Trench Gate Semiconductor Junction Edge Termination
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Solution Overview
Problem
Existing semiconductor devices face challenges in reducing on-resistance and improving breakdown voltage reliability while maintaining low manufacturing costs, particularly in trench gate-type power ICs, where the breakdown voltage is susceptible to reduction due to electric field concentration and external charge influences.
Innovation Solution
The semiconductor device incorporates a vertical trench MOS gate-type semiconductor element with a junction edge termination region featuring a p− diffusion region with low impurity concentration and a sustain region, both formed without additional manufacturing processes, to enhance breakdown voltage and reduce on-resistance, along with a field plate on the insulating film to manage external charges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a p− diffusion region with low impurity concentration is provided in the junction edge termination region, then the breakdown voltage increases, but the manufacturing complexity increases due to additional diffusion processes
Solution Approach 1:
The patent combines the formation of the p− diffusion region in the junction edge termination region with the existing p-type base region formation process. By using a single diffusion step that simultaneously creates both regions with appropriate concentration gradients, the manufacturing complexity is reduced while still achieving the desired breakdown voltage enhancement through extended depletion layer formation.
Solution Approach 2:
The patent applies local quality by creating a p− diffusion region with specifically controlled low impurity concentration in the junction edge termination region, while maintaining higher concentration in the active p-type base region. This localized concentration gradient optimizes the breakdown characteristics at the termination region without compromising the overall device performance.
2Reliability
If the depletion layer is extended from the active region to the junction edge termination region, then the maximum field intensity is reduced and breakdown voltage increases, but the device area increases
Solution Approach 1:
The patent transitions from a planar depletion layer extension to a three-dimensional depletion structure by forming a p− diffusion region that extends vertically and laterally in the junction edge termination region. This dimensional approach allows the depletion layer to extend effectively in multiple directions, reducing maximum field intensity without proportionally increasing the surface area of the device.
Solution Approach 2:
The p− diffusion region is nested within the junction edge termination region structure, creating a concentrated depletion zone that efficiently extends the depletion layer effect. This nested configuration allows maximum field intensity reduction within a compact footprint, avoiding proportional area increase while achieving enhanced breakdown voltage.
3Reliability
If a complex semiconductor device with protective semiconductor element is formed, then the breakdown voltage reliability improves, but the manufacturing cost increases
Solution Approach 1:
The patent merges the protective function into the existing semiconductor device structure by forming a p− diffusion region in the junction edge termination region of the vertical trench MOS gate-type semiconductor element. This integration eliminates the need for separate protective semiconductor elements while achieving enhanced breakdown voltage reliability, thereby reducing manufacturing costs.
Solution Approach 2:
The p− diffusion region in the junction edge termination region serves multiple functions simultaneously: it extends the depletion layer to reduce maximum field intensity, increases breakdown voltage, and provides protective functionality. This multi-functionality eliminates the need for additional dedicated protective structures, reducing overall device complexity and manufacturing cost.
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 increases the breakdown voltage reliability and reduces on-resistance without increasing manufacturing costs, by distributing the electric field and minimizing the impact of external charges, thereby preventing device destruction from avalanche breakdown.
Implementation Method 1
a depletion layer is likely to be extended from the active region 68 to the junction edge termination region 69 when an off voltage is applied. Therefore, the maximum field intensity of the junction edge termination region 69 is sufficiently reduced and the breakdown voltage of the junction edge termination region 69 increases.
Implementation Method 2
the breakdown voltage of a junction edge termination region 69 needs to be higher than that of an active region 68 such that a current caused by avalanche breakdown flows to the active region 68.
Implementation Method 3
the breakdown voltage is susceptible to reduction due to electric field concentration and external charge influences
Data Source
AI summary
A semiconductor device includes a vertical trench gate element portion and a lateral n-channel element portion for control which includes a well diffusion region, and a junction edge termination region which surrounds the vertical trench gate element portion and the lateral n-channel element portion for control. The junction edge termination region includes an oxide layer, a sustain region in contact with a trench provided at the end, and a diffusion region in contact with the sustain region. The diffusion region is deeper than the base region and has low concentration. The sustain region is shallower than the diffusion region and has high concentration. The well diffusion region is deeper than the base region and the sustain region and has low concentration. The breakdown voltage of the junction edge termination region and the well diffusion region is higher than that of the vertical trench gate element portion.