Characterisation of a novel electron beam lithography resist, SML and its comparison to PMMA and ZEP resists

Abstract

We present study on a novel, positive-tone electron beam lithography (EBL) resist known as SLM and compare its lithographic performance to well-established positive resists such as 950K polymethyl methacrylate (PMMA) and ZEP 520A. SML has been fabricated to have processing parameters similar to PMMA, but with enhanced functionality. Processing parameters such as film deposition, baking temperatures as well as the developers used for PMMA work well with SML resist.Contrast curve measurements were generated for different thicknesses of SLM and exposure voltages. Two temperature variants were employed for developing the resist with 7:3 IPA:water co-solvent developer, viz. room temperature and 0°C. To verify the resolution of SML resist, dense gratings of single pixel lines were compared to those fabricated using 950K PMMA and ZEP 520A resists. Fundamental pattern transfer skills of metal lift-off and dry etching were compared with ZEP. Metal lift-off was carried out using 5–10nm thick chromium metal and Microposit 1165 resist remover. The resilience of the SML resist to dry etching (ICP etching system with SF6 and C4F8 gas mixture) was compared to ZEP and PMMA resists and then dense gratings on ZEP and SML were etched into Si.The data obtained from the contrast curves show high contrast of the new resist. From the grating results, SML demonstrates very high resolution like ZEP and PMMA. The pattern transfer abilities of SML are also similar and in some aspects even outdo that of ZEP resist.