纳米SiO_2浆料中半导体硅片的化学机械抛光速率及抛光机理

CHEMICAL MECHANICAL POLISHING REMOVAL RATE AND MECHANISM OF SEMICONDUCTOR SILICON WITH NANO-SiO_2 SLURRIES

采用电化学方法,研究了SiO2浆料pH值、H2O2浓度、固体含量以及抛光转速、压力和时间等不同抛光工艺参数对n型半导体单晶硅片(100)和(111)晶面化学机械抛光(chemical mechanical polishing,CMP)去除速率的影响和作用机理。结果表明:抛光速率随SiO2固体含量、抛光转速及压力的增加而增大,随抛光时间的增加而减小;在pH值为10.5和H2O2为1%(体积分数)时,抛光速率出现最大值;相同抛光工艺条件下(100)晶面的抛光速率远大于(111)晶面。半导体硅片CMP过程是按照成膜(化学腐蚀作用)→去膜(机械磨削作用)→再成膜→再去膜的方式进行,直到最终全局平坦化。实验所获得适合n型半导体硅片CMP的优化工艺参数为:5%～10%SiO2(质量分数),pH=10.5,1%H2O2,压力为40kPa及(110)晶面和(111)晶面的抛光转速分别为100r/min和200r/min;在该条件下10%SiO2浆料中抛光30min得到的抛光硅片的表面粗糙度为0.7nm左右。

The effects of different process parameters including the pH value, H2O2 concentration, SiO2 solid content of slurry, polishing pressure, polishing rotation speed and polishing time on the chemical mechanical polishing （CMP） removal rate of n-type Si （100） and Si （111） were studied using the electrochemical method and using nano-SiO2 shtrry as the polishing material. The results show that the polishing removal rate increases with the increase of SiO2 solid content in slurry, polishing pressure and rotation speed, and decreases with the increase of polishing time. The highest values of the polishing removal rates of the n-type Si （100） and Si （111） samples were observed at a pH value of 10.5 and 1% （in volume） H2O2. The polishing rate of the n-type Si （100） sample was much faster than that of the n-type Si （111） sample. The polishing process of CMP was the continuous cycles of passivation film formation→removal→reformation film→removal. The optimal technology parameters suitable for the CMP used in the polishing of n-type semiconductor silicon wafers are as follows： 5%-10% SiO2 （in mass）, pH=1 0.5, 1% H2O2, polishing pressure of 40 kPa, and polishing rotating speeds of 100 and 200 r/min for the （100） plane and （111） plane wafers, respectively. The surface roughness of the （100） plane and （111 ） plane silicon wafers polished by shtrry with 10% SiO2 under the above conditions for 30 min is about 0.7 rim.