Techniques are disclosed herein for creating metal bitlines (BLs) in stacked wafer memory. Using techniques described herein, metal BLs are created on a bottom surface of a wafer. The metal BLs can be created using different processes. In some configurations, a salicide process is utilized. In other configurations, a damascene process is utilized. Using metal reduces the resistance of the BLs as compared to using non-metal diffused BLs. In some configurations, wafers are stacked and bonded together to form three-dimensional memory structures.

A semiconductor device includes a buried power rail (BPR) over a substrate and a semiconductor structure over the BPR. The semiconductor structure is tube-shaped and extends along a vertical direction. The semiconductor structure includes a first source/drain (S/D) region over the BPR, a gate region over the first S/D region, and a second S/D region over the gate region. The semiconductor device includes a first S/D interconnect structure extending from the BPR and further into the semiconductor structure such that a top portion of the first S/D interconnect structure is surrounded by the first S/D region. The semiconductor device includes a gate structure that includes (i) a gate oxide formed along an inner surface of the gate region and (ii) a gate electrode formed along sidewalls of the gate oxide in the gate region. The semiconductor device includes a second S/D interconnect structure positioned over the second S/D region.

Structures and methods are disclosed in which a layer stack can be formed with a plurality of layers of a metal, where each of the layers of metal can be separated by a layer of a dielectric. An opening in the layer stack can be formed such that a semiconductor layer beneath the plurality of layers of the metal is uncovered. One or more vertical channel structures can be formed within the opening by epitaxial growth. The vertical channel structure can include a vertically oriented transistor. The vertical channel structure can include an interface of a silicide metal with a first metal layer of the plurality of metal layers. The interface can correspond to one of a source or a drain connection of a transistor. The silicide metal can be annealed above a temperature threshold to form a silicide interface between the vertical channel structure and the first metal layer.

Some embodiments include an assembly having pillars of semiconductor material arranged in rows extending along a first direction. The rows include spacing regions between the pillars. The rows are spaced from one another by gap regions. Two conductive structures are within each of the gap regions and are spaced apart from one another by a separating region. The separating region has a floor section with an undulating surface that extends across semiconductor segments and insulative segments. The semiconductor segments have upper surfaces which are above upper surfaces of the insulative segments; Transistors include channel regions within the pillars of semiconductor material, and include gates within the conductive structures. Some embodiments include methods for forming integrated circuitry.

A semiconductor device includes substrate, a first gate structure, a second gate structure, and an epitaxy layer. The first gate structure and the second gate structure are over the substrate, in which the first gate structure and the second gate structure each comprises a shielding electrode, a gate electrode over the shielding electrode, and a first gate dielectric layer vertically separating the shielding electrode from the gate electrode. The epitaxy layer is over the substrate and cups an underside of the first gate structure and the second gate structure, in which the epitaxy layer comprises a doped region laterally between the first gate dielectric layer of the first gate structure and the first gate dielectric layer of the second gate structure, a dopant concentration of the doped region being non-uniform along a lateral direction.

Techniques are disclosed herein for creating metal bitlines (BLs) in stacked wafer memory. Using techniques described herein, metal BLs are created on a bottom surface of a wafer. The metal BLs can be created using different processes. In some configurations, a salicide process is utilized. In other configurations, a damascene process is utilized. Using metal reduces the resistance of the BLs as compared to using non-metal diffused BLs. In some configurations, wafers are stacked and bonded together to form three-dimensional memory structures.

Methods and systems for power semiconductor devices integrating multiple trench transistors on a single chip. Multiple power transistors (or active regions) are paralleled, but one transistor has a lower threshold voltage. This reduces the voltage drop when the transistor is forward-biased. In an alternative embodiment, the power device with lower threshold voltage is simply connected as a depletion diode, to thereby shunt the body diodes of the active transistors, without affecting turn-on and ON-state behavior.

A method is presented for forming a semiconductor structure. The method includes forming a plurality of fins over a source/drain region, forming a first spacer within troughs defined by the plurality of fins and depositing a high-k dielectric layer, a work function material layer, and a conducting layer. The method further includes etching the high-k dielectric layer, the work function material layer, and the conducting layer to form recesses between the plurality of fins, depositing a liner dielectric, and etching portions of the liner dielectric to form a plurality of second spacers having a U-shaped configuration. The method further includes forming an epitaxial layer over the plurality of fins such that a gap region is defined between the plurality of second spacers and the epitaxial layer.

A semiconductor device having a vertical drain extended MOS transistor may be formed by forming deep trench structures to define vertical drift regions of the transistor, so that each vertical drift region is bounded on at least two opposite sides by the deep trench structures. The deep trench structures are spaced so as to form RESURF regions for the drift region. Trench gates are formed in trenches in the substrate over the vertical drift regions. The body regions are located in the substrate over the vertical drift regions.

A method includes depositing a sacrificial layer on a first dielectric layer over a substrate; applying a first patterning process, a second patterning process, a third patterning process to the sacrificial layer to form a first group of openings, a second group of openings and a third group of openings, respectively, in the sacrificial layer, wherein three first openings from three different patterning processes form a first side, a second side and a first angle between the first side and the second side, and three second openings from the three different patterning processes form a third side, a fourth side and a second angle between the third side and the fourth side, wherein the first angle is approximately equal to the second angle and forming nanowires based on the first group of openings, the second group of openings and the third group of openings.