LITHOGRAPHIC THERMAL DISTORTION COMPENSATION WITH THE USE OF MACHINE LEARNING

• US 20180275525A1
• Filed: 03/26/2018
• Published: 09/27/2018
• Est. Priority Date: 03/24/2017
• Status: Active Grant

• Current Assignee: Nikon Research Corporation Of America (Nikon Corporation)
• Original Assignee: Nikon Research Corporation Of America (Nikon Corporation)
• Inventors: Bow, Travis, Hashemi, Fardad, Pang, Henry Kin Heng
• Granted Patent: US 10,444,643 B2
• Time in Patent Office: Days
• CPC Class Codes: G03F 7/705 Modelling or simulating from physical phenomena up to complete wafer processes or whole workflow in wafer productions
• CPC Class Codes: G03F 7/70516 Calibration of components of the microlithographic apparatus, e.g. light sources, addressable masks or detectors
• CPC Class Codes: G03F 7/70725 control
• CPC Class Codes: G03F 7/70775 Position control, e.g. interferometers or encoders for determining the stage position
• CPC Class Codes: G03F 7/7085 Detection arrangement, e.g. detectors of apparatus alignment possibly mounted on wafers, exposure dose, photo-cleaning flux, stray light, thermal load
• CPC Class Codes: G03F 7/70858 Environment aspects, e.g. pressure of beam-path gas, temperature pollution aspects G03F7/70916
• CPC Class Codes: G03F 7/70875 Temperature, e.g. temperature control of masks or workpieces via control of stage temperature
• CPC Class Codes: G03F 7/70891 Temperature

Abstract

Lithographic exposure tool and method for operating thereof that includes modification of the tool (assessed based on the measurements of geometrical distortions caused, in the tool, by the exposure process and used to train the exposure tool) to ensure that such geometrical distortions are reduced for any chosen exposure process. The method includes processing first data (representing distortions caused by initial exposure run(s)) to estimate second data representing distortions that would occur for another exposure run); and forming a modified exposure tool by changing at least one of a) a geometrical path is a path along which the workpiece stage is repositioned during the operation of the exposure tool; b) one or more of a presence, position, orientation, size and shape of an optical component of an optical projection sub-system of the optical system of the exposure tool; and c) a parameter of scanning synchronization of the exposure tool.

Claims

1. A lithographic exposure tool, comprising

an optical system configured to expose a workpiece to a dose of radiation to form a predetermined image thereon;

a sensor system in operable cooperation with at least one sub-system of the exposure tool, said sensor system configured to measure data representing a first change in mutual orientation of first and second components of said sub-system for each of a plurality of values of a parameter of an exposure process; and

a first electronic circuitry in operable communication with a tangible storage medium, the storage medium containing program code which, when run by the electronic circuitry, causes the electronic circuitry

to estimate a second change in the mutual orientation for a supplementary value of the parameter based on data acquired from the sensor system and to generate a value of estimated second change;

and

a second electronic circuitry configured

to modify the exposure tool, based on said value of the estimated change, by changing a geometrical path to from a modified exposure tool, and

to operate the modified exposure tool while having a value of a third change in the mutual orientation be smaller than the value of the estimated second change, the third change being a change in the mutual orientation measured with the sensor system during operation of the modified exposure tool,

wherein the geometrical path is a path along which a movable stage of said exposure tool, carrying the workpiece during the operation of the exposure tool, is repositioned during the operation of the exposure tool.

2. A lithographic exposure tool according to claim 1, wherein said first and second components include mirrors of an optical interferometer portion of the exposure tool, and said second change represents a change is mutually-orthogonal positioning of said mirrors.

3. A lithographic exposure tool according to claim 1, wherein the supplementary value is not part of said plurality of values.

4. A lithographic exposure tool according to claim 1, wherein said program code includes

program code for operating the exposure tool according to a schedule of said exposure process at the highest value of said dose occurring in a production environment for a first duration of time;

program code for keeping the exposure tool in a stationary mode without movement present between components of the exposure tool for a second duration of time;

and

program code for operating the exposure tool according to the schedule at a zero exposure dose for a third duration of time.

5. A lithographic exposure tool according to claim 1, wherein said machine learning electronic circuitry is configured to compensate for said second change by changing at least one of a) one or more of a presence, position, orientation, size and shape of an optical component of an optical projection sub-system of the optical system of the exposure tool, and b) a parameter of scanning synchronization of the exposure tool.

8. A method according to claim 1, further comprising positioning sensors from said multiplicity of sensors at locations defined, at said at least one sub-system of the exposure tool, such that readings of temperature produced by said sensors are generated either before or after a moment when the first change occurred but not at said moment.

9. A method according to claim 1, wherein the first change in said mutual orientation includes at least one of i) a change of at least one of mutual position and orientation of interferometer mirrors of the exposure tool;

ii) at least one of geometrical distortion and changes of an optical property of a lens of the exposure tool;

iii) a change of at least one of position and orientation of the workpiece stage with respect to a reference location identified at the exposure tool;

iv) a geometrical distortion of a mount hardware, carrying a sensor from said multiplicity, occurring with respect to the reference location.

6. A method for operating a lithographic exposure tool, comprising:

exposing, through an optical projection sub-system of an optical system of the exposure tool, a workpiece disposed at a workpiece stage of the exposure tool to a dose of radiation to form a pre-determined image thereon;

with a multiplicity of sensors, operably cooperated with at least one sub-system of the exposure tool, measuring a first change in mutual orientation measuring a change in mutual orientation of first and second components of said at least one sub-system for a plurality of values of a parameter of said exposing, to produce first data representing the first change;

processing the first data with first electronic circuitry to estimate a second change in said mutual orientation, the second change caused by a supplementary value of said parameter;

transforming the exposure tool to form a modified exposure tool by changing at least one of

a) a geometrical path is a path along which the workpiece stage is repositioned during the operation of the exposure tool;

b) one or more of a presence, position, orientation, size and shape of an optical component of an optical projection sub-system of the optical system of the exposure tool; and

c) a parameter of scanning synchronization of the exposure tool;

exposing, through an optical projection sub-system of an optical system of the modified exposure tool, said workpiece to the dose of radiation.

7. A method according to claim 6, further comprising

measuring a third change in the mutual orientation with said multiplicity of sensors;

and

producing a report showing a difference between values of the second and third changes.