淀积参数对PECVD氮化硅薄膜力学特性的影响

等离子增强化学气相淀积(PECVD)法制备的氮化硅薄膜具有沉积温度低、生长速率高和残余应力可调节等特点,研究其力学特性对研制MEMS器件和系统具有重要意义。采用HQ-2型PECVD淀积台,在沉积温度为350℃,NH3流量为30cm3/min的条件下,通过改变氩气稀释至5%的SiH4流量和射频功率大小,制备了具有压应力、微应力和张应力的多种氮化硅薄膜样品。采用纳米压痕仪Nanoidenter-G200对淀积薄膜的杨氏模量和硬度进行测试,结果表明,在较小的SiH4流量和较高的射频功率条件下,淀积的氮化硅薄膜具有更高的杨氏模量和硬度。     

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.     

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。     

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。     

真空退火对低频PECVD氮化硅薄膜性能的影响

研究了真空退火温度对不同流量比工艺参数下PECVD氮化硅薄膜性能的影响,测试了退火后氮化硅薄膜厚度、折射率以及在氢氟酸中的腐蚀速率。结果表明,退火后氮化硅薄膜厚度及折射率变化与薄膜沉积工艺条件有关,而薄膜在氢氟酸中的腐蚀速率在退火后大大降低。结合退火前后氮化硅薄膜的红外透射谱对以上测试结果进行了讨论。     

PECVD制备氮化硅薄膜的研究

采用PECVD法制备了氮化硅薄膜,探讨了沉积参数对氮化硅薄膜折射率的影响和衬底温度对氮化硅薄膜形貌和成分的影响规律。结果表明,不同的NH3流量可改变反应腔体内的氮硅比,对氮化硅的折射率,即减反射性能影响较大;衬底温度是影响氮化硅薄膜形貌和成分的主要因素;在衬底温度达到400℃时,形成了白色团状或岛状的氮化硅膜。     

PECVD氮化硅膜的微电子学特性

利用电子极化的劳伦茨-劳伦兹关系研究了PECVD氮化硅膜的组分(Si/N).生长条件的变化导致薄膜的Si/N比率千差万别.采取C-V测试和高温准静态离子电流测试对不同Si/N比率的氮化硅膜的微电子学特性进行了探讨.     

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。     

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。     

卧式热壁型PECVD设备

1、简介我公司研制的卧式PECVD设备专门应用于太阳能电池制造领域中氮化硅薄膜的淀积工艺。由于PECVD淀积氮化硅膜时,在生长氮化硅膜作为减反射膜的同时生成了大量的原子氢,这些氢原子不但具有表面钝化作用,同时可以很好的钝化硅中的位错、表面悬挂键,从而提高硅片中载流子迁移率,具有     

The application of polyimide/silicon nitride dual passivation to AlxGa1−xN/GaN high electron mobility transistors

PECVD silicon nitride passivation is quite frequently done at the end of AlGaN/GaN HEMT fabrication before substrate back-side lapping. However, the PECVD silicon nitride process is likely to produce pinholes in the passivation film. A very thick PECVD silicon nitride film may produce mechanical stress on the underlying device. Polyimide passivation has also been known to be effective for AlGaN/GaN HEMT and it can also serve as a stress buffer. However, polyimide can take up water while PECVD silicon nitride is a good diffusion barrier for water, etc. Thus it is expected that a dual PECVD silicon nitride/polyimide passivation will be a better choice than just a single layer of PECVD silicon nitride or polyimide. In this paper, we will demonstrate the application of a dual PECVD silicon nitride/polyimide passivation to AlGaN/GaN HEMT process.     

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     

低应力PECVD氮化硅薄膜工艺探讨

介绍了一种掺氦的等离子增强化学气相淀积（ＰＥＣＶＤ）氮化硅薄膜工艺技术,可调控氮化硅薄膜的应力,从而在较低的射频功率下生长低应力的氮化硅薄膜。文中对其机理作了初步的探讨。所生长的氮化硅薄膜的折射率和腐蚀速率没有明显变化,对器件,尤其是对砷化镓异质结器件几乎没有应力损伤。     

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.     

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.     

晶体硅太阳电池的双层结构钝化膜研究

针对目前基于p型硅片制备的单结太阳电池进一步提高表面钝化膜生产效率,利用氮化硅(SiNx)薄膜良好的钝化效果与价格低廉的二氧化钛(TiO2)膜,降低SiNx镀膜厚度减薄对少子寿命的影响。在单晶硅片表面先用PECVD法沉积SiNx薄膜,然后用热喷涂沉积TiO2薄膜。对比测试了热喷涂沉积TiO2薄膜前后电池的性能,结果表明在SiNx膜上增加TiO2膜层后少子寿命明显提高,这可能是TiO2膜结构内存在固定正电荷所致。这种双层结构封装后的太阳电池显示出了较好的光学与电学性能,对进一步改进太阳电池性能具有重要参考价值。     

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.     

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.