Ion Implantation Sources and Source Materials.

The method of doping semiconductors through the use of ion implantation has become of great industrial interest. The ability to measure accurately the quantity of ions being implanted in the sample allows better control of concentration than is possible with diffusion. This close control is particularly important in MOS threshold voltage adjustment. The ability to create pure, high current, stable beams of various dopant materials is the primary concern of this work. First, the basic elements of an implanter and ion sources are reviewed, with an emphasis on the mechanisms of beam creation. Then, the mass spectra beam analysis obtained from three sources on an Accelerators Inc. 300-MP ion implanter are given for a variety of source materials. Finally, for each source material, recommendations are made as to which source produces the desired beam characteristics.