Study of Development Processes for ZEP-520 as a High-Resolution Positive and Negative Tone Electron Beam Lithography Resist

• DOI: 10.1143/jjap.51.06fc05
• Publication Date: 2012-06-20T01:33:10Z
• Authors: Mohammad Ali Moha...; Kirill Koshelev; Taras Fito; David Ai Zhi Zheng; Maria Stepanova; Steven Dew
• Keywords: High sensitivity; Methyl isobutyl ketone; Kinetic models; Dense gratings; Electron beams; 02 engineering and technology; Ketones; Microscopic parameter; Analytical method; Isopropyl alcohols; 01 natural sciences; Positive tone; Performance metrics; 0103 physical sciences; Electron beam resist; Development process; High resolution; Negative tones; 0210 nano-technology; Dissolution

ZEP brand electron beam resists are well-known for their high sensitivity and etch durability. The various performance metrics such as sensitivity, contrast, and resolution of ZEP resist depend strongly on the development process. In this work, we investigate the development of ZEP-520 resist through contrast curves, dense gratings, and surface roughness measurements using three different classes of developer systems of varying solvation strength, ZED-N50, methyl isobutyl ketone (MIBK) : isopropyl alcohol (IPA) 1:3, and IPA : H2O 7:3, at the ambient temperature (22 °C) and cold (-15 °C) development conditions. In order to provide a deeper insight into the ZEP development process, we propose a novel kinetic model of dissolution for ZEP, and develop an efficient analytical method that allows determining the microscopic parameters of ZEP dissolution based on experimental contrast curves. We also observe experimentally and characterize the negative tone behavior of ZEP for dense grating patterning and compare its performance with positive tone behavior.