High Voltage Diode With Deep Well For Low On-Resistance
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Solution Overview
Problem
Conventional CMOS embedded high voltage diodes achieve high breakdown voltage at the expense of high on-resistance, limiting their efficiency in applications requiring both high voltage and low resistance.
Innovation Solution
A diode design incorporating a semiconductor substrate with balanced dopant type wells and regions, including a deep well that fully depletes the conduction path to reduce electric field, allowing for adjustable breakdown voltage and on-resistance with minimal tradeoff, using shallow trench isolation and specific dopant densities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a low doped drift region is used to reduce the junction field, then the breakdown voltage is high, but the on-resistance becomes high
Solution Approach 1:
The patent applies local quality by creating distinct doped regions with different doping concentrations at specific locations within the semiconductor structure. The lightly-doped drift region is positioned between the heavily-doped contact regions and the junction, allowing each zone to perform its specific function: the lightly-doped region manages the electric field for high breakdown voltage, while the heavily-doped contact regions provide low resistance paths for current flow.
Solution Approach 2:
The patent transitions from a conventional planar junction structure to a vertically stacked multi-region structure. By adding the dimension of vertical layering with the drift region positioned between contact regions and the junction, the patent achieves both high breakdown voltage and low on-resistance simultaneously, resolving the trade-off present in conventional single-plane designs.
2Reliability
If the dopant density in the drift region is reduced to achieve high breakdown voltage, then the electric field is reduced, but the on-resistance increases
Solution Approach 1:
The patent implements local quality by assigning different doping concentrations to different spatial zones: the drift region maintains low dopant density (10^14 to 10^16 atoms/cm³) specifically where electric field management is critical, while the contact regions use high dopant density (10^19 to 10^21 atoms/cm³) where low resistance is critical. This localized optimization resolves the contradiction between breakdown voltage and on-resistance.
Solution Approach 2:
The patent segments the semiconductor structure into functionally distinct regions: lightly-doped drift regions for electric field control and heavily-doped contact regions for low resistance current flow. This segmentation allows each segment to be optimized for its specific function without compromising the other, achieving both high breakdown voltage and low on-resistance.
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 diode achieves high breakdown voltage while maintaining low on-resistance, enabling efficient operation in high voltage applications such as switches and voltage regulators with adjustable performance.
Implementation Method 1
uses a low doped drift region to reduce the junction field
Implementation Method 2
a lightly P-doped semiconductor substrate (P-substrate) includes a low N-doped drift region (N-drift), P+ doped region (28) as the anode, and an N+ doped region (30) as the cathode
Data Source
AI summary
A diode, includes a semiconductor substrate, a first region doped with a first dopant type in the substrate, a second region doped with a second dopant type in the substrate, a first well of the first dopant type in the substrate and surrounding the first region and the second region, and a second well of the second dopant type in the substrate connecting the first region and the second region. The first dopant type is opposite the second dopant type.