Method and apparatus for measuring thickness of thin films

An apparatus for measuring the thickness of a thin film layer on the surface of a substrate comprising:

• means for generating a probe beam of radiation;
• means for focusing said probe beam onto the surface of the substrate such that various rays within the focused probe beam create a spread of angles of incidence with respect to said surface and wherein said focused incident probe beam includes at least one ray substantially normal to the surface of the substrate;
• detector means for receiving the probe beam after it has been reflected from the surface of the substrate, said detector means for measuring the intensity of various rays as a function of position within the reflected probe beam, with the position of the rays within said reflected probe beam corresponding to specific angles of incidence with respect to said surface;
• and
• processor means for determining the thickness of the thin film layer based upon the angular dependent intensity measurements made by the detector means.

An apparatus for measuring the thickness of a thin film layer on the surface of a substrate comprising:

• means for generating a probe beam of radiation;
• means for focusing said probe beam onto the surface of the substrate such that various rays within the focused probe beam create a spread of angles of incidence with respect to said surface, wherein said focusing means is defined by a lens having a numerical aperture of at least 0.5;
• detector means for receiving the probe beam after it has been reflected from the surface of the substrate, said detector means for measuring the intensity of various rays as a function of position within the reflected probe beam, with the position of the rays within said reflected probe beam corresponding to specific angles of incidence with respect to said surface;
• and
• a processor means for determining the thickness of the thin film layer based upon the angular dependent intensity measurements made by the detector means.

An apparatus for measuring the thickness of a thin film layer on the surface of a substrate comprising:

• means for generating a probe beam of radiation;
• means for focusing said probe beam onto the surface of the substrate such that various rays within the focused probe beam create a spread of angles of incidence with respect to said surface, wherein the variation in the angle of incidence of the rays of the focused incident probe beam, from the center to the outer edge, is at least 30 degrees;
• detector means for receiving the probe beam after it has been reflected from the surface of the substrate, said detector means for measuring the intensity of various rays as a function of position within the reflected probe beam, with the position of the rays within said reflected probe beam corresponding to specific angles of incidence with respect to said surface;
• and
• processor means for determining the thickness of the thin film layer based upon the angular dependent intensity measurements made by the detector means.

An apparatus for measuring the thickness of a thin film layer on the surface of a substrate comprising:

• means for generating a probe beam of radiation;
• means for focusing said probe beam to a diameter of about one micron or less onto the surface of the substrate such that various rays within the focused probe beam create a spread of angles of incidence with respect to said surface;
• detector means for receiving the probe beam after it has been reflected from the surface of the substrate, said detector means for measuring the intensity of various rays as a function of position within the reflected probe beam, with the position of the rays within said reflected probe beam corresponding to specific angles of incidence with respect to said surface;
• and
• processor means for determining the thickness of the thin film layer based upon the angular dependent intensity measurements made by the detector means.

An apparatus for measuring the thickness of a thin film layer on the surface of a substrate comprising:

• means for generating a probe beam of radiation;
• means for focusing said probe beam onto the surface of the substrate such that various rays within the focused probe beam create a spread of angles of incidence with respect to said surface and wherein the light in said probe beam is linearly polarized prior to being focused by said focusing means and wherein said probe beam is focused substantially normal to the surface of the substrate such that light rays incident on the sample surface have substantial components of S and P polarized light with respect to the plane of incidence at the sample surface;
• detector means for receiving the probe beam after it has been reflected from the surface of the substrate, said detector means for measuring the intensity of various rays as a function of position within the reflected probe beam, with the position of the rays within said reflected probe beam corresponding to specific angles of incidence with respect to said surface;
• and
• processor means for determining the thickness of the thin film layer based upon the angular dependent intensity measurements made by the detector means.

An apparatus for measuring the thickness of a thin film layer on the surface of a substrate comprising:

• means for generating a probe beam of radiation;
• means for focusing said probe beam onto the surface of the substrate such that various rays within the focused probe beam create a spread of angles of incidence with respect to said surface;
• detector means for receiving the probe beam after it has been reflected from the surface of the substrate, said detector means for measuring the intensity of various rays as a function of position within the reflected probe beam, with the position of the rays within said reflected probe beam corresponding to specific angles of incidence with respect to said surface;
• and
• processor means for determining the thickness of the thin film layer based upon the angular dependent intensity measurements made by the detector means and wherein said processor means determines the thickness of the thin film layer using a mathematical model which relates the angular dependent intensity measurements made by the detector means, angle of incidence, polarization of the rays of the focused incident probe beam and layer thickness.

An apparatus for measuring the thickness of a thin film layer on the surface of a substrate comprising:

• means for generating a probe beam of radiation;
• means for focusing said probe beam onto the surface of the substrate such that various rays within the focused probe beam create a spread of angles of incidence with respect to said surface;
• detector means for receiving the probe beam after it has been reflected from the surface of the substrate, said detector means for measuring the intensity of various rays as a function of position within the reflected probe beam, with the position of the rays within said reflected probe beam corresponding to specific angles of incidence with respect to said surface;
• and
• processor means for determining the thickness of the thin film layer based upon the angular dependent intensity measurements made by the detector means and wherein said detector means further functions to measure the total power of the reflected probe beam and wherein said processor means determines the thickness of the thin film layer based upon both the angular dependent intensity measurements and the total reflected power measurements made by the detector means.

An apparatus for measuring the thickness of a thin film layer on the surface of a substrate comprising:

• means for generating a probe beam of linearly polarized radiation;
• lens means for focusing said probe beam substantially normal to the surface of the substrate such that various rays within the focused probe beam create a spread of angles of incidence with respect to said surface and such that light rays incident on the sample surface have substantial components of S and P polarized light with respect to the plane of incidence at the sample surface;
• detector means for receiving the probe beam after it has been reflected from the surface of the substrate, said detector means for measuring the intensity of various rays as a function of position within the reflected probe beam in a manner to isolate the S and P polarization components, with the position of the rays within said reflected probe beam corresponding to specific angles of incidence with respect to said surface;
• and
• processor means for determining the thickness of the thin film layer based upon the angular dependent intensity measurements of the S and P polarized light made by the detector means.

An apparatus for measuring the thickness of a thin film layer on the surface of a substrate comprising:

• means for generating a probe beam of radiation;
• lens means for focusing said probe beam onto the surface of the substrate, such that various rays within the focused probe beam create a spread of angles of incidence with respect to said surface;
• detector means for receiving the probe beam after it has been reflected from the surface of the substrate, said detector means for measuring the intensity of various rays as a function of position within the reflected probe beam, with the position of the rays within said reflected probe beam corresponding to specific angles of incidence with respect to said surface;
• and
• processor means for determining the thickness of the thin film layer using a mathematical model which relates the angular dependent intensity measurements made by the detector means, angle of incidence, polarization of the rays of the focused incident probe beam and layer thickness.

An apparatus for measuring the thickness of a thin film layer on the surface of a substrate comprising:

• means for generating a probe beam of radiation;
• lens means for focusing said probe beam onto the surface of the substrate such that various rays within the focused probe beam create a spread of angles of incidence with respect to said surface;
• first detector means for receiving the probe beam after it has been reflected from the surface of the substrate, said first detector means for measuring the intensity of various rays as a function of position within the reflected probe beam, with the position of the rays within said reflected probe beam corresponding to specific angles of incidence with respect to said surface;
• second detector means for receiving the probe beam after it has been reflected from the surface of the substrate, said second detector means for measuring the total power of the reflected probe beam;
• and
• processor means for determining the thickness of the thin film layer based upon both the angular dependent intensity measurements made by the first detector means and the total reflected power measured by the second detector means.

An apparatus for evaluating parameters of a sample which includes a thin film layer on the surface of a substrate comprising:

• means for generating a probe beam of radiation;
• lens means for focusing said probe beam onto the surface of the sample such that various rays within the focused probe beam create a spread of angles of incidence with respect to said surface;
• detector means for receiving the probe beam after it has been reflected from the surface of the substrate, said detector means for measuring the intensity of various rays as a function of position within the reflected probe beam, with the position of the rays within said reflected probe beam corresponding to specific angles of incidence with respect to said surface;
• and
• processor means for determining parameters of the sample including the thickness of the thin film layer and the index of refraction of the thin film layer or the substrate based upon the angular dependent intensity measurements made by the detector means and wherein the light in said probe beam is linearly polarized prior to being focused by said lens means and wherein sad probe beam is focused substantially normal to the surface of the substrate such that light rays incident on the sample surface have substantial components of S and P polarized light with respect to the plane of incidence at the sample surface.

An apparatus for evaluating parameters of a sample which includes a thin film layer on the surface of a substrate comprising:

• means for generating a probe beam of radiation;
• lens means for focusing said probe beam to a diameter of about one micron or less onto the surface of the sample such that various rays within the focused probe beam create a spread of angles of incidence with respect to said surface;
• detector means for receiving the probe beam after it has been reflected from the surface of the substrate, said detector means for measuring the intensity of various rays as a function of position within the reflected probe beam, with the position of the rays within said reflected probe beam corresponding to specific angles of incidence with respect to said surface;
• and
• processor means for determining parameters of the sample including the thickness of the thin film layer and the index of refraction of the thin film layer or the substrate based upon the angular dependent intensity measurements made by the detector means.

An apparatus for measuring the thickness of a thin film layer on the surface of a substrate comprising:

• means for generating a probe beam of radiation;
• lens means for focusing said probe beam onto the surface of the substrate such that various rays within the focused probe beam create a spread of angles of incidence with respect to said surface and wherein said lens means has a numerical aperture of at least 0.5 and said probe beam is focused substantially normal to the surface of the substrate;
• detector means for receiving the reflected probe beam, said detector means for measuring the interference effected created by the interaction between the rays of the probe beam reflecting off the thin film layer and the upper surface of the underlying substrate as a function of position within the reflected probe beam, with the position of the interference effects within said reflected probe beam corresponding to specific angles of incidence with respect to said surface;
• and
• processor means for determining the thickness of the thin film layer based upon the angular dependent interference effects measured made by the detector means.

An apparatus for measuring the thickness of a thin film layer on the surface of a substrate comprising;

• means for generating a probe beam of radiation;
• lens means for focusing said probe beam to a diameter of about one micron or less onto the surface of the substrate such that various rays within the focused probe beam create a spread of angles of incidence with respect to said surface;
• detector means for receiving the reflected probe beam, said detector means for measuring the interference effects created by the interaction between the rays of the probe beam reflecting off the thin film layer and the upper surface of the underlying substrate as a function of position within the reflected probe beam, with the position of the interference effects within said reflected probe beam corresponding to specific angles of incidence with respect to said surface;
• and
• processor means for determining the thickness of the thin film layer based upon the angular dependent interference effects measured made by the detector means.

A method of measuring the thickness of a thin film layer on the surface of a substrate comprising the steps of:

• generating a probe beam of radiation;
• focusing the probe beam substantially normal onto the surface of the substrate such that various rays within the focused probe beam create a spread of angles of incidence with respect to said surface;
• measuring the intensity of various rays as a function of position within the reflected beam with the position of the rays within said reflected probe beam corresponding to specific angles of incidence with respect to said surface;
• and
• determining the thickness of the thin film layer based upon the angularly dependent intensity measurements.

A method of measuring the thickness of a thin film layer on the surface of a substrate comprising the steps of:

• generating a probe beam of radiation;
• focusing the probe beam on the surface of the substrate such that various rays within the focused probe beam create a spread of angles of incidence with respect to said surface wherein said incident probe beam is focused in a manner such that it includes at least one ray that is substantially normal to the surface of the substrate;
• measuring the intensity of various rays as a function of position within the reflected beam with the position of the rays within said reflected probe beam corresponding to specific angles of incidence with respect to said surface;
• and
• determining the thickness of the thin film layer based upon the angularly dependent intensity measurements.

A method of measuring the thickness of a thin film layer on the surface of a substrate comprising the steps of:

• generating a probe beam of radiation;
• focusing the probe beam on the surface of the substrate such that various rays within the focused probe beam create a spread of angles of incidence with respect to said surface wherein said incident probe beam is focused in a manner to include at least one ray that is inclined near Brewster's angle with respect to either the thin film layer or the substrate;
• measuring the intensity of various rays as a function of position within the reflected beam with the position of the rays within said reflected probe beam corresponding to specific angles of incidence with respect to said surface;
• and
• determining the thickness of the thin film layer based upon the angularly dependent intensity measurements.

A method of measuring the thickness of a thin film layer on the surface of a substrate comprising the steps of:

• generating a probe beam of radiation;
• focusing the probe beam on the surface of the substrate such that various rays within the focused probe beam create a spread of angles of incident with respect to said surface wherein the incident probe beam is focused in a manner such that the variation in the angle of incidence of the rays with respect to the substrate is at least 30 degrees;
• measuring the intensity of various rays as a function of position within the reflected beam with the position of the rays within said reflected probe beam corresponding to specific angles of incidence with respect to said surface;
• and
• determining the thickness of the thin film layer based upon the angularly dependent intensity measurements.

A method of measuring the thickness of a thin film layer on the surface of a substrate comprising the steps of:

• generating a probe beam of radiation;
• focusing the probe beam to a diameter of about one micron or less on the surface of the substrate such that various rays within the focused probe beam create a spread of angles of incidence with respect to said surface;
• measuring the intensity of various rays as a function of position within the reflected beam with the position of the rays within said reflected probe beam corresponding to specific angles of incidence with respect to said surface;
• and
• determining the thickness of the thin film layer based upon the angularly dependent intensity measurements.

A method of measuring the thickness of a thin film layer on the surface of a substrate comprising the steps of:

• generating a probe beam of radiation;
• focusing the probe beam on the surface of the substrate such that various rays within the focused probe beam create a spread of angles of incidence with respect to said surface and wherein the light in said probe beam is linearly polarized prior to being focused and wherein said probe beam is directed substantially normal to the surface of the substrate such that the light incident on said substrate includes substantial components of S and P polarized light with respect to the plane of incidence at the sample surface;
• measuring the intensity of various rays as a function of position within the reflected beam with the position of the rays within said reflected probe beam corresponding to specific angles of incidence with respect to said surface;
• and
• determining the thickness of the thin film layer based upon the angularly dependent intensity measurements.

A method of measuring the thickness of a thin film layer on the surface of a substrate comprising the steps of:

• generating a probe beam of radiation;
• focusing the probe beam on the surface of the substrate such that various rays within the focused probe beam create a spread of angles of incidence with respect to said surface;
• measuring the intensity of various rays as a function of position within the reflected beam with the position of the rays within said reflected probe beam corresponding to specific angles of incidence with respect to said surface;
• and
• determining the thickness of the thin film layer based upon the angularly dependent intensity measurements and wherein the thickness of the thin film is calculated using a mathematical model which relates the angular dependent intensity measurements, angle of incidence and polarization of the rays of the focused incident probe beam with layer thickness.

A method of measuring the thickness of a thin film layer on the surface of a substrate comprising the steps of:

• generating a probe beam of radiation;
• focusing the probe beam on the surface of the substrate such that various rays within the focused probe beam create a spread of angles of incidence with respect to said surface;
• measuring the intensity of various rays as a function of position within the reflected beam with the position of the rays within said reflected probe beam corresponding to specific angles of incidence with respect to said surface;
• measuring the total power of the reflected probe beam;
• and
• determining the thickness of the thin film layer based upon both the angular dependent intensity measurements and the total reflected power.