等离子体增强化学气相低温沉积碳化硅薄膜及其性质研究

用等离子体增强化学气、相沉积（PECVD）方法,以CH4和SiH4为反应气体,在低电极温度（180℃）条件下制备了碳化硅薄膜．实验结果表明,低电极温度条件下沉积参数（反应气体流量比、反应气体压力、射频功率）的变化对薄膜的沉积和性质影响较大．制得的薄膜均匀性良好,其化学组成Si／C在0．72-4．0之间,具有（5-9）×109dyn／cm2的压应力．红外光谱结果证明,随着薄膜化学成分的变化,薄膜的结构也改变。同氮化硅薄膜相比,制得的碳化硅薄膜具有良好的抗溶液腐蚀性．     

有机发光器件的低温氮化硅薄膜封装

利用等离子体化学气相沉积(PECVD)技术，采用不同的沉积条件(20—180℃的基板温度范围和10—30W的射频功率)制备了氮化硅薄膜，研究了沉积条件对氮化硅薄膜性质和防水性能的影响。实验发现随着基板温度的增加，氮化硅薄膜的密度、折射率和Si／N比相应增加，而沉积速率和H含量相应减少；随着射频功率的增加，氮化硅薄膜的沉积速率、密度、折射率和Si／N比相应增加，而H含量相应减少。水汽渗透实验发现即使基板温度降低为50℃，所沉积的氮化硅薄膜仍然具有良好的防水性能。实验结果表明低温氮化硅薄膜可以有效地应用于有机发光器件（OLED)的封装。     

ICP-CVD设备低温制备低应力氮化硅薄膜工艺的探索北大核心CSCD

制备低应力的氮化硅薄膜是微机械系统和集成电路中非常重要的工艺。在温度不高于80℃的条件下,采用ICP-CVD设备,利用硅烷和氮气作为前驱体沉积氮化硅介质薄膜。研究了沉积温度、ICP功率、硅烷与氮气流量比例、工作气压等因素对氮化硅薄膜应力的影响,并利用相关的理论合理解释了应力随不同工艺参数变化的原因。根据研究结果,我们优化了氮化硅薄膜沉积的工艺参数,在70℃低温条件下,制备出厚度160 nm,应力0.03 MPa的低应力氮化硅介质薄膜。     

ICP-CVD设备低温制备低应力氮化硅薄膜工艺的探索

制备低应力的氮化硅薄膜是微机械系统和集成电路中非常重要的工艺。在温度不高于80℃的条件下,采用ICP-CVD设备,利用硅烷和氮气作为前驱体沉积氮化硅介质薄膜。研究了沉积温度、ICP功率、硅烷与氮气流量比例、工作气压等因素对氮化硅薄膜应力的影响,并利用相关的理论合理解释了应力随不同工艺参数变化的原因。根据研究结果,我们优化了氮化硅薄膜沉积的工艺参数,在70℃低温条件下,制备出厚度160 nm,应力0.03 MPa的低应力氮化硅介质薄膜。     

超高真空（UHV）PECVD系统沉积a—Si1—xCx：Hk薄膜及其特性

本文研究了应用新型的超高真空等离子增强化学了相沉积（ＶＨＶ－ＰＥＣＶＤ）复合腔系统 只ａ－Ｓｉ１－ｘＣｘ：Ｈｋ薄膜及其特性。系统的真空度可达１０＾－７Ｐａ（１０＾－９Ｔｏｒｒ）以上。通过控制Ｈ２对常规用混合气体（ＳｉＨ４＋ＣＨ４）的稀释程度以及相应的ＣＨ４比例,优化沉积工艺参数,制备出能带宽度范围变化较大的高质量非晶氢化硅碳（ａ－Ｓｉ１－ｘＣｓ：Ｈｋ）薄膜,通过ＲＢＳ、ＥＲＤＡ、ＩＴ和Ｒａｍａｍ光     

离子束轰击对电子束蒸发制备二氧化钛薄膜应力的影响

在硅基底上用电子束蒸发方法制备了二氧化钛薄膜.通过XRD、AFM和薄膜应力测试仪研究了离子束轰击对薄膜应力的影响规律.结果表明沉积温度为323K、沉积速率为0.2nm·s-1时,二氧化钛薄膜具有较小的应力值,平均应力为48.2MPa.用能量为113eV的离子束轰击300s时,平均应力由72.9MPa的张应力变为16.7MPa的压应力.二氧化钛薄膜的微观结构变化是影响薄膜应力的主要因素.     

用ECRCVD方法制备优质氮化硅钝化膜

利用电子回旋共振等离子体化学气相沉积(ECR—CVD)技术，以SiH4和N2为反应气体进行了氮化硅钝化薄膜的低温沉积技术的研究。采用原子力显微镜、傅立叶变换红外光谱和椭圆偏振光检测等技术对薄膜的表面形貌、结构、厚度和折射率等性质进行了测量。结果表明，采用ECR—CVD技术能够在较低的衬底温度条件下以较高的沉积速率制备厚度均匀的氮化硅薄膜，薄膜中H含量很低。薄膜沉积速率随微波功率和混合气体中硅烷比例的增加而增大。折射率随微波功率的增大而减小，随混合气体中硅炕比例的增大而增大。在相同气体混合比和微波功率条件下，较高衬底温度条件下制备的薄膜折射率较大。     

类金铡石薄膜内应力的测试

采用射频－直流等离子增强化学气相沉积法制备出类金刚石薄膜，用弯曲法测定薄膜的内应力。类金刚石薄膜中存在１－４．７ＧＰａ的压应力，沉积工艺对薄膜的内应力有很大影响，薄膜的内应力随极板负偏压的升高而降低，随Ｃ２Ｈ２气体一的增加而增大。     

高氢稀释硅烷加乙烯法制备纳米硅碳薄膜

在等离子体化学气相沉积系统（ＰＥＣＶＤ）中，使用高氢稀释硅烷（ＳｉＨ４）加乙烯（Ｃ２Ｈ４）为反应气氛制备了纳米硅碳（ｎｃ－ＳｉＣｘ＾２Ｈ）薄膜，随着（Ｃ２Ｈ４＋ＳｉＨ４）／Ｈ２（Ｘｇ）从５％时，由于Ｈ蚀刻效应的减弱，薄膜的晶态率从４８％下降到８％，平均晶粒尺寸在３．５－１０ｎｍ。当Ｘｇ≥６％时，生成薄膜为非晶硅碳（ａ－ＳｉＣｘ＾２Ｈ）薄膜。ｎｃ－ＳｉＣｘ＾２Ｈ薄膜的电学性质具有与薄膜的晶态率紧密相     

APCVD制备氮化硅薄膜的微观结构

以ＳｉＨ４和ＮＨ３作为反应气体,用常压化学气相沉积（ＡＰＣＶＤ）法在平板玻璃表面制备出了氮化硅薄膜,研究氮化硅薄膜的形貌和微观结构,研究结果表明：在６６０℃温度所获得的氮化硅薄膜为非晶态,氮化硅薄膜与平板玻璃基板之间的界有熔焊现象,结合牢固。     

Effect of deposition temperature and thermal annealing on the dry etch rate of a-C: H films for the dry etch hard process of semiconductor devices

The effect of deposition and thermal annealing temperatures on the dry etch rate of a-C:H films was investigated to increase our fundamental understanding of the relationship between thermal annealing and dry etch rate and to obtain a low dry etch rate hard mask. The hydrocarbon contents and hydrogen concentration were decreased with increasing deposition and annealing temperatures. The I(D)/I(G) intensity ratio and extinction coefficient of the a-C:H films were increased with increasing deposition and annealing temperatures because of the increase of sp² bonds in the a-C:H films. There was no relationship between the density of the unpaired electrons and the deposition temperature, or between the density of the unpaired electrons and the annealing temperature. However, the thermally annealed a-C:H films had fewer unpaired electrons compared with the as-deposited ones. Transmission electron microscopy analysis showed the absence of any crystallographic change after thermal annealing. The density of the as-deposited films was increased with increasing deposition temperature. The density of the 600 °C annealed a-C:H films deposited under 450 °C was decreased but at 550 °C was increased, and the density of all 800 °C annealed films was increased. The dry etch rate of the as-deposited a-C:H films was negatively correlated with the deposition temperature. The dry etch rate of the 600 °C annealed a-C:H films deposited at 350 °C and 450 °C was faster than that of the as-deposited film and that of the 800 °C annealed a-C:H films deposited at 350 °C and 450 °C was 17% faster than that of the as-deposited film. However, the dry etch rate of the 550 °C deposited a-C:H film was decreased after annealing at 600 °C and 800 °C. The dry etch rate of the as-deposited films was decreased with increasing density but that of the annealed a-C:H films was not. These results indicated that the dry etch rate of a-C:H films for dry etch hard masks can be further decreased by thermal annealing of the high density, as-deposited a-C:H films. Furthermore, not only the density itself but also the variation of density with thermal annealing need to be elucidated in order to understand the dry etch properties of annealed a-C:H films.     

Hydrogen plasma transport and deposition of films from a solid boron source

Thin boron films were produced on Si substrates from a solid boron source and a hydrogen plasma. The plasma was generated using a 13.56 MHz generator and films were deposited with a forward radio frequency (RF) power of 2.0 kW. At pressures from 0.931–2.26×102 Pa under high hydrogen concentrations a capacitively coupled plasma (CCP) was observed whereas at low hydrogen concentrations an inductively coupled plasma (ICP) was observed. The films were predominantly deposited with an ICP but in one case a film was deposited using a CCP discharge. The deposited films consisted primarily of boron, but they also contained oxygen and silicon. The films were amorphous at 225 and 350°C, but revealed X-ray diffractions at 475°C. It was concluded that the hydrogen concentration, RF plasma power and surface temperature as well as the plasma-boron source interactions strongly influenced the film thickness and composition.     

Influence of substrate properties on the growth of titanium films: Part II

In situ internal stress measurements were used to investigate the influence of the chemical properties of the substrate on the growth of a titanium film deposited under UHV conditions. The substrate films used were titanium films evaporated at different water partial pressures. When the titanium film is evaporated at substrate temperatures of 130 °C and higher the shape of the stress vs thickness curve is interpreted to indicate island growth. Comparing the internal stress curve of titanium on Al₂O₃ and Ti/H₂O substrates it is seen that the initial tensile stress is significantly larger on the Ti/H₂O substrate film. This larger tensile stress is interpreted to originate from a redistribution of oxygen at the substrate interface during the early growth stage of the clean titanium film. A compressive stress contribution at higher thickness of the titanium film is interpreted to be due to hydrogen interdiffusion from the substrate into the titanium film. Annealing of the Ti/H₂O substrate films at 350 °C for 20 min reduces the concentration of the surface oxygen species and the amount of hydrogen incorporated in the films.

Dosing of previously annealed Ti/H₂O substrate films with water affects both the oxygen concentration on the surface of these substrate films and the amount of hydrogen incorporated in the films. Oxygen dosing of these films only increases the concentration of the oxygen species on the substrate surface; thus only the initial tensile stress built up in the titanium film is affected. Dosing the films with hydrogen, on the other hand, only increases the amount of hydrogen incorporated in the substrate film, which by way of interdiffusion into the growing titanium film gives rise to a larger compressive stress at higher film thickness     

Evolution of internal stress and microstructure in Ti50Cu50 alloy films: influence of substrate temperature and composition

The growth stress of Ti₅₀Cu₅₀ alloy films on alumina substrates was measured in situ under ultrahigh vacuum conditions with a cantilever beam technique as a function of substrate temperature and variation of copper concentration. The growth stress of films deposited at low temperature is interpreted to indicate the growth of amorphous respectively nanocrystalline films. At substrate temperatures above 300 °C, a novel tensile stress contribution is interpreted to be due to the formation of a preferentially oriented film of metastable copper vacancy superstructured γ-TiCu. Finally, at substrate temperatures above 365 °C, a polycrystalline γ-TiCu film is formed.Annealing of low-temperature alloy films gives rise to irreversible tensile stress changes indicating restructuring of the films. The stress change measured when annealing a superstructured γ-TiCu film is compressive and is assigned to the transformation of the metastable superstructure to polycrystalline γ-TiCu. The magnitude of this compressive stress contribution is strongly dependent on the copper concentration, i.e., copper vacancy concentration.     

The influence of deposition rate on the stress and microstructure of AlN films deposited from a filtered cathodic vacuum arc

Aluminium nitride (AlN) thin films have been reactively deposited using a filtered cathodic vacuum arc system. A pulsed substrate bias was applied in order to increase the average energy of the depositing species. The stress and microstructure of the films were determined as a function of the deposition rate and pulse bias amplitude/frequency. The stress generated in films grown with high voltage pulsed bias depended on the deposition rate and a transition from tensile stress to compressive stress occurred as the deposition rate increased. This trend was accompanied by progressive changes in the microstructure. In order of increasing deposition rate, the films exhibited: a porous structure with tensile stress; a dense AlN film with compressive stress; and a dense AlN film showing evidence of a thermally induced reduction in stress.     

Residual stress in silicon films deposited by LPCVD from disilane

Measurements of the thermomechanical stress in amorphous silicon films deposited by low pressure chemical vapour deposition (LPCVD) from disilane Si₂H₆ are reported as a function of the deposition parameters (temperature, gas pressure and wafer spacing). Major influences of the deposition temperature and the deposition rate are put into evidence and related to the films ordering and hydrogenation. The effects of a 600°C anneal are also investigated and a transition from highly compressive to highly tensile stress is characterised whatever the deposition. Such behaviour has been explained thanks to hydrogen atoms out-diffusion and crystallisation effects.     

Internal stress and structure of evaporated chromium and MgF2 films and their dependence on substrate temperature

The internal stress in chromium and MgF₂ films was measured by the cantilever beam method. The substrate temperature, which was kept constant during the film deposition, could be varied up to 500°C. At room temperature both materials exhibit only tensile stress over the whole thickness range. At higher temperature for both materials compressive as well as tensile stresses are found as the film thickness increases. Similar stress versus thickness curves have previously been obtained for the low melting point metals silver, copper and gold deposited at room temperature. The model for the origin of the internal stress proposed to interpret the stress curves of the metals of the copper group is again applicable. Thus the changes in the stress curves obtained at different substrate temperatures can again be correlated with changes in the growth mode and thus the structure of the respective films. The structure determined on the basis of the stress model agrees with the film structure visible in the electron microscope.     

Massive stress changes in plasma-enhanced chemical vapor deposited silicon nitride films on thermal cycling

Massive irreversible increases in tensile stress (up to 2 GPa) on thermal cycling are demonstrated for plasma-enhanced chemical vapor deposited (PECVD) silicon nitride films. Results give further evidence for the claim that this phenomenon is generic to PECVD films and is attributable to the removal of bonded hydrogen: the magnitude of stress increase is independent of the film stress and can be accounted for with a calculation involving the amount of evolved hydrogen. The massive stress changes cause film fracture in most of the films discussed here, with a large diversity of fracture behavior exhibited. The effects of deposition conditions (temperature, plasma frequency, substrate) on film modulus, hardness and coefficient of thermal expansion, as well as stress and stress hysteresis are also examined.     

Stability of plasma-deposited SiO2 films evaluated using stress and IR measurements

The plasma deposition conditions required to produce near-stoichiometric SiO₂ films with excellent stability against humidity and annealing were clarified. The film stability was evaluated by means of internal film stress and IR measurements. Films deposited at low N₂O-to-SiH₄ ratios typically exhibit compressive stress on silicon substrates. The compressive stress increased within a few days on exposure of the films to an ambient environment. The change in stress was accelerated when the films were subjected to an 83% humidity test at 80 °C but was prevented in vacuum. The change in the IR absorption signal corresponding to H₂O was consistent with the stress change. These results suggest that the stress change is caused by water permeation into the film. The stress instability against humidity was drasttically improved by increasing the N₂O-to-SiH₄ ratio. At an N₂O-to-SiH₄ ratio of 100, films stable against the humidity test were obtained. The film quality, determined from the p etch rate, was found to be further improved by increasing the power density and by decreasing the chamber pressure. Spectra obtained using electron spectroscopy for chemical analysis revealed that the films stable against humidity were near-stoichiometric SiO₂.     

残余应力对SrRuO3薄膜磁学及电输运性能的影响

采用射频磁控溅射法在单晶SrTiO₃ (STO)衬底和硅(Si)衬底上制备出不同取向的SrRuO₃ (SRO)薄膜, 对薄膜的残余应力进行了分析, 并研究了应力对不同取向SRO薄膜磁学性能与电输运特性的影响。根据X射线衍射(XRD)结果分析可知, Si基SRO薄膜为多晶单轴取向薄膜, 且应力来源主要为热失配拉应力; STO基SRO薄膜为外延薄膜, 其应力主要为热失配压应力和外延压应力; 磁学性能测试表明, (001)取向SRO薄膜比(110)取向薄膜拥有更高的居里温度T_C; 压应力提高了(001)取向SRO薄膜的T_C, 却降低了(110)取向薄膜的T_C。电阻性能测试表明, 对于在同种类型衬底上沉积的SRO薄膜, (001)取向的薄膜的剩余表面电阻比(RRR)高于(110)取向的薄膜。另外, 拉应力引起了薄膜微结构的无序度增加, 弱化了表面电阻率的温度依赖性, 提高了金属绝缘体转变温度(T_MI)。