Single-crystal – oriented-crystal – and epitaxy growth processes; – Processes of growth from liquid or supercritical state – Having pulling during growth
Patent
1997-02-10
1999-10-26
Hiteshew, Felisa
Single-crystal, oriented-crystal, and epitaxy growth processes;
Processes of growth from liquid or supercritical state
Having pulling during growth
117 15, 117216, 117217, 117218, 117222, C30B 1520
Patent
active
059721065
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to a device and method for producing a single crystal, in particular, a device for producing a single crystal by pulling it by the Czochralski method in which the temperature distribution and thermal history of a pulling single crystal are controlled to improve the production efficiency of single crystals and the qualities thereof, and a method for producing a single crystal by using the device.
2 . Background Art
In recent years, high- integration and high- precision of semiconductor devices are more and more advanced, and wafers of semiconductor crystals are becoming larger in diameter and higher in quality. Such semiconductor crystals are mainly produced by the Czochralski method (the pulling method), in which various efforts to produce semiconductor crystals having further large diameter and high quality are made.
For example, explaining such a case that a silicon single crystal rod is produced by the Czochralski method as shown in FIG. 4, a pulling chamber (a metal chamber) 1 is provided with a quartz crucible 3 in the middle, the quartz crucible 3 being supported by a graphite susceptor 4 which is supported at the center of the bottom by a supporting shaft 4 which is rotatable and up- and- down movable. The quartz crucible is filled with a raw material, polycrystalline silicon, which is heated and melted by a graphite heater 6 surrounded with a heat insulating cylinder 5 to give melt 7. The pulling chamber 1 has an opening part 8 in the middle of the ceiling thereof, to which a sub- chamber 9 is connected. A pulling shaft 11 which is rotatable and up-and- down movable and holds a seed 10 at the end is moved down through the sub- chamber 9, thereby the seed 10 is dipped into the melt 7, and subsequently the seed 10 is pulled with rotating the pulling shaft 11 and the quartz crucible 3, thereby a single crystal rod 12 can be grown following the end part of the seed 10. The problems arising when single crystal rods are produced by such a conventional Czochralski method are as follows: First, in pulling a crystal, a protective gas such as, for example, argon gas, is introduced from the upper part of the sub- chamber 9 and discharged from a discharge outlet 15. The gas to be introduced is extremely highly pure, but in the pulling chamber a reaction between the quartz crucible 3 and the silicon melt 7 takes place so that vapor of SiO occurs from the surface of the melt 7, the vapor of SiO being present in the upper part of the inside space of the pulling chamber 7. Most of the vapor of SiO flows downward and is discharged from the discharge outlet 15, but a part thereof is deposited as aggregate of fine powders in a form of layers or masses on such places as those having relatively low temperatures such as an inside wall 16 of the upper part of the quartz crucible 3 or an inside wall 17 of the upper part of the pulling chamber 7, when any turbulent flows 13, 14 are present in the upper part of the inside space of the chamber 7 or around the single crystal rod 12 and the surface of the melt 7. The deposited SiO falls down on the surface of the melt in pulling a single crystal and attaches to the interface of growing the crystal, which results in dislocation of the pulling single crystal rod.
Furthermore, in the pulling chamber, a reaction between carbon materials such as the graphite susceptor 2, the graphite heater 6, the heat insulating cylinder 5 (for example, made of graphite felt) and the like and the above- mentioned SiO or the quartz crucible takes place so that a CO gas occurs. When the turbulent flows 13, 14 are present in the upper part of the inside space of the pulling chamber 7 and around the single crystal rod 12 and the surface of the melt 7, the CO gas flows downward and comes into contact with the surface of the melt, which results in the increase of the concentration of carbon in a pulling single crystal silicon rod and the deterioration of the characteristics of integrated circuit devices on the wafers produced
REFERENCES:
patent: 5720810 (1998-02-01), Arai et al.
"Ways for Cleaning Wafer and Problems of Manufacturers of Semiconductors", Edt. Editorial Committee of Urgent Report of ULSI Production Technology, pp. 58-70, Dec. 20, 1993, 1.sup.st Impression of 1.sup.st Edition.
Kodama Yoshihiro
Ohta Tomohiko
Soeta Satoshi
Sonokawa Susumu
Hiteshew Felisa
Shin-Etsu Handotai & Co., Ltd.
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