Methods of making a MEMS device by monitoring a process parameter
View Patent ↗Embodiments of the present invention relate to methods and systems for making a microelectromechanical system MEMS device comprising supplying an etchant to etch one or more sacrificial structures of the system in a chamber. A process parameter relating to the pressure within the chamber is monitored as a function of time to provide an indication of the extent of the etching of the one or more sacrificial structures.
1. A method for making a microelectromechanical systems (MEMS) device, comprising:
(a) providing a chamber and an unreleased MEMS device situated therein, the unreleased MEMS device comprising a sacrificial structure;
(b) supplying an etchant to the chamber to thereby etch the sacrificial structure;
(c) monitoring a process parameter related to the pressure within the chamber as a function of time to thereby provide an indication of the extent of etching of the sacrificial structure; and
(d) removing from the chamber at least a portion of a gaseous product that is formed from the etching of the sacrificial structure with the etchant.
2. The method of claim 1 , wherein the monitored process parameter is the change in pressure within the chamber as a function of time.
3. The method of claim 1 , wherein the monitored process parameter comprises at least one of the temperature within the chamber and the change in temperature within the chamber as a function of time.
4. The method of claim 1 , further comprising discontinuing the supplying of the etchant to the chamber.
5. The method of claim 1 further comprising conducting one or more additional cycles by repeating at least steps (b), (c) and (d).
6. The method of claim 5 , wherein the monitored process parameter is a change in a time derivative of a within-cycle pressure across cycles.
7. The method of claim 5 , further comprising discontinuing an initiation of an additional cycle upon the providing of the indication.
8. The method of claim 5 , wherein the indication is provided when the monitored process parameter corresponding to a specific time relative to the beginning of an additional cycle crosses a pre-selected threshold.
9. The method of claim 5 , wherein the indication is provided when the monitored process parameter corresponding to a specific time relative to the beginning of an additional cycle crosses a pre-selected second threshold after having already crossed a pre- selected first threshold.
10. The method of claim 5 , further comprising comparing a monitored process parameter measured at a specific time relative to the beginning of the first or additional cycle to a monitored process parameter measured at the same specific time relative to the beginning of a different additional cycle to thereby provide the indication.
11. The method of claim 1 , wherein the indication is provided when the monitored process parameter crosses a pre-selected threshold.
12. The method of claim 11 , wherein the pre-selected threshold is about zero.
13. The method of claim 11 , wherein the pre-selected threshold is about 1%, about 5% or about 10% of a maximum process parameter relative to an initial process parameter.
14. The method of claim 11 , wherein the pre-selected threshold is about 105% of a first pressure expected if the etchant does not react with another substance.
15. The method of claim 11 , wherein the pre-selected threshold is a pressure change of about 0.2 mT per second or about −0.2 mT per second.
16. The method of claim 1 , wherein the unreleased MEMS device comprises:
a substrate;
one or more first layers positioned over the substrate;
a sacrificial layer comprising a sacrificial structure positioned over the one or more first layers; and
one or more second layers positioned over the sacrificial layer.
17. The method of claim 16 , wherein the one or more first layers comprise a first electrode.
18. The method of claim 16 , wherein the one or more second layers comprise a second electrode.
19. The method of claim 1 , wherein a reaction between the etchant and the sacrificial structure produces primarily gaseous products.
20. The method of claim 1 , wherein the sacrificial structure comprises molybdenum.
21. The method of claim 1 , wherein the etchant comprises xenon difluoride.
22. The method of claim 1 , further comprising:
positioning one or more additional unreleased MEMS devices in the chamber, the additional unreleased MEMS devices comprising additional one or more sacrificial structures.
23. The method of claim 1 , wherein the unreleased MEMS device comprises an unreleased interferometric modulator.
24. A MEMS device manufactured by the method of claim 1 .
25. A method for making a microelectromechanical systems (MEMS) device, comprising:
(a) providing a chamber and an unreleased MEMS device situated therein, the unreleased MEMS device comprising a sacrificial structure;
(b) supplying an etchant to the chamber to thereby etch the sacrificial structure; and
(c) monitoring a process parameter related to the pressure within the chamber as a function of time to thereby provide an indication of the extent of etching of the sacrificial structure, wherein the indication is provided when the monitored process parameter crosses a pre-selected threshold.
26. The method of claim 25 , wherein the monitored process parameter is the change in pressure within the chamber as a function of time.
27. The method of claim 25 , wherein the monitored process parameter comprises at least one of the temperature within the chamber and the change in temperature within the chamber as a function of time.
28. The method of claim 25 , further comprising discontinuing the supplying of the etchant to the chamber.
29. The method of claim 25 , further comprising:
(d) removing from the chamber at least a portion of a gaseous product.
30. The method of claim 29 , further comprising conducting one or more additional cycles by repeating at least steps (b), (c) and (d).
31. The method of claim 30 , wherein the monitored process parameter is a change in a time derivative of a within-cycle pressure across cycles.
32. The method of claim 30 , further comprising discontinuing an initiation of an additional cycle upon the providing of the indication.
33. The method of claim 30 , wherein the indication is provided when the monitored process parameter corresponding to a specific time relative to the beginning of an additional cycle crosses the pre-selected threshold.
34. The method of claim 30 , wherein the indication is provided when the monitored process parameter corresponding to a specific time relative to the beginning of an additional cycle crosses a second pre-selected second threshold after having already crossed the first pre-selected threshold.
35. The method of claim 30 , further comprising comparing a monitored process parameter measured at a specific time relative to the beginning of the first or additional cycle to a monitored process parameter measured at the same specific time relative to the beginning of a different additional cycle to thereby provide the indication.
36. The method of claim 25 , wherein the pre-selected threshold is about zero.
37. The method of claim 25 , wherein the pre-selected threshold is about 1%, about 5% or about 10% of a maximum process parameter relative to an initial process parameter.
38. The method of claim 25 , wherein the pre-selected threshold is about 105% of a first pressure expected if the etchant does not react with another substance.
39. The method of claim 25 , wherein the pre-selected threshold is a pressure change of about 0.2 mT per second or about −0.2 mT per second.
40. The method of claim 25 , wherein the unreleased MEMS device comprises:
a substrate;
one or more first layers positioned over the substrate;
a sacrificial layer comprising a sacrificial structure positioned over the one or more first layers; and
one or more second layers positioned over the sacrificial layer.
41. The method of claim 40 , wherein the one or more first layers comprise a first electrode.
42. The method of claim 40 , wherein the one or more second layers comprise a second electrode.
43. The method of claim 25 , wherein a reaction between the etchant and the sacrificial structure produces primarily gaseous products.
44. The method of claim 25 , wherein the sacrificial structure comprises molybdenum.
45. The method of claim 25 , wherein the etchant comprises xenon difluoride.
46. The method of claim 25 , further comprising:
positioning one or more additional unreleased MEMS devices in the chamber, the additional unreleased MEMS devices comprising additional one or more sacrificial structures.
47. The method of claim 25 , wherein the unreleased MEMS device comprises an unreleased interferometric modulator.
48. A MEMS device manufactured by the method of claim 25 .
49. A method for making a microelectromechanical systems (MEMS) device, comprising:
(a) providing a chamber and an unreleased MEMS device situated therein, the unreleased MEMS device comprising a sacrificial structure;
(b) supplying an etchant to the chamber to thereby etch the sacrificial structure; and
(c) monitoring a process parameter related to the pressure within the chamber as a function of time to thereby provide an indication of the extent of etching of the sacrificial structure;
wherein the unreleased MEMS device comprises:
a substrate;
one or more first layers positioned over the substrate;
a sacrificial layer comprising a sacrificial structure positioned over the one or more first layers; and
one or more second layers positioned over the sacrificial layer.
50. The method of claim 49 , wherein the monitored process parameter is the change in pressure within the chamber as a function of time.
51. The method of claim 49 , wherein the monitored process parameter comprises at least one of the temperature within the chamber and the change in temperature within the chamber as a function of time.
52. The method of claim 49 , further comprising discontinuing the supplying of the etchant to the chamber.
53. The method of claim 49 , further comprising:
(d) removing from the chamber at least a portion of a gaseous product.
54. The method of claim 53 , further comprising conducting one or more additional cycles by repeating at least steps (b), (c) and (d).
55. The method of claim 54 , wherein the monitored process parameter is a change in a time derivative of a within-cycle pressure across cycles.
56. The method of claim 54 , further comprising discontinuing an initiation of an additional cycle upon the providing of the indication.
57. The method of claim 54 , wherein the indication is provided when the monitored process parameter corresponding to a specific time relative to the beginning of an additional cycle crosses a pre-selected threshold.
58. The method of claim 54 , wherein the indication is provided when the monitored process parameter corresponding to a specific time relative to the beginning of an additional cycle crosses a pre-selected second threshold after having already crossed a pre-selected first threshold.
59. The method of claim 54 , further comprising comparing a monitored process parameter measured at a specific time relative to the beginning of the first or additional cycle to a monitored process parameter measured at the same specific time relative to the beginning of a different additional cycle to thereby provide the indication.
60. The method of claim 49 , wherein the indication is provided when the monitored process parameter crosses a pre-selected threshold, wherein the pre-selected threshold is about zero.
61. The method of claim 49 , wherein the indication is provided when the monitored process parameter crosses a pre-selected threshold, wherein the pre-selected threshold is about 1%, about 5% or about 10% of a maximum process parameter relative to an initial process parameter.
62. The method of claim 49 , wherein the indication is provided when the monitored process parameter crosses a pre-selected threshold, wherein the pre-selected threshold is about 105% of a first pressure expected if the etchant does not react with another substance.
63. The method of claim 49 , wherein the indication is provided when the monitored process parameter crosses a pre-selected threshold, wherein the pre-selected threshold is a pressure change of about 0.2 mT per second or about −0.2 mT per second.
64. The method of claim 49 , wherein the one or more first layers comprise a first electrode.
65. The method of claim 49 , wherein the one or more second layers comprise a second electrode.
66. The method of claim 49 , wherein a reaction between the etchant and the sacrificial structure produces primarily gaseous products.
67. The method of claim 49 , wherein the sacrificial structure comprises molybdenum.
68. The method of claim 49 , wherein the etchant comprises xenon diflouride.
69. The method of claim 49 , further comprising:
positioning one or more additional unreleased MEMS devices in the chamber, the additional unreleased MEMS devices comprising additional one or more sacrificial structures.
70. The method of claim 49 , wherein the unreleased MEMS device comprises an unreleased interferometric modulator.
71. A MEMS device manufactured by the method of claim 49 .