Journal of Vacuum Science & Technology B, Vol.16, No.6, 3701-3704, 1998
Copolymer approach to charge-dissipating electron-beam resists
During electron-beam lithographic exposure on insulating substrates, pattern distortions and displacements are observed due to charging of the surface. To alleviate these displacements, conducting polymers have been investigated in the past decade as negative-tone resists and as unimageable top or bottom layers in a multilayer stack. Our approach uses a graft copolymer: an acrylic backbone for the imaging performance of the resist and a conducting polymer grafted onto the backbone for the charge-dissipating performance. By using this system, the respective properties of the two components can be individually optimized for such properties as speed, etch resistance, solubility, and conductivity. This system also permits positive-tone single-layer imaging, which has not been achievable previously. High-resolution features (<0.10 mu m): minimal pattern distortions, and no change in the clearing dose, were observed for graft copolymers containing <1% of the charge-dissipating component that were processed identically to commercially available PMMA resist.