Method of fabricating a MEMS device
A microelectromechanical system (MEMS) is comprised of a micromirror device attached to a semiconductor device. A first spacer layer is formed and patterned to form hinge via openings. A hinge metal is deposited above the first spacer layer to form the hinge and the hinge vias. A capping layer is formed above the hinge metal and hinge vias. A second spacer layer is formed above the capping layer and patterned to form a mirror via. The capping layer protects the hinge metal from the developer solution used in the patterning step. The capping layer is removed from within the mirror via opening. Another metal layer is deposited above the second spacer layer to form the mirror and the mirror via.
1. A method of fabricating a microelectromechanical system (MEMS) device, comprising:
depositing a first photoresist spacer layer above a substrate with circuits formed therein;
patterning hinge via openings within the first photoresist spacer layer;
depositing a hinge metal layer above the first photoresist spacer layer and within the hinge via openings to form a hinge and hinge vias;
depositing a capping layer above the hinge metal layer and above the hinge vias;
depositing a second photoresist spacer layer above the capping layer;
using a developer solution to pattern a mirror via opening within the second photoresist spacer layer, wherein the capping layer at a bottom of the mirror via opening prevents the developer solution from touching the hinge metal layer;
removing the capping layer exposed at the bottom of the mirror via opening to expose the hinge metal layer at the bottom of the mirror via opening;
depositing a mirror metal within the mirror via opening and above the second photoresist spacer layer to form a mirror and mirror via, wherein the mirror metal contacts the hinge metal layer at a bottom of the mirror via;
removing the first and second photoresist spacer layers and capping layer using an oxygen ash to release the hinge and the mirror.
2. The method of claim 1 , wherein the capping layer is conformal.
3. The method of claim 1 , wherein the capping layer is sacrificial.
4. The method of claim 1 , wherein the thickness of the capping layer is 100 to 500 Angstroms.
5. The method of claim 1 , wherein the capping layer comprises a dielectric.
6. The method of claim 1 , wherein the capping layer comprises a chemical vapor deposited carbon material.
7. The method of claim 1 , wherein the capping layer comprises a silicon oxynitride material.
8. The method of claim 1 , wherein the capping layer is removed using an O 2 and CF 4 ash process.
9. A method of fabricating a digital micromirror device, comprising:
depositing a first photoresist spacer layer above a substrate, the first photoresist spacer layer comprising a photoresist;
patterning hinge via openings within the first photoresist spacer layer;
depositing a hinge metal layer above the first photoresist spacer layer and within the hinge via openings to form a hinge and hinge vias;
depositing a capping layer above the hinge metal layer, wherein the capping layer comprises a chemical vapor deposited carbon material;
depositing a second photoresist spacer layer above the capping layer, the second photoresist spacer layer comprising photoresist;
patterning a mirror via opening within the second photoresist spacer layer to expose the capping layer, wherein the patterning step uses a developer solution, and wherein the capping layer prevents the developer solution from contacting the hinge metal layer;
removing the capping layer within the mirror via opening using a plasma etch process after the patterning step, to expose the hinge metal layer within the mirror via opening;
depositing a mirror metal within the mirror via opening and above the second photoresist spacer layer to form a mirror and mirror via, wherein the mirror metal contacts the hinge metal layer at a bottom of the mirror via;
removing the first and second photoresist spacer layers and capping layer using an oxygen ash to release the hinge and the mirror.
10. The method of claim 9 , wherein the capping layer is conformal.
11. The method of claim 9 , wherein the capping layer is sacrificial.
12. The method of claim 9 , wherein the thickness of the capping layer is approximately 100 to 500 Angstroms.
13. The method of claim 9 , wherein the capping layer is removed using an O 2 and CF 4 ash process.