Semiconductor Edge Termination with Diffluent Insulation Layer
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Solution Overview
Problem
Existing edge termination structures in semiconductor devices face challenges in minimizing space while maintaining blocking capabilities and reducing the influence of surface charges and external electrical fields, with field-plates causing field peaks due to sharp edges, which are difficult to manufacture and partially reduce field strength.
Innovation Solution
A method involving the formation of an insulation layer with a laterally varying thickness by creating recesses and openings at varying pitches and widths, followed by tempering to achieve a diffluent state, which allows for a continuous layer with an inclined surface, reducing sharp edges and field peaks, and enabling a single field-plate to suffice for high blocking voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If field-plates with sharp edges are used to reduce electrical field, then field strength is reduced, but field peaks occur in the semiconductor material and dielectric layer
Solution Approach 1:
The patent applies curvature by forming the field-plate with a rounded or curved leading edge instead of a sharp edge. This curvature distributes the electrical field more evenly, reducing field peaks while maintaining the field strength reduction effect. The curved geometry eliminates the concentration of electric field lines at sharp corners, thereby resolving the contradiction between reducing field strength and avoiding field peaks.
Solution Approach 2:
The patent changes the geometric parameters of the field-plate, specifically the edge radius and profile shape. By optimizing these parameters, the field-plate achieves both field strength reduction and elimination of field peaks. The parameter optimization includes adjusting the curvature radius, thickness, and lateral dimensions to balance the electrical field distribution.
2Object-affected harmful factors
If field-plates with optimized geometry are used to avoid field peaks, then field peaks are avoided, but manufacturing becomes difficult
Solution Approach 1:
The patent segments the field-plate formation into multiple manufacturing steps: first forming a preliminary field-plate structure with standard photolithography, then applying an additional curving process to create the optimized geometry. This segmentation allows the complex curved shape to be achieved through simpler, more manufacturable steps rather than requiring direct formation of the final complex geometry in a single step.
Solution Approach 2:
The patent performs preliminary formation of the field-plate structure before applying the curving process. The preliminary field-plate is formed using standard photolithography and deposition techniques, and then the curving process is applied to achieve the optimized geometry. This preliminary action simplifies manufacturing by separating the formation of the basic structure from the geometry optimization.
3Strength
If multiple steps are used to reduce field strength, then field strength is partially reduced, but field peaks remain in the dielectric layer and long term problems persist
Solution Approach 1:
The patent uses a curved field-plate geometry that completely eliminates field peaks in the dielectric layer, not just partially reduces them. The continuous curvature ensures smooth field distribution throughout the structure, preventing long term reliability issues associated with field peaks such as dielectric breakdown and charge accumulation.
4Strength
If multiple photolithographic steps are used to manufacture field-plates with multiple steps, then field strength is reduced, but the number of lithographical steps increases
Solution Approach 1:
The patent segments the field-plate formation process into a standard photolithography step for basic pattern definition and a separate curving process for geometry optimization. This segmentation allows the use of standard photolithography equipment and processes while achieving the complex curved geometry, thereby reducing the number of lithographical steps required.
Solution Approach 2:
The patent introduces an intermediary curving process that transforms the preliminary field-plate structure into the final optimized geometry. This intermediary process acts as a bridge between the simple photolithography-formed structure and the complex curved field-plate, achieving the desired field strength reduction without requiring multiple complex lithographical steps.
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 reduces the maximum lateral extension of the edge termination structure, improves blocking characteristics by minimizing dielectric breakdown likelihood, and decreases the number of required field-plates, while also simplifying the manufacturing process by reducing the number of lithographical steps.
Implementation Method 1
tempering the insulation layer having the plurality of the at least one of the recesses and openings at elevated temperatures so that the insulation layer at least partially diffluences to provide the insulation layer with a laterally varying thickness
Data Source
AI summary
According to one embodiment of a semiconductor device, the semiconductor device includes a semiconductor substrate having a first surface, an insulation layer having a laterally varying thickness on the first surface, and a metal layer on the first surface. The insulation layer has ripples in its surface facing the metal layer. According to another embodiment of a semiconductor device, the semiconductor device includes a semiconductor substrate having a first surface and including at least one of a laterally varying thickness and an inclined first surface. The first surface of the semiconductor substrate has ripples.