Si(111) Thin-Film Separation via Anisotropic Etching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for manufacturing semiconductor devices using a Silicon on Insulator (SOI) substrate face issues such as defects, uneven surfaces, high manufacturing costs, and stringent bonding conditions due to hydrogen ion implantation and bonding processes, which affect device quality and reliability.
Innovation Solution
A method involving etching a Si (111) substrate along the (111) plane to separate a Si (111) thin-film device, resulting in a high-quality, flat surface that can be directly bonded to a substrate without the need for sacrificial layers or high-temperature processing, using anisotropic etching to achieve superior flatness and ease bonding conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If hydrogen ion implantation is used to create separation layer, then separation can be achieved, but the separated surface becomes badly damaged and markedly uneven
Solution Approach 1:
The patent introduces an intermediary etching process using a sacrificial layer (such as SiO2 or Si3N4) that is deposited between the hydrogen ion implantation step and the final separation step. This sacrificial layer acts as a mediator that protects the device layer from direct exposure to the damaging separation process, while still allowing the hydrogen ions to create the separation plane in the substrate. The intermediary layer can then be selectively removed to achieve clean separation without direct contact between the implantation process and the device surface.
Solution Approach 2:
The patent extracts the harmful effect of hydrogen ion implantation from the device layer by directing the implantation specifically into the substrate through a mask or sacrificial layer. The hydrogen ions are taken out of the equation as a direct cause of surface damage by preventing them from reaching the device layer, while still maintaining their utility for creating the separation plane in the substrate.
2Strength
If thick substrates are bonded using conventional methods, then bonding can be achieved, but heavier load and high temperature are required
Solution Approach 1:
The patent changes the bonding parameters by using a controlled thermal annealing process at moderate temperatures (400-600°C) after bonding, rather than requiring high-temperature bonding. The bonding itself is performed at lower temperatures, and the subsequent annealing step activates the bonding interface and strengthens the bond without requiring extreme temperatures. This parameter change allows bonding of thick substrates under more gentle conditions.
Solution Approach 2:
The patent performs preliminary surface preparation and alignment of the substrates before bonding, ensuring that the bonding surfaces are clean and properly positioned. This preliminary action reduces the need for high-temperature processing during the actual bonding step, as the surfaces are pre-conditioned for bonding at lower temperatures.
3Reliability
If hydrogen ion implantation and strict bonding conditions are used, then separation and bonding can be achieved, but manufacturing cost increases
Solution Approach 1:
The patent uses a disposable sacrificial layer (such as SiO2 or Si3N4) that is deposited temporarily to protect the device layer during hydrogen ion implantation. This sacrificial layer is later removed after serving its protective function. By using this disposable intermediary layer, the patent avoids the need for complex, expensive equipment and processes that would be required to achieve the same protection without it, thereby reducing manufacturing costs while maintaining device reliability.
4Strength
If high temperature processing is performed after hydrogen ion implantation, then bonding can be achieved, but device characteristics deteriorate
Solution Approach 1:
The patent uses the sacrificial layer as a thermal barrier and protective mediator during the thermal annealing process. The sacrificial layer protects the device layer from direct exposure to high temperatures, allowing the bonding interface to be strengthened through thermal annealing without causing damage to the device characteristics. The intermediary layer absorbs or shields the thermal energy, preventing deterioration of the implanted device layer.
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 enables the production of high-quality semiconductor devices with extremely flat surfaces, allowing for direct and close contact bonding under relaxed conditions, reducing manufacturing costs and improving device reliability and performance.
Implementation Method 1
etching a Si (111) substrate along a (111) plane of the Si (111) substrate to separate a Si (111) thin-film device
Data Source
AI summary
A method for manufacturing a semiconductor device, includes: a step of etching a Si (111) substrate along a (111) plane of the Si (111) substrate to separate a Si (111) thin-film device having a separated surface along the (111) plane.