Brain operations aided by transparent instruments

Abstract

Ion implantation is usually performed through a mask, usually of photoresist, a layer of organic material thick enough to stop the incoming ions except where it has been patterned lithographically to expose key areas. The lithography is an essential adjunct to implantation, as with other processes used in VLSI. Many of the limitations of ion implantation arise from limitations and drawbacks of the lithography and of the masking materials and their properties. This chapter outlines some commercial ion implanters, such as low-current first-generation implanters, medium-current implanters, high-current implanters, very-high current implanters, low-energy implanters, high-energy implanters, mask-projection implantation, and direct-write implantation. It also discusses ion beam production and acceleration and the problems associated with ion implantation. It then reviews ion implanter system design. Ion implanters grow increasingly complex. The successful implanter design will be one in which these complex needs are implemented in simple ways, in which subsystems can communicate and yet can stand alone, and in which access, particularly to key areas such as the ion source and its gases and to areas needing regular preventative maintenance, such as beam dumps and vacuum pumps, is as uncluttered and direct as possible.