Ultra-low temperature silicon nitride photonic integration platform

Abstract

High-quality SiNx films with controllable low stress and low optical loss are deposited at ultra-low temperature (75 °C) using inductively coupled plasma chemical vapor deposition (ICP-CVD). Two kinds of integrated photonic structures have been demonstrated that exemplify its viability as a photonic integration platform. A microcavity consists of two distributed Bragg reflectors (DBR) formed by alternating a total of 49 layers of SiNx and SiO2 with a total thickness of about 11.5 μm is grown without any cracks, confirming the excellent stress control in the process. Microring resonators are also fabricated in as-deposited planar SiNx waveguide layer using electron-beam lithography (EBL) and plasma etching. Average waveguide loss of 0.79 ± 0.22 dB/cm has been achieved in the range of 1550-1600 nm for ring radii larger than 40 μm. The ultra-low temperature grown SiNx with properties of low loss and low stress is therefore a promising photonic integration platform for various photonic integration applications.

Room-temperature-deposited dielectrics and superconductors for integrated photonics

“…The mean Q of the data set was 110,000 (corresponding to 2.8 dB/cm), and the standard deviation was 8,900. Sidewall roughness due to patterning with i-line lithography is likely the leading contribution to linear propagation losses, as lower losses have been observed in waveguides of similar material when patterned with electron beam lithography (0.8 dB/cm) [24] as well as within this process when resist reflow was employed (1.8 dB/cm), as discussed in Sec. 4.…”

“…While most Si photonics foundry processes to date utilize crystalline Si as a waveguiding layer, deposited amorphous materials offer several advantages such as low-propagation-loss amorphous silicon (a-Si) [25,26] as well as SiN waveguides [24,27], a wide variety of indices of refraction, lower loss and crosstalk in waveguide crossings [27], and 3D layering [27][28][29][30]. A schematic of the layers used in this process is shown in Fig.…”

“…Alternatively, the fabrication process could commence with a handle wafer other than oxidized Si such as sapphire, quartz, diamond, or III-V materials. Next, the SiN waveguiding layer is deposited using plasma-enhanced chemical vapor deposition [24] using N 2 and SiH 4 as precursors (27 and 30 sccm respectively). The plasma is struck at 30 W and cut to 0 W after 10 s. The chamber pressure is 10 mTorr, and the inductively-coupled power is 1000 W. The wafer temperature has been monitored and does not exceed 65 • C. The resulting SiN film has low stress due to high hydrogen content, so films as thick as 900 nm have been deposited with no cracking or delamination.…”

“…For BEOL integration with CMOS electronics, deposition temperatures of less than 400 • C can meet many process requirements, and several photonic devices have been demonstrated in such a process [23]. Room temperature deposited materials [24] are even more broadly compatible. With this fabrication process, we have demonstrated low-loss passive SiN waveguides and resonators, critically coupled rings, and Mach-Zehnder interferometers (MZIs), dispersion-engineered waveguides and waveguide-device-integrated WSi superconducting-nanowire single-photon detectors (SNSPDs).…”

Hybrid light-emitting polymer/SiN_x platform for photonic integration

“…Recently, inductively coupled plasma chemical vapor deposition (ICP-CVD) technique has been developed to deposit SiN x film under ultra-low temperature [25][26][27]. In our previous work, we have reported that a high quality SiN x film with thickness up to 2 μm can be achieved in a single growth process under ultra-low temperature circumstance [27], which shows great potential for active passive hybrid photonic integration [28,29].…”