Sgs-thomson Microelectronics S.r.l.

Stmicroelectronics S.r.l.

Sgs Microelettronica Spa

Danilo Re

Livio Baldi

Emilio Giambattista Ghio

Giuseppe Meroni

Paola Maria Granatieri

Massimo Monselice

Alfonso Maurelli

Giuseppe Corda

Giorgio De Santi

Giulio Iannuzzi

A fabrication process and an integrated MOS device having multi-crystal silicon resisters are described. The process includes depositing a multi-crystal silicon layer on top of a single-crystal silicon body; forming silicon oxide regions on top of the multi-crystal silicon layer in zones where resistors are to be produced; depositing a metal silicide layer on top of and in contact with the multi-crystal silicon layer so as to form a double conductive layer; and shaping the conductive layer to form gate regions, of MOS transistors. During etching of the double conductive layer, the metal silicide layer on top of the silicon oxide regions is removed and the silicon oxide regions form masking regions for the multi-crystal silicon underneath, so as to form resistive regions having a greater resistivity than the gate regions.

Process for fabricating integrated multi-crystal silicon resistors in MOS technology, and integrated MOS device comprising multi-crystal silicon resistors

A process for manufacturing integrated capacitors in CMOS technology, comprising the steps of: producing, in a substrate of semiconductor material having a first type of conductivity, at least one well with the opposite type of conductivity, defining the active areas, producing insulation regions, depositing a first conducting layer of polycrystalline silicon adapted to form the gate regions and the lower plates of the capacitors, depositing a layer of silicon oxide at low temperature, to form the dielectric of the capacitors, depositing a second layer of polycrystalline silicon to form the second plate of the capacitors, shaping the polycrystalline silicon and silicon oxide layers, implanting and diffusing the source and drain regions of the CMOS transistors, providing the insulation layer, the metallic connecting layer, and final covering with a layer of protective insulation.

Process for manufacturing integrated capacitors in MOS technology

ROM memories made in MOS or CMOS technology with LDD cells may be programmed advantageously in a relatively advanced stage of fabrication by decoupling an already formed drain region from the channel region of cells to be permanently made nonconductive (programmed) by implanting a dopant in an amount sufficient to invert the type of conductivity in a portion of the drain region adjacent to the channel region. In CMOS processes, the programming mask may be a purposely modified mask commonly used for implanting source/drain regions of transistors of a certain type of conductivity. By using high-energy implantation and a dedicated mask, the programming may be effected at even later stages of the fabrication process.

NOR-type ROM with LDD cells and process of fabrication

Method of making NOR-type ROM with LDD cells

A method of manufacturing integrated circuits includes steps: forming a first layer of polycrystalline silicon on areas of a semiconductor substrate previously covered with a dielectric material; forming a first insulating layer and a second thin layer of polycrystalline silicon acting as a shield; removing the second layer of polycrystalline silicon and the first insulating layer except from predetermined areas for containing a first type of electronic component; doping the exposed portion of the first layer of polycrystalline silicon; forming, by deposition, masking and removal, of a second insulating layer on the first layer of polycrystalline silicon in an area for containing a second type of electronic component; forming of a third layer of polycrystalline silicon; masking predetermined zones of this latter layer lying at least partially above the areas intended for the two types of electronic components, and removing the polycrystalline silicon external to these predetermined zones. The method continues with conventional steps and makes it possible to obtain, for instance, EPROM memory cells and capacitors using the same polycrystalline silicon depositing steps for forming their electrodes, without dispensing with the maximum freedom and precision in the choice of the physical characteristics and dimensions of the two types of components.

Method of manufacturing integrated circuits having electronic components

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.

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Bernareggio, Italy

Danilo Re