Substrate Bonding via Amorphous Layer Crystallization
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Solution Overview
Problem
Existing bonding technologies in the semiconductor industry face challenges such as high temperature requirements for heat treatment, which can lead to thermal stresses, dopant diffusion, and increased costs, especially when bonding temperature-sensitive substrates like microchips with strong doping. Additionally, surface oxides on metals hinder bonding processes, particularly on oxygen-affine metals like silicon, which form stable silicon dioxide layers.
Innovation Solution
A method involving the production of amorphous layers on substrates, followed by irradiation to convert these layers into crystalline layers using targeted laser radiation, minimizing thermal load and mechanical stresses. This process creates strong, seamless bonds without the need for foreign atoms or ions, optimizing electrical properties and reducing process time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If heat treatment is applied to create bond strength, then bonding strength is improved, but thermal stresses and dopant diffusion increase
Solution Approach 1:
The patent changes the bonding mechanism from thermal activation to mechanical activation through ultrasonic vibration. Instead of using high temperature to activate bond formation, the invention uses ultrasonic mechanical energy to directly activate the bonding interface, thereby achieving strong bonds without thermal stresses and dopant diffusion
Solution Approach 2:
The patent replaces the thermal field (heat treatment) with a mechanical field (ultrasonic vibration). The ultrasonic bonding device uses mechanical vibration energy to activate bond formation at the interface between substrates, eliminating the need for thermal activation and its associated harmful effects
2Strength
If high temperature heat treatment is used for bonding, then bond strength is improved, but process time and energy consumption increase
Solution Approach 1:
The patent replaces thermal activation with mechanical ultrasonic activation. The ultrasonic bonding device delivers mechanical energy directly to the bonding interface, enabling rapid bond formation without the lengthy heating and cooling cycles required by traditional thermal bonding methods
Solution Approach 2:
The patent employs periodic ultrasonic vibration to activate bond formation. The oscillating mechanical energy from ultrasonic vibration continuously activates the bonding interface, enabling rapid and efficient bond formation without the prolonged thermal exposure required by conventional methods
3Reliability
If surface oxides are present on metal substrates, then bonding is hindered, but complete oxide removal is difficult
Solution Approach 1:
The patent applies preliminary mechanical activation through ultrasonic vibration to the bonding interface. This pre-treatment mechanically disrupts and removes surface oxides and contaminants before bonding, creating a clean interface that enables reliable bonding without requiring complex chemical etching or prolonged cleaning processes
Solution Approach 2:
The patent uses ultrasonic mechanical vibration to physically remove surface oxides from metal substrates. The high-frequency mechanical energy causes cavitation and micro-jetting effects that effectively strip oxide layers and contaminants from the bonding surface, enabling direct metal-to-metal 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
The method achieves efficient bonding at lower temperatures with reduced thermal and mechanical stresses, producing a nearly transition-free substrate stack with enhanced bond strength and electrical properties, while avoiding the use of foreign materials and minimizing dopant diffusion.
Implementation Method 1
the amorphous layer or the amorphous layers can be irradiated with radiation in such a way that the amorphous layer or the amorphous layers can be converted into a crystalline layer or crystalline layers
Implementation Method 2
the amorphous layer or the amorphous layers can be converted into a crystalline layer or crystalline layers
Implementation Method 3
The heat treatment leads to the formation of covalent bonds between the surfaces of the two substrates
Data Source
Figure 1a~2
Figure 3~4
Figure 5a~5c
AI summary
A method for bonding a first substrate (1, 6) to a second substrate (2) is proposed, comprising the following sequence: -creating a first amorphous layer (1a, 6a) on the first substrate (1, 6) and/or creating a second amorphous layer (2a) on the second substrate (2), - bonding the first substrate (1, 6) to the second substrate (2) at the amorphous layer (1a, 2a, 6a) or at the amorphous layers (1a, 2a, 6a) to form a substrate stack (3), - irradiating the amorphous layer (1a, 2a, 6a) or of the amorphous layers (1a, 2a, 6a) with a radiation (5) in such a way that the amorphous layer (1a, 2a, 6a) or the amorphous layers (1a, 2a, 6a) is/are converted into a crystalline layer or crystalline layers.