Interfacial reactions of Pd/Si0.76Ge0.24 by pulsed KrF laser annealing

Abstract

The interfacial reactions of Pd/Si0.76Ge0.24 were studied by pulsed KrF laser annealing as a function of energy density and pulse number. At an energy density of 0.1–0.4 J/cm2, a continuous germanosilicide layer composed of a low-temperature phase, Pd2(Si1−xGex), and a high-temperature phase, Pd(Si1−xGex), was formed. In contrast to vacuum annealing, Ge segregation out of the germanosilicide layer and the strain relaxation of the residual Si0.76Ge0.24 film could be effectively suppressed by pulsed KrF laser annealing at 0.1 J/cm2. Multiple pulse annealing at 0.1 J/cm2 could further homogenize the Pd concentration of the germanosilicide layer and promote the growth of Pd(Si1−xGex). Concurrently, the smoothness of the germanosilicide layer was substantially improved in comparison with those grown by vacuum annealing at temperatures above 200 °C. The studies also revealed that for multiple pulse annealing at 0.1 J/cm2 with a low repetition rate, 1 Hz, the evolution of phase formation and Pd diffusion could be proceeded by each individual laser pulse.

Interfacial reactions of Co/Si0.76Ge0.24 and Co(Si0.76Ge0.24)/Si0.76Ge0.24 by pulsed KrF laser annealing

“…Similar results were observed in the Pd/Si 0.76 Ge 0.24 system. 28 Those results imply that during the interfacial reactions of metal-Si 1−x Ge x the strain relaxation of the residual Si 1−x Ge x film can be suppressed by inhibiting Ge segregation out of the germanosilicide via pulsed KrF laser annealing. In the present study, we concluded that multiple pulse annealing at 0.2 J/cm 2 is an effective method to produce a smooth Co(Si 0.76 Ge 0.24 ) 2 film without Ge segregation out of the germanosilicide and inducing strain relaxation in the residual Si 0.76 Ge 0.24 film.…”

“…Strain relaxation might be induced by the chemical inhomogeneities, e.g., Ge segregation, and defects present in the interface between the germanosilicide and the unreacted Si 1−x Ge x film. 7,17,[26][27][28] At 0.6 J/cm 2 three germanosilicide layers were still present, and some Ge further diffused to the Si substrate, indicating that the melting depth exceeded the total thickness of the asdeposited Co layer (∼25 nm) and the as-grown Si 0.76 Ge 0.24 film (∼150 nm). Meanwhile the inhomogeneous distribution of Co in the reacted region was significantly improved.…”

“…Multiple pulse annealing has been reported to effectively homogenize the Pd concentration in the germanosilicide without inducing Ge segregation to the underlying Si 0.76 Ge 0.24 film. 28 In the present study, therefore, multiple pulse annealing at 0.2 J/cm 2 was performed on some samples. The decision to choose 0.2 J/cm 2 as the energy density for multiple pulse annealing is based on the result that on one pulse annealing at 0.2 J/cm 2 no Ge segregation out of the germanosilicide film occurred.…”

“…31 For Ni and Pd on Si 1−x Ge x pulsed KrF laser annealing has been found to effectively prevent Ge segregation out of the germanosilicide, the formation of agglomeration structure, and the occurrence of strain relaxation. [26][27][28] Strain relaxation is possibly induced by the chemical inhomogeneities and defects present in the interface between the germanosilicide and the unreacted Si 1−x Ge x film. 7 In a salicide formation technique CoSi 2 has received much attention because it can significantly reduce the contact resistivity of Si devices and act as a solid diffusion source to form shallow junction.…”

GOALI: Systems Integration of Uncooled YBaCuO IR Detectors

“…Excimer lasers have been used to convert amorphous Si to Poly-Si for the fabrication of thin film transistors for flat panel displays [24], [25]. Additionally, excimer lasers have been used to anneal SiN x films [26], Pd/SiGe contacts [27], and n-GaAs contacts [28].…”