# US 7,746,461 B2 · Optical defect inspection apparatus

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- Number: US 7,746,461 B2
- Document ID: US7746461B2
- Status: Granted
- Kind: B2
- Application number: 12/275,746
- Filed: 2008-11-21
- Published: 2009-06-11
- Granted: 2010-06-29
- Earliest claimed: 2006-02-24
- Assignees: Hitachi High-Technologies Corporation
- Inventors: Noriyuki Aizawa; Hiroyuki Kawakami; Kazuhiro Zama; Kazuo Takahashi; Yusuke Miyazaki; Shingo Tanaka
- Web page: https://patentgrep.com/patent/US7746461B2

## CPC

- G01N 21/9501: {Semiconductor wafers (manufacturing processes per se of semiconductor devices implementing a measuring step H10P74/20)}
- G01N 21/94: Investigating contamination, e.g. dust (G01N21/85 takes precedence)
- H10P 74/203: {Structural properties, e.g. testing or measuring thicknesses, line widths, warpage, bond strengths or physical defects}
- G01N 2021/9513: {Liquid crystal panels}
- G01N 2021/95676: {Masks, reticles, shadow masks}
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

A laser beam oscillated from a laser source is folded in its path by first and second plane mirrors and enters a beam expander. The surface of each plane mirror is deteriorated with illumination by the laser beam and the reflectance is reduced. To avoid a light quantity of the laser beam entering the beam expander from being reduced below a reference value, when the laser beam is illuminated over a certain time, a position on each of the first and second plane mirrors at which the laser beam is illuminated is changed by a structure for rotating and/or translating a reflecting surface of each plane mirror on a plane, which includes the plane mirror, while an optical axis is kept same. Thus, the useful life of each plane mirror can be prolonged without displacing the optical axis.

## Claims

### Claim 1

An optical defect inspection apparatus comprising:
a light illuminating unit for illuminating a light to an object to be inspected;
a first light detecting unit of an optical system for detecting a light scattered from the inspected object;
an inspected object moving unit for moving the inspected object such that a position on the inspected object illuminated by the light from the light illuminating unit is changed;
an inspected object holding unit for holding the inspected object; and
a focal position aligning unit for detecting the light illuminated from the light illuminating unit and reflected by the inspected object, obtaining height information of a surface of the inspected object, and aligning a focal position of the first light detecting unit of the optical system based on the obtained information,
wherein the focal position is aligned by combined control of an operation of vertically moving the inspected object holding unit and an operation of spraying the gas toward the rear surface thereof.

### Claim 2 (depends on 1)

The optical defect inspection apparatus according to claim 1, where the focal position aligning unit includes a second light detecting unit for detecting the light illuminated from the light illuminating unit and reflected by the inspected object, and a control system for executing control based on height information, which is detected by the second light detecting unit and is fed back, such that the focal position and the surface of the inspected object are held at the same height.

### Claim 3 (depends on 1)

The optical defect inspection apparatus according to claim 1, wherein said optical defect inspection apparatus further comprises a light quantity optimizing unit for optimizing a quantity of the reflected light from the inspected object by an optical element.

### Claim 4 (depends on 1)

The optical defect inspection apparatus according to claim 1, wherein the inspected object is supported at an outer peripheral edge thereof by the inspected object holding unit, thereby enabling the inspected object to be inspected while a rear surface of the inspected object is kept in a non-contact state.

### Claim 5 (depends on 1)

The optical defect inspection apparatus according to claim 1, wherein the inspected object is two-dimensionally moved by moving the inspected object in one direction while the inspected object is rotated.