US 8,101,935 B2 · Inspection apparatus and inspection method

Abstract

Reflected light caused by the state of the surface of a wafer, a foreign material or a defect is superimposed on a haze frequency component caused by the type and thickness of a film or a surface irregularity. It has therefore been difficult to accurately measure the haze frequency component by use of a fixed threshold value. In order to detect a haze frequency component caused by a haze present on the surface of an object to be inspected, light propagating from the object to be inspected is detected and converted into an electric signal. The electric signal is sampled at a predetermined sampling time interval and converted into digital data. A frequency component caused by a foreign material, a defect or the like is separated from the digital data to ensure that a haze frequency component is selected. The haze frequency component is caused by a stain attached to the surface of the wafer, hazy tarnish, a surface irregularity or the like.

Claims11

Dependent claims

An inspection apparatus comprising:

an illumination unit which illuminates the surface of an object that is to be inspected and placed on a movable stage;
an optical detection unit which detects light propagating from the surface of the object and converts the detected light into an electric signal;
an A/D converter which converts the electric signal to digital data;
and
a processing unit which separates and removes a first frequency component from the digital data and selects a haze frequency component caused by a haze,
wherein, in order to determine normality of the haze frequency component, data on the haze frequency component caused by the haze located at a coordinate position is compared with data on a frequency component caused by a normal object located at the same coordinate position.

3 more elements

An inspection method which illuminates with light an object that is to be inspected and placed on a movable stage to inspect a region present on the surface of the object or inspect the inside of the object that is located near the surface of the object, comprising the steps of:

detecting light propagating from the object to be inspected and converting the detected light into an electric signal;
sampling the electric signal at a predetermined sampling time interval and converting the sampled electric signal into digital data;
and
separating from the digital data a frequency component caused by a foreign material or a defect and selecting a haze frequency component caused by a haze in the form of a stain attached to the surface of the object, hazy tarnish or a surface irregularity,
wherein, in order to determine normality of the haze frequency component, data on the haze frequency component caused by the haze located at a coordinate position is compared with data on a frequency component caused by a normal object located at the same coordinate position.

2 more elements

Dependencies are inferred from the claim text.

Inspection apparatus and inspection method

Life of this patent

Inspection apparatus and inspection method

Life of this patent

Abstract

Claims11