SOI Substrate Gettering via Bonded SiO2 Defect Engineering
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Solution Overview
Problem
SOI substrates face challenges in effectively capturing and removing metal impurities due to the slow diffusion rate of metal impurities through the silicon oxide film, leading to serious contamination issues and reduced productivity in existing gettering techniques.
Innovation Solution
A method involving the formation of a silicon oxide film on at least one of the single-crystal silicon substrates, followed by bonding and a heat treatment within specific temperature ranges to enhance the bonding interface's gettering ability, without adding additional processing steps, thereby creating a high-gettering ability SOI substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional gettering techniques (oxide precipitates, high-concentration boron addition, polysilicon film) are introduced on the support substrate side, then the gettering layer is formed, but the metal impurity cannot sufficiently pass through the BOX layer to reach the gettering layer, resulting in poor gettering function
Solution Approach 1:
The patent changes the physical and chemical parameters of the silicon oxide film by controlling oxygen concentration (1×10^19 to 1×10^21 atoms/cm³) and creating specific defect structures through controlled oxidation and heat treatment. This transforms the BOX layer from a simple insulator into an active gettering medium that can capture metal impurities through defect-mediated trapping mechanisms, resolving the contradiction between maintaining BOX layer integrity and enabling impurity capture.
Solution Approach 2:
The patent introduces oxygen-rich regions and defect structures as intermediary mechanisms within the silicon oxide film. These intermediaries serve as trapping sites that can capture metal impurities without requiring the impurities to diffuse through the entire BOX layer thickness, thus enabling effective gettering while maintaining the electrical isolation function of the BOX layer.
2Reliability
If additional processing steps are added to introduce gettering layers or impurity regions, then the gettering ability is improved, but the number of processing steps increases, leading to reduced productivity and increased cost
Solution Approach 1:
The patent makes the silicon oxide film serve multiple functions: it maintains its role as an electrical insulator (BOX layer) while simultaneously functioning as a gettering layer through controlled oxygen concentration and defect engineering. This multi-functionality eliminates the need for separate gettering layer formation steps, preserving productivity while achieving effective metal impurity capture.
Solution Approach 2:
The patent merges the BOX layer and gettering layer functions into a single silicon oxide film structure. By creating oxygen-rich regions and defects within the existing BOX layer through controlled oxidation and heat treatment, the patent combines the electrical isolation function with the metal impurity capture function, eliminating redundant processing steps.
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 efficiently manufactures SOI substrates with excellent gettering ability for metal impurities, maintaining high bonding strength and avoiding electrical characteristic degradation, while reducing costs and maintaining productivity.
Implementation Method 1
performing a heat treatment for holding at a temperature falling within the range of at least 950°C to 1100°C set to the range of 1 hour to 4 hours and then carrying out a heat treatment at a temperature higher than 1100°C when effecting a bonding heat treatment for increasing bonding strength
Implementation Method 2
a diffusion rate of a metal impurity is slow in the silicon oxide film rather than in silicon
Implementation Method 3
an oxide film is formed on a surface of at least one silicon substrate
Data Source
Figure 1(a)~1(d)
Figure 2
Figure 3(a)~3(e)
AI summary
According to the present invention, there is provided a method for manufacturing an SOI substrate based on a bonding method, comprising at least: forming a silicon oxide film on a surface of at least one of a single-crystal silicon substrate that becomes an SOI layer and a single-crystal silicon substrate that becomes a support substrate; bonding the single-crystal silicon substrate that becomes the SOI layer to the single-crystal silicon substrate that becomes the support substrate through the silicon oxide film; and performing a heat treatment for holding at a temperature falling within the range of at least 950°C to 1100°C and then carrying out a heat treatment at a temperature higher than 1100°C when effecting a bonding heat treatment for increasing bonding strength As a result, there are provided the method for manufacturing an SOI substrate that can efficiently manufacture an SOI substrate having an excellent gettering ability with respect to metal contamination in an SOI layer, and the SOI substrate.