Top-via etch technique for forming dielectric membranes
First Claim
1. A method of fabricating a film bulk acoustic resonator comprising the steps of:
- a) depositing a membrane layer on an upper planar surface of a substrate;
b) forming a film bulk acoustic resonator on the membrane layer;
c) depositing a photoresist etch mask on the membrane layer and the film bulk acoustic resonator;
d) opening respective first and second vias through the membrane layer and the photoresist etch mask at respective first and second ends of the film bulk acoustic resonator to expose the substrate;
e) isotropically etching the substrate through the first and second vias to form air gaps under the membrane layer along the first and second ends of the film bulk acoustic resonator; and
f) removing the photoresist etch mask.
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Abstract
A top-via etch technique for forming dielectric membranes for thin film devices, the dielectric membrane being deposited on the upper planar surface of the substrate. After the thin film device is formed on the dielectric membrane, a photoresist etch mask is deposited on the entire upper planar surface of the substrate, including the thin film structure. Vias are formed through the dielectric membrane and the protective photoresist etch mask to expose the upper planar surface of the substrate along opposite first and second ends of the thin film device. The upper planar surface of the substrate is isotropically etched using a reactive ion etching technique for example, to form air gaps beneath the dielectric membrane. The etching process may be carried out in etch segments of predetermined intervals, each followed by a cool down period of a prescribed interval.
214 Citations
21 Claims
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1. A method of fabricating a film bulk acoustic resonator comprising the steps of:
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a) depositing a membrane layer on an upper planar surface of a substrate; b) forming a film bulk acoustic resonator on the membrane layer; c) depositing a photoresist etch mask on the membrane layer and the film bulk acoustic resonator; d) opening respective first and second vias through the membrane layer and the photoresist etch mask at respective first and second ends of the film bulk acoustic resonator to expose the substrate; e) isotropically etching the substrate through the first and second vias to form air gaps under the membrane layer along the first and second ends of the film bulk acoustic resonator; and f) removing the photoresist etch mask. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of forming air gaps under a dielectric membrane, the dielectric membrane being deposited on an upper planar surface of a substrate and having a thin film device integrated thereon, the method comprising the steps of:
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a) depositing a photoresist layer on the dielectric membrane and the thin film device; b) forming respective first and second vias through the dielectric membrane and the photoresist layer at respective first and second ends of the thin film device to expose the substrate; c) isotropically etching the substrate through the first and second vias to form air gaps under the dielectric membrane along the first and second ends of the thin film device; and d) removing the photoresist layer. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21)
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Specification