PECVD下基底温度对SiC薄膜形态、成分及生长速度的影响

在单晶Si和多晶Cu基底表面上使用等离子体增强化学气相沉积(PECVD)方法沉积了SiC薄膜. 通过高分辨透射电子显微镜(HRTEM)、X射线光电子能谱仪(XPS)及扫描电子显微镜(SEM)研究基底温度对SiC薄膜成分、结构及生长速度的影响规律。结果表明: 在60~500℃基底温度下制备的SiC薄膜均为非晶态薄膜, 薄膜的生长速度随基底温度的升高而线性降低, 并且在相同沉积条件下, 薄膜在Si基底上的生长速度要高于Cu基底。此外, 薄膜中的硅碳原子比随基底温度的升高而降低, 当基底温度控制在350℃左右时, 可以获得硅碳比为1:1较理想的SiC薄膜。     

KMC模拟活性剂作用下的薄膜外延生长

运用动力学蒙特卡罗方法模拟了两种原子组成的薄膜外延生长时的形貌,给出了一种原子作为活性剂时的同质外延生长情况,从动力学角度模拟了表面活性剂向上漂浮的行为,模拟结果发现,在原子间结合能满足Eaa〉EBB〉EAB时,在基底上先沉积少量活性剂原子薄膜更趋于向层状模式生长;温度越高,活性剂原子越容易与沉积原子发生交换,薄膜表面更加光滑平整。同时,也发现活性剂原子的漂浮行为对温度有一个敏感的临界温度,大于这个温度时,活性剂原子呈现漂浮行为。     

薄膜生长的计算机模拟

建立了一个比较合理的三维模型,并通过模拟成像和定量计算研究了薄膜生长过程中的两个重要问题,早期成核与表面粗糙度.结果表明,薄膜的长生过程是原子吸附、迁移、脱附、连带等微观过程的积累.随着衬底温度的升高或入射率的降低,沉积在衬底上的原子逐步由各自独立的离散型分布向聚集状态转变形成岛核,并由二维岛核向三维岛核转变.衬底温度越高、入射率越低,成核尺寸越大.存在一个最佳成核温度,成核率出现一个极大值.随着衬底温度的升高,薄膜的粗糙度先降低后来又增加.存在一个生长转变温度Tr,薄膜的粗糙度达到极小值.当衬底温度小于Tr时,入射率越大,薄膜的粗糙度越大.当衬底温度大于Tr时,入射率越大,粗糙度越小.薄膜生长的主要微观机理是原子热运动对薄膜生长的影响.     

化学气相沉积SiC膜{111}取向生长的原子尺度模拟

在化学气相沉积SiC膜过程中, 分别考虑了化学反应的动力学以及基底表面原子的沉积与扩散, 利用动力学蒙特卡罗方法, 建立了SiC膜{111}取向的三维原子尺度模型, 使用MATLAB模拟了原子尺度的SiC膜{111}取向生长过程. 模拟结果表明: 膜的生长经历了小岛的生成、小岛的合并与扩展、小岛间达到动态平衡三个阶段. 随着温度的升高, 膜的生长速率、表面粗糙度以及膜的厚度都增大. 随着生长速率的增大, 表面粗糙度增大, 相对密度减小. 模拟结果与理论和实验具有较好的吻合性.     

Ti薄膜在Si基底上的生长模拟

利用三维动态蒙特卡洛模型模拟了Si基底上沉积Ti薄膜的初始期间的生长特性。模拟结果发现,在扩散截止步长为50的情况下,沉积温度和沉积速率对Ti薄膜初始生长模式和表面形貌有明显的影响。模拟结果表明,随着沉积温度的增加,Ti薄膜的初始晶核尺寸越来越大,数目越来越少,趋于岛状生长模式,同时Ti薄膜的相对密度越来越大,薄膜表面粗糙度也越来越小,即:较高的温度有利于Ti薄膜的岛状生长。随着沉积速率的增大,Ti薄膜表面越来越粗糙,相对密度也越来越小;较大的沉积速率不利于Ti薄膜的生长。     

基底温度对直流磁控溅射制备氮化铜薄膜的影响研究

采用反应直流磁控溅射镀膜法,在氮气分压为0.9Pa、不同基底温度下、玻璃基底上制备了纳米多晶Cu3N薄膜,并研究了基底温度对薄膜结构和性能的影响。结果表明,当基底温度为100℃及以下时,薄膜以[111]方向择优生长为主;在150℃及200℃时,薄膜以[100]方向择优生长为主;250℃时开始出现Cu的[111]方向生长,300℃时已完全不能形成Cu3N晶体,只有明显的Cu晶体。随基底温度的升高,薄膜的沉积速率在13～28nm/min呈U型变化,低温和高温时较高,150℃时最低;薄膜的电阻率显著降低;薄膜的显微硬度先升后降,100℃时显微硬度最大。     

溅射沉积Cu膜生长的Monte Carlo模拟

在本文中,我们建立了一个较完整的基于动力学晶格蒙特卡罗方法的模拟薄膜生长的三维模型,利用该模型我们研究了溅射沉积条件下粒子的沉积角度、沉积速率以及入射能量对Cu膜生长的影响.模拟结果表明Cu膜表面粗糙度会随沉积角度和沉积速率的增大而增大,而相对密度随之减小.模拟的薄膜的三维形貌显示,在薄膜的表面存在着柱状结构,这与实验是相符的.     

沉积速率对EB-PVD Ni-Cr薄膜表面形貌的影响

采用动态蒙特卡罗(KMC)方法模拟电子束物理气相沉积(EB-PVD)制备Ni-Cr合金薄膜过程中沉积速率与薄膜微观结构之间的关系,并用分维理论研究薄膜表面形貌.研究结果表明:对于基板温度为500K,入射角度为35°的情况,沉积速率＜5μm/min时,薄膜表面分维均＜2.04,表面光滑,而当沉积速率＞5μm/min时薄膜分维随沉积速率增大而增大,表面变得越来越粗糙,直到沉积速率升高到1000μm/min时,分维达到最大值2.31,表面非常粗糙,具有细致的皱褶和缺陷.分维与沉积速率间的关系说明低沉积速率有利于分维小、表面光滑薄膜的制备,而高沉积速率使薄膜分维增大、表面结构更加复杂.该研究结果与沉积速率对EB-PVD薄膜表面粗糙度影响的研究结果一致,表明分维也是评价薄膜表面形貌的途径.     

氧等离子体辅助原子层沉积氧化铝的研究

本文研究氧等离子体辅助原子层沉积氧化铝中各个沉积参数对薄膜性能和结构的影响。在氧等离子体辅助原子层沉积氧化铝的过程中,通过改变基底温度、等离子体放电时间、等离子体放电功率、单体三甲基铝冲洗时间和反应气体氧气冲洗时间,研究了工艺参数对于氧化铝的生长的影响。通过发射光谱仪(OES)对等离子体进行检测,原子力显微镜(AFM)和椭偏(SE)对薄膜表面形貌、厚度和折射率进行测量及SEM对薄膜断面进行检测。结果显示,在室温下氧等离子体辅助氧化铝沉积需要较长的单体三甲基铝的冲洗时间才能得到粗糙度小的薄膜,薄膜沉积速率随温度的升高而减小(低的沉积温度),薄膜的折射率则变大。而等离子体在40W到80W的低放电功率下,放电功率对氧化铝的沉积速率影响不大。     

直流磁控溅射制备氮化铜薄膜的热稳定性研究

用直流磁控溅射方法,在氮气分压为0．5Pa、不同的基底温度下,于玻璃基底上制备了Cu3N薄膜。当基底温度为100℃及以下时,温度越高薄膜的结晶程度越好。当基底温度在100℃以上时,随着基底温度的升高,薄膜的结晶程度逐渐减弱,200℃时结晶已很弱,300℃时已完全不能形成Cu3N晶体。薄膜的电阻率随基底温度的变化不大,薄膜的沉积速率随基底温度的升高在18～30nm／min之间近似地线性增大,薄膜的显微硬度随基底温度的升高而略有降低。对基底温度为室温和100℃下制备的氮化铜薄膜进行不同温度下的真空退火,研究了它们的热稳定性。XRD测试表明,薄膜在200℃时开始出现分解,350℃时完全分解。比较在基底温度为室温和100℃下制备的样品,发现室温下制备的氮化铜薄膜比100℃下制备的氮化铜薄膜稳定。     

磁控溅射薄膜生长全过程的计算机模拟研究

本文通过建立多尺度模型,结合模拟了磁控溅射中溅射原子的产生、溅射原子的碰撞传输、以及最终成膜的全过程,研究了基板温度、溅射速率、磁场分布和靶材-基板间距对薄膜生长过程与薄膜性能的影响.模拟结果显示,提高基板温度或降低溅射速率都会增加初期生长阶段薄膜的相对密度;磁场对靶的利用率有显著的影响,而对薄膜最终形貌的影响不大;增大靶材-基板间距会降低薄膜的粗糙度.     

Chemical vapor deposition of aluminum from methylpyrrolidine alane complex

Chemical vapor deposition of aluminum from a recently developed precursor, methylpyrrolidine alane complex, has been studied. Aluminum films deposited on conducting surfaces (titanium nitride, copper, gold), but not on insulating surfaces (silicon, silicon dioxide, glass) at low substrate temperatures, showing deposition selectivity, while the deposition selectivity was lost at high substrate temperatures (> 210 °C). Al deposition rates on TiN and Cu were very close, but much higher than on Au. Deposition rates on all conducting substrates increased with the temperature and reached maximum at 180 °C. Al films deposited on as-sputtered TiN or Cu have no preferred orientations. Al–Au alloys and intermetallics were observed in the films deposited on Au. Surface morphology observation revealed that the film growth on TiN or Cu is different from that on Au. The surface roughness of Al films increased with the deposition time or the film thickness.     

Kinetic Monte Carlo simulation of Cu thin film growth

A three-dimensional kinetic Monte Carlo technique has been developed for simulating the growth of thin Cu films. The model involves incident atom attachment, surface diffusion of the atoms on the growing surface and atom detachment from the growing surface. A significant improvement in calculation of activation barriers for the surface atom diffusion on the growing film was made. The related effects caused by surface atom diffusion were taken into account. The results showed that there exist a transition temperature T_t at a certain deposition rate. When the substrate temperature approaches T_t, the growing surface becomes smoother and the relative density of the films increases. The surface roughness minimizes and the relative density saturates at T_t. The surface roughness increases with increased substrate temperature when the temperature is higher than T_t. T_t is a function of the deposition rate. The influence of the deposition rate on the surface roughness is dependent on the substrate temperature. The simulation results also showed that the relative density decreases with increasing deposition rate and average thickness of the film.     

A computer simulation of nucleation and growth of thin films

A three-dimensional kinetic Monte Carlo technique has been developed for simulating the nucleation and growth of thin films. The model involves incident atom attachment, surface diffusion of the atoms on the growing surface and atom detachment from the growing surface. Related effects caused by atom diffusion were taken into account. A significant improvement in calculation of activation energy for the atom diffusion was made based on a reasonable assumption of interaction potential between atoms. Trace files were created during the simulation and snapshots showing the morphology of the nucleation and growth of the thin films were taken by computer graph technique. The results showed that the density of the nucleus decreases and the size of island nucleation increases with increasing the substrate temperature and decreasing the deposition rate. At the meantime, a transition from two-dimension to three-dimension nucleation was observed. There exist three critical temperatures at a certain deposition rate: T_n at which the nucleation rate reaches maximum, T_r at which the surface roughness minimizes and T_d at which the relative film density saturates. The three critical temperatures are functions of the deposition rate. The nucleation rate is close to constant under lower temperatures while it increases with deposition rate at higher temperatures. The film surface roughness depends on the density of island nucleation, it increases with temperature at lower temperatures and decreases at higher temperatures. The relative film density decreases with increasing the deposition rate.     

Reactive DC Magnetron Sputtering Deposition of Copper Nitride Thin Film

Copper nitride thin film was deposited on glass substrates by reactive DC （direct current） magnetron sputtering at a 0.5 Pa N2 partial pressure and different substrate temperatures. The as-prepared film, characterized with X-Ray diffraction, atomic force microscopy, and X-ray photoelectron spectroscopy measurements, showed a composed structure of Cu3N crystallites with anti-ReO3 structure and a slight oxidation of the resulted film.The crystal structure and growth rate of Cu3N films were affected strongly by substrate temperature. The preferred crystalline orientation of Cu3N films were （111） and （200） at RT, 100℃. These peaks decayed at 200℃ and 300℃ only Cu （111） peak was noticed. Growth of Cu3N films at 100℃ is the optimum substrate temperature for producing high-quality （111） Cu3N films. The deposition rate of Cu3N films estimated to be in range of 18-30 nm/min increased while the resistivity and the microhardness of Cu3N films decreased when the temperature of glass substrate increased.     

离子束溅射制备CuInSe_2薄膜的研究

利用离子束溅射沉积技术,设计三元复合靶,直接制备CuInSe_2(CIS)薄膜.通过X射线衍射仪(XRD)、原子力显微镜(AFM)和分光光度计检测在不同衬底温度和退火温度条件下制备的CIS薄膜的微结构、表面形貌和光学性能.实验结果表明:使用离子束溅射沉积技术制备的CIS薄膜具有黄铜矿结构,在一定的条件下,适当温度的热处理可以制备结构紧密、颗粒均匀、致密性和结晶性良好的CIS薄膜,具有强烈的单一晶向生长现象.     

Growth-induced atomic step ordering on patterned and non-patterned Si(111)

Atomic step configurations on the vicinal surfaces of patterned and non-patterned Si(111) during homoepitaxial step-flow growth were studied as a function of film thickness, deposition temperature, deposition rate, and substrate miscut. We found, for the first time, that step-flow growth on the vicinal surfaces of Si(111) miscut toward the [11 ] direction results in the formation of collective, in-phase zigzag arrays of [2 ]- and [1̄21̄]-type steps. We also found that step-flow growth on the lower-level region around the edge of Si(111) mesa ridges significantly improves period uniformity. We explained the shape of atomic steps on the basis of the stability of surface reconstruction on Si(111), and the atomic step ordering on the assumption of the anisotropic barrier for diffusion at the growing steps.     

平面光波导膜的ECR-PECVD制备及特性研究

采用微波电子回旋共振等离子体增强化学气相沉积技术 ,在单晶硅衬底上制备了用于平面光波导的SiO2 薄膜 ,研究了沉积速率与工艺参数之间的关系 ,并对射频偏置对成膜特性的影响作了初步实验研究。通过X射线光电子能谱、傅立叶变换红外光谱、扫描电镜、原子力显微镜、以及扫描隧道显微镜三维形貌和椭偏仪等测量手段 ,分析了样品的薄膜结构和光学特性等。结果表明 ,在较低温度下沉积出均匀致密、性能优良的SiO2 薄膜。此外 ,还成功制备出掺Ge的SiO2 薄膜 ,并可以精确控制掺杂浓度 ,以适应不同光波导芯的要求