Method and apparatus for accurate calibration of a reflectometer by using a relative reflectance measurement

A method of calibrating a system that obtains reflectance data, comprising:

• obtaining reflectance data from a first calibration sample;
• obtaining reflectance data from a second calibration sample, wherein exact properties of the at least one of the first and second calibration samples may vary from assumed properties of the calibration samples and wherein the reflective properties of the first and second calibration samples differ;
• and
• utilizing a ratio based upon the data obtained from the first calibration sample and the data obtained from the second calibration sample in order to assist in calibrating the system,
• wherein a first set of reflectance data is collected from the first calibration sample, the first calibration sample having a calibration error function in a first wavelength region in which calibration is desired and a second set of reflectance data is collected from the second calibration sample, the second calibration sample having less spectral features as compared to the standard sample in the first wavelength region,
• wherein the first calibration sample has a thicker oxide as compared to a thinner oxide on the second calibration sample,
• wherein the first calibration sample comprises an SiO2/Si structure and the second calibration sample comprises an SiO2/Si structure, and
• wherein the thinner oxide on the second calibration sample is a native oxide film.

A method of calibrating a system that obtains reflectance data, comprising:

• obtaining reflectance data from a first calibration sample;
• obtaining reflectance data from a second calibration sample, wherein exact properties of the at least one of the first and second calibration samples may vary from assumed properties of the calibration samples and wherein the reflective properties of the first and second calibration samples differ;
• and
• utilizing a ratio based upon the data obtained from the first calibration sample and the data obtained from the second calibration sample in order to assist in calibrating the system,
• wherein the reflectance data from the first calibration sample is decoupled from the reflectance data from the second calibration sample,
• wherein the first calibration sample has a thicker oxide as compared to a thinner oxide on the second calibration sample, and
• wherein the thinner oxide on the second calibration sample is a native oxide.

A method of calibrating a system that obtains reflectance data, comprising:

• obtaining reflectance data from a first calibration sample;
• obtaining reflectance data from a second calibration sample, wherein exact properties of the at least one of the first and second calibration samples may vary from assumed properties of the calibration samples and wherein the reflective properties of the first and second calibration samples differ;
• and
• utilizing a ratio based upon the data obtained from the first calibration sample and the data obtained from the second calibration sample in order to assist in calibrating the system,
• wherein the first calibration sample has a thicker oxide as compared to a thinner oxide on the second calibration sample,
• wherein the first calibration sample comprises an SiO2/Si structure and the second calibration sample comprises an SiO2/Si structure, and
• wherein the second calibration sample is a spectrally featureless reference sample.

A method of calibrating a system that obtains reflectance data, comprising:

• obtaining reflectance data from a first calibration sample;
• obtaining reflectance data from a second calibration sample, wherein exact properties of the at least one of the first and second calibration samples may vary from assumed properties of the calibration samples and wherein the reflective properties of the first and second calibration samples differ;
• and
• utilizing a ratio based upon the data obtained from the first calibration sample and the data obtained from the second calibration sample in order to assist in calibrating the system,
• wherein the utilizing step further comprises:
• configuring a calibration routine to utilize a first set of reflectance data from the first calibration sample and to provide a first calibration of the system based at least in part upon the first set of reflectance data;
• and
• configuring the calibration routine to utilize a second set of reflectance data from the second calibration sample, the second set of reflectance data having less features than the first set of reflectance data.

A method of calibrating a system that obtains reflectance data comprising:

• obtaining reflectance data from a first calibration sample;
• obtaining reflectance data from a second calibration sample, wherein exact properties of the at least one of the first and second calibration samples may vary from assumed properties of the calibration samples and wherein the reflective properties of the first and second calibration samples differ;
• and
• utilizing a ratio based upon the data obtained from the first calibration sample and the data obtained from the second calibration sample in order to assist in calibrating the system
• wherein the data obtained from the first calibration sample is intensity data and the data obtained from the second calibration sample is intensity data, and
• wherein a reflectance ratio is obtained from the intensity data of the first and second calibration samples.