Termination Arrangement for Vertical MOSFET Trench Field Management
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Transistor structures face issues with high electric field concentrations at trench corners, leading to carrier injection into insulating regions, which can cause trapped electric charge accumulation, affecting breakdown voltage, on-resistance, and device lifetime.
Innovation Solution
A deep body region is implanted in the termination region, electrically connected to the active region, to modify the electric field distribution and reduce hole current paths to the semiconductor-insulator interface, along with a field plate structure over the gate insulator/field insulator step, and other termination arrangements to steer currents and minimize field intensity across insulating regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If trenches are used in the termination region, then device structure is improved for voltage blocking, but high electric field concentration occurs at trench corners causing carrier injection into insulating regions
Solution Approach 1:
The patent applies local quality by creating a deep body region with different doping characteristics specifically at the trench corners where high electric field concentration occurs. This localized modification changes the electrical properties only in the critical high-field regions while maintaining the overall trench structure for voltage blocking, thereby reducing carrier injection at problem areas without compromising the voltage blocking capability.
Solution Approach 2:
The deep body region is formed prior to final device operation to preemptively address the electric field concentration issue. By establishing the deep body structure in advance, the patent prevents carrier injection into insulating regions before it can occur during device operation, thereby eliminating the harmful effect at its source.
2Reliability
If carriers are injected into insulating regions, then breakdown voltage is affected, but device lifetime is reduced due to trapped charge accumulation
Solution Approach 1:
The patent converts the potentially harmful effect of high electric fields at trench corners into a beneficial outcome by using the deep body region to control and redirect the electric field distribution. The deep body structure guides the high-field regions away from insulating regions and toward the deep body itself, where carriers are safely handled. This transforms what would be a harmful carrier injection mechanism into a controlled field distribution pattern that protects both breakdown voltage stability and device lifetime.
3Ease of manufacture
If termination region structure is simplified, then manufacturing is easier, but electric field distribution cannot be optimized to reduce carrier injection
Solution Approach 1:
The patent merges the formation of the deep body region with the existing termination region fabrication process. The deep body is created as an integrated part of the termination structure through coordinated doping steps that combine with standard trench formation and insulator deposition processes. This merging approach allows the complex electric field optimization to be achieved without adding separate, complex manufacturing steps, thereby maintaining ease of manufacture while eliminating carrier injection issues.
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 approach increases breakdown voltage, reduces electric field intensity across insulating regions, improves current distribution, and extends device lifetime by minimizing carrier injection and trapping, resulting in enhanced stability and robustness.
Implementation Method 1
A deep body region is implanted in the termination region, electrically connected to the active region, to modify the electric field distribution
Implementation Method 2
Once the electric field reaches a critical level, impact ionization of the transistor materials in the high field region can generate large quantities of carriers, leading to avalanche breakdown of the device
Data Source
AI summary
Representative implementations of devices and techniques provide a termination arrangement for a transistor structure. The periphery of a transistor structure may include a recessed area having features arranged to improve performance of the transistor at or near breakdown.