TiC/n型4H-SiC欧姆接触的低温退火研究

利用电子回旋共振(ECR)氢等离子体处理n型4H-SiC(0.5～1.5×1019cm-3)表面,采用溅射法制备碳化钛(TiC)电极,并在低温(<800℃)条件下退火。直线传输线模型(TLM)测试结果表明,TiC电极无需退火即可与SiC形成欧姆接触,采用ECR氢等离子体处理能明显降低比接触电阻,并在600℃退火时获得了最小的比接触电阻2.45×10-6Ω.cm2;当退火温度超过600℃时,欧姆接触性能开始退化,但是比接触电阻仍然低于未经氢等离子体处理的样品,说明ECR氢等离子体处理对防止高温欧姆接触性能劣化仍有明显的效果。利用X射线衍射(XRD)分析了不同退火温度下TiC/SiC界面的物相组成,揭示了电学特性与微观结构的关系。

Investigation of Low Temperature Annealing on TiC Ohmic Contact to n-type 4H-SiC

The surface of highly doped n-type(0.5～1.5×10~(19)cm~(-3)) 4H-SiC was treated by electronic cyclotron resonance(ECR) hydrogen plasma. TiC electrodes were fabricated by sputtering and low temperature(<800℃) annealing process. The results of TLM measurement indicated that TiC electrodes showed ohmic behavior without annealing and the treatment of ECR hydrogen plasma decreased the annealing temperature effectively. The lowest contact resistivity 2.45×10~(-6)Ω·cm~2 was obtained after annealing at 600℃. After annealing above 600℃ the property of ohmic contact started to degenerate, but the specific contact resistivity was still much lower than that of samples which weren't treated by hydrogen plasma. This phenomenon showed that ECR hydrogen plasma treatment had a significant effect on avoiding deterioration of ohmic contact under high temperature. To reveal the correlation between electrical properties and microstructures, XRD was used to determine the intermetallic compound formed at the TiC/4H-SiC interface at different annealing temperatures.