Evaluation of the mechanical behaviour of nanometre-thick coatings deposited using an atmospheric pressure plasma system

This study evaluated the use of pin-on-disc wear testing as a technique to examine the mechanical behaviour of nanometre thick plasma deposited coatings. The coatings were deposited onto polyethylene terephthalate and silicon wafer substrates by directly injecting an aerosol of siloxane liquid precursors into a helium/oxygen atmospheric pressure plasma. The siloxane precursors examined were hexamethyldisiloxane, polydimethylsiloxane and tetramethyldisiloxane. The mechanical performance of 21 (± 3) nm thick coatings was compared using a pin-on-disc wear test technique and fragmentation tests. An increase in the level of precursor plasma exposure was found to be associated with an increase in coating surface energy and a reduction in coating roughness and resulted in enhanced wear resistance. Fragmentation tests revealed a transition from ductile failure to brittle failure as the level of plasma exposure increased. This correlated with the reduction in coating wear rates. Wear track depth and proximity to the coating/substrate interface were both found to influence the rate or wear. A simple correlation between wear rate and applied force is presented as a method for comparing coating performance using pin-on-disc wear testing.     

On the structure of low-temperature PECVD silicon dioxide films

It is demonstrated that the results of refractive index, infra-red absorption and electron spin resonance measurements on low temperature PECVD silicon dioxide films are con-sistent with a network structure composed of densified, amorphous SiO₂ and micro-scopes. The density of the amorphous SiO₂ is suggested to be greater than that of un-densified SiO₂ by about 10%. Approximately 5% of the deposited film volume is argued to consist of micropores High temperature annealing relaxes the dense state of the amorphous SiO₂ and collapses the volume occupied by the micropores.     

New solutions for intermetal dielectrics using trimethylsilane-based PECVD processes

Trimethylsilane, (CH₃)₃SiH, is a non-pyrophoric organosilicon gas. This material is easily used to deposit dielectric thin films in standard PECVD systems designed for SiH₄. In addition to deposition of standard dielectrics (e.g. SiO₂), trimethylsilane can be used to deposit reduced permittivity (low-k) dielectric versions of amorphous hydrogenated silicon carbide and its oxides. The low-k carbides (k<5.5) are highly insulating and useful as hard masks, etch stops and copper diffusion barriers. The low-k oxides (2.6<k<3.0) are useful as intermetal dielectrics, and exhibit stability and electrical properties which can meet many specifications in device fabrication that are now placed on SiO₂. This paper reviews PECVD processing using trimethylsilane. Examples will show that the 3MS-based dielectrics can be used in place of SiH₄-based oxides and nitrides in advanced device multilevel metal interconnection schemes to provide improved circuit performance.     

一种精细调控 PECVD 晶圆温度的设计及其仿真分析

为在等离子增强型化学气相沉积工艺过程中,实现对晶圆平均温度及温度分布轮廓的精细化调控。采用Comsol软件建立热流仿真模型,通过调节冷却气体的进气流量,调节晶圆平均温度;通过调节布气板环形气道宽度,调节晶圆的温度分布轮廓。结果表明,与不通冷却气体时相比,当气体流量为70000 mL／min时,晶圆表面平均温度从430℃降到预设温度220℃;当布气板环形气道宽度从中心到边缘分别为0．5mm、8．0mm、2．0mm、1．0mm、0．5mm时,晶圆表面温度分布变异系数小于2％。该方法实现了在工艺过程中对晶圆平均温度及分布轮廓的有效控制,为薄膜沉积工艺提供了均匀的热场分布。     

Ultrathin PECVD epitaxial Si solar cells on glass via low‐temperature transfer process

Fabrication of high‐quality ultrathin monocrystalline silicon layers and their transfer to low‐cost substrates are key steps for flexible electronics and photovoltaics. In this work, we demonstrate a low‐temperature and low‐cost process for ultrathin silicon solar cells. By using standard plasma‐enhanced chemical vapor deposition (PECVD), we grow high‐quality epitaxial silicon layers (epi‐PECVD) from SiH₄/H₂ gas mixtures at 175 °C. Using secondary ion mass spectrometry and transmission electron microscopy, we show that the porosity of the epi‐PECVD/crystalline silicon interface can be tuned by controlling the hydrogen accumulation there. Moreover, we demonstrate that 13–14% porosity is a threshold above which the interface becomes fragile and can easily be cleaved. Taking advantage of the H‐rich interface fragility, we demonstrate the transfer of large areas (∽10 cm²) ultrathin epi‐PECVD layers (0.5–5.5 µm) onto glass substrates by anodic bonding and moderate annealing (275–350 °C). The structural properties of transferred layers are assessed, and the first PECVD epitaxial silicon solar cells transferred on glass are characterized. Copyright © 2016 John Wiley & Sons, Ltd.     

低应力PECVD SiC晶圆级薄膜封装新技术

为了解决MEMS封装过程中易对微致动件造成损伤的问题,提出了一种低成本、与CMOS工艺兼容的晶圆级薄膜封装技术,用等离子体增强化学气相淀积(PECVD)法制备的低应力SiC作为封装和密封材料。此材料的杨氏模量为460 GPa,残余应力为65 MPa,可使MEMS器件悬浮时封装部位不变形。与GaAs,Si半导体材料相比,SiC具有较佳的物理稳定性,较高的杨氏模量等性能优势。将PECVD薄膜封装技术用于表面微结构和绝缘膜上Si(SOI)微结构部件(如射频开关、微加速度计等)封装中,不仅减小了封装尺寸,降低了芯片厚度,简化了封装工艺,而且封装芯片还与CMOS工艺兼容。较之晶圆键合封装方式,此晶圆级薄膜封装成本可降低5%左右。     

高产能四管卧式热壁型PECVD设备

介绍了北京七星华创电子股份有限公司自主创新产品国内首台带有自动上下料系统的高产能四管卧式热壁型PECVD设备,该设备具有高产能、自动化程度高、成膜质量好、高性价比等特点,并着重阐述了该设备的技术先进性及性能指标。     

氢等离子体处理钝化层对高效晶硅异质结太阳电池性能的影响

研究不同时间氢等离子体处理（HPT）氢化非晶硅a-Si:H（i）钝化层对高效晶硅异质结太阳电池（效率>23％）性能的影响。发现适当时间的HPT可改善钝化效果提升电池性能,但过长时间的HPT可导致薄膜钝化效果变差,有效少数载流子寿命降低。分析认为HPT时间过长,H原子进入到a-Si:H（i）薄膜层中,导致薄膜内部SiH₂增多,微结构因子（R）增大,薄膜质量变差。并且,适当时间的HPT改善太阳电池性能的幅度有限,而过长时间的HPT导致电池性能下降却很明显。因此,针对高效率的晶硅异质结太阳电池,应对钝化层沉积之后的HPT工艺进行谨慎控制。     

Near-edge X-ray absorption fine structure spectroscopy of arcjet-deposited cubic boron nitride

Near-edge X-ray absorption fine structure (NEXAFS) spectroscopy was employed to help determine the structure of boron nitride films grown by bias-enhanced chemical vapor deposition in a low-density supersonic arcjet flow. BN films containing 0.90% cubic boron nitride were analyzed by NEXAFS and compared with c-BN and h-BN reference spectra. The mainly cubic films have been shown previously to be nanocrystalline, which leads to the inability to obtain structural information from Raman scattering spectra. However, with NEXAFS, the nanocrystalline nature of the films does not strongly affect the structural interpretation. It is shown that films deposited with a bias of −75 V are primarily sp³ bonded. This high sp³ bonding character agrees with previous measrements based on infraredtransmission and reflectance spectroscopy, as well as X-ray photoelectron spectroscopy.     

循环氩离子轰击-等离子体增强化学气相沉积 TiN 膜组织与性能研究

分析对比了常规ＰＥＣＶＤＴｉＮ膜与循环氩离子轰击－ＰＥＣＶＤＴｉＮ膜组织与性能的差异。结果表明，循环氩离子轰击－ＰＥＣＶＤＴｉＮ膜较之常规ＰＥＣＶＤＴｉＮ膜，其组织细小致密，膜内残余氯含量显著降低，膜的硬度与耐磨性提高，但膜－基体结合强度没有显著改变。