Droplet splash control for extreme ultraviolet photolithography

Patent metadata

Field	Value
Publication number	US-12411419-B2
Application number	US-202418611440-A
Country	US
Kind code	B2
Filing date	Mar 20, 2024
Priority date	Jun 15, 2020
Publication date	Sep 9, 2025
Grant date	Sep 9, 2025

Abstract

A photolithography system utilizes tin droplets to generate extreme ultraviolet radiation for photolithography. The photolithography system irradiates the droplets with a laser. The droplets become energized and emit extreme ultraviolet radiation. A collector reflects the extreme ultraviolet radiation toward a photolithography target. The photolithography system reduces splashback of the tin droplets onto the receiver by generating a net electric charge within the droplets using a charge electrode and decelerating the droplets by applying an electric field with a counter electrode.

First claim

The invention claimed is:

1. A photolithography system, comprising:
a droplet generator configured to output a stream of droplets;
a droplet receiver positioned to receive and collect the droplets;
a laser configured to irradiate the droplets at an irradiation location between the droplet generator and the droplet receiver;
a collector configured to receive extreme ultraviolet radiation from the droplets and to reflect the extreme ultraviolet radiation for use in photolithography;
a charge electrode positioned between the irradiation location and the droplet receiver;
a counter electrode positioned within the droplet receiver downstream from the charge electrode with respect to a direction of travel of the droplets;
a droplet sensor positioned within the droplet receiver and configured to generate sensor signals indicative of a speed of the droplets within the droplet sensor; and
a control system configured to apply a first voltage to the charge electrode and a second voltage to the counter electrode selected to reduce a speed of the droplets within the droplet receiver, the control system including a machine learning model configured to analyze the sensor signals and to generate voltage adjustment data, the control system configured adjust one or both of the first and second voltages responsive to the sensor signals.

2. The photolithography system of claim 1 , wherein the first voltage and the second voltage have a same polarity.

3. The photolithography system of claim 2 , wherein the second voltage has a greater magnitude than the first voltage.

4. The photolithography system of claim 1 , wherein the charge electrode is an annular electrode.

5. The photolithography system of claim 4 , wherein the charge electrode is an annular electrode.

6. The photolithography system of claim 1 , wherein the collector mirror includes an aperture adjacent to the laser.

7. The photolithography system of claim 1 , wherein the control system adjusts one or both of the first and second voltages based on the voltage adjustment data.

8. The photolithography system of claim 7 , wherein the machine learning model includes a neural network.

9. The photolithography system of claim 7 , wherein the machine learning model includes a decision tree model.

10. A method comprising:
outputting a stream of droplets from a droplet generator;
irradiating, with a laser, the droplets at an irradiation location between the droplet generator and a droplet receiver;
generating a net charge in the droplets downstream from the irradiation location;
receiving the droplets in the droplet receiver downstream from the irradiation location;
generating, with a droplet sensor positioned within the droplet receiver, sensor signals indicative of a speed of the droplets within the droplet receiver;
generating, with a machine learning model, electric field adjustment data by analyzing the sensor signals; and
reducing a speed of the droplets within the droplet receiver by generating an electric field within the droplet receiver based on the electric field adjustment data.

11. The method of claim 10 , wherein generating the net charge in the droplets includes applying a first voltage to a charge electrode positioned upstream from the droplet receiver.

12. The method of claim 11 , wherein generating the electric field includes applying a second voltage to a counter electrode.

13. The method of claim 12 , further comprising adjusting, with the control system, the second voltage based on the electric field adjustment data.

14. The method of claim 13 , further comprising generating the electric field adjustment data based, at least in part, on a mass of the droplets.

15. The method of claim 13 , further comprising generating the electric field adjustment data based, at least in part, on a previous speed of the droplets.

16. The method of claim 12 , further comprising generating extreme ultraviolet radiation from the droplets by irradiating the droplets with the laser.

17. The method of claim 16 , further comprising performing photolithography with the extreme ultraviolet radiation.

18. A method, comprising:
outputting a plurality of droplets with a droplet generator;
generating extreme ultraviolet radiation by irradiating the droplets with a laser at an irradiation location between the droplet generator and a droplet receiver;
irradiating an integrated circuit with the extreme ultraviolet radiation;
applying a first voltage to an annular charge electrode surrounding a path of travel of the droplets and positioned between the irradiation location and the droplet receiver;
generating, with a droplet sensor positioned within the droplet receiver, sensor signals indicative of a speed of the droplets within the droplet receiver;
reducing a speed of the droplets by applying a second voltage to a counter electrode positioned within the droplet receiver downstream from the charge electrode;
collecting the droplets in the droplet receiver; and
adjusting the second voltage in response to the sensor signals.

19. The method of claim 18 , further comprising:
passing the sensor signals to a control system; and
adjusting, with the control system, one or both of the first and second voltages based on the sensor signals.

20. The method of claim 18 , wherein the counter electrode is an annular electrode.

Assignees

• Taiwan Semiconductor Mfg Co Ltd

Inventors

• Shih Po-Ming
• Liao Chi-Hung

Classifications

• H05G2/0027

  Arrangements for controlling the supply; Arrangements for measurements · CPC title

• G03F7/70191

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

• G03F7/70033

  by plasma extreme ultraviolet [EUV] sources · CPC title

• G03F7/70916

  Pollution mitigation, i.e. mitigating effect of contamination or debris, e.g. foil traps · CPC title

• G01P5/08

  by measuring variation of an electric variable directly affected by the flow, e.g. by using dynamo-electric effect · CPC title