JP2011165759A - Cmp polishing liquid, and polishing method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a CMP polishing liquid that further improves the polishing speed of at least a palladium layer compared with that when using the conventional polishing liquid, and a polishing method. <P>SOLUTION: The CMP polishing liquid contains: abrasive grains having an anionic functional group; 1, 2, 4-triazole; phosphoric acids; an oxidizing agent; and water. The pH of the CMP polishing liquid is ≤7. The polishing method includes a step for polishing a palladium layer by a polishing cloth while supplying the CMP polishing liquid between a substrate, having the palladium layer formed on at least one surface, and the polishing cloth. The CMP polishing liquid contains: abrasive grains having an anionic functional group; 1, 2, 4-triazole; phosphoric acids; an oxidizing agent; and water. The pH of the CMP polishing liquid is ≤7. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a CMP polishing liquid and a polishing method using the CMP polishing liquid.

  In recent years, new microfabrication techniques have been developed along with higher integration and higher performance of semiconductor integrated circuits (LSIs). The chemical mechanical polishing (CMP) method is one of them, and it is a technique frequently used in planarization of an interlayer insulating film layer, metal plug formation, and embedded wiring formation in an LSI manufacturing process, particularly in a multilayer wiring forming process. (For example, refer to Patent Document 1).

  The metal polishing liquid used in CMP generally has an oxidizing agent and solid abrasive grains, and a metal oxide dissolving agent and a protective film forming agent (metal anticorrosive) are further added as necessary. It is considered that the basic mechanism of polishing is to first oxidize the surface of the metal layer with an oxidizing agent to form an oxide layer, and then to scrape off the oxide layer with solid abrasive grains.

  The oxide layer on the gold layer deposited on the groove (concave) does not touch the polishing cloth (polishing pad) so much that it does not have the effect of scraping with solid abrasive grains, but the metal deposited on the convex part that touches the polishing cloth. In the oxide layer on the surface of the layer, scraping proceeds. Therefore, as the CMP progresses, the metal layer on the convex portion is removed and the substrate surface is flattened (for example, see Non-Patent Document 1).

  On the other hand, with higher integration of semiconductor elements, there are demands for higher pin count, narrower pitch, and thinner mounting. Furthermore, wiring delay and noise prevention between the semiconductor element and the wiring board are also important issues. For this reason, a flip chip mounting method has been widely adopted as a connection method between a semiconductor element and a wiring board instead of a conventional mounting method mainly using wire bonding.

  In this flip chip mounting method, there is a wide solder bump connection method in which a protruding electrode is formed on an electrode terminal of a semiconductor element and bonded together to a connection terminal formed on the wiring board via the protruding electrode. in use.

  As a CMP polishing liquid, a polishing liquid to which a layer made of titanium nitride or tantalum nitride formed on a substrate is to be polished is known, and a protective film forming agent and an organic acid are added (for example, Patent Documents). 2).

  Further, as an attempt to apply CMP to a layer made of copper, for example, a method using a polishing liquid to which 2-quinolinecarboxylic acid is added is known (for example, see Patent Document 3). Further, as an attempt to apply CMP to the nickel layer, for example, a method using a polishing liquid to which abrasive grains, an organic acid, and an oxidizing agent are added is known as a polishing liquid for an HDD magnetic head (see, for example, Patent Document 4).

  By the way, palladium is generally classified as “noble metal” together with platinum, ruthenium and the like. Attempts to apply CMP to such a noble metal layer include, for example, a polishing liquid to which a sulfur compound is added, a polishing liquid to which a diketone, a nitrogen-containing heterocyclic compound, or a zwitterionic compound is added, or a platinum group metal. A method using a polishing liquid to which an oxide is added is known (see, for example, Patent Documents 5, 6, and 7).

U.S. Pat. No. 4,944,836 Japanese Patent No. 3780767 Japanese Patent No. 3192968 JP 2006-297501 A International Publication No. 01/44396 Pamphlet US Pat. No. 6,527,622 Japanese Patent Laid-Open No. 11-121411

Journal of Electrochemical Society, Vol.138, No.11 (1991), 3460-3464

  However, until now, no study has been made of polishing palladium by CMP. According to the knowledge of the present inventors, the polishing liquids of Patent Documents 2, 3, and 4 cannot easily oxidize palladium having high hardness. In addition, in the polishing liquids of Patent Documents 5, 6, and 7, platinum and ruthenium can be polished. However, it has been found that polishing does not proceed even when palladium is polished with the same polishing liquid.

  Accordingly, an object of the present invention is to provide a CMP polishing liquid capable of improving the polishing rate of at least the palladium layer as compared with the case where a conventional polishing liquid is used, and a polishing method using the CMP polishing liquid. To do.

  The present inventors have found that a CMP polishing liquid containing 1,2,4-triazole can efficiently polish a palladium layer. And this invention discovered that the grinding | polishing rate of a palladium layer improved further, when using the abrasive grain modified with the anionic functional group.

  Specifically, the present invention relates to CMP polishing comprising an abrasive having an anionic functional group, 1,2,4-triazole, phosphoric acids, an oxidizing agent, and water, and having a pH of 7 or less. Regarding liquids.

  According to the CMP polishing liquid of the present invention, at least the palladium layer polishing rate can be improved and polishing can be performed at a desired polishing rate, compared to the case of using a conventional polishing liquid. Such a CMP polishing liquid of the present invention is useful as a CMP polishing liquid for palladium polishing.

  The abrasive preferably has at least one selected from an aluminate group, a sulfonic acid group, a carboxylic acid group, a nitric acid group, a phosphoric acid group, a carbonic acid group and an iodic acid group as an anionic functional group. In this case, a better polishing rate for the palladium layer can be obtained.

  In addition, the present inventors use the abrasive grains having a predetermined particle diameter after being modified with an anionic functional group, and thus the effect of the anionic functional group (anionic substituent) appears remarkably. It has been found that the polishing rate of the layer can be further improved. That is, the average secondary particle diameter of the abrasive grains is preferably 60 nm or more.

  The degree of association of the abrasive grains is preferably 1.7 to 2.3. In this case, the polishing rate of the palladium layer can be further improved.

  The CMP polishing liquid preferably contains abrasive grains made of at least one selected from alumina, silica, zirconia, titania and ceria as abrasive grains. In this case, the polishing rate of the palladium layer can be further improved.

  The content of the abrasive grains is preferably 0.1 to 10% by mass based on the total mass of the CMP polishing liquid. By setting the content of the abrasive grains in the CMP polishing liquid within this range, it is possible to keep the scraping action and at the same time suppress the particles from aggregating and settling.

  The CMP polishing liquid preferably contains at least one selected from hydrogen peroxide, periodic acid, periodate, iodate, bromate and persulfate as an oxidizing agent. In this case, the polishing rate of the palladium layer can be further improved.

  The present invention further includes a step of polishing the palladium layer with the polishing cloth while supplying the CMP polishing liquid between the substrate having the palladium layer formed on at least one surface and the polishing cloth, The present invention relates to a polishing method comprising abrasive grains having an anionic functional group, 1,2,4-triazole, phosphoric acids, an oxidizing agent, and water, and a CMP polishing solution having a pH of 7 or less. According to such a polishing method, at least the polishing rate of the palladium layer can be improved as compared with the case where a conventional polishing liquid is used.

  According to the CMP polishing liquid and the polishing method using the CMP polishing liquid of the present invention, it becomes possible to efficiently polish a substrate having a palladium layer, which has been difficult to polish with a conventionally known metal polishing liquid. . Thereby, the polishing rate of at least the palladium layer can be improved and polishing can be performed at a desired polishing rate as compared with the case where a conventional polishing liquid is used.

It is sectional drawing which shows 1st Embodiment of the manufacturing method of the board | substrate which has a protruding electrode. It is sectional drawing which shows 2nd Embodiment of the manufacturing method of the board | substrate which has a protruding electrode. It is sectional drawing which shows 3rd Embodiment of the manufacturing method of the board | substrate which has a protruding electrode. It is sectional drawing which shows the specific example of 3rd Embodiment of the manufacturing method of the board | substrate which has a protruding electrode.

  Hereinafter, embodiments for carrying out the present invention will be described in detail. The CMP polishing liquid of this embodiment comprises abrasive grains modified with an anionic functional group (hereinafter sometimes referred to as “anion-modified abrasive grains”), 1,2,4-triazole, phosphoric acids, oxidizing agent and water. Contains at least.

(Anion-modified abrasive)
The CMP polishing liquid of this embodiment contains anion-modified abrasive grains. Unlike normal abrasive grains, the surface of anion-modified abrasive grains is anion-treated. By using such abrasive grains, the polishing rate of the palladium layer can be improved.

  The reason for this is not known in detail, but the present inventors consider as follows. That is, some “reaction layer” is formed on the palladium surface by the action of the components contained in the CMP polishing liquid of this embodiment. For example, since the zeta potential of palladium acetate is 23.7 mV and the zeta potential of palladium oxide is 21.7 mV (both measured by the present inventor), the “reaction layer” is considered to be “cationic”. It is done. Therefore, an anion treatment is applied to the abrasive grain surface to make the abrasive grain surface easy to form negative ions. Preferably, the abrasive grain surface is made anionic so that the abrasive grain is brought into contact with the palladium surface by electrostatic attraction. The frequency is likely to increase and the polishing rate tends to improve.

  In this embodiment, “anion treatment” means a treatment for imparting a structure that easily forms negative ions in the acidic or neutral region to the surface of the abrasive grains. In another aspect, in a CMP polishing liquid having a pH of 7 or less, it means a process of adding anion species to the abrasive grains so that the zeta potential of the abrasive grains changes in the negative direction.

  Specific examples of the abrasive grains include alumina (fumed alumina, transition alumina, colloidal alumina), silica (fumed silica, colloidal silica), zirconia, titania, ceria, and the like. Dola alumina, transition alumina, fumed silica, colloidal silica, and colloidal alumina are preferable, and colloidal silica and colloidal alumina are more preferable in that generation of polishing scratches can be suppressed while maintaining a high polishing rate.

The anion treatment will be described by taking as an example the case where silica is used as abrasive grains. Silica is SiO ₂ in general formula, but some silanol groups (Si—OH groups) are present at the terminal (surface). Since the hydrogen atom in the silanol group hardly dissociates in the acidic region, ordinary silica particles exhibit a zeta potential close to plus or zero in the acidic region. Here, by reacting the silanol group with an anionic species, silica particles having a group that is more likely to generate negative ions than the silanol group can be obtained on the surface.

Examples of such anionic species include aluminum compounds such as potassium aluminate [(AlO (OH) ₂ K], etc. More specifically, for example, the above-mentioned aluminate in a colloidal silica solution. By adding potassium and refluxing at 60 ° C. or higher, the silanol group can be converted into a “—Si—O—Al (OH) ₂ ” group that is more easily ionized.

  Specific examples of the anionic functional group to be modified include an aluminate group, a sulfonic acid group, a carboxylic acid group, a nitric acid group, a phosphoric acid group, a carbonic acid group, and an iodic acid group. An aluminate group, a nitric acid group, and a carboxylic acid group are preferable, and a sulfonic acid group, an aluminate group, and a nitric acid group are more preferable in that the polishing rate can be further improved.

  Examples of the sulfonic acid group include a sulfo group. The anionic species can be obtained by using, for example, sodium sulfonate. Examples of the carboxylic acid group include a carboxyl group, and the anionic species can be obtained by using, for example, formic acid, acetic acid, propionic acid and the like. The nitrate group can be obtained by using, for example, calcium nitrate as the anionic species. The phosphate group can be obtained by using, for example, trisodium phosphate as the anionic species. A carbonate group can be obtained by using, for example, magnesium carbonate as an anionic species. As an iodate group, an iodine group is mentioned, for example, It can obtain by using, for example, potassium iodate as an anionic species.

  Further, the zeta potential on the abrasive grain surface can be used as an indicator of the degree of anion modification. When anion modification is performed, the zeta potential on the abrasive grain surface changes in the negative direction. When the zeta potential is negative, the effect of improving the polishing rate of the palladium layer becomes higher when compared with abrasive grains having the same average secondary particle diameter. Therefore, it is preferable that the absolute value of the zeta potential is large.

  The zeta potential of the abrasive grain surface is preferably smaller than −2 mV, more preferably smaller than −5 mV, and even smaller than −10 mV in the CMP polishing liquid (in particular, CMP polishing liquid having a pH of 1 to 7). preferable. When the zeta potential is smaller than −2 mV, the contact frequency between the abrasive grains and the palladium surface is further increased, and the effect of improving the palladium polishing rate can be significantly obtained by using the anion-modified abrasive grains.

  “Zeta potential” means the surface charge of the abrasive grain surface dispersed in the polishing liquid. Specifically, the zeta potential is obtained as a value measured using a zeta potential measuring device “Zetasizer 3000 HSA (trade name)” manufactured by Marvern Instruments.

  The abrasive grains used in the CMP polishing liquid of this embodiment preferably have an average secondary particle diameter of 60 nm or more. By using such abrasive grains, the effect of improving the palladium polishing rate can be significantly obtained by using anion-modified abrasive grains.

  As described above, since the reaction layer formed on the palladium surface is considered to be cationic, the use of anion-modified abrasive grains increases the contact frequency between the abrasive grains and the palladium surface and improves the polishing rate. It is thought that there is a tendency to. When the average secondary particle diameter is 60 nm or more, such a phenomenon tends to occur remarkably, but the detailed mechanism is not well understood. In this respect, the average secondary particle diameter is more preferably 62 nm or more, still more preferably 64 nm or more, and extremely preferably 66 nm or more. The average secondary particle size is preferably 150 nm or less, more preferably 140 nm or less, because the polishing rate of the palladium layer tends to be further improved.

  The “average secondary particle diameter” was obtained from the measurement result obtained by measuring the particle diameter of the abrasive grains of the sample in which the abrasive grains were dispersed in water using a dynamic light scattering particle size distribution meter. Mean average particle size. The average secondary particle diameter is specifically obtained by the method shown below. First, 50 ml of 0.3% citric acid aqueous solution is added to 4 g of sample, and the sample shaken lightly is used as a measurement sample. A value obtained by measuring this sample using ELS-8000 manufactured by Otsuka Electronics Co., Ltd. is defined as an average secondary particle size.

  The degree of association of the abrasive grains (value obtained by dividing the average secondary particle diameter by the average primary particle diameter) is preferably 1.7 to 2.3. When the degree of association is in this range, a remarkable effect of improving the polishing rate can be obtained by using anion-modified abrasive grains. In view of the above, the lower limit value of the degree of association is more preferably 1.8, still more preferably 1.9, the upper limit value is more preferably 2.2, and even more preferably 2.1.

The “average primary particle diameter” of the abrasive grains in the CMP polishing liquid necessary for determining the degree of association refers to the average diameter of the particles that can be calculated from the BET specific surface area. From the measurement of the surface area (hereinafter the same), it is calculated by the following equation (1).
D1 = 6 / (ρ × V) (1)
In the formula (1), D1 represents an average primary particle diameter (unit: m), ρ represents particle density (unit: kg / m ³ ), and V represents a BET specific surface area (unit: m ² / g).

More specifically, the abrasive grains are first dried with a vacuum freeze dryer, and the residue is finely crushed with a mortar (magnetic, 100 ml) to obtain a measurement sample, which is a BET specific surface area made by Yuasa Ionics Co., Ltd. The BET specific surface area V is measured using a measuring device (trade name: Autosorb 6), and the average primary particle diameter D1 is calculated.
When the particles are colloidal silica, the density ρ of the particles is “ρ = 2200 (kg / m ³ )”. Therefore, the average primary particle diameter D1 can be obtained by substituting the BET specific surface area V (m ² / g) into the following formula (2).
D1 = 2.727 × 10 ⁻⁶ / V (m)
= 2727 / V (nm) (2)

  The content of the abrasive grains is preferably 0.1 to 10% by mass, more preferably 0.2 to 8.0% by mass based on the total mass of the CMP polishing liquid. When the content is 0.1% by mass or more, a physical scraping action can be obtained, and the polishing rate by CMP tends to be further increased. Moreover, if it is 10 mass% or less, it exists in the tendency which can suppress that a particle | grain coagulates and settles, and there exists a tendency for the increase in the grinding | polishing rate corresponding to content to be acquired. Such a tendency tends to be more noticeable with respect to the polishing rate of the palladium layer.

(1,2,4-triazole)
The CMP polishing liquid contains 1,2,4-triazole. 1,2,4-Triazole is considered to form a complex with palladium together with phosphoric acid to be described later, and it is estimated that a good polishing rate can be obtained because the complex formed here is easily polished. . Further, it is considered that a nitrogen-containing compound can form a complex with palladium. However, according to the study by the present inventors, a compound other than 1,2,4-triazole can improve the polishing rate of the palladium layer. I know I can't. For example, with 1,2,3-triazole having a structure similar to that of 1,2,4-triazole and 3-amino-1,2,4-triazole, it is difficult to obtain a good polishing rate for the palladium layer.

  The content of 1,2,4-triazole is preferably 0.001 to 20% by mass based on the total mass of the CMP polishing liquid. If this content is 0.001% by mass or more, the polishing rate of the palladium layer tends to be further increased, and the lower limit of the content is more preferably 0.01% by mass, and 0.05% by mass. % Is more preferable. Moreover, if content is 20 mass% or less, there exists a tendency which can suppress that the grinding | polishing rate of a palladium layer is saturated with respect to content, and the upper limit of content is more than 15 mass%. It is preferably 12% by mass, more preferably 10% by mass.

(Phosphoric acids)
The CMP polishing liquid contains phosphoric acids. Phosphoric acids are thought to promote the polishing of the metal film by complexing and / or dissolving the metal oxidized by the oxidizing agent described later, and are presumed to have a function as a metal oxide dissolving agent for palladium. .

  As the compound having a function as a metal oxide solubilizer for palladium, various inorganic acids, organic acids, and the like can be considered, but according to the study by the present inventors, good polishing against palladium is possible with acids other than phosphoric acids. Getting speed is difficult.

  Phosphoric acids mean phosphoric acid, phosphorous acid and hypophosphorous acid, and their condensates (including salts). Examples of phosphoric acids include phosphoric acid, phosphorous acid, hypophosphorous acid, pyrophosphoric acid, pyrophosphorous acid, trimetaphosphoric acid, tetrametaphosphoric acid, hexametaphosphoric acid, polyphosphoric acid, tripolyphosphoric acid, and other condensed phosphoric acids. And the like. These phosphoric acids may be used alone or in combination of two or more.

  An example of a salt of phosphoric acid is a salt of an anion and a cation of phosphoric acid. Examples of phosphoric acid anions include phosphate ion, phosphite ion, hypophosphite ion, pyrophosphate ion, pyrophosphite ion, trimetaphosphate ion, tetrametaphosphate ion, hexametaphosphate ion, polyphosphate Examples thereof include ions, tripolyphosphate ions, and other condensed phosphate ions. Examples of cations include lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, barium, titanium, zirconium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, silver, palladium, zinc And ions of aluminum, gallium, tin, ammonium and the like. These salts are either a first salt having one metal and two hydrogens in the molecule, a second salt having two metals and one hydrogen, or a third salt having three metals. Any of acid salts, alkaline salts and neutral salts may be used.

  The phosphoric acid content is preferably 0.001 to 20% by mass based on the total mass of the CMP polishing liquid. If the content is 0.001% by mass or more, the polishing rate of the palladium layer tends to be further increased, and the lower limit of the content is more preferably 0.01% by mass, and 0.02% by mass. % Is more preferable. Moreover, if content is 20 mass% or less, there exists a tendency which can suppress that the grinding | polishing rate of a palladium layer is saturated with respect to content, and the upper limit of content is more than 15 mass%. Preferably, it is 10 mass%. In addition, when the substrate having a nickel layer, a base metal layer or the like in addition to the palladium layer as described later is polished, the above content is preferable.

(Oxidant)
The oxidizing agent contained in the CMP polishing liquid is an oxidizing agent for the metal used for the substrate for layer formation or the like. Examples of the oxidizing agent include hydrogen peroxide (H ₂ O ₂ ), periodic acid, periodate, iodate, bromate, persulfate, etc. Among them, hydrogen peroxide is particularly preferable. These can be used individually by 1 type or in mixture of 2 or more types.

  The content of the oxidizing agent is preferably 0.05 to 20% by mass, more preferably 0.1 to 15% by mass based on the total mass of the CMP polishing liquid, and 0.1 to 10% by mass. More preferably it is. If the content is 0.05% by mass or more, metal oxidation is sufficient and the polishing rate of the palladium layer tends to be further increased. If the content is 20% by mass or less, the polished surface is less likely to be roughened. There is. Hydrogen peroxide is usually available as hydrogen peroxide water. Therefore, when hydrogen peroxide is used as the oxidizing agent, the content is converted into the actual concentration. In addition, when the substrate having a nickel layer, a base metal layer or the like in addition to the palladium layer as described later is polished, the above content is preferable.

(Organic solvent)
The CMP polishing liquid can further contain an organic solvent. Since the organic solvent dissolves the poorly water-soluble palladium-containing compound produced during polishing and prevents the compound from adhering to the polishing cloth, it is presumed that the decrease in the polishing rate of the palladium layer can be suppressed. Among organic solvents, those that have a low reducing power and do not reduce palladium ions to palladium metal are preferred.

  As an organic solvent, what can be mixed with water arbitrarily is preferable. Examples of the organic solvent include carbonate ester, lactone, glycol, glycol derivative, ether, alcohol, ketone, carboxylic acid ester and the like.

Examples of the carbonate ester include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.
Examples of lactones include butyrolactone and propyrolactone.
Examples of the glycol include ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, and tripropylene glycol.

  Examples of glycol derivatives include ethylene glycol monomethyl ether, propylene glycol monomethyl ether, diethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, triethylene glycol monomethyl ether, tripropylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monoethyl ether, Diethylene glycol monoethyl ether, dipropylene glycol monoethyl ether, triethylene glycol monoethyl ether, tripropylene glycol monoethyl ether, ethylene glycol monopropyl ether, propylene glycol monopropyl ether, diethylene glycol monopropyl ether, dipropylene glycol Monopropyl ether, triethylene glycol monopropyl ether, tripropylene glycol monopropyl ether, ethylene glycol monobutyl ether, propylene glycol monobutyl ether, diethylene glycol monobutyl ether, dipropylene glycol monobutyl ether, triethylene glycol monobutyl ether, tripropylene glycol monobutyl ether, etc. Glycol monoether: ethylene glycol dimethyl ether, propylene glycol dimethyl ether, diethylene glycol dimethyl ether, dipropylene glycol dimethyl ether, triethylene glycol dimethyl ether, tripropylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene Glycol diethyl ether, diethylene glycol diethyl ether, dipropylene glycol diethyl ether, triethylene glycol diethyl ether, tripropylene glycol diethyl ether, ethylene glycol dipropyl ether, propylene glycol dipropyl ether, diethylene glycol dipropyl ether, dipropylene glycol dipropyl ether, Triethylene glycol dipropyl ether, tripropylene glycol dipropyl ether, ethylene glycol dibutyl ether, propylene glycol dibutyl ether, diethylene glycol dibutyl ether, dipropylene glycol dibutyl ether, triethylene glycol dibutyl ether, tripropylene glycol dibutyl ether And the like.

Examples of the ether include tetrahydrofuran, dioxane, dimethoxyethane, polyethylene oxide, ethylene glycol monomethyl acetate, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate and the like.
Examples of the alcohol include methanol, ethanol, propanol, n-butanol, n-pentanol, n-hexanol, and isopropanol.
Examples of the ketone include acetone and methyl ethyl ketone.
Examples of the carboxylic acid ester include ethyl acetate and ethyl lactate.
Examples of the organic solvent include phenol, dimethylformamide, n-methylpyrrolidone, sulfolane and the like.

  These organic solvents can be used alone or in combination of two or more. Among the above organic solvents, glycols, glycol derivatives, alcohols, carbonic acid esters, and carboxylic acid esters are preferable, and glycols and carboxylic acid esters are more preferable. By using the above substances in an organic solvent, the poorly water-soluble palladium-containing compound is more efficiently dissolved, and the decrease in the polishing rate of the palladium layer when polishing the palladium layer continuously is extremely small. Can do.

  The content of the organic solvent is preferably 0.1 to 95% by mass based on the total mass of the CMP polishing liquid. When the content is 0.1% by mass or more, there is a tendency that it is possible to suppress a gradual decrease in the polishing rate of the palladium layer when the palladium layer is continuously polished. The lower limit of the content is more preferably 0.2% by mass, and still more preferably 0.5% by mass. Further, when the content is 95% by mass or less, the solubility of the CMP polishing liquid component tends to be improved, and aggregation of abrasive grains tends to be suppressed. The upper limit of the content is more preferably 50% by mass, and still more preferably 30% by mass.

(Metal anticorrosive)
The CMP polishing liquid can further contain a metal anticorrosive. The metal anticorrosive is a compound that suppresses etching of the metal layer and improves dishing characteristics.

  Specific examples of the metal anticorrosive include imines other than 1,2,4-triazole, azoles, mercaptans, etc. Among them, the suppression of the etching rate of the metal layer and the polishing rate of the metal layer can be mentioned. A nitrogen-containing cyclic compound is preferable from the viewpoint of achieving both improvement. These can be used alone or in combination of two or more.

  Specifically, imines are dithizone, loin (2,2′-biquinoline), neocuproin (2,9-dimethyl-1,10-phenanthroline), bathocuproine (2,9-dimethyl-4,7-diphenyl-1). , 10-phenanthroline) and cuperazone (biscyclohexanone oxalyl hydrazone).

  Specifically, the azole is benzimidazol-2-thiol, triazinedithiol, triazinetrithiol, 2- [2- (benzothiazolyl)] thiopropionic acid, 2- [2- (benzothiazolyl)] thiobutyric acid, 2 -Mercaptobenzothiazole, 1,2,3-triazole, 2-amino-1H-1,2,4-triazole, 3-amino-1H-1,2,4-triazole, 3,5-diamino-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-1H-benzotriazole octyl ester, 5-hexylbenzotriazole, [1,2,3-benzotriazolyl-1-methyl] [1,2, , 4-Triazolyl-1-methyl] [2-ethylhexyl] amine, tolyltriazole, naphthotriazole, bis [(1-benzotriazolyl) methyl] phosphonic acid, tetrazole, 5-amino-tetrazole, 5-methyl-tetrazole 1-methyl-5-mercaptotetrazole, 1-N, N-dimethylaminoethyl-5-tetrazole and the like.

  Specific examples of mercaptans include nonyl mercaptan and dodecyl mercaptan.

  When the metal anticorrosive agent is added, the content thereof is preferably in a range that does not impair the polishing rate improvement effect by 1,2,4-triazole and phosphoric acid, and both the etching suppression function and the polishing rate are achieved. In this respect, it is preferable that the content is 0.005 to 2.0 mass% based on the total mass of the CMP polishing liquid. The content of the metal anticorrosive is preferably 0.01% by mass or more, and more preferably 0.02% by mass or more, in that higher etching performance can be obtained. Moreover, 1.0 mass% or less is more preferable, and 0.5 mass% or less is still more preferable at the point which becomes easy to obtain suitable polishing rate for content of a metal anticorrosive.

(Water-soluble polymer)
The CMP polishing liquid can contain a water-soluble polymer in that the flatness after polishing can be improved. In view of the above, the weight average molecular weight of the water-soluble polymer is preferably 500 or more, more preferably 1500 or more, and still more preferably 5000 or more. The upper limit of the weight average molecular weight is not particularly specified, but is preferably 5 million or less from the viewpoint of solubility. When the weight average molecular weight is 500 or more, a higher polishing rate tends to be obtained.

The weight average molecular weight can be measured using a standard polystyrene calibration curve by gel permeation chromatography (GPC), and more specifically can be measured under the following conditions.
Equipment used: Hitachi L-6000 (manufactured by Hitachi, Ltd.)
Column: Gel Pack GL-R420 + Gel Pack GL-R430 + Gel Pack GL-R440 [Hitachi Chemical Industry Co., Ltd., trade name, total of 3]
Eluent: Tetrahydrofuran Measurement temperature: 40 ° C
Flow rate: 1.75 ml / min.
Detector: L-3300RI [manufactured by Hitachi, Ltd.]

  The water-soluble polymer having a weight average molecular weight of 500 or more is not particularly limited as long as the solubility of the polishing liquid component does not decrease and the abrasive grains do not aggregate. Specifically, polysaccharides, polycarboxylic acid compounds , Vinyl polymer, glycol polymer, and the like. These may be used alone or in combination of two or more.

  Specific examples of the polysaccharide used as the water-soluble polymer include alginic acid, pectic acid, carboxymethylcellulose, agar, curdlan and pullulan.

  Specific examples of the polycarboxylic acid-based compound include, for example, polyaspartic acid, polyglutamic acid, polylysine, polymalic acid, polymethacrylic acid, polymethacrylic acid ammonium salt, polymethacrylic acid sodium salt, polyamic acid, polymaleic acid, polyitaconic acid, Polyfumaric acid, poly (p-styrenecarboxylic acid), polyacrylic acid, polyacrylamide, aminopolyacrylamide, polyacrylic acid ammonium salt, polyacrylic acid sodium salt, polyamic acid, polyamic acid ammonium salt, polyamic acid sodium salt and polyglyoxyl Examples thereof include polycarboxylic acids such as acids, polycarboxylic acid esters and salts thereof, and copolymers thereof.

  Furthermore, specific examples of the vinyl polymer used as the water-soluble polymer include polyvinyl alcohol, polyvinyl pyrrolidone and polyacrolein. Moreover, polyethylene glycol etc. can also be used as a glycol polymer.

  Among the water-soluble polymer compounds, when the substrate to be applied is a silicon substrate for a semiconductor integrated circuit or the like, contamination with an alkali metal, an alkaline earth metal, a halide, or the like is not desirable, so an acid or an ammonium salt thereof is desirable.

  Among the above water-soluble polymer compounds, pullulan, polymalic acid, polymethacrylic acid, polyacrylic acid, polyacrylamide, polyvinyl alcohol and polyvinyl pyrrolidone, esters thereof and ammonium salts thereof are capable of being highly flattened. preferable.

(water)
The CMP polishing liquid contains water. Although there is no restriction | limiting in particular as water, Deionized water and ultrapure water are preferable. The content of water is not particularly limited, and may be the remainder of the content of other components.

(PH)
The pH of the CMP polishing liquid is 7 or less, and is preferably 1 or more from the viewpoint of increasing the CMP polishing rate of the palladium layer. Further, the pH of the CMP polishing liquid is preferably less than 7, and the desired polishing rate tends to be easily secured, and from the viewpoint of becoming a practical polishing liquid, 1 to 6 is more preferable, and 1 to 5 is preferable. Is more preferable, and 1-4 is very preferable.

  The pH of the CMP polishing liquid can be measured with a pH meter (for example, model number PHL-40 manufactured by Electrochemical Instrument Co., Ltd. or model number F-51 manufactured by HORIBA). As a measured value of pH, two-point calibration is performed using a standard buffer (phthalate pH buffer solution pH: 4.01 (25 ° C.), neutral phosphate pH buffer solution pH 6.86 (25 ° C.)). After that, the electrode is put into a CMP polishing liquid, and a value after 2 minutes or more has been stabilized is adopted.

(Polishing method)
By using the CMP polishing liquid described above, it is possible to polish a substrate having a palladium layer formed on at least one surface (surface). That is, the substrate polishing method of this embodiment supplies a CMP polishing liquid containing at least anion-modified abrasive grains, 1,2,4-triazole, phosphoric acids, an oxidizing agent, and water between the substrate and the polishing cloth. However, a polishing step of polishing unnecessary portions of the palladium layer with a polishing cloth is provided.

  In applying this polishing method, the surface to be polished of the substrate exposed to the palladium layer is pressed against the polishing cloth of the polishing platen, and a predetermined pressure is applied to the back surface (the surface opposite to the surface to be polished) of the substrate to be polished. The surface to be polished is polished by moving the substrate relative to the polishing surface plate while supplying the CMP polishing liquid between the surface to be polished and the polishing cloth while the surface is pressed against the polishing cloth. Is preferred. The polishing method of this embodiment may include a preparation step for preparing the substrate before the polishing step.

  As the polishing apparatus, for example, a general polishing apparatus having a motor or the like that can change the number of rotations and having a surface plate to which a polishing cloth (pad) can be attached and a holder that holds the substrate can be used. . As the polishing cloth, a general nonwoven fabric, foamed polyurethane, porous fluororesin, or the like can be used.

  As polishing conditions, it is preferable to set the rotation speed of the surface plate to a low rotation of 200 rpm or less so that the substrate does not jump out. The pressure applied to the substrate pressed against the polishing cloth (polishing pressure) is preferably 4 to 100 kPa, and more preferably 6 to 50 kPa from the viewpoint of excellent uniformity in the substrate surface and pattern flatness. . By using the CMP polishing liquid of this embodiment, the palladium layer can be polished at a high polishing rate at a low polishing pressure. The fact that polishing is possible with a low polishing pressure is important from the viewpoint of preventing peeling of the polishing layer, chipping, fragmentation, cracking, etc., and the flatness of the pattern.

  During polishing, it is preferable to continuously supply a CMP polishing liquid to the surface of the polishing cloth with a pump or the like. As the supply amount, it is preferable that the surface of the polishing pad is always covered with the polishing liquid. The substrate after polishing is preferably washed in running water, and then dried after removing water droplets adhering to the substrate using a spin dryer or the like.

  The substrate that exhibits the best effect of the CMP polishing liquid is a substrate having a palladium layer (referred to as a layer containing palladium). The CMP polishing liquid of this embodiment is also suitable for a substrate in which at least an insulating film layer, a nickel layer (referred to as a layer containing nickel), and a palladium layer are formed in this order on a semiconductor wafer such as silicon. . A base metal layer may be formed between the insulating film layer and the nickel layer.

  Examples of the material forming the palladium layer include at least one selected from palladium, palladium alloys, and other palladium compounds.

  Examples of the material for forming the nickel layer include at least one selected from nickel, nickel alloys, and other nickel compounds.

  The base metal layer is a layer that prevents the conductive material from diffusing into the interlayer insulating film. Examples of the material for forming the base metal layer include tantalum compounds such as tantalum, tantalum alloy, and tantalum nitride; titanium compounds such as titanium, titanium alloy, and titanium nitride; tungsten compounds such as tungsten, tungsten nitride, and tungsten alloy.

Examples of the insulating film layer include inorganic insulating films such as SiO ₂ films and SiN films, organosilicate glasses, and low-k films such as wholly aromatic ring-based Low-k films.

  Hereinafter, a polishing method using a CMP polishing liquid will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a first embodiment of a method for manufacturing a substrate having protruding electrodes, and the polishing method is applied to a part of the steps of the manufacturing method.

  The substrate shown in FIG. 1A includes a silicon wafer 1, an insulating film 2 having unevenness formed on the silicon wafer 1, and an under barrier metal layer 3 that covers the uneven surface of the insulating film 2. Yes. The under barrier metal layer 3 corresponds to a palladium layer. The under barrier metal layer 3 of such a substrate is polished using the CMP polishing liquid of this embodiment. That is, the substrate is polished with a polishing cloth while supplying a CMP polishing liquid containing at least abrasive grains, 1,2,4-triazole, phosphoric acids, an oxidizing agent and water between the under barrier metal layer 3 and the polishing cloth. Then, the convex portion of the insulating film 2 is exposed.

  By such polishing, the under barrier metal layer 3 formed on the convex portion of the insulating film 2 is removed. FIG.1 (b) is sectional drawing which shows the board | substrate obtained by such grinding | polishing.

  Next, a resist pattern 4 is formed by a known method on the convex portion of the insulating film 2 from which the under barrier metal layer 3 has been removed so that the under barrier metal layer 3 formed on the concave portion of the insulating film 2 is exposed. Form. FIG. 1C is a cross-sectional view showing the substrate on which the resist pattern 4 is formed.

  Next, the protruding electrode 5 is formed in the concave portion of the substrate on which the resist pattern 4 is formed by a method such as electroplating, and is protruded from the surface of the insulating film 2. FIG. 1D is a cross-sectional view showing the substrate on which the protruding electrodes 5 are formed. Finally, by removing the resist pattern 4, it is possible to obtain a substrate on which the protruding electrodes 5 are formed on the silicon wafer 1. FIG. 1E is a cross-sectional view showing the substrate having the protruding electrodes obtained as described above. The protruding electrode 5 is generally made of a material such as gold, silver, copper, nickel or solder.

  FIG. 2 is a cross-sectional view showing a second embodiment of a method for manufacturing a substrate having protruding electrodes, and the above polishing method is also applied to a part of the steps of the manufacturing method. However, FIG. 2 shows only the substrate before applying the polishing method (FIG. 2 (a)) and the substrate having the finally obtained protruding electrode (FIG. 2 (b)). The steps of resist pattern formation, bump electrode formation, and resist pattern removal are performed in the same manner as in the first embodiment.

  The substrate shown in FIG. 2A includes a silicon wafer 1, an insulating film 2 having unevenness formed on the silicon wafer 1, a base metal film 6 covering the uneven surface of the insulating film 2, and a base metal film 6. An under barrier metal layer 3 formed thereon. The under barrier metal layer 3 corresponds to a palladium layer. The base metal film 6 is formed for the purpose of suppressing the diffusion of the components of the under barrier metal layer 3 into the silicon wafer 1 and improving the adhesion between the silicon wafer 1 and the under barrier metal layer 3.

  The under barrier metal layer 3 and the underlying metal film 6 of such a substrate are polished using the CMP polishing liquid of the present invention. That is, the substrate is polished with the polishing cloth while supplying the CMP polishing liquid containing abrasive grains, 1,2,4-triazole, phosphoric acid, oxidizing agent and water between the under barrier metal layer 3 and the polishing cloth. Thus, the convex portion of the insulating film 2 is exposed. By such polishing, the under barrier metal layer 3 and the base metal film 6 formed on the convex portion of the insulating film 2 are removed. Then, by performing resist pattern formation, bump electrode formation, and resist pattern removal on the substrate thus obtained in the same manner as in the first embodiment, the silicon wafer 1 shown in FIG. A substrate on which the protruding electrode 5 is formed can be obtained.

  FIG. 3 is a cross-sectional view showing a third embodiment of a method for manufacturing a substrate having protruding electrodes, and the above polishing method is also applied to a part of the steps of the manufacturing method. However, FIG. 3 shows only the substrate before application of the polishing method (FIG. 3A) and the substrate having the bump electrode finally obtained (FIG. 3B). Each step of resist pattern formation, bump electrode formation, and resist pattern removal is performed in the same manner as in the first embodiment.

  The substrate shown in FIG. 3A includes a silicon wafer 1, an insulating film 2 having unevenness formed on the silicon wafer 1, a base metal film 6 covering the uneven surface of the insulating film 2, and a base metal film 6. A first under-barrier metal layer 3b formed above and a second under-barrier metal layer 3a formed on the first under-barrier metal layer 3b are provided. The first under barrier metal layer 3b or the second under barrier metal layer 3a corresponds to a palladium layer.

  The first under barrier metal layer 3b, the second under barrier metal layer 3a, and the base metal film 6 of such a substrate are polished using the CMP polishing liquid of this embodiment. That is, while supplying a CMP polishing liquid containing abrasive grains, 1,2,4-triazole, phosphoric acids, an oxidizing agent and water between the second under barrier metal layer 3a and the polishing cloth, the substrate is polished. The protrusion of the insulating film 2 is exposed by polishing. By such polishing, the first under barrier metal layer 3b, the second under barrier metal layer 3a, and the base metal film 6 formed on the convex portion of the insulating film 2 are removed. The substrate thus obtained is subjected to resist pattern formation, bump electrode formation, and resist pattern removal in the same manner as in the first embodiment, so that the silicon wafer 1 shown in FIG. A substrate on which the protruding electrode 5 is formed can be obtained.

  FIG. 4 shows an example in which the first under barrier metal layer 3b in FIG. 3 is a nickel layer and the second under barrier metal layer 3a is a palladium layer (structure having two under barrier metals).

  The substrate shown in FIG. 4A is obtained by forming a base metal layer 15, a nickel layer 14 and a palladium layer 13 in this order on an uneven portion of an insulating film 12 provided on a silicon substrate 11. By using the CMP polishing liquid of the present embodiment, the palladium layer 13, the nickel layer 14, and the base metal layer 15 can be polished to expose the protrusions of the insulating film 12 as shown in FIG. 4B.

  As another example of the polishing method using the CMP polishing liquid, a first polishing step in which the palladium layer 13 existing on the convex portion of the insulating film 12 is polished to expose the nickel layer 14, and the convex portion of the insulating film 12 is used. A second polishing step of polishing a portion of the nickel layer 14, the base metal layer 15, and the palladium layer 13 filling the concave portion of the insulating film 12 to expose the convex portion of the insulating film 12. And a method using a CMP polishing liquid in at least the first polishing step of the two polishing steps.

  Hereinafter, the present invention will be described by way of examples. In addition, this invention is not restrict | limited to these Examples.

<Reference examples and comparative examples>
First, as a reference example, it is shown that 1,2,4-triazole has a remarkable effect of improving the palladium polishing rate as compared with other additives.

(Polishing liquid preparation method)
The CMP polishing liquids used in Reference Examples 1 to 5 and Reference Comparative Examples 1 to 16 are 2% by mass or 10% by mass of abrasive grains shown in Tables 1 and 2 and 30% peroxide based on the total mass of the CMP polishing liquid. 10% by mass of hydrogen water, 0 to 5% by mass of the metal oxide dissolving agent shown in Tables 1 and 2, 0 or 0.5% by mass of the metal anticorrosive shown in Tables 1 and 2, and pure water in the balance Prepared.

(Liquid property evaluation: pH measurement)
The measurement temperature of CMP polishing liquid was made into the range of 25 +/- 5 degreeC, and pH was measured by the electrochemical instrument company make and type | model number PHL-40.

The substrate was polished under the following polishing conditions using the CMP polishing liquid.
(CMP polishing conditions)
Polishing device: Desktop lapping device (manufactured by Nano Factor Co., Ltd.)
Polishing liquid flow rate: 11 mL / min Substrate: A silicon substrate on which a palladium film having a thickness of 0.3 μm is formed by sputtering.
Polishing cloth: Polyurethane resin with closed cells (Rohm and Haas Japan Co., Ltd., model number IC1000)
Polishing pressure: 29.4 kPa
Relative speed between substrate and polishing platen: 25 m / min Polishing liquid supply amount: 11 mL / min Polishing time: 1 minute Cleaning: After polishing, the substrate was thoroughly washed with running water, and then water droplets were removed and dried.

(Abrasive product evaluation items)
Polishing rate: The film thickness difference before and after polishing was converted from the electrical resistance value, and the polishing rate (PdRR) of the palladium layer polished and washed under the above conditions was determined from the following equation.
(PdRR) = (Palladium layer thickness difference before and after polishing (nm)) / (Polishing time (minutes))

  Tables 1 and 2 show the pH of the CMP polishing liquid and the polishing rate (PdRR) of the palladium layer in Reference Examples 1 to 5 and Reference Comparative Examples 1 to 16, respectively.

  As can be seen from the above, it is understood that a polishing liquid containing phosphoric acids, an oxidizing agent and abrasive grains exhibits an excellent palladium polishing rate after using 1,2,4-triazole as an additive.

<Examples and Comparative Examples>
Next, with respect to the polishing liquid containing 1,2,4-triazole, the effect of the abrasive grains modified with an anionic functional group, the particle diameter of the abrasive grains, and the degree of association on the polishing rate will be described.

As the abrasive grains, the following abrasive grains A to F were prepared.
Abrasive A: Colloidal silica abrasive B having an average primary particle diameter of 35 nm and an average secondary particle diameter of 67 nm B: Colloidal silica abrasive having an average primary particle diameter of 55 nm and an average secondary particle diameter of 114 nm C: Average primary particle diameter of 35 nm Colloidal silica abrasive grain D having a primary particle diameter of 55 nm: Colloidal silica abrasive grain F having an average primary particle diameter of 15 nm, colloidal silica abrasive grain having an average secondary particle diameter of 39 nm, and colloidal silica abrasive grain F having an average secondary particle diameter of 64 nm Colloidal silica with a primary particle size of 31 nm and an average secondary particle size of 87 nm

  Furthermore, using these abrasive grains A to F, abrasive grains whose surfaces were cation-modified with amino groups, abrasive grains whose surfaces were anion-modified with sulfonic acid, and abrasive grains whose surfaces were anion-modified with aluminate were prepared. .

The average primary particle diameter and average secondary particle diameter of the abrasive grains having a modified surface were measured as follows, and the degree of association was calculated from the obtained average primary particle diameter and average secondary particle diameter.
(Average primary particle size)
The abrasive grains were dried with a vacuum freeze dryer, and the residue was finely crushed with a mortar (magnetic, 100 ml) to obtain a measurement sample. And the BET specific surface area measuring apparatus (trade name: Autosorb 6) manufactured by Yuasa Ionics Co., Ltd. was used to measure the BET specific surface area of the sample, and the average primary particle diameter was calculated.
(Average secondary particle size)
A dispersion (medium: water) adjusted so as to have an abrasive concentration of 12% by mass was used as a sample. A sample for measurement was prepared by adding 50 ml of 0.3% aqueous citric acid solution to 4 g of the sample and shaking it lightly. This measurement sample was measured using a particle size measuring device (ELS-8000 (trade name) manufactured by Otsuka Electronics Co., Ltd.), and the value of the obtained average particle size was defined as the average secondary particle size.

(Comparative Example 1)
5.0% by weight of abrasive grain A with no surface modification as abrasive grains, 10% by weight of 30% hydrogen peroxide as an oxidizing agent, 5% by weight of phosphoric acid as a metal oxide solubilizer, metal corrosion protection A CMP polishing liquid was prepared by mixing and stirring 0.5% by mass of 1,2,4-triazole as an agent, 5.0% by mass of propylpropylene glycol as an organic solvent, and the remaining pure water.
(Comparative Example 2)
A CMP polishing liquid was prepared in the same manner as in Comparative Example 1 except that abrasive grains A whose surface was cationically modified with amino groups were used as abrasive grains.
Example 1
A CMP polishing liquid was prepared in the same manner as in Comparative Example 1 except that abrasive grains A whose surface was anion-modified with aluminate were used as abrasive grains.
(Example 2)
A CMP polishing solution was prepared in the same manner as in Comparative Example 1 except that abrasive grains A whose surface was anion-modified with sulfonic acid were used as abrasive grains.

(Comparative Example 3)
A CMP polishing liquid was prepared in the same manner as in Comparative Example 1 except that abrasive grains B that were not surface-modified were used as abrasive grains.
(Example 3)
A CMP polishing liquid was prepared in the same manner as in Comparative Example 3 except that abrasive grains B whose surface was anion-modified with sulfonic acid were used as abrasive grains.

(Comparative Example 4)
A CMP polishing liquid was prepared in the same manner as in Comparative Example 1 except that abrasive grains C not subjected to surface modification were used as abrasive grains.
Example 4
A CMP polishing liquid was prepared in the same manner as in Comparative Example 4 except that abrasive grains C whose surfaces were anion-modified with sulfonic acid were used as abrasive grains.

(Comparative Example 5)
A CMP polishing liquid was prepared in the same manner as in Comparative Example 1 except that abrasive grains D that were not subjected to surface modification were used as abrasive grains.
(Comparative Example 6)
A CMP polishing liquid was prepared in the same manner as in Comparative Example 5 except that the abrasive grains D whose surface was cationically modified with amino groups were used as the abrasive grains.
(Example 5)
A CMP polishing solution was prepared in the same manner as in Comparative Example 5 except that the abrasive grains D whose surface was anion-modified with aluminate were used as the abrasive grains.
(Example 6)
A CMP polishing liquid was prepared in the same manner as in Comparative Example 5 except that the abrasive grains D whose surface was anion-modified with sulfonic acid were used as abrasive grains.

(Comparative Example 7)
A CMP polishing liquid was prepared in the same manner as in Comparative Example 1 except that abrasive grains E that were not subjected to surface modification were used as abrasive grains.
(Example 7)
A CMP polishing liquid was prepared in the same manner as Comparative Example 7 except that the abrasive grains E whose surface was anion-modified with aluminate were used as the abrasive grains.

(Comparative Example 8)
A CMP polishing liquid was prepared in the same manner as in Comparative Example 1 except that abrasive grains F that were not surface-modified were used as abrasive grains.
(Example 8)
A CMP polishing liquid was prepared in the same manner as in Comparative Example 8, except that abrasive grains F whose surface was anion-modified with aluminate were used as abrasive grains.
Example 9
A CMP polishing liquid was prepared in the same manner as in Comparative Example 8, except that abrasive grains F whose surface was anion-modified with sulfonic acid were used as abrasive grains.

The pH of each CMP polishing liquid prepared above and the zeta potential of the abrasive grains were measured as follows.
(PH)
The measurement temperature of CMP polishing liquid was made into the range of 25 +/- 5 degreeC, and pH was measured using the product made from HORIBA, model number F-51.
(Zeta potential)
The zeta potential of abrasive grains contained in the CMP polishing liquid was measured using a zeta potential measuring device “Zetasizer 3000 HSA (trade name)” manufactured by Marvern Instruments.

The substrate to be polished was polished under the following polishing conditions using the CMP polishing liquid prepared above.
(CMP polishing conditions)
Polishing device: Mirra (Applied Materials)
CMP polishing fluid flow rate: 200 mL / min Substrate to be polished: Silicon substrate on which a palladium layer having a thickness of 0.3 μm is formed by a sputtering method Polishing cloth: Polyurethane resin with closed cells (Rohm and Haas Japan Co., Ltd., Model number IC1000)
Polishing pressure: 29.4 kPa (4 psi)
Relative speed between substrate and polishing platen: 68 m / min Polishing time: 1 minute Cleaning: After CMP treatment, cleaning with ultrasonic water was performed, followed by drying with a spin dryer.

(Abrasive product evaluation items)
Polishing rate: The film thickness difference before and after polishing was converted from the electrical resistance value, and the polishing rate (PdRR) of the palladium layer polished and washed under the above conditions was determined from the following equation.
(PdRR) = (Palladium layer thickness difference before and after polishing (nm)) / (Polishing time (minutes))

  Further, the amount of change in PdRR was calculated by comparing PdRR when using surface-modified abrasive grains and PdRR when using unmodified abrasive grains.

Table 3 shows the average primary particle size, average secondary particle size, association degree, zeta potential, polishing solution pH, PdRR, and PdRR variation of the abrasive grains. In Table 3, superscript symbols for abrasive grains indicate the following.
0: Abrasive grains not surface-modified +: Abrasive grains cation-modified with amino groups -1: Abrasive grains anion-modified with sulfonic acid -2: Abrasive grains anion-modified with aluminate

  Hereinafter, the results shown in Table 3 will be described in detail. As can be seen from Table 3, in the polishing liquid containing phosphoric acids and an oxidizing agent in addition to 1,2,4-triazole, by using anion-modified abrasive grains as abrasive grains, the polishing rate for the palladium layer is further improved. It turns out that the improvement effect is acquired.

  In particular, Examples 1 to 3 and 7 to 9 in which the average secondary particle diameter of the abrasive grains is 60 nm or more are more anionic than Examples 4 to 6 in which the average secondary particle diameter of the abrasive grains is less than 60 nm. The degree of improvement of the polishing rate by adding the modified abrasive grains is remarkable.

  In addition, when the degree of association of the abrasive grains is around 2.0 (1.8 to 2.1), the polishing rate is excellent even when the abrasive grains that are not surface-modified are used. In Examples 1 to 3 using the polished abrasive grains, it can be seen that the degree of improvement in the polishing rate is large, and a further excellent polishing rate can be obtained.

  According to the CMP polishing liquid and the polishing method using the CMP polishing liquid of the present invention, it is possible to improve the polishing rate of at least the palladium layer and perform polishing at a desired polishing rate as compared with the case of using the conventional polishing liquid. it can.

  DESCRIPTION OF SYMBOLS 1 ... Silicon wafer, 2, 12 ... Insulating film, 3 ... Under barrier metal layer, 3a ... 2nd under barrier metal layer, 3b ... 1st under barrier metal layer, 4 ... Resist pattern, 5 ... Projection electrode, 6 ... base metal film, 11 ... silicon substrate, 13 ... palladium layer, 14 ... nickel layer, 15 ... base metal layer.

Claims (14)

  A CMP polishing liquid containing abrasive grains having an anionic functional group, 1,2,4-triazole, phosphoric acids, an oxidizing agent, and water, and having a pH of 7 or less.   The CMP polishing according to claim 1, wherein the abrasive grains have at least one selected from an aluminate group, a sulfonic acid group, a carboxylic acid group, a nitric acid group, a phosphoric acid group, a carbonic acid group, and an iodic acid group as the anionic functional group. liquid.   The CMP polishing liquid of Claim 1 or 2 whose average secondary particle diameter of the said abrasive grain is 60 nm or more.   The CMP polishing liquid according to any one of claims 1 to 3, wherein the degree of association of the abrasive grains is 1.7 to 2.3.   The CMP polishing liquid according to any one of claims 1 to 4, wherein the abrasive contains at least one abrasive selected from alumina, silica, zirconia, titania and ceria.   The CMP polishing liquid according to claim 1, wherein the content of the abrasive grains is 0.1 to 10% by mass based on the total mass of the CMP polishing liquid.   The oxidant according to any one of claims 1 to 6, comprising at least one selected from hydrogen peroxide, periodic acid, periodate, iodate, bromate and persulfate. CMP polishing liquid. A step of polishing the palladium layer with the polishing cloth while supplying a CMP polishing liquid between the substrate having the palladium layer formed on at least one surface and the polishing cloth;
The CMP polishing liquid contains abrasive grains having an anionic functional group, 1,2,4-triazole, phosphoric acids, an oxidizing agent, and water,
A polishing method, wherein the CMP polishing solution has a pH of 7 or less.   The polishing method according to claim 8, wherein the abrasive grains have at least one selected from an aluminate group, a sulfonate group, a carboxylic acid group, a nitrate group, a phosphate group, a carbonate group, and an iodate group as the anionic functional group. .   The polishing method according to claim 8 or 9, wherein an average secondary particle diameter of the abrasive grains is 60 nm or more.   The grinding | polishing method as described in any one of Claims 8-10 whose association degree of the said abrasive grain is 1.7-2.3.   The polishing method according to any one of claims 8 to 11, wherein the CMP polishing liquid contains abrasive grains made of at least one selected from alumina, silica, zirconia, titania and ceria as the abrasive grains.   The polishing method according to any one of claims 8 to 12, wherein the content of the abrasive grains is 0.1 to 10% by mass based on the total mass of the CMP polishing liquid.   The CMP polishing liquid contains at least one selected from hydrogen peroxide, periodic acid, periodate, iodate, bromate, and persulfate as the oxidizing agent. The polishing method according to one item.

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