Target trajectory metrology in an extreme ultraviolet light source

Patent metadata

Field	Value
Publication number	US-10149375-B2
Application number	US-201615265373-A
Country	US
Kind code	B2
Filing date	Sep 14, 2016
Priority date	Sep 14, 2016
Publication date	Dec 4, 2018
Grant date	Dec 4, 2018

Abstract

A method is described for measuring a moving property of a target. The method includes: forming a remaining plasma that at least partially coincides with an extended target region, the remaining plasma being a plasma formed from an interaction between a prior target and a prior radiation pulse in a target space; releasing a current target along a trajectory toward the target space that is at least partly overlapping the extended target region; determining one or more moving properties of the current target when the current target is within the extended target region and after a prior and adjacent target has interacted with a prior radiation pulse in the target space; and if any of the determined one or more moving properties of the current target are outside an acceptable range, then adjusting one or more characteristics of a radiation pulse directed toward the target space.

First claim

What is claimed is:

1. A method of measuring a moving property of a target as it travels along its trajectory in a laser produced plasma extreme ultraviolet light source, the method comprising:
forming a remaining plasma that at least partially coincides with an extended target region, the remaining plasma being a plasma formed from an interaction between a prior target and a prior radiation pulse in a target space, wherein the extended target region is that region in which plasma pushback forces affect a target and cause motion of the target to deviate from a motion;
releasing a current target along a trajectory toward the target space that is at least partly overlapping the extended target region, the current target including a component that emits extreme ultraviolet (EUV) light when converted to plasma;
determining one or more moving properties of the current target when the current target is within the extended target region and after a prior and adjacent target has interacted with a prior radiation pulse in the target space, wherein determining includes detecting one or more diagnostic interactions with the current target while the current target is within the extended target region and determining one or more moving properties of the current target comprises determining one or more of a speed of the current target, a velocity of the current target, and/or an acceleration of the current target; and
if any of the determined one or more moving properties of the current target are outside an acceptable range, then adjusting one or more characteristics of a radiation pulse directed toward the target space.

2. The method of claim 1 , further comprising interacting the radiation pulse with a present target in the target space, wherein the present target is either the current target that has entered the target space or another target that has entered the target space, wherein the other target enters the target space at a time that follows the time when the current target enters the target space.

3. The method of claim 2 , wherein adjusting the one or more characteristics of the radiation pulse directed toward the target space causes an adjustment in a relative position between the radiation pulse and the present target.

4. The method of claim 1 , wherein determining one or more moving properties of the current target when the current target is within the extended target region comprises determining a direction of the trajectory of the current target.

5. The method of claim 2 , wherein the radiation pulse delivers energy to the present target to modify a geometric distribution of the present target, the method further comprising, after directing the radiation pulse toward the present target, directing a main radiation pulse toward the present target to thereby convert at least part of the present target into plasma that emits extreme ultraviolet light.

6. The method of claim 1 , further comprising analyzing the determined one or more moving properties, wherein adjusting the one or more characteristics of the radiation pulse is based on the analysis of the determined one or more moving properties of the current target.

7. The method of claim 1 , wherein adjusting one or more characteristics of the radiation pulse comprises adjusting one or more of a timing of a release of the radiation pulse and a direction at which the radiation pulse travels.

8. The method of claim 1 , wherein determining the one or more moving properties of the current target comprises:
detecting a first diagnostic interaction between a first diagnostic light beam and the current target at a first location within the extended target region;
detecting a second diagnostic interaction between a second diagnostic light beam and the current target at a second location within the extended target region, the second location being distinct from the first location; and
determining the one or more moving properties based on the detections of the first and second diagnostic interactions.

9. The method of claim 8 , wherein determining the one or more moving properties of the current target comprises:
directing the first diagnostic light beam toward the current target at the first location; and
directing the second diagnostic light beam toward the current target at the second location.

10. The method of claim 9 , wherein:
directing the first diagnostic beam toward the current target at the first location comprises directing the first diagnostic beam along a first direction toward the current target; and
directing the second diagnostic beam toward the current target at the second location comprises directing the second diagnostic beam along a second direction toward the current target, the second direction is not parallel with the first direction.

11. The method of claim 9 , wherein:
detecting the first diagnostic interaction comprises detecting light that is produced from the diagnostic interaction between the current target and the first diagnostic beam at a first time;
detecting the second diagnostic interaction comprises detecting light that is produced from the diagnostic interaction between the current target and the second diagnostic beam at a second time that is distinct from the first time; and
determining the one or more moving properties of the current target is based on an analysis of the detections of the light.

12. The method of claim 11 , wherein detecting the light comprises detecting a one-dimensional aspect of the light and producing a one-dimensional signal.

13. A method of measuring a moving property of a target as it travels along its trajectory in a laser produced plasma extreme ultraviolet light source, the method comprising:
forming a remaining plasma that at least partially coincides with an extended target region, the remaining plasma being a plasma formed from an interaction between a prior target and a prior radiation pulse in a target space;
releasing a current target along a trajectory toward the target space that is at least partly overlapping the extended target region, the current target including a component that emits extreme ultraviolet (EUV) light when converted to plasma;
determining one or more moving properties of the current target when the current target is within the extended target region and after a prior and adjacent target has interacted with a prior radiation pulse in the target space, wherein determining the one or more moving properties of the current target comprises:
detecting a first interaction between a first diagnostic light beam and the current target at a first location within the extended target region;
detecting a second interaction between a second diagnostic light beam and the current target at a second location within the extended target region, the second location being distinct from the first location; and
determining the one or more moving properties based on the detections of the first and second interactions;
if any of the determined one or more moving properties of the current target are outside an acceptable range, then adjusting one or more characteristics of a radiation pulse directed toward the target space; and
detecting a third interaction between a third diagnostic light beam and the current target at a third location within the extended target region, the third location being distinct from the first and second locations.

14. An apparatus comprising:
a chamber that defines a target space that is at least partly overlapping with an extended target region, wherein the extended target region is that region in which plasma pushback forces affect a target and cause motion of the target to deviat

Assignees

• Asml Netherlands Bv

Inventors

• Price Michael Leslie
• Stinson Cory Alan
• Mitry Mark Joseph

Classifications

• H01S3/2366

  comprising a gas as the active medium (H01S3/10092, H01S3/2383 take precedence) · CPC title

• H05G2/008 Primary

  involving an energy-carrying beam in the process of plasma generation · CPC title

• H05G2/0027 Primary

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