Method of manufacturing a mechanical resonating structure
Methods are described for constructing a mechanical resonating structure by applying an active layer on a surface of a compensating structure. The compensating structure comprises one or more materials having an adaptive resistance to deform that reduces a variance in a resonating frequency of the mechanical resonating structure, wherein at least the active layer and the compensating structure form a mechanical resonating structure having a plurality of layers of materials A thickness of each of the plurality of layers of materials results in a plurality of thickness ratios therebetween.
1. A method of fabricating a mechanical resonating structure characterized by a resonance frequency (f 0 ) and a zero temperature coefficient of frequency (T 0 ), the method comprising:
applying an active layer on a compensating structure, wherein the compensating structure comprises one or more materials having an adaptive stiffness that reduces variation of the resonance frequency (f 0 );
applying a sacrificial layer on a surface of the active layer such that a portion of the active layer and a portion of the sacrificial layer are exposed, the sacrificial layer being a material different than the active layer; and
subsequent to applying the sacrificial layer, adjusting a thickness of the portion of the sacrificial layer to tune a value of f 0 and a value of T 0 .
2. The method of claim 1 , wherein the sacrificial layer is a conductor, wherein a configuration of the conductor causes a resonance mode of operation of the mechanical resonating structure to be influenced more by a lateral displacement than by a thickness displacement.
3. The method of claim 1 , further comprising adjusting a thickness of the active layer.
4. The method of claim 3 , wherein the compensating structure comprises first, second and third layers, wherein the second layer is formed between the first and third layers, wherein the first and third layers are formed of silicon dioxide, and wherein the second layer is formed of silicon.
5. The method of claim 1 , further comprising forming a conductor on a surface of the compensating structure prior to applying the active layer.
6. The method of claim 1 , wherein applying the sacrificial layer comprises applying the sacrificial layer in a configuration such that the portion of the active layer and the portion of the sacrificial layer are in a side-by-side configuration.
7. A method of fabricating a mechanical resonating structure characterized by a resonance frequency (f 0 ) and a zero temperature coefficient of frequency (T 0 ), the method comprising:
obtaining a mechanical resonating structure comprising an active layer and a compensating structure, wherein the compensating structure comprises one or more materials having an adaptive stiffness that reduces variation of the resonance frequency (f 0 );
patterning a trimming layer on the active layer; and
adjusting a thickness of the trimming layer to selectively tune a value of f 0 and a value of T 0 .
8. The method of claim 7 , wherein the trimming layer is a conductor, wherein a configuration of the conductor causes a resonance mode of operation of the mechanical resonating structure to be influenced more by a lateral displacement than by a thickness displacement.
9. The method of claim 7 , further comprising adjusting a thickness of an exposed portion of the active layer.
10. The method of claim 9 , wherein the compensating structure comprises first, second and third layers, wherein the second layer is formed between the first and third layers, wherein the first and third layers comprise silicon dioxide and the second layer comprises silicon.
11. The method of claim 7 , wherein patterning the trimming layer comprises patterning the trimming layer to be side-by-side with an exposed portion of the active layer.
12. The method of claim 7 , wherein patterning the trimming layer comprises patterning the trimming layer to have a greater surface area than an exposed portion of the active layer.
13. The method of claim 7 , wherein the trimming layer is an electrode layer, and wherein patterning the trimming layer comprises patterning the trimming layer to form an interdigital transducer.