Abstract:
An improved method for autoaligning lines (WL) of a conductive material in circuits integrated on a semiconductor substrate (2), comprising the following steps:
forming, on said semiconductor substrate (2), a plurality of regions (3) projecting from the substrate (2) surface and aligned to one another; forming a fill layer (4) in the gaps between said regions (3) ; planarizing said fill layer (4) to expose said regions (3) ; removing a surface portion of said regions (3) to form holes (5) at the locations of said regions (3); forming an insulating layer (6) in said holes (5); selectively removing the dielectric layer (6) to form spacers (7) along the edges of said holes (5) ; depositing at least one conductive layer (8) all over the exposed surface; photolithographing with a mask and etching away the layer (8) to define lines (WL) and collimate them to the underlying regions (3).
Abstract:
A method of manufacturing a P-channel native MOS transistor (7) in a circuit integrated on a semiconductor (1) which also includes a matrix of non-volatile memory cells of the floating gate type with two polysilicon levels (5,10) having an interpoly dielectric layer sandwiched between the two polysilicon levels, comprises the following steps:
masking and defining active areas (2) of the discrete integrated devices; masking and defining the first polysilicon level (5) using a Poly1 mask; and masking and defining an intermediate dielectric layer (8) using a Matrix mask (9).
The length of the native threshold channel of the native transistor is defined by means of the Matrix mask (9) and by etching away the interpoly dielectric layer (8). A subsequent step of masking and defining the second polysilicon level (10) provides for the use of a Poly2 mask (12) which extends the active area of the transistor (7) with a greater width than the previous mask (9) in order to enable, by subsequent etching, the two polysilicon levels (5,10) to overlap in self-alignment over the channel region.
Abstract:
A process for manufacturing an integrated circuit comprising an array of memory cells, providing for: a) forming in a memory cell array area of a semiconductor layer (6) an active area for the memory cells; b) forming over said active area for the memory cells a gate oxide layer (8); c) forming over the whole integrated circuit a first layer of conductive material (9); d) forming over the first layer of conductive material (9) a layer of insulating material (10); e) removing the layer of insulating material (10) from outside the memory cell array area; f) forming over the whole integrated circuit a second layer of conductive material (11) which in the memory cell array area is separated from the first layer of conductive material (9) by the insulating material layer (10), while outside the memory cell array area is directly superimposed over said first layer of conductive material (9); g) inside the memory cell array area, defining first strips (22) of the second layer of conductive material (11) for forming rows (3) of the memory cell array (1), and outside the memory cell array area defining second strips (17) of the second layer of conductive material (11) for forming interconnection lines (100) for electrically interconnecting the rows (3) of the memory cell array with a circuitry (5,RD), said defining the second strips (17) providing for selectively etching the first and second layers of conductive material (9,11) outside the memory cell array area by means of a first mask (MASK1), and said defining the first strips (22) providing for selectively etching the second layer of conductive material (11), the layer of insulating material (10) and the first layer of conductive material (9) inside the memory cell array area by means of a second mask (MASK2). The first and second masks (MASK1,MASK2) overlap in a boundary region around the memory cell array area, so that the first strips (22) and the second strips (17) of the second layer of conductive material (11) are automatically joined at respective ends thereof at said boundary region.
Abstract:
A process for manufacturing electronic semiconductor integrated electronic memory devices having virtual ground and comprising at least a matrix of floating gate memory cells (1), the matrix being formed on a semiconductor substrate (2) with a plurality of continuous bit lines (10) extending across the substrate (2) as discrete parallel strips, comprising at least the following steps:
forming an oxide layer (3) over the matrix region; depositing the semiconductor throughout with a stack structure which comprises a first conductor layer (4), first dielectric layer (5), and second conductor layer (6); forming a second dielectric layer (7); defining floating gate regions (13) by photolithography using a mask of "POLY1 along a first predetermined direction", and associated etching, to define, in said stack structure, a plurality of parallel openings (9); implanting said parallel openings (9) to confer a predetermined conductivity on the bit line (10) regions; filling the parallel openings (12) with a photo-sensitive material (11) to protect the matrix bit lines (10).
Abstract:
A process for manufacturing a dual charge storage location electrically programmable memory cell comprises the steps of: forming a central insulated gate ( 12 , 15 ) over a semiconductor substrate ( 11 ); forming physically separated charge-confining layers stack portions of a dielectric-charge trapping material-dielectric layers stack ( 19 , 110 , 111 ; 29 , 210 , 211;49A , B , 410A , B , 411A , B ) at the sides of the central gate, the charge trapping material layer ( 110 ; 210 ; 410A , B ) in each charge-confining layers stack portion forming a charge storage element; forming side control gates ( 113A , B ; 212 ; 312 ; 413A , B ) over each of the charge-confining layers stack portions; forming memory cell source/drain regions ( 115 ; 215 ; 315 ; 415 ) laterally to the side control gates; electrically connecting ( 116 , 117 ; 216 ; 312 ; 416 ) the side control gates to the central gate. Each of the charge-confining layers stack portions at the sides of the central gate is formed with an "L" shape, with a base charge-confining layers stack portion lying on the substrate surface and an upright charge-confining layers stack portion lying against a respective side of the insulated gate.
Abstract:
A process for manufacturing electronic semiconductor integrated memory devices having a virtual ground and comprising at least a matrix of floating gate memory cells (1), the matrix being formed on a semiconductor substrate (2) with a plurality of continuous bit lines (BL) extending across the substrate (2) as discrete parallel strips, comprising at least the following steps:
growing an oxide layer (3) over the matrix region; depositing the semiconductor throughout with a stack structure which comprises a first conductor layer (4), first dielectric layer (5), and second conductor layer (6): depositing a second dielectric layer (7); defining floating gate regions (10) by photolithography using a mask of "POLY1 along a first direction", to thereby define, in said dielectric layer (7), a plurality of parallel strips (8) which delimit a first dimension of floating gate regions; etching away said dielectric layer (7) to define said plurality of parallel dielectric strips (8); photolithographing by means of a mask of "POLY1 along a second direction" to define a plurality of dielectric islands (9) in said plurality of parallel strips (8); etching away said dielectric layer (7) to define the plurality of islands (9); etching away said stack structure (4,5,6) and the thin gate oxide layer (3) to define gate regions (10) of the matrix cells using said oxide island (9).
Abstract:
A process for manufacturing a MOS transistor (1) integrated in a semiconductor substrate (2) having a first type of conductivity, which process comprises the steps of:
forming a layer (3) of gate oxide over the semiconductor substrate (2); forming a gate electrode (4) over this oxide layer; forming a layer (5) of covering oxide over the gate oxide layer (3), the gate electrode (4), and around the gate electrode (4); implanting a dopant of a second type of conductivity to provide implanted regions (6,6a,6b) adjacent to the gate electrode; subjecting the semiconductor to thermal treatments to allow the implanted regions (6,6a,6b) to diffuse into the semiconductor substrate (2) under the gate electrode (4) and form gradual junction drain and source regions of said transistor.