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1989
Journal Article
Titel
Overlay precision between electron beam and optical lithography systems for a mix and match GaAs technology.
Alternative
Justiergenauigkeit bei einer Mischlithographie zwischen Elektronenstrahl- und optischer Lithographie in der GaAs-Technologie
Abstract
A systematic study has been carried out to determine the feasibility of a mix and match GaAs technology where only the gate level is defined by electron beam (e-beam). The overlay accuracy between e-beam and optically defined patterns was determined for a range of marker field sizes up to 8x8 mm. Ti/Au markers, which are ideal for e-beam registration and alloyed Au/Ge/Ni/Au markers (Ohmic contact on GaAs), which are not normally considered suitable for registration, were used in the study. Using Ohmic metal markers the gate can be aligned directly to the source-drain contact mask level, thus eliminating optical-to-optical overlay errors which would occur if a zero level alignment mask were used. A "mix and match" technology has been used to fabricate 0.2 mym gate-length metal-semiconductor field effect transistor (MESFET) devices with 0.3 mym source-gate spacing.