A method for forming an oxide layer on a vertical, non-planar semiconductor surface provides a low stress oxide layer having a pristine interface characterized by a roughness of less than 3 angstroms. The electric charge is generated in the charge generating layer by reception of the light energy emitted from the light source, and the surface of the latent image bearing member is electrically charged by applying the bias voltage from the bias voltage applying portion to the electrode. The object illumination beam is directed onto an object, and a portion of the beam is reflected back to the beamsplitter, which combines the phase-shifted reference beam and object illumination beam substantially coaxially. This reduces the number of ions entering into the photoresist.