Method for optical inspection, detection and analysis of double sided wafer macro defects

摘要

A method of automatic optical self-contained inspection for detection of macro defects of sub-pixel defect size in pattern wafers and non-pattern wafers is based on surface light scattering color-intensity computerized analysis. The method includes setting-up initial calibration and deriving correction data. A wafer image is acquired and rendered and compensated for lighting intensity and optical sensor sensitivity color spectra biases and spatial variances prior to displaying the inspection results.

主权项

1. A method of automatic optical self-contained inspection for detection of macro defects of sub-pixel defect size in pattern wafers and non-pattern wafers based on surface light scattering color-intensity computerized analysis, the method comprising:
setting-up initial calibration and correction data derivation; wafer image acquisition and rendering; compensating for lighting intensity and optical sensor sensitivity color spectra biases and spatial variances; and displaying the inspection results; wherein wafer image acquisition and rendering includes:
illuminating opposite surfaces of the wafer simultaneously with a circumferential dark field source having an optical axis that is normal to the wafer and that is disposed around a periphery of the wafer, wherein the circumferential dark field source is disposed within a circumferential ring having an internal surface coated by a light-absorbent material for absorbing light beams that are not parallel to the wafer surface;illuminating respective opposite surfaces of the wafer with a bright illumination source;disposing on opposite surfaces of the wafer a pair of optical sensors normal to both the wafer surfaces and to the bright illumination source, both of said sensors having an optical axis that is coaxial with the optical axis of the circumferential dark field source, andusing said sensors to capture light reflected from the wafer surface and to produce a sensor signal having sufficient resolution for detection of surface defects.