Plasma-Activated Substrate Bonding Under Partial Vacuum
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-temperature thermal treatments required for achieving high bonding energies between substrates are not feasible when devices are present, as they can damage the devices due to dopant concentration spreading and metal diffusion, leading to low bonding energies and increased edge voids, which negatively impact fabrication yield.
Innovation Solution
A method involving plasma treatment and contacting the substrates under partial vacuum at room temperature to achieve bonding energies of 700-1000 mJ/m² with reduced edge voids, using standard rough pumps and maintaining the process in a dry, neutral atmosphere to prevent defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high-temperature thermal treatment (1000-1100°C) is applied to achieve high bonding energy, then bonding energy increases to 1.5 J/m², but devices on the substrate are damaged due to dopant spreading and metal diffusion
Solution Approach 1:
The patent changes the bonding parameters from high-temperature (1000-1100°C) to room temperature conditions. By using plasma activation to modify surface chemistry and creating partial vacuum (1-50 Torr) to remove contaminants and promote molecular bonding, the method achieves high bonding energy (700-1000 mJ/m²) without thermal damage to devices, thus resolving the contradiction between bonding strength and device reliability
Solution Approach 2:
The patent replaces the thermal field (heat treatment) with a combination of plasma field and vacuum field. Instead of using thermal energy to activate bonding, the method uses plasma activation to create reactive surface groups and partial vacuum to facilitate direct molecular contact, achieving bonding without the harmful thermal effects on processed devices
2Strength
If surface activation steps (plasma activation) are applied to achieve high bonding energy without high temperature, then bonding energy increases, but the number of edge voids increases
Solution Approach 1:
The patent merges plasma activation with partial vacuum conditions in a single bonding process. The plasma treatment activates surface groups while the partial vacuum (1-50 Torr) simultaneously removes adsorbed water and contaminants. This combination prevents the formation of edge voids that occur with plasma activation alone in atmospheric conditions, while maintaining high bonding energy
Solution Approach 2:
The patent uses partial vacuum as an inert environment during bonding. By reducing the pressure to 1-50 Torr, the method eliminates atmospheric contaminants and moisture that would otherwise interfere with the bonding interface. This creates a clean environment that prevents edge void formation while allowing high bonding energy to be achieved through plasma-activated surfaces
3Reliability
If standard thermal treatment is applied to improve bonding energy, then bonding quality improves, but fabrication yield decreases due to device damage
Solution Approach 1:
The patent fundamentally changes the bonding parameters from thermal-based to plasma-and-vacuum-based processing. By conducting bonding at room temperature under partial vacuum (1-50 Torr) with plasma activation, the method achieves high bonding quality (700-1000 mJ/m²) while completely avoiding thermal damage to devices, thus maintaining high fabrication yield
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 method achieves high bonding quality with reduced edge voids and allows for successful layer transfer without high-temperature annealing, preserving device integrity and improving fabrication yield, even with substrates of different thermal expansion coefficients.
Implementation Method 1
applying an activation treatment, comprising a plasma treatment, to at least one of the two substrates
Implementation Method 2
the adhesion between two substrates is achieved via molecular forces (Van de Waals forces)
Implementation Method 3
performing the contacting step of the two substrates under partial vacuum
Data Source
Figure 1a~1g
AI summary
The invention relates to a method for bonding two substrates, comprising the steps of applying an activation treatment to at least one of the substrates, and performing the contacting step of the two substrates under partial vacuum. Due to the combination of the two steps, it is possible to carry out the bonding and obtain high bonding energy with a reduced number of bonding voids. The invention is in particular applicable to a substrate comprising processed or at least partially processed devices.