Abstract: The presently disclosed technology provides a method for forming a structure wherein an electrode, such as a gate, comprising a refractory metal is deposited. The method comprises depositing a plurality of electron sensitive resist layers on the substrate. Several of the resist layers used have properties that allow them to maintain their shape when exposed to the temperatures needed to deposit refractory metals. Using electron beam lithography, several regions are defined in the resist layers that will be removed to create a mold for a gate. By using resist layers which maintain their shape when exposed to the temperatures needed for evaporating a refractory metal, the mold defined in the resist layers will maintain its shape, thereby allowing a gate having a mushroom shape to be formed.

Abstract: The benefits of strained semiconductors are combined with silicon-on-insulator approaches to substrate and device fabrication.

Abstract: An integrated Schottky diode and method of manufacture of such a diode is disclosed. In a first aspect, a Schottky diode comprises a semiconductor substrate. The semiconductor substrate includes an epitaxial layer (EPI) on the substrate region. The diode includes a plurality of guard rings in the EPI layer and a plurality of oxidized slots. Finally, the diode includes metal within the plurality of slots to form a Buried Power Buss. A portion of the metal is completely oxide isolated from the other elements of the diode. In a second aspect, a method for manufacturing a Schottky diode comprises providing a substrate region, A buried N+ region providing an epitaxial (EPI) layer. The method also includes providing a plurality of guard rings in the EPI layer and providing a plurality of slots in the semiconductor substrate that is in contact with the EPI layer and the substrate region.

Abstract: Alternate methods of forming low resistance “hatted” polysilicon gate elements are provided that increase the effective area in the polysilicon gate for silicide grain growth during silicide formation. The expanded top portion helps to prevent silicide agglomeration in the silicide regions, thereby maintaining or reducing electrode resistance, improving high-frequency performance, and reducing gate delay in sub micron FET ULSI devices, without increasing the underlying active channel length.

Abstract: A nitride semiconductor substrate including (a) a supporting substrate, (b) a first nitride semiconductor layer having a periodical T-shaped cross-section, having grown from periodically arranged stripe-like, grid-like or island-like portions on the supporting substrate, and (c) a second nitride semiconductor substrate covering said supporting substrate, having grown from the top and side surfaces of said first nitride semiconductor layer, wherein a cavity is formed under the second nitride semiconductor layer. A protective layer having a periodically arranged stripe-like, grid-like or island-like apertures is formed on the supporting substrate. The first nitride semiconductor layer is laterally grown from the exposed portion of the substrate. The growth is stopped before the first nitride semiconductor layer covers the supporting substrate. Thus, the first nitride semiconductor layer has a periodical T-shaped cross-section.

Abstract: A gate electrode is formed in the following manner. A first resist layer having a first opening is formed on a semiconductor substrate. A second resist layer having a second opening larger than the first opening is formed on the first resist layer. A first conductor layer containing a high-melting-point metal is formed. Subsequently, a second conductor layer containing low-resistance metal is formed, and then the first conductor layer within the second opening is removed by etching. Next, the second resist layer is removed by a lift-off process, and finally the first resist layer is removed by ashing.

Abstract: The presently disclosed technology provides a method for forming a structure wherein an electrode, such as a gate, comprising a refractory metal is deposited. The method comprises depositing a plurality of electron sensitive resist layers on the substrate. Several of the resist layers used have properties that allow them to maintain their shape when exposed to the temperatures needed to deposit refractory metals. Using electron beam lithography, several regions are defined in the resist layers that will be removed to create a mold for a gate. By using resist layers which maintain their shape when exposed to the temperatures needed for evaporating a refractory metal, the mold defined in the resist layers will maintain its shape, thereby allowing a gate having a mushroom shape to be formed.

Abstract: A method for making a semiconductor device includes forming a resist pattern having a multi-layered structure by performing a plurality of development steps, the resist pattern including a first opening corresponding to a fine gate section of a gate electrode and a second opening placed on the first opening, the second opening corresponding to an over-gate section which is wider than the fine gate section and having a cross section protruding over an undercut in an underlying layer, wherein every angle of the second opening at the tip of the over-gate section is more than 90 degrees; and forming the gate electrode provided with the fine gate section and the over-gate section by depositing electrode materials on the resist pattern.

Abstract: A method of forming a gate structure includes forming sequentially a pad layer and a first photoresist layer over a substrate. A cross-linked surface layer is formed on the surface of the first photoresist layer, followed by rounding the profile of the first photoresist layer, and removing the exposed pad layer to expose the substrate. A second photoresist layer is formed over the first photoresist layer, wherein a portion of the first photoresist layer and the exposed substrate are exposed by the second photoresist layer. Thereafter, a conductive layer is formed, wherein the conductive layer formed on the second photoresist layer is separated from the conductive layer formed on the first photoresist layer and the exposed substrate. The first and the second photoresist layers are removed while the conductive layer on the second photoresist layer is concurrently being striped. The remaining conductive layer serves as a gate structure.

Abstract: A method of fabricating a semiconductor transistor device comprises the steps as follows. Provide a semiconductor substrate with a gate dielectric layer thereover and a lower gate electrode structure formed over the gate dielectric layer with the lower gate electrode structure having a lower gate top. Form a planarizing layer over the gate dielectric layer leaving the gate top of the lower gate electrode structure exposed. Form an upper gate structure over the lower gate electrode structure to form a T-shaped gate electrode with an exposed lower surface of the upper gate surface and exposed vertical sidewalls of the gate electrode. Remove the planarizing layer. Form source/drain extensions in the substrate protected from the short channel effect. Form sidewall spacers adjacent to the exposed lower surface of the upper gate and the exposed vertical sidewalls of the T-shaped gate electrode. Form source/drain regions in the substrate.

Abstract: The cross-sectional area of polysilicon lines is increased by selectively epitaxially growing an upper portion of the polysilicon line in the presence of a dielectric layer exposing the upper portion. Thus, a substantially T-shaped line is obtained, allowing a minimum bottom-CD while insuring a sufficient high conductivity.

Abstract: An edge of a passivation film is positioned inside an edge of an overhanging emitter structure by a distance L so that a base electrode layer is formed at an interval not to overlap the edge of the passivation film even when the base electrode layer is formed by etching with the emitter structure as a mask.

Abstract: A method for making a semiconductor device includes forming a resist pattern having a multi-layered structure by performing a plurality of development steps, the resist pattern including a first opening corresponding to a fine gate section of a gate electrode and a second opening placed on the first opening, the second opening corresponding to an over-gate section which is wider than the fine gate section and having a cross section protruding like an overhang, wherein every angle of the second opening at the tip of the over-gate section is more than 90 degrees; and forming the gate electrode provided with the fine gate section and the over-gate section by depositing electrode materials on the resist pattern.

Abstract: A nitride semiconductor substrate including (a) a supporting substrate, (b) a first nitride semiconductor layer having a periodical T-shaped cross-section, having grown from periodically arranged stripe-like, grid-like or island-like portions on the supporting substrate, and (c) a second nitride semiconductor substrate covering said supporting substrate, having grown from the top and side surfaces of said first nitride semiconductor layer, wherein a cavity is formed under the second nitride semiconductor layer. A protective layer having a periodically arranged stripe-like, grid-like or island-like apertures is formed on the supporting substrate. The first nitride semiconductor layer is laterally grown from the exposed portion of the substrate. The growth is stopped before the first nitride semiconductor layer covers the supporting substrate. Thus, the first nitride semiconductor layer has a periodical T-shaped cross-section.

Abstract: A gate electrode is formed in the following manner. A first resist layer having a first opening is formed on a semiconductor substrate. A second resist layer having a second opening larger than the first opening is formed on the first resist layer. A first conductor layer containing a high-melting-point metal is formed. Subsequently, a second conductor layer containing low-resistance metal is formed, and then the first conductor layer within the second opening is removed by etching. Next, the second resist layer is removed by a lift-off process, and finally the first resist layer is removed by ashing.

Abstract: A method of fabricating a semiconductor device includes the steps of forming an insulation film on a compound semiconductor layer, forming an opening in the insulation film so as to expose a part of the compound semiconductor layer, forming a gate electrode of a refractory metal compound on the insulation film such that the gate electrode contacts with the compound semiconductor layer at the contact hole, and removing the insulation film by a wet etching process, wherein the wet etching process is conducted by an etchant to which both of the gate electrode and the compound semiconductor layer show a resistance.

Abstract: This invention has an objective to provide a field effect transistor semiconductor which has great adhesiveness between a gate metal and an insulating film defining a gate electrode end and to improve production yield thereof.

Abstract: A method of fabricating a transistor using silicon on lattice matched insulator. A first monocrystalline silicon layer is provided and a first layer of dielectric is epitaxially deposited over the first silicon layer substantially lattice matched with the first silicon layer and substantially monocrystalline. A first electrically conductive gate electrode is epitaxially formed over the first layer of dielectric substantially lattice matched with the first layer of dielectric. A second layer of dielectric is epitaxially deposited conformally over the first gate electrode and exposed portions of first layer of dielectric substantially lattice matched with the first silicon layer and substantially monocrystalline. A second monocrystalline silicon layer is epitaxially deposited over the second layer of dielectric and a third layer of dielectric is epitaxially deposited over the second silicon layer substantially lattice matched with the first silicon layer and substantially monocrystalline.

Abstract: A gate-controlled device includes an inverted-T gate which overlaps lightly doped, shallow extension regions formed in an underlying base layer. Spacers are included on the sides of the gate, and source/drain regions are formed in the base layer in non-overlapping relationship with the gate layer. This device outperforms conventional devices in terms of performance. Lower external resistance is achieved by forming a gate-controlled inversion channel over at least a portion of the shallow LDD extensions, and by making the shallow LDD extensions graded (or sloped) towards the deep source/drain regions. Also, forming portions of the gate underneath the spacers, electrical gate control of the shallow LDD junctions is made possible. This advantageously reduces the series resistance of the device and increases drive current, both of which translate into improved device performance with no increase in gate-to-source/drain parasitic capacitance.

Abstract: A process of simultaneously forming a plurality of metal features on a substrate, in which at least one metal feature has undercut sides and at least one metal feature does not have undercut sides involves the application of a lower photoresist feature having rounded sides and an upper photoresist feature having undercut sides wherein the upper photoresist feature is positioned in offset relation to the lower photoresist feature such that one edge of the upper photoresist feature does not extend over the corresponding edge of the lower photoresist feature and the other edge of the upper photoresist feature does extend beyond the corresponding edge of the lower photoresist feature.

Abstract: A method of forming a fully depleted semiconductor-on-insulator (SOI) field effect transistor (FET). The method includes forming a T-shaped gate electrode formed at least in part in a recess formed in a layer of semiconductor material and over a body region that is disposed between a source and a drain. The method includes spacing the gate electrode from the body by a gate dielectric made from a high-K material.

Abstract: An integrated circuit includes a transistor with a T-shaped gate conductor. The T-shaped gate conductor can achieve a lower sheet resistance characteristic. The transistor can include a silicided source region, a silicided drain region, and a gate structure having the T-shaped gate conductor. The T-shaped gate conductor has a silicided top portion. The silicided top portion can have different silicidation characteristics than the silicided source region and the silicided drain region.

Abstract: A gate-controlled device includes an inverted-T gate which overlaps lightly doped, shallow extension regions formed in an underlying base layer. Spacers are included on the sides of the gate, and source/drain regions are formed in the base layer in non-overlapping relationship with the gate layer. This device outperforms conventional devices in terms of performance. Lower external resistance is achieved by forming a gate-controlled inversion channel over at least a portion of the shallow LDD extensions, and by making the shallow LDD extensions graded (or sloped) towards the deep source/drain regions. Also, forming portions of the gate underneath the spacers, electrical gate control of the shallow LDD junctions is made possible. This advantageously reduces the series resistance of the device and increases drive current, both of which translate into improved device performance with no increase in gate-to-source/drain parasitic capacitance.

Abstract: A field effect transistor includes a semiconductor substrate with a channel layer being formed on its surface, a source electrode and a drain electrode formed at a distance on said semiconductor substrate, and a gate electrode placed between the source electrode and the drain electrode and making a Schottky junction with the channel layer. The gate electrode is provided with an overhanging field plate section and between the field plate section and the channel layer, there is laid a dielectric film. When the relative permittivity and the film thickness of the dielectric film are denoted by ∈ and t (nm), respectively, the following condition is satisfied 5≦∈<8, and 100<t<350.

Abstract: For fabricating a field effect transistor on a semiconductor substrate in SOI (semiconductor on insulator) technology, a pillar of semiconductor material is formed on a layer of buried insulating material. The pillar has a top surface and first and second side surfaces, and the pillar has a width, a length, and a height. A masking structure is formed on a center portion of the top surface of the pillar along the length of the pillar. A top portion of the height of the pillar is etched from exposed surfaces of the top surface of the pillar down to a bottom portion of the height of the pillar to form an upside down T-shape for the pillar. A gate dielectric material is deposited on any exposed surface of the semiconductor material of the pillar for a gate length along the length of the pillar. A gate electrode material is deposited on the gate dielectric material to surround the pillar for the gate length of the pillar.

Abstract: A field effect transistor device has a semiconductor substrate having a predetermined impurity concentration of a first conductivity type. Inpurity layers of a second conductivity type are formed spaced apart at the main surface of the semiconductor substrate. The impurity layers make up source/drain regions. A region between the impurity layers defines a channel region. A notch-shaped conductive layer is formed on the channel region. The notch-shaped conductive layer has an upper layer section longer than a lower layer section. The upper and lower layer sections are formed of at least two different materials, one being silicon-germanium layer with varying germanium content. The material of the lower layer section can be etched at a greater rate than the material of the upper layer section during a common etching process.

Abstract: A method for fabricating a T-gate structure is provided. The method comprises the steps of providing a silicon layer having a gate oxide layer, a protection layer over the gate oxide layer, a first sacrificial layer over the protection layer and a second sacrificial layer over the first sacrificial layer. A photoresist layer is formed over the second sacrificial layer. An opening is formed in the photoresist layer. An opening is then formed in the second sacrificial layer beneath the opening in the photoresist layer. The opening is then expanded in the photoresist layer to expose portions of the top surface of the second sacrificial layer around the opening in the second sacrificial layer. The opening is extended in the second sacrificial layer through the first sacrificial layer and the opening is expanded in the second sacrificial layer to form a T-shaped opening in the first and second sacrificial layers. The photoresist layer is removed and the T-shaped opening is filled with a conductive material.

Abstract: The impurity concentration contained in a layer on an electron supply layer of a high electron mobility field effect transistor is set in the range of 1˜1016 to 1˜1017 atoms/cm3, or the bandgap of a Schottky layer is set wider than that of the electron supply layer. Otherwise, in the steps of manufacturing the high electron mobility field effect transistor, after a silicon nitride film has been formed on a GaAs buried layer in which a second recess is formed and in a region on the inside of a first recess formed in a GaAs contact layer, the GaAs buried layer is still heated.

Abstract: A comb-shape MESFET has a gate electrode having a plurality of gate fingers coupled to a gate bar at the proximal ends of the gate fingers. The distal end of each gate finger is formed as a large width end on the inactive region of the wafer. The large width end prevents peel-off of the gate finger from the semiconductor layer, thereby improving reliability of the structure of the comb-shape MESFET.

Abstract: A metal line of a semiconductor device and method of fabricating the same are provided in which the metal line deterioration due to electromigration is minimized to improve its reliability.

Abstract: Methods for forming a T-gate on a substrate are provided that employ a hybrid resist. The hybrid resist specifically is employed to define a base of the T-gate on the substrate with very high resolution. To define a base of the T-gate, a hybrid resist layer is deposited on the substrate. A mask having a reticle feature with an edge is provided and is positioned above the hybrid resist layer so that the edge of the reticle feature is above a desired location for the base of the T-gate. Thereafter, the hybrid resist layer is exposed to radiation through the mask, and the exposed hybrid resist layer is developed to define an opening therein for the base of the T-gate. Preferably the loop feature formed in the hybrid resist layer by the reticle feature during exposure is trimmed. The T-gate may be completed by employing any known T-gate fabrication techniques.

Abstract: In a semiconductor device, a gate electrode is formed by sequentially forming a Schottky metal film, a barrier metal film, and a low-resistance metal film from the lower side. The Schottky metal film or barrier metal film has a gap in a lower gate vertical portion. The gap is closed at its upper and lower portions. The overlaying low-resistance metal film does not extend into the lower gate vertical portion. A method for this semiconductor device is also disclosed.

Abstract: A method for forming a transistor is formed where a gate electrode of the transistor is formed over a substrate defining a gate channel portion of the substrate. A mask is also formed over the substrate, a portion of the mask extending over a first portion of the substrate adjacent to the gate channel portion of the substrate. The mask defines a second portion of the substrate adjacent to the first portion of the substrate. An ion beam is directed toward the substrate to form a drain or a source region of said transistor adjacent to the gate channel portion of the substrate, the source or drain region including the first and second portions of the substrate. The ion beam implants the second portion of the substrate with a first implantation characteristic.

Abstract: There is formed, so as to cover the upper structure (a gold-containing, low-resistance metal layer) of a T- or Y-shaped gate, a thin film (e.g. a thin TiN film) which is not reactive to the low-resistance metal layer, which is resistant to an etching solution to be applied in a later wet etching step, and which has good adhesivity to a resist to be coated in a later step, to prevent the direct contact of the low-resistance metal layer with the resist. In this state, supports are formed.

Abstract: A method for depositing metal lines for semiconductor devices, in accordance with the present invention includes the step of providing a semiconductor wafer including a dielectric layer formed on the wafer. The dielectric layer has vias formed therein. The wafer is placed in a deposition chamber wherein the wafer has a first temperature achieved without preheating. A metal is deposited on the wafer which fills the vias wherein the metal depositing is initiated at a substantially same time as heating the wafer from the first temperature.

Abstract: A new method is provided for the integration of the of T-top gate process. Active regions are defined and bounded by STI's on the surface of a substrate. The pad oxide is removed from the substrate and replaced by a layer of SAC oxide. A thin layer of nitride is deposited that covers the surface of the created layer of SAC oxide and the surface of the STI regions. A layer of TEOS is deposited and etched defining the regions where the gate electrodes need to be formed. Gate spacers are next formed on the sidewalls of the openings that have been created in the layer of TEOS. The required implants (such as channel implant and threshold implant) are performed, the gate structure is then grown in the openings that have been created in the layer of TEOS. After the gate structure has been completed, the surface of the created structure is polished and the remaining layer of TEOS is removed. Source and drain regions implants can now be performed, LDD regions are implanted using a tilted implant.

Abstract: In a semiconductor device, a gate electrode is formed by sequentially forming a Schottky metal film, a barrier metal film, and a low-resistance metal film from the lower side. The Schottky metal film or barrier metal film has a gap in a lower gate vertical portion. The gap is closed at its upper and lower portions. The overlayering low-resistance metal film does not extend into the lower gate vertical portion. A method for this semiconductor device is also disclosed.

Abstract: A method for fabricating a T-gate structure is provided. A structure is provided that has a silicon layer having a gate oxide layer, a protection layer over the gate oxide layer and a sacrificial layer over the protection layer. An opening is then formed in the sacrificial layer. A contact material is deposited over the sacrificial layer filling the opening with the contact material and forming a contact layer. Portions of the contact material outside a gate region are then removed. Finally, the sacrificial layer and portions of the protection layer and the gate oxide layer not forming a part of the T-gate structure are removed.

Abstract: A silicon-rectifier integral with either an NMOS transistor or a PMOS transistor (together which constitute an output buffer) is disclosed. If integral with the NMOS transistor, the silicon-controlled rectifier is provided with the emitter and base of the NPN bipolar junction transistor acting as the source and bulk of the NMOS transistor. On the other hand, if integral with the PMOS transistor, the silicon-controlled rectifier is provided with the emitter and base of the PNP bipolar junction transistor acting as the source and bulk of the PMOS transistor.

Abstract: A high electron mobility transistor includes a channel layer for developing therein an electron gas layer having a substantially uniform electron gas density, and upper and lower high-resistance wide-band gap layers disposed respective over and beneath the channel layer, each of the upper and lower high-resistance wide-band gap layers having a silicon-doped planar layer disposed therein. A contact layer is disposed on the upper wide-band gap layer for contact with source and drain electrodes, the contact layer having a recess defined therein which divides the contact tact layer. A gate electrode of substantially T-shaped cross section is disposed in the recess, and a passivation film is disposed on an inner wall surface of the recess and a lower leg portion of the gate electrode, exposing an upper head portion of the gate electrode.

Abstract: A microwave monolithic integrated circuit comprises a T-shaped gate electrode including a Schottky gate electrode formed on a first region of a compound semiconductor substrate, a pair of ohmic electrodes making an ohmic contact with a surface of the substrate in the first region at respective sides of the T-shaped gate electrode, a lower capacitor electrode pattern formed on a second region of the compound semiconductor substrate with a composition substantially identical with a low-resistance, top electrode constituting the T-shaped gate electrode on the Schottky gate electrode, a dielectric film formed on the lower electrode pattern, and an upper electrode pattern formed on the dielectric film.

Abstract: By providing an area where an Au film 28b is removed and a Ti film 28a is exposed along the plane tangent to the side where the p-n junction of a semiconductor chip is exposed, sticking of the Au film 28b to the chip side or protruding of the film as a flash from the side is prevented, which normally provides a starting place for creep of a solder 42 on the chip side, which in turn causes p-n junction short-circuiting when dividing of chips.

Abstract: A method for fabricating a T-gate structure is provided. A structure is provided that has a silicon layer having a gate oxide layer, a polysilicon layer over the gate oxide layer and an insulating layer over the gate oxide layer. An opening is formed extending partially into the insulating layer. The opening in the insulating layer extends from a top surface of the insulating layer to a first depth. Spacers are then formed on the sides of the opening. The opening is then extended in the insulating layer from the first depth to a second depth. The opening is wider from the top surface of the insulating layer to the first depth than the opening is from the first depth to the second depth. The spacers are then removed from the opening. The opening is then filled with a conductive material to form a T-gate structure.

Abstract: A method of forming a gate electrode of a compound semiconductor device includes forming a first insulating film pattern having a first aperture, forming a second insulating film pattern having a second aperture consisting of inverse V-type on the first insulating film pattern, forming a T-type gate electrode by depositing a conductivity film on the entire structure, removing a second insulating film pattern, forming a insulating spacer on a pole sidewall by etching a first insulating film pattern, and forming an ohmic electrode of the source and drain by self-aligning method using T-type gate electrode as a mask. Thereby T-type gate electrode of materials such as refractory metals can be prevented to be deteriorate because of high annealing, as well as it is stably formed, by using an insulating film. Ohmic metal and gate electrodes formed by self-aligning method can be prevented an interconnection by forming an insulating film spacer between these electrodes.

Abstract: A first resist film for EB exposure, a buffer film, and a second resist film for i-line exposure are applied sequentially onto a substrate. Thereafter, the second resist film and the buffer film are subjected to patterning for forming a first opening. Then, dry etching is performed with respect to the first resist film masked with the second resist film to transfer the pattern of the second resist film to the first resist film and thereby form a second opening in the first resist film. Subsequently, a third resist film of chemically amplified type is applied to the entire surface of the first resist film to form a mixing layer in conjunction with the first resist film. As a result, the wall faces of the second opening are covered with the mixing layer and the width of the second opening is thereby reduced.

Abstract: An improved method of fabricating a flash memory cell is disclosed. A tunnel oxide film is formed on active regions. A first conductive film and a protective film are sequentially formed on the tunnel oxide film. The protective film on the isolation film is selectively etched, thus forming a protective film pattern on the tunnel oxide film. A sacrificial conductive film is formed on the resultant structure. The sacrificial conductive film and the first conductive film pattern are over-etched until the sidewalls and the upper surface of the protective film pattern are exposed, thereby exposing the center of the isolation film and simultaneously forming a first conductive film pattern having sloped sidewalls. With the present invention, an electrical field is prevented from being concentrated in an area between a control gate electrode and a floating gate because the floating gate have a sloped sidewall profile instead of sharp edges.

Abstract: The specification describes a photolithography process using multiple exposures to form z-dimension patterns. Multiple exposures at different thickness levels are made using photomasks aligned with a latent image of alignment marks formed during the first exposure. The latent image is visible to the alignment system of commercial steppers.

Abstract: A method for making improved MOSFET structures is achieved. A Si.sub.3 N.sub.4 and a SiO.sub.2 layer are deposited and patterned to have openings for gate electrodes over device areas on a substrate. A second Si.sub.3 N.sub.4 layer is deposited and etched back to form arc-shaped sidewall spacers in the openings. An anti-punchthrough implant and a gate oxide are formed in the openings between the Si.sub.3 N.sub.4 sidewall spacers. A polysilicon layer is deposited and polished back to form gate electrodes. The SiO.sub.2 and the Si.sub.3 N.sub.4 layers, including the sidewall spacers, are removed to form free-standing gate electrodes that increase in width with height, and having arc-shaped sidewalls. An implant through the edges of the arc-shaped gate electrodes results in lightly doped source/drains that are graded both in junction depth and dopant concentration to reduce hot electron effects. A second SiO.sub.

Abstract: A method for fabricating a field effect transistor (FET) with a T-like gate structure includes forming a silicon nitride layer over a silicon substrate and patterning it to form an opening that exposes the substrate. A dielectric layer is formed on a lower portion of each side-wall of the opening so that the opening has a T-like free space. A doped polysilicon layer fills the T-like free space through only one deposition. After performing a planarization on the doped polysilicon layer, a titanium metal layer is formed over the substrate. A self-aligned titanium silicide is formed over the substrate other than the dielectric layer surface through a rapid thermal process (RTP). A selective etching process is performed to remove the remaining titanium metal layer. After removing the dielectric layer a RTP is performed again to reform the crystal structure of the titanium silicide layer so as to reduce its resistance. A T-like gate structure is formed.

Abstract: A lower resist film, which is made of PMMA for EB exposure and has a thickness of about 200 nm, is applied onto a substrate, and then an upper resist film to be exposed to i-rays is applied on the lower resist film. Thereafter, a mixed layer, in which the upper and lower resist films are mixed, is formed in the interface between the upper and lower resist films. Next, the upper resist film, except for the head-forming region thereof, is exposed to i-rays and developed, thereby forming an upper-layer opening. And then the mixed layer and a leg-forming region of the lower resist film are exposed to EB and developed, thereby forming a lower-layer opening having an upper part like a taper progressively expanding upward.