman method is characterized in that the melt and the single crystal are in the same container and have the same cross-sectional area. The boundary surface (solid-liquid interface) moves gradually. The solid-liquid interface is moved by moving the quartz tube in a furnace with a temperature gradient. Since the horizontal Bridgman method does not pull up the crystal, it is possible to obtain a crystal with little stress and no stress. Therefore, a high-quality single crystal having a low dislocation density can be produced. Crystals of compound semiconductors such as light-emitting elements and high-frequency elements are produced by this method.

In the liquid sealing Czochralski method, a raw material is put in a crucible and a sealing agent such as B ₂ O ₃ is further added. Heat to high temperature and apply high pressure to prevent volatilization of group V elements. The seed crystal is hung from above, seeded, and pulled up while rotating. Since the high pressure suppresses the sealant, volatilization of the group V can be prevented, but the thermal insulation of the sealant is large and the temperature gradient is large, so that thermal distortion tends to occur. Crystals made by this method have a high dislocation density.

  The vertical Bridgman method which is the subject of the present invention is different from any of these typical compound semiconductor growth methods. It's like a horizontal bridgeman made vertical. Put the vertical crucible containing the raw material into a vertical temperature gradient furnace with the upper part at a high temperature and the lower part at a low temperature, melt the whole into a melt, move the crucible downward, and gradually start the raw material from below Solidify the melt. Since the bottom is solid and the top is liquid, the temperature gradient is opposite to the Czochralski method.

  First, we will explain why the vertical Bridgman method is necessary. The Czochralski method is a familiar method, the boundary between solid and liquid is clear, and control is easy. The weight of the crystal can be measured by a load cell attached to the upper shaft. The boundary can be observed visually or with a television camera. However, the Czochralski method cannot grow a mixed crystal having a uniform impurity concentration or a uniform composition. In general, the raw material in the crucible is in an equilibrium state, and the impurity concentration differs at the solid-liquid interface. The value obtained by dividing the impurity concentration in the solid by the impurity concentration of the liquid (melt) is a constant based only on temperature. The value of this ratio is called the segregation coefficient. If the segregation coefficient is less than 1, the impurities in the melt are concentrated with the pulling, so that the impurity concentration in the crystal increases. On the contrary, when the segregation coefficient is greater than 1, the impurity concentration decreases.

  This is the case of impurities, but the same is true for mixed crystals. The raw material composition contained in the melt and the solid in the parallel state is not the same. Therefore, the mixed crystal ratio fluctuates with growth. A mixed crystal having a uniform composition cannot be obtained. Such a defect is also the same in the horizontal Bridgman method. Since the melt and the solid (crystal) are in thermal equilibrium, the raw material composition of the solid and the melt is not the same.

As a method of growing a crystal by the vertical Bridgman method,
Japanese Patent Laid-Open No. 1-221291 (1989. 8.25) ... The temperature at a plurality of locations is obtained by providing thermocouples at a plurality of locations, the temperature distribution is calculated and estimated based on this, and the growth interface shape and the growth interface position change. To control. PCT application WO 91/02832 (19991.3.7) ... In addition to the external main heater, a disk-shaped auxiliary heater is provided inside the raw material melt. The movement of the raw material melt is suppressed by the action of the auxiliary heater. This is because the effective segregation coefficient is substantially equal to 1, and a crystal having a constant impurity concentration can be grown.

  The vertical Bridgman method is said to be suitable for mixed crystals and crystals containing impurities, but it does not necessarily produce a mixed crystal ratio or a constant impurity concentration in the longitudinal direction. In this method, it is not clear where the interface between the solid part and the liquid part is, and it is difficult to keep the crystal growth conditions uniform in the longitudinal direction. When the crucible is moved in a certain direction at a constant speed, the growth rate (solid-liquid interface velocity) is affected by mechanical noise accompanying the crucible movement and changes in the thermal environment in the furnace caused by the movement of the crucible. ), And this causes a story (micro compositional change).

In the case of a mixed crystal semiconductor, the mixed crystal ratio also fluctuates in the longitudinal direction. The impurity concentration of a semiconductor doped with impurities varies in the longitudinal direction. In the case of an andrp semiconductor, twins easily enter and the crystallinity is poor. The structure of Patent Document 1 is complicated. There is also a problem in reproducibility. In Patent Document 2, impurities may be mixed into the raw material melt.
In the vertical Bridgman method, the present invention makes the growth rate constant by making the crystallization position (melting point position or solid-liquid interface position) of the raw material constant, and crystal with stable impurity concentration and mixed crystal ratio. The purpose is to grow.

  The method for growing a semiconductor crystal according to the present invention includes a vertical crucible, a cylindrical vertical heat insulating material surrounding the outer periphery of the crucible, a lower shaft capable of supporting and moving up and down the heat insulating material crucible, and the periphery of the heat insulating material. Using a semiconductor crystal growth apparatus that includes a heater that is provided in the vertical direction and that can independently control output and that can form a temperature distribution in the vertical direction, and a temperature sensor installed on the outer periphery of the crucible. The raw material solid is contained in the heater, the heater is energized, and the heat of the heater heats the crucible for heat insulation. The heat melts the raw material into a raw material melt, and the heater output is adjusted The heat treatment is controlled so that the amount of heat passing through the heat insulating material is smaller than the amount of heat in the vertical direction, while the raw material melt is solidified from below and the solid-liquid interface protrudes upward. Crystal growth while maintaining

Since the heat insulating material is provided on the outer periphery of the crucible, the raw material melt is shielded from the heater and the outside, and the temperature distribution of the raw material melt and the solid is stabilized. Since the crucible is surrounded by heat insulating material, the heat flow is mainly in the vertical direction. The heat flow across the insulation is small. If there is no heat insulating material, the heat will be radiated from the raw material melt and the material will be heated by the radiation of the heater, so the temperature fluctuation will be large, but in the case of the present invention, the temperature in the melt / solid part will be wrapped with the heat insulating material. The stability of is excellent. Further, since the heat insulating material blocks the heat radiation from the heater, the temperature measurement by the temperature sensor becomes precise.
Alternatively, in addition to the temperature sensor set at the melting point position, one or more temperature sensors are provided above and one or more temperature sensors are provided below. Since the number of temperature sensors is increased, the temperature distribution on the outer periphery of the crucible can be measured more precisely.
The amount of heat that flows from the position above the melting point to the position of the melting point is larger than the amount of heat that flows from below the position of the melting point, and the amount of heat that passes through the heat insulating material is small. The solid-liquid interface becomes convex upward.

  In the present invention, a raw material is placed in a vertical crucible surrounded by a vertically long heat insulating material to form a melt, and a plurality of independent heaters arranged in the vertical direction are controlled so that the lower temperature is lower and the upper temperature is higher. The distribution is made, and the heat insulating material, the crucible, and the melt are lowered in a temperature gradient in which the lower temperature is low and the upper temperature is high, so that the raw material melt is solidified from below. A vertically long space is formed inside the outer periphery of the crucible from the heat insulating material, and a temperature sensor such as a thermocouple is provided so as to be movable up and down, and the temperature of the raw material melt is measured. The temperature sensor is highly reliable because it is surrounded by heat insulating material and does not receive the radiation of the heater directly. In the present invention, the position of the temperature sensor and the position of the solid-liquid interface are not changed, and the raw material melt and the crystal are lowered downward by displacing the lower shaft downward. In this way, the conditions for solidifying the raw material melt do not change with time. Since the temperature sensor is fixed at the melting point of the raw material, the relationship between the solid-liquid interface in the raw material and the temperature sensor is constant. For this reason, the height of the solid-liquid interface is constant. The difficulty of the vertical Bridgman method is that the solid-liquid interface is unknown. However, the present invention can always know the position of the solid-liquid interface precisely. It is a powerful method to eliminate the drawbacks of the vertical bridgeman.

FIG. 1 is a schematic configuration diagram of a vertical Bridgman device of the present invention. Heaters 2, 3, 4, 5, which can control power independently, are installed in the vertical direction inside the chamber 1 that can be evacuated. Thereby, an arbitrary temperature distribution can be formed. There is a vertically long crucible 6 at the center of the chamber 1. The outer peripheral surface of the crucible is surrounded by a cylindrical heat insulating material 12. The lower bottom of the crucible 6 and the lower end of the heat insulating material are supported by the lower shaft 8. A vertically long thermocouple insertion tube 9 is formed inside the side heat insulating material of the crucible 6. A thermocouple 10 is inserted into the thermocouple insertion tube 9 from above. A raw material melt 7 is accommodated inside the vertically long crucible 6. The upper opening of the crucible 6 is closed with a lid 11. Radiant heat from the heater directly heats the insulation. The temperature of the heat insulating material is raised, and the heat transmitted through the heat insulating material is transferred to the inner crucible or the raw material inside the crucible is heated to form a melt. The heat insulating material blocks direct heating from the heater and prevents direct heat radiation from the raw material melt.
In this state, everything is a melt. The temperature environment by the heater is low in the lower part and high in the upper part. By lowering the lower shaft 8, the melt gradually solidifies from the lower side. The position of the thermocouple 10 is not changed. Moreover, the thermocouple 10 is adjusted so that it is always located at the solid-liquid interface. The lower shaft lowering speed is adjusted to satisfy these conditions. The height of the solid-liquid interface is always constant. The crystal grows under the same conditions in the vertical direction. A crystal having a uniform quality and a uniform impurity density can be grown.

  In the present invention, since the outer peripheral surfaces of the crucible and the temperature sensor are covered with a heat insulating material, the heater radiation does not directly hit the crucible, and heat does not escape from the crucible to the side by radiation. Because of its high thermal insulation, the temperature distribution of the raw material melt and solid inside the crucible is stable and not subject to temporal disturbance. If the radiation from the heater hits the temperature sensor, the measured value will be higher, but if it is wrapped with a heat insulating material, the radiation will be blocked. Since it is only heat conduction, the temperature of the melt can be measured more accurately.

Although the number of temperature sensors may be one, the temperature distribution in the crucible can be obtained more accurately by using a plurality of temperature sensors. In addition to what is fixed to the solid-liquid interface, one or more temperature sensors are provided above and one or more temperature sensors are provided below. In this method, solidification starts from the bottom of the vertical crucible, so that the lower temperature sensor can monitor the crystal temperature and the upper temperature sensor can monitor the melt temperature.
As described above, the vertical Bridgman has the disadvantage that the solid-liquid interface is not known. However, in the present invention, by providing three or more temperature sensors, the temperature distribution of the raw material melt and crystals in the vertical direction can be increased. Desired. The temperature distribution can be used as data for controlling the crucible lowering speed and the heater power.

FIG. 2 shows an example of an apparatus provided with three thermocouples. Three thermocouples 10, 13, and 14 are inserted into the thermocouple insertion tube 9. The intermediate thermocouple 10 is at the height of the solid-liquid interface 16 which is the boundary between the raw material melt 7 and the crystal 15. One thermocouple 13 is at a higher point and monitors the temperature of the melt. The other thermocouple 14 is at a lower point and monitors the temperature of the crystal.
Upper thermocouple 13, intermediate thermocouple 10, the temperature of the lower thermocouple 14 and _{T 1,} T 2, _{T 3,} respectively. T ₂ is fixed at the melting point of the raw material. T ₁ > T ₂ > T ₃ . The difference in height between the intermediate thermocouple 10 and the upper thermocouple 13 is L ₁ , and the difference in height between the intermediate thermocouple 10 and the lower thermocouple 14 is L ₂ .

In order to produce an excellent crystalline material, the solid-liquid interface of the raw material must be convex on the solid side and concave on the melt side as shown in FIG. That is, it is desirable in terms of crystallinity that the solid-liquid interface has a curved surface that is high at the center and low at the periphery. For this purpose, it compares the amount of heat Q ₂ to which flow away from heat Q _1, the solid-liquid interface downward flowing from the upper to the solid-liquid interface at the periphery of the solid-liquid interface, may Q ₁ is larger than Q _2. FIG. 4 shows the relationship of heat flow. And Q ₁ is greater than _{Q 2,} the difference _Q 3 _{= Q} 1 -Q ₂ is a heat flow toward the center of the crucible. Since there is a heat insulating material on the side, the exchange of heat in the radial direction in the crucible taking the outside becomes small, and the above Q ₃ = Q ₁ -Q ₂ is established assuming that there is almost no heat passing through the heat insulating material.

The existence of such a heat flow toward the center means that the temperature of the outer periphery of the raw crystal and the melt is higher than that of the central portion. Since the temperature is low at the bottom and high at the top, an upwardly convex isotherm is formed. For this reason, the solid-liquid interface is convex upward. As a result, crystals with good crystallinity can be obtained. Let us write the condition of Q ₁ > Q ₂ by the temperature distribution.

Define the Z-axis vertically upward. The magnitude of the upward heat flow can be expressed by -λ (δT / δz). Here, λ is the thermal conductivity. T is the temperature and z is the coordinate on the Z axis. In the case where the temperature sensors are provided at three different heights: upper (melt), middle (solid-liquid interface), and lower (crystal), the temperatures at these points can be measured.
Let L _{1 be} the distance between the upper temperature sensor and the middle (solid-liquid interface) temperature sensor, and let L ₂ be the distance between the middle temperature sensor and the lower (solid) temperature sensor. Heat flow _Q 1, _{Q 2} above, the temperature _{T 1} of the these three points (the melt), _{T 2} (the solid-liquid interface), _{T 3} can be (crystals) and by the distance expressed as follows.
The downward heat flow Q ₁ from the melt side toward the solid-liquid interface is Q ₁ = λ ₁ (T ₁ −T ₂ ) / L ₁ . Here, λ ₁ is the thermal conductivity in the melt. The downward heat flow Q ₂ flowing from the solid-liquid interface to the crystal side is Q ₂ = λ _s (T ₂ −T ₃ ) / L ₂ . λ _s is the thermal conductivity in the solid. In order to make the solid-liquid interface convex upward, Q ₁ > Q ₂ suffices. Therefore, λ ₁ (T ₁ -T ₂ ) / L ₁ > λ _s (T ₂ -T ₃ ) / L ₂ is sufficient.

  In the vertical temperature gradient furnace, the present invention surrounds the crucible with a heat insulating material and lowers or raises the whole crucible so as to keep the thermocouple held at a constant height at the melting point. As a result, the temperature distribution in the crucible can be stabilized, the solidification conditions can be kept constant, and the mixed crystal semiconductor mixed crystal ratio and the impurity concentration of the impurity doped semiconductor can be made substantially uniform in the axial direction. be able to. In mixed crystal semiconductors, the lattice constant can be changed by changing the mixed crystal ratio. Since the present invention can produce a desired mixed crystal ratio, it is extremely effective when manufacturing electronic devices using mixed crystals. Furthermore, even in the case of an andrp semiconductor, twinning can be prevented.

[Example 1]
An InGaAs mixed crystal was grown using the vertical temperature gradient furnace shown in FIG. The target mixed crystal ratio is In 97% and Ga 3%. 33.25 g of In _1-x Ga _x As (x = 0.03) synthesized in advance was vacuum-sealed in a quartz crucible 6 having an inner diameter of 12 mm. The quartz crucible 6 and the thermocouple insertion tube 9 were inserted into the heat insulating material 12, and these were fixed on the lower shaft 8. The chamber 1 was closed and a vacuum was applied, and then a current was passed through the heater to heat the crucible 6 and the raw material. The crucible was raised upward and heated to a high temperature to make the whole as a raw material melt. A thermocouple 10 is inserted into the thermocouple insertion tube 9. The crucible 6 and the lower shaft 8 are lowered at a speed of 4 mm / h. The raw material melt is solidified from below and becomes crystals. During this time, the height of the thermocouple 10 is made constant and equal to the melting point of the raw material.

In this case, the heater power is appropriately adjusted so that the temperature of the thermocouple reaches the melting point. Lower the lower shaft to solidify the whole raw material. The whole becomes a crystal.
The axial variation of the mixed crystal ratio is a problem. The reason why the vertical Bridgman is used is that a mixed crystal having a uniform composition may be formed. You have to make sure that it meets your expectations. Therefore, the crystal was cut into thin slices, and the concentration of Ga in the sample was examined. Changes in the Ga concentration in the axial direction can be known by measuring the Ga concentration of many thin pieces (wafers). The result is shown in FIG. The horizontal axis is the solidification rate g. The vertical axis represents the Ga concentration.

The solidification rate is a value obtained by dividing the weight of the crystal by the weight of the whole raw material. However, it can be said that the solidification rate here expresses the distance from the lower edge of the crystal. The point of the solidification rate g means that g is a value obtained by dividing the weight of the crystal from the bottom of the crystal to the point by the weight of the first raw material. If the crystal is completely cylindrical and all the raw material is crystal, the distance from the bottom to the measurement point is s, the crystal radius is r, the density is ρ, and the crystal length is L, g = πρr ² s / Πρr ² L = s / L.

  As shown in FIG. 5, at the beginning of crystallization, the Ga concentration has a fairly high value. However, almost the same value is maintained after the Ga concentration immediately decreases. The Ga concentration hardly fluctuates in a wide range of the solidification rate of 0.05 to 0.7. When the solidification rate exceeds 0.7, the Ga concentration decreases uniformly. This crystal has a uniform mixed crystal ratio except for the start and end portions. Since the length of the constant mixed crystal ratio is long, the productivity is high as a method for manufacturing a mixed crystal with a fixed ratio. This is the effect of the present invention that the stability of the heat distribution is increased by covering the crucible with the heat insulating material, the solid-liquid interface is convex upward, and the position of the solid-liquid interface is unchanged.

[Comparative Example 1]
The InGaAs mixed crystal was grown without controlling the height of the solid-liquid interface using the crystal growth apparatus in which the heat insulating material was removed from the vertical temperature gradient furnace of FIG. The conditions are the same as in Example 1 except that there is no heat insulating material and the solid-liquid interface is not controlled. The variation in the axial direction of the Ga concentration of the InGaAs mixed crystal grown by this method is shown in FIG. The change in the Ga concentration is remarkable, and there is almost no portion having a uniform concentration. Even if the start and end are cut off, a uniform Ga concentration crystal cannot be obtained.
Comparing the results of FIG. 5 and FIG. 6, as in the present invention, the crucible is covered with a heat insulating material to increase the temperature stability, and the crystal is moved to the low temperature side while keeping the height of the solid-liquid interface constant. It can be seen that the growth is extremely effective in obtaining a uniform mixed crystal ratio.

[Example 2]
Te-doped GaAs was grown using the vertical temperature gradient furnace shown in FIG. The apparatus shown in FIG. 2 uses three temperature sensors to set growth conditions by monitoring the temperature at three points of the crucible. The uniformity of impurity concentration is an advantage of the vertical Bridgman method. 29.96 g of GaAs and 1.2 mg of Te were put in a quartz crucible with an inner diameter of 12 mm and sealed under vacuum. This was placed in a chamber and fixed on the lower shaft. Close the chamber and pull a vacuum. Energize the heater so that the top is hot and the bottom is cold. Raise the crucible upward and heat the crucible and the raw material. The raw material of GaAs becomes a melt. After the whole becomes a melt, the lower shaft is lowered at a speed of 4 mm / h to solidify the raw material melt from below. After growing, the crystal was cut along a plane parallel to the growth direction. In other words, the crystal was cut vertically. The cut surface was polished. The polished surface was immersed in an etching solution composed of chromic acid + hydrofluoric acid. The etched surface was irradiated with light, and growth stripes were observed. The growth stripes were concave in the growth direction. This means that it is a curved surface in which the solid-liquid interface becomes convex toward the melt side during crystal growth. That is, a solid-liquid interface as shown in FIG. 3 is formed. From this result, it can be seen that according to the present invention, the shape of the solid-liquid interface can be controlled.

1 is a schematic cross-sectional view of a semiconductor growth apparatus according to a first embodiment of the present invention that covers a crucible with a heat insulating material and uses one thermocouple. The schematic sectional drawing of the semiconductor growth apparatus based on the 2nd Example of this invention which covers a crucible with a heat insulating material and uses three thermocouples. Sectional drawing which shows the shape of a desirable solid-liquid interface. Schematic explaining the relationship of the heat flow near the solid-liquid interface of a crystal | crystallization. The Ga concentration distribution in the axial direction when an InGaAs mixed crystal is grown while the position of the solid-liquid interface is maintained at a certain height using the apparatus of FIG. 1 having a thermocouple covered with a heat insulating material. The graph which shows the measured value of. The graph which shows the measured value of Ga concentration distribution of an axial direction at the time of removing a heat insulating material in the apparatus of FIG. 1, and growing the mixed crystal of InGaAs, without controlling the position of a solid-liquid interface.

Explanation of symbols

1 chamber
2 Heater
3 Heater
4 Heater
5 Heater
6 crucible
7 Raw material melt
8 Lower shaft
9 Thermocouple insertion tube
10 Thermocouple
11 Lid
12 Insulation
13 Thermocouple
14 Thermocouple
15 crystals
16 Solid-liquid interface

Claims (6)

A chamber, a plurality of heaters provided in the chamber and arranged in the vertical direction and independently controllable, a vertically long cylindrical heat insulating material surrounded by the heaters, and a raw material liquid provided inside the vertical heat insulating material for holding the raw material melt A method for growing a semiconductor crystal using a crystal growth apparatus including a vertically long crucible and a lower shaft supporting a heat insulating material crucible, wherein the semiconductor raw material is placed in the crucible and the heat insulating material crucible is obtained by a plurality of independent heaters. Heat the raw material inside and adjust the output of multiple heaters to form a temperature distribution with a temperature gradient in the axial direction so that the bottom is low temperature and the top is high temperature inside the crucible for heat insulation. The semiconductor melt is grown from the bottom by solidifying the raw material melt from below, and the temperature of the plurality of independent heaters is controlled so that the raw material melt is fed from above the solid-liquid interface. Inflow And heat to adjust the amount of heat flowing downwards, semiconductor crystal heat flowing from above the solid-liquid interface in the crystal outer circumference raw material melt and adjusting the amount of heat to be greater than the amount of heat flowing downwardly Growth method. By controlling the temperature of multiple independent heaters, the amount of heat flowing into the raw material melt from the upper part of the solid-liquid interface and the amount of heat flowing out from the lower part of the solid-liquid interface are adjusted. In the vicinity of the solid-liquid interface, the intensity of heat flowing in the direction is controlled, and the amount of heat flowing into the raw material melt from above the solid-liquid interface is larger than the amount of heat flowing out at the crystal periphery. 2. The method for growing a semiconductor crystal according to claim 1, wherein the strength of the heat flow flowing toward the center in the raw material melt and the crystal is controlled . A chamber, a plurality of heaters provided in the chamber and arranged in the vertical direction and independently controllable, a vertically long cylindrical heat insulating material surrounded by the heaters, and a raw material liquid provided inside the vertical heat insulating material for holding the raw material melt A method for growing a semiconductor crystal using a crystal growth apparatus including a vertically long crucible and a lower shaft supporting a heat insulating material crucible, wherein the semiconductor raw material is placed in the crucible and the heat insulating material crucible is obtained by a plurality of independent heaters. Heat the raw material inside and adjust the output of multiple heaters to form a temperature distribution with a temperature gradient in the axial direction so that the bottom is low temperature and the top is high temperature inside the crucible for heat insulation. The semiconductor melt is grown from the bottom by solidifying the raw material melt from below, and the temperature of the plurality of independent heaters is controlled so that the raw material melt is fed from above the solid-liquid interface. Inflow Adjusting the amount of heat and the amount of heat that flows downward, and controlling the strength of the heat flow that flows in the center direction in the raw material melt and crystal in the vicinity of the solid-liquid interface, so that the solid-liquid interface becomes convex upward A method for growing a semiconductor crystal, comprising: By controlling the temperature of multiple independent heaters, the amount of heat is adjusted so that the amount of heat flowing into the raw material melt from above the solid-liquid interface is greater than the amount of heat flowing downward at the outer periphery of the crystal. 4. The growth of a semiconductor crystal according to claim 3 , wherein the solid-liquid interface is convex upward by controlling the strength of the raw material melt and the heat flow flowing toward the center in the crystal. Method. The method for growing a semiconductor crystal according to any one of claims 1 to 4 , wherein the heat insulating material is provided so as to contact the outer periphery of the crucible. The amount of heat that flows across the insulation is small compared to the amount of heat that flows from above the raw material melt to the solid-liquid interface at the end of the solid-liquid interface near the contact portion with the insulation, and the amount of heat that flows out to the solid below. Te, of claims 1 to 5 heat flow by adjusting the amount of heat flowing from the heat and the solid-liquid interface which flows from above to the solid-liquid interface of the solid downward, characterized in that to flow towards the center in the solid portion The growth method of the semiconductor crystal in any one.

Images