Lateral Superjunction MOSFET Termination Structure Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The design and manufacturing of superjunction semiconductor devices face challenges such as difficulties in forming the superjunction structure, improving manufacturability, and high product costs, particularly with epitaxial processes, and require effective termination structures to ensure robust device operation.
Innovation Solution
A lateral superjunction MOSFET device is developed with a low voltage MOS gate structure, incorporating N-type and P-type columns and an edge termination structure using ion implantation to form alternating superjunction layers, which improves charge control and reduces manufacturing variations, and employs termination pillars and RESURF surface implants to enhance breakdown voltage and manufacturability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If epitaxial processes are used to form superjunction structure, then manufacturing precision is improved, but product cost increases and manufacturability deteriorates
Solution Approach 1:
The patent changes the formation method parameters from epitaxial growth to ion implantation followed by selective removal. This parameter change allows achieving the same superjunction structure with better process control and lower cost, resolving the contradiction between manufacturing precision and ease of manufacture
Solution Approach 2:
The patent replaces the chemical epitaxial growth process with a physical ion implantation process followed by selective etching. This substitution enables better precision control through ion dose management and improves manufacturability by using more controllable and cheaper ion implantation equipment
2Reliability
If termination structure is added to manage high electrical fields, then device reliability is improved, but device complexity increases
Solution Approach 1:
The patent merges the termination structure formation with the existing superjunction fabrication steps. The same ion implantation and selective removal processes used to create the superjunction structure are also employed to form the termination regions, thereby improving reliability without significantly increasing device complexity
Solution Approach 2:
The patent creates a multi-functional structure where the termination regions serve both as field management elements and as part of the overall device architecture. The N-type and P-type columns serve dual purposes: forming the superjunction structure for low on-resistance and providing termination for high voltage breakdown, thus improving reliability without adding separate complexity
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 solution enables the lateral superjunction MOSFET device to achieve high breakdown voltage while optimizing on-resistance and switching speed, with improved manufacturability and reduced costs compared to conventional epitaxial processes, and effectively manages high electrical fields at the device terminations.
Implementation Method 1
incorporating N-type and P-type columns and an edge termination structure using ion implantation to form alternating superjunction layers
Data Source
AI summary
A method for forming a lateral superjunction MOSFET device includes forming a semiconductor body including a lateral superjunction structure and a first column connected to the lateral superjunction structure. The MOSFET device includes the first column to receive current from the channel when the MOSFET is turned on and to distribute the channel current to the lateral superjunction structure functioning as the drain drift region. In some embodiment, the MOSFET device includes a second column disposed in close proximity to the first column. The second column disposed near the first column is used to pinch off the first column when the MOSFET device is to be turned off and to block the high voltage being sustained by the MOSFET device at the drain terminal from reaching the gate structure. In some embodiments, the MOSFET device further includes termination structures for the drain, source and body contact doped region fingers.