Inspection of a lithographic mask that is protected by a pellicle

Patent metadata

Field	Value
Publication number	US-10156785-B2
Application number	US-201615177226-A
Country	US
Kind code	B2
Filing date	Jun 8, 2016
Priority date	Jul 23, 2013
Publication date	Dec 18, 2018
Grant date	Dec 18, 2018

Abstract

A system and a method for evaluating a lithography mask, the system may include: (a) electron optics for directing primary electrons towards a pellicle that is positioned between the electron optics and the lithography mask; wherein the primary electrons exhibit an energy level that allows the primary electrons to pass through the pellicle and to impinge on the lithographic mask; (b) at least one detector for detecting detected emitted electrons and for generating detection signals; wherein detected emitted electrons are generated as a result of an impingement of the primary electrons on the lithographic mask; and (c) a processor for processing the detection signals to provide information about the lithography mask.

First claim

The invention claimed is:

1. A method for evaluating a lithography mask, the method comprising:
directing, by electron optics, primary electrons towards a pellicle that is positioned between the electron optics and the lithography mask; wherein at least a portion of the primary electrons pass through the pellicle and impinge on the lithography mask;
detecting, by at least one detector, detected emitted electrons and generating detection signals; wherein the detected emitted electrons are secondary electrons that are emitted from the pellicle due to an interaction of backscattered electrons with the pellicle, wherein the backscattered electrons are generated as a result of an impingement of the portion of the primary electrons on the lithography mask, and the secondary electrons are generated as a result of an impingement of the backscattered electrons on the pellicle, the backscattered electrons traveling from emission points on the lithography mask to impingement points on a backside of the pellicle, and the secondary electrons traveling from emission points on a frontside of the pellicle to the at least one detector; and
processing, by a processor, the detection signals to provide information about the lithography mask.

2. A method for evaluating a lithography mask, the method comprising:
directing, by electron optics, primary electrons towards a pellicle that is positioned between the electron optics and the lithography mask, wherein at least a portion of the primary electrons pass through the pellicle and impinge on the lithography mask;
masking secondary electrons emitted from the pellicle due to an interaction of the primary electrons with the pellicle;
detecting, by at least one detector, detected emitted electrons and generating detection signals, wherein the detected emitted electrons are detected secondary electrons that are emitted from the pellicle due to an interaction of backscattered electrons with the pellicle, wherein the backscattered electrons are generated as a result of an impingement of the portion of the primary electrons on the lithography mask, and the detected secondary electrons are generated as a result of an impingement of the backscattered electrons on the pellicle; and
processing, by a processor, the detection signals to provide information about the lithography mask.

3. The method according to claim 1 , further comprising masking the backscattered electrons passing through the pellicle.

4. The method according to claim 1 , further comprising masking secondary electrons emitted from the pellicle due to an interaction of the primary electrons with the pellicle and masking the backscattered electrons passing through the pellicle.

5. The method according to claim 1 , further comprising imaging the plane of the pellicle on the at least one detector.

6. A system for evaluating a lithography mask, the system comprising:
electron optics for directing primary electrons towards a pellicle that is positioned between the electron optics and the lithography mask; wherein the primary electrons exhibit an energy level that allows at least a portion of the primary electrons to pass through the pellicle and to impinge on the lithography mask;
at least one detector for detecting detected emitted electrons and for generating detection signals; wherein the detected emitted electrons are secondary electrons that are emitted from the pellicle due to an interaction of backscattered electrons with the pellicle, wherein the backscattered electrons are generated as a result of an impingement of the portion of the primary electrons on the lithography mask, and the secondary electrons are generated as a result of an impingement of the backscattered electrons on the pellicle, the backscattered electrons traveling from emission points on the lithography mask to impingement points on a backside of the pellicle, and the secondary electrons traveling from emission points on a frontside of the pellicle to the at least one detector; and
a processor for processing the detection signals to provide information about the lithography mask.

7. The system according to claim 6 , wherein the system is arranged to mask secondary electrons emitted from the pellicle due to an interaction of the primary electrons with the pellicle.

8. The system according to claim 6 , wherein the system is arranged to mask the backscattered electrons passing through the pellicle.

9. The system according to claim 6 , wherein the system is arranged to mask secondary electrons emitted from the pellicle due to an interaction of the primary electrons with the pellicle and to mask the backscattered electrons passing through the pellicle.

10. The system according to claim 6 , wherein the electron optics is arranged to image the plane of the pellicle on the at least one detector.

Assignees

• Applied Materials Israel Ltd

Inventors

• Litman Alon
• Dodzin Nir Ben-David
• Karabekov Albert
• Goldenshtein Alex

Classifications

• H01J2237/164

  Particle-permeable windows · CPC title

• H01J2237/2449

  Detector devices with moving charges in electric or magnetic fields · CPC title

• G03F1/86 Primary

  by charged particle beam [CPB] · CPC title

• G03F1/62

  Pellicles, e.g. pellicle assemblies, e.g. having membrane on support frame; Preparation thereof · CPC title

• H01J2237/2817

  Pattern inspection · CPC title