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 . 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 selected from the group consisting of one or more angles of reflection and one or more wavelengths; and    comparing one or more characteristics of the back-scattered light by performing an operation comprising examining data from complementary angles of reflection.    
   
   
       2 . The method of  claim 1  wherein the directing step comprises directing light at substantially a single wavelength.  
   
   
       3 . The method of  claim 1  wherein the directing step comprises directing light at a plurality of wavelengths.  
   
   
       4 . The method of  claim 1  wherein the comparing step comprises comparing light intensity.  
   
   
       5 . The method of  claim 1  wherein the comparing step additionally comprises comparing phase.  
   
   
       6 . The method of  claim 1  wherein the comparing step additionally comprises comparing ratios of light magnitude and light phase.  
   
   
       7 . The method of  claim 1  wherein the directing step comprises directing light at an array of microelectronic features in general conical configuration.  
   
   
       8 . The method of  claim 1  wherein the directing and detecting steps are performed by an angular scatterometer.  
   
   
       9 . The method of  claim 1  wherein the directing and detecting steps are performed by a spectral scatterometer.  
   
   
       10 . The method of  claim 1  wherein the comparing step comprises decomposing back-scattered light into S and P components relative to a plane of incidence.  
   
   
       11 . The method of  claim 1  wherein the detecting step comprises detecting specular order diffracted light.  
   
   
       12 . The method of  claim 1  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.  
   
   
       13 . The method of  claim 12  additionally comprising the step of controlling a manufacturing process if results of the comparing step indicate an asymmetry in the array.  
   
   
       14 . 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 selected from the group consisting of one or more angles of reflection and one or more wavelengths; and    means for comparing one or more characteristics of the back-scattered light by performing an operation comprising examining data from complementary angles of reflection.    
   
   
       15 . The apparatus of  claim 14  wherein said directing means comprises means for directing light at substantially a single wavelength.  
   
   
       16 . The apparatus of  claim 14  wherein said directing means comprises means for directing light at a plurality of wavelengths.  
   
   
       17 . The apparatus of  claim 14  wherein said comparing means additionally comprises means for comparing light intensity.  
   
   
       18 . The apparatus of  claim 14  wherein said comparing means additionally comprises means for comparing phase.  
   
   
       19 . The apparatus of  claim 14  wherein said comparing means additionally comprises means for comparing ratios of light magnitude and light phase.  
   
   
       20 . The apparatus of  claim 14  wherein said directing means comprises means for directing light at an array of microelectronic features in general conical configuration.  
   
   
       21 . The apparatus of  claim 14  wherein said directing and detecting means comprise an angular scatterometer.  
   
   
       22 . The apparatus of  claim 14  wherein said directing and detecting means comprise a spectral scatterometer.  
   
   
       23 . The apparatus of  claim 14  wherein said comparing means comprises means for decomposing back-scattered light into S and P components relative to a plane of incidence.  
   
   
       24 . The apparatus of  claim 14  wherein said detecting means comprises means for detecting specular order diffracted light.  
   
   
       25 . The apparatus of  claim 14  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.  
   
   
       26 . The apparatus of  claim 25  additionally comprising means for controlling a manufacturing process if said comparing means indicates an asymmetry in the array.  
   
   
       27 . 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 selected from the group consisting of one or more angles of reflection and one or mare wavelengths; and    comparing one or more characteristics of the back-scattered light by performing an operation comprising performing a model comparison with an asymmetric model.    
   
   
       28 . The method of  claim 27  wherein the directing step comprises directing light at substantially a single wavelength.  
   
   
       29 . The method of  claim 27  wherein the directing step comprises directing light at a plurality of wavelengths.  
   
   
       30 . The method of  claim 27  wherein the comparing step comprises comparing light intensity.  
   
   
       31 . The method of  claim 27  wherein the comparing step additionally comprises comparing phase.  
   
   
       32 . The method of  claim 27  wherein the comparing step additionally comprises comparing ratios of light magnitude and light phase.  
   
   
       33 . The method of  claim 27  wherein comparing comprises a model comparison with a library of asymmetric models.  
   
   
       34 . The method of  claim 27  wherein comparing comprises a model comparison by regression analysis with an asymmetric model.  
   
   
       35 . The method of  claim 27  wherein the directing step comprises directing light at an array of microelectronic features in general conical configuration.  
   
   
       36 . The method of  claim 27  wherein the directing and detecting steps are performed by an angular scatterometer.  
   
   
       37 . The method of  claim 27  wherein the directing and detecting steps are performed by a spectral scatterometer.  
   
   
       38 . The method of  claim 27  wherein the comparing step comprises decomposing back-scattered light into S and P components relative to a plane of incidence.  
   
   
       39 . The method of  claim 27  wherein the detecting step comprises detecting specular order diffracted light.  
   
   
       40 . The method of  claim 27  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.  
   
   
       41 . The method of  claim 40  additionally comprising the step of controlling a manufacturing process if results of the comparing step indicate an asymmetry in the array.  
   
   
       42 . 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 selected from the group consisting of one or more angles of reflection and one or more wavelengths; and    means for comparing one or more characteristics of the back-scattered light by performing an operation comprising performing a model comparison with an asymmetric model.    
   
   
       43 . The apparatus of  claim 42  wherein said directing means comprises means for directing light at substantially a single wavelength.  
   
   
       44 . The apparatus of  claim 42  wherein said directing means comprises means for directing light at a plurality of wavelengths.  
   
   
       45 . The apparatus of  claim 42  wherein said comparing means additionally comprises means for comparing light intensity.  
   
   
       46 . The apparatus of  claim 42  wherein said comparing means additionally comprises means for comparing phase.  
   
   
       47 . The apparatus of  claim 42  wherein said comparing means additionally comprises means for comparing ratios of light magnitude and light phase.  
   
   
       48 . The apparatus of  claim 42  wherein said means for comparing comprises a model comparison with a library of asymmetric models.  
   
   
       49 . The apparatus of  claim 42  wherein said means for comparing comprises a model comparison by regression analysis with an asymmetric model.  
   
   
       50 . The apparatus of  claim 42  wherein said directing means comprises means for directing light at an array of microelectronic features in general conical configuration.  
   
   
       51 . The apparatus of  claim 42  wherein said directing and detecting means comprise an angular scatterometer.  
   
   
       52 . The apparatus of  claim 42  wherein said directing and detecting means comprise a spectral scatterometer.  
   
   
       53 . The apparatus of  claim 42  wherein said comparing means comprises means for decomposing back-scattered light into S and P components relative to a plane of incidence.  
   
   
       54 . The apparatus of  claim 42  wherein said detecting means comprises means for detecting specular order diffracted light.  
   
   
       55 . The apparatus of  claim 42  additionally comprising means for employing the results or 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.  
   
   
       56 . The apparatus of  claim 55  additionally comprising means for controlling a manufacturing process if said comparing means indicates an asymmetry in the array.  
   
   
       57 . A method of measuring misalignments in devices, the method comprising the steps of: 
 directing radiation at periodic structures of features of a device;    detecting radiation scattered back from the periodic structures comprising one or more features selected from the group consisting of one or more polarization angles and one or more wavelengths; and    comparing one or more characteristics of the back-scattered light by performing an operation comprising examining data from polarization angles.    
   
   
       58 . The method of  claim 57  wherein the directing step comprises directing radiation at substantially a single wavelength.  
   
   
       59 . The method of  claim 57  wherein the directing step comprises directing radiation at different wavelengths.  
   
   
       60 . The method of  claim 57  wherein the comparing step comprises comparing light intensity with a reference signal.  
   
   
       61 . The method of  claim 57  wherein the comparing step additionally comprises comparing phase.  
   
   
       62 . The method of  claim 57  wherein the directing and detecting steps are performed by a scatterometer.  
   
   
       63 . The method of  claim 57  wherein the directing and detecting steps are performed by a spectral scatterometer.  
   
   
       64 . The method of  claim 57 , wherein the comparing step comprises polarizing back-scattered light into S and P components relative to a plane of incidence.  
   
   
       65 . The method of  claim 57  wherein the detecting step comprises detecting specular order diffracted radiation.  
   
   
       66 . The method of  claim 57  additionally comprising the step of employing the results of the comparing step to detect misalignment selected from the group consisting of misalignment within a single layer of the device and misalignment within multiple layers of the device.  
   
   
       67 . The method of  claim 66  additionally comprising the step of correcting a manufacturing process if results of the comparing step indicate misalignment of the periodic structures before providing another layer or periodic structure on the wafer.  
   
   
       68 . An apparatus for measuring misalignment in devices, said apparatus comprising: 
 means for directing radiation at periodic structures of features of a device;    means for detecting radiation from the periodic structures comprising one or more features selected from the group consisting of one or more polarization angles and one or more wavelengths; and    means for comparing one or more characteristics of the back-scattered light by performing an operation comprising examining data from polarization angles.    
   
   
       69 . The apparatus of  claim 68  wherein said directing means comprises means for directing light at substantially a single wavelength.  
   
   
       70 . The apparatus of  claim 68  wherein said directing means comprises means for directing light at different wavelengths.  
   
   
       71 . The apparatus of  claim 68  wherein said comparing means additionally comprises means for comparing light intensity with a reference signal.  
   
   
       72 . The apparatus of  claim 68  wherein said comparing means additionally comprises means for comparing phase.  
   
   
       73 . The apparatus of  claim 68  wherein said directing and detecting means comprise a scatterometer.  
   
   
       74 . The apparatus of  claim 68  wherein said directing and detecting means comprise a spectral scatterometer.  
   
   
       75 . The apparatus of  claim 68 , wherein said comparing means comprises means for polarizing back-scattered light into S and P components relative to a plane of incidence.  
   
   
       76 . The apparatus of  claim 68  wherein said detecting means comprises means for detecting specular order diffracted radiation.  
   
   
       77 . The apparatus of  claim 68  additionally comprising means for employing the results of the comparing step to detect misalignment selected from the group consisting of misalignment within a single layer of the device and misalignment within multiple layers of the device.  
   
   
       78 . The apparatus of  claim 77  additionally comprising means for correcting a manufacturing process if said comparing means indicates misalignment of the periodic structures before providing another layer or periodic structure on the wafer.  
   
   
       79 . A method of measuring misalignment in devices, the method comprising the steps of: 
 directing radiation at periodic structures of features of a device;    detecting diffracted radiation from the periodic structures comprising one or more features selected from the group consisting of one or more polarization angles and one or mare wavelengths; and    comparing one or more characteristics of the diffracted radiation by performing an operation comprising performing a comparison with a reference signal.    
   
   
       80 . The method of  claim 79  wherein the directing step comprises directing light at substantially a single wavelength.  
   
   
       81 . The method of  claim 79  wherein the directing step comprises directing light at a plurality of wavelengths.  
   
   
       82 . The method of  claim 79  wherein the comparing step comprises comparing light intensity with a reference signal.  
   
   
       83 . The method of  claim 79  wherein the comparing step additionally comprises comparing phase.  
   
   
       84 . The method of  claim 79  wherein comparing comprises correlating misalignment and data comprising intensity, polarization angle and/or phase information with a reference.  
   
   
       85 . The method of  claim 79  wherein the directing and detecting steps are performed by a scatterometer.  
   
   
       86 . The method of  claim 79  wherein the directing and detecting steps are performed by a spectral scatterometer.  
   
   
       87 . The method of  claim 79 , wherein the comparing step comprises polarizing back-scattered light into S and P components relative to a plane of incidence.  
   
   
       88 . The method of  claim 79  wherein the detecting step comprises detecting specular order diffracted radiation.  
   
   
       89 . The method of  claim 79  additionally comprising the step of employing the results of the comparing step to detect misalignment selected from the group consisting of misalignment within a single layer of the device and misalignment within multiple layers of the device.  
   
   
       90 . The method of  claim 89  additionally comprising the step of correcting a manufacturing process if results of the comparing step indicate misalignment of the periodic structures before providing another layer or periodic structure on the wafer.  
   
   
       91 . An apparatus for measuring misalignment in devices, said apparatus comprising: 
 means for directing radiation at a periodic structure of features of a device;    means for detecting diffracted radiation from the periodic structures comprising one or more features selected from the group consisting of one or more polarization angles and one or more wavelengths; and    means for comparing one or more characteristics of the diffracted radiation by performing an operation comprising performing a comparison with a reference signal.    
   
   
       92 . The apparatus of  claim 91  wherein said directing means comprises means for directing light at substantially a single wavelength.  
   
   
       93 . The apparatus of  claim 91  wherein said directing means comprises means for directing light at a plurality of wavelengths.  
   
   
       94 . The apparatus of  claim 91  wherein said comparing means additionally comprises means for comparing light intensity with a reference signal.  
   
   
       95 . The apparatus of  claim 91  wherein said comparing means additionally comprises means for comparing phase.  
   
   
       96 . The apparatus of  claim 91  wherein said means for comparing comprises correlating misalignment and data comprising intensity, polarization angle and/or phase information.  
   
   
       97 . The apparatus of  claim 91  wherein said directing and detecting means comprise a scatterometer.  
   
   
       98 . The apparatus of  claim 91  wherein said directing and detecting means comprise a spectral scatterometer.  
   
   
       99 . The apparatus of  claim 91 , wherein said comparing means comprises means for polarizing back-scattered light into S and P components relative to a plane of incidence.  
   
   
       100 . The apparatus of  claim 91  wherein said detecting means comprises means for detecting specular order diffracted radiation.  
   
   
       101 . The apparatus of  claim 91  additionally comprising means for employing the results or the comparing step to detect misalignment selected from the group consisting of misalignment within a single layer of the device and misalignment within multiple layers of the device.  
   
   
       102 . The apparatus of  claim 101  additionally comprising means for correcting a manufacturing process if said comparing means indicates a misalignment before providing another layer or periodic structure on the wafer.