JP2001144044A - Metal polishing fluid and polishing method using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal polishing fluid which can realize the high CMP speed of tantalum and tantalum oxide, realize high flatness, reduce a dishing value and an erosion value, and form the flush pattern of a metal film with high reliability, and to provide a polishing method using the fluid. SOLUTION: A board on which a film to be polished is formed is pressed against a polishing cloth on a polishing surface plate and, in that state, the polishing surface plate and the board are moved relatively to each other while a metal polishing fluid containing fluorine-containing compound and water is supplied to the polishing cloth.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing liquid for a metal in a wiring step of a semiconductor device and a polishing method using the same.

[0002]

2. Description of the Related Art In recent years, a new fine processing technology has been developed in accordance with high integration and high performance of a semiconductor integrated circuit (hereinafter, referred to as LSI). Chemical mechanical polishing (hereinafter referred to as CMP)
The method is one of them. For example, in an LSI manufacturing process, particularly, in a multilayer wiring forming process, an interlayer insulating film is flattened, a metal plug is formed,
This is a technique frequently used in the formation of embedded wiring. This technique is disclosed, for example, in US Pat. No. 4,944,836.

Recently, use of a copper alloy as a wiring material has been attempted in order to improve the performance of an LSI. However, it is difficult to finely process a copper alloy by a dry etching method frequently used in forming a conventional aluminum alloy wiring. Therefore, a copper alloy thin film is deposited and buried on an insulating film in which a groove is formed in advance, and a copper alloy thin film other than the groove is removed by CMP to form a buried wiring.
The so-called damascene method is mainly employed. This technique is disclosed in, for example, Japanese Patent Application Laid-Open No. 2-278822.

A general method of metal CMP is to attach a polishing pad to a circular polishing platen (platen), immerse the surface of the polishing pad with a metal polishing solution, and press the surface of the substrate on which the metal film is formed. Then, the polishing platen is rotated while applying a predetermined pressure (hereinafter, referred to as a polishing pressure) from the back surface, and the metal film of the convex portion is removed by mechanical friction between the polishing liquid and the convex portion of the metal film. is there.

[0005] The metal polishing liquid used for CMP generally comprises an oxidizing agent and solid abrasive grains, and if necessary, a metal oxide dissolving agent and a protective film forming agent are further added. It is considered that the basic mechanism is to first oxidize the surface of the metal film by oxidation and to scrape off the oxidized layer with solid abrasive grains. The oxide layer on the metal surface of the concave portion does not substantially touch the polishing pad, and the effect of the shaving by the solid abrasive grains does not reach. Therefore, as the CMP proceeds, the metal layer on the convex portion is removed and the substrate surface is flattened. See the Journal of Electrochemical Society (Journal of
Vol. 138, No. 11 (19)
1991), pages 3460-3364.

As a method of increasing the polishing rate by CMP, it is effective to add a metal oxide dissolving agent. It can be interpreted that dissolving the metal oxide particles removed by the solid abrasive grains in the polishing liquid increases the effect of the solid abrasive grains. However, when the oxide layer on the surface of the metal film in the recess is also dissolved (hereinafter referred to as etching) and the surface of the metal film is exposed, the surface of the metal film is further oxidized by the oxidizing agent. It is feared that the flattening effect is impaired. In order to prevent this, a protective film forming agent is further added. It is important to balance the effects of the metal oxide dissolving agent and the protective film forming agent. The oxide layer on the surface of the metal film in the concave portion is not etched so much, the particles of the cut oxide layer are efficiently dissolved, and polishing by CMP is performed. High speed is desirable.

As described above, by adding the metal oxide dissolving agent and the protective film forming agent to add the effect of the chemical reaction, the CMP
The speed (polishing speed by CMP) is improved and the CM
The effect of reducing the damage (damage) on the surface of the metal layer to be P is obtained.

However, when a buried wiring is formed by CMP using a conventional metal polishing slurry containing solid abrasive grains, (1) the surface central portion of the buried metal wiring is isotropically corroded. Generation of a dish-like phenomenon (hereinafter referred to as dishing), (2) generation of polishing scratches (scratch) derived from solid abrasive grains, and (3) removal of solid abrasive grains remaining on the substrate surface after polishing. The cleaning process is complicated, and (4) the cost of the solid abrasive grains itself and the cost increase due to the waste liquid treatment arise.

In order to suppress the corrosion of the copper alloy during dishing and polishing and to form a highly reliable LSI wiring, a metal oxide dissolving agent composed of aminoacetic acid or amide sulfuric acid such as glycine and BTA (benzotriazole) are used. A method using a contained metal polishing liquid has been proposed. This technique is described in, for example, Japanese Patent Application Laid-Open No. 8-83780.

In the formation of a metal buried such as the formation of a damascene wiring of copper or a copper alloy or the formation of a plug wiring of tungsten or the like, when the polishing rate of a silicon dioxide film which is an interlayer insulating film formed in a portion other than the buried portion is high, Thinning occurs in which the thickness of the wiring is thinned together with the interlayer insulating film.
As a result, variations in resistance occur due to an increase in wiring resistance, pattern density, and the like. Therefore, a characteristic in which the polishing rate of the silicon dioxide film is sufficiently low relative to the metal film to be polished is required. Therefore, a method has been proposed in which the polishing rate of the polishing liquid is made higher than pKa-0.5 by suppressing the polishing rate of silicon dioxide by anions generated by dissociation of the acid. This technique is described in, for example, Japanese Patent No. 2819196.

On the other hand, a tantalum, a tantalum alloy, a tantalum nitride, another tantalum compound, or the like is formed as a barrier layer for preventing copper from diffusing into an interlayer insulating film in a lower layer of a wiring such as copper or a copper alloy. . Therefore, it is necessary to remove the exposed barrier layer by CMP except for the wiring portion where copper or copper alloy is embedded. However, since these barrier layer conductor films have higher hardness than copper or copper alloy, a combination of polishing materials for copper or copper alloy often cannot provide a sufficient CMP rate. Therefore, a two-step polishing method including a first step of polishing copper or a copper alloy and a second step of polishing the barrier layer conductor has been studied.

In a two-step polishing method comprising a first step of polishing copper or a copper alloy and a second step of polishing a barrier layer,
Because the hardness and chemical properties of the films to be polished are different, compositions having considerably different properties are being studied for the composition of the polishing liquid such as pH, abrasive grains and additives. Tantalum, tantalum alloy, tantalum nitride, and other tantalum compounds used as barrier layers are chemically stable and difficult to etch, and the only compound that can be etched at room temperature is a fluorine-containing compound. However, it is said that a high CMP rate of tantalum or tantalum nitride cannot be obtained only with a fluorine-containing compound, and a barrier layer polishing technique using a polishing liquid containing both abrasive grains and a fluorine-containing compound has been developed. . This technique is disclosed, for example, in Japanese Patent Application Laid-Open No. 10-67986.

[0013]

However, when a wiring and a plug are formed by CMP using a conventional polishing agent containing a solid abrasive for polishing a metal film as a main component, at least the following (1) to (6) ). (1) A phenomenon in which the central portion of the surface of the metal wiring embedded in the groove formed in the insulating film is polished excessively more than the peripheral portion thereof (dishing), and a phenomenon in which the surface of the insulating film around the wiring portion is polished ( Hereafter referred to as erosion),
(2) Generation of polishing scratches (scratch) by solid abrasive grains for polishing; (3) Increase in cleaning process due to many abrasive grains remaining on the wafer surface after CMP; (4) Manufacturing cost of abrasive grains , CM originating from clogging of abrasive grains on pads
High cost of consumables used for P. (5) Requires abrasive sedimentation prevention mechanism in abrasive supply system, dust reduction mechanism in clean room due to use of abrasive, waste liquid treatment, etc., (6) Recycling is required. It is not easy and costly. All of the above problems are caused by performing CMP using an abrasive containing a high concentration of abrasive grains. However, tantalum, tantalum alloys, tantalum nitride, and other tantalum compounds used as barrier layers are chemically stable and difficult to etch, and because of their high hardness, mechanical polishing is not as easy as copper or copper alloys. It is said that it is necessary to increase the hardness of the grains. Therefore, when the hardness of the abrasive grains is increased, polishing flaws are generated in copper or copper alloy and cause poor electrical characteristics, and when the particle concentration of the abrasive grains is increased, the polishing rate of the silicon dioxide film is reduced. And erosion occurs. Furthermore, since the fluorine-containing compound etches not only the barrier layer but also the silicon dioxide film, there is a problem that the erosion is increased in the method of polishing the barrier layer using the polishing liquid containing both the abrasive grains and the fluorine-containing compound. there were. The present invention expresses a high CMP rate of tantalum or tantalum nitride,
An object of the present invention is to provide a metal polishing liquid and a polishing method using the same, which can reduce a dishing amount and an erosion amount and can form a highly reliable buried pattern of a metal film. Further, the present invention can continuously and efficiently polishing copper or copper alloy and the barrier layer conductor,
An object of the present invention is to provide a method for polishing a substrate, which enables formation of a highly reliable buried pattern of a metal film.

[0014]

SUMMARY OF THE INVENTION The present invention provides a metal polishing slurry containing (1) a fluorine-containing compound and water. (2)
2. The metal polishing slurry according to claim 1, wherein the fluorine-containing compound is at least one selected from an organic fluorine compound, an inorganic fluorine compound, and an ammonium salt thereof, and (3) further comprising a metal oxidizing agent. (1) or (2), the metal polishing liquid according to any one of (1) to (3), further comprising (4) a metal oxide dissolving agent, and (5) protection against the metal surface. The metal polishing slurry according to any one of the above (1) to (4), further containing a film-forming agent, and (6) the metal according to any one of the above (1) to (5), further containing a water-soluble polymer. Polishing slurry, and (7) the metal oxidizing agent is at least one selected from the group consisting of hydrogen peroxide, nitric acid, potassium periodate, hypochlorous acid, and ozone water. Polishing liquid for metals described in (8), (8) gold oxide The metal polishing slurry according to any one of the above (4) to (7), wherein the dissolving agent is at least one selected from organic acids, and (9) the protective film forming agent is a nitrogen-containing compound and a salt thereof, a mercaptan (10) The metal polishing slurry according to any one of the above (5) to (8), which is at least one selected from the group consisting of glucose, and cellulose.
Any of the above (6) to (9), wherein the water-soluble polymer is at least one selected from the group consisting of polyacrylic acid or a salt thereof, polymethacrylic acid or a salt thereof, polyacrylamide, polyvinyl alcohol, and polyvinylpyrrolidone. (11) The metal according to any of (6) to (10), wherein (11) the water-soluble polymer has a weight average molecular weight of 500 or more and at least two or more different weight average molecular weights. Polishing liquid for (12)
(13) a metal polishing liquid containing 1% by weight or less of abrasive grains in the metal polishing liquid according to any of (1) to (11) above;
The metal polishing solution according to any one of the above (1) to (12), wherein the metal film to be polished is a barrier layer of copper and a copper alloy, (14) the barrier layer is made of tantalum, tantalum nitride, or a tantalum alloy The polishing slurry for metals according to the above (13), which is another tantalum alloy. Further, the present invention provides (15) a method of forming a substrate having a film to be polished on a polishing cloth while supplying the metal polishing liquid according to any one of the above (1) to (14) onto the polishing cloth of the polishing platen. This is a polishing method for polishing a film to be polished by relatively moving a polishing platen and a substrate in a pressed state.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The metal polishing slurry of the present invention contains a fluorine-containing compound and water. As the fluorine-containing compound used in the present invention, at least one selected from an organic fluorine compound or an inorganic fluorine compound and an ammonium salt thereof is preferable, and F-butyric acid, F-hexanoic acid,
At least one selected from octanoic acid, F-decanoic acid, F-dodecanoic acid, trifluoroacrylic acid, pentafluorobenzoic acid and ammonium salts thereof is preferred. The metal polishing slurry of the present invention can further contain a metal oxidizing agent. The oxidizing agent used in the present invention is preferably at least one selected from hydrogen peroxide, nitric acid, potassium periodate, hypochlorous acid and ozone water. The metal polishing slurry of the present invention can further contain a protective film forming agent for the metal surface. The protective film forming agent used in the present invention forms a protective film on a metal surface, and the protective film forming agent is at least one selected from nitrogen-containing compounds and salts thereof, mercaptan, glucose and cellulose. Species are preferred. The metal polishing slurry of the present invention may further contain a water-soluble polymer. As the water-soluble polymer used in the present invention, polysaccharides,
Polycarboxylic acids, polycarboxylic esters and salts thereof,
And at least one selected from vinyl polymers. The metal-polishing liquid in the present invention may further contain at least one or more kinds of metal oxide dissolving agents such as organic acids and abrasive grains as necessary. At least a part of the metal film by the step of polishing a metal film composed of a laminated film including at least one metal layer selected from copper, a copper alloy and an oxide of copper or a copper alloy using the metal polishing slurry of the present invention. Can be removed. In the polishing method of the present invention, the polishing plate and the substrate are relatively moved while the substrate having the film to be polished is pressed against the polishing cloth while the metal polishing liquid is supplied onto the polishing cloth of the polishing table. Thus, the film to be polished can be polished.

In the present invention, it is possible to provide a metal polishing liquid which exhibits high polishing of tantalum and tantalum nitride by using a fluorine-containing compound, and a method of polishing a substrate using the same. When the pH of the metal polishing slurry in the present invention is higher than 9, the CMP rate of the silicon dioxide film increases. The pH can be adjusted by the amount of acid added.
It can also be adjusted by adding an alkali component such as ammonia, sodium hydroxide, tetramethylammonium hydride and the like. If necessary, an oxidizing agent for a metal, a water-soluble polymer, and abrasive grains may be added.

In the present invention, a metal film containing copper or a copper alloy (eg, copper / chromium) is formed and filled on a substrate having a concave portion on the surface. When the substrate is subjected to CMP using the polishing slurry for metal according to the present invention, the metal film at the convex portion of the substrate is selectively CM.
After P, the metal film is left in the concave portion, and a desired conductor pattern is obtained. The polishing slurry for metals of the present invention may be substantially free of solid abrasive grains, and polishing scratches are dramatically reduced because CMP proceeds by friction with a polishing pad that is much more mechanically soft than solid abrasive grains. Is done. The metal polishing slurry of the present invention contains a fluorine-containing compound and water as essential components. Metal oxidizing agent, metal oxide dissolving agent, protective film forming agent,
It may include a water-soluble polymer. Solid abrasive particles need not be substantially contained, but may be used.

The metal oxidizing agent of the metal polishing slurry of the present invention, when containing a water-soluble polymer, has a concentration of 0.0
It is preferably from 1 to 1.5% by weight. The water-soluble polymer is
In order to adsorb on tantalum, tantalum alloy, tantalum nitride, other tantalum compounds or their oxide films,
The oxidant concentration range in which a high CMP rate can be obtained becomes smaller. In addition, since the water-soluble polymer is easily adsorbed on the surface of a nitride compound film such as tantalum nitride or titanium nitride, the CMP rate of the nitride compound film such as tantalum nitride or titanium nitride decreases. On the other hand, the water-soluble polymer has a metal surface protective film forming effect, and improves flattening characteristics such as dishing and erosion.

As the fluorine-containing compound, those selected from the following groups are suitable. Trifluoroacetic acid, trifluoropropionic acid, F-butyric acid, F-hexanoic acid, F-octanoic acid, F-decanoic acid, F-dodecanoic acid, trifluoroacrylic acid, pentafluorobenzoic acid, pentafluorophenol, trifluoroacetic acid Sodium, potassium trifluoroacetate, ammonium trifluoroacetate, sodium trifluoropropionate, potassium trifluoropropionate, ammonium trifluoropropionate, sodium F-butyrate, potassium F-butyrate, ammonium F-butyrate, sodium F-hexanoate , Potassium F-hexanoate, ammonium F-hexanoate, sodium F-octanoate, potassium F-octanoate, ammonium F-octanoate, sodium F-decanoate, F-
Potassium decanoate, ammonium F-decanoate, sodium F-dodecanoate, potassium F-dodecanoate, ammonium F-dodecanoate, sodium trifluoroacrylate, potassium trifluoroacrylate, ammonium trifluoroacrylate, pentafluorobenzoic acid Organic fluorine compounds such as sodium, potassium pentafluorobenzoate, ammonium pentafluorobenzoate, sodium pentafluorophenol, potassium pentafluorophenol, and pentafluorophenol ammonium and their ammonium salts; hydrofluoric acid, fluorophosphoric acid, hexafluorosilicic acid , Tetrafluoroboric acid, hexafluorotitanic acid, sodium fluoride, potassium fluoride, ammonium fluoride, ammonium hydrogen difluoride, hydrogen difluoride Umm, sodium fluoro phosphate,
Potassium fluorophosphate, ammonium fluorophosphate, sodium hexafluorosilicate, potassium hexafluorosilicate, ammonium hexafluorosilicate, sodium tetrafluoroborate, potassium tetrafluoroborate, ammonium tetrafluoroborate, sodium hexafluorotitanate, potassium hexafluorotitanate, Inorganic fluorine compounds such as ammonium hexafluorotitanate and ammonium salts thereof can be mentioned. However, when the substrate to be applied is a silicon substrate for a semiconductor integrated circuit or the like, an acid or an ammonium salt thereof is preferable because contamination by an alkali metal, an alkaline earth metal, a halide or the like is not desirable. This is not the case when the substrate is a glass substrate or the like. Among them, F-butyric acid, F-hexanoic acid, F
-Octanoic acid, F-decanoic acid, F-dodecanoic acid, trifluoroacrylic acid and pentafluorobenzoic acid are more preferred.

The metal polishing slurry of the present invention may contain a metal oxidizing agent. Metal oxidants include hydrogen peroxide (H ₂ O ₂ ), nitric acid, potassium periodate, hypochlorous acid,
Ozone water and the like can be mentioned, and among them, hydrogen peroxide is particularly preferable. When the substrate is a silicon substrate including an element for an integrated circuit, contamination by an alkali metal, an alkaline earth metal, a halide, or the like is not desirable, and an oxidizing agent containing no nonvolatile component is desirable. However, hydrogen peroxide is most suitable because the composition of ozone water changes drastically with time. However,
When the substrate to be applied is a glass substrate or the like containing no semiconductor element, an oxidizing agent containing a nonvolatile component may be used.

The metal polishing slurry of the present invention may contain a metal oxide dissolving agent. The metal oxide dissolving agent is desirably water-soluble. Aqueous solutions of those selected from the following groups are suitable. Formic acid, acetic acid, propionic acid, butyric acid, valeric acid, 2
-Methylbutyric acid, n-hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid, 4-methylpentanoic acid, n-heptanoic acid, 2-methylhexanoic acid, n-octanoic acid, 2-
Ethylhexanoic acid, benzoic acid, glycolic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, phthalic acid, malic acid, tartaric acid, citric acid, etc. And salts thereof such as ammonium salts of organic acids, sulfuric acid, nitric acid, ammonia, ammonium salts such as ammonium persulfate, ammonium nitrate, ammonium chloride, chromic acid and the like, and mixtures thereof. Of these, formic acid,
Malonic acid, malic acid, tartaric acid, and citric acid are suitable for a laminated film including at least one metal layer selected from copper, a copper alloy, and an oxide of copper or a copper alloy. These are preferred in that they can be easily balanced with the protective film forming agent. In particular,
Practical CMP for malic acid, tartaric acid and citric acid
This is preferable in that the etching rate can be effectively suppressed while maintaining the rate.

The metal polishing slurry of the present invention may contain a protective film forming agent. The protective film forming agent is preferably selected from the following group. Ammonia; dimethylamine,
Alkylamines such as trimethylamine, triethylamine and propylenediamine; and amines such as ethylenediaminetetraacetic acid (EDTA), sodium diethyldithiocarbamate and chitosan; glycine, L-alanine,
β-alanine, L-2-aminobutyric acid, L-norvaline,
L-valine, L-leucine, L-norleucine, L-isoleucine, L-alloisoleucine, L-phenylalanine, L-proline, sarcosine, L-ornithine, L
-Lysine, taurine, L-serine, L-threonine, L
-Allothreonine, L-homoserine, L-tyrosine,
3,5-diiodo-L-tyrosine, β- (3,4-dihydroxyphenyl) -L-alanine, L-thyroxine,
4-hydroxy-L-proline, L-cystine, L-
Methionine, L-ethionine, L-lanthionine, L-
Cystathionine, L-cystine, L-cystinic acid, L
-Aspartic acid, L-glutamic acid, S- (carboxymethyl) -L-cysteine, 4-aminobutyric acid, L-asparagine, L-glutamine, azaserine, L-arginine, L-canavanine, L-citrulline, δ-hydroxy- L-lysine, creatine, L-kynurenine, L-histidine, 1-methyl-L-histidine, 3-methyl-
Amino acids such as L-histidine, ergothioneine, L-tryptophan, actinomycin C1, apamin, angiotensin I, angiotensin II and antipain; dithizone, cuproin (2,2′-biquinoline), neocuproin (2,9-dimethyl-1, 10-
Imines such as phenanthroline), bathocuproin (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline) and cuperazone (biscyclohexanone oxalylhydrazone); benzimidazole-2-
Thiol, 2- [2- (benzothiazolyl)] thiopropionic acid, 2- [2- (benzothiazolyl) thiobutyric acid, 2-mercaptobenzothiazole, 1,2,3-triazole, 1,2,4-triazole, 3- Amino-
1H-1,2,4-triazole, benzotriazole, 1-hydroxybenzotriazole, 1-dihydroxypropylbenzotriazole, 2,3-dicarboxypropylbenzotriazole, 4-hydroxybenzotriazole, 4-carboxyl-1H-benzotriazole , 4-methoxycarbonyl-1H-benzotriazole, 4-butoxycarbonyl-1H-benzotriazole, 4-octyloxycarbonyl-1H-benzotriazole, 5-hexylbenzotriazole, N-
(1,2,3-benzotriazolyl-1-methyl) -N
-(1,2,4-triazolyl-1-methyl) -2-ethylhexylamine, tolyltriazole, naphthotriazole, bis [(1-benzotriazolyl) methyl]
Azoles such as phosphonic acid; mercaptans such as nonylmercaptan, dodecylmercaptan, triazinethiol, triazinedithiol, and triazinetrithiol; and saccharides such as glucose and cellulose. Among them, chitosan, ethylenediaminetetraacetic acid, L-tryptophan, cuperazone, triazinedithiol,
Benzotriazole, 4-hydroxybenzotriazole, 4-carboxylbenzotriazole butyl ester, tolyltriazole, naphthotriazole have high C
It is preferable to achieve both the MP rate and the low etching rate.

The metal polishing slurry of the present invention may contain a water-soluble polymer. As the water-soluble polymer, those selected from the following group are preferable. Polysaccharides such as alginic acid, pectic acid, carboxymethyl cellulose, agar, cardran and pullulan; amino acid salts such as glycine ammonium salt and glycine sodium salt; polyaspartic acid, polyglutamic acid, polylysine, polymalic acid, polymethacrylic acid Ammonium polymethacrylate, sodium polymethacrylate, polyamic acid, polymaleic acid, polyitaconic acid, polyfumaric acid, poly (p-styrenecarboxylic acid), polyacrylic acid, ammonium polyacrylate, sodium polyacrylate Polycarboxylic acids such as polyacrylamide, aminopolyacrylamide, polyamic acid, polyamic acid ammonium salt, polyamic acid sodium salt and polyglyoxylic acid; and salts thereof; polyvinyl alcohol, polyvinylpyro Vinyl polymers such as pyrrolidone and polyacrolein, and the like. However, when the substrate to be applied is a silicon substrate for a semiconductor integrated circuit or the like, an acid or an ammonium salt thereof is preferable because contamination by an alkali metal, an alkaline earth metal, a halide or the like is not desirable. This is not the case when the substrate is a glass substrate or the like. Among them, pectic acid, agar, polymalic acid, polymethacrylic acid, polyacrylic acid, ammonium polyacrylate, ammonium polymethacrylate, polyacrylamide, polyvinyl alcohol and polyvinylpyrrolidone, their esters, and their ammonium salts are preferred.

Abrasive grains may be added to the metal polishing liquid of the present invention. As abrasive grains, silica, alumina, ceria,
Any one of inorganic abrasive grains such as titania, zirconia, germania, and silicon carbide, and organic abrasive grains such as polystyrene, polyacryl, and polyvinyl chloride may be used. However, the dispersion stability in the polishing solution is good, and the polishing scratches generated by CMP. Colloidal silica or colloidal alumina having a small number of (scratch) occurrences and an average particle size of 100 nm or less is preferred.
The average particle size is more preferably 20 nm or less at which the polishing rate of the barrier layer becomes higher and the polishing rate of silicon dioxide becomes lower. A method of producing colloidal silica by hydrolysis of silicon alkoxide or ion exchange of sodium silicate is known, and a method of producing colloidal alumina by hydrolysis of aluminum nitrate is known.

The metal film to which the present invention is applied is a laminated film containing at least one selected from copper, a copper alloy, and an oxide of copper or a copper alloy (hereinafter referred to as a copper alloy).

The compounding amount of the fluorine-containing compound component in the present invention is 0.00
001 to 0.005 mol, preferably 0.1 to 0.005 mol.
It is more preferably from 0.0005 to 0.0025 mol, particularly preferably from 0.0005 to 0.0015 mol. If the amount exceeds 0.005 mol, it tends to be difficult to suppress the CMP rate of the insulating film.

In the present invention, a metal oxidizing agent can be added. The compounding amount of the oxidizing agent component is preferably 0.003 to 0.7 mol, more preferably 0.03 to 0.5 mol, and more preferably 0.2 to 0.5 mol based on 100 g of the total weight of the metal polishing liquid. It is particularly preferable that the content be 0.3 mol. If the amount is less than 0.003 mol, the metal is not sufficiently oxidized and the CMP rate is low. If the amount exceeds 0.7 mol, the polished surface tends to be rough.

In the present invention, a metal oxide dissolving agent may be added. The compounding amount of the metal oxide dissolving agent component in the present invention is 0 to 0.0 with respect to 100 g of the total weight of the polishing slurry for metal.
It is preferable that the content be 0.05 mol, and 0.00005 to
0.0025 mol is more preferable, and 0.025 mol
It is particularly preferred that the amount be from 005 to 0.0015 mol. When the amount exceeds 0.005 mol, it tends to be difficult to suppress the etching.

In the present invention, a protective film forming agent may be added. The compounding amount of the protective film forming agent is preferably 0.0001 to 0.05 mol, more preferably 0.0003 to 0.005 mol, and more preferably 0.0005 to 0.005 mol based on 100 g of the total weight of the metal polishing liquid. 0.0035m
ol is particularly preferred. This compounding amount is 0.00
If it is less than 01 mol, it tends to be difficult to suppress etching, and if it exceeds 0.05 mol, the CMP rate tends to be low.

In the present invention, a water-soluble polymer can be added. The compounding amount of the water-soluble polymer is preferably 0.001 to 0.3% by weight, more preferably 0.003 to 0.1% by weight, based on 100 g of the total weight of the metal polishing liquid. It is particularly preferred that the content be 0.01 to 0.08% by weight. If the amount is less than 0.001% by weight, the effect of using the protective film-forming agent in suppressing etching tends not to be exhibited, and if it exceeds 0.3% by weight, the CMP rate tends to decrease. The weight average molecular weight of the water-soluble polymer is preferably 500 or more, more preferably 1500 or more, and particularly preferably 5000 or more. The upper limit of the weight average molecular weight is not particularly limited, but is 5,000,000 or less from the viewpoint of solubility. If the weight average molecular weight is less than 500, a high CMP rate tends not to be exhibited. In the present invention, it is preferable to use at least two kinds of water-soluble polymers having a weight average molecular weight of 500 or more and different weight average molecular weights. The same type of water-soluble polymer or a different type of water-soluble polymer may be used.

In the present invention, abrasive grains can be added.
The compounding amount of the abrasive grains is preferably 0.01 to 10% by weight based on 100 g of the total weight of the metal polishing liquid,
More preferably, the content is 5 to 5% by weight. 0.05-1
It is particularly preferable to set the weight%. If the amount is 0.0
If it is less than 1% by weight, there is no effect of containing abrasive grains, and if it exceeds 10% by weight, the polishing rate by CMP saturates, and no increase is observed even if more than 10% by weight is added.

In the polishing method of the present invention, the polishing platen and the substrate are relatively moved while the substrate having the film to be polished is pressed against the polishing cloth while the metal polishing liquid is supplied onto the polishing cloth of the polishing platen. This is a polishing method for polishing a film to be polished by moving it in a horizontal direction. As an apparatus for polishing, a general polishing apparatus having a holder for holding a semiconductor substrate and a platen on which a polishing cloth (pad) is attached (a motor or the like capable of changing the number of rotations is attached) can be used. As the polishing cloth, general nonwoven fabric, foamed polyurethane, porous fluororesin and the like can be used, and there is no particular limitation. The polishing conditions are not limited, but the rotation speed of the platen is preferably low, such as 200 rpm or less so that the substrate does not pop out. The pressing pressure of the semiconductor substrate having the film to be polished against the polishing cloth is 9.8 to 98 KPa (100 KPa).
To 1000 gf / cm ² )
In order to satisfy the uniformity of the P speed within the wafer surface and the flatness of the pattern, it is necessary to use 9.8 to 49 KPa (100 to 500 g).
f / cm ² ). During polishing, a metal polishing liquid is continuously supplied to the polishing cloth by a pump or the like. The supply amount is not limited, but it is preferable that the surface of the polishing pad is always covered with the polishing liquid. After the polishing is completed, the semiconductor substrate is preferably washed well in running water, and then dried by spin-drying or the like to remove water droplets attached to the semiconductor substrate.

[0033]

The present invention will be described below in detail with reference to examples. The present invention is not limited by these examples. (Preparation of polishing liquid for metal) Fluorine-containing compound or acid
A solution prepared by adding 100 parts by weight of water to 4 parts by weight and dissolving it was used as a metal polishing liquid. When adding hydrogen peroxide solution, a part of the water is replaced with hydrogen peroxide solution (special grade, 30% by weight aqueous solution).
And the desired concentration was obtained. When benzotriazole (BTA) is added, 0.2 parts by weight (solid content) of BTA is added in the form of a 1% by weight aqueous solution of BTA, and when a water-soluble polymer is added, 0.05 parts by weight.
1.0 parts by weight (solid content)
Parts by weight were added. Even when BTA, a water-soluble polymer and abrasive grains were added, the weight part of water added first was adjusted so that the total weight of the metal polishing liquid was 103.4 parts by weight. The pH of each polishing liquid was finely adjusted with an acid or ammonia so that the pH was within the range of 3.0 ± 0.05.

In Examples 1-4 and Comparative Examples 1-2, Table 1
Using the above-mentioned metal polishing slurry having the composition described in 1 above, CMP was performed under the following polishing conditions. (Polishing conditions) Substrate: Silicon substrate on which a 200 nm thick tantalum film was formed. Silicon substrate on which a 100 nm thick tantalum nitride film was formed. Silicon substrate on which a 1 μm thick silicon dioxide film was formed. 1 μm thick copper film was formed. Silicon substrate Polishing pad: (IC1000 (Rodel)) Foamed polyurethane resin having closed cells Polishing pressure: 24.5 KPa (250 gf / cm ² ) Relative speed between substrate and polishing platen: 18 m / min (polished product) Evaluation of CMP) CMP speed: The difference in thickness of the copper film before and after the CMP was calculated from the electrical resistance value. Etching rate: stirring metal polishing liquid (room temperature, 25
The temperature difference between the copper layer before and after immersion in 100 ° C. and stirring at 100 rpm was calculated from the electrical resistance value. Dishing amount: A groove having a depth of 0.5 μm is formed in silicon dioxide, a tantalum nitride film having a thickness of 50 nm is formed as a barrier layer by a known sputtering method, and a copper film is similarly formed by a sputtering method. Polishing is performed using the silicon substrate embedded by the heat treatment of Step 2, and the width of the wiring metal part is 100 μm and the width of the insulating film part is 100 μm by the stylus type step meter.
Was determined from the surface shape of the stripe-shaped pattern portions in which the wiring metal portions were reduced with respect to the insulating film portion.
As the first-stage polishing liquid for copper, polishing was performed using a polishing liquid for copper or a copper alloy having a sufficiently high polishing rate ratio of copper to tantalum nitride. After the first-stage polishing, the dishing amount measured with the barrier layer exposed on the insulating film portion is 50.
A substrate sample was prepared so as to have a thickness of 2 nm, and polished in two steps until there was no barrier layer in the insulating film portion. Thinning amount: The surface shape of the 2.5-mm-wide stripe-shaped pattern portion formed by alternately arranging the wiring metal portion width 4.5 μm and the insulating film portion width 0.5 μm formed on the dishing amount evaluation substrate is a stylus. The amount of film reduction in the insulating film portion near the center of the pattern with respect to the insulating film field portion around the stripe-shaped pattern was determined by using a step gauge. After the first-stage polishing, a substrate sample was prepared so that the thinning amount measured in a state where the barrier layer was exposed on the insulating film portion was 20 nm.
Step polishing. Table 1 shows polishing rates and polishing rate ratios by CMP in Examples 1 to 4 and Comparative Examples 1 and 2. Table 2 shows the dishing amount and the thinning amount.

[0035]

[Table 1]

[0036]

[Table 2]

When oxalic acid which is not a fluorine-containing compound is used as shown in Comparative Example 1, copper CM
The P rate (polishing rate) increases, and the polishing rate ratio of barrier layer / copper decreases. Further, when γ-alumina was used as abrasive grains without using hydrogen peroxide as an oxidizing agent as shown in Comparative Example 2, the CMP rate (polishing rate) of copper did not change compared to Examples 2 and 4. Although the polishing rate ratio of the layer / copper increases, the amount of dishing increases, and the amount of thinning increases because the polishing rate of the insulating film SiO ₂ is high. In contrast,
As shown in Examples 1 to 4, when a fluorine-containing compound was used, the CM of the barrier layer was increased despite the absence of abrasive grains.
The P speed can be increased, and the polishing rate and thinning amount of the insulating film can exhibit small polishing characteristics. In addition, since the CMP rate of copper can be reduced by increasing the amount of BTA, the amount of dishing can be reduced and high flatness can be achieved.

[0038]

The metal polishing slurry of the present invention can exhibit a high CMP rate by forming a fluorine-containing compound and can form a highly reliable embedded pattern.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/306 H01L 21/306 M // H01L 21/3205 21/88 K (72) Inventor Hiroki Terasaki Ibaraki 48 Wadai, Tsukuba, Japan Pref. Within Hitachi Chemical Co., Ltd. (72) Inventor Yasushi Kurata 48 Wadai, Tsukuba, Ibaraki Pref. F-term in Hitachi Chemical Co., Ltd. Research Laboratory (reference)

Claims (15)

[Claims] 1. A metal polishing slurry containing a fluorine-containing compound and water. 2. The method according to claim 1, wherein the fluorine-containing compound is an organic fluorine compound,
The metal polishing slurry according to claim 1, wherein the metal polishing slurry is at least one selected from inorganic fluorine compounds and ammonium salts thereof. 3. The metal polishing slurry according to claim 1, further comprising a metal oxidizing agent. 4. The metal polishing slurry according to claim 1, further comprising a metal oxide dissolving agent. 5. The metal polishing slurry according to claim 1, further comprising a protective film forming agent for the metal surface. 6. The metal polishing slurry according to claim 1, further comprising a water-soluble polymer. 7. The method according to claim 3, wherein the metal oxidizing agent is at least one selected from hydrogen peroxide, nitric acid, potassium periodate, hypochlorous acid and ozone water. Polishing liquid for metal. 8. The metal polishing slurry according to claim 4, wherein the metal oxide dissolving agent is at least one selected from organic acids. 9. The metal polishing slurry according to claim 5, wherein the protective film forming agent is at least one selected from a nitrogen-containing compound and a salt thereof, mercaptan, glucose and cellulose. 10. The water-soluble polymer is at least one selected from the group consisting of polyacrylic acid or a salt thereof, polymethacrylic acid or a salt thereof, polyacrylamide, polyvinyl alcohol, and polyvinylpyrrolidone. Item 10. The metal polishing slurry according to any one of Items 9 to 10. 11. The water-soluble polymer having a weight average molecular weight of 50
The metal polishing slurry according to any one of claims 6 to 10, wherein at least two or more kinds having different weight average molecular weights of 0 or more are used. 12. A metal polishing liquid according to any one of claims 1 to 11, wherein the metal polishing liquid contains 1% by weight or less of abrasive grains. 13. The metal-polishing liquid according to claim 1, wherein the metal film to be polished is a barrier layer of copper and a copper alloy. 14. The metal polishing slurry according to claim 13, wherein the barrier layer is tantalum, tantalum nitride, a tantalum alloy, or another tantalum alloy. 15. A polishing method in which a substrate having a film to be polished is pressed against a polishing cloth while the polishing liquid for a metal according to any one of claims 1 to 14 is supplied onto the polishing cloth of the polishing platen. A polishing method for polishing a film to be polished by relatively moving a surface plate and a substrate.