Method of temperature compensation in high power focusing system for EUV LPP source

Patent metadata

Field	Value
Publication number	US-9541838-B2
Application number	US-201615011218-A
Country	US
Kind code	B2
Filing date	Jan 29, 2016
Priority date	Sep 4, 2013
Publication date	Jan 10, 2017
Grant date	Jan 10, 2017

Abstract

Method of temperature compensating a focusing system in which a temperature of a thermal lens compensation plate is regulated based on an optical absorption of the thermal lens compensation plate with optical absorption being determined based at least in part on an expected end-of-lifetime value for focus lens optical absorption. A value representative of cumulative time in use of the focusing systems is determined and the temperature of the thermal lens compensation plate is increased to a temperature based at least in part on said cumulative time in use.

First claim

What is claimed is:

1. A method of temperature compensating a focusing system, the method comprising the steps of:
regulating a temperature of a thermal lens compensation plate to a first temperature, said first temperature being based on an optical absorption of said thermal lens compensation plate, said optical absorption having been determined based at least in part on an expected end-of-lifetime value for focus lens optical absorption for a final focus lens comprising part of said focusing system;
determining a value representative of cumulative time in use of said focusing system; and
adjusting said temperature of said thermal lens compensation plate to a second temperature higher than said first temperature, said second temperature having a value based at least in part on said cumulative time in use.

2. A method as claimed in claim 1 wherein said determining step and said adjusting step are carried out periodically.

3. A method as claimed in claim 1 wherein said determining step and said adjusting step are carried out substantially continuously.

Assignees

• Asml Netherlands Bv

Inventors

• Ershov Alexander I

Classifications

• G03F7/70033

  by plasma extreme ultraviolet [EUV] sources · CPC title

• G03F7/70341

  Details of immersion lithography aspects, e.g. exposure media or control of immersion liquid supply (chemical composition of immersion liquids G03F7/2041) · CPC title

• G03F7/70875

  Temperature, e.g. temperature control of masks or workpieces via control of stage temperature · CPC title

• G03F7/70041 Primary

  by pulsed sources, e.g. multiplexing, pulse duration, interval control or intensity control · CPC title

• G03F7/70008 Primary

  Production of exposure light, i.e. light sources · CPC title