Semiconductor Device Drain Region Breakdown Voltage
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Solution Overview
Problem
High-breakdown-voltage field effect transistors require a large number of manufacturing processes and a significant element area to create electric field relaxation and breakdown voltage structures.
Innovation Solution
A semiconductor device with a field effect transistor featuring a drain region structure comprising a high-concentration layer, a low-concentration layer, and another high-concentration layer connected in series, which increases the resistance and breakdown voltage while minimizing the number of processes and element area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electric field relaxation structure and breakdown voltage structure are created in high-breakdown-voltage field effect transistor, then breakdown voltage is improved, but the number of manufacturing processes increases and element area increases
Solution Approach 1:
The patent merges the breakdown voltage structure creation into the existing well diffusion process. The low-concentration layer is formed as part of the well diffusion layer, and the high-concentration layers are integrated with the source/drain region formation processes. This combining of multiple functions into existing processes eliminates the need for separate breakdown voltage structure manufacturing steps, thereby improving breakdown voltage without increasing the number of manufacturing processes.
Solution Approach 2:
The well diffusion layer serves multiple functions: it provides the base doping for the drain region, creates the low-concentration layer for breakdown voltage enhancement, and integrates with the overall device structure. By making the well diffusion layer multi-functional, the patent achieves breakdown voltage improvement without requiring dedicated separate processes for creating relaxation structures.
2Reliability
If electric field relaxation structure and breakdown voltage structure are created in high-breakdown-voltage field effect transistor, then breakdown voltage is improved, but element area increases
Solution Approach 1:
The patent applies local quality by creating a low-concentration layer specifically in the drain region where breakdown voltage enhancement is needed, while maintaining high-concentration layers in the source region and at the drain electrode interface. This localized doping strategy enhances breakdown voltage at critical points without requiring uniform area expansion across the entire device structure.
Solution Approach 2:
The patent utilizes vertical dimensionality by creating a multi-layered doping structure in the drain region with different concentration levels at different depths. The low-concentration layer is positioned between the semiconductor region and the high-concentration layer near the drain electrode, creating a vertical concentration gradient that enhances breakdown voltage without requiring lateral area expansion.
3Reliability
If low-concentration layer is added to drain region, then resistance of drain region increases and breakdown voltage increases, but process complexity may increase
Solution Approach 1:
The low-concentration layer is formed preliminarily during the well diffusion process, before subsequent high-concentration doping steps. By establishing the low-concentration base layer in advance, the patent enables subsequent high-concentration layer formation without requiring additional dedicated processes for breakdown voltage enhancement, thereby reducing overall process complexity.
Solution Approach 2:
The well diffusion process serves itself by simultaneously creating the low-concentration layer and providing the foundation for high-concentration layer formation. The process structure is designed so that each doping step naturally builds upon the previous layer, with the low-concentration layer automatically serving as the base for subsequent high-concentration doping, eliminating the need for separate breakdown voltage structure creation processes.
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 semiconductor device effectively increases breakdown voltage without increasing the number of manufacturing processes or element area, enhancing the performance of field effect transistors.
Implementation Method 1
providing the low-concentration layer can increase the resistance of the drain region, and can increase the breakdown voltage between the source and the drain
Data Source
AI summary
Provided is a semiconductor device capable of increasing the breakdown voltage of a field effect transistor while suppressing an increase in the number of processes. The semiconductor device includes a semiconductor substrate and a field effect transistor provided on a first main surface side of the semiconductor substrate. The field effect transistor includes a semiconductor region where a channel is formed, a source region of a first conductivity type located on one side in a gate length direction of the semiconductor region, a drain region of the first conductivity type located on the other side in the gate length direction, and a drain electrode connected to the drain region. The drain region includes a structure in which a first high-concentration layer having a high impurity concentration of the first conductivity type, a low-concentration layer having a low impurity concentration of the first conductivity type, and a second high-concentration layer having a high impurity concentration of the first conductivity type are connected in this order from the semiconductor region to the drain electrode side.