A Si/W/Ti trilayer structure which consists of a top insulating Si film, a middle lateral growth suppressing W film, and a bottom Ti film is proposed to form the titanium silicide. With the properly chosen thicknesses, the W/Ti films on the oxide layer can be completely converted into the TixWyalloy after annealing. Since the TixWyalloy has a higher silicidation temperature than the pure Ti film, the titanium silicide cannot be formed on top of the oxide layer and the problem of lateral growth can be solved. The thickness ranges of the W/Ti films for the TiSi2 formation without the lateral growth has been determined experimentally. Within these ranges, the obtainable sheet resistance of TiSi2 is between 0.8 and 2.5 Ω/▭. Moreover, the optimal annealing process is a one-step anneal at 750°C for 30 min, which can be carried out in an N2 flowing open-tube furnace. The mechanism of TiSi2 formation using the trilayer structure has also been explored and verified by experimental data.