Method of detecting and classifying scratches, particles and pits on thin film disks or wafers

Abstract

Scratches, pits and particles which are smaller or larger than the beam size may be measured and identified by a dual beam technique. This invention uses a pair of orthogonally oriented laser beams, one in the radial and one in the circumferential direction. The scattered light from radial and circumferential beams allows the detection and classification of particles, pits and scratches.

Description

RELATED APPLICATIONS [0001] This application is a continuation of U.S. patent application Ser. No. 10 / 219,632, filed on Aug. 14, 2002 (applicants reference number 20830-07089), which is a continuation-in-part of U.S. patent application Ser. No. 10 / 126,154, filed on Apr. 19, 2002 (applicants reference number 6820), which is a continuation-in-part of U.S. patent application Ser. No. 10 / 029,957, filed on Dec. 21, 2001 (applicants reference number 6581), which is a continuation-in-part of U.S. patent application Ser. No. 09 / 861,280, filed on May 18, 2001 (applicants reference number 6056), which is a continuation of U.S. patent application Ser. No. 09 / 818,199, filed on Mar. 26, 2001 (applicants reference number 5727), which are all incorporated by reference herein in their entirety. [0002] This application is also related to U.S. patent application Ser. No. 09 / 718,054 filed on 20 Nov. 2000 (applicants reference number 5534), which is a continuation-in-part of U.S. patent application Ser...

AI Technical Summary

Benefits of technology

[0011] A method is provided for categorizing defects, such as scratches, particles, and pits, on the surface of an object. Two or more light beams with different planes of incidence, such as orthogonally oriented beams, are directed at the surface of the object. The scattered light...

Problems solved by technology

One problem that the manufacturers of hard disks experience is how to maximize the operating life of a hard disk.

When a hard disk fails the data stored therein may be difficult, expensive, or impossible to retrieve.

Failure of a hard disk may be caused by defects on the surface of the thin film disk.

As a result even very small defects can cause a hard drive to fail.

The problem is that the CMP process can leave residual copper, nitride, or CMP slurry on the surface of the wafer.

In addition, stains, particles, scratches, and micro-waviness may be present on the polished wafer.

Fewer defects will also mean greater wafer yields at the end of the process.

The problem in the hard disk, semiconductor and photonics industries is to inspect these magnetic disks and wafers for defects such as particles, scratches, pits, mounds, stains, topographic irregularities and inclusions.

None of these systems enables the simultaneous measurement of topographic and non-topographic defects.

When a defect is smaller in size than the dimension of a measurement beam, it is difficult to determine the nature of the defect.

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