Lithographic Mask Repair Shapes for Small Defect Correction
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Solution Overview
Problem
The increasing complexity and cost of producing photolithographic masks due to smaller structure sizes and the difficulty in repairing small defects, which are difficult to detect and require precise metrology and time-consuming repair processes.
Innovation Solution
A method and apparatus for repairing defects in lithographic masks by ascertaining parameters for a repair shape that deviate from the predefined values, allowing for simplified correction of small defects by altering the repair process to account for diffraction effects and averaging of actinic radiation, using focused particle beams and precursor gases to create repair elements that do not perfectly replicate the defect but achieve similar imaging behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If conventional repair methods are used for small defects, then defect repair is possible, but the process becomes extremely time-consuming and complex due to the need for precise positioning and metrology
Solution Approach 1:
The patent changes the fundamental parameters of the repair approach by abandoning precise defect localization and instead using a probabilistic field-based method. The repair tool applies corrections across a broader area with controlled probability distributions, transforming the repair process from a precision targeting task to a statistical field correction task, thereby dramatically reducing time and complexity
Solution Approach 2:
The patent replaces the mechanical precision positioning system with a field-based probabilistic system. Instead of mechanically positioning the repair tool to exact defect coordinates, the system uses field-based corrections with controlled probability distributions, substituting mechanical precision requirements with statistical control methods
2Manufacturing precision
If precise metrology is used to position the repair tool, then repair accuracy is improved, but the device complexity and cost increase significantly
Solution Approach 1:
The patent replaces complex mechanical metrology and positioning systems with a field-based probabilistic approach. Instead of using precision measurement instruments to locate defects, the system employs field-based corrections with controlled probability distributions, eliminating the need for sophisticated metrology equipment while maintaining effective repair outcomes
Solution Approach 2:
The patent introduces a probabilistic field model as an intermediary between the repair tool and the defect. This intermediary layer allows corrections to be applied through controlled probability distributions across a field, mediating the interaction between the repair tool and defect without requiring direct precise positioning or complex metrology systems
3Reliability
If the repair shape parameters are set to exactly match the defect, then complete defect coverage is achieved, but the repair process becomes more complex and time-consuming
Solution Approach 1:
The patent fundamentally changes the parameters of the repair shape from exact defect matching to probabilistic field-based corrections. Instead of defining repair shapes that precisely replicate defect geometry, the system uses controlled probability distributions to apply corrections across a field, simplifying the repair process while maintaining reliability through statistical control
Solution Approach 2:
The patent applies partial corrections across a broader field rather than attempting complete precise matching of the defect. By applying controlled probability distributions over a larger area with partial corrections, the system achieves reliable defect repair without the complexity of exact defect replication, using excessive coverage with controlled intensity
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
Facilitates the repair of small defects by relaxing positional accuracy requirements and reducing the time and complexity of the repair process, maintaining image quality by altering the diffraction behavior of the mask to achieve defect-free imaging results.
Implementation Method 1
producing the at least one repair element on the lithographic mask by use of at least one focused particle beam
Implementation Method 2
using focused particle beams and precursor gases to create repair elements
Data Source
AI summary
A method for repairing at least one defect of a lithographic mask comprises the step of: ascertaining parameters of at least one repair shape for the at least one defect, wherein ascertaining parameters comprises: allocating at least one numerical value to a parameter, wherein the numerical value deviates from the numerical value predefined by the at least one defect for said parameter.