JP2013038237A - Cmp polishing liquid and polishing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a CMP polishing liquid and a polishing method which can dramatically reduce the number of abrasion scratches while keeping a good polishing speed.SOLUTION: The CMP polishing liquid has pH less than or equal to 4 and contains abrasive grains, a metal oxide solubilizer, an oxidizer and water. The secondary particle size of the abrasive grains ranges between 10 nm and 200 nm. As the particle size distribution measurement, the light-scattering method gives the number of particles of less than 1000 particles/ml with a particle size greater than or equal to 0.56 μm and less than 0.64 μm, and the light-blocking method gives the number of particles of less than 600 particles/ml with a particle size greater than or equal to 0.64 μm and less than 0.79 μm.

Description

  The present invention relates to a polishing liquid for CMP and a polishing method used for polishing in a wiring formation process of a semiconductor device.

  2. Description of the Related Art In recent years, new microfabrication techniques have been developed along with higher integration and higher performance of semiconductor integrated circuits (hereinafter referred to as LSIs). Chemical mechanical polishing (hereinafter referred to as CMP) is one of them, and is a technology frequently used in LSI manufacturing processes, particularly in the formation of interlayer insulating films, metal plugs, embedded wirings, etc. in multilayer wiring forming processes. (For example, see Patent Document 1).

  Recently, in order to improve the performance of LSIs, attempts have been made to use copper or a copper alloy as a conductive substance serving as a wiring material. However, it is difficult to finely process copper or a copper alloy by a dry etching method frequently used in forming a conventional aluminum alloy wiring.

  Therefore, for example, a so-called damascene method is mainly employed, in which a thin film of copper or copper alloy is deposited and embedded on an insulating film in which grooves have been previously formed, and the thin film other than the grooves is removed by CMP to form embedded wiring. (For example, see Patent Document 2).

  On the other hand, on the lower layer of a conductive material layer made of a metal for wiring such as copper or a copper alloy, a barrier conductor layer (hereinafter referred to as a barrier conductor layer for preventing metal diffusion into an interlayer insulating film formed on a silicon substrate and improving adhesion) For example, a layer made of a conductor such as tantalum, a tantalum alloy, or tantalum nitride is formed. Therefore, it is necessary to remove the exposed barrier layer by CMP except for a wiring portion in which a conductive material made of a wiring metal such as copper or a copper alloy is embedded.

  However, since the conductor constituting the barrier layer has higher hardness than copper or copper alloy, a sufficient polishing rate cannot be obtained even when a polishing material for copper or copper alloy is combined, and the surface to be polished is flat. In many cases, it becomes worse. Therefore, a two-stage polishing method in which polishing is performed with different polishing liquids has been studied, divided into a first polishing process for polishing the conductive material layer and a second polishing process for polishing the barrier layer.

  FIG. 1 is a schematic cross-sectional view showing wiring formation by a damascene process to which a general two-stage polishing method is applied. FIG. 1A shows a state before polishing, an interlayer insulating film 1 having a groove formed on the surface, a barrier layer 2 formed so as to follow the recesses and protrusions on the surface of the interlayer insulating film 1, and the recesses. And a conductive material layer 3 made of a wiring metal such as copper or a copper alloy deposited so as to fill the convex portion.

  First, as shown in FIG. 1B, the conductive material layer 3 is polished with a polishing liquid for polishing the wiring metal until the barrier layer 2 is exposed (first polishing step). Next, the barrier layer 2 is polished with a polishing liquid for polishing the barrier layer 2 until the convex portions of the interlayer insulating film 1 are exposed (second polishing step). In this second polishing step, as shown in FIG. 1C, over polishing is often performed in which the interlayer insulating film 1 is excessively polished. By such overpolishing, the flatness of the polished surface after polishing can be improved. In FIG. 1C, the dotted line represents the polished barrier layer portion 4 (the state of the barrier layer 2 before the second polishing step (FIG. 1B)).

  Such a polishing liquid for the barrier layer 2 contains an oxidizing agent, a protective film forming agent for the metal surface, an acid, and water, has a pH of 3 or less, and a concentration of the oxidizing agent of 0.01 mass. An abrasive for chemical mechanical polishing of from% to 3% by mass has been proposed. (For example, refer to Patent Document 3.)

  By the way, in recent years, with further miniaturization of the wiring interval and the wiring thickness, a problem due to the generation of polishing scratches (also called scratches) generated in the second polishing process for polishing the barrier layer has become larger. Polishing scratches are linear scratches generated on the surfaces of the conductive material layer and the interlayer insulating film, and cause film defects and structural changes. When polishing flaws occur on the surface of the conductive material layer and the interlayer insulating film, film defects and structural changes occur, resulting in problems such as disconnection of the wiring of the semiconductor device and a decrease in reliability. This problem becomes more prominent when the wiring interval and the wiring thickness are miniaturized.

U.S. Pat. No. 4,944,836 Japanese Patent Laid-Open No. 02-278822 Republished patent WO01 / 13417 pamphlet

  As described above, the polishing scratches that become a problem when the conventional barrier layer polishing liquid is used are caused by coarse particles such as silica and alumina used as abrasive grains in order to improve the polishing rate. Conceivable. That is, if the CMP polishing liquid contains particles having a relatively large particle size, the particles are likely to be selectively subjected to pressure from the polishing pad during polishing, and local pressure is applied to the film surface in contact with the particles. It is considered that when the particles move on the film surface in this state, linear polishing scratches are generated. Therefore, in order to manufacture a semiconductor device that operates well as designed, it is increasingly important to suppress the generation of polishing flaws in the second polishing step for polishing the barrier layer.

The present invention solves this problem, and provides a polishing liquid for CMP and a polishing method using the same that can dramatically reduce the number of occurrences of polishing flaws while ensuring a good polishing rate. It is to provide.

  As a result of various studies to solve the above problems, the present inventors have determined that the particle diameter and the number of particles so that the abrasive grains contained in the polishing liquid have a specific particle size distribution according to the secondary particle diameter. It was found that the number of occurrences of polishing flaws can be remarkably reduced by controlling.

The CMP polishing liquid and polishing method according to the present invention are as follows.
<1> An abrasive grain, a metal oxide solubilizer, an oxidizer, and water are included. The pH is 4 or less, and the particle size distribution measured using a light scattering method and a light shielding method is the following condition (a ) And (b).
Condition (a): The number of particles having a particle diameter of 0.56 μm or more and less than 0.64 μm is less than 1000 / ml Condition (b): The number of particles having a particle diameter of 0.64 μm or more and less than 0.79 μm is 600 Less than pieces / ml

<2> The CMP polishing liquid according to <1>, wherein the particle size distribution further satisfies the following condition (c).
Condition (c): The number of particles having a particle diameter of 0.79 μm or more and less than 0.98 μm is less than 500 / ml.

<3> The CMP polishing liquid according to <2>, wherein the particle size distribution further satisfies the following condition (d).
Condition (d): The number of particles having a particle diameter of 0.98 μm or more and less than 1.43 μm is less than 300 / ml.

<4> The CMP polishing liquid according to <3>, wherein the particle size distribution further satisfies the following condition (e).
Condition (e): The number of particles having a particle size of 1.43 μm or more and less than 3.99 μm is less than 150 / ml.

<5> The CMP polishing liquid according to <4>, wherein the particle size distribution further satisfies the following condition (f).
Condition (f): The number of particles having a particle size of 3.99 μm or more is less than 50 / ml.

<6> The abrasive grain according to any one of <1> to <5>, wherein the abrasive is at least one selected from the group consisting of silica, alumina, ceria, titania, zirconia, germania, and modified products thereof. A polishing liquid for CMP.

<7> The polishing slurry for CMP according to any one of <1> to <6>, wherein a secondary particle diameter of the abrasive grains is 10 nm or more and 200 nm or less.

<8> The polishing slurry for CMP according to any one of <1> to <7>, wherein the content of the abrasive grains is 0.2 to 50 parts by mass in 100 parts by mass of the polishing slurry for CMP. is there.

<9> The polishing slurry for CMP according to any one of <1> to <8>, further containing a quaternary phosphonium salt.

<10> The quaternary phosphonium salt is selected from butyltriphenylphosphonium salt, amyltriphenylphosphonium salt, hexyltriphenylphosphonium salt, n-heptyltriphenylphosphonium salt, tetraphenylphosphonium salt and benzyltriphenylphosphonium salt. The polishing slurry for CMP according to <9>, which is at least one kind.

<11> An interlayer insulating film having recesses and protrusions formed on the surface, a barrier layer covering the surface of the interlayer insulating film along the recesses and protrusions, at least filling the recesses, and the barrier A first polishing step of polishing the conductive material layer of the substrate having a conductive material layer covering the layer to expose the barrier layer on the convex portion, and polishing the exposed barrier layer; <1> to <10> for use in the second polishing step of a two-step polishing method comprising: a second polishing step for exposing a convex portion of the interlayer insulating film. A polishing liquid.

<12> An interlayer insulating film having recesses and protrusions formed on the surface, a barrier layer covering the surface of the interlayer insulating film along the recesses and protrusions, at least filling the recesses, and the barrier A first polishing step of polishing the conductive material layer of the substrate having a conductive material layer covering the layer to expose the barrier layer on the convex portion, and the exposed barrier layer <1> A polishing method comprising: a second polishing step of polishing using the CMP polishing liquid according to any one of <10> to expose a convex portion of the interlayer insulating film.

<13> The polishing method according to <12>, wherein the conductive material layer includes at least one conductive material selected from copper, a copper alloy, a copper oxide, and a copper alloy oxide.

<14> The polishing method according to <12> or <13>, wherein the barrier layer includes at least one selected from tantalum, a tantalum compound, titanium, a titanium compound, tungsten, a tungsten compound, ruthenium, and a ruthenium compound.

<15> The polishing method according to any one of <12> to <14>, wherein the interlayer insulating film is a low-k film.

<16> The polishing method according to <15>, wherein the low-k film is a silicon-based film or an organic polymer film having a dielectric constant of 2.9 or less.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the polishing liquid for CMP which can dramatically reduce the number of generation | occurrence | production of a polishing flaw, and the polishing method using the same, ensuring a favorable polishing rate.

The cross-sectional schematic diagram of the wiring formation by a general damascene process is shown.

  In this specification, the term “process” is not limited to an independent process, and is included in the term if the intended action of the process is achieved even when it cannot be clearly distinguished from other processes. . In the present specification, a numerical range indicated by using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively. Further, in the present specification, when referring to the amount of each component in the polishing liquid, when there are a plurality of substances corresponding to each component in the polishing liquid, the plurality of the plurality of substances existing in the polishing liquid unless otherwise specified. It means the total amount of substance.

Hereinafter, preferred embodiments of a polishing slurry for CMP of the present invention (hereinafter also simply referred to as “polishing fluid”) and a polishing method using the same will be described in detail.
[Polishing liquid]

  The CMP polishing liquid of the present invention contains abrasive grains, at least one metal oxide solubilizer described later, at least one oxidizing agent, and water, and has a pH of 4 or less.

  In the polishing liquid, by controlling the particle size distribution of the abrasive grains according to the secondary particle diameter, it is possible to remarkably reduce the number of polishing flaws generated on the film surface during polishing. Therefore, according to the polishing liquid, it is possible to suppress problems such as disconnection of the wiring of the semiconductor device and deterioration of reliability due to film defects and structural changes. The particle size distribution of the abrasive grains represents a particle size distribution measured by a light scattering method and a light shielding method using a polishing liquid.

<Abrasive>
The polishing liquid contains abrasive grains whose particle size distribution is controlled according to the secondary particle diameter. The abrasive grains are controlled so that the abrasive particles having a larger secondary particle diameter are gradually reduced in number. As a result, it is possible to dramatically reduce polishing scratches generated on the film surface during polishing while ensuring a good polishing rate of the barrier layer.

The particle size distribution of the abrasive grains satisfies the following conditions (a) and (b). From the viewpoint of achieving both the controllability of the polishing rate and the effect of reducing polishing flaws, it is preferable that the following conditions (c) to (f) are further satisfied, and it is more preferable that all of the following conditions (a) to (f) are satisfied.
Condition (a): Abrasive particles (first particle group) having a secondary particle size of 0.56 μm or more and less than 0.64 μm are contained in 1 ml of CMP polishing liquid in a range of 0 or more and less than 1000 particles. Condition (b): Abrasive particles (second particle group) having a secondary particle diameter of 0.64 μm or more and less than 0.79 μm are contained in 1 ml of CMP polishing liquid in a range of 0 or more and less than 600. Condition (c): Abrasive particles (third particle group) having a secondary particle diameter of 0.79 μm or more and less than 0.98 μm are contained in 1 ml of CMP polishing liquid in a range of 0 or more and less than 500 particles. Condition (d): Abrasive particles (fourth particle group) having a secondary particle size of 0.98 μm or more and less than 1.43 μm are contained in a range of 0 or more and less than 300 in 1 ml of the polishing slurry for CMP. Condition (e): Abrasive grains having a secondary particle size of 1.43 μm or more and less than 3.99 μm (Fifth particle group) is contained in 1 ml of CMP polishing liquid in a range of 0 or more and less than 150 Condition (f): Abrasive particles (second particles) having a secondary particle diameter of 3.99 μm or more Group) is contained in 1 ml of CMP polishing liquid in the range of 0 or more and less than 50.

  The number of particles in the first particle group is preferably 0 or more and less than 900, more preferably 0 or more and less than 800. The number of particles in the second particle group is preferably 0 or more and less than 550, more preferably 0 or more and less than 500. The number of particles in the third particle group is preferably 0 or more and less than 450, more preferably 0 or more and less than 400. The number of particles in the fourth particle group is preferably 0 or more and less than 270, more preferably 0 or more and less than 240. The number of particles in the fifth particle group is preferably 0 or more and less than 135, more preferably 0 or more and less than 120. The number of particles in the sixth particle group is preferably 0 or more and less than 45, more preferably 0 or more and less than 40.

  However, the number of the first to sixth particles represents a numerical value when the polishing liquid of the present invention is applied to a polishing liquid used in actually manufacturing a semiconductor device, In the case of applying to a concentrated polishing liquid used by diluting to a predetermined concentration with a solvent such as the above, it is a numerical value in the diluted polishing liquid.

  The method for controlling the particle size distribution of the abrasive grains is not particularly limited, but is preferably at least one selected from filtration using a filter, natural sedimentation separation, centrifugation, and the like. Especially, filtration using a filter is more preferable from a viewpoint that process time and process expense can be suppressed, reducing a coarse particle effectively. Such a method for controlling the particle size distribution may be used alone or in combination of two or more.

  The particle size distribution of the abrasive grains can be measured with a particle size distribution measuring apparatus using a light scattering method and a light shielding method (for example, trade name: Accusizer 780 manufactured by Particle Sizing System). In the measurement using the particle size distribution measuring apparatus, details of the measurement conditions are as described below.

  The abrasive grains are not particularly limited, and specific examples include silica, alumina, zirconia, ceria, titania, germania, and modified products thereof, among which silica, alumina, zirconia, ceria, titania. And germania are preferred, and silica and alumina are more preferred.

  The silica or alumina particles are preferably colloidal silica or colloidal alumina, more preferably colloidal silica, which is excellent in dispersion stability in the polishing liquid and has a small number of polishing scratches (scratches) generated by CMP.

  The colloidal silica can be produced by a known production method by hydrolysis of silicon alkoxide or ion exchange of sodium silicate, and silicon such as tetramethoxysilane or tetraethoxysilane in terms of particle size controllability and alkali metal impurities. The method of hydrolyzing the alkoxide is most often used. The colloidal alumina can be produced by a known production method by hydrolysis of aluminum nitrate.

  The modified product is a product obtained by modifying the surface of abrasive grains with an alkyl group or the like. The method of modifying the surface of the abrasive grain with an alkyl group is not particularly limited, and examples thereof include a method of reacting a hydroxyl group present on the grain surface of the abrasive grain with an alkoxysilane having an alkyl group.

  The alkoxysilane having an alkyl group is not particularly limited, but monomethyltrimethoxysilane, dimethyldimethoxysilane, trimethylmonomethoxysilane, monoethyltrimethoxysilane, diethyldimethoxysilane, triethylmonomethoxysilane, monomethyltriethoxysilane, Examples thereof include dimethyldiethoxysilane and trimethylmonoethoxysilane.

  The method for reacting the hydroxyl group and the alkoxysilane having an alkyl group is not particularly limited. For example, a method of reacting abrasive grains and alkoxysilane in a polishing liquid at room temperature or optionally with heating can be used. These abrasive grains can be used alone or in combination of two or more.

  The content of the abrasive grains is preferably 0.2 to 50 parts by mass, more preferably 0.5 to 30 parts by mass, and further preferably 1 to 20 parts by mass in 100 parts by mass of the polishing liquid. Part by mass. When the content of the abrasive grains is 0.2 parts by mass or more, the polishing rate for the barrier layer and the interlayer insulating film does not decrease, and when 50 parts by mass or less is used, aggregation of the abrasive grains can be suppressed.

  The secondary particle diameter of the abrasive grains is preferably 10 nm to 200 nm. The secondary particle diameter is more preferably 20 nm or more, further preferably 30 nm or more, and particularly preferably 40 nm or more in that a better polishing rate can be obtained. Further, the secondary particle diameter is more preferably 150 nm or less, further preferably 100 nm or less, and particularly preferably 80 nm or less in that polishing scratches can be more effectively suppressed.

  The secondary particle diameter of the abrasive grains is a value measured with a dynamic light scattering particle size distribution meter (for example, trade name: COULTER N4 SD manufactured by COULTER Electronics). The measurement conditions of the Coulter were a measurement temperature of 20 ° C., a solvent refractive index of 1.333 (water), a particle refractive index of Unknown (setting), a solvent viscosity of 1.005 cp (water), a Run Time of 200 sec, and a laser incident angle of 90 °. When it is higher than 4E + 05 so that (scattering intensity, corresponding to turbidity) falls within the range of 5E + 04 to 4E + 05, it is diluted with water and measured.

  The abrasive grains preferably have a standard deviation of the average particle size distribution of 10 nm or less, more preferably 5 nm or less, from the viewpoint of suppressing aggregation of the abrasive grains.

  The abrasive grains are preferably aggregated particles obtained by agglomerating primary particles having an average of less than 2 particles, and primary particles having an average of less than 1.5 particles from the viewpoint of the polishing rate of the conductive material layer, the barrier layer, and the interlayer insulating film. More preferably, the particles are aggregated particles.

  In order to confirm that the abrasive grains are less than 2 particles on average, first, the average particle size is measured by a dynamic light scattering particle size distribution meter (for example, product name: COULTER N4 SD manufactured by COULTER Electronics). Ask. Next, the primary particle size of the abrasive grains is obtained by observing with a length-measuring scanning electron microscope (for example, trade name: S-4800 manufactured by Hitachi High-Technologies Corporation). Then, the average particle diameter of the obtained abrasive grains may be divided by the primary particle diameter and calculated.

<Metal oxide solubilizer>
The polishing liquid of the present invention contains at least one metal oxide solubilizer. The metal oxide solubilizer is a compound that can effectively control the polishing rate and the etching rate.

  The metal oxide solubilizer is not particularly limited, and examples thereof include organic acid compounds such as organic acids, organic acid esters, and ammonium salts of organic acids, and inorganic acid compounds such as inorganic acids and ammonium salts of inorganic acids. Specifically, for example, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, 2-methylbutyric acid, n-hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid, 4-methylpentanoic acid, n-heptane Acid, 2-methylhexanoic acid, n-octanoic acid, 2-ethylhexanoic acid, benzoic acid, glycolic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid Organic acids such as phthalic acid, malic acid, tartaric acid, citric acid and p-toluenesulfonic acid; ammonium salts of the organic acid esters and organic acids; inorganic acids such as hydrochloric acid, sulfuric acid and nitric acid; ammonium persulfate, ammonium nitrate and chloride Examples thereof include ammonium salts of the above inorganic acids such as ammonium and ammonium chromate.

  Among these, formic acid, malonic acid, malic acid, tartaric acid, citric acid, salicylic acid, and adipic acid are preferable in that the etching rate can be effectively suppressed while maintaining a practical polishing rate. These metal oxide solubilizers can be used alone or in combination of two or more.

  The content of the metal oxide solubilizer is preferably 0.001 parts by mass or more in 100 parts by mass of the polishing liquid in terms of improving the polishing rate of the conductive material layer and the barrier layer, and 0.002 parts by mass. More preferably, it is more preferably 0.005 parts by mass or more. Moreover, it is preferable that it is 20 parts by mass or less, more preferably 10 parts by mass or less, in 100 parts by mass of the polishing liquid, in that etching can be easily suppressed and roughness generated on the surface to be polished can be suppressed. More preferably, it is 5 parts by mass or less.

<Oxidizing agent>
The polishing liquid contains at least one oxidizing agent. The oxidizing agent is not particularly limited as long as it is a compound having an oxidizing action on metals. Specifically, for example, hydrogen peroxide, peroxosulfate, nitric acid, potassium periodate, hypochlorous acid, ozone water Among them, hydrogen peroxide is preferable. These oxidizing agents can be used alone or in combination of two or more.

  The content of the oxidizing agent is preferably 0.01 parts by mass or more in 100 parts by mass of the polishing liquid, in that the conductive material layer and the barrier layer are sufficiently oxidized and the polishing rate is also kept good. 0.02 parts by mass or more is more preferable, and 0.05 parts by mass or more is more preferable. Moreover, it is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 15 parts by mass or less in 100 parts by mass of the polishing liquid in that it can prevent the surface to be polished from being rough. .

<Metal anticorrosive>
The polishing liquid of the present invention preferably contains at least one metal anticorrosive agent. As the metal anticorrosive agent, any conventionally known compounds can be used as compounds having an anticorrosive action against metals.

  For example, compounds having a thiazole skeleton such as 2-mercaptobenzothiazol and 2,4-dimethylthiazole; 1,2,3-triazol, 1,2,4-triazole, 3-amino-1H -1,2,4-triazole, benzotriazole, 1-hydroxybenzotriazole, 1-dihydroxypropylbenzotriazole, 2,3-dicarboxypropylbenzotriazole, 4-hydroxy Benzotriazole, 4-carboxyl (-1H-) benzotriazole, 4-carboxyl (-1H-) benzotriazole methyl ester, 4-carboxyl (-1H-) benzotriazole butyl ester, 4-carboxyl ( -1H-) benzotriazol octyl ester, 5-hexylbenzotriazole, [1,2,3-benzoto Azolyl-1-methyl] [1,2,4-triazolyl-1-methyl] [2-ethylhexyl] amine, tolyltriazole, naphthotriazole, bis [(1-benzotriazolyl) methyl] phosphonic acid, etc. Compound having a triazole skeleton; pyrimidine, 1,2,4-triazolo [1,5-a] pyrimidine, 1,3,4,6,7,8-hexahydro-2H-pyrimido [1,2-a] pyrimidine 1,3-diphenyl-pyrimidine-2,4,6-trione, 1,4,5,6-tetrahydropyrimidine, 2,4,5,6-tetraaminopyrimidine sulfate, 2,4,5-trione Hydroxypyrimidine, 2,4,6-triaminopyrimidine, 2,4,6-trichloropyrimidine, 2,4,6-trimethoxypyrimidine, 2,4,6-to Phenylpyrimidine, 2,4-diamino-6-hydroxylpyrimidine, 2,4-diaminopyrimidine, 2-acetamidopyrimidine, 2-aminopyrimidine, 2-methyl-5,7-diphenyl- (1,2,4) triazolo ( 1,5-a) pyrimidine, 2-methylsulfanyl-5,7-diphenyl- (1,2,4) triazolo (1,5-a) pyrimidine, 2-methylsulfanyl-5,7-diphenyl-4 , 7-dihydro- (1,2,4) triazolo (1,5-a) pyrimidine, compounds having a pyrimidine skeleton such as 4-aminopyrazolo [3,4, -d] pyrimidine; tetrazole, 5-methyltetrazole, 5 -Compounds having a tetrazole skeleton such as aminotetrazole and 1- (2-dimethylaminoethyl) -5-mercaptotetrazole Imidazole, 2-methylimidazole, 2-ethylimidazole, 2-isopropylimidazole, 2-propylimidazole, 2-butylimidazole, 4-methylimidazole, 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole, 2; -Compounds having an imidazole skeleton such as undecylimidazole and 2-aminoimidazole; such as pyrazole, 3,5-dimethylpyrazole, 3-amino-5-methylpyrazole, 4-methylpyrazole, 3-amino-5-hydroxypyrazole A compound having a pyrazole skeleton; and the like. These may be used alone or in combination of two or more.

  Among them, a compound having a triazole skeleton and a compound having a tetrazole skeleton are preferable in that the etching rate can be effectively suppressed, and 1,2,3-triazole, benzotriazole, 1-hydroxybenzotriazole and the like. Azol, tetrazole, 5-methyltetrazole and 5-aminotetrazole are more preferred.

  The content of the metal anticorrosive is 0.001 part by mass in 100 parts by mass of the polishing liquid in that the etching of the conductive material layer can be easily suppressed and the surface to be polished is less likely to be rough. Preferably, it is 0.005 parts by mass or more, and more preferably 0.01 parts by mass or more. Moreover, it is preferable that it is 10 mass parts or less in 100 mass parts of said polishing liquid, and it is more preferable that it is 5 mass parts or less at the point which can suppress the fall of the grinding | polishing rate of an electroconductive substance layer and a barrier layer. It is still more preferable that it is below mass parts.

<Water-soluble polymer>
The polishing liquid preferably contains at least one water-soluble polymer. Thereby, the improvement of the flatness of a to-be-polished surface can be achieved effectively. A water-soluble polymer can be used individually by 1 type or in mixture of 2 or more types.

  The water-soluble polymer is preferably obtained by polymerizing or copolymerizing a raw material monomer having a polymerizable substituent. The water-soluble polymer may be a homopolymer composed of a single monomer or a copolymer (copolymer) composed of two or more monomers.

  Specific examples of the raw material monomer include acrylic acid, methacrylic acid, crotonic acid, vinyl acetic acid, tiglic acid, 2-trifluoromethyl acrylic acid, itaconic acid, fumaric acid, maleic acid, citraconic acid, mesaconic acid, Examples thereof include carboxylic acids such as gluconic acid; sulfonic acids such as 2-acrylamido-2-methylpropanesulfonic acid; esters such as methyl acrylate, butyl acrylate, methyl methacrylate, and butyl methacrylate.

  In the water-soluble polymer, a part of acid groups such as a carboxylic acid group and a sulfonic acid group may form a salt. Examples of the salt include ammonium salt, alkali metal salt, alkylamine salt and the like. In the present invention, a water-soluble polymer having a part or all of substituents capable of forming a salt forming a salt is defined as a salt of the water-soluble polymer. For example, a polymer in which some or all of the carboxylic acid groups in polyacrylic acid (a homopolymer of acrylic acid) are substituted with an ammonium base is referred to as “polyacrylic acid ammonium salt”.

  The water-soluble polymer is an acrylic acid polymer (polymer obtained by polymerization or copolymerization containing a compound raw material monomer having a C═C—COOH skeleton as a monomer component) in terms of excellent planarization characteristics. preferable.

  Specific examples of the water-soluble polymer 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. Acid, poly (p-styrenecarboxylic acid), polyacrylic acid, polyacrylamide, aminopolyacrylamide, ammonium polyacrylate, sodium polyacrylate, polyamic acid, polyamic acid ammonium salt, polyamic acid sodium salt and polyglyoxylic acid Polycarboxylic acids such as alginic acid, pectinic acid, carboxymethylcellulose, agar, curdlan and pullulan, etc .; polyvinyl alcohol, polyvinylpyrrolidone and polychlore Vinyl polymers such as emissions and the like.

  The water-soluble polymer has a weight average molecular weight of 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 of the water-soluble polymer is not particularly limited, but is preferably 5 million or less from the viewpoint of solubility. When the water-soluble polymer has a weight average molecular weight of 500 or more, a high polishing rate is exhibited. The weight average molecular weight of the water-soluble polymer can be measured by gel permeation chromatography using a standard polystyrene calibration curve.

  The content of the water-soluble polymer is preferably 0.001 to 15 parts by mass, more preferably 0.005 to 10 parts by mass, and still more preferably 0.01 parts by mass in 100 parts by mass of the polishing liquid. Part to 5 parts by mass. When the content of the water-soluble polymer is 0.001 part by mass or more, the effect of suppressing erosion and seam is not lowered, and when it is 15 parts by mass or less, the stability of the abrasive grains contained in the polishing liquid is increased. There is no extreme decline.

<Organic solvent>
The polishing liquid may contain an organic solvent in addition to the metal oxide solubilizer and the oxidant described above. By adding the organic solvent, the wettability with respect to the surface to be polished is controlled, and the polishing rate for the interlayer insulating film can be improved. Although there is no restriction | limiting in particular as said organic solvent, The thing which can be arbitrarily mixed with water is preferable.

  Examples of the organic solvent include carbonates such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate; lactones such as butyrolactone and propyrolactone; ethylene glycol, propylene glycol, diethylene glycol, and dipropylene glycol. Glycols such as triethylene glycol and tripropylene glycol; derivatives of glycols 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 And 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 Glycol ethers such as ether, tripropylene glycol monobutyl ether, 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, triethylene glycol Glycol diethers such as propylene glycol dibutyl ether; Ethers such as tetrahydrofuran, dioxane, dimethoxyethane, polyethylene oxide, ethylene glycol monomethyl acetate, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate; methanol, ethanol, propanol, n -Bu Alcohols such as diol, n-pentanol, n-hexanol and isopropanol; ketones such as acetone and methyl ethyl ketone; amides such as phenol and dimethylformamide; N-methylpyrrolidone, ethyl acetate, ethyl lactate and sulfolanes Etc.

  Among these, glycol monoethers, alcohols, and carbonates are preferable. These organic solvents can be used individually by 1 type or in mixture of 2 or more types.

  The content of the organic solvent is preferably 0.1 parts by mass to 95 parts by mass, more preferably 0.2 parts by mass to 50 parts by mass, and still more preferably 0.5 parts by mass in 100 parts by mass of the polishing liquid. -10 parts by mass. When the content of the organic solvent is 0.1 part by mass or more, the wettability of the polishing liquid to the substrate is not lowered, and when it is 95 parts by mass or less, there is no possibility of ignition and it is preferable in terms of the manufacturing process.

<Quaternary phosphonium salt>
The polishing liquid of the present invention preferably further contains a quaternary phosphonium salt. When the polishing liquid contains a quaternary phosphonium salt, the polishing rate of the low-k film can be effectively controlled. Although there is no restriction | limiting in particular as said quaternary phosphonium salt, It is preferable that it is what is represented by following General formula (1).

(In the above formula (1), R represents a substituted or unsubstituted alkyl group, and X ⁻ represents an anion.)

  In the above formula (1), the substituted or unsubstituted alkyl group represented by R is preferably at least one selected from a linear alkyl group, a branched alkyl group, or an alkyl group having a benzene ring.

  Further, the alkyl group of R in the above formula (1) may be linear or branched as described above. The chain length of the alkyl group is preferably 1 to 14 carbon atoms, more preferably 4 to 7 carbon atoms. When the alkyl group chain length is 14 or less, the storage stability of the polishing liquid is not significantly reduced.

  The alkyl group of R in the above formula (1) may be an alkyl group having a benzene ring as described above, preferably a benzyl group or a phenyl group derivative, more preferably a benzyl group or a phenyl group. is there.

Moreover, the anion of X ^{− in} the above formula (1) is not particularly limited, but is a halogen ion (for example, F ⁻ , Cl ⁻ , Br ⁻ , I ⁻ ), hydroxide ion, nitrate ion, nitrous acid. Ion, hypochlorite ion, chlorite ion, chlorate ion, perchlorate ion, acetate ion, hydrogen carbonate ion, phosphate ion, sulfate ion, hydrogen sulfate ion, sulfite ion, thiosulfate ion, carbonate ion, etc. Can be mentioned.

  Examples of the quaternary phosphonium salt include methyltriphenylphosphonium salt, ethyltriphenylphosphonium salt, triphenylpropylphosphonium salt, isopropyltriphenylphosphonium salt, butyltriphenylphosphonium salt, amyltriphenylphosphonium salt, hexyltriphenylphosphonium salt. N-heptyltriphenylphosphonium salt, triphenyl (tetradecyl) phosphonium salt, tetraphenylphosphonium salt, benzyltriphenylphosphonium salt, (2-hydroxybenzyl) triphenylphosphonium salt, (2-chlorobenzyl) triphenylphosphonium salt, (4-chlorobenzyl) triphenylphosphonium salt, (2,4-dichlorobenzyl) phenylphosphonium salt, (4-nitrobenzyl) trif Nylphosphonium salt, 4-ethoxybenzyltriphenylphosphonium salt, (1-naphthylmethyl) triphenylphosphonium salt, (cyanomethyl) triphenylphosphonium salt, (methoxymethyl) triphenylphosphonium salt, (formylmethyl) triphenylphosphonium salt, Acetonyltriphenylphosphonium salt, phenacyltriphenylphosphonium salt, methoxycarbonylmethyl (triphenyl) phosphonium salt, ethoxycarbonylmethyl (triphenyl) phosphonium salt, (3-carboxypropyl) triphenylphosphonium salt, (4-carboxybutyl ) Triphenylphosphonium salt, (N-methyl-N-phenylamino) triphenylphosphonium salt, 2-dimethylaminoethyltriphenylphosphonium salt, tri E sulfonyl vinyl phosphonium salt, allyl triphenylphosphonium salt, triphenyl propargyl phosphonium salts and the like, which can be used by mixing one kind alone, or two or more kinds.

  Among these, butyltriphenylphosphonium salt, amyltriphenylphosphonium salt, hexyltriphenylphosphonium salt, n-butyltriphenylphosphonium salt, tetraphenylphosphonium salt, and benzyltriphenylphosphonium salt are preferable.

  The content of the quaternary phosphonium salt is preferably 0.0001 parts by mass to 1 part by mass, more preferably 0.001 parts by mass to 0.5 parts by mass, and still more preferably 0 in 100 parts by mass of the polishing liquid. 0.005 part by mass to 0.2 part by mass. When the content of the abrasive grains is 0.0001 part by mass or more, a decrease in the polishing rate suppression effect of the low-k film is suppressed, and when it is 1 part by mass or less, the storage stability of the polishing liquid is maintained. Can do.

<Water>
The water used in the present invention is not particularly limited, but pure water can be preferably used. Water should just be mix | blended as a remainder, and there is no restriction | limiting in particular in content rate.

  The polishing liquid of the present invention can be applied to the formation of a wiring layer in a semiconductor device. The film to be polished, which is an object to be polished, may include, for example, a conductive material layer, a barrier layer, and an interlayer insulating film.

  In general, in CMP under the same conditions, the polishing rate ratio of conductive material layer / barrier layer / interlayer insulating film is preferably in the range of 0.1-2 / 1 / 0.1-5, If is used, the polishing rate ratio can be within the above range.

As a method for confirming the polishing rate ratio, the target surface to be polished is subjected to chemical mechanical polishing for 60 seconds under the following polishing conditions, the substrate is cleaned under the following cleaning conditions, and then the difference in film thickness before and after polishing is usually determined. The method of calculating by using the film thickness measuring apparatus used (for example, Dainippon Screen Mfg. Co., Ltd. product name: Lambda Ace, VL-M8000LS) is used.
(Polishing conditions)
Polishing device: Single-sided metal film polishing machine (MIRRA, Applied Materials)
Polishing cloth: foamed polyurethane resin polishing cloth surface plate rotation speed: 93 times / minute Head rotation speed: 87 times / minute Polishing pressure: 14 kPa
Supply amount of polishing liquid: 200 ml / min

(Substrate cleaning conditions)
A sponge brush (made of polyvinyl alcohol resin) is pressed against the polished surface of the polished substrate, and the substrate and the sponge brush are rotated while supplying distilled water to the substrate, and washed for 60 seconds. Next, the sponge brush is removed, and distilled water is supplied to the polished surface of the substrate for 60 seconds. Finally, the substrate is rotated at high speed to blow off distilled water and dry the substrate.

[Polishing method]
The polishing method of the present invention fills at least the inside of the recess with an interlayer insulating film having a recess and a protrusion formed on the surface, a barrier layer covering the surface of the interlayer insulating film along the recess and the protrusion. And a first polishing step of polishing the conductive material layer of the substrate having the conductive material layer covering the barrier layer to expose the barrier layer on the convex portion, and the exposed barrier layer. And polishing using the CMP polishing liquid according to any one of claims 1 to 6 to expose a convex portion of the interlayer insulating film.

  When polishing the substrate using the polishing method, the polishing liquid described above is supplied between the film to be polished including the barrier layer formed on at least one surface of the substrate and the polishing cloth on the polishing surface plate. However, at least a part of the film to be polished is removed by relatively moving the substrate and the polishing surface plate in a state where the surface of the substrate on the surface provided with the film to be polished is pressed against a polishing cloth.

  Hereinafter, a series of steps for forming a wiring layer in a semiconductor device using the polishing method of the present invention will be described with reference to the drawings. As shown in FIG. 1A, the substrate before polishing is a barrier layer that covers the interlayer insulating film 1 along the irregularities on the surface of the interlayer insulating film 1 on the interlayer insulating film 1 having concave portions of a predetermined pattern. The conductive material layer 3 is formed on the barrier layer 2 so as to fill the inside of the recess.

  Examples of the interlayer insulating film 1 include a silicon-based film and an organic polymer film. Examples of the silicon-based coating include silicon oxide film, fluorosilicate glass, trimethylsilane, dimethoxydimethylsilane and tetraethoxysilane, which are used as starting materials, organosilicate glass, porous organosilicate glass, silicon oxynitride, hydrogenated silsesquioxane. Examples thereof include silica-based films such as sun, silicon carbide, and silicon nitride. Among these, organosilicate glass and porous organosilicate glass are preferable. The organic polymer film may be a wholly aromatic low dielectric constant interlayer insulating film 1 (low-k film). The dielectric constant of the organic polymer film is preferably 2.9 or less from the viewpoint of eliminating wiring delay.

  The interlayer insulating film 1 is formed by a CVD (chemical vapor deposition) method, a spin coating method, a dip coating method, or a spray method.

  Specific examples of the interlayer insulating film 1 include an interlayer insulating film in an LSI manufacturing process, particularly a multilayer wiring forming process.

  The barrier layer 2 is formed to prevent the conductive material from diffusing into the interlayer insulating film 1 and to improve the adhesion between the interlayer insulating film 1 and the conductive material layer 3.

  The composition of the barrier layer 2 is selected from tungsten compounds such as tungsten, tungsten nitride and tungsten alloys, titanium compounds such as titanium, titanium nitride and titanium alloys, tantalum compounds such as tantalum, tantalum nitride and tantalum alloys, ruthenium and ruthenium compounds. It is preferable that The barrier layer 2 may have a single layer structure composed of one kind of these or a laminated structure composed of two or more kinds.

  Examples of the conductive material layer 3 include a layer made of a material whose main component is a metal such as copper, copper alloy, copper oxide or copper alloy oxide, tungsten, tungsten alloy, silver, or gold. Among these, what has copper as a main component, such as copper, a copper alloy, an oxide of copper, and an oxide of a copper alloy, is preferable. As the conductive material layer 3, it is possible to use a film in which the material is formed by a known sputtering method or plating method.

  Hereinafter, embodiments of the polishing method of the present invention will be described along a series of steps for forming a wiring layer in a semiconductor device. First, a low-k film such as an organosilicate glass is formed as an interlayer insulating film 1 on a silicon substrate. Next, a concave portion (substrate exposed portion) having a predetermined pattern is formed on the surface of the interlayer insulating film 1 by a known means such as resist layer formation or etching, so that the interlayer insulating film 1 having the convex portion and the concave portion is obtained. On this interlayer insulating film 1, a barrier layer 2 made of tantalum or the like covering the interlayer insulating film 1 is formed by vapor deposition or CVD along the surface irregularities. Further, as shown in FIG. 1A, a conductive material layer 3 such as copper covering the barrier layer 2 is formed by vapor deposition, plating, CVD or the like so as to fill the concave portion.

  The interlayer insulating film 1 formed on the substrate has a thickness of about 0.01 μm to 2.0 μm, the barrier layer 2 has a thickness of about 0.01 μm to 2.5 μm, and the conductive material layer 3 has a thickness of about 0.1 μm. About 01 μm to 2.5 μm is preferable.

  Next, the conductive material layer 3 on the surface of the substrate is polished by CMP using, for example, a polishing liquid for the conductive material having a sufficiently high polishing rate ratio of the conductive material layer 3 / barrier layer 2. (First polishing step). As a result, the convex barrier layer 2 on the interlayer insulating film 1 is exposed on the surface, and a desired conductor pattern is obtained in which the conductive material layer 3 is left in the concave portion (FIG. 1B).

  As the polishing liquid for the conductive material having a sufficiently high polishing rate ratio of the conductive material layer 3 / barrier layer 2, for example, the polishing liquid described in Japanese Patent No. 3337464 can be used. When this polishing proceeds, a part of the convex barrier layer 2 may be polished simultaneously with the conductive material layer 3.

  The conductor pattern surface obtained by the first polishing step is polished using the polishing liquid of the present invention as the surface to be polished for the subsequent second polishing step. In the second polishing step, the polishing platen and the substrate are moved relatively while supplying the polishing liquid of the present invention between the polishing cloth and the substrate while the substrate is pressed onto the polishing cloth. Then, at least the barrier layer 2 exposed by the first polishing step is polished.

  In such a polishing process, as a polishing apparatus to be used, for example, when polishing with a polishing cloth, a polishing cloth is attached to a holder that can hold a substrate to be polished, a motor that can change the number of rotations, and the like. A general polishing apparatus having a surface plate can be used. There is no restriction | limiting in particular as said abrasive cloth, All can be used normally. For example, a nonwoven fabric, a polyurethane foam, a porous fluororesin, etc. are mentioned.

  When polishing using the polishing apparatus, there is no particular limitation on the polishing conditions. As the rotation speed of the surface plate, for example, a low rotation of 200 rpm or less is preferable so that the substrate does not jump out. The pressure applied to the polishing cloth of the semiconductor substrate having the surface to be polished is preferably 1 kPa to 100 kPa, and 5 kPa to 50 kPa in order to satisfy the in-surface uniformity of the polishing rate and the flatness of the pattern. More preferably.

  During the polishing process, the polishing liquid is continuously supplied between the polishing cloth and the film to be polished by a pump or the like. The supply amount of the polishing liquid is not particularly limited as long as the surface of the polishing cloth 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 spin drying or the like. At this time, in order to perform chemical mechanical polishing with the surface state of the polishing cloth always the same, it is preferable to perform a conditioning process of the polishing cloth before polishing. For example, the polishing cloth is conditioned with a treatment liquid containing at least water using a dresser with diamond particles. In addition, it is preferable to add a substrate cleaning step after polishing the substrate by the polishing method described later using the conditioned polishing cloth.

  The polishing liquid of the present invention can polish the conductive material layer 3, the barrier layer 2, and the interlayer insulating film 1, and in the second polishing step, at least the exposed barrier layer 2 is polished. As shown in FIG. 1C, the interlayer insulating film 1 under the convex barrier layer 2 is entirely exposed, leaving the conductive material layer 3 serving as a wiring layer in the concave portion, and the boundary between the convex portion and the concave portion. When the desired pattern in which the cross section of the barrier layer 2 is exposed is obtained, the polishing is finished.

  In order to ensure better flatness at the end of polishing, overpolishing (for example, when the time until a desired pattern is obtained in the second polishing step is 100 seconds, in addition to this polishing for 100 seconds) Polishing for an additional 50 seconds may be referred to as overpolishing 50%). In the case of overpolishing, a part of the interlayer insulating film 1 is also polished.

  After the interlayer insulating film 1 is formed on the metal wiring formed in this way, it is polished to obtain a smooth surface over the entire surface of the semiconductor substrate. By repeating this step a predetermined number of times, a semiconductor device having a desired number of wiring layers can be manufactured.

  The polishing liquid of the present invention can be used not only for polishing a metal film formed on a semiconductor substrate as described above but also for polishing a substrate such as a magnetic head.

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples without departing from the technical idea of the present invention. For example, the type of polishing liquid material and the blending ratio thereof may be other than the type and ratio described in the present embodiment, and the composition and structure of the polishing target may be other than those described in the present embodiment.

Example 1
[Preparation of polishing liquid (I) for CMP]
The composition of the polishing slurry for CMP is 5.0 parts by weight of colloidal silica having an average particle size of 60 nm, 0.5 parts by weight of malonic acid, 0.2 parts by weight of 30% hydrogen peroxide, and 0.2 parts by weight of 5-aminotetrazole. After stirring and mixing 0.1 parts by weight of polymethacrylic acid (weight average molecular weight 8000) and 94.0 parts by weight of water, the whole amount was filtered using a filter A (manufacturer nominal pore size: 0.2 μm) and polished for CMP. Liquid (I) was produced.

(Examples 2 to 6)
[Preparation of polishing liquids (II) to (VI) for CMP]
The CMP polishing liquids (II) to (VI) were prepared in the same manner as in Example 1 except that the composition of the CMP polishing liquid in Example 1 was changed as shown in Table 1. In Table 1, “-” indicates that it is not blended.

(Comparative Example 1)
[Preparation of CMP polishing liquid (VII)]
A polishing slurry (VII) for CMP was prepared in the same manner as in Example 1 except that the filter used in the filtration in Example 1 was replaced with the filter D (maker nominal pore size: 0.5 μm).

(Comparative Examples 2 to 4)
[Preparation of CMP polishing liquids (VIII) to (X)]
The CMP polishing liquids (VIII) to (X) were prepared in the same manner as in Comparative Example 1 except that the composition of the CMP polishing liquid in Comparative Example 1 (same as Example 1) was changed to the components shown in Table 2. did. In Table 2, “-” indicates that it is not blended.

[Evaluation of CMP polishing liquids (I) to (X)]
According to the following procedures, the number of coarse particles of CMP polishing liquids (I) to (X), the blanket substrate polishing rate, and the polishing scratches on the copper wiring pattern substrate were evaluated.

<Evaluation of the number of coarse particles>
First, the CMP polishing liquid (I) was subdivided into a 100 ml plastic bottle, set in a mix rotor, and stirred for 5 minutes at a rotation speed of 60 rpm / min. Thereafter, 5 ml of the CMP polishing liquid (I) was taken into a 5 ml syringe, and the entire amount taken out from the loop tube after bleeding the air was put into a particle size distribution measuring apparatus to measure the particle size distribution.

  From the measurement results obtained, the secondary particle size was divided into 6 stages of particle groups (a) to (f) as follows, and the number of particles was read for each group. This was repeated three times, and the average value was defined as the number of coarse particles. The number of coarse particles of CMP polishing liquids (II) to (X) was evaluated in the same manner.

Particle group (a): 0.56 μm or more, less than 0.64 μm Particle group (b): 0.64 μm or more, less than 0.79 μm Particle group (c): 0.79 μm or more, less than 0.98 μm Particle group (d) : 0.98 μm or more and less than 1.43 μm Particle group (e): 1.43 μm or more and less than 3.99 μm Particle group (f): 3.99 μm or more

The measurement conditions for evaluating the number of coarse particles are as follows.
(Measurement condition)
Measuring device: Particle size distribution measuring device (manufactured by Particle Sizing System, product name “Accumizer 780”)
data collection time: 60 sec
number channels: 128
Diluent flow rate: 60 ml / min
target concentration: 3000 parts / ml
# Of samples: 1
time between samples: 1 min
bakground threshold: 50 parts / sec
initial 2 ^nd -stage dilution factor: 10
vessel flush time: 80 sec
2 ^nd -stage mixer volume: 8ml
sample flow time: 10 sec
sum mode: min.
diameter: 0.56 μm

<Evaluation of polishing rate and polishing scratches>
The following substrates (a) to (e) were used for the evaluation of the polishing rate of the blanket substrate and the polishing scratches on the patterned substrate with copper wiring.
Blanket substrate (a): A silicon substrate on which tantalum nitride (thickness: 200 nm) is formed by sputtering.
Blanket substrate (b): A silicon substrate on which copper (thickness: 1000 nm) is formed by a plating method.
Blanket substrate (c): A silicon substrate on which an organosilicate glass (thickness: 1000 nm) is formed by a CVD method.
Blanket substrate (d): A silicon substrate on which silicon dioxide (thickness: 1000 nm) is formed by CVD.
Pattern substrate with copper wiring (e): A silicon substrate in which an organosilicate glass having a thickness of 500 nm is formed as the interlayer insulating film 1 and tantalum nitride having a thickness of 35 nm and copper having a thickness of 1100 nm are formed thereon. Also, a patterned substrate with copper wiring having a minimum copper wiring width of 0.18 μm.

(Blanket substrate polishing process)
Using the blanket substrates (a) to (d), chemical mechanical polishing was performed for 60 seconds under the following polishing conditions with CMP polishing liquids (I) to (X).

(Polishing process of patterned substrate with copper wiring)
The copper film other than the groove of the patterned substrate with copper wiring (e) is polished by a known CMP method using a copper polishing liquid to expose the convex barrier layer on the surface to be polished, and then polished for CMP. Chemical mechanical polishing was performed with the liquids (I) to (X) for 90 seconds under the following polishing conditions.

(Polishing conditions)
Polishing equipment: Single-sided metal film polishing machine (Applied Materials, product name “MIRRA”)
Abrasive cloth: Foamed polyurethane resin abrasive cloth surface plate rotational speed: 93 times / minute Head rotational speed: 87 times / minute Polishing pressure: 14 kPa
Supply amount of polishing liquid: 200 ml / min

(Substrate cleaning process)
A sponge brush (made of polyvinyl alcohol resin) was pressed against the surface to be polished of the substrate polished under the above polishing conditions, and the substrate and the sponge brush were rotated while supplying distilled water to the substrate, and washed for 60 seconds. Next, the sponge brush was removed, and distilled water was supplied to the polished surface of the substrate for 60 seconds. Finally, the substrate was rotated at high speed to blow off distilled water and dried.

(Blanket substrate polishing rate)
For the cleaned blanket substrates (a) and (b), the difference in film thickness before and after polishing was measured using a metal film thickness measuring device (product name “VR-120 / 08S” manufactured by Hitachi Kokusai Electric Co., Ltd.). The polishing rate was determined from the obtained results. Moreover, about the cleaned blanket board | substrate (c) and (d), the film thickness difference before and behind grinding | polishing using the film thickness measuring apparatus (Dainippon Screen Mfg. Co., Ltd. product name "Lambda ace, VL-M8000LS"). Was measured, and the polishing rate was determined from the results obtained. The results are shown in Tables 1 and 2.

(Polishing scratches on a patterned substrate with copper wiring)
Polishing scratches on the patterned substrate with copper wiring (e) treated and cleaned under the above polishing conditions were evaluated by the following procedure. First, the pattern board (e) with copper wiring was subjected to defect inspection using a defect inspection apparatus (product name “ComPlus 3T” manufactured by Applied Materials). The inspected L / S patterns are in two places, a repeated pattern portion of L / S = 0.18 μm / 0.18 μm and a repeated pattern portion of L / S = 0.25 μm / 0.25 μm. The area of the inspected L / S pattern is 1.25 mm × 1.80 mm. The number of chips inspected is 57 chips per wafer.

Next, each defect is observed using a scanning electron microscope (product name “SEM Vision G3”, manufactured by Applied Materials) as a defect observing device, and the polishing scratches and other defects are identified. The number of occurrences was determined.

  As shown in Table 1, in the polishing slurry for CMP of Examples 1 to 6 including coarse particles having a predetermined particle size distribution in the polishing solution, the number of polishing scratches on the pattern wafer is 1 / wafer or less, and the polishing scratches It is clear that the number of occurrences is extremely small.

  On the other hand, as shown in Table 2, the polishing slurry for CMP of Comparative Example 4 in which the number of particles in the particle groups (a) to (f) contained in 1 ml of the polishing slurry for CMP is not less than the range specified in the present invention. Then, it is clear that the number of polishing scratches on the pattern wafer is 65 / wafer, and the number of polishing scratches generated is extremely large as compared with the CMP polishing liquids of Examples 1 to 6.

  As described above, in the polishing slurry for CMP according to the present invention, by appropriately controlling the number of coarse particles according to the secondary particle diameter, an excellent polishing rate can be obtained and the number of occurrence of polishing flaws can be dramatically increased. Clearly, it is possible to provide a polishing slurry for CMP that can be reduced and can produce semiconductor devices as designed without film defects or structural changes. That is, it is apparent that the CMP polishing liquid of the present invention can suppress problems such as short circuit, disconnection, yield, and reduced reliability in the manufacture of high-performance semiconductor devices in which formation of fine metal wiring is indispensable.

1 Interlayer insulation film 2 Barrier layer 3 Conductive material layer

Claims (16)

It contains abrasive grains, a metal oxide solubilizer, an oxidizer, and water, has a pH of 4 or less, and a particle size distribution measured using a light scattering method and a light shielding method has the following conditions (a) and ( Polishing liquid for CMP satisfying b).
Condition (a): The number of particles having a particle diameter of 0.56 μm or more and less than 0.64 μm is less than 1000 / ml Condition (b): The number of particles having a particle diameter of 0.64 μm or more and less than 0.79 μm is 600 Less than pieces / ml The polishing slurry for CMP according to claim 1, wherein the particle size distribution further satisfies the following condition (c).
Condition (c): The number of particles having a particle diameter of 0.79 μm or more and less than 0.98 μm is less than 500 / ml. The polishing slurry for CMP according to claim 2, wherein the particle size distribution further satisfies the following condition (d).
Condition (d): The number of particles having a particle diameter of 0.98 μm or more and less than 1.43 μm is less than 300 / ml. The polishing slurry for CMP according to claim 3, wherein the particle size distribution further satisfies the following condition (e).
Condition (e): The number of particles having a particle size of 1.43 μm or more and less than 3.99 μm is less than 150 / ml. The polishing slurry for CMP according to claim 4, wherein the particle size distribution further satisfies the following condition (f).
Condition (f): The number of particles having a particle size of 3.99 μm or more is less than 50 / ml. The polishing for CMP according to any one of claims 1 to 5, wherein the abrasive is at least one selected from the group consisting of silica, alumina, ceria, titania, zirconia, germania, and modified products thereof. liquid. The polishing liquid for CMP according to any one of claims 1 to 6, wherein a secondary particle diameter of the abrasive grains is 10 nm or more and 200 nm or less. The polishing slurry for CMP according to any one of claims 1 to 7, wherein a content of the abrasive grains is 0.2 to 50 parts by mass in 100 parts by mass of the polishing slurry for CMP. The polishing slurry for CMP according to any one of claims 1 to 8, further comprising a quaternary phosphonium salt. The quaternary phosphonium salt is at least one selected from butyltriphenylphosphonium salt, amyltriphenylphosphonium salt, hexyltriphenylphosphonium salt, n-heptyltriphenylphosphonium salt, tetraphenylphosphonium salt and benzyltriphenylphosphonium salt. The polishing slurry for CMP according to claim 9. An interlayer insulating film having concave and convex portions formed on the surface; a barrier layer covering the surface of the interlayer insulating film along the concave and convex portions; and at least filling the concave portion and covering the barrier layer A first polishing step of polishing the conductive material layer of the substrate having a conductive material layer to expose the barrier layer on the convex portion;
Polishing the exposed barrier layer to expose the convex portions of the interlayer insulating film;
The polishing liquid for CMP according to any one of claims 1 to 10, which is used in the second polishing step of the two-stage polishing method having the following. An interlayer insulating film having concave and convex portions formed on the surface; a barrier layer covering the surface of the interlayer insulating film along the concave and convex portions; and at least filling the concave portion and covering the barrier layer A first polishing step of polishing the conductive material layer of the substrate having a conductive material layer to expose the barrier layer on the convex portion;
A second polishing step of polishing the exposed barrier layer using the CMP polishing liquid according to any one of claims 1 to 10 to expose a convex portion of the interlayer insulating film;
A polishing method comprising: The polishing method according to claim 12, wherein the conductive material layer includes at least one conductive material selected from copper, a copper alloy, a copper oxide, and a copper alloy oxide. The polishing method according to claim 12 or 13, wherein the barrier layer includes at least one selected from tantalum, a tantalum compound, titanium, a titanium compound, tungsten, a tungsten compound, ruthenium, and a ruthenium compound. The polishing method according to claim 12, wherein the interlayer insulating film is a low-k film. The polishing method according to claim 15, wherein the low-k film is a silicon-based film or an organic polymer film having a dielectric constant of 2.9 or less.