Sumitomo Mitsubishi Silicon Corporation

Sumitomo Metal Industries, Inc.

Sumitomo Sitix Corporation

Sumco Corporation

Takayuki Kubo

Hiroshi Asano

Manabu Nishimoto

Masahiko Okui

Fumio Kawahigashi

Hideki Fujiwara

Sumio Kobayashi

Shunji Miyahara

Junji Horii

Shingo Kizaki

Shuichi Inami

Toshiyuki Fujiwara

Toshiaki Ono

Ken Nakajima

Wataru Sugimura

Hiroki Murakami

Makoto Ito

Kazuyuki Egashira

Kaoru Kuramochi

Tadami Tanaka

Setsuo Okamoto

Eiichi Asayama

Masataka Horai

Yoshihiro Akashi

Akira Higuchi

Shinichiro Miki

Shunji Kuragaki

Tatsuya Yabusame

Akira Tsujino

Katsuhito Makiyama

Masanori Kuwahara

Naohiro Takaoka

A process for producing a silicon single crystal includes the steps of bringing a seed crystal into contact with a silicon melt, gradually pulling the seed crystal from the melt so as to form a neck having a tapered portion and a constant diameter portion, then pulling a silicon single crystal. The atmosphere used during neck formation is a hydrogen-containing atmosphere prepared by adding a hydrogen-containing substance to an inert gas. The hydrogen-containing substance has a hydrogen gas equivalent concentration in the hydrogen-containing atmosphere of 3 to 20%.

Process for producing silicon single crystal

There are provided silicon single crystal, silicon wafer, and epitaxial wafer having a sufficient gettering effect suitable for a large-scale integrated device. The silicon single crystal which is suitable for an epitaxial wafer is grown with nitrogen doping at a concentration of 1&#xd7;10atoms/cmor more, or with nitrogen doping at a concentration of 1&#xd7;10atoms/cmand carbon doping at a concentration of 0.1&#xd7;10-5&#xd7;10atoms/cmand/or boron doping at a concentration of 1&#xd7;10atoms/cmor more. The silicon wafer is produced by slicing from the silicon single crystal, and an epitaxial layer is grown on a surface of the silicon wafer to produce the epitaxial wafer. The present invention provides an epitaxial wafer for a large-scale integrated device having no defects in a device-active region and having an excellent gettering effect without performance of an extrinsic or intrinsic gettering treatment, which is a factor for increasing the number of production steps and production costs.

Silicon single crystal, silicon wafer, and epitaxial wafer

In the CZ process using a cooling member surrounding a single crystal, the cooling member is permitted to effectively serve to increase a pulling speed. Cracks of the single crystal due to excessive cooling are prevented to occur. A high crystal quality is acquired. In order to realize these objects, the temperature of the inner peripheral surface of the cooling member opposing to the outer peripheral surface of the single crystal is restricted to 500&deg; C. or below, even in the lower end, the temperature of which becomes the highest. To achieve this restriction, the thickness T of the cooling member is 10 to 50 mm. The height H of the cooling member is 0.1 to 1.5 times the diameter D of the single crystal

Crystal growth method

An apparatus for growing a crystal, using the cooler surrounding the single crystal for high speed pulling. The cooler is prepared using a copper-based metal and is water cooled. The supporting arm that supports the cooler is prepared using stainless steel or the like, which is higher in mechanical strength than copper-based metals and is inferior in thermal conductivity, and is detachably connected to the cooler . Excessive cooling of the supporting arm and disposition due to precipitation of silicon oxide are prevented, leading to improvement in disposition free pulling rate without the prevention of speed-up. The cost of manufacture of the cooler is saved. The support strength of the cooler is improved.

Crystal growth apparatus

In a high rate pulling with a cooler surrounding a single crystal steam explosion by leakage from the cooler is prevented. Flow rates La, Lb of cooling water are measured by flowmeters on a cooling water inflow side and cooling water outflow side of the cooler When flow rate difference &Dgr;L (La&minus;Lb) determined from the flow rates La, Lb exceeds 20 cc/minute, open/close valves are operated to stop water supply to the cooler and drain outward the cooing water in the cooler

Crystal growing apparatus

An apparatus is provided which is to be used in producing single crystals for silicon wafers useful as semiconductor materials and which can stably produce large-diameter, long-length and high-quality single crystals from which wafers limited in the number of grown-in defects can be taken. This silicon single crystal production apparatus comprises a cooling member surrounding the single crystal to be pulled up and having an internal surface coaxial with the pulling axis and thermal insulating members disposed outside the outer surface and below the bottom surface of the cooling member, the cooling member having an internal surface diameter of 1.20D to 2.50D (D being the diameter of the single crystal to be pulled up) and a length of not less than 0.25D, the distance from the melt surface to the bottom surface of the cooling member being 0.30D to 0.85D and the bottom side of the thermal insulating member below the cooling member having an inside diameter smaller than the inside diameter of the bottom of the cooling member.

Production device for high-quality silicon single crystals

To impart flexibility suitable for recovery of a quartz crucible to a divided type graphite crucible and avoid damage to the quartz crucible due to the flexibility. A graphite crucible is divided into two or more parts by radial dividing lines . An opening is provided in a center of a bottom of the graphite crucible . A protrusion fitting into the opening is provided on a crucible placing surface of a crucible tray . An inner diameter d of the opening is 0.04 to 0.9 times an inner diameter d of a straight body portion of the graphite crucible . An outer diameter D of the crucible tray is 0.5 or more times an outer diameter D of the straight body portion of the graphite crucible . Minimum thickness of the crucible tray is 15 mm or more.

Single crystal pulling apparatus

A method of producing a high-quality silicon single crystal of a large diameter and a long size in a good yield by controlling the positions where ring-like oxygen-induced stacking faults (R-OSF) occur in the crystal faces and minimizing grown-in defects such a dislocation clusters and infrared scattering bodies that are introduced in the pulling step. Wafers produced from the above-high-quality silicon single crystal contain little harmful defects that would deteriorate device characteristics and can be effectively adapted to larger scale integration and size reduction of the devices. Therefore, the method can be extensively utilized in the field of producing semiconductor silicon single crystals.

High-quality silicon single crystal and method of producing the same

A single crystal silicon is produced using a Czocharalski (CZ) method. Silicon nitride powder is put in the bottom of a quartz crucible to provide a nitrogen concentration in the single crystal silicon of not less than about 1&times;10 atoms/cm . A poly-silicon raw material is then charged in the crucible. A pulling rate for the single crystal silicon is low so that an oxidation induced stacking faults ring exists or disappears at the center. Maintaining the nitrogen concentration of the single crystal silicon to not less than 1&times;10 atoms/cm decrease the vacancy cluster and existinguish the dislocation cluster. Wafers prepared from the single crystal silicon have very high quality with minimal defects.

Method for producing a single crystal silicon

The present invention was achieved in order to provide an apparatus for pulling a single crystal with which a single crystal having a low density of grown-in defects called infrared scatterers, dislocation clusters or the like can be grown. In the apparatus for pulling a single crystal having a crucible to be charged with a melt, a heater arranged around the crucible, a straightening vane in the shape of a side surface of an inverted truncated cone or a cylinder surrounding a pulled single crystal and a heat shield plate for inhibiting the radiant heat from diverging upward in the chamber from the side surface of the pulled single crystal located in the vicinity of the melt surface are arranged.

Single crystal pull-up apparatus

A process of growing crystals in which the uniformity of the oxygen concentration is desirable. In the process, the upper part of the material in the crucible is heated to form a molten layer, and a solid layer is formed at its lower part, then a seed crystal is made to contact the surface of the molten layer, and pulled up to grow a crystal, while characteristically a magnetic field is applied to the molten layer. This method produces single crystals with a uniform distribution of oxygen concentration. Furthermore, this method produces single crystals at low cost and with a high productivity.

Method of growing crystals

A solid layer is melted from the upper part thereof by the heat of a heater while the contact area between a molten liquid layer and an inner wall of a crucible is adjusted in a Double Layered CZ method, so that the eluting amount of oxygen from the crucible to the molten liquid layer is controlled. Accordingly, silicon single crystals of the low concentration of oxygen are produced.

Method of producing silison single crystal

A single crystal material is filled in a crucible, and the whole of the single crystal material is melted to contain doping impurities. A solid layer coagulated upward from the bottom of the crucible is rendered to coexist with a melted layer over the solid layer. The solid layer is melted from the upper side thereof while pulling the single crystal from the melted layer. The ratio by weight between the solid layer and the single crystal material at the start of pulling is adjusted, together with the ratio by weight between the grown single crystal and the melting solid layer. The single crystal is thus grown while changing the volume of the melted layer.

Method of growing crystal

An apparatus for growing a single crystal having a crucible, two heaters arranged at the outside of the crucible and along the vertical direction, a heat shield placed at the outside of the heaters, a radiation shield for shielding the single crystal from the radiation heat, and an upper heat shield for preventing the upward heat, transfer of the heaters. In the apparatus, a melted layer and solid layer of raw material are formed in the upper and lower portions of the crucible, respectively. While melting the solid layer, the single crystal is pulled up. The lower portion of the heat shield is thinner than the upper portion. The ratio of the height to the diameter of the crucible is 0.85 or more. The melting amount of the solid layer is controlled in the pulling process according to the non-segregation condition in the variable-thickness melted layer method. The oxygen concentration of the pulled single crystal is controlled in the pulling process by adjusting the rotation speed and rotation direction of the crucible.

Growing community of inventors

Tokyo, Japan

Takayuki Kubo