SOI Wafer Room-Temperature Bonding via Plasma Activation
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Solution Overview
Problem
The manufacturing of SOI wafers with an SOI layer on transparent insulation substrates faces challenges due to thermal deformation, flaking, and cracking caused by differences in thermal expansion coefficients between the substrate and the SOI layer, which existing methods struggle to address effectively.
Innovation Solution
A method involving the formation of an ion injection layer in the single crystal silicon wafer, followed by plasma or ozone processing of the surfaces, room-temperature bonding to a transparent insulation substrate, mechanical peeling to form the SOI layer, and subsequent thermal processing in an inert gas atmosphere to flatten and refine the surface, thereby avoiding high-temperature thermal processing and its associated stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high temperature thermal processing is performed to enhance bonding strength between silica substrate and SOI layer, then bonding strength is improved, but thermal deformation, cracking, or flaking occurs due to difference in thermal expansion coefficient
Solution Approach 1:
The invention changes the bonding temperature parameter from high temperature to room temperature, eliminating thermal expansion mismatch issues. The bonding strength is maintained through surface activation treatments (plasma or ozone) that create reactive surface groups for strong adhesion without requiring thermal energy
Solution Approach 2:
The invention performs preliminary surface treatment (plasma or ozone processing) before bonding to activate the surface and enhance adhesion. This preliminary action ensures strong bonding occurs at room temperature, preventing subsequent thermal stress-related defects during cooling or processing
2Reliability
If room temperature bonding is performed to avoid thermal stress, then thermal deformation and cracking are prevented, but bonding strength may be insufficient
Solution Approach 1:
The invention changes the bonding temperature parameter from high temperature to room temperature, eliminating thermal expansion mismatch issues. The bonding strength is maintained through surface activation treatments (plasma or ozone) that create reactive surface groups for strong adhesion without requiring thermal energy
Solution Approach 2:
The invention uses ozone (a strong oxidant) or plasma to oxidize and activate the bonding surfaces, creating hydroxyl groups and other reactive species that form strong chemical bonds upon contact. This accelerated oxidation at room temperature ensures sufficient bonding strength without thermal processing
3Manufacturing precision
If thin SOI layer is formed to achieve desired thickness, then device performance is improved, but bonding strength must be sufficiently strong to endure grinding and polishing
Solution Approach 1:
The invention changes the bonding temperature parameter from high temperature to room temperature, eliminating thermal expansion mismatch issues. The bonding strength is maintained through surface activation treatments (plasma or ozone) that create reactive surface groups for strong adhesion without requiring thermal energy
Solution Approach 2:
The invention performs preliminary surface treatment (plasma or ozone processing) before bonding to activate the surface and enhance adhesion. This preliminary action ensures strong bonding occurs at room temperature, preventing subsequent thermal stress-related defects during cooling or processing
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 ensures strong, stress-free bonding, achieves a thin and even SOI layer with excellent crystallization and high carrier mobility, preventing thermal deformation and surface defects, and allows for the production of SOI wafers suitable for high-density semiconductor and optical devices.
Implementation Method 1
a step of forming an ion injection layer within the single crystal silicon wafer, by injecting at least one of a hydrogen ion and a rare gas ion from a surface of the single crystal silicon wafer
Implementation Method 2
a step of processing the ion injection surface of the single crystal silicon wafer and/or a surface of the transparent insulation substrate using plasma or ozone
Implementation Method 3
a step of processing the ion injection surface of the single crystal silicon wafer and/or a surface of the transparent insulation substrate using plasma or ozone
Implementation Method 4
a step of bonding the ion injection surface of the single crystal silicon wafer to a surface of the transparent insulation substrate, by bringing them into contact with each other in a room temperature, with the processed surface(s) as bonding surface(s)
Implementation Method 5
a step of obtaining an SOI wafer, by mechanically peeling the single crystal silicon wafer by giving an impact to the ion injection layer, to form an SOI layer on the transparent insulation substrate
Implementation Method 6
a step of performing thermal processing for flattening a surface of the SOI layer, to the resulting SOI wafer, under an atmosphere of an inert gas, a hydrogen gas, or a mixture gas of the inert gas and the hydrogen gas
Data Source
Figure 1(A)~1(J)
AI summary
Ion injection is performed to a single crystal silicon wafer to form an ion injection layer, the ion injection surface of the single crystal silicon wafer and/or the surface of the transparent insulation substrate are/is processed using plasma and/or ozone, the ion injection surface of the single crystal silicon wafer and the surface of the transparent insulation substrate are bonded to each other, by bringing them into close contact with each other at room temperature, with the ion injection surface and the surface as bonding surfaces, an SOI wafer is obtained by mechanically peeling the single crystal silicon wafer by giving an impact to the ion injection layer, to form an SOI layer on the transparent insulation substrate, and thermal processing for flattening the SOI layer surface is performed to the SOI wafer, under an atmosphere of an inert gas, a hydrogen gas, and a mixture gas of them.