Semiconductor Isolation Ring Reducing Parasitic Effects
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Solution Overview
Problem
High-frequency operations in semiconductor processes lead to significant parasitic effects due to parasitic resistance and capacitance, which are difficult to mitigate effectively using existing multi-well structures, especially in radio frequency (RF) applications.
Innovation Solution
A semiconductor structure incorporating a first and second well with a deep isolation layer forming a ring structure around the first well, and optionally a heavily-doped region with a second isolation layer, where the doping types of the wells are different to reduce parasitic effects by increasing parasitic resistance and decreasing capacitance, and allowing for reverse bias voltage application through openings in the isolation layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multi-well structures are used to reduce parasitic effects, then isolation effect is improved, but parasitic resistance and capacitance remain significant at high frequencies
Solution Approach 1:
The patent transitions from planar isolation to three-dimensional isolation by forming isolation layers that extend vertically to the surface of the semiconductor substrate. This deep isolation structure creates additional isolation dimension, effectively reducing parasitic coupling between adjacent wells at high frequencies where traditional shallow isolation fails.
Solution Approach 2:
The patent introduces an intermediate isolation layer between adjacent doped wells that acts as a mediator to reduce direct parasitic coupling. This isolation layer, extending from the substrate surface to the well bottom, provides an intermediate barrier that reduces both parasitic resistance and capacitance between neighboring wells.
2Object-affected harmful factors
If deep isolation layers are formed to reduce parasitic effects, then parasitic resistance increases and capacitance decreases, but device complexity increases
Solution Approach 1:
The deep isolation layer serves multiple functions simultaneously: it provides electrical isolation between adjacent wells, reduces parasitic coupling at high frequencies, and can be integrated with existing CMOS fabrication processes. This multi-functionality reduces the need for additional specialized structures, thereby limiting the increase in device complexity.
Solution Approach 2:
The patent merges the isolation structure with the well formation process by using the same doped regions to define both the wells and the isolation boundaries. The isolation layer is formed in the same fabrication sequence as the well doping, combining multiple functions into a unified structure rather than adding separate isolation components.
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
The deep isolation layers effectively reduce parasitic effects, enhancing the performance of semiconductor elements by increasing parasitic resistance and decreasing capacitance, thereby improving device performance, especially at high frequencies.
Implementation Method 1
parasitic effects with parasitic resistance and capacitance generated by high-frequency operation
Implementation Method 2
parasitic effects with parasitic resistance and capacitance generated by high-frequency operation
Implementation Method 3
parasitic effects with parasitic resistance and capacitance generated by high-frequency operation
Implementation Method 4
parasitic effects with parasitic resistance and capacitance generated by high-frequency operation
Data Source
AI summary
A semiconductor structure includes a first well, a semiconductor element, a second well and a first isolation layer. The semiconductor element is formed on or contacts the first well. The first well is formed on the second well. The first isolation layer is used to reduce a parasitic effect between the first well and the second well. The bottom of the first isolation layer is at least as deep as the bottom of the first well. The first isolation layer substantially forms a first ring structure around the first well. The doping type of the second well is different from the doping type of the first well.