Effect of hydrogen content on dielectric strength of the silicon nitride film deposited by ICP-CVD

The inductively coupled plasma chemical vapor deposition(ICP-CVD) deposited silicon nitride(SiN_(x)) thin film was evaluated for its application as the electrical insulating film for a capacitor device.In order to achieve highest possible dielectric strength of SiN_(x),the process parameters of ICP-CVD were carefully tuned to control hydrogen in SiN_(x) films by means of tuning N_(2)/SiH_(4) ratio and radio frequency(RF) power.Besides electrical measurements,the hydrogen content in the films was measured by dynamic secondary ion mass spectrometry(D-SIMS).Fourier transform infrared spectroscopy(FTIR) and micro Raman spectroscopy were used to characterize the SiN_(x) films by measuring Si-H and N-H bonds’ intensities.It was found that the more Si-H bonds lead to the higher dielectric strength.

Thermal conductivity of PECVD silicon-rich silicon nitride films measured with a SiO_2/Si_xN_y bimaterial microbridge test structure

In order to balance the compressive stress of a silicon dioxide film and compose a steady MEMS structure, a silicon-rich silicon nitride film with tensile stress is deposited by plasma enhanced chemical vapor deposition process. Accurately measuring the thermal conductivity of the film is highly desirable in order to design, simulate and optimize MEMS devices. In this paper, a Si02/SixNy bimaterial microbridge structure is presented to measure the thermal conductivity of the silicon-rich silicon nitride film by single steady-state measurement. The thermal conductivity is extracted as 3.25 W/（m-K）. Low thermal conductivity indicates that the silicon-rich silicon nitride film can still be utilized as thermally insulating material in thermal sensors although its thermal conductivity is slightly larger than the values reported in literature.

Effect of Hydrogen Dilution on Growth of Silicon Nanocrystals Embedded in Silicon Nitride Thin Film by Plasma-Enhanced CVD

An investigation was conducted into the effect of hydrogen dilution on the microstructure and optical properties of silicon nanograins embedded in silicon nitride （Si/SiNx） thin film deposited by the helicon wave plasma-enhanced chemical vapour deposition technique. With Ar-diluted SiH4 and N2 as the reactant gas sources in the fabrication of thin film, the film was formed at a high deposition rate. There was a high density of defect at the amorphous silicon （a-Si）/SiNx interface and a relative low optical gap in the film. An addition of hydrogen into the reactant gas reduced the film deposition rate sharply. The silicon nanograins in the SiNx matrix were in a crystalline state, and the density of defects at the silicon nanocrystals （nc-Si）/SiNx interface decreased significantly and the optical gap of the films widened. These results suggested that hydrogen activated by the plasma could not only eliminate in the defects between the interface of silicon nanograins and SiNx matrix, but also helped the nanograins transform from the amorphous into crystalline state. By changing the hydrogen dilution ratio in the reactant gas sources, a tunable band gap from 1.87 eV to 3.32 eV was obtained in the Si/SiNx film.

Deposition of Silicon Nitride Films by Silane Hydrazine Process

A new catalytic chemical vapor process for depositing silicon nitride films using silane hydrazine gaseous mixture is described. This system can be useful at a temperature of lower than 400 ℃. The catalytic process gives more rapid deposition rate than 10 nm/min. The atomic composition ratio, N/Si, which is evaluated by Rutherfold backscattering method is about 1.4 under a given experimental conditions more than the stoichiometric value of 1.33 in Si 3N 4. The infrared transmission spectra show a large dip at 850 cm -1 due to Si-N bonds and no clear dip due to Si-O bonds. High N-H bond density is the evidence that the deposition mechanism is limited by N-N bond breaking of the hydrazine. The H contents, evaluated from Si-H and N-H bonds in the infrared absorption spectra, and the deposition rate are measured as a function of the substrate temperature. In addition some film properties such as the resistivity and the breakdown electric field are presented.

Characteristics and Electrical Properties of SiNx:H Films Fabricated by Plasma-Enhanced Chemical Vapor Deposition

SiNx：H films with different N/Si ratios are synthesized by plasma-enhanced chemical vapor deposition （PECVD）. Composition and structure characteristics are detected by Fourier transform infrared spectroscopy （FTIR） and X-ray photoelectron spectroscopy （XPS）. It indicates that Si-N bonds increase with increased NH3/SiH4 ratio. Electrical property investigations by I-V measurements show that the prepared films offer higher resistivity and less leakage current with increased N/Si ratio and exhibit entirely insulating properties when N/Si ratio reaches 0.9, which is ascribed to increased Si-N bonds achieved.

Dependence of Optical Absorption in Silicon Nanostructures on Size of Silicon Nanoparticles

The amorphous silicon nanoparticles （Si NPs） embedded in silicon nitride （SiNx） films prepared by helicon wave plasma-enhanced chemical vapor deposition （HWP-CVD） technique are studied. From Raman scattering investigation, we determine that the deposited film has the structure of silicon nanocrystals embedded in silicon nitride （nc-Si/SiNx） thin film at a certain hydrogen dilution amount. The analysis of optical absorption spectra implies that the Si NPs is affected by quantum size effects and has the nature of an indirect-band-gap semiconductor. Further, considering the effects of the mean Si NP size and their dispersion on oscillator strength, and quantum-confinement, we obtain an analytical expression for the spectral absorbance of ensemble samples. Gaussian as well as lognormal size-distributions of the Si NPs are considered for optical absorption coefficient calculations. The influence of the particle size-distribution on the optical absorption spectra was systematically studied. We present the fitting of the optical absorption experimental data with our model and discuss the results.

Mechanical strains in pecvd SiN_x:H films for nanophotonic application

Hydrogenated amorphous silicon nitride films（Si N x：H） are deposited at low temperature by high-frequency plasmaenhanced chemical vapor deposition（HF PECVD）. The main effort is to investigate the roles of plasma frequency and plasma power density in determining the film properties particularly in stress. Information about chemical bonds in the films is obtained by Fourier transform infrared spectroscopy（FTIR）. The stresses in the Si N x：H film are determined from substrate curvature measurements. It is shown that plasma frequency plays an important role in controlling the stresses in Si N x：H films. For silicon nitride layers grown at plasma frequency 40.68 MHz initial tensile stresses are observed to be in a range of 400 MPa-700 MPa. Measurements of the intrinsic stresses of silicon nitride films show that the stress quantity is sufficient for film applications in strained silicon photonics.