Chromeless Phase Shifting Mask for IC Feature Printing
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Solution Overview
Problem
Conventional photolithographic masks struggle to print smallest features due to difficulties in creating phase shifter masks for small components and other exposure techniques for larger features, leading to misalignment issues and circuit malfunctions.
Innovation Solution
A system and method for creating mask pattern data that uses annular rim phase shifters and filling phase shifting regions to print both small and larger features, allowing for easier manufacturing and reducing the need for multiple mask creation processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional chrome-on-glass photolithographic masks are used, then manufacturing process is simple, but smallest features cannot be printed with required precision
Solution Approach 1:
The patent applies phase transition by using phase shifters that introduce a 180-degree phase shift in the light wavefront. This phase transition enables destructive interference to print sub-resolution features that cannot be printed with conventional chrome masks, directly resolving the contradiction between feature size and printing precision.
Solution Approach 2:
The patent segments the mask into different functional regions: phase-shifting regions for small features, non-phase-shifting regions for larger features, and assist feature regions. This segmentation allows each region to be optimized for its specific function, enabling both small and large features to be printed with appropriate techniques.
2Manufacturing precision
If phase shifter masks are used for small features, then smallest features can be printed, but alignment with larger features becomes difficult
Solution Approach 1:
The patent creates a universal mask structure that handles both small and large features within a single mask. The mask simultaneously contains phase-shifting regions for small features and non-phase-shifting regions for larger features, eliminating the need for separate masks and thereby ensuring reliable alignment between features of different sizes.
Solution Approach 2:
The patent introduces assist features as intermediary elements that facilitate alignment between phase-shifting and non-phase-shifting regions. These assist features act as mediators that help establish precise registration between different feature types on the same mask.
3Adaptability or versatility
If multiple mask creation processes are used for different feature sizes, then both small and large features can be addressed, but manufacturing complexity and misalignment risk increase
Solution Approach 1:
The patent implements a single universal mask design that accommodates both small and large features through integrated phase-shifting and non-phase-shifting regions. This eliminates the need for multiple separate mask creation processes, thereby reducing manufacturing complexity while maintaining versatility across different feature sizes.
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 enables the creation of masks that can print both small and larger features on a wafer with improved alignment and reduced risk of misalignment errors, enhancing the manufacturing efficiency and electrical functionality of integrated circuits.
Implementation Method 1
A phase shifter operates to shift the phase of the illumination light by some amount, typically 180 degrees, with respect to light that passes through an adjacent, non-phase shifting area of the mask
Implementation Method 2
The phase shifted and non-phase shifted light destructively interfere on the surface of the wafer to create desired patterns on the wafer
Data Source
AI summary
A system for creating mask layout pattern data in order to create a number of desired features on a semiconductor wafer. Critical features and features that are adjacent to or abut critical features are formed as phase shifting regions on a mask. Larger, non-critical features can be formed as annular rim shifters and may include one or more filling phase shifting regions. Non-critical features that are not adjacent to critical features and/or sub-resolution features that are not desired to print on the wafer can be formed as opaque or partially transparent regions on the mask.