Method and apparatus for production line screening

A tool guard for restricting input to a production tool for carrying out a stage in the production of a layered product having a plurality of later thickness values, the tool guard comprising:

• predetermined layers properties data representing an expected part construction for the stage,
• an intensity deriver located at said tool operable to obtain an intensity spectrum of an incoming partly constructed product, said intensity spectrum deriver comprising:
• an illuminator for irradiating a part product at at least one point thereof with a multiple wavelength radiation source, and
• an intensity detector for detecting intensities within reflections of said source from said points,
• an analyzer operatively associated with said intensity deriver for analyzing said intensities in terms of wavelength and converting said analyzed intensities spectrum into a transformation of a frequency spectrum thereof, said analyzer comprising:
• a spectral analyzer for carrying out a spectral analysis of said detected intensities to produce an intensity spectrum, and
• an orthogonal transform calculator, associated with said spectral analyzer, for carrying out said orthogonal transformation of said analyzed intensity spectrum,
• a layer property determiner, associated with said analyzer, for determining, from said orthogonal transformation of said frequency spectrum, layer properties of layers on said part product, and
• a comparator, for comparing layer property determiner output with said predetermined layers properties data to determine whether layer properties of said incoming partly constructed product corresponds with layer properties of said respective predefined part construction for the stage.

A production line router for routing intermediate inputs around a multiple stage production line, the intermediate inputs comprising substrates with at least one superimposed layer, the router comprising:

• predetermined layers properties data for each of a plurality of said stages representing a respective intermediate construction for the stage,
• at least one intensity deriver located within said production line for obtaining intensity spectra of intermediate inputs, said intensity spectrum deriver comprising:
• an illuminator for irradiating a part product at at least one point thereof with a multiple wavelength radiation source,
• an intensity detector for detecting intensities within reflections of said source from said point,
• an analyzer operatively associated with said intensity detector for analyzing said intensities in terms of wavelength and converting said analyzed intensities spectrum into a frequency spectrum thereof, said analyzer comprising:
• a spectrum analyzer, associated with said intensity detector for obtaining a spectral analysis of said intensities, and
• an orthogonal transform calculator, associated with said spectrum analyzer, for applying an orthogonal transformation to said intensity spectrum,
• a layer property determiner, associated with said orthogonal transform calculator, for determining, from said orthogonal transformation of said frequency spectrum, layer properties of layer on said part product, and
• a comparator, for obtaining a closest match between layers defined in said obtained intensity spectrum and layers defined in any of said predetermined layer properties data, said router being operable to route said intermediate input to a stage corresponding to said closest matching spectrum.

A water production history determiner for determining the production history of a semiconductor wafer product having multiple thicknesses, the determiner comprising:

• a plurality of predetermined layer properties data for semiconductor wafer products having completed respective stages of a multiple stage semiconductor wafer production process,
• an intensity deriver for obtaining an intensity spectrum of an incoming semiconductor wafer product said intensity spectrum deriver comprising:
• an illuminator for irradiating a part product at at least one point thereof with a multiple wavelength radiation source, and
• an intensity detector for detecting intensities within reflections of said source from said point,
• an analyzer operatively associated with said intensity detector for analyzing said intensities in terms of wavelength and converting said analyzed intensities spectrum into a transformation of frequency spectrum thereof, said analyzer comprising:
• a spectrum analyzer associated with said intensity detector tin performing a spectral analysis of said intensities, and
• an orthogonal transform calculator, associated with said spectrum analyzer, for carrying out orthogonal transformation of said analyzed intensity spectrum,
• a layer property determiner for determining, from said orthogonal transformation of said frequency spectrum, layer properties of layers on said part products, and
• a comparator, for comparing layers defined in said obtained layers properties with layers defined in each of said predetermined layers properties data, to determine a closest match between said obtained layers properties and one of said predetermined layers properties data, said determiner inferring said production history as including the respective completed stage corresponding to said closest match predetermined layers properties data.

In a production line having a plurality of successive stages for construction of a product comprising a plurality of layer thickness values on a substrate, and routers for transferring a partly constructed product between the stages such that each stage receives a respective predefined partly constructed product as its input, and having a predetermined intensity spectrum associated with at least one stage representing the respective part construction for the stage, a method comprising:

• obtaining intensity spectra of partly constructed products incoming to said stage, said obtaining comprising
• irradiating a part product at least one point thereof with a multiple wavelength radiation source,
• detecting intensities within reflections of said source from said point,
• analyzing said intensities in terms of wavelength, thereby to produce a spectrum of intensities at respective wavelengths,
• transforming said spectrum of intensities into a frequency spectrum using orthogonal transformation of said spectrum of intensities,
• determining, from said orthogonal analysis of said frequency spectrum, layer properties of layers on said part product, and
• comparing said layer properties with layer properties of said predetermined intensity spectrum and thereby determining whether said incoming partly constructed product corresponds with said respective predefined part construction for the respective stage.