Semiconductor Field Electrode Structures for Low On-State Resistance
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Solution Overview
Problem
Power semiconductor devices based on IGFET cells face challenges in achieving low ohmic losses and high breakdown voltage due to wafer bowing caused by deep compensation structures filled with thick field dielectrics, which can result in inadequate dopant concentrations and compromised blocking capability.
Innovation Solution
The semiconductor device incorporates field electrode structures and termination structures arranged in regular patterns, with doped regions forming homojunctions or pn junctions with the drift zone, allowing for controlled current flow and increased dopant concentrations without adverse effects on blocking capability, thereby reducing on-state resistance and enhancing breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If deep compensation structures filled with thick field dielectrics are used to reduce on-state resistance, then higher dopant concentrations can be achieved, but wafer bowing occurs which compromises blocking capability
Solution Approach 1:
The device is divided into two distinct regions: a cell area with field electrode structures for low on-state resistance, and an edge area with termination structures for high breakdown voltage. This segmentation allows each region to be optimized independently, resolving the contradiction between reducing on-state resistance and maintaining blocking capability.
Solution Approach 2:
Different structural configurations are applied to different regions of the semiconductor device. The cell area employs field electrode structures with specific dopant concentrations optimized for conduction, while the edge area uses termination structures with dopant concentrations optimized for voltage blocking. This local differentiation enables simultaneous optimization of both on-state resistance and blocking capability.
2Loss of energy
If deep compensation structures are used to increase dopant concentration, then on-state resistance decreases, but wafer bowing occurs leading to manufacturing difficulties
Solution Approach 1:
The compensation structures are segmented into field electrode structures in the cell area and termination structures in the edge area. This segmentation allows the field dielectric thickness and dopant concentration to be optimized separately in each region, enabling deep compensation in the cell area without causing excessive wafer bowing that would compromise manufacturing.
Solution Approach 2:
The patent employs different dopant concentrations and field dielectric thicknesses in different regions. By changing these parameters locally rather than uniformly across the entire device, the patent achieves deep compensation where needed while maintaining manufacturability by avoiding excessive wafer bowing in critical areas.
3Ease of manufacture
If uniform structural configuration is used across the entire device, then manufacturing is simplified, but performance is compromised due to inability to optimize different regions for different functions
Solution Approach 1:
The patent applies different structural configurations to different regions: field electrode structures in the cell area and termination structures in the edge area. Each region is optimized for its specific function - conduction in the cell area and voltage blocking in the edge area - thereby achieving high reliability without sacrificing manufacturability, as the different structures are integrated into a single device architecture.
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 configuration effectively reduces on-state resistance and increases breakdown voltage, improving the semiconductor device's performance by allowing higher dopant concentrations while maintaining or improving blocking capability.
Implementation Method 1
Doped regions directly adjoin the termination structures and form pn junctions with the drift zone in the inner edge area
Implementation Method 2
At least one doped region forms a homojunction with the drift zone in the inner edge area
Implementation Method 3
a voltage applied to a gate electrode controls a current flow through the cell mesas
Data Source
AI summary
A semiconductor device includes field electrode structures regularly arranged in lines in a cell area and forming a first portion of a regular pattern. Termination structures are formed in an inner edge area surrounding the cell area, wherein at least portions of the termination structures form a second portion of the regular pattern. Cell mesas separate neighboring ones of the field electrode structures from each other in the cell area and include first portions of a drift zone, wherein a voltage applied to a gate electrode controls a current flow through the cell mesas. At least one doped region forms a homojunction with the drift zone in the inner edge area.