Semiconductor Device Current Path Modification for Breakdown Voltage
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Solution Overview
Problem
Existing semiconductor devices face challenges in achieving uniform electrical characteristics and maximizing breakdown voltage and resistance, particularly in high voltage applications such as display driving technologies, where uniformity of terminals directly affects image quality.
Innovation Solution
The method involves forming a semiconductor device with a semiconductor substrate, an epi layer, a current path changing part, and a gate electrode, where the current path changing trench is formed within the epi layer to alter the current path between the source and drain regions, minimizing on-resistance and maximizing breakdown voltage by using a dummy trench and align trench structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a shallow trench isolation (STI) structure is used to form a field-plate-on-oxide structure, then breakdown voltage is maximized, but on-resistance increases due to extended current path
Solution Approach 1:
The patent divides the current path modification into two distinct segments: a first current path changing part formed in the drift region and a second current path changing part formed in the epi layer. This segmentation allows the current path to be shortened in the vertical direction (reducing on-resistance) while maintaining the field plate structure for breakdown voltage enhancement.
Solution Approach 2:
The patent introduces a vertical dimension element by forming the second current path changing part in the epi layer at a different depth level than the first current path changing part in the drift region. This three-dimensional arrangement allows the current path to fold back vertically, shortening the effective current path length while maintaining lateral coverage for field protection.
2Reliability
If additional processes are required to form field-plate-on-oxide structure, then manufacturing complexity increases, but breakdown voltage characteristics are improved
Solution Approach 1:
The patent combines the formation of current path changing parts with the existing field plate and epi layer structures. The dummy trench formation is integrated into the same fabrication sequence as the field plate formation, allowing multiple functions (field protection and current path modification) to be achieved through a unified process flow rather than separate additional steps.
Solution Approach 2:
The epi layer serves multiple functions: it provides the substrate for the second current path changing part, acts as an isolation layer, and maintains the field plate structure. The dummy trench structure simultaneously serves as a mask for implantation and defines the geometry of the current path changing part, reducing the need for separate dedicated process steps.
3Reliability
If uniform electrical characteristics are achieved across all terminals, then image uniformity is improved, but fabrication precision requirements increase
Solution Approach 1:
The patent applies local quality modification by forming current path changing parts at specific locations within the drift region and epi layer, rather than uniformly across all terminals. The dummy trench pattern is strategically placed to modify current paths in regions where it most effectively promotes uniformity, allowing selective optimization without requiring perfect precision across the entire wafer.
Solution Approach 2:
The dummy trench structure is formed preliminarily before final device fabrication, establishing a template that guides subsequent implantation and defines current path geometry. This preliminary structuring ensures that all subsequent processing steps are aligned to the same reference framework, reducing cumulative alignment errors and improving terminal-to-terminal uniformity.
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 efficiently fabricates semiconductor devices with minimized current path resistance and maximized breakdown voltage, ensuring uniform electrical characteristics and improved image quality in high voltage applications.
Implementation Method 1
forming an epi layer over a top surface of the semiconductor substrate
Data Source
AI summary
A semiconductor device and a method of fabricating the semiconductor device is provided. In the method, a semiconductor substrate defining a device region and an outer region at a periphery of the device region is provided, an align trench is formed in the outer region, a dummy trench is formed in the device region, an epi layer is formed over a top surface of the semiconductor substrate and within the dummy trench, a current path changing part is formed over the epi layer, and a gate electrode is formed over the current path changing part. When the epi layer is formed, a current path changing trench corresponding to the dummy trench is formed over the epi layer, and the current path changing part is formed within the current path changing trench.