Radiation-Beam Mask Correction for Lithographic Pattern Accuracy
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Solution Overview
Problem
Manufacturing masks for lithographic apparatus is time-consuming and expensive, and existing methods for correcting mask flaws or distortions are inefficient and require extensive remaking, especially when dealing with dust particles and small flaws.
Innovation Solution
A lithographic apparatus equipped with a mask correction system that controllably and locally alters mask properties using a radiation beam to correct distortions and flaws, including transmissivity, birefringence, and geometry, allowing for real-time adjustments without remaking the mask.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional mask manufacturing methods are used, then mask quality can be achieved, but the process is time-consuming and expensive
Solution Approach 1:
The patent applies preliminary action by pre-characterizing the mask's optical properties (transmissivity, birefringence, geometry) before lithography use. This allows the mask correction system to have correction data ready in advance, eliminating the need for time-consuming real-time measurements during production and enabling rapid correction application.
Solution Approach 2:
The patent replaces mechanical mask remaking processes with an optical/electronic correction system. Instead of physically manufacturing new masks to correct flaws, the system uses characterized mask data combined with optical correction techniques to compensate for mask defects, significantly reducing both time and cost.
2Reliability
If existing mask correction methods are used, then some flaws can be addressed, but extensive remaking is still required
Solution Approach 1:
The patent applies parameter changes by measuring and characterizing specific optical parameters of the mask (transmissivity, birefringence, geometric dimensions) and using these characterized parameters to guide corrections. This systematic approach to parameter measurement and adjustment enables effective flaw correction without requiring complex remaking procedures.
Solution Approach 2:
The patent implements feedback by measuring the actual mask properties and using this information to adjust and correct mask patterns. The characterization data provides feedback on mask deviations, enabling targeted corrections that maintain reliability while avoiding extensive remaking.
3Manufacturing precision
If mask remaking is performed for dust particles and small flaws, then pattern accuracy can be maintained, but cost and time increase significantly
Solution Approach 1:
The patent extracts and characterizes specific mask properties (transmissivity, birefringence, geometry) separately from the overall mask manufacturing process. This extraction allows for targeted correction of specific flaws like dust particles and small defects without requiring complete mask remaking, thereby maintaining pattern accuracy while improving productivity.
Solution Approach 2:
By performing preliminary characterization of mask properties before use, the system identifies areas requiring correction in advance. This allows for efficient, targeted corrections rather than blanket remaking, maintaining pattern accuracy while significantly improving production efficiency.
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
Enables rapid and cost-effective correction of mask distortions and flaws, improving pattern accuracy and reducing the need for remaking masks, thereby enhancing the efficiency and precision of the lithographic process.
Implementation Method 1
A lithographic apparatus equipped with a mask correction system that controllably and locally alters mask properties using a radiation beam
Data Source
AI summary
A lithographic apparatus includes a mask correction system configured to controllably and locally alter a property of a mask, for example transmissivity, transmissivity to a particular polarization state, birefringence and/or geometry. The mask correction system, in an embodiment, directs a beam of radiation onto a spot of the mask, the mask being scanned relative to the mask correction system. The mask correction system may include an arrangement to irradiate multiple spots on the mask substantially simultaneously.