Patterning issues for the fabrication of sub-micron memory capacitors' electrodes
This paper describes some of the key issues associated with the patterning of metal electrodes of sub-micron (especially at the critical dimension (CD) of 0.15 μm) dynamic random access memory devices. Due to reactive ion etching lag, the Pt etch rate decreased drastically below the CD of 0.20 μm and thus K-th storage node electrode with the CD of 0.15 μm could not be fabricated using the Pt electrodes. Accordingly, we have proposed novel techniques to surmountly-the above difficulties. The Ru electrode cannot for the stack-type structure is introduced and alternative multischemes based on the introduction of the concave-type selfstructure upto using semi-Pt or Ru as an electrode material are outlined respectively.
Study of Ru etching using O2/Cl2 helicon plasmas
Abstract We have investigated the characteristics of ruthenium (Ru) etching using O 2 /Cl 2 helicon plasmas, resulting in the high Ru etch profile (>85°) and the optimal etch rate (>500 A min −1 ). We revealed that the chamber pressure greatly affects the Ru etch rate and Ru to mask etch selectivity. The dependence of Re etch rate on pressure was scrutinized for both patterned and non-patterned wafers.
Ultrathin Ta2 O 5 Film Capacitor with Ru Bottom Electrode
The characteristics of the ultrathin Ta 2 O 5 film capacitors with Ru bottom electrodes have been investigated. Ru films are deposited on n-Si by sputtering in 10% O 2 /Ar ambient, for the bottom electrode, and Ta 2 O 5 films are deposited by chemical vapor deposition using Ta(OC 2 H 5 ) 5 and O 2 . By O 2 plasma treatment at 400°C after N 2 thermal treatment at 700°C, excellent properties, are obtained such that the effective SiO 2 film thickness is 0.68 nm for 6 nm thick Ta 2 O 5 film and the leakage current is less than 1 × 10 8 A/cm 2 between the range of -2.1 and +1.8 V. The Ta 2 O 5 film with a Ru bottom electrode is one of the most suitable structures for Gbit dynamic random access memory capacitors.