Electro-chemical mechanical polishing of silicon carbide
Electro-chemical mechanical polishing of silicon carbide
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DOI：
10.4028/www.scientific.net/msf.457-460.801
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发表时间：
2004-05
影响因子：
2.1
通讯作者：
Canhua Li;I. Bhat;Rongjun Wang;J. Seiler
中科院分区：
文献类型：
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作者：
Canhua Li;I. Bhat;Rongjun Wang;J. Seiler
为了改善碳化硅衬底表面，开发了一种新的电化学机械抛光(ECMP)技术。本工作主要研究了硅端4H-SiC(0001)衬底向<1120>偏轴方向切割8°。以过氧化氢(H_2O_2)和硝酸钾(KNO_3)为电解液，以硅胶浆为抛光介质去除氧化物。抛光过程中的电流密度从10微A/cm2到20 mA/cm2以上。即使使用高电流密度可以获得高抛光速率，也需要适当地平衡氧化速率和氧化物去除速率，以获得抛光后的光滑表面。开发了一种两步ECMP工艺，它允许我们分别控制阳极氧化和生成氧化物的去除。适当控制阳极氧化电流和抛光速度可获得最佳表面。当电流密度为1 mA/cm2时，当电流密度为1 mA/cm2时，表面较为光滑。用高分辨原子力显微镜(AFM)研究了原始片、0.1µm金刚石抛光液和EMCP抛光片的表面形貌。
In an effort to improve the silicon carbide (SiC) substrate surface, a new electro-chemical mechanical polishing (ECMP) technique was developed. This work focused on the Si-terminated 4H-SiC (0001) substrates cut 8° off-axis toward 〈1120〉. Hydrogen peroxide (H2O2) and potassium nitrate (KNO3) were used as the electrolytes while using colloidal silica slurry as the polishing medium for removal of the oxide. The current density during the polishing was varied from 10 µA/cm2 to over 20 mA/cm2. Even though a high polishing rate can be achieved using high current density, the oxidation rate and the oxide removal rate need to be properly balanced to get a smooth surface after polishing. A two-step ECMP process was developed, which allows us to separately control the anodic oxidation and removal of formed oxide. The optimum surface can be achieved by properly controlling the anodic oxidation current as well as the polishing rate. At higher current flow (>20 mA/cm2), the final surface was rough, whereas a smoother surface was obtained when the current density was in the vicinity of 1 mA/cm2. The surface morphology of the as-received wafer, fine diamond slurry (0.1 µm) polished wafer, and EMCP polished wafer were studied by high-resolution atomic force microscopy (AFM).