Method of fabricating MEMS devices using plasma etching and device therefor
A method for fabricating a MEMS sensor device. The method can include providing a substrate, forming an IC layer overlying the substrate, forming an oxide layer overlying the IC layer, forming a metal layer coupled to the IC layer through the oxide layer, forming a MEMS layer having a pair of designated sense electrode portions and a designated proof mass portion overlying the oxide layer, forming a via structure within each of the designated sense electrode portions, and etching the MEMS layer to form a pair of sense electrodes and a proof mass from the designated sense electrode portions and proof mass portions, respectively. The via structure can include a ground post and the proof mass can include a sense comb. The MEMS sensor device formed using this method can result is more well-defined edges of the proof mass structure.
1. A MEMS device, the device comprising:
a substrate member;
an IC (Integrated Circuit) layer overlying the substrate member;
an oxide layer overlying the IC layer comprising a pair of anchor portions;
a metal layer coupled to the IC layer through the oxide layer;
a silicon MEMS layer disposed above the oxide layer, wherein the silicon MEMS layer comprises a first portion and a second portion separated by a void in the silicon MEMS layer, wherein the first portion comprises a pair of designated stationary sense electrode portions, wherein each designated stationary sense electrode portion is respectively disposed above and upon one anchor portion of the pair of anchor portions, wherein the second portion comprises a movable proof mass portion, wherein a top-most surface of the first portion is in a same plane as a top-most surface of the second portion, and wherein a bottom-most surface of the first portion is in a same plane as a bottom-most surface of the second portion;
wherein a ground post is formed in a via structure formed within at least one designated stationary sense electrode portion of the pair of designated stationary sense electrode portions; and
a cap layer disposed on top of the silicon MEMS layer to thereby overlie at least the second portion of the MEMS layer, wherein the cap layer comprises a first plurality of stops that are disposed above and vertically aligned to the pair of designated stationary sense electrode portions and the pair of anchor portions.
2. The device of claim 1 wherein the MEMS device comprises a device selected from a group consisting of: an accelerometer and a gyroscope.
3. The device of claim 1 wherein the pair of designated stationary sense electrode portions are anchored to the oxide layer.
4. The device of claim 1 wherein a first stop from the first plurality of stops in the cap layer is initially disposed above, but not in contact with, at least a designated stationary sense electrode portion from the pair of designated sense electrode portions.
5. The device of claim 4 wherein a second stop from the first plurality of stops in the cap layer is initially disposed above, but not in contact with, the movable proof mass portion.
6. The device of claim 5 wherein a height of the first stop and a height of the second stop are substantially similar.
7. The device of claim 1 wherein the via structure extends into the oxide layer and reaches a metallic layer.
8. The device of claim 1 wherein the pair of designated stationary sense electrode portions are disposed on either side of the movable proof mass portion.
9. The device of claim 1
wherein the movable proof mass portion comprises a pair of proof masses; and
wherein the cap layer comprises a second plurality of stops that are disposed above, but not in contact with the pair of proof masses.
10. The device of claim 1
wherein the movable proof mass portion comprises a pair of proof masses; and
wherein the oxide layer comprises a pair of stops that are disposed below, but not in contact with the pair of proof masses.
11. A MEMS device, the device comprising:
a substrate member;
an IC (Integrated Circuit) layer overlying the substrate member;
an oxide layer overlying the IC layer comprising a pair of anchor portions;
a metal layer coupled to the IC layer through the oxide layer;
a silicon MEMS layer overlying the oxide layer, wherein the silicon MEMS layer comprises a first portion having a pair of designated portions anchored to at least the pair of anchor portions of the oxide layer and a second portion having a proof mass portion configured to move relative to the oxide layer, wherein the first portion and the second portion are formed from etching a silicon material layer, wherein a top-most surface of the first portion is in a same plane as a top-most surface of the second portion, and wherein a bottom-most surface of the first portion is in a same plane as a bottom-most surface of the second portion, wherein the first portion is laterally separated from the second portion;
wherein a ground post is formed in a via structure formed within at least one designated portion of the pair of designated portions anchored to an ancor portion of the pair of anchor portions of the oxide layer; and
a cap layer overlying the silicon MEMS layer, wherein the cap layer comprises a first plurality of stops that are disposed above and vertically aligned the pair of designated portions and to the pair of anchor portions of the oxide layer.
12. The device of claim 11 wherein the MEMS device comprises a device selected from a group consisting of: an accelerometer and a gyroscope.
13. The device of claim 11 wherein the pair of designated portions are anchored to the oxide layer.
14. The device of claim 11 wherein a first stop from the first plurality of stops in the cap layer is initially disposed above, but not in contact with, at least a designated portion from the pair of designated portions.
15. The device of claim 14 wherein a second stop from the first plurality of stops in the cap layer is initially disposed above, but not in contact with, the movable proof mass portion.
16. The device of claim 15 wherein a height of the first stop and a height of the second stop are substantially similar.
17. The device of claim 11 wherein the via structure extends into the oxide layer and reaches a metallic layer.
18. The device of claim 11 wherein the pair of designated portions are disposed on either side of the second portion.
19. The device of claim 11
wherein the proof mass portion comprises a pair of proof masses; and
wherein the cap layer comprises a second plurality of stops that are disposed above the pair of proof masses.
20. The device of claim 11
wherein the proof mass portion comprises a pair of proof masses; and
wherein the oxide layer comprises a pair of stops that are disposed below, but not in contact with the pair of proof masses.