Monitoring of film characteristics during plasma-based semi-conductor processing using optical emission spectroscopy

A method for monitoring characteristics of films exposed to a plasma in a semiconductor processing chamber:

• sensing optical energy produced by said plasma, said optical energy having a plurality of spectral bands associated therewith;
• identifying a plurality of subsets of said plurality of spectral bands each of which has an intensity associated therewith that varies in response to variations of said characteristics, defining a correlated intensity;
• identifying a subgroup of said plurality of spectral bands that has an intensity associated therewith that varies minimally in response to variations of said characteristics, defining a disjunctive intensity;
• and
• measuring said characteristics, defining measured characteristics, by quantizing said disjunctive intensity, defining a disjunctive quantization, and quantizing the correlated intensity associated with each of said plurality of subsets, forming multiple correlated quantizations, with each of said multiple quantizations corresponding to one of said plurality of subsets and obtaining a ratio of said disjunctive quantization and each of said multiple correlated quantizations forming a set of multiple ratios and summing said multiple ratios in said set.

A system for monitoring characteristics of films exposed to a plasma in a semiconductor processing chamber, said system comprising:

• a detector in optical communication with said processing chamber to sense optical energy generated by said plasma, said optical energy having a plurality of spectral bands associated therewith;
• a spectrum analyzer, in electrical communication with said optical detector, to resolve said spectral bands and produce information corresponding thereto;
• a processor in electrical communication with said spectrum analyzer;
• and
• a memory in electrical communication with said processor, said memory comprising a computer-readable medium having a computer-readable program embodied therein, said computer-readable program including a first set of instructions to cause said processor to operate on said information and identify a plurality of subsets of said plurality of spectral bands having data corresponding to said characteristics;
• and a second set of instructions to control said processor to measure said characteristics as a function of said information by sensing an intensity associated with each of said plurality of subsets, quantizing said intensity to produce a set of multiple quantizations, and summing said multiple quantizations, with each of said multiple quantizations corresponding to one of said plurality of subsets.

A method for monitoring characteristics of films exposed to a source of light in a semiconductor processing chamber, said method comprising:

• sensing optical energy produced by said source of light, said optical energy having a plurality of spectral bands associated therewith;
• identifying a subset of said plurality of spectral bands, including information corresponding to said characteristics;
• obtaining a sequence of measurements of said subset at differing intervals of time, defining a sequence of measured intensity data;
• normalizing said sequence of measured intensity data to produce a normalized sequence of intensity data;
• obtaining a linear function from said normalized sequence of intensity data and said sequence of measured data;
• and
• measuring said characteristics as a function of a product of said linear function and a sum of the data in said normalized sequence of intensity data.