A method of forming field effect transistors (FETs) and on Integrated Circuit (IC) chips with the FETs. Channel placeholders at FET locations are undercut at each end of FET channels. Source/drain regions adjacent to each channel placeholder extend into and fill the undercut. The channel placeholder is opened to expose channel surface under each channel placeholder. Source/drain extensions are formed under each channel placeholder, adjacent to each source/drain region. After removing the channel placeholders metal gates are formed over each said FET channel.

A method for fabricating a gate stack of a semiconductor device comprises forming a first dielectric layer over a channel region of the device, forming a first nitride layer over the first dielectric layer, depositing a scavenging layer on the first nitride layer, forming a capping layer over the scavenging layer, removing portions of the capping layer and the scavenging layer to expose a portion of the first nitride layer in a n-type field effect transistor (nFET) region of the gate stack, forming a first gate metal layer over the first nitride layer and the capping layer, depositing a second nitride layer on the first gate metal layer, and depositing a gate electrode material on the second nitride layer.

A p-type field effect transistor includes a pair of spacers over a substrate top surface. The p-type field effect transistor includes a channel recess cavity in the substrate top surface between the pair of spacers. The p-type field effect transistor includes a gate stack with a bottom portion in the channel recess cavity. The p-type field effect transistor includes a source/drain (S/D) recess cavity including a bottom surface and sidewalls below the substrate top surface, wherein the S/D recess cavity includes a portion extending below the gate stack. The p-type field effect transistor includes a strained material filling the S/D recess cavity. The p-type field effect transistor further includes a source/drain (S/D) extension substantially conformably surrounding the bottom surface and sidewalls of the S/D recess cavity. The S/D extension includes a portion between the gate stack and the S/D recess cavity.

A silicon-containing nucleation layer can be employed to provide a self-aligned template for selective deposition of tungsten within backside recesses during formation of a three-dimensional memory device. The silicon-containing nucleation layer may remain as a silicon layer, converted into a tungsten silicide layer, or replaced with a tungsten nucleation layer. Tungsten deposition can proceed only on the surface of the silicon-containing nucleation layer or a layer derived therefrom in a subsequent tungsten deposition process.

A method for fabricating floating body memory cells (FBCs), and the resultant FBCs where gates favoring different conductivity type regions are used is described. In one embodiment, a p type back gate with a thicker insulation is used with a thinner insulated n type front gate. Processing, which compensates for misalignment, which allows the different oxide and gate materials to be fabricated is described.

A dual gate CMOS structure including a semiconductor substrate; a first channel structure including a first semiconductor material and a second channel structure including a second semiconductor material on the substrate. The first semiconductor material including Si.sub.xGe.sub.1-x where x=0 to 1 and the second semiconductor material including a group III-V compound material. A first gate stack on the first channel structure includes: a first native oxide layer as an interface control layer, the first native oxide layer comprising an oxide of the first semiconductor material; a first high-k dielectric layer; a first metal gate layer. A second gate stack on the second channel structure includes a second high-k dielectric layer; a second metal gate layer. The interface between the second channel structure and the second high-k dielectric layer is free of any native oxides of the second semiconductor material.

A semiconductor device includes a gate disposed over a substrate; a source region and a drain region on opposing sides of the gate; and a pair of trench contacts over and abutting an interfacial layer portion of at least one of the source region and the drain region; wherein the interfacial layer includes boron in an amount in a range from about 510.sup.21 to about 510.sup.22 atoms/cm.sup.2.

A semiconductor device includes a gate disposed over a substrate; a source region and a drain region on opposing sides of the gate; and a pair of trench contacts over and abutting an interfacial layer portion of at least one of the source region and the drain region; wherein the interfacial layer includes boron in an amount in a range from about 510.sup.21 to about 510.sup.22 atoms/cm.sup.2.

A structure includes a substrate and a tunnel field effect transistor (TFET). The TFET includes a source region disposed in the substrate having an overlying source contact, the source region containing first semiconductor material having a first doping type; a drain region disposed in the substrate having an overlying drain contact, the drain region containing second semiconductor material having a second, opposite doping type; and a gate structure that overlies a channel region between the source and the drain. The source region and the drain region are asymmetric with respect to one another such that one contains a larger volume of semiconductor material than the other one. A method is disclosed to fabricate a plurality of the TFETs using a plurality of spaced apart mandrels having spacers. A pair of the mandrels and the associated spacers is processed to form four adjacent TFETs without requiring intervening lithographic processes.

A semiconductor device includes a substrate including a first active region, a second active region and a field region between the first and second active regions, and a gate structure formed on the substrate to cross the first active region, the second active region and the field region. The gate structure includes a p type metal gate electrode and an n-type metal gate electrode directly contacting each other, the p-type metal gate electrode extends from the first active region less than half way toward the second active region.