This step is most important from the viewpoint of transistor characteristics.
A gate oxide film greatly influences the performance and reliability of a transistor, and should therefore be a high-density thin film uniformly distributed over the wafer surface.
Since the size of the gate formed may also greatly influence the performance of the transistor, strict dimensional control is necessary in both photo resist patterning and gate etching.
Gate electrodes are formed of polysilicon (polycrystalline silicon) by CVD