Sub-quarter-micron Pt etching technology using electron beam resist with round-head

Pt patterns of 0.16, 0.25 and 0.36 mu m size and without a sidewall-fence w ere formed using dipole ring magnetron reactive ion etcher (DRM-RIE) with r ound-head resist masks of 0.1, 0.2 and 0.28 mu m size written by an electro n beam. Critical dimension (CD) gains ranged from 50 to 60 nm, and taper an gles ranged from 72 to 75 degrees. To realize sidewall-fence-free Pt etchin g with a small CD gain and large taper angle, it is important to tune resis t selectivity to an optimum. Taper angle becomes small and CD gain becomes large in the case of low resist selectivity: on the other hand, sidewall-fe nce is formed in the case of high resist selectivity. Eventually, under the condition of optimum resist selectivity, no sidewall-fence is formed and t aper angle and CD gain become large and small, respectively. The optimum re sist selectivity has been realized under the conditions of low pressure, hi gh Cl-2 flow rate, and high RF power.