The behavior of stress was studied in as-deposited and thermal cycled SiO2 films deposited by plasma tetraethylorthosilicate (TEOS) and ozone TEOS chemical vapor deposition (CVD) processes. It was found that the stress is large and compressive for thin films (-<1500 .~) for both types of oxides. At larger thicknesses, the stress becomes very small. During thermal cycling, the stress variation shows a hysteresis behavior. However, the type of hysteresis depends on the maximum temperature of cycling. This behavior of stress is explained based on the densification and structural changes in the oxide film which are shown up by the changes in the IR absorption spectra.

The variations of stress in SiO2 films, deposited by tetraethylorthosilicate (TEOS)‐based chemical vapor deposition (CVD) processes, during isochronal and isothermal cycling was studied. It was found that significant stresses are developed in these SiO2 films during thermal cycling. Further, the SiO2 films deposited by the O3‐normalbased thermal CVD (ThCVD) exhibit much larger variations in stress as compared to the films deposited by plasma‐enhanced CVD (PECVD). The maximum stress is developed at a temperature of about 400°C which has significant implications on the multilevel metallization technologies. The observed variations of stress are explained on the basis of the intrinsic stresses built up in these films.

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As the focus of integration technology inevitably shifts from the present very large scale integration (VLSI) to ultra large scale integration (ULSI) schemes, thus leading to continuous decrease in circuit dimensions, the limitations of present multilevel metallization technologies become increasingly important. Because of the appreciably higher speeds and more complex multi-functional layering involved in the newest ULSI circuits, the electrical resistance and capacitance of presently used interconnects and their electromigration and stress resistance stand as major limiting factors to signal processing throughput. In this paper, some recent results achieved by the present investigators in their studies of blanket and selective low-temperature metal-organic chemical vapor deposition (LTMOCVD) of copper for potential use in multilevel metallizations in ULSIC’s are presented. The films were produced at 300–400°C in atmospheres of pure H2 or Ar from the β-diketonate precursor bis(6, 6, 7,7, 8, 8, 8-heptafluoro-2, 2-dimethy1-3, 5-octanediono)copper(II), Cu(fod)2. The films were analyzed by x-ray diffraction (XRD), Rutherford Backscattering (RBS), Auger electron spectroscopy (AES), scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDXS), and four-point resistivity probe. The results of these studies showed that films deposited on metallic substrates were uniform, continuous, adherent, highly pure, and exhibited very low resistivity, as low as 1.8 μΩcm for films deposited in pure H2 atmosphere. Preliminary investigations of selective LTMOCVD of copper showed that selectivity is indeed possible, but is a function of a wide range of parameters that include reactor geometry, substrate type and temperature, working pressure, type of carrier gas, and precursor chemistry.

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