KR20140027561A - Abrasive slurry, abrasive set, and method for polishing substrate - Google Patents

Abstract

The present invention relates to an abrasive containing water, abrasive grains and additives, wherein the abrasive contains tetravalent metal hydroxide particles and at least one component of the additive is a polyvinyl alcohol having a saponification degree of 95 mol% or less. will be. The present invention also relates to an abrasive set for dividing and storing the abrasive into a slurry containing particles and an additive liquid containing an additive, and a method for polishing a substrate using the abrasive described above. As a result, in the CMP technique for planarizing the STI insulating film, the premetal insulating film, the interlayer insulating film, and the like, insulating films such as silicon oxide films can be polished at high speed and with low polishing, and high polishing of the insulating film and the polysilicon film is performed. An abrasive having a speed ratio, an abrasive set and a substrate polishing method are provided.

Description

Abrasive, abrasive set and substrate polishing method {ABRASIVE SLURRY, ABRASIVE SET, AND METHOD FOR POLISHING SUBSTRATE}

The present invention provides an abrasive used in a planarization step of a substrate surface, which is a semiconductor device manufacturing technology, in particular, a planarization step of an STI insulating film, a premetal insulating film, an interlayer insulating film, an abrasive set for storing the abrasive, and polishing of a substrate using the abrasive. It is about a method.

In the recent semiconductor device manufacturing process, the importance of the processing technology for densification and fineness is increasing. One of the CMP (Chemical Mechanical Polishing: Chemical Mechanical Polishing) techniques is to form a shallow trench isolation, planarize a premetal insulating film or an interlayer insulating film in the manufacturing process of a semiconductor device, and to provide a plug and a buried metal wiring. It becomes the technique necessary for formation.

The most widely used abrasive for CMP is an abrasive containing silica (silicon oxide) abrasive grains such as fumed silica and colloidal silica. Silica-based abrasives are characterized by high versatility, and by appropriately selecting abrasive grain concentration, pH, additives, and the like, a wide variety of films can be polished regardless of the insulating film or the conductive film.

On the other hand, the demand for abrasives containing cerium compound abrasive grains, which mainly target insulating films such as silicon oxide films, is also expanding. For example, a cerium oxide-based abrasive containing cerium oxide (ceria) particles as an abrasive is characterized in that the silicon oxide film can be polished at high speed even at a grain concentration lower than that of the silica-based abrasive.

In addition, it is known that flatness and polishing selectivity can be improved by adding a suitable additive to a cerium oxide-based abrasive. For example, in the process of forming STI (slow trench isolation), it is common to provide a silicon nitride film as a polishing stop layer under the silicon oxide film. Here, by appropriately selecting an additive to be added to the abrasive when polishing the silicon oxide film, the ratio (polishing selectivity) of the polishing rate of the silicon oxide film to the silicon nitride film can be increased.

As a result, it becomes easy to stop polishing when the silicon nitride film is exposed, and it is possible to prevent excessive progress of polishing. The cerium oxide-based abrasive used in the CMP process is disclosed in Patent Document 1 and Patent Document 2, for example.

In recent years, the semiconductor element manufacturing process is further refined, and the demand for the polishing wound which arises at the time of grinding | polishing has become more severe. For this problem, attempts have been made to reduce the average particle diameter of cerium oxide particles of an abrasive using cerium oxide as described above. However, when the average particle diameter is reduced, the mechanical action is lowered, so that the polishing rate is lowered.

About this problem, the abrasive | polishing agent using tetravalent metal hydroxide particle is examined, and this technique is disclosed by patent document 3. As shown in FIG. This technique utilizes the chemical action of the tetravalent metal hydroxide particles and makes the mechanical action as small as possible, thereby making it possible to reduce the scratches caused by the particles and to improve the polishing rate.

Patent Document 1: Japanese Patent Application Laid-open No. Hei 10-106994 Patent Document 2: Japanese Patent Application Laid-Open No. 08-022970 Patent Document 3: International Publication No. 02/067309

In recent years, for example, in the process of forming STI, the use of a polysilicon film as a polishing stop layer has also been achieved. In this case, it was necessary to improve the polishing selectivity of the silicon oxide film with respect to the polysilicon film.

In the CMP technique for planarizing an STI insulating film, a premetal insulating film, an interlayer insulating film, and the like, an insulating film such as a silicon oxide film can be polished at a high speed and at a low polishing rate. It is an object to provide an abrasive having polishing selectivity. It is also an object of the present invention to provide an abrasive set for storing the abrasive and a method for polishing a substrate using the abrasive.

The abrasive of the present invention is characterized by containing abrasive grains containing tetravalent metal hydroxide particles and polyvinyl alcohol having an saponification degree of 95 mol% or less. As a result, a high polishing rate ratio of the insulating film to the polysilicon film can be obtained. In the case where a silicon oxide film is used as the insulating film, an example will be described. By taking the above configuration, the silicon oxide film can be polished in preference to polysilicon.

The present invention is (1) an abrasive containing water, abrasive grains and additives,

The abrasive grains comprise tetravalent metal hydroxide particles,

At least one component of the said additive relates to the abrasive | polishing agent whose saponification degree is polyvinyl alcohol of 95 mol% or less.

Moreover, this invention relates to the abrasive | polishing agent of said (1) whose average particle diameter of (2) said abrasive grain is 1 nm or more and 400 nm or less.

Moreover, this invention relates to the abrasive of said (1) or (2) whose pH of (3) abrasive is 3.0 or more and 12.0 or less.

Moreover, this invention relates to the abrasive of any one of said (1)-(3) whose content of the said abrasive grain is 0.01 weight part or more and 5 weight part or less with respect to 100 weight part of abrasives.

Moreover, this invention relates to the abrasive of any one of said (1)-(4) whose zeta potential in the abrasive of the said abrasive grain is -20 mV or more and +20 mV or less.

Moreover, this invention relates to the abrasive of any one of said (1)-(5) whose content of the said polyvinyl alcohol is 0.01 weight part or more with respect to 100 weight part of abrasives.

Moreover, this invention relates to the abrasive | polishing agent in any one of said (1)-(6) used in order to grind | polish the to-be-polished surface containing a silicon oxide at least (7) at the surface.

Moreover, this invention relates to the abrasive | polishing agent in any one of said (1)-(7) whose (8) tetravalent metal hydroxide is at least one of a rare earth metal hydroxide and zirconium hydroxide.

Moreover, this invention presses and presses the board | substrate with which the to-be-polished film | membrane was formed to the polishing pad of a polishing platen, and presses the abrasive | polishing agent in any one of said (1)-(8) between a to-be-polished film and a polishing pad. The present invention relates to a method of polishing a substrate in which the substrate and the polishing plate are relatively moved while polishing the polished film.

Moreover, this invention relates to the grinding | polishing method of the said board | substrate of said (9) whose Shore D hardness of (10) polishing pad is 70 or more.

In addition, the present invention is divided into (11) slurry and the additive liquid, and is preserve | saved, It mixes immediately before grinding | polishing, or at the time of grinding | polishing, The abrasive | polishing agent set which becomes an abrasive | polishing agent in any one of said (1)-(8), and a slurry is a grain and water And the additive liquid relates to an abrasive set comprising the additive and water.

The disclosure of the present invention relates to the subject matter disclosed in Japanese Patent Application No. 2009-138124 filed on June 9, 2009, and Japanese Patent Application No. 2009-236488 filed on October 13, 2009. The disclosures of which are incorporated herein by reference.

In the CMP technique for planarizing an STI insulating film, a premetal insulating film, an interlayer insulating film, and the like, an insulating film such as a silicon oxide film can be polished at a high speed and with a low abrasion scratch. An abrasive having a polishing rate ratio, an abrasive set for storing the abrasive, and a substrate polishing method using the abrasive can be provided.

1 is a graph showing a relationship between saponification of polyvinyl alcohol and polishing selectivity of an insulating film with respect to a polysilicon film.

In the present invention, the "high selectivity of the insulating film to the polysilicon film" means that the polishing rate of the insulating film is higher than the polishing rate of the polysilicon film. High selectivity to ". Hereinafter, unless the restriction | limiting in particular, the case where a silicon oxide film is applied as an insulating film is demonstrated as an example, For example, "excellent selectivity with respect to a polysilicon film" means high selectivity with respect to the polysilicon film of a silicon oxide film. Means that.

The mechanism of action of obtaining such an effect is not necessarily clear, but the present inventors estimate as follows. That is, the polyvinyl alcohol can be considered to act on either abrasive grains such as tetravalent metal hydroxide particles, the to-be-polished film, or either. In particular, it is estimated that the difference in the degree of interaction between the silicon oxide film-polyvinyl alcohol and the degree of interaction of the polysilicon film-polyvinyl alcohol results in a high polishing rate ratio for the polysilicon film. More specifically, it can be considered that the interaction with the polysilicon film-polyvinyl alcohol becomes stronger. That is, since polyvinyl alcohol adsorb | sucks to a hydrophobic polysilicon film effectively, becomes a protective film, and inhibits grinding | polishing, it is guessed that a difference in polishing rate arises as a result.

This reason is considered as follows. That is, since the monomer of vinyl alcohol cannot be synthesize | combined theoretically, polyvinyl alcohol generally polymerizes carboxylic acid vinyl monomers, such as a vinyl acetate monomer, and obtains polyvinyl carboxylate, and then saponifies this (hydrolysis). Is obtained.

Thus, for example, polyvinyl alcohol, obtained by using a vinyl acetate monomer as a raw material is, as a functional group in a molecule has a -OCOCH ₃ and hydrolyzed -0H, is defined as the ratio in which the -OH saponification degree. When the degree of saponification is 95 mol% or less, hydrophobic -0COCH ₃ is more effectively adsorbed onto the hydrophobic polysilicon film than -0H, becomes a protective film and inhibits polishing, and consequently, it is estimated that a difference in polishing rate occurs.

In this invention, an abrasive | polishing agent is a composition which touches a to-be-polished film at the time of grinding | polishing, As a specific aspect, it contains water, an abrasive, and an additive. Hereinafter, each component and the component which can be added arbitrarily are demonstrated in order.

(Grip)

One specific aspect of the abrasive of the present invention is that the abrasive contains tetravalent metal hydroxide particles. The tetravalent metal hydroxide particles are preferable in view of high reactivity with silicon oxide and high polishing rate compared with conventional abrasive grains such as silica and cerium oxide. As another abrasive grain which can be used in the abrasive | polishing agent of this invention, silica, alumina, cerium oxide, etc. are mentioned, for example.

In the abrasive, the content of the tetravalent metal hydroxide particles is preferably 80% by weight or more, more preferably 90% by weight or more, still more preferably 95% by weight or more, and 98% by weight or more, based on the whole abrasive. It is especially preferable, and it is extremely preferable that it is 99 weight% or more. From the viewpoint of easy adjustment of the abrasive and excellent polishing properties, it is most preferable that the abrasive grain is composed of the tetravalent metal hydroxide particles (100% by weight of the abrasive grains are the tetravalent metal hydroxide particles).

As the tetravalent metal hydroxide particles, it is preferable to use at least one of the rare earth metal hydroxide and the zirconium hydroxide, but two or more kinds may be selected and used from the rare earth metal hydroxide and the zirconium hydroxide. Among them, cerium hydroxide Ce (OH) ₄ is preferably used as the rare earth metal hydroxide in terms of high polishing rate.

As a method for producing tetravalent metal hydroxide particles, a method of mixing a tetravalent metal salt and an alkaline liquid can be used. This method is described, for example, in pages 304 to 305 of "The Science of Rare Earth" (Adachi Kinya, Chemical Chemical Co., 1999).

As the tetravalent metal salt, for example, M (SO ₄ ) ₂ , M (NH ₄ ) ₂ (NO ₃ ) ₆ , M (NH ₄ ) ₄ (SO ₄ ) ₄ (M represents a rare earth element.), Zr (SO ₄ ) ₂ · 4H ₂ 0 and the like. As mentioned above, as M, cerium (Ce) which is chemically active is more preferable.

As said alkaline liquid, ammonia water, potassium hydroxide, sodium hydroxide, etc. can be used, for example, aqueous ammonia is preferable. The tetravalent metal hydroxide particles synthesized by the above method can be washed to remove metal impurities. For washing the metal hydroxide, a method of repeating the solid-liquid separation several times by centrifugation or the like can be used.

When the tetravalent metal hydroxide particle | grains obtained above are aggregated, it is preferable to disperse | distribute in water by a suitable method. As a method of disperse | distributing tetravalent metal hydroxide particle | grains in the water which is a main dispersion medium, a homogenizer, an ultrasonic disperser, a wet ball mill, etc. can be used besides the dispersion process by a normal stirrer. As for the dispersion method and the particle size control method, for example, the method described in "Distribution Technology Collection" [Information Agency, July, 2005] Chapter 3 "The latest development trend and selection criteria of various dispersion machines" It is available.

Since the average particle diameter of the abrasive grain in an abrasive | polishing avoids too low a polishing rate, it is preferable that it is 1 nm or more, as for a minimum, it is more preferable that it is 2 nm or more, and it is still more preferable that it is 10 nm or more.

Moreover, as an upper limit of the average particle diameter of an abrasive grain, it is preferable that it is 400 nm or less, It is more preferable that it is 300 nm or less, It is further more preferable that it is 250 nm or less from the point which is hard to damage the film | membrane to grind.

In the present invention, the average particle size of the abrasive grains refers to the Z-average Size obtained by the cumulant analysis using the dynamic light scattering method. For example, Malvern Co., Ltd. brand name: Zetasizer NanoS can be used.

As a more specific example, the abrasive is diluted with water to adjust the measurement sample so that the concentration of the abrasive grains is 0.1 parts by weight. About 1 mL of the obtained measurement sample is put into a 1 cm square cell, and it installs in a zetasizer nanoS. The refractive index of a dispersion medium is 1.33, the viscosity is 0.887, it measures at 25 degreeC, and the value shown as Z-average Size is read.

Moreover, it is preferable that the specific surface area of the said abrasive grain is 100 m <^2> / g or more from a viewpoint of improving the polishing rate by increasing a to-be-polishing film | membrane and chemical action. The specific surface area of a particle can be measured by BET method.

As a measuring method of the specific surface area by the said BET method, an abrasive | polishing agent is dried at 150 degreeC for 3 hours, and also vacuum deaeration drying at 150 degreeC for 1 hour, and a measurement sample is obtained. Using the gas adsorption amount measuring device AUTOSORB-1MP type manufactured by QUANTACHROME, the nitrogen adsorption method (measurement of adsorption to relative pressure is analyzed and the data are analyzed by a BET method based on the multimolecular adsorption theory, relative pressures of 0.1 and 0.2 And the BET three-point method using data of and 0.3).

As a minimum, it is preferable that the density | concentration of an abrasive grain is 0.01 weight part or more with respect to 100 weight part of abrasives, It is more preferable that it is 0.03 weight part or more, It is further more preferable that it is 0.05 weight part or more as a minimum. Moreover, as an upper limit, 5 weight part or less is preferable, 3 weight part or less is more preferable, 2 weight part or less is more preferable, and 1 weight part or less is especially preferable at the point which can make storage stability of an abrasive high. Do.

(additive)

The abrasive | polishing agent of this invention contains an additive. An additive refers to the substance contained other than water and an abrasive grain in order to adjust the dispersibility, grinding | polishing characteristic, storage stability, etc. of an abrasive grain here.

(Polyvinyl alcohol)

One specific aspect of the abrasive of the present invention is characterized by containing polyvinyl alcohol as the additive. Polyvinyl alcohol has the effect of improving the stability of an abrasive. When the hydroxyl group of the polyvinyl alcohol interacts with the abrasive grains, the aggregation can be suppressed, the change in the particle size of the abrasive can be suppressed, and the stability can be improved.

As explained so far, since the monomer of vinyl alcohol cannot be synthesized theoretically, the polyvinyl alcohol generally polymerizes carboxylic acid vinyl monomers such as vinyl acetate monomer to obtain polycarboxylic acid. It is obtained by saponification (hydrolysis). Thus, for example, polyvinyl alcohol, obtained by using a vinyl acetate monomer as a raw material, contains -OCOCH ₃ and hydrolyzed -OH group as the functional group in the molecule. In the present invention, polyvinyl alcohol is defined to include not only the homopolymer of vinyl alcohol (100% soap) but also a copolymer of vinyl carboxylate and vinyl alcohol.

Moreover, the polyvinyl alcohol derivative which introduce | transduced the functional group into polyvinyl alcohol can also be used, In this invention, such a polyvinyl alcohol derivative is also defined as polyvinyl alcohol.

As the polyvinyl alcohol derivative, for example, reactive polyvinyl alcohol (e.g., manufactured by Nihon Kosei Chemical Industry Co., Ltd., Gosepima® Z, etc.), cationic polyvinyl alcohol (e.g., Nihon Koseika Gaku Kogyo Kogyo Co., Ltd., Gosefima (registered trademark) K, etc.), Anionized polyvinyl alcohol (For example, Nihon Kosei Kagaku Co., Ltd., Goseran (registered trademark) L, Gosenar (registered trademark) T, etc.) And hydrophilic group modified polyvinyl alcohol (for example, Nihon Kosei Chemical Co., Ltd. make, Ecomati (trademark), etc.) etc. are mentioned.

In the abrasive of the present invention, the above-described compounds defined as polyvinyl alcohols may be used alone or in combination of two or more thereof for the purpose of adjusting selectivity and flatness. Moreover, it can also be used combining several polyvinyl alcohol from which saponification degree, polymerization degree, etc. which are mentioned later differ.

(Soap)

As explained so far, generally, polyvinyl alcohol has -OCOCH ₃ and -OH hydrolyzed as a functional group in a molecule | numerator, and defines the ratio which becomes -OH as a degree of saponification. When the degree of saponification is less than or equal to a predetermined value, hydrophobic -OCOCH ₃ is more effectively adsorbed onto the hydrophobic polysilicon film than the -OH, becomes a protective film and inhibits polishing, and consequently, it is estimated that a difference in polishing rate occurs. Thereby, there exists a tendency which can raise the grinding | polishing rate ratio (henceforth also a selectivity) with respect to the polysilicon film of a silicon oxide film. From this viewpoint, as a saponification degree of polyvinyl alcohol, 95 mol% or less of an upper limit is preferable, 90 mol% or less is more preferable, 88 mol% or less is more preferable, 85 mol% or less is especially preferable, 83 mol% or less is very preferable, and 80 mol% or less is extremely preferable.

Moreover, there is no restriction | limiting in particular in the lower limit of saponification degree, From a viewpoint of the solubility to water, 50 mol% or more is preferable, 60 mol% or more is more preferable, 70 mol% or more is more preferable. In addition, the saponification degree of polyvinyl alcohol can be measured based on JISK6726 (Japanese Industrial Standard, the polyvinyl alcohol test method).

In the case where a plurality of polyvinyl alcohols having different saponification degrees are used, the saponification degree of at least one polyvinyl alcohol may be 95 mol% or less, and from the viewpoint of improving the selectivity from each saponification degree and compounding ratio, It is more preferable if the average saponification degree is 95 mol% or less.

(Degree of polymerization)

In addition, the average degree of polymerization of the polyvinyl alcohol is not particularly limited, but the upper limit is preferably 3000 or less, more preferably 2000 or less, and most preferably 1000 or less from the viewpoint of increasing the polishing rate of the silicon oxide film. .

Moreover, as a minimum, from a viewpoint that a selectivity can be improved, 50 or more are preferable, 100 or more are more preferable, and 150 or more are more preferable. In addition, the average degree of polymerization of polyvinyl alcohol can be measured based on JISK6726 (polyvinyl alcohol test method) mentioned above.

From the viewpoint of improving the selectivity of the total concentration of the polyvinyl alcohol having a saponification degree of 95 mol% or less used as an additive, the lower limit is preferably 0.001 parts by weight or more, and 0.01 parts by weight or more based on 100 parts by weight of the abrasive. More preferably, 0.1 weight part or more is more preferable.

From the viewpoint of increasing the polishing rate of the silicon oxide film, the upper limit thereof is preferably 10 parts by weight or less, more preferably 5 parts by weight or less, further preferably 3 parts by weight or less with respect to 100 parts by weight of the abrasive.

(Second additive)

The abrasive of the present invention may contain another additive (hereinafter also referred to as "second additive") in addition to the polyvinyl alcohol for the purpose of adjusting the polishing characteristics. Specific examples of such additives include carboxylic acids, amino acids, amphoteric surfactants, anionic surfactants, nonionic surfactants, cationic surfactants, and the like, and these may be used alone or in combination of two or more thereof. Can be used. Especially, a carboxylic acid, an amino acid, and an amphoteric surfactant are preferable from a viewpoint of the balance of the dispersibility and grinding | polishing characteristic of an abrasive grain.

Among the above, the carboxylic acid has an effect of stabilizing pH, and specific examples thereof include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, and lactic acid.

Amino acids have the effect of improving the dispersibility of abrasive grains such as the tetravalent metal hydroxide particles and improving the polishing rate. Specifically, for example, arginine, lysine, aspartic acid, glutamic acid, asparagine, glutamine, histidine, and proline , Tyrosine, tryptophan, serine, threonine, glycine, alanine, β-alanine, methionine, cysteine, phenylalanine, leucine, varine, isoleucine and the like.

The amphoteric surfactant has the effect of improving the dispersibility of abrasive grains such as the tetravalent metal hydroxide particles and improving the polishing rate. Specifically, for example, betaine, β-alanine betaine, and lauryl beta. Phosphorus, stearylbetaine, lauryldimethylamine oxide, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazoliniumbetaine, lauric acid amide propyl betaine, palm oil fatty acid amide propyl betaine, la Usyl hydroxy sulfobetaine etc. are mentioned. Among them, betaine, β-alanine betaine and lauric acid amide propyl betaine are more preferable from the viewpoint of dispersibility stability.

Anionic surfactant has the effect of adjusting the flatness and in-plane uniformity of the to-be-polished surface after completion | finish of grinding | polishing, For example, lauryl triethanolamine, ammonium lauryl sulfate, polyoxyethylene alkyl ether triethanolamine And special polycarboxylic acid type polymer dispersants.

A nonionic surfactant has the effect of adjusting the flatness and in-plane uniformity of the to-be-polished surface after completion | finish of grinding | polishing, For example, 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 derivative, polyoxyethylene sorbitan monolaurate, Polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate, tetraoleic acid polyoxyethylene Sorbite, polyethylene glycol monolaurate, polyethylene It may be a recall monostearate, polyethylene glycol distearate, polyethylene glycol monooleate, polyoxyethylene alkylamine, polyoxyethylene hydrogenated castor oil, 2-hydroxyethyl methacrylate, an alkyl alkanolamide and the like.

Cationic surfactant has the effect of adjusting the flatness and in-plane uniformity of the to-be-polished surface after completion | finish of grinding | polishing, For example, coconut amine acetate, a stearyl amine acetate, etc. are mentioned.

When using these 2nd additives, the addition amount is 0.01 weight part or more and 10 weight part or less with respect to 100 weight part of abrasives from the point which can obtain the addition effect of an additive, suppressing sedimentation of an abrasive grain. It is preferable.

(Water soluble polymer)

Moreover, the abrasive | polishing agent of this invention may contain water-soluble polymers other than polyvinyl alcohol for the purpose of adjusting the flatness and in-plane uniformity of grinding | polishing characteristic. The water-soluble polymer is defined herein as a polymer that dissolves in 0.1 g or more with respect to 100 g of water.

There is no restriction | limiting in particular as a specific example of the said water-soluble polymer, For example, polysaccharides, such as alginic acid, pectic acid, carboxymethylcellulose, agar, curdlan, pullulan:

Polycarboxes such as polyaspartic acid, polyglutamic acid, polylysine, polymalic acid, polyamic acid, polymaleic acid, polyitaconic acid, polypmaric acid, poly (p-styrenecarboxylic acid), polyamic acid, polyglyoxylic acid and the like Acids and salts thereof;

Vinyl polymers such as polyvinylpyrrolidone and polyacrolein;

Acrylic polymers such as polyacrylamide and polydimethylacrylamide;

Polyethylene glycol, polyoxypropylene, polyoxyethylene-polyoxypropylene condensate, polyoxyethylene-polyoxypropylene block polymer of ethylenediamine, and the like. A copolymer may be sufficient as the said polycarboxylic acid. Moreover, as the salt, an ammonium salt, a sodium salt, etc. are mentioned, for example.

When using these water-soluble polymers, since the addition effect of a water-soluble polymer can be acquired, suppressing sedimentation of an abrasive grain, it is preferable that addition amount is 0.01 weight part or more and 5 weight part or less with respect to 100 weight part of abrasives.

(Characteristic of polishing agent)

(pH)

It is preferable that pH of the abrasive of this invention exists in the range of 3.0 or more and 12.0 or less from the point which is excellent in the storage stability and polishing rate of an abrasive. The lower limit of the pH mainly affects the polishing rate, preferably 3.0 or more, more preferably 4.0 or more, and even more preferably 5.0 or more. In addition, the upper limit mainly affects the polishing rate, preferably 12.0 or less, more preferably 11.0 or less, and even more preferably 10.0 or less.

pH can be adjusted by addition of acid components, such as an inorganic acid and an organic acid, and alkali components, such as ammonia, sodium hydroxide, tetramethylammonium hydroxide (TMAH), and imidazole. Moreover, in order to stabilize pH, you may add a buffer. As such a buffer, acetate buffer, a phthalate buffer, etc. are mentioned, for example.

PH of the abrasive | polishing agent of this invention can be measured with a pH meter (for example, Model PH81 by Yokogawa Denki Corporation). Specifically, for example, phthalate pH buffer (pH 4.01) and neutral phosphate pH buffer (pH6.86) as a standard buffer, the pH meter is calibrated by two points, and then the electrode of the pH meter is placed in the abrasive. After 2 minutes or more, the value after stabilization is measured. At this time, the temperature of the liquid of the standard buffer and the abrasive is both 25 ° C.

(Zeta potential)

The zeta potential of the abrasive grain in the abrasive is preferably from -20 mV to +20 mV, more preferably from OmV to +20 mV, from the viewpoint of improving the selectivity to polysilicon. In addition, the zeta potential measurement can use, for example, Malvern Co., Ltd. brand name: Zetasizer 3000HS, For example, it can measure by diluting an abrasive with water so that the recommended amount of scattered light of Zetasizer 3000HS may be sufficient.

The abrasive | polishing agent of this invention may be preserve | saved as a one-component abrasive | polishing agent containing the said abrasive grain, the said additive, and water, and is the two-component type which divided the slurry containing at least abrasive grains and water, and the addition liquid containing at least an additive and water. You may save as an abrasive set.

It is preferable that the said polyvinyl alcohol and water-soluble polymer are contained in addition liquid in two liquids. In addition, it is preferable that the said buffer liquid is contained in addition liquid in two liquids.

The abrasive set is mixed immediately before or at the time of polishing to become an abrasive. Moreover, in either case, you may save as a concentrated slurry which reduced content of water, a concentrated addition liquid, and a concentrated abrasive, and may dilute and use with water at the time of grinding | polishing.

When storing as a two-part abrasive which divided the slurry and the addition liquid, the polishing rate can be adjusted by arbitrarily changing the combination of these two liquids. When polishing with a two-part abrasive, there is a method shown below as a supply method of the abrasive on the polishing platen. For example, a method of feeding a slurry and an additive liquid into respective pipes, joining and mixing these pipes, and supplying a concentrated slurry, a concentrated additive liquid, and water to each pipe, merging and mixing them, and supplying them. The method, the method of mixing a slurry and an addition liquid previously, and supplying, the method of mixing and supplying a concentrated slurry, a concentrated addition liquid, and water previously, etc. can be used.

In the case of a one-component abrasive containing abrasive grains, additives, and water, as a method of supplying the abrasive on the polishing surface, for example, a method of directly feeding and supplying an abrasive, a concentrated abrasive and water are delivered to respective pipes, The method of joining, mixing, and supplying, the method of previously mixing and supplying a concentrated abrasive | polishing agent, and water can be used.

In the polishing method of the present invention, the substrate and the polishing plate are relatively pressed while pressing the substrate on which the polishing film is formed to press the polishing pad of the polishing platen, and supplying the abrasive of the present invention between the polishing film and the polishing pad. It is characterized in that the polishing to move the polishing finish.

As a board | substrate, the board | substrate which concerns on semiconductor element manufacture, for example, the board | substrate with which the insulating film was formed on the semiconductor substrate in which the STI pattern, the gate pattern, the wiring pattern, etc. was formed is mentioned. The film to be polished includes an insulating film formed on such a pattern, for example, a silicon oxide film or a polysilicon film. In the present invention, the film to be polished may be a single film or a plurality of films. When a plurality of films are exposed on the substrate surface, they can be regarded as to-be-polished films.

By polishing the silicon oxide film or the polysilicon film formed on the semiconductor substrate with the abrasive, the unevenness of the surface of the silicon oxide film layer can be eliminated and a smooth surface can be provided over the entire surface of the semiconductor substrate. Thus, it is preferable that the abrasive | polishing agent of this invention is used in order to grind | polish the to-be-polished surface containing a silicon oxide at least on the surface.

When at least the surface of the to-be-finished film contains silicon oxide and the polishing stop layer is provided in the lower layer, it is preferable that a polishing stop layer is a polysilicon film, a silicon nitride film, etc. When the polishing stop layer having a lower polishing rate than silicon oxide is exposed, the polishing is stopped to prevent excessive polishing of the silicon oxide film, which is the film to be polished, thereby improving the flatness after polishing of the film to be polished.

Moreover, the abrasive | polishing agent of this invention can be used suitably also for STI (slow trench isolation). In order to use for STI, it is preferable that the selectivity with respect to the said polishing stop layer of a silicon oxide film is 100 or more. This is because when the selectivity is less than 100, the difference between the silicon oxide film polishing rate and the polysilicon film polishing rate is small, and it becomes difficult to stop polishing at a predetermined position during STI. If the said selectivity is 100 or more, stop of grinding becomes easy and it is more suitable for STI.

It can also be used for polishing a premetal insulating film. In addition to silicon oxide, for example, phosphorus-silicate glass or boron-phosphate-silicate glass is used as the premetal insulating film, and silicon oxyfluoride, fluorinated morphocarbon and the like can also be used.

Hereinafter, the grinding | polishing method is demonstrated taking the case of the semiconductor substrate in which the insulating film was formed as an example.

In the polishing method of the present invention, a general polishing apparatus having a holder capable of holding a substrate having a to-be-polished film such as a semiconductor substrate and a polishing plate on which a polishing pad can be attached can be used.

To the holder and the polishing platen, motors and the like, each of which can change the rotation speed, are attached. For example, the polishing apparatus by the Ebara Corporation make: model number EPO-111 can be used.

As the polishing pad, a general nonwoven fabric, foam, non-foaming foam, or the like can be used. As a material, polyurethane, acrylic, polyester, acrylic ester copolymer, polytetrafluoroethylene, polypropylene, polyethylene, poly4-methylpentene, Resin, such as cellulose, a cellulose ester, nylon (trade name), polyamide, such as aramid, a polyimide, polyimide amide, a polysiloxane copolymer, an oxirane compound, a phenol resin, polystyrene, polycarbonate, an epoxy resin, can be used.

In particular, foamed polyurethane and non-foamed polyurethane are preferable from the viewpoint of polishing rate and flatness.

Moreover, from the viewpoint of improving flatness, the shore D hardness of the polishing pad is preferably 70 or more, more preferably 75 or more, and even more preferably 80 or more. Shore D hardness can be measured with a Shore D hardness tester (for example, Asuka rubber hardness tester type D of a polymeric instrument).

Moreover, it is preferable to give the polishing pad the groove process by which an abrasive | polishing agent accumulates. Although there are no limitations on the polishing conditions, the rotational speed of the surface plate is preferably 200 min ⁻¹ or less so that the semiconductor substrate does not protrude, and the pressure (processing load) applied to the semiconductor substrate is preferably 100 kPa or less so that a polishing wound does not occur. While polishing, the polishing pad is continuously supplied to the polishing pad by a pump or the like. Although there is no restriction | limiting in this supply amount, It is preferable that the surface of a polishing pad is always covered with an abrasive | polishing agent.

It is preferable to remove the particle | grains which wash | cleaned the semiconductor substrate after completion | finish of polishing well in flowing water, and adhered to the board | substrate. In addition to pure water, dilute hydrofluoric acid and ammonia water may be used for washing | cleaning, and you may use a brush together in order to raise washing efficiency.

In addition, after washing, it is preferable to dry after dropping the water droplets affixed on a semiconductor substrate using a spin dryer or the like.

As a manufacturing method of the insulating film using the abrasive | polishing agent of this invention, the CVD method represented by the low pressure CVD method, the semi-normal pressure CVD method, the plasma CVD method, etc., the rotation coating method which apply | coats a liquid raw material to a rotating substrate, etc. are mentioned.

The silicon oxide film by the low pressure CVD method is obtained by, for example, thermally reacting monosilane (SiH ₄ ) with oxygen (0 ₂ ).

In addition, the silicon oxide film by the quasi-atmospheric pressure CVD method is obtained by thermally reacting tetraethoxysilane (Si (OC ₂ H ₅ ) ₄ ) and ozone (0 ₃ ), for example.

As another example, a silicon oxide film is similarly obtained even by plasma-reacting tetraethoxysilane and oxygen.

The silicon oxide film by the rotation coating method is obtained by apply | coating the liquid raw material containing inorganic polysilazane, inorganic siloxane, etc. on a board | substrate, and thermosetting reaction by a furnace body etc., for example.

As a film forming method of a polysilicon film, the low pressure CVD method which heat-reacts monosilane, the plasma CVD method which plasma-reacts monosilane, etc. are mentioned, for example.

In order to stabilize film | membrane quality, such as a silicon oxide film and a polysilicon film obtained by the above method, you may heat-process at the temperature of 200-1000 degreeC as needed.

In addition, a small amount of boron (B), phosphorus (P), carbon (C), etc. may be contained in the silicon oxide film obtained by the above method in order to improve embedding.

The abrasive and the polishing method of the present invention can be applied to films other than an insulating film such as a silicon oxide film. For example, high dielectric constant films such as Hf-based, Ti-based and Ta-based oxides, semiconductor films such as silicon, amorphous silicon, SiC, SiGe, Ge, GaN, GaP, GaAs, organic semiconductors, phase change films such as GeSbTe, And inorganic conductive films such as ITO, polyimide-based, polybenzoxazole-based, acrylic, epoxy-based, and phenol-based polymer resin films.

In addition, the abrasive and the polishing method of the present invention can be applied not only to film-like materials but also to various substrate materials such as glass, silicon, SiC, SiGe, Ge, GaN, GaP, GaAs, sapphire, and plastics.

Further, according to the abrasive and polishing method of the present invention, not only the production of semiconductor devices, but also optical components such as image display devices such as TFTs and organic ELs, photomasks, lenses, prisms, optical fibers, and single crystal scintillators, optical switching elements, It can be used for the manufacture of magnetic memory devices such as optical elements such as optical waveguides, light emitting elements such as solid state lasers and blue laser LEDs, magnetic disks and magnetic heads.

Example

(Synthesis of Tetravalent Metal Hydroxide)

430 g of Ce (NH ₄ ) ₂ (NO ₃ ) ₆ was dissolved in 7300 g of pure water, and then 240 g of ammonia water (25 wt% aqueous solution) was added dropwise while stirring the solution to contain 160 g of cerium hydroxide. A dispersion (yellow white) was obtained.

The liquid dispersion of cerium hydroxide obtained was subjected to solid-liquid separation by centrifugation (4000 min ^-1 for 5 minutes). The liquid was removed, newly added pure water, and centrifuged again under the above conditions. This operation was repeated four times, and washing was performed. The specific surface area of the obtained particles was measured according to the above BET method and found to be 200 m ² / g.

In addition, 10 g of the obtained particles and 990 g of water were mixed and dispersed using an ultrasonic cleaner to prepare a concentrated cerium hydroxide slurry (1% by weight of cerium hydroxide concentration).

It was 115 nm when this concentrated cerium hydroxide slurry was diluted with water, and the average particle diameter (Z-average Size) was measured using the Malvern company make, brand name Zetasizer NanoS. As a measuring method, the concentration of tetravalent metal hydroxide particles is diluted with water so as to be 0.1 parts by weight, and about 1 mL is placed in a 1 cm square cell and installed in the zetasizer nanoS. The refractive index of the dispersion medium was 1.33, the viscosity was 0.887, the measurement was performed at 25 degreeC, and the value shown as Z-average Size was read.

Moreover, in order to measure the zeta potential of the particle | grains in a concentrated cerium hydroxide slurry, after diluting with water at a suitable density | concentration, it measured +43 mV using the product made by Malvern Corporation, brand name Zeta sizer 3000HS. In addition, the measurement was performed at 25 degreeC, diluting a concentrated cerium hydroxide slurry with water so that the recommended scattered light amount of the zetasizer 3000HS might be sufficient.

(Example 1)

100 g of concentrated additive solution containing 5% by weight of polyvinyl alcohol [Kuraray Co., Ltd. PVA-203, average degree of polymerization 300, saponification degree 88 mol%], 0.4% by weight of acetic acid, 0.66% by weight of imidazole and 93.94% by weight of water. 100 g of the concentrated cerium hydroxide slurry and 800 g of water were mixed to prepare an abrasive containing 0.1 wt% of cerium hydroxide concentration and 0.5 wt% of polyvinyl alcohol concentration. The pH of the abrasive was 6.6, the average particle diameter was 140 nm, and the zeta potential was +6 mV. In addition, the average particle diameter and zeta potential were measured similarly to the above.

(Example 2)

In the same manner as in Example 1, except that 5% by weight of Kuraray Co., Ltd. PVA-403, average polymerization degree 300, and saponification degree 80 mol% were used as the polyvinyl alcohol used in the concentrated additive solution, 0.1 wt% cerium hydroxide concentration and polyvinyl alcohol An abrasive containing a concentration of 0.5% by weight was prepared.

(Example 3)

As the polyvinyl alcohol used for the concentrated addition liquid, the cerium hydroxide concentration was 0.1 wt% and the polyvinyl alcohol concentration in the same manner as in Example 1, except that 5 wt% of Kuraray Co., Ltd. PVA-205, average polymerization degree 500 and saponification degree 88 mol% were used. An abrasive containing 0.5% by weight was prepared.

(Example 4)

As the polyvinyl alcohol used for the concentrated addition liquid, the cerium hydroxide concentration was 0.1 wt% and the polyvinyl alcohol concentration in the same manner as in Example 1, except that 5 wt% of Kuraray Co., Ltd. PVA-405, an average degree of polymerization of 500 and a saponification degree of 80 mol% were used. An abrasive containing 0.5% by weight was prepared.

(Example 5)

As the polyvinyl alcohol used for the concentrated addition liquid, the cerium hydroxide concentration was 0.1 wt% and the polyvinyl alcohol concentration in the same manner as in Example 1, except that 5 wt% of Kuraray Co., Ltd. PVA-505, average polymerization degree 500, and saponification degree 73 mol% were used. An abrasive containing 0.5% by weight was prepared.

(Example 6)

100 g of concentrated additive solution containing 2% by weight of polyvinyl alcohol (Kurarese PVA-217, average degree of polymerization 1700, saponification degree 88 mol%), 0.4% by weight acetic acid, 0.66% by weight of imidazole and 96.94% by weight of water. 200 g of the obtained concentrated cerium hydroxide slurry and 700 g of water were mixed to prepare an abrasive containing 0.2% by weight of cerium hydroxide concentration and 0.2% by weight of polyvinyl alcohol.

(Example 7)

100 g of concentrated addition solution containing 10% by weight of polyvinyl alcohol (Curarese Co., Ltd., cation modification, average degree of polymerization 600, saponification degree 77 mol%), 0.4% by weight of acetic acid, 0.66% by weight of imidazole and 88.94% by weight of water , 200 g of the concentrated cerium hydroxide slurry and 700 g of water were mixed to prepare an abrasive containing 0.2% by weight of cerium hydroxide concentration and 1% by weight of polyvinyl alcohol concentration.

(Comparative Example 1)

100 g of the concentrated cerium hydroxide slurry and 900 g of water were mixed, and an abrasive was prepared by adding a 5 wt% aqueous solution of imidazole to a pH of 6.6.

(Comparative Example 2)

As the polyvinyl alcohol used for the concentrated addition liquid, the cerium hydroxide concentration was 0.1 wt% and the polyvinyl alcohol concentration in the same manner as in Example 1, except that 5 wt% of Kuraray Co., Ltd. PVA-103, average polymerization degree 300, and saponification degree 98 mol% were used. An abrasive containing 0.5% by weight was prepared.

(Comparative Example 3)

As the polyvinyl alcohol used for the concentrated addition liquid, the cerium hydroxide concentration was 0.1 wt% and the polyvinyl alcohol concentration in the same manner as in Example 1, except that 5 wt% of Kuraray Co., Ltd. PVA-105, average polymerization degree 500, and saponification degree 98 mol% were used. An abrasive containing 0.5% by weight was prepared.

(Comparative Example 4)

1 kg of cerium oxide particles, 23 g of a commercially available ammonium polyacrylate salt solution (40% by weight), and 8977 g of deionized water were mixed, and ultrasonic dispersion was performed while stirring.

Filtration was carried out with a 1 micron filter, and deionized water was added to obtain a concentrated cerium oxide slurry having 5% by weight of cerium oxide.

100 g of the above-mentioned concentrated cerium oxide slurry and 900 g of water were mixed, and 1N nitric acid was added until pH became 42, and the abrasive | polishing agent (cerium oxide particle concentration: 0.5 weight%) was prepared.

(Comparative Example 5)

100 g of concentrated additive solution containing 2% by weight of polyvinyl alcohol (Kurarese PVA-117, average degree of polymerization 1700, saponification degree 98 mol%), 0.4% by weight of acetic acid, 0.66% by weight of imidazole and 96.94% by weight of water. 200 g of the obtained concentrated cerium hydroxide slurry and 700 g of water were mixed to prepare an abrasive containing 0.2% by weight of cerium hydroxide concentration and 0.2% by weight of polyvinyl alcohol.

The pH, average particle diameter, and zeta potential of each abrasive of Examples 2-6 and Comparative Examples 1-5 were measured similarly to Example 1.

(Polishing of insulating film)

Evaluation wafer (1) in which a silicon oxide (SiO ₂ ) having a thickness of 1000 nm was formed on a front surface of a silicon (Si) substrate having a diameter of 200 mm on a substrate holder of a polishing apparatus (product number EPO-111 manufactured by Ebara Corporation). Fixed). In addition, a polishing pad IC-1000 (product number, groove shape: perforate made by Rodale Company) made of porous urethane resin was attached to a polishing plate having a diameter of 600 mm.

The substrate holder was pressed against the polishing pad so that the silicon oxide film of the evaluation wafer 1 was in contact with the polishing pad, and the processing load was set to 30 kPa. While the abrasive prepared above was dripped on the polishing pad at a rate of 200 mL / min, the polishing platen and the substrate holder were operated at 50 min ⁻¹ , respectively, and the wafer for evaluation was polished for 60 seconds.

The wafer 1 for evaluation after polishing was well washed with pure water and dried. Then, the residual film thickness of silicon oxide was measured using the optical interference film thickness apparatus (Nanometrics make, brand name: Nanospec AFT-5100). Here, the silicon oxide polishing rate [RR (SiO ₂ )] per minute was determined from (reduced amount of silicon oxide film) / (polishing time).

Moreover, the evaluation wafer 2 in which the polysilicon (poly-Si) of 250 nm in thickness was formed on the silicon (Si) substrate of diameter 200mm on the whole surface was prepared, and it grind | polished for 60 second by the same method as the above. The wafer 2 for evaluation after polishing was well washed with pure water and dried. Then, the remaining film thickness of polysilicon was measured similarly to the above, and the polysilicon polishing rate [RR (poly-Si)] per minute was calculated | required.

From the resultant value, and calculating the selectivity of the silicon oxide film and polysilicon, from _{RR (SiO 2) / RR (} poly-Si).

Further, the prepared silicon (Si), a wafer evaluation (3) formed on the entire surface of the silicon oxide film (SiO ₂₎ having a thickness of 1000nm on a substrate diameter of 200mm, and polishing for 60 seconds in the same manner as described above. After the polishing, the wafer 3 for evaluation was washed well with pure water, hydrofluoric acid, and ammonia water, and dried, and the polishing wound number was counted by a scanning electron microscope defect inspection device. The relative abrasive scratches were calculated by setting the abrasive scratches of Comparative Example 4 to 1.

The result of each said Example and each comparative example was put together in Table 1, and was shown.

[Table 1]

As is apparent from Table 1, it is understood that the abrasives of Examples 1 to 6, which contain cerium hydroxide and polyvinyl alcohol having a saponification degree of 95 mol% or less, are excellent in polishing rate of silicon oxide film and selectivity to polysilicon. have. Comparative Examples 1 and 4 that do not contain the polyvinyl alcohol are inferior in selectivity to polysilicon. In addition, as apparent from the comparison with Comparative Example 4, by using cerium hydroxide particles, it is possible to greatly reduce the scratches.

In addition, the graph which taken the saponification degree of the polyvinyl alcohol in each Example and Comparative Examples 2, 3, 5 on the horizontal axis and the selectivity on the vertical axis is shown in FIG. From this figure, it can also be read that the selectivity tends to increase as the saponification degree of polyvinyl alcohol becomes small, and it turns out that the saponification degree of polyvinyl alcohol is an important factor for selectivity.

[Industrial applicability]

In the CMP technique for planarizing an STI insulating film, a premetal insulating film, an interlayer insulating film, and the like, an insulating film such as a silicon oxide film can be polished at a high speed and with a low abrasion scratch. An abrasive having a polishing rate ratio, an abrasive set for storing the abrasive, and a substrate polishing method using the abrasive can be provided.

Claims (11)

As an abrasive containing water, abrasive grains and additives,
The abrasive grains comprise tetravalent metal hydroxide particles,
The abrasive | polishing agent whose at least 1 component of the said additive is polyvinyl alcohol of 95 mol% or less of saponification degree. The method of claim 1,
The abrasive grain is an average particle diameter of 1 nm or more and 400 nm or less. 3. The method according to claim 1 or 2,
The abrasive | polishing agent whose pH of an abrasives is 3.0 or more and 12.0 or less. 4. The method according to any one of claims 1 to 3,
The abrasive | polishing agent whose content of the said abrasive grain is 0.01 weight part or more and 5 weight part or less with respect to 100 weight part of abrasives. 5. The method according to any one of claims 1 to 4,
The abrasive | polishing agent whose zeta potential in the abrasive | polishing agent of the said abrasive grain is -20 mV or more and +20 mV or less. The method according to any one of claims 1 to 5,
The abrasive | polishing agent whose content of the said polyvinyl alcohol is 0.01 weight part or more with respect to 100 weight part of abrasives. 7. The method according to any one of claims 1 to 6,
An abrasive | polishing agent used for grinding the to-be-polished surface containing a silicon oxide at least on the surface. 8. The method according to any one of claims 1 to 7,
An abrasive whose tetravalent metal hydroxide is at least one of a rare earth metal hydroxide and a zirconium hydroxide. The substrate and the polishing plate are pressed while pressing the substrate on which the polishing film is formed to the polishing pad of the polishing platen and supplying the abrasive according to any one of claims 1 to 8 between the polishing film and the polishing pad. A method of polishing a substrate, which moves relatively to polish a polished film. 10. The method of claim 9,
The polishing method of the board | substrate whose Shore D hardness of a polishing pad is 70 or more. A set of abrasives, which are divided into and preserved in a slurry and an additive liquid, are mixed immediately before or at the time of polishing to be the abrasive according to any one of claims 1 to 8, wherein the slurry contains abrasive grains and water, and the additive liquid is an additive. And abrasive set comprising water.

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