JP2001085372A - Metal polishing liquid and polishing method for substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To be applicable to a polish surface where different materials appear by, related to a metal polishing liquid, adjusting a polishing speed ratio between a copper or copper alloy and a barrier layer based on the concentration of an oxidant, with pH at a specified value or below. SOLUTION: A metal polishing liquid is a conductive oxidant comprising hydrogen peroxide, nitric acid, potassium periodate, hypochlorous acid, and ozone solution, etc., a protective film formation agent for a metal surface such as benzotriazole, and naphthotriazole, etc., and a polishing liquid containing acid and water, and, the concentration of an oxidant is adjusted according to an insulating layer part for an applied process, a copper on a barrier layer, or the degree of copper alloy residue, with pH at 3 or below. A substrate is polished using a polishing agent like this so that a barrier layer at the protruding part of substrate is exposed on the surface of a barrier layer at the protruding part of substrate, providing an intended conductor pattern where a copper or copper alloy film remains at a recessed part.

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 used for polishing in a wiring forming 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 in, for example, US Pat. No. 4,944,836.

[0003] Recently, in order to improve the performance of LSI, utilization of copper or copper alloy as a wiring material has been attempted. However, it is difficult to finely process copper or a copper alloy by a dry etching method frequently used in forming a conventional aluminum alloy wiring. Therefore, a so-called damascene method is mainly used in which a copper or copper alloy thin film is deposited and buried on an insulating film in which a groove is formed in advance, and the copper or copper alloy thin film other than the groove is removed by CMP to form a buried wiring. Has been adopted. This technology is disclosed in, for example,
278822.

A general method of metal CMP such as copper or copper alloy is to attach a polishing pad on a circular polishing platen (platen), immerse the polishing pad surface with a metal polishing solution, and remove the metal film on the substrate. The formed surface is pressed, and the polishing platen is rotated while applying a predetermined pressure (hereinafter, referred to as polishing pressure) from the back surface, and the metal film of the convex portion is formed by mechanical friction between the polishing liquid and the convex portion of the metal film. Is to be removed. The metal polishing solution used for CMP generally comprises an oxidizing agent and solid abrasive grains, and further includes a metal oxide dissolving agent and a protective film forming agent as necessary. It is considered that the basic mechanism is to oxidize the surface of the metal film with an oxidizing agent, and to scrape off the oxidized layer with solid abrasive grains. Since the oxide layer on the metal surface of the concave portion does not substantially touch the polishing pad and does not have the effect of the scraping by the solid abrasive grains, the metal layer of the convex portion is removed with the progress of the CMP, and the substrate surface is flattened. For details, refer to Journal of Electrochemical Society, Vol. 138, No. 11, published in 1991.
It is disclosed on pages 460-3644.

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 (hereinafter referred to as "etching") the metal oxide particles removed by the solid abrasive grains in the polishing liquid increases the effect of the solid abrasive grains. 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) and the metal film surface is exposed, the metal film surface is further oxidized by the oxidizing agent. If this is repeated, the etching of the metal film in the concave portion proceeds. For this reason, a phenomenon (hereinafter referred to as dishing) occurs in which the central portion of the surface of the metal wiring buried after polishing is dish-like, 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 dissolving in the polishing liquid. This protective film can be easily scraped off by solid abrasive grains, and it is desired that the polishing rate by CMP is not reduced. Contains a metal oxide dissolving agent consisting of aminoacetic acid or amide sulfuric acid such as glycine, and BTA as a protective film forming agent to suppress corrosion during dishing or polishing of copper or copper alloy and form highly reliable LSI wiring A method using a metal polishing solution has been proposed. This technique is described, for example, in 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, if 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 in the lower layer of the wiring such as copper or copper alloy to prevent copper diffusion into the interlayer insulating film. . 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 conductors have higher hardness than copper or copper alloy, a sufficient polishing rate cannot often be obtained with a combination of polishing materials for copper or copper alloy. 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 the polishing of copper or copper alloy in the first step, in the insulating layer portion other than the buried wiring portion, the copper or copper alloy on the upper part of the barrier film is completely polished uniformly in the wafer surface, and the ideal barrier layer is exposed. In such a state, in the CMP of the barrier layer in the second step, a polishing liquid capable of selectively polishing the barrier layer with respect to copper or a copper alloy is effective. On the other hand, in the upper layer process of the multilayer wiring, uniformity and flatness in the wafer surface vary due to accumulation of minute residual steps and non-uniformity in the lower layer process. Copper or copper alloy remains in the barrier layer. In such an upper layer process, it is necessary to polish the barrier layer after removing the copper or copper alloy remaining in the polishing of the barrier layer in the second step by polishing. As described above, the characteristics of the polishing rate ratio between the copper or copper alloy and the barrier layer conductor required for the polishing liquid in the second step are different depending on the application location of the process. In the polishing of a barrier layer which requires polishing of copper or a copper alloy, when a polishing liquid for copper or a copper alloy is applied, problems such as an increase in dishing of wiring or an insufficient polishing rate of the barrier layer cannot be obtained. is there.

[0010]

The tantalum, tantalum alloy, tantalum nitride and other tantalum compounds used as the barrier layer are chemically stable and difficult to etch, and have high hardness, so that the mechanical polishing can be performed using copper or copper. Not as easy as alloys. Further, in the polishing of the barrier layer, a required polishing rate ratio with respect to copper or a copper alloy is different depending on a portion to which the process is applied, so that there is a problem that a polishing liquid having a different composition must be applied. The present invention is applicable to polishing of tantalum, tantalum alloy, tantalum nitride, and other tantalum compounds used as copper or a copper alloy and a barrier layer conductor, by adjusting one component of a polishing solution, a different material appears. Accordingly, it is an object of the present invention to provide a metal polishing liquid capable of efficiently forming a buried pattern of a metal film and a method of polishing a substrate using the same.

[0011]

The metal-polishing liquid of the present invention is a polishing liquid containing an oxidizing agent for a conductor, a protective film forming agent for a metal surface, an acid and water, and has a pH of 3 or less;
This is a metal polishing liquid capable of adjusting the polishing rate ratio between copper or a copper alloy and the barrier layer by adjusting the concentration of the oxidizing agent. The concentration of the oxidizing agent is preferably 0.01 to 10% by weight, more preferably 0.01 to 3% by weight. The metal polishing liquid may further contain a water-soluble polymer. The water-soluble polymer is preferably at least one selected from the group consisting of polyacrylic acid or a salt thereof, polymethacrylic acid or a salt thereof, polyacrylamide, polyvinyl alcohol, polyvinylpyrrolidone, polyamic acid and a salt thereof. The acid is preferably an organic acid, malonic acid,
More preferably, it is at least one selected from malic acid, tartaric acid, glycolic acid and citric acid. As the protective film forming agent for the metal surface, at least one kind (BTAs) selected from benzotriazole (BTA) and its derivatives, which have been widely used in the past, is used. The oxidizing agent for the conductor is preferably at least one selected from hydrogen peroxide, nitric acid, potassium periodate, hypochlorous acid, and ozone water. The metal-polishing liquid may contain abrasive grains. The abrasive grains are preferably at least one selected from silica, alumina, ceria, titania, zirconia, and germania, and more preferably colloidal silica or colloidal alumina having an average particle diameter of 100 nm or less. The conductor is a barrier layer of copper or a copper alloy, and the barrier layer is tantalum, tantalum nitride, a tantalum alloy, or another tantalum compound. The polishing liquid for metal of the present invention preferably has a polishing rate ratio (Ta / SiO ₂ , TaN / SiO ₂ ) of tantalum, tantalum nitride and silicon dioxide film of more than 10. The polishing method of the present invention is a polishing method for polishing a barrier layer made of tantalum, tantalum nitride, a tantalum alloy, and other tantalum compounds using the above-mentioned metal polishing slurry. The polishing method of the present invention is a polishing method for polishing a surface containing copper or a copper alloy and its barrier layer using the above-mentioned metal polishing liquid.

According to the present invention, dishing, thinning, and polishing scratches of copper or copper alloy wiring are suppressed by using a metal polishing solution in a low pH region and a low oxidizing agent concentration region, and the barrier layer is formed at a low abrasive particle concentration. The present invention provides a metal polishing liquid realizing a high polishing rate and a method for polishing a substrate using the same. As a method of polishing the barrier layer, a required polishing rate ratio of copper or a copper alloy differs depending on a portion to which a process is applied, and therefore, there is a problem that a polishing liquid having another composition having different characteristics must be applied. The present inventors have found that polishing of tantalum, a tantalum alloy, tantalum nitride, and other tantalum compounds used as a barrier layer conductor easily proceeds in a low pH region and a low oxidizing agent concentration region, and that the oxidizing agent concentration makes copper polishing possible. Alternatively, it has been found that the polishing rate ratio with the copper alloy can be adjusted.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a barrier layer and a metal film containing copper or a copper alloy are formed and filled on a substrate having a concave portion of silicon dioxide on the surface. When the substrate is first subjected to CMP using a polishing liquid for copper or copper alloy having a sufficiently high polishing rate ratio of copper or copper alloy / barrier layer, the barrier layer of the convex portion of the substrate is exposed on the surface, and the copper or copper A desired conductor pattern with the alloy film left is obtained. The metal polishing liquid of the present invention is a polishing liquid containing an oxidizing agent for a conductor, a protective film forming agent for a metal surface, an acid and water, and has a pH of 3
The concentration of the oxidizing agent is adjusted according to the degree of the copper or copper alloy remaining on the insulating layer portion and the barrier layer in the process to be applied. If necessary, a water-soluble polymer may be added. If the pH of the metal polishing liquid in the present invention exceeds 3 and is large, the polishing rate of tantalum, a tantalum alloy, tantalum nitride and other tantalum compounds is low regardless of the concentration of the oxidizing agent. The pH can be adjusted by the amount of the acid added. It can also be adjusted by adding an alkali component such as ammonia, sodium hydroxide, or tetramethylammonium hydride.

The oxidizing agent concentration of the metal polishing slurry in the present invention is preferably 0.01 to 10% by weight, more preferably 0.01 to 3% by weight. The polishing rate of tantalum, a tantalum alloy, tantalum nitride, and other tantalum compounds serving as barrier layers reaches a maximum near 0.15% by weight. this is,
A primary oxide layer that is easily mechanically polished is formed on the surface of a conductive film such as tantalum, a tantalum alloy, tantalum nitride, or another tantalum compound by the oxidizing agent, and a high polishing rate can be obtained. On the other hand, the polishing rate of copper or a copper alloy increases as the concentration of the oxidizing agent increases. When the concentration of the oxidizing agent is in the range of 0.01 to 10% by weight, the polishing rate ratio of the barrier layer conductor to copper or copper alloy can be adjusted.
If the concentration of the oxidizing agent is greater than 10% by weight, the etching rate of copper or copper alloy is increased, and dishing or the like is likely to occur. In addition, as the oxidizing agent concentration increases, a secondary oxide layer, which is less polished than the primary oxide layer, is formed on the surface of a conductor film such as tantalum, a tantalum alloy, tantalum nitride, or another tantalum compound. Will decrease. Oxidant concentration is 0.01% by weight
If it is less than 10, the oxide layer is not sufficiently formed, so that the polishing rate of tantalum, a tantalum alloy, tantalum nitride, and other tantalum compounds is low, and the polishing rate of copper or a copper alloy is low.

The metal polishing slurry of the present invention may contain a water-soluble polymer. Since the water-soluble polymer is adsorbed on tantalum, a tantalum alloy, tantalum nitride or other tantalum compounds, or the oxide film surface thereof, the oxidizing agent concentration range in which a high polishing rate of these barrier layer conductor films can be obtained is reduced. . Further, since the water-soluble polymer is easily adsorbed on the surface of a nitride compound film such as a tantalum nitride film or titanium nitride, the polishing rate of the nitride compound film such as a tantalum nitride film or titanium nitride decreases. However, water-soluble polymers
Since it has an effect of forming a protective film on the surface of a metal, planarization characteristics such as dishing and thinning are improved.

Examples of the oxidizing agent for the conductor in the present invention include hydrogen peroxide (H ₂ O ₂ ), nitric acid, potassium periodate, hypochlorous acid, ozone water and the like. Of these, hydrogen peroxide is particularly preferred. . 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 acid in the present invention includes formic acid, acetic acid,
Propionic 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,
Examples thereof include citric acid and the like, and salts of these organic acids such as ammonium salt, sulfuric acid, nitric acid, ammonia and ammonium salts such as ammonium persulfate, ammonium nitrate, ammonium chloride, chromic acid and the like, and mixtures thereof. Among these, malonic acid, malic acid, tartaric acid, glycolic acid and citric acid are preferred in that a practical CMP polishing rate can be obtained.

The protective film forming agent in the present invention is a benzotriazole (BTA), a BTA derivative, for example, one obtained by substituting one hydrogen atom of the benzene ring of BTA with a methyl group (tolyltriazole) or substituting it with a carboxyl group or the like. (Methyl, ethyl, propyl, butyl and octyl esters of benzotriazole-4-carboxylic acid), or naphthotriazole, naphthotriazole derivatives and mixtures containing these.

As the water-soluble polymer in the present invention, those selected from the following groups are preferred, and polyacrylic acid, ammonium polyacrylate, sodium polyacrylate, polymethacrylic acid, polyammonium polymethacrylate are preferred. , Polymethacrylic acid sodium salt, a polymer having a carboxyl group-containing monomer such as polyacrylamide as a basic structural unit and a salt thereof, polyvinyl alcohol,
A polymer having a monomer having a vinyl group such as polyvinylpyrrolidone as a basic structural unit is exemplified. 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. By adding these water-soluble polymers, etching is suppressed by the synergistic effect with the protective film forming agent and the protective film forming effect of the water-soluble polymer, and the dishing characteristics can be greatly improved.

Abrasive grains may be added to the metal polishing liquid of the present invention. The abrasive grains may be any of inorganic abrasive grains such as silica, alumina, zirconia, ceria, titania, germania, and silicon carbide, and organic abrasive grains such as polystyrene, polyacryl, and polyvinyl chloride. Colloidal silica and colloidal alumina which have good stability, have a small number of polishing scratches (scratch) generated by CMP, and have an average particle diameter of 100 nm or less are preferable. 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 conductor film to which the present invention is applied is a copper or copper alloy barrier layer and is made of tantalum, a tantalum alloy, tantalum nitride, or another tantalum compound.

In the present invention, the compounding amount of the acid is determined by the total amount of the oxidizing agent for the conductor, the acid, the protective film forming agent, the water-soluble polymer and the water.
The amount is preferably 0.0001 to 0.05 mol, more preferably 0.001 to 0.01 mol, per 0 g. If the amount exceeds 0.05 mol, the etching of copper or copper alloy tends to increase.

The compounding amount of the protective film forming agent in the present invention is as follows:
The amount is preferably 0.0001 to 0.01 mol, more preferably 0.0005 to 0.005 mol, per 100 g of the total amount of the oxidizing agent, acid, protective film forming agent, water-soluble polymer and water. This compounding amount is 0.0001m
If the amount is less than 0.01 mol, the etching of copper or a copper alloy tends to increase, and if it exceeds 0.01 mol, the effect remains unchanged.

In the present invention, a water-soluble polymer can be added. The blending amount of the water-soluble polymer is based on 100 g of the total amount of the oxidizing agent, the acid, the protective film forming agent, the water-soluble polymer and water.
It is preferably 0.001 to 0.5% by weight,
It is more preferable that the content be 01 to 0.2% by weight. If the compounding amount is less than 0.001% by weight, the effect of using the protective film forming agent in combination tends not to be exhibited in suppressing etching,
If it exceeds 0.5% by weight, the polishing rate by CMP tends to decrease.

In the present invention, abrasive grains can be contained.
The amount of abrasive added is from 0.01% by weight to 10% by
%, More preferably in the range of 0.05% to 5% by weight. If the amount is less than 0.01% by weight, there is no effect of containing abrasive grains,
When the content exceeds 0% by weight, the polishing rate by CMP saturates, and no increase is observed even if the polishing rate is further increased.

[0026]

The present invention will be described below in detail with reference to examples. The present invention is not limited by these examples.

(Examples 1 to 10) (Preparation method of polishing liquid) Acid 0.4 parts by weight, water-soluble polymer 0.05 parts by weight, BTA 0.2 as protective film forming agent
98.85 parts by weight to 89.35 parts by weight of water (adjusted by the concentration of hydrogen peroxide, 98.9 parts by weight to 89.40 parts by weight when no water-soluble polymer is added) is added to and dissolved in parts by weight,
A solution obtained by adding 0.5 to 10 parts by weight of hydrogen peroxide (special grade reagent, 30% aqueous solution) was used as a metal polishing liquid. In the case of adding abrasive grains, 1 part by weight of colloidal silica having an average particle diameter of 20 nm produced by hydrolysis of tetraethoxysilane in an aqueous ammonia solution is added, and water is 97.85 parts by weight to 88.35 parts by weight. (Adjusted by the concentration of hydrogen peroxide, 97.9 parts by weight to 88.40 parts by weight when no water-soluble polymer is added). PKa of the acid used
Is 3.4 for malic acid and 3.7 for glycolic acid. In Examples 1 to 10, CMP was performed under the following polishing conditions using the above metal polishing slurry using the acid and water-soluble polymer shown in Table 1. (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. A 1-μm-thick copper film was formed. Silicon substrate Polishing pad: Foamed polyurethane resin having closed cells Polishing pressure: 250 gf / cm ² Relative speed between substrate and polishing platen: 18 m / min (Evaluation item of polishing product) Polishing speed by CMP: Film before and after CMP The thickness difference was determined by converting from the electric resistance value. Etching rate: The difference in copper film thickness before and after immersion in a stirred polishing liquid (room temperature, 25 ° C., stirring 100 rpm) was determined by converting from the electrical resistance value. Dicing 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. From the surface shape of the stripe pattern portion in which the wiring metal part width and the insulating film part width 100 μm are alternately arranged by a stylus type step meter,
The amount of film reduction of the wiring metal part relative to the insulating film part was determined. 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, a substrate sample was prepared so that the dishing amount measured in a state where the barrier layer was exposed on the insulating film portion was 50 nm, and two-stage polishing was performed until the insulating film portion had no barrier layer. Thinning amount: The surface shape of a 2.5-mm-wide stripe-shaped pattern portion formed by alternately arranging a wiring metal portion width of 45 μm and an insulating film portion width of 5 μm formed on the dishing amount evaluation substrate is measured by a stylus type profilometer. Then, the amount of film reduction of the insulating film portion near the center of the pattern with respect to the insulating film field portion around the stripe pattern was determined. After the first-stage polishing, the thinning amount measured with the barrier layer exposed on the insulating film portion was 2
A substrate sample was prepared so as to have a thickness of 0 nm, and polished in two steps until the barrier layer disappeared in the insulating film portion. Examples 1 to 10
Table 1 shows polishing rates and polishing rate ratios by CMP.
Table 2 shows the amount of dishing and the amount of thinning.

[0028]

[Table 1]

[0029]

[Table 2]

Examples 1 and 2 are examples in which abrasive grains and a water-soluble polymer are not blended. In Example 1, the hydrogen peroxide concentration was 0.1%.
5% by weight, and Example 2 is 3.0% by weight. When the concentration of the peroxide solution was high in Example 2, the polishing rate of copper was 7
It is 5.0 nm / min, which is suitable for polishing the copper layer that is left unpolished in the first step. Grooves were formed in the insulating layer of silicon dioxide, and when tantalum or tantalum nitride was used as a barrier layer to prevent copper diffusion, the concentration of hydrogen peroxide as an oxidizing agent was increased when a copper layer was provided on the surface. With the metal polishing liquid, the polishing rate of the copper layer is high, and the copper layer remaining in the first step can be polished in a short time. In the case where there was no copper layer polishing residue in the first step, the concentration of hydrogen peroxide as an oxidizing agent was reduced as a metal polishing liquid in Example 1.
When the polishing is performed, the polishing rate of copper is reduced, the polishing rate of tantalum or tantalum nitride is increased, and the barrier layer and the copper layer can be polished to substantially the same degree. If there is a polishing residue of copper on the barrier layer in the first step, the concentration of hydrogen peroxide is increased, and the polishing liquid is supplied by a pump or the like, and the polishing step of the copper is performed in the first step. When there is no residue, polishing may be performed by supplying a polishing solution having a low concentration of hydrogen peroxide by a pump or the like. Examples 3 to 5 are examples using abrasive grains. As in Examples 1 and 2 in which abrasive grains are not blended when the concentration of hydrogen peroxide as an oxidizing agent is high, the polishing rate of copper is high and a barrier layer is used. Is relatively low, and the uniformity after barrier layer polishing is also improved. When the concentration of hydrogen peroxide is low, the polishing rate of the barrier layer is high, the polishing rate of the copper layer is low, and there is a concentration at which the polishing rate of the barrier layer and the polishing rate of the copper layer are equal, and the barrier layer polishing without dishing is possible. . Examples 6 to 8 are examples in which a water-soluble polymer is blended, and the same tendency is observed. The dicing amount shown in Table 2 is the smallest and is excellent in Example 8, in which a water-soluble polymer is blended, as compared with Examples 2, 5, and 8 in which the concentration of hydrogen peroxide is 3.0% by weight. In any of the embodiments, the polishing rate of silicon dioxide as the insulating layer is lower than that of the metal layer, and the polishing can be reliably stopped near the upper surface of this layer.

[0031]

The polishing liquid for metals of the present invention has a pH of 3 or less, and can be used only as an oxidizing agent in a tantalum, a tantalum alloy, a tantalum nitride, another tantalum compound, or a tantalum compound used as a barrier layer conductor. By adjusting the polishing rate ratio with the polishing rate, it is possible to apply a polishing liquid having the same compounding component to all the processing locations where the barrier layer polishing is required, and to efficiently form a buried pattern of the metal film. be able to.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Tsuyoshi Uchida 48 Wadai, Tsukuba, Ibaraki Prefecture Within Hitachi Chemical Co., Ltd. In-house (72) Inventor Akiko Igarashi 48 Wadai, Tsukuba-shi, Ibaraki F-term (reference) at Hitachi Chemical Co., Ltd. 3C058 AA07 CA01 CB03 DA02 DA12

Claims (16)

[Claims] 1. A polishing liquid containing an oxidizing agent for a conductor, an agent for forming a protective film for a metal surface, an acid and water, having a pH of 3 or less, and polishing copper or a copper alloy and a barrier layer depending on the concentration of the oxidizing agent. A polishing liquid for metal, which adjusts a speed ratio. 2. An oxidizing agent having a concentration of 0.01 to 10% by weight.
The polishing liquid for metals according to claim 1, which is: 3. The method according to claim 1, further comprising a water-soluble polymer.
Alternatively, the metal polishing slurry according to claim 2. 4. The water-soluble polymer according to claim 3, 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. Polishing liquid for metals. 5. The metal polishing slurry according to claim 1, wherein the acid is an organic acid. 6. The metal polishing slurry according to claim 5, wherein the acid is at least one selected from malonic acid, malic acid, tartaric acid, glycolic acid and citric acid. 7. The metal-polishing liquid according to claim 1, wherein the protective film forming agent for the metal surface is at least one selected from benzotriazole (BTA) and its derivatives. 8. The conductor according to claim 1, wherein the oxidizing agent is at least one selected from hydrogen peroxide, nitric acid, potassium periodate, hypochlorous acid, and ozone water. Polishing liquid for metals. 9. The metal polishing liquid according to claim 1, wherein abrasive grains are added to the metal polishing liquid. 10. The abrasive grains are silica, alumina, ceria,
The metal polishing slurry according to claim 9, wherein the metal polishing slurry is at least one selected from titania, zirconia, and germania. 11. The metal polishing slurry according to claim 10, wherein the abrasive is colloidal silica or colloidal alumina having an average particle diameter of 100 nm or less. 12. The metal polishing slurry according to claim 1, wherein the conductor is a copper or copper alloy barrier layer. 13. The metal-polishing liquid according to claim 12, wherein the barrier layer is at least one selected from tantalum, tantalum nitride, a tantalum alloy, and other tantalum compounds. 14. A polishing rate ratio between a tantalum, a tantalum nitride and a silicon dioxide film (Ta / SiO ₂ , TaN / Si).
The metal polishing slurry according to any one of claims 1 to 13, wherein O ₂ ) is larger than 10. 15. A barrier layer comprising at least one selected from the group consisting of tantalum, tantalum nitride, a tantalum alloy and another tantalum compound, using the metal polishing liquid according to claim 1. Polishing method for polishing. 16. A polishing method for polishing a surface including copper or a copper alloy and a barrier layer thereof using the metal polishing liquid according to claim 1. Description: