Importance of heat-up ramp rate for palladium-silicide fully-silicided-gate structure formation
Silicidation process for fully-silicided (FUSI) Pd2Si gate formation has been investigated. Two types of heating equipment was used for siliciding palladium deposited on a poly-Si/SiO2/Si MOS structure. One is lamp heating in a sputtering chamber and another is hot-plate heating. The former provide slower heat-up ramp because of relatively large thermal capacity. In this case, metal-rich phase was formed in the first stage of silicidation and it changed to Pd2 Si phase by additional heating after completion of silicidation reaction. FUSI utilizes impurity pre-doping to poly-Si to modulate workfunction. Pre-doping to poly-Si sometimes resulted in needle structure formation on a top of silicided film and voids at the interface between silicide and SiO2. These defects were reduced by silicidation with hot plate heating. In addition, Pd2 Si phase was obtained at the early stage of silicidation. Palladium and silicon reacts even at temperatures lower than 250degC. Therefore, in the case of the lamp heating, silicidation during heating is not negligible. These results are explainable considering change of major diffusion species during silicidation
Transmission electron microscopy and X-ray diffraction investigation of phase formation and transition between Pd2Si and PdSi in Pd thin films on (111)Si
Abstract Phase formation and transition between Pd 2 Si and PdSi in Pd thin films on (111)Si has been investigated by X-ray diffraction and transmission electron microscopy. In as-deposited and 200 °C/1 h annealed Pd(30nm)/(lll)Si samples, epitaxial Pd 2 Si was found to coexist with the unreacted Pd layer. In samples annealed at 250–800 °C, epitaxial Pd 2 Si is the only suicide phase present. PdSi was found to form along with Pd 2 Si in samples annealed at 850 °C. Pd 2 Si was found to be the predominant phase along with PdSi in samples annealed at 900–1000 °C. Pd 2 Si and PdSi were found to be the stable phases at 300–800 and 850–875 °C, respectively. The phase transition between Pd 2 Si and PdSi is reversible. In samples annealed at 900 °C, epitaxial Pd 2 Si is initially the only suicide phase present; then polycrystalline PdSi becomes the dominant phase. After annealing for more than 240 s, polycrystalline Pd 2 Si predominates over PdSi. The peculiar Pd 2 Si to PdSi, then back to Pd 2 Si phase transition behavior is correlated with the formation of PdSi islands, which is thought to alter the order of the total energy of the system.
Studies on the composition, quality and processing of triticale. Part II. Mineral composition of grain and flour.
Mineral composition of grain and flour in 14 promising triticale strains from India are reported. The mean values for whole grain, i.e. Ca (0.47 mg/g), P (2.70 mg/g), K 4.60 mg/g, Na (352 micrograms/g), Zn (41.6 micrograms/g), Cu (7.0 micrograms/g), Fe (73.4 micrograms/g) and Mn (33.6 micrograms/g) were obtained as compared to those of flour, i.e. Ca (0.27 mg/g), P (0.97 mg/g), K (1.64 mg/g), Na (231 micrograms/g), Zn (26 micrograms/g), Cu (4.0 micrograms/g) and Mn (10.5 micrograms/g), respectively. These values were found to be considerably higher than those of wheat. Highly significant positive correlations of ash with sodium and zinc in whole grain were observed. In the case of triticale flour, highly significant positive correlations of ash with manganese, phosphorus and potassium were obtained.