KR20090122182A - Polishing Method for Polishing Metals and Polished Films - Google Patents

Abstract

A polishing liquid for metals which comprises: a metal oxide solubilizer, a metal corrosion inhibitor, a polyacrylic acid polymer, a metal-oxidizing agent, and water. The metal-oxidizing agent is hydrogen peroxide, and the content of hydrogen peroxide is 12-30 mass% based on the polishing liquid for metals. With the polishing liquid for metals, a surface can be polished so as to realize excellent flatness while maintaining a satisfactory polishing speed. Also provided is a method of polishing a film to be polished which comprises using the polishing liquid.

Description

POLISHING LIQUID FOR METAL AND METHOD OF POLISHING FILM TO BE POLISHED}

The present invention relates to a polishing method for a polishing liquid for metal and a polished film.

Recently, new microfabrication techniques have been developed in accordance with high integration and high performance of semiconductor integrated circuits (hereinafter referred to as LSI). The chemical mechanical polishing (hereinafter referred to as CMP) method is one such technique, which is frequently used in the planarization of an interlayer insulating film, the formation of a metal plug, the formation of embedded wirings, etc. in an LSI manufacturing process, especially a multilayer wiring forming step. This technique is disclosed, for example, in US Pat. No. 4,444,836.

In recent years, in order to improve the performance of LSI, copper alloys have been attempted as wiring materials. However, the copper alloy is difficult to be finely processed by the dry etching method frequently used in the formation of conventional aluminum alloy wiring. Thus, for example, a so-called damascene method is mainly used in which a copper alloy thin film is deposited on an insulating film in which grooves are formed in advance and embedded, and a copper alloy thin film other than the groove portion is removed by CMP to form embedded wiring. It is adopted. This technique is disclosed in, for example, Japanese Patent Laid-Open No. 2-278822.

The general method of CMP of metal is the surface which affixed the polishing cloth on the circular polishing plate, immersed the surface of the polishing cloth in the polishing liquid for metal, and formed the metal film of the board | substrate. Is pressed, and the polishing surface is turned while applying a predetermined pressure (hereinafter referred to as polishing pressure) from the back surface thereof to remove the metal film of the convex portion by mechanical friction between the metal polishing liquid and the convex portion of the metal film. The polishing liquid for metals used for CMP generally contains an oxidizing agent and an abrasive grain, and a metal oxide dissolving agent, a metal anticorrosive, etc. are further added as needed. First, it is thought that the basic mechanism is to oxidize the surface of the metal film with an oxidizing agent and to cut the oxide layer by the abrasive grains. Since the oxide layer of the metal surface of the concave portion does not come into contact with the polishing cloth very much, and the effect of cutting by the abrasive grains is not effective, the metal layer of the convex portion is removed and the substrate surface is flattened with the progress of CMP. This technique is disclosed, for example, in pages 3460-3464 of Journal of Electrochemical Society Vol. 138, No. 11 (issued in 1991).

Disclosure of Invention

In the case of forming embedded wirings by CMP using a conventional polishing liquid for metals, when the content of the metal oxidant is small with respect to the weight of the polishing liquid for metals, sufficient flatness of the surface to be polished cannot be obtained. On the contrary, when the content of the metal oxidant is excessive with respect to the weight of the polishing liquid for metal, a problem arises in that the polishing rate of the metal, in particular, copper cannot be sufficiently obtained. An object of the present invention is to provide a polishing liquid for metal, a metal polishing liquid material and a polishing method for achieving excellent flatness of the surface to be polished while maintaining a good polishing rate.

As a result of earnest examination in order to solve such a conventional problem, the present inventors set the content of the oxidizing agent of the metal in the polishing liquid for metal to a specific range, thereby achieving excellent flatness of the surface to be polished while maintaining a good polishing rate. Succeeded.

The present invention comprises (1) a metal oxide dissolving agent, a metal anticorrosive agent, a polyacrylic acid polymer, a metal oxidizing agent and water,

The metal oxidant is hydrogen peroxide,

Content of the said hydrogen peroxide water is related with the polishing liquid for metals which is 12-30 weight% with respect to the weight of the polishing liquid for metals.

Moreover, this invention relates to the polishing liquid for metals of said (1) whose content of the said metal oxide dissolving agent is 0.001-10 weight% with respect to the weight of the polishing liquid for metals.

Moreover, this invention relates to the polishing liquid for metals of said (1) or (2) whose content of the said metal anticorrosive agent is 0.001-10 weight% with respect to the weight of the polishing liquid for metals.

Moreover, this invention relates to the polishing liquid for metals in any one of said (1)-(3) whose (4) said polyacrylic-acid polymer is an ammonium polyacrylate salt.

Moreover, this invention relates to the polishing liquid for metals in any one of said (1)-(4) containing (5) abrasive grains.

Moreover, this invention supplies the board | substrate before grinding | polishing which has a to-be-polished film to a polishing cloth, supplying the polishing liquid material for any one of said base materials of said (1)-(5) on the polishing cloth of (6) polishing platen. The polishing substrate is obtained by relatively operating the polishing platen and the substrate in a pressed state, thereby polishing the substrate to be obtained, thereby obtaining a substrate.

Implement the invention  Best form for

EMBODIMENT OF THE INVENTION Hereinafter, preferred embodiment of the polishing liquid for metals of this invention is described in detail.

The polishing liquid for metals of this invention is a polishing liquid for metals containing a metal oxide dissolving agent, a metal anticorrosive agent, a polyacrylic-acid polymer, a metal oxidizing agent, and water.

As the metal oxidant used in the present invention, hydrogen peroxide (H ₂ O ₂ ) is particularly preferable. Examples of the oxidizing agent include nitric acid, potassium periodate, hypochlorous acid, ozone water, and the like. In the specific aspect of the present invention, when an acid other than hydrogen peroxide is used, the polishing rate of wiring metals such as copper tends to be increased. Finally, the flatness of the surface to be polished tends to be lost.

In the case where the substrate to be polished is a silicon substrate including an integrated circuit element, contamination by alkali metals, alkaline earth metals, halides, etc. is not preferable. Therefore, it is preferable to use a non-volatile component in the oxidant. . However, when the substrate to be polished is a glass substrate or the like which does not contain a semiconductor element, it may be an oxidizing agent containing a nonvolatile component.

In one aspect of the present invention, hydrogen peroxide, which is a metal oxidant, is added so that the concentration in the polishing liquid is 12 to 30% by weight. Since hydrogen peroxide is generally unstable and dangerous in a single body, it is produced and sold as an aqueous solution of about 20 to 35 wt% of hydrogen peroxide, and most commonly available hydrogen peroxide is 30 wt%. Conventionally, a polishing liquid for adding hydrogen peroxide is known. Usually, the amount of hydrogen peroxide added is described as the amount of hydrogen peroxide aqueous solution added. In this invention, the hydrogen peroxide water is added so that it may become 12 to 30 weight% using the value obtained by calculating the amount of hydrogen peroxide in hydrogen peroxide water, not the addition amount of hydrogen peroxide water.

FIG. 1 shows a plurality of polishing liquids containing a metal anticorrosive agent, a polyacrylic acid polymer, and hydrogen peroxide as a metal oxidant, and changing only the concentration of hydrogen peroxide (4% by weight, 11% by weight, and 18% by weight of hydrogen peroxide). The etching rate (isotropic copper dissolution rate) when the chip of the copper wafer cut into the size of 20 mm x 20 mm is immersed for 10 minutes is shown. As can be seen from FIG. 1, when the hydrogen peroxide concentration rises, etching is suppressed.

Similarly, a plurality of polishing liquids containing a metal anticorrosive agent, a polyacrylic acid polymer, and hydrogen peroxide as the metal oxidant and changing only the concentration of hydrogen peroxide (7% by weight and 18% by weight) are prepared, and a copper wafer is prepared under the same polishing conditions. When the dishing amount (Line & Space = 100 µm / 100 µm part at the time of polishing, the film type of the surface changes depending on the progress of polishing), as shown in Fig. 2, when the amount of oxidant is increased, the dishing amount is decreased. It turns out that a grinding | polishing rate falls.

As described above, the reason why the amount of dishing is reduced is that the hard and strong reaction layer (for example, copper complex) is formed by increasing the amount of hydrogen peroxide which is a metal oxidant, which protects the recess in the polishing process. Guess. Then, when the other polishing liquid containing 7 weight% and 17.5 weight% hydrogen peroxide was adjusted, and copper foil was immersed here, the reaction layer which arises on the surface of copper foil was observed, and hardness and thickness were measured. The results are shown in Table 1.

In Table 1, it can be seen that by increasing the metal oxidizing agent (hydrogen peroxide) concentration, the reaction layer formed on the surface of copper becomes harder. However, it was found that the thickness of the reaction layer was not thickened but thinned by increasing the concentration of the metal oxidant. Therefore, as a result of measuring the oxygen concentration in the reaction layer, as shown in Table 1, it was found that the oxygen concentration was high by increasing the concentration of the metal oxidant. From these results, it can be seen that, by increasing the concentration of the oxidant, the reaction layer has a higher oxygen concentration, a thinner thickness, and a harder hardness.

TABLE 1

Measurement result of the reaction layer

* 1 As for the hardness of the film, it is measured by the scratch test.

* 2 Film thickness and oxygen concentration are analyzed by SIMS

* 3 unit: (atoms / cm3) × 1021

From the above results, it is assumed that the reaction layer is as shown in FIG. 3. As shown in Fig. 3, copper, polyacrylic acid polymers, and metal anticorrosive agents are intricately entangled, which contains a large amount of oxygen, creates a thin and hard reaction layer (copper complex), protects the film of the recess, and contributes to polishing. I think. By increasing the hydrogen peroxide concentration, a thin and hard reaction layer is formed, and even if a reaction layer is formed in the convex portion, it is cut out by polishing, but it is considered that the reaction layer accumulates in the concave portion and it is difficult to penetrate the polishing liquid. In addition, when the concentration of hydrogen peroxide is made high, the etching rate tends to be slow, and it is considered that dishing is suppressed by both actions due to accumulation of the reaction layer and lowering of the etching rate in the concave portion.

The polishing liquid of the present invention is completed from the above idea, and the concentration of hydrogen peroxide, which is an oxidizing agent of the metal, is set between 12 to 30% by weight. Also about other abrasive components, the optimal thing can be selected under the said thought, and it demonstrates in detail below. In addition, in order to acquire the effect of each component, the more effective addition amount is mentioned later.

The metal oxide dissolving agent used in the present invention is not particularly limited as long as it is water-soluble. For example, 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, glycerinic acid, oxalic acid, malonic acid, succinic acid, And organic acids such as glutaric acid, adipic acid, pimeline acid, maleic acid, phthalic acid, malic acid, tartaric acid, citric acid, organic acid esters thereof, and ammonium salts of these organic acids. Moreover, inorganic acids, such as hydrochloric acid, a sulfuric acid, nitric acid, phosphoric acid, ammonium salts of these inorganic acids, for example, ammonium persulfate, ammonium nitrate, ammonium chloride, chromic acid, etc. are mentioned. Among them, formic acid, malonic acid, malic acid, tartaric acid, citric acid, succinic acid and phosphoric acid are copper, copper alloys and copper or copper as the film to be polished, in that the etching rate can be effectively suppressed while maintaining a practical polishing rate. It is suitable for laminated films containing at least one metal layer selected from oxides of alloys. These can be used individually by 1 type or in mixture of 2 or more types.

The metal anticorrosive agent used in the present invention is, for example, a compound having a triazole skeleton, a compound having a pyrazole skeleton, a compound having a pyrimidine skeleton, a compound having an imidazole skeleton, a compound having a guanidine skeleton, a thia The compound which has a sol skeleton, etc. are mentioned.

Examples of the compound having a triazole skeleton include 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 -Carboxyl (-1H-) benzotriazole methyl ester, 4-carboxyl (-1H-) benzotriazole butyl ester, 4-carboxyl (-1 H-) benzotriazole octyl ester, 5-hexyl benzotriazole , [1,2,3-benzotriazol-1-methyl] [1,2,4-triazolyl-1-methyl] [2-ethylhexyl] amine, tolyltriazole, naphthotriazole, bis [( 1-benzotriazolyl) methyl] phosphonic acid etc. are mentioned.

Examples of the compound having a pyrazole skeleton include 3,5-dimethylpyrazole, 3-methyl-5-pyrazole, 3-amino-5-methylpyrazole, 3-amino-5-hydroxypyrazole, 3-amino-5-methylpyrazole etc. are mentioned.

Examples of the compound having a pyrimidine skeleton include pyrimidine, 1,2,4-triazolo [1,5-a] pyrimidine, 1,3,4,6,7,8-hexahydro-2H- Pyrimid [1,2-a] pyrimidine, 1,3-diphenyl-pyrimidine-2,4,6-trione, 1,4,5,6-tetrahydropyrimidine, 2,4,5, 6-tetraaminopyrimidinesulphite, 2,4,5-trihydroxyhydroxypyrimidine, 2,4,6-triaminopyrimidine, 2,4,6-trichloropyrimidine, 2,4,6- Trimethoxypyrimidine, 2,4,6-triphenylpyrimidine, 2,4-diamino-6-hydroxypyrimidine, 2,4-diaminopyrimidine, 2-acetamidepyrimidine, 2- Aminopyrimidine, 2-methyl-5,7-diphenyl- (1,2,4) triazolo (1,5-a) pyrimidine, 2-methylsulfanyl-5,7-diphenyl- (1 Triazolo (1,5-a) pyrimidine, 2-methylsulfanyl-5,7-diphenyl-4,7-dihydro- (1,2,4) triazolo (1, 5-a) pyrimidine, 4-aminopyrazolo [3,4-d] pyrimidine, and the like.

As a compound which has an imidazole skeleton, for example, imidazole, 2-methylimidazole, 2-ethylimidazole, 2-isopropylimidazole, 2-propylimidazole, 2-butylimidazole , 4-methylimidazole, 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-aminoimidazole, mercaptobenzoimidazole and the like.

As a compound which has a guanidine skeleton, 1, 3- diphenyl guanidine, 1-methyl-3- nitro guanidine, etc. are mentioned, for example.

As the compound having a thiazole skeleton, for example, 2-aminothiazole, 4,5-dimethylthiazole, 2-amino-2-thiazoline, 2,4-dimethylthiazole, 2-amino-4-methyl Thiazole etc. are mentioned.

Among these, triazole, benzotriazole, and 2-methylimidazole are preferable in obtaining a low etching rate. These can be used individually by 1 type or in mixture of 2 or more types.

Although the polyacrylic acid type polymer is contained in the abrasive | polishing agent for metals of this invention, you may use together another water-soluble polymer.

Examples of the polyacrylic acid polymer include polyacrylic acid, polyacrylamide, amino polyacrylamide, ammonium polyacrylate salt, sodium polyacrylate salt, and the like. Among these, the ammonium polyacrylate salt is particularly preferable because the substrate to be polished is not contaminated by the alkali metal, alkaline earth metal, halide or the like in the case of a silicon substrate for semiconductor integrated circuit or the like.

As other water-soluble polymers, For example, polysaccharides, such as arginic acid, pectinic acid, carboxymethylcellulose, agar, curdlan, and pullulan; Polyaspartic acid, polyglutamic acid, polylysine, polymalic acid, polymethacrylic acid, polymethacrylic acid ammonium salt, polymethacrylic acid salt, polyamic acid, polymaleic acid, polyitaconic acid, polyfumaric acid, poly (p-styrene Carboxylic acid), polycarboxylic acid, polyamic acid ammonium salt, polycarboxylic acid sodium salt and polyglyoxylic acid, polycarboxylic acid, polycarboxylic acid ester, these copolymers and salts thereof, polyvinyl alcohol, polyvinylpyrroly Vinyl polymers such as toxin and polyacrolein; and the like.

However, when the substrate to be polished is a silicon substrate for a semiconductor integrated circuit or the like, contamination by the alkali metal, alkaline earth metal, halide or the like is not preferable. Thus, the polyacrylic acid polymer and the water-soluble polymer may be acid or the like. Ammonium salts are preferred. This is not the case when the substrate to be polished is a glass substrate or the like. Among them, pectinic acid, agar, polymalic acid, polymethacrylic acid, ammonium polyacrylate, polyacrylamide, polyvinyl alcohol and polyvinylpyrrolidone, esters thereof and ammonium salts thereof are preferable. These can be used individually by 1 type or in mixture of 2 or more types.

The weight average molecular weight of the polyacrylic acid polymer and the water-soluble polymer is preferably 500 to 1 million, more preferably 1000 to 500,000, particularly preferably 5000 to 200,000, and most preferably 10,000 to 150,000. Most preferred. However, the weight average molecular weight in this invention is measured by gel permeation chromatography, and uses the value converted into polyacrylic acid.

In the metal polishing liquid of the present invention, it is important to set the content of hydrogen peroxide as the metal oxidizing agent to 12 to 30% by weight based on the weight (total amount) of the metal polishing liquid, and by setting the above content, a good polishing rate is achieved. While maintaining, excellent flatness of the surface to be polished can be realized. When the content of hydrogen peroxide is 10% by weight, sufficient flatness of the surface to be polished tends to be obtained, but flatness can be more reliably obtained when it is 12% by weight or more. When it is 30 weight% or less, the polishing rate of metal, especially copper can fully be obtained. It is preferable to make a minimum into 12 weight% from the viewpoint of flatness, and, as for content of the said hydrogen peroxide, it is more preferable to set it as 14 weight%. In addition, from the point of obtaining a favorable polishing rate, 30 weight% is preferable, as for an upper limit, 25 weight% is more preferable, and 23 weight% is especially preferable. It is preferable that it is 12-25 weight% from a viewpoint of both the flatness of a to-be-polished surface, and a polishing rate, and it is more preferable that it is 12-23 weight%. In addition, in this invention, the density | concentration of hydrogen peroxide shows the quantity of hydrogen peroxide itself contained in polishing liquid, and is not the quantity of hydrogen peroxide. For example, in the polishing liquid in which 30 weight% of hydrogen peroxide water generally sold is added 30 weight% of the polishing liquid, the amount of hydrogen peroxide is calculated to be 30 weight% x 30 weight% = 9 weight%.

In the present invention, the content of the metal oxide dissolving agent is preferably 0.001 to 10% by weight, more preferably 0.01 to 5% by weight based on the weight (total amount) of the metal polishing liquid. By adjusting the content of the metal oxide solubilizer in the above range, excellent surface flatness can be realized while maintaining a good polishing rate.

In the present invention, the content of the metal anticorrosive agent is preferably 0.001 to 10% by weight, more preferably 0.01 to 5% by weight, particularly preferably 0.02 to 2.0% by weight based on the weight (total amount) of the metal polishing liquid. %to be. By adjusting the content of the metal anticorrosive agent in the above range, excellent surface flatness can be realized while maintaining a good polishing rate.

In the present invention, the content of the polyacrylic acid polymer is preferably 0.001 to 10% by weight, more preferably 0.01 to 5% by weight, particularly preferably 0.02 to 2.0, based on the weight (total amount) of the metal polishing liquid. Weight percent. By adjusting the content of the polyacrylic acid polymer in the above range, excellent surface flatness can be realized while maintaining a good polishing rate.

When using another water-soluble polymer together, it is preferable to set it as 0.01 to 5 weight% in total content of a polyacrylic-acid polymer and a water-soluble polymer.

The polishing liquid for metals of the present invention may contain abrasive grains. Examples of the abrasive include inorganic abrasive particles such as silica, alumina, zirconia, ceria, titania, germania, silicon carbide, and organic abrasive particles such as polystyrene, polyacryl, and polyvinyl chloride. Among these, silica, alumina, zirconia, ceria, titania, and germania are preferable, and silica or alumina is particularly preferable. Among silica or alumina, colloidal silica or colloidal alumina, which has good dispersion stability in the polishing liquid and is less likely to generate abrasive scratches (scratches) caused by CMP, is preferable. These abrasive grains can be used individually by 1 type or in mixture of 2 or more types.

Colloidal silica can be produced by a known production method by hydrolysis of silicon alkoxide or ion exchange of sodium silicate, and in terms of particle size controllability and alkali metal impurities, tetramethoxysilane or tetraethoxysilane The method of hydrolyzing silicon alkoxides, such as these, is used most. In addition, colloidal alumina can be manufactured by a well-known manufacturing method by hydrolysis of aluminum nitrate.

In the present invention, the content of the abrasive grains is preferably 0.01 to 3% by weight, more preferably 0.05 to 2% by weight based on the weight (total amount) of the polishing liquid for metal. By setting content of the said abrasive grain in the said range, favorable grinding | polishing speed and flatness can be made compatible.

The metal polishing liquid of the present invention may contain, in addition to the above-mentioned materials, coloring agents such as organic solvents such as alcohols, surfactants, dyes such as Victoria Pure Blue, and pigments such as phthalocyanine green.

The polishing liquid for metal of the present invention is a polishing liquid containing a metal oxide dissolving agent, a metal anticorrosive material, a polyacrylic acid polymer, hydrogen peroxide and water, but the polishing liquid may be stored and used as it is. In addition, it may be stored as a metal polishing liquid material containing a metal oxide dissolving agent, a metal anticorrosive material and water, and may be used in combination with the metal polishing liquid material, hydrogen peroxide and water as appropriate, in this case, polyacrylic You may add an acidic polymer at any time. That is, the polishing liquid for metal at the time of grinding | polishing should just contain the metal oxide dissolving agent, a metal anticorrosive material, a polyacrylic-acid polymer, hydrogen peroxide, and water.

In the polishing method of the present invention, the polishing platen and the substrate are relatively operated while the substrate (before polishing) having the polishing film is pressed against the polishing cloth while the polishing solution for metal of the present invention is supplied onto the polishing cloth of the polishing platen. It is a grinding | polishing method of grind | polishing a to-be-finished film and obtaining a pattern wiring board.

In addition, the polishing method of the present invention provides the relative polishing surface and the substrate in a state in which the substrate having the polishing film is pressed against the polishing cloth while supplying the polishing liquid material for metal and the oxidizing agent of the metal on the polishing cloth of the polishing plate. It is a polishing method of polishing a to-be-polished film by operating with.

In addition, in the polishing method of the present invention, the polishing plate and the substrate are pressed in a state in which the substrate having the polishing film is pressed against the polishing cloth while supplying the polishing liquid material for metal of the present invention, the metal oxidant and water onto the polishing cloth of the polishing platen. It is a polishing method for polishing a polished film by operating relatively.

In the polishing method of the present invention, in the polishing liquid for metal of the present invention, only the hydrogen peroxide or hydrogen peroxide and water are mixed, and the metal polishing liquid material is mixed, and the metal polishing liquid material and hydrogen peroxide (or hydrogen peroxide and water) are mixed. The polishing film may be polished by relatively operating the polishing platen and the substrate while the substrate having the to-be-polished film is pressed against the polishing cloth while feeding the substrate onto the polishing cloth of the polishing platen.

The to-be-polished film which applies the grinding | polishing method of this invention contains a metal normally, As the metal, For example, copper, a copper alloy, an oxide of copper, an oxide of a copper alloy, tungsten, tungsten nitride, a tungsten alloy, etc. Titanium compounds, such as a tungsten compound, titanium, titanium nitride, and a titanium alloy, tantalum compounds, such as tantalum, tantalum nitride, and a tantalum alloy, etc. are mentioned. Among these, copper, a copper alloy, the oxide of copper, the oxide of a copper alloy, etc. are preferable. As these to-be-polished films, the metal film formed by the well-known sputtering method and the plating method can be used.

As a device for polishing, a general polishing device having a holder holding a substrate to be polished, a polishing plate that can be attached to a motor or the like capable of changing the rotational speed and affixing a polishing cloth can be used. As the polishing cloth, a general nonwoven fabric, a foamed polyurethane, a porous fluorocarbon resin, or the like can be used, and there is no particular limitation. The polishing conditions are not particularly limited, but a low rotation of 200 rpm or less is preferable so that the rotational speed of the polishing platen does not protrude. It is preferable that the press part pressure to the polishing cloth of the board | substrate which has a to-be-polished film is 1-100KPa, and in order to satisfy the uniformity in the to-be-polished surface of a polishing rate, and flatness of a pattern, it is more preferable that it is 5-50KPa.

While polishing, the polishing cloth for metal is continuously supplied to the polishing cloth by a pump or the like. Although this supply amount is not limited, it is preferable that the surface of the polishing cloth is always covered with the polishing liquid.

It is preferable to dry the board | substrate after grinding | polishing after flowing well in flowing water, after dropping the water droplet which adhered on the board | substrate using spin dry etc.

1 is a graph showing the results of evaluating the etching rate with respect to the hydrogen peroxide concentration in the polishing liquid for metals.

2 is a graph showing the results of evaluating the dishing amount with respect to the hydrogen peroxide concentration in the polishing liquid for metals.

Fig. 3 is a diagram showing an estimated reaction mechanism in a to-be-polished film (copper alloy) using the polishing liquid for metal of the present invention.

Best Modes for Carrying Out the Invention Hereinafter, the best mode of the present invention will be described in more detail, but the present invention is not limited to these examples.

(Examples 1-9, Comparative Examples 1-11)

<How to make a polishing solution>

The materials were mixed by the mixing | blending as shown in Tables 2-4, and the polishing liquid for metals used in Examples 1-9 and Comparative Examples 1-11 was produced. In addition,% in Table 2-Table 4 is weight%. Polishing was performed under the following polishing conditions using this metal polishing liquid.

<Polishing condition>

Blanket substrate: A silicon substrate on which a copper film with a thickness of 1600 nm is formed.

Pattern Substrate: A groove having a depth of 0.5 µm is formed in organosilicate formed by CVD or silicon dioxide using trimethylsilane as a starting material using a known method, and has a thickness of 20 nm as a barrier layer according to a known sputtering method. The board | substrate which formed only the tantalum film | membrane, and similarly polished the copper film which protruded by the well-known method the board | substrate which formed 0.1 micrometer of copper films by sputtering method, and 1.0 micrometer of copper films by plating method.

Grinding cloth: IC1000 (Rodel Corporation)

Polishing pressure: 2psi (13.7MPa)

Relative speed between base and polishing table: 36m / min

Supply amount of polishing liquid: 200ml / min

<Evaluation item>

Polishing rate: The blanket substrate was polished for 60 seconds with the metal polishing liquid, and the film thickness difference before and after polishing was calculated in terms of electric resistance values.

Flatness (discing amount): The pattern substrate was polished for 180 seconds with the metal polishing liquid. The surface shape of the stripe-shaped pattern portion in which the width of the wiring metal portion having a width of 100 μm and the insulating film portion having a width of 100 μm formed on the pattern substrate were alternately reduced is measured by a tactile step meter, and the film reduction amount of the wiring metal portion with respect to the insulating film portion is measured. It calculated | required and set it as the index of flatness.

Copper residue: The presence or absence of the copper residue on a board | substrate was observed with the naked eye or a metal microscope on the said pattern substrate after grind | polishing for 180 second with the said metal polishing liquid.

The various characteristics in Examples 1-9 and Comparative Examples 1-11 measured by the said method were shown to Tables 2-4.

TABLE 2

* 1: The weight average molecular weight of ammonium polyacrylate is 130,000.

* 2: A 35.0% aqueous solution was used as the hydrogen peroxide solution.

TABLE 3

* 1: The weight average molecular weight of ammonium polyacrylate is 130,000.

* 2: A 35.0% aqueous solution was used as the hydrogen peroxide solution.

TABLE 4

* 1: The weight average molecular weight of ammonium polyacrylate is 130,000.

* 2: A 35.0% aqueous solution was used as the hydrogen peroxide solution.

The polishing liquid for metal of the present invention can realize the excellent flatness of the surface to be polished while maintaining a good polishing rate. On the other hand, it turns out that the comparative examples 1-8 whose content of hydrogen peroxide are less than 12 weight% with respect to the weight of the polishing liquid for metals are inferior to the flatness of a to-be-polished surface. Moreover, the comparative example 9 in which content of hydrogen peroxide exceeds 30 weight% with respect to the weight of the polishing liquid for metals discovered that the polishing rate of a metal, especially copper was not fully acquired. It can be seen that in Comparative Example 10 in which the polyacrylic acid polymer is not added, the polishing rate decreases. In Comparative Example 11, in which the metal anticorrosive was not developed, the flatness of the surface to be polished was poor, and the polishing rate was also lowered.

According to the present invention, it is possible to provide a polishing liquid for metal and a polishing method for a polished film which can realize excellent flatness of the polished surface while maintaining a good polishing rate.

Claims (6)

It contains a metal oxide dissolving agent, a metal anticorrosive agent, a polyacrylic acid polymer, a metal oxidizing agent and water, The metal oxidant is hydrogen peroxide, The polishing liquid for metals whose content of the said hydrogen peroxide is 12-30 weight% with respect to the weight of the polishing liquid for metals. The metal polishing liquid according to claim 1, wherein the content of the metal oxide dissolving agent is 0.001 to 10% by weight based on the weight of the metal polishing liquid. The polishing liquid for metals of Claim 1 or 2 whose content of the said metal anticorrosive agent is 0.001-10 weight% with respect to the weight of the polishing liquid for metals. The polishing liquid for metal according to any one of claims 1 to 3, wherein the polyacrylic acid polymer is an ammonium polyacrylate salt. The polishing liquid for metal according to any one of claims 1 to 4 containing abrasive grains. The polishing platen and the substrate before polishing are operated relatively while the substrate having the polished film is pressed against the polishing cloth while supplying the polishing liquid for metal according to any one of claims 1 to 5 on the polishing cloth of the polishing platen. And polishing a to-be-polished film to obtain a substrate.

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