Guard Ring Layout for RF-Logic Isolation on Shared Substrates
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Solution Overview
Problem
The semiconductor industry faces challenges in integrating RF and logic transistors on the same substrate due to noise coupling, shorting, leakage, routing resistance, alignment margins, layout flexibility, and packing density, particularly as feature sizes shrink to 7 nm, 5 nm, and 3 nm, requiring a structure and method to enhance circuit performance and reliability.
Innovation Solution
A semiconductor circuit structure with field-effect transistors (FETs) that includes RF transistors and logic transistors separated by moat-like guard rings, where the guard rings encircle the RF transistors to prevent interference and improve isolation, allowing for different gate pitches and configurations optimized for each type of transistor, thereby enhancing circuit performance without degrading fabrication quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If RF transistors and logic transistors are integrated on the same substrate, then production efficiency increases and costs decrease, but noise coupling and interference occur
Solution Approach 1:
The substrate is segmented into distinct RF circuit regions and logic circuit regions, with guard rings creating physical and electrical boundaries between them. This segmentation allows both types of circuits to coexist on the same substrate while minimizing noise coupling and interference.
Solution Approach 2:
Guard rings are introduced as intermediary structures between RF transistors and logic transistors. These guard rings act as electrical buffers that isolate the two circuit types, preventing noise coupling while allowing both to function on the same substrate.
2Productivity
If feature sizes are scaled down to 7 nm, 5 nm, and 3 nm, then production efficiency increases and costs decrease, but processing complexity increases
Solution Approach 1:
Different regions of the substrate are designed with locally optimized structures - RF transistors have specific gate pitch and layout configurations while logic transistors have different configurations. This local quality approach allows each circuit type to be optimized for its function while maintaining overall integration.
Solution Approach 2:
The fabrication process uses universal steps that can produce both RF and logic transistors simultaneously, such as common gate dielectric deposition and common source/drain formation. This multi-functionality reduces processing complexity despite the different requirements of RF and logic circuits.
3Object-affected harmful factors
If guard rings are added to separate RF and logic transistors, then noise interference is reduced, but device complexity increases
Solution Approach 1:
The guard rings are merged with the active circuit regions rather than being completely separate structures. The guard rings share the same substrate and are integrated into the overall device layout, reducing the increase in device complexity while still providing noise isolation.
Data Source
AI summary
The present disclosure provides a semiconductor structure in accordance with some embodiment. The semiconductor structure includes a semiconductor substrate having a first circuit region and a second circuit region, first transistors that include first gate stacks disposed in the first circuit region, second transistors that include second gate stacks disposed in the second circuit region, and a guard ring structure disposed between the first circuit region and the second circuit region. The first gate stacks and the second gate stacks have different material compositions. The guard ring structure fully surrounds the second circuit region.