Abstract: A CMOS semiconductor device having shallow source/drain junctions is formed by ion implanting antimony to form lightly doped source/drain regions of an N-channel transistor, thereby reducing channeling for a shallower projected junction depth as compared to conventional N-type impurity implantations. Upon growing a thermal oxide screen layer to protect the substrate from subsequent ion implantations, the implanted antimony experiences oxidation-retarded diffusion, further reducing the projected junction depth. After ion implanting N-type impurities to form moderately or heavily doped source/drain regions and activation annealing, the resulting semiconductor device exhibits the desirably shallow LDD junctions.

Abstract: A semiconductor device is provided with a gate electrode having a substantially rectangular profile by depositing a layer of amorphous or microcrystalline silicon. The amorphous or microcrystalline silicon is doped with impurities, before patterning to form the gate electrode, to reduce gate depletion. The doped gate electrode layer is then patterned to form a gate electrode having a substantially rectangular profile.

Abstract: Halo implant regions are formed in a P-channel semiconductor device employing a zero degree tilt angle. N-type impurities are ion implanted to the desired depth in the semiconductor substrate prior to forming P-channel lightly doped source/drain areas. Subsequently, moderately or heavily doped source/drain regions are formed, followed by activation annealing. The halo implants diffuse to form halo structures at the desired location, thereby reducing short channel effects, such as subsurface punchthrough. Other embodiments enable independent control of the junction depths and channel lengths of N- and P-channel transistors, while maintaining high manufacturing throughput.

Abstract: A silicon on insulator (SOI) wafer is formed with an unoxidized perforation in the insulating silicon dioxide buried oxide layer. A field effect transistor (FET) structure on the SOI wafer is located above the unoxidized perforation such that the unoxidized perforation provides for electrical coupling between the channel region of the FET with the bulk silicon substrate to eliminate the floating body effect caused by charge accumulation in the channel regions due to historical operation of the FET. The method of forming the FET includes masking a silicon wafer prior to an oxygen implantation process to form the unoxidized perforated buried oxide layer in the wafer.

Abstract: A method for fabricating a semiconductor device having asymmetric source-drain extension regions includes the formation of a conformal layer of spacer forming material over a gate electrode. Nitrogen atoms are directionally introduced into the sidewall spacer material to form nitrogenated regions within the sidewall spacer material. The gate electrode casts a shadow over a portion of the sidewall spacer material adjacent to an edge of the gate electrode that is opposite from the direction of introduction of the nitrogen atoms. The shadow region of the sidewall spacer material remains free of nitrogen atoms. The shadow region of the sidewall spacer material is converted into a sidewall spacer by isotropically etching away the nitrogenated regions, while not substantially etching the shadow region. The asymmetrically formed sidewall spacer can then be used to mask a portion of the substrate adjacent to the drain edge of the gate electrode.

Abstract: A process in accordance with the invention enables the manufacturability of raised source-drain MOSFETs. In accordance with the invention, a raised source-drain material, having a window therein, is formed over the substrate. A gate oxide and window sidewall oxides are subsequently formed. Dopants are diffused into the substrate. A gate is formed within the window.

Abstract: A method of making a lightly doped drain transistor includes the steps of forming a gate electrode (52) and a gate oxide (54) over a semiconductor substrate (56) and forming a drain (70) in a drain region (58) and a source (72) in a source region (60) of the substrate (56). The method further includes generating interstitials (62) near a lateral edge of at least one of the drain (70) and the source (72) and thermally treating the substrate (56). The thermal treatment cause the interstitials (62) to enhance a lateral diffusion (84) of the drain (70) under the gate oxide (54) without substantially impacting a vertical diffusion (82) of the drain (70) or the source (72). The enhanced lateral diffusion (84) results in the formation of at least one of a lightly doped drain extension region (75) and a lightly doped source extension region (76) without an increase in a junction depth of the drain (70) or the source (72).

Abstract: A process in accordance with the invention minimizes the number of heat steps to which an source-drain extension region is exposed, thus minimizing source-drain extension region diffusion and allowing more precise control of source-drain extension region thickness over conventional processes. In accordance with the invention, spacers are formed abutting the gate and then heavily doped source and drain regions are formed. The gate and source and drain regions are silicided. The spacers are subsequently removed and source-drain extension regions are then formed. In one embodiment of the invention, a laser doping process is used to form the source-drain extension regions.

Abstract: Shallow LDD junctions are obtained by depositing a thin screening oxide layer prior to moderate or heavy ion implantations. The use of a thin deposited screening oxide, as by plasma enhanced chemical vapor deposition, instead of a thermally grown oxide, minimizes transient enhanced diffusion during annealing to activate the source/drain regions, thereby decreasing the junction depth.

Abstract: N-channel and P-channel transistor performances are separately optimized by activating the source/drain regions of the N-channel transistor before forming the P-channel lightly doped implant. Separate sidewall spacers for the moderately or heavily doped implants of the N- and P-channel transistors are employed. Embodiments enable independent control of the junction depths and channel lengths of N- and P-channel transistors.

Abstract: The etch profile of side surfaces of a gate electrode is improved by heat treating the gate electrode layer after nitrogen implantation and before etching to form the gate electrode. Nitrogen implantation at high dosages to prevent subsequent impurity penetration through the gate dielectric layer, e.g., B penetration, amorphizes the upper portion of the gate electrode layer resulting in concave side surfaces upon etching to form the gate electrode. Heat treatment performed after nitrogen implantation can restore sufficient crystallinity so that, after etching the gate electrode layer, the side surfaces of the resulting gate electrode are substantially parallel.

Abstract: N- and P-channel transistor characteristics are independently optimized for CMOS semiconductor devices with design features of 0.25 microns and under. Removable second sidewall spacers are formed on the N-channel transistor gate electrode having first sidewall spacers thereon. Ion implantation is conducted to form N-type moderately/heavily doped implants followed by activation annealing. The second sidewall spacer is then removed from the P-channel transistor leaving first sidewall spacers thereon serving as an ion implantation mask for the P-type lightly doped implants. Subsequently, third sidewall spacers are formed on the P-channel gate electrode having first sidewall spacers thereon followed by ion implantation to form the P-type moderately or heavily doped implants, with subsequent activation annealing. Embodiments enable complete independent control of the channel lengths of the N- and P-channel transistors by varying the width of the first, second and third sidewall spacers.

Abstract: The present invention is directed to a metal oxide semiconductor transistor having a fully overlapped lightly doped drain (LDD) structure which offers the advantages of conventional fully overlapped LDD transistors but which significantly reduces the drain-to-gate overlap capacitance associate therewith. To achieve fully overlapped LDD construction and reduced drain-to-gate overlap capacitance, the metal oxide semiconductor transistor of the present invention employs a gate electrode comprising a main gate region formed from heavily doped polysilicon and depleted sidewall polysilicon spacers formed from undoped or depleted polysilicon. In the MOS transistor of the present invention, the lightly doped regions are fully overlapped by the combination of the depleted sidewall polysilicon spacers and the main gate region.