Stencil Mask Cell Projection Lithography Throughput
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Solution Overview
Problem
Current particle beam lithography techniques, such as electron beam direct writing with cell projection, are limited by the number of cell patterns that can be accommodated on a stencil mask, restricting throughput and practical usage to small volume production due to the need for conventional variable shape beam methods for remaining chip patterns.
Innovation Solution
The method involves designing stencils with a large number of cell patterns and using a partial projection technique to selectively expose cell patterns on a substrate, allowing multiple cell patterns to be drawn using a limited number of patterns on the stencil mask, thereby increasing throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cell projection technique is used to reduce electron beam writing time, then writing speed is improved, but the limited number of cell patterns on a single stencil mask restricts the number of cell patterns that can be drawn
Solution Approach 1:
The stencil mask is divided into multiple segments or regions, each containing different cell patterns. The system can selectively expose different segments by moving the mask or adjusting the beam path, effectively multiplying the number of available cell patterns without increasing the physical mask size.
Solution Approach 2:
The patent introduces a temporal dimension to the cell pattern selection process. By using a rotating mask wheel or movable mask stages, cell patterns are accessed in sequence over time rather than all at once, allowing hundreds of patterns to be available from a compact mask structure.
2Adaptability or versatility
If conventional variable shape beam method is used for remaining chip patterns, then all cell patterns can be drawn, but writing time increases and throughput decreases
Solution Approach 1:
The system uses cell projection for the majority of cell patterns that appear frequently in chip designs, while reserving variable shape beam capability for rare or custom patterns. This partial application of the faster cell projection method achieves high throughput for typical designs without requiring complete replacement of the VSB system.
Solution Approach 2:
The stencil mask system is designed to work in conjunction with the variable shape beam capability, creating a hybrid system that can handle both standard cell patterns efficiently and custom patterns when needed. The mask system provides universal coverage for standard libraries while the VSB capability remains available for exceptions.
3Adaptability or versatility
If stencil mask contains all possible orientations of each cell, then complete cell library coverage is achieved, but the number of patterns required exceeds mask capacity
Solution Approach 1:
The stencil mask system incorporates movable components such as rotating mask wheels or translation stages that allow dynamic selection of different mask regions. This dynamic access mechanism enables a compact mask to provide access to a large number of cell patterns by presenting different portions of the mask at different times during the writing process.
Solution Approach 2:
Cell patterns are pre-organized and pre-positioned on the stencil mask in specific orientations and arrangements. The mask design anticipates common design requirements by placing frequently used patterns in easily accessible positions, reducing the need to access all possible orientations of every cell type.
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 significantly reduces electron beam writing time and improves throughput by enabling a large number of cell patterns to be drawn using cell projection capability, overcoming the limitations of conventional methods and facilitating volume production.
Implementation Method 1
a particle or electron beam source 100 provides a particle or electron beam 102 to a first mask 112
Data Source
AI summary
A method and system for particle beam lithography, such as electron beam (EB) lithography, is disclosed. The method and system include selecting one of a plurality of cell patterns from a stencil mask and partially exposing the cell pattern to a particle beam, such as an electron beam, so as to selectively project a portion of the cell pattern on a substrate.