Method and apparatus for inspecting defects of a specimen

A defect inspection apparatus comprising:

• means for mounting a specimen;
• means for illuminating the specimen;
• an imaging optical system which forms an optical image of said illuminated specimen;
• means for detecting an optical image of said specimen formed by said imaging optical system;
• an auto-focus optical system obliquely illuminating a surface of said specimen and detecting light reflected from said specimen;
• means for measuring temperature of said imaging optical system;
• means for adjusting a focal position of said imaging optical system based on a detection signal from said auto-focus optical system and information about a temperature of said imaging optical system measured by said temperature measuring means;
• means for detecting defects on said specimen by processing output from said means detecting an optical image;
• and
• means for displaying, on a screen, information relating to defects of said specimen detected by said means for detecting defects.

A method for inspecting defects comprising the following steps:

• measuring a temperature of an imaging optical system;
• illuminating a surface of a specimen at an angle relative to said surface;
• detecting light reflected by said specimen;
• determining, based on a signal obtained by detecting light reflected from said specimen, a focal position of said imaging optical system used to form an optical image of a surface of said substrate;
• matching a height position of said specimen with said determined focal position;
• illuminating said specimen at said matched height;
• forming an optical image of said specimen using said imaging optical system equipped with an objective lens;
• capturing an optical image of said specimen;
• processing a signal obtained by capturing said optical image of said specimen and detecting defects of said specimen;
• and
• wherein said step of determining a focal position is based on said temperature of said imaging optical system.

A method for inspecting defects comprising the following steps:

• illuminating with a first light a surface of a specimen at an angle relative to said surface;
• measuring a temperature of an imaging optical system which has an objective lens;
• detecting light reflected from said surface of said specimen and determining, based on a signal obtained by said detecting and said measured temperature information, a focal position of an imaging optical system;
• adjusting a relative position between said specimen and said determined focal position;
• illuminating said specimen with a second light;
• forming an optical image of said specimen illuminated by said second light using said imaging optical system;
• capturing an optical image of said specimen;
• and
• processing a signal obtained by capturing said optical image of said specimen and detecting defects of said specimen.