Backside-Contact FET Structure With Uniform Source/Drain Regions
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Solution Overview
Problem
The formation of direct backside contact structures in field-effect transistors can interfere with the formation of other elements, such as source/drain regions, and there is a need for semiconductor devices with both front side and backside contact plugs of uniform size or height to ensure consistent device performance and integration.
Innovation Solution
A method of manufacturing field-effect transistors where front side and backside contact plugs are formed on source/drain regions of uniform size or height, involving the creation of recesses, placeholder structures, and subsequent epitaxial growth, allowing for self-aligned backside contact plugs and maintaining consistent device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If direct backside contact structures are formed in field-effect transistors, then power distribution network performance is improved, but formation of other elements such as source/drain regions is interfered with
Solution Approach 1:
The method performs preliminary actions by forming placeholder structures at the backside contact locations before forming the source/drain regions. These placeholders define the contact locations and prevent interference with subsequent source/drain region formation, resolving the contradiction between improving power distribution network performance and maintaining ease of manufacture.
2Reliability
If front side and backside contact plugs are formed on source/drain regions, then device performance is improved, but device complexity increases
Solution Approach 1:
The contact plug structure is segmented into front side contact plugs and backside contact plugs that are formed separately through different process sequences. The backside contact plugs are formed first with placeholders, then source/drain regions are formed, and finally front side contact plugs are formed. This segmentation allows each contact plug type to be optimized independently, improving device performance while managing complexity through systematic process separation.
Solution Approach 2:
Backside contact plugs are formed preliminarily before source/drain regions through the placeholder structure method. This preliminary action establishes the backside contact infrastructure early in the process, allowing front side contact plugs to be added later without interfering with the already-formed backside contacts, thus managing device complexity while achieving dual-contact performance.
3Manufacturing precision
If source/drain regions are formed after backside contact structures, then manufacturing precision is improved, but formation of other elements is interfered with
Solution Approach 1:
Placeholder structures are formed preliminarily at the backside contact locations before source/drain region formation. These placeholders serve as physical guides that define the exact locations where source/drain regions should be formed, ensuring manufacturing precision and uniformity. The placeholders prevent interference with source/drain region formation by pre-establishing the contact boundaries, thus resolving the contradiction between improving manufacturing precision and maintaining ease of manufacture.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables the formation of field-effect transistors with both front side and backside contact plugs of uniform size or height, improving device consistency and performance by ensuring uniform source/drain regions, which is crucial for high-density and high-performance integrated circuits.
Implementation Method 1
involving the creation of recesses, placeholder structures, and subsequent epitaxial growth
Data Source
Figure 1A~1D
Figure 2A~2D
Figure 3A~3D
AI summary
Provided is field-effect transistor structure including: a channel structure; a 1st source/drain region and a 2nd source/drain region connected to each other through the channel structure; a 1st contact plug, on a top surface of the 1st source/drain region, connected to a 1st voltage source or 1st circuit element through a back-end-of-line (BEOL) structure; and a 2nd contact plug, on a bottom surface of the 2nd source/drain region, connected to the 1st voltage source, through a backside power rail, or another circuit element, wherein the 1st source/drain region and the 2nd source/drain region have a substantially same height.