Mask Set Inwardly Displaced Segments Mitigate Alignment Mismatches
Solution Overview
Problem
Conventional semiconductor device fabrication methods face challenges in achieving superior performance and reliability, particularly in fabricating CMOS devices with metal gates, n-type and p-type work function metal layers, and high-K gate dielectric layers, due to issues like boron penetration and depletion effects.
Innovation Solution
A mask set and method for fabricating semiconductor devices that include a first mask with geometric patterns and a second mask with a strip-shaped pattern featuring inwardly displaced segments, allowing for the formation of a serpentine pattern on the substrate, which provides a buffer to mitigate alignment mismatches and ensure complete removal of work function metal layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional photomask patterns are used for fabricating metal gate CMOS devices, then the fabrication process is simple, but alignment mismatches cause incomplete removal of work function metal layers, reducing device reliability
Solution Approach 1:
The patent applies preliminary action by designing the photomask with inwardly displaced segments that overlap geometric patterns before the actual fabrication process. This pre-positioned overlap creates a buffer region that compensates for potential alignment mismatches during subsequent manufacturing steps, ensuring complete removal of work function metal layers even when alignment varies within acceptable tolerances.
Solution Approach 2:
The patent implements beforehand cushioning by creating a buffer region through the overlapping segments in the photomask design. This buffer region acts as a cushion that absorbs alignment variations, preventing them from causing incomplete removal of metal layers. The inwardly displaced segments provide a margin of error that protects against alignment mismatches, thereby maintaining device reliability.
2Productivity
If the serpentine pattern is positioned close to gate structure ends, then manufacturing efficiency is high, but alignment mismatches cause incomplete removal of work function metal layers
Solution Approach 1:
The patent applies preliminary action by pre-positioning the inwardly displaced segments to overlap with geometric patterns, creating a buffer region before fabrication begins. This ensures that even when the serpentine pattern is positioned efficiently close to gate structure ends, the overlapping buffer compensates for alignment variations, maintaining complete removal of work function metal layers.
Solution Approach 2:
The patent implements beforehand cushioning by designing overlapping segments that create a buffer region in advance. This buffer region provides a safety margin that protects against alignment mismatches, allowing the serpentine pattern to be positioned close to gate structure ends for high manufacturing efficiency while still ensuring complete metal layer removal and device reliability.
3Ease of manufacture
If conventional masks without overlapping segments are used, then mask design is simple, but alignment mismatches reduce fabrication precision
Solution Approach 1:
The patent applies preliminary action by incorporating inwardly displaced segments that overlap geometric patterns in the photomask design. While this adds some complexity to mask design, it pre-establishes a buffer region that compensates for alignment mismatches, significantly improving manufacturing precision without requiring complex additional processing steps.
Data Source
AI summary
A mask set includes a first mask and a second mask. The first mask includes geometric patterns. The second mask includes at least a strip-shaped pattern with a first edge and a second edge opposite to the first edge. The strip-shaped pattern has a centerline along a long axis of the strip-shaped pattern. The first edge includes inwardly displaced segments shifting towards the centerline and each of the inwardly displaced segments overlaps each of the geometric patterns.