Substrates for mm-Wave Research

university wafer substrates

Thin Silicon for mm-Wave Research

A senior research scientist requested a quote for the following:

I have some specific requirements (I am using these as sub mm-wave 50-50 beam splitters) with regard to thickness.  I need 64.2 microns for a 4" thin silicon wafer.  What would be the cost and availability?

A: Inventory wafers allows us to provide:

64um+/-1um doable. 4”, CZ, <100>, N-type, 1-10 ohm.cm.

B: For the same 64um+/-1um thickness, other specification for P-type, and other resistivity will be done in a customized base.

Reference #121952 for specs and pricing.

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Silicon as a Dichroic Beam Combinder

A PhD candidate requested a quote for the following:

I am thinking to use a Si wafer as a dichroic beam combiner for visible light (to be reflected off the polished side of a Si wafer) and mm-wave radiation (to be transmitted through said wafer.)

The resistivity needs to be rather high to mitigate free-carrier absorption of the mm-wave signal. Also, the roughness on the less-polished side needs to be a small fraction of the wavelength (which would be ~ 1mm. I am thinking 10 micron RMS might be good enough. Or we could splurge and get double-side polished.)

I sorted your list at on your store according to resistivity. Most of the entries mentioned FZ ("float zone.") Would you please explain what that is, and/or refer me to a textbook or website or something? I am willing to visit the library, as appropriate.

UniversityWafer, Inc. Quoted:

FZ stands for Float Zone, which is a growth method, most silicon wafers are either FZ (Float Zone grown) or CZ (​Czochralski method grown). FZ items are usually more expensive than CZ items.

We have this Intrinsic (undoped) FZ item that is DSP (Double Side Polished):

Item # 2272: Silicon 100mm diameter, Undoped, <100>, FZ >20,000 ohm-cm 500um DSP

 

What is mm-Wave?

Millimeter-wave (mm-Wave) refers to a segment of the electromagnetic spectrum with wavelengths between 1 millimeter and 10 millimeters, corresponding to frequencies roughly between 30 GHz and 300 GHz. This range is situated between microwave and infrared frequencies and is characterized by its high frequency and short wavelength.

Key Features of mm-Wave:

  1. High Frequency: mm-Wave frequencies range from 30 GHz to 300 GHz, which allows for high data transmission rates.
  2. Short Wavelength: The short wavelength enables the use of smaller antennas and tighter beamforming, facilitating high-precision targeting of signals.
  3. High Bandwidth: The wide bandwidth available in the mm-Wave spectrum supports high-capacity data transfer and a large number of users.

Applications of mm-Wave Technology:

  1. 5G and Beyond: mm-Wave bands are crucial for the development of 5G networks, providing extremely various applications of mm-Wave technologhigh-speed wireless communication and supporting high-density data transmission.
  2. High-Resolution Imaging: Used in applications such as security scanning, medical imaging, and automotive radar systems.
  3. Wireless Backhaul: Provides high-capacity links between cell towers and core networks, supporting the infrastructure of mobile networks.
  4. Satellite Communications: Enables high-speed communication links for satellite-to-ground and inter-satellite communications.
  5. Remote Sensing: Applied in environmental monitoring, weather prediction, and atmospheric research due to its sensitivity to moisture and other atmospheric constituents.
  6. Industrial and Consumer Electronics: Facilitates high-speed wireless data transfer for devices like virtual reality (VR) headsets, high-definition video streaming, and wireless docking stations.

Challenges of mm-Wave Technology:

  1. Propagation Loss: mm-Wave signals experience higher attenuation and are more susceptible to obstacles like buildings, foliage, and even rain, leading to shorter range compared to lower frequency signals.
  2. Penetration Issues: The high frequency of mm-Wave signals limits their ability to penetrate walls and other solid objects.
  3. Line-of-Sight Requirement: Effective mm-Wave communication often requires a clear line-of-sight between the transmitter and receiver.
  4. Technological Complexity: The design and fabrication of mm-Wave components and systems are more complex and expensive due to the high frequencies involved.

Advancements in mm-Wave Technology:

To overcome these challenges, various advancements are being made, such as:

  • Beamforming: Using multiple antennas to direct signals in specific directions, enhancing signal strength and reducing interference.
  • Advanced Materials and Devices: Developing new semiconductor materials and device architectures to improve performance and reduce costs.
  • Network Densification: Increasing the number of small cells and access points to ensure better coverage and capacity in urban and dense environments.

Overall, mm-Wave technology is a critical enabler of future communication systems and various advanced applications, offering unprecedented speed and capacity while presenting unique technical challenges.