1070-4272/01/7411-1947$25.00C2001 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 74, No. 11, 2001, pp. 1947!1949. Translated from Zhurnal Prikladnoi Khimii, Vol. 74, No. 11,
2001, pp. 1884!1887.
Original Russian Text Copyright + 2001 by Anfinogenov, Sirotkina, Domina, Khlebnikov.
AND POLYMERIC MATERIALS
Photoetching of Copper Surface with Photosensitive
V. A. Anfinogenov, E. E. Sirotkina, N. G. Domina, and A. I. Khlebnikov
Polzunov State Engineering University, Barnaul, Russia
Institute of Petrochemistry, Siberian Division, Russian Academy of Sciences, Tomsk, Russia
Received November 14, 2000; in final form, August 2001
Abstract-Solid-phase photoetching of copper surface with photosensitive polyvinyl chloride compositions
was studied. The depth of the relief was determined as influenced by the nature of photosensitizers present
in the composition and by the exposure time of the photosensitive layer.
The main principles of photoetching were proposed
in 1967 . Preparation of a relief image consists of
three steps: (1) application of a polymeric film con-
taining photosensitive C3Hlg bonds on the metal sur-
face (2) activating irradiation through a phototem-
plate, and (3) dissolution of the polymeric film.
The advantages of this procedure over, e.g., the
photoresist process is smaller number of steps owing
to etching of the surface during its irradiation and
the absence of aggressive media.
The photoetching mechanism involves formation of
active products in the polymeric matrix during pho-
tolysis of polyhalogenated organic compounds and
reaction of these products with the metal surface .
The feasibility of etching is determined by the
ability of the metal to form stable halides upon ir-
The necessary conditions for all photosensitive sys-
tems are photolysis of the etching agent with a high
quantum yield, high thermal stability under these con-
ditions, and compatibility of the components.
Solid-phase photoetching of the copper surface
finished to the 14th grade was studied with the aim
of producing reflecting diffraction grating with the
line depth no less than 0.1 mm. Photosensitive com-
positions containing polyvinyl chloride resin and vari-
ous photosensitizing agents were developed. The
samples thermostated at 25+2oC were irradiated with
a DRSh-250 lamp through a quartz phototemplate.
The line depth on the copper surface was measured
with an MII-4 microinterferometer after removal of
the polymeric film and photoetching products.
Solid-phase etching strongly depends on the thick-
ness of the polymeric film. The thicker the film, the
faster the process but worse the resolution. Therefore,
we studied how the polyvinyl chloride concentration
in the casting solution C
affects the thickness of
photosensitive films l:
The films with the optimal thickness (8315 mm),
allowing formation of a sharp image without side
etching, were prepared at the polymer concentration
ranging from 0.07 to 0.09 g ml
Most of photosensitive polymers contain C3C,
C3O, C3N, and C3Hlg bonds whose energy does not
exceed 420 kJ mol
. Since the energy of UV
quanta is enough for homolytic rupture of these bonds,
photolysis of these polymers almost always involves
generation of radicals. Various organic and inorganic
halogen-containing compounds used as photosensitive
components are presented un Table 1. Inorganic addi-
tives have virtually no effect on the solid phase
photoetching, probably because of poor compatibility
with the polymeric matrix of the photosensitive layer.
Bromoform, tetrachloro-9-octylcarbazole (TCOC) ,
and phenothiazine with p-toluenesulfonyl chloride are
the most effective organic additives.
Etching of the inorganic surface depends also on
the nature of solvent used for photosensitive film cast-