Apparatus for Automatically Balancing Wafers During Rotational Ion Implant
Original Publication Date: 1978-May-01
Included in the Prior Art Database: 2005-Feb-20
U. S. Patent 3,983,402 describes an apparatus for ion implantation wherein the wafers are mounted on a rotating disc which rotates the wafers past the ion beam in order to achieve mechanical scanning. On occasion, the scanning disc may be less than fully loaded. In such a situation, because of the delicate balance of the structure, balancing is necessary to make up for any off-balance presented by the missing wafers on the less than full rotating disc. The present approach avoids the use of dummy wafers.