摘要:
A semiconductor-on-insulator (SOI) electronic device includes a monocrystalline semiconductor substrate and at least one trench therein. A trench insulating layer is provided on a bottom the trench for electrical isolation and a monocrystalline semiconducting region is also included in the trench, on the trench insulating layer. The semiconducting region preferably includes epitaxially overgrown silicon (EOS) which is grown from an exposed sidewall of the trench. An active region of the electronic device is also included in the semiconductor layer. Second, third, and additional active regions of the electronic device, if any, may also be included in the semiconducting region or in additional semiconducting regions which are provided in additional trenches. The semiconductor substrate may also include one or more active regions of the electronic device.
摘要:
A method of forming a semiconductor-on-insulator (SOI) electronic device includes the steps of etching a semiconductor substrate to form a plurality of adjacent trenches therein and then forming electrically insulating layers on bottoms of the trenches. Epitaxial lateral overgrowth (ELO) is then performed to grow respective monocrystalline semiconducting regions in the trenches. These semiconducting regions are preferably grown from a sidewall of each trench onto a respective insulating layer and fill each trench. Monocrystalline active regions of the electronic device are then formed in the semiconducting regions and also in the substrate, adjacent the trench sidewalls. For example, a monocrystalline trench isolated extrinsic base region of a bipolar junction transistor (BJT) can be formed in a semiconducting region in a respective trench, and a corresponding intrinsic base region and an intrinsic collector region can be formed in the substrate, adjacent the semiconducting region. Alternatively, trench isolated source and drain regions of a field effect transistor (FET) can be formed in one or more adjacent semiconducting regions and the corresponding channel region of the FET can be formed therebetween.
摘要:
A magnetoresistive random access memory (MRAM) has separate read and write paths. This reduces the peripheral circuitry by not requiring switching between read and write functions on a particular line. By having the paths dedicated to either read signals or write signals, the voltage levels can be optimized for these functions. The select transistors, which are part of only the read function, may be of the low-voltage type because they do not have to receive the relatively higher voltages of the write circuitry. Similarly, the write voltages do not have to be degraded to accommodate the lower-voltage type transistors. The size of the overall memory is kept efficiently small while improving performance. The memory cells are grouped so that adjacent to groups are coupled to a common global bit line which reduces the space required for providing the capacitance-reducing group approach to memory cell selection.
摘要:
A sense amplifier (1300, 1500) is provided for sensing the state of a toggling type magnetoresistive random access memory (MRAM) cell without using a reference. The sense amplifier (1300, 1500) employs a sample-and-hold circuit (1336, 1508) combined with a current-to-voltage converter (1301, 1501), gain circuit (1303), and cross-coupled latch (1305, 1503) to sense the state of a bit. The sense amplifier (1300, 1500), first senses and holds a first state of the cell. The cell is toggled to a second state. Then, the sense amplifier (1300, 1500) compares the first state to the second state to determine the first state of a toggling type memory cell.
摘要:
A semiconductor device that includes a floating gate made up of a plurality of pre-formed isolated storage elements (18) and a method for making such a device is presented. The device is formed by first providing a semiconductor layer (12) upon which a first gate insulator (14) is formed. A plurality of pre-fabricated isolated storage elements (18) is then deposited on the first gate insulator (14). This deposition step may be accomplished by immersion in a colloidal solution (16) that includes a solvent and pre-fabricated isolated storage elements (18). Once deposited, the solvent of the solution (16) can be removed, leaving the pre-fabricated isolated storage elements (18) deposited on the first gate insulator (14). After depositing the pre-fabricated isolated storage elements (18), a second gate insulator (20) is formed over the pre-fabricated isolated storage elements (18). A gate electrode (24) is then formed over the second gate insulator (20), and portions the first and second gate insulators and the plurality of pre-fabricated isolated storage elements that do not underlie the gate electrode are selectively removed. A source region (32) and a drain region (34) are then formed in the semiconductor layer (12) such that a channel region is formed between underlying the gate electrode (24).
摘要:
An antifuse circuit provides on a per bit basis a signal that indicates whether an MTJ (magnetic tunnel junction) antifuse has been previously programmed to a low resistance state in response to a program voltage. A sense amplifier provides the resistance state signal. A plurality of reference magnetic tunnel junctions are coupled in parallel and to the sense amplifier, each having a resistance within a range to provide a collective resistance that can be determined by the sense amplifier to differ from each resistance state of the MTJ antifuse. A write circuit selectively provides a current sufficient to create the program voltage when the write circuit is enabled to program the antifuse magnetic tunnel junction. Upon detecting a change in resistance in the MTJ antifuse, the write circuit reduces current supplied to the antifuse. Multiple antifuses may be programmed concurrently. Gate oxide thicknesses of transistors are adjusted for optimal performance.
摘要:
In a magnetoresistive random access memory (MRAM), a magnetic tunnel junction (MTJ) (54) cell is stacked with an asymmetric tunnel device (56). This device, when used in a crosspoint MRAM array, improves the sensing of the state or resistance of the MTJ cells. Each MTJ cell has at least two ferromagnetic layers (42, 46) separated by an insulator (44). The asymmetric tunnel device (56) is electrically connected in series with the MTJ cell and is formed by at least two conductive layers (48, 52) separated by an insulator (50). The asymmetric tunnel device may be a MIM (56), MIMIM (80) or a MIIM (70). Asymmetry results from conducting electrons in a forward biased direction at a significantly greater rate than in a reversed biased direction. Materials chosen for the asymmetric tunnel device are selected to obtain an appropriate electron tunneling barrier shape to obtain the desired rectifying current/voltage characteristic.
摘要:
A magnetoresistive random access memory (MRAM) has separate read and write paths. Switchable current mirrors, each having multiple series-connected stages, receive a common reference current. A timing circuit provides control signals to word and bit decoders and to the switchable current mirrors to selectively complete current paths through a predetermined write word line and a predetermined write bit line. Bit lines are connected together at a common end, and word lines are connected together at a common end. By precharging a common rail having multiple write bit lines connected together, the write noise immunity is improved and current spikes are minimized. Groups of bit lines may be connected via a metal option to adjust a transition time of a programming current.
摘要:
A magnetoresistive random access memory (MRAM) has separate read and write paths. Switchable current mirrors, each having multiple series-connected stages, receive a common reference current. A timing circuit provides control signals to word and bit decoders and to the switchable current mirrors to selectively complete current paths through a predetermined write word line and a predetermined write bit line. Bit lines are connected together at a common end, and word lines are connected together at a common end. By precharging a common rail having multiple write bit lines connected together, the write noise immunity is improved and current spikes are minimized. Groups of bit lines may be connected via a metal option to adjust a transition time of a programming current.
摘要:
A process for polish planarizing a fill material (40) overlying a semiconductor substrate (30) includes a multi-step polishing process. In one embodiment, a second planarization layer (42) is deposited over a fill material (40) and a portion of the fill material (40) is removed leaving a remaining portion (44). The pad pressure of a CMP apparatus (20) is adjusted such that a first pressure is generated during the polishing process. Then, the remaining portion (44) is removed, while operating the CMP apparatus (20) at a second pad pressure. The selectivity of the polishing process is maintained by reducing the pad pressure during the second polishing step. In a second embodiment, after the first polishing step is performed, the remaining portion (44) is removed by an etching process using a portion (46) of second planarization layer (42).