The as-deposited stress in sputtered, 75-Å-period Mo/Si multilayers was measured to be approximately −350 MPa (compressive), and relaxed to approximately −150 MPa after thermal cycling to 200 °C. The multilayer period was found to decrease by 0.25 Å as a result of thermal cycling, with only a slight decrease in peak soft-x-ray reflectance. The stress-temperature behavior of individual Mo and Si films was also measured, and correlated with the multilayer behavior: stress relaxation in the multilayer is attributed to viscous flow associated with defect annihilation, occurring predominantly in the amorphous Si layers.

We have investigated the effect of nickel and copper on defect formation in silicon employing the rapid thermal processing (RTP) scheme. Treatment by RTP induces haze in the silicon wafer front side when its back side is contaminated by either nickel or copper. Transmission electron microscopy studies showed that the haze consisted of metal silicide precipitates, which negates a previous suggestion that ‘‘oxidation-induced stacking faults’’ are the main defect forming the haze. The morphology and nature of these precipitates have been analyzed. The nickel silicide precipitates were found to be NiSi2 and the copper silicide precipitates are most likely CuSi (zinc blende structure). Both kinds of precipitates exhibited an epitaxial relationship with the silicon substrate and adopted the shape of an inverted pyramid or section of a pyramid. The present CuSi precipitate morphology differs totally from that obtained using furnace annealing, and is attributed to the availability of free-silicon surface as the main silicon self-interstitial sink. Implications for low-temperature ultralarge scale integration processing are discussed.

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