JP2008109081A - Polishing composition and polishing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing composition of which a polishing speed with an insulating film of low specific inductive capacity can be increased even if polishing an object which uses an insulating film material of low specific inductive capacity. <P>SOLUTION: In a manufacturing method of a semiconductor device, an embedded wiring is formed, through a barrier metal layer, in an insulating film which has an organic siloxane structure with specific inductive capacity being 3.0 or less, to provide an object to be polished. The insulating film of the object is polished chemically and mechanically using the polishing composition which contains silica particles of primary particle size 10-80 nm, benzotriazol dielectrics, and inorganic salt of 1-10 mass%, with pH being 8-11. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a polishing method and a polishing composition for performing chemical mechanical planarization at the time of polishing a semiconductor device, for example.

In the development of a semiconductor device represented by a semiconductor integrated circuit (hereinafter referred to as LSI), in recent years, in order to reduce the size and increase the speed, there has been a demand for higher density and higher integration by miniaturizing and stacking wiring. In order to increase the speed of the LSI, an interlayer insulating film used in the LSI is required to have a material with a low dielectric constant and a low inter-wiring capacitance.
Conventionally, SiO ₂ is used as an interlayer insulating film material of a semiconductor device, and its relative dielectric constant is about 3.8 to 4.2. However, as the line width becomes narrower, the dielectric constant of the interlayer insulating film material must be lowered. For example, an element having a line width of 130 nm requires a material having a relative dielectric constant of about 2.5 to 3.0. And

As a material used to form an insulating film having a low relative dielectric constant (Low-k film) as an interlayer insulating film, a SiOC-based material (for example, a plurality of Si-C or SiOC containing Si-H bonds) is used. Organic-inorganic hybrid materials such as MSQ are known.
Specifically, as a material used for forming an insulating film having a relative dielectric constant, there are HSG-R7 (Hitachi Chemical Industries), BLACKDIAMOND (Applied Materials, Inc.) and the like in the SiOC system.

These Low-k films need to be flattened for LSI miniaturization, and a technique for that purpose is required.
As a method for planarizing the Low-k film, Patent Document 1 discloses a planarization method using a CMP technique, that is, a method of polishing using cerium oxide particles as abrasive grains. Here, CMP is an abbreviation for Chemical Mechanical Polishing. Generally, a polishing pad is attached on a circular polishing platen (platen), and the surface of the polishing pad is immersed in a polishing solution. While pressing the surface of the substrate (wafer) against the pad and applying a predetermined pressure (polishing pressure) from the back side, both the polishing platen and the substrate are rotated, and the surface of the surface to be polished is caused by the generated mechanical friction. Flattening.
However, the method of polishing using cerium oxide particles as the abrasive grains is slow in polishing rate, and the insulating film between the metal wirings is polished more than necessary, and the surface of the plurality of wiring metal surfaces forms dish-shaped recesses ( Erosion) was easy to occur.
JP 2000-286255 A

In order to increase the operation speed of LSIs that are becoming finer, it is necessary to reduce the inter-wiring capacitance by reducing the dielectric constant of the insulating film. An insulating film having a low relative dielectric constant has a relatively low mechanical strength, and it has been difficult to increase the polishing rate without giving such an insulating film damage such as scratches.
The present invention relates to a polishing composition capable of increasing the polishing rate of a low dielectric constant insulating film and a polishing using the same even when an object to be polished using an insulating film material having a low dielectric constant is polished. The object is to provide a method and to achieve the object.

Specific means for solving the above problems are as follows.
(1) In the method of manufacturing a semiconductor device, the insulating film of the object to be polished is formed by forming a buried wiring through an insulating film having an organosiloxane structure and a relative dielectric constant of 3.0 or less via a barrier metal layer. A polishing composition used for mechanical polishing, comprising silica particles having a primary particle diameter of 10 to 80 nm, a benzotriazole compound, and 1 to 10% by mass of an inorganic salt, and having a pH of 8 to 11 It is the polishing composition which is the range.
(2) The polishing composition according to (1), wherein the concentration of the silica particles is 0.5 to 15% by mass.
(3) The benzotriazole compound is 1,2,3-benzotriazole (BTA), 5,6-dimethyl-1,2,3-benzotriazole (DBTA), 1- (1,2-dicarboxyethyl) It is at least one selected from benzotriazole (DCEBTA), 1- [N, N-bis (hydroxyethyl) aminomethyl] benzotriazole (HEABTA), and 1- (hydroxymethyl) benzotriazole (HMBTA). The polishing composition according to (1) or (2).
(4) The polishing composition according to any one of (1) to (3), wherein the inorganic salt is at least one selected from an ammonium salt, a sodium salt, and a potassium salt. .
(5) The polishing composition according to any one of (1) to (4) above, which does not contain an aromatic ring compound other than the benzotriazole compound.
(6) The polishing composition is supplied to the polishing pad on the polishing surface plate, and the polishing surface is rotated while the polishing pad is in contact with the insulating film of the object to be polished, and the contact surface is rotated to perform polishing. A method of polishing, wherein the insulating film is an insulating film of the object to be polished formed by forming an embedded wiring through a barrier metal layer in an insulating film having an organic siloxane structure and a relative dielectric constant of 3.0 or less, And it is a polishing method, wherein the polishing composition is the polishing composition according to any one of the above (1) to (5).
(7) The polishing method according to (6) above, wherein a load (polishing pressure) when the polishing pad is brought into contact with the insulating film of the object to be polished is 0.69 to 21.6 KPa.
(8) The above (6) or (7), wherein the supply flow rate when supplying the polishing composition to the polishing pad on the polishing surface plate is 0.035 to 0.60 ml / min · cm ^2. ).

  According to the present invention, a polishing composition capable of increasing the polishing rate of a low relative dielectric constant insulating film even when polishing an object to be polished using an insulating film material having a low relative dielectric constant, and the same are used. Can be provided.

The polishing composition of the present invention is a method of manufacturing a semiconductor device, comprising: an insulating film having an organosiloxane structure having a relative dielectric constant of 3.0 or less and an embedded wiring formed through a barrier metal layer; A polishing composition used for chemically and mechanically polishing the insulating film, comprising silica particles having a primary particle size of 10 to 80 nm, a benzotriazole compound, and 1 to 10% by mass of an inorganic salt. The pH is in the range of 8-11.
Hereinafter, specific embodiments of the present invention will be described.

[Low dielectric constant insulating film]
The insulating film (interlayer insulating film) in the present invention is an insulating film having an organosiloxane structure and a low relative dielectric constant of 3.0 or less (hereinafter also referred to as “low-k film in the present invention”). .
The material used for forming the insulating film having a low relative dielectric constant is not particularly limited as long as it is a material capable of forming an insulating film having an organosiloxane structure and a relative dielectric constant of 3.0 or less.
An organic-inorganic hybrid material such as SiOC having an organosiloxane structure (for example, SiOC including a plurality of Si-C or Si-H bonds), MSQ, or the like is preferable.
Among these, it is preferable to include an organosiloxane structural unit represented by the following general formula (I).

In the general formula (I), R ¹ represents a hydrogen atom, a hydrocarbon group, or OR ³ , and R ² represents a hydrocarbon group or OR ⁴ . R ³ and R ⁴ each independently represents a hydrocarbon group.
In the general formula (I), examples of the hydrocarbon group represented by R ^{1 to} R ⁴ include an aliphatic hydrocarbon group and an aromatic hydrocarbon group.

  Examples of materials that can be used for forming the insulating film having a low relative dielectric constant include, for example, HSG-R7 (manufactured by Hitachi Chemical Co., Ltd .: relative dielectric constant 2.8), BLACKDIAMOND (Applied Materials, Inc.) Manufactured by: relative dielectric constant 2.4-3.0), Coral (manufactured by Novellus Systems, Inc .: relative dielectric constant 2.4-2.7), Aurora (manufactured by Japan IMS: relative dielectric constant 2.7) Examples of the MSQ system include OCDT-9 (manufactured by Tokyo Ohka Kogyo Co., Ltd .: relative dielectric constant 2.7), LKD-T200 (manufactured by JSR: dielectric constant 2.5 to 2.7), HOSP (Honeywell Electronic Materials). Manufactured: relative dielectric constant 2.5), HSG-RZ25 (manufactured by Hitachi Chemical Co., Ltd .: relative dielectric constant 2.5), OCLT-31 (Tokyo) Industrial: relative dielectric constant 2.3), LKD-T400 (manufactured by JSR: relative dielectric constant 2.0-2.2), HSG-6111X (manufactured by Hitachi Chemical Co., Ltd .: relative dielectric constant 2.1), ALCAP-S (Asahi Kasei Kogyo: relative dielectric constant 1.8-2.3), OCLT-77 (Tokyo Ohka Kogyo: relative dielectric constant 1.9-2.2), HSG-6211X (Hitachi Chemical Industries: relative dielectric constant) 2.4), silica aerogel (manufactured by Kobe Steel: relative dielectric constant 1.1 to 1.4), and the like, but are not limited thereto.

  The material that can form the insulating film having a low relative dielectric constant may be used alone or in combination. Furthermore, the insulating film formed of these materials may have minute holes.

In the present invention, the insulating film may be formed by plasma CVD or spin coating.
The dielectric constant of the insulating film in the present invention is required to be 3.0 or less, but is preferably low, and particularly preferably 1.8 to 2.8.
In the present invention, the relative dielectric constant is measured by a measurement method using a mercury probe for a solid film, and the relative dielectric constant of an insulating film provided with wiring is measured by a Precision 4284A LCR meter (manufactured by Agilent Technology). Can do. For example, in an element having a line width of 90 nm or less, the relative dielectric constant is preferably less than 2.4.

[Polishing composition]
The polishing composition of the present invention comprises (a) silica particles, (b) a benzotriazole compound, and (c) an inorganic salt.
[(A) Silica particles]
The polishing composition of the present invention contains silica particles having a primary particle size of 10 to 80 nm as a constituent component. The silica particles are contained as abrasive particles. Examples of the silica particles in the present invention include precipitated silica, fumed silica, colloidal silica, and synthetic silica. Among these, colloidal silica or fumed silica is preferable from the viewpoint of polishing rate, and colloidal silica is more preferable.

Examples of the method for producing the colloidal silica particles include silicon such as Si (OC ₂ H ₅ ) ₄ , Si (sec-OC ₄ H ₉ ) ₄ , Si (OCH ₃ ) ₄ , Si (OC ₄ H ₉ ) _4. It can be obtained by hydrolyzing an alkoxide compound by a sol-gel method. Such colloidal silica particles have a very sharp particle size distribution.

  Examples of the method for producing the fumed silica particles include a high-temperature hydrolysis method in an oxyhydrogen flame of silicon tetrachloride.

  The primary particle size of the silica particles in the present invention is a particle size cumulative curve showing the relationship between the particle size of the silica particles and the cumulative frequency obtained by integrating the number of particles having the particle size, and the cumulative frequency of this curve is 50%. It means the particle diameter at a point. The particle diameter of the silica particles represents an average particle diameter determined in the particle size distribution obtained from the dynamic light scattering method. As a measuring device for obtaining the particle size distribution, for example, LB-500 manufactured by Horiba Ltd. is used.

In this invention, although the primary particle diameter of the silica particle to be contained needs to be 10-80 nm, it is preferable that it is 10-60 nm, More preferably, it is 10-30 nm. Particles of 10 nm or more are preferable for the purpose of achieving a sufficient polishing speed. Further, the particle diameter is preferably 80 nm or less for the purpose of not generating excessive frictional heat during polishing.
In this invention, a silica particle can also be used individually by 1 type, and can also be used in combination of 2 or more type.

In this invention, it is preferable that the density | concentration of the silica particle contained is contained in the ratio for 0.5-15 mass% in the polishing composition at the time of using for grinding | polishing, More preferably, it is 1-10 mass. %. The concentration is preferably 0.5% by mass or more from the viewpoint of achieving a sufficient polishing speed. Further, from the viewpoint of suppressing the generation of excessive frictional heat during polishing, the concentration is preferably 15% by mass or less. Here, being contained in the polishing composition at a ratio of 0.5 to 15% by mass means that 5 to 150 g is contained in 1 L of the polishing composition.
Further, the polishing composition of the present invention can be used as it is or in a diluted form, but even when the polishing composition is used after being diluted, the concentration in the polishing composition dilution liquid at the time of use is determined by polishing. This is the same as the concentration range of the composition for use, and the preferred range is also the same.

[(B) Benzotriazole compound]
The polishing liquid of the present invention contains a benzotriazole compound.
In the present invention, 1,2,3-benzotriazole (BTA), 5,6-dimethyl-1,2,3-benzotriazole (DBTA), 1- (1,2-dicarboxyethyl) is used as the benzotriazole compound. ) Containing at least one selected from benzotriazole (DCEBTA), 1- [N, N-bis (hydroxyethyl) aminomethyl] benzotriazole (HEABTA), 1- (hydroxymethyl) benzotriazole (HMBTA) .
By using a specific compound as the benzotriazole compound, the polishing rate ratio (selection ratio) between the insulating film having a low relative dielectric constant and the embedded wiring can be set to a suitable value.

The benzotriazole compounds used in the present invention may be used alone or in combination of two or more.
The concentration of the benzotriazole compound is not particularly limited, but is preferably 0.01% by mass or more and 0.2% by mass or less in the polishing composition when used for polishing, more preferably 0. It is 0.05 mass% or more and 0.2 mass% or less.
The polishing composition of the present invention preferably contains no aromatic ring compound other than the benzotriazole compound. In the present invention, examples of the aromatic ring compound other than the benzotriazole compound include triazole and tetrazole. By not containing an aromatic ring compound other than the benzotriazole compound, the polishing rate ratio (selection ratio) of the embedded wiring can be set to a suitable value.

[(C) inorganic salt]
The polishing composition of this invention contains 1-10 mass% inorganic salt in the polishing composition at the time of using for grinding | polishing. The said addition amount means containing 10-100g of inorganic salts with respect to 1L of polishing compositions at the time of using for grinding | polishing. By including the inorganic salt in the above range, the polishing rate of the insulating film having a low relative dielectric constant can be improved.
In this invention, it is preferable that content of an inorganic salt is 1-5 mass%, and it is more preferable that it is 2-3 mass%.

  The inorganic salt that can be used in the present invention is not particularly limited, but is preferably at least one selected from ammonium salts, sodium salts, and potassium salts from the viewpoint of detergency. Of these, ammonium salts and potassium salts are more preferable, and ammonium salts are more preferable.

There is no restriction | limiting in particular as an anion of the inorganic salt which can be used for this invention, For example, a chloride ion, a nitrate ion, a sulfate ion, a phosphate ion etc. can be mentioned.
Specific examples of inorganic salts that can be used in the present invention include ammonium nitrate, ammonium sulfate, ammonium phosphate, ammonium chloride, sodium nitrate, sodium sulfate, sodium chloride, potassium nitrate, potassium sulfate, and potassium chloride.
Among these, ammonium nitrate is preferable from the viewpoint of suppressing generation of various defects accompanying CMP.
The said inorganic salt in this invention can be used individually by 1 type, or can also be used in combination of 2 or more type.

[PH]
The polishing composition of the present invention is required to have a polishing composition having a pH of 8 to 11 when used for polishing, and preferably has a pH of 9 to 11, and 9.5. More preferably, it is ˜10.5.
Alkali / acid or buffering agents can be used to adjust the pH to the preferred range. The polishing composition of the present invention exhibits an effect of improving the polishing rate when the pH of the polishing composition when used for polishing is within this range.

  Examples of alkali / acid or buffering agents include non-metallic alkaline agents such as organic ammonium hydroxides such as ammonia, ammonium hydroxide and tetramethylammonium hydroxide, alkanolamines such as diethanolamine, triethanolamine and triisopropanolamine. , Alkali metal hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide, inorganic acids such as nitric acid, sulfuric acid and phosphoric acid, carbonates such as sodium carbonate, phosphates such as trisodium phosphate, boric acid Preferred examples include salts, tetraborate and hydroxybenzoate. Particularly preferred alkali agents are ammonium hydroxide, potassium hydroxide, lithium hydroxide and tetramethylammonium hydroxide.

  The addition amount of the alkali / acid or the buffer may be an amount that maintains the pH within a preferable range, and is preferably 0.0001 g to 1 g in 1 L of the polishing composition when used for polishing. More preferably, it is 0.001 g to 0.1 g.

〔Oxidant〕
The polishing composition of the present invention preferably contains a compound (oxidant) capable of oxidizing the metal to be polished.
Examples of the oxidizing agent include hydrogen peroxide, peroxide, nitrate, iodate, periodate, hypochlorite, chlorite, chlorate, perchlorate, persulfate, Examples thereof include dichromate, permanganate, ozone water, silver (II) salt, and iron (III) salt. Among them, hydrogen peroxide is preferably used.
Examples of the iron (III) salt include iron (III) in addition to inorganic iron (III) salts such as iron nitrate (III), iron chloride (III), iron sulfate (III) and iron bromide (III). Organic complex salts are preferably used.

  The addition amount of the oxidizing agent is preferably 0.01 mol to 1 mol, and particularly preferably 0.05 mol to 0.6 mol in 1 L of the polishing liquid used for polishing.

[Chelating agent]
The polishing composition of the present invention preferably contains a chelating agent as necessary in order to reduce adverse effects such as mixed polyvalent metal ions.
Chelating agents include general water softeners and related compounds that are calcium and magnesium precipitation inhibitors, such as nitrilotriacetic acid, diethylenetriaminepentaacetic acid, ethylenediaminetetraacetic acid, N, N, N-trimethylenephosphonic acid, ethylenediamine -N, N, N ', N'-tetramethylenesulfonic acid, transcyclohexanediaminetetraacetic acid, 1,2-diaminopropanetetraacetic acid, glycol etherdiaminetetraacetic acid, ethylenediamine orthohydroxyphenylacetic acid, ethylenediamine disuccinic acid (SS form) ), N- (2-carboxylateethyl) -L-aspartic acid, β-alanine diacetic acid, 2-phosphonobutane-1,2,4-tricarboxylic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, N, N '-Bis (2-hydroxybenzyl) Ethylenediamine -N, N'-diacetic acid, 1,2-dihydroxy-4,6-disulfonic acid.

[Organic acid]
The polishing liquid in the present invention can further contain an organic acid.
The organic acid here is a compound having a structure different from that of an oxidizing agent for oxidizing a metal, and does not include an acid that functions as the above-described oxidizing agent. The acid here has an action of promoting oxidation, adjusting pH, and buffering agent.
As an organic acid in this invention, what was chosen from the following groups is preferable.
That is, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, 2-methylbutyric acid, n-hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid, 4-methylpentanoic acid, n-heptanoic acid, 2-methyl Hexanoic acid, n-octanoic acid, 2-ethylhexanoic acid, benzoic acid, glycolic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, phthalic acid, apple Examples thereof include acids, tartaric acid, citric acid, lactic acid, and salts thereof such as ammonium salts and alkali metal salts, sulfuric acid, nitric acid, ammonia, ammonium salts, and mixtures thereof.
Among these, formic acid, malonic acid, malic acid, tartaric acid, and citric acid are suitable for laminated films including at least one metal layer selected from copper, copper alloys, and copper or copper alloy oxides. is there.

Preferred examples of the organic acid in the present invention include amino acids.
As this amino acid and the like, water-soluble ones are preferable, and those selected from the following groups are more suitable.
That is, for example, glycine, L-alanine, β-alanine, L-2-aminobutyric acid, L-norvaline, L-valine, L-leucine, L-norleucine, L-isoleucine, L-alloisoleucine, L-phenylalanine, L-proline, sarcosine, L-ornithine, L-lysine, taurine, L-serine, L-threonine, L-allothreonine, L-homoserine, L-tyrosine, 3,5-diiodo-L-tyrosine, β- ( 3,4-dihydroxyphenyl) -L-alanine, L-thyroxine, 4-hydroxy-L-proline, L-cystine, L-methionine, L-ethionine, L-lanthionine, L-cystathionine, L-cystine, L- Cysteic acid, L-aspartic acid, L-glutamic acid, S- (carboxymethyl) -L-cysteine, 4- Aminobutyric acid, L-asparagine, L-glutamine, azaserine, L-arginine, L-canavanine, L-citrulline, δ-hydroxy-L-lysine, creatine, L-quinurenin, L-histidine, 1-methyl-L-histidine It is desirable to contain at least one of amino acids such as 3-methyl-L-histidine, ergothioneine, L-tryptophan, actinomycin C1, apamin, angiotensin I, angiotensin II and antipine.
Among these, malic acid, tartaric acid, citric acid, glycine, and glycolic acid are particularly preferable in that the etching rate can be effectively suppressed while maintaining a practical CMP rate.

  The amount of the organic acid added is preferably 0.0005 mol to 0.5 mol, more preferably 0.005 mol to 0.3 mol, and more preferably 0.01 mol to 1 mol in 1 L of the polishing liquid used for polishing. The amount is particularly preferably 0.1 mol. That is, the addition amount of the organic acid is preferably 0.5 mol or less from the viewpoint of suppressing etching, and 0.0005 mol or more is preferable for obtaining a sufficient effect.

[Other additives]
The polishing composition of the present invention can contain a known additive such as a surfactant, if necessary.

[Polishing method]
In the polishing method of the present invention, the polishing composition is supplied to a polishing pad on a polishing surface plate, and the polishing surface plate is rotated while the polishing pad is in contact with the insulating film of the object to be polished. A polishing method for polishing by moving, wherein the insulating film has an organosiloxane structure and has an insulating film having a relative dielectric constant of 3.0 or less and an embedded wiring is formed through a barrier metal layer to insulate the object to be polished It is a film | membrane and the said polishing composition consists of the polishing composition of this invention, It is characterized by the above-mentioned. Thereby, even when an insulating film having a low relative dielectric constant is polished, the polishing rate can be increased without damaging the insulating film such as scratches.

In the polishing method of the present invention, the insulating film having an organosiloxane structure and a relative dielectric constant of 3.0 or less is the same as that described in the above-mentioned section of the polishing composition of the present invention, and preferred examples are also included. The same.
The polishing composition used in the polishing method of the present invention is the same as the above-described polishing composition of the present invention, and preferred examples are also the same.

The polishing composition of the present invention comprises: 1. A concentrated liquid which is diluted by adding water or an aqueous solution when used. 2. When each component is prepared in the form of an aqueous solution described in the next section, these are mixed, and if necessary diluted with water to make a working solution. It may be prepared as a working solution.
The polishing composition (polishing liquid) in any case is applicable to the polishing method using the polishing composition of the present invention.

  As an apparatus used for polishing, a holder for holding an object to be polished (for example, a wafer on which a conductive material film is formed) having a surface to be polished and a polishing pad are attached (a motor capable of changing the number of rotations). Etc.) and a general polishing apparatus having a polishing surface plate.

  Specific examples of the polishing apparatus include: Mirra Mesa CMP, Reflexion CMP (manufactured by Applied Materials), FREX200, FREX300 (manufactured by Ebara Corporation), NPS3301, NPS2301 (manufactured by Nikon), A-FP-310A, A-FP- 210A (manufactured by Tokyo Seimitsu), 2300 TERES (manufactured by Ram Research), Momentum (manufactured by Speedfam IPEC), and the like.

As the polishing pad, a general nonwoven fabric, foamed polyurethane, porous fluororesin, or the like can be used, and there is no particular limitation. Details will be described later.
The polishing conditions are not limited, but the rotation speed of the polishing surface plate is preferably a low rotation of 200 rpm or less so that the object to be polished does not pop out. The pressing pressure of the object to be polished having the surface to be polished (film to be polished) against the polishing pad is preferably 0.68 to 34.5 KPa, more preferably 0.69 to 21.6 KPa, and polishing. In order to satisfy the in-plane uniformity of the object to be polished and the flatness of the pattern, it is more preferably 3.40 to 20.7 KPa.

  During polishing, the polishing composition can be continuously supplied to the polishing pad with a pump or the like. After the polishing is completed, the object to be polished can be thoroughly washed in running water, and then dried after removing water droplets adhering to the object to be polished using a spin dryer or the like.

In the present invention, the 1. When diluting the concentrated solution as in the above method, the following aqueous solutions can be used. The aqueous solution is water containing at least one of an oxidizing agent, an organic acid, an additive, and a surfactant in advance, and the components contained in the aqueous solution and the concentrated solution to be diluted are contained. The component obtained by adding up the components to be used is a component of the polishing composition (use liquid) used for polishing.
Thus, when the concentrate is diluted with an aqueous solution and used, components that are difficult to dissolve can be added later in the form of an aqueous solution, so that a more concentrated concentrate can be prepared.

  In addition, as a method of diluting by adding water or an aqueous solution to the concentrated liquid, a pipe for supplying a concentrated liquid having a concentrated composition and a pipe for supplying water or an aqueous solution are merged and mixed, mixed and diluted. There is a method of supplying a use liquid of a polishing composition to a polishing pad. Mixing of concentrated liquid with water or aqueous solution is a method in which liquids collide with each other through a narrow passage under pressure, filling the pipe with a filler such as a glass tube, and separating and separating the liquid flow. Ordinary methods such as a method of repeatedly performing and a method of providing a blade rotating with power in the pipe can be employed.

The supply rate of the polishing composition is preferably 10 to 1000 ml / min, and more preferably 170 to 800 ml / min in order to satisfy the in-plane uniformity of the polishing rate and the flatness of the pattern.
The supply flow rate of the polishing composition is the flow rate of the polishing composition per minute supplied to the object to be polished (polishing pad), and the area of the surface to be polished in the object to be polished (wafer area) ), The supply flow rate of the polishing composition is preferably 0.035 to 0.60 ml / min · cm ² . As a result, the in-plane uniformity of the polishing rate and the flatness of the pattern can be satisfied.

  Furthermore, as a method of polishing while diluting the concentrate with water or an aqueous solution, a pipe for supplying the concentrate and a pipe for supplying water or an aqueous solution are provided independently, and a predetermined amount of liquid is supplied to the polishing pad from each. There is a method of supplying and polishing while mixing by the relative motion of the polishing pad and the surface to be polished. Alternatively, a method may be used in which a predetermined amount of concentrated liquid and water or an aqueous solution are mixed in a single container, and then the mixed polishing composition is supplied to a polishing pad to perform polishing.

Further, as another polishing method, the component to be contained in the polishing composition is divided into at least two constituent components, and when using them, a polishing pad on a polishing surface plate is diluted by adding water or an aqueous solution. And the surface to be polished is brought into contact with the surface to be polished, and the surface to be polished and the polishing pad are moved relative to each other for polishing.
For example, an oxidant is used as the component (A), an organic acid, an additive, a surfactant, and water are used as the component (B). A component (B) can be diluted and used.
Further, an additive having low solubility is divided into two constituent components (A) and (B). For example, an oxidizing agent, an additive, and a surfactant are used as the constituent component (A), and an organic acid, an additive, and a surface active agent are used. An agent and water are used as the component (B), and when they are used, water or an aqueous solution is added to dilute the component (A) and the component (B). In these cases, the silica particles (abrasive grains) in the present invention are preferably contained in the component (A).

In the case of the above example, three pipes for supplying the component (A), the component (B), and water or an aqueous solution are required, and dilution mixing supplies the three pipes to the polishing pad. There is a method of connecting to one pipe and mixing in the pipe. In this case, it is possible to connect two pipes and then connect another pipe. Specifically, this is a method in which a constituent component containing an additive that is difficult to dissolve is mixed with another constituent component, a mixing path is lengthened to ensure a dissolution time, and then a water or aqueous solution pipe is further coupled. .
As described above, the other mixing methods are as follows. The three pipes are directly guided to the polishing pad and mixed by the relative movement of the polishing pad and the surface to be polished, or the three components are mixed in one container. There is a method of supplying a diluted polishing composition from there to a polishing pad.

  In the above polishing method, when one constituent component containing an oxidizing agent is made 40 ° C. or lower and the other constituent components are heated in the range of room temperature to 100 ° C., one constituent component and another constituent component are mixed. Alternatively, when diluting by adding water or an aqueous solution, the liquid temperature can be set to 40 ° C. or lower. This method is a preferable method for increasing the solubility of the raw material having a low solubility of the polishing composition by utilizing the phenomenon that the solubility becomes high when the temperature is high.

  The raw materials in which the above other components are dissolved by heating in the range of room temperature to 100 ° C. are precipitated in the solution when the temperature is lowered. It is necessary to dissolve the raw material deposited by heating. For this purpose, there are provided means for heating and feeding the other constituents in which the raw material is dissolved, and means for stirring and feeding the liquid containing the precipitate, and heating and dissolving the piping. Can be adopted. When the temperature of one constituent component containing an oxidizing agent is increased to 40 ° C. or higher, the other constituent components that have been heated may be decomposed. When two components are mixed, it is preferable that the temperature be 40 ° C. or lower.

Thus, in the present invention, the components of the polishing composition may be divided into two or more parts and supplied to the surface to be polished. In this case, it is preferable to divide and supply the component containing an oxide and the component containing an organic acid. Alternatively, the polishing composition may be used as a concentrated liquid and supplied to the surface to be polished separately from the dilution water.
In the present invention, when applying a method of dividing the components of the polishing composition into two or more parts and supplying them to the surface to be polished, the supply amount represents the total supply amount from each pipe.

〔pad〕
The polishing pad for polishing applicable to the polishing method of the present invention may be a non-foamed structure pad or a foamed structure pad. The former uses a hard synthetic resin bulk material like a plastic plate for a pad. Further, the latter further includes three types of a closed foam (dry foam system), a continuous foam (wet foam system), and a two-layer composite (laminated system), and a two-layer composite (laminated system) is particularly preferable. Foaming may be uniform or non-uniform.
Further, it may be one containing abrasive grains generally used for polishing (for example, ceria, silica, alumina, resin, etc.). In addition, the hardness may be either soft or hard, and either may be used. In the laminated system, it is preferable to use a different hardness for each layer. As the material, non-woven fabric, artificial leather, polyamide, polyurethane, polyester, polycarbonate and the like are preferable. Further, the surface contacting the surface to be polished may be subjected to processing such as lattice grooves / holes / concentric grooves / helical grooves.

[Wafer]
In the present invention, the wafer as the object to be polished by CMP with the polishing composition preferably has a diameter of 200 mm or more, and particularly preferably 300 mm or more. The effect of the present invention is remarkably exhibited when the thickness is 300 mm or more.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

<Example 1>
(Preparation of polishing composition)
The following composition was mixed to prepare a polishing composition.
Hydrogen peroxide (oxidant) 10g / L
Ammonium nitrate (inorganic salt, manufactured by Wako Pure Chemical Industries, Ltd.) 10 g / L
1,2,3-benzotriazole (BTA: aromatic ring compound) 0.5 g / L
Colloidal silica particles (PL-3) 100g / L (converted into powder)
Add pure water, total volume 1000mL
pH (adjusted with aqueous ammonia and sulfuric acid) 9.5

<Examples 2 to 18 and Comparative Examples 1 to 5>
In the preparation of the polishing composition of Example 1, the polishing composition was prepared in the same manner as in Example 1, except that the abrasive particles (silica particles), the inorganic salt, and the pH were changed as described in Table 1. did.

(Polishing test and evaluation)
Using an apparatus “LGP-612” manufactured by Lapmaster as a polishing apparatus, and polishing the insulating film provided on the wafer while supplying the polishing composition (slurry) obtained above under the following conditions, The polishing rate at that time was measured.
Specifically, while supplying the polishing composition to the polishing pad of the polishing platen of the polishing apparatus, the polishing platen and the substrate are relatively relative to each other while the substrate (object to be polished) is pressed against the polishing pad. And polished the insulation film (BDI)

-Object to be polished-
Using black diamond (BDI, Applied Materials, Inc.) as an insulating film material, an insulating film was formed on an 8-inch wafer by a CVD method.

-Polishing conditions-
Table rotation speed: 64 rpm
-Head rotation speed: 65 rpm (Processing linear velocity = 1.0 m / s)
Polishing pressure: 6.89 kPa
Polishing pad: Rohm and Haas product number IC-1400 (K-XY-grv) + (A21)
-Slurry supply rate: 200 ml / min.

-Evaluation method-
(1) Insulating film polishing rate The polishing rate was obtained from the following equation by converting the film thickness difference of the insulating film (BDI) before and after CMP from the electrical resistance value. The film thickness difference was measured using F20 manufactured by Filmmetrics Co., Ltd.
BDI polishing rate (nm / min) = (BDI thickness before polishing−BDI thickness after polishing) / Polishing time

  According to the results of Table 1, in Examples 1 to 18 of the present invention, a very large insulating film polishing rate is achieved. On the other hand, in Comparative Examples 1 to 5 deviating from the aspect of the present invention, a sufficient polishing rate could not be achieved.

Claims (8)

  In a semiconductor device manufacturing method, the insulating film of an object to be polished is formed by chemically and mechanically forming an embedded wiring through a barrier metal layer in an insulating film having an organosiloxane structure and a relative dielectric constant of 3.0 or less. A polishing composition used for polishing, comprising silica particles having a primary particle size of 10 to 80 nm, a benzotriazole compound, and 1 to 10% by mass of an inorganic salt, and having a pH of 8 to 11 A polishing composition.   The polishing composition according to claim 1, wherein a concentration of the silica particles is 0.5 to 15% by mass.   The benzotriazole compound is 1,2,3-benzotriazole (BTA), 5,6-dimethyl-1,2,3-benzotriazole (DBTA), 1- (1,2-dicarboxyethyl) benzotriazole ( DCEBTA), 1- [N, N-bis (hydroxyethyl) aminomethyl] benzotriazole (HEABTA), 1- (hydroxymethyl) benzotriazole (HMBTA) The polishing composition according to 1 or 2.   The polishing composition according to any one of claims 1 to 3, wherein the inorganic salt is at least one selected from an ammonium salt, a sodium salt, and a potassium salt.   The polishing composition according to claim 1, which does not contain an aromatic ring compound other than the benzotriazole compound.   A polishing method in which a polishing composition is supplied to a polishing pad on a polishing platen, and the polishing surface is rotated by rotating the polishing platen while the polishing pad is in contact with an insulating film of an object to be polished, thereby polishing the contact surface. And the insulating film is an insulating film of the object to be polished formed by forming an embedded wiring through a barrier metal layer in an insulating film having an organic siloxane structure and having a relative dielectric constant of 3.0 or less, and A polishing method, wherein the polishing composition is the polishing composition according to claim 1.   The polishing method according to claim 6, wherein a load (polishing pressure) when the polishing pad is brought into contact with the insulating film of the object to be polished is 0.69 to 21.6 KPa. The polishing method according to claim 6 or 7, wherein a supply flow rate when supplying the polishing composition to the polishing pad on the polishing surface plate is 0.035 to 0.60 ml / min · cm ^2. .