Abrasive tool making process – material – or composition – With inorganic material
Reexamination Certificate
1999-03-15
2001-01-09
Koslow, C. Melissa (Department: 1755)
Abrasive tool making process, material, or composition
With inorganic material
C051S308000, C051S309000
Reexamination Certificate
active
06171352
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention pertains to chemical mechanical abrasive compositions. The chemical mechanical abrasive compositions of the invention are useful in polishing the surface of a semiconductor wafer.
2. Description of the Prior Art
In the semiconductor industry, semiconductor wafer surface polishing is a universally used technique, because it enhances the smoothness on the semiconductor wafer and a dielectric layer and facilitates the production of wire circuits. In general, the polishing method for producing a wire circuit comprises mounting a semiconductor wafer on a spinning platen equipped with an abrasive head and applying an abrasive slurry comprising abrasive particles and an oxidant to the surface of the wafer to enhance the abrasive efficacy.
U.S. Pat. No. 5,225,034 discloses a chemical mechanical abrasive slurry which comprises AgNO
3
, solid abrasive particles, and an oxidant selected from H
2
O
2
, HOCl, KOCl, KMgO
4
, or CH
3
COOOH. The slurry is used for polishing a copper layer on a semiconductor wafer so as to produce copper wire on the wafer.
U.S. Pat. No. 5,209,816 discloses a method for polishing an Al- or Ti-containing metal layer with a chemical mechanical abrasive slurry. The abrasive slurry contains, in addition to the solid abrasive material, about 0.1-20% by volume of H
3
PO
4
and about 1-30% by volume of H
2
O
2
.
U.S. Pat. No. 4,959,113 discloses a method of using an aqueous abrasive composition for polishing metal surfaces. The aqueous abrasive composition comprises water, an abrasive, e.g. CeO
2
, Al
2
O
3
, ZrO
2
, TiO
2
, SiO
2
, SiC, SnO
2
, or TiC, and a salt including a metal cation of Group IIA, IIIA, IVA or IVB and an anion of chloride, bromide, iodide, nitrate, sulfate, phosphate or perchlorate. This patent also discloses the use of hydrochloric acid, nitric acid, phosphoric acid or sulfuric acid to adjust the pH of the abrasive composition to be in the range of 1 to 6.
U.S. Pat. No. 5,391,258 discloses an abrasive composition for polishing silicon, silica or silicate composite. The abrasive composition comprises, in addition to abrasive particles, hydrogen peroxide and potassium hydrogen phthalate.
U.S. Pat. No. 5,114,437 discloses a polishing composition for an aluminum substrate comprising an alumina polishing agent having an average particle size of 0.2 to 5 &mgr;m, and a polishing accelerator selected from the group consisting of chromium(III) nitrate, lanthanum nitrate, ammonium cerium(III) nitrate, and neodymium nitrate.
U.S. Pat. No. 5,084,071 discloses a chemical mechanical polishing slurry for an electronic component substrate. The polishing slurry comprises abrasive particles (e.g. SiO
2
, CeO
2
, SiC, Si
3
N
4
, or Fe
2
O
3
particles) containing no more than 1 percent weight of alumina, a transition metal chelated salt (e.g. ammonium iron EDTA) for use as a polishing accelerator, and a solvent for said salt.
U.S. Pat. No. 5,480,476 discusses the effect of Ce4+ and Zr4+ cations on the polishing rate of SiO
2
-based abrasives.
U.S. Pat. No. 5,366,542 discloses a polishing composition comprising alumina abrasive particles, and a chelating agent selected from the group consisting of polyaminocarboxylic acid (e.g. EDTA) and sodium and potassium salts thereof. The composition may further comprise beohmit or an aluminum salt.
U.S. Pat. No. 5,340,370 discloses a chemical mechanical polishing slurry for tungsten or tungsten nitride film, which comprises an oxidizing agent such as potassium ferricyanide, an abrasive, and water, and has a pH between 2 and 4.
U.S. Pat. No. 5,516,346 discloses a slurry for chemical mechanically polishing a titanium film, said slurry comprising potassium fluoride in a concentration sufficient to complex said titanium film, and an abrasive, such as silica, and having a pH less than eight.
WO 96/16436 discloses a chemical mechanical polishing slurry which comprises abrasive particles having a median particle diameter less than 0.400 microns, a ferric salt oxidant, and a suspension agent of an aqueous surfactant which is a mixture of propyleneglycol and methylparaben.
U.S. Pat. No. 5,527,423 discloses a chemical mechanical slurry for polishing a metal layer, which comprises an oxidizing component such as iron nitrate, an aluminum particle comprising at least 50% gamma phase, and nonionic surfactants such as polyalkyl siloxanes, or polyoxyalkylene ethers.
It is known in the art that if the abrasive composition viscosity is too high to be flowable, the abrasive particles will deposit on the abrasive pad and be difficult to remove, possibly scratching the wafer surfaces. Although U.S. Pat. No. 5,527,423 discloses the use of nonionic surfactants, such as polyalkyl siloxanes or polyoxyalkylene ethers, these surfactants cannot effectively reduce the viscosity of the abrasive composition.
Accordingly, need still exists for abrasive compositions which are more economical and have high polishing performance, and for chemical mechanical abrasive compositions with reduced viscosity.
SUMMARY OF THE INVENTION
The present invention provides a chemical mechanical abrasive composition for semiconductor processing, which comprises 70-95% by weight of an aqueous medium, 1-25% by weight of an abrasive, and 0.1-20% by weight of an abrasion accelerator, wherein the abrasion accelerator comprises a monocarboxy group- or an amido group-containing compound and optionally a nitrate salt. The chemical mechanical abrasive composition of the present invention can further comprise an anionic surfactant, such as polycarboxylic acid or polyacrylic acid copolymer, or the salts thereof, to reduce the viscosity of the abrasive composition.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides a chemical mechanical abrasive composition for semiconductor processing, which comprises 70-95% by weight of an aqueous medium, 1-25% by weight of, preferably 3-10% by weight of, and more preferably 4-6% by weight of, an abrasive, and 0.1-20% by weight of, preferably 1-10% by weight of, and more preferably 2-5% by weight of, an abrasion accelerator, wherein the abrasion accelerator comprises a monocarboxy group- or an amido group-containing compound and optionally a nitrate salt.
The chemical mechanical abrasive composition of the present invention can further comprise 1-15% by weight of, and preferably 4-8% by weight of, an oxidant.
According to the present invention, the abrasive used in the abrasive composition can be any commercially available abrasive agent in particle form, such as SiO
2
, Al
2
O
3
, ZrO
2
, CeO
2
, SiC, Fe
2
O
3
, TiO
2
, Si
3
N
4
, or any mixture thereof.
The oxidant used in the abrasive composition, according to the present invention, can be any suitable commercial oxidant, such as peroxides, chlorates, chlorites, perchlorates, bromates, bromites, perbromate, nitrates, or the mixture thereof.
The monocarboxy group containing compound used in the abrasive composition according to the present invention is selected from:
(a) the monocarboxy group compound of the formula:
in which, R
1
is hydrogen, C
1
-C
6
alkyl or C
1
-C
6
hydroxyalkyl; and R
2
is hydrogen, ammonium, or alkali metal ions and preferably, potassium ion; or
(b) Aminoacid compounds.
Examples of the above compound (a) include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid, glycolic acid, lactic acid and the salts thereof Examples of the above aminoacid compounds (b) include glycine, sarcosine, dimethylglycine, alanine and the salts thereof. Further examples of aminoacid compounds (b) include mixtures of two or more of the above acids and/or their salts.
Examples of the amido group-containing compound used in the present invention as an abrasion accelerator include foramide, acetamide, propionamide, N-methylforamide, N-methylacetamide, urea, methylurea, ethylurea, dimethylurea and diethylurea.
The nitrate optionally used in the present invention is the alkali metal salt or ammonium salt well known to a person with ordinary skill in the art.
The abrasi
Lee Tsung-Ho
Yeh Tsui-Ping
Eternal Chemical Co., Ltd.
Koslow C. Melissa
Scully Scott Murphy & Presser
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