High-Voltage Transistor Drain Drift 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 of the transistors, 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 transistor 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 portion of the drain drift region while maintaining higher concentration in other portions. This localized modification increases the breakdown voltage at critical regions without requiring a change in the overall transistor pitch, thereby resolving the technical contradiction between improving reliability and maintaining dimensional constraints.
2Reliability
If the dopant concentration is reduced in part of the drain drift region, then the breakdown voltage is increased, but the manufacturing process complexity increases
Solution Approach 1:
The patent employs segmentation by dividing the drain drift region into multiple portions with different dopant concentrations. A photo mask with a comb-like pattern is used to define these different regions, allowing selective dopant implantation or diffusion. This segmentation approach enables precise control over the dopant concentration distribution, achieving the desired breakdown voltage enhancement while managing fabrication complexity through systematic region definition.
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 method increases breakdown voltage without altering the pitch, thereby improving the working stability and efficiency of high voltage transistors.
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.