Digital Phase Mask Resolves Phase Conflicts in Lithography
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Binary phase masks fail to adequately transfer patterns at pattern portions with both binary phase values, leading to device failure and poor manufacturing yield, and using multiple masks introduces process delays and increased costs.
Innovation Solution
A digital phase mask with independently assignable phase pixels, coupled with a pattern generator and an optical system, exposes a sensitized substrate to multiple phase patterns, including a bridging pattern to resolve phase conflicts, using a pulsed laser with varying pulse energies and scanning to optimize pattern transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If binary phase masks are used for pattern transfer, then the manufacturing process is simple, but phase conflicts occur at pattern portions requiring both binary phase values, leading to device failure and poor yield
Solution Approach 1:
The patent employs a dynamic, reconfigurable digital phase mask where individual phase pixels can be independently programmed to different phase values (0, π/2, π, 3π/2) based on the specific pattern requirements. This dynamic adaptability allows the mask to resolve phase conflicts by assigning appropriate phase values to different regions, eliminating the phase conflicts that plague static binary masks while maintaining manufacturing simplicity through software control rather than hardware complexity.
Solution Approach 2:
The digital phase mask implements local quality by allowing different phase values to be assigned to different spatial locations (phase pixels) across the mask. Each phase pixel can be independently configured to provide the optimal phase shift for its local region, enabling precise control over the optical field at each pattern portion. This local customization resolves phase conflicts by ensuring that regions requiring different phase values receive the appropriate local phase treatment.
2Manufacturing precision
If multiple masks are used to resolve phase conflicts, then pattern transfer fidelity improves, but process delays increase due to mask changes and costs increase due to mask generation
Solution Approach 1:
The digital phase mask achieves universality by consolidating the functionality of multiple static masks into a single reconfigurable device. The same physical mask can be programmed to generate different phase patterns for different pattern types by simply changing the phase values assigned to its pixels through software control. This eliminates the need for physical mask changes, resolving phase conflicts while maintaining manufacturing precision and eliminating the time losses and costs associated with multiple mask fabrication and changeover operations.
Solution Approach 2:
The patent resolves the contradiction by changing the controllable parameters of the mask from fixed physical structures to software-programmable phase values. By varying the phase parameter (0, π/2, π, 3π/2) assigned to each pixel through digital control, the system can adapt to different patterning requirements without physical mask changes. This parameter-based flexibility maintains high manufacturing precision while eliminating process delays and reduction costs.
3Manufacturing precision
If multiple phase patterns are exposed sequentially, then phase conflicts are resolved and pattern fidelity improves, but exposure time increases
Solution Approach 1:
The patent employs periodic pulsed laser exposure to transfer the phase pattern to the substrate. By using a series of periodic laser pulses rather than continuous illumination, the system achieves precise energy delivery while maintaining short total exposure times. The periodic nature of the pulsed exposure allows for efficient energy transfer and reduces the overall exposure duration while still achieving the required pattern fidelity through cumulative exposure effects.
Solution Approach 2:
The digital phase mask performs preliminary action by pre-calculating and pre-programming the optimal phase values for each pixel based on the target pattern requirements before exposure begins. This preliminary configuration of the phase mask allows the exposure process to proceed efficiently with minimal adjustments, reducing the total exposure time needed to achieve high pattern fidelity compared to iterative or adaptive approaches.
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
The solution effectively transfers patterns by compensating phase conflicts, improving manufacturing yield and reducing costs by eliminating the need for multiple mask changes, while maintaining pattern fidelity and efficiency.
Implementation Method 1
An optical system is situated to expose a sensitized substrate to the first and second phase pattern portions defined on the digital phase mask
Data Source
AI summary
Phase conflicts in pattern transfer with phase masks can be resolve by exposing pattern features with a first pattern and a second pattern, wherein the second pattern is selected based on the phase conflicts. In scanned exposures using pulsed lasers, a number of exposures of the second pattern can be less than 20% of a total number of exposures.