SiCOI Thin Films

Silicon carbide on insulator (SiCOI) thin film is an innovative composite material, typically prepared by coating a single crystal high-quality silicon carbide (SiC) thin layer (500-600 nm, depending on the specific application) on silicon-based silicon dioxide (SiO₂). SiC is renowned for its excellent thermal conductivity, high breakdown voltage, and outstanding chemical resistance. When this material is combined with the insulation layer, it can simultaneously meet the requirements of demanding applications such as high power, high frequency, and high temperature. SiCOI wafer structure is listed as follows. For additional information of SiCOI wafers, please feel free to consult our sales team at [email protected].

1. Specification of SiCOI Wafer

Layer	Thickness
Semi-insulating SiC	~1um
SiO2	–
Si Substrate	–

2. Preparation Progresses for SiCOI Wafer

The preparation of SiCOI thin films can be achieved through CMOS technology, such as bonding and smart cut, enabling seamless integration with existing electronic circuits.

2.1 Bonding Technology

Another preparation method is bonding technology, which applies pressure between SiC and Si wafers and uses the thermal oxide layer of the two wafers for bonding. However, the thermal oxidation layer of SiC may cause local defects at the SiC oxide interface, which may lead to increased light loss or the formation of charge traps. In addition, the silicon dioxide layer on SiC is usually prepared by plasma enhanced chemical vapor deposition (PECVD), which may also bring certain structural problems.

In order to overcome the above challenges, a new 3C-SiCOI chip manufacturing process has been proposed, which combines anodic bonding technology with borosilicate glass, thereby retaining all the functions of silicon microfabrication/CMOS and SiC photonics. In addition, amorphous SiC can also be directly deposited on SiO ₂/Si chips through PECVD or sputtering, thereby achieving simplified process integration. These methods are fully compatible with CMOS processes, further promoting the application of SiCOI in the field of photonics.

 2.2 Smart Cut (Ion Cut)

The smart cut technology has been applied to the large-scale production of silicon on insulator (SOI) chips. However, in the application of SiC, ion implantation may introduce damage that cannot be recovered by thermal annealing, resulting in excessive losses in the photonic structure. In addition, high-temperature annealing above 1000°C is not always compatible with certain application processes.

To solve these problems, grinding and chemical mechanical polishing (CMP) techniques can be used to directly thin the combined SiC and SiO₂/Si to<1 μm, thereby obtaining a smooth surface. Further thinning can be achieved through reactive ion etching, which can minimize losses in SiCOI structures to the greatest extent possible. Meanwhile, wet oxidation assisted CMP technology has been proven to significantly reduce surface roughness and scattering loss, while high-temperature annealing can further optimize chip quality.

Fig. 1 Ion Cutting Technological Process

3. Advantages of SiCOI Thin Films

Compared with the existing silicon on insulator (SOI), silicon nitride (SiN), and lithium niobate on insulator (LNOI) 3 material platforms, the SiCOI material platform exhibits significant advantages in optical applications and is becoming the next generation material platform for quantum technology. The specific advantages are as follows:

1) Exhibiting excellent transparency in the wavelength range of~400 nm to~5000 nm and achieving outstanding performance with waveguide loss<1 dB/cm;

2) Support multiple functions such as electro-optic modulation, thermal switching, frequency tuning, etc;

3) It exhibits second harmonic and other nonlinear optical properties and can serve as a single photon source platform based on color centers.

4. Applications of SiCOI Wafers

In addition, SiC on insulator combines the advantages of high thermal conductivity and high breakdown voltage of SiC with the good electrical isolation performance of insulators, and enhances the optical properties of the original SiC substrate. It is widely used in multiple high-tech fields such as integrated photonics, quantum optics, and power devices.

Based on this material, researchers have developed numerous high-quality photonic components, including linear waveguides, micro ring resonators, photonic crystal waveguides, microdisk resonators, electro-optic modulators, Mach Zehnder interferometers (MZIs), and beam splitters. These components have the characteristics of low loss and high performance, providing solid technical support for quantum communication, photon computing, and high-frequency power devices.

Whether you need SiCOI film for research or for industrial applications, please contact us email at [email protected] and [email protected].