Patents by Inventor Souroku Kawanishi
Souroku Kawanishi has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 6579363Abstract: By using a semiconductor single crystal pulling apparatus for growing single crystals by the Czochralski method while rotating the melt by a magnetic field and electric current, namely by the EMCZ method, which comprises a main pulling means for pulling a single crystal, a holding mechanism for gripping an engaging stepped portion formed on the single crystal through engaging members and a sub pulling means for moving the holding mechanism up and down and in which an electric current is passed through the main pulling means and through the sub pulling means, it is possible to prevent heavy single crystals from undergoing a falling accident and, at the same time, effectively reduce the power consumption. In this pulling apparatus, it is effective to feed an electric current to the sub pulling means alone and it is desirable to dispose two or more electrodes whether the pulling means is of a shaft type or wire type.Type: GrantFiled: October 17, 2001Date of Patent: June 17, 2003Assignees: Sumitomo Metal Industries, Ltd., NEC CorporationInventors: Souroku Kawanishi, Masahito Watanabe, Minoru Eguchi
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Publication number: 20020073919Abstract: By using a semiconductor single crystal pulling apparatus for growing single crystals by the Czochralski method while rotating the melt by a magnetic field and electric current, namely by the EMCZ method, which comprises a main pulling means for pulling a single crystal, a holding mechanism for gripping an engaging stepped portion formed on the single crystal through engaging members and a sub pulling means for moving the holding mechanism up and down and in which an electric current is passed through the main pulling means and through the sub pulling means, it is possible to prevent heavy single crystals from undergoing a falling accident and, at the same time, effectively reduce the power consumption. In this pulling apparatus, it is effective to feed an electric current to the sub pulling means alone and it is desirable to dispose two or more electrodes whether the pulling means is of a shaft type or wire type.Type: ApplicationFiled: October 17, 2001Publication date: June 20, 2002Inventors: Souroku Kawanishi, Masahito Watanabe, Minoru Eguchi
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Patent number: 6113688Abstract: A method of growing a single crystal, comprises pulling a single crystal from molten material in a crucible by the Czochralski method; simultaneously applying an axially symmetric, radial cusp magnetic field to the molten material; and simultaneously heating the crucible from both the bottom and the sides; where a ratio of the heating from the bottom of the crucible, q, to the total heating of the crucible, Q, is q/Q, and during the pulling the ratio q/Q changes. The concentration of oxygen in the pulling direction of the crystal may be accurately controlled, and is uniform.Type: GrantFiled: October 1, 1998Date of Patent: September 5, 2000Assignee: Sumitomo Metal Industries, Ltd.Inventors: Souroku Kawanishi, Makoto Itou
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Patent number: 6086671Abstract: A method for melting a silicon starting material can suppress silica (SiO2) from melting out from a quartz crucible wherein the silicon starting material is melted and can provide a high-quality silicon single crystal in a high yield. The growth method comprises melting the silicon starting material charged in the crucible while applying thereto a static magnetic field, contacting a seed crystal to a surface of the silicon melt, and pulling the seed crystal upwardly to solidify the contacted melt. The silicon starting material charged in the crucible, which is under melting, is applied with a static magnetic field such as a Cusp magnetic field, a horizontal magnetic field and/or a vertical magnetic field. The application can control heat convection occurring in the crucible during the course of the melting of the starting material, thereby obtaining a silicon single crystal having a reduced number of dislocation defects.Type: GrantFiled: September 1, 1998Date of Patent: July 11, 2000Assignee: Sumitomo Sitix CorporationInventors: Souroku Kawanishi, Youichi Yamamoto
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Patent number: 5704974Abstract: When a Si single crystal 8 is pulled up from a melt 6 received in a crucible 2, the state of eddy flows generated in the melt 6 is judged from the temperature distribution of the melt at the surface. According to the result of judgement, the gas, i.e. N.sub.2, Xe or Kr, which causes extraoridnary deviation in the density of a melt 6 is added to an atmospheric gas, so as to keep the eddy flows under unstabilized condition. The effect of said gas is typical in the case of crystal growth from the melt to which a dopant such as Ca, Sb, Al, As or In having the effect to suppress the extraordinary deviation in the density is added. Since the single crystal is pulled up from the melt held in the temperature-controlled condition at the surface, impurity distribution and oxygen distribution are made uniform along the direction of crystal growth. A single crystal obtained in this way has highly-stabilized quality.Type: GrantFiled: March 22, 1996Date of Patent: January 6, 1998Assignees: Research Development Corporation of Japan, Sumitomo Sitix Corporation, Toshiba Ceramics Co., Ltd., Nippon Steel Corporation, Komatsu Electronic Metals Co., Ltd., Mitsubishi Materials CorporationInventors: Koji Izunome, Souroku Kawanishi, Shinji Togawa, Atsushi Ikari, Hitoshi Sasaki, Shigeyuki Kimura
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Patent number: 5700320Abstract: When a B or P-doped Si single crystal is pulled up from a B or P-doped melt by the Czochralski method, an element such as Ga, Sb or In having the effect to reduce the heat expansion coefficient of said melt at a temperature near the melting point is added to said melt. The additive element stabilizes the temperature condition of crystal growth so as to control the generation of eddy flows just below the interface of crystal growth.When a Ga or Sb-doped Si single crystal is pulled up from a Ga or Sb-doped melt, an element such as B or P having the effect to increase the heat expansion coefficient of said melt at a temperature near the melting point is added. The agitation of the melt just below the interface of crystal growth is accelerated by the addition of B or P, so as to assure the growth of a Si single crystal from the melt having impurity distribution made uniform along the radial direction.Type: GrantFiled: March 22, 1996Date of Patent: December 23, 1997Assignees: Research Development Corporation of Japan, Sumitomo Sitix Corporation, Toshiba Ceramics Co., Ltd., Nippon Steel Corporation, Komatsu Electronic Metals Co., Ltd., Mitsubishi Materials CorporationInventors: Koji Izunome, Souroku Kawanishi, Shinji Togawa, Atsushi Ikari, Hitoshi Sasaki, Shigeyuki Kimura
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Patent number: 5683504Abstract: When a single crystal is pulled up from a melt, the difference .DELTA.T between temperatures at the bottom of a crucible and at the interface of crystal growth is controlled so as to hold the Rayleigh constant defined by the formula of:R a=g.multidot..beta..multidot..DELTA.T.multidot.L/.kappa..multidot..nu.within the range of 5.times.10.sup.5 -4.times.10.sup.7, wherein g represents the acceleration of gravity, .beta. the volumetric expansion coefficient of the melt, L the depth of the melt, .kappa. thermal diffusivity and .nu. the kinematic viscocity. Since the convection mode of the melt at the interface of crystal growth is constantly held in the region of soft turbulence, a single crystal is grown under the stabilized temperature condition without the transfer of the impurity distribution in the melt into the growing single crystal.Type: GrantFiled: March 22, 1996Date of Patent: November 4, 1997Assignees: Research Development Corporation of Japan, Sumitomo Sitix Corporation, Toshiba Ceramics Co., Ltd., Nippon Steel Corporation, Komatsu Electronic Metals Co., Ltd., Mitsubishi Materials CorporationInventors: Koji Izunome, Souroku Kawanishi, Shinji Togawa, Atsushi Ikari, Hitoshi Sasaki, Shigeyuki Kimura