N-well Resistor With Segmented Deep N-well For SOI Isolation
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Solution Overview
Problem
N-well resistors are restricted in semiconductor on insulator (SOI) technologies due to deeper shallow trench isolation (STI) compared to N-well depth, limiting their use in circuit designs.
Innovation Solution
The implementation of a structure comprising a substrate with N-well and deep N-well implant regions, along with shallow trench isolation regions that extend into these layers but not beyond the deep N-well implant region, allowing for adjustable resistance without additional masking or processing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If shallow trench isolation regions are made deeper to provide robust N-well to N-well isolation in SOI technology, then isolation reliability is improved, but N-well resistors cannot be used because the STI depth exceeds N-well depth
Solution Approach 1:
The implant region is segmented into two distinct depth zones: a first N-well implant region at a shallower depth and a second N-well implant region at a greater depth. The shallow trench isolation regions extend into both regions but terminate before reaching the substrate, creating isolated N-well zones that function as resistors while maintaining robust isolation between adjacent N-wells.
Solution Approach 2:
The solution introduces a vertical depth dimension with two distinct implant regions at different depths. By implanting N-type dopants at two different depths (first and second N-well implant regions) and using STI regions that extend into both but terminate above the substrate, the patent creates a three-dimensional structure that enables resistor functionality while maintaining isolation reliability.
2Adaptability or versatility
If N-well resistors are used in SOI technology with deep STI, then circuit design flexibility is improved, but additional masking and processing steps are required
Solution Approach 1:
The patent merges the isolation structure and resistor formation into a single integrated process. The shallow trench isolation regions are formed to extend into both the first and second N-well implant regions, simultaneously achieving N-well to N-well isolation and defining the resistor regions. This consolidation eliminates the need for separate masking and processing steps that would otherwise be required.
Solution Approach 2:
The shallow trench isolation regions serve multiple functions: they provide robust N-well to N-well isolation by extending into both implant regions, and they simultaneously define the boundaries of the N-well resistor regions. This multi-functionality allows the same structural element to address both isolation requirements and resistor formation, reducing overall device complexity.
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
Enables tuning of N-well resistance by varying the density of shallow trench isolation structures, facilitating their use in circuit designs without requiring extra processing steps, and maintaining robust N-well to N-well isolation.
Implementation Method 1
forming a N-well implant in a bulk wafer of the SOI technology; and forming a deep N-well implant below the N-well implant in the bulk wafer of the SOI technology
Data Source
AI summary
The present disclosure relates to semiconductor structures and, more particularly, to n-well resistors and methods of manufacture. The structure includes: a substrate composed of a N-well implant region and a deep N-well implant region; and a plurality of shallow trench isolation regions extending into both the N-well implant region and a deep N-well implant region.