Method and structure of wafer level encapsulation of integrated circuits with cavity
The present invention is related shielding integrated devices using CMOS fabrication techniques to form an encapsulation with cavity. The integrated circuits are completed first using standard IC processes. A wafer-level hermetic encapsulation is applied to form a cavity above the sensitive portion of the circuits using IC-foundry compatible processes. The encapsulation and cavity provide a hermetic inert environment that shields the sensitive circuits from EM interference, noise, moisture, gas, and corrosion from the outside environment.
1. A packaged integrated circuit device comprising:
a semiconductor substrate having a surface region, a first portion and a second portion;
one or more CMOS integrated circuit devices fabricated on a first portion of the semiconductor substrate;
one or more sensitive integrated circuit modules provided on a second portion of the semiconductor substrate;
a seal ring formed encircling the one or more sensitive integrated circuit modules;
one or more dielectric layers overlying the one or more CMOS integrated circuit devices and the one or more sensitive integrated circuit modules to form a passivation structure overlying the one or more CMOS integrated circuit devices and the one or more sensitive integrated circuit modules;
a void volume overlying the one or more dielectric layers within a vicinity of at least the one or more sensitive integrated circuit modules; and
a barrier material overlying at least the void volume to hermitically seal the one or more sensitive integrated circuit modules while maintaining the void volume overlying the one or more dielectric layers, the barrier material being electrically coupled with the seal ring to shield the one or more sensitive integrated circuit modules.
2. The device of claim 1 further comprising one or more dielectric layers overlying the barrier material.
3. The device of claim 1 wherein the barrier material is selected from a group consisting of: amorphous silicon, polysilicon, silicon germanium, and germanium.
4. The device of claim 1 wherein the barrier material is selected from a group consisting of: tungsten, platinum, titanium, titanium nitride, titanium tungsten, copper, tantalum, aluminum, or aluminum titanium alloy.
5. The device of claim 1 wherein the barrier material is selected from a group consisting of: an oxide, a nitride, oxynitride, spin-on glass, or spray-on glass.
6. The device of claim 1 wherein the barrier material comprises a semiconductor, a metal, or a dielectric.
7. The device of claim 1 wherein the void volume comprises air.
8. The device of claim 1 wherein the void volume comprises an inert material.
9. The device of claim 1 wherein the void volume comprises an inert gas.
10. The device of claim 1 wherein the void volume is characterized as a vacuum environment.
11. The device of claim 1 wherein the void volume is characterized by a dielectric constant of 1.2 and less.
12. The device of claim 1 wherein the one or more sensitive integrated circuit modules comprises an RC timing circuit, LC timing circuit, RF circuit, or analog circuit.