The invention relates to a sensor with at least one silicon-based micromechanical structure, which is integrated with a sensor chamber of a foundation wafer, and with at least one covering that covers the foundation wafer in the region of the sensor chamber, and to a method for producing a sensor. It is provided that in the sensor of the invention, the covering (13) comprises a first layer (32) (deposition layer) that is permeable to an etching medium and the reaction products, and a hermetically sealing second layer (34) (sealing layer) located above it, and that in the method of the invention, at least the sensor chamber (28) present in the foundation wafer (11) after the establishment of the structure (26) is filled with an oxide (30), in particular CVD oxide or porous oxide; the sensor chamber (28) is covered by a first layer (32) (deposition layer), in particular of polysilicon, that is transparent to an etching medium and the reaction products or is retroactively made transparent; the oxide (30) in the sensor chamber (28) is removed through the deposition layer (32) with the etching medium; and next, a second layer (34) (sealing layer), in particular of metal or an insulator, is applied to the deposition layer (32) and hermetically seals off the sensor chamber (28).