Radiation source for lithography process

Patent metadata

Field	Value
Publication number	US-2019155179-A1
Application number	US-201816117545-A
Country	US
Kind code	A1
Filing date	Aug 30, 2018
Priority date	Nov 21, 2017
Publication date	May 23, 2019
Grant date	—

Abstract

A method for a lithography exposure process is provided. The method includes irradiating a target droplet with a laser beam to create an extreme ultraviolet (EUV) light. The method further includes reflecting the EUV light with a collector. The method also includes discharging a cleaning gas over the collector through a gas distributor positioned next to the collector. A portion of the cleaning gas is converted to free radicals before the cleaning gas leaves the gas distributor, and the free radicals are discharged over the collector along with the cleaning gas.

First claim

What is claimed is:

1 . A method for a lithography exposure process, comprising:
irradiating a target droplet with a laser beam to create an extreme ultraviolet (EUV) light; reflecting the EUV light with a collector; and discharging a cleaning gas over the collector through a gas distributor positioned next to the collector, wherein a portion of the cleaning gas is converted to free radicals before the cleaning gas leaves the gas distributor, and the free radicals are discharged over the collector along with the cleaning gas.

2 . The method for a lithography exposure process as claimed in claim 1 , further comprising applying an electromagnetic radiant energy into the cleaning gas with an energy converter positioned in the gas distributor to convert the portion of the cleaning gas to the free-radicals.

3 . The method for a lithography exposure process as claimed in claim 1 , wherein the free radicals and the cleaning gas are supplied to a central area of the collector through which the laser beam passes the collector to irradiate the target droplet.

4 . The method for a lithography exposure process as claimed in claim 1 , wherein the free radicals and the cleaning gas are supplied to a peripheral area of the collector that is adjacent to a circumference of the collector.

5 . The method for a lithography exposure process as claimed in claim 1 , further comprising:
determining at least one contaminated area of the collector according to an estimated contamination status of the collector; wherein the free radicals and the cleaning gas are supplied to the contaminated area.

6 . The method for a lithography exposure process as claimed in claim 1 , further comprising applying a thermal energy into the cleaning gas with an energy converter to convert the portion of the cleaning gas to the free-radicals.

7 . The method for a lithography exposure process as claimed in claim 1 , further comprising:
reducing accumulated debris on the collector to a gaseous product with the free radicals; exhausting the gaseous product via an exhaust line; and heating up the exhaust line to a predetermined temperature that is above a melting point of the of the debris.

8 . The method for a lithography exposure process as claimed in claim 1 , wherein the cleaning gas comprises hydrogen, and the free radicals of the cleaning gas are configured to reduce debris comprising tin accumulated on the collector.

9 . The method for a lithography exposure process as claimed in claim 1 , further comprising:
supplying the free radicals and the cleaning gas over the collector multiple times, wherein a predetermined period is set between two of the supplies of the free radicals and the cleaning gas, and during the predetermined period the supply of the free radicals and the cleaning gas is paused.

10 . A method for lithography exposure process, comprising:
irradiating a target droplet with a laser beam to create an extreme ultraviolet (EUV) light; reflecting the EUV light with a collector; performing a lithography exposure process on a wafer with the EUV light which is reflected by the collector; and discharging a cleaning gas over the collector multiple times during the lithography exposure process, wherein a predetermined period is set between two of the supplies of the cleaning gas, and during the predetermined period the supply of the cleaning gas is paused.

11 . The method for a lithography exposure process as claimed in claim 10 , wherein the cleaning gas is supplied to a central area of the collector through which the laser beam passes the collector to irradiate the target droplet.

12 . The method for a lithography exposure process as claimed in claim 10 , wherein the cleaning gas is supplied to a peripheral area of the collector that is adjacent to a circumference of the collector.

13 . The method for a lithography exposure process as claimed in claim 10 , further comprising:
determining at least one contaminated area of the collector according to an archive database; wherein the cleaning gas is supplied to the contaminated area.

14 . The method for a lithography exposure process as claimed in claim 10 , further comprising heating up the cleaning gas before the cleaning gas is supplied to the collector.

15 . The method for a lithography exposure process as claimed in claim 10 , further comprising:
dissipating accumulated debris on the collector with the cleaning gas; exhausting the debris and the cleaning gas via an exhaust line; and heating up the exhaust line to a predetermined temperature that is above a melting point of the debris.

16 . The method for a lithography exposure process as claimed in claim 10 , further comprising:
applying energy into the cleaning gas to generate free radicals before the cleaning gas is supplied to the collector, wherein the energy comprises an electromagnetic radiant energy or a thermal energy; and discharging the free radicals along with the cleaning gas over the collector, wherein the free radicals chemically react with the accumulated debris on the collector.

17 . A radiation source for generating light for a lithography exposure process, comprising:
a target droplet generator configured to generate a target droplet; a preheated laser source configured to hit the target droplet and then generate a precursor target; a main laser source configured to generate a laser beam to convert the precursor target to an extreme ultraviolet (EUV) light; and a collector configured to collect and reflect the EUV light; a gas flowing path configured to discharge a cleaning gas to the collector; an energy converter connected to the gas flowing path; and a controller configured to control an energy applied into the cleaning gas in the gas flowing path from the energy converter to convert a portion of the cleaning gas in the gas flowing path into free radicals.

18 . The radiation source for generating light for a lithography exposure process as claimed in claim 17 , wherein the energy applied into the cleaning gas includes an electromagnetic radiant energy, and the energy converter includes an electrode configured to convert an electric energy to the electromagnetic radiant energy.

19 . The radiation source for generating light for a lithography exposure process as claimed in claim 17 , wherein the energy applied into the cleaning gas includes a thermal, and the energy converter includes a heating member configured to convert an electric energy to the thermal energy.

20 . The radiation source for generating light for a lithography exposure process as claimed in claim 17 , further comprising:
a flow rate regulator configured to adjust a flow rate of the cleaning gas supplied by the gas flowing path; wherein the controller is also configured to repeatedly turn on and turn off the flow rate regulator.

Assignees

• Taiwan Semiconductor Mfg Co Ltd

Inventors

• Wu Shang-Ying
• Chien Shang-Chieh
• Liu Bo-Tsun
• Chen Li-Jui
• Cheng Po-Chung

Classifications

• G03F7/70175

  Lamphouse reflector arrangements or collector mirrors, i.e. collecting light from solid angle upstream of the light source · CPC title

• G03F7/70025

  by lasers · CPC title

• G03F7/70033

  by plasma extreme ultraviolet [EUV] sources · CPC title

• G03F7/70925 Primary

  Cleaning, i.e. actively freeing apparatus from pollutants, e.g. using plasma cleaning · CPC title

• H05G2/0094

  Reduction, prevention or protection from contamination; Cleaning · CPC title