Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10B—ELECTRONIC MEMORY DEVICES
  • H10B69/00—Erasable-and-programmable ROM [EPROM] devices not provided for in groups H10B41/00 - H10B63/00, e.g. ultraviolet erasable-and-programmable ROM [UVEPROM] devices
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B82—NANOTECHNOLOGY
  • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
  • B82Y10/00—Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
  • H10D30/00—Field-effect transistors [FET]
  • H10D30/60—Insulated-gate field-effect transistors [IGFET]
  • H10D30/68—Floating-gate IGFETs
  • H10D30/6891—Floating-gate IGFETs characterised by the shapes, relative sizes or dispositions of the floating gate electrode
  • H10D30/6893—Floating-gate IGFETs characterised by the shapes, relative sizes or dispositions of the floating gate electrode wherein the floating gate has multiple non-connected parts, e.g. multi-particle floating gate
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
  • H10D64/00—Electrodes of devices having potential barriers
  • H10D64/01—Manufacture or treatment
  • H10D64/031—Manufacture or treatment of data-storage electrodes
  • H10D64/035—Manufacture or treatment of data-storage electrodes comprising conductor-insulator-conductor-insulator-semiconductor structures
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
  • H10D30/00—Field-effect transistors [FET]
  • H10D30/60—Insulated-gate field-effect transistors [IGFET]
  • H10D30/68—Floating-gate IGFETs
  • H10D30/681—Floating-gate IGFETs having only two programming levels
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S977/00—Nanotechnology
  • Y10S977/902—Specified use of nanostructure
  • Y10S977/932—Specified use of nanostructure for electronic or optoelectronic application
  • Y10S977/936—Specified use of nanostructure for electronic or optoelectronic application in a transistor or 3-terminal device
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S977/00—Nanotechnology
  • Y10S977/902—Specified use of nanostructure
  • Y10S977/932—Specified use of nanostructure for electronic or optoelectronic application
  • Y10S977/943—Information storage or retrieval using nanostructure

Definitions

• the present invention relates generally to semiconductor devices, and more particularly, to a semiconductor device having a nitridated oxide layer and method therefor.
• Non-volatile memory arrays require a relatively high voltage for programming and erasing operations.
• high voltage tolerant transistors that can withstand, for example, the relatively high programming and erase voltages are implemented at the same time as the array.
• the charge storage layer is formed prior to the formation of the high voltage transistor gate oxide. The subsequent formation of oxide layers may cause further oxidation of the insulating layers. Further oxidation in the non-volatile device may lead to an increase in the tunnel oxide thickness. Also, further oxidation may cause the nanocrystals to oxidize and shrink. Changing the charge storage layer may lead to the need for higher program and erase voltages. Also, changing the charge storage layer may lead to an undesirable change in program and erase threshold voltages.
• FIG. 1 illustrates a cross-sectional view of a portion of a semiconductor device having a tunnel oxide and charge storage layer in accordance with the present invention.
• FIG. 2 illustrates a cross-sectional view of a portion of the semiconductor device exposed to a nitriding ambient in accordance with the present invention.
• FIG. 3 illustrates a cross-sectional view of a portion of the semiconductor device after patterning of the charge storage region in accordance with the present invention.
• FIG. 4 illustrates a cross-sectional view of a portion of the semiconductor device after a gate dielectric is formed adjacent to the patterned charge storage region in accordance with the present invention.
• FIG. 5 illustrates a cross-sectional view of a portion of the semiconductor device after a polysilicon layer is formed in accordance with the present invention.
• FIG. 6 illustrates a cross-sectional view of a portion of the semiconductor device after gates are formed in the polysilicon layer accordance with the present invention.
• the present invention provides, in one form, a method for forming a semiconductor device comprising: providing a semiconductor substrate; forming a first insulating layer over a surface of the semiconductor substrate; forming a layer of nanocrystals over a surface of the first insulating layer; forming a second insulating layer over the layer of nanocrystals; applying a nitriding ambient to the second insulating layer; selectively removing portions of the layer of nanocrystals and the first and second insulating layers to expose the surface of the semiconductor substrate; and forming a third insulating layer over the exposed surface of the semiconductor substrate.
• the present invention provides a semiconductor device comprising: a semiconductor substrate; a first insulating layer formed over a surface of the semiconductor substrate; a patterned layer of nanocrystals formed over a surface of the first insulating layer; a second insulating layer formed over the layer of nanocrystals, the second insulating layer having a nitrogen content greater than or equal to two (2) atomic percent of the second insulating layer; and a third insulating layer formed on the surface of the semiconductor substrate and not over the first and second insulating layer.
• nitriding the second insulating layer By nitriding the second insulating layer, oxidation of the nanocrystals and the first insulating layer is reduced, thus reducing, or restricting, a change in oxide thickness when subsequent oxide layers are formed. Also, using nitridation instead of an oxidation barrier simplifies the manufacturing process.
• FIG. 1 illustrates a cross-sectional view of a portion of a semiconductor device 10 having a tunnel oxide 14 and charge storage stack 16 formed on a semiconductor substrate 12.
• the semiconductor substrate 12 may be formed from silicon.
• a first insulating layer 14 is formed over the substrate 12 which functions as the tunnel oxide for a non-volatile memory cell.
• the first insulating layer 14 may be silicon dioxide, nitrided oxide, or other high-k dielectric.
• the insulating layer 14 may be thermally grown or deposited, and the thickness may be on the order of 50 Angstroms.
• Charge storage stack 16 includes a plurality of discrete charge storage elements. In the illustrated embodiment, nanocrystals, represented by the small circles in charge storage layer 16, are used to form the plurality of discrete charge storage elements.
• nanocrystals are typically formed of silicon, but the discrete storage elements may also be formed of clusters of material consisting of, for example, germanium, silicon carbide, any number of metals, or any combination of these.
• the nanocrystals are preferably deposited by chemical deposition, but other processes may also be used. Other processes for forming nanocrystals include recrystallization of a thin amorphous layer of silicon and the deposition of prefabricated nanocrystals. Subsequent to nanocrystal formation, the nanocrystals may be passivated by oxidizing them using nitrous oxide.
• FIG. 2 illustrates a cross-sectional view of a portion of the semiconductor device 10 exposed to a nitriding ambient.
• the charge storage stack 16 includes the nanocrystals 13 surrounded by an oxide 15. Alternately, the charge storage stack 16 may formed by forming a plurality of relatively thin insulating layers, such as an insulating layer 17, over one another.
• the semiconductor device 10 is exposed to a nitriding ambient.
• the nitriding ambient includes one or more of ammonia, nitrous oxide, atomic nitrogen, or other nitrogen compounds.
• the process for exposing the semiconductor device 10 to the nitriding ambient may include one of plasma nitridation, thermal nitridation, or ion nitridation.
• the semiconductor device 10 is placed in a processing chamber having one or more of a plasma source, a thermal source or an ion source. Appropriate chambers are commercially available.
• the semiconductor device is exposed to a plasma 18 to provide a nitrogen content of greater than or equal to 2 atomic percent and preferably between 2 and 10 atomic percent.
• FIG. 3 illustrates a cross-sectional view of a portion of the semiconductor device 10 after patterning of the charge storage region 16 and first insulating layer 14 to form a patterned charge storage layer 20.
• a photo resist layer (not shown) is deposited over the charge storage region 16 and then patterned.
• the step of nitridation using a nitrogen containing plasma 19 may be accomplished after patterning instead of before patterning using one or more of a plasma source, a thermal source or an ion source as described above.
• FIG. 4 illustrates a cross-sectional view of a portion of the semiconductor device 10 after a gate dielectric 22 is formed adjacent to the patterned charge storage layer 20.
• the gate dielectric 22 may be one thickness throughout or may be different thicknesses to accommodate, for example, both high voltage transistors and logic circuits.
• FIG. 5 illustrates a cross-sectional view of a portion of the semiconductor device 10 after a polysilicon layer 24 is formed over the patterned charge storage layer 20 and the gate dielectric 22.
• FIG. 6 illustrates a cross-sectional view of a portion of the semiconductor device 10 after the polysilicon layer 24 is patterned and etched to form gate electrodes.
• Non-volatile memory cells 23 and 25 are representative of an array of non-volatile memory cells implemented on an integrated circuit. The non-volatile memory cells may be on a "standalone memory device or embedded with other circuitry, such as a central processing unit.
• Non-volatile memory cells 23 and 25 are formed by selectively etching charge storage layer 20, first insulating layer 14, and polysilicon layer 24.
• the gate electrodes 28 are formed from the polysilicon layer 24.
• the memory array requires additional circuitry, whether on not the memory array is embedded, to access the memory array, such as row and column decoders and input/output (I/O) circuits. Some of these additional circuits may be exposed to the relatively high programming and erase voltages and will therefore require thicker gate oxides than the circuits not exposed to the higher programming and erase voltages.
• Transistors 31 and 33 in FIG. 6 represent transistors necessary to implement the additional circuits.
• the nitridation of the patterned charge storage layer 20 prevents oxidation or shrinkage of the nanocrystals in memory cells 23 and 25 and an increase in the thickness of the first insulating layer 14.
• the nitridated second insulating layer 20 incorporates an oxidation barrier and thus provides a relatively simple process flow for manufacturing the semiconductor device 10.
• sidewall spacers and source/drain regions are typically sidewall spacers and source/drain regions.
• the side-wall spacers are formed by deposition of a layer of spacer material, followed by an anisotropic etch of the spacer material.
• the spacer material is typically nitride.
• the source/drain regions are typically diffused adjacent to the gate stack.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Nanotechnology (AREA)
• Physics & Mathematics (AREA)
• Mathematical Physics (AREA)
• Theoretical Computer Science (AREA)
• Crystallography & Structural Chemistry (AREA)
• Semiconductor Memories (AREA)
• Non-Volatile Memory (AREA)
• Formation Of Insulating Films (AREA)

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Publications (2)

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• 2005
  • 2005-01-26 US US11/043,827 patent/US7338894B2/en not_active Expired - Fee Related
  • 2005-12-16 JP JP2007552132A patent/JP5354907B2/ja not_active Expired - Fee Related
  • 2005-12-16 CN CNB2005800412072A patent/CN100541740C/zh not_active Expired - Fee Related
  • 2005-12-16 WO PCT/US2005/045731 patent/WO2006081005A2/en not_active Ceased
• 2006
  • 2006-01-04 TW TW095100397A patent/TWI377649B/zh not_active IP Right Cessation
• 2007
  • 2007-12-12 US US11/955,009 patent/US7781831B2/en not_active Expired - Fee Related

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