Patent ID: 9025147
Filing Date: 2015-05-05
Classification: G01B,G01N,G02B

Abstract:
1. A method for detecting ultra-fine features of an integrated circuit on a semiconductor substrate, comprising: positioning an optical focus system in vicinity of a first planar surface of a semiconductor substrate, wherein the semiconductor substrate comprises an integrated circuit (IC) fabricated by 22 nanometer or smaller scale semiconductor micro-fabrication process, wherein the IC includes circuit features parallel to a circuit horizontal direction or a circuit vertical direction, wherein the circuit horizontal direction and circuit vertical direction are substantially parallel to the first planar surface; focusing an incident light by the optical focus system to produce a first focused light spot on a portion of the integrated circuit in the semiconductor substrate, wherein the incident light is linearly polarized in a first linear polarization substantially parallel to the circuit horizontal direction; detecting, by a photo detector, a first reflected light reflected from the portion of the integrated circuit in the semiconductor substrate; producing, by a scanning system, a relative movement between the first focused light spot and the integrated circuit to allow the first focused light to illuminate different portions of the integrated circuit; obtaining a first image of the integrated circuit using signals of the first reflected light detected from different locations of the integrated circuit; detecting first features of the integrated circuit in the first image; producing a relative rotation between the first linear polarization of the incident light and the semiconductor substrate to cause the linear polarization substantially parallel to the circuit vertical direction; focusing the incident light by the optical focus system to produce a second focused light spot on the first planar surface of the semiconductor substrate; detecting a second reflected light reflected from the semiconductor substrate by the photo detector; producing a relative movement between the second focused light spot and the integrated circuit by the scanning system; and obtaining a second image of the integrated circuit using signals of the second reflected light detected from different locations of the integrated circuit, wherein the first features in the first image of the integrated circuit are absent in the second image.