Method for producing a micromechanical device comprising a cavity having a melt seal

A method for producing a micromechanical device having a cavity, an access channel to the cavity, and a melt seal in the access channel, the method comprising steps including:

• (A) providing a microelectromechanical systems (MEMS) substrate having micromechanical functional layers on an inner side bounding the cavity;
• (B) structuring an oxide layer to form an oxide mask having a first recess having a first diameter on an outer side of the MEMS substrate;
• (C) applying a resist mask to the oxide mask and the first recess;
• (D) introducing a second recess having a second diameter into the resist mask in an area of the first recess, wherein the second diameter is smaller than the first diameter;
• (E) introducing a first trench into the MEMS substrate through the second recess having the second diameter, to a first depth;
• (F) removing the resist mask;
• (G) introducing a second trench into the MEMS substrate through the first recess having the first diameter, to a second depth and simultaneously deepening the first trench at least through the micromechanical substrate to the inner side;
• (H) adjusting a desired gas composition at a desired pressure in the cavity;
• and
• (I) sealing the first trench using a melt plug by melting substrate material of the MEMS substrate that surrounds the first trench.