Detecting registration marks with a low energy electron beam

Abstract From the Canadian patent

For electron beam wafer or mask processing a registration mark is , capacitively coupled to the top surface of an overlying resist layer on a substrate to form a voltage potential on the surface of the resist layer directly over the registration mark. The registration mark is directly connected to an electrical lead that produces an AC voltage on the registration mark, which is capacitively induced on the surface of the resist layer. Alternatively, the registration mark itself is capacitively coupled to a conductive plate placed on the bottom surface of the semiconductor substrate. An AC voltage is then applied to the conductive plate that induces a charge on the registration mark, …