High-Voltage Semiconductor Structure With Segmented Column Doping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing high-voltage power semiconductor devices face challenges in achieving a balance between breakdown voltage and on resistance, with known multi-drain devices requiring complex processes and often having non-constant dopant profiles, making it difficult to extend voltage class and implement efficiently.
Innovation Solution
A high-voltage device structure featuring column structures with a high aspect ratio deep trench filled partially with an epitaxial layer of opposing conductivity, counterbalancing dopant charge, and a dielectric layer to fill the trench, allowing for a U-shaped external portion with controlled dopant concentration, facilitating easier implementation and improved charge balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multi-drain devices are implemented with charge balanced column structures, then breakdown voltage is improved, but device complexity and manufacturing complexity increase
Solution Approach 1:
The drain region is segmented into multiple column structures (first conductivity type) separated by regions of the second conductivity type. This segmentation creates charge-balanced regions that improve breakdown voltage while maintaining a manageable structural complexity through periodic repetition of the segmented pattern.
Solution Approach 2:
Different regions of the device are assigned different conductivity types and dopant concentrations to optimize local charge balance. The column structures have one conductivity type while the regions between them have the opposite type, creating localized charge compensation that improves overall breakdown voltage without requiring complex global restructuring.
2Reliability
If dopant implantation and diffusion processes are used to create column structures, then charge balance is achieved, but manufacturing precision and process complexity increase
Solution Approach 1:
The column structures are formed by preliminary epitaxial growth of regions with predetermined dopant concentrations and conductivity types. This preliminary action establishes the charge balance framework before final device fabrication, reducing the precision requirements for subsequent implantation and diffusion steps while maintaining overall charge balance.
3Loss of energy
If high dopant concentration is used in the drain layer, then on resistance is reduced, but breakdown voltage decreases
Solution Approach 1:
Regions of the second conductivity type are positioned between the column structures to counterbalance the charge in the high-dopant column structures. This charge compensation allows the column structures to maintain high dopant concentrations for low on-resistance while the counterbalancing regions prevent excessive electric field buildup, preserving breakdown voltage.
Solution Approach 2:
The dopant concentration is varied spatially across the drain region, with high concentrations in the column structures for low resistance and lower concentrations in the regions between columns for high breakdown voltage. This parameter variation optimizes both conduction losses and breakdown characteristics simultaneously.
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 solution simplifies the manufacturing process, maintains charge balance with reduced conduction losses, and allows for the extension of voltage class in high-voltage devices by using a controlled dopant profile and dielectric filling, enhancing the efficiency and scalability of high-voltage devices.
Implementation Method 1
epitaxially growing on said semiconductor substrate an epitaxial layer having the first conductivity type
Implementation Method 2
subjected to a following diffusion process of the dopant atoms
Data Source
AI summary
An embodiment of a structure for a high voltage device of the type which comprises at least a semiconductor substrate being covered by an epitaxial layer of a first type of conductivity, wherein a plurality of column structures are realized, which column structures comprises high aspect ratio deep trenches, said epitaxial layer being in turn covered by an active surface area wherein said high voltage device is realized, each of the column structures comprising at least an external portion being in turn realized by a silicon epitaxial layer of a second type of conductivity, opposed than said first type of conductivity and having a dopant charge which counterbalances the dopant charge being in said epitaxial layer outside said column structures, as well as a dielectric filling portion which is realized inside said external portion in order to completely fill said deep trench.