Wrapped Epi Contacts and Dielectric Bars for Lower S/D Resistance
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Solution Overview
Problem
Conventional stacked transistors and FETs face challenges in scaling due to the contacts needed to connect source/drain with backside or frontside contacts, leading to issues with unwanted current and heat transfer, and increased S/D resistance.
Innovation Solution
The use of dielectric bars and wrapped contacts in semiconductor structures, where the wrapped contacts have direct contact with three or more sides of the epitaxy, helps to reduce physical distance between components, prevent current and heat transfer, and improve current access through the epitaxy despite S/D resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional stacked transistors use traditional contact structures to connect source/drain, then device connectivity is achieved, but S/D resistance increases and physical distance between components increases
Solution Approach 1:
The wrapped contact structure implements nesting by having the contact material wrap around and enclose portions of the epitaxy from multiple directions (front, back, and sidewalls). This nested configuration allows the contact to penetrate deeper into the epitaxy and establish multiple contact points, thereby reducing S/D resistance without requiring increased physical distance between components.
Solution Approach 2:
The invention transitions from conventional planar contact structures to a three-dimensional wrapped contact architecture. By extending the contact in multiple dimensions (wrapping around the epitaxy from front, back, and sidewalls), the contact area and contact points are significantly increased, reducing S/D resistance without increasing the footprint or physical distance between components.
2Object-generated harmful factors
If dielectric bars are introduced to separate components, then current and heat transfer between components is prevented, but device density decreases
Solution Approach 1:
The dielectric bar is strategically positioned only in specific locations where unwanted current and heat transfer between components is most problematic. Rather than using dielectric material throughout the entire device structure, the invention applies dielectric separation locally at critical interfaces, thereby preventing harmful transfers while maintaining high device density in other regions.
3Reliability
If wrapped contacts with direct contact to three or more sides of epi are used, then current access through epitaxy is improved, but manufacturing complexity increases
Solution Approach 1:
The wrapped contact structure is formed using preliminary patterning and deposition steps that prepare the epitaxy and contact material in advance. The contact material is deposited and shaped to wrap around the epitaxy before final device assembly, making the complex three-dimensional contact structure achievable through sequential manufacturing steps rather than requiring complex post-assembly operations.
Data Source
AI summary
A semiconductor structure, a system, and a method of forming a transistor with a dielectric bar and a wrapped contact. The semiconductor structure may include a first transistor. The first transistor may include an epi. The first transistor may also include a dielectric bar. The first transistor may also include a wrapped contact, where the wrapped contact has direct contact with three or more sides of the epi. The system may include a semiconductor structure. The method may include forming a set of stacked nanosheets. The method may also include forming a dielectric bar. The method may also include growing an epi. The method may also include performing an epi cut to remove portions of the epi. The method may also include depositing metal contact around the two or more sides of the epi. The method may also include depositing dielectric to separate portions of the metal contact.