JP5105869B2 - Polishing liquid composition - Google Patents

Description

  The present invention relates to a polishing liquid composition and a method for producing a semiconductor device using the same.

  Along with the high integration of semiconductor devices, for example, the storage capacity of semiconductor devices such as memory devices has increased dramatically. In order to achieve high integration of semiconductor devices, miniaturization of elements is essential. However, in order to realize miniaturization of elements, a surface obtained through a polishing process (hereinafter referred to as “polishing”) in a polishing process in the manufacturing process of a semiconductor device. It may be necessary to improve the flatness of the surface.

  In recent years, polishing liquid compositions containing ceria (cerium oxide) particles have been widely used as polishing liquid compositions used in the polishing step. Ceria particles have a lower hardness than silica particles and alumina particles. Therefore, when a thin film having an uneven surface is polished using a polishing composition containing ceria particles, the surface is hardly damaged during polishing, and the flatness of the polished surface is somewhat improved.

  As a polishing composition containing ceria particles, there has been proposed a polishing composition that further contains a copolymer of ammonium acrylate and methyl acrylate as an additive (see, for example, Patent Document 1). When this polishing liquid composition is used, the flatness of the polishing surface is improved more than when an abrasive containing only silica particles is used, but the flatness is still not sufficient. Specifically, for example, when a polishing composition containing the above-described additive is used for polishing a thin film having an uneven surface, not only convex portions but also concave portions are simultaneously polished. A phenomenon (dishing phenomenon) in which the corresponding portion bends in a dish shape occurs. This dishing phenomenon occurs remarkably when the distance between adjacent convex portions is larger, that is, when the ratio of the total area of the concave portions visible when the concave and convex surfaces are viewed in plan is large (when the concave surface density is large).

In order to solve the above-mentioned dishing problem, a polishing composition containing ceria particles having a higher content of a copolymer of ammonium acrylate and methyl acrylate is used, or an azole group is incorporated into the molecule 3 It has been proposed to use a polishing liquid composition containing a compound containing at least one compound, an oxidizing agent, an amino acid, and the like (for example, see Patent Document 2). However, using these polishing liquid compositions does not sufficiently solve the dishing problem.
JP 2000-17195 A JP 2005-340755 A

  Accordingly, the present invention provides a polishing liquid composition that can form a surface with high flatness regardless of the size of the recess surface density to be polished, and a method of manufacturing a semiconductor device using the same.

  The polishing composition of the present invention comprises a component A consisting of one or more selected from the group consisting of dihydroxyethyl glycine, aminopolycarboxylic acid, and non-metal salt of aminopolycarboxylic acid, a polyoxyalkylene alkyl ether, And ceria particles, a polycarboxylic acid polymer dispersant, and an aqueous medium.

Further, the polishing composition of the present invention comprises a component A consisting of one or more selected from the group consisting of dihydroxyethyl glycine, aminopolycarboxylic acid, and non-metal salt of aminopolycarboxylic acid, and a polyoxyalkylene alkyl. It is obtained by mixing ether, ceria particles, a polycarboxylic acid polymer dispersant, and an aqueous medium.

  The method of manufacturing a semiconductor device according to the present invention includes a step of forming a thin film on a semiconductor substrate, that is, a thin film forming step of forming a thin film on one main surface of the semiconductor substrate, and a pattern on the surface of the semiconductor substrate. A patterning step, that is, a concave / convex surface forming step in which the thin film semiconductor substrate forms a concave / convex pattern on the opposite side of the wafer surface, and a polishing step in which the concave / convex surface is polished using the polishing liquid composition of the present invention. Including.

  ADVANTAGE OF THE INVENTION According to this invention, the polishing liquid composition which can form the surface with high flatness irrespective of the magnitude | size of the recessed part surface density of grinding | polishing object, and the manufacturing method of a semiconductor device using the same can be provided.

  The polishing composition of the present embodiment comprises at least component A consisting of one or more selected from the group consisting of dihydroxyethylglycine (hereinafter also referred to as “DHEG”), aminopolycarboxylic acid, and a non-metal salt thereof. It is obtained by adding polyoxyalkylene alkyl ether, ceria particles, and polycarboxylic acid polymer dispersant to an aqueous medium. If necessary, a pH adjuster or the like is added to the aqueous medium.

  In the polishing liquid composition of the present embodiment, it is possible to form a polished surface with high flatness by including the component A and polyoxyalkylene alkyl ether as additives. More specifically, in the polishing using the polishing composition of this embodiment, first, the convex portions are selectively polished, and the concave portions are prevented from being polished. Therefore, for example, even when the concave surface density on the surface to be polished is large or the diameter of the semiconductor substrate is large, the occurrence of dishing is suppressed, and a polished surface with excellent flatness can be obtained.

  The polishing mechanism using the polishing composition of this embodiment is presumed as follows. Component A in the polishing composition of this embodiment is adsorbed on the surface of the ceria particles to form a film. As for the polyoxyalkylene alkyl ether, when an example of the polishing liquid composition of the present embodiment is supplied on the uneven surface of a thin film to be polished, for example, the polyoxyalkylene alkyl ether is adsorbed on the uneven surface. Form a film. When the coating is formed on the ceria particle surface and the uneven surface of the thin film in this way, the ceria particles are less likely to act on the uneven surface of the thin film, and polishing is suppressed. When the polishing load equal to or higher than the threshold is not applied to the thin film, the thin film is not polished.

  When a thin film having an uneven surface is polished, a polishing load higher than a set load locally set in the polishing apparatus is usually applied to the convex portion, and a polishing load lower than the set load is applied to the concave portion. However, when polishing is performed by supplying an example of the polishing composition of the present embodiment to the uneven surface, a polyoxyalkylene alkyl ether film is formed on the uneven surface. In combination with the polishing suppressing action due to the adsorbed film containing component A, first, only the convex portion is selectively polished, and the step between the convex portion and the concave portion is gradually reduced. When the level difference between the convex portion and the concave portion is further reduced by further polishing, the polishing load applied to the film surface becomes substantially constant over the entire surface, and the load is approximately the same as the set load. As described above, according to the polishing using the polishing composition of the present embodiment, the occurrence of dishing is suppressed regardless of the size of the recess surface density or the diameter of the semiconductor substrate on the surface to be polished, Therefore, a polished surface with excellent flatness can be obtained. However, these assumptions do not limit the present invention.

For example, if the set load set in the polishing apparatus is set to such a value that almost no polishing is performed on a flat surface, the level difference between the concave portion and the convex portion is eliminated. Polishing is hardly performed, and unnecessary polishing can be easily prevented.

  The polishing liquid composition of the present embodiment is a component comprising one or more selected from the group consisting of DHEG, aminopolycarboxylic acid, and non-metal salts thereof, from the viewpoint of realizing good planarization of the uneven surface. Although A is included, among these, it is more preferable that DHEG is included from the viewpoint of sufficiently suppressing the cross-linking and aggregation of the ceria particles and further improving the dispersion stability of the polishing composition. When the non-metallic salt of aminopolycarboxylic acid is contained in the polishing liquid composition of the present embodiment, the non-metallic salt is preferably an ammonium salt or an amine salt, and more preferably an ammonium salt. In addition, from the viewpoint of avoiding contamination of the semiconductor device by metal during the manufacturing process, the salt of aminopolycarboxylic acid needs to be a nonmetallic salt of aminopolycarboxylic acid.

The aminopolycarboxylic acid contained in the polishing composition of this embodiment has a structure represented by the following formula in the molecule with two or more carboxyl groups.
> N—CH ₂ COOH or> N—CH ₂ —CH ₂ COOH

Examples of the aminopolycarboxylic acid include compounds having the following structures a) to e) when the —CH ₂ COOH group or —CH ₂ —CH ₂ COOH group in the above formula is represented as X.
a) RNX ₂ type compounds b) NX ₃ type compounds _{c) RNX-CH 2 -CH 2} -NX-R type compound _{d) RNX-CH 2 -CH 2} -NX 2 type compounds e) X ₂ N -R'-NX type ₂ compound and compound containing 4 or more of X

In a) to e), R is a hydrogen atom (H) or a saturated or unsaturated hydrocarbon group composed of a linear, molecular chain or cyclic skeleton having 1 to 8 carbon atoms, and R ′ is carbon. It is a saturated or unsaturated hydrocarbon group having a linear, molecular chain or cyclic skeleton of formulas 1-8. The hydrogen atom bonded to the carbon atom of R and R ′ is substituted with —OH group, —NH ₂ group, —SH group, —SO ₃ H group, —PO ₃ H ₂ group or —NO ₂ group. Also good.

From the viewpoint of realizing better planarization of the uneven surface, the compound a) is preferably iminodiacetic acid, N-methyliminodiacetic acid, or hydroxyethyliminodiacetic acid. Compound b) is preferably nitrilotriacetic acid. Compound c) is preferably N, N′-ethylenediaminediacetic acid. Compound d) is preferably N′-hydroxyethyl-N, N, N′-triacetic acid. The compound e) is preferably ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid, triethylenetetraaminehexaacetic acid or the like, and more preferably EDTA.

The polyoxyalkylene alkyl ether contained in the polishing composition of this embodiment is represented by the following formula. The polishing liquid composition of this embodiment may contain only 1 type in the polyoxyalkylene alkyl ether represented by a following formula, and may contain 2 or more types.
R ¹ —O— (AO) _n —H

In this formula, n is the average number of moles added. R ¹ is an alkyl group having 4 to 24 carbon atoms or an alkenyl group having 4 to 24 carbon atoms, more preferably an alkyl group having 6 to 18 carbon atoms or an alkenyl group having 6 to 18 carbon atoms, and R ¹ is More preferably, it is an alkyl group having 6 to 8 carbon atoms.

AO is an oxyalkylene group having 2 to 4 carbon atoms, more preferably an oxyalkylene group having 2 to 3 carbon atoms, and further preferably an oxyalkylene group having 2 carbon atoms. AO may be the same or different, that is, (AO) _n may be composed of one kind of oxyalkylene group, but may contain two or more kinds of oxyalkylene groups. AO addition may be block or random, that is, when (AO) _n contains two or more oxyalkylene groups, the arrangement of the oxyalkylene groups may be block or random.

  n is preferably a number of 1 to 50, more preferably a number of 2 to 20, and even more preferably a number of 2 to 4.

Specific examples of the polyoxyalkylene alkyl ether include butanol, pentanol, hexanol, 2-ethylhexanol, octanol, decanol, dodecanol, 2-butyloctanol, isodecanol, tridecanol, tetradecanol, octadecanol, oleyl alcohol, Secondary alcohol obtained by introducing OH group into —CH ₂ — group such as 2-hexyldecanol or n-paraffin is selected from the group consisting of ethylene oxide (EO), propylene oxide (PO) and butylene oxide. It is preferable that at least one kind is added. What added at least 1 type chosen from the group which consists of (EO) and (PO) to the said secondary alcohol is more preferable, and what added (EO) to the said secondary alcohol is still more preferable.

  More specifically, examples of the polyoxyalkylene alkyl ether include ethylene glycol butyl ether, ethylene glycol pentyl ether, ethylene glycol hexyl ether, ethylene glycol 2-ethylhexyl ether; diethylene glycol butyl ether, diethylene glycol hexyl ether, diethylene glycol 2-ethylhexyl ether; triethylene Glycol butyl ether, triethylene glycol hexyl ether, triethylene glycol 2-ethylhexyl ether; tetraethylene glycol butyl ether, tetraethylene glycol hexyl ether, tetraethylene glycol 2-ethylhexyl ether; propylene glycol butyl ether, propylene glycol pentyl ether Ter, propylene glycol hexyl ether, propylene glycol 2-ethylhexyl ether; dipropylene glycol butyl ether, dipropylene glycol hexyl ether, dipropylene glycol 2-ethylhexyl ether; tripropylene glycol butyl ether, tripropylene glycol hexyl ether, tripropylene glycol 2-ethylhexyl Ether; tetrapropylene glycol butyl ether, tetrapropylene glycol hexyl ether, tetrapropylene glycol 2-ethylhexyl ether, and the like. In the polishing liquid composition of this embodiment, only 1 type of these polyoxyalkylene alkyl ethers may be contained, and 2 or more types may be contained.

Other polyoxyalkylene alkyl ethers include polyoxyethylene (1) lauryl ether, polyoxyethylene (2) lauryl ether, polyoxyethylene (3) lauryl ether, polyoxyethylene (4) lauryl ether, polyoxyethylene ( 5) Lauryl ether, polyoxyethylene (6) lauryl ether, polyoxyethylene (8) lauryl ether, polyoxyethylene (9) lauryl ether, polyoxyethylene (20) lauryl ether, polyoxyethylene (23) lauryl ether, Polyoxyethylene (30) lauryl ether; polyoxyethylene (10) cetyl ether, polyoxyethylene (20) cetyl ether; polyoxyethylene (6) stearyl ether, polyoxyethylene (20) Stearyl ether, polyoxyethylene (50) stearyl ether; polyoxyethylene (4) oleyl ether, polyoxyethylene (8) oleyl ether, polyoxyethylene (9) oleyl ether, polyoxyethylene (20) oleyl ether Polyoxyethylene (30) oleyl ether; polyoxyethylene (6) polyoxypropylene (1.5) lauryl mystil ether; polyoxyethylene (10) polyoxypropylene (1.5) lauryl mysyl ether; polyoxyethylene ( 14) polyoxypropylene (1.5) lauryl mysyl ether; polyoxyethylene (10) polyoxypropylene (1.5) lauryl mysyl ether. Of these, diethylene glycol butyl ether and diethylene glycol hexyl ether are preferable, and diethylene glycol hexyl ether is more preferable from the viewpoint of foam suppression.

From the viewpoint of further improving the polishing rate, the lower limit of the volume median diameter (D ₅₀ ) of the ceria particles contained in the polishing liquid composition of the present embodiment is preferably 30 nm or more, more preferably 40 nm or more, and still more preferably. Is 50 nm or more. From the viewpoint of dispersion stability, the upper limit is preferably 1000 nm or less, more preferably 500 nm or less, still more preferably 160 nm or less, and particularly preferably 140 nm or less. Therefore, the volume median diameter (D ₅₀ ) of the ceria particles is preferably 30 to 1000 nm, more preferably 40 to 500 nm, still more preferably _{50 to} 160 nm, and particularly preferably 50 to 140 nm.

Volume median diameter (D ₅₀ ) means the particle size at which the cumulative volume frequency calculated by volume fraction is 50% when calculated from the smaller particle size. It can be calculated as a volume-based median diameter measured by name LA-920 (manufactured by Horiba Seisakusho).

In addition, the average primary particle diameter of the ceria particles is preferably 5 nm or more, more preferably 10 nm or more, and further preferably 20 nm or more, from the viewpoint of further improving the polishing rate. Further, from the viewpoint of further improving the mirror state of the polished surface, the upper limit is preferably 100 nm or less, more preferably 50 nm or less, and further preferably 40 nm or less. Therefore, the average primary particle diameter of the ceria particles is preferably 5 to 100 nm, more preferably 10 to 50 nm, and still more preferably 20 to 40 nm. The average primary particle diameter (nm) means a particle diameter (true sphere conversion) calculated by the following formula from a specific surface area S (m ² / g) calculated by the BET (nitrogen adsorption) method.
Average primary particle diameter (nm) = 820 / S

  The ceria particles may be commercially available or may be prepared in-house. Examples of the method for preparing ceria particles include conventionally known methods such as a calcination method, a hydrothermal synthesis method, a salt / catalyst method, and a gas phase method (PSV method). Among them, the calcination method is preferable. More specifically, from the viewpoint of further improving the polishing rate, the ceria particles contained in the polishing composition of the present embodiment are obtained by firing a cerium compound such as carbonate, sulfate, nitrate, or oxalate. The obtained cerium oxide particles are preferable, and water-soluble is desirable. The form of the ceria particles before being mixed with other components is not particularly limited, and may be a powder form or a sol form.

From the viewpoint of dispersion stability, the polycarboxylic acid polymer dispersant contained in the polishing composition of the present embodiment is preferably at least one selected from the group consisting of the following polymers and salts thereof. In the polishing composition of this embodiment, only 1 type chosen from the group which consists of the following polymer and its salt may be contained, and 2 or more types may be contained.
(1) A homopolymer of unsaturated monocarboxylic acid such as acrylic acid or methacrylic acid,
(2) Maleic acid or homopolymer of unsaturated dicarboxylic acid such as fumaric acid and itaconic acid (3) Copolymer containing structural units derived from at least one of the unsaturated monocarboxylic acid and unsaturated dicarboxylic acid ( 4) Ammonium salt, lower alkyl ammonium salt (for example, tetramethylammonium salt, etc.) or water-soluble amine salt of the polymer of (1) to (3)

  Among these polycarboxylic acid polymer dispersants, an ammonium salt of polyacrylic acid is more preferable from the viewpoint of dispersion stability.

The weight average molecular weight of the polycarboxylic acid polymer dispersant is preferably in the range of 1,000 to 10,000, and more preferably in the range of 1,000 to 6,000. The weight average molecular weight is a value calculated based on a peak in a chromatogram obtained by applying a gel permeation chromatography (GPC) method under the following conditions.
<GPC conditions>
Column: G4000PWXL + G2500PWXL (both trade names, manufactured by Tosoh Corporation) Eluent: 0.2 M phosphate buffer / CH ₃ CN = 9/1 (volume ratio)
Flow rate: 1.0 mL / min
Column temperature: 40 ° C
Detector: RI detector Standard material: Polyacrylic acid equivalent

  Examples of the aqueous medium contained in the polishing liquid composition of the present embodiment include water, a mixed medium of water and a solvent, and the solvent includes a solvent that can be mixed with water (for example, alcohol such as ethanol). Is preferred. Among these, water is preferable as the aqueous medium, and ion-exchanged water is more preferable.

  From the viewpoint of improving the polishing rate, the lower limit of the content of ceria particles in the polishing composition of the present embodiment is preferably 0.1% by weight or more, more preferably 0.2% by weight or more, and still more preferably. Is 0.4% by weight or more, particularly preferably 0.5% by weight or more. From the viewpoint of improving dispersion stability, the upper limit is preferably 5% by weight or less, more preferably 4% by weight or less, and still more preferably 3% by weight or less. Therefore, the content of ceria particles is preferably 0.1 to 5% by weight, more preferably 0.2 to 5% by weight, still more preferably 0.4 to 4% by weight, and particularly preferably 0.5 to 3% by weight. %.

  The content of Component A can be appropriately determined according to the content of ceria particles, but is preferably 0.05 to 4% by weight, more preferably 0.1 to 3% by weight, and still more preferably 0.2 to 2% by weight. %.

  The content of the polyoxyalkylene alkyl ether is preferably 0.01 to 2% by weight, more preferably 0.01 to 1.5% by weight, and still more preferably 0.01 to 1% by weight.

  The content of the polycarboxylic acid-based polymer dispersant can be appropriately determined according to the content of the ceria particles, but is preferably 0.0005 to 0.5% by weight, more preferably 0.001 to 0.1% by weight. It is.

  The content of the aqueous medium is preferably 80 to 99.69959% by weight, more preferably 85 to 99% by weight from the viewpoint of improving the polishing rate and improving the dispersion stability.

  In addition, although the content rate of each component demonstrated above is a content rate at the time of use, the polishing liquid composition of this embodiment is preserve | saved and supplied in the state concentrated in the range which does not impair the stability. May be. In this case, it is preferable in that the manufacturing and transportation costs can be further reduced. In particular, when the polishing liquid composition contains DHEG that has a high ability to suppress aggregation of ceria particles, the content of ceria particles in the polishing liquid composition can be further increased. It is possible to supply. Such a concentrated solution may be used by appropriately diluting with the aforementioned aqueous solvent as necessary.

  In the case where the polishing liquid composition of the present embodiment is a concentrated liquid containing DHEG, the lower limit of the content of ceria particles is preferably 2% by weight or more from the viewpoint of further reducing production and transportation costs. Preferably it is 2.5 weight% or more, More preferably, it is 3 weight% or more. From the viewpoint of further improving the dispersion stability, the upper limit is preferably 15% by weight or less, more preferably 12% by weight or less, still more preferably 10% by weight or less, and particularly preferably 8% by weight or less. Therefore, the content of ceria particles is preferably 2 to 15% by weight, more preferably 2.5 to 12% by weight, still more preferably 3 to 10% by weight, and particularly preferably 3 to 8% by weight.

  When the polishing liquid composition of the present embodiment is a concentrated liquid containing DHEG, the content of DHEG can be appropriately determined according to the content of ceria particles, but is preferably 0.15 to 20% by weight, more preferably 0.3 to 15% by weight, more preferably 0.6 to 10% by weight.

  When the polishing composition of the present embodiment is a concentrated solution containing DHEG, the content of polyoxyalkylene alkyl ether is preferably 0.03 to 10% by weight, more preferably 0.03 to 7.5% by weight. More preferably, it is 0.03 to 5% by weight.

  When the polishing liquid composition of the present embodiment is a concentrated liquid containing DHEG, the content of the polycarboxylic acid polymer dispersant can be appropriately determined according to the content of the ceria particles. 0 weight% is preferable, More preferably, it is 0.003-0.3 weight%, More preferably, it is 0.005-0.5 weight%.

  When the polishing composition of the present embodiment is a concentrated solution containing DHEG, the content of the aqueous medium is preferably 60 to 97.599% by weight, more preferably, since the polishing rate and dispersion stability can be further improved. 70 to 96% by weight.

  The pH of the abrasive composition of the present embodiment is adjusted using a pH adjuster as necessary. Examples of the pH adjuster include basic compounds and acidic compounds. Examples of the basic compound include ammonia, potassium hydroxide, water-soluble organic amine, quaternary ammonium hydroxide and the like. Examples of the acidic compound include inorganic acids such as sulfuric acid, hydrochloric acid, nitric acid and phosphoric acid, and organic acids such as acetic acid, oxalic acid, succinic acid, glycolic acid, malic acid, citric acid and benzoic acid.

  The pH at 25 ° C. of the polishing composition of the present embodiment is not particularly limited, but is preferably 3 to 10, more preferably 4 to 8, more preferably 4.5 to 7 because the polishing rate can be further improved. . Here, the pH at 25 ° C. can be measured using a pH meter (Toa Denpa Kogyo Co., Ltd., HM-30G), and is a value one minute after the electrode is immersed in the cleaning composition.

  The polishing liquid composition of the present embodiment may further contain an optional component such as a preservative or an oxidizing agent as long as the effects of the present invention are not hindered. Preservatives include benzalkonium chloride, benzethonium chloride, 1,2-benzisothiazolin-3-one, (5-chloro-) 2-methyl-4-isothiazolin-3-one, hydrogen peroxide, or hypochlorite And acid salts. Examples of the oxidizing agent include peroxides such as permanganic acid or peroxo acid, chromic acid, nitric acid, and salts thereof.

  Next, a method for preparing the polishing composition of this embodiment will be described.

The method for preparing the polishing composition of the present embodiment is not limited in any way, for example, at least component A consisting of one or more selected from the group consisting of DHEG, aminopolycarboxylic acid and nonmetal salts thereof, and It can be prepared by mixing polyoxyalkylene alkyl ether, ceria particles, a polycarboxylic acid polymer dispersant, and an aqueous medium.

  The order of mixing these components is not particularly limited, and all the components may be mixed at the same time, or the ceria particles are dispersed in advance in an aqueous medium in which a polycarboxylic acid polymer dispersant is dissolved. Then, a mixture containing Component A, polyoxyalkylene alkyl ether, and aqueous medium may be mixed into the ceria slurry. The latter is preferable from the viewpoint of sufficiently preventing ceria particles from aggregating.

  From the viewpoint of improving the polishing rate, the lower limit of the mixing ratio of the ceria particles in the polishing liquid composition of the present embodiment is preferably 0.1% by weight or more, more preferably 0.2% by weight or more. Is 0.4% by weight or more, particularly preferably 0.5% by weight or more. From the viewpoint of improving dispersion stability, the upper limit is preferably 5% by weight or less, more preferably 4% by weight or less, and still more preferably 3% by weight or less. Therefore, the content of ceria particles is preferably 0.1 to 5% by weight, more preferably 0.2 to 5% by weight, still more preferably 0.4 to 4% by weight, and particularly preferably 0.5 to 3% by weight. %.

  The blending ratio of Component A can be appropriately determined according to the blending ratio of the ceria particles, but is preferably 0.05 to 4% by weight, more preferably 0.1 to 3% by weight, still more preferably 0.2 to 2% by weight. %.

  The blending ratio of the polyoxyalkylene alkyl ether is preferably 0.01 to 2% by weight, more preferably 0.01 to 1.5% by weight, and still more preferably 0.01 to 1% by weight.

  The blending ratio of the polycarboxylic acid polymer dispersant can be appropriately determined according to the content of the ceria particles, but is preferably 0.0005 to 0.5% by weight, more preferably 0.001 to 0.1% by weight. It is.

  The blending ratio of the aqueous medium is preferably 80 to 99.69959% by weight, more preferably 85 to 99% by weight, from the viewpoint of improving the polishing rate and improving the dispersion stability.

  When component A is dihydroxyethyl glycine, each component is 0.05 to 20% by weight of dihydroxyethyl glycine, 0.01 to 10% by weight of polyoxyalkylene alkyl ether, and ceria particles in the total amount of the polishing composition. It is preferable that it is 0.1 to 15 weight%.

  The ceria particles can be dispersed in the aqueous medium using, for example, a homomixer, a homogenizer, an ultrasonic disperser, a stirrer such as a wet ball mill, or the like. After the ceria particles are dispersed in the aqueous medium, when coarse particles formed by aggregation of the ceria particles are contained in the aqueous medium, the coarse particles are preferably removed by centrifugation, filter filtration, or the like.

  When adjusting the pH of the polishing composition using a pH adjuster, the constituents of the polishing composition except for the pH adjuster may be mixed at the same time, and then the pH may be adjusted using the pH adjuster. When the constituents of the polishing liquid composition excluding the pH adjusting agent are sequentially mixed, the pH adjusting agent may be mixed at any of the mixing stages to adjust the pH of the polishing liquid composition. .

  Next, a method for manufacturing the semiconductor device of this embodiment will be described.

The manufacturing method of the semiconductor substrate of this embodiment includes a step of forming a thin film on the semiconductor substrate, that is, a thin film forming step of forming a thin film on one main surface of the semiconductor substrate and a pattern on the surface of the semiconductor substrate. Patterning step, that is, a concave-convex surface forming step of forming a concave-convex pattern on the opposite surface of the thin semiconductor substrate, and a polishing step of polishing the concave-convex surface using the polishing composition of the present embodiment. Including. The thin film forming process is performed a plurality of times as necessary.

  As a thin film formed in a thin film formation process, conductor layers, such as an insulating layer, a metal layer, and a semiconductor layer, are mention | raise | lifted, for example. Examples of the material included in the insulating layer include silicon oxide, silicon nitride, and polysilicon.

  The thin film forming method may be appropriately selected according to the material constituting the thin film, and examples thereof include a CVD method, a PVD method, a coating method, and a plating method.

  Examples of the method for forming the uneven surface include conventionally known lithography methods. In the lithography method, photoresist application, exposure, development, etching, photoresist removal, and the like are performed in this order.

  For polishing the uneven surface, the polishing composition of the present embodiment is supplied to the uneven surface, for example, a polishing pad is brought into contact with the uneven surface, and a predetermined pressure (load) is applied to the uneven surface, and the semiconductor substrate and one of them This can be done by relatively moving at least one of a structure including a thin film having a concavo-convex surface with a principal surface of the surface and a polishing pad. The polishing treatment can be performed by a conventionally known polishing apparatus.

  The polishing composition may be used as it is, or may be used after being diluted if it is a concentrated solution. When diluting the concentrate, the dilution factor is not particularly limited, and may be appropriately determined according to the concentration of each component (the content of ceria particles, etc.) in the concentrate, the polishing conditions, and the like.

  As a specific example of the dilution rate, the lower limit is preferably 1.5 times or more, more preferably 2 times or more, still more preferably 3 times or more, particularly preferably 4 times or more, and the upper limit is 20 times or less. More preferably, it is 15 times or less, more preferably 10 times or less, and particularly preferably 8 times or less. Therefore, the dilution factor is preferably 1.5 to 20 times, more preferably 2 to 15 times, still more preferably 2 to 10 times, and particularly preferably 2 to 8 times.

  Examples of the material of the semiconductor substrate include elemental semiconductors such as Si or Ge, compound semiconductors such as GaAs, InP, or CdS, mixed crystal semiconductors such as InGaAs, HgCdTe, and the like.

The material or material of the thin film in which the polishing liquid composition of the present embodiment is more preferably used includes a metal such as aluminum, nickel, tungsten, copper, tantalum, or titanium; a semi-metal such as silicon; A glassy material such as glass, glassy carbon, or amorphous carbon; a ceramic material such as alumina, silicon dioxide, silicon nitride, tantalum nitride, or titanium nitride; a semiconductor device such as a resin such as a polyimide resin; A conventionally well-known thing is mention | raise | lifted as a material. Among these, the thin film preferably contains silicon because polishing with ceria particles works well, and more preferably contains at least one selected from the group consisting of silicon oxide, silicon nitride, and polysilicon. It is preferable that Examples of silicon oxide include quartz, glass, silicon dioxide, and tetraethoxysilane (TEOS). The thin film containing silicon oxide may be doped with elements such as phosphorus and boron. Specific examples of such a thin film include BPSG (Boro-Phospho-Silicate Glass) film and PSG (Phospho-Silicate Glass). ) Membrane and the like. Since these elementally doped silicon oxide films are harder to polish than silicon oxide films not elementally doped, additives added to promote polishing are included in the polishing composition. Need to be included more. However, when a conventional polishing composition containing a large amount of the above additives is used, there is a problem that ceria particles aggregate and settle. In an example of the polishing composition of this embodiment containing DHEG, the aggregation of ceria particles is sufficiently suppressed, and the dispersion stability is extremely high. Therefore, examples of the polishing composition include BPSG films, PSG films, and the like. Especially suitable for polishing.

  The manufacturing method of the semiconductor device of the present embodiment allows the convex portions to be polished quickly, and from the viewpoint of enabling the formation of a polished surface with higher flatness, when the entire surface of the concave and convex surfaces is formed from the same material. Useful. The step (H) between the convex and concave portions adjacent to each other (see FIG. 1A) is preferably 50 to 2000 nm, more preferably 100 to 1500 nm. The size of the unevenness, that is, “step (H)” (see FIG. 1A) means the height between the top of the convex portion and the bottom point of the concave portion, and the profile measuring device (trade name HRP-100, KLA Tencor). (Manufactured by company).

  The material of the polishing pad used in the polishing process is not particularly limited, and conventionally known materials can be used. Examples of the material of the polishing pad include organic polymer foams such as hard foamed polyurethane and non-foamed foams, among which hard foamed polyurethane is preferable.

From the viewpoint of further improving the polishing rate, the lower limit of the supply rate of the polishing composition is preferably 0.01 g / min or more, more preferably 0.1 g / min, per 1 cm ^{2 of the} semiconductor substrate to be polished. More than a minute. Further, from the viewpoint of cost reduction and ease of waste liquid treatment, the upper limit is preferably 10 g / min or less, more preferably 5 g / min or less per 1 cm ^{2 of the} surface to be polished, that is, the uneven surface. Therefore, the supply rate of the polishing liquid composition is preferably 0.01 to 10 g / min, more preferably 0, per 1 cm ^{2 of the} surface to be polished, that is, the uneven surface.
. 1-5 g / min.

  The lower limit of the polishing load set in the polishing apparatus is preferably 5 kPa or more, more preferably 10 kPa or more, from the viewpoint of further improving the polishing rate. From the viewpoint of further improving the mirror state of the polished surface, the upper limit is preferably 100 kPa or less, more preferably 70 kPa or less, and even more preferably 50 kPa or less. Therefore, the set polishing load is preferably 5 to 100 kPa, more preferably 10 to 70 kPa, and still more preferably 10 to 50 kPa.

  The number of rotations of the polishing pad is preferably 30 to 200 rpm, more preferably 45 to 150 rpm, and still more preferably 60 to 100 rpm.

  The polishing step can be used for any polishing in the manufacturing process of a semiconductor device. As specific examples, for example, (1) polishing performed in a step of forming an embedded isolation film, (2) polishing performed in a step of planarizing an interlayer insulating film, and (3) embedded metal wiring (for example, damascene wiring) Etc.) and (4) polishing performed in the step of forming the embedded capacitor. Especially, it is preferable that the polishing process performed in the manufacturing method of the semiconductor device of this embodiment is applied to (1) and (2).

  The manufacturing method of the semiconductor device of the present embodiment may include a cleaning process, a heat treatment process, an impurity diffusion process, and the like as necessary.

In the manufacturing method of the semiconductor device of this embodiment, since polishing using the polishing liquid composition of this embodiment is performed, it is possible to form a polished surface with excellent flatness. This can contribute to the manufacture of semiconductor devices. The manufacturing method of the semiconductor device of this embodiment includes an IC (Integrated Circuit) and an LSI (Large-Scale Integrate).
ion) and is particularly useful as a method for manufacturing memory ICs, logic ICs, and system LSIs.

Example 1
A polishing liquid composition was prepared as follows so as to have the composition shown in Table 1 below. Specifically, first, DHEG (trade name: Kirest Ga, manufactured by Kirest Co., Ltd.), HeDG (trade name: hexyl diglycol, chemical name: diethylene glycol monohexyl ether, manufactured by Nippon Emulsifier Co., Ltd.), ion-exchanged water, Were mixed. An aqueous dispersion containing ceria particles (volume median diameter 125 nm) and ammonium polyacrylate (weight average molecular weight 6000) is added to the obtained mixed liquid while stirring the mixed liquid, and a 10% aqueous ammonia solution is further added. A polishing composition was prepared by adjusting the pH to 6.2. The volume median diameter of the ceria particles was calculated as a volume-based median diameter measured with a laser diffraction / scattering particle size distribution meter (trade name LA-920, manufactured by Horiba, Ltd.).

(Comparative Examples 1-3)
As Comparative Examples 1 to 3, polishing liquid compositions having the compositions shown in Table 1 below were prepared in the same manner as in Example 1. For silica particles (Comparative Example 3), Semispace SS-25 (trade name, manufactured by Cabot) was used.

(Sample for evaluation)
As an evaluation sample, a commercially available wafer for CMP characteristic evaluation (trade name: STI MIT 864, diameter 200 mm) was prepared. This sample for evaluation will be described with reference to FIGS. 1A and 2A to 2C are partially enlarged sectional views of the evaluation sample, FIG. 1B is a top view of the evaluation sample, and FIG. 1C is a partially enlarged view of FIG. 1B. As shown in FIG. 1A, the sample for evaluation includes a silicon substrate and a silicon nitride film with a thickness of 150 nm (hereinafter referred to as “Si ₃ N ₄ film”) disposed thereon. The Si ₃ N ₄ film is formed by a CVD method. A groove having a depth of 500 nm (150 nm + 350 nm) is formed in the stacked body. On the Si ₃ N ₄ film, a silicon oxide film having a thickness of 600 nm (hereinafter referred to as “HDP film”) is disposed. The HDP film is formed by HDP-CVD (High Density Plasma Chemical Vapor Deposition). As shown in FIG. 1B, the plane of the HDP film is divided into 61 regions (20 mm × 20 mm), and each region is further divided into 25 small regions (4 mm × 4 mm). (FIG. 1C). In FIG. 1B, a black area (hereinafter referred to as “center”) and a hatched area (hereinafter referred to as “edge”) are areas where thickness was measured, as will be described later. 20, 90 and 10 of D20, D90 and D100 in FIG. 1C
0 indicates the ratio (convex surface density) of the total area of the convex portions visible when the small region is viewed in plan to the small region. Partial enlarged cross-sectional views of each small region are shown in FIGS. 2A, 2B, and 2C, respectively. As shown in these drawings, a linear projection / recess pattern having a convex portion width of 20 μm and a concave portion width of 80 μm is formed on D20 (FIG. 2A), and a convex portion width of 90 μm and a concave portion width of 10 μm is formed on D90 (FIG. 2B). A line uneven pattern is formed. Since D100 (FIG. 2C) consists entirely of convex portions, the concave / convex pattern is not formed.

(Polishing conditions)
Polishing tester: Single-side polishing machine (Part No .: LP-541, manufactured by Lapmaster SFT, surface plate diameter 540 mm)
Polishing pad: Part No. IC-1000 / Suba400 (made by Nitta Haas Co., Ltd.)
Surface plate rotation speed: 60 rpm
Head rotation speed: 62 rpm (Rotation direction is the same as the surface plate)
Polishing load: 30 kPa (setting value)
Polishing liquid supply amount: 200 mL / min (0.6 g / (cm ² · min))
Polishing time: 3 minutes

Using the polishing composition shown in Table 1, the sample for evaluation was polished under the above polishing conditions. About the sample for evaluation after polishing, the remaining film thickness at each of D20, D90 and D100 of center and edge was measured using an optical interference film thickness meter (trade name: VM-1000, manufactured by Dainippon Screen Mfg. Co., Ltd.). It was measured. The measured residual film thickness is of three types: the film thickness (t1) of the convex HDP film, the film thickness (t2) of the Si ₃ N ₄ film, and the film thickness (t3) of the HDP film of the concave part.

From the selected measurement results, the flatness was evaluated based on the criteria shown in Table 2 below. The evaluation results and evaluation are shown in Table 3 below. The unit of numerical values in Table 3 is “nm”, and the symbols (◯ and ×) are based on the judgment criteria in Table 2 below. “Step Height” in Tables 2 and 3 is the difference between the film thickness at the convex part and the film thickness at the concave part after polishing, and the film thickness (t1) of the HDP film at the convex part. Using the values of the thickness of the Si ₃ N ₄ film (t2) and the thickness of the HDP film in the recess (t3), it can be calculated from the following equation. The units of thickness in the following formula are all “nm”.
Step Height = {Si ₃ N ₄ film thickness (convex part) + HDP film thickness (convex part) +350} −HDP film thickness (recessed part)

  In general, the larger the convex surface density (the smaller the concave surface density), the thicker the remaining film in the convex portion, and the smaller the convex surface density (the higher the concave surface density), the more easily the concave portion is scraped and dishing phenomenon occurs. It is easy to happen. Therefore, the evaluation as to whether or not the polishing was sufficiently performed was performed based on the measurement results regarding D90 and D100 (no recesses), and the evaluation of the dishing suppression effect was performed based on the measurement results regarding D20.

As shown in Table 3, in the sample for evaluation polished using the polishing composition of Example 1, the film thickness (t1) of the HDP film at the convex portion and the film of the Si ₃ N ₄ film in all regions All of the thickness (t2), the thickness of the HDP film in the recess (t3), and the Step Height were applicable to the criterion (circle) shown in Table 2. Therefore, in the polishing using the polishing liquid composition of Example 1, the occurrence of dishing was suppressed, the polishing was sufficiently performed, and a polished surface with high flatness of the polished surface was obtained.

In the sample for evaluation polished using the polishing liquid composition of Comparative Example 1, the film thickness (t2) of the Si ₃ N ₄ film at the convex part of the center D20 and the film thickness (t3) of the HDP film at the concave part are It was found that the determination criterion x shown in Table 2 was satisfied, dishing occurred, and there was a problem with the flatness of the polished surface.

  In the sample for evaluation polished using the polishing liquid composition of Comparative Example 2, the D100 and D90 of the edge were not sufficiently polished although dishing occurred in the convex and concave portions of the center D20. It was found that there was a problem with the flatness of the polished surface.

  In the semiconductor substrate using the polishing liquid composition of Comparative Example 3, dishing occurred at the center and edge D20, and it was found that there was a problem in the flatness of the polished surface.

  Further, if the surface of the object to be polished is polished using the polishing composition of Example 1, even if the polishing time is extended, both in the center and the edge, the thickness variation is large in D20 where the convex surface density is small. There was no dishing. This is because the coating was formed on the surface to be polished by HeDG and the coating was formed on the surface of the ceria particles by DHEG, so that the polishing was hardly performed on the flat surface and the polishing rate was reduced. Conceivable.

(Examples 2 to 7)
A polishing composition was prepared so as to have the composition shown in Table 4 below. The adjustment method of the polishing liquid composition of Examples 2 to 7 was performed in the same manner as the adjustment method of the polishing liquid composition of Example 1. However, in the adjustment of the polishing liquid compositions of Examples 2 to 6, the following polyoxyalkylene alkyl ether was mixed with DHEG and ion-exchanged water in the same manner as HeDG in the polishing liquid composition of Example 1. And an aqueous dispersion containing ceria particles (volume median diameter 125 nm) and ammonium polyacrylate (weight average molecular weight 6000). The polishing composition of Example 7 was prepared in the same manner as the polishing composition of Example 1 except that EDTA · 2NH ₄ was used instead of DHEG.

BDG (trade name butyl diglycol, chemical name diethylene glycol mono n-butyl ether, manufactured by Nippon Emulsifier Co., Ltd.)
HeDG (trade name hexyl diglycol, chemical name diethylene glycol monohexyl ether, manufactured by Nippon Emulsifier Co., Ltd.)
EHDG (trade name: Niethylhexyl diglycol, chemical name: Diethylene glycol 2-ethylhexyl ether, manufactured by Nippon Emulsifier Co., Ltd.)
Emulgen 108 (chemical name: polyoxyethylene lauryl ether, manufactured by Kao Corporation)
Emulgen LS-110 (chemical name polyoxyethylene propylene higher alcohol ether, manufactured by Kao Corporation)
EDTA 2NH ₄ (chemical name ethylenediaminetetraacetic acid diammonium salt, manufactured by Wako Pure Chemical Industries, Ltd.)

Note that Emulgen LS-110 is C _12-14 —O— (EO) ₁₀ (PO) _1.5 —H, C ₁₂ —O— (EO) ₁₀ (PO) _1.5 —H, and C ₁₃ —O—. (EO) ₁₀ (PO) and _1.5 -H, a _{C 14 -O- (EO) 10 (} PO) mixture of _1.5 -H.

(Comparative Example 4)
As Comparative Example 4, a polishing liquid composition having the composition shown in Table 5 below was prepared in the same manner as in Example 2.

(Polishing conditions)
The conditions were the same as those in Example 1 and Comparative Examples 1 to 3 except that the platen rotation number, the head rotation number, and the polishing time were changed.
Surface plate rotation speed: 100 rpm
Head rotation speed: 110 rpm (Rotation direction is the same as the surface plate)

The end of polishing was determined using a torque measurement method. In this method, the change in the coefficient of friction between the surface to be polished and the polishing pad is detected from the change in the rotation axis torque of the wafer carrier or the surface plate. The friction coefficient change was detected from the motor current change. At the initial stage of polishing, only the HDP film comes into contact with the polishing pad, but at the end of polishing, the nitride film Si ₃ N ₄ is exposed and the friction coefficient changes, so that the current value also changes. When the nitride film is exposed in all of D20 to D100, the current value is saturated. The point of time when the saturation state was reached was set as the polishing end point (EP), and polishing was further performed for 30 seconds to complete the polishing.

As in the case of Example 1 and Comparative Examples 1 to 3, the HDP film thickness (t1) and Si ₃ N ₄ film thickness (t2) in the convex portion, and the HDP film thickness (t3) in the concave portion are set. Measurements were made and evaluated based on the criteria listed in Table 2. The results are shown in Table 6.

As shown in Table 6, in the samples for evaluation polished using the polishing liquid compositions of Examples 2 to 6, the film thickness (t1) of the HDP film at the convex portion, the Si ₃ N ₄ film in all regions All of the film thickness (t2), the film thickness (t3) of the HDP film in the concave portion, and the step height were all applicable to the judgment standard ◯ shown in Table 2. Therefore, in the polishing using the polishing liquid compositions of Examples 2 to 6, the occurrence of dishing was suppressed, the polishing was sufficiently performed, and a polishing surface with high flatness of the polishing surface was obtained.

  On the other hand, in the sample for evaluation polished using the polishing liquid composition of Comparative Example 4, the D100 and D90 of the edge were not sufficiently polished although the dishing occurred at the convex portion of the center D20. It was found that there was a problem with surface flatness.

  From the above results, the component A consisting of one or more selected from the group consisting of dihydroxyethyl glycine, aminopolycarboxylic acid, and non-metal salt of aminopolycarboxylic acid, polyoxyalkylene alkyl ether, ceria particles, It was confirmed that a polished surface with excellent flatness could be formed by polishing the uneven surface using a polishing composition containing a polycarboxylic acid polymer dispersant and an aqueous medium.

  If polishing is performed using the polishing composition of the present invention, a polished surface with excellent flatness can be formed. Therefore, the polishing liquid composition of the present invention is useful as a polishing liquid composition used in various semiconductor device manufacturing processes, and is particularly useful for the manufacture of ICs and LSIs.

1A is a partially enlarged cross-sectional view of an evaluation sample used in an example of the present invention, FIG. 1B is a plan view of the evaluation sample, and FIG. 1C is an enlarged view of a part of FIG. 1B. 2A to 2C are partially enlarged sectional views of samples for evaluation used in the examples of the present invention.

Claims (11)

And dihydroxyethyl glycinate down,
A polyoxyalkylene alkyl ether;
Ceria particles,
A polycarboxylic acid polymer dispersant;
A polishing composition comprising an aqueous medium. And dihydroxyethyl glycinate down,
A polyoxyalkylene alkyl ether;
Ceria particles,
A polycarboxylic acid polymer dispersant;
A polishing composition obtained by mixing an aqueous medium. The polishing composition according to claim 1 or 2, wherein the polyoxyalkylene alkyl ether is represented by the following (formula 1).
(Formula 1) R ¹ —O— (AO) _n —H
In the above (Formula 1), AO is an oxyalkylene group having 2 to 4 carbon atoms, AO may be the same or different, and n is an average number of moles added and is a number from 1 to 50. R ¹ is an alkyl group having 4 to 24 carbon atoms or an alkenyl group having 4 to 24 carbon atoms. In the polishing composition total amount, the dihydroxyethylglycine 0.05 to 20 wt%, the polyoxyalkylene alkyl ether is from 0.01 to 10 wt%, claim 1 ceria particles is 0.1 to 15 wt% The polishing liquid composition as described in any one of -3 .   The polishing liquid composition according to any one of claims 1 to 4, wherein the polycarboxylic acid polymer dispersant is a polyacrylic acid ammonium salt.   The polishing liquid composition according to any one of claims 1 to 5, which is used for polishing a thin film having a concavo-convex surface with a step of 50 to 2000 nm between adjacent convex portions and concave portions. Forming a thin film having an uneven surface on one main surface side of the semiconductor substrate ;
A manufacturing method of a semiconductor device including a polishing process of polishing the uneven surface using the polishing liquid composition according to any one of claims 1 to 6. The method of manufacturing a semiconductor device according to claim 7, wherein the thin film contains silicon. The uneven surface has a plurality of concave portions and a plurality of convex portions,
The method of manufacturing a semiconductor device according to claim 7 or 8, wherein the size of the unevenness, that is, a step between adjacent convex portions and concave portions is 50 to 2000 nm.   In the said grinding | polishing process, the said thin film is grind | polished using the grinding | polishing apparatus provided with the polishing pad, The grinding | polishing load set in the said grinding | polishing apparatus is 5-100 kPa. A method for manufacturing a semiconductor device. In the polishing step, the polishing composition, a semiconductor substrate to be polished, that is, according to any one of the uneven surface 1cm claim 7-10 supplies at ² per 0.01 to 10 g / min A method for manufacturing a semiconductor device.

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