High-Voltage Transistor Drift Region Layout for Higher Breakdown Voltage
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Solution Overview
Problem
Existing methods to increase the breakdown voltage of high voltage transistors often alter the pitch, which is undesirable.
Innovation Solution
A method to fabricate high voltage transistors by reducing dopant concentration in part of the drain drift region, using a photo mask with a comb-liked pattern to define the drain drift region, and diffusing dopants to form the drain drift region without changing the pitch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the edge of the drain drift region is adjusted to increase breakdown voltage, then the breakdown voltage is improved, but the pitch of the high resistance transistor changes
Solution Approach 1:
The patent applies local quality by creating a non-uniform dopant concentration distribution within the drain drift region. Specifically, the dopant concentration is reduced in a first region compared to a second region, allowing different parts of the same region to have different electrical properties. This enables breakdown voltage enhancement through localized dopant concentration modification without requiring changes to the overall pitch dimension
Solution Approach 2:
The patent changes the dopant concentration parameter within the drain drift region to achieve the desired breakdown voltage improvement. By reducing dopant concentration in the first region relative to the second region, the electrical characteristics are modified locally, enabling breakdown voltage enhancement while maintaining the original pitch
2Reliability
If dopant concentration is reduced in the drain drift region to increase breakdown voltage, then the breakdown voltage is improved, but the on-resistance may increase
Solution Approach 1:
The patent applies local quality by spatially differentiating the dopant concentration within the drain drift region. The first region has reduced dopant concentration to enhance breakdown voltage, while the second region maintains higher dopant concentration to preserve low on-resistance. This localized differentiation allows simultaneous optimization of both breakdown voltage and on-resistance characteristics
Solution Approach 2:
The patent segments the drain drift region into distinct first and second regions with different dopant concentration levels. This segmentation enables independent optimization of each region's electrical properties - the first region for breakdown voltage enhancement and the second region for maintaining low on-resistance, thereby resolving the trade-off between these two parameters
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
Increases breakdown voltage without altering the pitch, thereby improving the working stability and efficiency of the power supply circuit.
Implementation Method 1
An ion implantation process is performed to implant dopants into the drain drift predetermined region
Implementation Method 2
dopants in the drain drift predetermined region are diffused to form the drain drift region
Data Source
AI summary
A fabricating method of a high voltage transistor includes providing a high voltage transistor. The high voltage transistor includes a substrate. A gate structure is disposed on the substrate. A source drift region and a drain drift region are respectively disposed at two sides of the gate structure and embedded within the substrate. A source is disposed in the source drift region. A drain is disposed within the drain drift region. The steps of fabricating the drain drift region include defining a drain drift region predetermined region on the substrate by using a photo mask. The photo mask includes a first comb-liked pattern. The first comb-liked pattern includes a first rectangle and numerous first tooth structures. Then, an ion implantation process is performed to implant dopants into the drain drift region predetermined region. Then, dopants in the drain drift region predetermined region are diffused to form the drain drift region.