Methods of depositing piezoelectric films
View Patent ↗This invention relates to methods of depositing piezoelectric films such as in part of a stack including depositing a piezoelectric layer, measuring the thickness of the layer and depositing a further film or films such that the combined thickness is substantially equal to the target thickness.
1. A method of depositing a stack of layers of a target thickness to provide a predetermined resonant frequency including depositing a piezoelectric layer, performing in situ a measurement of the thickness of the layer and depositing a further film or films such that the combined thickness of the stack is substantially equal to the target thickness.
2. A method as claimed in claim 1 wherein the film is the same material as the layer.
3. A method as claimed in claim 2 wherein the film is deposited in the same chamber as the layer.
4. A method as claimed in claim 1 wherein a further film is an electrode.
5. A method as claimed in claim 1 wherein the film is a different material to the layer.
6. A method as claimed in claim 5 wherein the film is an electrically conducting material.
7. A method as claimed in claim 6 wherein the film is at least part of a conducting electrode.
8. A method as claimed in claim 1 wherein the layer is optically transparent.
9. A method as claimed in claim 8 wherein the layer is AIN.
10. A method as claimed in claim 8 wherein the thickness is measured optically.
11. A method as claimed in claim 1 wherein the stack extends across at least part of a workpiece and the measuring step takes place at multiple points to allow the target thickness to be achieved substantially across the part of the workpiece.
12. A method of depositing a stack of layers of a target thickness to provide a resonant frequency including depositing an optically transparent piezoelectric layer and performing in situ an optical measurement of the thickness of the layer and depositing a further film or films such that the construed thickness of the stack is substantially equal to the target thickness.
13. A method as claimed in claim 12 wherein the film is the same material as the layer.
14. A method of forming a resonator having a predetermined resonator frequency including depositing an electrode, depositing a piezoelectric layer using the method as claimed in any one of the preceding claims and depositing a further electrode if one has not been deposited in a preceding step.
15. A method of depositing a piezoelectric layer as part of a resonant structure of predetermined resonant frequency, including depositing a layer of piezoelectric material having a thickness of less than a target thickness, performing in situ a measurement of the thickness of the deposited layer and depositing a film on the layer such that the thickness of the resonant structure including the film and the layer is substantially equal to the target thickness.