Tuning substrate/resist contrast to maximize defect inspection sensitivity for ultra-thin resist in DUV lithography

• US 6,316,277 B1
• Filed: 05/30/2000
• Issued: 11/13/2001
• Est. Priority Date: 05/30/2000
• Status: Expired due to Fees

• Current Assignee: Advanced Micro Devices, Inc.
• Original Assignee: Advanced Micro Devices, Inc.
• Inventors: Schefske, Jeff, Phan, Khoi A., Lyons, Christopher F., Nguyen, Khanh B.
• Primary Examiner(s): Niebling, John F.
• Assistant Examiner(s): Luk, Olivia T
• Application Number:
  US09/580,612
• Time in Patent Office: 532 Days
• Field of Search: 438/14, 438/16, 438/636, 430/313
• US Class Current: 438/14
• CPC Class Codes: H01L 22/24 Optical enhancement of defects or not directly visible states, e.g. selective electrolytic deposition, bubbles in liquids, light emission, colour change voltage contrast G01R31/311

Abstract

There is provided a method for enhancing the contrast between oxide film and ultra-thin resists in deep-ultraviolet lithography for use with a wafer defect inspection system in order to maximize defect inspection sensitivity. This is achieved by varying the thickness of the oxide film for a given ultra-thin resist thickness so as to produce a high contrast. As a result, defect inspection of the ultra-thin resist pattern is easily obtained. In a second embodiment, the ultra-thin resist thickness is varied for a given oxide film thickness. In a third embodiment, both the oxide film and the ultra-thin resist thicknesses are varied simultaneously so as to obtain an optimum contrast.

Claims

1. A method for enhancing the contrast between oxide film and ultra-thin resists on a semiconductor wafer in DUV lithography for use with a wafer defect inspection system in order to maximize defect inspection sensitivity, said method comprising the steps of:

providing a semiconductor wafer having a standard oxide film thickness of about 1600 Å and

a standard ultra-thin resist thickness of 1000 Å

or less;

fixing said ultra-thin resist thickness; and

varying the thickness of the oxide film in order to obtain a reflectivity of the ultra-thin resist which is different from the reflectivity of the oxide film so as to produce a high contrast therebetween.

2. A method for enhancing as claimed in claim 1, wherein said ultra-thin resist has a fixed thickness of 975 Å

and said oxide film thickness is varied to a thickness of 1200 Å

to produce an optimal contrast.

3. A method for enhancing as claimed in claim 1, wherein said ultra-thin resist has a fixed thickness of 975 Å

and said oxide film thickness is varied to a thickness of 860 Å

to produce an optimal contrast.

4. A method for enhancing as claimed in claim 1, wherein said ultra-thin resist has a fixed thickness of 975 Å

and said oxide film thickness is varied to a thickness of 2,750 Å

to produce an optimal contrast.

5. A method for enhancing the contrast between oxide film and ultra-thin resists on a semiconductor wafer in DUV lithography for use with a wafer defect inspection system in order to maximize defect inspection sensitivity, said method comprising the steps of:

providing a semiconductor wafer having a standard oxide film thickness of about 1600 Å and

a standard ultra-thin resist thickness of 1000 Å

or less;

fixing said oxide film thickness; and

varying the thickness of the ultra-thin resist in order to obtain a reflectivity of the ultra-thin resist which is different from the reflectivity of the oxide film so as to produce a high contrast therebetween.

6. A method for enhancing the contrast between oxide film and ultra-thin resists on a semiconductor wafer in DUV lithography for use with a wafer defect inspection system in order to maximize defect inspection sensitivity, said method comprising the steps of:

providing a semiconductor wafer having a standard oxide film thickness of about 1600 Å and

a standard ultra-thin resist thickness of 1000 Å

or less;

varying said ultra-thin resist thickness; and

varying simultaneously the thickness of the oxide film in order to obtain a reflectivity of the ultra-thin resist which is different from the reflectivity of the oxide film so as to produce a high contrast therebetween.