Power Diode Trench Field Ring Structure for Contamination Control
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Solution Overview
Problem
Existing power semiconductor components face challenges in avoiding contamination during deep dopant diffusion processes, which can lead to long diffusion times and risks of heavy metal contamination in the diffusion region.
Innovation Solution
A power semiconductor component with a field ring structure featuring trench-shaped recesses and ion implantation to create concentric doping profiles, reducing contamination risks and diffusion times, while forming a pn junction and field rings in a more efficient and controlled manner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If deep diffusion of dopant is used to form field rings, then the field ring structure is created, but diffusion times become long and contamination risk increases
Solution Approach 1:
Trenches are formed in the semiconductor substrate before dopant diffusion. This preliminary structural preparation allows the dopant to be confined within the trench regions, enabling faster and more controlled diffusion while preventing contamination spread to surrounding areas. The trenches act as pre-defined pathways that guide the diffusion process.
Solution Approach 2:
The trench structure serves as an intermediary element between the dopant source and the bulk semiconductor material. By introducing this intermediate structural feature, the diffusion process is mediated and controlled - the dopant diffuses along the trench walls rather than through the entire substrate depth, reducing diffusion time and limiting contamination exposure.
2Reliability
If deep diffusion of dopant is used to form field rings, then the field ring structure is created, but contamination risk from heavy metals increases
Solution Approach 1:
The dopant diffusion process is extracted from the bulk substrate environment and confined to the trench regions. By separating the diffusion zone from the surrounding substrate, the risk of heavy metal contamination is localized and contained within the trench structures, preventing spread to other critical areas of the semiconductor device.
Solution Approach 2:
The trench structure creates localized diffusion zones with distinct properties from the surrounding substrate. The dopant concentration and diffusion characteristics are locally optimized within each trench, while the surrounding areas remain protected from contamination. This local quality approach allows controlled doping without exposing the entire device to contamination risks.
3Reliability
If conventional diffusion process is used, then field rings are formed, but mask steps and processing complexity increase
Solution Approach 1:
The field ring structure is segmented into discrete trench regions rather than being formed as continuous concentric rings through multiple mask steps. Each trench is independently formed and doped, simplifying the overall process. The segmentation approach eliminates the need for complex alignment and multiple masking operations while maintaining the functional field ring structure.
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 solution enables a faster and cleaner doping process, minimizing contamination risks and maintaining the electrical properties of the semiconductor component, with improved dielectric strength and reduced processing time.
Implementation Method 1
Generation of the first and second doping profile of the second doping starting from the first surface in the region of the trenches and thus formation of the field ring structure; this production is advantageously carried out by means of ion implantation
Implementation Method 2
it is known to produce these field rings by a diffusion process, with a dopant being applied to the surface in a masked manner and then being diffused into the semiconductor body by the action of temperature
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention describes a power semiconductor device and an associated manufacturing process comprising a semiconductor substrate with a first doping. In this substrate (2, 4) with first doping, a pn junction is formed by means of a contact area (12) with a second doping profile (120). Likewise, a field ring structure (14) with a second doping profile (140) of the respective field ring is arranged. Here, the contact area and the field ring structure are arranged on respective first and second sub-surfaces (10a, 10b) of a first surface of the substrate. Both extend into the volume of the substrate, the substrate having a trench-shaped recess (142) for the field ring structure, the surface of which substantially follows the contour of the associated doping profile.