Method of manufacturing a MEMS DVC device
The present invention generally relates to a MEMS DVC having a shielding electrode structure between the RF electrode and one or more other electrodes that cause a plate to move. The shielding electrode structure may be grounded and, in essence, block or shield the RF electrode from the one or more electrodes that cause the plate to move. By shielding the RF electrode, coupling of the RF electrode to the one or more electrodes that cause the plate to move is reduced and capacitance modulation is reduced or even eliminated.
1. A method of manufacturing a micro-electromechanical system (MEMS) digital variable capacitor (DVC), the method comprising:
depositing an electrically conductive layer over a first dielectric layer;
patterning the electrically conductive layer to form a first electrode, an RF electrode, a ground electrode and a shielding electrode, wherein the shielding electrode is disposed adjacent the RF electrode and the first electrode, wherein the shielding electrode is grounded;
depositing a second dielectric layer over a substrate, the first electrode, the RF electrode, the ground electrode and the shielding electrode;
planarizing the second dielectric layer to expose the first electrode, the RF electrode, the ground electrode and the shielding electrode;
depositing a third dielectric layer over the exposed first electrode, the RF electrode, the ground electrode, the shielding electrode, and the second dielectric layer;
forming a moving electrode above the third dielectric layer;
forming a fourth dielectric layer over the moving electrode; and
forming a second electrode over the fourth dielectric layer, wherein the second electrode is disposed opposite the first electrode, wherein the moving electrode is movable from a first position in contact with the third dielectric layer and a second position in contact with the fourth dielectric layer.
2. The method of claim 1 , further comprising, prior to depositing the electrically conductive layer, forming a first via hole in the substrate and forming a first shielding via in the first via.
3. The method of claim 2 , wherein the first shielding via is coupled to the shielding electrode.
4. The method of claim 3 , further comprising, prior to forming the first via hole, forming an underneath shielding electrode in the substrate.
5. The method of claim 4 , wherein the underneath shielding electrode is coupled to the first shielding via.
6. The method of claim 5 , wherein the underneath shielding electrode is coupled to the ground electrode.
7. The method of claim 6 , further comprising forming a second via hole in the substrate to expose the underneath electrode and depositing an electrically conductive material within the second via hole to form a second shielding via, wherein the ground electrode is coupled to the second shielding via.
8. The method of claim 2 , further comprising, prior to forming the first via hole, forming an underneath shielding electrode in the substrate.
9. The method of claim 8 , wherein the underneath shielding electrode is coupled to the first shielding via.
10. The method of claim 9 , wherein the underneath shielding electrode is coupled to the ground electrode.
11. The method of claim 10 , further comprising forming a second via hole in the substrate to expose the underneath electrode and depositing an electrically conductive material within the second via hole to form a second shielding via, wherein the ground electrode is coupled to the second shielding via.