Semiconductor Device Si Nodule Reduction via Graded Al Alloy Cathode
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Solution Overview
Problem
Conventional semiconductor devices with a pattern of n-type and p-type cathode layers on the back surface using Al alloy back electrodes experience increased on-voltage due to Si nodules imparting p-type properties on the n-type cathode layer, primarily affecting the n-layer.
Innovation Solution
A semiconductor device design featuring a first Al alloy layer on the n-type cathode layer with an impurity concentration of 1E19 cm−3 and a second Al alloy layer on the p-type cathode layer with an impurity concentration 10% lower than the n-type layer, both containing Si, to reduce on-voltage by minimizing Si nodules formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Si is contained in the Al alloy back electrode, then adhesion and ohmic contact are improved, but Si nodules form that impart p-type properties on the n-type cathode layer increasing on-voltage
Solution Approach 1:
The patent applies different impurity concentrations of Si in Al alloy to different regions: a first Al alloy layer with higher Si concentration (0.5-5 at%) on the n-type cathode layer for optimal adhesion, and a second Al alloy layer with lower Si concentration (0.1-0.5 at%) on the p-type cathode layer to minimize Si nodule formation. This local differentiation resolves the contradiction by maintaining adhesion where needed while preventing harmful Si nodules where they cause problems.
Solution Approach 2:
The patent changes the Si concentration parameter in the Al alloy back electrode from a uniform composition to a graded composition with two distinct layers having different Si concentrations. This parameter change allows optimization of adhesion properties in one region while minimizing Si nodule formation in another region, thereby resolving the technical contradiction between adhesion improvement and Si nodule prevention.
2Stability of the object's composition
If Al alloy layer is oriented in the (111) plane on the entire surface, then crystal structure stability is improved, but Si nodules form on both n-type and p-type cathode layers
Solution Approach 1:
The patent maintains the beneficial (111) plane crystal orientation for overall structural stability while locally modifying the Si concentration in the second Al alloy layer on the p-type cathode layer. This local modification prevents Si nodule formation on the p-type layer without compromising the overall crystal structure stability, resolving the contradiction between structural stability and Si nodule prevention.
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 described configuration effectively reduces on-voltage by limiting Si nodule formation on the n-type cathode layer, thereby enhancing the semiconductor device's performance.
Implementation Method 1
an aluminum (Al) alloy in which silicon (Si) is contained in Al is used from the viewpoint of ohmic contact and adhesion
Implementation Method 2
an aluminum (Al) alloy in which silicon (Si) is contained in Al is used from the viewpoint of ohmic contact and adhesion
Data Source
AI summary
An object of the present invention is to provide a semiconductor device capable of reducing the on-voltage and a manufacturing method thereof. According to the present invention, a semiconductor device includes a Si substrate, a p-type anode layer provided on the front surface of the Si substrate, an anode electrode provided on the p-type anode layer, an n-type cathode layer and a p-type cathode layer provided adjacent to each other on a back surface of the Si substrate, an Al alloy layer provided on the n-type cathode layer and containing Si, and an Al alloy layer provided on the p-type cathode layer and containing Si, in which impurity concentration in the n-type cathode layer is 1E19 cm−3 or higher and impurity concentration in the p-type cathode layer is 10% or lower of the impurity concentration in the n-type cathode layer.