AVS 47th International Symposium
    MEMS Wednesday Sessions
       Session MM-WeA

Paper MM-WeA2
Application of Magnetic Neutral Loop Discharge Plasma in Deep Silica Etching

Wednesday, October 4, 2000, 2:20 pm, Room 309

Session: MEMS Processing
Presenter: W. Chen, ULVAC JAPAN, Ltd.
Authors: W. Chen, ULVAC JAPAN, Ltd.
K. Sugita, ULVAC JAPAN, Ltd.
T. Hayashi, ULVAC JAPAN, Ltd.
T. Uchida, ULVAC JAPAN, Ltd.
Correspondent: Click to Email
Generally, plasma density is well known to be concerned with etch rate, and electron temperature is a key parameter for the decomposition of reactive gases which is also relative to the operating pressure. So, margin of plasma production in process can be defined as the highest density, lowest applicable electron temperature and pressure, which indicate the variability of gas chemistry for processes. Process pressure is an especially important parameter for the Micro-Electro-Mechanical-Systems (MEMS). Metal mask and/or doped glass are usually used. These metal masks, such as Cr, Ni and WSi, and doped materials do not reactive to the dominant reactive species of CF@sub x@, which are consumed by physical sputtering mainly. Certainly, the sputtered clusters are easily re-deposited to sample substrate by collision of the sputtered metal cluster with neutral gases in high-pressure process, which may result in a rough surface and large taper angle. Magnetic neutral loop discharge (NLD) plasma@Footnote 1-3@ is a wide marginal one with a high density (>10@sup 11@ cm@sup -3@) and low electron temperature of about 2.5eV in a very low pressure of about 0.2Pa. Using NLD system, vertical trench structures for optical wave-guide were successfully fabricated on fused quartz glass and silica film with very smooth surface in the depth of 6-30mm. Meanwhile, the etch rate were kept greater than 500nm/min with good uniformity (deviation of @sigma@<1%) on 6 inch, wafer, where hard mask of Cr, Ni and WSi were used. @FootnoteText@@footnote 1@T. Uchida : Jpn. J. Appl. Phys., 33 (1994) L43. @footnote 2@W. Chen, M. Itoh, T. Hayashi, and T. Uchida, Jpn. J. Appl. Phys. 37, 332 (1998). @footnote 3@W. Chen, Y. Morikawa, M. Itoh, T. Hayashi, K. Sugita, H. Shindo and T. Uchida: J. Vac. Sci. Technol., A17(5) (1999) 2546.