Calibration of semiconductor metrology systems

A method for treatment of calibration substrates used in a calibration process, the method comprising:

• recording a plurality of measurements of a first calibration substrate measured by one or more measuring tools over a predetermined period of time;
• recording a plurality of measurements of product substrates measured by the one or more measuring tools over the predetermined period of time;
• directing ultraviolet light, a plurality of times during the predetermined period of time, to the surface of the calibration substrate while maintaining the temperature of the calibration substrate below a predetermined temperature threshold, thereby removing contaminants from the surface of the calibration substrate;
• establishing a cleaning limit for calibration substrates based on the recorded measurements of the first calibration substrate and the product substrates where a difference criterion between the calibration substrate and product substrate references has been exceeded;
• and
• directing ultraviolet light to the surface of a second calibration substrate until the cleaning limit is reached;
• upon reaching the calibration limit, removing the second calibration substrate from the calibration process.

A cleaning system for use in calibration of measuring tools for use in production of a product substrate, the system comprising:

• an enclosure having a substrate support and a source of electromagnetic radiation;
• and
• a controller operatively coupled to the enclosure, the controller having at least one processor and a memory operatively coupled to the at least one processor, wherein the memory stores instructions, that when executed by the processor, cause the following actions:
• direct electromagnetic radiation from the source towards a surface of the calibration substrate while maintaining a temperature of the calibration substrate below a predetermined temperature threshold, thereby cleaning the calibration surface by removing contaminants from the surface of the calibration substrate.