Method of inspecting mask using aerial image inspection apparatus

• US 7,865,866 B2
• Filed: 05/16/2008
• Issued: 01/04/2011
• Est. Priority Date: 05/16/2007
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Choi, Sun-Young, Kim, Hee-Bom, Ji, Min-Kyu, Baik, Hyun-Joo
• Primary Examiner(s): Lin; Sun J
• Application Number:
  US12/122,399
• Publication Number:
  US 20080288912A1
• Time in Patent Office: 963 Days
• Field of Search: 716/19, 716/21, 716/50, 716/51, 716/53, 716/54, 716/55
• US Class Current: 716/50
• CPC Class Codes: G03F 1/84 Inspecting

Abstract

A method of precisely inspecting the entire surface of a mask at a high speed in consideration of optical effects of the mask. The method includes designing a target mask layout for a pattern to be formed on a wafer, and extracting an effective mask layout using an inspection image measured from the target mask layout using an aerial image inspection apparatus as a mask inspection apparatus. The effective mask layout is input to a wafer simulation tool for calculating a wafer image to be formed on the wafer. Optical effects of the mask are detected by comparing the target mask layout with the effective mask layout.

Claims

1. A method of inspecting a mask using an aerial image inspection apparatus, the method comprising:

designing a target mask layout for a pattern to be formed on a wafer;

extracting an effective mask layout by comparing an inspection image measured from the target mask layout using the aerial image inspection apparatus with a simulation image; and

inputting the effective mask layout to a wafer simulation tool for calculating a wafer image to be formed on the wafer,

wherein optical effects of the mask are detected by comparing the target mask layout with the effective mask layout.

2. The method of claim 1, wherein the extracting an effective mask layout comprises:

fabricating the mask according to the target mask layout for measuring the inspection image of the target mask layout;

calculating the simulation image of the target mask layout;

comparing the simulation image with the inspection image; and

when the simulation image is substantially the same as the inspection image, selecting the target mask layout as the effective mask layout.

3. The method of claim 2,

wherein when the simulation image is not substantially the same as the inspection image, extracting of the effective mask layout comprises:

(a) modifying the target mask layout;

(b) calculating a simulation image of the modified target mask layout;

(c) comparing the simulation image of the modified target mask layout with the inspection image; and

repeating (a) through (c) until the simulation image is substantially the same as the inspection image, and selecting the modified target mask layout as the effective mask layout.

4. The method of claim 1, wherein the designing a target mask layout comprises:

designing the pattern;

adjusting variables of an optical proximity correction (OPC) algorithm using optical characteristics of the aerial image inspection apparatus; and

designing the target mask layout for the pattern using the OPC algorithm.

5. The method of claim 1, wherein the extracting an effective mask layout is performed using a modified optical proximity correction (OPC) algorithm.

6. The method of claim 5, wherein the modified OPC algorithm comprises a biasing operation for a scattering bar of the effective mask layout.

7. The method of claim 6, wherein the biasing operation for the scattering bar is performed by compensating for an edge threshold intensity difference (ETD) between the inspection image and the simulation image at an edge portion of the scattering bar.

8. The method of claim 1, wherein the wafer simulation tool is an optical proximity correction (OPC) algorithm for calculating the wafer image in consideration of wafer conditions, the wafer conditions including a photoresist (PR) layer formed on the wafer and vector effects of light.

9. The method of claim 1, wherein a mask error caused by the mask is detected by comparing the target mask layout with the effective mask layout.

10. The method of claim 9, wherein information about critical dimension (CD) variations and a weak pattern of the wafer caused by the mask error is obtained by comparing the pattern with the wafer image.

11. The method of claim 9, wherein the mask error is at least one of a defect of the 30 mask, a critical dimension (CD) uniformity error of the mask, and a CD error of a pattern of the mask.

12. A method of inspecting a mask using an aerial image inspection apparatus, the method comprising:

designing a pattern to be formed on a wafer;

adjusting variables of an optical proximity correction (OPC) algorithm using optical characteristics of the aerial image inspection apparatus, the aerial image inspection apparatus being used as a mask inspection apparatus;

designing a target mask layout for the pattern using the OPC algorithm;

extracting an effective mask layout by comparing an inspection image measured from the target mask layout using the aerial image inspection apparatus with a simulation image; and

inputting the effective mask layout to a wafer simulation tool for calculating a wafer image to be formed on the wafer,

wherein optical effects of the mask are detected by comparing the target mask layout with the effective mask layout.

13. The method of claim 12, wherein the extracting an effective mask layout comprises:

fabricating the mask according to the target mask layout for measuring the inspection image of the target mask layout;

calculating the simulation image of the target mask layout;

comparing the simulation image with the inspection image; and

when the simulation image is substantially the same as the inspection image, selecting the target mask layout as the effective mask layout.

14. The method of claim 13,

wherein when the simulation image is not substantially the same as the inspection image, extracting of the effective mask layout comprises:

(a) modifying the target mask layout;

(b) calculating a simulation image of the modified target mask layout;

(c) comparing the simulation image of the modified target mask layout with the inspection image;

repeating (a) through (c) until the simulation image is substantially the same as the inspection image, and selecting the modified target mask layout as the effective mask layout.

15. The method of claim 12, wherein the extracting an effective mask layout is performed using a modified OPC algorithm.

16. The method of claim 15, wherein the modified OPC algorithm comprises a biasing operation for a scattering bar of the effective mask layout.

17. The method of claim 16, wherein the biasing operation for the scattering bar is performed by compensating for an edge threshold intensity difference (ETD) between the inspection image and the simulation image at an edge portion of the scattering bar.

18. The method of claim 12, wherein:

the wafer simulation tool is an OPC algorithm for calculating the wafer image in consideration of wafer conditions, the wafer conditions including a photoresist (PR) layer formed on the wafer and vector effects of light;

a mask error caused by the mask is detected by comparing the target mask layout with the effective mask layout; and

information about critical dimension (CD) variations and a weak pattern of the wafer caused by the mask error is obtained by comparing the pattern with the wafer image.

19. The method of claim 18, wherein the mask error is at least one of a defect of the mask, a CD uniformity error of the mask, and a CD error of a pattern of the mask.

20. A method of inspecting a mask using an aerial image inspection apparatus, the method comprising:

designing a pattern to be formed on a wafer;

adjusting variables of an optical proximity correction (OPC) algorithm using optical characteristics of the aerial image inspection apparatus, the aerial image inspection apparatus being used as a mask inspection apparatus;

designing a target mask layout for the pattern using the OPC algorithm;

extracting an effective mask layout by comparing an inspection image measured from the target mask layout using the aerial image inspection apparatus with a simulation image;

inputting the effective mask layout to a wafer simulation tool for calculating a wafer image to be formed on the wafer; and

detecting optical effects of the mask by comparing the target mask layout with the effective mask layout,

wherein the extracting an effective mask layout is performed using a modified OPC algorithm comprising a biasing operation for a scattering bar of the effective mask layout, the biasing operation for the scattering bar being performed by compensating for an edge threshold intensity difference (ETD) between the inspection image and the simulation image at an edge portion of the scattering bar, wherein when an inspection image intensity is greater than a simulation image intensity, a width of the scattering bar is decreased in the effective mask layout, and wherein when the inspection image intensity is less than the simulation image intensity, the width of the scattering bar is increased in the effective mask layout.