A sub‐0.5 μm bilevel lithographic process using the deep‐UV electron‐beam resist p(si‐cms)

Abstract Optimization of the deep‐UV and electron‐beam lithographic properties of a copolymer of trimethylsilylmethyl methacrylate (SI) and chloromethylstyrene (CMS), P(SI‐CMS), within a weight average molecular weight range of 1.4 to 4.1 × 10 5 and 90 to 93 mole percent SI composition has been achieved. The solubility behavior of P(SI‐CMS) resist was examined using the Hansen 3‐dimensional solubility parameter model and dissolution rate measurements. Swelling of the resist has been minimized through the identification of a single component developer (2‐propanol) and rinse (water) system. For the material containing 90 mole percent SI (14.9 weight percent Si) and M̄ ω = 1.4 × 10 5 , the sensitivity to 248 nm radiation is 65 mJ/cm 2 and to electron‐beam exposure is 3.4 μC/cm 2 at 20 kV. This material Is applicable to bilevel lithographic processes, and the O 2 reactive ion etching (RIE) rate is 16 times slower than standard hard‐baked photoresist. Using a He/O 2 (60/40) RIE pattern transfer process, 0.4 μm line/space patterns have been resolved in a 1.3 μm bilayer structure for deep‐UV exposures, and 0.25 μm imaging has been demonstrated in a 0.7 μm thick planarizing layer using electron beam irradiation. The loss in linewidth associated with the 0.25 μm process is ∼0.04 μm.