Super-junction Device Channel Length Control via Sacrificial Stack
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Solution Overview
Problem
Conventional super-junction device manufacturing methods result in varying channel lengths due to alignment errors, leading to inconsistent switching performance and reliability issues across different batches.
Innovation Solution
The method involves forming a sacrificial stack that defines the channel length of the super-junction device, allowing for self-aligned formation of the body and source regions, with the sidewall thickness of the sacrificial stack determining the channel length, thereby reducing process fluctuations and improving reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ion implantation steps are used to form body region and source region, then the manufacturing process is simple, but the channel length varies due to alignment errors leading to poor reliability
Solution Approach 1:
A sacrificial stack is introduced as an intermediary structure to define the channel length. The sacrificial stack serves as a reference structure that mediates the alignment between body region and source region formation, eliminating direct alignment errors between these two regions while adding a temporary structure that is removed later.
Solution Approach 2:
The sacrificial stack is formed preliminarily before the body region and source region ion implantation steps. This preliminary structure establishes the channel length definition early in the process, allowing subsequent steps to align relative to this fixed reference rather than requiring precise mutual alignment between body and source regions.
2Manufacturing precision
If alignment errors occur in conventional manufacturing, then the manufacturing process is fast, but the channel length varies across batches leading to inconsistent switching performance
Solution Approach 1:
The sacrificial stack acts as an intermediary reference that decouples the alignment requirements. Instead of requiring precise alignment between body and source regions directly, both regions align to the sacrificial stack, which is formed with controlled dimensions. This intermediary approach improves channel length precision without significantly impacting manufacturing efficiency.
Solution Approach 2:
The sacrificial stack serves multiple functions: it defines the channel length, serves as an alignment reference for both body and source region formation, and provides a physical mask during ion implantation. This self-service approach consolidates multiple functions into one structure, improving precision while maintaining efficiency.
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 approach ensures a consistent channel length across batches, enhancing the reliability and performance of the super-junction device by controlling the sidewall thickness, which corresponds to the predetermined value, thus improving the specific on-resistance and withstand voltage.
Implementation Method 1
forming a body region in the epitaxial layer with the sacrificial stack as a first hard mask, the body region having a first edge aligned with the first hard mask; forming a sidewall on a side surface of the sacrificial stack; forming a source region in the body region with the sacrificial stack and the sidewall as a second hard mask, the source region having a first edge aligned with the second hard mask
Data Source
AI summary
The present disclosure relates to a super-junction device and a manufacturing method thereof. In the manufacturing method, a first plurality of semiconductor pillars are formed in an epitaxial layer and a sacrificial stack is formed above the epitaxial layer. The sacrificial stack is used as a hard mask both for a body region and for a source region, and has a sidewall which controls a channel length of the super-junction device to reduce process fluctuation in different batches and improve reliability of the super-junction device.