Darmstadt 2008 – wissenschaftliches Programm
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P: Fachverband Plasmaphysik
P II: Poster: Niedertemperaturplasmen, Plasmatechnologie
P II.24: Poster
Dienstag, 11. März 2008, 11:00–13:00, Poster C3
A New Dry Etch Chemistry in Deep Trench Silicon Plasma Etching For Sub-100nm Technologies — •Harald Richter1, Siegfried Günther1, Stephan Wege2, Sven Barth2, Ioan Costina1, Günter Weidner1, Steffen Marschmeyer1, and Heike Silz1 — 1IHP Frankfurt (Oder) — 2Qimonda Dresden
An esssential market share of today's DRAM production is covered by devices using a trench capacitor cell. The technology and productivity driven shrink of lateral dimensions at approximately constant capacity specifications lead to an increased deep trench (DT) aspect ratio (depth/width) requirement. For sub-100nm technologies and a given capacitance and cell size the requirement for DT etching results in aspect ratios of 60 to 80. In this paper, we describe DT process developments driven by the following motivation: To realise aspect ratio requirements a high selectivity to hard mask is needed. Therefore, process conditions which lead to minimized hard mask consumption during Si DT etching are necessary. A new DT plasma etch chemistry was introduced using CO2 as a successful alternative to the standard passivation component O2 in the common gas mixture HBr/NF3/O2. Investigations were focused on a non conventional hard mask material containing a TiN/Ti sandwich structure. In former investigations TiN/Ti works only as a stop layer for DT etch. Approx. 3.5 micron deep trenches over a 200nm TiN/Ti hard mask can be realized using HBr/NF3/CO2 processes. During Si etching a passivation layer is formed on the hard mask regions protecting TiN and ensures the requested high selectivity.