JPH04130086A - Method and apparatus for production of high dissociation pressure single crystal - Google Patents

Abstract

PURPOSE:To produce the compd. semiconductor single crystal having a low dislocation density and good quality at a good yield by maintaining the B2O3 liquid sealants in a hermetic vessel which is filled with gaseous high-dissociation pressure component elements and pulls up a single crystal from a raw material melt to a specific temp. CONSTITUTION:The gases formed by heating and evaporating high-dissociation pressure component elements 13, such as AS and P, housed in an ampoule 12 by a heater are filled into the hermetic vessel 2 disposed in a high-pressure chamber 1. The raw material melt 16 and the liquid sealant 17 heated and melted by a heater 19 are housed into a crucible 15 in a susceptor 14 rotationally supported by a lower shaft 4 in this hermetic vessel 2. While a single crystal 26 is grown via the seed crystal 18 mounted to the bottom end of the upper shaft 3, the single crystal is pulled up under rotation. The B2O3 liquid sealants 7, 8 in liquid pools 5, 6 are interposed in the spacings of the parts where the above-mentioned upper and lower shafts 3, 4 penetrate the hermetic vessel 2 and the temp. thereof is kept up to above 700 to 1100 deg.C by heaters 9, 10. The drop of the partial pressure of the above-mentioned gases is averted and the good-quality single crystal is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention is a method for producing Ga
The present invention relates to a method and apparatus for manufacturing m-v group compound semiconductors such as AsGaP, InAs, and InP.

(Prior art) A method for producing a compound semiconductor single crystal by the Czochralski method or the liquid-sealed Czochralski method in an airtight container filled with a high dissociation pressure component gas is to Since decomposition reactions can be suppressed, it has become possible to grow crystals under extremely small temperature gradients. As a result, it has become possible to obtain single crystals with low dislocation density.

FIGS. 1 and 2 are cross-sectional views of a conventional liquid-sealed Czochralski implant. In the apparatus shown in FIG. 1, an airtight container 2 is provided in a high-pressure chamber 1, a liquid reservoir 6 is provided at a portion where a lower shaft 4 that supports a susceptor 14 of a crucible 15 passes through the airtight container 2, and a liquid sealant 8 is provided. The liquid sealant 8 is heated and melted by the heater 10 to form a seed crystal 1.
A liquid reservoir 5 is provided at the part where the two shafts 3 and the airtight container 2 pass through, and a liquid sealant 7 is accommodated therein.
It is heated and melted to form a hole. And airtight container 2
In this case, the ampoule 12 is communicated through the conduit 11, and the high dissociation pressure component element 13 in the ampoule 12 is heated and evaporated by the heater 25, so that the airtight container 2 is filled with the component element gas.

Next, to explain the procedure of crystal growth, high pressure chamber]
is evacuated, an inert gas such as nitrogen or argon is introduced, and the heaters 9 and 10 are heated to heat and melt the liquid sealants 7 and 8 in the liquid reservoirs on the upper and lower axes, thereby sealing the airtight container 2. do. The heater 25 is heated to evaporate the high dissociation pressure component element 13 to maintain a predetermined partial pressure in the airtight container 2 and to balance the pressure inside and outside the airtight container 2. Increase gas pressure. Thereafter, the heaters 19 and 20 are heated to release the raw material 16 and the liquid sealant 17.
After stabilizing the temperature of the raw material melt 16 while rotating the crucible 15, lower the shaft 3, immerse the seed crystal 18 at its tip in the raw material melt I6, and lower the upper shaft while rotating. 3, a single crystal 26 is grown.

The device shown in FIG. 2 is a modification of the device shown in FIG. 1, in which the airtight container is divided into an upper part 21 and a lower part 22 to facilitate the introduction of raw materials and the recovery of burnt single crystals. The lower part 22 of the airtight container is used as a susceptor containing the crucible 15, and an annular groove 23 is provided around the upper end to contain the liquid sealant 2.
4, and the lower end of the upper part 21 of the airtight container is immersed in the liquid).1+h agent 24 to ensure airtightness. The rest of the structure is the same as that of the apparatus shown in FIG. 1, and the crystal growth procedure is also the same, so a description thereof will be omitted.

(Problems to be Solved by the Invention) In the above device, generally speaking, the higher the temperature of the liquid sealant in the sealing portion, the lower the viscosity of the liquid sealant;
It was thought that this was a good idea because it allowed smooth rotation of the two lower shafts, etc. When crystal growth is performed under a gentle temperature gradient using this type of equipment, the temperature of the liquid sealant in the 7th part tends to rise, especially in the equipment shown in Figure 2. When a liquid sealant medium is provided around the crucible, it is structurally unavoidable that the temperature of the liquid sealant increases.

However, during crystal growth using the above-mentioned apparatus, the present inventor discovered that due to deterioration of the seed crystal, the crystal may fall during the growth, or the surface of the growing crystal may deteriorate, resulting in high dissociation in the airtight container. I noticed a decrease in the partial pressure of the pressure component element gas.

Therefore, the present invention avoids a drop in the partial pressure of a high dissociation pressure component gas in an airtight container, prevents deterioration of a seed crystal and a grown crystal, and produces a high-quality compound semiconductor single crystal with a low dislocation density at a high yield. The purpose of this paper is to provide a method and device that can achieve this goal.

(Means for Solving the Problems) The present invention provides a high dissociation pressure in a sealed airtight container by interposing a B2O3 liquid sealant in the gap between the connection part of the airtight container and the part where the shaft penetrates the airtight container. In a method for manufacturing a compound semiconductor single crystal, in which a single crystal is pulled from a raw material melt in a crucible filled with component gas and supported by a lower axis using an upper axis, agent,
A method for manufacturing a compound semiconductor single crystal, characterized in that the single crystal is pulled by holding it at a temperature exceeding 700°C and not more than 1100°C, and an apparatus used in the above manufacturing method, wherein an airtight container is provided. This is a compound semiconductor single crystal manufacturing apparatus characterized in that a connecting portion of the crucible is provided at a position away from a crucible.

Note that arsenic or phosphorus gas can be used as the high dissociation pressure component element gas.

(Function) The present inventor investigated the cause of the decrease in the partial pressure of the high dissociation pressure component elemental gas in the liquid-sealed Czochralski apparatus described above, and found that the path through which the gas escapes from the airtight container is: When the pressure inside the high-pressure chamber becomes higher than the pressure inside the high-pressure chamber, the liquid sealant in the chamber becomes bubbles and is released to the outside. There are two cases in which it is diffused and released to the outside.

On the other hand, as mentioned above, when increasing the temperature of the agent on the liquid side to lower the viscosity in order to smooth the rotation of the lower shaft, bubbles are likely to form in the liquid sealant ( In addition, the high dissociation pressure component gas easily dissolves into the liquid sealant.

Therefore, through repeated experiments using a B2O3 liquid sealant, the inventor investigated the relationship between the temperature of the B2O3 liquid sealant and the release of the high dissociation pressure component element gas. When the temperature of the sealant exceeds 1100°C, leakage becomes noticeable, and it becomes difficult to maintain the partial pressure of the high dissociation pressure component gas in the airtight container, resulting in deviations in the composition of the raw material melt, seed crystals, and pulling. If the temperature is lower than 700℃, the rotation of the vertical axis will not be smooth, and especially if vibration occurs in the upper axis, the noise of the load cell connected to the upper axis will become louder. It has been found that this makes it difficult to accurately measure the weight of the pulled crystal, making it impossible to accurately control the crystal diameter, and causing crystal defects.

That is, the B2O3 liquid sealant with rotating parts is rotated at 700°.
By maintaining the temperature above C and below 1100℃, it prevents the escape of high dissociation pressure component gas from the airtight container, guarantees crystal growth with smooth rotation, and produces high-quality products with low dislocation density. This made it possible to manufacture compound semiconductor single crystals with high yield.

FIG. 3 shows an improved version of the apparatus shown in FIG. 2 in order to easily carry out the above manufacturing method, and the connecting portion between the upper part 21 of the airtight container and the lower part 22 of the airtight container, which also serves as a susceptor for the crucible 15, is optimized. The feature is that it is provided at the upper part and separated from the high-temperature raw material melt 16.

Note that the other device configurations are the same as the device shown in FIG. 2, so explanations will be omitted.

(Example) A GaAs single crystal was grown using the apparatus shown in FIG.

40 kg of GaAs polycrystalline raw material and 500 g of BtOs as a liquid sealant were stored in a P311 crucible with a diameter of 6 inches, and liquid sealant B2 was placed in the liquid reservoir provided in the part where the vertical axis penetrated.
O3 is added to A as a raw material for supplying high dissociation pressure component element gas.
s500g was placed in an ampoule.

First, the inside of the high-pressure chamber is evacuated, and the liquid sealant in the liquid reservoir penetrated by the upper and lower shafts is heated to 95~J
After heating the ampoule to 000°C and completely sealing the airtight container, the ampoule was heated to about 617°C and the partial pressure of As in the airtight container was adjusted to about 1 atm. 15
Nitrogen gas was added to achieve atmospheric pressure. Then, the temperature gradient of the raw material melt was adjusted to 10℃/1m1 using a heater around the airtight container.
1, and crystal growth was performed with the rotation speed of the crucible at 5 rpm, the rotation speed of the upper shaft at 3 rpm, and the pulling speed at 6 mm/hr. As a result, a GaAs single crystal with a diameter of about 8511I11 and a length of about 150 mm was grown. I was able to do that. After the growth, the weight of the grown crystal and the remaining raw material was measured and compared with the raw material used to measure the raw material loss, and it was confirmed that it was only Ig, and there was almost no deviation in the raw material composition. Further, no deterioration was observed on the surfaces of the seed crystal and the grown crystal. When the grown crystal was cut out perpendicularly to the growth axis and the dislocation density was measured, the dislocation density did not become high near the outer periphery of the crystal, and was extremely good at 2000 c+s-'' on average for 3 inches.

Among the above growth conditions, only the temperature of the liquid sealant in the liquid reservoir penetrated by the upper and lower axes was changed to 1150°C, and GaAs was grown in the same way.
When a single crystal was grown, there was a raw material loss of 40 g, and deterioration was observed on the seed crystal and the surface of the grown crystal.

Further, when the dislocation density was measured in the same manner as above, it was found that the dislocation density near the outer periphery of the crystal was as high as 50,000 cm-'', and the overall average was as high as 100,100 O''.

(Effects of the Invention) By adopting the above configuration, the present invention can prevent the escape of high dissociation pressure component element gas from the airtight container, and can sufficiently ensure the partial pressure of the gas. It has now become possible to produce high-quality, high-dissociation-pressure single crystals with low dislocation density and high yield without deteriorating the surfaces of the seed crystal and growing crystal.

[Brief explanation of the drawing]

Claims (3)

[Claims] (1) By interposing B_2O_3 liquid sealant in the gap between the connection part of the airtight container and the part where the shaft penetrates the airtight container, the airtight container is filled with high dissociation pressure component element gas and supported by the lower shaft. In a method for producing a compound semiconductor single crystal, in which a single crystal is pulled from a raw material melt in a crucible using an upper axis, the liquid sealant for sealing is maintained at a temperature exceeding 700 °C and below 1100 °C. A method for producing a compound semiconductor single crystal, characterized by pulling the single crystal. (2) The method for manufacturing a compound semiconductor single crystal according to claim (1), characterized in that arsenic or phosphorus gas is used as the high dissociation pressure component element gas. (3) In the apparatus used in the method for manufacturing a compound semiconductor single crystal according to claim (1) or (2), the compound semiconductor single crystal is characterized in that the connecting portion of the airtight container is provided at a position away from the crucible. manufacturing equipment.