Structural Properties of Nickel Metal-Induced Laterally Crystallized Silicon Films and Their Improvement Using Excimer Laser Annealing

Structural properties of nickel metal-induced laterally crystallized (Ni-MILC) silicon films are studied in detail mainly using transmission electron microscopy (TEM). Laterally grown crystalline grains can be as large as 17 µm, though the grains consist of small misorientated subgrains and, in addition, some subgrains are divided further into overlapping upper and lower subgrains. The excimer laser annealing (ELA) method definitely improves the Ni-MILC silicon film quality, enlarges the subgrains and removes the overlapping structure. As a result, fairly good polycrystalline silicon (polysilicon) thin film transistors (TFTs) are easily fabricated through a low-temperature process. It is difficult, however, to completely eliminate the subgrains by simply applying the ELA method to Ni-MILC silicon films.