Bonded SOI Wafer Gettering via Carbon-Induced Interface Defects
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Solution Overview
Problem
Conventional gettering techniques for SOI wafers are insufficient due to the insulating layer hindering heavy-metal impurity removal, leading to increased production costs and complex processes.
Innovation Solution
A method involving bonding SOI wafers in a state where organics exist on the surface, allowing carbon-induced micro crystal defects to form at the interface during heat treatment, which acts as a gettering source without adding extra processes, using pre-bonding SC-1 cleaning in an atmosphere containing N-methyl-2-pyrrolidone to trap organics and create crystal defects for effective impurity removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional gettering techniques are applied to SOI wafers with an insulating layer, then the structure provides electrical isolation, but the insulating layer hinders heavy-metal impurity movement resulting in insufficient gettering effect
Solution Approach 1:
The patent creates a localized gettering region at the interface between the insulating layer and the substrate by introducing crystal defects specifically at this boundary. The bulk insulating layer maintains its electrical isolation property, while the interface region acquires heavy-metal trapping capability through defect engineering, thus resolving the contradiction between electrical isolation and impurity removal.
Solution Approach 2:
The interface region acts as an intermediary between the insulating layer and the substrate, serving as a dedicated gettering zone. Crystal defects are introduced at this intermediate location to capture heavy-metal impurities that migrate from the substrate, allowing the insulating layer to maintain its electrical isolation function while the interface mediates the impurity removal process.
2Object-affected harmful factors
If a gettering source is formed at the interface between the SOI layer and the insulating layer, then effective heavy-metal impurity removal is achieved, but the manufacturing process becomes more complicated and production costs increase
Solution Approach 1:
The patent employs self-service by utilizing the existing insulating layer structure and introducing crystal defects through standard thermal processing. The interface region automatically serves as the gettering source without requiring additional deposited layers or complex processing steps, thus achieving effective impurity removal while avoiding increased manufacturing complexity.
Solution Approach 2:
The patent changes the physical-chemical parameters of the interface region by introducing crystal defects through thermal processing. This parameter change transforms the interface into an effective gettering source without altering the fundamental structure or adding complex manufacturing steps, thereby achieving impurity removal while maintaining process simplicity.
3Object-affected harmful factors
If carbon ions are implanted into the oxide film and heat treatment is performed to form precipitation nuclei, then a gettering source is created at the interface, but additional processes are required resulting in increased production cost
Solution Approach 1:
The patent extracts the carbon ion implantation step and replaces it with a simpler method of introducing crystal defects through thermal processing. By removing the expensive and time-consuming ion implantation process while maintaining the gettering function through interface defect creation, the production cost is reduced while still achieving effective heavy-metal impurity removal.
Solution Approach 2:
The patent uses a simple, low-cost thermal processing method instead of expensive carbon ion implantation. The crystal defects are created through a disposable, one-time heat treatment process that is much cheaper and faster than ion implantation, thereby reducing production cost while achieving the same gettering effect.
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 forms a simple and inexpensive gettering source at the SOI layer and insulating layer interface, effectively removing heavy-metal impurities and improving withstand voltage characteristics without increasing production costs.
Implementation Method 1
heat-treating for bonding reinforcement is performed in a state where organics are trapped at an interface between the active layer wafer and the supporting wafer with the oxide film to form carbon-induced micro crystal defects
Implementation Method 2
form carbon-induced micro crystal defects at an interface between the SOI layer and the oxide film
Implementation Method 3
performing pre-bonding SC-1 cleaning on the surface of the active layer wafer and/or on the surface of the supporting wafer with the oxide film
Implementation Method 4
heat-treating for bonding reinforcement is performed in a state where organics are trapped at an interface
Data Source
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AI summary
A bonded SOI wafer is manufactured by performing bonding in a state where organics exist on a surface of an active layer wafer and/or on a surface of a supporting wafer and performing heat-treating for bonding reinforcement in a state where the organics are trapped at an interface between the active layer wafer and the supporting wafer to form crystal defects at an interface between the active layer wafer and the oxide film and/or at an interface between the supporting wafer and the oxide film. This allows a simple and inexpensive gettering source to be formed at the interface between an SOI layer and an insulating layer (oxide film). Also, the bonded SOI wafer of the present invention that is manufactured by this method can effectively remove heavy-metal impurities that may have a negative impact on the characteristics of the device and/or the withstand voltage characteristics of the oxide film. Therefore, the manufacturing method and the bonded SOI wafer according to the present invention can be utilized widely as an SOI wafer with improved device characteristics or as a manufacturing method thereof.