Electrical characterization of amorphous Al2O3 dielectric films on n-type 4H-SiC
Electrical characterization of amorphous Al2O3 dielectric films on n-type 4H-SiC
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DOI：
10.1063/1.5021411
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发表时间：
2018-02-01
期刊：
影响因子：
1.6
通讯作者：
Sveinbjornsson, E. O.
中科院分区：
文献类型：
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作者：
Khosa, R. Y.;Thorsteinsson, E. B.;Sveinbjornsson, E. O.
我们报告了在低温（200 摄氏度 - 300 摄氏度）下通过连续热氧化薄 Al 层在 4H-SiC 上生长的 Al2O3 薄膜的电性能。与通过原子层沉积 (ALD) 或快速热处理 (RTP) 生长的 Al2O3 薄膜相比，使用这些薄膜制成的 MOS 电容器具有较低密度的界面陷阱，更不易受到电子注入的影响，并且表现出更高的击穿电场 (5MV/cm)。此外，界面态密度明显低于使用在 N2O 中生长的氮化热二氧化硅作为栅极电介质的 MOS 电容器。在 Al2O3 层顶部沉积额外的 SiO2 薄膜可提高 MOS 电容器的击穿电压，同时保持低密度的界面陷阱。我们研究了在 SiC 上生长的 Al2O3 薄膜中经常遇到的负电荷的来源，发现这些电荷由捕获的电子组成，这些电子可以通过耗尽偏压和紫外光照射从 Al2O3 层中释放出来。如果要将 Al2O3 用作 SiC MOS 技术中的栅极电介质，则需要减少这种电子俘获。 (c) 2018 年作者。
We report on the electrical properties of Al2O3 films grown on 4H-SiC by successive thermal oxidation of thin Al layers at low temperatures (200 degrees C - 300 degrees C). MOS capacitors made using these films contain lower density of interface traps, are more immune to electron injection and exhibit higher breakdown field (5MV/cm) than Al2O3 films grown by atomic layer deposition (ALD) or rapid thermal processing (RTP). Furthermore, the interface state density is significantly lower than in MOS capacitors with nitrided thermal silicon dioxide, grown in N2O, serving as the gate dielectric. Deposition of an additional SiO2 film on the top of the Al2O3 layer increases the breakdown voltage of the MOS capacitors while maintaining low density of interface traps. We examine the origin of negative charges frequently encountered in Al2O3 films grown on SiC and find that these charges consist of trapped electrons which can be released from the Al2O3 layer by depletion bias stress and ultraviolet light exposure. This electron trapping needs to be reduced if Al2O3 is to be used as a gate dielectric in SiC MOS technology. (c) 2018 Author(s).