Scanning interference lithographic system

Patent metadata

Field	Value
Publication number	US-12189300-B2
Application number	US-202017767416-A
Country	US
Kind code	B2
Filing date	Oct 23, 2020
Priority date	Oct 31, 2019
Publication date	Jan 7, 2025
Grant date	Jan 7, 2025

Abstract

Disclosed is a scanning interference photolithography system, comprising a heterodyne optical path, a first interference optical path, a second interference optical path, a motion platform and a control subsystem, wherein a substrate is carried on the motion platform, a displacement measurement interferometer is used to measure the displacement of the motion platform, a first light beam and a second light beam are focused on the substrate for interference exposure; the control subsystem generates instructions according to various measurement information, adjusts angles of corresponding devices or the phase of a light beam, and locks the phase shift of interference exposure fringes of the first light beam and the second light beam. The system has a high precision of fringe pattern locking and a high laser utilization rate, and can be used for producing a large-area high-precision dense grating line gradient periodic grating.

First claim

The invention claimed is:

1. A scanning interference photolithography system, comprising:
a heterodyne optical path, a laser light emitted by a laser is split into a zero-order diffracted light and a first-order diffracted light by a first phase modulator, wherein the first-order diffracted light is sequentially reflected by a third mirror, a fourth mirror and a third universal mirror, is transmitted by a fourth lens, and becomes a heterodyne beam of a heterodyne phase meter;
a first interference optical path, the zero-order diffracted light split by the first phase modulator is reflected to a grating beam splitter by a first mirror, and is split into a first light beam and a second light beam by the grating beam splitter, wherein the first light beam sequentially passes through a third phase modulator, is reflected by a second universal mirror and is transmitted by a second lens to a splitting prism, the light transmitted by the splitting prism travels to an angle measurement module, the light reflected by the splitting prism travels to a beam extraction mirror, the light transmitted by the beam extraction mirror travels to a third lens and is transmitted by the third lens, and then is focused on a substrate, wherein the light reflected by the beam extraction mirror is a first input beam of the heterodyne phase meter;
a second interference optical path, the second light beam split by the grating beam splitter sequentially passes through a second phase modulator, is reflected by a second mirror and a first universal mirror, and is transmitted by a first lens to the splitting prism, and the light reflected by the splitting prism travels to the angle measurement module, the light transmitted by the splitting prism travels to the beam extraction mirror, and the light transmitted by the beam extraction mirror travels to the third lens and is transmitted by the third lens, and then is focused on the substrate, wherein the light reflected by the beam extraction mirror is a second input beam of the heterodyne phase meter;
a motion platform, the substrate is carried on the motion platform, a displacement measurement interferometer is used to measure the displacement of the motion platform, the first light beam and the second light beam are focused on the substrate for interference exposure; and
a control subsystem, two interference measurement electrical signals are obtained by the heterodyne phase meter from the first input beam, the second input beam and the heterodyne beam and are transmitted to a signal receiving part, angle information of the first light beam and the second light beam are obtained by the angle measurement module and are transmitted to the signal receiving part, and displacement information of the motion platform is measured by the displacement measurement interferometer and is transmitted to the signal receiving part, and the information is then transmitted to a processor from the signal receiving part to perform calculation so as to obtain information about phase shift of exposure fringe, the processor generates a compensation instruction and transmits it to a phase modulation actuator, and the phase modulation actuator sends the compensation instruction to the first phase modulator, the second phase modulator and the third phase modulator to perform phase modulation, so as to complete the locking of the phase shift of exposure fringe; the processor generates a control command and transmits it to a driver to adjust angles of the first universal mirror, the second universal mirror and the third universal mirror so as to adjust the angle at which the first light beam and the second light beam are focused on the substrate for exposure, meanwhile, a reference light and a measurement light remain combined, such that a beam offset does not affect an intensity change of a phase measurement signal during a variable period, and the heterodyne phase meter based on heterodyne measurement principle measures the phase between the exposure beams, modulates the phase and enables the phase of the exposure beams to be locked to a grating substrate, and realizes control of interference fringes,
wherein the heterodyne phase meter comprises a first wave plate, a first polarization splitting prism, a second wave plate, a second polarization splitting prism, a polarizer, a first photodetector, a second photodetector, a third polarization splitting prism, a mirror, a third wave plate, a retroreflector and a fourth wave plate, and
wherein the optical path of the heterodyne phase meter is as follows: the first input beam in an s polarization state is incident from an incident surface of the third polarization splitting prism, is sequentially reflected by the third polarization splitting prism and the second polarization splitting prism, and then is transmitted by the polarizer to form a first measurement light; the second input beam, which is parallel to the first input beam, is incident from the incident surface of the third polarization splitting prism in the s polarization state, is sequentially reflected by the third polarization splitting prism and the second polarization splitting prism, and is then transmitted by the polarizer to form a second measurement light.

2. The scanning interference photolithography system of claim 1 , further comprising a base and a vibration isolator, wherein the heterodyne optical path, the first interference optical path, the second interference optical path, the motion platform and the control subsystem are disposed on the base, and the vibration isolator is mounted at bottom of the base.

3. The scanning interference photolithography system of claim 1 ,
wherein the optical path of the heterodyne phase meter is further as follows:
a heterodyne light beam is incident from the first wave plate, is changed into a circular polarization state after being transmitted by the first wave plate and incidents onto the first polarization splitting prism, the light reflected by the first polarization splitting prism is transmitted to the retroreflector through the fourth wave plate, reflected by the retroreflector, then turns back, and is changed into a p polarization state after being transmitted by the fourth wave plate, then the light is sequentially transmitted by the first polarization splitting prism, the second polarization splitting prism, and the polarizer to form a first reference light, the light transmitted by the first polarization splitting prism is transmitted to the mirror through the third wave plate, reflected back to the third wave plate by the mirror, and changed into the s polarization state to the first polarization splitting prism after being transmitted by the third wave plate, then it is changed into the p polarization state after being reflected by the first polarization splitting prism and transmitted by the second wave plate, then it is sequentially transmitted by the second polarization splitting prism and the polarizer to form a second reference light;
the first measurement light combines with the first reference light to form an interference measurement signal, which is incident to the first photodetector; the second measurement light combines with the second reference light to form another interference measurement signal, which is incident to the second photodetector;
the first photodetector and the second photodetector convert the received interference measurement signal into an electrical signal and then transmit it to the signal receiving part, respectively.

4. The scanning interference photolithography system of claim 3 , wherein the first wave plate, the third wave plate and the fourth wave plate are quarter wave plates.

5. The scanning interference photolithography system of claim 3 , wherein the second wave plate is a half wave plate.

6. The scanning interfe

Assignees

• Univ Tsinghua
• Beijing U Prec Tech Co Ltd
• Tsinghua Univ Beijing U Precision Tech Co Ltd

Inventors

• Wang Leijie
• Zhu Yu
• Zhang Ming
• Xu Jitao
• Cheng Rong
• Hao Jiankun
• Yang Kaiming
• Li Xin
• Gao Siqi
• Fan Yujiao

Classifications

• G03F7/7085

  Detection arrangement, e.g. detectors of apparatus alignment possibly mounted on wafers, exposure dose, photo-cleaning flux, stray light, thermal load · CPC title

• G03F7/70191

  Optical correction elements, filters or phase plates for controlling intensity, wavelength, polarisation, phase or the like · CPC title

• G03F7/70025 Primary

  by lasers · CPC title

• G03F7/70408 Primary

  Interferometric lithography; Holographic lithography; Self-imaging lithography, e.g. utilizing the Talbot effect · CPC title

• G03F7/70725

  control · CPC title