Single wavelength ellipsometry with improved spot size capability

Abstract

Methods and systems for performing single wavelength ellipsometry (SWE) measurements with reduced measurement spot size are presented herein. In one aspect, a pupil stop is located at or near a pupilplane in the collection optical path to reduce sensitivity to target edge diffraction effects. In another aspect, a field stop is located at or near an image plane conjugate to the wafer plane in thecollection optical path to reduce sensitivity to undesired optical-structural interactions. In another aspect, a linear polarizer acting on the input beam of the SWE system includes a thin, nanoparticle based polarizer element. The nanoparticle based polarizer element improves illumination beam quality and reduces astigmatism on the wafer plane. The pupil and field stops filter out unwanted lightrays before reaching the detector. As a result, measurement spot size is reduced and tool-to-tool matching performance for small measurement targets is greatly enhanced.

Description

[0001] Cross References to Related Applications [0002] This patent application asserts the title of "Methods of Improved Spot Size Capability in Single Wavelength Ellipsometry" filed on January 22, 2016 under 35 U.S.C. §119 Priority to US Provisional Patent Application No. 62 / 286,279, the subject matter of which is hereby incorporated by reference in its entirety. technical field [0003] The embodiments relate to metrology systems and methods, and more particularly, the embodiments relate to methods and systems for improved metrology of semiconductor structures. Background technique [0004] Semiconductor devices, such as logic and memory devices, are typically fabricated through a series of processing steps applied to samples. Various features and multiple structural levels of the semiconductor device are formed through these processing steps. For example, photolithography, among other things, is a semiconductor manufacturing process that involves creating patterns on...

AI Technical Summary

Problems solved by technology

[0011] Future metrology applications present challenges due to small feature sizes and multi-parameter correlations

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