Semiconductor Device Field Plate Leak Current Suppression
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Solution Overview
Problem
Schottky barrier diodes with field plate structures experience reduced breakdown voltage due to diffusion of low-work-function wiring materials into the semiconductor layer, leading to increased leak current, especially under high-temperature conditions or long-term use.
Innovation Solution
A semiconductor device design featuring a semiconductor layer with an insulating layer and a first electrode layer forming a field plate structure, where the distance between the first electrode layer and a second electrode layer is set to at least 0.2 μm, and the first electrode layer has a work function greater than 0.5 eV relative to the semiconductor's electron affinity, along with a third electrode layer to prevent metal diffusion, effectively suppressing leak current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a thick wiring layer with low resistivity metal (Al or Cu) is formed on the Schottky electrode to serve as pad electrode, then electrical conductivity is improved, but the breakdown voltage decreases due to material diffusion into the semiconductor layer
Solution Approach 1:
A barrier metal layer is introduced as an intermediary between the Schottky electrode and the wiring layer. This barrier layer prevents diffusion of the wiring layer material into the Schottky electrode and semiconductor layer, while maintaining electrical conductivity. The barrier layer thus mediates between the conflicting requirements of low resistivity and high breakdown voltage.
Solution Approach 2:
The barrier metal layer is formed in advance before the wiring layer, creating a protective interface that prevents future diffusion issues. This preliminary protective action ensures that even when the wiring layer is subsequently formed with thick low-resistivity metal, the breakdown voltage is preserved by preventing material interdiffusion during device operation.
2Reliability
If the Schottky electrode is extended to the surface of the insulating layer to form a field plate structure, then breakdown voltage is improved, but leak current increases due to thinner film thickness at the side face
Solution Approach 1:
The barrier metal layer serves as a protective intermediary that covers the side face of the Schottky electrode where the film thickness is reduced. This prevents wiring layer material from diffusing through the thinner region, thereby suppressing leak current while maintaining the field plate structure's breakdown voltage enhancement.
Solution Approach 2:
The barrier metal layer is specifically positioned at the critical region where the Schottky electrode contacts the insulating layer side face. This localized protection addresses the specific problem area of thin film thickness without altering the overall field plate structure, maintaining both breakdown voltage and suppressing leak current.
3Reliability
If the distance between the first electrode layer and second electrode layer is increased to prevent material diffusion, then reliability is improved, but device size increases
Solution Approach 1:
The barrier metal layer acts as a diffusion barrier that enables maintaining a small distance between the Schottky electrode and wiring layer. By preventing material interdiffusion through this intermediary layer, the device can achieve high reliability without increasing the spacing between electrodes, thus avoiding device size enlargement.
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 design effectively suppresses the increase in leak current and maintains breakdown voltage by preventing material diffusion and ensuring uniform film thickness, enhancing the semiconductor device's durability and usability.
Implementation Method 1
a first electrode layer formed on the semiconductor layer, configured to have a work function of not less than 0.5 eV relative to electron affinity of the semiconductor layer
Implementation Method 2
an insulating layer configured to have electric insulation property and formed to cover part of the semiconductor layer
Implementation Method 3
a barrier metal layer formed on the Schottky electrode... suppresses the material of the wiring layer from being diffused in the Schottky electrode
Data Source
AI summary
A technique of suppressing leak current in a semiconductor device is provided. A semiconductor device, comprises: a semiconductor layer made of a semiconductor; an insulating layer configured to have electric insulation property and formed to cover part of the semiconductor layer; a first electrode layer formed on the semiconductor layer, configured to have a work function of not less than 0.5 eV relative to electron affinity of the semiconductor layer and extended to surface of the insulating layer to form a field plate structure; and a second electrode layer configured to have electrical conductivity and formed to cover at least part of the first electrode layer. A distance between an edge of a part of the first electrode layer that is in contact with the semiconductor layer and the second electrode layer is equal to or greater than 0.2 μm.