Method and apparatus employing optical emission spectroscopy to detect a fault in process conditions of a semiconductor processing system

A method for detecting one of a plurality of processing conditions of a semiconductor processing system employing a plasma, said method comprising:

• providing said semiconductor processing system with a plurality of subsystems;
• sensing optical energy produced by said plasma, said optical energy having a plurality of spectral bands associated therewith;
• identifying first, second and third subsets of said plurality of spectral bands, with said first subset having a first intensity associated therewith that varies in response to said one of said plurality of processing conditions, said second subset having a second intensity associated therewith that varies substantially independently of the presence of said one of said plurality of processing conditions, and said third subset having a third intensity associated therewith that varies substantially independently of substantially all of said plurality of processing conditions;
• and
• detecting said one of said plurality of processing conditions as a function of said first, second and third subsets.

An apparatus for characterizing processing conditions of a semiconductor processing system employing a source of light in a processing chamber, said apparatus comprising:

• a detector in optical communication with said processing chamber to sense optical energy generated by said source of light, said optical energy having a plurality of spectral bands associated therewith;
• a spectral 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 set of instructions to cause said processor to operate on said information to identify a first subset of said plurality of spectral bands that has a first intensity associated therewith that varies in response to one of said processing conditions, and a second subset of said plurality of spectral bands that has a second intensity associated therewith that varies substantially independently of said one of said processing conditions and a second set of instructions to cause said processor to operate on said information to identify a third subset of spectral bands having an intensity associated therewith that varies substantially independently of said processing conditions and a third set of instructions to cause said processor to characterize said one of said processing conditions as a function of said first, second and third intensities.

A method for monitoring processing conditions of a semiconductor processing system employing a source of light, said method comprising:

• sensing optical energy produced by said source of light, said optical energy having a plurality of spectral bands associated therewith;
• ascertaining a first subset of said plurality of spectral bands having first and second sets of frequencies associated therewith, with said first and second sets of frequencies having an intensity associated therewith, defining first and second intensities, respectively, with said first intensity varying a first magnitude in response to changes in multiple processing conditions and said second intensity varying a second magnitude in response to said multiple processing conditions, with said second magnitude being less than said first magnitude;
• identifying a second subset of said spectral bands having an intensity associated therewith that varies a third magnitude in response to changes in a subset of said multiple processing conditions, with said third magnitude being less than said first and second magnitudes;
• obtaining a first ratio of intensities of said second subset and said first set of frequencies;
• obtaining a second ratio of said second subset and said second set of frequencies;
• and
• determining a state of one of said multiple processing conditions by comparing said first and second ratios.