Multilayer MEMS Component Monocrystalline Silicon Integration
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Solution Overview
Problem
Existing methods for manufacturing multi-layer MEMS components struggle to integrate monocrystalline layers with minimal thickness variability into polycrystalline layer systems, limiting the combination of high thermal conductivity and mechanical properties, and preventing the formation of specific layer configurations like polycrystalline silicon/oxide/monocrystalline silicon/oxide/polycrystalline silicon.
Innovation Solution
A method that allows for the integration of monocrystalline layers with minimal thickness variability into polycrystalline layer systems by embedding a thin monocrystalline Si layer between two polycrystalline layers, enabling the combination of enhanced thermal conductivity and mechanical properties, and allowing for flexible positioning and thickness variations of polycrystalline layers above and below the monocrystalline layer, along with electrical contacting and insulation through patterned regions and sacrificial layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If epitaxy is used to grow silicon layers, then monocrystalline growth is achieved on monocrystalline substrates, but polycrystalline growth occurs on amorphous layers requiring seed layers
Solution Approach 1:
Instead of growing monocrystalline silicon on amorphous oxide layers through conventional epitaxy (which requires seed layers), the patent inverts the approach by bonding a monocrystalline silicon wafer to the polycrystalline layer, allowing the monocrystalline structure to be transferred and grown directly on the amorphous layer without requiring a seed layer.
Solution Approach 2:
The patent introduces a bonding layer as an intermediary between the monocrystalline silicon wafer and the amorphous oxide layer. This bonding layer facilitates the bonding process and enables the transfer of the monocrystalline structure to the amorphous layer, solving the incompatibility between epitaxy requirements and amorphous substrate properties.
2Reliability
If monocrystalline silicon layers are integrated into polycrystalline layer systems, then thermal conductivity is improved, but layer configuration flexibility is limited
Solution Approach 1:
The patent segments the layer system into distinct polycrystalline and monocrystalline regions, allowing the monocrystalline silicon layer to be strategically positioned within the polycrystalline structure. This segmentation enables thermal management in specific regions while maintaining polycrystalline structures in other areas, thus achieving both improved thermal conductivity and configuration flexibility.
Solution Approach 2:
The patent applies local quality by introducing monocrystalline silicon specifically in regions where high thermal conductivity is required, while maintaining polycrystalline structures in other regions. This localized approach allows optimization of thermal properties in specific areas without compromising the overall flexibility of the layer configuration.
3Manufacturing precision
If silicon direct bonding is used to bond monocrystalline and polycrystalline layers, then layer thickness uniformity is improved, but process complexity increases
Solution Approach 1:
The patent performs preliminary actions by preparing the bonding surfaces of the monocrystalline silicon wafer and the amorphous oxide layer before bonding. This includes cleaning, oxidation, and other surface treatments that ensure optimal bonding conditions, thereby achieving uniform layer thickness while managing process complexity through systematic preparation 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
Enables the creation of multi-layer MEMS components with improved thermal conductivity and mechanical properties, allowing for precise layer positioning and electrical contacting, while maintaining thickness uniformity and enabling the formation of complex layer configurations.
Implementation Method 1
Silicon direct bonding has been known since 1986. Here two wafers are brought into contact under high pressure.
Implementation Method 2
Here a disruption layer is generated at the desired location in the substrate by hydrogen ion implantation; upon subsequent heating, that layer results in cracks so that the wafer can be spalled or split off in that region.
Implementation Method 3
upon subsequent heating, that layer results in cracks so that the wafer can be spalled or split off
Implementation Method 4
to manufacture a monocrystalline Si layer from polycrystalline silicon by laser recrystallization
Implementation Method 5
Many semiconductor processes require epitaxial growth of a silicon layer onto a substrate wafer or an insulation layer such as an oxide or nitride. While epitaxy on a monocrystalline silicon layer results in monocrystalline growth, epitaxy does not function directly on an amorphous layer
Data Source
AI summary
A method for manufacturing a multi-layer MEMS component includes: providing a multi-layer substrate that has a monocrystalline carrier layer, a monocrystalline functional layer having a front side and a back side, and a bonding layer located between the back side and the carrier layer; growing a first polycrystalline layer over the front side of the monocrystalline functional layer; removing the monocrystalline carrier layer; and growing a second polycrystalline layer over the back side of the monocrystalline functional layer.