Determining moving properties of a target in an extreme ultraviolet light source

Patent metadata

Field	Value
Publication number	US-11758639-B2
Application number	US-202017416636-A
Country	US
Kind code	B2
Filing date	Jan 27, 2020
Priority date	Jan 30, 2019
Publication date	Sep 12, 2023
Grant date	Sep 12, 2023

Abstract

An apparatus includes: a diagnostic system configured to diagnostically interact with a current target ( 110 c ) traveling along a trajectory (TR) and before the current target enters a target space; a first detection apparatus ( 120 ) configured to detect first light; a second detection apparatus ( 130 ) configured to detect second light; and a control system ( 150 ) in communication with the first and second detection apparatuses. The first light includes: light ( 140 ) produced from an interaction between the current target and the diagnostic system, and light ( 142 ) emitted from a plasma produced by a previous target. The second light includes the light ( 142 ) emitted from the plasma produced by the previous target. The control system ( 150 ) is configured to: produce an analysis signal based on first and second signals produced from respective outputs of the first and second detection apparatuses; and estimate a property of the current target based on the produced analysis signal.

First claim

What is claimed is:

1. A method comprising:
enabling an interaction between a diagnostic system and a current target traveling along a trajectory toward a target space, the current target including a component that emits light when converted to plasma;
detecting first light at a first detection region, wherein the first light comprises light emitted from the plasma produced by a previous target and light produced from the enabled interaction between the current target and the diagnostic system;
detecting second light at a second detection region, wherein the second light comprises the light emitted from the previous target's plasma;
producing an analysis signal based on a first signal produced by the detected first light and a second signal produced by the detected second light; and
estimating a property of the current target based on the produced analysis signal.

2. The method of claim 1 , wherein the light emitted from the plasma produced by the target component comprises: extreme ultraviolet (EUV) light being in the EUV wavelength range and non-EUV light being outside of the EUV wavelength range.

3. The method of claim 1 , wherein detecting second light at the second detection region comprises suppressing at least a portion of the light produced from the interaction between the current target and the diagnostic system.

4. The method of claim 3 , wherein suppressing light produced from the interaction between the current target and the diagnostic system comprises filtering the light produced from the interaction between the current target and the diagnostic system based on one or more of: a spectral property, a polarization property, and/or a spatial property of the light produced from the interaction between the current target and the diagnostic system.

5. The method of claim 1 , wherein the interaction between the current target and the diagnostic system comprises:
a first interaction between the current target and a first diagnostic probe of the diagnostic system; and
a second interaction between the current target and a second diagnostic probe of the diagnostic system.

6. The method of claim 5 , wherein the second interaction between the current target and the second diagnostic probe occurs at a location and time that are distinct from the location and time at which the first interaction between the current target and the first diagnostic probe occurs.

7. The method of claim 1 , wherein enabling the interaction between the diagnostic system and the current target comprises directing the diagnostic system toward the current target so that the diagnostic system and the current target interact at a region along the current target trajectory.

8. The method of claim 7 , wherein directing the diagnostic system toward the current target comprises directing a diagnostic light beam toward the current target.

9. The method of claim 1 , wherein estimating the property of the current target comprises estimating one or more of:
an arrival time of the current target at a particular position in space;
a speed, a velocity, and/or an acceleration of the current target; and
a time interval between an arrival of the current target at a particular position in space and an arrival of another target at the particular position in space.

10. The method of claim 1 , further comprising adjusting one or more properties of a radiation pulse directed toward the target space if the estimated target property is outside an acceptable specification.

11. The method of claim 1 , wherein detecting the first and second light comprises detecting the first and second light during or after a preceding target has interacted with the prior radiation pulse.

12. The method of claim 1 , wherein the light emitted from the previous target's plasma has a spectral bandwidth that is substantially broader than a spectral bandwidth of the light produced from the interaction between the current target and the diagnostic system.

13. The method of claim 1 , wherein the light produced from the interaction between the current target and the diagnostic system includes light from the diagnostic system that is reflected or scattered from the current target.

14. The method of claim 1 , wherein producing the analysis signal from the first signal and the second signal comprises electronically subtracting the second signal from the first signal.

15. The method of claim 1 , wherein producing the analysis signal from the first signal and the second signal comprises digitizing the first signal and the second signal, and computing a difference between each time-stamped sample of the second digitized signal and the first digitized signal.

16. The method of claim 1 , wherein detecting second light at the second detection region comprises detecting an amount of the light produced from the enabled interaction between the current target and the diagnostic system, wherein the detected amount of the light produced from the enabled interaction between the current target and the diagnostic system at the second detection region is less than an amount of the light produced from the enabled interaction between the current target and the diagnostic system that is detected at the first detection region.

17. An apparatus comprising:
a diagnostic system configured to diagnostically interact with a current target traveling along a trajectory and before the current target enters a target space;
a first detection apparatus configured to detect first light comprising:
light produced from an interaction between the current target and the diagnostic system, and
light emitted from a plasma produced by a previous target;

a second detection apparatus configured to detect second light comprising the light emitted from the plasma produced by the previous target; and
a control system in communication with the first and second detection apparatuses and configured to:
produce an analysis signal based on first and second signals produced from respective outputs of the first and second detection apparatuses; and
estimate a property of the current target based on the produced analysis signal.

18. The apparatus of claim 17 , further comprising a target delivery system configured to release a plurality of targets each along a trajectory toward the target space, wherein each target includes a component that emits extreme ultraviolet (EUV) light when converted to plasma.

19. The apparatus of claim 17 , further comprising an optical source configured to produce radiation pulses directed toward the target space, wherein the plasma produced by the previous target is produced due to an interaction between the previous target and a prior radiation pulse.

20. The apparatus of claim 17 , wherein the diagnostic system comprises a diagnostic light beam, and the diagnostic light produced from the interaction between the current target and the diagnostic light beam comprises the diagnostic light beam that is reflected or scattered from the current target.

21. The apparatus of claim 17 , wherein the first detection apparatus comprises a first light detector, and the second detection apparatus comprises a second light detector.

22. The apparatus of claim 21 , wherein each of the first light detector and the second light detector comprises one or more: photodiodes, the output of which is a voltage signal related to current produced from the detected light; photo-transistors, light-dependent resistors, and photomultiplier tubes.

23. The apparatus of cla

Assignees

• Asml Netherlands Bv

Inventors

• Rafac Robert Jay

Classifications

• H05G2/0084

  Control of the laser beam · CPC title

• H05G2/0027 Primary

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

• G01N21/6402

  Atomic fluorescence; Laser induced fluorescence · CPC title

• H05G2/008 Primary

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

• H05G2/006

  Electricity · mapped topic