Projection-patterned etching of silicon in chlorine atmosphere with a KrF excimer laser

摘要: The formation of relief features in silicon by a one-step process that avoids resist patterning has been achieved laser-projection-patterned etching chlorine atmosphere. Etching is performed with pulsed KrF excimer laser (λ=248 nm, τ=15 ns) and deep UV projection optics having an optical resolution 2 μm. takes place two steps. Between pulses, the surface covered monolayer chemisorbed atoms (one Cl per Si). During pulse, transient heating at temperatures excess 1250 K results desorption reaction products (mainly SiCl2). At energy densities induce melting, this saturated etch. rate 0.06 nm corresponding to removal about 0.5 Si pulse. below melting threshold, reduced thermal possibly small amount photochemical result lower etch rates. Projection test photomask onto shows size etched differs from projected strongly depends on density. As heat spread highly nonlinear character reaction, smaller than irradiated area are obtained all fluences range 350–700 mJ/cm2. Etched lines width down 1.3 μm were produced. Proximity effects due also evidenced for (<4 μm). characteristics patterns compared those GaAs chlorinated gases same experimental set-up. Significant differences pattern observed. This variation believed fact greater diffusivity GaAs.