CPODE Isolation Structure for Lower Parasitic Capacitance
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Solution Overview
Problem
As integrated circuit technologies progress towards smaller technology nodes, parasitic capacitance between active device regions becomes a significant factor in reducing device speed and increasing RC delays, with existing methods of reducing parasitic capacitance being inadequate in all aspects.
Innovation Solution
The method involves forming a Continuous Poly on Diffusion Edge (CPODE) structure by replacing a dummy gate stack with a dielectric material in field-effect transistors, specifically in three-dimensional nanostructure FETs, to reduce parasitic capacitance by using a dielectric material with lower k values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If separation distances between active device regions are reduced to meet design requirements of smaller technology nodes, then functional density increases, but parasitic capacitance increases leading to lower device speed
Solution Approach 1:
The patent applies local quality by replacing the dummy gate stack material with a dielectric material that has a lower k value than the original dummy gate material. This creates a localized region with different dielectric properties (lower parasitic capacitance) specifically where needed between active device regions, while leaving the rest of the device structure unchanged. The selective material substitution addresses the parasitic capacitance issue locally without affecting overall device architecture.
2Speed
If dummy gate stack is replaced with dielectric material to reduce parasitic capacitance, then device speed improves, but manufacturing complexity increases
Solution Approach 1:
The patent employs preliminary action by forming the dielectric material in the dummy gate stack region before final device assembly and testing. This early substitution ensures that the lower-k dielectric is already in place during subsequent processing steps, preventing parasitic capacitance issues from developing later. The dummy gate stack is replaced with the dielectric material during an intermediate processing stage, allowing for verification and adjustment before final device completion.
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 effectively reduces parasitic capacitance, enhancing device performance by minimizing RC delays and improving processing speed in semiconductor devices.
Implementation Method 1
parasitic capacitance of dielectric components disposed between active device regions may have serious bearings on the overall performance of an IC device
Implementation Method 2
replacing a dummy gate stack with a dielectric material in field-effect transistors, specifically in three-dimensional nanostructure FETs, to reduce parasitic capacitance by using a dielectric material with lower k values
Data Source
AI summary
A semiconductor structure includes semiconductor layers disposed over a substrate and oriented lengthwise in a first direction, a metal gate stack disposed over the semiconductor layers and oriented lengthwise in a second direction perpendicular to the first direction, where the metal gate stack includes a top portion and a bottom portion that is interleaved with the semiconductor layers, source/drain features disposed in the semiconductor layers and adjacent to the metal gate stack, and an isolation structure protruding from the substrate, where the isolation structure is oriented lengthwise along the second direction and spaced from the metal gate stack along the first direction, and where the isolation structure includes a dielectric layer and an air gap.