Double frequency laser grating interference three-dimensional measurement method and system with optical aliasing resistance

Abstract

The invention discloses a double frequency laser grating interference three-dimensional measurement method and system with optical aliasing resistance, and belongs to a grating measurement technology. The system comprises a laser device, a grating interference mirror set and a photoelectric detection and signal processing unit. Two laser beams which are simultaneously output by the laser device, different in frequency and separated in space enter a polarizing beam splitter in parallel and in an incident mode. The first laser beam enters a reference grating in an incident mode after being reflected by the polarizing beam splitter to form multiple reference diffraction laser beams with multiple levels, the second laser beam enters a measurement grating in an incident mode after being transmitted by the polarizing beam splitter to form multiple measurement diffraction laser beams, five of the reference diffraction laser beams are sequentially and correspondingly joint with the (0, 0) level laser beam, the (0, +1) level laser beam, the (0, -1) level laser beam, the (+1, 0) level laser beam and the (-1, 0) level laser beam in the measurement diffraction laser beams respectively to form an optical beat frequency, and three-dimensional relative motion information of the measurement grating is acquired through photoelectric detection and signal processing. By the adoption of the method and system, optical frequency aliasing, polarization state aliasing and corresponding periodic non-linear errors caused by traditional incomplete polarizing beam splitting are eliminated.

Description

technical field [0001] The invention relates to a grating measurement method and a measurement system, in particular to a dual-frequency laser grating interference three-dimensional measurement method and a measurement system. Background technique [0002] The lithography machine in semiconductor manufacturing equipment is the key equipment in the production of semiconductor chips. The ultra-precision workpiece stage is the core subsystem of the lithography machine, which is used to carry the mask plate and silicon wafer to complete the high-speed ultra-precision step-and-scan movement. Ultra-precision workpiece table has become the most representative type of ultra-precision motion system due to its high-speed, high-acceleration, large-stroke, ultra-precision, and multi-degree-of-freedom motion characteristics. In order to realize the above-mentioned movement, the ultra-precision workpiece table usually uses a dual-frequency laser interferometer measurement system to measu...

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Problems solved by technology

Netherlands ASML company US patent US7,102,729B2 (disclosure date August 4, 2005), US7,483,120B2 (disclosure date November 15, 2007), US7,940,392B2 (disclosure date December 24, 2009), US2010 / 0321665A1 (published on December 23, 2010) discloses a planar grating measurement system and layout scheme applied to ultra-precision workpiece tables of lithography machines. The measurement system mainly uses one-dimensional or two-dimensional planar gratings for reading The head measures the horizontal large-stroke displacement of the workpiece table, and the displacement measurement in the height direction uses height sensors such as eddy currents or interferometers, but the application of various sensors limits the measurement accuracy of the workpiece table

U.S. Patent Publication No. US2011 / 0255096A1 (published on October 20, 2011) of ZYGO Corporation of the United States discloses a grating measurement system applied to ultra-precision workpiece tables of lithography machines. The measurement system also uses one-dimensional or two-dimensional gratings. A specific reading head realizes displacement measurement, which can simultaneously measure horizontal and vertical displacements; Tsinghua University Chinese Patent CN102937411A (public date: February 20, 2013), Tsinghua University Chinese Patent CN102944176A (public date: February 27, 2013) Disclosed is a dual-frequency grating interferometer displacement measurement system for an ultra-precision workpiece table of a lithography machine. The measurement system replaces the measurement target reflector (pyramid) of a traditional dual-frequency laser interferometer with a grating to realize dual-frequency laser Grating interferometry can measure large horizontal travel displacement and vertical displacement at the same time, but because the dual-frequency laser is coaxial, it uses a polarization beam splitter to separate it into reference light and measurement light, and there is optical frequency aliasing caused by incomplete polarization splitting , polarization aliasing and the corresponding periodic nonlinear error problem

The Chinese patent CN102353327A of the University of National Defense Science and Technology of the Chinese People's Liberation Army (public date: February 15, 2013) discloses a dual-frequency laser grating interferometry method and measurement system. Light, reference light and measuring light are incident on the moving measuring grating at the same time, and the reference light and measuring light diffracted by the measuring grating merge to form an optical beat frequency, and the displacement of the moving grating is obtained by photoelectric detection and signal processing. This system can only realize one Dimensional measurement, there are also problems of optical frequency aliasing, polarization state aliasing and corresponding periodic nonlinear errors caused by incomplete polarization splitting

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