Inline process characterization and control for robust BEOL reliability

Abstract

In advanced technology node, the complexity of process, materials selection and limitation of tools' capability, becomes very challenging with respect to meet tight reliability targets. In our fabrication of low-k based BEOL integration scheme, we have demonstrated that by proper inline process characterization, feedback and control at critical process modules, a robust Time Dependent Dielectric Breakdown (TDDB) and Electromigration (EM) performance can be achieved. In this paper, we proposed a working model with inline process parameters characterization, reliability performance evaluation, root causes identification and solutions, to establish a relationship between inline process parameters and BEOL TDDB, EM performance. Our data shows that, to pass TDDB E-model (field driven), Mx final critical dimension (FCD) must be within very tight control of less than FCD target + 0.5nm, and greater than FCD target − 2nm. On the other hand, to pass TDDB SQRT E-model, FCD target − 2nm FCD target − 2nm is needed. Through this working model, we are able to justify and identify the critical process modules and to determine the process window to achieve robust BEOL TDDB and EM performance.