Method of making thermally-isolated silicon-based integrated circuits

Patent metadata

Field	Value
Publication number	US-9824932-B1
Application number	US-201615234932-A
Country	US
Kind code	B1
Filing date	Aug 11, 2016
Priority date	Aug 5, 2013
Publication date	Nov 21, 2017
Grant date	Nov 21, 2017

Abstract

Thermally isolated devices may be formed by performing a series of etches on a silicon-based substrate. As a result of the series of etches, silicon material may be removed from underneath a region of an integrated circuit (IC). The removal of the silicon material from underneath the IC forms a gap between remaining substrate and the integrated circuit, though the integrated circuit remains connected to the substrate via a support bar arrangement that suspends the integrated circuit over the substrate. The creation of this gap functions to release the device from the substrate and create a thermally-isolated integrated circuit.

First claim

What is claimed is:

1. A method of fabricating a thermally isolated integrated circuit and resonator combination, the method comprising the steps of:
a) providing a silicon-based substrate;
b) fabricating at least one integrated circuit comprising a portion of the silicon-based substrate, the at least one integrated circuit comprising an interlevel dielectric layer formed over the silicon-based substrate;
c) forming a silicon release layer on a top surface of the interlevel dielectric layer at a location over the at least one integrated circuit;
d) depositing an isolation layer over a remaining, exposed surface of the interlevel dielectric layer and the silicon release layer;
e) depositing a conductive layer over a structure resulting from step d) and patterning the conductive layer to create a lower electrode;
f) depositing a piezoelectric layer over a structure resulting from step e),
g) depositing a conductive layer over a structure resulting from step f) and patterning the conductive layer to create an upper electrode;
h) patterning a top surface of a structure resulting from step g), wherein the patterning of step h) is performed so as to define (i) a resonator formed by the lower electrode, piezoelectric layer and the upper electrode, (ii) boundaries around at least one region to be thermally isolated and (iii) a support bar region to be further processed to provide a support bar;
i) etching piezoelectric material exposed by the patterning in step h), the etching terminating upon exposure of portions of the silicon release layer, then removing exposed portions of the silicon release layer;
j) etching a structure resulting from step i) to remove exposed regions of the interlevel dielectric layer and a buried oxide insulating layer, exposing the silicon-based substrate; and
k) etching a structure resulting from step j) to remove any remainder of the silicon release layer to isolate the resonator from the silicon-based substrate, the etching also removing a portion of the exposed silicon-based substrate sufficient to release the integrated circuit from the silicon-based substrate, with the support bar maintaining physical contact between the integrated circuit and the silicon-based substrate, creating a suspended structure.

2. The method as in claim 1 , wherein in performing step f) a layer of aluminum nitride is deposited.

3. The method as in claim 1 , wherein in performing step c) an amorphous silicon layer is deposited.

4. The method as in claim 1 , wherein in performing steps e) and g), aluminum contact layers are deposited.

5. The method as in claim 1 , wherein in performing step a), a silicon-on-insulator (SOI) substrate is provided.

Assignees

• Sandia Corp
• Nat Tech & Eng Solutions Sandia Llc

Inventors

• Wojciechowski Kenneth
• Olsson Roy
• Clews Peggy J
• Bauer Todd

Classifications

• H10P50/642

  Chemical etching · CPC title

• H10P50/283

  by chemical means · CPC title

• H10P50/00

  Etching of wafers, substrates or parts of devices · CPC title

• H10P14/69391

  the material containing aluminium, e.g. Al2O3 · CPC title

• H10P14/3454

  Amorphous · CPC title