Wafer Bonding via CMP Surface Preparation and Barrier Layers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Semiconductor manufacturers face challenges in achieving smaller feature sizes, higher device density, and lower power consumption while maintaining effective bonding between stacked semiconductor wafers, as existing bonding techniques often result in electrical and mechanical imperfections.
Innovation Solution
A method for wafer bonding that involves forming bonding pads with specific barrier layers and metallic materials, followed by chemical mechanical polishing and surface cleaning to reduce voids, allowing for direct metal-to-metal and dielectric-to-dielectric bonding, enhancing the electrical and mechanical connection between wafers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional bonding techniques are used to bond semiconductor wafers, then bonding between wafers can be achieved, but electrical and mechanical imperfections occur at the bonding interface
Solution Approach 1:
The patent applies preliminary action by performing surface cleaning and chemical mechanical polishing (CMP) on the bonding surfaces of semiconductor wafers before bonding. This pre-treatment removes contaminants and reduces void formation at the bonding interface, ensuring high-quality electrical and mechanical connections are achieved from the outset rather than requiring post-bonding corrections.
2Productivity
If smaller feature sizes are implemented to increase device density, then more devices can be packed into smaller areas, but bonding challenges increase due to reduced tolerance margins
Solution Approach 1:
The patent applies self-service through self-aligned bonding structures where bonding pads on opposing wafers are automatically aligned through precise positioning mechanisms. The bonding process itself facilitates alignment, with bonding pads designed to self-align during the bonding operation, eliminating the need for separate alignment steps and ensuring precision even with reduced feature sizes.
3Reliability
If direct metal-to-metal bonding is performed to improve electrical connection, then electrical conductivity increases, but void formation and bonding defects increase
Solution Approach 1:
The patent applies preliminary action by performing thorough surface cleaning and chemical mechanical polishing (CMP) on bonding surfaces before direct metal-to-metal bonding. This pre-treatment removes contaminants and oxides that would otherwise cause void formation, enabling direct metal bonding to achieve both high electrical conductivity and minimal void formation simultaneously.
Solution Approach 2:
The patent applies parameter changes by optimizing bonding parameters such as bonding pressure, temperature, and surface preparation conditions. By carefully controlling these parameters, the bonding process achieves intimate metal-to-metal contact that maximizes electrical conductivity while minimizing void formation through optimized pressure and temperature profiles during bonding.
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 improves the quality of electrical connections and mechanical bonding between wafers, reducing void sizes and enhancing bonding strength, thereby achieving smaller form factors, increased performance, and cost-effectiveness.
Implementation Method 1
chemical mechanical polishing and surface cleaning to reduce voids
Implementation Method 2
direct metal-to-metal and dielectric-to-dielectric bonding, enhancing the electrical and mechanical connection between wafers
Data Source
AI summary
A semiconductor device and a method of fabricating the same are introduced. In an embodiment, one or more passivation layers are formed over a first substrate. Recesses are formed in the passivation layers and one or more conductive pads are formed in the recesses. One or more barrier layers are formed between the passivation layers and the conductive pads. The conductive pads of the first substrate are aligned to the conductive pads of a second substrate and are bonded using a direct bonding method.