AVS 46th International Symposium
    Plasma Science and Technology Division Friday Sessions
       Session PS-FrM

Paper PS-FrM6
200 mm SCALPEL@super TM@ Mask Dry Etch Development

Friday, October 29, 1999, 10:00 am, Room 609

Session: Emerging Plasma Applications
Presenter: G.R. Bogart, Lucent Technologies
Authors: G.R. Bogart, Lucent Technologies
A. Kornblit, Lucent Technologies
I. Johnston, Surface Technology Systems, UK
A.E. Novembre, Lucent Technologies
M.L. Peabody, Lucent Technologies
C.S. Knurek, Lucent Technologies
R.J. Kasica, Lucent Technologies
Correspondent: Click to Email
SCALPEL (SCattering using Angular Limitation Projection E-beam Lithography) is based on the variation in scattering angles between two electron transparent materials supported on a membrane mask.@footnote 1@ Plasma etching of the membrane structure offers many advantages over wet etching using KOH. We have used a Time Multiplexed Deep Etching (TMDE) technique (Bosch process)@footnote 2,3@ for generation of large area thin (<150 nm) membranes using silicon as a support. Critical to membrane generation are handling, uniform substrate temperature control, backside cooling pressure control, a need for high silicon removal rate, CD control and waste disposal. Results using a dry etch process to generate the silicon supported membrane are presented. We have demonstrated etch rates near 3 µm/min (0.1g Si/min) and etch mask (SiO@sub 2@) selectivity >200:1 with a side wall angle of 89°. Etch uniformity is <10% over 180 mm but dependent on pattern geometry and process conditions. Initial experiments with the modified commercial etcher showed the expected etch dependence on source power, gas flow rates, and loading. Silicon etch rates for small exposed areas (44 cm@super 2@) were 6 µm /min (0.06 g/min). Larger exposed areas (176 cm @super 2@) had lower etch rates of 3 µm/min but higher overall silicon removal (0.1 g/min). Source power as high as 2.5 kW has been used with high flow rates of SF@sub 6@ gas. Tooling changes to prevent breakage of the wafer during the etch process included modifications to the chuck and the wafer clamping mechanism. Other key issues involved in establishing an acceptable dry etch process such as etch stop materials will also be presented. Support by DARPA Contract #972-95-C-0013. @FootnoteText@ @footnote 1@ Harriott, L.R.; Liddle, J.A.: Future Fab International. 1(2), pp. 143-148, 1997. @footnote 2@ Ayon, A.A.; et.al.: J. Electrochem. Soc. 146(1), pp. 339-349, 1999. @footnote 3@ Laermer, F.; Schilp, A.: U.S. Patent # 5,501,893.