Low-Temperature Bonding of 3D Heterostructures
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing low-temperature bonding processes for substrates or wafers often result in defects at the bonding interface, which adversely affect the bonding energy, making it challenging to achieve high-quality bonding without high-temperature heat treatment, especially when components or circuits are present.
Innovation Solution
A method involving the formation of bonding layers on substrates at low temperatures, followed by a degassing annealing to remove contaminants, and subsequent molecular adhesion with a bonding interface strengthening annealing at temperatures below 450°C, ensuring a gradual or rapid temperature ramp to maintain bonding energy and prevent defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If low-temperature bonding is used to avoid damage to components or circuits, then the substrates can be assembled without high-temperature heat treatment, but defects appear at the bonding interface and bonding energy is reduced
Solution Approach 1:
The bonding layers are pre-annealed at low temperatures (below 450°C) before the actual bonding process. This preliminary action removes contaminants and prepares the bonding surfaces, enabling high-quality bonding at low temperatures without damaging components or circuits while avoiding interface defects
Solution Approach 2:
The patent changes the temperature parameters of the annealing process, specifically using low temperatures (below 450°C) that are sufficient to activate the bonding layers and remove contaminants but low enough to prevent damage to temperature-sensitive components and circuits on the substrates
2Temperature
If low-temperature bonding layers are formed to protect components, then substrates can be assembled at low temperatures, but bonding energy is insufficient and interface defects occur
Solution Approach 1:
A preliminary annealing step is performed on the bonding layers at low temperatures (below 450°C) before bonding. This activates the bonding layers and removes contaminants, enabling strong bonding (≥3 J/m²) at low temperatures without damaging components
Solution Approach 2:
The bonding layers are formed and then immediately annealed in a continuous low-temperature process, maintaining the beneficial low-temperature condition throughout while achieving both strong bonding and component protection
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 energies of at least 3 J/m2 with minimal defects, enabling the assembly of substrates or wafers with components or circuits without high-temperature treatments, thus overcoming the limitations of prior low-temperature bonding processes.
Implementation Method 1
conducting a first annealing of the first and second bonding layers on the first and second substrates for a first annealing time period
Implementation Method 2
The first annealing of the first and second bonding layers at a temperature below 450° C. removes contaminants from the bonding layers
Implementation Method 3
contacting the exposed surfaces of the first bonding layer and the second bonding layer produces bonding by molecular adhesion
Data Source
AI summary
The invention relates to a process for assembling a first element that includes at least one first wafer, substrate or at least one chip, and a second element of at least one second wafer or substrate, involving the formation of a surface layer, known as a bonding layer, on each substrate, at least one of the bonding layers being formed at a temperature less than or equal to 300° C.; conducting a first annealing, known as degassing annealing, of the bonding layers, before assembly, at least partly at a temperature at least equal to the subsequent bonding interface strengthening temperature but below 450° C.; forming an assembling of the substrates by bringing into contact the exposed surfaces of the bonding layers, and conducting an annealing of the assembled structure at a bonding interface strengthening temperature below 450° C.