Method for producing thin MEMS chips on SOI substrate and micromechanical component

A method for producing thin a Micro-Electro-Mechanical System (MEMS) chip on a Silicon-on-Insulator (SOI) substrate, the method comprising:

• (A) providing an SOI substrate having a silicon layer on a front side and having an oxide intermediate layer;
• (B) producing a layer structure on the front side of the SOI substrate and producing a MEMS structure from this layer structure;
• (C) capping the MEMS structure and producing a cavity;
• and
• (D) etching a back side of the SOI substrate down to the oxide intermediate layer;
• wherein the MEMS structure is capped in (C) wherein an additional oxide layer and a final polysilicon layer are deposited on the MEMS structure, wherein etching accesses are etched into the final polysilicon layer, wherein the additional oxide layer is etched through the etching accesses, and wherein an exposed MEMS structure is produced and the etching accesses are closed by depositing another layer or by melting the accesses shut.