Method for writing a pattern on a surface intended for use in exposure equipment and for measuring the physical properties of the surface

Abstract

The present invention relates to a method for writing a pattern on a surface intended for use in exposure equipment, including the steps of: arranging an object having a thickness (T) provided with a surface on a stage of a pattern generating apparatus, dividing the surface into a number of measurement points, where two adjacent measurement points being spaced a distance (P) apart not exceeding a predetermined maximum distance, determining the gradient of the surface at each measurement point, calculating a 2-dimensional local offset (d) in the x-y plane for each measurement point as a function of the gradient, and the thickness (T) of object, and correcting the pattern to be written on said surface by using the 2-dimensional local offset (d). The invention also relates to a method for measuring the physical properties of a surface.

1 . A method for writing a pattern on a surface intended for use in exposure equipment, comprising the steps of: 
 arranging an object having a thickness (T) provided with a surface on a stage of a pattern generating apparatus,    dividing the surface into a number of measurement points, where two adjacent measurement points being spaced a distance (P) apart not exceeding a predetermined maximum distance,    determining the gradient of the surface at each measurement point,    calculating a 2-dimensional local offset (d) in the x-y plane for each measurement point as a function of the gradient, and the thickness (T) of object, and    correcting the pattern to be written on said surface by using the 2-dimensional local offset (d).    
   
   
       2 . The method according to  claim 1 , wherein the step of correcting the pattern comprises the steps: 
 determining a correction function for the surface using the calculated 2-dimensional local offset (d) for each measurement point, and    writing the pattern on the surface using the correction function with the pattern generating apparatus.    
   
   
       3 . The method according to  claim 1 , wherein the step of determining the gradient comprises measuring the variation in height of the surface at each measurement point.  
   
   
       4 . The method according to  claim 3 , wherein the step of measuring the variations in height of the surface comprises the steps of: 
 determining a reference surface, 
 measuring the height (H) between the reference surface and the surface of the object at each measurement point,  
 whereby the 2-dimensional local offset (d) in the x-y plane may be calculated as a function of the measured height (H), the distance (P) from each at least one adjacent measurement point, and the thickness (T) of the object.  
   
   
   
       5 . The method according to  claim 4 , wherein the local offset (d) is calculated using the formula:  
         d =( T*H )/(2* P )  
   
   
       6 . The method according to  claim 3 , wherein the measurement points are arranged in a grid structure having a first predetermined pitch in the x direction and a second predetermined pitch in the y direction.  
   
   
       7 . The method according to  claim 4 , wherein the height (H) between the reference surface and the surface of the object originate from unevenness of the stage, and/or unevenness of one or both surfaces of the object and/or undesired objects arranged between the stage and the object.  
   
   
       8 . The method according to  claim 7 , wherein the undesired objects may be trapped air or particles.  
   
   
       9 . The method according to  claim 1 , wherein the top surface of the object is selected to carry the pattern.  
   
   
       10 . The method according to  claim 1 , wherein the correction function also compensates for expected deformation from the exposure equipment during subsequent processing steps.  
   
   
       11 . A method for measuring the physical properties of a surface, including the steps of: 
 arranging an object having a thickness (T) provided with a surface on a stage of a measuring apparatus,    dividing the glass plate into a number of measurement point, where two adjacent measurement points being spaced a distance apart not exceeding a predetermined maximum distance,    determining the gradient of the surface at each measurement point,    calculating a 2-dimensional local offset (d) in the x-y plane for each measurement point as a function of the gradient, and the thickness (T) of object, and    determining a correction function for the surface using the calculated 2-dimensional local offset (d) for each measurement point.    
   
   
       12 . The method according to  claim 11 , wherein the step of determining the gradient comprises measuring the variation in height of the surface at each measurement point.  
   
   
       13 . The method according to  claim 12 , wherein the step of measuring the variations in height of the surface comprises the steps of: 
 determining a reference surface, 
 measuring the height (H) between the reference surface and the surface of the object at each measurement point,  
 whereby the 2-dimensional local offset (d) in the x-y plane may be calculated as a function of the measured height (H), the distance (P) from each at least one adjacent measurement point, and the thickness (T) of the object.  
   
   
   
       14 . The method according to  claim 11 , wherein the object is a reference object, and said surface is provided with marks at each measurement point.  
   
   
       15 . A computer program for performing the following steps: 
 determining the gradient of the surface at each measurement point being defined on a surface of an object having a thickness (T),    calculating a 2-dimensional, local offset; (d) in the x-y plane for each measurement point as a function of the gradient, and the thickness (T) of object, and determining a correction function for the surface, or correcting a pattern to be written on said surface, using the calculated 2-dimensional local offset (d) for each measurement point.    
   
   
       16 . A computer program product for carrying the computer program as defined in  claim 15.