Low temperature plasma enhanced chemical vapor deposition of silicon oxide films using disilane and nitrous oxide

Silicon oxide films have been deposited between room temperature and 300°C using disilane and nitrous oxide by plasma enhanced chemical vapor deposition. Film deposition was investigated as a function of the gas flow ratio of nitrous oxide to disilane, the substrate temperature, the total gas flow rate, the radio frequency discharge power, and the process pressure. The stoichiometric SiO₂ films were obtained when the gas ratio of nitrous oxide to disilane was in the range of 50-150. The deposition was found to be nearly temperature independent indicating the mass transport limited regime.     

Effects of nitrogen doping on the growth and properties of plasma-enhanced chemical-vapor-deposited diamond-like-carbon films

Nitrogen-doped diamond-like carbon (DLC) or amorphous hydrogenated carbon (a-C:H) films were grown by plasma enhanced chemical vapor deposition using methane and nitrogen gases as precursors. The effects of nitrogen trifluoride (NF₃) on these nitrogen-doped DLC films were also investigated. The deposition rate decreases sharply with the addition of nitrogen in the absence of NFF₃ due to dilution, while it increases in the presence of NFF₃ due, presumably, to the reduction of activated hydrogen species by the fluorine radical (F϶. X-ray photoelectron spectra reveal a nitrogen concentration in the range of 9.3 to 13.8% in these DLC films with a C Is electron binding energy of 287-288 eV, indicating the diamond-like structure. Infrared spectra of DLC films indicate the presence of amino groups (N-H) and nitrile and/or isonitrile (C= N) groups giving strong evidence of sp carbon. Diamond like carbon films deposited in CHF₄ +NF₄ (with and without NFF₃) have a lower refractive index, a lower bulk resistivity, and a lower optical bandgap than films deposited using CHF₄ due to a lower hydrogen content in the films. Moreover, the bulk resistivity of these films decreases by over four orders of magnitude and the optical bandgap decreases from 2.65 eV to about 0.75 eV following annealing at a temperature of 500°C.     

Effect of Radio-Frequency and Low-Frequency Bias Voltage on the Formation of Amorphous Carbon Films Deposited by Plasma Enhanced Chemical Vapor Deposition

The effect of radio-frequency （RF） or low-frequency （LF） bias voltage on the for- mation of amorphous hydrogenated carbon （a-C：H） films was studied on silicon substrates with a low methane （CH4） concentration （2-10 vol.%） in CH4＋Ar mixtures. The bias substrate was applied either by RF （13.56 MHz） or by LF （150 kHz） power supply. The highest hardness values （~18-22 GPa） with lower hydrogen content in the fihns （~20 at.%） deposited at 10 vol.% CH4, was achieved by using the RF bias, However, the films deposited using the LF bias, under similar RF plasma generation power and CH4 concentration （50 W and 10 vol.%, respectively）, displayed lower hardness （~6-12 GPa） with high hydrogen content （~40 at.%）. The structures analyzed by Fourier Transform Infrared （FTIR） and Raman scattering measurements provide an indication of trans-polyacetylene structure formation. However, its excessive formation in the films deposited by the LF bias method is consistent with its higher bonded hydrogen concentration and low level of hardness, as compared to the film prepared by the RF bias method. It was found that the effect of RF bias on the film structure and properties is stronger than the effect of the low-frequency （LF） bias under identical radio-frequency （RF） powered electrode and identical PECVD （plasma enhanced chemical vapor deposition） system configuration.     

C元素对N型a-Si:H薄膜微结构及电学特性的影响

采用等离子增强化学气相沉积(PECVD)工艺,制备了P-C二元复合掺杂氢化非晶硅(a-Si:H)薄膜,研究了C元素对N型a-Si:H薄膜暗电导率(σ)及电导激活能(Ea)的影响;利用激光拉曼光谱研究了C元素对薄膜微结构的影响,讨论了P-C二元复合掺杂a-Si:H薄膜电学性能与微结构之间的相互影响关系.结果表明:随着C掺杂量的增加,a-Si:H薄膜的短程有序度降低,中程有序度基本保持不变,缺陷逐渐减少;一定程度的C掺杂可使N型a-Si:H薄膜电导激活能降低而使薄膜的暗电导率升高,但过量的C掺杂使N型a-Si:H薄膜非晶网络结构有序度严重恶化,电导率出现明显下降趋势.

Abstract：

Hydrogenated amorphous silicon (a-Si:H) thin films doped with P and C were deposited by plasma enhanced chemical vapor deposition (PECVD).The influence of carbon on the dark conductivity,activation energy and mirostructure of the P-doped a-Si:H films was investigated by means of electrical measurment and Raman spectroscopy,and the relationship between electrical properties and microstructure of the films was also analyzed.It is shown from Raman spectra that the degree of short-range order and the defects of the films decreae with the increase of carbon doping,while the degree of intermediate-range order remains unchanged.A small amount of carbon can reduce the activation energy and enhance the dark conductivity of the P-doped a-Si : H thin films.However,excessive carbon makes the structural order of the amouphous network get worse which leads to a decline of dark conductivity.     

喇曼光谱研究硅烷体积分数对Si薄膜结构影响

采用等离子体增强化学气相沉积(PECVD)技术,在一定射频功率、衬底温度和气压下,在普通玻璃衬底上制备了不同硅烷体积分数的Si薄膜材料.使用喇曼光谱对薄膜材料的结构进行了研究.结果表明,随着硅烷体积分数的降低,Si薄膜沉积速率将会逐渐降低.当硅烷体积分数降到2%时,喇曼光谱检测到出现对应的晶体Si的吸收峰,而最初的非晶吸收峰位逐渐减弱.Si薄膜的结构实现了由非晶向微晶转变.随着硅烷体积分数进一步降低,结晶率不断提高,微晶比例进一步扩大.     

PECVD沉积SiOP电介质膜及其XPS研究

采用等离子体增强化学气相沉积(PECVD)技术沉积含P电介质薄膜,用于无杂质空穴扩散(IFVD)技术中InGaAsP-InP MQW结构中新的包封层,替代传统的SiO2层。经X射线光电子谱(XPS)研究证明,该膜就是SiOP结构。快速退火(RTA)研究表明,该膜结构基本稳定,但膜中P原子存在明显扩散,它增强了InPMQW结构中In原子的外扩,却抑制了Ga原子的外扩。这些都明显区别于常规SiO2膜的性质。     

ZnO Thin Film, Device, and Circuit Fabrication using Low-Temperature PECVD Processes

We report undoped ZnO films deposited at low temperature (200°C) using plasma-enhanced chemical vapor deposition (PECVD). ZnO thin-film transistors (TFTs) fabricated using ZnO and Al₂O₃ deposited in situ by PECVD with moderate gate leakage show a field-effect mobility of 10 cm²/V s, threshold voltage of 7.5 V, subthreshold slope <1 V/dec, and current on/off ratios >10⁴. Inverter circuits fabricated using these ZnO TFTs show peak gain magnitude (dV _out/dV _in) ~5. These devices appear to be strongly limited by interface states and reducing the gate leakage results in TFTs with lower mobility. For example, ZnO TFTs fabricated with low-leakage Al₂O₃ have mobility near 0.05 cm²/V s, and five-stage ring-oscillator integrated circuits fabricated using these TFTs have a 1.2 kHz oscillation frequency at 60 V, likely limited by interface states.     

Hydrogen-assisted low-temperature plasma-enhanced chemical vapor deposition of thin film encapsulation layers for top-emission organic light-emitting diodes

In this work, we developed a single high-performance SiN_x encapsulation layer that can be directly integrated into organic devices by low-temperature plasma-enhanced chemical vapor deposition (PECVD). We investigated a hydrogen-assisted low-temperature PECVD process at a temperature of 80 °C. The thin film density improved with an increased hydrogen gas ratio, and the moisture permeability was less than 5 × 10⁻⁵ g/m²·day. To verify the stability of the PECVD process, we applied the SiN_x encapsulation layer directly to top-emitting organic light-emitting diodes. The results showed minor changes in the current-density–voltage characteristics after the PECVD process, as well as high reliability after a water dipping test.     

DLTS技术研究富氮SiOxNy薄介质膜的电学特性

采用深能级瞬态谱技术（ＤＬＴＳ）,测试了等离子体增强化学汽相淀积（ＰＥＣＶＤ）法低温制备的富氮的ＳｉＯｘＮｙ栅介质膜的电学特性（界面态密度、俘获截面随禁带中能量的变化关系）,结果表明,采用合适的ＰＥＣＶＤ低温工艺淀积ＳｉＯｘＮｙ膜可以制备性质优良的栅介质膜。     

Remote plasma-enhanced CVD of silicon nitride films: effects of diluting nitrogen with argon. Part I: effect on nitrogen plasma parameters studied by emission spectroscopy

In a series of two papers we describe the effect of argon dilution of the nitrogen passed through the RF discharge region on the plasma composition, growth rate and some characteristics of silicon nitride films deposited by remove PECVD. In this part we report the results of an emission spectroscopic study of the plasma obtained in an SiH₄–N₂–Ar mixture. It is shown that argon in metastable electronic excited states plays an important role during the RPECVD of silicon nitride films by providing a high concentration of atomic nitrogen which is necessary for the promotion of film growth. In Part II the influence of argon dilution on the growth rate, composition and some properties of silicon nitride films deposited by capacitively and inductively coupled remote PECVD is discussed. © 1998 John Wiley & Sons, Ltd.