Method and system for non-destructive distribution profiling of an element in a film
View Patent ↗A method to determine a distribution profile of an element in a film. The method comprises exciting an electron energy of an element deposited in a first film, obtaining a first spectrum associating with the electron energy, and removing a background spectrum from the first spectrum. Removing the background value generates a processed spectrum. The method further includes matching the processed spectrum to a simulated spectrum with a known simulated distribution profile for the element in a film comparable to the first film. A distribution profile is obtained for the element in the first film based on the matching of the processed spectrum to a simulated spectrum selected from the set of simulated spectra.
1. A method comprising:
obtaining a first spectrum associated with an electron energy excited from one or more elements in a sample film;
obtaining a processed spectrum, said processed spectrum having a background spectrum removed from said first spectrum;
optimizing a simulated spectrum as a function of element distribution profile for said one or more elements;
matching said processed spectrum to said simulated spectrum using a minimization algorithm; and
determining a distribution profile for said one or more elements in said sample film based on the matching and minimizing.
2. The method of claim 1 , farther comprising at least one of:
determining a centroid value for said one or more elements in said sample film;
determining a dose level for said one or more elements in said sample film;
correcting a dose level for said element for said one or more elements in said sample film;
predicting an electrical parameter for a device to be formed in or on said sample film; and
controlling an electrical parameter for a device to be formed in or on said sample film.
3. The method of claim 1 , farther comprising:
determining a centroid value for said one or more elements in said sample film;
determining a thickness of said sample film;
obtaining a ratio of said centroid value and said thickness for said sample film; and
performing one of monitoring, predicting, and controlling one or more electrical parameters for one or more devices to be formed in or formed on said sample film.
4. The method of claim 1 , wherein obtaining said processed further comprising:
obtaining a set of background values spectra from films comparable to said sample film and without having said element being deposited therein, each of said background spectra having a value associated with a selected parameter surrounding said film;
generating a background table comprising said background spectra as a function of said selected parameter; and
selecting a background value to be used for said sample film based on said selected parameter surrounding said sample film including one of (a) choosing a background spectrum selected from said set of background spectra that has a selected parameter matching said sample film, and (b) interpolating a background spectrum using said background table and said selected parameter.
5. The method of claim 1 , wherein said first spectrum is obtained using a photoelectron spectroscopy system at a constant emission angle.
6. The method of claim 1 , wherein said first spectrum is obtained using a photoelectron spectroscopy system at a constant emission angle selected from a range of 0-45 degrees.
7. The method of claim 1 , wherein said first spectrum is obtained using a photoelectron spectroscopy system and wherein said first spectrum is selected from multiple and simultaneous measurements at multiple emission angles wherein each measurement is performed at a constant emission angle.
8. The method of claim 1 , wherein optimizing the simulated spectrum as a function of element distribution profile and matching said processed spectrum to said simulated spectrum further comprises minimizing pre-computed figure of merit for the simulated spectrum and determining minimization by interpolation from a figure of merit surface.
9. The method of claim 1 , wherein said simulated spectrum is from a set of simulated spectra with associated element distribution profiles and
wherein optimizing the simulated spectrum as a function of element distribution profile and matching said processed spectrum to said simulated spectrum farther comprises associating the distribution profile for said one or more elements in said sample film to a parameterized family of curves that is used to generate the simulated spectra.
10. The method of claim 1 , wherein said background spectrum removed from said first spectrum is a reconstructed background spectrum.
11. The method of claim 10 , wherein said reconstructed background spectrum is extracted from a measured spectrum containing a superposition of a plurality of elements and a plurality of respective several species associated with said elements.
12. The method of claim 1 , wherein optimizing the simulated spectrum as a function of element distribution profile and matching said processed spectrum to said simulated spectrum further comprises defining one or more parameters used to generate the simulated spectrum.
13. The method of claim 12 , wherein said one or more parameters are chosen based on a Signal-to-Noise analysis.