Characteristics in SiC-CMP using MnO 2 slurry with Strong Oxidant under Different Atmospheric Conditions
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Characteristics in SiC-CMP using MnO2 slurry with Strong Oxidant under Different Atmospheric Conditions Syuhei Kurokawa1, Toshiro Doi1, Osamu Ohnishi2, Tsutomu Yamazaki1, Zhe Tan3, and Tao Yin3 1 Department of Mechanical Engineering, Faculty of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, JAPAN 2 Department of Mechanical Engineering, Faculty of Engineering, University of Miyazaki, 1-1, Gakuen Kibanadai-nishi, Miyazaki-shi, 889-2192, JAPAN 3 Department of Mechanical Engineering, Graduate School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, JAPAN
ABSTRACT Semiconductor technology is the key point of the information society. However, as technology developing, the traditional semiconductor material such as silicon (Si) could not meet the demand of the society. Therefore, the next generation semiconductor material silicon carbide (SiC) is widely concerned. Compared to Si, SiC has some superior physical and chemical properties. On the other hand, it is difficult to polish SiC wafers due to the chemical, mechanical, and thermal stability. To achieve high-efficient CMP processing of SiC substrates, oxygen gas was introduced which might increase removal rates. MnO2 slurry was selected instead of silica slurry and strong oxidant KMnO4 was used to improve SiC-CMP process as an additive. In this paper, the effect of oxidant was inspected first. Meanwhile, we carried out the CMP experiment with the new type CMP machine to control the processing atmospheres including types of gases and gas pressures. As conclusions, oxygen and high atmospheric pressure can increase the removal rate in MnO2 slurry. KMnO4 additive has a great effect on increase of the removal rate. One of additional interesting results is that there seems to be the optimum mixture ratio of N2 and O2 gases to achieve a higher removal rate of SiC wafer.
INTRODUCTION SiC (silicon carbide) has been recently applied in the semiconductor industry and optical components due to its high hardness, excellent thermal conductivity, good chemical stability, wide band-gap, high critical electron mobility and so on [1]. SiC is attracting extensive concern as a power semiconductor device material, therefore it has a great potential in the area of the next generation power controlling devices, LED lighting [2]. SiC exists in about 250 crystalline forms [3]. The polymorphism of SiC is characterized by a large family of similar crystalline structures called poly types. They are variations of the same chemical compound that are identical in two dimensions and differ in the third. Thus, they can be viewed as layers stacked in a certain sequence. Three kinds of crystalline forms of SiC, 3C-SiC, 6H-SiC and 4H-SiC are introduced. 4H-SiC has a greater band-gap and thermal conductivity which means a possibility of being used in some complex environment. In addition,
low power loss was realized in the SiC power device. In this research, 4H-SiC was used to make experiment. In the manufacturing process of SiC wafer, after SiC crys
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