Periodic patterns and technique to control misalignment between two layers

Abstract

A method and system to measure misalignment error between two overlying or interlaced periodic structures are proposed. The overlying or interlaced periodic structures are illuminated by incident radiation, and the diffracted radiation of the incident radiation by the overlying or interlaced periodic structures are detected to provide an output signal. The misalignment between the overlying or interlaced periodic structures may then be determined from the output signal.

1 - 54 . (canceled)  
   
   
       55 . A method of measuring line profile asymmetries in microelectronic devices, the method comprising the steps of: 
 directing light at an array of microelectronic features of a microelectronic device;    detecting light scattered back from the array comprising one or more features at one or more wavelengths; and    comparing one or more characteristics of the back-scattered light by performing a model comparison.    
   
   
       56 . The method of  claim 55  wherein the directing step comprises directing light at substantially a single wavelength.  
   
   
       57 . The method of  claim 55  wherein the directing step comprises directing light at a plurality of wavelengths.  
   
   
       58 . The method of  claim 55 , wherein the comparing step comprises comparing light intensity.  
   
   
       59 . The method of  claim 55 , wherein the comparing step additionally comprises comparing phase.  
   
   
       60 . The method of  claim 55 , wherein the comparing step additionally comprises comparing ratios of light magnitude and light phase.  
   
   
       61 . The method of  claim 55 , wherein the directing and detecting steps are performed by a spectral scatterometer.  
   
   
       62 . The method of  claim 55 , wherein the detecting step comprises decomposing back-scattered light into S and P components relative to a plane of incidence.  
   
   
       63 . The method of  claim 55 , wherein the detecting step comprises detecting specular order diffracted light.  
   
   
       64 . The method of  claim 55 , additionally comprising the step of employing the results of the comparing step to detect asymmetries selected from the group consisting of asymmetries within a single layer of the microelectronic device and asymmetries within multiple layers of the microelectronic device.  
   
   
       65 . The method of  claim 64 , additionally comprising the step of controlling a manufacturing process if results of the comparing step indicate an asymmetry in the array.  
   
   
       66 . An apparatus for measuring line-profile asymmetries in microelectronic devices, said apparatus comprising: 
 means for directing light at an array of microelectronic features of a microelectronic device;    means for detecting light scattered back from the array comprising one or more features at one or more wavelengths; and    means for comparing one or more characteristics of the back-scattered light by performing a model comparison.    
   
   
       67 . The apparatus of  claim 66  wherein said directing means comprises means for directing light at substantially a single wavelength.  
   
   
       68 . The apparatus of  claim 66  wherein said directing means comprises means for directing light at a plurality of wavelengths.  
   
   
       69 . The apparatus of  claim 66  wherein said comparing means additionally comprises means for comparing light intensity.  
   
   
       70 . The apparatus of  claim 66  wherein said comparing means additionally comprises means for comparing phase.  
   
   
       71 . The apparatus of  claim 66  wherein said comparing means additionally comprises means for comparing ratios of light magnitude and light phase.  
   
   
       72 . The apparatus of  claim 66  wherein said directing and detecting means comprise a spectral scatterometer.  
   
   
       73 . The apparatus of  claim 66  wherein said detecting means comprises means for decomposing back-scattered light into S and P components relative to a plane of incidence.  
   
   
       74 . The apparatus of  claim 66  wherein said detecting means comprises means for detecting specular order diffracted light.  
   
   
       75 . The apparatus of  claim 66 , additionally comprising means for employing the results of the comparing step to detect asymmetries selected from the group consisting of asymmetries within a single layer of the microelectronic device and asymmetries within multiple layers of the microelectronic device.  
   
   
       76 . The apparatus of  claim 75  additionally comprising means for controlling a manufacturing process if said comparing means indicates an asymmetry in the array.