What Scientific Research are Silicon on Sapphire (SoS) Wafers Used For?

university wafer substrates

Why Use Silicon-on-Sapphire (SoS) Wafers?

Most Silicon-to-Sapphire (SoS) devices are fabricated by a 1985 patented process by Armen Sahagen.  Devices include pressure transmitters, pressure transmitters, temperature sensors and membranes.  SoS technology is great for sensor technology resulting in  long-term stability. This is a major advantage over non-SoS-bound silicon sensors. New dielectric sensors made of silicon-on-sapphire (SoS) are attracting great interest and are being integrated into optical devices used in smartphones and tablets.    

UniversityWafer, Inc. and our partners Silicon-on-Sapphire Wafers (SoS), have EPI layers to control the thickness for extremely tight Total Thickness Variation (TTV) and flatness specs on Kyropoulos grown sapphires.

Silicon-on-Sapphire (SoS) wafers are compatible with standard semiconductor processing equipment.

Companies that Use Silicon Sapphire (SOS) Wafers

The subtrates benefits have been attacted companies, including Apple, Google, Microsoft, Samsung and Samsung Electronics.

Typical Silicon-on-Sapphire (SoS) Packaging for One Wafer

Silicon on Sapphire Wafers

Get your SoS Substrate Quote FAST!

Pre-cut 4'' Silicon-on-Sapphire (SOS) Wafer

We can pre-cut SoS wafers into diced pieces.

Sapphire thickness 460+/-25um,we have 400nm SOS based on 460um DSP R-sapphire,if need SSP SOS,we have it with >/=600nm Si on 460+/-25um SSP Sapphire.

diced silicon on sapphire wafers

Wafers for Metasurfaces Research

600nm thick Silicon deposited on on sapphire wafers have been used from research clients for their academic research metasurfaces.

Our Research Client States:

We will use e-beam lithography to fabricate designed silicon
nanostructures on the sapphire wafer, which is called as

Metasurfaces can be used to manipulate the wavefront,
propagation direction, or focusing of light.

Silicon-on-Sapphire Refractive Index

A researcher asks:

I am interested in Si on Sapphire Wafer(SOS) for some experiments. And I have a few questions. 1. I want to know the refractive index of Si for the light with wavelength of 850nm. Is it okay to think that your Si on wafer has the same refractive index as bulk crystalline silicon whose refractive index for 850nm is n=3.673 and k=0.005? If it is not correct, would it be possible to know the refractive index? 2. Does your company have an agency in Japan which I can buy through? I look forward to hearing from you soon.

UniversityWafer replied:

The refractive index shoud be the same, because the si film on sapphire was the same single crystal silicon <100>.

How to Commercialize Silicon-on-Sapphire (SoS) Wafers


Silicon on Sapphire (SoS) Applications

The advantage of sapphire is that it is an excellent electrical insulator, preventing stray currents caused by radiation from spreading to nearby circuit elements. When silicon is grown on sapphire, the resulting SoS substrate are used to fabricate IC devices. Often SoS wafers are used instead of Silicon-on-Insulator when a device requires less parasitic device capacitance, and increased device efficiency under high-temperatures.

But the problems with epitaxial silicon growth on sapphire wafers are lattice mismatch, discordant thermal expansion coefficients and limited silicon size. The Si-sapphire interface is home to a thick, defective region. After solid-phase epitaxial growth (SPER), Si is injected to reduce the density of defects. Two-phase epitaxial regrowth (SPER), film thinning and two-step epitaxy all provide sophisticated methods for material improvement. The bonding and Smartcut are the best methods to produce the highest quality SOS wafers.

Buy SoS wafers Online!

Analog-to-Digital Converters

Analog to Digital Converters

Monolithic Digital Isolation Buffers

Monolithic Digital Isolation Buffers

SOS-CMOS image sensor arrays

silicon on insulator cmos image sensor arrays

Patch-Clamp Amplifiers

Silicon on Sapphire patch clamp amplifiers

Energy Harvesting Devices

Silicon-on-Sapphire Energy Harvesting Devices

Three-Dimensional (3D) Integration with no Galvanic Connections

Silicon on Sapphire three diminsional integration without galvanic connections

Charge Pumps

Silicon-on-Sapphire (SoS) Charge Pumps

Temperature Sensors

Silicon-on-Sapphire (SoS) Temperature Sensors

Silicon-on-Sapphire R-Plane Al2O3

The 60° angle known as the R plane reveals the oxygen atoms in the crystal, and the distance between them is identical to that in the silicon crystal when silicon is deposited on the surface of the sapphire wafer. SOS is involved in epitaxial growth of silicon on a sapphire substrate (Al2O3).

Applications of this process are found in manufactured MOs and devices that include silicon cleaning processes to mitigate crystal defects resulting from mismatches in the sapphire silicon lattice.    

Below are just some of the Silicon-on-Sapphire Wafers that we have in stock!

Size (") Orientation Thick(μm) Pol Qty Grade Si Film Thickness
4 R-plane+/-0.5° 460+/-20 SSP 50 Prime 0.6um <100> Si
4 R-plane+/-0.5° 460+/-20 SSP 2 Prime 0.6um <100> Si
4 R-plane+/-0.5° 460+/-20 DSP 10 Prime 0.6um <100> Si
4 R-plane+/-0.5° 530+/-20 DSP 4 Prime 100+/-10nm <100> Si
4 R-plane+/-0.2° 530+/-20 DSP 4 Prime 230+/-10nm <100> Si
4 R-plane+/-0.2° 530+/-20 DSP 4 Prime 1.5+/-0.15um <100> Si
4 R-plane+/-0.5° 460+/-20 SSP 4 Dummy  
6 R-plane+/-1° 600+/-20 SSP 1    
8 R-plane+/-2° 725+/-20 SSP 1    

SoS wafers to Fabricate Dielectric Resonantors

A new dielectric sensor fabricated from Silicon-on-Silicon (SOS) is attracting great interest as an integrated optical device for use in smartphones and tablets.

Scientists are reseaching fabricating dielectric resonator capable of maximising the maximum power of the sensor and its optical properties in the form of an optical sensor using SoS.

What are Silicon-on-Sapphire Wafers Used For?

Researchers have used the following SoS wafer specs to fabricate photonic crystal structures using e-beam lithography.

1 item of Pre-cut 4" Silicon on Sapphire Wafer, DSP, 100nm of Si film layer.

Qty. one wafer
dicing into 10x10mm chips.
Silicon orientation is 100

We use these substrates to fabricate photonic crystal structures using e-beam lithography. Before we ordered Si on Insulator substrates with 70 nm film of Si from you and they worked pretty well for fabrication of photonic crystals which operate in visible wavelength range. However, the presence of BOX in SOI substrates gives rise to Fabry Perot modes which overlay with our photonic modes, which worsens the contrast. That's why we need to switch to the substrate without an intermediate layer, like SOS substrate. A while ago we ordered SOS wafer from you, but with 230 nm of Si film. This thickness is too large for our project in visible range, so we are trying to reduce it somehow. We are not very experienced in that, we have tried the plasma etching of Si, but it leads to not very good quality of surface. We think also to try chemical etching of Si. Maybe you can suggest any good solution for this problem? Of course, other option for us is to buy SOS substrate with the thinnest Si film, but it appears too pricy for us, especially because we are not very large research group and we do not need the whole 4" wafer for this one specific project. Hopefully, I answered you questions. I will appreciate any suggestions from your side.

Silicon-on-Sapphier (SoS) for Photonic Waveguides

A larger university researcher was interested in SoS wafers for their work on Photonic waveguides. The researcher asked:

I have some questions that I would like to get answered first: What is the resistivity of the Si layer? Is it possible to get Si resistivities in the order of >3000 Ohm.cm? What is the Si crystal orientation in relation to primary flat for the R plane sapphire wafers? What is the purity of the EPI grown Si crystal? What can we expect in terms of monocrystallinity of the Si layer? What is the minimum qty for purchase? What is the lead time? If you have any other information for me I would love to hear it. Looking forward to your response! 

UniversityWafer, Inc. Quoted our Thin SoS:

Pls see below for the offer on thin SOS Wafer

Dia.(inch) Orientation Si film thick. Surface Resistivity Substrate Thick
4'' R+/-0.5deg 200+/-10nm P/P $Conact us>100 Ohm.cm 460+/-20um
4'' R+/-0.5deg 300+/-10nm P/P $Conact us>100 Ohm.cm 460+/-20um