铝栅碱性CMP的析氢腐蚀

Hydrogen Evolution Corrosion of Al Gate CMP in an Alkaline Solution

采用碱性抛光液对铝栅进行化学机械抛光(CMP),在pH值大于8.3时会发生析氢反应,表面产生氢气泡,在铝栅表面留下大量蚀坑缺陷,降低平坦化效果,严重影响芯片器件性能的完整性和可靠性。对铝栅在碱性介质CMP条件下的析氢反应机理及控制理论进行了深入探究。通过接触角实验和静态腐蚀实验,并结合金相显微镜观察静态腐蚀后表面状态,发现抛光液中加入FA/O I非离子型表面活性剂可有效抑制碱性环境中铝栅CMP析氢腐蚀。通过实验得出,当碱性抛光液中FA/O I非离子型表面活性剂的体积分数为1.5%时,抛光液的表面张力最小,接触角最小,抑制析氢腐蚀效果最好。

The hydrogen evolution reaction happens during the aluminum gate chemical mechanical polishing（CMP）process when the pH value of the alkaline solution is above 8.3,and the hydrogen bubbles generate on the surface of the Al gate,leading to many corrosion pit defects and reducing the effect of the planarization.Thus the hydrogen evolution corrosion influences the integrality and reliability of the devices on the chip seriously.The reaction mechanism and control theory of the hydrogen evolution for the Al gate under the condition of alkaline medium CMP were studied.After the contact angle tests and static corrosion experiments,the surface state was observed by metallographic microscope.It is obtained that adding the FA/O I nonionic surfactant into the alkaline slurry can effectively restrain the hydrogen evolution corrosion.The experimental results show that when the volume fraction of the FA/O I nonionic surfactant is1.5%,the surface tension and contact angle of the alkaline slurry are the smallest,and the restraint effect of hydrogen evolution corrosion is the best.