EP0976153A1 - Pellicules dielectriques nanoporeuses a densite progressive, et leur procede de fabrication - Google Patents

Pellicules dielectriques nanoporeuses a densite progressive, et leur procede de fabrication

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Publication number
EP0976153A1
EP0976153A1 EP98914425A EP98914425A EP0976153A1 EP 0976153 A1 EP0976153 A1 EP 0976153A1 EP 98914425 A EP98914425 A EP 98914425A EP 98914425 A EP98914425 A EP 98914425A EP 0976153 A1 EP0976153 A1 EP 0976153A1
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EP
European Patent Office
Prior art keywords
dielectric constant
lines
substrate
silicon containing
porosity
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP98914425A
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German (de)
English (en)
Inventor
Stephen Wallace
Douglas M. Smith
Teresa Ramos
Kevin H. Roderick
James S. Drage
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Honeywell International Inc
Original Assignee
AlliedSignal Inc
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Publication date
Application filed by AlliedSignal Inc filed Critical AlliedSignal Inc
Publication of EP0976153A1 publication Critical patent/EP0976153A1/fr
Withdrawn legal-status Critical Current

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    • 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
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    • 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
    • H01L21/02104—Forming layers
    • H01L21/02107—Forming insulating materials on a substrate
    • H01L21/02109—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates
    • H01L21/02203—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates the layer being porous
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    • 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
    • H01L21/02104—Forming layers
    • H01L21/02107—Forming insulating materials on a substrate
    • H01L21/02109—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates
    • H01L21/02112—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer
    • H01L21/02123—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material containing silicon
    • H01L21/02126—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material containing silicon the material containing Si, O, and at least one of H, N, C, F, or other non-metal elements, e.g. SiOC, SiOC:H or SiONC
    • H—ELECTRICITY
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    • 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
    • H01L21/02104—Forming layers
    • H01L21/02107—Forming insulating materials on a substrate
    • H01L21/02109—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates
    • H01L21/02205—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates the layer being characterised by the precursor material for deposition
    • H01L21/02208—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates the layer being characterised by the precursor material for deposition the precursor containing a compound comprising Si
    • H01L21/02214—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates the layer being characterised by the precursor material for deposition the precursor containing a compound comprising Si the compound comprising silicon and oxygen
    • H01L21/02216—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates the layer being characterised by the precursor material for deposition the precursor containing a compound comprising Si the compound comprising silicon and oxygen the compound being a molecule comprising at least one silicon-oxygen bond and the compound having hydrogen or an organic group attached to the silicon or oxygen, e.g. a siloxane
    • H—ELECTRICITY
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    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02107—Forming insulating materials on a substrate
    • H01L21/02225—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer
    • H01L21/0226—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process
    • H01L21/02282—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process liquid deposition, e.g. spin-coating, sol-gel techniques, spray coating
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    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02107—Forming insulating materials on a substrate
    • H01L21/02296—Forming insulating materials on a substrate characterised by the treatment performed before or after the formation of the layer
    • H01L21/02318—Forming insulating materials on a substrate characterised by the treatment performed before or after the formation of the layer post-treatment
    • H01L21/02337—Forming insulating materials on a substrate characterised by the treatment performed before or after the formation of the layer post-treatment treatment by exposure to a gas or vapour
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    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02107—Forming insulating materials on a substrate
    • H01L21/02296—Forming insulating materials on a substrate characterised by the treatment performed before or after the formation of the layer
    • H01L21/02318—Forming insulating materials on a substrate characterised by the treatment performed before or after the formation of the layer post-treatment
    • H01L21/02343—Forming insulating materials on a substrate characterised by the treatment performed before or after the formation of the layer post-treatment treatment by exposure to a liquid
    • H—ELECTRICITY
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    • 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
    • H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
    • H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
    • H01L21/768—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics
    • H01L21/76801—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing
    • H01L21/7682—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing the dielectric comprising air gaps
    • H—ELECTRICITY
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    • 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
    • H01L23/5222—Capacitive arrangements or effects of, or between wiring layers
    • H—ELECTRICITY
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    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2221/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof covered by H01L21/00
    • H01L2221/10—Applying interconnections to be used for carrying current between separate components within a device
    • H01L2221/1005—Formation and after-treatment of dielectrics
    • H01L2221/1042—Formation and after-treatment of dielectrics the dielectric comprising air gaps
    • H01L2221/1047—Formation and after-treatment of dielectrics the dielectric comprising air gaps the air gaps being formed by pores in the dielectric
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    • 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

Definitions

  • the present invention relates to nanoporous dielectric films and to a process for their manufacture. Such films are useful in the production of integrated circuits.
  • nanoporous silica offers other advantages for microelectronics including thermal stability up to 900°C, small pore size ( « microelectronics features), use of materials, silica and precursors (e.g., TEOS), that are widely used in the semiconductor industry, the ability to tune dielectric constant over a wide range and deposition using similar tools as employed for conventional SOG processing.
  • Density (or the inverse, porosity) is the key nanoporous silica parameter controlling property of importance for dielectrics. Properties of nanoporous silica may be varied over a continuous spectrum from the extremes of an air gap at a porosity of 100% to dense silica with a porosity of 0%. As density increases, dielectric constant and mechanical strength increase but the pore size decreases. This suggests that the optimum density range for semiconductor applications is not the very low densities associated with K ⁇ 1 but rather, higher densities which yield higher strength and smaller pore size.
  • Nanoporous silica films can be fabricated by using a mixture of a solvent and a silica precursor which is deposited onto a silicon wafer by conventional methods of spincoating, dip-coating, etc.
  • the precursor polymerizes after deposition and the resulting layer is sufficiently strong such that it does not shrink during drying.
  • Film thickness and density/dielectric constant can be controlled independently by using a mixture of two solvents with dramatically different volatility. The more volatile solvent evaporates during and immediately after precursor deposition.
  • the silica precursor typically, a partially hydrolyzed and condensed product of TEOS, is polymerized by chemical and/or thermal means until it forms a gel layer. The second solvent is then removed by increasing the temperature.
  • a gel is a substance that contains a continuous solid skeleton enclosing a continuous liquid phase.
  • the term "gel” as used herein means an open-pored solid structure enclosing a pore fluid.
  • nanoporous silica with a relatively lower density, and hence lower dielectric constant, for the insulator between metal lines and a higher density, stronger, porous layer on top of the lines.
  • this can be accomplished by performing multiple depositions using precursors with different solvent/silica ratios.
  • that approach has a high cost because of the multiple deposition and drying/baking steps that must be used.
  • the invention provides a multidensity nanoporous dielectric coated substrate which comprises a substrate, a plurality of raised lines on the substrate, a relatively high porosity, low dielectric constant, silicon containing polymer composition positioned between the raised lines and a relatively low porosity, high dielectric constant, silicon 5 containing polymer composition positioned on top of the lines.
  • the invention further provides a semiconductor device which comprises a substrate, a plurality of raised lines on the substrate, a relatively high porosity, low dielectric constant, nanoporous, dielectric silicon containing polymer composition positioned l o between the raised lines and a relatively low porosity, high dielectric constant, nanoporous, dielectric silicon containing polymer composition positioned on top of the lines.
  • the invention also provides a process for forming a multidensity nanoporous dielectric 15 coating on a substrate having raised pattern lines which comprises a) blending at least one alkoxysilane with a relatively high volatility solvent composition, a relatively low volatility solvent composition and optional water thus forming a mixture and causing a partial hydrolysis and partial condensation of the alkoxysilane; 20 b) depositing the mixture onto a substrate having a raised pattern of lines such that the mixture is positioned both between the lines and on the lines, while evaporating at least a portion of the relatively high volatility solvent composition; c) exposing the mixture to a water vapor and a base vapor; and d) evaporating the relatively low volatility solvent composition, thereby forming a 25 relatively high porosity, low dielectric constant, silicon containing polymer composition positioned between the raised lines and a relatively low porosity, high dielectric constant, silicon containing polymer composition positioned on top of the lines.
  • a nanoporous silica film can be produced with two regions of density.
  • a nanoporous silica with a relatively lower density, lower dielectric constant insulator is produced between metal lines and a relatively higher density, higher dielectric constant, denser porosity layer is formed on top of the lines.
  • the dielectric constant of the insulation is controlled, by controlling the number and type of alkoxy groups on silica oligomers (i.e., the silicon containing polymer). These alkoxy groups are removed at a certain point in the process in order to obtain a lower density, lower dielectric constant in the portion of the film which is in the trenches between metal lines.
  • Figure 1 is a schematic representation of a substrate having a pattern of metal lines.
  • Figure 2 is a schematic representation of the patterned substrate coated with an alkoxysilane composition before reaction.
  • Figure 3 is a schematic representation of the patterned and coated substrate after reaction.
  • the invention forms a reaction product of at least one alkoxysilane with a relatively high volatility solvent composition, a relatively low volatility solvent composition, optional water and an optional catalytic amount of an acid.
  • This reaction product is applied onto a substrate having raised lines, such as metal or oxide lines in such a manner that the blend is deposited both between the lines and on top of the lines.
  • the high volatility solvent evaporates during and immediately after deposition of the reaction product.
  • the reaction product is further hydrolyzed and condensed until it forms a gel layer and the portion on top of the lines shrinks.
  • the metal lines support the gel and hinder gel shrinkage between the lines, thus producing a relatively less dense, higher porosity, lower dielectric constant silica between the lines. However, the gel on top of the lines is not so supported and shrinks.
  • This shrinkage produces a relatively denser, lower porosity, higher dielectric constant silica on top of the metal lines. Assuming that no shrinkage occurs after gelation, the density/dielectric constant of the top film is fixed by the volume ratio of low volatility solvent to silica. The second solvent is then removed by increasing the temperature.
  • Useful alkoxysilanes for this invention include those which have the formula:
  • R groups are independently Ci to C 4 alkoxy groups and the balance, if any, are independently selected from the group consisting of hydrogen, alkyl, phenyl, halogen, substituted phenyl.
  • alkoxy includes any other organic group which can be readily cleaved from silicon at temperatures near room temperature by hydrolysis.
  • R groups can be ethylene glycoxy or propylene glycoxy or the like, but preferably all four R groups are methoxy, ethoxy, propoxy or butoxy.
  • the most preferred alkoxysilanes nonexclusively include tetraethoxysilane (TEOS) and tetramethoxysilane.
  • the alkoxysilane is reacted with a relatively high volatility solvent composition, a relatively low volatility solvent composition, optional water and optional catalytic amount of an acid. Water is included to provide a medium for hydrolyzing the alkoxysilane.
  • the relatively low volatility solvent composition is one which evaporates at a temperature below, preferably significantly below that of the relatively low volatility solvent composition.
  • the relatively high volatility solvent composition preferably has a boiling point of about 120 °C or less, preferably about 100 °C or less.
  • Suitable high volatility solvent composition nonexclusively include methanol, ethanol, n-propanol, isopropanol, n-butanol and mixtures thereof.
  • Other relatively high volatility solvent compositions which are compatible with the other ingredients can be readily determined by those skilled in the art.
  • the relatively high volatility solvent composition is one which evaporates at a temperature above, preferably significantly above that of the relatively high volatility solvent composition.
  • the relatively low volatility solvent composition preferably has a boiling point of about 175 °C or more, preferably about 200 °C or more .
  • Suitable low volatility solvent compositions nonexclusively include alcohols and polyols including glycols such as ethylene glycol, 1,4-butylene glycol, 1,5-pentanediol, 1,2,4-butanetriol, 1,2,3-butanetriol, 2-methyl-propanetriol, 2-(hydroxymethyl)-l,3-propanediol, 1,4,1,4- butanediol, 2-methyl-l,3-propanediol, tetraethylene glycol, triethylene glycol monomethyl ether, glycerol and mixtures thereof.
  • Other relatively low volatility solvent compositions which are compatible with the other ingredients can be readily determined by those skilled in the art.
  • the optional acid serves to catalyze the reaction of the alkoxysilane with the relatively high volatility solvent composition, a relatively low volatility solvent composition and water.
  • Suitable acids are nitric acid and compatible organic acids which are volatile, i.e. which evaporate from the resulting reaction product under the process operating conditions, and which do not introduce impurities into the reaction product.
  • the alkoxysilane component is preferably present in an amount of from about 3 % to about 50 % by weight of the overall blend. A more preferred range is from about 5 % to about 45 % and most preferably from about 10 % to about 40 %.
  • the high volatility solvent composition component is preferably present in an amount of from about 20 % to about 90 % by weight of the overall blend. A more preferred range is from about 30 % to about 70 % and most preferably from about 40 % to about 60 %.
  • the low volatility solvent composition component is preferably present in an amount of from about 1 to about 40 % by weight of the overall blend. A more preferred range is from about 3 % to about 30 % and most preferably from about 5 % to about 20 %.
  • the mole ratio of water to silane is preferably from about 0 to about 50. A more preferred range is from about 0.1 to about 10 and most preferably from about 0.5 to about 1.5.
  • the acid is present in a catalytic amount which can be readily determined by those skilled in the art.
  • the molar ratio of acid to silane ranges from about 0 to about 0.2, more preferably from about 0.001 to about 0.05, and most preferably from about 0.005 to about 0.02.
  • the alkoxysilane containing composition is then coated on a substrate having a pattern of lines on its surface and forms a dielectric film on the surface.
  • a substrate 2 having an array of patterned lines 4 is applied with a layer 6 of the silica precursor composition.
  • the layer 6 is relatively uniformly applied so that it is positioned both between and on top of the lines 6.
  • the lines are lithographically formed and may be composed of a metal, an oxide, a nitride or an oxynitride. Suitable materials include silica, silicon nitride, titanium nitride, tantalum nitride, aluminum, aluminum alloys, copper, copper alloys, tantalum, tungsten and silicon oxynitride. These lines form the conductors or insulators of an integrated circuit.
  • the higher volatility layer is then partially evaporated.
  • the more volatile solvent evaporates over a period of seconds or minutes resulting in film shrinkage.
  • the film is a viscous liquid of the silica precursors and the less volatile solvent.
  • Slightly elevated temperatures may optionally be employed to accelerate this step. Such temperatures may range from about 20 °C to about 80 °C, preferably range from about 20 °C to about 50 °C and more range from about 20 °C to about 35 °C .
  • Typical substrates are those suitable to be processed into an integrated circuit or other microelectronic device.
  • Suitable substrates for the present invention non-exclusively include semiconductor materials such as gallium arsenide (GaAs), silicon and compositions containing silicon such as crystalline silicon, polysilicon, amorphous silicon, epitaxial silicon, and silicon dioxide (SiO 2 ) and mixtures thereof.
  • GaAs gallium arsenide
  • silicon compositions containing silicon such as crystalline silicon, polysilicon, amorphous silicon, epitaxial silicon, and silicon dioxide (SiO 2 ) and mixtures thereof.
  • On the surface of the substrate is a pattern of raised lines, such as metal, oxide, nitride or oxynitride lines which are formed by well known lithographic techniques. Such are typically closely separated from one another at distances of about 20 micrometers or less, preferably 1 micrometer or less, and more preferably from about 0.05 to about 1 micrometer.
  • the coating is exposed to both a water vapor and a base vapor.
  • the base vapor may be introduced first followed by the water vapor or both the water vapor and the base vapor may be introduced simultaneously.
  • the water vapor causes a continued hydrolysis of the alkoxysilane alkoxy groups, and the base catalyzes condensation of the hydrolyzed alkoxysilane and serves to increase molecular weight until the coating gels and ultimately increases gel strength.
  • the coating between the lines is constrained and supported by the lines and hence does not substantially shrink and forms a relatively less dense, high porosity, low dielectric constant material.
  • the silicon containing polymer composition between the lines preferably has a dielectric constant of from about 1.1 to about 2.5, more preferably from about 1.1 to about 2.2, and most preferably from about 1.5 to about 2.0.
  • the pore size ranges from about 2 run to about 200 nm, more preferably from about 5 nm to about 50 nm, and most preferably from about 10 nm to about 30 nm.
  • the density of the silicon containing composition, including pores ranges from about 0.1 to about 1.2 g/cm 2 , more preferably from about 0.25 to about 1 g/cm 2 , and most preferably from about 0.4 to about 0.8 g/cm 2 .
  • the coating above the lines is not constrained and hence shrinks and densities to a low porosity material. If the condensation rate is much faster than hydrolysis, a significant number of alkoxy groups will remain after the gel point. If little hydrolysis has occurred, then the film will not shrink and still maintains the same thickness as at the coating step. Continued exposure to basic water vapor results in continued hydrolysis of alkoxy groups forming silanols and the generation of volatile alcohols. These product alcohols leave the coating film causing shrinkage in the region above the lines in contrast to the gel in the trenches between lines which is constrained by the walls and bottom of the trench by adhesion to the walls, does not shrink and hence produces a high porosity material.
  • the film is then dried in a conventional way by solvent evaporation of the less volatile solvent with no further shrinkage.
  • Elevated temperatures may be employed to dry the coating in this step. Such temperatures may range from about 20 °C to about 450 °C, preferably from about 50 °C to about 350 °C and more preferably from about 175 °C to about 320 °C.
  • a relatively high porosity, low dielectric constant, silicon containing polymer composition forms between the raised lines and a relatively low porosity, high dielectric constant, silicon containing polymer composition is formed on the lines.
  • the silicon containing polymer composition on top of the lines preferably has a dielectric constant of from about 1.3 to about 3.5, more preferably from about 1.5 to about 3.0, and most preferably from about 1.8 to about 2.5.
  • the dielectric constant of the silicon containing polymer composition between the lines is at least about .2 less than the dielectric constant of the silicon containing polymer composition on top of the lines.
  • the pore size of silica composition on top of the lines ranges from about 1 nm to about 100 nm, more preferably from about 2 nm to about 30 nm, and most preferably from about 3 nm to about 20 nm.
  • the density of the silicon containing composition on top of the lines, including the pores, ranges from about 0.25 to about 1.9 g/cm 2 , more preferably from about 0.4 to about 1.6 g/cm 2 , and most preferably from about 0.7 to about 1.2 g/cm 2 .
  • Figure 3 shows a zone 8 of relatively high density, low porosity, high dielectric constant silica formed on the lines 4 and a zone 10 of relatively high porosity, low density, low dielectric constant silica formed between lines 4.
  • the area 8 above the lines 4 is contracted as compared to Figure 2.
  • the density difference is controlled by the degree of hydrolysis of alkoxy groups after the film has gelled.
  • alkoxy group size can be controlled by different alcohols such as methanol, ethanol, n-propanol, isopropanol, or diols such as ethylene glycol or propylene glycol or any other organic group which can be readily cleaved from silicon at temperatures near room temperature by hydrolysis.
  • the number of groups can be controlled by the relative concentrations of water and precursor alcohols in the starting reaction mass as well as the time- temperature-concentration of water vapor and base vapor applied to the film after deposition.
  • Suitable bases for use in the base vapor nonexclusively include ammonia and amines, such as primary, secondary and tertiary alkyl amines, aryl amines, alcohol amines and mixtures thereof which have a boiling point of about 200 °C or less, preferably 100 °C or less and more preferably 25 °C or less.
  • Preferred amines are methyl amine, dimethyl amine, trimethyl amine, n-butyl amine, n-propyl amine, tetramethyl ammonium hydroxide, piperidine and 2-methoxyethyl amine.
  • the pK b of the base may range from about less than 0 to about 9. A more preferred range is from about 2 to about 6 and most preferably from about 4 to about 5.
  • the mole ratio of water vapor to base vapor ranges from about 1:3 to about 1 :100, preferably from about 1:5 to about 1 :50, and more preferably from about 1: 10 to about 1:30.
  • the silica polymer polymerizes and gels with significant concentration of alkoxy groups remaining on the internal silica surface. After hydrolysis, the alkoxy groups hydrolyze and the product alcohol evaporates. If the gel is unconstrained, it will shrink and if it is constrained in a trench, it will not shrink and yield lower density/dielectric constant.
  • the dielectric constant (density) in the low density gap region depends on the target dielectric constant formulation which is fixed by the pore control solvent to silica volumetric ration, the size of the alkoxy groups and the ratio of alkoxy groups per silicon atoms at the point when the silica polymer has gelled. This is calculated for three common alkoxy groups (methoxy, ethoxy, and n-butoxy) for three different target dielectric constants and a range of OR/Si mole ratios and is shown below. When the mole ratio of OR/Si is near zero, as in conventional processing there is no differential shrinkage. However, when processed according to this invention, the OR/Si ratio at the gelation point is between 0.2 and 2.
  • the OR/Si ratio is one, one uses ethoxy groups, and the target dielectric constant is 2.5, significant differential dielectric constants will be observed.
  • the value on the top (unconstrained) is 2.5 and the value of the dielectric constant in the gaps will be 1.75.
  • the extent of differential dielectric constant increases. The extent of shrinkage after gelation and before final cure is a good measure of the volume change from dealkoxylation.
  • This example illustrates a process wherein no discernible differential density is observed for a film with a target top layer dielectric constant K of 1.3.
  • a precursor is reacted with water and base before deposition which reduces the OR: Si ratio, and deposited onto a patterned wafer, aged for 3 minutes, solvent exchanged, and dried.
  • a precursor was synthesized by adding 61.0 mL of tetraethoxy silane, 61.0 mL of tetraethylene glycol, 4.87 mL of deionized water, and 0.2 mL of IN nitric acid together in a round bottom flask. The solution was allowed to mix vigorously then heated to -80 °C and refluxed for 1.5 hours to form a solution. After the solution was allowed to cool, the solution was diluted with ethanol to reduce the viscosity and achieve a desirable thickness. The diluted precursor was filtered to 0.1 ⁇ m using a teflon filter.
  • the precursor was pre-catalyzed by adding 1 mL of 0.5M ammonium hydroxide to 10 ml of the above solution and mixed for -15 seconds. Approximately 3.0 ml of this pre-catalyzed precursor was deposited onto a 6 inch patterned wafer on a spin chuck, and spun on at 2500 rpm for 30 seconds to form films. The films were aged for 10.0 min. statically by adding 1 ml of 15M ammonium hydroxide to the bottom of a petri dish. A film is placed on a stand in the petri dish and the dish is covered. Water and ammonia from the base are evaporated in the dish and allowed to diffuse into the film to promote gelation.
  • the films were then solvent exchanged in a two step process by which -20 mL of ethanol was spun on the film at 250 rpm for 10 seconds without allowing the film to dry. Approximately 20 mL of hexamethyldisilazane was immediately spun on the film at 250 rpm for 10 seconds.
  • the films were heated at elevated temperatures for 1 min. each at 175 °C and 320 °C in air.
  • the films were cleaved to 1 inch squares and inspected by scanning electron microscopy (SEM). SEM photographs were taken at magnifications between 10,000X and 50,000X in between the patterned lines to observe the density throughout the film. No discernible density gradient was observed in the SEM photos.
  • EXAMPLE 2 This example illustrates a process wherein a very slight differential density is observed for a film with a target top layer dielectric constant K of 1.3. A precursor is deposited onto a patterned wafer, aged for 3 minutes, solvent exchanged, and dried.
  • a precursor was synthesized by adding 61.0 mL of tetraethoxysilane, 61.0 mL of tetraethylene glycol, 4.87 mL of deionized water, and 0.2 mL of IN nitric acid together in a round bottom flask. The solution was allowed to mix vigorously then heated to -80 °C and refluxed for 1.5 hours to form a solution. After the solution was allowed to cool, the solution was diluted with ethanol to reduce the viscosity and achieve a desirable thickness. The diluted precursor was filtered to 0.1 ⁇ m using a teflon filter.
  • Approximately 3.0 ml of the precursor was deposited onto a 6 inch patterned wafer on a spin chuck, and spun on at 2500 rpm for 30 seconds.
  • the films were aged for 10.0 min. statically by adding 1 ml of 15M ammonium hydroxide to the bottom of a petri-dish. A film is placed on a stand in the petri-dish and the dish is covered. Water and ammonia from the base are evaporated in the dish and allowed to diffuse into the film to promote aging.
  • the films were then solvent exchanged in a two step process by which -20 mL of ethanol was spun on the film at 250 rpm for 10 seconds without allowing the film to dry.
  • This example illustrates a process wherein no discernible differential density is observed for a film with a target top layer dielectric constant K of 1.8.
  • the precursor is reacted with water and base before deposition which reduces the OR: Si ratio, and deposited onto a patterned wafer, aged for 3 minutes, solvent exchanged, and dried.
  • a precursor was synthesized by adding 208.0 mL of tetraethoxysilane, 61.0 mL of tetraethylene glycol, 16.8 mL of deionized water, and 0.67 mL of IN nitric acid together in a round bottom flask. The solution was allowed to mix vigorously then heated to -80 °C and refluxed for 1.5 hours to form a solution. After the solution was allowed to cool, the solution was diluted with ethanol to reduce the viscosity and achieve a desirable thickness. The diluted precursor was filtered to 0.1 ⁇ m using a teflon filter.
  • the precursor was pre-catalyzed by adding 1 mL of 0.5M ammonium hydroxide to 10 ml of the above solution and mixed for -15 seconds. Approximately 3.0 ml of this pre-catalyzed precursor was deposited onto a 6 inch patterned wafer on a spin chuck, and spun on at 2500 rpm for 30 seconds. The films were aged for 10.0 min. statically by adding 1 ml of 15M ammonium hydroxide to the bottom of a petri- dish. A film is placed on a stand in the petri-dish and the dish is covered. Water and ammonia from the base are evaporated in the dish and allowed to diffuse into the film to promote aging.
  • the films were then solvent exchanged in a two step process by which -20 mL of ethanol was spun on the film at 250 rpm for 10 seconds without allowing the film to dry. Approximately 20 mL of hexamethyldisilazane was immediately spun on the film at 250 rpm for 10 seconds.
  • the films were heated at elevated temperatures for 1 min. each at 175 °C and 320 °C in air.
  • the films were cleaved to 1 inch squares and inspected by scanning electron microscopy (SEM). SEM photographs were taken at magnifications between 10,000X and 50,000X in between the patterned lines to observe the density throughout the film. No discernible density gradient was observed in the SEM photos
  • EXAMPLE 4 This example illustrates a process wherein a pronounced differential density is observed for a film with a target top layer dielectric constant K of 1.8.
  • the precursor is deposited onto a patterned wafer, aged for 3 minutes, solvent exchanged, and dried.
  • a precursor was synthesized by adding 208.0 mL of tetraethoxysilane, 61.0 mL of tetraethylene glycol, 16.8 mL of deionized water, and 0.67 mL of IN nitric acid together in a round bottom flask. The solution was allowed to mix vigorously then heated to -80 °C and refluxed for 1.5 hours to form a solution. After the solution was allowed to cool, the solution was diluted with ethanol to reduce the viscosity and achieve a desirable thickness. The diluted precursor was filtered to 0.1 ⁇ m using a teflon filter.
  • Approximately 3.0 ml of precursor was deposited onto a 6 inch patterned wafer on a spin chuck, and spun on at 2500 rpm for 30 seconds.
  • the films were aged for 10.0 min. statically by adding 1 ml of 15M ammonium hydroxide to the bottom of a petri-dish. A film is placed on a stand in the petri-dish and the dish is covered. Water and ammonia from the base are evaporated in the dish and allowed to diffuse into the film to promote aging.
  • the films were then solvent exchanged in a two step process by which -20 mL of ethanol was spun on the film at 250 rpm for 10 seconds without allowing the film to dry.
  • the films were heated at elevated temperatures for 1 min. each at 175 °C and 320 °C in air. Focus Ion Beam (FIB) analysis was done to minimize damage as a result of cleaving the sample during sample preparation.
  • the films were then inspected by scanning electron microscopy (SEM). SEM photographs were taken at magnifications between 10,000X and 50,000X in between the patterned lines to observe the density throughout the film. The films showed a pronounced difference in density. The material in between the lines showed a much lower density then the material on top of the lines.
  • SEM scanning electron microscopy
  • a silicon containing polymer composition having a low density is formed between patterned lines on a semiconductor substrate while the silicon containing polymer composition on top of the lines has a high density.

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  • Microelectronics & Electronic Packaging (AREA)
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  • Manufacturing & Machinery (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Formation Of Insulating Films (AREA)
  • Internal Circuitry In Semiconductor Integrated Circuit Devices (AREA)
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Abstract

L'invention concerne des pellicules diélectriques nanoporeuses (10) et leur procédé de fabrication. Un substrat présentant à sa surface une pluralité de lignes en relief (4) est revêtu d'une composition polymère (10) contenant du silicium, ayant une porosité relativement élevée et une constante diélectrique basse, positionnée entre lesdites lignes (4), et d'une composition contenant du silicium (8), ayant une porosité relativement basse et une constante diélectrique élevée, positionnée sur lesdites lignes (4).
EP98914425A 1997-04-17 1998-04-02 Pellicules dielectriques nanoporeuses a densite progressive, et leur procede de fabrication Withdrawn EP0976153A1 (fr)

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US4326197P 1997-04-17 1997-04-17
US43261P 1997-04-17
US4647498A 1998-03-25 1998-03-25
US46474 1998-03-25
PCT/US1998/006492 WO1998047177A1 (fr) 1997-04-17 1998-04-02 Pellicules dielectriques nanoporeuses a densite progressive, et leur procede de fabrication

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KR (1) KR20010006553A (fr)
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US6042994A (en) * 1998-01-20 2000-03-28 Alliedsignal Inc. Nanoporous silica dielectric films modified by electron beam exposure and having low dielectric constant and low water content
US6231989B1 (en) 1998-11-20 2001-05-15 Dow Corning Corporation Method of forming coatings
US6306778B1 (en) * 1999-08-31 2001-10-23 Tokyo Electron Limited Substrate processing method
US6465365B1 (en) * 2000-04-07 2002-10-15 Koninklijke Philips Electronics N.V. Method of improving adhesion of cap oxide to nanoporous silica for integrated circuit fabrication
US6495479B1 (en) 2000-05-05 2002-12-17 Honeywell International, Inc. Simplified method to produce nanoporous silicon-based films
KR100382702B1 (ko) * 2000-09-18 2003-05-09 주식회사 엘지화학 유기실리케이트 중합체의 제조방법
WO2002031596A1 (fr) 2000-10-12 2002-04-18 University Of North Carolina At Chapel Hill Photoresists soumis a des traitements au co2, polymeres et composes photoactifs utilises en microlithographie
US20020076543A1 (en) * 2000-12-19 2002-06-20 Sikonia John G. Layered dielectric nanoporous materials and methods of producing same
AU2002251769A1 (en) * 2002-01-03 2003-09-04 Honeywell International Inc. Nanoporous dielectric films with graded density and process for making such films
WO2003088344A1 (fr) * 2002-04-10 2003-10-23 Honeywell International, Inc. Dielectrique en silice poreuse, a faible teneur en metal, pour applications sur des circuits integres
JP2006500769A (ja) * 2002-09-20 2006-01-05 ハネウェル・インターナショナル・インコーポレーテッド 低ｋ材料用の中間層接着促進剤
JP4493278B2 (ja) * 2003-02-20 2010-06-30 富士通株式会社 多孔性樹脂絶縁膜、電子装置及びそれらの製造方法
US7030468B2 (en) * 2004-01-16 2006-04-18 International Business Machines Corporation Low k and ultra low k SiCOH dielectric films and methods to form the same
JP2010131700A (ja) * 2008-12-04 2010-06-17 Sony Corp 微粒子構造体／基体複合部材及びその製造方法

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DE69128073T2 (de) * 1990-08-23 1998-02-26 Univ California As Represented Verfahren zur herstellung von metalloxidaerogelen mit dichte weniger als 0,02 g/cm3
JP4014234B2 (ja) * 1994-05-27 2007-11-28 テキサス インスツルメンツ インコーポレイテツド 半導体デバイス中に線間容量の低減化された相互接続線を作製する方法
US5494858A (en) * 1994-06-07 1996-02-27 Texas Instruments Incorporated Method for forming porous composites as a low dielectric constant layer with varying porosity distribution electronics applications

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WO1998047177A1 (fr) 1998-10-22
CN1260908A (zh) 2000-07-19
KR20010006553A (ko) 2001-01-26
JP2001520805A (ja) 2001-10-30
AU6878598A (en) 1998-11-11

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