3D Backside Contact Structure for Low-Resistance Source/Drain Contacts
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Solution Overview
Problem
The nano-scale dimension of field-effect transistors leads to increased ohmic contact resistance between the source/drain region and the backside contact structure due to the small size of the backside contact area.
Innovation Solution
An enlarged backside contact structure is implemented, which includes a backside contact structure connected to the bottom surface of the source/drain region, a side via structure connected to the side surface, and a front contact structure connected to the top surface, thereby increasing the contact area and reducing ohmic contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional backside contact structure is used, then the device density and integration are improved, but the ohmic contact resistance increases due to reduced contact area
Solution Approach 1:
The contact structure transitions from a conventional single-plane contact to a multi-dimensional contact system involving bottom surface contact, side surface contact via via structures, and top surface contact. This three-dimensional contact architecture increases the effective contact area without increasing the planar footprint, thereby reducing ohmic contact resistance while maintaining high device density.
Solution Approach 2:
The contact structure employs nested via structures where first side vias are formed within second side vias, and further nested within third side vias. This nested configuration allows multiple contact paths to be stacked vertically, increasing the effective contact area and providing redundant current paths while maintaining a compact footprint suitable for high-density integration.
2Reliability
If the backside contact area is increased to reduce ohmic contact resistance, then the contact resistance decreases, but the device density and integration are compromised
Solution Approach 1:
The invention resolves this contradiction by extending the contact structure into the vertical dimension through multi-level via structures and side surface contacts. This allows the effective contact area to be increased without increasing the planar footprint, thereby maintaining high device density while reducing ohmic contact resistance.
Solution Approach 2:
The contact structure is segmented into multiple independent contact components including bottom surface contacts, side surface contacts through first/second/third side vias, and top surface contacts. This segmentation allows the total contact area to be distributed across multiple discrete contact points, increasing the effective contact area while maintaining a compact overall footprint for high-density integration.
Data Source
AI summary
Provided is a semiconductor device including: a channel structure; a 1st source/drain region on the channel structure; and an enlarged backside contact structure connected to the 1st source/drain region, wherein the enlarged backside contact structure includes a backside contact structure below the 1st source/drain region, a 1st side via structure at a 1st side of the 1st source/drain region, and a 1st front contact structure above the 1st source/drain region, and wherein the backside contact structure is connected to the 1st side via structure, which is connected to the front contact structure.