US 9,812,996 B2
Method for calculating distance, method for neutralizing electrostatic chuck, and processing apparatus
Kenji Nagai, Miyagi (JP); and Yoshinobu Ooya, Miyagi (JP)
Assigned to TOKYO ELECTRON LIMITED, Tokyo (JP)
Filed by TOKYO ELECTRON LIMITED, Tokyo (JP)
Filed on Nov. 17, 2014, as Appl. No. 14/542,979.
Claims priority of application No. 2013-253271 (JP), filed on Dec. 6, 2013.
Prior Publication US 2015/0162233 A1, Jun. 11, 2015
Int. Cl. H01L 21/683 (2006.01); G01B 11/14 (2006.01); H02N 13/00 (2006.01)
CPC H02N 13/00 (2013.01) [G01B 11/14 (2013.01); H01L 21/6831 (2013.01)] 3 Claims
OG exemplary drawing
 
1. A method for obtaining a distance between a back surface of a target object to be processed and a base portion of an electrostatic chuck when the target object is mounted on the electrostatic chuck, wherein the electrostatic chuck has an upper surface including the base portion and a plurality of convex portions projecting from the base portion and the target object is mounted on apexes of the convex portions of the electrostatic chuck such that the back surface is in contact with the apexes, the method comprising:
acquiring, by using a spectroscope, a first wavelength spectrum, with respect to intensity, of reflected light of light emitted from a light source and irradiated on the back surface of the target object and the base portion of the electrostatic chuck;
acquiring a second wavelength spectrum by converting the first wavelength spectrum into a wavelength spectrum of reflectivity based on a wavelength spectrum of the light emitted from the light source;
acquiring a first wavenumber spectrum by converting a wavelength of the second wavelength spectrum into a wavenumber;
acquiring a second wavenumber spectrum by interpolating the first wavenumber spectrum at regular intervals in a wavenumber direction;
acquiring a third wavenumber spectrum by subjecting the second wavenumber spectrum to a first correction process to equalize reflectivities of both ends of the second wavenumber spectrum in the wavenumber direction;
acquiring a first optical path length spectrum by subjecting the third wavenumber spectrum to fast Fourier transform;
acquiring a second optical path length spectrum by subjecting the first optical path length spectrum to a filtering process to remove components of an optical path length corresponding to a thickness of the target object from the first optical path length spectrum;
acquiring a fourth wavenumber spectrum by subjecting the second optical path length spectrum to inverse fast Fourier transform;
acquiring a fifth wavenumber spectrum by subjecting the fourth wavenumber spectrum to a second correction process which is an inverse of the first correction process;
acquiring a third wavelength spectrum by converting a wavenumber of the fifth wavenumber spectrum into a wavelength;
acquiring a fourth wavelength spectrum by normalizing the third wavelength spectrum by using a normalization wavelength spectrum by indicating characteristics of the spectroscope based on the light emitted from the light source; and
calculating the distance based on a peak wavelength or a valley wavelength in the fourth wave length spectrum.