Atomic scale characterization of HfO2∕Al2O3 thin films grown on nitrided and oxidized Si substrates
Atomic scale characterization of HfO2∕Al2O3 thin films grown on nitrided and oxidized Si substrates
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DOI：
10.1063/1.1808245
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发表时间：
2004-11
影响因子：
3.2
通讯作者：
T. Nishimura;T. Okazawa;Y. Hoshino;Y. Kido;K. Iwamoto;K. Tominaga;T. Nabatame;T. Yasuda;A. Toriumi
中科院分区：
文献类型：
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作者：
T. Nishimura;T. Okazawa;Y. Hoshino;Y. Kido;K. Iwamoto;K. Tominaga;T. Nabatame;T. Yasuda;A. Toriumi
采用原子层化学气相沉积法在表面氮化或氧化的Si（001）衬底上生长了一层和三层HfO2(9A)∕Al2O3（3A）薄膜。采用原子力显微镜、光电子能谱和中能离子散射等方法对制备的薄膜进行了分析。对于在氮化硅衬底上生长的一层和三层薄膜，在600℃以上的温度下，HfO2和Al2O3层混合形成Hf铝酸盐。900℃后退火，混合Hf铝酸盐层部分分解为HfO2和Al2O3晶粒，Al2O3向表面偏析。在1000℃时发生完全分解，表面被Al2O3覆盖。在900°C时，表面是均匀的，几乎是平坦的，但在1000°C时，由于Hf铝酸盐层完全分解，表面变得相当粗糙。相反，对于堆叠在氧化硅衬底上的单层薄膜，包括铝酸铪在内的硅酸铪层是通过退火形成的。
One and three bilayers of HfO2(9A)∕Al2O3(3A) thin films were grown by atomic layer chemical-vapor deposition on Si(001) substrates whose surfaces were nitrided or oxidized. The films as-grown and postannealed in an ultrahigh vacuum were analyzed by atomic force microscopy, photoelectron spectroscopy, and medium energy ion scattering. For the one- and three-bilayer films grown on the nitrided Si substrates, the HfO2 and Al2O3 layers are mixed to form Hf aluminates at temperatures above 600°C. The mixed Hf aluminate layer is partly decomposed into HfO2 and Al2O3 grains and Al2O3 segregates to the surface by postannealing at 900°C. Complete decomposition takes place at 1000°C and the surface is covered with Al2O3. The surfaces are uniform and almost flat up to 900°C but are considerably roughened at 1000°C due to the complete decomposition of the Hf aluminate layer. In contrast, for one- bilayer films stacked on the oxidized Si substrates, Hf silicate layers, including Hf aluminate, are formed by annealing a...