Kabushiki Kaisha Toshiba

Youji Yamashita

Masakatu Kojima

Takanobu Kamakura

Yoshiaki Matsushita

Masanobu Ogino

To manufacture a low-carbon concentration GaAs wafer required for devices such as hall sensors, FETs, HEMTs etc. at a high production yield without deteriorating the semi-insulation characteristics thereof, a method of manufacturing a semi-insulation GaAs monocrystal by controlling carbon concentration during crystal growth by a simple method is disclosed. The method of manufacturing a semi-insulation GaAs monocrystal in accordance with liquid encapsulated Czochralski method, comprises the steps of: preparing a crucible (5) formed with a crucible body (6) and a small chamber (8) communicating with a lower part of the crucible body and a carbon heater (4) processed to reduce surface blow holes thereof; putting a melted GaAs liquid and a sealing compound B.sub.2 O.sub.3 in the crucible housed in an airtight vessel in such a way that the sealing compound B.sub.2 O.sub.3 is on the melted GaAs liquid and further the melted GaAs liquid put in the small chamber contains carbon to be supplied to the melted GaAs liquid in the crucible body; heating the crucible by the heater housed in the airtight vessel; and pulling up the melted GaAs liquid from the crucible body by keeping the airtight vessel at a high pressure.

Method and apparatus for manufacturing semi-insulation GaAs monocrystal

A method of manufacturing a semiconductor substrate in which a damage layer is formed on one surface of a wafer. An etching protection film is formed on the damage layer. An epitaxial layer is formed on the other surface of the wafer. Thereafter, the etching protection film is removed to expose the damage layer. The exposed damage layer enhances gettering ability.

Method of manufacturing a semiconductor substrate

A crystal pulling method includes the steps of disposing a separation wall concentrically with an in a semiconductor crystal pulling crucible to divide the crucible into an inner chamber and an outer chamber, putting first doped material melt into the inner chamber and second material melt into the outer chamber, and pulling crystal from the first material melt in the inner chamber while the second material melt in the outer chamber is being supplied to the inner chamber via a coupling member which connects the inner and outer chamber with each other but suppresses the outflow of impurity from the inner chamber to the outer chamber. Assume that k is the segregation coefficient of doping impurity in the first material melt, r is half the inner diameter of the inner chamber, and R is half the inner diameter of the outer chamber. The second material melt in the outer chamber is undoped melt, and the condition of (r/R)&gt;.sqroot.k is set to increase the doping impurity concentration in the longitudinal direction of the crystal, or the condition of (r/R)&lt;.sqroot.k is set to lower the doping impurity concentration in the longitudinal direction of the crystal so as to compensate for or cancel the influence by conductive impurity which has flowed out of the crucible and mixed into the melt, thus controlling the resistivity of the pulling crystal in the longitudinal direction thereof.

Semiconductor crystal pulling method

A crystal pulling apparatus of double structure crucible has a crucible body which is divided into inner and outer chambers by a cylindrical partition wall coaxially disposed in the crucible body. A melt supplying path used to supply melt from the outer chamber of the crucible to the inner chamber in which the crystal is pulled is formed of a small through hole formed in the partition wall or the small through hole and a pipe-like passage formed in communication with small through hole. The radius of the inner chamber of the double structure crucible has a specified relation determined by the segregation coefficient of dopant impurity with respect to the radius of the outer chamber. This is, the radius of the inner chamber is set substantially equal to .sqroot.k times the radius of the outer chamber when the segregation coefficient of the dopant impurity is k. In the crystal pulling apparatus with the double structure crucible, a small chamber for introducing dopant is disposed in the outer chamber of the crucible to be in communication with the inner chamber.

Crystal pulling apparatus and crystal pulling method

In a crystal pulling process using an integral type double crucible, a cylindrical separation wall is mounted in and is coaxial with a crucible, for receiving semiconductor material melt to divide the crucible into inner and outer chambers. A coupling tube fixed at the side wall of the separation wall and having a pipe-like passage with a small hole is provided to make a pass between the inner and outer chambers. While material melt in the outer chamber is being supplied to the inner chamber via the coupling tube, crystal is pulled from the melt received in the inner chamber and having an impurity composition different from that of the melt in the outer chamber.

Crystal pulling apparatus and crystal pulling method using the same

The present invention discloses a crystal pulling apparatus having a double-crucible structure, wherein an inner crucible is located in an outer crucible. An end of a pipe-like passage is located in a through hole formed in a side wall of an inner crucible located in an outer crucible, and a melt is supplied from the outer crucible to the inner crucible through the pipe-like passage, during crystal pulling. During melting or neckdown, prior to crystal pulling, diffusion of an impurity between the melts in the outer crucible and the inner crucible, and exchange of the melts between the outer crucible and the inner crucible are prevented by the pipe-like passage.

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Yokohama, Japan

Youji Yamashita