The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 17, 1991
Filed:
Jun. 29, 1990
Youji Yamashita, Yokohama, JP;
Masakatu Kojima, Yokosuka, JP;
Kabushiki Kaisha Toshiba, Kawasaki, JP;
Abstract
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)>.sqroot.k is set to increase the doping impurity concentration in the longitudinal direction of the crystal, or the condition of (r/R)<.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.