BioFET device having a metal crown structure as a sensing layer disposed on an oxide layer formed under a channel region of a transistor

A biological field-effect transistor (BioFET) device, comprising:

• a substrate comprising a semiconductor layer;
• a first dielectric layer disposed on a front side of the semiconductor layer;
• a conductive line disposed in the first dielectric layer;
• a second dielectric layer comprising a silicon oxide layer disposed on a back side of the semiconductor layer, wherein the second dielectric layer extends into the semiconductor layer and into the first dielectric layer and is in contact with the conductive line;
• and
• an array of transistors, wherein each transistor of the array of transistors comprises:
• a gate structure disposed on the front side of the semiconductor layer and
• a channel region disposed between and in contact with vertical inner sidewalls of source and drain regions that are disposed within the semiconductor layer, wherein the source and drain regions are in contact with a bottom surface of the second dielectric layer;
• a first doped region disposed between a first portion of the semiconductor layer and a vertical outer sidewall of the source region;
• a second doped region disposed between a second portion of the semiconductor layer and a vertical outer sidewall of the drain region, wherein the first and second doped regions comprise dopants of a conductivity type that is different from dopants in the source and drain regions;
• an interface layer comprising a metal oxide layer disposed within an opening of the second dielectric layer, wherein the interface layer is in contact with the source and drain regions;
• and
• a metal crown structure disposed on top and side surfaces of the second dielectric layer and disposed directly on the interface layer, wherein the metal crown structure of a first transistor of the array of transistors comprises a first metal and the metal crown structure of a second transistor of the array of transistors comprises a second metal that is different from the first metal.

A biological field-effect transistor (BioFET) device, comprising:

• a substrate comprising a semiconductor layer;
• a multi-layer interconnect (MLI) structure disposed on a front side of the semiconductor layer and comprising an inter-metal dielectric layer and a conductive line;
• an oxide layer disposed on a back side of the semiconductor layer, wherein the oxide layer extends into the semiconductor layer and into the inter-metal dielectric layer and is in contact with the conductive line;
• a gate structure disposed on the front side of the semiconductor layer;
• source and drain regions disposed in the semiconductor layer;
• a first doped region disposed between a first portion of the semiconductor layer and the source region;
• a second doped region disposed between a second portion of the semiconductor layer and the drain region, wherein the first and second doped regions comprise dopants of a conductivity type that is different from dopants in the source and drain regions;
• a channel region disposed in the semiconductor layer, wherein the oxide layer comprises an opening aligned with the channel region,
• wherein the source region comprises a first vertical inner sidewall in contact with the channel region and a first vertical outer sidewall in contact with the first doped region, and
• wherein the drain region comprises a second vertical inner sidewall in contact with the channel region and a second vertical outer sidewall in contact with the second doped region;
• and
• a conductive layer comprising a composite layer of a ruthenium oxide layer and a tungsten nitride layer disposed on the oxide layer.