<title>0.35-um i-line poly processing with a bottom antireflective coating (BARC)</title>

Abstract

The manufacturing of high performance integrated circuits requires tight control of critical dimensions (CD) at poly pattern. Achieving these CD requirements forces process engineers to eliminate linewidth variation caused by reflective notching and thin film effects. Implementation of a bottom antireflective coating (BARC) can reduce or eliminate linewidth variations caused by reflective notching and thin film effects. With the additional process complexity, a number of issues must be resolved to obtain the true benefits of using a BARC material. The following paper discusses the characterization of a commercially available BARC material for 0.35 micrometers i-line poly patterning. Initial characterization of gratings and isolated lines on flat poly test wafers shows the resist process with BARC to have equal and in some cases better process capability compared to a conventional resist process. An 800 angstrom BARC film thickness on flat silicon wafers reduces the amplitude of the resist swing curve by 75%. On topography wafers an 800 angstrom BARC thickness eliminates reflective notching although for some small feature sizes, thin film effects still cause linewidth nonuniformity. Evaluations of BARC thicknesses ranging from 800 angstrom to 2,400 angstrom demonstrate the capability of the BARC to eliminate the swing effect in the resist by optimization of the BARC thickness. Cross sections of the resist profiles before and after etch demonstrate the ability for a repeatable pattern transfer. Wafer-to-wafer data and lot- to-lot data show the successful development of an etch process with a 0.03 micrometers bias. The data presented demonstrates the implementation of an optimized BARC process enhances the CD control capability at poly patterning for 0.35 micrometers i-line processing.