To acquire high performance p-type FET, suppressing Fermi level pinning is required. From XPS and Raman measurements, the actual origin of pinning of Au on WSe₂ was found to be the chemical bonding between WSe₂ and Au. To obtain ideal vdW contact, inserting thin Bi layer to separate the Au-Se bonding and subsequent removing Bi from interface by surface segregation were proposed. This strategy was demonstrated on WSe₂ FET with Bi/Au bilayer electrodes.