Low-stress doped ultrananocrystalline diamond
Nanocrystalline diamond coatings exhibit stress in nano/micro-electro mechanical systems (MEMS). Doped nanocrstalline diamond coatings exhibit increased stress. A carbide forming metal coating reduces the in-plane stress. In addition, without any metal coating, simply growing UNCD or NCD with thickness in the range of 3-4 micron also reduces in-plane stress significantly. Such coatings can be used in MEMS applications.
1. A method of fabricating a device comprising:
depositing, by vapor deposition, nitrogen doped ultrananocrystalline diamond (UNCD) and boron or nitrogen dopant, forming, by in-situ incorporation a nitrogen doped ultrananocrystalline diamond (B/N-UNCD);
depositing a layer of depositing a layer of a carbide-forming metal on the(B/N-UNCD); and
exerting a tensile stress by the carbide-forming metal, tuning the internal stress properties of the device by controlling deposition thickness of the carbide forming metal.
2. The method of claim 1 , wherein the carbide forming metal is titanium.
3. The method of claim 1 , wherein a dopant in the doped B/N-UNCD is nitrogen (N-UNCD).
4. The method of claim 3 , wherein the device is a nano/micro-electro mechanical device (MEMS).
5. The method of claim 3 , further comprising
fabricating the MEMS by: depositing an oxide layer on a silicon base;
depositing a tungsten layer on the oxide layer;
depositing the N-UNCD on the tungsten layer
depositing a Ti layer on N-UNCD; and
etching to form the MEMS.
6. The method of claim 5 , further comprising tuning the internal stress properties of the device by controlling deposition thickness of the Ti layer.
7. The device of claim 1 , wherein the N-UNCD layer is 3 microns to 4 microns thick.
8. The device of claim 1 , wherein the carbide layer has a thickness of about 50 nm.
9. A device comprising:
a silicon base;
an oxide layer;
a conductive nitrogen doped ultrananocrystalline diamond (N-UNCD) layer of 3 microns to 4 microns; and
a titanium carbide layer deposited on the N-UNCD layer, the titanium carbide layer exerting a tensile stress on the N-UNCD layer;
wherein the residual stress of the titanium carbide layer and N-UNCD layer is about zero.
10. The device of claim 9 , further comprising a tungsten layer.
11. The device of claim 9 wherein the device is a nano/micro-electro mechanical device (MEMS).
12. The device of claim 11 , wherein the MEMS device comprises a thermal actuator.
13. The device of claim 12 , wherein the MEMS device exhibits a maximum displacement (in a linear direction) of 8 microns and a minimum step resolution of 0.4 nm.
14. The device of claim 11 , wherein the titanium carbide layer has a thickness of 30-50 nm.
15. The device of claim 11 , wherein the device exhibits negligible in-plane stress.
16. The device of claim 9 , further comprising the doped N-UNCD layer and an un-doped UNCD layer.
17. A nano/micro-electro mechanical (MEMS) device comprising:
a non-conductive base;
a laterally movable conductive thermal actuator disposed on the non-conductive base, the actuator comprising doped ultrananocrystalline diamond (UNCD);
wherein the UNCD exhibits negligible in-plane stress.
18. The device of claim 17 , wherein the conductive thermal actuator is a chevron actuator comprising nitrogen or boron doped N-UNCD.