Classifications

• • 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 at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
  • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
  • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
  • H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
  • H01L21/304—Mechanical treatment, e.g. grinding, polishing, cutting
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09G—POLISHING COMPOSITIONS; SKI WAXES
  • C09G1/00—Polishing compositions
  • C09G1/02—Polishing compositions containing abrasives or grinding agents
• • 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 at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
  • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
  • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
  • H01L21/31—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers; Selection of materials for these layers
  • H01L21/3105—After-treatment
  • H01L21/31058—After-treatment of organic layers
• • 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 at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
  • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
  • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
  • H01L21/31—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers; Selection of materials for these layers
  • H01L21/3205—Deposition of non-insulating-, e.g. conductive- or resistive-, layers on insulating layers; After-treatment of these layers
  • H01L21/321—After treatment
  • H01L21/32115—Planarisation
  • H01L21/3212—Planarisation by chemical mechanical polishing [CMP]

Definitions

• the present invention relates generally to chemical mechanical polishing of multilayer semiconductor IC wafers, especially those comprising a low dielectric constant polymeric layer.
• Semiconductor devices are fabricated step-by-step, beginning with a silicon wafer (substrate), implanting various ions, creating various circuit structures and elements, and depositing various insulating and conductive layers. Some of these layers are subsequently patterned by photoresist and etching, or similar processes, which results in topological features on the surface of the substrate. Subsequent layers over the topological layers sometimes duplicate the uneven topology of the underlying layers. Such uneven (irregular, non-planar) surface topology can cause undesirable effects and/or difficulties in the application of subsequent layers and fabrication processes.
• CMP chemical mechanical polishing
• U.S. Pat. No. 5,245,790 to Jerbic describes a technique for chemical mechanical polishing of semiconductor wafers using ultrasonic energy and a silica based slurry in a KOH solution.
• U.S. Pat. No. 5,244,534 to Yu et al. discloses a method of forming conductive plugs within an insulation layer. The process results in a plug of material, such as tungsten, which is more even with the insulation layer surface than that achieved using conventional plug formation techniques.
• Slurries of abrasive particles such as A12O3 and etchants such as H2O2 and either KOH or NH4OH are used in the first CMP step to remove the tungsten at a predictable rate while removing very little of the insulation.
• the second CMP step utilizes a slurry consisting of an abrasive material, such as aluminum oxide, and an oxidizing component of hydrogen peroxide and water.
• U.S. Pat. No. 5,209,816 to Yu et al. teaches a CMP slurry comprising H3PO4, H2O2, H2O and a solid abrasive material while U.S. Pat. Nos. 5,157,876 and 5,137,544 to Medellin teach stress free CMP agents for polishing semiconductor wafers which include a mixture of water, colloidal silica and bleach containing sodium hypochlorite.
• U.S. Pat. No. 4,956,313 to Cote et al. discloses a slurry consisting of A12O3 particulates, deionized water, a base and an oxidizing agent.
• CMP slurry refers to the abrasive and etching chemicals.
• a silica-based slurry is "SCI" available from Cabot Industries.
• Other CMP slurrys are based on silica and cerium
• colloidal or “colloidally stable” means that the d ⁇ spersion is question does not settle in a non-agitated state to an extent that renders the dispersion unusable as-is. In other words the utility for chemical mechanical polishing is available at any time, even after storage, or periods of non-use.
• colloidal stablility in a dispersion as “stable” where there are forces sufficient in the dispersion to overcome the van der Waals forces between the particles, as primary particles, aggregate particle, of a combination of both that may be present in the dispersion.
• U.S. Pat. No. 4,956,313 discloses a via-filling and planarization technique. This patent discusses a planarization etch to remove portions of a dielectric surface lying outside of vias, while simultaneously planarizing a passivation layer, to provide a planarized surface upon which subsequent metal and insulator layers can be deposited.
• the use of an abrasive slurry consisting of A12O3 particulates, de-ionized water, a base, and an oxidizing agent (e.g., hydrogen peroxide) is discussed, for etching tungsten and BPSG.
• a multilevel metallized semiconductor integrated circuit typically includes conductive interconnections covered by interlayer dilectric material.
• Conventional interlayer dilectric materials include SiO2, and SiO2 doped with fluorine or boron, for example.
• Global planarization of surface layers is necessary to ensure adequate focus depth during photolithography, as well as removing any irregularities arising during the various stages of the fabrication process.
• Such layers are typically composed of parylenes, fluoro-polymers, polytetrafluoroethylene, aerogels, micro-porous polymers, and polyaryleneethers.
• a low dielectric constant polymer surface on a semiconductor wafer is treated under CMP conditions with particular types of particles of Alumina (Al 2 O 3 ) , Silica (SiO 2 ), Titania (TiO 2 ), Zirconia (ZrO 2 ), Ceria (CeO 2 ), or mixtures thereof maintained in a colloidal suspension, and specified hereinbelow.
• the present invention is directed to a process for chemical mechanical polishing low dielectric constant polymer surfaces on a semiconductor device with the use of high purity, fine metal oxide particles uniformly dispersed in a stable colliodal aqueous dispersion in a CMP process applied to the ILD layer.
• the process utilizes as the abrasive component, a stable colloidal dispersion of fine metal oxide particles that have a surface area ranging from about 40 m 2 /g to about 430 m 2 /g, an aggregate size distribution less than about 1.0 micron, and a mean aggregate diameter less than about 0.4 micron
• the present invention is directed to a process for chemical mechanical polishing a low dielectric constant polymer surfaces using a slurry comprising high purity, fine metal oxide particles colloidally dispersed in an aqueous medium.
• the particles of the present invention exhibit a surface area ranging from about 40 m2/g to about 430 m2/g, an aggregate size distribution less than about 1.0 micron, and a mean aggregate diameter less than about 0.4 micron.
• the particles may comprise between 0.5% and 55% of the slurry depending on the desired rate of ILD material removal.
• the abrasion of the metal oxide particles is a function of the particle composition, the degree of crystallinity and the crystalline phase, e.g. gamma or alpha for alumina.
• the optimum surface area and loading level will vary depending upon which fine metal oxide particles are chosen for a particular polishing slurry, as well as the degree of crystallinity and phase of the particles. In one embodiment when a high degree of selectivity is desired, solid loadings of less than
• alumina particles having surface areas ranging from about 70 m2/g to about 170 m2/g are preferred. At lower surface areas, i.e. less than 70 m2/g, solid loadings of less than 7% is preferred for alumina particles.
• surface areas ranging between 40 m2/g and 250 m2/g should be present in a range from about 0.5% to about 20% by weight.
• the metal oxide particles of the present invention are of a high purity and have an aggregate size distribution of less than about 1.0 micron in order to avoid scratching, pit marks, divots and other surface imperfections during the polishing.
• FIGS. 2 and 3 illustrate aggregate size distributions for metal oxide particles of the present invention for fumed alumina and silica, respectively.
• High purity means that the total impurity content is typically less than 1% and preferably less than 0.01% (i.e. 100 ppm).
• Sources of impurities typically include raw material impurities and trace processing contaminants.
• the aggregate size of the particles refers to the measurement of the branched, three dimensional chains of fused primary particles (individual molten spheres).
• the mean aggregate diameter refers to the average equivalent spherical diameter when using TEM image analysis, i.e. based on the cross-sectional area of the aggregate.
• the metal oxide particles used herein have a mean aggregate size distribution preferably less than 0.3 micron.
• the aggregate size distribution of the colloidal dispersed particles can be determined by transmission electron microscopy (TEM) of metal oxide particles dispersed in a liquid medium where the agglomerates have been reversed to aggregates and concentration adjusted until discrete aggregates are shown on the TEM grid. Multiple fields on the grid are then imaged using an image analysis system manufactured by Kontron Instruments (Everett, Mass.) and an image analysis computer with a frame-grabber board for further processing, adjusting background and normalizing the image. Individual aggregates in the binary field are measured for a number of particle parameters, i.e. aggregate size, using known techniques such as that described in ASTM D3849-89
• stable colloidal dispersion is meant that the particle aggregates are isolated and well distributed throughout the medium and remain stable without agitation for at least a three months.
• the metal oxide particles used in the present invention have an average or mean aggregate diameter of less than about 0.4 micron and for colloidal stability, the surface potential or the hydration force of the metal oxide particles is sufficient to repel and overcome the van der Waals attractive forces between the particles.
• the particles used herein have a maximum zeta potential greater than ⁇ 10 millivolts.
• the zeta potential is dependent on the pH of the aqueous medium. In the process, for a given metal oxide particle composition, the preferred operating pH is above or below the point where the maximum zeta potential for that material occurs. It should be noted that the maximum zeta potential and isoelectric point are functions of the metal oxide composition and that the maximum zeta potential can be effected by the addition of salts to the aqueous medium. See R. J. Hunter, Zeta Potential in Colloid Science (Academic Press 1981). Zeta potential can be determined by measurement of the electrokinetic sonic amplitude using a Matec MBS-8000 instrument (available from Matec Applied Sciences, Inc., Hopkington, Mass.).
• oxide CMP may be simultaneously accomplished with the polishing slurry where the surface of metal vias is planarized with the ILD .
• an oxidizing component is used to oxidize a metal via surface to its corresponding oxide.
• the via is mechanically polished to remove the oxide from the via.
• oxidizing components include oxidizing metal salts, oxidizing metal complexes, iron salts such as nitrates, sulfates, EDTA, citrates, potassium ferricyanide and the like, aluminum salts, sodium salts, potassium salts, ammonium salts, quaternary ammonium salts, phosphonium salts, peroxides, chlorates, perchlorates, permanganates, persulfates and mixtures thereof.
• the oxidizing component is present in the slurry in an amount sufficient to ensure rapid oxidation of the metal via while balancing the mechanical and chemical polishing components of the slurry.
• Oxidizing components are typically present in the slurry from about 0.5% to 15% by weight, and preferably in a range between 1% and 7% by weight.
• a variety of additives such as surfactants, polymeric stabilizers or other surface active dispersing agents, can be used.
• surfactants such as surfactants, polymeric stabilizers or other surface active dispersing agents.
• suitable surfactants for use in the present invention are disclosed in, for example, Kirk-Othmer, Encyclopedia of Chemical Technology, 3rd Edition, Vol.
• a surfactant consisting of a copolymer of polydimethyl siloxane and polyoxyalkylene ether was found to be suitable.
• the amount of an additive used, such as a surfactant, in the present invention should be sufficient to achieve effective steric stabilization of the slurry and will typically vary depending on the particular surfactant selected and the nature of the surface of the particle. As a result, additives like surfactants should generally be present in a range between about 0.001% and 10% by weight.
• the additive may be added directly to the slurry or treated onto the surface of the metal oxide particle utilizing known techniques. In either case, the amount of additive is adjusted to achieve the desired concentration in the polishing slurry.
• the metal oxide particles of the present invention are typically precipitated aluminas, fumed silicas or fumed aluminas and preferably are fumed silicas or fumed aluminas.
• the production of fumed silicas and aluminas is a well-documented process which involves the hydrolysis of suitable feedstock vapor, such as silicon tetrachloride or aluminum chloride, in a flame of hydrogen and oxygen.
• suitable feedstock vapor such as silicon tetrachloride or aluminum chloride
• Molten particles of roughly spherical shapes are formed in the combustion process, the diameters of which are varied through process parameters.
• These molten spheres of fumed silica or alumina typically referred to as primary particles, fuse with one another by undergoing collisions at their contact points to form branched, three dimensional chain-like aggregates.
• the precipitated metal oxide particles may be manufactured utilizing conventional techniques and are typically formed by the coagulation of the desired particles from an aqueous medium under the influence of high salt concentrations, acids or other coagulants.
• the particles are filtered, washed, dried and separated from residues of other reaction products by conventional techniques known to those skilled in the art.
• the metal oxide is slowly added to deionized water to form a colloidal dispersion.
• the slurry is completed by subjecting the dispersion to high shear mixing using conventional techniques.
• the pH of the slurry is adjusted away from the isoelectric point to maximize colloidal stability.
• the polishing slurry used in the present invention can be a
• one package system metal oxide particles and oxidizing component, if desired, in a stable aqueous medium
• two package the first package consists of the metal oxide particles in a stable aqueous medium and the second package consists of oxidizing component
• the two package system is used for short shelf life oxidizers and the oxidizing component is added to the slurry just prior to polishing.
• the polishing slurry of the present invention has been found useful in providing effective polishing to low dielectric constant polymer surfaces at desired polishing rates while mii-imizing surface imperfections and defects.
• the polishing slurry of the present invention has been found particularly useful in chemical mechanical planarization to remove uneven ILD topography, layers of material, surface defects including scratches, roughness, or contaminant particles such as dirt or dust.
• semiconductor processes utilizing this slurry experience an improvement in surface quality, device reliability and yield as compared to conventional etch back techniques.
• the fine metal oxide particles have been directed to aluminas and silicas, it is understood that the teachings herein have applicability to other fine metal oxide particles such as germania, ceria, titania and the like.
• the metal oxide particles may be utilized to polish other metal surfaces such as copper and titanium, as well as underlayers such as titanium, titanium nitride and titanium tungsten.

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• 2000
  • 2000-02-16 EP EP00913478A patent/EP1171906A1/en not_active Withdrawn
  • 2000-02-16 WO PCT/US2000/003893 patent/WO2000049647A1/en not_active Application Discontinuation
  • 2000-02-16 KR KR1020017010397A patent/KR20010111261A/ko not_active Application Discontinuation
  • 2000-02-16 JP JP2000600297A patent/JP2002537652A/ja active Pending

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