Preparation method of field effect transistor

The invention provides a preparation method of a field effect transistor, comprising the following steps of: supplying a first molded body substrate, forming a shallow groove by utilizing a photoetching and etching method, and growing to form a silicon dioxide shallow groove isolation structure in the shallow groove; depositing on the first molded body substrate and the silicon dioxide shallow groove isolation structure to form a high-K gate dielectric layer and a metal gate electrode layer; forming a grid electrode structure by utilizing a photoetching or corrosion process and the like; implanting second molded body foreign ions to form a source drain extension area; depositing an insulating layer to form a side wall attached to the edge of a grid electrode; implanting the second molded body foreign ions to form a source drain area of a second molded body field effect transistor and a PN (Performance Number) junction interface positioned between the source drain area and a silicon substrate; and carrying out microwave annealing to activate the implanted ions. The novel process of the field effect transistor can activate the impurities in the source drain area at lower temperature and reduce the influence of source drain annealing on a high-K gate dielectric/metal gate electrode.