KR20070017512A - Metal polishing liquid and polishing method using it - Google Patents

Abstract

In order to enable high flattening at a high Cu polishing rate and to reduce abrasive particles remaining on the surface to be polished after polishing, polishing of the metal polishing liquid as polishing liquid containing abrasive particles and chemical components A polishing liquid for metal containing abrasive particles having a charge of the surface potential equal to the charge of the surface potential of the reaction layer or the adsorption layer formed by the above chemical component or the mixed layer thereof to the target metal to be polished, and a polishing method using the same to provide.

Description

Metal polishing liquid and polishing method using the same {METAL POLISHING LIQUID AND POLISHING METHOD USING IT}

The present invention relates to a polishing liquid for metals and a polishing method using the same.

Recently, new microfabrication technologies 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 the interlayer insulating film, the metal plug formation, and the buried wiring formation in the LSI manufacturing process, especially in the multilayer wiring forming process ( See, eg, US Pat. No. 4,944,836.).

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 large machine method is mainly employed in which a copper alloy thin film is deposited and buried on an insulating film in which grooves are formed in advance, and a copper alloy thin film other than the groove portion is removed by CMP to form a buried wiring ( See, for example, Japanese Patent Laid-Open No. 2-278822.).

In general method of CMP of metal, a polishing pad is affixed on a circular polishing plate, the surface of the polishing pad is immersed in a polishing liquid for metal, and the surface on which the metal film of the substrate is formed is pressed, and a predetermined surface is applied from the back surface thereof. The polishing platen is turned in a state where a pressure (hereinafter referred to as polishing pressure) is applied to remove the metal film of the convex portion by mechanical friction between the polishing liquid and the convex portion of the metal film.

The polishing liquid for metal used for CMP generally consists of an oxidizing agent and abrasive grains, A metal oxide dissolving agent, a protective film forming agent, etc. are further added as needed. First, it is thought that the basic mechanism is to oxidize the surface of the metal film by oxidation and to scrape the oxide layer by abrasive particles. Since the oxide layer of the metal surface of the concave portion does not come into contact with the polishing pad so much that it does not have an effect of being scraped off by the abrasive particles, the metal layer of the convex portion is removed with the progress of CMP, and the substrate surface is flattened (for example, FB Kaufman et al., &Quot; See Chemical-Mechanical Polishing for Fabricating Patterned W Metal Features as Chip Interconnects, "Journal of The Electrochemical Society, Vol. 138, No. 11 (1991), pages 3460-3464.) .

However, in the case of forming a buried wiring by CMP using a conventional polishing liquid for metal containing abrasive grains, (1) the center portion of the surface of the buried metal wiring is isotropically polished and recessed like a dish. Deterioration in flatness, such as development (hereinafter referred to as dishing), phenomenon in which an interlayer insulating film is polished together with a wiring metal (hereinafter referred to as corrosion), or (2) on the substrate surface after polishing. Problems such as the complexity of the cleaning process for removing residual abrasive particles occur.

In order to solve the deterioration of flatness, to prevent dishing, corrosion, polishing damage and the like and to form a highly reliable LSI wiring, a protective film such as a metal oxide dissolving agent consisting of aminoacetic acid or amic sulfuric acid such as glycine and BTA (benzotriazole) A method of using a polishing liquid for metal containing a forming agent and the like have been proposed (see, for example, Japanese Patent Laid-Open No. 8-83780).

However, the solution of the deterioration of flatness due to the protective film forming effect such as BTA may not only reduce dishing and corrosion, but also significantly reduce the polishing rate, which is undesirable.

On the other hand, the removal of the abrasive grains adhered to the substrate by the CMP process is mainly performed by physical cleaning by PVA blush or ultrasonic waves. However, as the abrasive grains adhered to the substrate become finer, it becomes difficult to effectively exert a physical force on the abrasive grains.

As a solution for the cleaning of abrasive particles, removal of abrasive particles adhering to the substrate may be achieved by adding a surfactant to the cleaning liquid or by changing the pH of the cleaning liquid so that the potential of the abrasive particles and the substrate is the same. (See, for example, Japanese Patent Application Laid-Open No. 8-107094).

Disclosure of the Invention

As described above, since the protective film forming effect of BTA is considerably high, it tends to considerably reduce not only dishing and corrosion but also polishing rate. Therefore, there is a demand for a polishing liquid for metal that sufficiently reduces dishing and corrosion and does not lower the CMP rate.

Moreover, the addition of the said surfactant has a problem that surfactant may adhere to a board | substrate itself, and may become a pollution source, and also the effect may not be exhibited depending on the combination with the polishing liquid to be used.

The present invention provides a polishing liquid for metal and a polishing method using the same, which enable high flattening at a high Cu polishing rate.

The present invention also provides a polishing liquid for metal and a polishing method using the same, which enable the reduction of the abrasive grains remaining on the substrate surface after polishing.

The present invention is (1) a polishing liquid for metal containing abrasive particles and chemical components,

Polishing for metals containing abrasive particles having a charge of the surface potential equal to the surface potential of the reaction layer or the adsorption layer formed by the chemical component or the mixed layer thereof formed on the polished metal to be polished of the polishing liquid for metal; It is about liquid.

In addition, the present invention is (2) a polishing liquid for metal containing abrasive particles,

The electric charge of the surface potential of the said abrasive grain and the electric charge of the surface potential of the to-be-polished metal which are the grinding | polishing object of a metal polishing liquid are related with the same.

The present invention also relates to (3) the polishing liquid for metal of (1) above, wherein the product of the surface potential (mV) of the reaction layer or the adsorption layer or a mixed layer thereof and the surface potential (mV) of the abrasive grains is 1 to 10,000. .

The present invention also relates to (2) the polishing liquid for metal (2) above, wherein the product of the surface potential (mV) of the polished metal and the surface potential (mV) of the abrasive grains is 1 to 10000.

Moreover, this invention relates to the polishing liquid for metals in any one of said (1)-(4) whose primary particle diameter of (5) abrasive grain is 200 nm or less.

Moreover, this invention relates to the polishing liquid for metals in any one of said (1)-(5) with which (6) abrasive grains are aggregated and the secondary particle size with which the association was 200 nm or less.

Moreover, this invention relates to the said metal polishing liquid in any one of (1)-(6) whose compounding quantity of (7) abrasive grain is 0.001-10 weight%.

Moreover, this invention relates to the polishing liquid for metals in any one of said (1)-(7) whose (8) abrasive grain is at least one of colloidal silica and colloidal silicas.

Moreover, this invention relates to the metal polishing liquid in any one of said (1)-(8) whose pH of (9) metal polishing liquid is 2.0-7.0.

Moreover, this invention is the said (1)-(9) which is at least 1 sort (s) selected from the group which the to-be-polished metal which is a polishing object of the polishing liquid for metals consists of copper, a copper alloy, an oxide of copper, and an oxide of a copper alloy. It relates to a polishing liquid for any one of the metal).

In addition, the present invention provides the polishing table with the polishing cloth being pressed in the polishing cloth while supplying the polishing liquid for any one of the above (1) to (10) on the polishing cloth of the polishing table (11). A polishing method for polishing a polished film by moving a substrate relatively.

The polishing liquid for metals of the present invention and the polishing method using the same allow high leveling at high Cu polishing rate.

In addition, the polishing liquid for metal of the present invention and the polishing method using the same enable reduction of abrasive particles remaining on the polished surface after polishing.

To practice the invention  Best form for

The polishing liquid for metals which concerns on embodiment of this invention is demonstrated in detail.

One aspect of the polishing liquid for metal of the present invention is a polishing liquid for metal containing abrasive particles and chemical components,

The abrasive metal to be polished of the metal polishing liquid contains abrasive particles having a charge of the surface potential equal to that of the surface potential of the reaction layer, the adsorption layer, or the mixed layer formed by the chemical component.

Moreover, the chemical component in the polishing liquid for metals of this invention is a component which forms a reaction layer, an adsorption layer, or their mixed layer in the to-be-polished metal, Comprising: Components other than the abrasive grain which mainly act mechanically with respect to a to-be-polished metal. That is, it refers to a metal oxide solubilizer, a metal anticorrosive agent, an oxidizing agent, other additives, etc.

In addition, the reaction layer formed of a chemical component refers to the layer which the chemical component couple | bonded with the to-be-polished metal by covalent bond, coordination bond, ionic bond, etc. An adsorption layer refers to the layer which the chemical component adsorbed to the to-be-polished metal by physical adsorption, such as a hydrogen bond, van der Waals force, and electrostatic attraction. In the present invention, the surface potential refers to the ζ potential measured by the ζ potential measuring device. The surface potential of the to-be-polished metal, the surface layer of the reaction layer, or the adsorption layer, or the mixed layer thereof refers to the ζ potential obtained by measuring the oxide powder fine particles of the polished metal added to the polishing liquid for metal to which the abrasive grains were not added. For example, when the to-be-polished metal is Cu, copper (II) oxide powder is added to the polishing liquid for metals which does not contain abrasive grains, and the supernatant liquid is taken out and the ζ potential of copper oxide is measured. In addition, the surface potential of abrasive grains refers to the zeta potential obtained by measuring the said abrasive grain in the polishing liquid for metals.

Another aspect of the metal polishing liquid of the present invention is a metal polishing liquid containing abrasive particles, the charge of the surface potential of the abrasive particles and the surface potential of the polished metal to be polished of the metal polishing liquid. Is the same symbol.

The surface potential of a to-be-polished metal refers to the zeta potential obtained by measuring the oxide powder microparticles | fine-particles of the to-be-polished metal added to the polishing liquid for metals which do not add the abrasive grain.

It is preferable that the to-be-polished metal which is a grinding | polishing object of the metal polishing liquid is at least 1 sort (s) chosen from the group which consists of copper, a copper alloy, the oxide of copper, and the oxide of a copper alloy. In addition, tantalum, titanium, tungsten, these compounds, etc. are mentioned.

Examples of the abrasive particles include silica, alumina, titania, cerium oxide, and the like, and colloidal silica and / or colloidal silica are preferable. Furthermore, addition of trace metal species or surface modification to the abrasive grains may be used. There is no restriction | limiting in particular in the technique. In addition, the abrasive grains may be suitably selected by measuring the surface potential of the material as it is commercially available and choosing what to choose for the metal to be polished.

Here, colloidal silicas are based on colloidal silica and refer to the addition of a trace amount of metal species at the time of sol-gel reaction, the chemical modification of the surface silanol group, etc., and the like. Is not.

The product of the surface potential (mV) of the reaction layer or the adsorption layer or the mixed layer of the polished metal formed by the chemical component contained in the polishing liquid for metal required by the zeta potential measurement device (mV) Hereinafter, R * A) is preferably 1 to 10,000, more preferably 100 to 10,000, and particularly preferably 250 to 10,000.

In addition, the product (hereinafter referred to as R * A) of the surface potential (mV) of the polished metal to be polished and the surface potential (mV) of the abrasive grains to be polished for the metal polishing liquid required by the ζ potential measuring device is 1 to 10,000. It is preferable that it is, It is more preferable that it is 100-10,000, It is especially preferable that it is 250-10,000.

CMP is thought to form a reaction layer composed of a chemical component and the polished metal by the action of a chemical component on the surface of the polished metal, and to be softened and polished more smoothly. In order to obtain good flatness, it is preferable that the contact between the softly soft reaction layer and the abrasive grains is suppressed, but it is considered that addition of abrasive grains is preferable for stabilizing the polishing rate and the distribution of the polishing rate in the substrate plane.

In the present invention, by using the abrasive particles having the same potential as the reaction layer or the adsorption layer formed on the polished metal or their mixed layer, the contact between the reaction layer and the abrasive particles can be suppressed by the electrostatic repulsion force, and the addition of the abrasive particles It is thought that both the favorable polishing rate and the stabilization of the polishing rate distribution in the substrate surface can be achieved.

In addition, by using abrasive particles at the same potential as the reaction layer or the adsorption layer formed on the polished metal or their mixed layer, it is considered that the residual of abrasive particles on the substrate to be polished after the CMP treatment is suppressed by the electrostatic repulsion force.

It is preferable that the primary particle diameter of the said abrasive grain is 200 nm or less, It is more preferable that it is 5-200 nm, It is especially preferable that it is 5-150 nm, It is extremely preferable that it is 5-100 nm. When this primary particle size exceeds 200 nm, flatness tends to deteriorate.

In the case where the abrasive particles are associated, the secondary particle size is preferably 200 nm or less, more preferably 10 to 200 nm, particularly preferably 10 to 150 nm, and extremely preferably 10 to 100 nm. When this secondary particle diameter exceeds 200 nm, flatness will tend to deteriorate. In addition, when the secondary particle diameter of less than 10 nm is selected, care should be taken because the ability to remove the mechanical reaction layer by the abrasive particles may be insufficient and the CMP rate may be lowered.

The primary particle diameter of the abrasive grain in this invention is measured using a transmission electron microscope (For example, S4700 by the Hitachi Corporation make). In addition, a secondary particle diameter is measured using the optical diffraction scattering particle size distribution analyzer (for example, COULTER N4SD by COULTER Electronics).

It is preferable that the compounding quantity of the said abrasive grain in the polishing liquid for metals is 0.001-10 weight%, It is more preferable that it is 0.01-2.0 weight%, It is especially preferable that it is 0.02-1.0 weight%. If the blending amount is less than 0.001% by weight, the mechanical reaction layer removal ability by the abrasive particles is insufficient, and the CMP rate tends to be low, and when it exceeds 10% by weight, flatness tends to be deteriorated.

In addition, the compounding quantity of each chemical component and abrasive grain is the weight% with respect to the metal polishing liquid at the time of CMP use.

In the metal polishing liquid of the present invention, the flatness improvement and the detergency improvement are expected to be exhibited in the entire pH region of the metal polishing liquid, but the pH is preferably 2.0 to 7.0, more preferably 3.0 to 5.0. desirable.

As the oxidizing agent of the metal to be polished according to the present invention, hydrogen peroxide (H ₂ O _2), there may be mentioned nitric acid, and oxo acid, potassium persulfate, ammonium persulfate, hypochlorous acid, ozone water, etc. Among them, hydrogen peroxide is particularly preferred. When the substrate is a silicon substrate including an integrated circuit device, an alkali metal, an alkaline earth metal, or the like can be used. Although these can be used individually by 1 type or in combination of 2 or more types, since contamination by a halide etc. is not preferable, the oxidizing agent which does not contain a non volatile component is preferable. Especially, hydrogen peroxide is preferable from a stability viewpoint.

It is desired that the metal oxide solubilizer is water-soluble and is at least one selected from organic acids, organic acid esters, ammonium salts of organic acids and sulfuric acid. 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, glycerin acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimeric acid, maleic acid, phthalic acid, malic acid, tartaric acid, citric acid, asparagine , Aspartic acid, alanine, arginine, isoleucine, glycine, glutamine, glutamic acid, cystine, cysteine, serine, tyrosine, tryptophan, threonine, varine, histidine, hydroxyproline, hydroxylysine, phenylalanine, proline, methionine and lysine, leucine Salts such as ammonium salts of these organic acids, sulfuric acid, nitric acid, ammonia, ammonium salts such as ammonium persulfate, ammonium nitrate, ammonium chloride, chromic acid and the like, and mixtures thereof. Among them, formic acid, malonic acid, malic acid, tartaric acid, and citric acid are suitable for a laminated film containing at least one metal layer selected from copper, copper alloys and oxides of copper or copper alloys. These are preferable at the point that the balance with a protective film forming agent is easy to be obtained. In particular, it is preferable in terms of malic acid, tartaric acid, and citric acid in that the etching rate can be effectively suppressed while maintaining the practical CMP rate. These can be used individually by 1 type or in combination of 2 or more types.

The metal anticorrosive is preferably selected from the following groups, and ammonia such as ammonia, dimethylamine, trimethylamine, triethylamine, propylenediamine, ethylenediaminetetraacetic acid (EDTA), sodium diethyldithiocarbamate and chitosan And alkylamines, ditizone, loin (2,2'-biquinoline), neocuproin (2,9-dimethyl-1,10-phenanthroline), vasocuproin (2,9-dimethyl-4, Imines, such as 7-diphenyl-1,10-phenanthroline) and cupperazone (biscyclohexanone oxarylyldrazone); Benzimidazole-2-thiol, triazinedithiol, triazinetriol, 2- [2- (benzothiazolyl)] thiopropionic acid, 2- [2- (benzothiazolyl)] thiobutyl acid, 2-mercapto Benzothiazole), 1,2,3-triazole, 1,2,4-triazole, 3-amino-1H-1,2,4-triazole, bentriazole, 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-hexylbenzotriazole, [1,2,3-benzotriazole-1-methyl Azoles such as] [1,2,4-triazolyl-1-methyl] [2-ethylhexyl] amine, tolyltriazole, naphthotriazole, bis [(1-benzotriazolyl) methyl] phosphonic acid; Mercaptans such as nonyl mercaptan and dodecyl mercaptan; And glucose, cellulose and the like. Among them, benzotriazole, triazole and derivatives thereof are preferable for achieving both high polishing rate and low etching rate.

As another additive in this invention, 1 or more types of water-soluble polymers chosen from the following groups are used suitably. Polymers and salts thereof, which include monomers having carboxyl groups such as polyacrylic acid, polyammonium acrylate, polyacrylic acid sodium salt, polymethacrylic acid, polymethacrylic acid ammonium salt, polymethacrylic acid sodium salt and polyacrylamide as basic structural units, The group which consists of a polymer which has a monomer which has vinyl groups, such as polyvinyl alcohol and polyvinylpyrrolidone, as a basic structural unit is mentioned. However, when the substrate to be applied is a silicon substrate for a semiconductor integrated circuit or the like, contamination with alkali metals, alkaline earth metals, halides or the like is not preferable, and therefore an acid or an ammonium salt thereof is preferable. By adding these water-soluble polymers, a high polishing rate and good dishing can be obtained.

In the polishing method of the present invention, the polishing film is polished by relatively moving the polishing table and the substrate while pressing the substrate having the polishing film on the polishing cloth while supplying the polishing liquid for metal on the polishing cloth of the polishing table. Polishing method.

As a device for polishing, for example, a general polishing device having a plate on which a polishing cloth (pad) is attached, a motor capable of changing the rotation speed, etc., and a holder holding a substrate can be used. Although there is no restriction | limiting in particular as an abrasive cloth, General nonwoven fabric, foamed polyurethane, porous fluororesin, etc. can be used. There is no restriction | limiting in particular in grinding | polishing conditions, It is preferable to make the rotation speed of a surface plate into low rotation of 200 rpm or less so that a board | substrate may not protrude.

It is preferable that the polishing pressure of the board | substrate with a to-be-polished film to a polishing cloth is 5-100 kPa, and it is more preferable that it is 10-50 kPa from the viewpoint of the in-plane uniformity of a polishing rate, and the flatness of a pattern. While polishing, it is preferable to continuously supply a polishing liquid for metal 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 semiconductor substrate after completion | finish of grinding | polishing after wash | cleaning well in flowing water, after dropping the water droplet adhered on a board | substrate using a spin dryer etc.

It is preferable that the to-be-polished film is at least 1 sort (s) chosen from the group which consists of copper, a copper alloy, an oxide of copper, and an oxide of a copper alloy like the above-mentioned to-be-polished metal. In addition, tantalum, titanium, tungsten, these compounds, etc. are mentioned.

The metal polishing liquid and the polishing method of the present invention can be applied to, for example, an LSI manufacturing step. In particular, in a multilayer wiring forming step, a wiring material such as a copper alloy thin film on a substrate can be polished to form a wiring. have. It can also be used for polishing substrates such as magnetic heads.

1 shows the polishing rates (left axis, solid line) and dishing (right axis, dashed line) and R * A (surface potentials of the polished metal and abrasive grains) of Examples 1, 2 and Comparative Example 1; It is a graph showing the relationship with the product of mV).

<Example>

Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples.

(Examples 1 to 4 and Comparative Example 1: Polishing Liquid 1 for Metals)

The used polishing liquid 1 for metals includes 1 wt% or less of an organic acid (metal oxide dissolving agent), 0.5 wt% or less of a nitrogen-containing cyclic compound (metal anticorrosive agent), 2 wt% or less of a water-soluble polymer (additive), 10 It contains up to weight percent hydrogen peroxide (oxidizing agent) and water. In addition, the abrasive grains of Table 1, wherein the primary particle diameters are in the range of the average value ± 10% of Table 1 and the secondary particle diameters of the average value +/- 15% of Table 1, and the surface potentials are different, respectively, It was added to the liquid 1.

In Examples 1 to 4 and Comparative Example 1, the substrate to be polished was subjected to CMP under the following polishing conditions, using the above polishing liquid 1 for metal to which abrasive grains having different surface potentials were added.

Example 5 and Comparative Example 2: Polishing Liquid 2 for Metals

The used polishing liquid for metal 2 was 0.5 wt% or less of a metal oxide solubilizer, 0.3 wt% or less of a nitrogen-containing cyclic compound (metal anticorrosive), 0.5 wt% or less of a water-soluble polymer (additive), and 10 wt% It contains up to% hydrogen peroxide (oxidizing agent) and water. Further, abrasive particles of Table 1 having primary particle diameters in the range of the average value ± 10% of Table 1 and secondary particle diameters of the average value +/- 15% of Table 1, and different surface potentials were added to the polishing liquid for metal. Added to 2.

In Example 5 and Comparative Example 2, CMP was carried out under the following polishing conditions using the above-described polishing liquid 2 for metal to which abrasive grains having different surface potentials were added.

Example 6 and Comparative Example 3 Polishing Liquid 3 for Metals

The used polishing liquid 3 for metal contains 1 wt% or less of an organic acid (metal oxide dissolving agent), 2 wt% or less of a water-soluble polymer (additive), 10 wt% or less of hydrogen peroxide (oxidizing agent), and water. In addition, abrasive grains having a primary particle diameter of ± 10% in Table 1 and secondary particle diameters in an average value of ± 15% in Table 1 and having different surface potentials were added to the polishing liquid 3 for metal. did.

In Example 6 and Comparative Example 3, the substrate to be polished was subjected to CMP under the following polishing conditions, using the polishing liquid 3 for metal to which the abrasive grains described in Table 1 having different surface potentials were added.

(Measurement of surface potential)

In the present invention, the surface potential (hereinafter referred to as ζ potential of the polished metal) of the reaction layer or the adsorption layer or the mixed layer formed on the polished metal by a chemical component, and the surface potential of the abrasive grain in the polishing liquid. Was measured by the following ζ potential measuring device using the laser Doppler method as the measuring principle. The measurement of the ζ potential of the to-be-polished metal whose Cu to be polished metal was measured by adding 1% by weight of copper (II) oxide powder (manufactured by Kanto Chemical Co., Ltd.) to a polishing liquid for metal not containing abrasive particles. The supernatant was collected by a pipette, and 5 milliliters were injected into the measuring cell using a syringe to measure the ζ potential of copper oxide. The surface potential of the abrasive grains (hereinafter also referred to as the zeta potential of the abrasive grains) was measured for the zeta potential in a state in which the polishing liquid for metal was contained in the compounding amount shown in Table 1.

Measuring device: ZETASIZER3000HS (made by MALVERN)

Measurement condition: temperature 25 ℃

         Refractive Index of Dispersant 1.331

         Viscosity of Dispersion Medium 0.893 cP

(Measuring method of polishing particle size)

The primary particle size of the abrasive grains used in the present invention was measured to be 10 to 500,000 times by drying the polishing liquid so as not to cause aggregation on the micromesh using a transmission electron microscope (S4700 manufactured by Hitachi, Ltd.). The secondary particles of the abrasive grains had an intensity (equivalent to scattering intensity and turbidity) of 5E + 04 to 4E + 05 at a measurement temperature of 20 ° C. using an optical diffraction scattering particle size distribution system (COULTER N4SD manufactured by COULTER Electronics). When it adjusted to the range and when intensity | strength was too strong, it diluted with pure water, measured 5 times, and calculated | required the average value of the Unimodal value. Moreover, solvent refractive index: 1.333 (water), particle refractive index setting: unknown, solvent viscosity: 1.005 cps (water), Run time: 200 sec, laser incidence angle: 90 degrees were performed.

(Substrate for polishing with copper wiring)

In the evaluation of dishing, a 25 nm TaN film and a 10 nm Cu film were formed on the surface of a substrate made of silicon with an insulating layer having a groove formed with a depth of 500 nm by a sputtering method, followed by deposition of 1.2 µm Cu by electroplating. A substrate for polishing (SEMATECH854 wafer) was used. Cu polishing speed was calculated | required from the initial film thickness and polishing time of the to-be-polished board | substrate.

(Polishing condition)

Polishing pad: IC-1400 (Rodel Corporation)

Polishing pressure: 13.8kPa

Polishing liquid supply amount: 200 ml

(CMP post-cleaning)

After the CMP treatment, washing was performed with PVA blush and ultrasonic water, followed by drying with a spin dryer.

(Evaluation items)

Cu polishing rate: The film thickness difference before and after CMP of a copper film was calculated | required in conversion from the electrical resistance value.

Dicing: The evaluation of dishing was performed by scanning 100 micrometers of wiring width and 100 micrometers of wiring space width | varieties with the contact type | difference stepmeter (DECKTAK V200-Si by Veeco).

Residual particle count: The residual abrasive grains on the polishing substrate were measured using Surfscan 6220 manufactured by KLA Tencol.

The presence of polishing damage was confirmed by visual observation, optical microscope observation, and electron microscope observation of the substrate after CMP. As a result, no occurrence of polishing damage was found.

Table 1 shows the evaluation results of the Cu polishing rate, dishing and the number of residual particles in Examples 1 to 6 and Comparative Examples 1 to 3.

Example 1 shows that, while Comparative Example 1 having substantially the same abrasive grain diameter and the surface potential of the abrasive grains added the abrasive grains and the abrasive grains having different signs, the dishing rate was substantially reduced while the dishing was greatly reduced. Able to know. In Example 2, particles having substantially the same abrasive grain diameter as in Example 1 and having a surface potential of the abrasive grains larger than those in Example 1 were added. Compared with Example 1, it turns out that dishing improves. Example 3 selects titania as abrasive grains. It can be seen that dishing is good regardless of the abrasive grain species. As shown in Example 4, when the primary particle size and the secondary particle size of the abrasive grains are large, it can be seen that attention is required because dishing tends to deteriorate. It can be seen from Example 5 and Comparative Example 2 that the effect is exhibited without depending on the pH. Example 6 remove | excluding metal anticorrosive agent from the chemical component of Examples 1-5. The polishing rate and the dishing are increased from not containing the metal anticorrosive agent, but it can be seen that the dishing is improved with respect to Comparative Example 3 having the same chemical composition as in Example 6. It can be seen from Examples 1 to 6 and Comparative Examples 1 to 3 that the number of residual particles decreases as the R? A of the ζ potential of the polished metal and the polished?

1, the graph which plotted the grinding | polishing rate and dishing of Example 1, Example 2, and Comparative Example 1 in relation to R * A is shown.

As apparent from Fig. 1, it can be seen that dishing decreases as the value of R * A increases. On the other hand, a clear decrease in Cu polishing rate is not found. In other words, it is understood that by increasing the value of R * A, the Cu polishing rate can be maintained and the dishing can be reduced.

In addition, in this embodiment, since the sign of the surface potential of the polished metal is negative, abrasive grains showing the sign of the negative surface potential are used. However, if the sign of the surface potential of the polished metal is positive, the positive surface is positive. It is thought that the effect of this invention is acquired when using the abrasive grain which shows the sign of electric potential.

The polishing liquid for metals of the present invention and the polishing method using the same allow high leveling at high Cu polishing rate.

In addition, the polishing liquid for metal of the present invention and the polishing method using the same enable reduction of abrasive grains remaining on the polished surface after polishing.

Claims (11)

A polishing liquid for metal containing abrasive particles and chemical components, Polishing for metals containing abrasive particles having a charge of the surface potential equal to the surface potential of the reaction layer or the adsorption layer formed by the chemical component or the mixed layer thereof formed on the polished metal to be polished of the polishing liquid for metal; liquid. As a polishing liquid for metals containing abrasive particles, The polishing liquid for metal whose electric charge of the surface potential of the said abrasive grain and the surface potential of the to-be-polished metal which are the grinding | polishing object of a metal polishing liquid are the same code | symbol. The polishing liquid for metal according to claim 1, wherein a product of the surface potential (mV) of the reaction layer or the adsorption layer or a mixed layer thereof and the surface potential (mV) of the abrasive grains is 1 to 10000. The polishing liquid for metal according to claim 2, wherein the product of the surface potential (mV) of the polished metal and the surface potential (mV) of the abrasive grain is 1 to 10000. The polishing liquid for metal according to any one of claims 1 to 4, wherein the primary particle diameter of the abrasive grain is 200 nm or less. The polishing liquid for metals according to any one of claims 1 to 5, wherein the abrasive particles are associated with each other, and the secondary particle diameters associated with them are 200 nm or less. The polishing liquid for metal according to any one of claims 1 to 6, wherein the compounding amount of the abrasive grain is 0.001 to 10% by weight. The polishing liquid for metal according to any one of claims 1 to 7, wherein the abrasive grain is at least one of colloidal silica and colloidal silica. The polishing liquid for metal according to any one of claims 1 to 8, wherein the pH is 2.0 to 7.0. The metal for polishing according to any one of claims 1 to 9, wherein the metal to be polished of the polishing liquid for metal is at least one selected from the group consisting of copper, copper alloys, oxides of copper and oxides of copper alloys. Polishing liquid. By supplying the polishing liquid for metal according to any one of claims 1 to 10 on the polishing cloth of the polishing table, by moving the polishing table and the substrate relative to each other while pressing the substrate having the polishing film on the polishing cloth. Polishing method for polishing the polishing film.

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