Transfer layer repair process for attenuated masks

Abstract

A method and apparatus for repairing transparent defects in a transfer layer circuit pattern in the process of fabricating an attenuated mask is provided comprising forming a sacrificial removable layer on the transfer layer including the part of the transfer layer having a transparent defect and then forming a patch to cover the transparent defect. After applying the sacrificial removable layer and patch, the sacrificial removable layer and unwanted exposed attenuated mask material is removed leaving the patch having an undercoating of sacrificial removable layer in the transparent defect region. The undercoat sacrificial removable layer is then at least partially etched and the patch and sacrificial layer removed by a lift off procedure. The transfer layer is then removed leaving the attenuated mask having the desired circuit pattern on the surface of the transparent mask substrate. Attenuated masks made using the method and apparatus of the invention are also provided.

1 . A method of forming defect free mask transfer layers comprising the steps of: 
 forming image segments in a mask transfer layer on a substrate;    inspecting the substrate for defects;    repairing the defects; and    removing the mask transfer layer.    
     
     
         2 . A transfer layer fabrication method for making an attenuated mask which requires a repair step to repair transparent defects in the transfer layer comprising the steps of: 
 supplying a transparent mask substrate;    depositing a layer of attenuated mask material on the mask substrate;    forming a metallic transfer layer on the attenuated mask material layer in a desired mask pattern leaving unwanted attenuated mask material exposed;    inspecting the metallic layer for transparent defects wherein metal is missing from the desired transfer layer design leaving wanted attenuated mask material exposed and forming transparent defects;    applying a sacrificial removable layer on the metallic transfer layer and wanted and unwanted attenuated mask material;    applying a patch material on top of the sacrificial removable layer in the transparent defect missing portion of the metallic transfer layer;    etching the sacrificial removable layer and unwanted exposed attenuated mask material;    contacting the etched substrate with an etchant which undercuts the patch material and at least partially etches the sacrificial removable layer under the patch material;    removing the patch material and remaining sacrificial removable layer; and    etching the metallic layer forming the attenuated mask which comprises the attenuated mask material in the form of the desired circuit pattern on the transparent mask substrate.    
     
     
         3 . The method of    claim 2    wherein the attenuated mask material is MoSi.  
     
     
         4 . The method of    claim 2    wherein the metallic transfer layer is chrome.  
     
     
         5 . The method of    claim 2    wherein the sacrificial removable layer is copper.  
     
     
         6 . A method for repairing transparent defects in a metal transfer layer in the process for making attenuated masks using a transfer layer which covers wanted attenuated mask material leaving unwanted attenuated mask material exposed wherein the attenuated mask comprises a circuit pattern of an attenuated mask material in either a negative or positive form on a transparent mask substrate which attenuated mask pattern is transferred to an electronic component substrate the method comprising the steps of: 
 inspecting the metallic layer for transparent defects wherein metal is missing from the desired transfer layer design leaving wanted attenuated mask material exposed and forming transparent defects;    applying a sacrificial removable layer on the metallic transfer layer and wanted and unwanted attenuated mask material;    applying a patch material on top of the sacrificial removable layer in the transparent defect missing portion of the metallic transfer layer;    etching the sacrificial removable layer and unwanted exposed attenuated mask material;    contacting the etched substrate with an etchant which undercuts the patch material and at least partially etches the sacrificial removable layer under the patch material;    removing the patch material and remaining sacrificial removable layer; and    etching the metallic layer forming the attenuated mask which comprises the attenuated mask material in the form of the desired circuit pattern on the transparent mask substrate.    
     
     
         7 . The method of    claim 6    wherein the attenuated mask material is MoSi.  
     
     
         8 . The method of    claim 6    wherein the metallic transfer layer is chrome.  
     
     
         9 . The method of    claim 6    wherein the sacrificial removable layer is copper.  
     
     
         10 . The method of    claim 9    wherein the etchant for undercutting the patch material is nitric acid.  
     
     
         11 . An apparatus for repairing transparent defects in a transfer layer in the process of making attenuated masks made using a transfer layer process wherein the attenuated mask has a circuit pattern of an attenuated mask material thereon which pattern is transferred to an electronic component substrate comprising: 
 holding means for securing an attenuated mask substrate having a circuit pattern thereon in the form of a transfer layer on an attenuated mask material on a transparent mask substrate, the transfer layer being in the desired mask pattern covering wanted attenuated mask material leaving unwanted attenuated mask material exposed;    detecting means for locating and identifying a transparent defect in the transfer layer exposing wanted attenuated mask material;    application means to form a sacrificial removable layer on the transfer layer and exposed wanted and unwanted attenuated mask material;    application means for applying a patch material on top of the sacrificial removable layer in the transparent defect missing portion of the transfer layer;    a first etching means to etch the sacrificial removable layer and unwanted exposed attenuated mask material;    a second etching means for etching the etched substrate to remove at least some of the sacrificial removable layer under the patch material;    removing means for removing the patch material and any remaining sacrificial removable layer under the patch material; and    a third etching means for etching the transfer layer forming the attenuated mask in the form of attenuated mask material in the desired mask pattern on the transparent mask substrate.    
     
     
         12 . The apparatus of    claim 11    wherein the application means is a focused ion beam.  
     
     
         13 . The apparatus of    claim 11    wherein the second etching means is nitric acid and the sacrificial removable layer is copper.  
     
     
         14 . An attenuated mask made using the method of    claim 1   .  
     
     
         15 . An attenuated mask made using the method of    claim 2   .  
     
     
         16 . An attenuated mask made using the method of    claim 3   .  
     
     
         17 . An attenuated mask made using the method of    claim 4   .