Semiconductor Well Isolation Using Deep Implants to Cut Leakage
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Solution Overview
Problem
The increased integration density in semiconductor devices leads to closer well spacing, resulting in higher leakage current among adjacent well regions, which reduces the quality and productivity of semiconductor devices.
Innovation Solution
The semiconductor device incorporates two deep implant regions with dopant types opposite to those of adjacent well regions, positioned at both sides of the shallow trench isolation (STI) structure and vertically lower than it, to act as charge barriers and improve segregation between well regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If integration density is increased to improve productivity, then productivity is improved, but leakage current increases reducing device quality
Solution Approach 1:
The patent introduces deep implant regions as intermediary structures between adjacent well regions. These deep implant regions, positioned below the STI structure and extending laterally between wells, act as mediator zones that intercept and block leakage current paths without preventing the close spacing of wells needed for high integration density.
Solution Approach 2:
The patent moves the leakage blocking function from the lateral dimension (where well spacing occurs) to the vertical dimension by placing deep implant regions below the STI structure. This dimensional transition allows wells to remain closely spaced laterally while introducing blocking structures in the vertical-substrate plane that prevent leakage without increasing lateral spacing.
2Area of moving object
If well spacing is reduced to improve integration density, then integration density is improved, but leakage current increases reducing device quality
Solution Approach 1:
The patent resolves the well spacing contradiction by transitioning the leakage blocking mechanism from lateral to vertical positioning. Deep implant regions are placed below the STI structure in the vertical dimension, allowing minimal lateral spacing between wells while maintaining effective leakage blocking through the substrate depth.
Solution Approach 2:
Deep implant regions serve as intermediary blocking structures that enable close well spacing by providing leakage current interception paths beneath the STI structure, decoupling the lateral well spacing parameter from the leakage blocking function.
3Reliability
If deep implant regions are added to reduce leakage current, then leakage current is reduced, but device complexity increases
Solution Approach 1:
The deep implant regions serve multiple functions simultaneously: they block leakage current between adjacent wells, extend laterally to provide comprehensive coverage between wells, and position vertically below the STI structure to leverage the isolation structure's shielding effect. This multi-functionality reduces the need for additional separate structures.
Solution Approach 2:
The patent merges the leakage blocking function with the existing STI structure by positioning deep implant regions below it and using the STI as a shielding element. This combination leverages the STI structure's presence to enhance the blocking effect without requiring completely separate isolation mechanisms.
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 configuration effectively reduces well-to-well leakage current, enabling more compact chip designs and robust performance in semiconductor devices.
Implementation Method 1
two deep implant regions with dopant types opposite to those of adjacent well regions... to act as charge barriers and improve segregation between well regions
Data Source
AI summary
A semiconductor device includes a first well region laterally separated from a second well region in a substrate, a shallow trench isolation (STI) structure laterally between the first well region and the second well region in the substrate, a first implant region of a dopant type opposite to a dopant type of the first well region in the substrate, disposed vertically lower than the STI structure and laterally between the first well region and a lateral center of the STI structure, and a second implant region of a dopant type opposite to a dopant type of the second well region in the substrate, disposed vertically lower than the STI structure and laterally between the second well region and the lateral center of the STI structure.