Classifications

• • 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 potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
  • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
  • H01L21/30—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
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K3/00—Materials not provided for elsewhere
  • C09K3/14—Anti-slip materials; Abrasives
  • C09K3/1454—Abrasive powders, suspensions and pastes for polishing
  • C09K3/1463—Aqueous liquid suspensions

Definitions

• the present invention relates, in general, to a process for preparing a metal oxide slurry useful in semiconductor chemical mechanical polishing (CMP) and, more particularly, to use of the counter collision of a metal oxide slurry by inj ecting it from two orifices at a high speed, whereby the metal oxide slurry can be allowed to be narrow in particle size distribution and superior in dispersion stability and polishing rate in addition to showing an exceptionally decreased /---scratch frequency.
• CMP semiconductor chemical mechanical polishing
• a CMP process a kind of lithography, is utilized in fabricating semiconductors.
• planarization which can be attained by the CMP process, is indispensable for the high integration of semiconductors .
• metal oxide slurry is required to show excellent dispersibility and polishing rate as well as to leave as few defects, such as / - scratches, after polishing, as possible, in addition to being high in purity.
• the particles are preferably distributed in a narrow size range. In other words, the particles more ur-iforrr. in size bring about better polishing results. For example, when using slurry with a bread range of particle sizes, the abraded surface is poor in flatness and has a significant amount of ,-- -scratches thereon .
• U.S. Pat. No. 5, 382, 272 discloses a preparation process of polishing compositions which exhibit high polishing rates.
• the compositions are based on Si0 2 and used to polish ⁇ i wafers.
• the compositions are prepared by blending silica and deionized water in a high speed mixer and agitating them in an agitator mill which contains a mill medium (bead) . It is written that the base abrasive is activated by addition of a second cation, such as Ce t and Zr 4+ , so that the polishing rate is enhanced.
• a second cation such as Ce t and Zr 4+
• the slurry composition of this patent contains SiO : as an abrasive, monoethanol amine as a pH-adjusting agent, and additives such as NH + , Cs + andBa 3+ .
• the pH-adjusting agent excludes the plausible possibility that conventional pH-adjusting agents, such as KOH or NH 4 OH, may diffuse into wafers during a polishing procedure and act as a pollutant.
• this slurry exhibits a relatively slow polishing rate ranging from 1,500 to 2,500 A/min.
• U.S. Pat a dispersion process for CMP slurry.
• No.5,342, 609 described a method and apparatus for forming emulsions, in which collisions between oils, cavitation, and shearing stresses are utilized, in combination.
• the apparatus called a microfluidizer, is known to be applied for various purposes and superior in emulsification. However, it has not yet been applied for the dispersion of particles, such as metal oxides.
• CMP semiconductor chemical mechanical polishing
• the above object could be accomplished by a provision of a process for preparing a metal oxide CMP slurry suitable for semiconductor devices, wherein a mixture comprising 1 to 50 weight % of a metal oxide and 50 to 99 weight % of water is mixed in a pre-mixing tank, transferred to a dispersion chamber with the aid of a transfer pump, allowed to have a flow rate of not less than 100 m/sec by pressurization at 50 atm with a high pressure pump, and subjected to counter collision for dispersion through two orifices in the dispersion chamber.
• a process for preparing a metal oxide CMP slurry suitable for semiconductor devices wherein a mixture comprising 1 to 50 weight % of a metal oxide and 50 to 99 weight % of water is mixed in a pre-mixing tank, transferred to a dispersion chamber with the aid of a transfer pump, allowed to have a flow rate of not less than 100 m/sec by pressurization at 50 atm with a high pressure pump, and subjected to counter
• Fig. 1 is a schematic view showing a dispersion process of metal oxide slurries, according to the present invention
• Fig.2 is a conceptional view showing the fluids are counter collided with each other via two orifices in a dispersion chamber.
• Fig.1 is a schematic process view showing the dispersion of CMP slurry according to the present invention.
• metal oxide slurry is introduced to a line connected with a high pressure pump 3 with the aid of a transfer pump 2.
• the slurry With a flow speed of not less than 100 m/sec by the accelerating action of the high pressure pump 3, the slurry is injected through two orifices into a dispersion chamber 4 in which the slurry is dispersed as a result of the complex occurrence of counter collisions, such as wall collision of fluid, cavitation, and shearing force.
• the dispersion of metal oxides is dependent on their surface area. As their surface area is larger, the metal oxides are better dispersed. Available in the present invention are any metal oxides that have a surface area from 20 to 300 m 2 /g when being oxidized at a temperature of 1,000 ° C or higher. Preferable is one which is selected from the group consisting of Si0 2 , Ce0 2 , Zr0 2 or the mixtures thereof.
• the selected metal oxide is mixed with water in the pre- mixing tank in such a way that the resulting metal slurry has a solid content of 1 to 50 weight % and preferably 5 to 30 weight %.
• the premixed slurry has a solid content less than 1 weight %, a satisfactory dispersion effect cannot be attained.
• a solid content more than 50 weight % causes a thixotropic phenomenon, resulting in an extreme increase of viscosity.
• this slurry Before being used in CMP process, this slurry is diluted.
• the solid content in the diluted metal oxide slurry to be used in a CMP process is controlled into a range of from 10 to 14 weight % for Si0 2 , from 1 to 5 for Ce0 2 and from 4 to 8 weight % for Zr0 2 .
• the dispersion degree of the metal oxides is proportional to the accelerated fluid' s flow rate which is, in turn, proportional to the pressure of the high pressure pump at an orifice diameter.
• the fluid accelerated by the pressurization of the high pressure pump 3 has a flow rate higher than 100 m/sec and preferably 350 m/sec.
• the high pressure pump 3 is required to pressurize at 50 atm for the flow rate of 100 m/sec and at 500 atm for the flow rate of 350 m/sec.
• any pressure pump that has a pressure capacity of 50 atm or higher can be used in the present invention.
• the fluid accelerated by the high pressure pump is introduced in the dispersion chamber 4 in which the fluid undergoes complex counter collision, such as wall collision and cavitation, to form ultrafine particles.
• the orifices are made of engineering plastics, glass-reinforced plastics, carbon steel, stainless steel (SUS) , ceramic, or diamond with preference to ceramic or diamond in an aspect of durability.
• SUS stainless steel
• ceramic or diamond with preference to ceramic or diamond in an aspect of durability.
• these examples are only illustrative, but not limitative of the present invention.
• the orifices 6 have a diameter of 0.05 to 0.5 mm and preferably 0.1 to 0.3 mm.
• the orifices 6 are below 0.05 mm in diameter, the metal oxide slurry is well dispersed by virtue of the increased acceleration effect under a pressure condition, but a poor result is brought into productivity by decreased throughput per time.
• productivity is increased, but it is economically unfavorable because there is needed a high pressure pump which has a capacity sufficient to maintain the required flow rate.
• the orifices have a tubular form and are designed to have an outlet diameter ⁇ 1 ) smaller than an inlet diameter ( 1 ? ) , so as to improve the acceleration effect under a pressure condition.
• the outlet diameter (1 2 ) is reduced to half of the inlet diameter ( 1 2 ) , the flow rate is increased four times.
• the production of slurry per time is proportional to the square of the outlet diameter of the orifice and to the square root of the pressure applied.
• the diameters of the orifices and the pressure capacity of the high pressure pump can be determined by taking the treatment rate of the slurry into account.
• the dispersion degree (ultrafining) of the metal oxides is in proportion to the pressure of the high pressure pump 3 and the number of counter collisions. In other words, as the pressure increases, the particles are smaller while as the collision number increases, the particles size distribution is narrower and more uniform.
• Si0 2 slurry which is the most widely used for CMP process, for example, when one counter collision is carried out once at a flow rate of 350 m/sec via two orifices with a diameter of 0.2 mm by a force of 500 atm, there can be obtained particles with an average size from 140 to 150 nm, which are suitable for CMP.
• pressurization at higher than 500 atm produces smaller particles, making the particle size distribution narrower.
• the slurry obtained at higher than 500 atm shows the same polishing effects such as in polishing rate and ⁇ -scratch frequency, as those of the slurry obtained at 500 atm.
• the slurry prepared under a pressure lower than 300 atm is as high in polishing rate as, but produces more ---scratches than that prepared at 500 atm.
• EXAMPLE VII The same procedure as that of Example I was repeated, except for using ceria (Ce0 2 , surface area of 30 rrr/g) instead of silica. The results are given in Table 1, below.
• EXAMPLE VIII The same procedure as that of Example I was repeated, except for using zirconia (Zr0 2 , surface area 30 m 2 /g) instead of silica. The results are given in Table 1, below.
• Polishing was performed for 2 min. The polishing rates were measured from the thickness change of the wafers. As for ⁇ - scratch, it was detected with the aid of a Tencor model KLA machine . For comparison, "SS-25", a slurry sold by Cabot, was used as a control.
• the CMP slurry of the present invention which is prepared by a dispersion process in which a fluid is subjected to counter collision and cavitation, takes advantages over the slurries prepared by conventional dispersion processes comprising bead use or wall collision only, in that the particles of the slurry of the present invention are narrower in particle size distribution, showing an ultrafine size ranging from 30 to 500 nm.
• the slurry of the present invention is little or not polluted at all during its preparation and shows no tailing phenomena, so that it is preventive of / /-scratching.
• the process according to the present invention can be carried out by a simple operation.
• the dispersion degree of the slurry is patterned on the pressure and collision number, so that the slurry can be reproduced at a high efficiency.
• An additional advantage of the process of the present invention resides in the ability to produce slurries in a continuous type and thus, at high productivity.

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• General Physics & Mathematics (AREA)
• Physics & Mathematics (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• Materials Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Computer Hardware Design (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Power Engineering (AREA)
• Mechanical Treatment Of Semiconductor (AREA)
• Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=19551460

Family Applications (1)

Country Status (6)

Families Citing this family (13)

Family Cites Families (2)

• 1998
  • 1998-09-22 KR KR1019980039212A patent/KR20000006595A/ko active Search and Examination
• 1999
  • 1999-03-19 WO PCT/KR1999/000123 patent/WO2000017282A1/en not_active Application Discontinuation
  • 1999-03-19 JP JP2000574185A patent/JP2002526593A/ja active Pending
  • 1999-03-19 EP EP99909365A patent/EP1032615A1/de not_active Withdrawn
  • 1999-03-19 CN CN99800657A patent/CN1113945C/zh not_active Expired - Lifetime
  • 1999-09-07 TW TW088115383A patent/TW440603B/zh not_active IP Right Cessation

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events