EUV Mask Absorber Deformation for Multilayer Defect Coverage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current EUV lithography mask manufacturing techniques are unable to completely neutralize multilayer defects, leading to printing errors due to residual defects, despite efforts to mitigate their influence through pattern shifting methods.
Innovation Solution
A method involving a multilayer EUV mask with a deliberately deformed absorber pattern, characterized by transformations such as translations and rotations, is used to cover multiple multilayer defects by positioning the absorber pattern in a predefined coordinate system, ensuring that all detected defects are covered by absorber material, and the deformation is compensated during the printing process to prevent defects from appearing in the printed pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pattern shifting techniques are used to mitigate ML defects, then defect coverage is improved, but complete neutralization of all defects cannot be achieved
Solution Approach 1:
The patent applies preliminary action by detecting and mapping all ML defects on the blank before pattern formation, then pre-calculating the optimal pattern deformation that will cover maximum defects. This advance planning allows the absorber pattern to be deliberately deformed to neutralize defects that would otherwise be unavoidable with simple pattern shifting.
Solution Approach 2:
The patent changes the geometric parameters of the absorber pattern through deliberate deformation transformations. By modifying the pattern's shape, position, and orientation based on calculated defect locations, the system achieves superior defect coverage compared to conventional pattern shifting. The pattern is transformed using mathematical operations to optimize defect neutralization.
2Reliability
If the absorber pattern is deliberately deformed to cover defects, then defect coverage yield is enhanced, but pattern deformation must be compensated to maintain printing accuracy
Solution Approach 1:
The patent applies preliminary anti-action by pre-calculating and storing the inverse transformation of the absorber pattern deformation. During lithography, this compensating transformation is applied to the projected pattern, effectively canceling out the deliberate deformation. This ensures that while the absorber pattern covers defects on the mask, the printed pattern on the wafer remains accurate and undistorted.
3Ease of manufacture
If simple pattern shifting is used, then the process is simple, but the success rate of defect coverage stays relatively low
Solution Approach 1:
The patent replaces simple mechanical pattern shifting with a computational approach. A computer-implemented method calculates the optimal pattern deformation based on defect locations, using mathematical transformations rather than straightforward mechanical shifts. This substitution of computational complexity for mechanical simplicity achieves superior defect coverage while maintaining process feasibility through automated calculation.
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 effectively covers all detected multilayer defects with absorber material, enhancing the defect coverage yield and reducing printing errors by modulating the scanner operations based on numerical data representing the pattern deformation, thereby improving the quality of the printed pattern on semiconductor wafers.
Implementation Method 1
The material (e.g., silicon and molybdenum) and the thickness of the layers are chosen so that EUV light reflected off the subsequent interfaces interferes constructively.
Implementation Method 2
As materials are too absorbing at the extremely small wavelengths applied in EUV lithography
Data Source
AI summary
The disclosure is related to a lithographic mask for EUV lithography, to a method for producing the mask, to a method for printing a pattern with the mask, to a stepper/scanner configured to print a pattern with the mask as well as to a computer-implemented method for calculating a deformation of the pattern. The mask comprises an absorber pattern, which is intentionally deformed in the 2-dimensional plane of the EUV mask, with respect to the intended pattern. The deformation of the pattern is based on a previous measurement of the location of multilayer defects on the blank, and calculated so that in the deformed pattern, a maximum of multilayer defects are covered by absorber material. When the pattern is subsequently printed on a semiconductor wafer in a stepper/scanner, the scanner operation is modulated so that the pattern deformation is not reproduced on the wafer.