Wettable Metallization Multilayer With Intermetallic Diffusion Adhesion
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Solution Overview
Problem
The existing wettable metalization multilayers in integrated electronic devices face adhesion issues due to oxidation at the bottom surface of the top metal layer, leading to detachment and failure in bonding with electrical connectors.
Innovation Solution
A wettable metalization multilayer is developed, comprising an adhesion layer of titanium, a barrier layer of nickel, an intermetallic layer of aluminum or tin, and a sintering layer of silver, where the intermetallic layer facilitates a diffusion process between the barrier and sintering layers, enhancing adhesion and preventing oxygen penetration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the top metal layer is made thicker to prevent oxidation, then oxidation resistance is improved, but adhesion between layers deteriorates due to stress accumulation and detachment
Solution Approach 1:
The top metal layer is segmented into multiple thinner sub-layers (e.g., first top metal layer and second top metal layer) with an intermediate layer in between. This segmentation reduces stress accumulation in each individual layer while maintaining overall thickness for oxidation resistance, thereby preventing detachment while blocking oxygen diffusion.
Solution Approach 2:
An intermediate layer is introduced between the top metal layers. This intermediate layer acts as a stress relief layer that accommodates thermal expansion differences and reduces interfacial stress, preventing detachment while the overall multilayer structure maintains oxidation resistance through the combined thickness of all layers.
2Object-affected harmful factors
If better chamber environment control is implemented to reduce oxygen presence, then oxidation is reduced, but manufacturing complexity increases
Solution Approach 1:
A bottom metal layer with high oxygen barrier properties (such as tungsten or molybdenum) is deposited beforehand as a diffusion barrier. This preliminary action blocks oxygen diffusion paths at the substrate interface, reducing the need for complex chamber environment control during subsequent processing steps.
Solution Approach 2:
The metalization structure uses composite material design with different layers having complementary properties: bottom layers provide oxygen barrier functionality (tungsten, molybdenum), intermediate layers provide adhesion and stress management (titanium, nickel), and top layers provide conductivity and oxidation resistance (gold, copper). This composite approach distributes functionality across layers, reducing reliance on complex environmental control.
3Ease of operation
If the surface topography is improved for better planarity, then bonding capability is enhanced, but manufacturing process complexity increases
Solution Approach 1:
The surface planarity is optimized locally at the bonding interface through selective deposition techniques. The top metal layers are deposited with controlled thickness and morphology to ensure adequate planarity only in the regions where bonding occurs, rather than requiring entire wafer-level planarity, thus reducing manufacturing complexity while maintaining bonding capability.
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 proposed solution effectively increases the adhesion energy between the barrier and sintering layers, preventing delamination and detachment, thereby ensuring reliable bonding with external connectors and improving the overall performance of integrated electronic devices.
Implementation Method 1
the formation of the sintering layer includes a diffusion process between atoms of the intermetallic layer and atoms of the respective barrier and sintering layers
Implementation Method 2
forming a sintering layer includes causing atoms of the intermetallic layer to diffuse into both the sintering layer and the barrier layer
Data Source
AI summary
Wettable metalization multilayer formed by an adhesion layer, containing titanium; a barrier layer, containing nickel; and a sintering layer, containing silver. A portion of the sintering layer, facing the barrier layer, contains atoms of a metal material chosen between aluminum and tin. A portion of the barrier layer facing the sintering layer may contain atoms of the metal material. The sintering layer is obtained depositing by PVD and spinning a metal material layer and then a silver layer, causing the diffusion of the atoms of the metal material in the silver layer.