Scanning probe lithography and nanofabrication

The capabilities of the scanning probe microscope to write nanometer-scale lines on various types of resist and to define a narrow metal gate line for a high electron mobility transistor have been demonstrated. A modified scanning tunneling microscope has been used to write lines with 25 nm wide and 60 nm period on a monolayer stearic acid deposited Au film. Carbon deposits build up underneath the tip for tip voltages with absolute value greater than 4 V. The scanning tunneling microscope was also used to selectively oxidize a 5 nm thick {dollar}rm Sisb3Nsb4{dollar} film which was deposited with low-pressure chemical vapor deposition on a p+ silicon substrate in ambient. After the SiO{dollar}sb2{dollar} lines were removed with buffered oxide etch, the unoxidized {dollar}rm Sisb3Nsb4{dollar} area was used to block the NH{dollar}sb4{dollar}F etch that was used to etch the Si substrate. A metallized scanning atomic force microscope was used to write sub-100 nm wide SiO{dollar}sb2{dollar} lines on either a thin thermally grown SiO{dollar}sb2{dollar} or native SiO{dollar}sb2.{dollar} Subsequently the field induced oxide lines were removed with a dip in buffered hydrofluoric acid. The modified atomic force microscope was also used to selectively oxidize {dollar}rm Sisb3Nsb4{dollar} in air. A high electron mobility transistor metal gate line was fabricated by exposing a thin resist with a metallized scanning force tip followed by a lift-off process to deposit the gate metal.