Semiconductor Electrode Barrier Layer Corrosion Prevention
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Solution Overview
Problem
Semiconductor light-emitting devices with aluminum (Al) reflection layers face issues such as corrosion, void formation, and interdiffusion with gold (Au) layers, leading to increased forward voltage and reduced reliability due to the low melting point and chemical activity of Al, as well as the complexity and cost of existing electrode manufacturing processes.
Innovation Solution
A semiconductor light-emitting device with an electrode structure featuring a barrier layer covering the side surface of the Al reflection layer and a pad layer only on the top surface, using high melting point metals like Pt, Mo, or W for the barrier layer and Au for the pad layer, and an adhesion layer like Ni to prevent interdiffusion and corrosion, while simplifying the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an Al layer is used as a reflection layer, then high reflectance and low cost are achieved, but corrosion, void formation, and interdiffusion with Au layer occur reducing reliability
Solution Approach 1:
A barrier layer made of high melting point metal (Pt, Mo, or W) is inserted between the Al reflection layer and the Au pad layer. This intermediary layer prevents direct contact between Al and Au, thereby suppressing interdiffusion and the formation of AuAl intermetallic compounds. The barrier layer also protects the Al layer from corrosion while maintaining the electrode's electrical and optical performance.
2Reliability
If multiple layers (Al, barrier, pad) are stacked to prevent interdiffusion, then reliability improves, but manufacturing process complexity increases
Solution Approach 1:
The invention specifies optimal thickness ranges for each layer to balance protection and manufacturability. The Al layer is 5-20 nm thick, the barrier layer is 2-10 nm thick, and the Au pad layer is 50-200 nm thick. These parameter optimizations ensure effective protection against interdiffusion and corrosion while maintaining compatibility with standard semiconductor manufacturing processes.
3Illumination intensity
If the Al layer is made thicker to improve reflectance, then optical performance improves, but void formation and interdiffusion increase
Solution Approach 1:
The invention creates a composite electrode structure where a thin Al layer (5-20 nm) provides sufficient reflectance for LED applications, while a barrier layer of high melting point metal (2-10 nm) prevents void formation and interdiffusion. This composite approach achieves optimal optical performance without the reliability issues associated with thicker Al layers.
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
This configuration effectively suppresses corrosion and interdiffusion, maintains reflectance, and reduces the formation of AuAl intermetallic compounds, enhancing the reliability and manufacturing efficiency of the semiconductor light-emitting device.
Implementation Method 1
a barrier layer covering side surfaces of the Al layer
Implementation Method 2
a reflection layer that reflects light exiting from the light-emitting layer
Implementation Method 3
an adhesion layer like Ni to prevent interdiffusion and corrosion
Data Source
AI summary
A semiconductor light-emitting device having an electrode that can be manufactured by a simple method and is unlikely to deteriorate, and a method for forming the electrode are provided. The semiconductor light-emitting device according to the present invention has a semiconductor layered structure having a light-emitting layer that emits light by supplying electric power and an electrode formed on the semiconductor layered structure. The electrode has a reflection layer that reflects light exiting from the light-emitting layer, a barrier layer formed on the upper side and side surface of the reflection layer, and a pad layer formed only on the top surface of the barrier layer.