Transient-Voltage-Suppression Diode with Polycrystalline Plugs
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Solution Overview
Problem
Conventional transient-voltage-suppression diodes face challenges in achieving low breakdown voltage due to difficulties in controlling and increasing the concentration of implant layers through general doping and drive-in procedures, leading to high parasitic resistance and inefficiencies.
Innovation Solution
The use of polycrystalline plugs embedded in the N− type epitaxial layer to reduce the distance of deep implantation and connect the first and deep N+ type implant layers, facilitating improved control over implant concentration and reducing parasitic resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If general doping and drive-in procedure is used, then the manufacturing process is simple, but it is difficult to control and increase the concentration of implant layers
Solution Approach 1:
The patent segments the implantation process by introducing polycrystalline plugs that divide the deep implantation into multiple stages. The plugs are formed at specific depths and serve as intermediate targets for subsequent implantation steps, allowing precise concentration control without requiring a single complex deep implantation process.
Solution Approach 2:
The polycrystalline plugs are formed in advance before the final implantation step. These pre-formed plugs serve as templates or intermediaries that guide the subsequent doping process, enabling better control over the final implant concentration and distribution.
2Manufacturing precision
If the thickness of the N− type epitaxial layer is increased, then the breakdown voltage can be reduced, but the distance of deep implantation increases causing concentration reduction
Solution Approach 1:
The patent segments the thick epitaxial layer into multiple implantation zones using polycrystalline plugs as depth markers. Instead of a single deep implantation that loses concentration, the process uses multiple shallower implantation steps targeted at different plug locations, maintaining high concentration throughout the thick layer.
Solution Approach 2:
The patent introduces a vertical dimension solution by forming polycrystalline plugs at specific depths within the thick epitaxial layer. These plugs create a stepped or multi-level implantation approach, transforming a single deep vertical implantation problem into multiple controlled shallower steps.
3Manufacturing precision
If deep implantation distance is increased, then the breakdown voltage decreases, but parasitic resistance increases
Solution Approach 1:
The patent segments the deep implantation path into multiple shorter segments separated by polycrystalline plugs. Each segment has its own implantation step, ensuring that no single implantation travels too far and loses concentration, thereby maintaining low parasitic resistance while achieving the required breakdown voltage.
Solution Approach 2:
The polycrystalline plugs act as intermediary structures that facilitate the implantation process. They serve as physical markers and concentration reservoirs that mediate between the surface and the deep regions, enabling controlled doping without excessive implantation distances.
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 effectively enhances the performance of transient-voltage-suppression diodes by achieving lower breakdown voltages and reducing manufacturing complexities, thereby improving the overall diode structure's efficiency.
Implementation Method 1
The structure of the polycrystalline plugs is helpful to reduce the distance of deep implantation and avoid the problem of concentration reduction after drive-in procedure
Implementation Method 2
the structure of the plurality of polycrystalline plugs is further helpful to reduce the parasitic resistance of, for example the N− type epitaxial layer
Data Source
AI summary
A transient-voltage-suppression diode structure and a manufacturing method thereof are disclosed. The structure includes a substrate, an N− type epitaxial layer, a first metal layer, a first N+ type implant layer, a deep N+ type implant layer and plural polycrystalline plugs. The N− type epitaxial layer is disposed on the substrate. The first metal layer is disposed on the N− type epitaxial layer to form a working-voltage terminal. The first N+ type implant layer spatially corresponding to the working-voltage terminal and embedded in the N− type epitaxial layer is connected with the working-voltage terminal. The deep N+ type implant layer spatially corresponding to the working-voltage terminal and embedded in the N− type epitaxial layer is spaced apart from the first N+ type implant layer at a separation distance. The plural polycrystalline plugs are connected between the working-voltage terminal of the first metal layer and the deep N+ type implant layer.