JP2003068683A - Polishing liquid for metal and method for polishing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing liquid capable of rapidly polishing and high planarization, without bringing about interface release of a low permittivity insulating material layer, in polishing a metal suitable for a multilayer wiring manufacturing step using the low permittivity insulating film and a copper wiring, and to provide a method for polishing. SOLUTION: The polishing liquid for the metal comprises a metal oxidizer, a metal oxide dissolving agent, anticorrosives, water soluble polymer, and metal laminated film interface release inhibitor. The method for polishing comprises the steps of supplying the polishing liquid for the metal to a polishing cloth on a polishing platen, bringing the liquid into contact with a surface to be polished of a substrate 1 of a semiconductor chip having a metal laminated film formed to have a low permittivity material layer 2 and a copper layer 5, and relatively moving the surface to be polished and the polishing surface to polish the surface of the substrate 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal polishing liquid and a polishing method used for polishing a wiring forming process of a semiconductor device. In particular, the present invention relates to a metal polishing liquid suitable for a multilayer wiring manufacturing process using a low dielectric constant insulating film and copper wiring.

[0002]

2. Description of the Related Art In recent years, a new fine processing technique has been developed in accordance with higher integration and higher performance of semiconductor integrated circuits (hereinafter referred to as LSI). Chemical mechanical polishing (hereinafter referred to as CMP)
The method is one of them, and flattening of the interlayer insulating film, metal plug formation,
This is a technique often used in the formation of embedded wiring. This technique is disclosed in, for example, US Pat. No. 4,944,836. Further, recently, in order to improve the performance of LSI, it has been attempted to use a copper alloy as a wiring material. However, it is difficult to perform fine processing on the copper alloy by the dry etching method which is frequently used in the conventional formation of aluminum alloy wiring. Therefore, a so-called damascene method is mainly adopted in which a copper alloy thin film is deposited and buried on an insulating film in which a groove is formed in advance, and the copper alloy thin film other than the groove portion is removed by CMP to form a buried wiring. . This technique is disclosed in, for example, Japanese Patent Laid-Open No. 2-278822.

A general method of metal CMP such as copper alloy is
A polishing pad is attached to a circular polishing platen (platen), the surface of the polishing pad is dipped in a polishing liquid for metal, and the surface of the substrate on which the metal film is formed is pressed, and 20 kPa from the back surface thereof.
The polishing platen is rotated under a higher pressure (hereinafter referred to as polishing pressure), and the metal film on the convex portion is removed by mechanical friction between the polishing liquid and the convex portion of the metal film.

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. First, it is considered that the basic mechanism is to oxidize the surface of the metal film with an oxidizing agent and scrape off the oxidized layer with solid abrasive grains. The oxide layer on the metal surface of the recess does not come into contact with the polishing pad so much that the effect of shaving by the solid abrasive is not exerted, so that the metal layer of the projection is removed and the substrate surface is flattened as CMP progresses. Details of this are disclosed in Journal of Electrochemical Society, Vol. 138, No. 11 (published in 1991), pages 3460-3464.

It has been considered effective to add a metal oxide dissolving agent as a method for increasing the polishing rate by CMP. It can be interpreted that if the particles of the metal oxide scraped off by the solid abrasive grains are dissolved in the polishing liquid (hereinafter referred to as etching), the effect of scraping off by the solid abrasive grains increases. Although the polishing rate by CMP is improved by the addition of the metal oxide dissolving agent, on the other hand, when the oxide layer on the surface of the metal film in the recess is also etched (dissolved) to expose the metal film surface, the metal film surface is further oxidized by the oxidizing agent. When this is repeated, the etching of the metal film in the recess proceeds. For this reason, a phenomenon in which the central portion of the surface of the metal wiring embedded after polishing is depressed like a dish (hereinafter referred to as dishing) occurs and the flattening effect is impaired. To prevent this, a protective film forming agent is further added. The protective film forming agent forms a protective film on the oxide layer on the surface of the metal film and prevents the oxide layer from being dissolved in the polishing liquid. It is desirable that this protective film can be easily scraped off with solid abrasive grains and that the polishing rate by CMP is not reduced. A metal containing BTA as a protective film forming agent and a metal oxide dissolving agent composed of aminoacetic acid such as glycine or amidosulfuric acid in order to suppress corrosion during copper alloy dishing and polishing and to form a highly reliable LSI wiring. A method using a polishing liquid for polishing has been proposed. This technique is described in, for example, Japanese Patent Application Laid-Open No. 8-83780.

[0006]

In order to further improve the performance of LSI, it is effective to lower the dielectric constant of the insulating material along with the lower resistance of the wiring material. The application of low-dielectric-constant insulating materials is being considered along with the conversion. Generally, various materials have been studied as a low dielectric constant film that replaces the conventional silicon oxide insulating film (relative dielectric constant 4.1). However, carbon-doped silicon oxide and organic polymer materials having a benzene ring are considered to be effective. Has become. Attempts have also been made to reduce the dielectric constant by making these materials porous. However, since these low dielectric constant materials have low strength themselves and low adhesion to other type laminated film materials, when a conventional metal-polishing liquid is used and polishing is usually performed under the CMP conditions, the film is formed at the interface. There is a problem that peeling occurs and the product yield is significantly reduced. Therefore, even a substrate using a low dielectric constant material having low strength of the material itself and low adhesion to other materials can be polished without peeling as in the case of a conventional substrate using silicon oxide. A polishing liquid has been sought. The present invention provides a metal polishing liquid and a polishing method capable of preventing interfacial peeling of a low dielectric constant insulating film material layer.

[0007]

The present invention relates to the following. (1) A metal-polishing liquid containing a metal oxidizing agent, a metal oxide dissolving agent, an anticorrosive agent, a water-soluble polymer, and a metal laminated film interface peeling preventing agent. (2) Polishing rate at a polishing pressure of 7 kPa is 100 nm
/ Min or less and the polishing rate at a polishing pressure of 14 kPa is 400 nm / min or more, (1) The metal-polishing liquid. (3) A metal polishing solution containing a metal oxidizing agent, a metal oxide dissolving agent, an anticorrosive agent, a water-soluble polymer, and a metal laminate film interfacial peeling inhibitor is supplied to a polishing cloth on a polishing platen to form a metal laminate film. Contacting the surface to be polished of the substrate, which is a semiconductor chip formed with,
A polishing method characterized in that a substrate surface is polished by relatively moving a surface to be polished and a polishing cloth to reduce a stress acting on an interface of a metal laminated film and planarizing the surface with a polishing pressure of less than 20 kPa. (4) The polishing method according to (3), wherein the metal laminated film comprises a low dielectric constant material layer and a copper layer or a copper alloy layer.

When a metal laminated film having a low dielectric constant material layer and a copper layer or a copper alloy layer is polished by using the above CMP polishing liquid, a metal laminated film interface peeling preventive agent in the polishing liquid works. The stress applied to the interface of the low dielectric constant material layer can be relaxed. Further, it has been found that, by using this metal laminated film interface peeling preventive agent, as another effect, it is possible to achieve a practical polishing rate and high planarization efficiency even at a polishing pressure of less than 20 kPa. For example, polishing pressure 7kP
When a polishing liquid having a high polishing rate of 100 nm / min or less at a and a polishing rate of 400 nm / min or more at a polishing pressure of 14 kPa is used, polishing proceeds at a convex portion where the applied polishing pressure is high, and Since the polishing is suppressed in the concave portion having a low value, it is possible to perform the polishing while suppressing the dishing. Moreover, since the polishing pressure is as low as 14 kPa, the frictional force between the polishing film and the polishing cloth is also reduced. Therefore, in addition to the function of the interlaminar film interfacial peeling preventive agent, the polishing pressure reducing effect can remarkably reduce the stress applied to the interface of the low dielectric constant material layer, resulting in the interfacial peeling of the low dielectric constant insulating film material layer. Polishing can be done without any problems.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The metal-polishing liquid of the present invention contains a metal oxidizing agent, a metal oxide dissolving agent, an anticorrosive agent, a water-soluble polymer, and a metal laminated film interfacial peeling preventing agent.

Hydrogen peroxide (H2
O2), nitric acid, potassium periodate, hypochlorous acid, ozone water and the like can be mentioned, of which hydrogen peroxide is particularly preferable. When the substrate is a silicon substrate containing an integrated circuit element, contamination with alkali metals, alkaline earth metals, halides, etc. is not desirable, so an oxidizer containing no non-volatile component is desirable. However, since the composition of ozone water changes drastically with time, hydrogen peroxide is most suitable. However, when the substrate to be applied is a glass substrate or the like that does not include a semiconductor element, an oxidizing agent containing a non-volatile component may be used.

The metal oxide dissolving agent used in the present invention is preferably water-soluble. Aqueous solutions of those selected from the following group 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 of these organic acids such as ammonium salts, Sulfuric acid, nitric acid, ammonia, ammonium salts such as ammonium persulfate, ammonium nitrate, ammonium chloride and the like, chromic acid and the like or a mixture thereof and the like can be mentioned. Of these, formic acid, malonic acid, malic acid, tartaric acid and citric acid are preferable.

The anticorrosive agent is preferably selected from the following group. Benzotriazole, 1-hydroxybenzotriazole, 1-dihydroxypropylbenzotriazole, 2,3-dicarboxypropylbenzotriazole, 4-hydroxybenzotriazole, 4-carboxyl (-1H-) benzotriazole, 4-carboxyl (-1H- ) Benzotriazole methyl ester, 4-carboxyl (-1H-) benzotriazole butyl ester, 4-carboxyl (-1H-) benzotriazole octyl ester, 5-hexyl benzotriazole, [1,2,3-benzotriazolyl- 1-
Methyl] [1,2,4-triazolyl-1-methyl]
[2-ethylhexyl] amine, tolyltriazole,
Examples thereof include naphthotriazole and bis [(1-benzotriazolyl) methyl] phosphonic acid. Among them, benzotriazole, 4-hydroxybenzotriazole, 4-carboxyl (-1H-) benzotriazole butyl ester, tolyltriazole, and naphthotriazole are preferable for obtaining a low etching rate.

The water-soluble polymer is preferably selected from the following group. Polysaccharides such as alginic acid, pectic acid, carboxymethylcellulose, agar, curdlan and pullulan; amino acid salts such as glycine ammonium salt and glycine sodium salt; polyaspartic acid, polyglutamic acid, polylysine, polymalic acid, polymethacrylic acid, polymethacrylic acid Ammonium salt, polymethacrylic acid sodium salt, polyamic acid, polymaleic acid,
Polyitaconic acid, polyfumaric acid, poly (p-styrenecarboxylic acid), polyacrylic acid, polyacrylamide, aminopolyacrylamide, polyacrylic acid ammonium salt, polyacrylic acid sodium salt, polyamic acid, polyamic acid ammonium salt, polyamic acid sodium salt And polycarboxylic acids such as polyglyoxylic acid and salts thereof;
Examples thereof include polyvinyl alcohol, polyvinylpyrrolidone, and vinyl-based polymers such as polyacrolein. However, when the substrate to be applied is a silicon substrate for semiconductor integrated circuits or the like, contamination with alkali metals, alkaline earth metals, halides and the like is not desirable, and therefore acids or ammonium salts thereof are 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, polyacrylamide, polyvinyl alcohol and polyvinylpyrrolidone, their esters and their ammonium salts are preferred.

As the agent for preventing interfacial peeling of the metal laminated film, one selected from the following group is suitable. 1,2,3-triazole, 1,2,4-triazole, 3-amino-1
Aliphatic azoles such as H-1,2,4-triazole; 2
-Methylimidazole, 4-methylimidazole, 2-
Imidazoles such as ethylimidazole, 2- (isopropyl) imidazole, 2-propylimidazole, 2-butylimidazole; 2-thiohydantoin, 1- (o
-Tolyl) -bisguanide, 1H-1,2,3-triazolo [4,5-b] pyridine, 1,2,4-triazolo [1,5-a] pyrimidine, 3-methyl-5-pyrazole, 3, Other nitrogen-containing compounds such as 5-dimethylpyrazole and 1,3-diphenylguanidine; 2-mercaptobenzothiazole, 2- [2- (benzothiazolyl)]
Thiazoles such as thiobutyric acid, 2- [2- (benzothiazolyl)] thiopropionic acid, 4,5-dimethylthiazole and 2-aminothiazole; benzimidazole-2.
-Thiols such as thiol, triazinedithiol and triazinetrithiol; thioamides such as thioacetamide and thiobenzamide; thioureas such as ethylenethiourea and propylenethiourea; and the like. Among them, 1H
-1,2,3-triazolo [4,5-b] pyridine,
1,3-diphenylguanidine, 3,5-dimethylpyrazole, 4,5-dimethylthiazole and 2-aminothiazole are more preferable.

The compounding amount of the metal oxidizer is as follows.
With respect to the total amount of 100 g of the metal oxide dissolving agent, the anticorrosive agent, the water-soluble polymer, the metal laminated film interface peeling preventive agent and water,
It is preferably 003 mol to 0.7 mol,
It is more preferably 0.03 mol to 0.5 mol, and particularly preferably 0.2 mol to 0.3 mol. When the content is less than 0.003 mol, the oxidation of metal is insufficient and the polishing rate is low, and when it exceeds 0.7 mol, the polished surface tends to be rough.

The compounding amount of the metal oxide dissolving agent in the present invention is such that the total amount of the metal oxidizing agent, the metal oxide dissolving agent, the anticorrosive agent, the water-soluble polymer, the interfacial peeling preventive agent for the metal laminated film and the water is 10.
It is preferably 0 to 0.005 mol, more preferably 0.00005 mol to 0.0025 mol, and 0.0005 mol to 0.001 with respect to 0 g.
It is particularly preferable to set it to 5 mol. This blending amount is 0.
If it exceeds 005 mol, it tends to be difficult to suppress etching.

The amount of the anticorrosive compounded is 0.0001 with respect to 100 g of the total amount of the metal oxidizing agent, the metal oxide dissolving agent, the anticorrosive agent, the water-soluble polymer, the interfacial peeling inhibitor for the metal laminated film and the water.
It is preferably 0.00 to 0.00 mol
The amount is more preferably 03 mol to 0.005 mol, and particularly preferably 0.0005 mol to 0.0035 mol. If the amount is less than 0.0001 mol, it tends to be difficult to suppress etching,
If it exceeds 0.05 mol, the polishing rate tends to be low.

The amount of the water-soluble polymer blended depends on the metal oxidizer,
Metal oxide dissolving agent, anticorrosive agent, water-soluble polymer, metal laminated film interfacial peeling preventive agent, and 0.0 per 100 g of water
It is preferably from 01 to 0.3% by weight, more preferably from 0.003% by weight to 0.1% by weight, and more preferably 0.01.
It is particularly preferable to set the content by weight to 0.08% by weight. If the blending amount is less than 0.001% by weight, the effect of combined use with the anticorrosive agent may not be exhibited in suppressing etching.
If it exceeds 3% by weight, the polishing 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 specified, but is 5,000,000 or less from the viewpoint of solubility. When the weight average molecular weight is less than 500, a high polishing rate tends not to appear.
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 in weight average molecular weight. The same type of water-soluble polymer or different types of water-soluble polymer may be used.

The compounding amount of the interfacial peeling preventing agent for the metal laminated film is such that the metal oxidizing agent, the metal oxide dissolving agent, the anticorrosive agent, the water-soluble polymer,
Further, it is preferably 0.0001 mol to 0.05 mol, more preferably 0.0003 mol to 0.005 mol, and more preferably 0.0005 mol to 0.00 with respect to 100 g of the total amount of the metal laminated film interface peeling preventive agent and water.
It is particularly preferable to set it to 35 mol. If this amount is less than 0.0001 mol, the polishing rate at a polishing pressure of 20 kPa or less tends to decrease.
If it exceeds, the effect of preventing interfacial peeling tends to be lost.

Abrasive particles may be further added to the CMP polishing agent, if necessary. Examples of the abrasive grains include inorganic abrasive grains such as silica, alumina, ceria, titania, zirconia, germania and silicon carbide, and organic abrasive grains such as polystyrene, polyacryl and polyvinyl chloride.

In the present invention, a high melting point metal film of Ta, Ti, W or the like or a nitride film thereof, and subsequently a copper or copper alloy film is formed on a substrate on which a low dielectric constant insulating film having a concave portion is formed. Form and fill. This substrate is C with the above polishing liquid.
When the MP is performed, the metal film on the convex portion of the substrate is selectively CMP, and the metal film is left on the concave portion to obtain a desired conductor pattern.

The low dielectric constant material has low film strength and low interlayer adhesion. Therefore, in the CMP polishing of the substrate using the low dielectric constant material, the compressive stress and the shear stress applied to the low dielectric constant material film in order to prevent the interfacial separation of the low dielectric constant insulating film material layer can be reduced. It is necessary to make the polishing pressure as low as possible.

Regarding the polishing rate, the polishing pressure is 7 kPa.
Under the following conditions, it is 100 nm / min or less, and 7 to
Polishing rate rapidly increased to 400 nm in the range of 20 kPa
/ Min or more is preferable. When polishing an uneven metal surface using a polishing liquid whose polishing rate depends on the polishing pressure in this way, the polishing rate becomes higher at the convex portion where the polishing pressure becomes higher and at the concave portion where the polishing pressure becomes lower. As a result, the planarization is promoted and the dishing of the wiring can be suppressed.

As the substrate, for example, as shown in FIGS. 1A and 1B, a semiconductor substrate, that is, a semiconductor substrate at a stage where circuit elements and wiring patterns are formed, a semiconductor substrate at a stage where circuit elements are formed, etc. A substrate in which a low dielectric constant material layer 2, a silicon oxide layer 3, and a barrier metal layer 4 are sequentially formed on a semiconductor Si substrate 1 and finally a copper layer 5 is formed on the surface can be used. By polishing the copper layer 5 formed on such a semiconductor substrate with the above-mentioned polishing agent, unevenness on the surface of the copper layer 5 is eliminated, and a smooth surface is formed over the entire surface of the semiconductor substrate as shown in FIG. 1 (c). And Specifically, a metal polishing liquid containing a metal oxidizing agent, a metal oxide dissolving agent, an anticorrosive agent, a water-soluble polymer, and a metal laminated film interfacial peeling inhibitor is supplied to a polishing pad on a polishing platen, The surface of the substrate, which is the semiconductor chip on which the layer 5 is formed, is brought into contact with the surface of the substrate and the polishing pad is relatively moved to polish the surface of the substrate. By polishing the lower metal layer while eliminating the unevenness of the metal layer, only the embedded metal layer is left. At this time, if the polishing rate ratio with the barrier metal layer serving as a stopper is large, the polishing process margin becomes large. It is also necessary that the number of scratches generated during polishing be small. Here, as a polishing device, a general polishing device having a holder for holding a semiconductor substrate and a surface plate to which a polishing cloth (pad) is attached (a motor or the like whose rotation speed is changeable) is used is used. it can.

FIG. 2 is a schematic diagram showing an example of a CMP apparatus used in the present invention. A metal polishing liquid containing a metal oxidizing agent, a metal oxide dissolving agent, an anticorrosive agent, a water-soluble polymer, and a metal laminated film interfacial peeling inhibitor on a polishing pad 17 attached on a polishing platen 18. Is supplied, and the copper layer 14 formed on the substrate 13, which is a semiconductor chip, is attached to the wafer holder 11 as the surface to be polished, the copper layer 14 is brought into contact with the polishing pad, and the surface to be polished and the polishing pad are moved relative to each other. The wafer holder 11 and the polishing platen 18 are rotated to perform CMP, that is, polishing of the substrate.

As the polishing pad, general non-woven fabric, foamed polyurethane, porous fluororesin, etc. can be used without any particular limitation. Further, it is preferable that the polishing pad is grooved so that the polishing agent is accumulated. There are no restrictions on the polishing conditions, but the rotation speed of the surface plate is 12 to prevent the semiconductor from jumping out.
A low rotation speed of 0 rpm or less is preferable. The pressing pressure of the semiconductor substrate having the film to be polished against the polishing pad is preferably 10 to 50 kPa in order to satisfy the in-plane uniformity of the polishing rate on the wafer and the flatness of the pattern. During polishing, the polishing liquid is continuously supplied to the polishing pad by a pump or the like. Although the supply amount is not limited, it is preferable that the surface of the polishing pad is always covered with the polishing liquid.

Examples of the low dielectric constant insulating film include carbon-added silicon oxide formed by plasma CVD, hydrogenated or carbon-added silicon oxide formed by spin coating, polymers having a benzene ring, and the like. It is known that the hardness of these materials is one digit or more lower than that of silicon oxide formed by the plasma CVD method. Also, although these materials themselves have a lower dielectric constant than silicon oxide,
It is possible to further lower the relative dielectric constant by introducing fine pores into the film to reduce the apparent density.
On the other hand, it is known that the film hardness decreases with the introduction amount of pores, and the strength of the film decreases with the introduction amount of pores. The relative permittivity of the low-dielectric-constant insulating material is preferably as low as possible in terms of insulation characteristics. The relative dielectric constant is preferably 4 or less, more preferably 3 or less. Further, in order to improve the adhesion between the low dielectric constant insulating film and the metal layer, it is possible to insert a thin film of silicon oxide, silicon nitride or the like between the low dielectric constant layer and the metal layer.

[0029]

EXAMPLES The present invention will be described below with reference to examples. Example 1 (Production of Polishing Rate Evaluation Substrate) A silicon oxide film having a thickness of 200 nm was formed on an 8-inch silicon wafer by a plasma CVD method, and a tantalum film was formed as a barrier metal by a sputtering method to 50 nm.
Then, 100 nm of copper was formed as a seed layer of the plating film by a sputtering method and 800 nm of copper was formed by a plating method as a seed layer of the plating film, and a substrate for polishing rate evaluation having a two-layer film of tantalum and copper on the insulating film was produced. (Preparation of substrate for polishing property evaluation) SiLK (Dow Chemical) was spin-coated on an 8-inch silicon wafer.
Al film) is formed to a thickness of 400 nm, a silicon oxide film is formed to a thickness of 100 nm by a plasma CVD method, and a space portion is formed by a photolithography method having a recessed portion having a width of 100 μm and a groove depth of 500 nm and a protrusion having a width of 100 μm. The dishing evaluation parts formed alternately were formed. Next, a tantalum film of 50 n is formed as a barrier metal by the sputtering method.
Then, as a seed layer of the plating film, copper is formed to a thickness of 100 nm by a sputtering method, and copper is formed to a thickness of 800 nm by a plating method.
A substrate for polishing property evaluation having a two-layer film of tantalum and copper on an insulating film having irregularities was prepared. (Preparation of polishing liquid) To 70 parts by weight of water was added to 0.1 part by weight of malonic acid (special grade reagent) and dissolved, and 0.05 part by weight of benzotriazole, 0.1 part by weight of aminothiazole, and 50,000 of molecular weight were added. 0.1 part by weight of polyacrylic acid was added. Finally, 30 parts by weight of hydrogen peroxide solution (special grade reagent, 30% by weight aqueous solution) was added to obtain a polishing solution. (Evaluation of polishing rate) Using the above polishing rate evaluation substrate and a polishing liquid, using a foamed polyurethane resin having closed cells in the polishing pad, the relative speed between the substrate and the supporting substrate: 36 m / m
In, polishing liquid flow rate: 300 ml / min was kept constant, and polishing was performed for 1 minute under each of three conditions of polishing pressure of 7 kPa, 14 kPa, and 21 kPa, and the relationship between the polishing pressure and the polishing rate was evaluated. The polishing rate by the blanket film is 50 nm / min at 7 kPa and 500 nm / min at 14 kPa.
It was 600 nm / min at 21 kPa. (Evaluation of Polishing Property) Using the above polishing property evaluation substrate and a polishing liquid, and using a foamed polyurethane resin having closed cells in the polishing pad, the relative speed between the substrate and the supporting substrate: 36 m / mi
n, polishing liquid flow rate: 300 ml / min, polishing pressure 14
Polishing was performed for 2 minutes and 10 seconds under the condition of kPa. The polishing time was until the remaining copper film was completely removed. Visual inspection of the substrate after CMP, surface observation with an optical microscope, and evaluation of dishing with a stylus profilometer were performed. As a result of visual observation and surface observation with an optical microscope, no peeling of the film was observed, and it was found that the film was completely polished without any copper residue.
When the dishing and erosion were measured with a stylus stepmeter, the dishing was 100/100 μm line /
It was 60 nm in the space portion.

Comparative Example 1 (Preparation of Evaluation Substrate) As the evaluation substrate, one prepared in the same manner as in Example 1 was used for both polishing speed and polishing characteristics. (Preparation of polishing liquid) In Example 1, the amount of aminothiazole was changed to 0.1 parts by weight → 0, and accordingly, the amount of water was changed to 70 →
A polishing liquid was prepared in the same manner except that the amount was 70.1 parts by weight. (Evaluation of Polishing Rate) A substrate for dishing evaluation was polished in the same manner as in Example except that polishing was performed at a polishing pressure of 21 kPa for 2 minutes. Polishing rate with blanket film is 45 at 7 kPa
65 nm / min, 21 k at nm / min, 14 kPa
It was 550 nm / min in Pa. (Evaluation of Polishing Property) Using the above polishing property evaluation substrate and a polishing liquid, using a foamed polyurethane resin having closed cells in the polishing pad, the relative speed between the substrate and the supporting substrate: 36 m / m
in, polishing liquid flow rate: 300 ml / min, polishing pressure 2
Polishing was performed for 2 minutes under the condition of 1 kPa. The polishing time was until the remaining copper film was completely removed. As a result of visual observation and surface observation with an optical microscope, it was found that peeling occurred at the interface between the SiLK and the silicon oxide film in the peripheral portion of the wafer. When the dishing was measured with a stylus type step meter, the dishing was 70 nm at 100/100 μm line / space part.
Met.

Metal oxidizing agents, metal oxide dissolving agents, anticorrosive agents,
C containing water-soluble polymer and interfacial peeling preventive agent for metal laminated film
In contrast to Example 1 using the MP polishing liquid, Comparative Example 1 using the polishing liquid containing no interfacial peeling inhibitor for the metal laminated film requires a polishing pressure higher than 20 kPa to obtain a practical polishing rate. Then, as a result, the interface peeling of the low dielectric constant insulating film material layer occurs due to polishing.

[0032]

According to the present invention, it is possible to provide a metal-polishing liquid containing a metal oxidizing agent, a metal oxide dissolving agent, an anticorrosive agent, a water-soluble polymer, and a metal laminated film interfacial peeling preventive agent.
Further, by using this polishing solution, the stress acting on the interface of the metal laminated film is relaxed and the surface of the substrate is polished while being flattened at a polishing pressure of less than 20 kPa, whereby the interface peeling of the low dielectric constant insulating film material layer occurs. It is possible to apply a method of polishing a substrate that is capable of performing high-speed polishing with a low polishing pressure and achieving high flatness.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an example of flattening unevenness on a substrate surface of the present invention.

FIG. 2 is a diagram showing an example of a CMP apparatus embodying the present invention.

[Explanation of symbols]

1. Si substrate 2. Low dielectric constant material layer 3. Silicon oxide layer 4. Barrier metal layer 5. Copper layer 11. Wafer holder 12. Retainer 13. Substrate that is a semiconductor chip 14. Copper layer 15. Polishing liquid supply mechanism 16. Metal polishing liquid 17. Polishing pad 18. Polishing surface plate

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C09K 3/14 550 C09K 3/14 550Z H01L 21/306 H01L 21/88 K 21/3205 21/306 M ( 72) Inventor Hajime Anzai 4-13-1, Higashi-cho, Hitachi-shi, Ibaraki F-term in Yamazaki Works, Hitachi Chemical Co., Ltd. (reference) 3C058 AA07 CB01 CB10 DA02 DA12 DA17 5F033 HH11 HH12 HH18 HH19 HH21 HH32 HH33 HH34 MM01 PP15 PP27 PP28 PP33 QQ09 QQ48 QQ50 RR01 RR04 RR06 RR21 RR29 SS15 SS21 WW00 WW05 XX01 XX24 5F043 AA27 BB18 DD16 FF07 GG10

Claims (4)

[Claims] 1. A metal polishing liquid containing a metal oxidizing agent, a metal oxide dissolving agent, an anticorrosive agent, a water-soluble polymer, and a metal laminate film interfacial peeling preventing agent. 2. A polishing rate at a polishing pressure of 7 kPa is 1
The polishing rate is 400 nm / min or more at a polishing pressure of 100 nm / min or less and a polishing pressure of 14 kPa.
The metal polishing liquid described. 3. A metal-polishing liquid containing a metal oxidizing agent, a metal oxide dissolving agent, an anticorrosive agent, a water-soluble polymer, and a metal laminated film interface peeling preventive agent is supplied to a polishing cloth on a polishing platen, By contacting the surface to be polished of the substrate which is the semiconductor chip on which the laminated film is formed and moving the surface to be polished and the polishing cloth relatively, the stress acting on the interface of the metal laminated film is relaxed and 20 kP
A polishing method which comprises polishing the surface of a substrate while flattening it with a polishing pressure of less than a. 4. The polishing method according to claim 3, wherein the metal laminated film comprises a low dielectric constant material layer and a copper layer or a copper alloy layer.