Schottky Diode Impurity Profile for Leakage Reduction
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Solution Overview
Problem
Conventional built-in Schottky barrier diodes in semiconductor devices suffer from increased recovery loss and leakage current due to insufficient depletion layer extension and high electric field intensity, leading to reliability issues and increased chip costs.
Innovation Solution
A semiconductor device design with a first region under the Schottky electrode having an impurity concentration higher than the drift layer but lower than the well region, optimizing impurity concentration profiles to enhance unipolar current density and reduce leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the impurity concentration of the first conductivity type in the region under the Schottky electrode is increased to increase unipolar current density, then the unipolar current density is improved, but the depletion layer extension is insufficient and leakage current increases
Solution Approach 1:
The patent applies local quality by creating distinct impurity concentration zones: a first region with higher impurity concentration under the Schottky electrode to enhance unipolar current density, and a second region with lower impurity concentration between the first region and the well region to ensure sufficient depletion layer extension and reduce leakage current. This spatial differentiation of impurity concentrations allows simultaneous optimization of both unipolar current density and leakage current suppression.
Solution Approach 2:
The patent changes the impurity concentration parameter across different regions. Specifically, the impurity concentration in the first region is set higher than in the drift layer to increase unipolar current density, while the impurity concentration in the second region is set lower to ensure proper depletion layer extension. This parameter variation resolves the contradiction between enhancing unipolar current and suppressing leakage current.
2Productivity
If the impurity concentration is increased to enhance unipolar current, then the unipolar current component is improved, but the electric field intensity increases causing reliability deterioration
Solution Approach 1:
The patent implements local quality by establishing a second region with lower impurity concentration that acts as a buffer zone. This region reduces the electric field intensity by ensuring sufficient depletion layer extension, while the first region with higher impurity concentration maintains high unipolar current. The spatial separation of these quality zones resolves the contradiction between enhancing unipolar current and controlling electric field intensity.
3Productivity
If the impurity concentration profile is optimized to increase unipolar current density, then the reflux diode performance is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent simplifies the manufacturing process by dividing the impurity concentration optimization into two distinct local regions with clearly defined concentration relationships. The first region has higher impurity concentration than the drift layer, and the second region has lower impurity concentration than the first region. This binary regional approach makes the manufacturing process more manageable compared to continuous gradient profiles, while still achieving the desired unipolar current density enhancement.
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 increases unipolar current density while preventing leakage current, thereby enhancing the reliability and reducing chip costs by optimizing impurity concentration profiles.
Implementation Method 1
there is proposed a method of building in and utilizing a Schottky barrier diode as a reflux diode
Implementation Method 2
a depletion layer is sufficiently extended to a lower part of the Schottky electrode and an electric field intensity to be applied to a Schottky barrier junction is raised
Data Source
AI summary
In a semiconductor device having a built-in Schottky barrier diode as a reflux diode, a maximum unipolar current is increased in a reflux state and a leakage current is reduced in an OFF state. A Schottky electrode is provided in at least a part of a surface between adjacent well regions of a second conductivity type disposed on a surface layer side of a drift layer of a first conductivity type, and an impurity concentration of a first conductivity type in a first region provided in a lower part of the Schottky electrode and provided between the adjacent well regions is set to be higher than a first impurity concentration of a first conductivity type in the drift layer and to be lower than a second impurity concentration of a second conductivity type in the well region.