Reactive ion etching for microelectrical mechanical system fabrication

Abstract

The suitability of reactive ion etching for the fabrication of microelectro mechanical systems (MEMS) has been evaluated by characterizing the change of lateral dimensions versus depth in etching deep structures in silicon. Fluorine, chlorine, and bromine containing gases have provided the basis for this investigation. A conventional planar RIE (reactive ion etching) reactor has been used, in some cases with magnetic field enhancement or an inductive coupled plasma source and low substrate temperature. For RIE based on Cl2 or Cl2/HBr plasma a slightly ‘‘positive’’ (top wider than bottom) slope is achieved when etching structures with a depth of several 10 μm, whereas a ‘‘negative’’ slope is obtained when etching with an SF6 /CCl2F2-based plasma. A pattern transfer with vertical walls is obtained for RIE based on SF6 (with O2 added) when maintaining the substrate at low temperature (≊−70 °C). Further optimization of plasma chemistries and RIE procedures should result in runouts on the order of 0.1/100 μm depth in Si as well as in organic materials.

Integrated plasmon and dielectric waveguides

“…Dow Corning's HSQ resist [13] was spun onto the chip, baked at 170 C, and silicon waveguides were exposed at 100kV in a commercial electron beam lithography system at 3500 µC/cm 2 . After development, pattern transfer was performed using a chlorine ICP plasma [14]. For the metal layer, PMMA resist was again spun onto the surface of the chip, and 100 nm of silver was evaporated followed by a metal liftoff.…”

Meniscus-Mask Lithography for Fabrication of Narrow Nanowires

“…27 In the SF 6 /O 2 process, the SiO x F y film is sputtered from the bottom and redeposited on the sidewalls 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 8 resulting in directionality etching. 24,27,28 For the SF 6 /O 2 etching procedure we measured a wider wire width distribution than for other procedures, however, the average wire widths for all three etching methods are very close, indicating that the exact etching mechanism or chemistry involved do not significantly affect the result. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 4...…”

The fabrication of millimeter-wavelength accelerating structures

“…For example, using gas mixture of BCl 3 and Cl 2 , the relative ratio of etch rate on Al to etch rate on SiO 2 is 25 [18]. Using RIE to fabricate microelectrical mechanical systems has been reported for thickness up to few tens of microns [27]. Little work has been done on etching pure copper.…”