Semiconductor Pad Diffusion Barrier for Bonding Reliability
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Solution Overview
Problem
The existing techniques for bonding semiconductor substrates often result in the deterioration of electrical properties due to material diffusion from contact pads into dielectric films, caused by relative displacement during bonding.
Innovation Solution
The solution involves forming pads on semiconductor substrates with exposed regions made of metallic materials that are less diffusible into insulating layers, ensuring that even if misalignment occurs during bonding, the pads do not degrade the electrical properties by minimizing diffusion into the dielectric films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional bonding techniques are used to bond semiconductor substrates, then the substrates can be electrically connected through bump structures, but material diffusion from contact pads into dielectric films occurs due to relative displacement during bonding, deteriorating electrical properties
Solution Approach 1:
A capping structure is introduced as an intermediary element between the contact pad and the dielectric film. This capping structure prevents direct contact and diffusion between the pad material and dielectric film, while still allowing electrical connection to be established through the bonding interface. The capping structure acts as a protective mediator that eliminates the harmful diffusion effect.
Solution Approach 2:
The capping structure is formed on the contact pad before the bonding process occurs. This preliminary protective action prevents the potential harmful effect of material diffusion that would occur during bonding, even before the actual displacement and contact between substrates takes place.
2Manufacturing precision
If contact pads are made larger to ensure proper alignment during bonding, then misalignment tolerance is improved, but the area available for electrical connection is reduced due to pad displacement
Solution Approach 1:
The capping structure serves as a mediator that decouples the alignment function from the electrical connection function. The enlarged contact pad can focus on providing alignment tolerance through increased area, while the capping structure ensures that the electrical connection area is protected from displacement effects, maintaining connection reliability.
3Object-generated harmful factors
If the bonding process is made more stringent to prevent displacement, then material diffusion is reduced, but the ease of manufacture decreases due to tighter process control requirements
Solution Approach 1:
The capping structure is formed in advance before bonding, providing preliminary protection against material diffusion. This allows the bonding process itself to be less stringent, as the protective barrier is already in place, thereby improving ease of manufacture while still preventing 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
This approach effectively prevents the degradation of electrical properties in semiconductor devices by using pads made of metals like Au, Ag, Al, Ta, Ti, W, Sn, Mo, Ni, In, and Co, which are less diffusible into dielectric films, thereby maintaining the integrity of the semiconductor devices during bonding and reducing costs.
Implementation Method 1
At least a region at an exposed top surface of the pad is made of a metallic material that is less diffusible into an insulating layer than is the wiring
Data Source
AI summary
A semiconductor device with a connection pad in a substrate, the connection pad having an exposed surface made of a metallic material that diffuses less readily into a dielectric layer than does a metal of a wiring layer connected thereto.