Aluminum Pad Electrode Corrosion Protection via Ion Implantation
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Solution Overview
Problem
Existing semiconductor devices face issues with aluminum corrosion and reduced bonding durability due to the reactivity of fluorine-based etching gases and the formation of intermetallic compounds at Au-Al junctions, which affect the reliability and longevity of the devices.
Innovation Solution
A semiconductor device manufacturing method that involves forming a conductive film of aluminum or aluminum alloy, depositing a metal film, and using ion milling to create a metal film region with implanted atoms on the surface, which acts as a protective layer during etching, reducing grain boundary diffusion and preventing corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If fluorine based etching gas (CF4) is used to open the pad electrode, then the etching process can be completed, but aluminum corrosion occurs due to hydrofluoric acid formation
Solution Approach 1:
A metal film (titanium, tungsten, or tungsten silicide) is introduced as an intermediary protective layer between the aluminum conductive film and the fluorine-based etching gas. This intermediary layer prevents direct contact between the etching gas and aluminum, blocking the formation of hydrofluoric acid and subsequent corrosion, while still allowing the etching process to proceed effectively.
Solution Approach 2:
The metal film is deposited on the aluminum conductive film before the etching process begins. This preliminary protective coating ensures that when fluorine-based etching gas is subsequently applied, the aluminum surface is already protected, preventing corrosion before it can occur during the etching operation.
2Use of energy by moving object
If aluminum is used as pad electrode material, then good electrical conductivity is achieved, but bonding durability decreases due to intermetallic compound formation at Au-Al junctions
Solution Approach 1:
The pad electrode structure is designed as a composite material system with multiple layers: aluminum conductive film providing electrical conductivity, metal film (titanium, tungsten, or tungsten silicide) providing corrosion resistance and intermediate bonding properties, and protective film providing environmental protection. This composite structure combines the advantages of different materials while mitigating their individual disadvantages.
Solution Approach 2:
Different regions of the pad electrode structure have different material compositions optimized for their specific functions: the aluminum layer provides bulk conductivity, the metal film layer provides corrosion resistance and controlled intermetallic formation, and the protective film layer provides environmental protection. Each layer's properties are locally optimized for its specific role in the overall system.
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 method enhances the reliability of semiconductor devices by preventing aluminum corrosion and improving bonding durability by restricting grain boundary diffusion and reducing the formation of intermetallic compounds, leading to a more stable and long-lasting semiconductor device.
Implementation Method 1
a metal film region in which atoms derived from the metal film are implanted is formed on a surface of the conductive film exposed by an opening formed in one portion of the protective film and the metal film
Implementation Method 2
a metal film region in which atoms derived from the metal film are implanted is formed on a surface of the conductive film
Implementation Method 3
restricting grain boundary diffusion
Data Source
AI summary
A pad electrode such that a conductive film is used as the pad electrode in a semiconductor device has an object of preventing Al corrosion and improving Au bonding wire durability. A semiconductor device according to the invention includes a conductive film of Al or having Al as a main component on which a signal processing circuit and a pad electrode portion are formed, a metal film formed on the conductive film, and a protective film formed on the metal film, wherein a metal film region in which atoms derived from the metal film are implanted is formed on a surface of the conductive film exposed by an opening formed in one portion of the protective film and the metal film, and adopted as the pad electrode.