Junction Termination Extension Doping Trimming for Power Devices
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional power semiconductor devices face issues with leakage current due to electric field crowding at the edges, leading to potential device breakdown, which is exacerbated by the complexity and cost of forming junction termination extensions (JTE) with multiple mask and implantation steps.
Innovation Solution
A method of forming power semiconductor devices with edge terminations that involves forming a junction termination extension with varying doping concentrations, followed by a dopant activation process and subsequent etching to adjust the effective doping concentration, allowing for in-process probing and trimming to achieve optimal breakdown voltage without the need for calibration wafers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional JTE formation with multiple mask and implantation steps is used, then the doping concentration can be controlled, but the manufacturing complexity and cost increase
Solution Approach 1:
The JTE formation process is segmented into two distinct phases: (1) forming the JTE structure with initial doping using conventional mask and implantation steps, and (2) selectively removing portions of the JTE in a second processing step to achieve the desired doping concentration profile. This segmentation allows the complex doping control to be achieved through a structured multi-step process rather than requiring all doping steps to be performed simultaneously, thereby managing manufacturing complexity while maintaining precision.
Solution Approach 2:
The patent applies preliminary action by first forming the complete JTE structure with sufficient doping concentration using standard mask and implantation techniques, then subsequently removing excess JTE material in a controlled manner. This preliminary formation of the full JTE structure allows the use of well-established, precise doping methods first, followed by a trimming step that fine-tunes the doping concentration by removing material, thereby achieving precise control without requiring all precision steps to be performed in a single complex operation.
2Reliability
If higher doping concentration is used in JTE, then the breakdown voltage may be insufficient, but if lower doping concentration is used, then leakage current increases
Solution Approach 1:
The patent implements local quality by creating a non-uniform doping concentration profile within the JTE structure, where the doping concentration varies spatially. Specifically, the JTE has higher doping concentration in regions closer to the active area and lower doping concentration in outer regions, or vice versa depending on the specific design. This spatial variation in doping quality allows the structure to simultaneously achieve adequate breakdown voltage (by having sufficient doping in critical regions) while minimizing leakage current (by having lower doping in regions where it would be harmful), thus resolving the contradiction between these two opposing requirements.
Solution Approach 2:
The patent applies parameter changes by systematically varying the doping concentration parameter across different regions of the JTE structure. Rather than using a uniform doping concentration, the invention employs a graded or stepped doping profile where the doping level is adjusted in different zones. This parameter variation allows optimization of both breakdown voltage and leakage current characteristics by matching the doping concentration to the specific electrical requirements of each region within the JTE structure.
3Manufacturing precision
If calibration wafers are used to determine optimal doping levels, then the breakdown voltage can be optimized, but the manufacturing time and cost increase
Solution Approach 1:
The patent applies self-service by designing a JTE formation process that uses the device's own structure and characteristics to determine the optimal doping concentration. The method involves forming the JTE with initial doping, then selectively removing portions of the JTE based on observed electrical characteristics or geometric considerations, allowing the process to self-adjust and optimize the doping level without requiring external calibration wafers. This self-service approach eliminates the need for separate calibration steps while still achieving optimized breakdown voltage performance.
Solution Approach 2:
The patent extracts the calibration step from the overall manufacturing process by eliminating the need for separate calibration wafers. Instead of using additional test structures or calibration devices, the invention integrates the optimization function directly into the main JTE formation process through selective removal of JTE material. This extraction of the calibration function from a separate step and its integration into the primary manufacturing flow reduces manufacturing cycle time while maintaining the ability to optimize breakdown voltage performance.
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 reduces the complexity and cost of JTE formation, enhances the breakdown voltage performance by optimizing the doping levels in real-time, and eliminates the need for calibration wafers, thereby improving the reliability and efficiency of power semiconductor devices.
Implementation Method 1
a dopant activation process is performed to activate at least some of the dopants in the junction termination zones
Implementation Method 2
the junction termination extension is etched in order to reduce the effective doping concentration of dopants within the junction termination extension
Data Source
AI summary
Methods of forming a power semiconductor device having an edge termination are provided in which the power semiconductor device that has a drift region of a first conductivity type is formed on a substrate. A junction termination extension is formed on the substrate adjacent the power semiconductor device, the junction termination extension including a plurality of junction termination zones that are doped with dopants having a second conductivity type. The junction termination zones have different effective doping concentrations. A dopant activation process is performed to activate at least some of the dopants in the junction termination zones. An electrical characteristic of the power semiconductor device is measured. Then, the junction termination extension is etched in order to reduce the effective doping concentration within the junction termination extension.