At&t Bell Laboratories

Bell Telephone Laboratories

Hans J Stocker

Legrand G Van Uitert

Nur Selamoglu

Craig N Bredbenner

Hans J Lewerenz

Troy A Giniecki

A method for etching metal layers including aluminum to create tapered sidewalls is disclosed. The method features the use of trifluoromethane and chlorine in controlled amounts to create a tapered metal layer profile.

Method for tapered etching

Patterning of a relatively thick silicon nitride layer coating a relatively thin silicon dioxide layer which coats a major surface of a silicon wafer is accomplished by reactive ion etching, without penetrating through the silicon dioxide layer to the major surface of the silicon wafer, by means of a two-step reactive ion etching procedure using a patterned masking layer. During the first etching step the silicon nitride layer is not completely penetrated; during the second step the nitride layer but not the silicon dioxide layer is completely penetrated. The gas mixture for the first etching step differs from that of the second etching step in accordance with prescription that the ratio of the etch rate of silicon dioxide to that of silicon nitride during the second step is significantly smaller than such ratio during the first step. Preferred gas mixtures are oxygen and CHF.sub.3 in the ratio of about 0.6 to 1.0 for the first etching step and about 9 to 1 for the second etching step. Other systems of layers and wafers can be similarly patterned by means of two-step etching processes using selections of the gas mixtures in accordance with this prescription for the ratios of etch rates.

Two-step anisotropic etching process for patterning a layer without

The reverse leakage current of InGaAs diodes, in particular the dark current of In.sub.0.53 Ga.sub.0.47 As photodiodes, is reduced by a treatment in a 1:1:X solution of H.sub.2 O.sub.2 :H.sub.2 SO.sub.4 :H.sub.2 O where 10.ltoreq..times..ltoreq.100 approximately.

Reduction of leakage current in InGaAs diodes

Devices of the nature of magnetic bubble devices, but in which 'bits' take the form of light spots, are described. A prototypical device takes the form of an electroluminescent, photoconducting film straddled by orthogonal arrays of insulated strip electrodes forming closely spaced intercept positions so arranged that during operation such intercepts are sequentially biased. A light spot once nucleated--e.g., through a combination of electroinduced and photoinduced luminescence, is stepped by applying bias below nucleation threshold. Devices may serve a variety of memory and/or logic functions.

Growing community of inventors

Summit, NJ, United States of America

Hans J Stocker