Bonding Pad Structure for TiN-Cu Intermetallic Connection Reliability
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Solution Overview
Problem
The formation of an intermetallic compound between titanium and copper layers in conductive structures during high-temperature processes in electronic devices leads to difficulties in etching and affects the electrical connection reliability.
Innovation Solution
A conductive structure with a specific sequence of layers, including a first and third conductive layer with an intermetallic compound and a second conductive layer exposed through openings in insulating layers, allowing for improved electrical connections through the bonding structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conductive structure with multiple conductive layers (titanium nitride, copper, titanium nitride) is used, then electrical conductivity is improved, but during high-temperature processes titanium diffuses toward copper forming intermetallic compounds that are difficult to remove and affect electrical connection reliability
Solution Approach 1:
The conductive structure is divided into multiple functional layers: a first conductive layer (titanium nitride), a second conductive layer (copper), and a third conductive layer (titanium nitride). This segmentation allows the copper layer to provide excellent electrical conductivity while the titanium nitride layers act as diffusion barriers, preventing titanium-copper intermetallic compound formation during high-temperature processes.
Solution Approach 2:
The first and third conductive layers of titanium nitride serve as intermediary barrier layers between the copper layer and other structures. These intermediary layers prevent direct contact and diffusion between titanium and copper, thereby eliminating the formation of difficult-to-etch intermetallic compounds while maintaining electrical conductivity.
2Reliability
If titanium nitride layers are used to prevent diffusion, then intermetallic compound formation is reduced, but the complexity of the conductive structure increases with multiple stacked layers
Solution Approach 1:
The conductive structure is divided into multiple functional layers: a first conductive layer (titanium nitride), a second conductive layer (copper), and a third conductive layer (titanium nitride). This segmentation allows the copper layer to provide excellent electrical conductivity while the titanium nitride layers act as diffusion barriers, preventing titanium-copper intermetallic compound formation during high-temperature processes.
Solution Approach 2:
The conductive structure employs a composite material design combining titanium nitride and copper in a stacked configuration. This composite structure leverages the high electrical conductivity of copper while utilizing titanium nitride's properties as a diffusion barrier, achieving reliable electrical connections without intermetallic compound formation.
3Ease of manufacture
If the bonding structure is directly connected to the conductive structure, then manufacturing is simplified, but adhesion and stability are insufficient due to intermetallic compounds
Solution Approach 1:
The first and third conductive layers of titanium nitride serve as intermediary barrier layers between the copper layer and other structures. These intermediary layers prevent direct contact and diffusion between titanium and copper, thereby eliminating the formation of difficult-to-etch intermetallic compounds while maintaining electrical conductivity.
Solution Approach 2:
The patent converts the potential harm of titanium-copper diffusion into a benefit by intentionally forming a controlled intermetallic compound layer between the copper layer and bonding structure. This controlled intermetallic layer actually improves adhesion and bonding strength while preventing further unwanted diffusion.
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
Enhances the reliability of electrical connections by ensuring good adhesion and stability of the bonding structure, reducing the impact of intermetallic compounds and improving signal transmission quality.
Implementation Method 1
the titanium in the titanium nitride layer included in the conductive structure diffuses toward the direction close to the copper layer, resulting in the formation of an intermetallic compound including copper and titanium
Data Source
AI summary
An electronic device including a substrate, a conductive structure, an insulating layer, and a bonding structure. The conductive structure is disposed on the substrate and includes a first conductive layer, a second conductive layer, an intermetallic compound, and a third conductive layer stacked in such a sequence, in which the intermetallic compound includes a first opening exposing the second conductive layer. The insulating layer is disposed on the conductive structure and includes a second opening exposing the second conductive layer of the conductive structure. The bonding structure is disposed on the insulating layer, in which the bonding structure is electrically connected to the conductive structure through the second opening of the insulating layer. A first width of the second opening of the insulating layer in a first direction is different from a second width of the first opening of the intermetallic compound in the first direction.