MEMS device and method for manufacturing a MEMS device

A method for producing a MEMS device, comprising:

• forming a semiconductor layer stack, the semiconductor layer stack comprising at least a first monocrystalline semiconductor layer, a second monocrystalline semiconductor layer, a third monocrystalline semiconductor layer, a fourth monocrystalline semiconductor layer, and a fifth monocrystalline semiconductor layer, the second monocrystalline semiconductor layer formed between the first and third monocrystalline semiconductor layers, the first monocrystalline semiconductor layer being formed above the fourth monocrystalline semiconductor layer and the fifth monocrystalline semiconductor layer being formed above the third monocrystalline semiconductor layer, wherein a semiconductor material of the second monocrystalline semiconductor layer is different from semiconductor materials of the first and third monocrystalline semiconductor layers, at least one layer of the semiconductor layer stack includes a compound semiconductor material and at least one layer of the semiconductor layer stack includes a non-compound semiconductor material, and adjacent layers of the first, the second, and the third monocrystalline semiconductor layers have mutual different doping types;
• etching the first, the second, the third, and the fifth monocrystalline semiconductor layers to form channels extending from the fifth monocrystalline semiconductor layer to the first monocrystalline semiconductor layer and terminating within the first monocrystalline semiconductor layer;
• etching, via the channels, the first and the third monocrystalline semiconductor layers, wherein a movable first portion of the second monocrystalline semiconductor layer forming a movable MEMS element is released by removing a first portion of the first monocrystalline semiconductor layer and a first portion of the third monocrystalline semiconductor layer, second and third portions of the first monocrystalline semiconductor layer remaining below respective second and third portions of the second monocrystalline semiconductor layer, and second and third portions of the third monocrystalline semiconductor layer remaining above the second and the third portions of the second monocrystalline semiconductor layer, the movable first portion of the second monocrystalline semiconductor layer being separated laterally by gaps defined by the channels and vertically by gaps defined by the removed first portion of the first monocrystalline semiconductor layer between the fourth monocrystalline semiconductor layer and the second monocrystalline semiconductor layer and the removed first portion of the third monocrystalline semiconductor layer between the second monocrystalline semiconductor layer and the fifth monocrystalline semiconductor layer;
• and
• providing a monocrystalline semiconductor material in a portion of the channels within the fifth monocrystalline semiconductor layer to seal the channels.