ETCHING PROCESSES USED IN MEMS PRODUCTION
The efficiency of an etching process may be increased in various ways, and the cost of an etching process may be decreased. Unused etchant may be isolated and recirculated during the etching process. Etching byproducts may be collected and removed from the etching system during the etching process. Components of the etchant may be isolated and used to general additional etchant. Either or both of the etchant or the layers being etched may also be optimized for a particular etching process.
1 . A method of fabricating an electronic device comprising a sacrificial material, wherein the method comprises:
providing an electronic device comprising a sacrificial material, the sacrificial material comprising a compound of the general formula M p X q , wherein M is selected from Mo, W, Si, and Ge; X is selected from Cl, F, O, N, and Si, wherein M is different from X, wherein p and q are in the range of 1 to 6, and wherein a molar volume of M p X q for a given M is greater than a molar volume of M; and
exposing the electronic device to an etchant.
2 . The method of claim 1 , wherein the etchant comprises a noble gas fluoride.
3 . The method of claim 2 , wherein the etchant further comprises O 2 .
4 . The method of claim 2 , wherein the etchant comprises XeF 2 .
5 . The method of claim 4 , wherein for a given M, a molar unit of M p X q is etchable by a smaller volume of XeF 2 than a molar unit of M.
6 . The method of claim 1 , wherein the sacrificial material comprises MoF 3 .
7 . The method of claim 1 , wherein the sacrificial material comprises MoF 4 .
8 . The method of claim 1 , wherein the sacrificial material comprises MoF 6 .
9 . The method of claim 1 , wherein the sacrificial material comprises MoN.
10 . The method of claim 1 , wherein the sacrificial material comprises MoSi 2 .
11 . The method of claim 1 , wherein the sacrificial material comprises MoO 2 .
12 . The method of claim 1 , wherein the sacrificial material comprises MoO 3 .
13 . The method of claim 1 , wherein the sacrificial material comprises MoCl 3 .
14 . The method of claim 1 , wherein the sacrificial material comprises WN 2 .
15 . The method of claim 1 , wherein the sacrificial material comprises WCl 4 .
16 . The method of claim 1 , wherein the sacrificial material comprises WO 2 .
17 . The method of claim 1 , wherein the sacrificial material comprises WF 4 .
18 . The method of claim 1 , wherein the sacrificial material comprises SiO.
19 . The method of claim 1 , wherein the sacrificial material comprises Si 3 N 4 .
20 . The method of claim 1 , wherein the sacrificial material comprises GeF 2 .
21 . A partially fabricated electronic device comprising a sacrificial material, the sacrificial material comprising a compound of the general formula M p X q , wherein M is selected from Mo, W, Si, and Ge; X is selected from Cl, F, O, N, and Si, wherein M is different from X, wherein p and q are in the range of 1 to 6, and wherein a molar volume of M p X q for a given M is greater than a molar volume of M.
22 . The device of claim 21 , wherein for a given M, a molar unit of M p X q is etchable by a smaller volume of XeF 2 than a molar unit of M.
23 . An etching device for use in fabricating a MEMS device, the etching device comprising:
a storage system configured to store an etchant, wherein the etchant comprises XeF 2 and O 2 ;
an etching chamber configured to retain a MEMS device during an etching process, wherein the etching chamber is in fluid communication with the storage system; and
a cold trap in fluid communication with the etching chamber, wherein the cold trap is configured to remove a byproduct of the etching process.
24 . The etching device of claim 23 , wherein the storage system comprises:
a first storage chamber configured to store XeF 2 ;
a second storage chamber configured to store O 2 ; and
a mixing chamber in fluid communication with both of said first and second storage chambers.
25 . The etching device of claim 23 , additionally comprising a purge storage chamber, wherein the purge storage chamber is configured to store a purge gas, and wherein the purge storage chamber is in fluid communication with the etching chamber.
26 . The etching device of claim 23 , additionally comprising:
an exhaust pump in fluid communication with the etching chamber, wherein the exhaust pump is configured to remove process gases from the etching chamber; and
a size discriminator configured to separate components from the process gases.