Patent ID: 7062013
Filing Date: 2006-06-13
Classification: G01B,G01N

Abstract:
1. A method for inspection of a sample, comprising: directing radiation from a radiation source in a first predetermined position toward a radiation sensor in a second predetermined position; sensing the radiation that is directly incident on the radiation sensor from the radiation source so as to generate a first direct signal as a function of elevation angle, while a shutter is positioned so as to cut off the radiation at a predetermined cutoff angle; sensing the radiation that is directly incident on the radiation sensor from the radiation source so as to generate a second direct signal as a function of the elevation angle, while the shutter is positioned so as not to cut off the radiation at the predetermined cutoff angle; introducing a sample between the radiation source in the first predetermined position and the radiation sensor in the second predetermined position, so that the radiation is incident on a surface of the sample; sensing the radiation reflected from the surface of the sample onto the radiation sensor so as to generate a first reflectance signal as a function of the elevation angle, while the shutter is positioned so as to cut off the radiation at the predetermined cutoff angle; sensing the radiation reflected from the surface of the sample onto the radiation sensor so as to generate a second reflectance signal as a function of the elevation angle, while the shutter is positioned so as not to cut off the radiation at the predetermined cutoff angle; and comparing a first ratio between the first direct signal and the second direct signal with a second ratio between the first reflectance signal and the second reflectance signal in order to find the elevation angle of a tangent to the surface.