Double-Sided BSPDN Contacts for Lower Resistance Power Delivery
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Solution Overview
Problem
Conventional semiconductor devices face challenges in achieving low resistance in backside power distribution networks due to limited thermal budgets during silicidation, leading to high resistance and significant resistance loss in power delivery.
Innovation Solution
The implementation of double-sided contacts in the backside power distribution network (BSPDN) with frontside and backside contacts, deep bar vias, and backside power rails, utilizing conductive metals and silicides to reduce resistance and parasitic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional single-sided contact in BSPDN is used, then device structure is simple, but resistance in power distribution network is high
Solution Approach 1:
The power distribution network is segmented into multiple contact paths: frontside contacts, backside contacts, and deep bar vias connecting them. This segmentation creates parallel current paths that reduce overall resistance while distributing the electrical load across multiple interfaces with the S/D epitaxial layer
Solution Approach 2:
The invention transitions from a single-sided (2D) contact architecture to a three-dimensional contact network by adding deep bar vias that extend vertically through the substrate. This dimensional expansion creates additional contact surfaces and parallel conduction paths, reducing resistance without increasing lateral footprint
2Reliability
If thermal budget is limited during silicidation, then frontside processing is protected, but backside contact resistance increases
Solution Approach 1:
Backside contacts are formed and silicided before final frontside processing steps. This preliminary action allows the backside contacts to achieve low resistance through silicidation at earlier process stages when thermal budget is available, while subsequent frontside processing occurs at lower temperatures that protect already-formed frontside structures
Solution Approach 2:
The silicidation process is segmented into separate stages for frontside and backside contacts. Backside contacts undergo silicidation during earlier high-temperature processing steps, while frontside contacts are silicided in later steps at lower temperatures, allowing each contact type to be optimized independently for low resistance
Data Source
AI summary
Disclosed are semiconductor devices with double sided contacts—frontside and backside contacts to source/drain epitaxials. As a result, resistance can be significantly reduced. Also, deep bar vias need not reach the backside contact, which helps with process margins.