Ultrasound transducer devices and methods for fabricating ultrasound transducer devices

Abstract

An ultrasound transducer device includes: a first insulating layer formed on a first integrated circuit substrate; a second insulating layer formed on the first insulating layer; a third insulating layer formed on the second insulating layer, and a second substrate bonded to the first integrated circuit. A first cavity is formed in the third insulating layer. The second substrate is bonded to the first integrated circuit such that the first cavity is sealed.

What is claimed is: 
     
         1 . An ultrasound transducer device, comprising:
 a first insulating layer formed on a first integrated circuit substrate;   a second insulating layer formed on the first insulating layer;   a third insulating layer formed on the second insulating layer, wherein a first cavity is formed in the third insulating layer; and   a second substrate bonded to the first integrated circuit substrate such that the first cavity is sealed.   
     
     
         2 . The ultrasound transducer device of  claim 1 , wherein the second insulating layer comprises aluminum oxide. 
     
     
         3 . The ultrasound transducer device of  claim 1 , wherein the third insulating layer comprises silicon oxide. 
     
     
         4 . The ultrasound transducer device of  claim 3 , wherein
 the second substrate comprises a silicon oxide layer, and   the second substrate is bonded to the first integrated circuit substrate with a silicon oxide—silicon oxide bond between the silicon oxide layer on the second substrate and the third insulating layer on the first integrated circuit substrate.   
     
     
         5 . The ultrasound transducer device of  claim 1 , further comprising a fourth insulating layer formed on the second substrate, wherein the fourth insulating layer comprises aluminum oxide. 
     
     
         6 . The ultrasound transducer device of  claim 5 , wherein
 the third insulating layer comprises silicon oxide, and   the second substrate is bonded to the first integrated circuit substrate with an aluminum oxide—silicon oxide bond between the fourth insulating layer on the second substrate and the third insulating layer on the first integrated circuit substrate.   
     
     
         7 . The ultrasound transducer device of  claim 5 , further comprising:
 a fifth insulating layer formed on the fourth insulating layer on the second substrate; and   a second cavity formed in the fifth insulating layer, wherein   the fifth insulating layer comprises silicon oxide,   the second substrate is bonded to the first integrated circuit substrate with a silicon oxide—silicon oxide bond between the fifth insulating layer on the second substrate and the third insulating layer on the first integrated circuit substrate, and   the first cavity is aligned with the second cavity.   
     
     
         8 . The ultrasound transducer device of  claim 1 , wherein the first insulating layer comprises silicon oxide. 
     
     
         9 . The ultrasound transducer device of  claim 1 , wherein the second substrate comprises a silicon-on-insulator (SOI) substrate. 
     
     
         10 . The ultrasound transducer device of  claim 1 , wherein a thickness of the second insulating layer is between approximately 0.005 microns to 0.100 microns. 
     
     
         11 . The ultrasound transducer device of  claim 1 , wherein the second insulating layer is formed using atomic layer deposition (ALD). 
     
     
         12 . The ultrasound transducer device of  claim 1 , wherein the third insulating layer is formed using atomic layer deposition (ALD). 
     
     
         13 . An ultrasound transducer device, comprising:
 an integrated circuit substrate;   an aluminum oxide layer formed on the integrated circuit substrate;   an insulating layer formed on the aluminum oxide layer;   a cavity formed in the insulating layer; and   a membrane substrate bonded to the integrated circuit substrate such that the membrane substrate seals the cavity, wherein   the membrane substrate forms a top surface of the cavity, and the aluminum oxide layer forms a bottom surface of the cavity, such that the cavity is between the membrane substrate and the aluminum oxide layer.   
     
     
         14 . The ultrasound transducer device of  claim 13 , wherein the insulating layer comprises silicon oxide. 
     
     
         15 . The ultrasound transducer device of  claim 14 , wherein
 the membrane substrate comprises a silicon oxide layer, and   the membrane substrate is bonded to the integrated circuit substrate with a silicon oxide—silicon oxide bond between the silicon oxide layer on the membrane substrate and the insulating layer on the integrated circuit substrate.   
     
     
         16 . The ultrasound transducer device of  claim 13 , wherein a thickness of the aluminum oxide layer is between approximately 0.005 microns to 0.100 microns. 
     
     
         17 . The ultrasound transducer device of  claim 13 , wherein the aluminum oxide layer is formed using atomic layer deposition (ALD). 
     
     
         18 . An ultrasound transducer device, comprising:
 a first substrate;   a first insulating layer formed on the first substrate;   a second insulating layer formed on the first insulating layer;   a cavity formed in the second insulating layer; and   a second substrate bonded to the first substrate such that the second substrate seals the cavity, wherein the second substrate comprises integrated circuitry.   
     
     
         19 . The ultrasound transducer device of  claim 18 , wherein the first insulating layer comprises aluminum oxide. 
     
     
         20 . The ultrasound transducer device of  claim 18 , wherein the second insulating layer comprises silicon oxide.