SEDL / STP / STP960-EB / STP25755S

Effects of Deep UV Radiation on Photoresist in Al Etch

Lee, SC
Members of the Technical StaffStaff Engineers, Siliconix Inc., Santa Clara, CA

Chin, BL
Members of the Technical StaffStaff Engineers, Siliconix Inc., Santa Clara, CA

Pages: 7    Published: Jan 1987

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Abstract

The photoresist integrity and edge profile can be improved in Al RIE etch by exposing the patterned Al coated wafers to deep UV radiation (λ =220nm). The transmitted DUV intensity on a photoresist coated clear sapphire wafer was measured as a function of the accumulated exposure time. The transmitted DUV intensity reaches a maximum after a period which is proportional to the photoresist thickness. The surface of the DUV exposed photoresist forms a highly polymerized membrane during hard bake and is stressed by the vapor pressure from inside the photoresist. The property of this membrane was studied and reasons for the improved etch integrity are proposed.