Backside Contact Structure for Reliable BSPDN Semiconductor Connections
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Solution Overview
Problem
The increasing demand for high-performance, high-speed, and multifunctional semiconductor devices has led to challenges in enhancing the reliability of semiconductor devices with backside power delivery networks (BSPDNs).
Innovation Solution
The semiconductor device design includes a substrate layer with first and second channel layers, gate structures, a source/drain epitaxial layer, a backside contact structure, and an interlayer insulating layer. The backside contact structure is electrically connected to the source/drain epitaxial layer and has a specific width configuration that increases towards the source/drain epitaxial layer, improving reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the backside contact structure is made narrower to reduce device area, then area is reduced, but electrical connection reliability deteriorates
Solution Approach 1:
The backside contact structure transitions from a two-dimensional planar contact to a three-dimensional structure with inclined side surfaces. By extending the contact structure vertically into the substrate and creating inclined surfaces that widen toward the source/drain epitaxial layer, the patent increases the effective contact area and electrical connection reliability without increasing the device footprint area. This dimensional transition allows the contact to engage the substrate at an angle, providing both mechanical anchoring and electrical connection.
Solution Approach 2:
The backside contact structure is nested within the substrate, with the inclined side surfaces forming a tapered configuration that integrates into the substrate volume. The contact structure is positioned between the source/drain epitaxial layer and the lower surface of the substrate, creating a nested arrangement that utilizes the substrate thickness dimension to achieve improved electrical connection without occupying additional lateral space.
2Reliability
If the backside contact structure is made wider to improve electrical connection, then electrical connection reliability is improved, but device area increases
Solution Approach 1:
The patent resolves this contradiction by transitioning the contact structure into the third dimension. The inclined side surfaces create a tapered geometry where the contact width increases vertically as it extends into the substrate, rather than expanding laterally at the surface. This allows the effective contact area for electrical connection to increase while the device footprint remains compact.
3Ease of manufacture
If the contact structure uses a vertical configuration, then manufacturing is simpler, but electrical connection reliability is insufficient
Solution Approach 1:
The contact structure transitions from a static vertical configuration to a dynamic inclined configuration. The inclined side surfaces are formed through controlled etching or growth processes that create angular facets, allowing the contact to engage the substrate at an optimized angle for both electrical connection and mechanical stability. This dynamic geometric adjustment improves reliability while remaining compatible with standard semiconductor manufacturing processes.
Data Source
AI summary
A semiconductor device may include a substrate layer; a source/drain epitaxial layer between first channel layers and second channel layers; a backside contact structure electrically connected to the source/drain epitaxial layer, wherein the backside contact structure is between the source/drain epitaxial layer and a lower surface of the substrate layer, first width of the source/drain epitaxial layer at an upper surface of the substrate layer is greater than a second width at an interface between the source/drain epitaxial layer and the backside contact structure, a first portion of the backside contact structure is closer than a closest end of the source/drain epitaxial layer to the lower surface of the substrate layer, the first portion of the backside contact structure has a third width, and the third width is greater than the second width.