Analysis of Substrate Effect in Chemically Amplified Resist

The substrate-effect of chemically amplified (CA) resist on several substrate (SiN, Boron-Phosphorous-Silicate-Glass (BPSG), Boron-Silicate-Glass (BSG), Phosphorous- Silicate-Glass (PSG) and non-doped-Silicate-Glass (NSG)) has been investigated using surface analyzing technique. The resist pattern of a negative-tone CA resist on SiN, BPSG, PSG and BSG substrate have undercut profile. To clarify the interaction between CA resist and SiN, BPSG, BSG, PSG and NSG substrate, the surface of these substrate was analyzed by Electron Spectroscopy for Chemical Analysis (ESCA). From the results of ESCA, it was found that Si-N bonding is replaced to Si-O bonding while SiN substrate is treated with oxygen plasma. As a results of MO(Molecular Orbital) method, HOMO(Highest Occupied Molecular Orbital) level of model compounds is in fair agreement with the present results. Their results suggests that the proton in CA resists were quenched by substrate. On the other hands it was found that BPSG, BSG, PSG and NSG substrate are boron oxides and/or phosphorous oxides on the surface. These oxides are considered to be contributing to undercut profile of negative resist, and they quench a photo-generated acid in the resist.