CMOS ultrasonic transducers and related apparatus and methods
First Claim
Patent Images
1. A method, comprising:
- forming a cavity in a first wafer above an integrated circuit in the first wafer, wherein forming the cavity comprises etching an upper surface of the first wafer down to an etch stop layer of the first wafer;
directly bonding the first wafer and a second wafer to seal the cavity of the first wafer with the second wafer to form a sealed cavity, wherein the second wafer defines an SOI wafer including a buried insulator layer; and
forming an ultrasonic transducer membrane from the second wafer, wherein forming the ultrasonic transducer membrane from the second wafer comprises thinning a backside of the second wafer distal the cavity, and wherein thinning the backside of the second wafer comprises etching a base silicon layer of the second wafer until reaching the buried insulator layer.
2 Assignments
0 Petitions
Accused Products
Abstract
CMOS Ultrasonic Transducers and processes for making such devices are described. The processes may include forming cavities on a first wafer and bonding the first wafer to a second wafer. The second wafer may be processed to form a membrane for the cavities. Electrical access to the cavities may be provided.
180 Citations
14 Claims
-
1. A method, comprising:
-
forming a cavity in a first wafer above an integrated circuit in the first wafer, wherein forming the cavity comprises etching an upper surface of the first wafer down to an etch stop layer of the first wafer; directly bonding the first wafer and a second wafer to seal the cavity of the first wafer with the second wafer to form a sealed cavity, wherein the second wafer defines an SOI wafer including a buried insulator layer; and forming an ultrasonic transducer membrane from the second wafer, wherein forming the ultrasonic transducer membrane from the second wafer comprises thinning a backside of the second wafer distal the cavity, and wherein thinning the backside of the second wafer comprises etching a base silicon layer of the second wafer until reaching the buried insulator layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
-
-
9. A method, comprising:
-
forming a cavity in a first wafer above an integrated circuit in the first wafer, wherein forming the cavity comprises etching an upper surface of the first wafer down to an etch stop layer of the first wafer; directly bonding the first wafer and a second wafer to seal the cavity of the first wafer with the second wafer to form a sealed cavity, wherein the second wafer comprises a layer of polysilicon proximate the cavity of the first wafer, a layer of silicon, and an insulator between the layer of polysilicon and the layer of silicon; and forming an ultrasonic transducer membrane from the second wafer, wherein forming the ultrasonic transducer membrane from the second wafer comprises thinning a backside of the second wafer distal the cavity, and wherein thinning the backside of the second wafer comprises etching the layer of silicon until reaching the insulator. - View Dependent Claims (10, 11)
-
-
12. A method, comprising:
-
forming a cavity in a first wafer above an integrated circuit in the first wafer, wherein forming the cavity comprises etching an upper surface of the first wafer down to an etch stop layer of the first wafer; directly bonding the first wafer and a second wafer to seal the cavity of the first wafer with the second wafer to form a sealed cavity, wherein the second wafer comprises a layer of amorphous silicon proximate the cavity of the first wafer, a layer of silicon, and an insulator between the layer of amorphous silicon and the layer of silicon; and forming an ultrasonic transducer membrane from the second wafer, wherein forming the ultrasonic transducer membrane from the second wafer comprises thinning a backside of the second wafer distal the cavity, wherein thinning the backside of the second wafer comprises etching the layer of silicon until the insulator is reached. - View Dependent Claims (13)
-
-
14. A method, comprising:
-
forming a cavity in a first wafer above an integrated circuit in the first wafer, wherein forming the cavity comprises etching an upper surface of the first wafer down to an etch stop layer of the first wafer; directly bonding the first wafer and a second wafer to seal the cavity of the first wafer with the second wafer to form a sealed cavity; and forming an ultrasonic transducer membrane from the second wafer, further comprising forming an oxide layer on the etched first wafer prior to the bonding such that the bonding results in a silicon-to-oxide bond between the first and second wafers.
-
Specification