Embedded High-Density Trench Capacitors for Smart Catheters

Abstract

Our work presents embedded high-density oxidenitride-oxide (ONO) trench capacitors for power supply decoupling in the next generation of smart catheters. These millimeter-scale smart catheters are using a novel integration platform, Flex-to-Rigid (F2R). In the F2R platform, various functional modules are fabricated or assembled on thin silicon islands. They are connected by flexible interconnects and can be folded into arbitrary shapes to facilitate small form-factor integration. Trench decoupling capacitors have the advantage of being integrated into the thin silicon islands of F2R to reduce the parasitic inductances and space consumption. Additionally, their small surface openings can be closed by layer deposition to enable follow-up processes on the closed-up surface. For demonstration, high aspect ratio (1.1:25 and 1.2:30) ONO trench capacitors with total areas of 300x300 µm 2 and 1000x1000 µm 2 are fabricated on planar wafers, and a 700 nm and a 1 µm thick plasma-enhanced chemical vapor deposition (PECVD) SiO2 layers are deposited to test the trench closing process. The F2R compatible ONO trench capacitors have capacitance densities of 6.17 nF/mm 2 and 10.12 nF/mm 2 , combined with breakdown voltages ranging from 28 to 30 V.

Cavity-BOX SOI: Advanced Silicon Substrate with Pre-Patterned BOX for Monolithic MEMS Fabrication

“…The advanced SOI substrate with cavities in the BOX can significantly simplify processes, such as microfabrication of highly integrated foldable devices [ 4 , 5 ] or 3-dimensional circuit integration using TSVs, in the device layer [ 12 ]. An example of the cavity-BOX application is a monolithic fabrication process of a foldable deep brain stimulation (DBS) device (see Figure 2 [ 5 ]).…”

“…Apart from electrical isolation, the BOX layer also allows for the fabrication of MEMS devices with a well-defined device layer thickness, and it can serve as a release layer in floating structures. SOI wafers are used in a wide range of applications, such as pressure sensors [ 1 ], resonators and inertial sensors [ 2 ], microchannels [ 3 ], and miniaturization of microfabricated medical devices [ 4 , 5 ].…”