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Dependence of Mechanical Stresses in Silicon Nitride Films on the Mode of Plasma-Enhanced Chemical Vapor Deposition
摘要： Films of silicon nitride SiNx, obtained by plasma-enhanced chemical vapor deposition from the monosilane SiH4 and ammonia NH3 gases, are widely used in microelectronics and micro- and nanoelectromechanical systems. Residual mechanical stresses and film composition are important characteristics for many applications. The properties of SiNx films, particularly mechanical stresses and composition, depend largely on the conditions of production, e.g., the ratio of the reacting gas flow rates, the composition of the gas mixture, the power and frequency of the plasma generator, and the temperature and pressure during deposition. Despite the great volume of works on the subject, data regarding the dependence of the properties and composition of SiNx films on the conditions of production remain sparse. This work considers the effect the ratio of the reacting gas flow rates has on the mechanical stresses and composition of silicon nitride films SiNx obtained by plasma-enhanced chemical vapor deposition from gaseous mixtures of SiH4 monosilane and NH3 ammonia using low-frequency plasma. It is found that when the ratio of the gas flow rates of SiH4 and NH3 is raised from 0.016 to 0.25, the compressive mechanical stresses are reduced by 31%, the stoichiometric coefficient falls from 1.40 to 1.20, the refractive index rises from 1.91 to 2.08, the concentration of N–H bonds is reduced by a factor of 7.4, the concentration of Si–H bonds grows by a factor of 8.7, and the concentration of hydrogen atoms is reduced by a factor of 1.5. These results can be used for the controlled production of SiNx films with such specified characteristics as residual mechanical stresses, refractive index, stoichiometric coefficient, and the concentration of hydrogen-containing bonds.
关键词： mechanical stresses,optical profilometry,films of PECVD silicon nitride SiNx,IR Fourier spectroscopy
更新于2025-11-14 15:18:02
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Rapid Thermal Process for Crystallization Silicon Nitride Films
摘要： Synthesis and characterisation of silicon nanocrystals (Si NCs) materials are carried out. We investigated the morphological and structural Si NCs embedded in the silicon nitride (SiNx) matrix. The study has been carried out on thin ?lms thermally annealed at high temperature by rapid thermal annealing after deposition at 380°C by plasma-enhanced chemical vapour deposition. Our study evidenced the existence of an Si NCs embedded on the SiNx matrix. This has been proven by Raman spectra and high-resolution transmission electron microscopy (HR-TEM). A sharp peak at a frequency of 515 cm?1 ascribed to the transverse optical (TO) mode becomes broader and makes a symmetric shoulder on the higher frequency side with an increase in the annealing temperature. HR-TEM analyses have demonstrated that Si NCs having a mean radius ranging between 3 and 5 nm. This con?rms the a-SiN phase transition to the c-SiN phase by the formation of silicon NCs.
关键词： SiNx,RTA,PECVD,Si NCs
更新于2025-09-23 15:23:52
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Selective Area Deposition of Hot Filament CVD Diamond on 100 mm MOCVD Grown AlGaN/GaN Wafers
摘要： A new technique is reported for selective growth of polycrystalline diamond by hot filament chemical vapor deposition (HFCVD) on AlGaN/GaN-on-Si (111) wafers without degradation of the underlying layers. Selective diamond seeding is accomplished by dispersing nano-diamond seeds in photoresist and patterned lithographically prior to HFCVD growth. A thin layer of plasma enhanced CVD SiNx, deposited prior to seeding and diamond deposition, was found to be essential to protect the AlGaN/GaN wafer. Methane concentration of 3.0% was used to achieve increased diamond growth rate and faster surface coverage. Excellent selectivity and minimal AlGaN surface damage were achieved due to the protective layer and faster surface coverage with increased methane concentration. Damage mitigation was confirmed by comparison of atomic force microscopy, x-ray diffraction, and Raman spectroscopy, each conducted before and after diamond deposition, and by SEM images of the final structures.
关键词： 2DEG,Reciprocal space mapping,III-Nitride,SiNx,Selective area deposition,CVD diamond,Photolithography,GaN decomposition
更新于2025-09-23 15:22:29
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Interface charge engineering in down-scaled AlGaN (<6a??nm)/GaN heterostructure for fabrication of GaN-based power HEMTs and MIS-HEMTs
摘要： The physical mechanism for recovery of 2D electron gas (2DEG) in down-scaled AlGaN/GaN heterostructures with SiNx layers grown by low-pressure chemical vapor deposition (LPCVD) was investigated by means of Hall-effect characterization, scanning Kelvin probe microscopy (SKPM), and self-consistent Poisson–Schr€odinger calculations. Observations using SKPM show that the surface potential of the AlGaN/GaN heterostructure remained nearly unchanged ((cid:2)1.08 eV) as the thickness of the AlGaN barrier was reduced from 18.5 to 5.5 nm and likely originated from the surface pinning effect. This led to a signi?cant depletion of 2DEG from 9.60 (cid:3) 1012 to 1.53 (cid:3) 1012 cm(cid:4)2, as determined by Hall measurements, toward a normally OFF 2DEG channel. Based on a consistent solution of the Schr€odinger–Poisson equations and analytical simulations, approximately 3.50 (cid:3) 1013 cm(cid:4)2 of positive ?xed charges were con?rmed to be induced by a 20-nm LPCVD-SiNx passivation over the AlGaN/GaN heterostructures. The interface charge exerted a strong modulation of band bending in the down-scaled AlGaN/GaN heterostructure, contributing to the ef?cient recovery of 2DEG charge density ((cid:2)1.63 (cid:3) 1013 cm(cid:4)2). E-mode ultrathin-barrier AlGaN/GaN metal–insulator–semiconductor high-electron-mobility transistors with a low ON-resistance (RON), high ON/OFF current ratio, and steep subthreshold slope were implemented using LPCVD-SiNx passivation.
关键词： AlGaN/GaN heterostructure,power HEMTs,LPCVD-SiNx passivation,2D electron gas,MIS-HEMTs,interface charge engineering
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Ultra-thin LPCVD SiN <sub/>x</sub> /n+poly-Si passivated contacts a?? A possibility?
摘要： This work explores the possibility of using ultrathin silicon nitride (SiNx) films with high positive fixed charge in a SiNx/poly-Si passivating contact. The factors including (i) film thickness, (ii) annealing condition (time, temp and ambient) and (iii) surface pre-treatment were optimized to boost the passivation performance of ultrathin LPCVD SiNx films. Our preliminary experiments reveal excellent surface passivation and low recombination current density, Jo (45 fA.cm-2) by ~1.5 nm thick LPCVD SiNx films when subjected to an air ambient anneal at 800?C for 30 mins. This is due to the formation of high positive fixed charge density (1.5 ?10 12 cm-2). Air ambient annealed (465 μs) samples also have a higher lifetime when compared to the forming gas annealed (208 μs) samples. These passivating SiNx films were further integrated into SiNx/n+poly-Si contacts and characterized for Jo,contact and tunneling resistance, ?contact. The best SiNx/n+poly-Si passivated contact in this study has Jo, contact = 5.9 fA.cm-2, ?contact = 0.525 Ω.cm2 and an efficiency potential > 22.75%. According to our knowledge, it is the first report confirming the formation of passivated contacts with SiNx as the dielectric tunnel layer.
关键词： poly-Si,TEM,LPCVD SiNx,annealing,lifetime studies,passivated contact,silicon nitride,tunnel layer
更新于2025-09-23 15:19:57
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Elucidating the mechanism of potential induced degradation delay effect by ultraviolet light irradiation for p-type crystalline silicon solar cells
摘要： A mechanism of potential induced degradation (PID) delay effect by ultraviolet (UV) light irradiation during PID test for p-type crystalline silicon (c-Si) solar cells was proposed in this work. The degradation rate of the solar cell performances is slowed down by the UV light irradiation in the 300–390 nm wavelength range during PID test. The conductivity increase of the silicon nitride (SiNx) anti-reflection coating (ARC) layer on the solar cell surface under UV light irradiation during PID tests, which relates to the mechanism preventing the penetration of sodium ions into the active cell layer, induces the PID delay effect for the p-type c-Si solar cells. The PID delay effect was also analyzed by a microwave photo-conductance decay (μ-PCD) technique in this work. The reduction behavior of the components in the μ-PCD signal curves including rapid (τ1) and slow (τ2) decay time constants and the effective lifetime (τeff) presents a good correlation with the performance degradation behavior of the solar cells over PID test duration. Moreover, the reduction rate of these components is also slowed down under the UV light irradiation in the 300–390 nm wavelength range during PID tests. Notably, their reduction behavior was compatible with the mechanism of the conductivity increase of the SiNx ARC layer under UV light irradiation.
关键词： Potential induced degradation (PID),Silicon solar cells,UV irradiation,Silicon nitride (SiNx),Microwave photo-conductance decay
更新于2025-09-23 15:19:57
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Hydrogen effects on AlGaN/GaN MISFET with LPCVD-SiNx gate dielectric
摘要： In this work, the effects of hydrogen on AlGaN/GaN MISFET with SiNx gate dielectric were investigated. It is found that after the hydrogen exposure, (1) the AlGaN/GaN MISFET exhibits better DC performance with larger maximum transconductance, (2) the gate lag phenomenon is effectively suppressed and (3) the 1/f noise performance is improved with lower noise magnitude. These results are different from the previous observations in other III-V semiconductor devices. Based on the theoretical analysis by space charge limited current (SCLC) and low-frequency noise (LFN) models, we propose that the hydrogen treatment induces hydrogen incorporation into SiNx, which could passivate the defect centers. These findings demonstrate the high hydrogen tolerance of AlGaN/GaN MISFET.
关键词： LPCVD-SiNx,hydrogen effect,AlGaN/GaN MISFET
更新于2025-09-19 17:15:36
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AIP Conference Proceedings [AIP Publishing 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Fes, Morocco (25–27 March 2019)] 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Inline deposited PassDop layers for rear side passivation and contacting of p-type c-Si PERL solar cells with high bifaciality
摘要： We investigate stacks of aluminum oxide (Al2O3) and boron-doped silicon nitride (SiNX:B) layers for the rear side passivation and local doping of p-type silicon solar cell samples aiming for the realization of bifacial passivated emitter and rear locally diffused (biPERL) solar cells. The local p+-doped back surface field regions are formed by laser doping and are electrically contacted using commercially available screen-printed and fired silver-aluminum (AgAl) or silver (Ag) contacts. This approach is referred to as “pPassDop”. Laser doping results in highly-doped silicon with sheet resistances as low as 15 ?/sq and surface doping concentrations up to 6×1019 cm-3. Low specific contact resistances around 1 m? cm2 and 5 m? cm2 are measured for the screen-printed and fired AgAl and Ag contacts, respectively. In addition, the influence of each individual layer within the pPassDop layer stack on the doping properties is investigated. In order to separate the impact of aluminum and boron doping, firstly the influence of the Al2O3 layer thickness (0 nm, 4 nm, 6 nm) below the SiNX:B capping layer is studied. Secondly, a conventional undoped SiNX capping layer is applied on a 6 nm-thick Al2O3 layer. The roles of each dopant are studied by measuring the doping profile and contact resistivity.
关键词： SiNX:B,laser doping,bifacial PERL solar cells,pPassDop,Al2O3
更新于2025-09-12 10:27:22
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P-10.2: The Influences of PECVD Deposition SiNx on the Thin Film Encapsulation Performance
摘要： Low-temperature PECVD technology was used to fabricated inorganic layer in thin film encapsulation for AMOLED display. We systematically obtained SiNx films in different RF power. Stress and refractive index was characterized and analyzed to study the film performance. The results shows that different RF power leads to different film stress, and well-designed stress-matched multilayer SiNx will highly improve the TFE reliability. Furthermore, the RA life time (60 °C, 90% RH) of OLED displays with new multilayer SiNx inorganic layer TFE structure has been sharply increased from 240hours to 480hours.
关键词： PECVD,SiNx,Thin Film Encapsulation,Flexible OLED
更新于2025-09-10 09:29:36
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Top-gated graphene field-effect transistors by low-temperature synthesized SiN <i> <sub/>x</sub></i> insulator on SiC substrates
摘要： Top-gated devices made from an epitaxial graphene film on a 4H-SiC substrate were fabricated. Atomic force microscopy and Raman spectroscopy results showed that a large-scale highly uniform monolayer graphene film was synthesized on the SiC substrate. A SiNx passivation film was deposited on a SiC graphene device as a top gate insulator by catalytic chemical-vapor deposition (Cat-CVD) below 65 °C. After the top gate electrode was formed on the SiNx film, no leakage current flowed between the gate and source electrodes. The transport characteristics showed clear ambipolar characteristics from 8 to 280 K, and the temperature dependences of the conductance and field-effect mobility of the devices implied that monolayer graphene devices can be successfully fabricated. Moreover, the position of the charge neutrality point after SiNx deposition was around 0 V, indicating p-doping characteristics. These results indicate that SiNx films synthesized by Cat-CVD can be used as gate insulators and that the carrier type may be controlled by adjusting the deposition conditions.
关键词： SiNx,Cat-CVD,field-effect transistors,graphene,SiC substrates
更新于2025-09-09 09:28:46