Sgsates Componenti Elettronici S.p.a.

Sgs Microelettronica Spa

Sgs-Thomson Microelectronics S.r.l.

Sgs-Thomson Microelectronics Limited

Stmicroelectronics S.r.l.

Giuseppe Corda

Paolo Giuseppe Cappelletti

Carlo Riva

Vincenzo Daniele

Andrea Ravaglia

Giuseppe Ferla

Guido Torelli

Bruno Vajana

Livio Baldi

Paolo Ghezzi

Giorgio De Santi

Danilo Re

Giulio Iannuzzi

Aldo Magrucci

Franco Miccoli

The cell is formed of a selection transistor, a detection transistor and a tunnel condenser. The detection Transistor has its own control gate formed with an n diffusion which is closed and isolated from those of the other cells of the same memory.

EEPROM memory cell with a single level of polysilicon programmable and erasable bit by bit

The manufacturing process comprises a first step of formation of an N type sink on a single-crystal silicon substrate, a second step of formation of an active area on the surface of said sink, a third step of implantation of N- dopant in a surface region of the sink inside said active area, a fourth step of growth of a layer of gate oxide over said region with N- dopant, a fifth step of N+ implantation inside said N- region, a sixth step of P+ implantation in a laterally displaced position with respect to said N+ region and a seventh step of formation of external contacts for said N+ and P+ regions. There is thus obtained a zener diode limiter, having a cut-off voltage which is stable over time and not much dependent on temperature and which does not require the addition of process steps with respect to those usually necessary for the accomplishment of EEPROM memory cells.

Process for the manufacture of a component to limit the programming

The tunnelling area of a EEPROM memory device of the FLOTOX type is efficiently reduced in respect to the minimum areas obtained by means of current fabrication technologies, by forming the injection zone for the transfer of the electric charges by tunnel effect to and from the floating gate through an original self-aligned process, which allows limiting the dimensions of such a tunnelling area independently from the resolution limits of the available photolithographic technology.

Electrically alterable, nonvolatile, floating gate type memory device

The cell is formed of a selection transistor, a detection transistor and a tunnel condenser. The detection Transistor has its own control gate formed with an n.sup.+ diffusion which is closed and isolated from those of the other cells of the same memory.

EEPROM memory cell with a single level of polysilicon programmable and

The tunnelling area of a EEPROM memory device of the FLOTOX type is efficiently reduced in respect of the minimum areas obtained by means of current fabrication technologies, by forming the injection zone for the transfer of the electric charges by tunnel effect to an from the floating gate through an original self-aligned process, which allows to limit the dimensions of such a tunnelling area independently from the resolution limits of the available photolithographic technology.

Floating gate memory with sidewall tunnelling area

An EPROM memory cell including a source, a drain, a floating gate and a control gate with interposed dielectric oxide is made up of two symmetrical half-cells having the drain and the control gate in common, the sources physically separated but electrically connected with each other and the floating gates separated physically and electrically.

Eprom memory cell with two symmetrical half-cells and separate floating

The invention provides an EPROM memory matrix and a method of writing to an EPROM memory matrix. Two pluralities of parallel source lines alternate with parallel drain lines while floating gate areas span the source and drain lines and parallel control gate lines are arranged perpendicularly to the source and drain lines and superimposed on and self-aligned with the floating gate areas. During the writing operation, the gate and drain lines corresponding to a selected cell are connected to a positive voltage source and the source line corresponding to the selected cell is connected to earth together with all the other source lines of the same plurality while all the source lines of the other plurality are left at a potential intermediate between said positive voltage and earth.

Eprom memory matrix with symmetrical elementary MOS cells and writing

The method provides for the formation of a layer of metal silicide on the gate layer of polycrystalline silicon and, for each transistor of the CMOS pair, the simultaneous doping of the active regions and the gate polycrystalline silicon. In the structure produced by this method, the gate electrodes are of polycrystalline silicon covered by metal silicide and the gate electrode of the n-channel transistor is doped with n-type material, while the gate electrode of the p-channel transistor is doped with p-type impurities. This enables the production of low threshold voltages for both transistors even in the case of very high integration densities.

Fabricating a CMOS transistor having low threshold voltages using

A storage cell of a nonvolatile electrically alterable MOS memory (EAROM) comprises a p-type silicon substrate with n-doped drain and source areas interlinked by an n-channel which is partly overlain by a floating gate extending over part of the drain area. An accessible gate overlaps the floating gate and has an extension overlying a gap between the latter gate and the source area to act as a common control electrode for two series IGFETs defined by the source and gate areas, namely a main or storage transistor and an ancillary or switching transistor. The capacitance of the floating gate relative to the drain area accounts for about half the overall capacitance of that gate relative to the entire semiconductor structure.

Storage cell for nonvolatile electrically alterable memory

A nonvolatile memory of the electrically alterable kind comprises an orthogonal array of cells each including a floating-gate IGFET and an enhancement IGFET in series. For the programming or the reading of a selected cell, lying at the intersection of a row and a column of the array, a common gate lead for all the enhancement IGFETs of the row and a common drain lead for all the enhancement IGFETs of the column are energized with voltage dependent on the desired kind of operation. To write a bit in a cell, its floating gate is progressively charged in a succession of steps separated by reading operations to check on the conduction threshold of the cell; the charging ends when that threshold reaches a predetermined storage level. To cancel a written bit, the floating gate is progressively discharged in a succession of steps again separated by reading operations; the discharging is terminated when the conduction threshold reaches a predetermined cancellation level. The width and/or the amplitude of a voltage pulse applied to an accessible gate of the floating-gate IGFET during the successive charging or discharging steps may be increased after each reading step in which the desired level is not attained.

Method of programming an electrically alterable nonvolatile memory

Filiform elements of predetermined resistivity, e.g. selectively destructible leads of an electrically programmable read-only memory, are formed on a semiconductor substrate such as a silicon body by first depositing thereon a layer of dielectric material such as SiO.sub.2 and topping that layer with a conductive or nonconductive coating which is resistant to a chemical such as hydrofluoric acid capable of attacking the dielectric layer. Next, the top coating is partly destroyed by photolithographic treatment to leave at least one substantially rectangular patch. Thereafter, the dielectric layer is isotropically attacked by the aforementioned chemical with resulting reduction to about half its original thickness and concurrent lateral erosion of a patch-supporting pedestal of that layer whereby channels of generally semicylindrical concavity are formed around the periphery of this pedestal. The patch, if composed of conductive or semiconductive material, is then clad in an insulating envelope whereupon the dielectric layer and the patch are covered with a deposit of the desired electrical conductivity which could consist of doped polycrystalline silicon or of metal. Finally, this deposit is removed by chemical or ionic etching except in the channels of the pedestal and along a pair of parallel strips adjoining opposite pedestal sides whereby these strips remain electrically interconnected by filiform inserts left in the undercuts of the other two sides.

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Saronno, Italy

Giuseppe Corda