化学气相沉积生长氧化铪薄膜研究进展

氧化铪薄膜具有高介电常数、大击穿场强、高热稳定性、高力学强度等优势,是新一代高集成芯片中的理想介质材料。本文总结了氧化铪薄膜的主要特性、制备技术及在芯片介质层中的应用。针对芯片介质层的电、热、力学性能与生产要求,以氧化铪薄膜制备技术的发展历程为主线,重点介绍各类化学气相沉积方法的特点与典型研究成果,讨论了氧化铪薄膜制备技术存在的问题,并对该领域未来的发展趋势进行了展望。     

Elimination of Voids at Interface of <Emphasis Type="Italic">β</Emphasis>-SiC Films and Si Substrate by Laser CVD

Void-free β-SiC films were deposited on Si(001) substrates by laser chemical vapor deposition using hexamethyldisilane (HMDS) as the precursor. The effect of the time of introducing HMDS, i e, the substrate temperature when HMDS introduced (T_in), on the preferred orientation, surface microstructure and void was investigated. The orientation of the deposited SiC films changed from <001> to random to <111> with increasing T_in. The surface showed a layer-by-layer microstructure with voids above T_in ? 773 K, and then transformed into mosaic structure without voids at T_in= 298 K. The mechanism of the elimination of voids was discussed. At T_in =298 K, Si surface can be covered by an ultrathin SiC film, which inhibits the out-diffusion of Si atoms from substrate and prohibites the formation of the voids.     

Morphology study of oriented SmBCO film deposited by MOCVD

c-axis-oriented SmBa_2Cu_3O_7(SmBCO) films have been deposited on(100)- LaA1O_3(LAO)substrate by metal organic chemical vapor deposition(MOCVD) technique.The effects of deposition temperature(T_(dep)) and total pressure(P_(tot)) on the orientation and microstructure of SmBCO films were investigated.The orientation of SmBCO films transformed from α-axis to c-axis with increasing of T_(dep) from 900 to 1 100℃.At T_(dep)=1 050℃,SmBCO films had c-axis orientation and tetragon surface.At P_(tot)~(dep)=400-800 Pa and T_(dep)=1 050 ℃,totally c-axis-oriented SmBCO films were obtained.The R_(dep) of SmBCO films increased firstly and then decreased with increasing P_(tot).The surface of SmBCO films exhibited tetragon morphology at 1 050 ℃ and400 Pa.Maximum thickness of SmBCO film deposited was 1.2μm at P_(tot)= 600 Pa,and the corresponding R_(dep)was 7.2 μm·h~(-1).     

Effects of annealing processes on Cu<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Si<Subscript>1-<Emphasis Type="Italic">x</Emphasis></Subscript> thin films

The Cu _x Si_1-x thin films have been grown by pulsed laser deposition (PLD) with in situ annealing on Si (001) and Si (111), respectively. The transformation of phase was detected by X-ray diffraction (XRD). The results showed that the as-deposited films were composed of Cu on both Si (001) and Si (111). The annealed thin films consisted of Cu + η”-Cu₃Si on Si (001) while Cu + η’-Cu₃Si on Si (111), respectively, at annealed temperature (T _a) = 300-600 °C. With the further increasing of T _a, at T _a= 700 °C, there was only one main phase, η”-Cu₃Si on Si (001) while η’-Cu₃Si on Si (111), respectively. The annealed thin films transformed from continuous dense structure to scattered-grain morphology with increasing T _a detected by field emission scanning electron microscope (FESEM). It was also showed that the grain size would enlarge with increasing annealing time (t _a).     

Ni3Al对TiC的润湿性及Mo添加的影响

为了研究Ni₃Al/TiC之间的润湿性,本工作利用两种Ni₃Al,即熔炼方法制备的块体Ni₃Al、SHS方法制备的Ni₃Al粉末,和致密TiC基板,通过高温摄影显微镜实验测定了Ni₃Al-TiC之间的接触角。结果表明:无论哪一种Ni₃Al,它们与TiC之间的接触角都在18°以内,表现出与TiC之间的良好的润湿性;当Ni₃Al压粉体中掺入少量Mo时,接触角降为11°左右。用XRD、EPMA等方法分析和观察了实验样品的组成、结构、断面形貌及其元素分布。探讨了Mo对改善Ni₃Al-TiC润湿性的作用机理。     

Elimination of Voids at Interface of β-SiC Films and Si Substrate by Laser CVD

Void-free β-SiC films were deposited on Si(001) substrates by laser chemical vapor deposition using hexamethyldisilane(HMDS) as the precursor. The effect of the time of introducing HMDS, i e, the substrate temperature when HMDS introduced(T_(in)), on the preferred orientation, surface microstructure and void was investigated. The orientation of the deposited SiC films changed from 001 to random to 111 with increasing T_(in). The surface showed a layer-by-layer microstructure with voids above T_(in) ≥ 773 K, and then transformed into mosaic structure without voids at T_(in)= 298 K. The mechanism of the elimination of voids was discussed. At T_(in) =298 K, Si surface can be covered by an ultrathin SiC film, which inhibits the out-diffusion of Si atoms from substrate and prohibites the formation of the voids.     

Mg掺杂对二钛酸钡(BaTi_2O_5)的介电性能的影响

采用电弧熔炼法成功制备了b轴取向的MgO置换二钛酸钡(BaTi2O5)多晶体Ba1-xMgxTi2O5,结果表明,MgO的置换显著增大了多晶体Ba1-xMgxTi2O5介电常数的数值,当MgO的置换量x为0.005时电弧熔炼法制得的多晶体Ba1-xMgxTi2O5的介电常数出现最大值为3 250. 多晶体Ba1-xMgxTi2O5的居里温度随着MgO的添加量的增加而有所降低.     

激光化学气相沉积快速生长高取向TiN_x薄膜的研究

采用激光化学气相沉积（LCVD）技术在氧化铝衬底上制备了高取向的TiN_x薄膜,重点研究了激光功率（PL）、衬底预热温度（T_pre）和沉积总压力（P_tot）对薄膜取向和沉积速率的影响,采用X射线衍射（XRD）、俄歇能谱（AES）和场发射扫描电镜（FESEM）对薄膜组成和结构进行了表征.结果表明：所得到的TiN_x薄膜成分均匀,其取向与衬底预热温度有关,随着预热温度的升高,TiNx薄膜的取向由（111）变为（200）,薄膜的取向与其微观结构一致.TiN_x薄膜的沉积速率随着激光功率升高而增大,在P_L=100W时,达到最大值90μm/h（沉积面积为300mm²）,显著高于采用其它方法制备的TiN_x薄膜.     

Catalytic Decomposition of Nitric Oxide by LaCoO<Subscript>3</Subscript> Nano-particles Prepared by Rotary CVD

Catalytic direct decomposition of NO by perovskite-type catalysts has attracted much attention for the various possible components and the unique structure. LaCoO₃ nanoparticles were precipitated on α-Al₂O₃ micro powders by rotary chemical vapor deposition (rotary CVD) and its catalytic performance for the decomposition of NO was investigated. LaCoO₃ nano-particles with 100 nm in average diameter and 1.5% in mass were uniformly dispersed on α-Al₂O₃ powder. The conversion of NO increased with increasing temperature from 400 to 950 °C, and reached 28.7% at 950 °C. The gas velocity of transformed NO on LaCoO₃ nano-particles catalyst per mass unit was 7.7 mL/(g min), showing a good catalytic activity over the calculated results of pure catalysts. After five times of aging performance experiments, the NO conversion kept the same value, showing a good aging performance and thermal stability.     

Mo添加对Ni3Al-TiC润湿特性的影响机制研究

采用2AP－LEITZ高温显微镜对Ni3Al-TiC的润湿接触角进行了实验测定，着重探讨了Ni3Al对TiC的润湿特性以及Ni3Al中添加少量Mo的影响机制。结果表明，TiC与Ni3Al之间具有良好的润湿性能。5wt%Mo的添加使Ni3Al向TiC基板浸渗的深度增大，并与TiC颗粒发生固溶反应置换出部分Ti，在其周围形成一个含Mo的壳层，在这个壳层里，Ti,Mo进一步与Ni3Al固液，这些反应降低了液－固表面张力，导致了润湿接触角的下降，从而改善了TiC-Ni3Al的润湿性。