On the photoresist stripping and damage of ultralow k dielectric materials using remote H2- and D2-based discharges

Blanket films of ultralow dielectric constant (ULK) materials and 193nm photoresist films have been processed downstream from hydrogen and deuterium-based discharges produced using an inductively coupled plasma reactor. Photoresist ashing rates and ULK modifications have been determined as a function of process parameters. The explored ULK materials differed widely in porosity and carbon content. The effect of processing time, substrate temperature (200–300°C), and gas composition on the surface and bulk chemical composition of ULK materials was monitored and quantified by ex situ ellipsometry and time-of-flight secondary ion mass spectrometry (SIMS). The stripping rates of 193nm photoresist films were found to strongly depend on processing temperature and only weakly on the nature of the H2/additive gas mixture. The authors found that hydrogen (or deuterium) fully penetrates the high porosity ULK layer, whereas for low porosity materials, such penetration is limited to a 50nm near-surface region. SIMS me...