Process optimization of polysilicon removal by wet etching with alkaline chemicals in a gate-last device integration scheme was investigated. Initial surface condition of the polysilicon layer, spreading properties of wet etching chemicals, and generation of hydrogen bubbles during wet etching were revealed as key parameters affecting the degree of polysilicon residue after wet etching both in patterned structures and on non-patterned bare wafers. Wet etching starting from a hydrophilic polysilicon surface showed successful polysilicon removal (no residues) compared with a hydrophobic polysilicon surface, indicating that the spreading and wetting properties of the wet etching chemical on polysilicon surface is very important in the polysilicon wet etching process. Therefore, it is believed that chemicals showing lower contact angles on the polysilicon surface may be suitable to enhance process efficiency. Furthermore, hydrogen gas generated during silicon wet etching can hinder polysilicon removal, causing significant residues after processing. Ultrasonication or addition of IPA in the wet etching solution can be an alternative method for preventing the hydrogen bubble effect.