Patents by Inventor Shozo Muraoka

Shozo Muraoka 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).

  • Patent number: 6364947
    Abstract: In method for manufacturing a silicon single crystal in accordance with a Czochralski method, during the growth of the silicon single crystal, pulling is performed such that a solid-liquid interface in the crystal, excluding a peripheral 5 mm-width portion, exists within a range of an average vertical position of the solid-liquid interface ±5 mm. There is also disclosed a method for manufacturing a silicon single crystal in accordance with the Czochralski method, wherein during the growth of a silicon single crystal, a furnace temperature is controlled such that a temperature gradient difference &Dgr;G (=Ge−Gc) is not greater than 5° C./cm, where Ge is a temperature gradient (° C./cm) at a peripheral portion of the crystal, and Gc is a temperature gradient (° C./cm) at a central portion of the crystal, both in an in-crystal descending temperature zone between 1420° C. and 1350° C. or between a melting point of silicon and 1400° C.
    Type: Grant
    Filed: September 14, 2000
    Date of Patent: April 2, 2002
    Assignee: Shin-Etsu Handotai Co., Ltd.
    Inventors: Makoto Iida, Eiichi Iino, Masanori Kimura, Shozo Muraoka, Hideki Yamanaka
  • Patent number: 6348180
    Abstract: A method for producing a silicon single crystal in accordance with the Czochralski method. The single crystal is grown in an N2(V) region where a large amount of precipitated oxygen and which is located within an N region located outside an OSF ring region, or is grown in a region including the OSF ring region, N1(V) and N2(V) regions located inside and outside the OSF ring region, in a defect distribution chart which shows a defect distribution in which the horizontal axis represents a radial distance D (mm) from the center of the crystal and the vertical axis represents a value of F/G (mm2/° C.·min), where F is a pulling rate (mm/min) of the single crystal, and G is an average intra-crystal temperature gradient (° C./mm) along the pulling direction within a temperature range of the melting point of silicon to 1400° C.
    Type: Grant
    Filed: January 26, 2000
    Date of Patent: February 19, 2002
    Assignee: Shin-Etsu Handotai Co., Ltd.
    Inventors: Makoto Iida, Satoshi Suzuki, Eiichi Iino, Masanori Kimura, Shozo Muraoka
  • Patent number: 6334896
    Abstract: A method for producing a silicon single crystal, wherein, when a silicon single crystal is grown by the Czochralski method, the crystal is pulled with such conditions as present in a region defined by a boundary between a V-rich region and an N-region and a boundary between an N-region and an I-rich region in a defect distribution chart showing defect distribution which is plotted with D [mm] as abscissa and F/G [mm2/° C.·min] as ordinate, wherein D represents a distance between center of the crystal and periphery of the crystal, F/G [mm/min] represents a pulling rate and G [° C./mm] represents an average temperature gradient along the crystal pulling axis direction in the temperature range of from the melting point of silicon to 1400° C., and time required for crystal temperature to pass through the temperature region of from 900° C. to 600° C.
    Type: Grant
    Filed: July 11, 2000
    Date of Patent: January 1, 2002
    Assignee: Shin-Etsu Handotai Co., Ltd.
    Inventors: Makoto Iida, Masanori Kimura, Shozo Muraoka
  • Patent number: 6261361
    Abstract: There is disclosed a method for producing a silicon single crystal wafer wherein a silicon single crystal is grown in accordance with the CZ method with doping nitrogen in an N-region in a defect distribution chart which shows a defect distribution in which the horizontal axis represents a radial distance D (mm) from the center of the crystal and the vertical axis represent a value of F/G (mm2/° C.·min), where F is a pulling rate (mm/min) of the single crystal, and G is an average intra-crystal temperature gradient(° C./mm) along the pulling direction within a temperature range of the melting point of silicon to 1400° C. There can be provided a method of producing a silicon single crystal wafer consisting of N-region where neither V-rich region nor I-rich region is present in the entire surface of the crystal by CZ method, under the condition that can be controlled easily in a wide range, in high yield, and in high productivity.
    Type: Grant
    Filed: May 19, 2000
    Date of Patent: July 17, 2001
    Assignee: Shin-Etsu Handotai Co., Ltd.
    Inventors: Makoto Iida, Masaro Tamatsuka, Masanori Kimura, Shozo Muraoka
  • Patent number: 6197109
    Abstract: There is disclosed a method for producing a silicon single crystal by growing the silicon single crystal by the Czochralski method, characterized in that the crystal is pulled at a pulling rate [mm/min] within a range of from V1 to V1+0.062×G while the crystal is doped with nitrogen during the growing, where G [K/mm] represents an average temperature gradient along the crystal growing direction, which is for a temperature range of from the melting point of silicon to 1400° C., and provided in an apparatus used for the crystal growing, and V1 [mm/min] represents a pulling rate at which an OSF ring disappears at the center of the crystal when the crystal is pulled by gradually decreasing the pulling rate.
    Type: Grant
    Filed: June 10, 1999
    Date of Patent: March 6, 2001
    Assignee: Shin-Etsu Handotai Co., Ltd.
    Inventors: Makoto Iida, Masaro Tamatsuka, Wataru Kusaki, Masanori Kimura, Shozo Muraoka
  • Patent number: 6159438
    Abstract: In method for manufacturing a silicon single crystal in accordance with a Czochralski method, during the growth of the silicon single crystal, pulling is performed such that a solid-liquid interface in the crystal, excluding a peripheral 5 mm-width portion, exists within a range of an average vertical position of the solid-liquid interface.+-. 5 mm. There is also disclosed a method for manufacturing a silicon single crystal in accordance with the Czochralski method, wherein during the growth of a silicon single crystal, a furnace temperature is controlled such that a temperature gradient difference .DELTA.G (=Ge-Gc) is not greater than 5.degree. C./cm, where Ge is a temperature gradient (.degree. C./cm) at a peripheral portion of the crystal, and Gc is a temperature gradient (.degree. C./cm) at a central portion of the crystal, both in an in-crystal descending temperature zone between 1420.degree. C. and 1350.degree. C. or between a melting point of silicon and 1400.degree. C.
    Type: Grant
    Filed: July 22, 1999
    Date of Patent: December 12, 2000
    Assignee: Shin-Etsu Handotai Co., Ltd.
    Inventors: Makoto Iida, Eiichi Iino, Masanori Kimura, Shozo Muraoka, Hideki Yamanaka
  • Patent number: 6120598
    Abstract: A single crystal is grown in accordance with a Czochralski method such that the time for passing through a temperature zone of 1150-1080.degree. C. is 20 minutes or less, or such that the length of a portion of the single crystal corresponding to the temperature zone of 1150-1080.degree. C. in the temperature distribution is 2.0 cm or less. Alternatively, the single crystal is grown such that the time for passing through a temperature zone of 1250-1200.degree. C. is 20 minutes or less, or such that the length of a portion of the single crystal corresponding to the temperature zone of 1250-1200.degree. C. in the temperature distribution is 2.0 cm or less. This method decreases both the density and size of so-called grown-in defects such as FPD (100 defects/cm.sup.2 or less), LSTD, and COP (10 defects/cm.sup.2 or less) to thereby enable efficient production of a single crystal having an excellent good chip yield (80% or greater) in terms of oxide dielectric breakdown voltage characteristics.
    Type: Grant
    Filed: December 13, 1999
    Date of Patent: September 19, 2000
    Assignee: Shin-Etsu Handotai Co., Ltd.
    Inventors: Makoto Iida, Eiichi Iino, Masanori Kimura, Shozo Muraoka
  • Patent number: 6120599
    Abstract: In a method for producing a silicon single crystal wafer, a silicon single crystal is grown in accordance with the Czochralski method such that the F/G value becomes 0.112-0.142 mm.sup.2 /.degree. C..multidot.min at the center of the crystal, where F is a pulling rate (mm/min) of the single crystal, and G is an average intra-crystal temperature gradient (.degree. C./mm) along the pulling direction within a temperature range of the melting point of silicon to 1400.degree. C. Additionally, the single crystal is pulled such that the interstitial oxygen concentration becomes less than 24 ppma, or the time required to pass through a temperature zone of 1050-850.degree. C. within the crystal is controlled to become 140 minutes or less. The method allows production of silicon single crystal wafers in which neither FPDs nor L/D defects exist on the wafer surface, which therefore has an extremely low defect density, and whose entire surface is usable.
    Type: Grant
    Filed: December 6, 1999
    Date of Patent: September 19, 2000
    Assignee: Shin-Etsu Handotai Co., Ltd.
    Inventors: Makoto Iida, Eiichi Iino, Masanori Kimura, Shozo Muraoka
  • Patent number: 6077343
    Abstract: There is disclosed a method for producing a silicon single crystal wafer wherein a silicon single crystal is grown in accordance with the CZ method with doping nitrogen in an N-region in a defect distribution chart which shows a defect distribution in which the horizontal axis represents a radial distance D (mm) from the center of the crystal and the vertical axis represent a value of F/G (mm.sup.2 /.degree. C..multidot.min), where F is a pulling rate (mm/min) of the single crystal, and G is an average intra-crystal temperature gradient (.degree. C./mm) along the pulling direction within a temperature range of the melting point of silicon to 1400.degree. C. There can be provided a method of producing a silicon single crystal wafer consisting of N-region where neither V-rich region nor I-rich region is present in the entire surface of the crystal by CZ method, under the condition that can be controlled easily in a wide range, in high yield, and in high productivity.
    Type: Grant
    Filed: May 25, 1999
    Date of Patent: June 20, 2000
    Assignee: Shin-Etsu Handotai Co., Ltd.
    Inventors: Makoto Iida, Masaro Tamatsuka, Masanori Kimura, Shozo Muraoka
  • Patent number: 6066306
    Abstract: In a method for producing a silicon single crystal wafer, a silicon single crystal is grown in accordance with the Czochralski method such that the F/G value becomes 0.112-0.142 mm.sup.2 /.degree.C.multidot.min at the center of the crystal, where F is a pulling rate (mm/min) of the single crystal, and G is an average intra-crystal temperature gradient (.degree.C/mm) along the pulling direction within a temperature range of the melting point of silicon to 1400.degree. C. Additionally, the single crystal is pulled such that the interstitial oxygen concentration becomes less than 24 ppma , or the time required to pass through a temperature zone of 1050-850.degree. C. within the crystal is controlled to become 140 minutes or less. The method allows production of silicon single crystal wafers in which neither FPDs nor L/D defects exist on the wafer surface, which therefore has an extremely low defect density, and whose entire surface is usable.
    Type: Grant
    Filed: November 9, 1998
    Date of Patent: May 23, 2000
    Assignee: Shin-Etsu Handotai Co., Ltd.
    Inventors: Makoto Iida, Eiichi Iino, Masanori Kimura, Shozo Muraoka
  • Patent number: 6053975
    Abstract: In a crystal holding apparatus, a corrugated portion between a seed crystal and a straight cylindrical portion of a monocrystal is held by holding portions of a lifting jig during a monocrystal growth process in which the seed crystal is brought into contact with material melt and is subsequently pulled while being rotated. In the crystal holding apparatus, an attachment member for establishing surface contact with the corrugated portion of the crystal is attached to the tip end of each holding portion of the lifting jig. Therefore, the monocrystal can be held reliably, so that the breaking and falling down of the monocrystal during the pulling operation can be prevented.
    Type: Grant
    Filed: March 16, 1998
    Date of Patent: April 25, 2000
    Assignee: Shin-Etsu Handotai Co., Ltd.
    Inventors: Makoto Iida, Eiichi Iino, Masanori Kimura, Shozo Muraoka
  • Patent number: 6048395
    Abstract: A method for producing a silicon single crystal in accordance with the Czochralski method. The single crystal is grown in an N.sub.2 (V) region where a large amount of precipitated oxygen and which is located within an N region located outside an OSF ring region, or is grown in a region including the OSF ring region, N.sub.1 (V) and N.sub.2 (V) regions located inside and outside the OSF ring region, in a defect distribution chart which shows a defect distribution in which the horizontal axis represents a radial distance D (mm) from the center of the crystal and the vertical axis represents a value of F/G (mm.sup.2 /.degree.C..multidot.min), where F is a pulling rate (mm/min) of the single crystal, and G is an average intra-crystal temperature gradient (.degree.C./mm) along the pulling direction within a temperature range of the melting point of silicon to 1400.degree. C.
    Type: Grant
    Filed: November 20, 1998
    Date of Patent: April 11, 2000
    Assignee: Shin-Etsu Handotai Co., Ltd.
    Inventors: Makoto Iida, Satoshi Suzuki, Eiichi Iino, Masanori Kimura, Shozo Muraoka
  • Patent number: 6027562
    Abstract: A single crystal is grown in accordance with a Czochralski method such that the time for passing through a temperature zone of 1150-1080.degree. C. is 20 minutes or less, or such that the length of a portion of the single crystal corresponding to the temperature zone of 1150-1080.degree. C. in the temperature distribution is 2.0 cm or less. Alternatively, the single crystal is grown such that the time for passing through a temperature zone of 1250-1200.degree. C. is 20 minutes or less, or such that the length of a portion of the single crystal corresponding to the temperature zone of 1250-1200.degree. C. in the temperature distribution is 2.0 cm or less. This method decreases both the density and size of so-called grown-in defects such as FPD (100 defects/cm.sup.2 or less), LSTD, and COP (10 defects/cm.sup.2 or less) to thereby enable efficient production of a single crystal having an excellent good chip yield (80% or greater) in terms of oxide dielectric breakdown voltage characteristics.
    Type: Grant
    Filed: October 16, 1998
    Date of Patent: February 22, 2000
    Assignee: Shin-Etsu Handotai Co., Ltd
    Inventors: Makoto Iida, Eiichi Iino, Masanori Kimura, Shozo Muraoka
  • Patent number: 5976246
    Abstract: A MCZ method in which the single crystal is pulled while being rotated under the conditions where the crystal growth rate V.sub.1 (mm/min) and the crystal circumference velocity V.sub.2 (mm/min) satisfy the following relationships:0.4.ltoreq.V.sub.10.628.times.10.sup.4 .ltoreq.V.sub.2 .ltoreq.1.0.times.10.sup.4andV.sub.2 .ltoreq.-3.72.times.10.sup.4 V.sub.1 +4.35.times.10.sup.4It is possible to manufacture a silicon single crystal with a large diameter with the MCZ method without causing distortion.
    Type: Grant
    Filed: November 19, 1997
    Date of Patent: November 2, 1999
    Assignee: Shin-Etsu Handotai Co., Ltd.
    Inventors: Eiichi Iino, Masanori Kimura, Shozo Muraoka
  • Patent number: 5968264
    Abstract: In method for manufacturing a silicon single crystal in accordance with a Czochralski method, during the growth of the silicon single crystal, pulling is performed such that a solid-liquid interface in the crystal, excluding a peripheral 5 mm-width portion, exists within a range of an average vertical position of the solid-liquid interface .+-.5 mm. There is also disclosed a method for manufacturing a silicon single crystal in accordance with the Czochralski method, wherein during the growth of a silicon single crystal, a furnace temperature is controlled such that a temperature gradient difference .DELTA.G (=Ge-Gc) is not greater than 5.degree. C./cm, where Ge is a temperature gradient (.degree.C./cm) at a peripheral portion of the crystal, and Gc is a temperature gradient (.degree.C./cm) at a central portion of the crystal, both in an in-crystal descending temperature zone between 1420.degree. C. and 1350.degree. C. or between a melting point of silicon and 1400.degree. C.
    Type: Grant
    Filed: July 2, 1998
    Date of Patent: October 19, 1999
    Assignee: Shin-etsu Handotai Co., Ltd.
    Inventors: Makoto Iida, Eiichi Iino, Masanori Kimura, Shozo Muraoka, Hideki Yamanaka
  • Patent number: 5968266
    Abstract: An apparatus for manufacturing a single crystal of silicon includes a crucible, a heater, electrodes, and a magnet. In addition to a plurality of heat generating portions and two main electrode portions, the heater has two or more auxiliary electrode portions. Two or more heater support members having an insulating property are further provided so as to support the heater through the auxiliary electrode portions. The number of heat generating portions which may be present between a heater support member and an electrode and between heater support members if adjacent to each other is equal to or less than 4. Each generating portion of the heater has a thickness of 25 mm or more. This structure makes it possible to produce a single crystal of silicon without causing breakage of a heater, even if a large electric current flows through the heater, even if a magnetic field of a high intensity is applied to a silicon melt in the crucible, and even if the heater has a large diameter.
    Type: Grant
    Filed: March 20, 1997
    Date of Patent: October 19, 1999
    Assignee: Shin-Etsu Handotai Co., Ltd.
    Inventors: Eiichi Iino, Masanori Kimura, Shozo Muraoka
  • Patent number: 5964941
    Abstract: A method and an apparatus for pulling a single crystal are disclosed. A neck portion, a corrugated portion, and a single crystal are formed below a seed crystal held by a seed chuck. When the corrugated portion is raised to a predetermined position (where lifting jig can hold the corrugated portion) by the seed chuck, the rising speed Va of the seed chuck is reduced, and a slider that supports a seed chuck lifting mechanism is raised at a speed Vb in order to maintain a constant pulling speed of the single crystal. Eventually, the pulling by the seed chuck is switched to the pulling by the slider. Subsequently, the lifting jig provided on the slider is raised slightly by a moving mechanism so that the crystal holding portions of the lifting jig are brought into contact with the corrugated portion and 1-50% of the weight of the crystal is shifted to the lifting jig. This enables safe and accurate growth of a heavy single crystal in accordance with, for example, the CZ method.
    Type: Grant
    Filed: September 15, 1997
    Date of Patent: October 12, 1999
    Assignee: Shin-Etsu Handotai., Ltd.
    Inventors: Eiichi Iino, Makoto Iida, Masanori Kimura, Shozo Muraoka
  • Patent number: 5948164
    Abstract: A seed crystal holder used in a crystal pulling apparatus operated in accordance with the Czochralski method. In the seed crystal holder, a heat-resistant cushioning material is provided between the surface of a seed crystal and the contact surface of claws of the holder or between a cutaway surface of the seed crystal and a contact surface of an insert of the holder. The heat-resistant cushioning material is selected from the group consisting of carbon fiber felt, glass fiber felt, metallic fiber felt, or selected from materials that cause plastic deformation such as Al.
    Type: Grant
    Filed: August 25, 1998
    Date of Patent: September 7, 1999
    Assignee: Shin Etsu Handotai Co., Ltd.
    Inventors: Makoto Iida, Eiichi Iino, Masanori Kimura, Shozo Muraoka
  • Patent number: 5911821
    Abstract: There is disclosed a Czochralski method in which a seed crystal in contact with material melt is pulled, while being rotated, so as to grow a monocrystal, and a part of the crystal being grown is mechanically held during the pulling operation. The crystal is mechanically held in such a way that the weight W(kg) of the crystal satisfies the following Formula (1):W<12.5.times..pi.D.sup.2 /4 (1)where D designates the minimum diameter (mm) of a neck. This makes it possible to pull a heavy monocrystal safely and reliably.
    Type: Grant
    Filed: September 5, 1997
    Date of Patent: June 15, 1999
    Assignee: Shin-Etsu Handotai Co., Ltd.
    Inventors: Eiichi Iino, Makoto Iida, Masanori Kimura, Shozo Muraoka
  • Patent number: 5882397
    Abstract: In a crystal pulling method in which a growing single crystal is initially pulled by a seed chuck and subsequently pulled by lifting jig in the middle of the pulling operation, the speed Va of the seed chuck relative to the lifting jig is decreased, while the rising speed Vb of the lifting jig increases, from a first point where switching of the pulling mechanism from the seed chuck to the lifting jig is started. The total speed Vt=Vb+Va is constantly maintained at a desired pulling speed V up to a third point where the shifting of the load from the seed chuck to the lifting jig is started. Subsequently, the total speed Vt is made less than the desired pulling speed V from the third point where the shifting of the load from the seed shuck to the lifting jig is started. This enables accurate growth of a crystal.
    Type: Grant
    Filed: October 6, 1997
    Date of Patent: March 16, 1999
    Assignee: Shin Etsu Handotai Co., Ltd.
    Inventors: Eiichi Iino, Makoto Iida, Masahiko Urano, Masanori Kimura, Shozo Muraoka