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研究了铜化学机械抛光(CMP)过程中,不同压力和非离子型表面活性剂对片内非均匀性(WIWNU)的影响。通过改变抛光压力大小和非离子型表面活性剂浓度,得出WIWNU的变化规律。实验表明,在不同抛光压力下,铜去除速率有明显的变化。当抛光压力为0 psi(1 psi=6.89×103Pa)时,去除速率呈中间高边缘低。当压力为0.5 psi时,边缘处去除速率较高,且随着压力的增大,晶圆边缘处去除速率与晶圆中心处去除速率差将更明显,导致片内非一致性增大。通过添加非离子型表面活性剂,可以改善WIWNU。当压力为1.5 psi时,非离子型表面活性剂体积分数为5%,WIWNU可降低到3.01%,并且得到良好的平坦化结果。同时,非离子型表面活性剂对晶圆表面残留颗粒具有良好的去除作用。
The effects of different pressure and non-ionic surfactants on intra-wafer inhomogeneity (WIWNU) during copper chemical mechanical polishing (CMP) were investigated. By changing the polishing pressure and the concentration of non-ionic surfactant, the variation of WIWNU was obtained. Experiments show that under different polishing pressure, copper removal rate has obvious changes. When the polishing pressure was 0 psi (1 psi = 6.89 × 103 Pa), the removal rate was low at the middle high edge. At 0.5 psi pressure, the edge removal rate is higher, and as pressure increases, the difference between the wafer edge removal rate and the wafer center removal rate will be more pronounced, resulting in an increase in on-chip non-uniformity. WIWNU can be improved by adding non-ionic surfactants. When the pressure is 1.5 psi, the volume fraction of non-ionic surfactant is 5%, WIWNU can be reduced to 3.01%, and get good flattening result. At the same time, non-ionic surfactants on the wafer surface residual particles have a good removal effect.