US 12,393,127 B2
Exposure light beam phase measurement method in laser interference photolithography, and photolithography system
Leijie Wang, Beijing (CN); Yu Zhu, Beijing (CN); Ming Zhang, Beijing (CN); Jitao Xu, Beijing (CN); Rong Cheng, Beijing (CN); Xin Li, Beijing (CN); Kaiming Yang, Beijing (CN); and Jinchun Hu, Beijing (CN)
Assigned to Tsinghua University, Beijing (CN); and Beijing U-Precision Tech Co., Ltd., Beijing (CN)
Appl. No. 17/767,399
Filed by TSINGHUA UNIVERSITY, Beijing (CN); and BEIJING U-PRECISION TECH CO., LTD., Beijing (CN)
PCT Filed Oct. 23, 2020, PCT No. PCT/CN2020/123222
§ 371(c)(1), (2) Date Apr. 7, 2022,
PCT Pub. No. WO2021/083043, PCT Pub. Date May 6, 2021.
Claims priority of application No. 201911050178.6 (CN), filed on Oct. 31, 2019.
Prior Publication US 2024/0061352 A1, Feb. 22, 2024
Int. Cl. G03F 7/00 (2006.01); G03F 7/20 (2006.01)
CPC G03F 7/7085 (2013.01) [G03F 7/2006 (2013.01); G03F 7/70408 (2013.01)] 10 Claims
OG exemplary drawing
 
1. An exposure light beam phase measurement method for laser interference photolithography, wherein a variable period interference fringe phase measurement method based on heterodyne measurement principle uses a laser phase measurement interferometer to measure a phase of an exposure light beam for laser interference photolithography, the laser phase measurement interferometer comprises a first wave plate, a first polarized beam-splitting prism, a second wave plate, a second polarized beam-splitting prism, a polarizer, a first photoelectric detector, a second photoelectric detector, a third polarized beam-splitting prism, a reflector, a third wave plate, a backward reflector and a fourth wave plate, and the exposure light beam phase measurement method comprises the following steps:
separating two measurement light beams from two exposure light beams for laser interference photolithography respectively, wherein the two measurement light beams are parallel with each other, and the two measurement light beams are respectively used as a first input light beam and a second input light beam of the laser phase measurement interferometer;
inputting the first input light beam having a frequency fs1 and with a s polarization state to the third polarized beam-splitting prism, reflected by the third polarized beam-splitting prism to the second polarized beam-splitting prism, and then reflected by the second polarized beam-splitting prism to the polarizer to form a first measurement light;
inputting the second input light beam having a frequency fs2 and with a s polarization state to the third polarized beam-splitting prism, reflected by the third polarized beam-splitting prism to the second polarized beam-splitting prism, and then reflected by the second polarized beam-splitting prism to the polarizer to form a second measurement light;
inputting a reference light beam homologous with the exposure light beams for laser interference photolithography as a third input light beam of the laser phase measurement interferometer, wherein the third input light beam having a frequency fs3 is input to the first wave plate, changed into a circular polarization state after passing through the first wave plate and incident on the first polarized beam-splitting prism, and split into a reflection reference light and a transmission reference light by the first polarized beam-splitting prism;
the reflection reference light passing through the fourth wave plate and propagating to the backward reflector, reflected back by the backward reflector and turned to the fourth wave plate so as to be changed into a p polarization state, and transmitted by the first polarized beam-splitting prism and the second polarized beam-splitting prism sequentially, and then passing through the polarizer to form a first reference light beam;
the transmitted reference light passing through the third wave plate and propagating to the reflector, reflected back by the reflector and turned to the third wave plate so as to be changed into a s polarization state and propagating to the first polarized beam-splitting prism, reflected by the first polarized beam-splitting prism to the second wave plate so as to be changed into a p polarization state, and then transmitted by the second polarized beam-splitting prism and passing through the polarizer to form a second reference light beam; and
combing the first measurement light and the first reference light beam to form one beam of interferometric optical signal to incident on the first photoelectric detector, and combing the second measurement light and the second reference light beam to form another beam of interferometric optical signal to incident on the second photoelectric detector, the first photoelectric detector and the second photoelectric detector respectively converting the received interferometric optical signals into electrical signals, and calculating on the electrical signals to obtain phases of the two exposure light beams for laser interference photolithography.