低应力PECVD氮化硅薄膜的制备

研究了等离子增强化学气相淀积(PECVD)工艺中射频条件(功率和频率)对氮化硅薄膜应力的影响.对于不同射频条件下薄膜的测试结果表明:低频(LF)时氮化硅薄膜处于压应力,高频(HF)时处于张应力,且相同功率时低频的沉积速率和应力分别为高频时的两倍左右;在此基础上采用不同高低频时间比的混频工艺实现了对氮化硅薄膜应力的调控,且在高低频时间比为5:1时获得了应力仅为10 MVa的极低应力氮化硅薄膜.     

晶体硅太阳电池减反射膜的研究

在太阳电池表面形成一层减反射薄膜是提高太阳电池的光电转换效率比较可行且降低成本的方法。应用PECVD（等离子体增强化学气相沉积）系统,采用SiH4和NH3气源以制备氮化硅薄膜。研究探索了PECVD生长氮化硅薄膜的基本物化性质以及在沉积过程中反应压强、反应温度、硅烷氨气流量比和微波功率对薄膜性质的影响。通过大量实验,分析了氮化硅薄膜的相对最佳沉积参数,并得出制作减反射膜的优化工艺。     

PECVD制备非晶硅薄膜的研究

实验采用等离子体增强化学气相沉积(PECVD)法在Si衬底上制备了非晶硅薄膜。研究了射频功率、PH3掺杂浓度等因素对薄膜电阻率以及应力的影响。实验结果表明,对于非掺杂非晶硅薄膜,当射频功率从15W增加到45W时,薄膜应力从张应力变化到压应力,在射频功率为35W时,应力几乎为零,应力绝对值先降低后增加,淀积速率随着射频功率的增加而增加;对于掺杂非晶硅薄膜,电阻率随着PH3掺杂浓度的增加而降低,当PH3流量从0cm3/min增加到12cm3/min时,薄膜掺杂效果明显,电阻率降低3个数量级,继续增加PH3流量,电阻率变化较小,而应力随着PH3掺杂浓度的增加而降低,当PH3流量超过12cm3/min时,应力有增加的趋势。     

沉积功率和气压对低频氮化硅薄膜应力的影响

利用等离子体增强化学气相沉积(PECVD)工艺,在不同射频功率,不同反应气压条件下制备了氮化硅薄膜。研究了低频工艺中氮化硅薄膜的沉积速率、应力以及厚度均匀性与其二者的关系。结果表明,射频功率的改变直接影响到离子对衬底的轰击效应,而反应气压的改变影响气体分子的平均自由程。离子轰击效应和分子平均自由程对氮化硅薄膜的生长过程产生影响,从而影响沉积速率、应力以及厚度均匀性等基本性质。     

用于MEMS开关的低应力氮氧化硅桥膜

给出了用于微机电(MEMS)开关悬浮桥的低应力氮氧化硅(SiOxNy)薄膜的制备工艺研究结果,分析了等离子增强化学气相淀积(PECVD)制备低应力薄膜的影响因素,通过改变反应气体(SiH4,NH3和N2O)的流量比,用PECVD方法生成系列SiOxNy薄膜样品.利用形貌仪测量样品的曲率半径,计算相应的应力.研究表明,当反应气体(SiH4,NH3和N2O)的流量比为32∶12∶8(N2标定)时,可以得到张应力值为76.8 MPa的SiOxNy薄膜,其折射率为1.688,Si,N和O三种元素的成分比为56.3∶23.7∶20.0.将此薄膜生长工艺应用于开关制备,得到了适用于DC～10 GHz频段的MEMS接触式开关,其驱动电压为23.3 V.     

应用高频激励源制备低应力氮化硅薄膜研究

研究了在等离子体增强化学气相沉积(PECVD)法制备氮化硅薄膜时,射频功率和腔室压力对氮化硅薄膜应力的影响以及应力与沉积速率的关系。通常认为高频下制备得到的氮化硅膜呈现张应力,但是通过实验,表明即使应用高频(13.56MH z)作为激励源同样可以沉积出呈现压应力的氮化硅薄膜。并使用角度可变光谱型椭偏仪观察了薄膜的厚度和低应力氮化硅膜的m app ing图,利用傅立叶变换红外光谱仪(FT IR)对不同应力状态下的氮化硅膜的化学键结构进行了分析。     

InSbCID焦平面器件中介质膜的制备和应用

本文介绍了等离子增强化学汽相淀积(简称PECVD)二氧化硅的生长原理.用硅烷(SiH_4)和二氧化碳(CO_2)通过射频电场产生辉光放电等离子体,以此增强化学反应降低淀积温度.在60～300℃下,SiH_4流量为0.5～2.0升/分,CO_2流量为0.2～1.5升/分,淀积压力为0.8～3.5托,射频功率为20～50瓦,极板间距为12～20.5毫米的条件下淀积二氧化硅膜.给出了射频功率、淀积压力、气体流量比等对淀积速率的影响以及红外光谱分析结果.其次,简述了PECVD二氧化硅钝化膜的性能及其在全单片锑化铟红外电荷注入器件(FMInSbIRCID)研制中的应用情况.     

等离子增强化学气相沉积法制备Si-C-H薄膜

以SiH4和CH4为气源,在不同的工艺条件下用增强化学气相沉积(PECVD)方法制备了一系列Si-C-H薄膜,并对薄膜的结构和性能进行了一系列测试分析,研究了薄膜的结构性能特点以及CH4/SiH4比和射频功率等工艺参数对薄膜结构和性能的影响。发现薄膜中主要形成的是嵌有Si晶粒的非晶态SiC结构,H原子主要以C-H键形式存在。高的射频功率和CH4/SiH4比均有利于Si-C的形成,而较低的CH4/SiH4比可以提高薄膜的晶态率。薄膜的电阻率随着CH4/SiH4比的增大而增大,随着射频功率的增大而减小。     

p-Si TFT栅绝缘层用SiNx薄膜界面特性的研究

以NH3和SiH4为反应源气体,在低温下采用射频等离子体增强化学气相沉积(RF-PECVD)法在多晶硅(p-Si)衬底上沉积了SiNx薄膜.系统地分析讨论了沉积温度、射频功率、反应源气体流量比对SiNx薄膜界面特性的影响.分析表明,沉积温度和射频功率主要是通过影响SiNx薄膜中的si/N比和H含量影响薄膜的界面特性,而NH3/SiH4流量比则主要通过影响薄膜中的H含量影响薄膜界面特性.实验制备的SiNx薄膜层中的固定电荷密度、可动离子密度、SiNx与p-si之间的界面态密度分别达到了1.7×1012/cm2、1.4×1012/cm2、3.5×1012/(eV·cm2),其界面特性达到了制备高质量p-si TFT栅绝缘层的性能要求.     

NH3/SiH4流量比对多晶硅/氮化硅复合层电池光电性能的影响研究

SiN薄膜因为具有良好的减反射性质和钝化作用, 越来越广泛地应用于晶硅太阳电池的制造工艺中。用等离子体化学气相沉积(PECVD)法, 通过改变流量比、气体总量及基底温度等工艺参数沉积SiN薄膜, 研究了流量比对在多晶硅太阳电池上所沉积的氮化硅薄膜性能的影响。实践表明, NH3/SiH4气体流量比为11.5∶1时电池材料具有最佳的光电性能。     

Determination of local stress in PECVD nitride films

Silicon nitride and silicon oxynitride films grown on silicon substrates by plasma-enhanced chemical vapour deposition (PECVD) are stressed and the correlation of the film stress to its refractive index is presented. It is shown that it is possible to determine the stress of the PECVD nitride films by measuring their refractive indices, which can be done locally, but that the method is not applicable to the PECVD oxynitride films.     

Optimization of saturation current density of PECVD SiN coated phosphorus diffused emitters using neural network modeling

Emitter surface passivation by low temperature plasma enhanced chemical vapor deposition (PECVD) silicon nitride is investigated and optimized in this paper. We have found that the saturation current density of a 90±10 μ/sq phosphorus diffused emitter with N_s ≈3 x 10¹⁹ and X_j ≈0.3 μm can be lowered by a factor of eight by appropriate PECVD silicon nitride deposition and photoassisted anneal. PECVD silicon nitride deposition alone reduces the emitter saturation density (J_oe) by about a factor of two to three, and a subsequent photoanneal at temperatures ≥350°C reduces J_oe by another factor of three. In spite of the larger flat band shift for direct PECVD silicon nitride coating, the silicon nitride induced surface passivation is found to be about a factor of two inferior to the thermal oxide plus PECVD silicon nitride passivation due to higher interface state density at the SiN/SiO₂ interface compared to SiO₂/Si interface. A combination of statistical experimental design and neural network modeling is used to show quantitatively that lower radio frequency power, higher substrate temperature, and higher reactor pressure during the PECVD deposition can reduce the J_oe of the silicon nitride coated emitter.     

New applications of low temperature PECVD silicon nitride films for microelectronic device fabrication

Silicon nitride has been widely used in microelectronic device fabrication processes for encapsulation, surface passivation and isolation. In this paper we report new applications of plasma-enhanced chemical vapor deposition (PECVD) silicon nitride films that can be deposited at a temperature lower than the soft bake temperature of normal photoresists. Lift-off of the silicon nitride film was carried out using standard positive photoresist. GaAs MESFETs and InP MISFETs with self-aligned gates were successfully fabricated using this lift-off process of low temperature PECVD silicon nitride.     

管式PECVD射频功率对氮化硅薄膜性能的影响

氮化硅薄膜作为传统的晶体硅太阳电池钝化减反膜,其性能的变化直接影响电池的转化效率。通过改变管式PECVD的射频功率,制备了不同膜厚和折射率的氮化硅薄膜,并分别进行了薄膜致密性以及硅片镀膜后少子寿命的测试。实验及测试结果表明,改变PECVD的射频功率对氮化硅薄膜的沉积速率及其薄膜的性能有重要影响。     

富硅量不同的富硅氮化硅薄膜的光致发光研究

采用等离子体增强化学气相沉积方法(PECVD)，在低衬底温度下制备了系列富硅量不同的富硅氮化硅薄膜。且所有样品分别经过不同温度的退火。通过X射线光电子能谱(XPS)的测试证实了薄膜中硅团簇的存在。对不同富硅量的氮化硅薄膜做了红外和光致发光的比较研究。由不同富硅量薄膜中硅团簇的尺寸变化对发光峰的影响。得出了发光来源于包埋于氮化硅薄膜中由于量子限制效应而使带隙增大了的硅团簇。     

Modeling the growth of PECVD silicon nitride films for solar cellapplications using neural networks

Silicon nitride films grown by plasma-enhanced chemical vapor deposition (PECVD) are useful for a variety of applications, including anti-reflection coatings in solar cells, passivation layers, dielectric layers in metal/insulator structures, and diffusion masks, PECVD nitride films are known to contain hydrogen, and defect passivation by hydrogenation enhances efficiency in polycrystalline silicon solar cells. PECVD systems are controlled by many operating variables, including RF power, pressure, gas flow rate, reactant composition, and substrate temperature. The wide variety of processing conditions, as well as the complex nature of particle dynamics within a plasma, makes tailoring Si₃N₄ film properties very challenging, since it is difficult to determine the exact relationship between desired film properties and controllable deposition conditions. In this study, silicon nitride PECVD modeling using neural networks has been investigated. The deposition of Si₃N₄ was characterized via a central composite experimental design, and data from this experiment was used to train optimized feed-forward neural networks using the back-propagation algorithm. From these neural process models, the effect of deposition conditions on film properties has been studied. It was found that the process parameters critical to increasing hydrogenation and therefore enhancing carrier lifetime in polysilicon solar cells are temperature, silane, and ammonia flow rate. The deposition experiments were carried out in a Plasma Therm 700 series PECVD system     

High‐quality surface passivation of silicon solar cells in an industrial‐type inline plasma silicon nitride deposition system

We have studied the surface passivation of silicon by deposition of silicon nitride (SiN) in an industrial‐type inline plasma‐enhanced chemical vapor deposition (PECVD) reactor designed for the continuous coating of silicon solar cells with high throughput. An optimization study for the passivation of low‐resistivity p‐type silicon has been performed exploring the dependence of the film quality on key deposition parameters of the system. With the optimized films, excellent passivation properties have been obtained, both on undiffused p‐type silicon and on phosphorus‐diffused n⁺ emitters. Using a simple design, solar cells with conversion efficiencies above 20% have been fabricated to prove the efficacy of the inline PECVD SiN. The passivation properties of the films are on a par with those of high‐quality films prepared in small‐area laboratory PECVD reactors. Copyright © 2004 John Wiley & Sons, Ltd.     

PECVD法氮化硅薄膜制备工艺的研究

采用等离子体增强化学气相沉积法（PECVD）在单晶硅衬底上制备了氮化硅薄膜,分别使用膜厚仪、椭圆偏振仪等手段对薄膜的厚度、折射率等参数进行了表征。研究了硅烷氨气流量比、极板间距等工艺参数对氮化硅薄膜性能的影响,发现当硅烷氨气流量比增加时,薄膜厚度和折射率均随之增加,并发现退火工艺可以有效降低氮化硅薄膜的氢氟酸腐蚀速率。     

PECVD法氮化硅薄膜生长工艺的研究

采用等离子体增强化学气相沉积法(PECVD),在单晶硅衬底(100)上成功制备了不同生长工艺条件下的氮化硅薄膜。分别采用XP-2台阶仪、椭圆偏振仪等手段测试了薄膜的厚度、折射率、生长速率等参数。并采用原子力显微镜(AFM)研究了薄膜的表面形貌。结果表明,温度和射频功率是影响薄膜生长速率的主要因素,生长速率变化幅度可以达到230nm/min甚至更高。对于薄膜折射率和成分影响最大的是NH3流量,折射率变化范围可以达到2.7～1.86。分析得出受工艺参数调控的薄膜生长速率对薄膜的性质有重要影响。     

Stress control of silicon nitride films deposited by plasma enhanced chemical vapor deposition

Stress controllable silicon nitride(Si Nx) films deposited by plasma enhanced chemical vapor deposition(PECVD) are reported. Low stress Si Nx films were deposited in both high frequency(HF) mode and dual frequency(HF/LF) mode. By optimizing process parameters, stress free(-0.27 MPa) Si Nx films were obtained with the deposition rate of 45.5 nm/min and the refractive index of 2.06. Furthermore, at HF/LF mode, the stress is significantly influenced by LF ratio and LF power, and can be controlled to be 10 MPa with the LF ratio of 17% and LF power of 150 W. However, LF power has a little effect on the deposition rate due to the interaction between HF power and LF power. The deposited Si Nx films have good mechanical and optical properties, low deposition temperature and controllable stress, and can be widely used in integrated circuit(IC), micro-electro-mechanical systems(MEMS) and bio-MEMS.