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WO2002041405A1 - Semiconductor device with reduced line-to-line capacitance and cross talk noise - Google Patents

Semiconductor device with reduced line-to-line capacitance and cross talk noise Download PDF

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Publication number
WO2002041405A1
WO2002041405A1 PCT/US2001/031199 US0131199W WO0241405A1 WO 2002041405 A1 WO2002041405 A1 WO 2002041405A1 US 0131199 W US0131199 W US 0131199W WO 0241405 A1 WO0241405 A1 WO 0241405A1
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WO
WIPO (PCT)
Prior art keywords
gate electrode
substrate
drain
field effect
effect transistor
Prior art date
Application number
PCT/US2001/031199
Other languages
French (fr)
Inventor
Manfred Horstmann
Karsten Wieczorek
Frederick N. Hause
Original Assignee
Advanced Micro Devices, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from DE10056868A external-priority patent/DE10056868A1/en
Application filed by Advanced Micro Devices, Inc. filed Critical Advanced Micro Devices, Inc.
Priority to JP2002543706A priority Critical patent/JP2004514294A/en
Priority to AU2001296630A priority patent/AU2001296630A1/en
Priority to EP01977517A priority patent/EP1334522A1/en
Priority to KR1020037006362A priority patent/KR100774600B1/en
Publication of WO2002041405A1 publication Critical patent/WO2002041405A1/en

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    • 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
    • H10D64/60—Electrodes characterised by their materials
    • H10D64/66—Electrodes having a conductor capacitively coupled to a semiconductor by an insulator, e.g. MIS electrodes
    • H10D64/671—Electrodes having a conductor capacitively coupled to a semiconductor by an insulator, e.g. MIS electrodes the conductor having lateral variation in doping or structure
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/28—Manufacture of electrodes on semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/268
    • H01L21/28008—Making conductor-insulator-semiconductor electrodes
    • H01L21/28017—Making conductor-insulator-semiconductor electrodes the insulator being formed after the semiconductor body, the semiconductor being silicon
    • H01L21/28247—Making conductor-insulator-semiconductor electrodes the insulator being formed after the semiconductor body, the semiconductor being silicon passivation or protection of the electrode, e.g. using re-oxidation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/52—Arrangements for conducting electric current within the device in operation from one component to another, i.e. interconnections, e.g. wires, lead frames
    • H01L23/522—Arrangements for conducting electric current within the device in operation from one component to another, i.e. interconnections, e.g. wires, lead frames including external interconnections consisting of a multilayer structure of conductive and insulating layers inseparably formed on the semiconductor body
    • H01L23/532—Arrangements for conducting electric current within the device in operation from one component to another, i.e. interconnections, e.g. wires, lead frames including external interconnections consisting of a multilayer structure of conductive and insulating layers inseparably formed on the semiconductor body characterised by the materials
    • H01L23/5329—Insulating materials
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
    • H10D30/00—Field-effect transistors [FET]
    • H10D30/01—Manufacture or treatment
    • H10D30/021—Manufacture or treatment of FETs having insulated gates [IGFET]
    • H10D30/0223—Manufacture or treatment of FETs having insulated gates [IGFET] having source and drain regions or source and drain extensions self-aligned to sides of the gate
    • H10D30/0227—Manufacture or treatment of FETs having insulated gates [IGFET] having source and drain regions or source and drain extensions self-aligned to sides of the gate having both lightly-doped source and drain extensions and source and drain regions self-aligned to the sides of the gate, e.g. lightly-doped drain [LDD] MOSFET or double-diffused drain [DDD] MOSFET
    • 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]
    • H10D30/601—Insulated-gate field-effect transistors [IGFET] having lightly-doped drain or source extensions, e.g. LDD IGFETs or DDD IGFETs 
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/0001—Technical content checked by a classifier
    • H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
    • 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
    • H10D64/20—Electrodes characterised by their shapes, relative sizes or dispositions 
    • H10D64/23—Electrodes carrying the current to be rectified, amplified, oscillated or switched, e.g. sources, drains, anodes or cathodes
    • H10D64/251—Source or drain electrodes for field-effect devices
    • H10D64/258—Source or drain electrodes for field-effect devices characterised by the relative positions of the source or drain electrodes with respect to the gate electrode

Definitions

  • the present invention relates to VLSI semiconductor devices and, particularly, relates to the problem of line-to-line capacitance and cross talk noise in semiconductor devices in ultra-high density circuits.
  • ICs integrated circuits
  • semiconductor devices such as insulated gate field effect transistors
  • feature sizes of the semiconductor devices are steadily decreasing. Decreasing feature sizes provide a variety of advantages, such as high package density and small rise and fall times during switching of the transistors due to reduced channel length.
  • advantages may be offset by certain disadvantages such as increased resistances of interconnects and higher coupling capacitances between adjacent lines when feature sizes are further decreased.
  • the increased resistance and/or the increase in capacitive coupling also slow the speed at which electrical signals propagate along the interconnects. This may be generally referred to as interconnect delay.
  • interconnect delay begins to dominate overall device delay in devices with feature sizes, e.g., gate lengths, on the order of 0.18 ⁇ m, so that device features of 0.18 ⁇ m and smaller will result in a deteriorated device performance, thereby restricting, for example, the clock frequency of CPUs.
  • feature sizes e.g., gate lengths
  • local interconnects i.e., connections which provide for contact to the drain and source regions of a field effect transistor.
  • the design rules in modern integrated circuits for example, in ultra-high density CMOS circuits, require small distances between the gate electrode and the local interconnects in the range of 10-250 nm. These distances are even smaller when slight misalignments occur in the formation of the openings for the respective local interconnects.
  • Figure la shows a schematic cross-sectional view of a field effect transistor device at a specific manufacturing stage.
  • shallow trans-isolations 2 define a transistor region.
  • a gate electrode 4 is formed over a substrate 1 and isolated therefrom by a gate insulation layer 3. Adjacent to the gate insulation layer 3, lightly doped regions 5 are formed.
  • the gate electrode 4 may be formed by DUV (deep ultraviolet) mask technology and, thereafter, the lightly doped regions 5 are formed by ion implantation.
  • Figure lb schematically shows a cross-sectional view of the field effect transistor in a more advanced manufacturing stage.
  • sidewall spacers 7 Adjacent to the sidewalk of the gate electrode 4, sidewall spacers 7 are formed and extend along a width dimension of the transistor, which is defined as the direction perpendicular to the drawing plane of Figure lb.
  • the lateral dimension of the gate electrode 4 is generally referred to as the length dimension.
  • the width of the gate electrode 4, i.e., the distance between the sidewall spacers 7 depicted in Figure lb is generally referred to as the gate length of the transistor.
  • drain and source regions 6 are formed. Formation of the sidewall spacers 7 may be performed by deposition of a silicon dioxide or a silicon nitride or a silicon oxynitride layer and subsequent anisotropic etch.
  • the dielectric constant "k" of these materials typically ranges from 3.9-6, depending on the type of deposition process used.
  • the highly doped source and drain regions 6 are formed by means of ion implantation and rapid thermal annealing as is well known to the skilled person.
  • Figure lc shows a schematic cross-sectional view of the transistor device in a further advanced manufacturing stage.
  • An interlayer of dielectric material 8 is formed over the structure and comprises openings 9 which at least partially expose the surface of the drain and source region, respectively.
  • the interlayer of dielectric material (ILD) 8 is deposited by chemical vapor deposition (CVD) from TEOS.
  • CVD chemical vapor deposition
  • CMP chemical mechanical polishing
  • the openings 9, in form of vias or lines are formed by using standard masking and etch techniques.
  • minor misalignments occur during the formation of the openings 9, so that, usually, the distances of the openings 9 to the gate electrode 4 are not exactly identical.
  • Figure Id schematically shows the transistor device of Figure lc with the openings 9 filled with a metal, such as tungsten, so as to provide electrical contact to the drain and source regions 6. Moreover, a further CMP process has been performed to level the surface of the ILD 8 and the metal in the openings 9. As the skilled person will appreciate, a thin barrier layer (not shown) may be deposited prior to filling the openings 9 with the metal.
  • a metal such as tungsten
  • the distances between the gate electrode 4 and the metal in the openings 9 is in the range of 10-250 nm in modern ultra-high density semiconductor circuits. This distance may even be smaller depending on the magnitude of any misalignment occurring during the formation of the openings 9.
  • the parasitic capacitance formed between the metal and the gate electrode is inversely proportional to the distance between the metal and the gate electrode and, thus, the time constant for switching the transistor device increases as the distance between the metal and the gate electrode decreases. Moreover, cross talk noise between the drain and source regions and the gate electrode also increases with a decreasing distance.
  • the advantages gained by steadily decreasing the transistor length, i.e., the gate length are, at least partially, nullified by the decreasing distance between source and drain lines and the gate electrode, thereby resulting in an increased parasitic capacitance and cross talk noise therebetween.
  • a field effect transistor device in an integrated circuit manufactured on a substrate, comprising a gate electrode having opposing sidewalk extending along a width direction of the transistor, the gate electrode being formed over a substrate and separated therefrom by a gate insulation layer, a drain line at least partially formed over a drain region, the drain line electrically connecting to the drain region, and a source line at least partially formed over a source region, the source line electrically connecting to the source region, the drain line and the source line being electrically insulated and spaced apart from the gate electrode by a sidewall spacer comprised of a material having a dielectric constant that is 3.5 or less.
  • a field effect transistor device in an integrated circuit manufactured on a substrate comprising a gate electrode having opposing sidewalk extending along a width direction of the transistor, the gate electrode being formed over a substrate and separated therefrom by a gate insulation layer, a drain line at least partially formed over a drain region, the drain line electrically connecting to the drain region, a source line at least partially formed over a source region, the source line electrically connecting to the source region, the drain line and the source line being electrically insulated and spaced apart from the gate electrode by a sidewall spacer, wherein a ratio of a distance between the drain line and the gate electrode and the dielectric constant of the sidewall spacer, and a ratio of a distance between the source line and the gate electrode and the dielectric constant of the sidewall spacer are equal or less than 0.35 nm "1 .
  • a method of manufacturing a field effect transistor comprising the steps of providing a substrate having a surface, forming an active region in the substrate, forming a gate electrode over the substrate, the gate electrode being electrically insulated from the substrate by a gate insulation layer, forming dielectric sidewall spacers adjacent the gate electrode and extending along the gate electrode in a width direction of the transistor, the sidewall spacers being comprised of a material having a dielectric constant that is 3.5 or less, forming a drain and a source region in the active region adjacent the gate electrode, depositing an insulating layer over the substrate, forming openings at least partially over the drain and source region, respectively, filling the openings with an electrically conductive material so as to form a drain line and a source line, wherein the sidewall spacers assist in electrically isolating and spatially separating the gate electrode from the drain line and the source line.
  • the capacitance between the drain region or the source region and the gate electrode is dependent on the dielectric constant "k" of the sidewall spacer material and is inversely proportional to the spacing of the drain line or the source line and the gate electrode, the increase of the capacitance by reducing said distance in ultra-high density integrated circuits can effectively be compensated by forming the sidewall spacers on the basis of a low k material.
  • the present invention provides field effect transistors having sidewall spacers formed of a material with a dielectric constant in the range of 3.5 to less than 1.3.
  • the present invention allows a further down-scaling of the transistor devices, thereby avoiding a deteriorated device performance caused by increased gate-to-source and/or gate-to-drain capacitance and cross talk noise.
  • Figure la schematically shows a cross-section of a field effect transistor device at a specific manufacturing stage
  • Figure lb schematically shows the cross-section of the field effect transistor device in an advanced manufacturing stage, depicting sidewall spacers formed according to a typical prior art process
  • Figure lc schematically shows a cross-section of the field effect transistor after depositing an interlayer of dielectric material and forming openings therein;
  • Figure Id schematically shows a cross-section of the field effect transistor at the manufacturing stage when drain and source lines are formed in the openings of the interlayer, illustrated in Figure lc;
  • Figure 2a shows a cross-sectional view of a field effect transistor at a specific manufacturing stage in accordance with the present invention.
  • Figure 2b schematically shows a cross-section of the field effect transistor of Figure 2a in a further advanced manufacturing stage.
  • FIG. 2a schematically shows a cross-section of a field effect transistor 200 at a specific manufacturing stage in accordance with the present invention.
  • shallow trench isolations 202 are formed in a substrate 201, which may be an appropriate semiconductor substrate, such as silicon or an insulating substrate, such as glass, and define an active region of the transistor 200.
  • a drain and a source region 206 with corresponding lightly doped regions 205 are formed in the active region of the transistor 200.
  • a gate electrode 204 is located over the active region of the transistor 200 and spaced apart therefrom by a gate insulation layer 203.
  • Sidewall spacers 207 are formed along the respective sidewalk of the gate electrode 204 and extend along the width direction of the transistor 200.
  • the process flow for forming the features of the field effect transistor 200 as depicted in Figure 2a may include the following steps. After standard gate formation, as described, for example, with reference to Figures la- Id, the lightly doped regions 205 are formed by ion implantation. Thereafter, the sidewall spacers 207 are formed by depositing a material having a dielectric constant of 3.5 or less.
  • HSQ and fluorinated oxides exhibit "k” values of 3.0 and 3.5, respectively, whereas organic polymers such as polyarylene exhibit “k” values below 3.0. "K.” values beyond 2.0 show nano porous silica films, porous polymers and P-TFE.
  • FIG. 2b schematically shows the field effect transistor 200 of Figure 2a in an advanced manufacturing stage.
  • an insulating layer 208 is formed, adjacent to which drain and source lines 210 are located.
  • the drain and source lines 210 may be formed as vias, lines, or both in combination, depending on design requirements.
  • the drain and source lines 210 may also be referred to as local interconnects.
  • the insulation layer 208 formed over the structure is then planarized and openings 209 are formed which partially expose the drain and source regions 206.
  • a thin barrier layer (not shown), such as a cobalt suicide or a titanium suicide layer, may be deposited so as to cover the surface of the openings 209.
  • the openings 209 are filled with a metal, such as tungsten, and the resulting structure is planarized by CMP.
  • the capacitance between the gate electrode 204 and the drain and the source line 210 is proportional to k/d, where "k" is the dielectric constant of the material positioned between the source and drain line 210 and the gate electrode 204. It should be noted that for obtaining absolute values the ratio k/d has to be multiplied by the electric field constant ⁇ 0 (8.8542 x 10 "12 As/Vm). Thus, a decreased distance "d” is compensated by a lower value of "k” according to the present invention, thereby allowing smaller distances "d” as in the prior art without deteriorating the performance of the transistor device.
  • the type of material and/or the type of deposition process for the low-k material may be selected to adjust the "k" value of the sidewall spacers 207 such that the ratio of the "k” value and the distance "d” to the source line, and the ratio of the "k” value and the distance “d” to the drain line, are both 0.35 nm “1 or less, or about 3.099 x 10 "3 As/Vm 2 or less, when absolute values are used.
  • the present invention suggests, for example, a dielectric material with a "k” equal to 3.5 or less for a minimal distance "d” of 10 nm, or a "k” of 2.8 for a "d” of 8 nm, etc.
  • the "k" value of the sidewall spacer material may be selected such that for a minimum distance "d," depending on design rule and process accuracy, the capacitance between gate electrode and drain and source line 210 is equal to or less than a constant times 3.099 x 10 "3 As Vm 2 for specified voltages applied to the gate, drain and source of the field effect transistor.
  • the present invention has been described with tungsten as the metal used for the drain and source lines 210, it should be noted, however, that any appropriate material, such as copper, aluminum, etc., may be employed. Moreover, the present invention is particularly useful in transistor devices having a gate length of 0.2 ⁇ m and less, since these transistor devices generally exhibit line to gate electrode distances of 250 nm and less.
  • the present invention is described with reference to field effect transistors formed on a semiconductor substrate, such as silicon, it is to be noted that the present invention may be applied to any field effect transistor formed on any appropriate substrate.
  • the field effect transistor may be formed as an SOI (silicon on oxide) device, or may be formed on an insulating substrate or other semiconductor substrates such as III-V or II- VI semiconductors.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Insulated Gate Type Field-Effect Transistor (AREA)
  • Electrodes Of Semiconductors (AREA)
  • Thin Film Transistor (AREA)

Abstract

A transistor device (200) is disclosed, having an insulating material disposed between the gate electrode (204) and the drain and source lines, wherein the dielectric constant of the insulating amterial is 3.5 or less. Accodingly, the capacitance between the gate electrode and the drain and source lines can be reduced, thereby improving signal performance of the field effect transistor (200) with decreased cross talk noise.

Description

SEMICONDUCTOR DEVICE WITH REDUCED LINE-TO-LINE CAPACITANCE AND CROSS TALK NOISE
TECHNICAL FIELD The present invention relates to VLSI semiconductor devices and, particularly, relates to the problem of line-to-line capacitance and cross talk noise in semiconductor devices in ultra-high density circuits.
BACKGROUND ART
The manufacturing process of integrated circuits (ICs) involves the fabrication of numerous semiconductor devices, such as insulated gate field effect transistors on a single substrate. In order to have increased integration density and improved device performance, for instance, with respect to signal processing time and power consumption, feature sizes of the semiconductor devices are steadily decreasing. Decreasing feature sizes provide a variety of advantages, such as high package density and small rise and fall times during switching of the transistors due to reduced channel length. However, these advantages may be offset by certain disadvantages such as increased resistances of interconnects and higher coupling capacitances between adjacent lines when feature sizes are further decreased. Moreover, the increased resistance and/or the increase in capacitive coupling also slow the speed at which electrical signals propagate along the interconnects. This may be generally referred to as interconnect delay.
Generally, interconnect delay begins to dominate overall device delay in devices with feature sizes, e.g., gate lengths, on the order of 0.18 μm, so that device features of 0.18 μm and smaller will result in a deteriorated device performance, thereby restricting, for example, the clock frequency of CPUs. In modern ultra-high density circuits, not only interconnect delay is an important issue, but also formation of local interconnects, i.e., connections which provide for contact to the drain and source regions of a field effect transistor. The design rules in modern integrated circuits, for example, in ultra-high density CMOS circuits, require small distances between the gate electrode and the local interconnects in the range of 10-250 nm. These distances are even smaller when slight misalignments occur in the formation of the openings for the respective local interconnects.
For the sake of clarity, a typical prior art process flow will be described with reference to Figures la and lb in order to detail some of the problems involved with the formation of local interconnects in modern integrated circuits. As the skilled person will easily appreciate, the figures depicting the prior art processing are merely of schematic nature, and transition and boundaries illustrated as sharp lines may not be imparted as sharp transitions in a real device. Furthermore, the description of the typical prior art process flow refers to standard manufacturing procedures without specifying typical parameter values used for these procedures, since the individual processing steps may be accordingly adapted to meet specific design requirements.
Figure la shows a schematic cross-sectional view of a field effect transistor device at a specific manufacturing stage. In a semiconductor substrate 1, shallow trans-isolations 2 define a transistor region. A gate electrode 4 is formed over a substrate 1 and isolated therefrom by a gate insulation layer 3. Adjacent to the gate insulation layer 3, lightly doped regions 5 are formed. As the skilled person will readily appreciate, the gate electrode 4 may be formed by DUV (deep ultraviolet) mask technology and, thereafter, the lightly doped regions 5 are formed by ion implantation. Figure lb schematically shows a cross-sectional view of the field effect transistor in a more advanced manufacturing stage. Adjacent to the sidewalk of the gate electrode 4, sidewall spacers 7 are formed and extend along a width dimension of the transistor, which is defined as the direction perpendicular to the drawing plane of Figure lb. The lateral dimension of the gate electrode 4, on the other hand, is generally referred to as the length dimension. For example, the width of the gate electrode 4, i.e., the distance between the sidewall spacers 7 depicted in Figure lb, is generally referred to as the gate length of the transistor. Furthermore, drain and source regions 6 are formed. Formation of the sidewall spacers 7 may be performed by deposition of a silicon dioxide or a silicon nitride or a silicon oxynitride layer and subsequent anisotropic etch. The dielectric constant "k" of these materials typically ranges from 3.9-6, depending on the type of deposition process used. After formation of the sidewall spacers 7, the highly doped source and drain regions 6 are formed by means of ion implantation and rapid thermal annealing as is well known to the skilled person.
Figure lc shows a schematic cross-sectional view of the transistor device in a further advanced manufacturing stage. An interlayer of dielectric material 8 is formed over the structure and comprises openings 9 which at least partially expose the surface of the drain and source region, respectively. A typical process flow for forming the openings 9 and the interlayer 8, generally referred to as Local Intercontact (LI) process sequence, typically includes the following steps. First, the interlayer of dielectric material (ILD) 8 is deposited by chemical vapor deposition (CVD) from TEOS. Next, the surface of the ILD 8 is planarized by performing a chemical mechanical polishing (CMP) process. Thereafter, the openings 9, in form of vias or lines, are formed by using standard masking and etch techniques. As can be seen in Figure lc, in general, minor misalignments occur during the formation of the openings 9, so that, usually, the distances of the openings 9 to the gate electrode 4 are not exactly identical.
Figure Id schematically shows the transistor device of Figure lc with the openings 9 filled with a metal, such as tungsten, so as to provide electrical contact to the drain and source regions 6. Moreover, a further CMP process has been performed to level the surface of the ILD 8 and the metal in the openings 9. As the skilled person will appreciate, a thin barrier layer (not shown) may be deposited prior to filling the openings 9 with the metal.
The distances between the gate electrode 4 and the metal in the openings 9 is in the range of 10-250 nm in modern ultra-high density semiconductor circuits. This distance may even be smaller depending on the magnitude of any misalignment occurring during the formation of the openings 9. The parasitic capacitance formed between the metal and the gate electrode is inversely proportional to the distance between the metal and the gate electrode and, thus, the time constant for switching the transistor device increases as the distance between the metal and the gate electrode decreases. Moreover, cross talk noise between the drain and source regions and the gate electrode also increases with a decreasing distance. As a consequence, in ultra-high density semiconductor circuits, the advantages gained by steadily decreasing the transistor length, i.e., the gate length, are, at least partially, nullified by the decreasing distance between source and drain lines and the gate electrode, thereby resulting in an increased parasitic capacitance and cross talk noise therebetween.
In view of the above, there exists a need for an improved field effect transistor device having a lower capacitance between its drain and source region and the gate electrode so as to improve device performance of ultra-high density semiconductor circuits. DISCLOSURE OF INVENTION
According to one aspect of the present invention, there is provided a field effect transistor device in an integrated circuit manufactured on a substrate, comprising a gate electrode having opposing sidewalk extending along a width direction of the transistor, the gate electrode being formed over a substrate and separated therefrom by a gate insulation layer, a drain line at least partially formed over a drain region, the drain line electrically connecting to the drain region, and a source line at least partially formed over a source region, the source line electrically connecting to the source region, the drain line and the source line being electrically insulated and spaced apart from the gate electrode by a sidewall spacer comprised of a material having a dielectric constant that is 3.5 or less. According to another aspect of the present invention, there is provided a field effect transistor device in an integrated circuit manufactured on a substrate, comprising a gate electrode having opposing sidewalk extending along a width direction of the transistor, the gate electrode being formed over a substrate and separated therefrom by a gate insulation layer, a drain line at least partially formed over a drain region, the drain line electrically connecting to the drain region, a source line at least partially formed over a source region, the source line electrically connecting to the source region, the drain line and the source line being electrically insulated and spaced apart from the gate electrode by a sidewall spacer, wherein a ratio of a distance between the drain line and the gate electrode and the dielectric constant of the sidewall spacer, and a ratio of a distance between the source line and the gate electrode and the dielectric constant of the sidewall spacer are equal or less than 0.35 nm"1. According to still another aspect of the present invention, there is provided a method of manufacturing a field effect transistor, comprising the steps of providing a substrate having a surface, forming an active region in the substrate, forming a gate electrode over the substrate, the gate electrode being electrically insulated from the substrate by a gate insulation layer, forming dielectric sidewall spacers adjacent the gate electrode and extending along the gate electrode in a width direction of the transistor, the sidewall spacers being comprised of a material having a dielectric constant that is 3.5 or less, forming a drain and a source region in the active region adjacent the gate electrode, depositing an insulating layer over the substrate, forming openings at least partially over the drain and source region, respectively, filling the openings with an electrically conductive material so as to form a drain line and a source line, wherein the sidewall spacers assist in electrically isolating and spatially separating the gate electrode from the drain line and the source line. Since the capacitance between the drain region or the source region and the gate electrode is dependent on the dielectric constant "k" of the sidewall spacer material and is inversely proportional to the spacing of the drain line or the source line and the gate electrode, the increase of the capacitance by reducing said distance in ultra-high density integrated circuits can effectively be compensated by forming the sidewall spacers on the basis of a low k material. Contrary to prior art devices containing sidewall spacers made of silicon oxide, silicon nitride or silicon oxynitride, having a dielectric constant k ranging from 3.9-6, the present invention provides field effect transistors having sidewall spacers formed of a material with a dielectric constant in the range of 3.5 to less than 1.3. Accordingly, the present invention allows a further down-scaling of the transistor devices, thereby avoiding a deteriorated device performance caused by increased gate-to-source and/or gate-to-drain capacitance and cross talk noise. BRIEF DESCRIPTION OF THE DRAWINGS
Further advantages and objects of the present invention will become more apparent with the following detailed description when taken with reference to the accompanying drawings in which:
Figure la schematically shows a cross-section of a field effect transistor device at a specific manufacturing stage;
Figure lb schematically shows the cross-section of the field effect transistor device in an advanced manufacturing stage, depicting sidewall spacers formed according to a typical prior art process;
Figure lc schematically shows a cross-section of the field effect transistor after depositing an interlayer of dielectric material and forming openings therein; Figure Id schematically shows a cross-section of the field effect transistor at the manufacturing stage when drain and source lines are formed in the openings of the interlayer, illustrated in Figure lc;
Figure 2a shows a cross-sectional view of a field effect transistor at a specific manufacturing stage in accordance with the present invention; and
Figure 2b schematically shows a cross-section of the field effect transistor of Figure 2a in a further advanced manufacturing stage.
While the present invention is described with reference to the embodiment as illustrated in the following detailed description as well as in the drawings, it should be understood that the following detailed description as well as the drawings are not intended to limit the present invention to the particular embodiment disclosed, but rather the described embodiment merely exemplifies the various aspects of the present invention, the scope of which is defined by the appended claims.
MODE(S) FOR CARRYING OUT THE INVENTION
Further advantages and objects of the present invention will become more apparent with the following detailed description and the appended claims. Furthermore, it is to be noted that although the present invention is described with reference to the embodiments as illustrated in the following detailed description, it should be noted that the following detailed description is not intended to limit the present invention to the particular embodiments disclosed, but rather the described embodiment merely exemplifies the various aspects of the present invention, the scope of which is defined by the appended claims.
Figure 2a schematically shows a cross-section of a field effect transistor 200 at a specific manufacturing stage in accordance with the present invention. In Figure 2a, shallow trench isolations 202 are formed in a substrate 201, which may be an appropriate semiconductor substrate, such as silicon or an insulating substrate, such as glass, and define an active region of the transistor 200. In the active region of the transistor 200, a drain and a source region 206 with corresponding lightly doped regions 205 are formed. A gate electrode 204 is located over the active region of the transistor 200 and spaced apart therefrom by a gate insulation layer 203. Sidewall spacers 207 are formed along the respective sidewalk of the gate electrode 204 and extend along the width direction of the transistor 200.
The process flow for forming the features of the field effect transistor 200 as depicted in Figure 2a may include the following steps. After standard gate formation, as described, for example, with reference to Figures la- Id, the lightly doped regions 205 are formed by ion implantation. Thereafter, the sidewall spacers 207 are formed by depositing a material having a dielectric constant of 3.5 or less. Suitable materials for a sidewall spacer 207 include silicon oxyfluoride (F-Si02j k = 2.6-3.5), hydrogen silsesquioxane (HSQ), fluorinated polyimide, parylene, polynaphtalene, polytetrafluoroethylene (P-TFE), methykikesquioxane (MSQ), perfluorcyclobutene, nano porous silica, and hybrid silsesquioxane. HSQ and fluorinated oxides exhibit "k" values of 3.0 and 3.5, respectively, whereas organic polymers such as polyarylene exhibit "k" values below 3.0. "K." values beyond 2.0 show nano porous silica films, porous polymers and P-TFE. These low "k" materials can be deposited by, for example, plasma enhanced CVD or high density plasma CVD. Since usually the type of deposition process affects the "k" value of the layer deposited, a variation of the low-k value of a specific material can be obtained by using a different deposition process or by changing parameter values of the deposition process, as is known from processing of previous spacer materials such as silicon oxide. Figure 2b schematically shows the field effect transistor 200 of Figure 2a in an advanced manufacturing stage. Over the gate electrode 204 and the sidewall spacers 207, an insulating layer 208 is formed, adjacent to which drain and source lines 210 are located. The drain and source lines 210 may be formed as vias, lines, or both in combination, depending on design requirements. As previously noted, the drain and source lines 210 may also be referred to as local interconnects. As previously described with reference to Figures la- Id, the insulation layer 208 formed over the structure is then planarized and openings 209 are formed which partially expose the drain and source regions 206. Thereafter, a thin barrier layer (not shown), such as a cobalt suicide or a titanium suicide layer, may be deposited so as to cover the surface of the openings 209. Next, the openings 209 are filled with a metal, such as tungsten, and the resulting structure is planarized by CMP. A distance 211, also referred to as distance "d," between the gate electrode 204 and the drain or the source line 210, depends on the precision of the alignment during the formation of the openings 209 for the drain and source lines 210. Since transistor length dimensions are steadily decreasing, the distance 211 in modern integrated circuits is typically in the range of 10-250 nm, and may even be smaller when a certain amount of misalignment occurs.
The capacitance between the gate electrode 204 and the drain and the source line 210 is proportional to k/d, where "k" is the dielectric constant of the material positioned between the source and drain line 210 and the gate electrode 204. It should be noted that for obtaining absolute values the ratio k/d has to be multiplied by the electric field constant ε0 (8.8542 x 10"12 As/Vm). Thus, a decreased distance "d" is compensated by a lower value of "k" according to the present invention, thereby allowing smaller distances "d" as in the prior art without deteriorating the performance of the transistor device. The type of material and/or the type of deposition process for the low-k material may be selected to adjust the "k" value of the sidewall spacers 207 such that the ratio of the "k" value and the distance "d" to the source line, and the ratio of the "k" value and the distance "d" to the drain line, are both 0.35 nm"1 or less, or about 3.099 x 10"3 As/Vm2 or less, when absolute values are used. This means, the present invention suggests, for example, a dielectric material with a "k" equal to 3.5 or less for a minimal distance "d" of 10 nm, or a "k" of 2.8 for a "d" of 8 nm, etc. Hence, according to the present invention, the "k" value of the sidewall spacer material may be selected such that for a minimum distance "d," depending on design rule and process accuracy, the capacitance between gate electrode and drain and source line 210 is equal to or less than a constant times 3.099 x 10"3 As Vm2 for specified voltages applied to the gate, drain and source of the field effect transistor.
Furthermore, although the present invention has been described with tungsten as the metal used for the drain and source lines 210, it should be noted, however, that any appropriate material, such as copper, aluminum, etc., may be employed. Moreover, the present invention is particularly useful in transistor devices having a gate length of 0.2 μm and less, since these transistor devices generally exhibit line to gate electrode distances of 250 nm and less.
Although the present invention is described with reference to field effect transistors formed on a semiconductor substrate, such as silicon, it is to be noted that the present invention may be applied to any field effect transistor formed on any appropriate substrate. For example, the field effect transistor may be formed as an SOI (silicon on oxide) device, or may be formed on an insulating substrate or other semiconductor substrates such as III-V or II- VI semiconductors.
The particular embodiments disclosed above are illustrative only, as the invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. For example, the process steps set forth above may be performed in a different order. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the invention. Accordingly, the protection sought herein is as set forth in the claims below.

Claims

1. A field effect transistor device (200) in an integrated circuit manufactured on a substrate, comprising: a gate electrode (204) having opposing sidewalk extending along a width direction of the transistor (200), the gate electrode (204) being formed over a substrate (201) and separated therefrom by a gate insulation layer (203); a drain line at least partially formed over a drain region, the drain line electrically connecting to the drain region; and a source line at least partially formed over a source region, the source line electrically connecting to the source region, said drain line and source line being electrically insulated and spaced apart from the gate electrode (204) by a sidewall spacer (207) comprised of a material having a dielectric constant that is 3.5 or less.
2. The field effect transistor device of claim 1, wherein the sidewall spacer (207) comprises one of the materials consisting of the group of silicon oxyfluoride, hydrogen silsesquioxane, fluorinated polyimide, parylene, polynaphtalene, polytetrafluoroethylene, methykilsesquioxane, perfluorcyclobutene, nano porous silica, and hybrid silsesquioxane.
3. The field effect transistor device of claim 1, wherein a length of the gate electrode is less than 0.2 μm.
4. The field effect transistor device of claim 1, wherein the drain line and the source line comprise one of tungsten, aluminum, and copper.
5. The field effect transistor of claim 1, wherein the substrate (201) is a semiconductor substrate.
6. A field effect transistor device (200) in an integrated circuit manufactured on a substrate, comprising: a gate electrode (204) having opposing sidewalk extending along a width direction of the transistor, the gate electrode (204) being formed over a substrate (201) and separated therefrom by a gate insulation layer (203); a drain line at least partially formed over a drain region, the drain line electrically connecting to the drain region; a source line at least partially formed over a source region, the source line electrically connecting to the source region, said drain line and source line being electrically insulated and spaced apart from the gate electrode by a dielectric sidewall spacer (207), wherein a ratio of a distance between the drain line and the gate electrode and a dielectric constant of the sidewall spacer (207) times the electric field constant ε0, and a ratio of a distance between the source line and the gate electrode and the dielectric constant of the sidewall spacer (207) times the electric field constant ε0 are equal or less than 3.099 x 10"3 As/Vm2.
7. The field effect transistor device (200) of claim 6, wherein the sidewall spacer comprises one of the materials consisting of the group silicon oxyfluoride, hydrogen silsesquioxane, fluorinated polyimide, parylene, polynaphtalene, polytetrafluoroethylene, methykilsesquioxane, perfluorcyclobutene, nano porous silica, and hybrid silsesquioxane.
8. The field effect transistor device of claim 6, wherein a length of the gate electrode is less than 0.2 μm.
9. The field effect transistor device of claim 6, wherein the drain line and the source line comprise one of tungsten, aluminum, and copper.
10. The field effect transistor of claim 6, wherein the substrate is a semiconductor substrate.
11. The field effect transistor of claim 6, wherein the substrate is an insulating substrate.
12. A method of manufacturing a field effect transistor, comprising the steps of: providing a substrate (201) having a surface; forming an active region in the substrate (201); forming a gate electrode (204) over the substrate (201), the gate electrode (204) being electrically insulated from the substrate (201) by a gate insulation layer (203); forming dielectric sidewall spacers (207) adjacent the gate electrode (204) and extending along the gate electrode in a width direction of the transistor, said sidewall spacers (207) comprised of a material having a dielectric constant that is equal or less than 3.5; forming a drain and a source region in the active region adjacent the gate electrode; depositing an insulating layer (208) over the substrate (201); forming openings at least partially over the drain and source region, respectively; and filling the openings with an electrically conductive material so as to form a drain line and a source line, wherein the sidewall spacers (207) assist in electrically isolating and spatially separating the gate electrode from the drain line and the source line.
13. The method of claim 12, wherein the sidewall spacer (207) comprises one of the materials consisting of the group silicon oxyfluoride, hydrogen silsesquioxane, fluorinated polyimide, parylene, polynaphtalene, polytetrafluoroethylene, methykilsesquioxane, perfluorcyclobutene, nano porous silica, and hybrid silsesquioxane.
14. The method of claim 12, wherein a length of the gate electrode (204) is less than 0.2 μm.
15. The method of claim 12, wherein the drain line and the source line comprise one of tungsten, aluminum, and copper.
16. The method of claim 12, wherein the substrate (201) is a semiconductor substrate.
17. The method of claim 12, wherein the substrate is an insulating substrate.
PCT/US2001/031199 2000-11-16 2001-10-04 Semiconductor device with reduced line-to-line capacitance and cross talk noise WO2002041405A1 (en)

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JP2002543706A JP2004514294A (en) 2000-11-16 2001-10-04 Semiconductor device with reduced line-to-line capacitance and crosstalk noise
AU2001296630A AU2001296630A1 (en) 2000-11-16 2001-10-04 Semiconductor device with reduced line-to-line capacitance and cross talk noise
EP01977517A EP1334522A1 (en) 2000-11-16 2001-10-04 Semiconductor device with reduced line-to-line capacitance and cross talk noise
KR1020037006362A KR100774600B1 (en) 2000-11-16 2001-10-04 Semiconductor devices with reduced line-to-line capacitance and crosstalk noise

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DE10056868.8 2000-11-16
DE10056868A DE10056868A1 (en) 2000-11-16 2000-11-16 Semiconductor device with reduced line capacitance and reduced crosstalk noise
US09/812,372 US6555892B2 (en) 2000-11-16 2001-03-20 Semiconductor device with reduced line-to-line capacitance and cross talk noise
US09/812,372 2001-03-20

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CN102456736A (en) * 2010-10-29 2012-05-16 上海宏力半导体制造有限公司 Channel-type field effect tube and preparation method thereof

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5472890A (en) * 1994-04-28 1995-12-05 Nec Corporation Method for fabricating an insulating gate field effect transistor
US5882983A (en) * 1997-12-19 1999-03-16 Advanced Micro Devices, Inc. Trench isolation structure partially bound between a pair of low K dielectric structures
US6107667A (en) * 1998-09-10 2000-08-22 Advanced Micro Devices, Inc. MOS transistor with low-k spacer to suppress capacitive coupling between gate and source/drain extensions
US6124177A (en) * 1999-08-13 2000-09-26 Taiwan Semiconductor Manufacturing Company Method for making deep sub-micron mosfet structures having improved electrical characteristics
US6137126A (en) * 1999-08-17 2000-10-24 Advanced Micro Devices, Inc. Method to reduce gate-to-local interconnect capacitance using a low dielectric constant material for LDD spacer

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5885871A (en) * 1997-07-31 1999-03-23 Stmicrolelectronics, Inc. Method of making EEPROM cell structure
US6271132B1 (en) * 1999-05-03 2001-08-07 Advanced Micro Devices, Inc. Self-aligned source and drain extensions fabricated in a damascene contact and gate process

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5472890A (en) * 1994-04-28 1995-12-05 Nec Corporation Method for fabricating an insulating gate field effect transistor
US5882983A (en) * 1997-12-19 1999-03-16 Advanced Micro Devices, Inc. Trench isolation structure partially bound between a pair of low K dielectric structures
US6107667A (en) * 1998-09-10 2000-08-22 Advanced Micro Devices, Inc. MOS transistor with low-k spacer to suppress capacitive coupling between gate and source/drain extensions
US6124177A (en) * 1999-08-13 2000-09-26 Taiwan Semiconductor Manufacturing Company Method for making deep sub-micron mosfet structures having improved electrical characteristics
US6137126A (en) * 1999-08-17 2000-10-24 Advanced Micro Devices, Inc. Method to reduce gate-to-local interconnect capacitance using a low dielectric constant material for LDD spacer

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of EP1334522A1 *

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JP2004514294A (en) 2004-05-13

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