Measurement of the native oxide thickness on a reference relief pitch structure on a single-crystal silicon substrate

Abstract

A reference relief pitch structure formed on a single-crystal silicon surface is investigated. The structure consists of trapezoidal elements (protrusions) with a pitch of 2 μm. The protrusions with upper bases of about 100 and 10 nm are located in one chip. The lateral surface of the element is tilted relative to its base by an angle of 54.7°. The entire structure is coated with the native oxide formed at room temperature. The oxide thickness is measured on an atomic-resolution transmission electron microscope in the mode of direct resolution of the crystal structure. In the measurements, the known distance between the {111} planes was used. It is established that the native oxide thickness depends on the sizes of both the protrusion’s upper base and bottom profile between the neighboring protrusions. It is demonstrated experimentally that in the region of the bottom, the native oxide thickness increases from 2.4 nm in the center of the bottom to 5 nm at the left and right bottom edges.