Trench-Gate MISFET Structure for Higher Withstand Voltage
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Solution Overview
Problem
Existing semiconductor devices with trench gate structures face challenges in maintaining high withstand voltage due to electric field concentration and punch-through issues, which affect the reliability and performance of common source/drain type MISFETs.
Innovation Solution
The semiconductor device incorporates a trench gate structure with a high concentration channel region and a p-type base region, where the high concentration channel region prevents depletion layer overlap and punch-through, and the p-type base region has a concentration gradient to reduce electric field strength between the gate electrode and source/drain regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a trench gate structure is used in a common source/drain type MISFET, then the device integration is improved, but electric field concentration occurs between the gate electrode and source/drain regions, reducing withstand voltage
Solution Approach 1:
The patent applies local quality by creating a concentration gradient in the p-type base region, where the impurity concentration varies from the main surface toward the deep interior. This gradient structure locally modifies the electric field distribution, reducing field concentration at critical interfaces while maintaining the trench gate configuration for device integration.
Solution Approach 2:
The patent changes the impurity concentration parameter of the p-type base region by forming a concentration gradient. This parameter modification alters the electric field distribution characteristics, enabling the device to maintain high integration with trench gates while improving withstand voltage through reduced electric field concentration.
2Ease of manufacture
If the trench gate structure is formed with standard configuration, then manufacturing is simplified, but punch-through occurs between drift regions, affecting device reliability
Solution Approach 1:
The patent applies local quality by forming a high concentration channel region at specific locations within the p-type base region. This localized high concentration zone prevents punch-through between drift regions while maintaining the overall simplicity of the trench gate structure, thus preserving ease of manufacture while improving reliability.
Solution Approach 2:
The patent applies preliminary action by pre-forming the concentration gradient in the p-type base region before final device operation. This preliminary structural preparation ensures that punch-through is prevented from occurring in the first place, while the trench gate structure remains relatively simple to manufacture.
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 configuration effectively suppresses electric field concentration and punch-through, thereby enhancing the withstand voltage and reliability of the semiconductor device.
Implementation Method 1
the high concentration channel region prevents depletion layer overlap and punch-through
Implementation Method 2
reduce electric field strength generated between the gate electrode and source/drain regions
Data Source
AI summary
A semiconductor device includes a semiconductor layer that has a main surface, a trench gate structure that includes a trench formed in the main surface and having a first sidewall at one side, a second sidewall at the other side and a bottom wall in a cross-sectional view, an insulation layer formed on an inner wall of the trench, and a gate electrode embedded in the trench with the insulation layer between the trench and the gate electrode and having an upper end portion positioned at a bottom-wall side with respect to the main surface, a plurality of first-conductivity-type drift regions that are respectively formed in a region at the first sidewall side of the trench and in a region at the second sidewall side of the trench such as to face each other with the trench interposed therebetween in a surface layer portion of the main surface and that are positioned in a region at the main surface side with respect to the bottom wall, and a plurality of first-conductivity-type source/drain regions that are formed in surface layer portions of the plurality of drift regions, respectively.