Source/Drain Contact Grain Structure for Low-Defect Nanosheet Devices
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Solution Overview
Problem
Existing semiconductor devices face challenges with defects and resistance in the source/drain contact, which affect the performance and scalability of integrated circuit devices.
Innovation Solution
The semiconductor device incorporates a multi-grain structure for the source/drain contact, including a multi-grain first filling layer and a single-grain second filling layer, along with a multi-grain bottom via, to enhance electrical connectivity and reduce defects and resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional source/drain contact structure is used, then the device structure is simple, but defects and resistance in the source/drain contact increase
Solution Approach 1:
The source/drain contact is divided into multiple distinct layers: a first filling layer with multi-grain structure and a second filling layer with single-grain structure. Each layer serves specific functional purposes, with the first layer providing defect tolerance and the second layer providing low resistance, thereby resolving the contradiction between reliability and structural simplicity.
Solution Approach 2:
Different regions of the contact structure are assigned different grain structures tailored to their specific functional requirements. The first filling layer uses multi-grain structure where defects can be tolerated, while the second filling layer uses single-grain structure where low resistance is critical. This local differentiation optimizes overall contact performance without requiring complete structural redesign.
2Productivity
If the source/drain contact is scaled down, then device density increases, but defects and resistance in the contact become more significant
Solution Approach 1:
The contact structure is segmented into functional layers that address different reliability concerns. The first filling layer's multi-grain structure provides defect tolerance for scaled dimensions, while the second filling layer's single-grain structure ensures low resistance despite reduced size, enabling continued scaling without sacrificing contact quality.
Solution Approach 2:
The contact structure employs a composite approach with two distinct filling layers having different grain structures. This composite design allows the contact to simultaneously achieve the defect tolerance needed for scaling and the low resistance required for performance, resolving the contradiction between device density and contact reliability.
Data Source
AI summary
A semiconductor device may include an insulating pattern on a first lower interlayer insulating layer, nanosheets vertically stacked on the insulating pattern, a gate electrode on the insulating pattern and surrounding the nanosheets, a source/drain region on one side of the gate electrode on the insulating pattern, and a source/drain contact electrically connected to the source/drain region. The source/drain region, the first lower interlayer insulating layer, and the insulating pattern may define a contact trench and the source/drain contact may fill the contact trench. The source/drain contact may include a barrier layer, a first filling layer between parts of the barrier layer in the contact trench, and a second filling layer in the contact trench under the first filling layer. The first filling layer may be multi grain and may have a first average grain size. The second filling layer may be single grain.