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Rotational Chemical Etching Disclosure Number: IPCOM000102434D
Original Publication Date: 1990-Nov-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 3 page(s) / 102K

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Berk, D: AUTHOR [+1]


A method is described for chemical etching of metals which produces straight wall profiles of the metal film.

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This is the abbreviated version, containing approximately 52% of the total text.

Rotational Chemical Etching

       A method is described for chemical etching of metals
which produces straight wall profiles of the metal film.

      Conventional methods of chemical etching of metals include dip
etching, bubble etching and spray etching. These methods involve both
mass transfer and a chemical reaction, which lead to reduced etch
rates and isotropic etch profiles, as shown in Fig. 1.

      As circuit densities of ceramic and printed circuit board
products increases a better dimensional uniformity of the circuit
elements is required and thus a method of producing straight wall
profiles after etching, as shown in Fig. 2, is highly desirable.

      To achieve a low convexity in the etched wall, dry etching
methods, such as plasma etching, sputter etching and reactive ion
etching, have been employed in the past. However, these methods may
not always be practical as they run in batch modes, are very
expensive to operate and are not compatible with all types of
etchable materials.  Wet etching, however, can be run in a continuous
mode of operation, is less expensive to operate and has a wider
applicability in the electronics industry and, more recently, in the
opto-electronics industry.

      Rotational etching uses the approach of controlling the
hydrodynamics of the etchant at the metal surface in a way as to
significantly reduce diffusional effects that contribute to isotropic
etching.  The etching reaction comes under kinetic control rather
than diffusional control, thus resulting not only in anisotropic
etching but also increased rates of etching over conventional wet
etching methods.

      In one embodiment of the direct rotational etching method, a
substrate is mounted in a holder and the holder itself is rotated at
a predetermined rotational speed in the etchant solution in order to
attain anisotropic etching. This method is restricted to smaller
sample sizes being etched in...