Methods of defect inspection for photomasks

Patent metadata

Field	Value
Publication number	US-9739723-B1
Application number	US-201615191209-A
Country	US
Kind code	B1
Filing date	Jun 23, 2016
Priority date	Feb 22, 2016
Publication date	Aug 22, 2017
Grant date	Aug 22, 2017

Abstract

A method of defect inspection for a photomask is provided. According to the method, a light transmittance correction is performed to reduce a light transmittance of a calibration key pattern region of a photomask including a field region and the calibration key pattern region to the light transmittance of the field region. Light calibration is performed using the calibration key pattern region having corrected light transmittance. Defect inspection for the field region is performed by applying a result of the light calibration.

First claim

What is claimed is:

1. A method of defect inspection for a photomask, the method comprising:
obtaining registration errors existing in a field region of the photomask, wherein the photomask includes the field region and a calibration key pattern region;
obtaining a first light transmittance of the field region;
performing registration correction by irradiating a first laser beam onto the field region;
obtaining a first transmittance reduction in the field region by the registration correction;
obtaining a second light transmittance in the field region by using the first transmittance reduction;
performing light transmittance correction to the calibration key pattern region so that the calibration key pattern region has light transmittance substantially equal to the second light transmittance;
performing light calibration using the corrected calibration key pattern region to obtain a light calibration result; and
performing defect inspection to the field region by using the light calibration result.

2. The method of claim 1 , wherein the first laser beam forms local first deformation elements in the field region to compensate for the registration errors.

3. The method of claim 2 , wherein the first deformation elements change the first light transmittance of the field region to the second light transmittance.

4. The method of claim 1 , wherein the performing of the light transmittance correction includes forming second deformation elements in the calibration key pattern region.

5. The method of claim 4 , wherein the second deformation elements are formed by irradiating a second laser beam onto the calibration key pattern region.

6. The method of claim 4 , wherein the performing of the light transmittance correction comprises:
obtaining a third light transmittance of the calibration key pattern region before the light transmittance correction;
calculating a second transmittance reduction using a difference between the second light transmittance and third light transmittance; and
irradiating a second laser beam so that the second deformation elements are formed to reduce the third light transmittance of the calibration key pattern region to a fourth transmittance.

7. A method of defect inspection for a photomask, the method comprising:
performing registration correction by irradiating a first laser beam onto a field region of the photomask to form a registration corrected field region, wherein the photomask includes the field region and a calibration key pattern region;
performing light transmittance correction to reduce light transmittance of the calibration key pattern region;
performing light calibration using the reduced light transmittance of the calibration key pattern region to obtain a result of the light calibration; and
performing defect inspection to the registration corrected field region by applying the result of the light calibration.

8. The method of claim 7 , wherein the first laser beam forms local deformation elements to the photomask.

9. The method of claim 8 , wherein the first deformation elements reduce light transmittance of the field region.

10. The method of claim 7 , wherein the performing of the light transmittance correction includes forming second deformation elements in the calibration key pattern region.

11. The method of claim 10 , wherein the second deformation elements are formed by irradiating a second laser beam onto the calibration key pattern region to make the reduced light transmittance of the calibration key pattern region substantially equal to light transmittance of the registration corrected field region.

12. A method of defect inspection for a photomask, the method comprising:
performing light transmittance correction to reduce light transmittance of a calibration key pattern region of the photomask to a corrected light transmittance, wherein the corrected light transmittance is substantially equal to light transmittance of a field region, wherein the photomask includes the field region and the calibration key pattern region; performing light calibration using the calibration key pattern region having the corrected light transmittance to obtain a result of the light calibration; and
performing defect inspection to the field region by applying the result of the light calibration.

13. The method of claim 12 , wherein the performing of the light transmittance correction includes forming deformation elements in the calibration key pattern region.

14. The method of claim 13 , wherein the deformation elements are formed by irradiating a laser beam onto the calibration key pattern region.

Assignees

• Sk Hynix Inc

Inventors

• Jeong Goo Min
• Kim Mun Sik

Classifications

• G01N2021/95676

  Masks, reticles, shadow masks · CPC title

• G01N2021/95615

  with stored comparision signal · CPC title

• G01N21/95607 Primary

  using a comparative method · CPC title

• G01N21/93 Primary

  Detection standards; Calibrating {baseline adjustment, drift correction} · CPC title

• G01N21/956

  Inspecting patterns on the surface of objects {(contactless testing of electronic circuits G01R31/308; testing currency G07D; manufacturing processes per se of semiconductor devices implementing a measuring step H10P74/20)} · CPC title