Patent ID: 8883536

Claim:
A method for fabricating a pressure sensor, the method comprising: forming a stress isolation member in contact with a substrate, wherein the stress isolation member and the substrate have a channel formed through the substrate and the stress isolation member; fabricating a first sensor die, the first sensor die having a first recessed portion to form a first diaphragm having sensing circuitry formed on a circuitry side of the first sensor die opposite the recessed portion; fabricating a second sensor die, the second sensor die having a second recessed portion to form a second diaphragm, wherein a center post extends from the second diaphragm into the recessed portion; bonding the first sensor die to the second sensor die to form a two layer die stack, such that the sensing circuitry is within the second recessed portion and the center post contacts the circuitry side of the first sensor die; mounting the two layer die stack to the stress isolation member, wherein the first recessed portion is exposed to the channel; securing the stress isolation member, the substrate, and the two layer die stack in a housing having a high side input port and a low side input port, wherein the channel is positioned in the housing such that a low pressure media entering the low side input port also enters the channel and a high pressure media entering the high side input port exerts a direct force on the second diaphragm; applying a low side atomic layer deposition to low side surfaces of the substrate, the stress isolation member, and the two layer die stack, wherein the low side surfaces are exposed to the low side input port and applying a high side atomic layer deposition to high side surfaces of the stress isolation member and the two layer die stack, wherein the high side surfaces are exposed to the high side input port; and electrically connecting the sensing circuitry to an external system.