EP1032615A1 - Process for preparing metal oxide slurry suitable for semiconductor chemical mechanical polishing - Google Patents
Process for preparing metal oxide slurry suitable for semiconductor chemical mechanical polishingInfo
- Publication number
- EP1032615A1 EP1032615A1 EP99909365A EP99909365A EP1032615A1 EP 1032615 A1 EP1032615 A1 EP 1032615A1 EP 99909365 A EP99909365 A EP 99909365A EP 99909365 A EP99909365 A EP 99909365A EP 1032615 A1 EP1032615 A1 EP 1032615A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- slurry
- metal oxide
- dispersion
- polishing
- orifices
- 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- Withdrawn
Links
- 239000002002 slurry Substances 0.000 title claims abstract description 58
- 229910044991 metal oxide Inorganic materials 0.000 title claims abstract description 28
- 150000004706 metal oxides Chemical class 0.000 title claims abstract description 26
- 239000004065 semiconductor Substances 0.000 title claims abstract description 12
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 8
- 238000005498 polishing Methods 0.000 title description 32
- 239000000126 substance Substances 0.000 title description 4
- 239000006185 dispersion Substances 0.000 claims abstract description 39
- 239000002245 particle Substances 0.000 claims abstract description 37
- 238000000034 method Methods 0.000 claims abstract description 34
- 230000008569 process Effects 0.000 claims abstract description 23
- 239000000203 mixture Substances 0.000 claims abstract description 14
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 8
- 238000002156 mixing Methods 0.000 claims abstract description 6
- 238000012546 transfer Methods 0.000 claims abstract description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 44
- 229910052681 coesite Inorganic materials 0.000 claims description 27
- 229910052906 cristobalite Inorganic materials 0.000 claims description 27
- 229910052682 stishovite Inorganic materials 0.000 claims description 27
- 229910052905 tridymite Inorganic materials 0.000 claims description 27
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 claims description 13
- 229910000422 cerium(IV) oxide Inorganic materials 0.000 claims description 10
- 239000000377 silicon dioxide Substances 0.000 claims description 8
- CETPSERCERDGAM-UHFFFAOYSA-N ceric oxide Chemical compound O=[Ce]=O CETPSERCERDGAM-UHFFFAOYSA-N 0.000 claims description 3
- 238000009826 distribution Methods 0.000 abstract description 16
- 238000002360 preparation method Methods 0.000 abstract description 4
- 238000002955 isolation Methods 0.000 abstract description 3
- 230000003449 preventive effect Effects 0.000 abstract description 2
- 238000006748 scratching Methods 0.000 abstract description 2
- 239000003989 dielectric material Substances 0.000 abstract 2
- 239000011229 interlayer Substances 0.000 abstract 1
- 239000012530 fluid Substances 0.000 description 8
- 239000011324 bead Substances 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 6
- 239000007787 solid Substances 0.000 description 5
- 235000012431 wafers Nutrition 0.000 description 5
- 230000003247 decreasing effect Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 239000008367 deionised water Substances 0.000 description 3
- 229910021641 deionized water Inorganic materials 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 239000003002 pH adjusting agent Substances 0.000 description 3
- 230000001133 acceleration Effects 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 2
- 229910003460 diamond Inorganic materials 0.000 description 2
- 239000010432 diamond Substances 0.000 description 2
- 238000010008 shearing Methods 0.000 description 2
- HZAXFHJVJLSVMW-UHFFFAOYSA-N 2-Aminoethan-1-ol Chemical compound NCCO HZAXFHJVJLSVMW-UHFFFAOYSA-N 0.000 description 1
- 229910002016 Aerosil® 200 Inorganic materials 0.000 description 1
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- -1 Cet and Zr4+ Chemical class 0.000 description 1
- 239000004809 Teflon Substances 0.000 description 1
- 229920006362 Teflon® Polymers 0.000 description 1
- 238000005299 abrasion Methods 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 235000008429 bread Nutrition 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 239000010962 carbon steel Substances 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000004945 emulsification Methods 0.000 description 1
- 239000000839 emulsion Substances 0.000 description 1
- 229920006351 engineering plastic Polymers 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 239000011152 fibreglass Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 238000001459 lithography Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000003801 milling Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 230000009974 thixotropic effect Effects 0.000 description 1
- 239000011882 ultra-fine particle Substances 0.000 description 1
- 238000002604 ultrasonography Methods 0.000 description 1
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.
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Organic Chemistry (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Manufacturing & Machinery (AREA)
- Computer Hardware Design (AREA)
- Physics & Mathematics (AREA)
- Power Engineering (AREA)
- General Physics & Mathematics (AREA)
- Materials Engineering (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- Mechanical Treatment Of Semiconductor (AREA)
- Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)
Abstract
There is disclosed 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 with a high pressure pump, and subjected to counter collision for dispersion through two orifices in the dispersion chamber. The slurry has particles which are narrow in particle size distribution, showing an ultrafine size ranging from 30 to 500 nm. Also, the slurry is not polluted at all during its preparation and shows no tailing phenomena, so that it is preventive of ν-scratching. Therefore, it can be used in the planarization for shallow trench isolation, interlayer dielectrics and intermetal dielectrics through a CMP process.
Description
PROCESS FOR PREPARING METAL OXIDE SLURRY SUITABLE FOR SEMICONDUCTOR CHEMICAL MECHANICAL POLISHING
BACKGROUND OF THE INVENTION
Field of the invention
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.
Description of the Prior Art
A CMP process, a kind of lithography, is utilized in fabricating semiconductors. As semiconductors become miniaturized with denser populations to more complex multilayer structures, planarization, which can be attained by the CMP process, is indispensable for the high integration of semiconductors .
To be useful in the CMP process, generally, 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.
All of these requirements, except for purity, are closely concerned with the particle size and distribution of the metal oxide. In regard to the particle size, smaller particles are preferable because they show better dispersion stability and provide fewer μ -scratches, but are disadvantageous in polishing efficiency because the smaller the particles are, the slower the polishing rate is. In an aspect of particle size distribution, of course, 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 .
Thus, when selecting the particle size and size distribution of slurry for CMP, account must be taken of polishing rate, dispersion stability and μ -scratch frequency. U.S. Pat. No. 5, 382, 272 discloses a preparation process of polishing compositions which exhibit high polishing rates. The compositions are based on Si02 and used to polish Ξi 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 Cet and Zr4+, so that the polishing rate is enhanced. The process disclosed in this patent suffers from disadvantages. The beads are inevitably polluted during the dispersion which is accomplished by the collision between the abrasive and the bead. In addition, a tailing phenomenon occurs, making it difficult to produce a slurry whose particles are in a narrow size distribution. Further, the beads are etched during milling, so that their dispersing ability is decreased. In face, because the slurries produced are significantly different from each other in particle size and size distribution, a constant polishing ability cannot be expected from the slurries. In another known preparation process, a fluid is rotated at a high speed by a rotor sold by IKA, Germany and collided with a stator. This technique, even if enhanced relative to the process of U.S. Pat. No. 5,382,272, has a problem in that the stator is etched as a result of the wall collision so that a significant decrease in dispersion capability results.
These conventional techniques all are known to produce particles which have a size of lμm. They are too large to be used in CMP. In particular, they cannot be used as a CMP slurry for
shallow trench isolation because ---scratches, if occurring during the isolation process, cause fatal damages to the function and yield of semiconductor devices.
Another technique relating to a CMP slurry is disclosed in WO Pat . No.9747430. With use in polishing Si wafers, the slurry composition of this patent contains SiO: as an abrasive, monoethanol amine as a pH-adjusting agent, and additives such as NH+, Cs+andBa3+. The pH-adjusting agent excludes the plausible possibility that conventional pH-adjusting agents, such as KOH or NH4OH, may diffuse into wafers during a polishing procedure and act as a pollutant. However, this slurry exhibits a relatively slow polishing rate ranging from 1,500 to 2,500 A/min. In addition, nowhere is mentioned a dispersion process for CMP slurry. U.S. Pat . 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.
An example of the prior art using the microfluiάizer is found in U.S. Pat. No. 5,342,609. According to the patent, a particle mixture comprising calcium and oxianions is dispersed
in a microfluidizer, so as to produce a composition with a particle size of 5 nm. However, this composition is used for diagnostic purposes, such as MRI, X-ray and ultrasound, but not for semiconductor polishing.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to overcome the problems encountered in prior arts and to provide a process for preparing a metal oxide slurry useful in semiconductor chemical mechanical polishing (CMP) , 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 μ - scratch frequency. In accordance with the present invention, 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.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other objects and aspects of the invention will become apparent from the following description of embodiments with reference to the accompanying drawings in which:
Fig. 1 is a schematic view showing a dispersion process of metal oxide slurries, according to the present invention; and Fig.2 is a conceptional view showing the fluids are counter collided with each other via two orifices in a dispersion chamber.
DETAILED DESCRIPTION OF THE INVENTION
The application of the preferred embodiments of the present invention is best understood with reference to the accompanying drawings .
Fig.1 is a schematic process view showing the dispersion of CMP slurry according to the present invention. As shown in this figure, after being homogeneously mixed with water in a pre- mixing tank 1, metal oxide slurry is introduced to a line connected with a high pressure pump 3 with the aid of a transfer pump 2. 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. In the process of the present invention, it is designed that the particles which remain larger than 500 nm in diameter after the dispersion is done by the collision should be recovered by a recovery means to stabilize the final slurry. Check valves 5 are provided in front of and at the back of the high pressure pump 3, so as to prevent the slurry from flowing backward.
In general, 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 m2/g when being oxidized at a temperature of 1,000 °C or higher. Preferable is one which is selected from the group consisting of Si02, Ce02, Zr02 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 %.
If the premixed slurry has a solid content less than 1 weight %, a satisfactory dispersion effect cannot be attained. On the other hand, a solid content more than 50 weight % causes a thixotropic phenomenon, resulting in an extreme increase of
viscosity.
Before being used in CMP process, this slurry is diluted.
For example, it is advantageous in polishing capacity and material cost that 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 Si02, from 1 to 5 for Ce02 and from 4 to 8 weight % for Zr02.
In the present invention, 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. Hence, metal oxide slurries with various particle size distributions can be obtained simply by controlling the pressure of the high pressure pump.
In accordance with the present invention, 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.
To accomplish this flow rate, 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. Thus, any pressure pump that has a pressure capacity of 50 atm or higher can be used in the present invention.
Via the two orifices 6 which are provided in the dispersion chamber 4, as mentioned above, 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. However, these examples are only illustrative, but not limitative of the present invention.
In consideration of the compatibility with the high pressure pump and the dispersion efficiency of the slurry, the orifices 6 have a diameter of 0.05 to 0.5 mm and preferably 0.1 to 0.3 mm. For example, if 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. On the other hand, if the orifices have a diameter larger than 0. 5 mm, 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. As shown in Fig.2, 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. When the outlet diameter (12) is reduced to half of the inlet diameter ( 12) , the flow rate is increased four
times. Mathematically, 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. When designing the dispersion process system, 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.
As for the dispersion degree (ultrafining) of the metal oxides, it 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.
For Si02 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. Of course, pressurization at higher than 500 atm produces smaller particles, making the particle size distribution narrower. However, the slurry obtained at higher than 500 atm shows the same polishing effects such as in polishing rate and μ -scratch frequency, as those of the slurry obtained at 500 atm. Thus, it is advantageous in energy efficiency to select as low a pressure as possible if there are no differences in polishing
results . On the other hand, 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.
The following examples are set forth to illustrate more clearly the principles and practice of this invention to one skilled in the art. As such, they are not intended to limit the invention, but are illustrative of certain preferred embodiments .
EXAMPLE I
130 g of silica with a surface area of 200 m2/g, such as that commercially available from Degussa, identified as "Aerosil 200", 18 g of a 20% KOH solution, and 860 g of deionized water, were mixed in a teflon-coated premixing tank with a volume of 1 m2 and transferred by a transfer pump (diaphram 1-50 atm) to a dispersion chamber in which the mixture is subjected to counter collision through two orifices with an inlet diameter of 0.4 mm and an outlet diameter of 0.2 mm by a force of 500 atm with the aid of a high pressure pump (Intensifier pump, 50-1, 500 atm) , so as to give CMP slurry . The sample from the dispersion chamber was measured for particle size, particle size distribution and average particle size by use of a size analyzer, such as that sold by Malvern under the brand name of "Zetasizer". The results are given in Table 1, below.
EXAMPLES II TO VI The same procedure as that of Example I was repeated, except for using the pressure of the high pressure pump according to the indication of Table 1, below. The results are given in Table 1.
EXAMPLE VII The same procedure as that of Example I was repeated, except for using ceria (Ce02, 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 (Zr02, surface area 30 m2/g) instead of silica. The results are given in Table 1, below.
EXAMPLES IX TO XIII The same procedure as that of Example I was repeated, except that the pressures of the high pressure pump and the number of the counter collisions were taken as indicated in Table 1, below, The results are given in Table 1.
EXAMPLE XIV The same procedure as that of Example I was repeated, except that a 20% KOH solution was not used.
Table 1
Solid Particle Avg.
No. of Metal Press. No. of Content Distribution Particle Examp. Oxide (atm) Collision (%) PH (nm) Size(nm)
I Si02 500 1 13 10.7 40-390 150
II Si02 300 1 13 10.9 50-520 ■ 170
III Si02 800 1 13 10.7 30-370 150
IV Si02 1000 1 13 10.7 30-350 145
V SiO, 1200 1 13 10.7 30-350 145
VI Si02 1500 1 13 10.6 30-320 130
VII Ce02 500 1 13 6.8 40-550 178
VIII Zr02 500 1 13 7.3 40-500 180
IX Si02 500 2 13 10.8 30-350 143
X Si02 500 5 13 10.6 30-280 135
XI Si02 500 10 13 10.5 30-250 120
XII Si02 1200 5 13 10.5 30-300 125
XIII Si02 2500 10 13 10.5 30-250 110
XIV Si02 500 1 13 4.5 40-390 153
XV Si02 500 1 18 10.5 30-370 148
XVI Si02 500 1 25 10.5 30-360 145
XVII Si02 500 1 30 10.5 30-340 143
COMPARATIVE EXAMPLES I TO IX
130 g of commercially available silica (Si02, surface area
200 mVg) , 18 g of 20% KOH solution, and 860 g of deionized water were added, together with 300 g of glass beads with a size of 2 mm, in a 2 liter Dynomill and dispersion was carried out under the dispersion speed and time conditions indicated in Table 2, below.
The results are given in Table 2.
COMPARATIVE EXAMPLE X
The same procedure as that of Comparative Example I was repeated, except that ceria (Ce02, surface area 30 m2/g) , instead of silica, was used in the absence of 20% KOH solution. The results are given in Table 2, below.
COMPARATIVE EXAMPLE XI
The same procedure as that of Comparative Example I was repeated, except for using zirconia (Zr02, surface area 30 m2/g) instead of silica. The results are given in Table 2, below.
TABLE 2
Particle Avg. No. of Dispersion Dispersion Size Particle
Co p. Metal rate Time Distribution Size Examp. Oxide (rpm) (hr) pH (nm) (nm)
I SiO: 1000 1 10.9 50-1200 456
II Si02 1500 1 10.9 50-1200 450
III Si02 2000 1 10.9 50-1100 450
IV SiO: 2500 1 10.8 50-950 430
V Si02 3000 1 10.7 50-800 420
VI Si02 2000 2 10.8 50-1100 420
VII Si02 2000 5 10.9 50-1100 400
VIII Si02 3000 2 10.7 50-750 370
IX Si02 3000 5 10.7 50-750 350
X Ce02 2000 1 7.3 70-1300 570
XI Zr02 2000 1 6.7 80-1550 680
TEST EXAMPLE The slurries obtained in Examples I, II, VII, VIII and Comparative Examples I, X and XI were tested for assessment of polishing performance . p-TEOS coated bare wafers 6 inches thick were polished with the slurries in a Strabaugh Model 6 EC polishing machine under the following abrasion conditions.
-Pad type: IClOOO/Ξuba IV Stacked (Rodel) -Platen Speed : 120 rpm
-Quill Speed : 120 rpm -Pressure : 6 psi -Back Pressure : 0 psi -Temperature : 25 , -Slurry Flow : 150 ml/min
Polishing was performed for 2 min. The polishing rates were measured from the thickness change of the wafers. As for μ - 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.
TABLE 3 Polishing Ability of Slurry
Slurries Particle Size Polishing Performance Distribution (nm) (Avg.) Polishing Nos. of
Rate (A/min) /--scratches
Example I 40-390 (150) 3550 0
Example II 50-520 (170) 3570 12
Example VII 40-520(178) 7210 50
Example VIII 40-500(180) 4830 42
C. Example I 50-1200(456) 3500 158
C. Example X 70-1300(570) 7210 290
C. Example XI 80-1550(680) 6230 170
SS-25 30-390(160) 3430 123
As described hereinbefore, 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. In addition, 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. Further, the process according to the present invention can be carried out by a simple operation. What is more, 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.
Although the invention has been described in detail by referring to certain preferred embodiments, it will be understood that various modifications can be made within the spirit and scope of the invention. The invention is not to be limited except as set forth in the following claims.
Claims
1. 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 with a high pressure pump, and subjected to counter collision for dispersion through two orifices in the dispersion chamber.
«
2. A process as set forth in claim 1, wherein the metal oxide is selected from the group consisting of silica (Si02) , ceria (Ce02) , zirconia (Zr02) and the mixtures thereof.
3. A process as set forth in claim 1, wherein the mixture is allowed to have a flow rate of 300 m/sec or greater by the pressurization with the high pressure pump.
4. A process as set forth in claim 1, wherein the orifices have a diameter ranging from 0.05 to 0.5 mm.
5. A process as set forth in claim 1, wherein the slurry ranges, in particle size, from 30 to 500 nm.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
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KR1019980039212A KR20000006595A (en) | 1998-09-22 | 1998-09-22 | Method for manufacturing metal dielectric slurry for cmp of semiconductor devices |
KR9839212 | 1998-09-22 | ||
PCT/KR1999/000123 WO2000017282A1 (en) | 1998-09-22 | 1999-03-19 | Process for preparing metal oxide slurry suitable for semiconductor chemical mechanical polishing |
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EP1032615A1 true EP1032615A1 (en) | 2000-09-06 |
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EP99909365A Withdrawn EP1032615A1 (en) | 1998-09-22 | 1999-03-19 | Process for preparing metal oxide slurry suitable for semiconductor chemical mechanical polishing |
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EP (1) | EP1032615A1 (en) |
JP (1) | JP2002526593A (en) |
KR (1) | KR20000006595A (en) |
CN (1) | CN1113945C (en) |
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KR20000055131A (en) * | 1999-02-03 | 2000-09-05 | 유현식 | Method for preparing metaloxide slurry for semiconductor element cmp |
KR100310234B1 (en) * | 1999-08-20 | 2001-11-14 | 안복현 | Preparation method of metal oxide slurry for cmp of semiconductor |
KR20020004425A (en) * | 2000-07-05 | 2002-01-16 | 안복현 | Cmp slurry and preparation method thereof |
KR100341141B1 (en) * | 2000-07-26 | 2002-06-20 | 이종학 | Slurry for Polishing Inter Layer Dielectric of Semiconductor in Chemical Mechanical Polishing Process and Method for Preparing the Same |
DE10054345A1 (en) * | 2000-11-02 | 2002-05-08 | Degussa | Aqueous dispersion, process for its preparation and use |
DE10065027A1 (en) | 2000-12-23 | 2002-07-04 | Degussa | Aqueous dispersion, process for its preparation and use |
EP1234800A1 (en) | 2001-02-22 | 2002-08-28 | Degussa Aktiengesellschaft | Aqueous dispersion, process for its production and use thereof |
KR100781870B1 (en) * | 2001-05-14 | 2007-12-05 | 주식회사 하이닉스반도체 | Forming Method for Field Oxide of Semiconductor Device |
DE10239144A1 (en) * | 2002-08-27 | 2004-03-18 | Degussa Ag | dispersion |
KR100827591B1 (en) | 2006-11-27 | 2008-05-07 | 제일모직주식회사 | Chemical mechanical polishing slurry compositions and the precursor composition of the same |
JP5360902B2 (en) * | 2009-11-12 | 2013-12-04 | 株式会社イズミフードマシナリ | Particle polishing method and particle polishing system |
US9120200B2 (en) | 2010-12-28 | 2015-09-01 | Saint-Gobain Ceramics & Plastics, Inc. | Polishing slurry including zirconia particles and a method of using the polishing slurry |
CN106450465A (en) * | 2016-11-21 | 2017-02-22 | 珠海光宇电池有限公司 | Preparation method of slurry of lithium-ion battery |
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US4057939A (en) * | 1975-12-05 | 1977-11-15 | International Business Machines Corporation | Silicon wafer polishing |
US5575837A (en) * | 1993-04-28 | 1996-11-19 | Fujimi Incorporated | Polishing composition |
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- 1998-09-22 KR KR1019980039212A patent/KR20000006595A/en active Search and Examination
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