Sumco Corporation

Shuichi Inami

Ken Hamada

Tsuyoshi Nakamura

Nobumitsu Takase

Yasuhiro Kogure

Hiroki Murakami

Hiroaki Taguchi

Takashi Atami

Takuya Yotsui

Manabu Moroishi

Nobuhiro Kusaba

Tsuguya Fukagawa

A single crystal pulling apparatus comprises: a chamber; a crucible disposed within the chamber for containing a melt; a water-cooling means disposed within the chamber in such a manner as surrounding a single crystal pulled up from the melt in the crucible; water piping for feeding cooling water to and discharging the same from the water-cooling means; and supporting arms connected to the chamber for supporting the water-cooling means, wherein the supporting arms are disposed between the single crystal and the water piping. According to this configuration, the supporting arms can prevent the water piping from being damaged in the event of fall and collapse of the single crystal due to failure of the seed neck portion or in the event of rupture of the single crystal due to thermal stress, for instance.

Single crystal pulling apparatus

A whole determination area of a targeted wafer is concentrically divided in a radial direction, COP density is obtained in each divided determination segment, a maximum value of the COP density is set as COP density, a minimum value of the COP density is set as COP density, a value computed by '(COP density&#x2212;COP density/COP density' is compared to a predetermined set value, and a non-crystal-induced COP and a crystal-induced COP are distinguished from each other based on a clear criterion, thereby determining the COP generation factor. Therefore, a rejected wafer in which a determination of the crystal-induced COP is made despite being the non-crystal-induced COP can be relieved, so that a wafer production yield can be enhanced.

Method for determining COP generation factors for single-crystal silicon wafer

A whole determination area of a targeted wafer is concentrically divided in a radial direction, COP density is obtained in each divided determination segment, a maximum value of the COP density is set as COP density, a minimum value of the COP density is set as COP density, a value computed by '(COP density-COP density)/COP density' is compared to a predetermined set value, and a non-crystal-induced COP and a crystal-induced COP are distinguished from each other based on a clear criterion, thereby determining the COP generation factor. Therefore, a rejected wafer in which a determination of the crystal-induced COP is made despite being the non-crystal-induced COP can be relieved, so that a wafer production yield can be enhanced.

A whole determination area of a targeted wafer is concentrically divided in a radial direction, COP density is obtained in each divided determination segment, a maximum value of the COP density is set as COP density, a minimum value of the COP density is set as COP density, a value computed by '(COP density&#x2212;COP density)/COP density' is compared to a predetermined set value, and a non-crystal-induced COP and a crystal-induced COP are distinguished from each other based on a clear criterion, thereby determining the COP generation factor. Therefore, a rejected wafer in which a determination of the crystal-induced COP is made despite being the non-crystal-induced COP can be relieved, so that a wafer production yield can be enhanced.

An evaluation area of an evaluation object wafer is concentrically divided in a radial direction, an upper limit value to the number of COPs is set in each divided evaluation segment, and an acceptance determination of the single-crystal silicon wafer is made using the upper limit value as a criterion. Thereby, a quantitative and objective COP evaluation can be made, and a proper determination is made based on a clear criterion. The evaluation method of the present invention can sufficiently deal with automation of the COP evaluation (inspection) and the higher-quality wafer in the near future, and the evaluation method can be widely applied to production of the single-crystal silicon wafer and production of a semiconductor device.

Method for making COP evaluation on single-crystal silicon wafer

In a method for growing a silicon single crystal, a silicon single crystal is grown by the Czochralski method to have an oxygen concentration of 12&#xd7;10to 18&#xd7;10atoms/cmon ASTM-F121 1979. A mixed gas of an inert gas and a gaseous substance containing hydrogen atoms is used as an atmospheric gas for growing the single crystal. A temperature of the silicon single crystal is controlled during the growth of the crystal such that the ratio Gc/Ge of an axial thermal gradient Gc at the central portion of the crystal between its melting point and its temperature of 1350&#xb0; C. to an axial thermal gradient Ge at the periphery of the crystal between its melting point and its temperature of 1350&#xb0; C. is 1.1 to 1.4. The axial thermal gradient Gc at the central portion of the crystal is 3.0 to 3.5&#xb0; C./mm.

Method for growing silicon single crystal and method for manufacturing silicon wafer

A method of growing silicon single crystals with a [110] crystallographic axis orientation by the Czochralski method is provided according to which a silicon seed crystal doped with a high concentration of boron is used and an included angle of a conical part during shoulder section formation is maintained within a specified range. It is thereby possible to grow large-diameter and heavy-weight dislocation-free silicon single crystals with a diameter of 300 mm or more in a stable manner, without the fear of dropping the single crystal during pulling up. Therefore, the method can be properly utilized in producing silicon single crystals as semiconductor materials.

Method for producing silicon single crystal

A silicon single crystal is grown using the Czochralski method. During the crystal growth, a thermal stress is applied to at least a portion of the silicon single crystal. A gaseous substance containing hydrogen atoms is used as an atmospheric gas for growing the crystal.

Method for growing silicon single crystal

This method for producing silicon single crystals includes: growing a silicon single crystal by the Czochralski method while cooling at least part of the silicon single crystal under growth with a cooling member which circumferentially surrounds the silicon single crystal and has an inner contour that is coaxial with a pull axis, wherein an ambient gas in which the silicon single crystal is grown includes a hydrogen-atom-containing substance in gaseous form. This silicon single crystal is produced by the above method.

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Tokyo, Japan

Shuichi Inami