Semiconductor device preparation method

The invention relates to a semiconductor device preparation method, which comprises the steps of providing a semiconductor substrate comprising a primitive cell region and a non-primitive cell region,and sequentially forming an isolation dielectric layer and a semiconductor layer with first conductivity type doping on the semiconductor substrate of the non-primitive cell region; performing firstconductive type well injection by taking the semiconductor layer and the isolation dielectric layer as masks, and forming a well region in the primitive cell region; forming a working structure in thewell region, and forming a protection structure in the semiconductor layer; and forming an interlayer dielectric layer on the working structure and the protection structure, forming a contact hole inthe interlayer dielectric layer, forming a metal interconnection layer connected with the contact hole on the interlayer dielectric layer, and connecting the working structure and the protection structure through the metal inte