MEMS DEVICE AND METHOD FOR MANUFACTURING A MEMS DEVICE

• US 20160060105A1
• Filed: 08/21/2015
• Published: 03/03/2016
• Est. Priority Date: 09/03/2014
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: KOLB, Stefan, MEISER, Andreas, SCHLOESSER, Till, WERNER, Wolfgang
• Granted Patent: US 10,246,325 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B81C 1/00182 Arrangements of deformable or non-deformable structures, e.g. membrane and cavity for use in a transducer
• CPC Class Codes: B81C 2201/019 Bonding or gluing multiple substrate layers

Abstract

A method for producing a MEMS device comprises forming a semiconductor layer stack, the semiconductor layer stack comprising at least a first monocrystalline semiconductor layer, a second monocrystalline semiconductor layer and a third monocrystalline semiconductor layer, the second monocrystalline semiconductor layer formed between the first and third monocrystalline semiconductor layers. A semiconductor material of the second monocrystalline semiconductor layer is different from semiconductor materials of the first and third monocrystalline semiconductor layers. After forming the semiconductor layer stack, at least a portion of each of the first and third monocrystalline semiconductor layers is concurrently etched.

Claims

1. 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 and a third monocrystalline semiconductor layer, the second monocrystalline semiconductor layer formed between the first and third monocrystalline semiconductor layers, wherein a semiconductor material of the second monocrystalline semiconductor layer is different from semiconductor materials of the first and third monocrystalline semiconductor layers; and

after forming the semiconductor layer stack, concurrently etching at least a portion of each of the first and third monocrystalline semiconductor layers.

2. The method according to claim 1, wherein the first, second and third monocrystalline semiconductor layers are epitaxial grown monocrystalline semiconductor layers.

3. The method according to claim 1, wherein a movable MEMS element is formed by a portion of the second monocrystalline layer, the portion of the second monocrystalline layer being released by the etching of at least a portion of each of the first and third monocrystalline semiconductor layers.

4. The method according to claim 3, wherein the semiconductor layer stack further comprises fourth and fifth semiconductor layers, wherein the first monocrystalline semiconductor layer is formed above the fourth semiconductor layer and wherein the fifth semiconductor layer is formed above the third monocrystalline semiconductor layer, wherein a first gap between the fourth semiconductor layer and the second monocrystalline semiconductor layer and a second gap between the second monocrystalline semiconductor layer and the fifth semiconductor layer is formed by the etching of at least a portion of the first and third monocrystalline semiconductor layers.

5. The method according to claim 4, wherein the second monocrystalline semiconductor layer and the fourth and fifth semiconductor layers comprise a same semiconductor material.

6. The method according to claim 5, wherein the first and third monocrystalline semiconductor layers comprise a semiconductor material different from a semiconductor material of the second monocrystalline semiconductor layer and the fourth and fifth semiconductor layers.

7. The method according to claim 1, wherein a semiconductor crystal structure of the first and third monocrystalline semiconductor layers have a first lattice constant which is different to a second lattice constant of a semiconductor crystal structure of the second monocrystalline semiconductor layer, wherein a difference of the first and second lattice constants is not greater than 10%.

8. The method according to claim 7, wherein the first and third monocrystalline semiconductor layers comprise a compound semiconductor.

9. The method according to claim 8, wherein a crystal structure of the second monocrystalline semiconductor layer is formed by a lattice arrangement of first atoms and a crystal structure of the compound semiconductor is formed by a lattice arrangement of the first atoms and second atoms.

10. The method according to claim 9 wherein the first and second atoms are chemical elements of a same group within a periodic table of chemical element.

11. The method according to claim 1, wherein the etching of at least a portion of each of the first and third monocrystalline semiconductor layer removes at least a portion of the first and third monocrystalline semiconductor layers above and below of a first portion of the second monocrystalline semiconductor layer while the first and third monocrystalline semiconductor layer remains above and below a second portion of the second monocrystalline semiconductor layer.

12. The method according to claim 11, wherein no etch stop is provided lateral to the first and third monocrystalline semiconductor layers to stop the etching of at least a portion of the first and third monocrystalline semiconductor layers.

13. The method according to claim 1, wherein a lateral etch stop is provided lateral to at least one of the first and third monocrystalline semiconductor layers to stop the etching of at least a portion of the first and third monocrystalline semiconductor layers.

14. The method according to claim 1, wherein an etchant is provided via channels which vertically extend at least between the first and third monocrystalline semiconductor layers.

15. The method according to claim 14, wherein the channels are at least partially filled with monocrystalline semiconductor material prior to the etching of at least a portion of the first and third monocrystalline semiconductor layers.

16. The method according to claim 15, wherein the monocrystalline semiconductor material in the channels comprises a same material as the material of at least one of the first and third monocrystalline semiconductor layers.

17. The method according to claim 1, wherein a portion of the second monocrystalline layer provides a movable element of the MEMS device, wherein the second monocrystalline semiconductor layer is structured prior to the etching of at least a portion of the first and third monocrystalline semiconductor layers such that gap portions at least partially surrounding the portion of the second monocrystalline layer are formed in the second monocrystalline semiconductor layer.

18. The method according to claim 17, wherein forming the semiconductor stack comprises:

epitaxial growing the second monocrystalline semiconductor layer on the first monocrystalline semiconductor layer;

structuring the second monocrystalline semiconductor layer such that gap portions are formed by removing at least a portion of the second monocrystalline semiconductor layer;

providing an epitaxial grow process to form the third monocrystalline semiconductor layer above the second monocrystalline semiconductor layer and to fill the gap portions with epitaxial grown semiconductor material;

etching at least a portion of each of the first and third monocrystalline semiconductor layers and at least a portion of the epitaxial grown semiconductor material in the gap portions.

19. The method according to claim 14, wherein a portion of the second monocrystalline semiconductor layer forms a movable element of the MEMS device, wherein the channels at least partially surround the portion of the second monocrystalline semiconductor layer.

20. The method according to claim 4, wherein the fifth semiconductor layer forms a cover of the MEMS device.

21. The method according to claim 20, wherein the method further comprises a forming of channels extending at least from the fifth semiconductor layer to the first monocrystalline semiconductor layer, and wherein the method further comprises a process to seal the channels in the fifth layer.

22. The method according to claim 4, further comprising forming a sixth monocrystalline semiconductor layer, a seventh monocrystalline semiconductor layer and an eighth monocrystalline semiconductor layer, wherein the sixth monocrystalline semiconductor layer is formed above the fifth semiconductor layer and wherein the seventh monocrystalline semiconductor layer is formed between the sixth monocrystalline semiconductor layer and the eighth monocrystalline semiconductor layer, and wherein at least a portion of the sixth and eighth monocrystalline semiconductor layers is etched to release a further movable MEMS element.

23. A MEMS device comprising:

a movable MEMS element comprising a monocrystalline semiconductor material;

a non-movable semiconductor layer stack lateral to the movable MEMS element, the semiconductor layer stack comprising at least a first monocrystalline semiconductor layer, a second monocrystalline semiconductor layer and a third monocrystalline semiconductor layer, the second monocrystalline semiconductor layer formed between the first and third monocrystalline semiconductor layers; and

a gap structure surrounding the movable MEMS element and separating the movable MEMS element in lateral directions from the layer stack.

24. The MEMS device according to claim 23, wherein a vertical extension of the movable MEMS element is equal to a vertical extension of the second monocrystalline semiconductor layer, wherein a vertical extension of a first gap below the movable MEMS element is equal to a vertical extension of the first monocrystalline semiconductor layer and a vertical extension of a second gap above the movable MEMS element is equal to a vertical extension of the third monocrystalline semiconductor layer.

25. A method of producing vertically stacked MEMS devices, the method comprising:

forming a first plurality of monocrystalline semiconductor layers of a semiconductor material such that a first monocrystalline semiconductor layer is formed between a first pair of monocrystalline semiconductor layers;

etching at least a portion of each layer of the first pair of monocrystalline semiconductor layers;

forming a second plurality of monocrystalline semiconductor layers of a semiconductor material such that a second monocrystalline semiconductor layer is formed between a second pair of monocrystalline semiconductor layers;

etching at least a portion of each layer of the second pair of monocrystalline semiconductor layers.

26. The method according to claim 25, wherein etching at least a portion of each layer of the first pair of monocrystalline semiconductor layers releases a first movable element of a first MEMS device and etching at least a portion of each layer of the second pair of monocrystalline semiconductor layers releases a second movable element of a second MEMS device.