Method of detecting mask defects, a computer program and reference substrate

• US 7,307,712 B2
• Filed: 10/27/2003
• Issued: 12/11/2007
• Est. Priority Date: 10/28/2002
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: Van Der Werf, Jan Evert, Mud, Auke Jan
• Primary Examiner(s): STAFIRA, MICHAEL PATRICK
• Application Number:
  US10/693,603
• Publication Number:
  US 20040130711A1
• Time in Patent Office: 1,506 Days
• Field of Search: None
• US Class Current: 356/237.2
• CPC Class Codes: G03F 7/7065 Defects, e.g. optical inspection of patterned layer for defects

Abstract

A method of detecting mask defects in which a reference substrate is patterned by the mask immediately after manufacture of the mask is disclosed. The reference substrate is stored in clean conditions while IC manufacture takes place. When a mask defect is suspected, a resist coated substrate, the test substrate, is patterned by exposure of the mask. The patterns on the reference substrate and the test substrate are compared to determine if there is a mask defect. The location of the mask defect can be found by scanning smaller areas of the patterns.

Claims

1. A method of detecting defects in a patterning device in a photolithographic process comprising:

printing a reference pattern on a reference substrate using the patterning device and a beam of radiation;

printing a pattern for manufacture of a device on a production substrate different from said reference substrate using the patterning device and beam of radiation;

printing a test pattern on a test substrate using the patterning device and beam of radiation; and

comparing the printed test pattern to the printed reference pattern to detect a defect in the patterning device.

2. A method of detecting defects in a patterning device according to claim 1, wherein the reference substrate is a silicon wafer.

3. A method of detecting defects in a patterning device according to claim 1, wherein the reference substrate is a silicon wafer having an SiO2 layer and the printed reference pattern is etched into the SiO2 layer.

4. A method of detecting defects in a patterning device according to claim 1, wherein the test substrate is the reference substrate.

5. A method of detecting defects in a patterning device according to claim 1, wherein the printed test pattern is a pattern in developed resist.

6. A method of detecting defects in a patterning device according to claim 1, wherein the reference pattern is printed at a plurality of different locations on the reference substrate.

7. A method of detecting defects in a patterning device according to claim 6, wherein individual printed reference patterns are spaced such that an individual test pattern can be printed beside each individual printed reference pattern.

8. A method of detecting defects in a patterning device according to claim 1, wherein in comparing the printed test pattern to the printed reference pattern the patterned test substrate and reference substrate are scanned by at least one optical defect inspection tool.

9. A method of detecting defects in a patterning device according to claim 8, wherein in comparing the printed test pattern to the printed reference pattern the patterned test substrate and reference substrate are scanned simultaneously by respective optical defect inspection tools.

10. A method of detecting defects in a patterning device according to claim 8, wherein multiple comparisons take place between multiple printed reference patterns and multiple printed test patterns.

11. A method of detecting defects in a patterning device according to claim 10, wherein majority voting determines location of the defect in the patterning device.

12. A method of detecting defects in a patterning device according to claim 1, wherein said patterning device is a photolithography mask.

13. A method of detecting defects in a patterning device of a photolithographic apparatus, the method comprising:

generating a reference pattern on a first substrate using a beam of radiation and the patterning device;

generating a pattern on a second substrate using the beam of radiation and the patterning device; and

comparing the reference pattern on the first substrate to the pattern on the second substrate to detect a defect in the patterning device.

14. A method of detecting defects in a patterning device according to claim 13, wherein the pattern is a test pattern and the second substrate is a test substrate.

15. A method of detecting defects in a patterning device according to claim 13, wherein the pattern is a test pattern and the second substrate is the first substrate.

16. A method of detecting defects in a patterning device according to claim 13, wherein the pattern comprises features of a manufactured device and the second substrate comprises the manufactured device.