Abstract:
Method of manufacturing an integrated circuit comprising a memory operating at high voltage and logic circuitry operating at a lower voltage than the memory: formation of a first layer of gate oxide (3) with a first thickness on first and second portions of a semiconductor substrate (1) which are intended, respectively, for first transistors operating at high voltage and for second transistors operating at the lower voltage, and formation of a second layer of gate oxide (5) with a second thickness on third portions for cells of the memory; deposition of a first polysilicon layer to define gate electrodes (8,9) for first transistors and floating gate electrodes (7) for the memory cells; deposition of an interpolysilicon dielectric layer (18) so as to leave the interpolysilicon dielectric layer on the gate electrodes (8,9) of first transistors and on the floating gate electrodes (7); formation, on the second portions (1), of a third gate oxide layer (24) with a third thickness less than the first thickness of the first gate oxide layer (3); deposition of a second polysilicon layer (25) to define gate structures (29) of the memory cells, and gate electrodes (26,27) of second transistors and polysilicon covers (80,90) for the gate electrodes (8,9) of first transistors.
Abstract:
A method is described for manufacturing electrically non active structures of an integrated electronic circuit (1) formed on a semiconductor substrate (7) comprising first electrically active structures (2) which comprise electric components provided with conductive elements (16) of a first height (H1) projecting from said semiconductor substrate (7) and second electrically active structures (3) which comprise electric components provided with conductive elements (20) of a second height (H2) projecting from said semiconductor substrate (7), said first height being different from said second height, the method comprising the steps of: - introducing, into the integrated electronic circuit (1), electrically non active structures (4) to superficially uniform the integrated electronic circuit (1), - identifying, between the electrically non active structures (4), a first group (5) of electrically non active structures which is formed by those electrically non active structures comprised in areas (5a) which substantially extend for a predetermined radius (R) around each electric component belonging to the second electrically active structures (3), - identifying, between the electrically non active structures (4), a second group (6) of electrically non active structures comprising electrically non active structures not belonging to the first group (5) of electrically non active structures, - forming the electrically non active structures belonging to the first group (5) of electrically non active structures with elements (20a) projecting from the substrate (7) having a height equal to the second height (H2), - forming the electrically non active structures belonging to the second group (6) of electrically non active structures with elements (16a) projecting from the substrate (7) having a height equal to the first height (H1), the elements (16a, 20a) belonging to the first (5) and second group (6) of electrically non active structures being formed by means of respective photolithographic steps.
Abstract:
The body regions for the n-channel and p-channel LV transistors, for the n-channel HV transistors, and for the EPROM cells are formed on a silicon substrate; a thermal oxide layer (12) is formed and a layer of polycrystalline silicon (13) is formed thereon; the latter layer is selectively removed to form the floating gate electrodes (13a) of the cells and the gate electrodes (13b) of the HV transistors; the source and drain regions (14) of the cells, the source and drain regions (22) of the n-channel HV transistors, the body regions (24) and the source and drain regions of the p-channel HV transistors are formed; an ONO composite layer (15) is formed; the silicon of the areas of the LV transistors is exposed; a thermal oxide layer (16) is formed on the exposed areas; a second polycrystalline silicon layer (17) is deposited and is then removed selectively to form the gate electrodes of the LV transistors (17c) and the control gate electrodes (17a) of the cells, and the source and drain regions of the LV transistors are formed. By virtue of the use of a material (ONO) which is impermeable to the oxygen atoms of the subsequent thermal oxidation and because the body regions (24) of the p-channel HV transistors and the source and drain regions of all of the HV transistors are produced by separate implantations, components of very good quality are produced with few more masks than a conventional LV method.
Abstract:
A sealing method for electronic devices such as flash memory cells (4) and CMOS transistors (5) formed on a common semiconductor substrate (1) comprising the steps of:
forming at least a first conductive layer (7,9) on a first portion of semiconductor substrate (1), forming a second conductive layer (11) on a second portion of semiconductor substrate (1), defining a first plurality of gate regions (4a) of the memory cells (4) in at least a first conductive layer (7), forming a first sealing layer (14) on the whole semiconductor substrate (1) to seal the first plurality of gate regions (4a), defining a second plurality of gate regions (5a) of the CMOS transistors (5) in the second conductive layer (11), forming a second sealing layer (16) on the whole semiconductor substrate (1) to seal the second plurality of gate regions (5a).
Abstract:
The active areas and the body regions for the LV MOS transistors, for the HV MOS transistors and for the EPROM cells are formed on a silicon substrate, a layer of thermal oxide is formed, and a layer of polycrystalline silicon is formed on it, the last-mentioned layer is removed selectively to form the floating gate electrodes (13a) of the cells, the source and drain regions of the cells are formed, the silicon of the areas of the HV MOS transistors is exposed, a layer of HTO oxide is formed and nitrided, the silicon of the areas of the LV MOS transistors is exposed, a layer of thermal oxide (16) is formed on the exposed areas, a second layer of polycrystalline silicon is deposited and is then removed selectively to form the gate electrodes of the LV and HV MOS transistors (17c, 17b) and the control gate electrodes (17a) of the cells, and the source and drain regions of the LV and HV MOS transistors are formed. Owing to the simultaneous formation of the gate dielectric of the HV MOS transistors and the intermediate dielectric of the cells, and the use of a material (nitrided HTO oxide) which is impermeable to the oxygen atoms of the subsequent thermal oxidation, the number of the operations in the process is smaller than in the prior art process.
Abstract:
The active areas and the body regions for the LV MOS transistors, for the HV MOS transistors and for the EPROM cells are formed on a silicon substrate, a layer of thermal oxide (12) is formed and a layer of polycrystalline silicon (13) is formed on it, the last-mentioned layer is removed selectively to form the floating gate electrodes (13a) of the cells, the source and drain regions (14) of the cells are formed, a composite ONO layer (15) is formed, the silicon of the areas of the LV MOS transistors is exposed, a layer of thermal oxide (16) is formed on the exposed areas, a second layer of polycrystalline silicon (17) is deposited and is then removed selectively to form the gate electrodes of the LV and HV MOS transistors (17c, 17b) and the control gate electrodes (17a) of the cells, and the source and drain regions of the LV and HV MOS transistors are formed. Owing to the simultaneous formation of part of the gate dielectric of the HV MOS transistors and the intermediate dielectric of the cells, and the use of a material (ONO) which is impermeable to the oxygen atoms of the subsequent thermal oxidation, the number of the operations in the process is smaller than in the prior art process.