Through-Pitch CD Control with TiN metal hardmask etch Process in Logic BEOL Patterning

The large amounts of through-pitch critical dimension (CD) data are required for generating the optical proximity effect (OPE) curves, which are the most sensitive ones to lithography scanner illumination setting and the following patterning transfer plasma etch process in semiconductor manufacturing. Etching process of TiN metal hardmask (MHM) with ArF photo resist (PR) are applied for this experiment. The test reticle contains line/space patterns in a range of pitch between 114nm and 900nm, and the target CD is 52nm for the dense line. The results of this study demonstrate that iso-dense loading of AEI (after etching inspection) is tunable from +16.1nm to -2.5nm by etch process tuning knobs, such as pressure, bias RF voltage, CF4 and additional N2 gas, during MHM patterning.