Plasma etch challenges for porous low k materials for 32nm and beyond

Abstract

The challenges facing back-end-of-line (BEOL) etch are becoming increasingly difficult as shrinking dimensions are compounded by new materials integration. As critical dimensions decrease, key dimension-related etch challenges include CD control, trench litho stack aspect ratios, RIE lag, and LER. The move to low k and ultra low k dielectrics requires the etch to consider the sensitivity of the films to compositional modification, polymer interactions with the pores, and diffusion effects possible with porous materials. As the minimum pitch reaches sub-100nm, new interactions of the materials with the critical dimensions need to be considered. The ability of low k materials to be patterned at the required aspect ratios without losing structural integrity will be the key challenge for future technologies' success. This paper will review the key etch challenges as a function of dimensions vs. materials and highlight where their interactions which will drive future work. ©The Electrochemical Society.