AVS 53rd International Symposium
    Plasma Science and Technology Tuesday Sessions
       Session PS1+MS+NM-TuM

Paper PS1+MS+NM-TuM11
Chamber and Process Development of High Aspect Ratio Deep Trench Si Etch for DRAM Application below 60 nm

Tuesday, November 14, 2006, 11:20 am, Room 2009

Session: Plasma Patterning
Presenter: S. Wege, Qimonda, Dresden, Germany
Authors: S. Barth, Qimonda, Dresden, Germany
A. Henke, Qimonda, Dresden, Germany
A. Kersch, Qimonda, Munich, Germany
M. Reinicke, University of Technology, Germany
W. Sabisch, Qimonda, Munich, Germany
J. Sobe, Qimonda, Dresden, Germany
A. Steinbach, Qimonda, Dresden, Germany
S. Wege, Qimonda, Dresden, Germany
Correspondent: Click to Email
For Qimonda's DRAM Technology the deep trench etched into silicon is the base for the capacitor concept. The shrink of lateral dimensions at approximately constant capacity specifications leads to increased deep trench aspect ratio requirements. Therefore high selectivity to the etch mask and excellent uniformity is needed, especially for technologies below 60nm. In this paper we describe the development of a new DT plasma etch chamber and process to fulfill these requirements. Simulations (an equivalence circuit plasma model and surface reaction models) were combined with in-situ plasma measurement techniques (QMS, high resolution OES, IR absorption spectroscopy, SEERS and Langmuir probe sensor wafers) and technological experiments, to characterize hardware features and process conditions. To achieve high Si etch rate and selectivity, plasma density and electron energy distribution in the plasma bulk, and ion energy distribution on the wafer surface can be optimized through multi frequency cathode excitation. The selectivity is further enhanced by using advanced hard mask materials and combining of etching and deposition process regimes. Excellent uniformity has been achieved by new tool components, e.g., multi zone gas distribution and wafer temperature control. In addition, the etch process chamber includes new features for process control, in-situ wafer surface temperature and trench dept measurement. The equipment and process development was accomplished through close cooperation between Qimonda and the tool supplier.