Bell Telephone Laboratories

At&t Bell Laboratories

Richard G Vadimsky

Adam Heller

King Lien Tai

Barry Irwin Miller

Costas H Tzinis

The invention involves a new sensitizing bath for chalcogenide glass-based resists. The inventive bath is alkaline and contains a silver complex whose ligand includes hydrophobic and hydrophilic moieties. Upon immersing a chalcogenide glass in the bath, a silver composition-containing film is formed on the surface of the glass. This film is substantially free of pin holes and has a uniform thickness which is insensitive to immersion time and largely determined by the pH of the bath.

Sensitizing bath for chalcogenide resists

Fabrication of a resist, useful for high resolution pattern delineation and having a silver containing layer on a glassy material, produces better results when the sensitizing bath contains both potassium silver cyanide and a metal cyanide complex capable of providing CN.sup.- ions to shift the equilibrium of Ag(CN).sub.2.sup.- .revreaction.AgCN+CN.sup.- to the left.

Sensitizing bath for silver containing resist

Lithographic patterning of particular interest in fabrication of integrated circuitry is based on the photoinduced migration of silver into germanium selenide or other glassy material of appropriate absorption cross section for the chosen actinic radiation. Resists which are negative-acting yield high resolution attributed to initial introduction of the silver in chemically combined form chosen so as to result in formation of a silver compound with a glass component with the compound serving as silver source. Removal of excess silver-containing material is engineered on the basis of the form of silver introduction and results in conversion to a water soluble form. Commercial use will likely be based on an embodiment in which the now developed patterned resist serves as a dry etching mask during delineation of a relatively thick underlying layer of organic material. This procedure is particularly advantageous for use on partially processed circuitry in which prior operations have resulted in surface steps.

Photoinduced migration of silver into chalcogenide layer

The ruthenium compound [Ru.sub.2 N(H.sub.2 O).sub.2 Cl.sub.8 ]K.sub.3 is prepared by refluxing a mixture of hydrated water soluble ruthenium chloride, having approximately 40% ruthenium content, and sulphamic acid, the latter having approximately half the molar concentration of the former, for several hours and then precipitating the desired compound by adding solutions of potassium chloride and hydrochloric acid. Electrical contacts on the reeds of sealed reed switches produced by electroplating from an aqueous solution of the salt produced in this manner are found to be particularly resistant to the thermal shock involved in the sealing of the switches.

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Somerville, NJ, United States of America

Richard G Vadimsky