MEMS device and method for manufacturing the same
View Patent ↗A MEMS device, including: a substrate having a first principal plane and a second principal plane opposite to the first principal plane; a through hole formed in the substrate; and a vibrating film formed over the first principal plane so as to cover the through hole. The first principal plane and the second principal plane are both a (110) crystal face; and the through hole has a substantially rhombic shape on the second principal plane.
1. A MEMS device, comprising:
a substrate having a first principal plane and a second principal plane opposite to the first principal plane;
a through hole formed in the substrate; and
a vibrating film formed over the first principal plane so as to cover the through hole, wherein:
the first principal plane and the second principal plane are both a (110) crystal face;
the through hole defines inner walls of the substrate, a first part of the inner walls being slanted relative to the first principal plane and a second part of the inner walls being substantially vertical relative to the second principal plane, and
the through hole has a substantially rhombic shape on the second principal plane.
2. The MEMS device of claim 1 , wherein the substrate is a silicon substrate.
3. The MEMS device of claim 1 , wherein the vibrating film is partially held by a holding section.
4. The MEMS device of claim 1 , wherein:
a first interior angle of the rhombic shape is in a range of 70.6±3 degrees; and
a second interior angle of the rhombic shape is in a range of 109.4±3 degrees.
5. The MEMS device of claim 1 , wherein a longer diagonal of the rhombic shape is substantially parallel to a <001> orientation on the second principal plane being a (110) crystal face.
6. The MEMS device of claim 1 , wherein a size of the through hole on the first principal plane is smaller than a size of the through hole on the second principal plane.
7. The MEMS device of claim 1 , wherein the through hole has a substantially hexagonal shape on the first principal plane.
8. The MEMS device of claim 7 , wherein:
two of corner portions of the hexagonal shape that are opposing each other have a first interior angle in a range of 109.4±3 degrees; and
the other four of the corner portions of the hexagonal shape have a second interior angle in a range of 125.3±3 degrees.
9. The MEMS device of claim 7 , wherein a side extending between adjacent ones of second interior angles of the hexagonal shape is substantially vertical to a <001> orientation on the first principal plane being a (110) crystal face.
10. The MEMS device of claim 7 , wherein the vibrating film has a substantially hexagonal shape.
11. The MEMS device of claim 1 , wherein the substrate has a substantially rhombic shape.
12. The MEMS device of claim 1 , further comprising:
a fixed film formed over the vibrating film so as to oppose the vibrating film; and
an air gap interposed between the vibrating film and the fixed film.
13. The MEMS device of claim 1 , wherein the first part of the inner walls is located on the first principal side relative to the second part of the inner walls.
14. A method for manufacturing a MEMS device, comprising the steps of:
(a) forming a sacrificial layer on a first principal plane of a substrate having the first principal plane and a second principal plane opposite to the first principal plane;
(b) forming a vibrating film over the sacrificial layer;
(c) etching the substrate from a side of the second principal plane to thereby form a through hole in the substrate; and
(d) supplying an etchant through the through hole, thereby removing the sacrificial layer and expanding the through hole from a side of the first principal plane, wherein:
the first principal plane and the second principal plane are both a (110) crystal face;
the through hole defines inner walls of the substrate, a first part of the inner walls being slanted relative to the first principal plane and a second part of the inner walls being substantially vertical relative to the second principal plane, and
the through hole has a substantially rhombic shape on the second principal plane.
15. The method for manufacturing a MEMS device of claim 14 , wherein the substrate is a silicon substrate.
16. The method for manufacturing a MEMS device of claim 14 , wherein the vibrating film is partially held by a holding section.
17. The method for manufacturing a MEMS device of claim 14 , wherein:
a first interior angle of the rhombic shape is in a range of 70.6±3 degrees; and
a second interior angle of the rhombic shape is in a range of 109.4±3 degrees.
18. The method for manufacturing a MEMS device of claim 14 , wherein a longer diagonal of the rhombic shape is substantially parallel to a <001> orientation on the second principal plane being a (110) crystal face.
19. The method for manufacturing a MEMS device of claim 14 , wherein a size of the through hole on the first principal plane after completion of the step (d) is smaller than a size of the through hole on the second principal plane after completion of the step (d).
20. The method for manufacturing a MEMS device of claim 14 , wherein the through hole has a substantially hexagonal shape on the first principal plane after completion of the step (d).
21. The method for manufacturing a MEMS device of claim 20 , wherein:
two of corner portions of the hexagonal shape that are opposing each other have a first interior angle in a range of 109.4±3 degrees; and
the other four of the corner portions of the hexagonal shape have a second interior angle in a range of 125.3±3 degrees.
22. The method for manufacturing a MEMS device of claim 20 , wherein a side extending between adjacent ones of the second interior angles of the hexagonal shape is substantially vertical to a <001> orientation on the first principal plane being a (110) crystal face.
23. The method for manufacturing a MEMS device of claim 20 , wherein the vibrating film has a substantially hexagonal shape.
24. The method for manufacturing a MEMS device of claim 14 , wherein the substrate has a substantially rhombic shape.
25. The method for manufacturing a MEMS device of claim 14 , further comprising, after the step (b), a step (e) of forming a fixed film over the vibrating film with a sacrificial film interposed therebetween and then removing the sacrificial film to thereby form an air gap between the vibrating film and the fixed film.
26. The method of manufacturing a MEMS device of claim 14 , wherein the first part of the inner walls is located on the first principal side relative to the second part of the inner walls.
27. A device, comprising:
a substrate having a first principal plane and a second principal plane opposite to the first principal plane; and
a through hole formed in the substrate; wherein:
the first principal plane and the second principal plane are both a (110) crystal face;
the through hole defines inner walls of the substrate, a first part of the inner walls being slanted relative to the first principal plane and a second part of the inner walls being substantially vertical relative to the second principal plane, and
the through hole has a substantially rhombic shape on the second principal plane.
28. The device of claim 27 , wherein the substrate is a silicon substrate.
29. The device of claim 27 , wherein the first part of the inner walls is located on the first principal side relative to the second part of the inner walls.
30. A method for manufacturing a device, comprising the steps of:
(a) forming a sacrificial layer on a first principal plane of a substrate having the first principal plane and a second principal plane opposite to the first principal plane;
(b) etching the substrate from a side of the second principal plane to thereby form a through hole in the substrate; and
(c) supplying an etchant through the through hole, thereby removing the sacrificial layer and expanding the through hole from a side of the first principal plane, wherein:
the first principal plane and the second principal plane are both a (110) crystal face;
the through hole defines inner walls of the substrate, a first part of the inner walls being slanted relative to the first principal plane and a second part of the inner walls being substantially vertical relative to the second principal plane, and
the through hole has a substantially rhombic shape on the second principal plane.
31. The method of manufacturing a device of claim 30 , wherein the substrate is a silicon substrate.
32. The method of manufacturing a device of claim 30 , wherein the first part of the inner walls is located on the first principal side relative to the second part of the inner walls.