The Study Of Plasma Stripping To Low K Material Damage

With scaling down of feature sizes of chips, the electrical resistance and parasitic capacitance have become a major factor that limits the performance of chips. It caused the semiconductor industry to move away from Aluminum interconnect metal with Silicon Dioxide to Copper with low-k dielectric materials. The copper and low-k multi-layer interconnection technology becomes the trend to interconnection of ICs.Copper Dual-damascene technology, low-k dielectric materials and plasma etching were introduced in this paper. And plasma stripping on low-k dielectric material issue was discussed in the paper. For the carbon doped low-k dielectric material, the Carbon bond will be damaged during plasma stripping for photo resistor. The K value will be increased or the critical dimension of profile will be changed.In this paper, the In-situ plasma stripping was studied using plasma etching equipment. The reason of low-k damage during In-situ plasma stripping was analyzed. And also the solution of reducing the plasma damage during In-situ plasma stripping was proposed in this paper. Oxygen was selected as the In-situ plasma stripping gas after gases resource optimization. The gas flux, chamber pressure and RF frequency were analyzed for the plasma damage to low-k dielectric material. After comparing with SEM picture with HF dip and without HF dip after plasma stripping, analyzing the process result, the Oxygen plasma damage to low-k dielectric material has been optimized to meet the specification of mass production. The memory effect of etch chamber to low-k dielectric material and the solution to eliminate the memory effect were also studied in this paper.