| 摘要 |
<p>A control system for an ion implantation system of the type in which wafers (12) to be implanted are mounted around the periphery of a disk (10) which rotates and also moves in a radial direction relative to an ion beam (B) to expose successive sections of each wafer to radiation. The control system senses beam current which passes through one or more apertures or slots (22) in the disk (10) and is collected by a Faraday cup (27). This current is integrated in integrator (50) to obtain a measure of charge which is compared with a calculated value based upon the desired ion dosage and other parameters in computer (40). The resultant controls the number of incremental steps the rotating disk moves radially through radial drive (30) and output worm shaft (31) to expose the adjacent sections of each wafer. This process is continued usually with two or more traverses until the entire surface of each wafer has been implanted with the proper ion dosage from ion source (25). </p> |
