Photomask Wing Design for Double Patterning Edge Protection
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Solution Overview
Problem
Conventional photolithography processes face challenges in achieving precise critical dimension control, particularly with the increasing densities of integrated circuit devices, due to potential misalignment issues in multi-pattern processing that can lead to patterning errors affecting circuit function.
Innovation Solution
A method employing multiple photomasks where one photomask is chosen to pattern an edge, and another with wings is used to protect it from double patterning, preventing misalignment errors by forming wings adjacent to the edge to prevent double patterning, thereby ensuring accurate edge definition and improved critical dimension control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple photomasks are used for patterning, then critical dimension control is improved, but misalignment errors between masks can cause patterning defects
Solution Approach 1:
The patent applies preliminary action by forming wings on the photomask patterns before the actual patterning process. These wings are created during mask fabrication to preemptively prevent misalignment errors. The wings extend beyond the intended pattern boundaries and act as a buffer zone that compensates for potential alignment deviations during multi-mask processing, thereby ensuring accurate critical dimensions without requiring perfect mask alignment.
Solution Approach 2:
The patent implements beforehand cushioning by incorporating protective wings that extend beyond the critical pattern edges. These wings serve as a cushion or buffer against misalignment errors. When masks are applied in sequence, the wings absorb or compensate for alignment deviations, preventing them from affecting the actual critical dimensions of the patterned features. This cushioning effect ensures reliable patterning even when minor misalignments occur between masks.
2Device complexity
If photomask patterns are formed without protective features, then manufacturing complexity is reduced, but double patterning errors occur affecting circuit function
Solution Approach 1:
The patent applies preliminary action by incorporating protective wings into the photomask design during the mask fabrication stage. These wings are formed as part of the mask pattern before the actual device patterning process begins. The wings are strategically positioned to overlap with critical features and provide preemptive protection against double patterning errors, ensuring circuit functionality without adding complex processing steps during device manufacturing.
3Reliability
If wings are added to photomask patterns, then edge protection from double patterning is improved, but mask pattern complexity increases
Solution Approach 1:
The patent applies local quality by adding protective wings only at specific locations where they are most needed - namely at the edges and boundaries of critical patterns. The wings are not uniformly applied across the entire mask but are strategically positioned at locations prone to double patterning errors. This localized approach provides edge protection where required while minimizing the overall increase in mask pattern complexity and maintaining manufacturing efficiency.
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 reduces patterning errors and enhances critical dimension control by avoiding misalignment issues, ensuring the desired dimensions and functionality of integrated circuit devices, particularly for features like gate lengths, which are critical for circuit performance.
Implementation Method 1
A stepper includes a light source and optics that project light coming through the photomask to image the circuit pattern on a photo-resist film formed on a wafer
Data Source
AI summary
The present disclosure is directed to a method for preparing photomask patterns for a lithography process that employs a plurality of photomasks. The method comprises receiving data describing a drawn pattern. An edge of the drawn pattern is identified that can be defined using a first photomask and a second photomask, and the first photomask is chosen for patterning the edge. Patterns are formed for the first photomask and the second photomask, wherein the first photomask pattern is formed to pattern the edge, and the second photomask pattern is formed to have a wing adjacent to the edge for protecting the edge from double patterning. A process for patterning an integrated circuit device is also disclosed.