Watanabe Heiji, Ohmi Hiromasa, Kakiuchi Hiroaki, Hosoi Takuji, Shimura Takayoshi, Yasutake Kiyoshi
Department of Material and Life Science, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
J Nanosci Nanotechnol. 2011 Apr;11(4):2802-8. doi: 10.1166/jnn.2011.3911.
We propose low-damage and high-efficiency treatment of 4H-SiC(0001) surfaces using atmospheric pressure (AP) hydrogen plasma. Hydrogen radicals generated by the AP plasma was found to effectively remove damaged layers on SiC wafers and improve surface morphology by isotropic etching. Localized high-density AP plasma generated with a cylindrical rotary electrode provides a high etching rate of 1.6 microm/min and yields smooth morphology by eliminating surface corrugation and scratches introduced by wafer slicing and lapping procedures. However, high-rate etching with localized plasma was found to cause an inhomogeneous etching profile depending on the plasma density and re-growth of the poly-Si layer at the downstream due to the decomposition of the vaporized SiH(x) products. On the other hand, for the purpose of achieving moderate etching and ideal cleaning of SiC surfaces, we demonstrated the application of a novel porous carbon electrode to form delocalized and uniform AP plasma over 4 inches in diameter. We obtained a reasonably moderate etching rate of 0.1 microm/min and succeeded in fabricating damage-free SiC surfaces.
我们提出使用大气压（AP）氢等离子体对4H-SiC(0001)表面进行低损伤且高效的处理。发现AP等离子体产生的氢自由基能有效去除SiC晶片上的损伤层，并通过各向同性蚀刻改善表面形貌。用圆柱形旋转电极产生的局部高密度AP等离子体提供了1.6微米/分钟的高蚀刻速率，并通过消除晶片切割和研磨过程中引入的表面波纹和划痕，产生光滑的形貌。然而，发现用局部等离子体进行高速蚀刻会导致蚀刻轮廓不均匀，这取决于等离子体密度，并且由于蒸发的SiH(x)产物的分解，在下游会使多晶硅层重新生长。另一方面，为了实现对SiC表面的适度蚀刻和理想清洁，我们展示了一种新型多孔碳电极的应用，以在直径超过4英寸的区域形成非局部化且均匀的AP等离子体。我们获得了0.1微米/分钟的合理适度蚀刻速率，并成功制造出无损伤的SiC表面。
