双层铝互连倒梯形通孔刻蚀技术研究

Study on Etching of Inverse Trapezoid Via for Double Aluminum Interconnects

针对双层布线中二铝在通孔处台阶覆盖率低的问题,通过优化光刻胶膜的厚度、硬烘温度,以及调整刻蚀气体流量、腔室压力及极板功率,开发出坡度为62.5°的倒梯形通孔;二铝在通孔处的台阶覆盖率大于90%。将该技术用于D/A转换器的研制,成品率得到明显提高。

In order to improve the low step coverage of the second Al metallization on the via,thickness and bake temperature of the photo-resist were optimized,and flux of etch gases,chamber pressure and RF power were adjusted to develop inverse trapezoid via with 62.5° gradient.Using this optimized process,step coverage of the second Al metallization on the via was more than 90%.The proposed process was used to fabricate D/A converters,and the yield was improved remarkably.