JPS5913480B2 - A method for growing a single crystal of a high dissociation pressure compound for semiconductors using a double melt seal pulling method and an apparatus therefor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for growing single crystals of high dissociation pressure compounds for semiconductors such as gallium arsenide, gallium phosphide, and indium arsenide.

Conventionally, as illustrated in a schematic vertical cross-sectional view in FIG. A rotary quartz crucible 2 supported by a graphite susceptor 10, and a quartz crucible 2 fitted into the upper end of the crucible 2 containing boron oxide 5 which is heated by an after-heater 3 to become a melt. Fitted lid 4
A rotary pulling shaft 6 is inserted into the crucible 2 through the metal container 1 and has a seed crystal 12 such as gallium arsenide attached to the tip via a chuck 11. After evacuating the inside from the exhaust system 14 to create a vacuum,
The boronic oxide 5 in the fitted lid 4 is transferred to the after-heater 3.
The crucible 2 is heated by heating to form a melt.
After sealing the upper end, an inert gas such as argon is introduced from the inert gas introduction system 13 to create an inert gas atmosphere outside the crucible 2, and the gallium arsenide 8 in the crucible 2 is transferred to the main heater 7. While rotating the pulling shaft 6 in the opposite direction to the crucible 2, a seed crystal 12 attached to the tip of the pulling shaft 6 via a chuck 11 is heated to form a melt. A method and apparatus for growing a single crystal 15 by lowering the pulling shaft 6 so as to contact the crystal 8 and then pulling it up (the state shown in FIG. 1) and its apparatus (hereinafter referred to as conventional single crystal growth method) is proposed.

According to the conventional single crystal growth method, the growing single crystal 15 is not exposed to an inert gas atmosphere at high temperature by the boron oxide melt seal 5, so that arsenic is dissociated from the surface of the single crystal 150. This has the advantage that the crystallinity near the single crystal surface is not inhibited, but on the other hand, in this conventional single crystal growth method, The evaporated material mainly adheres to the inner surface of the heated wall of the quartz rotating crucible 2 as gallium arsenide,
Not only does it eventually block the view from the outside and make it impossible to observe the growing single crystal 15 being pulled, but sometimes small pieces of the deposited gallium arsenide peel off and fall directly onto the surface of the gallium arsenide melt 8, preventing the growth of the single crystal. In addition to disturbing the conditions and interfering with single crystallization, in order to minimize the flow of the boronic melt seal 50 through the rotating pulling shaft 6, the gap between the pulling shaft 6 and the quartz-inserted lid 4 is Since this is made as small as possible, it often occurs that the smooth rotation of the pulling shaft 6 and the quartz rotating crucible 2 is hindered, and each time this occurs, vibrations are caused in the rotating crucible 2. This vibration of the rotating crucible 2 is transmitted to the surface of the gallium arsenide melt 8 and adversely affects the quality and yield of the single crystal 15.
In addition, a large quartz crucible with a special shape must be used as the quartz rotary crucible 2, and since the recessed lid 4 is made of quartz, it may break during each single crystal growth. , it has to be replaced with a new one each time, leading to various problems such as an increase in manufacturing costs.

From the above-mentioned viewpoint, the present inventors aimed to solve the problems of the conventional single-crystal growth method described above, and to economically obtain a high-dissociation-pressure compound single crystal for semiconductors with good crystallinity and mass productivity. As a result of the research, we found that (a) a lower part of a rotating pulling shaft with a seed crystal attached to the tip, a quartz rotating crucible holding a high dissociation pressure compound melt to be grown into a single crystal, and the above-mentioned The upper part of the rotating shaft that rotatably supports the crucible is housed in a quartz furnace core tube, and the upper and lower ends of the furnace core tube are sealed with an oxidized boron melt, and the high dissociation pressure compound in the crucible is When the melt is coated with the boronic oxide melt (double melt seal), the volatile components in the high dissociation pressure compound melt (
For example, if the melt is gallium arsenide, only arsenic (arsenic) is selectively evaporated through the boron oxide melt coating, so that an atmosphere of the volatile components is formed in the furnace core tube. Since the single crystal is grown in an atmosphere containing the volatile components, the volatile components do not dissociate from the surface of the growing single crystal and the crystallinity near the surface of the single crystal is not inhibited. In the oxidation, the evaporation of substances other than the volatile components is significantly suppressed by the borium melt coating, so that the adhesion of substances to the inner surface of the heating wall of the furnace core tube is extremely reduced, which hinders internal observation. Even if a small amount of material attached to the inner surface of the heating wall peels off and falls, the oxidation will fall onto the boron melt coating, so the single crystal conditions will not be disturbed. (This is called the double melt seal pulling method.)

Furthermore, regarding the device, (b) By manufacturing the fitting lid for sealing the oxidized boronic liquid from molybdenum or a molybdenum alloy, the molybdenum or molybdenum alloy can be used for the oxidized boronic melt or the molybdenum alloy. Since it has excellent corrosion resistance against high-temperature volatile components, it is possible to use the fitting lid semi-permanently, and by making the fitting lid fit against the quartz furnace core tube, the fitting lid can be used for a long time. Ensure airtightness.

(C) As described above, by adopting a structure in which a rotating quartz crucible containing and holding a high dissociation pressure compound melt and a oxidized borosilicate melt for coating it is housed in a furnace core tube, the crucible can be Since the shape of the crucible can be simplified and made smaller, even if the crucible is attacked by reacting with the boron melt, it can be replaced or repaired at low cost. In addition, even if vibrations are brought to the furnace core tube, the vibrations are not transmitted to the crucible at all, and by having a structure in which the furnace core tube is installed separately on a drive stand that can be moved up and down, the lower part of the crucible is The attachment of the furnace core tube to the fitting lid can be remotely controlled.

(d) The gap between the upper and lower fitting lids and the rotary pulling shaft and rotating shaft is more than double that of the conventional one to facilitate mutual rotation between the rotating crucible and the pulling shaft, and by widening this gap, especially when pulling The sealing oxidation boron melt flowing down the shaft and rotating shaft is collected by a molybdenum or molybdenum alloy saucer provided at the lower end of the pulling shaft and the rotating shaft, and has no effect on the growing single crystal. I tried to avoid it.

Improvements have been made in the points (b) to (d) above.

The present invention has been made based on the above findings and improvements, and will be specifically explained below with reference to the drawings by way of examples.

FIG. 2 shows a schematic longitudinal sectional view of a device for implementing the invention.

As shown in FIG. 2, (1) A driving platform 19 that can move the simple and small quartz crucible 2, the lower part of the rotating pull-up shaft 6, and the upper part of the rotating shaft 9 vertically; It was stored in the furnace core tube 20 installed above.

(2) At the upper end of the furnace core tube 20, a lower fitting lid 4 made of molybdenum or a molybdenum alloy containing sealing boron oxide 5 which is heated by the upper afterheater 3 and becomes a melt is fitted. On the other hand, the furnace core tube 20
The lower end contains sealing boron oxide 22 which is heated by the lower after-heater 23 and becomes a melt, and the lower fitting lid 21 made of molybdenum or molybdenum alloy placed on the support base 18 is slid. They were mated together.

(3) The surface of the melt 8 of gallium arsenide as a high dissociation pressure compound to be grown into a single crystal is coated with the boron oxide melt 16.

(4) While the metal container 1 is being evacuated, the lower fitting lid 4, into which the rotating pulling shaft 6 is inserted, is supported above the furnace core tube 20, and during single crystal growth, the lower fitting lid 4 is supported above the furnace core tube 20. Molybdenum or molybdenum alloy saucer 17°2 for receiving and storing the sealing boron oxide melt flowing down from the lid 4 and the lower fitting lid 21 along the pulling shaft 6 and rotating shaft 9.
4 are provided on the pulling shaft 6 and rotating shaft 9 in the furnace core tube 20.

Other than the points (1) to (4) above, it is the same as the conventional example shown in FIG. , and omit duplicate explanations.

Now, 1 high-purity gallium arsenide polycrystal and a predetermined amount of boron oxide for coating are loaded into a rotating crucible 2 made of quartz with an inner diameter of 90 mm, and heated to form a melt 8, 16, and the rotating crucible is heated. 2 and the pulling shaft 6 in opposite directions, seeding was carried out according to a conventional method, and the crucible 2 was pulled up. As a result, the pulling shaft 6 and the rotating crucible 2 smoothly rotated in opposite directions. Moreover, a large-diameter gallium arsenide single crystal 15 with a diameter of 40 gm and excellent crystallinity could be manufactured by observing the inside of the furnace core tube 20 well.

Further, in the above example, when the upper and lower fitting lids 4 and 21 were made of molybdenum, no problems occurred even after repeated use 20 times or more, and semi-permanent use was possible.

Note that this also applies to the case where the upper and lower fitting lids are made of molybdenum alloy.

Furthermore, the above example shows an extremely high single crystallization rate of 90% or more, whereas the conventional example shown in FIG. 1 shows a single crystallization rate of only 30% at most. We were able to grow single crystals with an even better single crystallization rate.

Furthermore, when carrying out the present invention, it is of course possible to freely select the conditions for single crystal growth, such as the rotational speed of the pulling shaft and rotating crucible, and the rate of rise of the pulling shaft, to the highest conditions for single crystal growth. Needless to say, a dopant may be added to the high dissociation pressure compound melt, or an existing diameter control mechanism may be provided, if necessary.

As described above, according to the present invention, all the problems of conventional single crystal growth methods are solved, and in addition, it is possible to increase the diameter and length of the single crystal, shorten the manufacturing time, and improve the single crystallization rate. It is possible to produce a high dissociation pressure compound single crystal for semiconductors at a low manufacturing cost with improved mass productivity such as, and improved crystallinity such as low dislocations.

[Brief explanation of the drawing]

FIG. 1 is a schematic longitudinal cross-sectional view showing an apparatus for carrying out a conventional single crystal growth method, and FIG. 2 is a schematic longitudinal cross-sectional view showing an apparatus for carrying out a single crystal growth method according to the present invention. In the drawings, 1...Metal container, 2...Quartz rotating crucible, 3゜23...After heater, 4...
... Upper acid-filled lid, 5.22 ... Boron oxide for sealing, 6 ... Rotating lifting shaft, 7 ...
・Main heater, 8... High dissociation pressure compound, 9.
... Rotating shaft, 10 ... Graphite susceptor, 1
1... Chuck, 12... Seed crystal, 1
3... Inert gas introduction system, 14... Exhaust system, 15... Single crystal, 16... Boron oxide for coating, 17, 24 ...Saucer, 18...
...Support stand, 19...Drive stand, 20...
...Furnace core tube, 21...Lower acid filling lid.

Claims (1)

[Claims] 1. A high dissociation pressure compound melt is held in a rotating quartz crucible supported at the upper end of a rotating shaft, and a rotating pulling shaft with a seed crystal attached to the tip is placed opposite to the crucible. In a method for growing a high dissociation pressure compound single crystal by pulling it while rotating it in a direction, the lower part of the pulling shaft, the crucible, and the upper part of the rotating shaft are housed in a quartz furnace core tube, and The upper and lower ends of the furnace core tube are sealed with a boron oxide melt, and the high dissociation pressure compound melt in the crucible is coated with a boron melt, and the high dissociation pressure compound melt in the crucible is coated with a boron oxide melt. A double melting method characterized by growing a high dissociation pressure compound single crystal in an atmosphere composed of the volatile components by selectively evaporating only the volatile components through the boron oxide melt coating. A method for growing single crystals of high dissociation pressure compounds for semiconductors using the liquid seal pulling method. 2 A high dissociation pressure compound melt is held in a rotating quartz crucible supported at the upper end of the rotating shaft, and the rotating pulling shaft with a seed crystal attached to the tip is pulled while rotating in the opposite direction to the crucible. In an apparatus for growing a single crystal of a high dissociation pressure compound by lifting, a quartz furnace core tube housing a lower part of the pulling shaft, the crucible, and an upper part of the rotating shaft is mounted on a drive stand that can be moved vertically. At the same time, upper and lower fitting lids made of molybdenum or molybdenum alloy are provided at the upper and lower ends of the furnace core tube to hold the borosilicate oxide melt for sealing, respectively. The pulling shaft and the rotating shaft are provided with a saucer for collecting the sealing oxidized boron melt flowing down from the upper and lower fitting lids along the pulling shaft and the rotating shaft. A device for growing single crystals of high dissociation pressure compounds for semiconductors using a double melt seal pulling method.