Time-domain optical metrology and inspection of semiconductor devices

Abstract

Semiconductor device metrology including creating a time-domain representation of wavelength-domain measurement data of light reflected by a patterned structure of a semiconductor device, selecting an earlier-in-time portion of the time-domain representation that excludes a later-in-time portion of the time-domain representation, and determining one or more measurements of one or more parameters of interest of the patterned structure by performing model-based processing using the earlier-in-time portion of the time-domain representation.

1 . A method for semiconductor device metrology, the method comprising:
 performing a plurality optical measurements of light reflected from a plurality of different locations on a semiconductor device, thereby obtaining wavelength-domain measurement data from the reflected light, wherein the wavelength-domain measurement data includes spectral amplitude of the reflected light and spectral phase of the reflected light;   creating a plurality of time-domain representations of the wavelength-domain measurement data;   identifying a plurality of points in the time-domain representations corresponding to a plurality of heights of the plurality of different locations on the semiconductor device; and   determining a differential between any of the plurality of heights of the plurality of different locations on the semiconductor device.   
     
     
         2 . The method according to  claim 1  wherein the plurality of different locations on the semiconductor device lie along a line defined by at least a first location on the semiconductor device and a second location on the semiconductor device. 
     
     
         3 . The method according to  claim 1  wherein the plurality of different locations on the semiconductor device lie along a line defined by a sequence of locations on the semiconductor device, where the sequence of locations is known to be continuously increasing in height or decreasing in height. 
     
     
         4 . The method according to  claim 1  wherein any of the plurality of different locations on the semiconductor device comprises any of SiO 2  and SiN. 
     
     
         5 . The method according to  claim 1  wherein the optical measurements include spectral measurements of between 200 nm-1000 nm. 
     
     
         6 . The method according to  claim 1  and further comprising using the height differential to control chemical-mechanical polishing (CMP) of the semiconductor device. 
     
     
         7 . A system for semiconductor device metrology, the system comprising:
 an optical metrology tool configured to perform a plurality optical measurements of light reflected from a plurality of different locations on a semiconductor device, thereby obtaining wavelength-domain measurement data from the reflected light, wherein the wavelength-domain measurement data includes spectral amplitude of the reflected light and spectral phase of the reflected light;   a spectrum processing unit configured create a plurality of time-domain representations of the wavelength-domain measurement data; and   a metrology unit configured to
 identify a plurality of points in the time-domain representations corresponding to a plurality of heights of the plurality of different locations on the semiconductor device, and 
 determine a differential between any of the plurality of heights of the plurality of different locations on the semiconductor device. 
   
     
     
         8 . The system according to  claim 7  wherein the plurality of different locations on the semiconductor device lie along a line defined by at least a first location on the semiconductor device and a second location on the semiconductor device. 
     
     
         9 . The system according to  claim 7  wherein the plurality of different locations on the semiconductor device lie along a line defined by a sequence of locations on the semiconductor device, where the sequence of locations is known to be continuously increasing in height or decreasing in height. 
     
     
         10 . The system according to  claim 7  wherein any of the plurality of different locations on the semiconductor device comprises any of SiO 2  and SiN. 
     
     
         11 . The system according to  claim 7  wherein the optical measurements include spectral measurements of between 200 nm-1000 nm. 
     
     
         12 . The system according to  claim 7  wherein the metrology unit is configured to use the height differential to control chemical-mechanical polishing (CMP) of the semiconductor device.