磁控溅射制备SiC薄膜及其电阻温度特性研究

发布时间：2018-04-29 06:11

  本文选题：SiC薄膜 + 磁控溅射技术　； 参考：《南京航空航天大学》2017年硕士论文

【摘要】：SiC作为如今越来越热门的第三代宽禁带半导体材料,拥有热导率高、饱和电子漂移速度高、禁带宽度大、击穿电场高、热稳定性高等一系列特点,因此在航天航空、核电以及大功率高频器件环境中具有广阔的应用前景。本课题选择100方向的单晶Si以及0001方向的单晶蓝宝石(α-Al2O3)两种衬底,利用射频磁控溅射技术制备了适合不同应用条件下的六方晶型SiC薄膜。研究了不同工艺条件对薄膜的物相结构、表面及断面形貌、电阻温度特性的影响,并对不同衬底上的薄膜元件的综合电学特性进行了总结。利用射频磁控溅射技术在100方向的单晶Si及单晶Si/SiO2(200nm)衬底上生长SiC薄膜。通过过渡层、沉积温度、退火前后等工艺参数的调控,在沉积温度750℃等条件下,单晶Si/SiO2(200nm)衬底上,由于薄膜与衬底晶格失配得到一定程度的释放,获得了具有一定取向的六方晶型SiC薄膜。薄膜热运输激活能为0.16eV,由扩展态导电机制主导。过高的沉积或退火温度,都会使该衬底上的SiC薄膜中Si、C原子发生扩散、产生杂相,影响其致密性和电阻温度稳定性。同时,该SiC薄膜在-100~250℃拥有很高的热敏常数B(1400~2000K),经多次重复测试后发现,不同温度下的电阻误差仅±5%,适合制成高精度型热敏电阻器和温度传感器。由于单晶Si衬底适用温度的局限性,为了能在更高温度下应用该SiC薄膜的电学特性,利用射频磁控溅射技术在0001方向的单晶蓝宝石衬底上生长SiC薄膜。在沉积温度750℃、溅射气压纯氩1Pa、射频功率100W、1000℃氩气气氛中快速热退火10min等工艺条件下,薄膜开始向晶态转变,XRD中出现了六方晶型的6H-SiC衍射峰。但由于衬底的巨大拉应力,薄膜晶格畸变,衍射峰都向小角度方向偏移了1~2°,并且薄膜导电机制偏向于扩展态导电,热运输激活能为0.21eV。同时,该SiC薄膜电阻稳定变化区间为-100℃~425℃,热敏常数B变化幅度大(960K~4500K),不同温度下的电阻经过多次重复测试,误差±8%,适合制成高温型热敏电阻器和温度传感器。为了缓解SiC薄膜与蓝宝石衬底间的晶格失配及热膨胀系数的差异,在蓝宝石衬底与SiC薄膜中间尝试加入了一层Si-O-C中间过渡层,使得SiC薄膜衍射峰向小角度方向偏移的程度减缓了0.2~0.4°,薄膜能更稳定地生长,膜厚增加了0.1μm,薄膜热运输激活能与电阻温度特性变化趋势未变,含有过渡层的膜基结合力比不含过渡层的膜基结合力提高了1N。
[Abstract]:As the third generation wide band gap semiconductor material, SiC has a series of characteristics, such as high thermal conductivity, high velocity of saturated electron drift, wide band gap, high breakdown electric field, high thermal stability and so on. Nuclear power and high-power high-frequency device environment have broad application prospects. In this paper, the hexagonal crystalline SiC thin films were prepared by RF magnetron sputtering on 0001 direction single crystal sapphire sapphire (伪 -Al 2O 3) and 100 direction single crystal Si substrates. The effects of different process conditions on the phase structure, surface and cross-section morphology, resistance temperature characteristics of the films were studied. The comprehensive electrical properties of the thin film elements on different substrates were summarized. SiC thin films were grown on Si and Si / SiO _ 2O _ (200 nm) substrates by radio frequency magnetron sputtering (RF magnetron sputtering). By controlling the process parameters such as transition layer, deposition temperature, annealing and so on, the single crystal Si / SiO _ 2O _ 2O _ (200 nm) substrate is released to a certain extent due to the mismatch between the film and the substrate lattice at the deposition temperature of 750 鈩，

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