Microwave Silicon Nanostructure Deposition Assembly
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Solution Overview
Problem
The VLS process for growing silicon nanowires is incompatible with CMOS integrated circuits due to high growth temperatures, which can compromise the integrated circuit components.
Innovation Solution
An assembly that heats only the nanometric droplets of the catalyst to a higher temperature, while keeping the substrate at a temperature below 250°C, using a microwave-generated electromagnetic field and a dielectric substrate-carrier support to separate the substrate from the heating termination wall, preventing excessive heating of the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the VLS process is used to grow silicon nanowires, then high growth temperatures are achieved, but the integrated circuit components are compromised
Solution Approach 1:
The system segments the heating function by introducing a separate susceptor layer that can be independently heated by microwave radiation. This allows the substrate to be heated to high temperatures only in specific regions where nanowire growth is desired, while other areas remain at lower temperatures to protect integrated circuit components. The susceptor layer acts as an independent heating element that decouples the temperature control of the growth region from the rest of the substrate.
Solution Approach 2:
The susceptor layer serves as an intermediary between the microwave radiation source and the substrate. It absorbs microwave energy and converts it to thermal energy, which is then transferred to the substrate in a controlled manner. This intermediary layer enables selective heating of the substrate surface without requiring bulk heating of the entire substrate, thus protecting temperature-sensitive integrated circuit components while providing sufficient heat for nanowire growth.
2Ease of manufacture
If the entire substrate is heated to activate VLP deposition, then silicon nanowire growth is enabled, but the integrated circuit is damaged
Solution Approach 1:
The system implements local quality by creating regions of different thermal properties on the substrate. The susceptor layer is deposited only in specific patterns or regions where nanowire growth is desired, creating local zones with high microwave absorption capability. This allows the substrate to exhibit different thermal responses in different areas: high temperature in susceptor regions for nanowire growth, and low temperature in non-susceptor regions to protect integrated circuits from thermal damage.
Solution Approach 2:
The system introduces dynamic control of the heating process through microwave irradiation. The microwave power can be adjusted, pulsed, or focused on specific regions to dynamically control the temperature distribution during the deposition process. This dynamic control allows the substrate temperature to be raised quickly to the required growth temperature and then maintained or reduced as needed, preventing thermal damage to temperature-sensitive circuit components.
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 growth of silicon nanostructures at low temperatures, compatible with CMOS integrated circuits, ensuring the integrity of the circuit and allowing for the production of sensitive sensors and other nanodevices.
Implementation Method 1
a microwave generator (5) for the production of electromagnetic radiation
Implementation Method 2
an electromagnetic termination wall (8), made of conducting material, reflecting the electromagnetic radiation and arranged to heat the layer of nanometric droplets
Implementation Method 3
a substrate-carrier support (9) made of dielectric material and adapted to maintain the substrate (S) in a position separate from the termination wall (8)
Implementation Method 4
the growth of silicon nanostructures occurs through the process known as VLS (vapour-liquid-solid). The name VLS refers to the fact that the process entails the silicon in vapour form passing into the liquid phase through a droplet of catalyst metal and, lastly, terminating as a solid
Data Source
AI summary
An assembly for the deposition of silicon nanostructures comprising a deposition chamber, which is defined by a side wall and by two end walls; a microwave generator, which is adapted to generate microwaves inside the deposition chamber; an electromagnetic termination wall, made of a conductor material and reflecting the microwave radiation, which is such as to create a termination for a TE-mode waveguide and is housed inside the deposition chamber; and a substrate-carrier support, which is made of a dielectric material and on which the substrate is housed on which to perform the growth of silicon nanostructures. The substrate-carrier support is arranged inside the deposition chamber above the termination wall.


