Room-Temperature Bonding for SOI Wafer on Transparent Substrate
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Solution Overview
Problem
The manufacturing of SOI wafers on transparent insulation substrates faces challenges with thermal deformation, flaking, and cracking due to differences in thermal expansion coefficients, and light leak currents in semiconductor devices caused by transparent substrates.
Innovation Solution
A method involving growing single crystal silicon with an N region surface using the Czochralski method, forming an ion injection layer, processing surfaces with plasma and/or ozone, and bonding at room temperature to achieve firm hydrogen bonding without high-temperature thermal processing, followed by mechanical peeling to form a thin SOI layer, which restricts light leak currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thermal processing at high temperature 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 coefficients
Solution Approach 1:
The patent changes the bonding temperature parameter from high temperature to room temperature, eliminating thermal expansion mismatch issues. The bonding strength is maintained through surface activation methods (plasma treatment, ozone treatment, or chemical treatment) that create strong chemical bonds without thermal stress, thereby resolving the contradiction between achieving strong bonding and preventing thermal deformation/cracking
Solution Approach 2:
The patent replaces the thermal bonding mechanism with a chemical bonding mechanism. Instead of using heat to activate bonding, the invention uses surface treatment methods (plasma, ozone, or chemical etching) to activate surface groups that form strong chemical bonds at room temperature, substituting the thermal field with chemical field to avoid thermal expansion problems
2Illumination intensity
If transparent silica substrate is used for optical devices, then optical performance is improved, but light leak current occurs in MOSFET channel region
Solution Approach 1:
The patent introduces an intermediate layer (black silicon layer or metal film) between the transparent silica substrate and the SOI layer. This intermediary layer blocks light from reaching the MOSFET channel region while maintaining the optical transparency of the overall structure for device operation, thereby resolving the contradiction between optical performance and light leak prevention
Solution Approach 2:
The patent applies local quality modification by creating a specific region (black silicon layer) with different optical properties (light-absorbing) in a localized area where light blocking is needed, while the rest of the substrate maintains its transparent quality for optical device functionality. This allows simultaneous achievement of optical performance and light leak prevention in different regions
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 ensures strong bonding without thermal deformation, flaking, or cracking, resulting in an SOI wafer with high carrier mobility and excellent crystallization, suitable for optical devices like TFT-LCDs, while minimizing light leak current issues.
Implementation Method 1
growing a single crystal silicon whose entire surface is an N region on an outer side of an OSF region, using a Czochralski method
Implementation Method 2
processing the ion injection surface of the N region single crystal silicon wafer and/or a surface of the transparent insulation substrate using plasma and/or ozone
Implementation Method 3
processing the ion injection surface of the N region single crystal silicon wafer and/or a surface of the transparent insulation substrate using plasma and/or ozone
Implementation Method 4
forming an ion injection layer within the N region single crystal silicon wafer, by injecting at least one of a hydrogen ion and a rare gas ion from a surface of the N region single crystal silicon wafer
Implementation Method 5
forming an SOI layer on the transparent insulation substrate, by mechanically peeling the single crystal silicon wafer by giving an impact to the ion injection layer
Data Source
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AI summary
In a manufacturing method for manufacturing an SOI wafer, a single crystal silicon whose entire surface is an N region on an outer side of an OSF region, is grown using a Czochralski method and sliced to fabricate an N region single crystal silicon; an ion injection layer is formed within the N region single crystal silicon wafer, by injecting a hydrogen ion or a rare gas ion from a surface of the N region single crystal silicon wafer; the ion injection surface of the N region single crystal silicon wafer and/or a surface of the transparent insulation substrate is processed using plasma and/or ozone; the ion injection surface of the N region single crystal silicon wafer is bonded to the surface of the transparent insulation substrate, by bringing them into close contact with each other at room temperature, with the processed surface(s) as bonding surface(s); and an SOI layer is formed on the transparent insulation substrate, by mechanically peeling the single crystal silicon wafer by giving an impact to the ion injection layer.