I can only suppose that it is cited because it deals clearly with a topic (the adhesion of copper metallurgy to low permittivity insulators) of particular importance to the manufacture of near-future (ULSI and GSI) microelectronic devices. I am surprised at its particular interest since it is only one of a series of papers on copper adhesion to the Cyclotene surface, and is not even the last one in the series dealing with enhanced adhesion through surface modification.

  Does it describe a new discovery or new methodology that’s useful to others?

Yes and yes. We discovered not only how to permanently fix copper nanoclusters to the Cyclotene surface, we also demonstrated that this adhesion was not lost, even when held at 350° C for extended periods of time. Because copper does not wet the Cyclotene surface, it forms such nanoclusters during the initial deposition; subsequently deposited copper forms a smooth film by depositing over these nanoclusters, retaining them, instead of filling the spaces between them. Thus, an apparently smooth copper film contacts the Cyclotene substrate through copper nanoasperities on its underside; this is also true for other insulators not wet by copper. What this means, as we described in a subsequent publication, is that the macroscopic adhesion of a copper film is determined by the nanoscopic adhesion (inability to diffuse across the Cyclotene surface) of those initially deposited nanoclusters. This chemical identification of the reacting species was made possible, in large measure, by the superb spectrum of surface analytical instruments at our disposal, including those used in the cited article: X-ray photoelectron spectroscopy (XPS), photoacoustic Fourier transform infrared spectroscopy (which permits the determination of the IR spectra of opaque surfaces), and scratch testing (which quantifies the macroscopic adhesion strength of a deposited film, as well as the use of inductive substituent constants (a standard feature of the linear free energy relationships used in physical organic chemistry) and a reliable intuition of the chemistry involved.

  Could you summarize the significance of your paper in layman’s terms?

The paper indicates that one of the earliest topics learned in general chemistry courses, the reaction of copper with an amine (a nitrogen-containing material similar to ammonia) to form chemical complexes, may reliably be used to promote the desirable adhesion of copper films to insulators. Such copper-insulator structures are needed in near-future microelectronics manufacture, so as to take advantage of the higher speeds of compound semiconductors, such as gallium arsenide.

I have long been interested in the metal-insulator interface. I have published in this field for many years, and have arranged two international conferences covering insulator metallization. The present work, on the copper metallization of Dow Cyclotene, is a natural follow-up, dealing with the metallurgy chosen for near-future microelectronic devices, as well as one of the candidates for low permittivity insulators. I was fortunate to have obtained the cooperation of Nortel Networks, interested in using Cyclotene, and the Dow Chemical Corporation, its manufacturer. Their backing enabled me to obtain a Strategic Grant from Canada’s Natural Sciences and Engineering Research Council, a government funding agency, which supported this work.