Surface acoustic wave sensor device formed on a quartz substrate

Abstract

An acoustic wave sensor device comprises a quartz material layer comprising a planar surface, a first interdigitated transducer formed over the planar surface of the quartz material layer, a first reflection structure formed over the planar surface of the quartz material layer, a second reflection structure formed over the planar surface of the quartz material layer, a first resonance cavity formed between the first interdigitated transducer and the first reflection structure and a second resonance cavity formed between the first interdigitated transducer and the second reflection structure. The planar surface of the quartz material layer is defined by a crystal cut of a quartz material of the quartz material layer with angles φ in the range of −14° to −24°, θ in the range of −25° to −45° and ψ in the range of +8° to +28°.

1 . Acoustic wave sensor device, comprising:
 a quartz material layer comprising a planar surface;   a first interdigitated transducer formed over the planar surface of the quartz material layer;   a first reflection structure formed over the planar surface of the quartz material layer;   a second reflection structure formed over the planar surface of the quartz material layer;   a first resonance cavity formed between the first interdigitated transducer and the first reflection structure; and   a second resonance cavity formed between the first interdigitated transducer and the second reflection structure; and   wherein the planar surface of the quartz material layer is defined by a crystal cut of a quartz material of the quartz material layer with angle φ in a range of −14° to −24°, angle θ in a range of −25° to −45° and angle ψ in a range of +8° to +28°.   
     
     
         2 . The acoustic wave sensor device of  claim 1 , wherein the quartz material layer is a quartz bulk quartz substrate. 
     
     
         3 . The acoustic wave sensor device of  claim 1 , further comprising a bulk substrate, and wherein the quartz material layer is formed over the bulk substrate. 
     
     
         4 . The acoustic wave sensor device of  claim 1 , wherein at least one of the first and second reflection structures comprises or consists of a Bragg mirror. 
     
     
         5 . The acoustic wave sensor device of  claim 1 , wherein at least one of the first and second reflection structures comprises a groove or an edge reflection structure or a short reflector comprising not more than three electrodes. 
     
     
         6 . The acoustic wave sensor device of  claim 1 , wherein an upper surface of the second resonance cavity comprises a physical and/or chemical modification as compared to an upper surface of the first resonance cavity. 
     
     
         7 . The acoustic wave sensor device of  claim 6 , wherein the physical and/or chemical modification comprises a metallization layer or passivation layer formed on the upper surface of the second resonance cavity. 
     
     
         8 . The acoustic wave sensor device of  claim 1 , wherein extensions lengths of the first resonance cavity and the second resonance cavity differ from each other. 
     
     
         9 . The acoustic wave sensor device of  claim 1 , wherein the first interdigitated transducer is split into two parts, the device further comprising a third reflection structure positioned between the two parts of the first interdigitated transducer. 
     
     
         10 . The acoustic wave sensor device of  claim 9 , wherein the third reflection structure is a Bragg mirror. 
     
     
         11 . The acoustic wave sensor device of  claim 9 , wherein a length of one of the two parts of the first interdigitated transducer differs from a length of the other one of the two parts and/or an aperture of one of the two parts of the first interdigitated transducer differs from an aperture of the other one of the two parts of the first interdigitated transducer. 
     
     
         12 . The acoustic wave sensor device of  claim 1 , wherein the first resonance cavity comprises first resonance sub-cavities separated from each other by first reflection sub-structures of the first reflection structure and the second resonance cavity comprises second resonance sub-cavities separated from each other by second reflection sub-structures of the second reflection structure. 
     
     
         13 . The acoustic wave sensor device of  claim 1 , wherein the acoustic wave sensor device is a passive surface acoustic wave sensor device configured for sensing an ambient parameter selected from one of a temperature, chemical species, strain, pressure or torque of a rotating axis. 
     
     
         14 . The acoustic wave sensor device of  claim 3 , wherein the bulk substrate comprises a Si bulk substrate or a sapphire bulk substrate. 
     
     
         15 . The acoustic wave sensor device of  claim 4 , wherein at least one of the first and second reflection structures comprises a groove or an edge reflection structure or a short reflector comprising not more than three electrodes. 
     
     
         16 . The acoustic wave sensor device of  claim 15 , wherein an upper surface of the second resonance cavity comprises a physical and/or chemical modification as compared to an upper surface of the first resonance cavity. 
     
     
         17 . The acoustic wave sensor device of  claim 16 , wherein the physical and/or chemical modification comprises a metallization layer or passivation layer formed on the upper surface of the second resonance cavity. 
     
     
         18 . The acoustic wave sensor device of  claim 17 , wherein extensions lengths of the first resonance cavity and the second resonance cavity differ from each other. 
     
     
         19 . The acoustic wave sensor device of  claim 18 , wherein the first interdigitated transducer is split into two parts, the device further comprising a third reflection structure positioned between the two parts of the first interdigitated transducer. 
     
     
         20 . The acoustic wave sensor device of  claim 18 , wherein the first resonance cavity comprises first resonance sub-cavities separated from each other by first reflection sub-structures of the first reflection structure and the second resonance cavity comprises second resonance sub-cavities separated from each other by second reflection sub-structures of the second reflection structure.