Stmicroelectronics S.r.l.

Matteo Patelmo

Bruno Vajana

Giovanna Dalla Libera

Nadia Galbiati

Federico Pio

Carlo Cremonesi

Massimo Bassi

Stefano Scuratti

Rosario Portoghese

A method for locating in an array of memory cells a set of cells having a stand-by current that exceeds a certain value based on their programming state. The method includes selecting all the cells of the array of memory cells as a set of cells to be tested, and dividing the set of cells to be tested into subsets of cells, and repeatedly sensing a stand-by current absorbed by the array of memory cells after having changed the programming state of the subsets of cells. The sensed stand-by currents are compared and a subset of cells having a stand-by current exceeding the certain value are identified as a function of the comparison. The identified subset of cells is selected as a new set of cells to be tested, and the method is repeated. Otherwise, the testing stops with the just tested subset of cells having a stand-by current exceeding the certain value.

Method and circuit for locating anomalous memory cells

A non-volatile memory device including a plurality of memory cells, each memory cell formed as MOS transistor with a source region, a drain region and a gate having sides formed therewith; and one or more dielectric spacers disposed on the sides of the gate. At least one memory cell is defined in an ON state and at least one memory cell is defined in an OFF state. The memory cells in the ON state comprise drain regions and source regions of the lightly diffused drain (LDD) type, characterized in that the at least one drain region and the at least one source region of the memory cells in the OFF state are formed by one or more high dopant regions. The memory cells in the OFF state consists of layers of silicide on top of one or more active regions defined as the source region, the drain region, and the gate.

Non-volatile high-performance memory device and relative manufacturing process

The manufacturing method comprises, in sequence, the steps of: depositing an upper layer of polycrystalline silicon; defining the upper layer, obtaining LV gate regions of low voltage transistors and undefined portions; forming LV source and drain regions laterally to the LV gate regions; forming a layer of silicide on the LV source and drain regions, on the LV gate regions, and on the undefined portions; defining stack gate regions and HV gate regions of high-voltage transistors; and forming HV source and drain regions and cell regions.

Method for manufacturing electronic devices having non-volatile memory cells and LV transistors with salicided junctions

A read only memory (ROM) device includes a semiconductor substrate having a first type of conductivity, and a plurality of memory cells on the semiconductor substrate. Each memory cell includes first and second regions of a second conductivity type opposite the first conductivity type. A first dielectric layer is on the plurality of memory cells, and a plurality of first contacts extend through the first dielectric layer for contacting the first regions. A second dielectric layer is on the first dielectric layer and the plurality of first contacts. A plurality of second contacts extend through the second dielectric layer and overlie the corresponding second regions. The plurality of second contacts define interconnection contacts by further extending through the first dielectric layer for contacting the second regions for memory cells programmed in a conductive state, and false interconnection contacts by not extending through the first dielectric layer for contacting the second regions for memory cells programmed in a non-conductive state.

Mask programmed ROM inviolable by reverse engineering inspections and method of fabrication

Presented is a method for obtaining a multi-level ROM in a dual gate EEPROM process flow. The method begins with, on a semiconductor substrate, defining active areas respectively for transistors of ROM cells, transistors of electrically erasable non-volatile memory cells, and additional transistors of the storage circuitry. Then, integrated capacitors are integrated in the storage circuit. According to this method, during the implanting step for forming integrated capacitors, at least an active area of the ROM cell is similarly implanted.

Method for obtaining a multi-level ROM in an EEPROM process flow

A process that provides for the manufacture of LV transistors with salicidated junctions on first areas of a substrate, HV transistors on second areas, and memory cells on third areas. The process includes forming LV oxide regions and LV gate regions on the first areas, HV oxide regions on the second areas, selection oxide regions, tunnel oxide regions, and matrix oxide regions on the third areas; forming floating gate regions and insulating regions on the tunnel oxide regions and the matrix oxide regions; forming first LV source and drain regions laterally to the LV gate regions; forming silicide regions on the first source and drain regions and on the LV gate regions; forming semiconductor material regions completely covering the second and third areas; and at the same time forming HV gate regions on the HV oxide regions, forming selection gate regions on the selection oxide regions, and forming control gate regions on the insulating regions through shaping of the semiconductor material regions.

Process for manufacturing electronic devices having non-salicidated non-volatile memory cells, non-salicidated HV transistors, and salicidated-junction LV transistors

A manufacturing process providing a zener diode formed in an N-type well housing a first N-type conductive region and having a doping level higher than the well, and a second P-type conductive region arranged contiguous to the first conductive region. The first conductive region is connected, through a third N-type conductive region having the same doping level as the first conductive region, to a conductive material layer overlying the gate oxide layer to be protected. The third conductive region, the well, and the substrate form an N /N/P diode that protects the gate oxide layer during manufacture of the integrated device from the deposition of the polycrystalline silicon layer that forms the gate regions of the MOS elements.

Process for the manufacture of integrated devices with gate oxide protection from manufacturing process damage, and protection structure therefor

A method of making an integrated circuit that is resistant to an unauthorized duplication through reverse engineering includes forming a plurality of false contacts and/or false interconnection vias in the integrated circuit. These false contacts and/or false interconnection vias are connected as true contacts and true interconnection vias by lines patterned in a metallization layer deposited over an insulating dielectric layer or multilayer through which the true contacts and/or the true interconnection vias are formed. False contacts and false vias extend in the respective dielectric layers or multilayers to a depth insufficient to reach the active areas of a semiconductor substrate for false contacts, or to a depth insufficient to reach a layer of conductive material below the dielectric layers or multilayers for false interconnection vias.

Anti-deciphering contacts

The invention relates to a method of producing a multi-level memory of the ROM type in a CMOS process of the dual gate type. Specifically, some of the transistors of the ROM cells have their polysilicon layers masked and the ROM cells are then implanted by a first dopant species in the active areas of the exposed transistors. Then the masks are removed from the polysilicon layer, and a second dopant species is implanted in said previously covered layer.

Method for forming a multilevel ROM memory in a dual gate CMOS process, and corresponding ROM memory cell

A process for manufacturing an electronic device having an HV MOS transistor with a low multiplication coefficient and a high threshold in a non-implanted area of the substrate, this area having the same conductivity type and the same doping level as the substrate. The transistor is obtained by forming, over the non-implanted substrate area, a first gate region of semiconductor material having the same doping type as the non-implanted substrate area; and forming, inside the non-implanted substrate area, first source and drain regions of a second conductivity type, arranged at the sides of the first gate region. At the same time, a dual-gate HV MOS transistor is formed, the source and drain regions of which are housed in a tub formed in the substrate and having the first conductivity type, but at a higher concentration than the non-implanted substrate area. It is moreover possible to form a nonvolatile memory cell simultaneously in a second tub of the substrate of semiconductor material.

Process for manufacturing electronic devices comprising high voltage MOS transistors, and electronic device thus obtained

A simplified non-DSCP process for the definition of the tunnel area in nonvolatile memory cells with semi-conductor floating gates is presented. The memory cells are non-aligned and are incorporated in a matrix of cells and have associated control circuitry. In additional, to each cell a selection transistor is associated. The process includes at least the following phases: growth or deposition of a dielectric layer of gate of the sensing transistor and of the cells; tunnel mask for defining the area of tunnel; cleaning etching of the dielectric layer of gate in the area of tunnel up to the surface of the semiconductor; and growth of tunnel oxide. Advantageously, the tunnel mask is extended above the region occupied by the selection transistor.

Simplified process for defining the tunnel area in non-aligned, non-volatile semiconductor memory cells

A manufacturing method having the steps of: depositing an upper layer of polycrystalline silicon; defining the upper layer, obtaining LV gate regions of low voltage transistors and undefined portions; forming LV source and drain regions laterally to the LV gate regions; forming a silicide layer on the LV source and drain regions, on the LV gate regions, and on the undefined portions; defining salicided HV gate regions of high voltage transistors; and forming HV source and drain regions not directly overlaid by silicide portions.

Method for manufacturing electronic devices having HV transistors and LV transistors with salicided junctions

To increase the facing surface and thus the coupling between the floating gate and control gate regions of a memory cell, the floating gate and control gate regions have a width that is not constant in different section planes parallel to a longitudinal section plane extending through the source and drain regions of the cell. In particular, the width of the floating gate and control gate regions is smallest in the longitudinal section plane and increases linearly in successive parallel section planes moving away from the longitudinal section plane.

High efficiency memory device

A method for manufacturing electronic devices, such as memory cells and LV transistors, with salicided junctions, that includes: depositing an upper layer of polycrystalline silicon; defining the upper layer, obtaining floating gate regions on first areas, LV gate regions on second areas of a substrate, and undefined regions on the first and third areas of the substrate; forming first cell source regions laterally to the floating gate regions; forming LV source and drain regions laterally to the LV gate regions; forming a silicide layer on the LV source and drain regions, on the LV gate regions, and on the undefined portions; defining HV gate regions on the third areas, and selection gate regions on the first areas; forming source regions laterally to the selection gate regions, and source and drain regions laterally to the HV gate regions.

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Trezzo sull'Adda, Italy

Matteo Patelmo