Radiant energy – Irradiation of objects or material – Irradiation of semiconductor devices
Reissue Patent
2008-01-22
2008-01-22
Berman, Jack I. (Department: 2881)
Radiant energy
Irradiation of objects or material
Irradiation of semiconductor devices
C250S492100
Reissue Patent
active
RE040008
ABSTRACT:
A method and apparatus for controlling implantation during vacuum fluctuations along a beam line. Vacuum fluctuations may be detected based on a detected beam current and/or may be compensated for without measuring pressure in an implantation chamber. A reference level for an ion beam current can determined and a difference between the reference value and the measured ion beam current can be used to control parameters of the ion implantation process, such as a wafer scan rate. The difference value can also be scaled to account for two types of charge exchanging collisions that result in a decrease in detected beam current. A first type of collision, a non-line of sight collision, causes a decrease in detected beam current, and also a decrease in the total dose delivered to a semiconductor wafer. A second type of collision, a line of sight collision, causes a decrease in detected beam current, but does not affect a total dose delivered to the wafer. Scaling of the difference can therefore be used to adjust a wafer scan rate that accounts for non-line of sight collisions.
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Berman Jack I.
Varian Semiconductor Equipment Associates Inc.
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