Direct Substrate Bonding in a Basic Environment at Low Temperature
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Solution Overview
Problem
Current direct bonding techniques face challenges in achieving high bonding energy at low temperatures without using plasma treatment, which can be incompatible with certain substrates and increase process costs and complexity, while also risking disruption to future device operations.
Innovation Solution
A process involving direct contact between substrates followed by immersion in a basic environment and a controlled heat treatment between 20 °C and 1000 °C, specifically between 100 °C and 500 °C, to enhance bonding energy without altering the adhesion properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If plasma treatment is used to increase bonding energy, then bonding energy increases rapidly to around 5 J/m², but the process becomes incompatible with certain substrates, increases time and costs, and modifies the surface over a thickness of 1-10 nm which can disrupt future devices
Solution Approach 1:
The patent replaces expensive and complex plasma treatment with a simple aqueous basic solution treatment that can be easily discarded after use. The basic solution treatment achieves comparable bonding energy enhancement without the need for expensive plasma equipment, complex process control, and substrate compatibility concerns.
Solution Approach 2:
The patent changes the chemical parameters of the treatment by using aqueous basic solutions with controlled pH and concentration rather than plasma. This parameter change allows achieving similar bonding energy enhancement while avoiding the harmful effects of plasma modification on substrate surfaces and device structures.
2Strength
If plasma treatment is used to increase bonding energy, then bonding energy increases rapidly, but the treatment modifies the surface over a thickness of 1-10 nm which can disrupt future device operations
Solution Approach 1:
The patent uses a simple aqueous basic solution that can be easily applied and discarded, replacing plasma treatment that causes permanent surface modification. The basic solution treatment enhances bonding energy without creating lasting surface changes that would disrupt future device operations.
Solution Approach 2:
The patent changes from plasma-based surface modification to aqueous basic solution treatment, altering the chemical parameters of the process. This change achieves bonding energy enhancement through chemical activation without the physical modification and damage caused by plasma, thus avoiding surface thickness modification and associated disruptions.
3Strength
If high temperature heat treatment is used to increase bonding energy to 3 J/m², then bonding energy increases, but the process becomes incompatible with electronic and opto-electronic components requiring low thermal budgets
Solution Approach 1:
The patent applies preliminary treatment with aqueous basic solutions before bonding to activate the surfaces and enhance adhesion energy. This preliminary chemical activation allows subsequent bonding to achieve high bonding energy at lower temperatures, making the process compatible with temperature-sensitive electronic and opto-electronic components.
Solution Approach 2:
The patent changes the chemical parameters by introducing aqueous basic solution treatment, which modifies surface properties to enable low-temperature bonding. This chemical parameter change compensates for the reduced thermal energy input, allowing bonding energy to reach 3 J/m² or higher at temperatures below 400°C, thus protecting temperature-sensitive components.
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 strong bonding energy at low temperatures, compatible with various applications and substrates, including electronic and opto-electronic components, with improved mechanical resistance and cost-effectiveness, while maintaining the adhesion energy and avoiding disruptions to subsequent processes.
Implementation Method 1
providing at least the direct bonding interface in a basic environment
Implementation Method 2
applying a heat treatment at a temperature between 20°C and 1000°C, in particular between 100°C and 500°C
Implementation Method 3
bring them into contact at the atomic scale so that the Van der Waals forces can be implemented
Data Source
Figure 1~4
Figure 5~7
AI summary
A method for manufacturing a multilayer structure (100) by direct bonding between a first substrate (1) and a second substrate (2), the method comprising the steps of: a) supplying a first substrate (1) and a second substrate (2) comprising respectively a first bonding surface (3) and a second bonding surface (4), b) bringing the first bonding surface (3) and the second bonding surface (4) into contact so as to create a direct bonding interface (6) between the first substrate (1) and the second substrate (2), c) disposing of at least the direct bonding interface (6) in a basic environment, and d) applying a heat treatment at a temperature between 20°C and 350°C so as to obtain the multilayer structure (100).