The optical properties of silicon-rich silicon nitride prepared by plasma-enhanced chemical vapor deposition

Yoshinaga, Seiya; Ishikawa, Yasuaki; Kawamura, Yusuke; Nakai, Yuya; Uraoka, Yukiharu

doi:10.1016/j.mssp.2018.09.029

Cited by 8 publications

(4 citation statements)

References 23 publications

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“…Thus, the hydrogen concentration in these poly-Si/SiO x contacts was measured by SIMS and correlated to the J 0 value, with the results shown in Figure a in the case of different capping layers and in Figure b for various firing temperatures. Detailed characterization results for SiN x -A, SiN x -B, and SiN x -C were reported in the former work, with SiN x -C showing a larger refractive index ( n ) and a higher density of Si–N bonds than SiN x -A and SiN x -B, reflecting a higher film density of SiN x -C. , The SIMS results given in Figure a support our former speculation that the observed dependence of firing stability on the refractive index ( n ) and the density of Si–N bonds of the SiN x capping films could be related to the film density . Denser SiN x layers could be more effective in preventing the out-diffusion of hydrogen from the wafer upon high-temperature annealing, , resulting in more hydrogen near the SiO x interlayer, as evidenced by the higher hydrogen content around the SiO x in the sample fired with SiN x -C.…”

Section: Resultssupporting

confidence: 83%

Optimum Hydrogen Injection in Phosphorus-Doped Polysilicon Passivating Contacts

Kang

Sio

Stückelberger

et al. 2021

ACS Appl. Mater. Interfaces

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It has previously been shown that ex situ phosphorus-doped polycrystalline silicon on silicon oxide (poly-Si/SiO x ) passivating contacts can suffer a pronounced surface passivation degradation when subjected to a firing treatment at 800 °C or above. The degradation behavior depends strongly on the processing conditions, such as the dielectric coating layers and the firing temperature. The current work further studies the firing stability of poly-Si contacts and proposes a mechanism for the observed behavior based on the role of hydrogen. Secondary ion mass spectrometry is applied to measure the hydrogen concentration in the poly-Si/SiO x structures after firing at different temperatures and after removing hydrogen by an anneal in nitrogen. While it is known that a certain amount of hydrogen around the interfacial SiO x can be beneficial for passivation, surprisingly, we found that the excess amount of hydrogen can deteriorate the poly-Si passivation and increase the recombination current density parameter J 0. The presence of excess hydrogen is evident in selected poly-Si samples fired with silicon nitride (SiN x ), where the injection of additional hydrogen to the SiO x interlayer leads to further degradation in the J 0, while removing hydrogen fully recovers the surface passivation. In addition, the proposed model explains the dependence of firing stability on the crystallite properties and the doping profile, which determine the effective diffusivity of hydrogen upon firing and hence the amount of hydrogen around the interfacial SiO x after firing.

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Section: Resultssupporting

confidence: 83%

Optimum Hydrogen Injection in Phosphorus-Doped Polysilicon Passivating Contacts

Kang

Sio

Stückelberger

et al. 2021

ACS Appl. Mater. Interfaces

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“…From these measurements we confirm our films to be safe for application of fields up to 1.2e8 v/m, which is in line with electric field breakdown strength measurements that have been carried out on SRN films with similar silicon compositions [14] and approximate our films RF permittivity to be 9.0578. Ellipsometric measurements performed at a wavelength of 800nm confirm our films to increase in refractive index when they undergo rapid thermal annealing (RTA) at 300 o C [15]. For more information see supplementary sections S.2 and S.3 respectively.…”

Section: Design and Fabricationsupporting

confidence: 53%

Demonstration of the DC-Kerr effect in silicon-rich nitride

et al. 2021

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We demonstrate the DC-Kerr effect in PECVD Silicon-rich Nitride (SRN) and use it to demonstrate a third order nonlinear susceptibility, 𝝌 (𝟑) , as high as (6 + 0.58)x10 -19 m 2 /v 2 . We employ spectral shift versus applied voltage measurements in a racetrack ring resonator as a tool by which to characterize the nonlinear susceptibilities of these films. In doing so we demonstrate a 𝝌 (𝟑) larger than that of silicon and argue that PECVD SRN can provide a versatile platform for employing optical phase-shifters while maintain a low thermal budget using a deposition technique readily available in CMOS process flows.

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“…In addition, elemental analysis indicates that the deposited SiN is silicon-rich with a stoichiometry close to Si2.5N. On a side note, silicon-rich SiN is preferred due to higher refractive index which translates to higher optical contrast, achieving better light confinement 13 . At the system level, this would enable photonic circuit designer to scale down the circuit real estate increasing circuit density.…”

Section: Resultsmentioning

confidence: 99%

Improved waveguide surface roughness by foundry-processing techniques for enhanced light delivery to integrated ion trap for quantum computing platforms

Goh,

Utama,

et al. 2024

Optical Interconnects XXIV

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Various types of qubits have been proposed and demonstrated for quantum information processing. Amongst the candidates, the trapped ion platform is a forerunner for high-fidelity gates and long coherence times of the qubits. Currently, the most advanced scalable ion trap architecture is based on microfabricated ion trap electrodes integrated with photonic circuits to deliver the laser light of different wavelengths performing the tasks of qubit initialization, gate operations and state determination. These operations require low-loss photonic components for a spectrum of wavelengths to address the trapped ion qubit. Moreover, based on the ion species, the wavelengths also differ. Thus, it requires a whole range of designs to accommodate different wavelengths from infra-red to ultra-violet.A low-loss waveguide is typically constructed using silicon nitride (SiN) as core with silicon oxide (SiO2) as the cladding material. During fabrication, some of the processes may degrade the surface quality of the waveguide core resulting in higher propagation loss. In this study, the relation between the waveguide propagation loss and to morphology of the waveguide core surface is investigated. The effect on waveguide propagation loss from the bottom oxide and SiN by chemical mechanical polishing (CMP) is compared to SiN dry etching. Both plasma-enhanced (PE) and low-pressure (LP) chemical vapor deposited (CVD) SiN on 12" Si wafers are used during evaluation. In the case of a well-designed waveguide, it is found that a reduction of the sidewall roughness by as much as 15% translates to a 20% improvement in the propagation loss at 1.6 μm. On the contrary, when the waveguide core's top and bottom surfaces are polished by CMP, the roughness improves by a factor of 1.75 and 18 for oxide and nitride surfaces respectively. This process however reduces the propagation loss by about 7 times at 1.6 μm wavelength. Furthermore, other improvements in processing techniques enable the fabrication of LPCVD SiN waveguides with propagation loss of 0.56 dB/cm at 685nm wavelength. The optimization of foundry processes for the fabrication of SiN waveguides will significantly contribute towards the efficient and high-fidelity gates in in integrated ion trap. It will also improve the performance of the photonic integrated circuits for quantum technology applications.

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The optical properties of silicon-rich silicon nitride prepared by plasma-enhanced chemical vapor deposition

Cited by 8 publications

References 23 publications

Optimum Hydrogen Injection in Phosphorus-Doped Polysilicon Passivating Contacts

Optimum Hydrogen Injection in Phosphorus-Doped Polysilicon Passivating Contacts

Demonstration of the DC-Kerr effect in silicon-rich nitride

Improved waveguide surface roughness by foundry-processing techniques for enhanced light delivery to integrated ion trap for quantum computing platforms

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