Semiconductor Gettering Layer for Metal Impurity Capture
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Solution Overview
Problem
The semiconductor device manufacturing process is complicated due to the repeated steps of forming gettering sites, heating, and removing contaminated layers, and there is a lack of clarity on the conditions under which the gettering technique affects the electrical characteristics of the semiconductor device.
Innovation Solution
A semiconductor device with a substrate having a drift layer and metal wiring, where the carrier lifetime in the drift layer is optimized to satisfy a specific expression, allowing for the stabilization of electrical characteristics while removing metal impurities in a simple manner, and a method involving a gettering layer to capture impurities and defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gettering technique is used to remove metal impurities from the substrate, then the electrical characteristics are improved, but the manufacturing process becomes complicated due to repeated steps of forming gettering sites, heating, and removing contaminated layers
Solution Approach 1:
A gettering layer is formed in advance before the drift layer is created. This preliminary gettering layer is positioned to face the drift layer, so that during subsequent heat treatment steps, metal impurities are automatically captured without requiring separate gettering site formation steps. This resolves the contradiction by performing the impurity capture function beforehand, eliminating the need for repeated manufacturing steps while maintaining electrical characteristic improvement.
Solution Approach 2:
A dedicated gettering layer is introduced as an intermediary component between the substrate and the drift layer. This gettering layer serves as a mediator that captures metal impurities through heat treatment, preventing them from affecting the drift layer's electrical characteristics. The intermediary layer absorbs the harmful impurities, thereby improving electrical characteristics without complicating the overall manufacturing process when properly integrated.
2Manufacturing precision
If multiple repeated steps of forming gettering sites, heating, and removing contaminated layers are performed, then metal impurities are effectively removed, but the manufacturing time and productivity are reduced
Solution Approach 1:
The gettering layer is formed in advance before drift layer fabrication, and is designed to perform impurity capture during standard heat treatment steps that are already part of the manufacturing process. This eliminates the need for additional repeated heating and contamination removal steps, thereby maintaining effective metal impurity removal while significantly improving manufacturing efficiency and productivity.
Solution Approach 2:
The gettering function is merged with the existing heat treatment steps used in drift layer formation. Instead of separating the impurity removal process into distinct repeated steps, the gettering layer utilizes the thermal energy already applied during standard manufacturing operations to capture metal impurities. This merging of functions maintains manufacturing precision for impurity removal while reducing overall process time and improving productivity.
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 stabilizes electrical characteristics and enhances the essential performance of the semiconductor device by optimizing carrier lifetime and gettering impurities, simplifying the manufacturing process and improving device performance.
Implementation Method 1
a gettering technique, a gettering site is first formed in a lower surface of a semiconductor wafer (substrate). Thereafter, a heat treatment is performed on the substrate to capture a metal impurity in the substrate with the gettering site
Implementation Method 2
a heat treatment is performed on the substrate to capture a metal impurity in the substrate with the gettering site
Data Source
AI summary
A semiconductor device of the present invention includes a substrate having a drift layer, metal wiring formed on an upper surface of the substrate, and an electrode formed on a back surface of the substrate, wherein the lifetime of carriers in the drift layer satisfies the following expression 1:[Expression 1]τ≥1.5×10−5 exp(5.4×103tN−) expression 1τ: the lifetime of carriers in the drift layertN−: the layer thickness of the drift layer.