Common Rail Contact Structure for Lower IC Contact Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
As integrated circuit (IC) technologies progress towards smaller technology nodes, the reduction of contact resistance in source/drain contact vias and gate contact vias becomes increasingly challenging due to their smaller sizes, leading to increased contact resistance and reduced metal fill windows.
Innovation Solution
The implementation of a common rail contact structure that is in contact with both the gate structure and the adjacent source/drain contact, formed by merging a gate contact opening with a source/drain contact opening, which reduces contact resistance and improves metal fill windows through an asymmetric profile design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If source/drain contact vias and gate contact vias are made smaller to increase functional density, then production efficiency increases and costs decrease, but contact resistance increases and metal fill windows are reduced
Solution Approach 1:
The patent merges the gate contact opening and source/drain contact opening into a single common rail contact structure. This integration allows the common rail contact to simultaneously contact both the gate structure and source/drain contact, creating a unified low-resistance conduction path that reduces overall contact resistance while maintaining the benefits of smaller technology nodes
2Productivity
If source/drain contact vias and gate contact vias are made smaller to increase functional density, then production efficiency increases and costs decrease, but metal fill windows are reduced
Solution Approach 1:
The patent introduces an asymmetric profile design in the common rail contact structure that extends laterally beyond the gate contact opening. This dimensional extension creates an enlarged metal fill window that provides sufficient space for metal deposition and filling operations, even as the overall contact structure operates at smaller technology nodes
3Reliability
If a common rail contact structure is formed by merging gate contact opening with source/drain contact opening, then contact resistance is reduced and metal fill windows are improved, but device complexity increases
Solution Approach 1:
The patent employs an asymmetric profile design where the common rail contact has different widths at different vertical levels. The contact structure is wider at the bottom to provide a low-resistance conduction path and sufficient metal fill window, and narrower at the top to align with the gate contact opening. This asymmetric geometry simultaneously achieves reduced contact resistance and improved manufacturability without requiring complex multi-component structures
Data Source
AI summary
A method according to the present disclosure includes receiving a workpiece including a gate structure, a first source/drain (S/D) feature, a second S/D feature, a first dielectric layer over the gate structure, the first S/D feature, the second S/D feature, a first S/D contact over the first S/D feature, a second S/D contact over the second S/D feature, a first etch stop layer (ESL) over the first dielectric layer, and a second dielectric layer over the first ESL, forming a S/D contact via through the second dielectric layer and the first ESL to couple to the first S/D contact, forming a gate contact opening through the second dielectric layer, the first ESL, and the first dielectric layer to expose the gate structure, and forming a common rail opening adjoining the gate contact opening to expose the second S/D contact, and forming a common rail contact in the common rail opening.