高浓度硼扩散硅片CMP工艺改进技术

Improvement of High Concentration Boron Diffusion of Silicon Wafers by Chemical Mechanical Polishing

"叉指式微加速度计"的研制,需要使用高浓度硼扩散硅片,而硅片经过高浓度硼扩散后,硅片双面生长了一层硼硅玻璃,采用原有CMP工艺很难将其去除,不能在高浓度硼扩散层上制作更好的"叉指式微加速度计"结构。针对上述问题,在CMP研磨抛光工艺中,通过改进双面粘片工艺,选择合适的研磨料和抛光料以及研磨盘和抛光盘,系统地考察了压力、转速、抛光垫、浆料、温度等因素对硅晶圆平坦化速率的影响,优化研磨抛光工艺流程及工艺参数,获得表面无划道、无麻坑、无桔皮的高浓度硼扩散硅片,表面粗糙度20A,达到"叉指式微加速度计"工艺用片指标。

High concentration boron diffusion of silicon wafers has been used for the fabrication of interdigital micro-accelerometer.However,the silicon wafers are usually covered with several layers of borosilicate glass after the diffusion.It is difficult to remove the layers of borosilicate glass by the conventional process of chemical mechanical polishing.In this paper,we describe a method of fabricating high concentration boron diffusion of silicon wafers by chemical mechanical polishing.The influence of the pressure,rotational speed,polishing pad,slurry and temperature on the surface structure has been systematically investigated and we optimize the parameters of the process.The surface height fluctuation of the silicon wafers fabricated by this method is about 20 and the quality of the silicon wafers is capable of performing well for interdigital micro-accelerometer.