283 results about "Floating body effect" patented technology

The present invention relates to double-gate FinFET devices and fabricating methods thereof. More particularly, the invention relates to an electrically stable double-gate FinFET device and the method of fabrication in which the Fin active region on a bulk silicon substrate where device channel and the body are to be formed has a nano-size width and is connected to the substrate and is formed with the shape of a wall along the channel length direction.

The conventional double-gate MOS devices are fabricated using SOI wafers which are more expensive than bulk silicon wafers. It also has problems including the floating body effects, larger source/drain parasitic resistance, off-current increase, and deterioration in heat transfer to the substrate.

In a substrate vertical transistor cells are formed and are arranged, in a transistor cell array, row by row in an x direction and column by column in a y direction. Lower source/drain regions of the transistor cells are connected to a common connection plate. Upper source/drain regions of the transistor cells impart a contact connection for instance to a storage capacitor of a DRAM memory cell. Active trenches running between the transistor cells with word lines are formed along the x direction. The word lines form gate electrodes in sections. A potential at the gate electrode controls a conductive channel in an active region arranged in each case between the upper and the lower source/drain connection region. According to the invention, the active regions of adjacent transistor cells are sections of a contiguous layer body and are connected to one another. An accumulation of charge carriers in the active region and floating body effects are avoided without increasing the area requirement of a transistor cell.

Channel depth in a field effect transistor is limited by an intra-layer structure including a discontinuous film or layer formed within a layer or substrate of semiconductor material. Channel depth can thus be controlled much in the manner of SOI or UT-SOI technology but with less expensive substrates and greater flexibility of channel depth control while avoiding floating body effects characteristic of SOI technology. The profile or cross-sectional shape of the discontinuous film may be controlled to an ogee or staircase shape to improve short channel effects and reduce source/drain and extension resistance without increase of capacitance. Materials for the discontinuous film may also be chosen to impose stress on the transistor channel from within the substrate or layer and provide increased levels of such stress to increase carrier mobility. Carrier mobility may be increased in combination with other meritorious effects.

A magnetoresistive memory cell includes an MTJ device and a select transistor. The select transistor includes a first conduction-type semiconductor layer, a gate electrode formed by disposing a gate insulating layer on top of the semiconductor layer, and first and second diffusion regions formed in the semiconductor layer to be spaced apart from each other and to have a second conduction type. A part of the semiconductor layer between the first and second diffusion regions is formed as an electrically floating body region. By using a high-performance select transistor with a floating body effect, high integration of a magnetoresistive memory device may be achieved.

The present invention relates to a silicon-on-insulator (SOI) substrate, a method for fabricating the SOI substrate and a SOI MOSFET using the SOI substrate to easily migrate the design applied to a conventional bulk silicon substrate to the SOI design and to remove a floating body effect. The SOI substrate includes a mono-silicon substrate, a buried oxide layer formed over the surface of the mono-silicon substrate, and a thin mono-silicon layer formed over the surface of the buried oxide layer. Conductive layers are formed at through holes of the buried oxide layer positioned between the predetermined regions of the thin layer and the substrate for body contacts. Therefore, additional layout spaces are not needed for body contacts and the constant body contact resistance can allow the conventional circuit design applied to the bulk silicon substrate to be migrated to the circuit design applied to the SOI substrate without any modifications. Also, a variety of operational failures caused by the floating effect can be eliminated in the SOI substrate. As a consequence, additional effort is not required for designing or verifying the circuit of the present invention, so as to make it possible to construct a highly efficient, but low power consuming system.

By forming a strained semiconductor layer in a PMOS transistor, a corresponding compressively strained channel region may be achieved, while, on the other hand, a corresponding strain in the NMOS transistor may be relaxed. Due to the reduced junction resistance caused by the reduced band gap of silicon/germanium in the NMOS transistor, an overall performance gain is accomplished, wherein, particularly in partially depleted SOI devices, the deleterious floating body effect is also reduced, due to the increased leakage currents generated by the silicon/germanium layer in the PMOS and NMOS transistor.

A extractor implanted region is used in a silicon-on-insulator CMOS memory device. The extractor region is reversed biased to remove minority carriers from the body region of partially depleted memory cells. This causes the body region to be fully depleted without the adverse floating body effects.

The conventional flash memory device is fabricated by the MOS processing technology on a bulk substrate and has a similar configuration to an MOS device. While the conventional CMOS device has a superior scaling down characteristic, the scaling down characteristic of a flash memory device is poor due to the inability to reduce the thickness below 7 nm or 8 nm for the tunneling oxide film where the charges in the channel are tunneled into the floating electrode through the tunneling oxide. In order to resolve this problem, the present invention, instead of a SOI wafer, uses a cheaper bulk silicon wafer with lower defect density. A wall shape Fin active region where the channel and the source/drain are formed is connected to the bulk silicon substrate by which floating body effect and heat conduction problem are resolved. a flash memory device is fabricated by forming a tunneling oxide film on side surfaces of the Fin active and a floating (storage) electrode where the charges could be stored. The above structure has a superior scaling down characteristic and enhanced memory performance due to a double-gate flash memory device structure.

Provision of a body control contact adjacent a transistor and between the transistor and a contact to the substrate or well in which the transistor is formed allows connection and disconnection of the substrate of the transistor to and from a zero (ground) or substantially arbitrary low voltage in accordance with control signals applied to the gate of the transistor to cause the transistor to exhibit a variable threshold which maintains good performance at low supply voltages and reduces power consumption/dissipation which is particularly advantageous in portable electronic devices. Floating body effects (when the transistor substrate in disconnected from a voltage source in the “on” state) are avoided since the substrate is discharged when the transistor is switched to the “off” state. The transistor configuration can be employed with both n-type and p-type transistors which may be in complementary pairs.

The present invention provides a 6T-SRAM semiconducting structure including a substrate having an SOI region and a bulk-Si region, wherein the SOI region and the bulk-Si region have a same or differing crystallographic orientation; an isolation region separating the SOI region from the bulk-Si region; and at least one first device located in the SOI region and at least one second device located in the bulk-Si region. The SOI region has an silicon layer atop an insulating layer. The bulk-Si region further comprises a well region underlying the second device and a contact to the well region, wherein the contact stabilizes floating body effects. The well contact is also used to control the threshold voltages of the FETs in the bulk-Si region to optimized the power and performance of the SRAM cell built from the combination of the SOI and bulk-Si region FETs.

In an exemplary embodiment, a fin active region is protruded along one direction from a bulk silicon substrate on which a shallow trench insulator is entirely formed so as to cover the fin active region. The shallow trench insulator is removed to selectively expose an upper part and sidewall of the fin active region, along a line shape that at least one time crosses with the fin active region, thus forming a trench. The fin active region is exposed by the trench and thereon a gate insulation layer is formed. Thereby, productivity is increased and performance of the device is improved. A fin FET employs a bulk silicon substrate of which a manufacturing cost is lower than that of a conventional SOI type silicon substrate. Also, a floating body effect can be prevented, or is substantially reduced.

A vertical transistor forming method includes forming a first pillar above a first source/drain and between second and third pillars, providing a first recess between the first and second pillars and a wider second recess between the first and third pillars, forming a gate insulator over the first pillar, forming a front gate and back gate over opposing sidewalls of the first pillar by depositing a gate conductor material within the first and second recesses and etching the gate conductor material to substantially fill the first recess, forming the back gate, and only partially fill the second recess, forming the front gate, forming a second source/drain elevationally above the first source/drain, and providing a transistor channel in the first pillar. The channel is operationally associated with the first and second sources/drains and with the front and back gates to form a vertical transistor configured to exhibit a floating body effect.

A preferred embodiment of the invention provides a semiconductor fabrication method. An embodiment comprises forming a MOS device and thermally oxidizing the MOS device to form a gate dielectric substantially thicker at a gate dielectric edge than that at a gate dielectric center. Embodiments further comprise performing a source/drain ion implant to form an asymmetric source/drain, wherein the source region includes a high leakage source junction, and wherein the drain region includes a low leakage drain junction. Other embodiments of the invention comprise a MOS device formed in a semiconductor substrate, wherein the device has improved resistance to floating body effects. Still other embodiments include a CMOS device for low power integrated circuits.

A silicon-on-insulator structure provides an effective drift field for holes, and simultaneously enhanced recombination centers for holes and electrons. The structure includes a silicon substrate, an oxide insulation layer disposed above the silicon substrate, a silicon body layer disposed above the oxide insulation layer, and a field shield gate disposed above the silicon body layer. The field shield gate includes a conductor portion, and an alumina insulation layer disposed beneath the conductor portion. The oxide insulation layer and the silicon body layer each include at least one channel stop region, and at least one recombination center for the recombination of positive- and negative-charge carriers. The effective drift field and enhanced recombination centers facilitate the rapid recombination of the charge carriers, leading to a very small recombination time constant, which overcomes the floating body effect associated with conventional silicon-on-insulator structures.

A structure for testing relative to an MOS transistor, can be easily constructed as part of the CMOS process flow. A doped device well is formed, for example, in a silicon-on-insulator structure. The concentration level in the well corresponds to that for a well of the transistor. Gate insulator and polysilicon layers are formed, and the polysilicon is implanted with dopant, to a concentration level expected in the transistor gate. After gate patterning, the methodology involves forming sidewall spacers and implanting dopant into the active device well, to form regions in the test structure corresponding to the transistor source and drain. Although the concentrations mimic those in the transistor source and drain, these test structure regions are doped with opposite type dopant material. The test structure enables accurate measurement of the gate-body current, for modeling floating body effects and/or for measurement of gate length.

A source trench and a drain trench are asymmetrically formed in a top semiconductor layer comprising a first semiconductor in a semiconductor substrate. A second semiconductor material having a narrower band gap than the first semiconductor material is deposited in the source trench and the drain trench to form a source side narrow band gap region and a drain side narrow band gap region, respectively. A gate spacer is formed and source and drain regions are formed in the top semiconductor layer. A portion of the boundary between an extended source region and an extended body region is formed in the source side narrow band gap region. Due to the narrower band gap of the second semiconductor material compared to the band gap of the first semiconductor material, charge formed in the extended body region is discharged through the source and floating body effects are reduced or eliminated.

A method for making a semiconductor device, comprising (a) providing a structure comprising a gate electrode (207) disposed on a substrate (203); (b) creating first (213) and second (214) pre-amorphization implant regions in the substrate such that the first and second pre-amorphization implant regions are asymmetrically disposed with respect to said gate electrode; (c) creating first (219) and second (220) spacer structures adjacent to first and second sides of the gate electrode, wherein the first and second spacer structures overlap the first and second pre-amorphization implant regions; and (d) creating source (217) and drain (218) regions in the substrate adjacent, respectively, to the first and second spacer structures.