Semiconductor Device Field Plate Stabilizing Breakdown Voltage
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Solution Overview
Problem
Guard ring structures in semiconductor devices limit the improvement of breakdown voltage due to electric field peaks near the outermost guard ring and require a large area for voltage retention, leading to instability in breakdown voltage.
Innovation Solution
Incorporating a field plate with overlapping portions between the semiconductor substrate and guard ring and channel stopper electrodes, which provides capacitively coupled capacitance to alleviate electric field concentration and stabilize breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If guard rings are provided up to the end of a semiconductor substrate, then breakdown voltage retention is improved, but electric field peak occurs in the central portion causing instability
Solution Approach 1:
A field plate is introduced as an intermediary structure between the guard ring electrode and the semiconductor substrate. The field plate includes a first portion overlapping the guard ring electrode and a second portion overlapping the channel stopper electrode, creating a capacitive coupling that mediates the electric field distribution and prevents peak formation in the central region.
Solution Approach 2:
The field plate extends in the vertical dimension above the substrate surface, creating a three-dimensional electric field distribution. By positioning the field plate at a height above the substrate with insulation layers, the electric field is distributed through an additional spatial dimension, preventing concentration at specific surface points.
2Reliability
If guard ring structure is used to retain breakdown voltage, then voltage retention is improved, but the area required increases
Solution Approach 1:
The field plate utilizes the vertical dimension above the substrate surface to provide additional breakdown voltage retention capability. By extending the electric field management function into the third dimension, the horizontal area requirement on the substrate is reduced while maintaining or improving voltage retention performance.
3Manufacturing precision
If intervals between guard rings are adjusted to maximize electric field peak below outermost guard ring, then electric field control is improved, but breakdown voltage improvement is limited
Solution Approach 1:
The field plate acts as a mediator that decouples the direct relationship between guard ring spacing and electric field peak location. By introducing the capacitive coupling structure, the electric field distribution can be controlled through the field plate's position and dimensions rather than solely through guard ring intervals, enabling better breakdown voltage improvement.
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 effectively stabilizes breakdown voltage by preventing electric field concentration just below the outermost guard ring, allowing for a narrower gap between guard rings and reducing the semiconductor substrate area required for voltage retention.
Implementation Method 1
the field plate can be capacitively coupled to the guard ring electrode and the channel stopper electrode to prevent concentration of electric field just below the guard ring electrode attached to the outermost guard ring
Data Source
AI summary
A semiconductor device includes: a semiconductor substrate having a main surface having an element formation region, a guard ring, a guard ring electrode, a channel stopper region, a channel stopper electrode, and a field plate disposed over and insulated from the semiconductor substrate. The field plate includes a first portion located between the main surface of the semiconductor substrate and the guard ring electrode, and a second portion located between the main surface of the semiconductor substrate and the channel stopper electrode. The first portion has a portion overlapping with the guard ring electrode when viewed in a plan view. The second portion has a portion overlapping with the channel stopper electrode when viewed in the plan view. In this way, a semiconductor device allowing for stabilized breakdown voltage can be obtained.