Method and apparatus for detecting defects in wafers including alignment of the wafer images so as to induce the same smear in all images

• US 20060193506A1
• Filed: 02/28/2005
• Published: 08/31/2006
• Est. Priority Date: 02/28/2005
• Status: Active Grant

• Current Assignee: Applied Materials South East Asia Pte Limited (Applied Materials Incorporated)
• Original Assignee: Negevtech Limited (Negevtech)
• Inventors: Silberstein, Shai, Dorphan, Yuval, Furman, Dov, Wagner, Mark, Zaslavsky, Ran
• Granted Patent: US 7,804,993 B2
• Time in Patent Office: Days
• US Class Current: 382/145
• CPC Class Codes: G01N 21/9501 Semiconductor wafers manufacturing processes per se of semiconductor devices implementing a measuring step H01L22/10
• CPC Class Codes: G01N 21/95607 using a comparative method

Abstract

A method for inspecting a wafer including a multiplicity of dies, the method including dividing an image of at least a portion of the wafer into a plurality of sub-images each representing a sub-portion of the wafer and selecting at least one defect candidate within each sub-image by comparing each sub-image to a corresponding sub-image of a reference including a representation, which is assumed to be faultless, of the portion of the wafer.

Claims

1. A method for inspecting a wafer including a multiplicity of dies, the method comprising:

aligning at least three images of identical portions of said wafer, thereby to provide at least three mutually aligned images, including adding smear to at least one of said images so as to generate an identical amount of smear in said at least three mutually aligned images;

combining said at least three images having identical amounts of smear into a reference; and

inspecting each of a plurality of images of a corresponding plurality of portions of a wafer to be inspected, relative to said reference.

2. A method according to claim 1 wherein said aligning comprises selecting a re-sampling kernel to apply to each of said identical portions, characterized in that said identical portions, once re-sampled using said kernels, have an identical amount of smear.

3. A method according to claim 2 wherein said aligning comprises:

if a sub-portion'"'"'s misalignment (dx,dy) relative to a selected alignment marker is 0.5 pixel, using a (0.5,0.5) filter;

otherwise, using a filter of order n>

2 whose shift is (dx,dy) and whose frequency response approximates the frequency response of said (0.5,0.5) filter.

4. Apparatus for inspecting a wafer including a multiplicity of dies comprising:

an image generator, operative to align at least three images of identical portions of said wafer, thereby to provide at least three mutually aligned images, and to add smear to at least one of said images so as to generate an identical amount of smear in said at least three mutually aligned images;

a reference image generator, operative to combine said at least three images having identical amounts of smear into a reference; and

an image inspector, operative to inspect each of a plurality of images of a corresponding plurality of portions of a wafer to be inspected, relative to said reference.