Effect of Hydrogen Partial Pressure on in-Situ Steam Generation Oxide Layer

As device sizes are scaled down, it is very difficult to obtain the stable quality of gate oxide due to the lattice deformation and irregular oxide thickness in furnace type annealing system. In that reason, to eliminate the excessive heat budget and to improve oxide layer quality, In-Situ Steam Generation (ISSG) has been widely used in rapid thermal process (RTP) system. When the thermal heat is too low to break bond energy of oxygen molecular for O*(radical oxygen) , it is very difficult to grow the oxide layer in homogenous thickness and quality. So, to compensate this lack of O* for ISSG process, special reactant such as hydrogen gas is added. "H₂ + O₂ = H₂O + O* + O^2- + other species" is common chemical equation for ISSG process with H2 gas which helps to generate more radical oxygen.

 In this study, we improved the gate oxide reliability In ISSG process depending on the influence of H₂ partial pressure and process temperature. An increased H₂ partial pressure under the same temperature, it is found that an oxide growth rate has increased. In Si-O bonds strain analysis in the Si/SiO₂ interface layer, due to the repairs of structural defects (three major structural defects , such as Si dangling bonds, weak Si-Si, and strained Si-O bonds), compressive strain has been decreased and also gate induced drain leakage (GIDL)  was improved. Based on the index of strain induced residual overlay values on the wafer surface, we confirmed that it became less sensitive than before. That implies less possibility of misalignment in lithography which brings about device failures.