1 kV resist technology for microcolumn-based electron-beam lithography

Abstract

The objective of this article is to evaluate low-voltage electron-beam (e-beam) resists suitable for direct write on wafer and mask fabrication in the sub-100 nm regime. Low kV exposure provides the advantages of high sensitivity, reduced charging, and a lack of proximity and heating effects. However, a major concern is whether a low-voltage e-beam is capable of patterning sub-100 nm features in resist with a thickness substantially greater than the penetration range of the electrons. At 1–2 kV, the penetration range is between 30 and 100 nm, while typical resist thickness is >200 nm. In an effort to overcome this limitation, thin film layer techniques are evaluated for low kV e-beam exposure. Preliminary 1 kV results on two thin imaging schemes, the bilayer CARL process and top surface imaging with NTS-4 resist, are reported here. Important results achieved are high sensitivity (1–2 μC/cm2), high contrast (γ>10), high resolution (70 nm in ∼300 nm thick resist), good critical dimension (CD) linearity (range=7 nm, mean=8 nm), large exposure latitude (ΔCD/Δdose=0.5 nm/% change in dose), and absence of proximity effects.