JP2013069929A - Additive liquid for cmp polishing liquid, cmp polishing liquid, method for polishing substrate, and electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an additive liquid for a CMP polishing liquid which hardly generates an organic residue on the surface of a substrate after polishing, and to provide a CMP polishing liquid capable of reducing the number of occurred defects to improve throughput of semiconductor device production.SOLUTION: The additive liquid for the CMP polishing liquid contains at least one type of an organic residue inhibitor selected from the group of alcohols and phenols, a polycarboxylic acid of which the content is 0.1 mass% or more, and water.

Description

  The present invention relates to an additive liquid for CMP polishing liquid, a CMP polishing liquid, a method for polishing a substrate, and an electronic component using the polished substrate.

  In the field of semiconductor manufacturing, along with the higher performance of VLSI devices, it has become the limit to achieve both higher integration and higher speed with the conventional miniaturization technology on the extension line. A technology for high integration (multi-layered wiring) has also been developed in the direction.

  One of the most important techniques in such a process for advancing multilayer wiring is a CMP (chemical mechanical polishing) technique. In multilayer wiring, it is indispensable to flatten the device for each layer in order to ensure the depth of focus of lithography. This is because when the surface of the substrate is uneven, it is impossible to focus the exposure process or form a fine wiring structure.

  Such a CMP process is performed by forming a silicon oxide film such as a plasma oxide film (BPSG / HDP-SiO / p-TEOS) / interlayer insulating film embedded after forming an element isolation structure, or flattening an Al / Cu plug after embedding a metal wiring. This technology is indispensable for semiconductor manufacturing.

  The CMP polishing liquid necessary for high planarization of such a semiconductor is a CMP polishing liquid having a characteristic that a silicon oxide film can be polished at a high speed and a silicon nitride film can be polished at a low speed in a shallow trench isolation (STI) process, Known is a CMP polishing liquid for polishing a metal wiring for polishing a metal wiring layer such as copper or aluminum, a barrier layer provided under the metal wiring layer, or the like.

  Various types of CMP polishing liquid for STI are known. In order to obtain a substrate having high flatness by polishing a substrate having irregularities, a slurry containing abrasive grains, a dispersant and water is used. Further, a CMP polishing liquid is known in which an additive liquid containing a water-soluble polymer compound such as polyacrylic acid and water is added (see, for example, Patent Document 1).

  By the way, in the CMP process, with the progress of the miniaturization technique, a CMP polishing liquid with a small number of defects generated on the polished surface is strongly demanded. A typical example of such a defect is a polishing flaw.

Japanese Patent No. 3649279

  When the substrate is polished using a CMP polishing liquid obtained by adding an additive liquid containing a water-soluble polymer compound and water to a slurry containing abrasive grains, a dispersant and water as described above, Organic residue may adhere to the surface of the substrate. Such an organic residue not only causes a problem in the semiconductor production process but also may cause the above-described polishing scratches. Conventionally, the organic residue has been removed by washing the surface of the substrate after polishing, but there are actual situations such as that it takes time for washing or it cannot be washed. In some cases, this organic residue is often generated, but the cause has not been sufficiently clarified so far.

  The present invention is intended to solve the above-described problems, and provides a CMP polishing liquid in which organic residues are hardly generated on the surface of a substrate after polishing, and an additive liquid for CMP polishing liquid used therefor. is there. It is another object of the present invention to provide a method for polishing a substrate capable of reducing the number of occurrences of defects and to improve the throughput of semiconductor device production.

  As a result of various studies on the above problems, the present inventors have found that the cause of the generation of organic residues is mainly the additive liquid used for the preparation of the CMP polishing liquid, and particularly the additive liquid containing a water-soluble polymer compound. It was found that organic residues are likely to be generated when using. And it discovered that generation | occurrence | production of the said organic residue could be improved dramatically by including the organic residue inhibitor which consists of alcohol etc. in an additive liquid.

That is, the present invention is as follows.
<1> CMP polishing liquid containing at least one organic residue inhibitor selected from the group consisting of alcohols and phenols, a polycarboxylic acid having a content of 0.1% by mass or more, and water. Additive solution.
According to such an additive solution for CMP polishing liquid, after the substrate is polished with the CMP polishing liquid obtained by mixing the additive liquid for CMP polishing liquid together with the slurry, generation of organic residues on the surface of the substrate is suppressed. it can.

<2> The additive liquid for CMP polishing liquid according to <1>, wherein the content of the organic residue inhibitor in the total mass of the additive liquid for CMP polishing liquid is 0.1% by mass or more and 30% by mass or less.
Thereby, generation | occurrence | production of an organic residue can be suppressed more effectively.

<3> The CMP polishing liquid additive liquid according to <1> or <2>, wherein the alcohol is at least one selected from monoalcohols and diols.
This can more effectively suppress the generation of organic residues, shorten the cleaning process, save the cleaning liquid, and improve the yield (yield) of the semiconductor to be polished.

<4> The alcohol according to any one of <1> to <3>, wherein the alcohol includes at least one monoalcohol selected from the group consisting of methanol, ethanol, isopropanol, propanol, butanol, and isobutanol. This is an additive liquid for CMP polishing liquid.

<5> The alcohol is ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 2,3-butanediol, 1,3-butanediol, 1,5-pentanediol, 1 , 2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, 2,3-pentanediol, 2,4-pentanediol, 1,6-hexanediol, 1,2-hexanediol, 1, 3-hexanediol, 1,4-hexanediol, 1,5-hexanediol, 2,3-hexanediol, 2,4-hexanediol, 2,5-hexanediol, 3,4-hexanediol, 3,5 <1> to <3> containing at least one diol selected from the group consisting of hexanediol and diethylene glycol The additive solution for CMP polishing liquid according to any one of the above.
By containing these alcohols, the generation of organic residues can be suppressed more effectively, the cleaning process can be shortened, the cleaning liquid can be saved, and the yield (yield) of the semiconductor to be polished can be improved.

<6> The CMP polishing liquid additive solution according to any one of <1> to <3>, wherein the phenols include at least one phenol selected from phenol and catechol.

<7> A CMP polishing liquid comprising a slurry containing abrasive grains and water and the CMP polishing liquid additive liquid according to any one of <1> to <6>.

<8> While supplying the CMP polishing liquid according to <7> between the film to be polished formed on at least one surface of the substrate and the polishing cloth on the polishing surface plate, the substrate and the polishing surface plate Are moved relative to each other to polish at least a part of the film to be polished.
According to such a method, it is possible to suppress the generation of organic residues on the polished substrate.

<9> An electronic component using the substrate polished by the polishing method according to <8>.
According to such an electronic component, since an organic residue is prevented from being generated on the substrate after polishing, an electronic component having excellent reliability can be obtained.

  ADVANTAGE OF THE INVENTION According to this invention, the CMP polishing liquid with few organic residues on the surface of the board | substrate after grinding | polishing and the additive liquid for CMP polishing liquid used for it can be provided. This also provides a method for polishing a substrate that can reduce the number of occurrences of defects, and can improve the throughput of semiconductor device production.

  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 CMP polishing liquid additive liquid or in the CMP polishing liquid, when there are a plurality of substances corresponding to each component, unless otherwise specified, for the CMP polishing liquid. It means the total amount of the plurality of substances present in the additive liquid or the CMP polishing liquid.

  Hereinafter, an additive solution for CMP polishing liquid of the present invention (hereinafter also simply referred to as “addition liquid”), a CMP polishing liquid, a method for polishing a substrate using the same (hereinafter also simply referred to as “polishing method”), and polishing. A preferred embodiment of an electronic component using the manufactured substrate will be described in detail.

1) Additive Liquid for CMP Polishing Liquid The additive liquid for CMP polishing liquid of the present invention (the additive liquid) is an additive liquid for mixing with a slurry containing abrasive grains and water to obtain a CMP polishing liquid, which is an alcohol. And an organic residue inhibitor of at least one selected from the group consisting of phenols (hereinafter, alcohols and phenols are also simply referred to as “alcohols”), and the content in the total mass of the additive liquid Contains at least one polycarboxylic acid of 0.1 mass% or more and water. The additive liquid has an organic residue reducing effect in a CMP polishing liquid obtained by mixing with a slurry containing abrasive grains and water described later.

By containing the additive liquid in a CMP polishing liquid described later, it is possible to suppress the generation of organic residues on the surface of the substrate after polishing. This is considered as follows, for example.
There are various possible causes of the generation of organic residues on the substrate after polishing. One of the causes is assumed to be the influence of organic components present in the CMP polishing liquid. The organic residue derived from the organic component is not removed by normal CMP polishing and remains on the substrate surface even after polishing. On the other hand, when an aqueous solution of the alcohol or the like is allowed to act on the organic component, the solubility of the organic component is increased, and the organic component can be eliminated or reduced. As an organic component, for example, bacteria or bacteria may be present in the CMP polishing liquid, and in this case, it is considered that the additive liquid exhibits a bactericidal effect. Thereby, it is estimated that generation | occurrence | production of an organic residue reduces.

1-1) Organic residue inhibitor The additive solution contains at least one organic residue inhibitor. Thereby, generation | occurrence | production of the organic residue on a substrate surface can be suppressed more effectively. The organic residue suppressor may be any one that is water-soluble, exhibits solubility in organic components present in the CMP polishing liquid described later, and has low reactivity with the substrate. What is necessary is just to select suitably according to a grinding | polishing object, the kind of below-mentioned slurry, etc.

The alcohol is preferably at least one selected from monoalcohols and diols. This can more effectively suppress the generation of organic residues, shorten the cleaning process, save the cleaning liquid, and improve the yield (yield) of the semiconductor to be polished. These can be used alone or in combination of two or more.

  As said monoalcohol, a C1-C4 alcohol is preferable. Examples thereof include at least one selected from the group consisting of methanol, ethanol, isopropanol, propanol, butanol, and isobutanol. Among these, ethanol, isopropanol, and propanol are more preferable from the viewpoint of the effect of suppressing the generation of organic residues.

  As said diol, a C2-C6 dialcohol is preferable. For example, ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 2,3-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, 2,3-pentanediol, 2,4-pentanediol, 1,6-hexanediol, 1,2-hexanediol, 1,3-hexanediol, 1 , 4-hexanediol, 1,5-hexanediol, 2,3-hexanediol, 2,4-hexanediol, 2,5-hexanediol, 3,4-hexanediol, 3,5-hexanediol, diethylene glycol, etc. Is mentioned. Of these, ethylene glycol, propylene glycol, and 1,3-propanediol are preferable, and ethylene glycol and propylene glycol are more preferable from the viewpoint of the effect of suppressing the generation of organic residues.

  Examples of the phenols include phenol, catechol, thymol, 3,4,5-trihydroxybenzoic acid, and the like. This can more effectively suppress the generation of organic residues, shorten the cleaning process, save the cleaning liquid, and improve the yield (yield) of the semiconductor to be polished. Of these, phenol, thymol, and 3,4,5-trihydroxybenzoic acid are preferable, and thymol and 3,4,5-trihydroxybenzoic acid are more preferable from the viewpoint of an organic residue generation inhibitory effect.

  Although there is no restriction | limiting in particular in the content rate of the said organic residue inhibitor, For example, it is preferable to set it as the range of 0.1 mass% or more and 30 mass% or less in the said additional liquid total mass. If it is this range, it is effective by reduction of an organic residue. Further, in terms of solubility in organic components present in the CMP polishing liquid, which is considered to be one of the causes of organic residues, 0.3% by mass or more is more preferable, 0.5% by mass or more is more preferable, and 0.9% A mass% or more is particularly preferred. Further, from the viewpoint of suppressing the volatilization of alcohol and stabilizing the composition of the CMP polishing liquid, it is more preferably 10% by mass or less, more preferably 8% by mass or less, and particularly preferably 5% by mass or less.

1-2) Polycarboxylic acid The additive liquid contains at least one polycarboxylic acid having a predetermined content. The polycarboxylic acid has a function of preferentially polishing the convex portions and flattening the surface of the substrate after polishing when a substrate having irregularities is polished. However, the action of the polycarboxylic acid is not limited to this. By using a CMP polishing liquid obtained by mixing the additive liquid containing the polycarboxylic acid and the organic residue inhibitor and a slurry described later, generation of organic residues on the substrate surface after polishing can be suppressed. it can. In the present invention, the polycarboxylic acid is defined as a polymer compound obtained by polymerizing or copolymerizing a carboxylic acid having a polymerizable substituent such as an unsaturated double bond.

  The polycarboxylic acid may be a homopolymer of a carboxylic acid having a polymerizable substituent or a copolymer of carboxylic acids having two or more polymerizable groups, and may be a carboxylic acid having a polymerizable substituent and other carboxylic acids. It may be a copolymer with a monomer having an unsaturated double bond. The polycarboxylic acid may be a salt such as an ammonium salt or an amine salt. These can be used alone or in combination of two or more. Examples of the carboxylic acid having a polymerizable substituent include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid and the like. Among these, acrylic acid and methacrylic acid are more preferable.

  Examples of the polycarboxylic acid include polymethacrylic acid, polymethacrylic acid ammonium salt, polymaleic acid, polyitaconic acid, polyfumaric acid, poly (p-styrenecarboxylic acid), polyacrylic acid, polyacrylic acid ammonium salt, and the like. And polycarboxylic acids thereof and salts thereof.

  The weight average molecular weight of the polycarboxylic acid is not particularly limited. Specifically, it is preferably 2,000 to 500,000, more preferably 2,000 to 50,000. When the weight average molecular weight of the polycarboxylic acid is 2,000 or more, uniform polishing characteristics are exhibited. When the weight average molecular weight is 50,000 or less, uniform adsorption of the polycarboxylic acid to the abrasive grains and the substrate surface can be obtained. . The weight average molecular weight of the polycarboxylic acid can be measured by gel permeation chromatography using a standard polystyrene calibration curve.

  The content rate of the said polycarboxylic acid shall be 0.1 mass% or more in the said addition liquid total mass. If it is less than 0.1% by mass, it is difficult to satisfactorily flatten the surface of the substrate after polishing. The upper limit of the content of the polycarboxylic acid may be appropriately selected according to the mixing ratio with the slurry described later, the dilution rate, and the like. However, as the content increases in the above range, the amount of organic residue tends to increase. is there. For this reason, it is preferable that it is 30 mass% or less in the said additional liquid total mass, It is more preferable that it is 10 mass% or less, It is still more preferable that it is 5 mass% or less. The content of the polycarboxylic acid is preferably 0.1% by mass or more, based on the total mass of the additive solution, from the viewpoint of improving the polishing effect and the flattening effect of the projections on the substrate surface, and is 0.3% by mass. More preferably, it is more preferably 0.5% by mass or more.

1-3) Water The water is not particularly limited, but pure water can be preferably used. Water should just be mix | blended as a remainder in the composition of the said addition liquid, and a content rate does not have a restriction | limiting in particular. The additive liquid is used to obtain a CMP polishing liquid by mixing with a slurry containing abrasive grains and water as will be described later.

2) CMP polishing liquid The CMP polishing liquid contains at least one kind of abrasive grains, water, and the CMP polishing liquid additive liquid. By using the CMP polishing liquid in a substrate polishing method described later, it is possible to suppress the generation of organic residues on the surface of the substrate after polishing.

2-1) Abrasive grains The abrasive grains are not particularly limited, but cerium-based abrasive grains, silica, alumina, titania, zirconia, magnesia, mullite, germania and their modified products, silicon nitride, α-sialon, aluminum nitride And at least one particle compound selected from the group consisting of inorganic abrasive particles such as titanium nitride, silicon carbide and boron carbide, and organic abrasive particles such as polystyrene, polyacryl and polyvinyl chloride. Examples of the modified product include those obtained by modifying the surface of abrasive grains such as ceria, silica, alumina, titania, zirconia, and germania with an alkyl group. 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.

  As the abrasive grains, cerium-based abrasive grains, silica, alumina, titania, zirconia, or germania particles are more preferable, and cerium-based abrasive grains, silica, or alumina particles are more preferable.

  The cerium-based abrasive is selected from the group of cerium oxide, cerium hydroxide, ammonium cerium nitrate, cerium acetate, cerium sulfate hydrate, cerium bromate, cerium bromide, cerium chloride, cerium oxalate, cerium nitrate, cerium carbonate Can be selected from at least one compound. Among these, cerium oxide and cerium hydroxide are more preferable.

Cerium has its own bactericidal action. For this reason, when the organic substance is derived from bacteria or the like, it is more effective to apply the additive liquid to the CMP polishing liquid using silica abrasive grains or other abrasive grains having a low bactericidal action. These abrasive grains can be used alone or in combination of two or more.

  The cerium oxide can be obtained by oxidizing a cerium compound of carbonate, nitrate, sulfate, or oxalate. The cerium oxide abrasive used for polishing a silicon oxide film formed by TEOS-CVD or the like has a large primary particle size and single crystal cerium oxide particles are used, but there is a tendency that polishing scratches are likely to occur. . Therefore, although the production method of the cerium oxide particles used in the present invention is not limited, it is preferable that the cerium oxide particles are polycrystalline in which single crystal particles of 5 nm to 300 nm are aggregated. Moreover, since it uses for semiconductor chip grinding | polishing, it is preferable to suppress the content rate of an alkali metal and halogens to 10 ppm or less in a cerium oxide particle.

  As a method for producing the cerium oxide powder, firing or oxidation using hydrogen peroxide or the like can be used. The firing temperature is preferably 350 ° C. or higher and 900 ° C. or lower. As a raw material at this time, cerium carbonate is preferable.

  Since the cerium oxide particles produced by the above method are agglomerated, it is preferably mechanically pulverized. As the pulverization method, a dry pulverization method such as a jet mill or a wet pulverization method such as a planetary bead mill is preferable.

  The silica or alumina particles are preferably colloidal silica or colloidal alumina, more preferably colloidal silica, which is excellent in dispersion stability in the CMP 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 average grain size of the abrasive grains is preferably 10 nm to 200 nm. By setting this range, a good polishing rate can be obtained. The particle size of the abrasive grains is a value measured with a light diffraction scattering type particle size distribution meter (for example, trade name: COULTER N4SD manufactured by COULTER Electronics). The measurement conditions of Coulter are: measurement temperature 20 ° C., solvent refractive index 1.333 (water), particle refractive index Unknown (setting), solvent viscosity 1.005 mPa · s (water), Run Time 200 sec, laser incident angle 90 °. , Intensity (corresponding to scattering intensity, turbidity) falls within the range of 5E + 04 to 4E + 05, and when it is higher than 4E + 05, it is diluted with water and measured.

  The content of the abrasive grains in the total mass of the CMP polishing liquid is not particularly limited, but considering the stability of the dispersant, for example, 0.05 mass% to 20.00 mass%. Good.

2-2) Water Although the water is not particularly limited, pure water can be preferably used. Water should just be mix | blended as a remainder in the composition of the said CMP polishing liquid, and a content rate does not have a restriction | limiting in particular.

2-3) Additive liquid for CMP polishing liquid The additive liquid for CMP polishing liquid (the additive liquid) of the present invention is mixed with the abrasive grains and the slurry containing water to form the CMP polishing liquid. The polycarboxylic acid contained in the additive liquid has a function of preferentially polishing the convex portion and flattening the surface of the substrate after polishing, for example, when a substrate having unevenness is polished.

  The content of the additive liquid is preferably included so that the content of the polycarboxylic acid in the mass of the CMP polishing liquid is 0.1% by mass to 2.0% by mass. The content of the polycarboxylic acid is more preferably 0.2% by mass or more, further preferably 0.3% by mass or more, particularly preferably 0.4% by mass or more, and extremely preferably 0.5% by mass or more. Further, the content of the polycarboxylic acid is more preferably 1.5% by mass or less, and further preferably 1.0% by mass or less. When the content ratio is in the above range, a substrate with unevenness can be polished with good flatness while maintaining a sufficient polishing rate of the film to be polished (preferably a silicon oxide film).

2-4) Dispersant The CMP polishing liquid may contain at least one dispersant in addition to the abrasive grains, the water, and the additive liquid. The dispersant improves the dispersibility of the abrasive grains in water. The dispersant is not particularly limited as long as it is a compound that can be dissolved in water. Generally, it refers to a compound having a solubility in water of 0.1% by mass to 99.9% by mass. For example, a water-soluble anionic dispersant, a water-soluble nonionic dispersant, a water-soluble cationic dispersant, a water-soluble amphoteric dispersant and the like can be mentioned. When used for semiconductor chip polishing, the content of alkali metals such as sodium ions and potassium ions, halogens and sulfur in the dispersant is preferably suppressed to 10 ppm or less.

  Examples of the water-soluble anionic dispersant include lauryl sulfate triethanolamine, ammonium lauryl sulfate, polyoxyethylene alkyl ether sulfate triethanolamine, and the like.

  Examples of the water-soluble nonionic dispersant include polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene higher alcohol ether, polyoxyethylene octylphenyl ether. , Polyoxyethylene nonylphenyl ether, polyoxyalkylene alkyl ether, polyoxyethylene derivatives, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate , Polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate, tetraoleic acid Reoxyethylene sorbit, polyethylene glycol monolaurate, polyethylene glycol monostearate, polyethylene glycol distearate, polyethylene glycol monooleate, polyoxyethylene alkylamine, polyoxyethylene hydrogenated castor oil, 2-hydroxyethyl methacrylate, alkyl alkanol Examples include amides and polyoxyacetylene ethers.

Examples of the water-soluble cationic dispersant include polyvinyl pyrrolidone, coconut amine acetate, stearyl amine acetate and the like.

Examples of the water-soluble amphoteric dispersant include lauryl betaine, stearyl betaine, lauryl dimethylamine oxide, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine and the like.

The said dispersing agent can be used individually or in combination of 2 or more types.

  Further, the dispersant may be a low molecular dispersant. Specifically, uracil-6-carboxylic acid, 5-hydroxy-2- (hydroxymethyl) -4H-pyran-4-one, 3-hydroxy-2-methyl-4H-pyran-4-one, 2-ethyl-3-hydroxy-4-pyrone, mandelic acid, salicylaldoxime, ascorbic acid, catechol, 3-methylcatechol, 4-methylcatechol, 4-tert-butylcatechol, 1,4-benzoquinone dioxime, 2 -Pyridinemethanol, 4-isopropyltropolone, 2-hydroxy-2,4,6-cycloheptatrien-1-one, 5-amino-uracil-6-carboxylic acid, benzylic acid and the like. Among them, 5-hydroxy-2- (hydroxymethyl) -4H-pyran-4-one, 3-hydroxy-2-methyl-4H-pyran-4-one, and 2-ethyl-3 are preferable from the viewpoint of high polishing rate. -Hydroxy-4-pyrone is preferred.

  The low molecular weight dispersant may further contain a saturated monocarboxylic acid. The saturated monocarboxylic acid preferably has 2 to 6 carbon atoms, more preferably 2 to 5 carbon atoms. Examples of the saturated monocarboxylic acid include acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, pivalic acid, hydroangelic acid, caproic acid, 2-methylpentanoic acid, 4-methylpentanoic acid, 2, 3 -At least one compound selected from the group consisting of dimethylbutanoic acid, 2-ethylbutanoic acid, 2,2-dimethylbutanoic acid and 3,3-dimethylbutanoic acid can be used. Of these, acetic acid and propionic acid are preferred because they are water-soluble and easy to handle.

  The content of the dispersant in the total mass of the CMP polishing liquid is preferably 0.01% by mass to 1.0% by mass. If it is 0.01 mass% or more, sufficient dispersibility of the abrasive grains can be obtained. If it is 1 mass% or less, agglomeration of abrasive grains can be suppressed.

2-5) pH adjuster The CMP polishing liquid may contain an acid or a base as a pH adjuster. The pH adjuster may be blended in the additive solution.

  The acid used as the pH adjuster is not particularly limited. For example, an inorganic acid selected from the group of sulfuric acid, nitric acid, hydrochloric acid, perchloric acid, iodic acid, odorous acid, oxalic acid, citric acid, malonic acid, aspartic acid, ortho-aminobenzoic acid, para-aminobenzoic acid, 2-aminoethylphosphonic acid, alanine, arginine, isonicotinic acid, isoleucine, oxaloacetic acid, ornithine, guanosine, glycine, 2-glycerin phosphate, para-glucose-1-phosphate, glutamine, glutamic acid, chloroacetic acid, salicylic acid, Sarcosine, cyanoacetic acid, dichloroacetic acid, cysteine, N, N-dimethylglycine, tartaric acid, tyrosine, trichloroacetic acid, threonine, nicotinic acid, nitroacetic acid, picric acid, picolinic acid, histidine, proline, maleic acid, lysine, leucine, etc. Polymer oxidation of organic acids such as polysulfonic acid An acid selected from such things like.

  Examples of the base include ammonia, ethylamine, diethylamine, triethylamine, diphenylguanidine, piperidine, butylamine, dibutylamine, isopropylamine, tetramethylammonium oxide, tetramethylammonium chloride, tetramethylammonium bromide, tetramethylammonium fluoride, tetrabutyl. Ammonium hydroxide, tetrabutylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium fluoride, tetramethylammonium nitrate, tetramethylammonium acetate, tetramethylammonium propionate, tetramethylammonium maleate, tetramethylammonium sulfate Etc. The base is preferably a water-soluble amine.

  The pH of the CMP polishing liquid is appropriately selected in the range of 4 to 12 depending on the needs of the semiconductor device structure.

  The pH of the CMP polishing liquid is measured by a pH meter (for example, Model F-51 manufactured by HORIBA). Standard buffer (phthalate pH buffer pH: 4.21 (25 ° C.), neutral phosphate pH buffer pH 6.86 (25 ° C.), borate pH buffer pH: 9.04 (25 ° C. )), The electrode is placed in a CMP polishing liquid after 3 points have been calibrated, and the value after 3 minutes has passed and stabilized is measured.

2-6) Method for Preparing CMP Polishing Liquid In the CMP polishing liquid, a composition comprising various components such as the dispersing agent and the pH adjusting agent, which are added as necessary, in addition to the abrasive grains, is dispersed in the water. It is prepared by mixing the slurry obtained by the above and the above-mentioned additive solution for CMP polishing liquid. As a method of mixing the slurry and the additive solution for CMP polishing liquid, a homogenizer, an ultrasonic disperser, a wet ball mill, or the like can be used in addition to a dispersion process using a normal stirrer.

3) Substrate Polishing Method and Electronic Component Using Polished Substrate 3-1) Substrate Polishing Method The substrate polishing method of the present invention (hereinafter sometimes simply referred to as “polishing method”) is at least one of the substrates. While supplying the CMP polishing liquid between the film to be polished formed on the surface and the polishing cloth on the polishing surface plate, the substrate and the polishing surface plate are moved relatively to each other, At least a part is polished. By polishing the substrate using the CMP polishing liquid, it is possible to suppress the generation of organic residues on the surface of the substrate after polishing, and to reduce the number of defects generated. Thereby, the throughput of semiconductor device production can be improved. The polishing method is suitable for a polishing step of flattening a step by polishing a substrate having a step on the surface.

  Here, as a method for confirming the presence or absence of organic residues, a method of confirming the number of organic residues on the wafer by confirming an SEM image on the defect inspection apparatus after polishing the substrate can be used. Examples of the defect inspection apparatus include SEM Vision manufactured by Applied Materials.

  In the polishing method, prior to the polishing step, the mixing step of preparing the CMP polishing liquid by mixing the slurry, the additive liquid, and, if necessary, deionized water or the like before polishing, You may have.

  Hereinafter, the polishing method will be described by taking as an example the case of a semiconductor substrate on which an inorganic insulating layer such as a silicon oxide film, a silicon nitride film, or a polycrystalline silicon film is formed.

  In the polishing method, as a polishing apparatus to be used, for example, a holder that holds a substrate having a film to be polished such as a semiconductor substrate, a motor that can attach a polishing cloth (pad) and can change the number of rotations, etc. A general polishing apparatus or the like having an attached polishing surface plate can be used.

  Examples of the polishing apparatus include a polishing apparatus manufactured by Ebara Manufacturing Co., Ltd., model number: EPO-111, polishing apparatus manufactured by AMAT, trade name: Mirror 3400, Reflection polishing machine, and the like. There is no restriction | limiting in particular as abrasive cloth, For example, a general nonwoven fabric, a polyurethane foam, a porous fluororesin, etc. can be used. Moreover, it is preferable that the polishing cloth is subjected to a groove processing so that a CMP polishing liquid is accumulated.

The polishing conditions in the polishing method are not particularly limited, but from the viewpoint of preventing the semiconductor substrate from popping out, the rotation speed of the polishing platen is preferably a low rotation of 200 min ⁻¹ or less, and the pressure applied to the semiconductor substrate ( The processing load is preferably 100 kPa or less from the viewpoint of preventing scratches after polishing.

  During polishing, the CMP polishing liquid is preferably continuously supplied to the polishing cloth with a pump or the like. Although the supply amount is not limited, it is preferable that the surface of the polishing pad is always covered with the CMP polishing liquid.

  As described above, the CMP polishing liquid supply method is as follows: (1) Two liquids of the slurry and the additive liquid are sent through separate pipes, and these pipes are merged and mixed immediately before the outlet of the supply pipe. (2) A method of mixing two liquids of the slurry and the additive liquid immediately before polishing, and (3) Separately supplying the two liquids of the slurry and the additive liquid onto the polishing surface plate. The method of supply etc. are mentioned.

  The semiconductor substrate after the polishing is preferably washed in running water and then dried after removing water droplets adhering to the semiconductor substrate using a spin dryer or the like. Thus, by polishing the inorganic insulating layer, which is a film to be polished, with the CMP polishing liquid, surface irregularities can be eliminated and a smooth surface can be obtained over the entire surface of the semiconductor substrate. By repeating this step a predetermined number of times, a semiconductor substrate having a desired number of layers can be manufactured.

Examples of a method for producing a silicon oxide film in which the CMP polishing liquid is used include a low pressure CVD method and a plasma CVD method. Silicon oxide film formation by low-pressure CVD uses monosilane: SiH ₄ as the Si source and oxygen: O ₂ as the oxygen source. It can be obtained by performing this SiH ₄ —O ₂ oxidation reaction at a low temperature of 400 ° C. or lower. In some cases, heat treatment is performed at a temperature of 1000 ° C. or lower after CVD.

When doping phosphorus: P in order to achieve surface flattening by high-temperature reflow, it is preferable to use a SiH ₄ —O ₂ —PH ₃ -based reactive gas. The plasma CVD method has an advantage that a chemical reaction requiring a high temperature can be performed at a low temperature under normal thermal equilibrium. There are two plasma generation methods, capacitive coupling type and inductive coupling type.

The reaction as a gas, SiH ₄ as an Si source, an oxygen source as _{N 2} O was used was _SiH 4 -N ₂ O-based gas and _{TEOS-O 2} based gas using tetraethoxysilane (TEOS) in an Si source (TEOS- Plasma CVD method). The substrate temperature is preferably in the range of 250 ° C. to 400 ° C. and the reaction pressure is in the range of 67 to 400 Pa.

Thus, the silicon oxide film polished in the present invention may be doped with an element such as phosphorus or boron. Similarly, the silicon nitride film formation by the low pressure CVD method uses dichlorosilane: SiH ₂ Cl ₂ as the Si source and ammonia: NH ₃ as the nitrogen source. It can be obtained by performing this SiH ₂ Cl ₂ —NH ₃ oxidation reaction at a high temperature of 900 ° C. In the plasma CVD method, examples of the reactive gas include SiH ₄ —NH ₃ -based gas using SiH ₄ as the Si source and NH ₃ as the nitrogen source. The substrate temperature is preferably 300 ° C to 400 ° C.

  The substrate includes individual semiconductors such as diodes, transistors, compound semiconductors, thermistors, varistors, thyristors, DRAMs (Dynamic Random Access Memory), SRAMs (Static Random Access Memory), EPROMs (Erasable Programmable Programmable). Theories of read-only memory (ROM), mask ROM (mask read-only memory), EEPROM (electrically erasable programmable read-only memory), flash memory, etc., microprocessor, DSP, ASIC, etc. Circuit elements, integrated circuit elements such as compound semiconductors represented by MMIC (monolithic microwave integrated circuit), hybrid integrated circuits (hybrid IC), light emitting diodes, electric charges It refers to a substrate containing such a photoelectric conversion element such as a coupling element.

  The additive liquid and the CMP polishing liquid are not only a silicon nitride film and a silicon oxide film formed on a semiconductor substrate, but also an inorganic insulation such as a silicon oxide film formed on a wiring board having a predetermined wiring, glass, and silicon nitride. A film mainly containing a film, polysilicon, Al, Cu, Ti, TiN, W, Ta, TaN or the like can be an object to be polished.

3-2) Electronic component The electronic component of the present invention uses the substrate polished by the polishing method. According to such an electronic component, since an organic residue is prevented from being generated on the substrate after polishing, an electronic component having excellent reliability can be obtained.

  The electronic components include not only semiconductor elements but also optical glasses such as photomasks, lenses, and prisms, inorganic conductive films such as ITO, glass, and crystalline materials, optical integrated circuits, optical switching elements, optical waveguides, and optical fibers. 1, a single crystal for optics such as a scintillator, a solid laser single crystal, a sapphire substrate for blue laser LED, a semiconductor single crystal such as SiC, GaP, and GaAs, a glass substrate for a magnetic disk, a magnetic head, and the like.

  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 CMP polishing liquid 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 CMP polishing liquid)
First, an additive solution for CMP polishing liquid was prepared using ethanol as an organic residue inhibitor. That is, polymethacrylic acid was used as the polycarboxylic acid, which was diluted with 890.1 g of pure water to prepare a polycarboxylic acid aqueous solution so that the final concentration was 10% by mass. Thereafter, 9.9 g of ethanol was added to the aqueous polycarboxylic acid solution to obtain an additive solution for CMP polishing liquid having an organic residue inhibitor content of 0.99 mass%.

  Subsequently, a cerium oxide slurry having an average particle diameter of 160 nm and a pH of 8.7 is added to 1000 g of the obtained CMP polishing liquid additive solution so that the abrasive concentration is 0.5 mass% and the polycarboxylic acid concentration is 0.5 mass%. Thus, it mixed with the pure water and produced CMP polishing liquid.

As a test wafer for CMP polishing evaluation, a SiO ₂ blanket wafer (initial film thickness: 1000 nm) manufactured by Advantech was used, and chemical mechanical polishing was performed by the CMP polishing solution by the following method.

(CMP polishing)
With a polishing machine Mirara 3400 (product name) manufactured by Applied Materials, polishing pressure is 20.68 kPa (3 psi), surface plate rotation number / head rotation number = 93/87 (rpm), and supply amount of CMP polishing liquid is 200 ml. CMP polishing was performed under the conditions of 1 minute. As the polishing cloth, a foamed polyurethane resin polishing cloth was used.

(Blanket substrate polishing rate)
And about the said blanket board | substrate after performing CMP grinding | polishing for 60 seconds, it is an initial film thickness and the film | membrane after grinding | polishing using the film thickness measuring apparatus (Dainippon Screen Mfg. Co., Ltd. product name: Lambda ace, VL-M8000LS). The polishing rate (nm / min) was determined from the difference in thickness.

(Defect inspection)
Defect inspection was performed with a defect review apparatus SEM Vision (product name) manufactured by Applied Materials. After the defect inspection, the SEM image recorded on the apparatus was confirmed, and the number of organic residues per wafer was measured. The results are shown in Table 1.

<Examples 2 and 3>
In place of the various organic residue inhibitors shown in Table 1 in place of the ethanol used in Example 1, a CMP polishing liquid was prepared in the same manner as in Example 1, and the polishing rate and organic residue when each CMP polishing liquid was used. I checked the number. The results are also shown in Table 1.
<Example 4>

While replacing the organic residue inhibitor used in Example 1 with phenol, the content of the organic residue inhibitor was 0.20% by mass, and the others were prepared in the same manner as in Example 1 to produce a CMP polishing liquid. The polishing rate and the number of organic residues when using the liquid were examined. The results are also shown in Table 1.
<Examples 5 to 8>
While the organic residue inhibitor used in Example 1 was replaced with isopropanol as in Example 2, the content of the organic residue inhibitor was 0.20% by mass, 2.00% by mass, 10.00% by mass, 30. A CMP polishing liquid was prepared in the same manner as in Example 1 except that the amount was changed to 00% by mass, and the polishing rate and the number of organic residues when each CMP polishing liquid was used were examined. The results are also shown in Table 1.

<Comparative Examples 1 and 2>
The organic residue inhibitor used in Example 1 was not added and was replaced with ammonia, and the others were prepared in the same manner as in Example 1, and the polishing rate and the number of organic residues when each CMP polishing solution was used. I investigated. The results are also shown in Table 1.

(Confirmation of effect)
As shown in Examples 1 to 8, it was revealed that the number of organic residues was remarkably reduced by using the CMP polishing liquid addition liquid according to the present invention containing an organic residue inhibitor. In Examples 1 to 8, it was found that the polishing rate was not significantly affected.
On the other hand, when ammonia was added to Comparative Example 2, it was confirmed that the number of organic residues increased. As a reason why ammonia did not show the effect of removing organic residues, for example, the case where the organic component is derived from bacteria or the like can be considered. That is, it is suggested that the presence of ammonia as a nutrient source for bacteria in the CMP polishing liquid may not reduce organic residues derived from organic components.

  In this embodiment, the CMP polishing liquid used includes a slurry containing cerium oxide abrasive grains. However, the present invention is not limited to this, and conventionally known, for example, silica abrasive grains. Even when applied to metal slurries, the same effects as described above can be obtained.

Claims (9)

  An additive solution for CMP polishing liquid, comprising at least one organic residue inhibitor selected from the group consisting of alcohols and phenols, a polycarboxylic acid having a content of 0.1% by mass or more, and water. .   The additive liquid for CMP polishing liquid according to claim 1, wherein the content of the organic residue inhibitor in the total mass of the additive liquid for CMP polishing liquid is 0.1 mass% or more and 30 mass% or less.   The additive liquid for CMP polishing liquid according to claim 1 or 2, wherein the alcohol is at least one selected from monoalcohol and diol.   The CMP polishing liquid according to any one of claims 1 to 3, wherein the alcohol includes at least one monoalcohol selected from the group consisting of methanol, ethanol, isopropanol, propanol, butanol, and isobutanol. Additive solution.   The above alcohols are ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 2,3-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,2- Pentanediol, 1,3-pentanediol, 1,4-pentanediol, 2,3-pentanediol, 2,4-pentanediol, 1,6-hexanediol, 1,2-hexanediol, 1,3-hexane Diol, 1,4-hexanediol, 1,5-hexanediol, 2,3-hexanediol, 2,4-hexanediol, 2,5-hexanediol, 3,4-hexanediol, 3,5-hexanediol And at least one diol selected from the group consisting of diethylene glycol. Zureka CMP polishing liquid additive solution according to item 1.   The additive liquid for CMP polishing liquid according to any one of claims 1 to 3, wherein the phenols include at least one phenol selected from phenol and catechol.   A CMP polishing liquid comprising a slurry containing abrasive grains and water and the additive liquid for CMP polishing liquid according to any one of claims 1 to 6.   While supplying the CMP polishing liquid according to claim 7 between the film to be polished formed on at least one surface of the substrate and the polishing cloth on the polishing surface plate, the substrate and the polishing surface plate are relatively A substrate polishing method for polishing at least a part of the film to be polished.   An electronic component using the substrate polished by the polishing method according to claim 8.