Semiconductor Ohmic Electrode Metal Diffusion Prevention
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Solution Overview
Problem
Existing semiconductor device manufacturing methods result in metal diffusion between the ohmic electrode and the wiring electrode, leading to high electrical resistance values due to metal contamination or impurity attachment and oxide film formation, compromising the reliability of the semiconductor device.
Innovation Solution
A manufacturing method involving the formation of an ohmic electrode with an aluminum layer, followed by heat treatment and acid treatment to remove the oxide film, and subsequent formation of a barrier metal layer and wiring electrode, preventing metal diffusion and maintaining low electrical resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heat treatment is performed after forming the ohmic electrode, the wiring electrode, and the barrier metal layer, then metal diffusion between the ohmic electrode and the wiring electrode is prevented, but the electrical resistance value increases due to oxide film formation and metal contamination on the ohmic electrode surface
Solution Approach 1:
The patent applies preliminary action by performing the heat treatment to form the oxide film on the aluminum layer surface before forming the barrier metal layer and wiring electrode. This preliminary oxide film formation prevents metal diffusion during subsequent processing, while the oxide film is later removed by acid treatment to restore low electrical resistance. The sequence of operations (heat treatment → barrier metal formation → acid treatment → wiring electrode formation) ensures both metal diffusion prevention and low resistance maintenance.
2Reliability
If the barrier metal layer is formed before heat treatment, then metal diffusion is prevented, but the manufacturing process complexity increases and the ohmic electrode surface quality deteriorates due to impurity attachment during heat treatment
Solution Approach 1:
The patent uses preliminary action by forming the oxide film on the aluminum layer surface through heat treatment before forming the barrier metal layer. This preliminary oxide film acts as a protective layer that prevents metal diffusion during subsequent processing steps, eliminating the need for a separate barrier metal layer formation step before heat treatment, thereby simplifying the overall manufacturing process.
Solution Approach 2:
The oxide film formed on the aluminum layer surface acts as an intermediary layer that prevents direct contact and diffusion between the ohmic electrode and wiring electrode metals. This intermediary oxide film, later removed by acid treatment, serves the protective function during critical processing steps without requiring complex barrier metal structures.
3Stability of the object's composition
If the ohmic electrode is exposed to the atmosphere after heat treatment, then the oxide film forms on the surface, but this increases electrical resistance and compromises device reliability
Solution Approach 1:
The patent converts the harmful effect of oxide film formation (which increases electrical resistance) into a beneficial protective layer. The oxide film formed by heat treatment or atmospheric exposure is initially harmful to electrical conductivity, but the patent utilizes this oxide film as a protective barrier against metal diffusion during subsequent processing. The oxide film is then selectively removed by acid treatment only in the contact portion, achieving both protection during manufacturing and low resistance in the final device.
Solution Approach 2:
The patent applies local quality by selectively removing the oxide film only in the contact portion where the wiring electrode contacts the ohmic electrode, while maintaining the oxide film in other areas for protection. This localized acid treatment ensures low electrical resistance at the critical contact interface while preserving the protective oxide film elsewhere on the aluminum layer surface.
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 method effectively prevents metal diffusion and maintains low electrical resistance in semiconductor devices, ensuring high reliability by using the acid treatment to remove the oxide film and forming the barrier metal layer and wiring electrode after heat treatment.
Implementation Method 1
performing a heat treatment on the ohmic electrode
Implementation Method 2
performing an acid treatment on a surface of the aluminum layer in the ohmic electrode that has been subjected to the heat treatment
Data Source
AI summary
A manufacturing method of a semiconductor device comprises forming an ohmic electrode on a surface of a semiconductor substrate, the ohmic electrode including an aluminum layer in a side opposite to a side in contact with the semiconductor substrate, performing a heat treatment on the ohmic electrode, performing an acid treatment on a surface of the aluminum layer in the ohmic electrode that has been subjected to the heat treatment and forming a wiring electrode in the side of the aluminum layer opposite to the side where the semiconductor substrate is provided after the acid treatment.