Schottky Diode Field Plate Structure for Breakdown Voltage
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Solution Overview
Problem
Schottky diode devices suffer from low reverse breakdown voltage due to the planar structure and metal spiking issues, which are not effectively addressed by existing solutions like diffused guard rings or extended metal flaps, complicating manufacturing and impacting performance.
Innovation Solution
A Schottky diode structure with a conductive plate and oversized contact openings is introduced, reducing electric field concentrations and avoiding metal spiking by separating the metal layer from the substrate with insulating layers, eliminating the need for diffused guard rings and parasitic bipolar transistor activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a planar Schottky diode structure is used, then the device is simple to manufacture, but the reverse breakdown voltage is low due to electric field concentration at corners
Solution Approach 1:
The patent introduces a three-dimensional field plate structure extending from the metal contact through dielectric layers, adding vertical and lateral dimensions to the traditional planar structure. This dimensional extension allows the electric field to be managed in multiple directions, reducing concentration at corners while maintaining manufacturing feasibility through standard semiconductor processing layers
2Reliability
If diffused guard rings are used to improve reverse breakdown voltage, then the breakdown voltage increases, but the device processing becomes complicated
Solution Approach 1:
The patent extracts the field management function from the traditional diffused guard ring approach and implements it through a separate field plate structure composed of metal contact, dielectric layers, and conductive plugs. This separation allows the Schottky junction and field control to be independently optimized while using standard processing techniques already present in CMOS fabrication
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 configuration enhances reverse breakdown voltage and overall performance while simplifying integration into existing IC processes, being cost-effective and compatible with CMOS and bipolar flows.
Implementation Method 1
the concentration of electric field lines increases near corners of the devices, which detrimentally impacts the abruptness of the reverse breakdown voltage
Implementation Method 2
Aluminum forms a blocking contact with n-type silicon if the n-type doping is sufficiently low enough to prevent tunneling electrons from penetrating the barrier
Data Source
AI summary
In one embodiment, a Schottky diode structure comprises a Schottky barrier layer in contact with a semiconductor material through a Schottky contact opening. A conductive ring is formed adjacent the Schottky contact opening and is separated from the semiconductor material by a thin insulating layer. Another insulating layer is formed overlying the structure, and a contact opening is formed therein. The contact opening is wider than the Schottky contact opening and exposes portions of the conductive ring. A Schottky barrier metal is formed in contact with the semiconductor material through the Schottky contact opening, and is formed in further+contact with the conductive ring.