Source Drain Region Contact Hole Resistance Reduction
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Solution Overview
Problem
As semiconductor devices shrink, reducing contact resistance between the source/drain region and contact hole becomes increasingly challenging due to the decreasing critical size of contact holes, making it difficult to optimize device performance.
Innovation Solution
The solution involves forming a source/drain region with a first region embedded in the substrate and a second region on top, made of a different material, which allows for a contact hole to be formed with increased contact area by forming a groove that terminates above the first region, thereby increasing the contact area and reducing resistance. This includes using auxiliary and stop layers to adjust the groove profile and size, and synchronously forming contact holes for PMOS and NMOS devices to simplify the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the critical size of semiconductor devices is decreased, then device integration density is improved, but contact resistance increases due to smaller contact hole area
Solution Approach 1:
The contact hole interface with the source/drain region is extended from a single bottom surface to include both bottom and side surfaces by forming a groove that terminates above the first region. This dimensional extension of the contact interface compensates for the reduced contact area caused by smaller device sizes, thereby maintaining low contact resistance despite continued device scaling.
2Area of moving object
If the contact hole size is decreased, then device miniaturization is achieved, but contact area is reduced leading to higher contact resistance
Solution Approach 1:
By forming a groove in the source/drain region that terminates above the first region, the contact interface is extended to include side surfaces in addition to the bottom surface. This creates a multi-faceted contact interface that increases the effective contact area without requiring a larger contact hole opening, thus maintaining low contact resistance during device miniaturization.
Solution Approach 2:
The source/drain region is divided into a first region embedded in the substrate and a second region formed on the first region. This segmentation allows the contact hole to interface with both regions, creating extended contact pathways through the groove structure that increases the effective contact area while maintaining a small contact hole footprint.
3Reliability
If a contact region is formed on the source/drain region to reduce contact resistance, then contact reliability is improved, but manufacturing complexity increases due to additional process steps
Solution Approach 1:
The groove formation process is combined with the contact hole formation process, where the same etching steps that create the contact hole also form the groove in the source/drain region. This merging of operations extends the contact interface without requiring separate manufacturing steps, thereby reducing contact resistance while avoiding additional process complexity.
Data Source
AI summary
An S/D region including a first region and a second region is provided. The first region is located, with at least a partial thickness, in the substrate. The second region is formed on the first region and made of a material different from that of the first region. A method for forming an S/D region is further provided, and the method includes: forming trenches at both sides of a gate stack structure in a substrate; forming a first semiconductor layer, wherein at least a part of the first semiconductor layer is filled into the trenches; and forming a second semiconductor layer on the first semiconductor layer, wherein the second semiconductor layer is made of a material different from that of the first semiconductor layer. A contact hole and a forming method thereof are also provided which may increase the contact area between a contact hole and a contact region, and reduce the contact resistance.