US 6,320,892 B1 · Energy efficient lithography laser

Abstract

An excimer laser system with an automatic fluorine control system to permit precise control of the fluorine concentration within an F2 “sweet spot” in a gas discharge laser chamber. This is done with a computer control system which monitors laser parameters, determines ΔE/ΔV, the change of pulse energy with voltage, and automatically and precisely controls the fluorine concentration based on ΔE/ΔV without the need to actually measure the fluorine concentration. The present invention is especially useful in lithography environments in which photo resist having a wide range of sensitivity are used. The present invention permits operation of the laser at substantially maximum efficiency over a wide range of pulse energy outputs.

Claims3

Dependent claims

A process for controlling a gas discharge comprising the steps of:

A) operating the laser at various F2 concentration levels and determining laser parameters to determine a preferred operating range;
B) determine ΔE/ΔV within said preferred operating range;
C) determine a ΔE/ΔV injection value, (ΔE/ΔV)i;
and
D) during laser operation inject a quantity of F2 when ΔE ΔV decreases to or below (ΔE/ΔV)i;
said process permitting said laser to operate over a wide range of pulse energy and repetition rate in order to accommodate, without substantial loss of laser efficiency or dose stability, changes in sensitivity of photo resist.

3 more elements

Dependencies are inferred from the claim text.

Facts

Application

09/420,297Filed 18 Oct 1999 · continuation in part

Priority

30 Jan 1998

Granted

20 Nov 2001

Term ends

Not estimatedThe source records don’t support an estimate.

Classification12 codes

G03F 7/70025
Production of exposure light, i.e. light sources: by lasers
G03F 7/70041
Production of exposure light, i.e. light sources: by pulsed sources, e.g. multiplexing, pulse duration, interval control or intensity control
G03F 7/70358
Mask projection systems: scanning exposure, i.e. relative movement of patterned beam and workpiece during imaging
G03F 7/70558
Exposure light control in all parts of the microlithographic apparatus, e.g. pulse length control or light interruption: dose control, i.e.…

Family

Application09/016,525Parent of this continuation-in-part · filed 30 Jan 1998

Application09/034,870Parent of this continuation-in-part · filed 4 Mar 1998

Application09/368,208Parent of this continuation-in-part · filed 4 Aug 1999

US 6,151,349 AParent of this continuation-in-part

US 6,005,879 AParent of this continuation-in-part

US 5,978,406 AParent of this continuation-in-part

US 6,320,892 B1This patent

From the US filing history. Foreign family members aren’t listed.

Energy efficient lithography laser

Life of this patent

Energy efficient lithography laser

Life of this patent

Abstract

Claims3