Split Via Gate Contact With Inverse Taper for Alignment Margin
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Solution Overview
Problem
Legacy contact formation techniques in integrated circuit manufacturing result in high rates of via short and open failures due to low process margin, especially when increasing transistor density, leading to alignment issues and increased risk of contact shorts and opens.
Innovation Solution
The implementation of a via gate contact (VCG) with two separate sections, where the bottom portion is oversized and self-aligned to a trench connector, and the top portion has an inverse taper to electrically couple with the metallization layer, allowing for improved alignment and increased contact area with the gate, thereby enhancing transistor density and manufacturing margin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If legacy contact formation techniques are used, then manufacturing simplicity is maintained, but alignment precision and contact reliability deteriorate due to low process margin
Solution Approach 1:
The via gate contact is divided into two separate sections: a bottom portion that is oversized and self-aligned to the trench connector, and a top portion with inverse taper that couples with the metallization layer. This segmentation allows each section to be optimized independently for its specific function, improving alignment precision without requiring complete restructuring of the contact formation process.
Solution Approach 2:
Different geometric characteristics are applied to different parts of the contact structure. The bottom portion has an oversized cross-section for self-alignment and mechanical stability, while the top portion has an inverse taper for precise electrical coupling with the metallization layer. This local differentiation of geometric properties optimizes both alignment precision and contact reliability.
2Productivity
If transistor density is increased, then productivity is improved, but contact reliability deteriorates due to increased risk of via shorts and opens
Solution Approach 1:
The bottom portion of the via gate contact is designed with an oversized cross-section that provides a larger margin for alignment errors. This pre-built cushioning compensates for potential misalignment issues that arise when transistor density is increased, thereby maintaining contact reliability despite higher productivity demands.
Solution Approach 2:
The contact structure transitions from a uniform cylindrical via to a two-section structure with different geometric parameters. The bottom section has a larger radius for alignment tolerance, while the top section has an inverse taper profile for precise electrical coupling. This parameter differentiation maintains reliability as transistor density increases.
3Productivity
If via dimensions are reduced for higher density, then transistor density is improved, but manufacturing precision deteriorates due to alignment difficulties
Solution Approach 1:
The solution moves from considering only the vertical dimension of via alignment to utilizing the horizontal dimension as well. The oversized bottom portion provides horizontal alignment tolerance, while the inverse taper top portion ensures precise vertical coupling with the metallization layer. This dimensional approach allows reduced via dimensions for higher density while maintaining manufacturing precision.
Data Source
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AI summary
Embodiments described herein may be related to apparatuses, processes, and techniques related to construct via gate contact (VCG) between a metal gate of a gate structure and a metallization layer, where the VCG is split into two separate portions. The bottom portion may be oversized with respect to the metal gate and self-aligned to a trench connector in a same layer as the bottom portion of the VCG. The top portion may be an inverse taper that may be used to electrically couple the bottom portion of the VCG with the metallization layer to reduce the effects of edge placement error. Other embodiments may be described and/or claimed.