Memory Device Bonding Pad Structure with Mesh Buffer for Stress Relief
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional pad bonding processes in memory device fabrication often result in bonding stress that damages vertical vias due to unrelieved stress, as the stress is not adequately released during the bonding of upper conductor layers.
Innovation Solution
A bonding pad structure featuring a base metal layer, an intermediate buffer layer with a mesh structure and hollow central region, and a surface bonding layer, where conductive vias are arranged in peripheral regions but not centrally, allowing for deformation and stress relief during bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vertical conductive vias are used to interconnect conductor layers, then electrical connection is achieved, but bonding stress causes damage to the vias
Solution Approach 1:
The patent introduces an intermediate buffer layer between the base metal layer and the surface bonding layer. This buffer layer acts as a stress-absorbing intermediary that prevents direct transmission of bonding stress to the conductive vias, thereby protecting them from damage while maintaining electrical connectivity.
Solution Approach 2:
The patent modifies the structural parameters of the bonding pad by creating a mesh structure in the intermediate buffer layer and positioning conductive vias in peripheral regions rather than central regions. This parameter change allows the central region to deform and absorb stress, reducing stress concentration on the vias during bonding.
2Strength
If the bonding layer is made rigid for structural stability, then mechanical strength is improved, but stress cannot be released during bonding
Solution Approach 1:
The intermediate buffer layer is segmented into a mesh structure with multiple regions. This segmentation allows different parts of the buffer layer to deform independently during bonding, enabling stress release while maintaining overall structural integrity and strength of the bonding layer.
Solution Approach 2:
The patent creates a dynamic structure where the intermediate buffer layer can deform in response to bonding stress. The mesh structure and peripheral via arrangement allow the layer to adapt its shape during bonding, transforming from a static rigid structure to a dynamic stress-absorbing structure that maintains strength while releasing stress.
Data Source
AI summary
A bonding pad structure and a method thereof includes: a base metal layer formed on a substrate; first conductive vias arranged in a peripheral region of the base metal layer; an intermediate buffer layer formed above the base metal layer, the intermediate buffer layer spaced from and aligned with the base metal layer, the first conductive vias vertically connecting the base metal layer and the intermediate buffer layer; second conductive vias arranged in a peripheral region of the intermediate buffer layer; a surface bonding layer formed above the intermediate buffer layer, the surface bonding layer spaced from and aligned with the intermediate buffer layer, the second conductive vias vertically connecting the intermediate buffer layer and the surface bonding layer, the intermediate buffer layer comprising a mesh structure, and the first conductive vias and the second conductive vias not vertically aligned with a central region of the intermediate buffer layer.