Photolithographic Mask Error Correction via Local Persistent Modifications
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Solution Overview
Problem
The increasing complexity and cost of manufacturing photolithographic masks with shrinking feature sizes, particularly in the extreme ultraviolet (EUV) wavelength range, are exacerbated by positioning errors and overlay inaccuracies, which are time-consuming and expensive to correct, especially when using double patterning lithography processes.
Innovation Solution
A method and apparatus for measuring and correcting errors on wafers illuminated by photolithographic masks using femtosecond or ultra-short light pulses to introduce local persistent modifications in the mask substrate, allowing for direct alignment of pattern elements and minimizing overlay errors without the need for extensive mask rewriting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If photolithographic masks are used with shrinking feature sizes in EUV wavelength range, then resolution is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent applies preliminary action by measuring and correcting positioning errors on the mask before the actual photolithography process. The method measures overlay errors using test structures, calculates correction values, and writes correction data to the mask in advance, thereby preventing errors from affecting production wafers and reducing the need for costly mask re-manufacturing.
Solution Approach 2:
The patent implements feedback by measuring overlay errors on test wafers, calculating correction values based on measured deviations, and applying these corrections to subsequent mask exposures. This closed-loop feedback system continuously optimizes mask alignment accuracy without requiring manual intervention or mask re-manufacturing.
2Measurement precision
If photolithographic masks are used with shrinking feature sizes in EUV wavelength range, then resolution is improved, but manufacturing cost increases
Solution Approach 1:
The patent applies preliminary action by measuring and correcting positioning errors on the mask before the actual photolithography process. The method measures overlay errors using test structures, calculates correction values, and writes correction data to the mask in advance, thereby preventing errors from affecting production wafers and reducing the need for costly mask re-manufacturing.
Solution Approach 2:
The patent implements feedback by measuring overlay errors on test wafers, calculating correction values based on measured deviations, and applying these corrections to subsequent mask exposures. This closed-loop feedback system continuously optimizes mask alignment accuracy without requiring manual intervention or mask re-manufacturing.
3Manufacturing precision
If mask rewriting is performed to correct positioning errors, then alignment accuracy is improved, but processing time increases
Solution Approach 1:
The patent applies preliminary action by measuring and correcting positioning errors on the mask before the actual photolithography process. The method measures overlay errors using test structures, calculates correction values, and writes correction data to the mask in advance, thereby preventing errors from affecting production wafers and reducing the need for costly mask re-manufacturing.
Solution Approach 2:
The patent implements feedback by measuring overlay errors on test wafers, calculating correction values based on measured deviations, and applying these corrections to subsequent mask exposures. This closed-loop feedback system continuously optimizes mask alignment accuracy without requiring manual intervention or mask re-manufacturing.
4Manufacturing precision
If repeated mask writing is performed to correct errors, then positioning accuracy is improved, but time consumption increases
Solution Approach 1:
The patent applies preliminary action by measuring and correcting positioning errors on the mask before the actual photolithography process. The method measures overlay errors using test structures, calculates correction values, and writes correction data to the mask in advance, thereby preventing errors from affecting production wafers and reducing the need for costly mask re-manufacturing.
Solution Approach 2:
The patent implements feedback by measuring overlay errors on test wafers, calculating correction values based on measured deviations, and applying these corrections to subsequent mask exposures. This closed-loop feedback system continuously optimizes mask alignment accuracy without requiring manual intervention or mask re-manufacturing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces alignment errors between masks, minimizes overlay errors, and allows for the correction of local CD and overlay errors, thereby enhancing the efficiency and reducing the cost of photolithographic processes, particularly in double patterning lithography, by enabling precise pattern placement and optical transmission adjustments.
Implementation Method 1
uses femtosecond or ultra-short light pulses of a laser system to locally change the density of the substrate of a photo-lithographic mask which results in a shift of the pattern placement on the substrate surface
Data Source
AI summary
The invention relates to a method for correcting at least one error on wafers processed by at least one photolithographic mask, the method comprises: (a) measuring the at least one error on a wafer at a wafer processing site, and (b) modifying the at least one photolithographic mask by introducing at least one arrangement of local persistent modifications in the at least one photolithographic mask.