Backside Source/Drain Contact Layout for Low-Capacitance IC Wiring
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Solution Overview
Problem
The challenge in developing integrated circuit (IC) devices is to create a structure that minimizes parasitic capacitance and allows for efficient power and signal wiring within a reduced area, while maintaining high operating speed and accuracy, which is difficult due to the downscaled nature of these devices.
Innovation Solution
The IC device incorporates an insulating structure with a backside contact structure that includes a first contact portion with a widening width towards the source/drain region and a second contact portion with a decreasing width, ensuring sufficient insulation distance and reducing parasitic capacitance, allowing for easy alignment and formation of stable and optimized wiring configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the area of IC device is reduced for downsaling, then integration density is improved, but parasitic capacitance increases and wiring stability deteriorates
Solution Approach 1:
The backside contact structure extends in the vertical direction through the insulating structure, utilizing the third dimension to provide contact paths without increasing horizontal area. This dimensional transition allows wiring to be established without occupying additional planar space, thereby maintaining reduced device area while ensuring stable electrical connections through sufficient insulation distances in the vertical arrangement.
Solution Approach 2:
The insulating structure serves as an intermediary between the backside contact structure and other components, providing electrical isolation. This mediator ensures sufficient insulation distance between the contact structure and surrounding wiring, preventing parasitic capacitance formation while allowing the compact horizontal layout required for downscaled devices.
2Object-affected harmful factors
If insulation distance between wiring structures is increased to reduce parasitic capacitance, then parasitic capacitance is reduced, but device area increases
Solution Approach 1:
The backside contact structure utilizes the vertical dimension to achieve sufficient insulation distances without expanding horizontal area. By extending through the insulating structure in the vertical direction, the contact structure maintains adequate spacing from other wiring elements, reducing parasitic capacitance while preserving the compact footprint required for downscaled devices.
3Ease of manufacture
If backside contact structure has uniform width, then manufacturing is simplified, but alignment with source/drain region is difficult
Solution Approach 1:
The backside contact structure features variable width along its extension direction, with a first width at the first end and a second width at the second end. This local variation in dimensional quality enables precise alignment with the source/drain region at one end while maintaining manufacturability through controlled gradual transitions, resolving the conflict between manufacturing simplicity and alignment precision.
Solution Approach 2:
The backside contact structure employs asymmetric width distribution, being wider at one end and narrower at the other. This asymmetric geometry facilitates precise alignment with the source/drain region at the wider end, where greater dimensional tolerance accommodates alignment variations, while the narrower portion optimizes space utilization and reduces parasitic effects.
Data Source
AI summary
An integrated circuit device includes an insulating structure, a source/drain region on the insulating structure, a pair of bottom semiconductor sheets being spaced apart from each other with the source/drain region therebetween in a first horizontal direction, a pair of channel regions spaced apart from the insulating structure with the bottom semiconductor sheets therebetween, a pair of gate lines respectively extending on the pair of channel regions on the bottom semiconductor sheets and extending longitudinally in a second horizontal direction perpendicular to the first horizontal direction, and a backside contact structure extending through the insulating structure to contact a bottom surface of the source/drain region, the backside contact structure including a first contact portion that has a width in the first horizontal direction increasing toward the source/drain region and a second contact portion that has a width in the first horizontal direction decreasing toward the source/drain region.