Multilayer hexamethyldisiloxane film as bottom antireflective coating for ArF lithography

Abstract

A new multilayer bottom antireflective coating (BARC) layer composed of hexamethyldisiloxane (HMDSO) film stack is demonstrated for ArF lithography. The required optical constant of each layer can be tuned by varying the gas flow rate ratio of oxygen to HMDSO in an electron cyclotron resonance plasma enhanced chemical vapor deposition process, and the deposition can be completed in one step without changing to other materials. The measured swing effect is shown significantly reduced by adding such a multilayer BARC on both Al/Si and silicon crystal substrates. The capability of applying the multilayer BARC to various highly reflective substrates is discussed. Additionally, the multilayer BARC is shown to be capable of providing larger thickness-controlled tolerances than a single-layer BARC.