High Voltage DDDMOS Drift Region Segmentation
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Solution Overview
Problem
High voltage DDDMOS devices have limited breakdown voltage and application range due to inflexible ion-implantation parameters, requiring additional manufacturing steps when integrated with low voltage devices, which increases costs.
Innovation Solution
A high voltage device design with a drift region comprising multiple sub-regions electrically connected via buffer regions, allowing for the same manufacturing process steps as low voltage devices, including the formation of lightly doped drains, to enhance breakdown voltage without additional process steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional manufacturing process steps are used to provide different ion-implantation parameters for high voltage devices, then breakdown voltage increases, but manufacturing cost increases
Solution Approach 1:
The drift region is segmented into multiple sub-regions (first drift region and second drift region) with different doping concentrations. The first drift region has a higher doping concentration than the second drift region, creating a gradient structure that enhances breakdown voltage without requiring additional ion-implantation steps. This segmentation is achieved through selective masking during a single ion-implantation process.
Solution Approach 2:
Different regions of the drift region are given different doping concentrations to optimize local electrical properties. The first drift region under the lightly doped drain has higher doping concentration for lower on-resistance, while the second drift region has lower doping concentration for higher breakdown voltage. This local quality variation is achieved through selective masking patterns in the ion-implantation process.
2Ease of manufacture
If common manufacturing process steps are used for both high voltage and low voltage devices, then manufacturing cost decreases, but breakdown voltage of high voltage device decreases
Solution Approach 1:
The masking pattern is dynamically adjusted to create different doping profiles in different regions during the same ion-implantation process. By using a masking pattern that selectively covers certain areas, the process dynamically creates the first drift region with higher doping concentration in specific areas while maintaining lower doping concentration in other areas, all within a single ion-implantation step.
Solution Approach 2:
The doping concentration parameter is changed across different regions of the drift region by using selective masking during ion-implantation. The masking pattern allows the same ion-implantation process to deposit different amounts of dopant in different areas, creating the required parameter variation (doping concentration gradient) to achieve high breakdown voltage without additional process steps.
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 increases the breakdown voltage and broadens the application range of high voltage devices while maintaining cost-effectiveness by using common manufacturing process steps with low voltage devices.
Implementation Method 1
the ion implantation process implants N-type impurities to the drift region 16, the drain 15 and the source 14
Data Source
AI summary
The present invention discloses a high voltage device and a manufacturing method thereof. The high voltage device includes: a substrate, having an isolation structure for defining a device region; a drift region located in the device region, wherein from top view, the drift region includes multiple sub-regions separated from one another but are electrically connected with one another; a source and a drain in the device region; and a gate on the surface of the substrate and between the source and drain in the device region.