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.     

GaAs衬底上氮化硅钝化层的低温制备工艺研究

为了获得应用于AlGaAs激光器上的优异的氮化硅薄膜,采用等离子增强化学气相沉积(PECVD)低温条件下在GaAs衬底上制备了不同参数的氮化硅薄膜,利用光学膜厚仪、原子力显微镜(AFM)、傅里叶变换红外光谱(FTIR)等技术对薄膜残余应力、表面形貌、折射率等进行了分析。结果表明,薄膜的残余应力随沉积功率的增加而变大;随气压先降低后变大,在200 Pa时仅为6 MPa。薄膜的表面粗糙度随功率的提高而变大;随气压的提高而减小。功率和气压对薄膜的折射率影响不大,均在2.0~2.2之间。薄膜中氢的存在形式为N-H键。选择合适的功率和气压,可以在低温下获得极低应力和优异表面形貌的氮化硅薄膜。     

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。     

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。     

流量及温度对低频PECVD氮化硅薄膜性能的影响

研究了低频等离子增强化学气相沉积(LF-PECVD)工艺中气体流量比和衬底温度对氮化硅薄膜折射率、密度及应力的影响规律,同时测试了薄膜的红外光谱以分析不同条件对薄膜成分的影响.结果表明,低频氮化硅薄膜折射率主要受薄膜内硅氮元素比的影响,其次是薄膜密度的影响.前者主要由硅烷/氨气反应气体流量比决定,而后者主要由衬底温度决定;低频氮化硅薄膜应力大致与密度成正比关系.此外,PECVD工艺所制备氮化硅薄膜都含有相当数量的氢元素,而衬底温度是薄膜内氢含量的决定因素.     

低压化学气相沉积制备低应力氮化硅膜的研究

采用低压化学气相沉积方法，通过改变工艺气体配比，在硅衬底上生长低应力氮化硅薄膜。用应力仪、椭偏仪对生成的氮化硅薄膜的应力、生长速率、均匀性、折射率及腐蚀速率等进行实验。实验结果表明：低应力氮化硅薄膜制备的关键是增大DCS和NH₃的配比，配比越大，生成的氮化硅薄膜应力越小，折射率越大，耐酸腐蚀能力越强，致密性越好；但随着配比增大，生成的氮化硅薄膜均匀性变差。选择合适的工艺气体配比可在硅衬底上制备出高质量的低应力氮化硅薄膜。     

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。     

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。     

变温LPCVD沉积氮化硅薄膜的均匀性优化

以低压化学气相沉积(LPCVD)热壁立式炉为实验平台,由二氯硅烷和氨通过LPCVD工艺合成氮化硅薄膜,利用降温成膜提高氮化硅薄膜的膜厚均匀度.基于气体碰撞理论建立了氮化硅薄膜沉积速率与反应气体浓度的关系式.分析比较了LPCVD炉内不同升温速率沉积氮化硅薄膜的表面性能.发现在变温沉积阶段,选择合适的降温速率是实现薄膜沉积...     

用ECR等离子体CVD沉积的氮化硅膜特性

本文研究了用电子回旋共振(ECR)等离子体化学气相沉积(CVD)的氮化硅膜的性能与沉积条件之间的相互关系。通过控制流比(SiH_4/N_2)和总流率(SiH_4 N_2)而不管微波功率如何,可以使BHF(缓冲氟)蚀刻率减至最小。在上述条件下沉积的膜的折射率约为2.0。在SiH_4(10sccm)和N_2(10sccm)条件下沉积的薄膜,其电击穿强度大于8MV/cm,电容率(1MHz)为6.4—6.9,内应力大于7×10~9dyn/cm~2。通过控制沉积条件可成功地沉积压应力、张应力和无应力薄膜。本文还研究了退火膜的特性。退火温度直到～400℃时,內应力几乎不变,但超过～400℃时,便明显地转变为张力。     

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。     

Silicon Nitride Films Deposited by RF Sputtering for Microstructure Fabrication in MEMS

In the present work, we report silicon nitride films deposited by a radio- frequency (RF) sputtering process at relatively low temperatures (<260°C) for microelectromechanical system (MEMS) applications. The films were prepared by RF diode sputtering using a 3-inch-diameter Si₃N₄ target in an argon ambient at 5 mTorr to 20 mTorr pressure and an RF power of 100 W to 300 W. The influence of the film deposition parameters, such as RF power and sputtering pressure, on deposition rate, Si-N bonding, surface roughness, etch rate, and stress in the films was investigated. The films were deposited on single/double-side polished silicon wafers and transparent fused-quartz substrates. To explore the RF-sputtered silicon nitride film as a structural material in MEMS, microcantilever beams of silicon nitride were fabricated by bulk, surface, and surface-bulk micromachining technology. An RF-sputtered phosphosilicate glass film was used as a sacrificial layer with RF-sputtered silicon nitride. Other applications of sputtered silicon nitride films, such as in the local oxidation of silicon (LOCOS) process, were also investigated.     

p-Si TFT栅绝缘层用SiN薄膜的研究

以NH3和SiH4为反应源气体,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)衬底上沉积了一系列SiN薄膜,并利用椭圆偏振测厚仪、超高电阻-微电流计、C-V测试仪对所沉积的薄膜作了相关性能测试.系统分析了沉积温度和射频功率对SiN薄膜的相对介电常数、电学性能及界面特性的影响.分析表明,沉积温度和射频功率主要是通过影响SiN薄膜中的Si/N比影响薄膜的性能,在制备高质量的p-Si TFT栅绝缘层用SiN薄膜方面具有重要的参考价值.     

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。     

Comparative reliability study of GaAs power MESFETs: mechanisms for surface-induced degradation and a reliable solution

A gradual degradation has been observed in the RF performance of GaAs power FETs. Electrical and physical analyses have been carried out, indicating the role played by the surface. A plasma enhanced chemical vapour deposited silicon nitride film is established as a suitable surface passivation.     

采用SiO2/SixNy双材料微桥测试结构测量PECVD富硅氮化硅薄膜的导热系数

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.     

Optimization of nitride films for linear pre-metal dielectric process

With applications in current semiconductor manufacturing, the characteristics of nitride films were investigated for the optimization of pre-metal dielectric (PMD) linear nitride process. For the purpose of this study, the deposit condition of nitride films was divided into four areas such as protected overcoat (PO) nitride process, baseline process, low hydrogen process, and low hydrogen process with high stress, respectively. The correlation between boro-phospho-silicate-glass (BPSG) depositions and their densification was also examined and Fourier transform infrared spectroscopy (FTIR) area method was used to analyze the change of Si-H and Si-NH-Si bonding density. In addition, the generation of cracks on the wafer edge was evaluated after BPSG densification. The stress changes of nitride film as a function of radio frequency (RF) power variation were used to determine the quality of the deposited films. Resultantly, the low hydrogen process was recommended as an optimized condition for linear PMD nitride film.     

Hot-carrier injection suppression due to the nitride-oxide LDDspacer structure

The hot-carrier effects in silicon nitride lightly doped drain (LDD) spacer MOSFETs are discussed. It is found that the oxide thickness under the nitride film spacer affects the hot-carrier effects. The thinner the LDD spacer oxide becomes, the larger the initial drain current degradation becomes at the DC stress test and the smaller the stress time dependence becomes. After the DC stress test, reduced drain current recovers at room temperature. These phenomena are due to the large hot-carrier injection into the LDD nitride spacer, because the nitride film barrier height is much less than the silicon oxide barrier height. Therefore, it is necessary to form the LDD spacer oxide, in order to suppress the large hot-carrier injection in the nitride film LDD spacer MOSFET. The drain current shift mechanism in the nitride spacer MOSFETs is discussed, considering the lucky electron model