Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B08—CLEANING
  • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
  • B08B3/00—Cleaning by methods involving the use or presence of liquid or steam
  • B08B3/04—Cleaning involving contact with liquid
  • B08B3/10—Cleaning involving contact with liquid with additional treatment of the liquid or of the object being cleaned, e.g. by heat, by electricity or by vibration
  • B08B3/12—Cleaning involving contact with liquid with additional treatment of the liquid or of the object being cleaned, e.g. by heat, by electricity or by vibration by sonic or ultrasonic vibrations
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B08—CLEANING
  • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
  • B08B7/00—Cleaning by methods not provided for in a single other subclass or a single group in this subclass
  • B08B7/0021—Cleaning by methods not provided for in a single other subclass or a single group in this subclass by liquid gases or supercritical fluids
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B08—CLEANING
  • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
  • B08B3/00—Cleaning by methods involving the use or presence of liquid or steam
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D3/00—Other compounding ingredients of detergent compositions covered in group C11D1/00
  • C11D3/02—Inorganic compounds ; Elemental compounds
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D3/00—Other compounding ingredients of detergent compositions covered in group C11D1/00
  • C11D3/02—Inorganic compounds ; Elemental compounds
  • C11D3/04—Water-soluble compounds
  • C11D3/042—Acids
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D3/00—Other compounding ingredients of detergent compositions covered in group C11D1/00
  • C11D3/02—Inorganic compounds ; Elemental compounds
  • C11D3/04—Water-soluble compounds
  • C11D3/046—Salts
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D3/00—Other compounding ingredients of detergent compositions covered in group C11D1/00
  • C11D3/16—Organic compounds
  • C11D3/37—Polymers
  • C11D3/3746—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • C11D3/3749—Polyolefins; Halogenated polyolefins; Natural or synthetic rubber; Polyarylolefins or halogenated polyarylolefins
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D3/00—Other compounding ingredients of detergent compositions covered in group C11D1/00
  • C11D3/43—Solvents
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D7/00—Compositions of detergents based essentially on non-surface-active compounds
  • C11D7/02—Inorganic compounds
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D7/00—Compositions of detergents based essentially on non-surface-active compounds
  • C11D7/02—Inorganic compounds
  • C11D7/04—Water-soluble compounds
  • C11D7/08—Acids
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D7/00—Compositions of detergents based essentially on non-surface-active compounds
  • C11D7/02—Inorganic compounds
  • C11D7/04—Water-soluble compounds
  • C11D7/10—Salts
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D7/00—Compositions of detergents based essentially on non-surface-active compounds
  • C11D7/50—Solvents
  • C11D7/5004—Organic solvents
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D2111/00—Cleaning compositions characterised by the objects to be cleaned; Cleaning compositions characterised by non-standard cleaning or washing processes
  • C11D2111/10—Objects to be cleaned
  • C11D2111/14—Hard surfaces
  • C11D2111/22—Electronic devices, e.g. PCBs or semiconductors

Definitions

• the present invention relates to supercritical fluid-based compositions containing polymeric alcohols such as polyvinyl alcohol, polymeric amines such as polyvinyl amine, and other polyalcohol or polyamine species, useful for the removal of silicon-containing particulate material, e.g., silicon nitrides and silicon oxides, generated in situ during plasma-assisted processes, from the surface of patterned semiconductor wafers.
• polymeric alcohols such as polyvinyl alcohol, polymeric amines such as polyvinyl amine, and other polyalcohol or polyamine species
• silicon-containing particulate material e.g., silicon nitrides and silicon oxides
• Particle contamination on the surface of semiconductor wafers is known to have deleterious effects on the morphology, performance, reliability and yield of the semiconductor device. For example, it has been reported that a particle larger than about one-quarter of the minimum line-width may cause fatal device defects.
• the effective removal of particulates from the surface of semiconductor wafers is increasingly essential.
• Well known sources of particle contamination during device production include plasma-assisted processes such as plasma-enhanced chemical vapor deposition (PECVD).
• PECVD plasma-enhanced chemical vapor deposition
• the particle contamination may occur in situ during continuous plasma operation or following the termination of the plasma process (Setyawan, H., Shimada, M., Imajo, Y., Hayashi, Y., Okuyama, K., J. Aerosol Sci., 34, 923-936 (2003); Selwyn, G.S., Singh, J., Bennett, R.S., J. Vac. Sci. Tech. A, 77, 2758-2765 (1989)).
• Megasonic agitation involves the application of energy in the 500-1000 kHz frequency range to the liquid in which particle-containing wafers are immersed (such as the APM solution) to remove said particles.
• Disadvantages of megasonic agitation include reports that the removal of particles smaller than 100 ran should not be theoretically possible (Olim, M., J. Electrochem. Soc, 144, 3657-3659 (1997)), which renders the technique useless as the dimensions of the devices, and hence the contaminating particles, get smaller and smaller.
• Aerosol jet dry cleaning uses solid water, carbon dioxide or argon particles in a high velocity gas stream to collide with and remove the contaminating particles from the surface.
• a disadvantage of aerosol jet dry cleaning includes the potential for dislodging delicate features, such as MEMS (Micro Electro Mechanical Systems) devices and wafer patterns, with the high velocity gas stream.
• SCCO 2 supercritical carbon dioxide
• the present invention relates to supercritical fluid-based compositions useful for the removal of silicon-containing particulate material from the surface of patterned semiconductor wafers, and methods of using such compositions for removal of same.
• the invention relates to a composition for removing silicon- containing particulate material from the surface of a semiconductor wafer, said composition comprising a supercritical fluid (SCF), at least one co-solvent, at least one etchant species, at least one surface passivator, a binder interactive with said silicon-containing particulate material to enhance removal thereof, deionized water, and optionally at least one surfactant.
• SCF supercritical fluid
• the invention in another aspect, relates to a method of removing silicon- containing particulate matter from a semiconductor wafer surface having same thereon, said method comprising contacting the wafer surface with a SCF-based composition comprising a SCF, at least one co-solvent, at least one etchant species, at least one surface passivator, a binder interactive with said silicon-containing particulate material to enhance removal thereof, deionized water, and optionally at least one surfactant, for sufficient time and under sufficient contacting conditions to remove the silicon-containing particulate matter from the surface of the semiconductor wafer.
• a SCF-based composition comprising a SCF, at least one co-solvent, at least one etchant species, at least one surface passivator, a binder interactive with said silicon-containing particulate material to enhance removal thereof, deionized water, and optionally at least one surfactant, for sufficient time and under sufficient contacting conditions to remove the silicon-containing particulate matter from the surface of the semiconductor wafer.
• the invention relates to a composition for removing silicon-containing particulate material from the surface of a semiconductor wafer, said composition comprising about 85.0% to about 99.0%> SCF, about 0.01% to about 15.0% co- solvent, about 0.25%) to about 5.0%> etchant, and optionally about 0% to about 3.0% surfactant, based on the total weight of the composition.
• the invention relates to a method of removing silicon- containing particulate matter from a semiconductor wafer surface having same thereon, said method comprising: pre-cleaning the wafer surface with a SCF-based pre-cleaning composition comprising a SCF and an aqueous-based pre-cleaning formulation; and
• a SCF-based composition comprising a SCF, at least one co-solvent, at least one etchant species, and optionally at least one surfactant, for sufficient time and under sufficient contacting conditions to remove the silicon-containing particulate matter from the surface of the semiconductor wafer.
• Figure 1 is an optical image of the Si/SiO 2 patterned SONY control wafer contaminated with Si N 4 particles.
• Figure 2 is an optical image of the wafer of Figure 1 cleaned at 50°C with the SCF- based composition of the present invention, wherein the SCF-based composition is devoid of polyvinyl alcohol.
• Figure 3 is an optical image of the wafer of Figure 1 cleaned at 50°C with the SCF- based composition of the present invention, wherein the SCF-based composition includes polyvinyl alcohol and has a high fluoride concentration.
• Figure 4 is an optical image of the wafer of Figure 1 cleaned at 50°C with the SCF- based composition of the present invention, wherein the SCF-based composition includes polyvinyl alcohol and has a low fluoride concentration.
• the present invention is based on the discovery of supercritical fluid (SCF)-based compositions that are highly efficacious for the removal of particulate material from the surface of patterned semiconductor wafers.
• SCF supercritical fluid
• the compositions and methods of the invention are effective for removing silicon-containing particulate material including, but not limited to, silicon nitride (Si 3 N 4 ), silicon oxide and hydrogenated silicon nitride (Si x N y H z ), from the surface of patterned silicon-containing wafers, e.g., Si/Si0 2 wafers.
• the particulate material is generated in situ during plasma-assisted processes including, but not limited to, sputtering and PECVD.
• the PECVD of silicon oxide films is often carried out using gaseous mixtures containing silane in nitrogen (SiH 4 /N 2 ), nitrous oxide and ammonia.
• gaseous mixtures containing silane in nitrogen (SiH 4 /N 2 ), nitrous oxide and ammonia In addition to the deposition of silicon dioxide onto the substrate, highly hydrogenated silicon nitride particles are formed that can settle out onto the wafer surface, either during plasma operation or following the completion of the PECVD process. It is speculated that the source of the hydrogen on the surface of the silicon nitride particles is the silane precursor and/or the ammonia oxidant.
• silazane (Si 2 -NH) groups at the surface of the silicon nitride particles silanol (Si-OH) groups may also be present. The proportion of these functional groups on the surface of the silicon nitride particles varies according to the conditions under which the particles are generated.
• SCCO 2 supercritical carbon dioxide
• SCCO 2 is an attractive reagent for removal of particle contaminants, since SCC0 2 has the characteristics of both a liquid and a gas. Like a gas, it diffuses rapidly, has low viscosity, near-zero surface tension, and penetrates easily into deep trenches and vias. Like a liquid, it has bulk flow capability as a "wash" medium. SCCO 2 also has the advantage of being recyclable, thus minimizing waste storage and disposal requirements. [0023] Ostensibly, SCCO 2 is an attractive reagent for the removal of Si 3 N 4 particles, because both compounds are non-polar. However, neat SCCO 2 has not proven to be an effective medium for solubilizing silicon nitride particles.
• a polar co-solvent e.g., alkanols
• SCCO 2 has not substantially improved the solubility of the silicon nitride particles in the SCC0 2 composition. Accordingly, there is a continuing need to modify the SCC0 2 composition to enhance the removal of particulate material from the semiconductor wafer surface.
• polymeric alcohols such as polyvinyl alcohol, adsorb onto the surface of silicon nitride particles, thus lowering the surface potential of the particles.
• the silanol (Si-OH) and the silazane (Si 2 -NH) groups at the surface of the silicon nitride particles participate in the transfer of protons in water to be Bronsted acid points, e.g., H + donation points, and Bronsted base points, e.g., H + receiving points.
• the polyvinyl alcohol hydroxyl groups may adsorb onto the surfaces of the silicon nitride particles at the Bronsted acid points, thus enhancing the removal of the particles from the wafer surface.
• hydrogen bonding between the polyvinyl alcohol hydroxyl groups and the silanol or silazane groups may participate in removal enhancement.
• polyvinyl alcohol can stabilize the dispersion of silicon nitride particles in the fluid, thus minimizing flocculation.
• the present invention combines the advantages associated with SCCO 2 and other SCFs, with the particle binding efficiency of polymeric alcohols such as polyvinyl alcohol, by using appropriately formulated SCF-based compositions as hereinafter more fully described.
• SCF-based compositions as hereinafter more fully described.
• the removal of silicon nitride particles from a wafer surface using these SCF- based compositions is upwards of 100% efficient, while maintaining the structural integrity of the Si/SiO 2 layers.
• the invention relates to SCF-based compositions useful in removing particulate contaminants including, but not limited to, silicon nitride, silicon oxide and hydrogenated silicon nitride, from a semiconductor wafer surface.
• the formulation of the present invention comprises a SCF, at least one co-solvent, at least one surface passivator, at least one etchant, a binder interactive with said silicon-containing particulate material to enhance removal thereof, deionized water, and optionally at least one surfactant, present in the following ranges, based on the total weight of the composition: component of % by weight SCF about 75.0% to about 99.9% co-solvent about 0.05% to about 22.5% surface passivator about 0.01% to about 1.25% etchant about 0.01% to about 5.0% binder about 0.01% to about 3.75% deionized (DI) water about 0.01 ) to about 3.5% surfactant 0 to about 1.25%
• DI deionized
• the SCF-based etching formulations may comprise, consist of, or consist essentially of a SCF, at least one co-solvent, at least one surface passivator, at least one etchant, a binder interactive with said silicon-containing particulate material to enhance removal thereof, deionized water, and optionally at least one surfactant.
• SCF surface passivator
• etchant surface passivator
• etchant a binder interactive with said silicon-containing particulate material to enhance removal thereof
• surfactant optionally at least one surfactant.
• the specific proportions and amounts of SCF, co-solvent, surface passivator, etchant, binder, surfactant, and deionized water, in relation to each other may be suitably varied to provide the desired removal of the silicon-containing particulate material from the wafer surface, as readily determinable within the skill of the art without undue effort.
• the inclusion of the co-solvent with the SCF serves to increase the solubility of the binder in the SCF.
• the co-solvents contemplated for use in the SCF-based composition include alkanols, dimethylsulfoxide, sulfolane, catechol, ethyl lactate, acetone, butyl carbitol, monoethanolamine, butyrol lactone, an alkyl carbonate such as butylene carbonate, ethylene carbonate and propylene carbonate, a glycol amine such as N-methylpyrrolidone (NMP), N-octylpyrrolidone and N-phenylpyrrolidone, or a mixture of two of more of such species.
• NMP N-methylpyrrolidone
• NMP N-octylpyrrolidone
• N-phenylpyrrolidone N-phenylpyrrolidone
• the alkanol co-solvent is preferably a straight-chain or branched C ⁇ -C 6 alcohol (i.e., methanol, ethanol, isopropanol, etc.), or a mixture of two or more of such alcohol species.
• the alkanol is methanol or isopropanol (IP A).
• Surface passivator is defined herein as a substance that protects the wafer surface from additional oxidation, while simultaneously being capable of hydrogen bonding to the silicon-containing particulate surface to improve the removal of particles from the wafer surface.
• the surface passivator may comprise boric acid, triethyl borate and triethanolamine.
• the surface passivator is boric acid.
• Species capable of etching silicon-containing species such as silicon nitride are well known in the art, and include hydrofluoric acid (HF), ammonium fluoride (NH 4 F) and triethylamine trihydrofluoride ((C 2 Hs) 3 N-3HF).
• salts of bifluorides may be used, including ammonium difluoride ((NH 4 )HF 2 ), tetraalkylammonium difluorides ((R) 4 NHF 2 , where R is methyl, ethyl, butyl, phenyl or fluorinated C ⁇ -C 4 alkyl groups) and alkyl phosphonium difluorides ((R) 4 PHF 2 , where R is methyl, ethyl, butyl, phenyl or fluorinated C ⁇ -C 4 alkyl groups).
• ammonium difluoride (NH 4 )HF 2 )
• R tetraalkylammonium difluorides
• R alkyl phosphonium difluorides
• R alkyl phosphonium difluorides
• the fluoride source aids in particle removal by chemically reacting with the silicon nitride and silicon oxide particles, undercutting the particles, thus reducing their size while concomitantly enhancing the ability of the binder to remove the particle from the wafer surface.
• the etchant is ammonium fluoride.
• Binders are defined herein as species that interact with the silicon-containing particulate material to enhance removal from the semiconductor wafer.
• the binder may have moieties, e.g., hydroxyl or amine groups, capable of interacting with the Bronsted acid and/or Bronsted base points present on the surface of the contaminating particulate material. Additionally, the binders may be capable of hydrogen bonding with the surface of the silicon-containing particulate material. The combined effect of these intermolecular interactions is a reduction of the surface potential of the particulate material and concomitantly, the enhanced removal of the particulate material from the wafer surface.
• the binder of the present invention may be derived from at least one ethylenically unsaturated reactant.
• the binder is a polymeric alcohol, a polymeric amine, a polymeric acetate or a enzymatically decomposed sugar.
• the polymeric alcohol is polyvinyl alcohol, which is commonly made by the polymerization of vinyl acetate followed by hydrolysis of the polyvinyl acetate polymer.
• the polymeric amine is polyvinyl amine, which is commonly made from vinyl formamide.
• the surfactants contemplated in the SCF-based composition of the present invention may include nonionic surfactants, such as fluoroalkyl surfactants, ethoxylated fluorosurfactants, polyethylene glycols, polypropylene glycols, polyethylene or polypropylene glycol ethers, carboxylic acid salts, dodecylbenzenesulfonic acid or salts thereof, polyacrylate polymers, dinonylphenyl polyoxyethylene, silicone or modified silicone polymers, acetylenic diols or modified acetylenic diols, and alkylammonium or modified alkylammonium salts, as well as combinations comprising at least one of the foregoing.
• nonionic surfactants such as fluoroalkyl surfactants, ethoxylated fluorosurfactants, polyethylene glycols, polypropylene glycols, polyethylene or polypropylene glycol ethers, carboxylic acid salts, dodec
• the surfactant is an ethoxylated fluorosurfactant such as ZONYL® FSO-100 fluorosurfactant (DuPont Canada Inc., Mississauga, Ontario, Canada).
• the surfactants may include anionic surfactants, or a mixture of anionic and non-ionic surfactants.
• Anionic surfactants contemplated in the SCF-based composition of the present invention include, but are not limited to, fluorosurfactants such as ZONYL® UR and ZONYL® FS-62 (DuPont Canada Inc., Mississauga, Ontario, Canada), sodium alkyl sulfates, ammonium alkyl sulfates, alkyl (C ⁇ o-C ⁇ 8 ) carboxylic acid ammonium salts, sodium sulfosuccinates and esters thereof, e.g., dioctyl sodium sulfosuccinate, and alkyl (C ⁇ o-C ⁇ 8 ) sulfonic acid sodium salts.
• fluorosurfactants such as ZONYL® UR and ZONYL® FS-62 (DuPont Canada Inc., Mississauga, Ontario, Canada)
• sodium alkyl sulfates such as ZONYL® UR and ZONYL® FS-62 (Du
• the SCF-based composition of the invention includes SCCO 2 , methanol, ammonium fluoride, boric acid, a fluorosurfactant, polyvinyl alcohol and deionized water.
• the invention relates to methods of particulate material contaminant removal including, but not limited to, silicon nitride and silicon oxide, from a semiconductor wafer surface using the SCF-based composition described herein.
• Particle removal by conventional wet chemical techniques e.g., using SC-1 or SC-2 solutions, has not proven wholly satisfactory in effecting complete removal of particulate material from the wafer surface. Further, these conventional cleaning approaches require substantial amounts of chemical reagents and produce substantial quantities of chemical waste.
• the SCF-based compositions of the present invention overcome the disadvantages of the prior art particle removal techniques by minimizing the volume of chemical reagents needed, thus reducing the quantity of waste, while simultaneously providing a composition and method having recyclable constituents, e.g., the SCFs.
• the appropriate SCF-based composition can be employed to contact a wafer surface having particulate material contaminants, e.g., silicon nitride and silicon oxide, thereon at a pressure in a range of from about 1200 to about 4500 psi for sufficient time to effect the desired removal of the particulate matter, e.g., for a contacting time in a range of from about 2 minutes to about 20 minutes and a temperature of from about 30°C to about 100°C, although greater or lesser contacting durations and temperatures may be advantageously employed in the broad practice of the present invention, where warranted.
• the contacting temperature is in the range of from about 40°C to about 70°C, preferably about 50°C.
• the removal process in a particularly preferred embodiment includes sequential processing steps including dynamic flow of the SCF-based composition over the contaminated wafer surface, followed by a static soak of the wafer in the SCF-based composition, with the respective dynamic flow and static soak steps being carried out alternatingly and repetitively, in a cycle of such alternating steps.
• a “dynamic” contacting mode involves continuous flow of the composition over the wafer surface, to maximize the mass transfer gradient and effect complete removal of the particulate material from the surface.
• a “static soak” contacting mode involves contacting the wafer surface with a static volume of the composition, and maintaining contact therewith for a continued (soaking) period of time.
• the dynamic flow/static soak steps may be carried out for four successive cycles in the aforementioned illustrative embodiment, as including a sequence of
• the sequence consists of a 2.5 min dynamic flow, a 2.5 min static soak at 4400 psi, a 2.5 min dynamic flow, and a 2.5 min static soak at 1500 psi.
• the wafer thereafter preferably is washed with copious amounts of SCF/methanol/deionized water solution in a first washing step, to remove any residual precipitated chemical additives from the region of the wafer surface in which particle removal has been effected, and finally with copious amounts of pure SCF, in a second washing step, to remove any residual methanol and/or precipitated chemical additives from the wafer surface.
• the SCF used for washing is SCCO 2 .
• compositions of the present invention are readily formulated by simple mixing of ingredients, e.g., in a mixing vessel under gentle agitation.
• such SCF-based compositions are applied to the wafer surface for contacting with the particulate material contaminants thereon, at suitable elevated pressures, e.g., in a pressurized contacting chamber to which the SCF-based composition is supplied at suitable volumetric rate and amount to effect the desired contacting operation for removal of the particulate material from the wafer surface.
• the invention relates to a second SCF-based composition for particulate material, e.g., silicon nitride and silicon oxide, removal from a semiconductor wafer surface, said second SCF-based composition being devoid of the binder and surface passivator.
• particulate material e.g., silicon nitride and silicon oxide
• the formulation comprises a SCF, at least one co-solvent, at least one etchant, and optionally at least one surfactant, present in the following ranges, based on the total weight of the composition: component of % by weight SCF about 85.0%) to about 99% co-solvent about 0.01% to about 15.0% etchant about 0.25% to about 5.0%> surfactant 0 to about 3.0%)
• compositional components are the same as those disclosed hereinabove.
• the SCF is SCCO 2
• the co-solvent is NMP
• the fluoride source is triethylamine trihydrofluoride
• the surfactant is dioctyl sodium sulfosuccinate.
• the methods of particulate material removal using the second SCF-based composition are the same as those disclosed hereinabove.
• the sample containing the particulate matter to be removed may have to be "pre-cleaned" prior to exposure to the second SCF-based composition to reoxidize the surface.
• An effective SCF-based "pre- cleaning" formulation includes 95-100 wt% SCCO 2 and 0-5 wt %> aqueous-based pre- cleaning formulation, wherein the aqueous-based pre-cleaning formulation includes 0-10 vol % ammonium hydroxide, 0-20 vol % tertbutyl hydrogen peroxide and 70-95 vol % water.
• the pre-cleaning method includes a static soak of the sample in the SCF-based pre- cleaning formulation at pressures in a range from about 1200 psi to about 2800 psi and temperatures in a range from about 40°C to about 60°C for about 2 to about 30 minutes.
• the sample wafers examined in this study were Si/SiO 2 patterned wafers contaminated with Si 3 N 4 particles.
• Various chemical additives, as described herein, were added to the SCF-based composition and particle removal efficiency evaluated.
• the temperature of the SCF-based composition was maintained at 50°C throughout the particle removal experiments.
• the wafers were thoroughly rinsed with copious amounts of SCCO 2 /methanol/deionized water and pure SCC0 2 in order to remove any residual solvent and/or precipitated chemical additives.
• the results are shown in Figures 1-4, as described hereinbelow.
• Figure 1 is an optical image of the SONY control wafer showing Si 3 N 4 particles covering the entire Si/Si0 2 wafer surface.
• Figure 2 is the same wafer cleaned with a SCCO 2 /methanol/DI water/boric acid/NH 4 F solution, which is devoid of polyvinyl alcohol.
• the results show that the Si 3 N 4 particles are completely removed from the SiO 2 surface, however, only approximately 50% of the particles were removed from the Si surface.
• Figure 3 is the same wafer cleaned with a SCCO 2 /methanol/DI water/boric acid/NH 4 F/polyvinyl alcohol solution having a fluoride/boric acid ratio of 3:1 (high fluoride concentration). The results clearly show that the Si 3 N 4 particles are completely removed from the Si0 2 surface, while leaving the particles residing on the silicon regions untouched.
• Figure 4 is the same wafer cleaned with a SCCO 2 /methanol/DI water/boric acid/NH 4 F/polyvinyl alcohol solution having a low fluoride concentration. The results clearly show that the Si 3 N 4 particles are completely removed from both the Si and Si0 2 surfaces, with no evidence of SiO 2 etching.
• Another formulation found to substantially remove particles at lower pressures, e.g., 2800 psi, and 50°C includes: Component Weight Percent triethylamine trihydrofluoride 0.1 % dioctyl sodium sulfosuccinate 0.02 % NMP 10.0 % SCC0 2 89.88 %

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• 2004
  • 2004-03-01 US US10/790,535 patent/US7553803B2/en not_active Expired - Fee Related
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  • 2005-02-25 KR KR1020067019819A patent/KR20070006800A/ko not_active Ceased
  • 2005-02-25 EP EP05723901A patent/EP1735425A2/en not_active Withdrawn
  • 2005-02-25 JP JP2007501865A patent/JP2007526653A/ja not_active Withdrawn
  • 2005-02-25 WO PCT/US2005/006228 patent/WO2005084241A2/en not_active Ceased

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