Optical measurement system using polarized light

A method of evaluating a substrate comprising the steps of generating an initial map of at least a portion of the substrate by:

• generating an intensity-stabilized laser light beam by using a laser source and feedback,
• polarizing the light beam to form a stabilized polarized light beam,
• directing the polarized laser light beam to a measurement point on the substrate,
• relatively transporting the polarized light beam to at least one new measurement point on the substrate in a two dimensional field,
• separating the polarized light beam after interaction with a particular location on the substrate into a set of two orthogonally polarized light beams,
• measuring the amplitude of each of the orthogonally polarized light beams,
• compiling a data set by synchronizing the measured amplitude of each set of orthogonally polarized light beams with the location of each corresponding measurement point on the substrate;
• thereafter following the aforesaid steps and generating a second map of said portion of the substrate;
• and
• determining changes in the substrate by comparing the initial map with the second map.

An optical measurement system for evaluating a substrate, the system comprising:

• an intensity stabilized light source including a feedback system configured to generate an intensity stabilized light beam
• a polarizing element for polarizing the light beam emanating from the light generating source to provide stabilized polarized light,
• an optical element for focusing the stabilized polarized light at a particular location on the substrate,
• a controllable translatable assembly to create relative movement between the focused stabilized polarized light and the substrate to move the location of the focused stabilized light over a two dimensional field on the substrate,
• a detection system for measuring the light beam reflected from the particular location on the substrate, the detection system including
• a beam splitting element to split the light beam reflected from the particular location on the substrate into s-polarized light and p-polarized light,
• a first sensor for measuring amplitude of the s-polarized light,
• a second sensor for measuring amplitude of the p-polarized light, and
• a CPU for controlling said translatable assembly and for determining the location of the light beam and for analyzing the measured amplitude of the s-polarized light and the p-polarized light to determine characteristics of the substrate.

An optical measurement system for evaluating a substrate, the system comprising:

• an intensity stabilized light source employing a feedback mechanism configured to generate an intensity stabilized light beam,
• a polarizing element for polarizing the light beam emanating from the light source to provide a polarized light beam,
• an optical system for directing the polarized light beam to a particular location on the substrate,
• a controllable translatable assembly for moving the polarized light beam across at least a portion of the substrate in a two dimensional field such that the polarized light beam impinges upon multiple locations on the substrate,
• a position indicator for determining the particular location on the substrate upon which the polarized light beam impinges,
• a detection system configured to evaluate the light beam after interaction with the particular locations on the substrate upon which the polarized light beam impinges, the detection system including
• a polarization analyzing element for separating the light from the particular locations on the substrate into s-polarized light and p-polarized light,
• a first optical sensor measuring amplitude of the s-polarized light,
• a second optical sensor measuring amplitude of the p-polarized light, and
• a control system for controlling said translatable assembly and said position indicator for determining the particular location of the light beam, configured to compile a data set correlating the measured amplitude of the s-polarized light and the p-polarized light with the particular location on the substrate upon which the polarized light beam impinges.

A method of evaluating a substrate comprising the steps of

• generating an intensity stabilized light beam;
• polarizing the light beam to form a polarized light beam;
• directing the polarized light beam to a particular location in a two dimensional field on the substrate;
• separating the polarized light beam after interaction with the particular location on the substrate into two orthogonally polarized light beams;
• controlling the directed light beam onto locations in said two dimensional field and determining the locations of the directed light beam;
• and
• analyzing the measured amplitude of each of the two orthogonally polarized light beams and the measured phase difference between the two orthogonally polarized light beams for various locations in said two dimensional field to determine changes in the substrate.

A method of evaluating a substrate area comprising the steps of:

• generating an intensity-stabilized light beam using a laser source with a feedback system;
• polarizing the light beam from said laser source to form a stabilized polarized light beam;
• directing the stabilized polarized light beam to a point for measurement on the substrate;
• relatively transporting the polarized light beam to a plurality of additional measurement points on the substrate within a two dimensional field so that the polarized light beam impinges on multiple locations on said substrate within said field
• detecting the light beam after interaction with the substrate in said field including:
• splitting the light beam after interaction with a location on said substrate into s-polarized light and p-polarized light and
• measuring the amplitude of the s-polarized light with a first sensor, and
• measuring the amplitude of the p-polarized light with a second sensor, and
• controlling the transport of said polarized light beam while determining the location of the light beam on the substrate for compiling a data set for each measurement of said first and second sensors to determine characteristics of the substrate.

A method of evaluating a substrate comprising the steps of

• generating an intensity stabilized light beam;
• polarizing the light beam to form a polarized light beam;
• directing the polarized light beam to particular locations in a two dimensional field on the substrate;
• controlling the directed light beam onto locations in said two dimensional field and determining the impinging locations of the directed light beam;
• and
• analyzing the measured phase difference between the two orthogonally polarized light beams for various locations in said two dimensional field to determine surface characteristics of the substrate.