Self-Balancing Super Junction Structure With Implantation-Based Charge Balance
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Solution Overview
Problem
Conventional methods for preparing super junction structures face challenges in achieving charge balance between the P and N regions, leading to high process difficulty and parameter fluctuations due to strict control requirements, especially in lithography processes.
Innovation Solution
A method involving repeated epitaxy and ion implantation processes to form stacked epitaxial layers with aligned implantation regions of opposite doping types, where the charge balance is achieved through ion implantation, reducing the reliance on precise lithography and simplifying the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If deep trench etching and epitaxial filling method is used to prepare super junction structure, then the structure can be formed with alternating PN junctions, but strict control of key parameters (epitaxial layer concentration, trench etching width, filling layer concentration) is required which increases process difficulty and reduces process compatibility
Solution Approach 1:
The patent extracts the charge balance control from the complex multi-parameter process and concentrates it into a single ion implantation step. By removing the barrier layer and performing ion implantation directly on the epitaxial layer, the method eliminates the need to control multiple parameters (trench width, epitaxial concentration, filling concentration) simultaneously, thus reducing process complexity while maintaining charge balance precision
Solution Approach 2:
The patent changes the fundamental parameter control approach from geometric control (trench width, layer thickness) to dosage control (ion implantation dose). This parameter transformation allows charge balance to be achieved through a single controllable parameter (ion dose) rather than multiple interdependent parameters, resolving the contradiction between precision and complexity
2Manufacturing precision
If epitaxy, implantation, and annealing processes are performed multiple times to prepare super junction structure, then alternating PN junctions can be formed, but lithography line width fluctuation greatly affects charge balance and precise line width control cannot be realistically achieved
Solution Approach 1:
The patent removes the lithography process from the charge balance determination step. By using ion implantation through a barrier layer with predefined windows rather than defining implantation regions through lithography, the method extracts charge balance control from the lithography process, eliminating the sensitivity to line width fluctuations
Solution Approach 2:
The barrier layer serves as an intermediary that decouples the lithography process from the ion implantation process. The barrier layer windows are formed by lithography, but the actual charge implantation occurs through this intermediate structure, allowing the lithography tolerances to be much larger while still achieving precise charge balance through controlled ion dosage
3Manufacturing precision
If conventional multilayer epitaxial structure super junction process is used, then super junction structure can be formed, but strict requirements for lithography process control result in high process difficulty and low process compatibility
Solution Approach 1:
The patent extracts the charge balance control function from the lithography process and transfers it to the ion implantation process. This separation allows the lithography process to have relaxed requirements and high compatibility with existing processes, while the ion implantation process independently ensures precise charge balance
Solution Approach 2:
The ion implantation process itself provides the charge balance control without requiring external lithography precision. The method is self-sufficient in achieving charge balance through dosage control, making the process compatible with various lithography capabilities and reducing overall process 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
This approach ensures charge balance solely through implantation, reducing the impact of lithography line width fluctuations, lowering process complexity, and increasing tolerance, thereby improving the consistency and reliability of the super junction structure.
Implementation Method 1
respectively forming an implantation region of the first doping type and an implantation region of a second doping type in the initial epitaxial layer through the implantation window by using an ion implantation process
Implementation Method 2
forming an initial epitaxial layer on the first surface of the substrate of the first doping type
Implementation Method 3
diffusing and connecting the implantation regions of the first doping type to form columns of the first doping type
Data Source
AI summary
A self-balancing super junction structure and a preparation method thereof. The method includes: forming an initial epitaxial layer on a surface of a substrate of a first doping type; respectively forming an implantation region of the first doping type and an implantation region of a second doping type in the initial epitaxial layer; forming an intrinsic epitaxial layer on the surface of the initial epitaxial layer; respectively forming an implantation region of the first doping type and an implantation region of the second doping type in the intrinsic epitaxial layer; and repeating the steps to form a structure with stacked epitaxial layers, and then performing thermal diffusion treatment to form a self-balancing super junction structure. Ions of the first doping type and ions of the second doping type in a same layer of the epitaxial layer stack structure are implanted after a same lithography step.