Amorphized Substrate Surfaces for Low-Temperature Oxide-Free Bonding
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Solution Overview
Problem
The semiconductor industry faces challenges in achieving optimal bonding at low temperatures without thermal degradation, particularly with oxygen-affine metals that form stable oxides, which hinder bonding and require high-energy processes that are costly and inefficient.
Innovation Solution
A method involving the amorphization of substrate surfaces using low-energy particle bombardment to create a nanometer-thick amorphous layer, which allows for simultaneous purification and surface smoothing, enabling strong bonding at lower temperatures by eliminating oxides and ensuring full contact between substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high-energy processes are used to bond oxygen-affine metals, then bonding strength is improved, but thermal degradation and process cost increase
Solution Approach 1:
The patent applies preliminary surface treatment (amorphization and purification) to substrate surfaces before bonding. By pre-treating surfaces to remove oxides and create amorphous layers, the actual bonding process can proceed at lower temperatures without thermal degradation, while still achieving strong bonds. This resolves the contradiction by preparing surfaces in advance so that high bonding strength can be achieved without high temperature processes.
Solution Approach 2:
The patent changes the physical state of surface layers from crystalline to amorphous through ion bombardment. This parameter change in surface structure enables bonding at lower temperatures while maintaining or improving bonding strength. The amorphous surface layer has different properties that facilitate low-temperature bonding, resolving the contradiction between bonding strength and thermal degradation.
2Loss of substance
If high-energy processes are used to remove oxides, then oxide removal is improved, but process cost and energy consumption increase
Solution Approach 1:
The patent replaces high-energy mechanical/thermal oxide removal processes with a chemical/electrical process involving ion bombardment and electrochemical reactions. The ion beam induces electrochemical reactions that selectively remove oxides at lower energy consumption. This substitution resolves the contradiction by achieving effective oxide removal through a different mechanism that consumes less energy.
Solution Approach 2:
The patent introduces ions as an intermediary medium to facilitate oxide removal. These ions act as mediators that transfer energy and induce electrochemical reactions at the surface, enabling selective oxide removal without requiring high-energy direct heating or mechanical processes. This intermediary approach resolves the contradiction between oxide removal efficiency and energy consumption.
3Reliability
If amorphous layers are created on substrate surfaces, then bonding quality is improved, but surface roughness increases
Solution Approach 1:
The patent applies local quality changes by creating amorphous layers only at the bonding interfaces rather than throughout the entire substrate. The amorphization is localized to surface regions where bonding occurs, improving bonding quality at the interface while minimizing the overall impact on surface geometry. This localized approach resolves the contradiction by confining the amorphous structure to where it provides benefit.
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 approach enhances bonding strength, reduces thermal stress, and prevents oxide incorporation, allowing for efficient bonding of various materials, including metals and semiconductors, with improved mechanical and electrical properties.
Implementation Method 1
Surface areas, in particular a contact side (preferably over the entire surface) of the two substrates or of at least one of the two substrates, are amorphized before the bonding process
Implementation Method 2
A method involving the amorphization of substrate surfaces using low-energy particle bombardment to create a nanometer-thick amorphous layer, which allows for simultaneous purification and surface smoothing
Implementation Method 3
A method for permanent bonding of two substrates, of which at least one, preferably two, was/were treated before the bonding as described below
Data Source
AI summary
A method for surface treatment of an at least primarily crystalline substrate surface of a substrate such that by amorphization of the substrate surface, an amorphous layer is formed at the substrate surface with a thickness d>0 nm of the amorphous layer. This invention also relates to a corresponding device for surface treatment of substrates.