Schottky Diode Ring Structure With Graded Doping for Breakdown Control

The device is segmented into multiple functional regions including a first region with graded doping concentration, first and second ring regions with different conductivity types, and terminal regions. This segmentation allows each region to perform specific functions: the graded doping region manages electric field distribution, the ring regions with alternating conductivity types create double RESURF effects to enhance breakdown voltage, and terminal regions provide electrical connections. This structural division resolves the contradiction by enabling high breakdown voltage through careful regional design while maintaining manufacturability through systematic fabrication processes.

Different regions of the device are assigned different doping concentrations and conductivity types to optimize local performance. The first region has graded doping concentration varying from light to heavy, the first ring region has second conductivity type while the second ring region has first conductivity type, creating localized electric field management. This local quality differentiation enables the device to achieve high breakdown voltage and low leakage current simultaneously by tailoring properties to specific functional requirements in different spatial locations.

The graded doping concentration is established as a preliminary structure before subsequent processing steps. The first region is doped with graded concentration profiles during early fabrication stages, creating a foundation for later ring region formation and terminal region integration. This preliminary action allows the graded doping structure to be established once, and then subsequent layers and regions are built upon it using standard photolithography and doping techniques, reducing the cumulative precision requirements.

The doping concentration varies in multiple dimensions: vertically through the substrate depth and laterally across the device plane. The graded doping in the first region transitions from light near the surface to heavy deeper in the substrate, while also varying radially from center to perimeter. This multi-dimensional doping profile manages electric fields in three-dimensional space, achieving high breakdown voltage through spatial field distribution rather than relying solely on precise two-dimensional concentration control.

The first ring region with second conductivity type and the second ring region with first conductivity type are merged into a concentric structure within the first region. These ring regions are integrated during the same fabrication sequence, sharing common photolithography masks and doping processes. The merging of these oppositely doped ring regions creates the double RESURF effect that suppresses leakage current through combined electric field management, while the integrated fabrication approach limits the increase in device complexity.

The first ring region and second ring region are nested concentrically within the first region, with each ring region containing or surrounding the other in a nested arrangement. This nesting allows multiple functional regions to be packed efficiently within the device footprint, achieving complex electric field management through compact spatial organization. The nested structure enables the double RESURF effect to occur in a confined area, reducing leakage current without proportionally increasing overall device complexity.