The Chemicomechanically grinding composition that manufacture of semiconductor is used
The present invention relates to a kind of Chemicomechanically grinding composition.Abrasive composition tool high stability of the present invention can be effectively applied to the grinding of semiconductor wafer surface.
In semi-conductor industry, the grinding of semiconductor wafer surface has been the technology of widespread use, to improve the flatness of semiconductor wafer and dielectric layer, is beneficial to make metallic circuit.Generally speaking, being used to make the Ginding process of metallic circuit, is that semiconductor wafer is placed on the spin finishing plane of being furnished with grinding head, uses the grinding milk that comprises polishing particles and oxygenant in wafer surface, grinds effect to promote.
United States Patent (USP) the 5th, 225 discloses a kind of chemical and mechanical grinding fluid No. 034, and it comprises AgNO
3, solid abrasive material and be selected from H
2O
2, HOCl, KOCl, KMgO
4Or CH
3The oxygenant of COOOH.This grinding milk is used for the copper layer on the grinding semiconductor chip, to make the copper cash on the wafer.
United States Patent (USP) the 5th, 209, a kind of chemical and mechanical grinding fluid that uses of No. 816 announcements will be will contain the method for Al or Ti metal level polishing, and its grinding milk still comprises the H of about 0.1-20 volume % except that comprising the solid abrasive material
3PO
4H with about 1-30 volume %
2O
2
United States Patent (USP) the 4th, 959 relates to a kind of method that makes the use abrasive composition with the surface, burnished metal No. 113.This water-based abrasive composition comprises water, abrasive (CeO for example
2, Al
2O
3, ZrO
2, TiO
2, SiO
2, SiC, SnO
2And TiC), with a kind of salt, the metallic cation of this salt containing element periodictable IIA, IIIA, IVA or IVB family and the negatively charged ion of chlorion, bromide anion, iodide ion, nitrate radical, sulfate radical, phosphate radical or peroxide acid group.This United States Patent (USP) also teaching uses hydrochloric acid, nitric acid, phosphoric acid or sulfuric acid so that its water-based abrasive composition is deployed into pH=1-6.
United States Patent (USP) the 5th, 391 discloses a kind of abrasive composition that is used to polish the mixture of siliceous, silica or silicate for No. 258, and it still comprises hydrogen peroxide and Potassium Hydrogen Phthalate except that comprising abrasive grains.
United States Patent (USP) the 5th, 114, relate to a kind of polishing composition that is used for the polished aluminum base material for No. 437, it comprises average particle size particle size between the aluminum oxide polishing agent of 0.2 to 5 μ m and be selected from the polishing promotor of chromium nitrate (III), lanthanum nitrate, cerous nitrate (III) ammonium or neodymium nitrate.
United States Patent (USP) 5,084 relates to a kind of chemical machinery polishing slurries that use for No. 071 with the method with the polishing of electronic component base material, and its employed polishing slurries comprise aluminum oxide, abrasive grains (for example, the SiO less than 1 weight %
2, CeO
2, SiC, Si
3N
4Or Fe
2O
3), as the transition metal chelating salt (for example, EDTA iron ammonium) of mill efficiency promotor, and for the solvent of this salt use.
United States Patent (USP) the 5th, 480, No. 476 is to inquire into Ce
4+And Zr
4+Positively charged ion is to SiO
2The influence of type abrasive polishing speed.
United States Patent (USP) the 5th, 366 discloses a kind of polishing composition No. 542, and it comprises alumina abrasive particles, and a sequestrant that is selected from polyamines yl carboxylic acid (for example EDTA) or its sodium or sylvite.This polishing composition can further comprise boehmite or aluminium salt.
United States Patent (USP) the 5th, 430 discloses a kind of slurries that are used for the chemical machinery polishing of tungsten for example or tungsten nitride film for No. 370, and it comprises Tripotassium iron hexacyanide oxygenant, abrasive and water for the film use, and wherein these slurries have 2 to 4 pH value.
United States Patent (USP) the 5th, 516 discloses a kind of slurries that are used for chemical machinery polishing titanium film No. 346, and it comprises concentration and is enough to Potassium monofluoride and abrasive (for example silicon oxide) with this titanium film misfit, and wherein these slurries have and are lower than 8 pH value.
WO96/16436 discloses a kind of chemical machinery polishing slurries, and it comprises and has less than 0.400 micron intermediate value particulate abrasive grains, molysite oxygenant, and the aqueous tenside suspension of propylene glycol and methyl p-hydroxybenzoate.
United States Patent (USP) the 5th, 476, disclose a kind of slurries that are used for cmp light metal level for No. 606, its comprise oxidized metal misfit thing (for example iron nitrate) oxygenant, contain at least 50% γ-phase fused alumina particles, with for example nonionic surfactant additive of poly-alkylsiloxane or polyoxyalkylene ether.
The grinding milk of above-mentioned Prior Art institute teaching all can't avoid causing the pollution of potassium ion or transition metal, or because of adopting high molecular type surfactant, cause except that when grinding, bubbling easily wafer surface local grind unequal, rugosity improves, more because polymer compound water-soluble not good very easily causes higher contamination of heavy.
In addition, United States Patent (USP) the 5th, 476, though No. 606 teaching is used the grinding rate of low-molecular-weight hydroxyl carboxylic acid with the inhibited oxidation thing, thereby the grinding selection rate of raising metal/oxide, yet because hydroxycarboxylic acid can't improve the Zeta-potential (that is electro kinetic potential) of abrasive grains, therefore, it often causes the unstable of slurries after adding.
In sum, in the skill of manufacture of semiconductor, still the enterprise seek to have higher quality Chemicomechanically grinding composition, to overcome the shortcoming that above-mentioned Prior Art abrasive composition is faced.
The purpose of this invention is to provide a kind of Chemicomechanically grinding composition that is used for manufacture of semiconductor abrasive metal film, it comprises the abrasive grains of 1-25 weight %; And while of 0.1-20 weight % as the buffer reagent of grinding promotor, wherein this buffer reagent comprises the salt of the compound that contains persulfate or iron content (III) and contains carboxyl or the compound of amide group.
The invention provides a kind of Chemicomechanically grinding composition that is used at manufacture of semiconductor abrasive metal film, it comprises 1-25 weight %, is preferably the abrasive grains of 3-10 weight %; And 0.1-20 weight %, while that is preferably 6-15 weight % be as the buffer reagent of grinding promotor, and wherein this buffer reagent comprises the salt of the compound that contains persulfate or iron content (III) and contains carboxyl or the compound of amide-containing.Chemicomechanically grinding composition of the present invention can further comprise 1-10 weight %, is preferably the oxygenant of 4-6 weight %.
According to the present invention, the employed abrasive grains of abrasive composition can be general commercially available person, for example SiO
2, Al
2O
3, ZrO
2, CeO
2, SiC, Fe
2O
3, TiO
2, Si
3N
4, or its mixture.These abrasive grains have higher degree, high-specific surface area, and advantage such as narrow size distribution, therefore are applicable in the Chemicomechanically grinding composition as abrasive grains.
The oxygenant that can be used among the present invention is general commercially available person, for example H
2O
2, KIO
3, KBrO
3, KMnO
4, K
2Cr
2O
7, K
2Mn
2O
7, HOCl, peracetic acid (CH
3Or its mixture COOOH).
According to the present invention, comprise H as the persulfate examples for compounds that contains of buffer reagent composition
2S
2O
8, K
2S
2O
8, (NH
4)
2S
2O
8, Na
2S
2O
8, or its mixture, and comprise the Tripotassium iron hexacyanide, ammonium sulfate iron (III), iron nitrate (III) or its mixture as the salt example of the iron content (III) of buffer reagent composition.
The carboxylated compound that can be used in the buffer reagent of the present invention is selected from:
(1) as shown in the formula mono carboxylic compound:
Wherein, R
1Be hydrogen, C
1-C
6Alkyl or C
1-C
6Hydroxyalkyl; And R
2Be hydrogen, ammonium ion or alkali, metal ion (being preferably potassium ion).
This kind mono carboxylic examples for compounds comprises: formic acid, acetate, propionic acid, butyric acid, valeric acid, caproic acid, hydroxacetic acid, lactic acid, and its esters.
(2) as shown in the formula dicarboxylic compounds:
Wherein, R
4Be a singly-bound, C
1-C
6Alkyl or C
1-C
6Hydroxyalkyl; And R
2And R
3Be hydrogen, ammonium ion or alkalimetal ion (being preferably potassium ion).
The example of this kind dicarboxylic compounds comprises: oxalic acid (oxalic acid), propanedioic acid, Succinic Acid (succsinic acid), pentanedioic acid, hydroxy-butanedioic acid (oxysuccinic acid), tartrate, tetrahydroxyadipic acid and its esters.
(3) three carboxylic compounds, for example citric acid and its esters.
(4) amino-acid compound, for example glycine, sarkosine, N-methylsarcosine, L-Ala and its esters.
Can be used for comprising: methane amide, ethanamide, propionic acid amide, N-methylformamide, N-methylacetamide, urea, methyl urea, ethyl carbamide, dimethyl urea and diethyl urea as the amide-containing examples for compounds of buffer reagent composition of the present invention.
Abrasive composition of the present invention is employed can to provide following advantage as the buffer reagent additive that grinds promotor:
(1) because the variation of grinding milk pH value can influence the Zeta-potential of abrasive grains, therefore, it is very important for grinding milk to keep stable p H value.Buffer reagent used in the present invention can provide grinding milk between 1.5 to 8.5 pH value, therefore has the function of stable grinding milk pH value.
Therefore (2) buffer reagent used in the present invention is water-soluble splendid, is easy to remove and can remain on the wafer.
(3) buffer reagent used in the present invention has bigger molecule, causes the pollution of wafer in its unlikely infiltration wafer.
(4) buffer reagent used in the present invention is general common chemical, and it does not more have danger, therefore can significantly reduce the dangerous of manufacture of semiconductor worker and unlikely environment is polluted.
(5) composition out of the ordinary of buffer reagent of the present invention is the lower compound of corrodibility, yet, when the compound that these corrodibility are lower is used in combination according to the present invention, will produce non-expected extremely strong corrodibility, therefore, can effectively improve the speed that scrapes off of metallic film.
Abrasive composition of the present invention can comprise, and for example, water is as medium.In preparation process, can make water so that abrasive composition is the slurries shape, be preferably and use conventional deionized water.
Abrasive composition of the present invention can be by general ordinary method preparation.For example, can earlier abrasive grains be added in the entry, continue to stir, until the abrasive grains formation slurries that suspend in water fully with agitator with high shear force.After, continue to add entry, so that the abrasive grains in the slurries reaches required solids content.According to the present invention, the solids content of slurries is 1-25 weight %, is preferably 3-10 weight %.Then additive as indicated above is imported in the high purity slurries of gained, adds for example ammoniacal liquor again, with the pH value of control slurries between required scope.For example, when the metallic film of desire grinding is W film, the pH value can be controlled between 1.5-2.5, be preferably between the 1.8-2.3; When the metallic film of desire grinding is the Al film, the pH value is controlled between the 3.0-4.5, be preferably between the 3.8-4.2; And when the metallic film of desire grinding is the Cu film, the pH value is controlled between the 5.5-9.0, be preferably between the 6.0-7.0.At last, with dope filtration to obtain abrasive composition of the present invention.The preparation process of abrasive composition of the present invention can be carried out under any suitable temperature, is preferably under 20-40 ℃ temperature and carries out.
Following examples will the present invention is further illustrated, and only non-in order to limit the scope of the invention, modification and change that any personage who has the knack of this skill can reach easily all are covered by in the scope of the present invention.Embodiment 1
Use the silicon-dioxide that Degussa produced in the present embodiment, it has following character:
PH value circle of (1) 5% waterborne suspension is between 3.6-4.3;
(2) specific surface area is 40-130m
2/ g; And
(3) proportion is≤0.7g/ml.
Under room temperature, 5 kilograms of above-mentioned silicon-dioxide are added in 20 kilograms the deionized water, continue to stir with the high shear force agitator, suspend in water fully and be the slurries shape until silicon-dioxide.And then add 20 kilograms deionized water dilution slurries, so that the solids content of slurries is for being slightly larger than 11%.Then 1.5 kilograms oxalic acid (oxalic acid) and 3 kilograms ammonium sulfate iron (III) are added in the slurries, it is dissolved in the slurries rapidly.Continue to stir after 3 hours, again with NH
4The pH value that OH adjusts slurries is about 2.0.Filter slurries to make Chemicomechanically grinding composition of the present invention, its solids content is about 10%.The grinding test result of gained abrasive composition is listed in hereinafter in the table 1 now.Embodiment 2
Heavily cover the identical preparation process of embodiment 1, only replace oxalic acid with 1.5 kilograms formic acid.The grinding test result of gained abrasive composition is listed in hereinafter in the table 1 now.Embodiment 3
Heavily cover the identical preparation process of embodiment 1, only replace silicon-dioxide with 5 kilograms of aluminum oxide (Sumitomo chemical company is produced, model AKP-G008), and with 1.5 kilograms of citric acids replacement oxalic acids.The grinding test result of gained abrasive composition is listed in hereinafter in the table 1 now.Embodiment 4
Heavily cover the identical preparation process of embodiment 3, only replace citric acid with 1.5 kilograms hydroxacetic acid.The grinding test result of gained abrasive composition is listed in hereinafter in the table 1 now.Comparative example 1
Heavily cover the identical system of embodiment 1, only do not add ammonium sulfate iron (III).The grinding test result of gained abrasive composition is listed in hereinafter in the table 1 now.Comparative example 2
Heavily cover the identical preparation process of embodiment 3, only do not add ammonium sulfate iron (III).The grinding test result of gained abrasive composition is listed in hereinafter in the table 1 now.Grind test
A, instrument: PIEC/Westch472
B, condition: pressure: 5psi
Temperature: 25 ℃
The speed of mainshaft: 45rpm
Platen rotating speed: 42rpm
Base pattern: Rodel IC 1400
Slurry flow rate: 150 ml/min
C, wafer:
(1) W film: available from Silicon Valley Microelectronics, Inc. is the film with the deposit 0.8 micron ± 5% on 6 inches silicon wafers of CVD technology
(2) Ti film: available from Silicon Valley Microelectronics, Inc. is the film with the deposit 0.5 micron ± 5% on 6 inches silicon wafers of CVD technology
(3) TiN film: available from Silicon Valley Microelectronics, Inc. is the film with CVD technology 0.5 micron ± % of deposit on 6 inches silicon wafers
(4) sull; Be to entrust country millimicron element laboratory, the silicon-dioxide that heat generates on silicon substrate.
D, slurries: get the foregoing description 1-4 and comparative example 1-2 gained slurries, be equipped with equal volume, contain 2 weight %H
2O
2The aqueous solution, evenly stir and test the grinding testing process after 15 minutes:
Before and after grinding, all need to measure the thickness of film with elcometer.Metallic membrane measures the sheet resistance of film with four-point probe, again through following formula convert the thickness of film:
T * R=specific resistance wherein, T is film thickness (A), and R is sheet resistance (Ω/cm
2), for various metallic films, (Ω/cm) is a constant to specific resistance.
The present invention adopts the RS75 type machine of KLA-Tencor company to measure the thickness of metal level.
The thickness of oxide compound can directly record by optical principle.The present invention is to use the SM300 type machine of KLA-Tencor company to measure the thickness of thermal oxide.The mensuration mode of polishing speed is as follows:
Record the thickness T of metal level earlier with above-mentioned RS75 type machine
1, respectively with the foregoing description slurries, grind 1 minute according to the aforesaid operations condition after, with the Evergreen Model 10X type machine cleaning machine clean wafers of solid-state instrument company (Solid StateEquipment Corporation), after, wafer is dried up.Measure the thickness T of metal level again with RS75 type machine
2With T
1-T
2Be the polishing speed of metal level.
In addition, record the thickness T of thermal oxide with SM300 type machine
3, with identical slurries, the identical operations condition was ground after 1 minute, and through cleaning, recording thickness is T
4With T
3-T
4Be the polishing speed of thermal oxide.
The gained test data is listed in the table below in 1 now.
Table 1
Embodiment | Remove speed |
W (/minute) | Ti (/minute) | TiN (/minute) | SiO
2(/minute)
|
Embodiment 1 | 4145 | 2976 | 983 | 237 |
Embodiment 2 | 4315 | 2921 | 950 | 201 |
Embodiment 3 | 5008 | 2337 | 3523 | 102 |
Embodiment 4 | 5273 | 1368 | 3899 | 210 |
Comparative example 1 | 572 | 247 | 687 | 167 |
Comparative example 2 | 1161 | 1198 | 1695 | 233 |
Embodiment 5
Repeat the identical preparation process of embodiment 3, only replace citric acid with 3 kilograms formic acid, and with 2 kilograms of (NH
4)
2S
2O
8Replace ammonium sulfate iron (III), the pH value is adjusted to 4.0 with ammoniacal liquor.The grinding test result of gained abrasive composition is listed in hereinafter in the table 2 now.Embodiment 6
Repeat the identical preparation process of embodiment 5, only replace formic acid, and the pH value is adjusted to 4.0 with ammoniacal liquor with 3 kilograms glycine.The grinding test result of gained abrasive composition is listed in hereinafter in the table 2 now.Embodiment 7
Repeat the identical preparation process of embodiment 5, only replace formic acid, and the pH value is adjusted to 4.0 with ammoniacal liquor with 3 kilograms methane amide.The grinding test result of gained abrasive composition is listed in hereinafter in the table 2 now.Comparative example 3
Heavily cover the identical preparation process of embodiment 5, only do not add (NH
4)
2S
2O
8The grinding test result of gained abrasive composition is listed in hereinafter in the table 2 now.Grind test
A. instrument: IPEC/Westech472
B. condition: pressure: 5psi
Temperature: 25 ℃
The speed of mainshaft: 45rpm
Platen rotating speed: 42rpm
Base pattern: Rodel Politex
Slurry flow rate: 150 ml/min
C. wafer:
(1) Al film: available from Silicon Valley Microelectronics, Inc. is to deposit 0.85 micron ± 5% film on 6 inches silicon wafers with the CVD technology, and purity is Al:98.5%, Si:1%, Cu:0.5%
(2) Ti film: available from Silicon Valley Microelectronics, Inc. is to deposit 0.5 micron ± 5% film on 6 inches silicon wafers with the CVD technology
(3) TiN film: available from Silicon Valley Microelectronics, Inc. is to deposit 0.5 micron ± 5% film on 6 inches silicon wafers with the CVD technology
(4) sull: be to entrust country millimicron element laboratory, the silicon-dioxide that heat generates on silicon substrate
D. slurries: get the foregoing description 5-7 and comparative example 3 gained slurries, be equipped with equal volume and contain 5 weight %H
2O
2The aqueous solution, evenly stir after 15 minutes and test
The grinding testing process is as indicated above, and the gained test data is listed in the table below in 2 now.
Table 2
Embodiment | Remove speed |
Al (/minute) | Ti (/minute) | TiN (/minute) | SiO
2(/minute)
|
Embodiment 5 | 3944 | 1704 | 3318 | 129 |
Embodiment 6 | 4682 | 1223 | 3380 | 117 |
Embodiment 7 | 3552 | 2279 | 4454 | 112 |
Comparative example 3 | 1705 | 673 | 3237 | 192 |
Embodiment 8
Repeat the identical preparation process of embodiment 5, only the pH value is adjusted to 6.5 with ammoniacal liquor.The grinding test result of gained abrasive composition is listed in hereinafter in the table 3 now.Embodiment 9
Heavily cover the identical preparation process of embodiment 6, only the pH value is adjusted to 6.5 with ammoniacal liquor.The grinding test result of gained abrasive composition is listed in hereinafter in the table 3 now.Embodiment 10
Heavily cover the identical preparation process of embodiment 7, only replace formic acid with 1.5 kilograms ethanamide.The grinding test result of gained abrasive composition is listed in hereinafter in the table 3 now.Comparative example 4
Heavily cover the identical preparation process of comparison 3, only the pH value is adjusted to 6.5 with ammoniacal liquor.The grinding test result of gained abrasive composition is listed in hereinafter in the table 3 now.Grind test
A. instrument: IPEC/Westech472
B. condition: pressure: 5psi
Temperature: 25 ℃
The speed of mainshaft: 45rpm
Platen rotating speed: 42rpm
Base pattern: Rodel 1400
Slurry flow rate: 150 ml/min
C. wafer:
(1) Cu film: available from Silicon Valley Microelectronics, Inc. is to deposit 0.85 micron ± 5% film on 6 inches silicon wafers with the CVD technology
(2) Ti film: available from Silicon Valley Microelectronics, Inc. is to deposit 0.5 micron ± 5% film on 6 inches silicon wafers with the CVD technology
(3) TiN film: available from Silicon Valley Microelectronics, Inc. is to deposit 0.5 micron ± 5% film on 6 inches silicon wafers with the CVD technology
(4) sull: be to entrust country millimicron element laboratory, the silicon-dioxide that heat generates on silicon substrate
D. slurries: get the foregoing description 8-11 and comparative example 4 gained slurries, be equipped with equal volume, contain 5 weight %H
2O
2The aqueous solution, evenly stir after 15 minutes and test
The grinding testing process is as indicated above, and the gained test data is listed in the table below in 3 now.
Table 3
Embodiment | Remove speed |
Cu (/minute) | Ti (/minute) | TiN (/minute) | SiO
2(/minute)
|
Embodiment 8 | 7430 | 1804 | 3322 | 194 |
Embodiment 9 | 7217 | 1665 | 4340 | 203 |
Embodiment 10 | 4001 | 1471 | 3677 | 211 |
Comparative example 4 | 7337 | 598 | 1829 | 189 |
As seen from the above embodiment, abrasive composition of the present invention can effectively improve metallic film, the mill efficiency of Ti and TiN film especially, and improve grinding selectivity to Cu/Ti and Cu/TiN.