GaN单晶片的表面加工工艺研究

Study on Surface Technical Processing of GaN Single Crystal Wafer

对硬脆材料氮化镓(GaN)单晶的机械研磨和化学机械抛光(CMP)加工工艺进行了研究。在机械研磨工艺中,研究了不同材料的研磨盘和不同粒径的磨料对GaN研磨时间的影响。实验结果表明,采用树脂铜盘和树脂锡盘将机械研磨时间缩短至1.5h,加工后的晶片表面最大划痕深度约为2.743nm,表面粗糙度为0.924nm。在GaNCMP单因素实验中,分析了工艺参数(如pH值、压力、转速)对GaN单晶片Ga面抛光速率的影响。实验结果表明,Ga面在酸性条件下的抛光速率较高,Ga面抛光速率随着压力和转速的增大而增加。确定了GaN单晶片表面加工的最佳工艺参数,当抛光液pH值为3,抛光压力为6×10^4Pa,抛光盘转速为100r/min时,Ga面抛光速率达到240nm/h,表面粗糙度可达到0.0719nm。

The mechanical lapping and chemical mechanical polishing (CMP)processing technolo- gies on hard brittle material GaN crystals were investigated.In the process of mechanical lapping,the effects of lapping plates with different materials and abrasives with different particle sizes were studied. The experimental results show that the lapping time is shortened to 1.5h by using the resin copper plate and tin plate.The maximum depth of the scratches on the surface of the wafer is about 2.743nm and the surface roughness is 0.924nm.During the GaN CMP single factor experiment,the influences of process parameters (such as pH value,pressure and rotating speed)on the polishing rate of Ga surface of GaN wafer were analyzed.The results indicate that the polishing rate of Ga surface is higher in the acid envi- ronment and it increases with the increase of pressure and rotating speed.The optimum processing para- meters of GaN wafers were determined.The polishing rate of Ga surface is 240nm/h and the surface roughness is 0.0719nm,when the pH value of the polishing solution is 3,the polishing pressure is 6×10^4Pa and the polishing plate rotation speed is 100r/min,respectively.