Optically Absorptive Material for Alignment Marks

Abstract

Imprint lithography templates having alignment marks with highly absorptive material. The alignment marks are insensitive to the effects of liquid spreading and can provide stability and increase contrast to alignment system during liquid imprint filling of template features.

What is claimed is: 
     
         1 . A method for aligning a template with a substrate in an imprint lithography process, the method comprising:
 providing an imprint lithography template having
 a body having a first side and a second side; 
 a mold having a patterned surface, the mold positioned on the first side of the body, the patterned surface having a feature area defining a first pattern; and 
 a template alignment mark formed in the patterned surface outside of the feature area, the template alignment mark having a plurality of features that include a highly optically absorptive material having an extinction coefficient k value greater than 2.8 at 600 nm. 
   providing a substrate having a substrate alignment mark;   depositing a polymerizable material on the substrate;   positioning the template in a spaced-apart position from the substrate;   adjusting the distance between the template and the substrate such that the polymerizable material fills the template alignment mark features;   determining the overlay error between the template alignment mark and the substrate alignment mark; and   varying the position of the template relative to the substrate such that the template alignment marks and the substrate alignment marks are aligned.   
     
     
         2 . The method of  claim 1  wherein the steps of determining overlay error and varying the position of the template relative to the substrate are performed as the polymerizable material is filling the template alignment mark features. 
     
     
         3 . The method of  claim 2  wherein the step of determining overlay error further comprises illuminating the alignment marks to generate moiré-based patterns and analyzing the generated moire-based patterns to determine the overlay error. 
     
     
         4 . The method of  claim 3  wherein the generated moiré-based pattern has a contrast value of at least 0.3. 
     
     
         5 . The method of  claim 4  wherein the template alignment mark features includes a plurality of recessions with the highly absorptive material located in the recessions and wherein the thickness of the highly absorptive material in the template alignment mark recessions is less than 20 nm. 
     
     
         6 . The method of  claim 1  wherein the highly absorptive material absorbs at least 60% of incident light from 500 to 800 nm and transmits ultraviolet (UV) radiation. 
     
     
         7 . The method of  claim 1  wherein the highly absorptive material has an extinction coefficient k value greater than 3.3 at 600 nm. 
     
     
         8 . The method of  claim 1  wherein the highly absorptive material further comprises aluminum (Al), aluminum alloys including Al x Si y , Al x Si y Ti z , Al x Cu y , AlxCr y ; rhodium (Rh), chromium (Cr), iridium (Ir), niobium (Nb), titanium (Ti); nickel (Ni), palladium (Pd), platinum (Pt), silver (Ag), gold (Au), copper (Cu), or iron (Fe). 
     
     
         9 . The method of  claim 1  wherein the highly absorptive material further comprises aluminum (Al), rhodium (Rh), chromium (Cr), or niobium (Nb). 
     
     
         10 . The method of  claim 1  wherein the highly absorptive material further comprises aluminum (Al). 
     
     
         11 . A method of forming a patterned layer on a substrate in an imprint lithography process, the method comprising the steps:
 aligning the template and the substrate according to the method of  claim 1 ;   solidifying the polymerizable material to form the patterned layer; and   separating the template from the formed patterned layer.   
     
     
         12 . The method of  claim 11  wherein the steps of determining overlay error and varying the position of the template relative to the substrate are performed as the polymerizable material is filling the template alignment mark features. 
     
     
         13 . The method of  claim 12  wherein the step of determining overlay error further comprises illuminating the alignment marks to generate moiré-based patterns and analyzing the generated moire-based patterns to determine the overlay error. 
     
     
         14 . The method of  claim 13  wherein the generated moiré-based pattern has a contrast value of at least 0.3. 
     
     
         15 . The method of  claim 14  wherein the template alignment mark features includes a plurality of recessions with the highly absorptive material located in the recessions and wherein the thickness of the highly absorptive material in the template alignment mark recessions is less than 20 nm. 
     
     
         16 . The method of  claim 11  wherein the highly absorptive material absorbs at least 60% of incident light from 500 to 800 nm and transmits ultraviolet (UV) radiation. 
     
     
         17 . The method of  claim 11  wherein the highly absorptive material an extinction coefficient k value greater than 3.3 at 600 nm. 
     
     
         18 . The method of  claim 11  wherein the highly absorptive material further comprises aluminum (Al), aluminum alloys including Al x Si y , Al x Si y Ti z , Al x Cu y , AlxCr y ; rhodium (Rh), chromium (Cr), iridium (Ir), niobium (Nb), titanium (Ti); nickel (Ni), palladium (Pd), platinum (Pt), silver (Ag), gold (Au), copper (Cu), or iron (Fe). 
     
     
         19 . The method of  claim 11  wherein the highly absorptive material further comprises aluminum (Al), rhodium (Rh), chromium (Cr), or niobium (Nb). 
     
     
         20 . The method of  claim 11  wherein the highly absorptive material further comprises aluminum (Al).