Mitsubishi Materials Corporation

Mitsubishi Kinzoku Kabushiki Kaisha

Mitsubishi Materials Silicon Corporation

Mitsubishi Metal Corporation

Zag Ltd.

Mitsubishi Materials Quartz Corporation

Mitsubishi Materials Sillcon Corporation

Michio Kida

Kensho Sahira

Hisashi Furuya

Takashi Atami

Yoshiaki Arai

Hiroaki Taguchi

Naoki Ono

Akikuni Nozoe

Masanori Fukui

The invention relates to a single crystal pulling apparatus comprising; an outer crucible 11 positioned inside a chamber (gas tight container) 2, for storing a semiconductor melt 21, and an inner crucible 30 comprising a cylindrical partition body, mounted inside the outer crucible 11 to form a double crucible, and wherein a single crystal of semiconductor 26 is pulled from the semiconductor melt 21 stored inside the inner crucible 30. With this arrangement, the inner crucible 30 is made from quartz and comprises an inside layer A, an outside layer C, and an intermediate layer B which lies between the inside layer A and the outside layer C, and the intermediate layer B is made from quartz with a larger gas bubble content than the quartz which makes up the inside layer A and the outside layer C of the inner crucible 30.

Single crystal pulling apparatus

A single crystal pulling method employing; a gas tight container, a double crucible for storing a semiconductor melt inside the gas tight container comprising an inter-connected outer crucible and inner crucible, and a source material supply tube suspended from an upper portion of the gas tight container and positioned so that a granulated or powdered source material can be added from a lower end opening thereof to the semiconductor melt inside the outer crucible, with the source material being injected into the source material supply tube together with an inert gas flowing towards the enclosed container, characterized in that said source material is injected under conditions where the flow rate N (1/min.multidot.cm.sup.2) of the inert gas is within the range 0.0048P+0.0264&lt;N&lt;0.07P, where P (Torr) is the internal pressure inside said gas tight container.

Single crystal pulling method and apparatus for its implementation

A single crystal pulling apparatus wherein a semiconductor melt is stored in an outer crucible, and a cylindrical inner crucible which acts as a partition body, is mounted inside the outer crucible to thus form a double crucible, and a single crystal of semiconductor is pulled from the semiconductor melt inside the inner crucible. The inner crucible contains a communicating portion, which is formed when the double crucible is formed, for allowing flow of the semiconductor melt into the inner crucible, and the communicating portion incorporates an arrangement for removal of gas bubbles which have adhered to the communicating portion.

A single crystal pulling apparatus comprising: a gas tight container, a double crucible for storing a semiconductor melt inside the gas tight container comprising an outer crucible and an inner crucible which are connected at a lower edge, and source material supply means for adding source material to the semiconductor melt at a position between the outer crucible and the inner crucible, characterized in that a flow restriction member is provided inside the semiconductor melt region between the outer crucible and the inner crucible for restricting the flow of the semiconductor melt.

The principal construction of a single crystal pulling apparatus involves a chamber (gas tight chamber) inside of which is a double crucible 3 for storing a semiconductor melt 21, comprising an outer crucible 11 and an inner crucible 12 communicated with each other, and a source material supply tube 5 suspended from an upper portion of the chamber, and positioned so that granular source material 8 can be introduced from a lower end opening 5a thereof into the semiconductor melt 21 between the outer crucible 11 and the inner crucible 12. An incline portion 13 is provided at a lower end of the source material supply tube 5 on the inner crucible 12 side, for introducing source material 8 discharging from the lower end opening 5a to the semiconductor melt 21 in the vicinity of the side wall of the outer crucible 11. The entry point of the source material 8 is as far as possible from the inner crucible 12, and close to the outer wall of the outer crucible 11, and hence the added source material 8 is melted rapidly by heat from a heater surrounding the outer crucible 11, and any gas bubbles generated as a result of the introduction of the source material 8, are unlikely infuse into the inner crucible 12.

A method of growing a single crystal of semiconductor using a CZ growth technique, having a step (0&lt;t&lt;t1) wherein a single crystal of semiconductor is pulled while a source material is supplied continuously to maintain a constant amount of semiconductor melt, and a step (t2&lt;t&lt;t3) wherein the supply of source material is halted, and the single crystal of semiconductor is pulled using residual melt from the first step.

Single crystal growth method

The present invention provides an improved single crystal pulling apparatus for pulling a single crystal semiconductor such as silicon or gallium arsenide. The apparatus of the present invention comprises a gas tight container, a crucible which is disposed inside the container, a heater, and a pair of coils to apply a cusp magnetic field in the semiconductor melt. The crucible is separated into two regions by a cylindrical partition body, and an outside region is used to supply source material and to melt the source material and an inside region is used for pulling up the single crystal. The inside and outside regions are communicated with the communication passage provided at the bottom of the partition body. Electrical currents in opposing directions are applied to a pair of coils for generating in the melt a cusp magnetic field which includes a vertical portion and a horizontal portion relative to the crucible. By positioning the vertical portion of the cusp magnetic field at the position of the communication passage and the horizontal portion below the semiconductor melt, the flow rate of the melt passing through the communication passage is reduced and the convection within the melt is suppressed. Consequently, high quality semiconductor single crystals can be obtained.

An apparatus for growing a single crystal is disclosed which includes a double crucible assembly. The double crucible assembly has an outer crucible and an inner crucible disposed in the outer crucible. A support member is provided for supporting the inner crucible, and the support member is formed of an inorganic oxide non-reactive with silicon oxide. The upper end portion of the inner crucible may be formed of the same inorganic oxide. Alumina or mullite is suitable as the inorganic oxide. With the above construction, silicon single crystals obtained by the crystal growing apparatus will be free of contamination by carbon or heavy metals, and will exhibit excellent quality.

Apparatus for growing single crystals

In apparatuses for melting semiconductor material and growing single crystals of semiconductor material, the apparatus comprising:

Apparatus for process for growing crystals of semiconductor materials

A monocrystal rod utilized for producing the semiconductor device or solar cell includes a neck section, a main rod section and a shoulder section. The neck section is smaller in diameter than a seed crystal. The main rod section is formed integrally with the neck section and is larger in diameter than the neck section. The shoulder section is tapered for linking the neck section to the main rod section. The main rod section has a stopper section at the top portion of the main rod section, and the stopper section is larger than the main rod section. Also, an apparatus for preparing the monocrystal rod has a safety member for supporting upward the stopper section of the falling monocrystal rod. Further, a method of preparing the monocrystal rod includes the steps as follows. The seed crystal is pulled out from a melt in a crucible while rotating it. The speed of pulling the seed crystal is at first increased to grow the neck section whose diameter is smaller than the seed crystal, and then is gradually decreased to grow the shoulder section. Subsequently, the pulling speed is increased again so as to prevent further increase in diameter to grow the stopper section at the lower end of the shoulder section or at the top portion of the main rod section, and then is decreased again to grow the main rod section whose diameter is equal to a required diameter.

Monocrystal rod pulled from a melt

A monocrystal rod utilized for producing the semiconductor device or solar cell includes a neck section, a main rod section and a shoulder section. The neck section is smaller in diameter than a seed crystal. The main rod section is formed integrally with the neck section and is larger in diameter than the neck section. The shoulder section is tapered for linking the neck section to the main rod section. The main rod section has a stopper section at the top portion of the main rod section, and the stopper section is larger than the main rod section. Also, an apparatus for preparing the monocrystal rod has a safety member for supporting upwards the stopper section of the falling monocrystal rod. Further, a method of preparing the monocrystal rod includes the steps as follows. The seed crystal is pulled out from a melt in a crucible while rotating it. The speed of pulling the seed crystal is at first increased to grow the neck section whose diameter is smaller than the seed crystal, and then is gradually decreased to grow the shoulder section. Subsequently, the pulling speed is increased again so as to prevent further increase in diameter to grow the stopper section at the lower end of the shoulder section or at the top portion of the main rod section, and then is decreased again to grow the main rod section whose diameter is equal to a required diameter.

A crystal growing apparatus includes a crucible, a feed pipe and a pulling mechanism. The crucible serves to melt a crystalline material. The feed pipe serves to cause the crystalline material to fall into the crucible to charge the crucible with the crystalline material. The pulling mechanism serves to pull a single-crystal from the molten material in the crucible. The feed pipe has a lower end positioned slightly above the surface of the molten material in the crucible and including a plurality of baffle plates mounted on an inner peripheral wall thereof in longitudinally spaced relation to one another. The baffle plates are arranged so that a pitch defined between adjacent two baffle plates decreases toward the lower end of the feed pipe.

Apparatus for growing crystals

A quartz double crucible assembly utilized for producing silicon crystalline rods is manufactured as follows. First, outer and inner quartz crucibles are prepared by means of arc fusion method. Then, the outer and inner crucibles are received in a vessel accommodated in a heat-treating furnace. Subsequently, the crucibles are heated to a prescribed elevated temperature. Thus, the outer and inner crucibles are caused to join together, and a double crucible assembly is produced.

Method of manufacturing quartz double crucible assembly

An apparatus for melting a semiconductor material and growing a semiconductor crystal from the melted material includes a susceptor having a peripheral rim, a quartz crucible assembly for receiving the semiconductor material therein. The crucible assembly includes an outer crucible housed in and supported by the susceptor and an inner crucible adapted to be so placed within the outer crucible as to define a multi-wall structure. The apparatus also includes at least one fluid passage for permitting the melted material to flow between the inner and outer crucibles when the multi-wall structure is defined by the inner and outer crucibles, a holder for holding the inner crucible, a heater disposed so as to surround the susceptor for heating the material in the crucible assembly, and a drive mechanism operable to move at least one of the holder and the susceptor vertically between a coupled position where the holder is supported by the susceptor in such a manner that the inner crucible is so placed within the outer crucible as to define the multi-wall structure and a released position where the holder is disengaged from the susceptor in such a manner that the inner crucible is released from the outer crucible. There is also provided a process which may be conveniently carried out in the apparatus described above.

Apparatus and process for growing crystals of semiconductor materials

In a method for pulling a single crystal, employing a double crucible assembly, the dopant concentration of the molten raw material in an inner crucible prior to the pulling, is raised to a value higher than the dopant concentration C of the molten raw material in the inner crucible at the steady state. Furthermore, at the initial stage of the pulling, the raw material having a dopant content ratio of no greater than kC is introduced into the outer crucible at a rate greater than the rate of decrease of the molten raw material within the inner crucible during the pulling, to achieve a concentration ratio of dopant between the inner and outer crucibles at a target value. Subsequently, the raw material having kC as the dopant content ratio is introduced into the outer crucible, at a rate equal to the rate of decrease of the molten raw material during the pulling.

Growing community of inventors

Urawa, Japan

Michio Kida