Semiconductor Contact Structure With Concave Interface for Lower Resistance
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Solution Overview
Problem
The increasing complexity of semiconductor manufacturing processes due to the scaling down of semiconductor devices, such as MOSFETs and finFETs, has made it challenging to reduce contact resistance between contact structures and interconnects without increasing critical dimensions.
Innovation Solution
The implementation of concavely curved interfaces between conductive regions and the use of insulating spacers to enhance contact areas between contact structures and interconnects in finFETs, reducing contact resistance without increasing the critical dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional planar interfaces are used between contact structures and interconnects, then the manufacturing process remains simple, but the contact resistance is high due to limited contact area
Solution Approach 1:
The patent applies curvature by forming a concavely curved interface between the contact structure and interconnect, replacing the conventional planar interface. This curved geometry increases the contact area between the two structures, thereby reducing contact resistance and improving electrical reliability without requiring larger critical dimensions.
Solution Approach 2:
The patent transitions from a two-dimensional planar interface to a three-dimensional concavely curved interface. This dimensional change allows the contact structure to engage with the interconnect over a larger surface area, effectively reducing contact resistance by utilizing the additional spatial dimension rather than increasing critical dimensions.
2Reliability
If the critical dimensions are increased to reduce contact resistance, then the contact area increases, but the device scaling is compromised
Solution Approach 1:
By forming a concavely curved interface, the patent increases the effective contact area between the contact structure and interconnect without increasing the critical dimensions. The curvature allows the same footprint to provide larger contact area, maintaining device scaling while improving electrical reliability.
Solution Approach 2:
The patent uses the third dimension (vertical depth of the concave curvature) to increase contact area without expanding the lateral critical dimensions. This allows the contact structure to achieve better electrical contact while maintaining the scaled-down footprint required for advanced semiconductor nodes.
3Area of stationary object
If conventional manufacturing processes are used, then the fabrication remains straightforward, but the contact area between contact structures and interconnects is insufficient
Solution Approach 1:
The concavely curved interface is formed using standard semiconductor fabrication techniques such as anisotropic etching or selective removal processes. This approach achieves the curved geometry and increased contact area without requiring fundamentally new manufacturing equipment or processes, integrating smoothly into existing fabrication flows.
Solution Approach 2:
The concave curvature is formed in advance during the contact structure fabrication process, before the interconnect is deposited. This preliminary shaping of the contact structure ensures that when the interconnect is formed, the larger contact area is already in place, allowing subsequent processes to proceed using conventional methods.
Data Source
AI summary
A method of forming a semiconductor device includes forming a source/drain region on a substrate and forming a first interlayer dielectric (ILD) layer over the source/drain region. The method further includes forming a second ILD layer over the first ILD layer, forming a source/drain contact structure within the first ILD layer and the second ILD layer, and selectively removing a portion of the source/drain contact structure to form a concave top surface of the source/drain contact structure.