Solid state reaction of Co,Ti with epitaxially-grown Si1−xGex film on Si(100) substrate

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Abstract
The solid state reaction of Co,Ti with an epitaxially grown Si1−xGex strained layer is investigated in this article. The reaction was performed in a rapid thermal annealing system. The resulting films were characterized by Rutherford backscattering, Auger electron spectroscopy, x‐ray photoelectron spectroscopy, x‐ray diffractometry, and scanning electron microscopy. The electrical resistivity and Hall effect were measured in the temperature range of 77–300 K. Rapid thermal annealing of Co/Si0.8Ge0.2 at 650 °C results in a Co(Si0.9Ge0.1) film with cubic crystalline structure. At higher temperature CoSi2 is formed with Ge segregation towards the surface. After a multi‐step annealing, a highly oriented CoSi2 layer can be grown. For TiN/Ti/SiGe, the ternary phase of Ti(Si1−yGey)2 is formed, with a smooth surface and with resistivity comparable to the lowest value exhibited by TiSi2. The Co/Ti/SiGe/Si reaction is studied for the first time, demonstrating that the uniformity of Co/SiGe reaction is improved by applying the Co/Ti bilayer. A TiN(O)/CoSi2(Ge)/Si multilayer structure is formed, and the CoSi2(Ge) layer exhibits a strongly textured structure. Low temperature measurement reveals that the CoSi2(Ge) layer has a re?istivity slightly higher than that of CoSi2.