Hybrid Bonding Surface Cleaning for Nanoparticle Leakage Control
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Solution Overview
Problem
In hybrid bonding processes involving metal-to-metal and dielectric materials, very small conductive nanoparticles can cause electrical leakage and micro-delamination due to their presence at the bonding interface, especially in microelectronic devices with submicron trace pitches, leading to reliability issues.
Innovation Solution
A cleaning process is introduced after surface activation to remove extraneous conductive nanoparticles using dilute acids, organic compounds, and mechanical methods like dry ice spraying, ensuring the bonding surfaces are free of such particles before hybrid bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cleaning with deionized water is used after surface activation, then the activated surface is maintained, but extraneous conductive nanoparticles remain and cause electrical leakage
Solution Approach 1:
The patent changes the chemical parameters of the cleaning solution by using dilute acids (such as hydrofluoric acid, phosphoric acid, or sulfuric acid) instead of conventional deionized water. This parameter change enables the cleaning solution to effectively dissolve and remove extraneous conductive nanoparticles from the bonding interface while maintaining compatibility with the activated bonding surfaces.
Solution Approach 2:
The patent introduces a specialized cleaning solution as an intermediary substance between the activated bonding surfaces. This cleaning solution acts as a mediator that selectively removes harmful conductive nanoparticles without damaging the bonding interfaces, thereby resolving the contradiction between maintaining surface activation and removing contamination.
2Object-affected harmful factors
If stronger cleaning chemicals are used to remove nanoparticles, then particle removal is improved, but the activated bonding surface may be damaged
Solution Approach 1:
The patent optimizes the concentration parameters of the cleaning solution by using dilute acids rather than concentrated strong chemicals. This parameter optimization achieves effective nanoparticle removal while controlling the aggressiveness of the cleaning action to prevent damage to the activated bonding surfaces.
Solution Approach 2:
The patent applies a controlled amount of cleaning action that is sufficient to remove nanoparticles but not excessive enough to damage the bonding interface. The use of dilute acids provides partial cleaning action that targets nanoparticles specifically while being gentler on the bonding surfaces compared to stronger chemicals.
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 process enhances the electrical reliability of microelectronic devices by preventing signal leakage and maintaining the integrity of the bonding interface, ensuring high success rates and fine pitch interconnects.
Implementation Method 1
cleaning the surface to remove particles disposed at the surface... cleaning with other chemicals
Implementation Method 2
the extraneous nanoparticles may be both physically removed and/or dissolved without detriment
Implementation Method 3
mechanical methods like dry ice spraying
Implementation Method 4
cleaning processes described herein increase the electrical reliability
Data Source
AI summary
Reliable hybrid bonded apparatuses are provided. An example process cleans nanoparticles from at least the smooth oxide top layer of a surface to be hybrid bonded after the surface has already been activated for the hybrid bonding. Conventionally, such an operation is discouraged. However, the example cleaning processes described herein increase the electrical reliability of microelectronic devices. Extraneous metal nanoparticles can enable undesirable current and signal leakage from finely spaced traces, especially at higher voltages with ultra-fine trace pitches. In the example process, the extraneous nanoparticles may be both physically removed and/or dissolved without detriment to the activated bonding surface.