Contact Hole Resolution Enhancement by Post Exposure Amine Treatment(CONPEAT) Process

摘要

We can print the contact hole pattern beyond the optical resolution limit using resist flow process. But its application has not strong point for the layer having various kinds of contact hole size and duty ratio according to x-axis or y-axis. Nevertheless, for the mass production of sub-150nm design rule device with KrF lithography using resist flow process, moderate shrink bias of below 40nm is required because the CD uniformity gets worser as the shrink bias gets larger by the influence of the hotplate dependency. We developed novel technology of shrinking contact hole using chemically amplified resist. It is generally known that the chemically amplified resist have t-top profile or larger line width when it has too much post exposure delay time at high amine concentration. Using this phenomenon, we intentionally treated amine of hexamethyl disilazane between exposure step and post exposure bake step, so we got smaller contact hole. Pattern profile of contact holes obtained by CONPEAT(CONtact hole resolution enhancement by Post Exposure Amine Treatment) process was fine. The contact size was 190nm with normal process and it was shrunk to 150nm using CONPEAT process. In this paper, we report the novel contact hole shrinkage technology of CONPEAT process. Its process feasibility was studied considering pattern fidelity, shrink bias and CD uniformity. We also introduce the experimental results of super contact hole shrinkage process using both contact hole shrinkage technology of CONPEAT process and resist flow process simultaneously.