Cmp technology (be called for short CMP) is the planarization that the difficulty that causes little shadow processing to be gone up focusing on because of plated film height difference when solving unicircuit (IC) and make develops.The cmp technology at first is applied in the manufacturing of 0.5 micron element on a small quantity, and along with dwindling of size, the number of plies that cmp is used is also more and more.To 0.25 micron epoch, cmp has become main flow and has been necessary planarization.Generally speaking, being used to make the Ginding process of metallic circuit, is that semiconductor wafer is placed on the spin finishing platform 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) 5225034 discloses a kind of chemical and mechanical grinding fluid, and it comprises AgNO
3, the solid abrasive material, be selected from H
2O
2, HOCl, KOCl, KMgO
4Or CH
3The oxygenant of COOOH.This grinding milk is the copper layer that is used on the grinding semiconductor chip, to make the copper cash on the wafer.
United States Patent (USP) 5209816 discloses a kind of use chemical and mechanical grinding fluid, and with the method that the metal level that will contain Al or Ti polishes, 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) 4959113 is the method that makes the use abrasive composition with the surface, burnished metal about a kind of.This water-based abrasive composition comprises water, abrasive (CeO for example
2, Al
2O
3, ZrO
2, TiO
2, SiO
2, SiC, SnO
2, TiC), with a kind of salt, the negatively charged ion of the metallic cation of this salt containing element periodictable IIA, IIIA, IVA or IVB family and chlorion, bromide anion, iodide ion, nitrate radical, sulfate radical, phosphate radical or mistake chlorate anions.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) 5391258 discloses a kind of abrasive composition that is used to polish the mixture of siliceous, silicon-dioxide or silicate, and it still comprises hydrogen peroxide and Potassium Hydrogen Phthalate except that comprising abrasive grains.
United States Patent (USP) 5114437 is the polishing composition that is used for the polished aluminum base material about a kind of, and 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) 5084071 is that its employed polishing slurries comprise aluminum oxide, abrasive grains (for example, the SiO less than 1 weight % about a kind of method of chemical machinery polishing slurries so that the electronic component base material is polished of using
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) 5336542 discloses a kind of polishing composition, and it comprises alumina abrasive particles, and one selects from the polyamino carboxylic acid (for example, EDTA) or the sequestrant of its sodium or sylvite.This polishing composition can further comprise boehmite or aluminium salt.
United States Patent (USP) 5340370 discloses a kind of slurries that are used for the chemical machinery polishing of tungsten for example or tungsten nitride film, and it comprises hydroferricyanic acid potassium oxygenant, abrasive and water for the film use, and wherein these slurries have 2 to 4 pH value.
United States Patent (USP) 5516346 discloses a kind of slurries that are used for chemical machinery polishing titanium film, and it comprises concentration and is enough to Potassium monofluoride and abrasive (for example silicon oxide) with this titanium film complexing (complex), and wherein these slurries have and are lower than 8 pH value.
WO96/16436 discloses a kind of chemical and mechanical grinding fluid, and it comprises the water-based interfacial agent suspension of the abrasive grains, molysite oxygenant and propylene glycol and the methyl p-hydroxybenzoate that have less than 0.400 micron median size.
Generally be used for promoting the salt of grinding rate to contain iron ion (Fe (NO for example
3)
3Or K
3Fe (CN)
6) or potassium ion (KIO for example
3), yet these metal ions can pollute wafer and CMP equipment, increase the workload of follow-up cleaning and reduce the time limit of service of CMP processing units.In addition, potassium ion has suitable mobility, penetrates dielectric layer easily, reduces the reliability of IC.
In IC processing, Ta or TaN film often are used to improve the tackiness of copper to insulating layer of silicon oxide, and Ta and TaN film also can be used as the metal of barrier film (barrier film) in addition.In theory, Ta and TaN remove speed should with Cu to remove speed close, yet the Ta metal is the metal with high resistance chemical because it is difficult for oxidation, in copper processing, the grinding of Ta metal is to be difficult to most in the skill overcome always.Simultaneously, because that barrier film is difficult to is worn, often cause the problem of copper cash depression.
In sum, in the semiconductor machining skill, still need seek more economical, have more usefulness and can reduce the Chemicomechanically grinding composition of metallic circuit depression.
The present invention system provides a kind of Chemicomechanically grinding composition that is used for semiconductor machining, it is characterized in that comprising the electrical chemical of water soluble negative.Electronegativity chemical used in the present invention can be covered in process of lapping on the metallic film, for example on the copper film surface, therefore can reduce the generation of metallic circuit depression in the metallic circuit in the cmp processing effectively.By the appended Fig. 1 of present specification as can be known, because electronegativity chemical used in the present invention can cover on the metallic film, after adding this electronegativity chemical in the grinding milk, can suppress the grinding rate of metal under the low pressure in process of lapping.
Electronegativity chemical used in the present invention can be and anyly can effectively be covered in person on the metallic film surface, it is preferable be comprise propylene acid group, phosphate radical, sulfate radical or sulfonate radical the electronegativity compound (for example, alkylphosphonic acid carboxylic acid root, alkylsulphonic acid ammonium and alkylsurfuric acid ammonium), polymkeric substance and/or multipolymer, or the mixture of these compounds, polymkeric substance and/or multipolymer.
One specific embodiment according to the present invention, Chemicomechanically grinding composition of the present invention can be prepared into the slurries form, and this slurries system comprises the aqueous medium of 70-99.5 weight %; 0.1-25 weight % is preferably 0.5-15 weight %, is more preferred from the abrasive grains of 0.5-8 weight %; 0.01-2.0 weight % is more preferred from 0.01-1.0 weight %, the best is grinding promotor and the 0.01-1 weight % of 0.1-1.0 weight %, is preferably 0.03-0.5 weight %, is more preferred from the electrical chemical of water soluble negative of 0.08-0.5 weight %.The Chemicomechanically grinding composition that the present invention is the slurries form can further comprise oxygenant.
The employed abrasive grains of grinding milk of the present invention 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
4Or its mixture.These abrasive grains have advantages such as higher degree, high-specific surface area and narrow size distribution, therefore are applicable in the abrasive composition as abrasive grains.
The grinding promotor that grinding milk of the present invention comprised, can be in the processing oneself grinding rate person who can be used for promoting in the semiconductor machining grinding milk of knowing.Another specific embodiment according to the present invention, the grinding promotor that can be used in the grinding milk of the present invention is to comprise following binding substances: (1) is selected from the composition of phosphorous acid, phosphite or its mixture; And (2) are selected from the composition of the mixture of amino acid, amino acid salts, carboxylic acid, carboxylate salt or these acid and/or salt.Wherein, amino acid for example can be selected from Padil, sarkosine or L-Ala, and wherein, carboxylic acid can be selected from formic acid, acetate, propionic acid, butyric acid, valeric acid, caproic acid, propanedioic acid, pentanedioic acid, hexanodioic acid, citric acid, oxysuccinic acid, tartrate and oxalic acid.
Chemicomechanically grinding 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 prepared into and be the slurries shape, preferable system uses the deionized water of knowing.
Chemicomechanically grinding composition of the present invention still can comprise in other cmp skill known but unlikely effect to abrasive composition of the present invention causes the composition of disadvantageous effect.For example in copper processing, can comprise and know the employed benzotriazole of abrasive composition and/or its derivative, to suppress the quick corrosion of copper.
According to the present invention, when grinding milk comprised the deionized water of 80-99.5 weight %, the solids content of slurries can be 0.5-15 weight %, was preferably 0.5-10 weight %, was more preferred from 0.5-5 weight %.Then additive as indicated above is imported in the high purity slurries of gained, add again acid or alkali with the pH value of control slurries between required scope.
Following examples will the present invention is further illustrated, is not in order to limiting the scope of the invention, and modification and change that any personage who is familiar with this skill can reach easily all are covered by in the scope of the present invention.
Grind test
A. instrument: IPEC/Westech 472
B. condition: pressure: 4psi
Back pressure: 0.5psi
Temperature: 25 ℃
The speed of mainshaft: 55rpm
Platen rotating speed: 50rpm
Base pattern: IC1400
Slurry flow rate: 150 ml/min
C. wafer: copper film and tantalum nitride membrane available from Silicon ValleyMicroelectinics.Inc., lie in thermal oxide, the PVD-Ta of 300_ and the PVD copper film of 10000_ ± 5% of deposition 1000_ silicon oxide on 6 inches silicon wafers.
D. slurries: the slurries and the 30%H that get the embodiment gained
2O
2Evenly test after the stirring with 9: 1 volume ratios.
Grind testing process:
Before and after grinding, must measure the thickness of film with elcometer.Metallic membrane measures the sheet resistance of film with four-point probe, convert through following formula the thickness of film:
T * R=specific resistance
Wherein T is a film thickness (_), 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 RS 75 type machines of KLA-Tencor company to measure the thickness of metal level.The measuring method system of polishing speed records metal level thickness T with above-mentioned RS 75 type machines earlier
1, grind 1 minute with the slurries among the embodiment respectively after, the Evergreen Model 10X type machine clean wafers with solid-state instrument company (SolidState Equipment Corporation) afterwards, dries up wafer.Measure the thickness T of metal level again with RS 75 type machines
2With T
1-T
2Be the polishing speed of metal level.
Embodiment 1
Prepare grinding milk with colloidal silica as abrasive grains.Slurries are composed as follows:
Colloidal silica: 3.0 weight %;
Benzotriazole content: 0.1 weight %;
Phosphorous acid: 0.2 weight %;
Padil: 0.2 weight %;
All the other content are for adjusting acid or the alkali and the deionized water of pH value.
The grinding rate of gained slurries is as shown in table 1.
Embodiment 2
The slurries of preparation and embodiment 1 described same composition, but additionally add the RS-610 (it is a kind of polymkeric substance of phosphorous acid group) that 0.045 weight % is produced by RHONE-POULENC company.
The grinding rate of gained slurries is as shown in table 1.
Embodiment 3
The preparation and the slurries of embodiment 1 described same composition, but additionally add the dodecyl sodium sulfonate ammonium of 0.045 weight %.
The grinding rate of gained slurries is as shown in table 1.
Embodiment 4
The slurries of preparation and embodiment 1 described same composition, but additionally add the RE-610 (it is a kind of polymkeric substance of phosphorous acid group) that 0.045 weight % is produced by RHONE-POULENC company.
The grinding rate of gained slurries is as shown in table 1.
Table 1
Grinding milk | The abrasive grains kind | Solid content % | The electronegativity chemical | The pH value | The copper grinding rate (_/min) |
????4psi | ????3psi | ????2psi | ????1psi |
Embodiment 1 | Colloidal silica | ????3 | --- | ?3.5~4.0 | ????5601 | ????5081 | ????4496 | ????2864 |
Embodiment 2 | Colloidal silica | ????3 | The RS-610 of RHONE-POULENC company | ?3.5~4.0 | ????3665 | ????2609 | ????647 | ????21 |
Embodiment 3 | Colloidal silica | ????3 | The dodecyl sodium sulfonate ammonium | ?3.5~4.0 | ????4686 | ????2822 | ????1851 | ????63 |
Embodiment 4 | Colloidal silica | ????3 | The RE-610 of RHONE-POULENC company | ?3.5~4.0 | ????4602 | ????2744 | ????1961 | ????569 |
The figure (Fig. 1) that the gained grinding rate is made by pressure different in the table 1 as can be known, the abrasive composition that the present invention adds the electronegativity chemical can effectively suppress the grinding rate of metal under low pressure, therefore, can avoid the formation of metal depression.