JP2013251339A - Erosion-preventing agent for chemical mechanical polishing, slurry for chemical mechanical polishing, and chemical mechanical polishing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an erosion-preventing agent for chemical mechanical polishing, allowing effective prevention of erosion and dishing and also suppression of polishing amount variation due to different wafer patterns.SOLUTION: An erosion-preventing agent for chemical mechanical polishing contains: a compound (a) having four or more hydroxy groups and no amino group; a compound (b) having four or more hydroxy groups and one amino group; and a compound (c) having four or more amino groups.

Description

  The present invention relates to an anti-erosion agent for chemical mechanical polishing, a slurry for chemical mechanical polishing, and a chemical mechanical polishing method suitable for manufacturing semiconductor devices. Here, the “erosion inhibitor for chemical mechanical polishing” means an additive added to the slurry for chemical mechanical polishing in order to prevent a phenomenon called “erosion” in which both the stop film and the insulating film are removed. .

  The chemical mechanical polishing erosion inhibitor and chemical mechanical polishing slurry of the present invention are preferably used in a semiconductor element separation step, planarization of an interlayer insulating film, formation of plugs and embedded metal wiring, and more preferably in a semiconductor element separation step. used.

  High performance of a semiconductor circuit has been achieved by increasing the density by miniaturizing transistors, resistors, wirings, etc. constituting the circuit, and at the same time by increasing the response speed. In addition, by stacking wiring, higher density and higher integration became possible. As technologies in semiconductor manufacturing that enable these, there are STI (Shallow Trench Isolation), interlayer insulating film planarization, damascene process, and metal plug. STI is transistor element isolation, damascene is a metal wiring embedding technique, and metal plug is a metal three-dimensional wiring having a structure penetrating an interlayer insulating film. An indispensable technique for each of these steps is CMP (Chemical Mechanical Polishing), which is always used in each step of STI formation, interlayer insulating film planarization, damascene process, and metal plug embedding. ing. These fine patterns are formed by transferring a resist mask formed by a photolithography process. However, as the miniaturization progresses, the depth of focus of the projection lens used for lithography becomes shallower, and the unevenness of the wafer is within that range. Since it must be accommodated, the required flatness is increased. By flattening the processed surface by CMP, a flat surface at the nano-order and atomic level can be obtained, and high performance can be achieved by three-dimensional wiring, that is, lamination.

  In the STI formation step, after forming a groove to be an element isolation region and forming a polishing stop film in a region other than the groove, an insulating film for element isolation is formed inside the groove and on the polishing stop film. Next, the excess insulating film is polished and removed by CMP until the polishing stop film is exposed and planarized. In general, silicon nitride is used as the stop film, and silicon oxide is often used as the insulating film.

  In order to achieve high planarization and device protection, it is necessary that both the polishing rate of the stop film and the insulating film decrease when the stop film is exposed. In order to reliably expose the stop film on the entire surface of the wafer, in a region where the polishing rate on the wafer is high, polishing is performed for a relatively long time after the stop film is exposed. For this reason, when the polishing rate of the stop film is high, a phenomenon called “erosion” in which the stop film is excessively removed together with the insulating film occurs, and the insulating film for element isolation becomes thin. On the other hand, if the polishing rate of the insulating film is high after the exposure of the stop film, a phenomenon called “dishing” occurs in which the insulating film in the pattern recesses is excessively removed, and the insulating film for element isolation becomes thin again. End up.

  Erosion and dishing will be further described with reference to FIGS. FIG. 1 is a schematic cross-sectional view of a pattern wafer before polishing. An insulating film 2 (such as silicon oxide), a stop film 3 (such as silicon nitride), and an insulating film 4 (such as silicon oxide) are formed on the pattern wafer 1. Has been. FIG. 2 is a schematic cross-sectional view of a patterned wafer after polishing in which erosion and dishing have occurred. In the pattern wafer shown in FIG. 2, erosion in which the stop film 3 is excessively removed together with the insulating film 4 and dishing in which the insulating film in the pattern recess is excessively removed occur (D1: initial film thickness of the stop film, D2). : Erosion amount, D3: dishing amount). On the other hand, FIG. 3 is a schematic cross-sectional view of a patterned wafer after polishing in which erosion and dishing are suppressed. In addition, the dimension of each part in a figure was set in order to make an understanding easy, and the dimension ratio between each part does not necessarily correspond with an actual thing.

  Currently, a slurry containing a combination of ceria (cerium oxide) abrasive grains and an anionic polymer is mainly used for STI formation (for example, Patent Documents 1 and 2). Slurries containing ceria abrasive grains have excellent flattening ability, but are expensive and are subject to change over time due to poor dispersion stability of the abrasive grains, and also tend to cause polishing scratches on the film to be polished. There is.

  In order to solve the above-mentioned problem of the slurry containing ceria abrasive grains, a slurry containing a combination of silica abrasive grains and various water-soluble compounds has been proposed (for example, Patent Documents 3 to 9). However, all of Patent Documents 3 to 9 measure the polishing rates of the silicon oxide film and the silicon nitride film separately using a blanket wafer having no pattern. As a result of verification by the present inventors, even when a slurry showing a high polishing rate ratio (ratio of the polishing rate of the silicon oxide film to the polishing rate of the silicon nitride film) in a blanket wafer having no pattern is used, an actual semiconductor is used. It has been found that a wafer having a concavo-convex pattern made of a silicon nitride film and a silicon oxide film similar to those used in the device has an insufficient polishing suppression effect for the silicon nitride film. The cause of this is that, compared with the blanket wafer, a substantially higher pressure is applied to the convex silicon nitride film in the pattern wafer, or the water-soluble compound adsorbed to the convex silicon nitride film is desorbed to form the concave portion. It seems that there is a phenomenon of running away.

Moreover, the slurry containing the combination of a silica abrasive grain and a polyethyleneimine is examined (for example, patent documents 10-12). In Table 2 of Patent Document 10, when polyethyleneimine (“PEI” described in Patent Document 10) is added to a slurry containing silica abrasive grains, a silicon nitride film (Patent Document 10) increases as the amount of polyethyleneimine increases. It is shown that the ratio of the polishing rate of the silicon oxide film (“PE-TEOS” described in Patent Document 10) to the polishing rate of “Si ₃ N” described in 1) decreases. From this, it is considered that a slurry containing only a combination of silica abrasive grains and polyethyleneimine is not suitable as a chemical mechanical polishing slurry for forming STI. Patent Documents 11 and 12 are intended to prevent surface roughness (haze) on the polished wafer surface, and are intended to reduce the amount of polishing and residual steps during overpolishing in the STI formation process. It is not a thing.

Japanese Patent No. 3672493 Japanese Patent No. 3649279 JP 2000-144111 A JP 2002-114967 A JP 2002-118082 A JP 2002-201462 A Japanese Patent Laid-Open No. 2002-261053 JP 2005-159351 A JP 2008-187191 A JP 2002-305167 A JP 2006-352042 A JP 2007-19093 A

  An object of the present invention is to provide an erosion inhibitor for chemical mechanical polishing that can effectively prevent erosion and dishing and suppress variation in polishing amount due to different wafer patterns. The “characteristic capable of suppressing variation in polishing amount due to different wafer patterns” possessed by the chemical mechanical polishing erosion inhibitor and the chemical mechanical polishing slurry may be abbreviated as “pattern uniformity” below.

  As a result of extensive studies by the present inventors, the compound (a) having 4 or more hydroxyl groups and no amino group (hereinafter sometimes abbreviated as “compound (a)”), 4 or more Compound (b) having a hydroxyl group and one amino group (hereinafter sometimes referred to as “compound (b)”), and compound (c) having four or more amino groups (hereinafter referred to as “compound (c)”) And the present invention described below was completed.

[1] Compound (a) having 4 or more hydroxyl groups and no amino group, compound (b) having 4 or more hydroxyl groups and 1 amino group, and compound having 4 or more amino groups An anti-erosion agent for chemical mechanical polishing containing (c).
[2] The erosion inhibitor for chemical mechanical polishing according to [1], wherein the compound (a) has a molecular weight of 100 to 100,000 and a hydroxyl group content of 5 to 40 mmol / g.
[3] The erosion inhibitor for chemical mechanical polishing according to [1] or [2], wherein the compound (a) has a skeleton derived from a monosaccharide.
[4] The chemical machine according to any one of the above [1] to [3], wherein the compound (a) is at least one selected from the group consisting of a compound to which 2 to 50 monosaccharides are bonded and a derivative thereof. Anti-erosion agent for polishing.
[5] The erosion inhibitor for chemical mechanical polishing according to any one of [1] to [4] above, wherein the compound (b) has a molecular weight of 150 to 1,000.
[6] The erosion inhibitor for chemical mechanical polishing according to any one of the above [1] to [5], wherein the compound (b) is at least one selected from glucamine and derivatives thereof.
[7] For chemical mechanical polishing according to any one of the above [1] to [6], wherein the compound (c) has a molecular weight of 200 to 100,000 and an amino group content of 3 to 30 mmol / g. Erosion inhibitor.
[8] The compound (c) is a polyalkyleneimine (c1); allylamine, N-alkylallylamine, N, N-dialkylallylamine, diallylamine, N-alkyldiallylamine, vinylamine, vinylpyridine, and (meth) acrylic acid-N. , N-dialkylaminoethyl, at least one monomer selected from the group consisting of (wherein the alkylene represents a divalent alkylene group having 1 to 6 carbon atoms, and the alkyl is a monovalent alkylene group having 1 to 4 carbon atoms. Represents an alkyl group.) Polymer (c2) obtained by polymerizing 25 to 100% by mass of another monomer having an unsaturated double bond of 75 to 0% by mass; and a derivative thereof. The erosion inhibitor for chemical mechanical polishing according to any one of the above [1] to [7], which is at least one selected from the group.
[9] A chemical mechanical polishing slurry containing the chemical mechanical polishing erosion inhibitor according to any one of [1] to [8], abrasive grains (d), and water.
[10] The slurry for chemical mechanical polishing according to [9], wherein the abrasive grains (d) are silica.
[11] In slurry for chemical mechanical polishing,
The concentration of the compound (a) is 0.01 to 10% by mass,
The concentration of the compound (b) is 0.001 to 10% by mass,
The concentration of the compound (c) is 0.001 to 5% by mass,
The concentration of the abrasive grains (d) is 0.2 to 30% by mass,
The slurry for chemical mechanical polishing according to [9] or [10] above.
[12] The slurry for chemical mechanical polishing according to any one of [9] to [11], wherein the pH is 9 to 13.
[13] A chemical mechanical polishing method for polishing an insulating film using the chemical mechanical polishing slurry according to any one of [9] to [12].
[14] The chemical mechanical polishing method of [13], wherein the silicon oxide film on the silicon nitride film is polished.

  By using the chemical mechanical polishing slurry containing the chemical mechanical polishing erosion inhibitor of the present invention, erosion and dishing can be effectively suppressed, and variation in polishing amount can be suppressed for different wafer patterns.

It is a schematic cross section of a pattern wafer before polishing. It is a schematic cross section of the patterned wafer after polishing in which erosion and dishing have occurred. It is a schematic cross section of the patterned wafer after polishing in which erosion and dishing are suppressed.

[Erosion inhibitor for chemical mechanical polishing]
The chemical mechanical polishing erosion inhibitor of the present invention contains the compound (a), the compound (b) and the compound (c) as essential components. As for a compound (a), a compound (b), and a compound (c), all may use only 1 type and may use 2 or more types together. The erosion inhibitor for chemical mechanical polishing of the present invention may further contain an optional component (for example, water) other than the compound (a), the compound (b) and the compound (c).

  When the chemical mechanical polishing erosion inhibitor contains an optional component other than water, the content of the optional component other than water is preferably based on the total amount of the compound (a), the compound (b) and the compound (c). It is 70 mass% or less, More preferably, it is 50 mass% or less, More preferably, it is 30 mass% or less.

  The mass ratio of the compound (a) to the compound (b) in the chemical mechanical polishing erosion inhibitor (that is, compound (a) / compound (b)) is preferably 0.1 to 100, more preferably 0.8. It is 3-70, More preferably, it is 0.5-40. The mass ratio of the compound (a) to the compound (c) in the chemical mechanical polishing erosion inhibitor (ie, compound (a) / compound (c)) is preferably 1 to 1000, more preferably 3 to 700, More preferably, it is 5-400. The mass ratio of the compound (b) to the compound (c) in the chemical mechanical polishing erosion inhibitor (ie, the compound (b) / compound (c)) is preferably 0.1 to 100, more preferably 0.8. It is 3-70, More preferably, it is 0.5-40.

When only one component of the compound (a), the compound (b) and the compound (c) is used, or when only the compound (a) and the compound (b) is not used, the pattern wafer is used. When polishing, the polishing suppression effect of the stop film is low, and erosion occurs in which the stop film and the insulating film adjacent to the stop film are excessively polished. Further, when the compound (b) is not used only with the compound (a) and the compound (c), or when the compound (a) is not used only with the compound (b) and the compound (c), polishing of the stop film is suppressed. Although the effect is relatively high, there is a large difference in polishing speed depending on the shape and size of the wafer pattern, and it is difficult to uniformly polish various pattern wafers.
Hereinafter, the compound (a), the compound (b) and the compound (c) will be described in detail.

[Compound (a)]
The number of hydroxyl groups in the compound (a) is preferably 5 or more, more preferably 6 or more, and even more preferably 7 or more. On the other hand, the upper limit of the number of hydroxyl groups of the compound (a) is not particularly limited, but from the viewpoint of easy availability of the compound (a), the number of hydroxyl groups is preferably 4000 or less, more preferably 1000 or less, More preferably, it is 300 or less.

The hydroxyl group content of the compound (a) is preferably 5 to 40 mmol / g, more preferably 10 to 35 mmol / g, and further preferably 15 to 30 mmol / g. When the hydroxyl group content of the compound (a) is within the above range, the compound (a) has both good water solubility and adsorptivity to the film to be polished, and polishing of the insulating film in the stop film and the pattern recess is further suppressed. .
In addition, the hydroxyl group content of a compound (a) can be measured by the method based on JISK0070. When the chemical structure of the compound (a) is known, the hydroxyl group content of the compound (a) can also be calculated from the molecular weight and the number of hydroxyl groups.

The molecular weight of the compound (a) is preferably 100 to 100,000, more preferably 150 to 50,000, and further preferably 200 to 10,000. When the molecular weight of the compound (a) is less than 100, the adsorptivity of the compound (a) to the film to be polished is weak, and the polishing suppressing effect of the stop film and the insulating film of the pattern recess tends to be low. On the other hand, when the molecular weight exceeds 100,000, the viscosity of the polishing slurry increases, the polishing rate and the polishing uniformity decrease, and erosion and dishing cannot be effectively prevented in many cases.
In addition, when the compound (a) is a polymer and is substantially a mixture of compounds having various molecular weights, the “molecular weight of the compound (a)” refers to the “weight average molecular weight of the compound (a)”. The weight average molecular weight of the compound (a) can be measured by size exclusion chromatography (SEC) using polyethylene glycol or polyethylene oxide as a calibration standard sample.

  Examples of the compound (a) include monosaccharides such as arabinose, xylose, fructose, sorbose, tagatose, glucose, mannose, galactose, fucose and rhamnose; sucrose, lactose, maltose, isomaltose, trehalose, gentiobiose, xylobiose, isomalt Disaccharides such as loose; trisaccharides such as raffinose, maltotriose, isomaltotriose, kestose, gentiotriose, xylotriose; tetrasaccharides such as nystose, isomalttetraose, gentiotetraose, xylotetraose ; Pentasaccharides such as fructofuranosyl nystose and pannose; α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, δ-cyclodextrin, methyl-β-cyclodextri; Cyclodextrins such as hydroxyethyl-β-cyclodextrin, hydroxypropyl-β-cyclodextrin; cyclodextran in which 5 to 20 glucoses are linked in a cyclic manner; dextrin, dextran, pullulan, inulin, hydroxyethylcellulose, hydroxypropyl Polysaccharides such as cellulose; sugar alcohols such as erythritol, xylitol, sorbitol, mannitol, inositol, lactitol, maltitol, and isomaltitol; polyvinyl alcohol, poly (2-hydroxyethyl (meth) acrylate), poly ((meta ) Hydroxyl group-containing polymers such as 2-hydroxypropyl acrylate); and derivatives thereof, and one or more of these may be used. In the present invention, “(meth) acrylic acid” means “methacrylic acid or acrylic acid”.

  Among compounds (a), a compound having a skeleton derived from a monosaccharide has a particularly high polishing-suppressing effect on a stop film when a pattern wafer is polished, and is extremely high when used in combination with compound (b) and compound (c). It is preferable because it exhibits a synergistic effect. Compound (a) is a compound in which 2 to 50 monosaccharides are bound (for example, disaccharide, trisaccharide, tetrasaccharide, pentasaccharide, cyclodextrins, cyclodextran, low molecular weight dextran, etc.) and derivatives thereof (for example, monosaccharides). More preferably, it is at least one selected from the group consisting of sugar alcohols obtained by reducing a part of the skeleton of a compound having 2 to 50 saccharides bonded thereto by hydrogenation. Compound (a) is more preferably at least one selected from the group consisting of disaccharides, trisaccharides, tetrasaccharides, sugar alcohols obtained by reducing disaccharides, and cyclodextrins, and sucrose, raffinose Particularly preferred are kestose, nystose, lactitol, maltitol or α-cyclodextrin.

[Compound (b)]
The number of hydroxyl groups in the compound (b) is preferably 4 to 100, more preferably 4 to 40, and still more preferably 5 to 20.

The hydroxyl group content of the compound (b) is preferably 10 to 40 mmol / g, more preferably 12 to 35 mmol / g, and further preferably 15 to 30 mmol / g. When the hydroxyl group content of the compound (b) is within the above range, the compound (b) has both good water solubility and adsorptivity to the film to be polished, and makes various patterns more uniform regardless of the shape and size of the pattern. Can be polished.
The hydroxyl group content of the compound (b) can be determined as follows by a method based on JIS K0070 and JIS K7237. First, the hydroxyl group content is measured in accordance with JIS K0070. The numerical value obtained by this is actually the total amount of hydroxyl group, primary amino group and secondary amino group. For this reason, the true hydroxyl group content is obtained by determining the total amount of primary amino groups and secondary amino groups by the method according to JIS K7237 and subtracting it from the value of “apparent hydroxyl group content” obtained according to JIS K0070. Is obtained. In order to determine the total amount of primary amino groups and secondary amino groups by a method in accordance with JIS K7237, the sample is reacted with an excess amount of acetic anhydride in advance from the value of the total amino group content determined by the usual method. The value of the tertiary amino group content obtained after converting the primary amino group and the secondary amino group into an amide group is reduced. In addition, when the chemical structure of the compound (b) is known, the hydroxyl group content of the compound (b) can be calculated from the molecular weight and the number of hydroxyl groups.

The molecular weight of the compound (b) is preferably 150 to 1,000, more preferably 160 to 700, and further preferably 170 to 500. When the molecular weight of the compound (b) is less than 150, the adsorptivity of the compound (b) to the film to be polished is weak, and the polishing suppressing effect of the stop film and the insulating film of the pattern recess tends to be low. On the other hand, when the molecular weight exceeds 1,000, the adsorptivity of the compound (b) to the film to be polished is easily changed depending on the shape and size of the pattern, and it is difficult to uniformly polish various patterns.
In addition, when the compound (b) is a polymer and is substantially a mixture of compounds having various molecular weights, the “molecular weight of the compound (b)” refers to the “number average molecular weight of the compound (b)”. The number average molecular weight of the compound (b) can be measured by a boiling point increase method.

  Examples of the compound (b) include glucamine, hexosamine, and derivatives thereof. These may use only 1 type and may use 2 or more types together. As the glucamine, hexosamine and derivatives thereof, any of D-form, L-form, D-form and a mixture of L-form can be used, but those D-forms are preferred from the viewpoint of availability. Examples of the glucamine derivative include N-methylglucamine, N-ethylglucamine, N-butylglucamine, N-octylglucamine and the like. Examples of hexosamine include glucosamine, galactosamine, mannosamine and the like. From the viewpoint of the availability of the compound (b) and the polishing properties of the erosion inhibitor for chemical mechanical polishing, the compound (b) is at least selected from the group consisting of glucamine, N-methylglucamine and N-ethylglucamine. It is preferable to use one.

[Compound (c)]
The amino group content of the compound (c) is preferably 3 to 30 mmol / g, more preferably 5 to 25 mmol / g, and even more preferably 7 to 20 mmol / g. When the amino group content is in the above range, the compound (c) has both good water solubility and adsorptivity to the film to be polished, and the polishing of the insulating film in the stop film and the pattern recess is further suppressed.
The amino group content of the compound (c) can be measured by a method based on JIS K7237. Moreover, when the chemical structure of compound (c) is known, the amino group content of compound (c) can also be calculated from the molecular weight and the number of amino groups.

  The number of amino groups of the compound (c) is preferably 4 to 400, more preferably 4 to 200, and still more preferably 4 to 100. Moreover, the compound (c) may have a hydroxyl group.

The molecular weight of the compound (c) is preferably 200 to 100,000, more preferably 250 to 30,000, further preferably 300 to 10,000, and 400 to 5,000. It is particularly preferred. When the molecular weight of the compound (c) is less than 200, the adsorptivity of the compound (c) to the film to be polished is weak, and the polishing suppressing effect of the stop film and the insulating film of the pattern recess tends to be low. On the other hand, when the molecular weight of the compound (c) exceeds 100,000, the viscosity of the polishing slurry becomes high, the polishing rate and the polishing uniformity are likely to decrease, and the abrasive grains may easily aggregate.
In addition, when the compound (c) is a polymer and is substantially a mixture of compounds having various molecular weights, the “molecular weight of the compound (c)” refers to “the number average molecular weight of the compound (c)”. The number average molecular weight of the compound (c) can be measured by a boiling point increase method.

  Examples of the compound (c) include polyalkyleneimine (c1) (for example, polyethyleneimine, polypropyleneimine, polybutyleneimine, N-methylpolyethyleneimine, etc.); allylamine, N-alkylallylamine (for example, N-methylallylamine, N- Ethyl allylamine, N-propylallylamine, etc.), N, N-dialkylallylamine (eg, N, N-dimethylallylamine, N, N-diethylallylamine, N-methyl-N-ethylallylamine, etc.), N-alkyldiallylamine (eg, N -Methyldiallylamine, N-ethyldiallylamine, etc.), vinylamine, vinylpyridine and (meth) acrylic acid-N, N-dialkylaminoethyl (eg (meth) acrylic acid-N, N-dimethylaminoethyl, (meth) a) At least one monomer selected from the group consisting of lauric acid-N, N-diethylaminoethyl and the like and another monomer having an unsaturated double bond (for example, methyl (meth) acrylate) , Ethyl (meth) acrylate, (meth) acrylamide, N, N-dimethyl (meth) acrylamide, styrene, methyl vinyl ether, vinyl pyrrolidone, ethylene, propylene, butadiene, etc.) Polymer (c2); polylysine, polyornithine, water-soluble chitosan; amine having a piperazine skeleton (for example, 1,4-bis (3-aminopropyl) piperazine, 1,4-bis [3- (cyclohexylmethylamino) propyl Piperazine, 1,4-bis [2- (2-aminoethylamino) ethyl] piperazine, 1 [3- (3-aminopropylamino) propyl] piperazine, 1- [4- (4-aminobutylamino) butyl] piperazine, etc.); and their derivatives, and one or more of these are used. be able to. In the present invention, “(meth) acrylamide” means “methacrylamide or acrylamide”.

  Compound (c) is preferably polyalkyleneimine (c1); allylamine, N-alkylallylamine, N, N-dialkylallylamine, diallylamine, N-alkyldiallylamine and (meth) acrylic acid-N, N-dialkylaminoethyl At least one monomer selected from the group consisting of 50 to 100% by mass (wherein the alkylene represents an alkylene group having 1 to 6 carbon atoms, and the alkyl represents an alkyl group having 1 to 4 carbon atoms); , A polymer (c2) obtained by polymerizing 50 to 0% by mass of another monomer having an unsaturated double bond; and at least one selected from the group consisting of derivatives thereof. Such a compound (c) has a particularly high effect of suppressing the polishing of the stop film when the patterned wafer is polished, and exhibits a very high synergistic effect when used in combination with the compound (a) and the compound (b).

  The compound (c) is more preferably polyethyleneimine, polypropyleneimine, N-methylpolyethyleneimine, polyallylamine, poly (N-methylallylamine), poly (N, N-dimethylallylamine), poly (diallylamine), poly (N -Methyldiallylamine), (allylamine / N, N-dimethylallylamine) copolymer, (allylamine / N-methyldiallylamine) copolymer, (N, N-dimethylallylamine / N-methyldiallylamine) copolymer and poly ( It is at least one selected from the group consisting of (meth) acrylic acid-N, N-dialkylaminoethyl. The compound (c) is more preferably polyethyleneimine, N-methylpolyethylenimine, polyallylamine, poly (N-methylallylamine), poly (N, N-dimethylallylamine), poly (diallylamine), poly (N-methyldiallylamine) ), (Allylamine / N, N-dimethylallylamine) copolymer, (allylamine / N-methyldiallylamine) copolymer and (N, N-dimethylallylamine / N-methyldiallylamine) copolymer. At least one.

  When the compound (c) having at least one secondary amino group and / or at least one tertiary amino group is used, the stability of the slurry when blended with abrasive grains tends to be improved. Therefore, the compound (c) is more preferably polyethyleneimine, N-methylpolyethylenimine, poly (N-methylallylamine), poly (N, N-dimethylallylamine), poly (diallylamine), poly (N-methyldiallylamine). At least selected from the group consisting of: (allylamine / N, N-dimethylallylamine) copolymer, (allylamine / N-methyldiallylamine) copolymer and (N, N-dimethylallylamine / N-methyldiallylamine) copolymer One.

[Slurry for chemical mechanical polishing]
The chemical mechanical polishing slurry of the present invention comprises the chemical mechanical polishing erosion inhibitor (ie, compound (a), compound (b), compound (c)), abrasive grains (d), and water as essential components. contains.

Abrasive grains generally used for chemical mechanical polishing can be used as the abrasive grains (d) in the chemical mechanical polishing slurry of the present invention.
Examples of the abrasive grains (d) include silica, alumina, zirconia, titania, ceria, germanium oxide, manganese oxide, zinc oxide, magnesium oxide, diamond, silicon carbide and the like. Among these, silica is preferable because it is excellent in polishing rate and abrasive dispersion stability and exhibits the erosion preventing effect of the present invention.

The average particle size of the abrasive grains (d) is preferably 5 to 500 nm, more preferably 10 to 400 nm, and more preferably 20 to 300 nm from the viewpoint that the polishing rate is excellent and polishing scratches on the film to be polished are reduced. More preferably.
In addition, the measurement of an average particle diameter can be calculated | required by analyzing by a cumulant method using the particle size measuring apparatus "ELSZ-2" by Otsuka Electronics Co., Ltd.

  The concentration of the compound (a) in the slurry for chemical mechanical polishing of the present invention is preferably 0.01 to 10% by mass because both the polishing rate and the erosion suppressing effect are excellent, and 0.05 to 8% by mass. Is more preferable, 0.1 to 6% by mass is further preferable, and 0.5 to 5% by mass is particularly preferable.

  Since the concentration of the compound (b) in the slurry for chemical mechanical polishing of the present invention is 0.001 to 10% by mass, various patterns can be polished more uniformly regardless of the shape and size of the pattern. Preferably, it is 0.01-8 mass%, More preferably, it is 0.05-6 mass%, It is especially preferable that it is 0.1-4 mass%.

  The concentration of the compound (c) in the chemical mechanical polishing slurry of the present invention is preferably 0.001 to 5% by mass because both the polishing rate and the erosion suppressing effect are excellent, and is 0.005 to 2% by mass. Is more preferable, 0.01 to 1% by mass is further preferable, and 0.02 to 0.5% by mass is particularly preferable.

  The concentration of the abrasive grains (d) in the chemical mechanical polishing slurry of the present invention is preferably 0.2 to 30% by mass because it is excellent in polishing rate and abrasive dispersion stability, and is 1 to 25% by mass. More preferably, it is more preferably 3 to 20% by mass.

  The pH of the slurry for chemical mechanical polishing of the present invention is preferably 9 to 13 and more preferably 10 to 12 from the viewpoints of excellent polishing rate, erosion suppressing effect and abrasive dispersion stability. The pH of the slurry for chemical mechanical polishing is adjusted with potassium hydroxide, sodium hydroxide, tetramethylammonium hydroxide, 2-hydroxyethyltrimethylammonium hydroxide, ammonia, trimethylamine, triethylamine, ethylenediamine, diethylenetriamine, N, N, N ′ , N′-tetramethylethylenediamine, N, N-dimethylethanolamine, N, N-dibutylethanolamine, N-methyldiethanolamine, N-butyldiethanolamine, triethanolamine, 2- (2-aminoethylamino) ethanol, 1 Bases such as (2-hydroxyethyl) piperazine and imidazole; acids such as hydrochloric acid, nitric acid, sulfuric acid, acetic acid, citric acid, malic acid and phthalic acid; or glycine, alanine, glutamic acid and aspa Amino acids such as Gin acid, ethylenediaminetetraacetic acid, chelating agents such as dihydroxyethylglycine; and the like may be carried out by adding to the slurry.

  Further, the slurry for chemical mechanical polishing of the present invention includes water-soluble polymers such as polyethylene glycol, polyvinyl pyrrolidone, poly (meth) acrylamide, poly (meth) acrylic acid, surfactants, antibacterial agents, water-soluble organic solvents, and the like. May be contained as long as the effects of the present invention are not impaired.

  The slurry for chemical mechanical polishing of the present invention is particularly useful for planarizing the uneven pattern formed on the insulating film, and is particularly suitable for applications where the insulating film for element isolation is polished and planarized in the STI formation process. ing. In the slurry for chemical mechanical polishing according to the present invention, the polishing rate of the stop film and the insulating film both decreases when the stop film is exposed. Occurrence of dishing in which the film is excessively removed can be suppressed. A silicon nitride film or a polysilicon film can be used as the stop film. However, since the erosion suppressing effect of the present invention is further exhibited, it is preferable to use a silicon nitride film as the stop film. On the other hand, the insulating film is preferably a silicon oxide film because the dishing suppression effect of the present invention is particularly exhibited. Note that the silicon oxide film may be modified with a small amount of boron, phosphorus, carbon, fluorine, or the like.

  As a method of chemical mechanical polishing using the chemical mechanical polishing slurry of the present invention, a known method can be adopted. For example, while supplying the slurry of the present invention to the surface of the polishing pad affixed on the polishing surface plate, the wafer on which the film to be polished is pressed and pressed, and the polishing surface plate and the wafer are both rotated to be polished. A method of polishing the film is mentioned. There is no restriction | limiting in particular as a polishing pad which can be used for this invention, Any of foamed resin, non-foamed resin, a nonwoven fabric, etc. can be used. Further, it may be a single-layer pad made of only a polishing layer, or a two-layer pad having a cushion layer under the polishing layer. As a method for supplying the chemical mechanical polishing slurry of the present invention onto the polishing pad, it may be fed as a single solution containing all the components, or a plurality of solutions containing each component may be fed to the middle of the piping. Alternatively, it may be mixed on the pad and adjusted to a desired concentration. In addition, the type and concentration of each component may be appropriately changed during polishing.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. The polishing performance was evaluated by the following method.

[PH of chemical mechanical polishing slurry]
Using a pH meter “F-22” manufactured by HORIBA, Ltd., standard buffer solution (phthalate pH buffer solution: pH 4.00 (25 ° C.), neutral phosphate pH buffer solution: pH 7.00 (25 ° C.) , Borate pH buffer solution: pH 9.00 (25 ° C.) was used for calibration, and then the pH of the chemical mechanical polishing slurry was measured at 25 ° C.

[Measurement of film thickness of silicon oxide and silicon nitride]
The film thickness measuring device “Nanospec Model 5100” manufactured by Nanometrics was used to measure the film thickness of silicon oxide and silicon nitride with an objective lens having a magnification of 10.

[Step measurement of patterned wafer]
Using a surface roughness measuring machine “SJ-400” manufactured by Mitutoyo Corporation, measurement is performed with a standard stylus, measurement range of 80 μm, JIS2001, GAUSS filter, cutoff value λc 2.5 mm, and cutoff value λs 8.0 μm. The step of the pattern wafer was obtained from the cross-sectional curve.

[Evaluation of polishing performance of patterned wafer]
A polishing pad “IC1400 (concentric circular groove); diameter 380 mm” manufactured by Nitta Haas Co., Ltd. is attached to a polishing surface plate of a polishing apparatus “BC-15” manufactured by MT Co., Ltd. The surface of the polishing pad was ground for 60 minutes at a dresser rotational speed of 140 rpm, a polishing pad rotational speed of 100 rpm, and a dresser load of 5 N while flowing pure water at a rate of 150 mL / min (hereinafter “conditioning”). Called).

  Next, while supplying polishing slurry at a rate of 120 mL / min under the conditions of polishing pad rotation speed 100 rpm, wafer rotation speed 99 rpm and polishing pressure 24 kPa, a silicon oxide film having a film thickness of 1000 nm and no pattern (by plasma chemical vapor deposition) A silicon wafer having a diameter of 2 inches having a formed PETEOS silicon oxide film) was polished for 60 seconds without conditioning. Then, after conditioning for 30 seconds, the wafer was exchanged and the polishing and conditioning were repeated again to polish a total of 10 wafers.

Subsequently, one STI polishing evaluation pattern wafer “SKW3-2” manufactured by SKW having a concavo-convex pattern in which linear convex portions and concave portions are alternately and repeatedly arranged was polished under the same conditions as described above. The pattern wafer has various pattern areas, and the following areas of patterns (i) to (iv) were selected as measurement targets of film thickness and level difference. Note that the pattern (ii) exists at a plurality of locations in the wafer, but a pattern adjacent to the pattern (i) was used as a measurement target.
Pattern (i): Pattern with convex width 100 μm and concave width 100 μm Pattern (ii): Pattern with convex width 50 μm and concave width 50 μm Pattern (iii): Pattern with convex width 500 μm and concave width 500 μm Pattern (iv): Pattern with a convex width of 70 μm and a concave width of 30 μm

  In each of the above patterns, the initial step between the convex part and the concave part is about 500 nm, the pattern convex part is a silicon oxide film having a film thickness of 13 nm on the silicon wafer, a silicon nitride film having a film thickness of 110 nm thereon, and further A silicon oxide film having a thickness of 670 nm (HDP silicon oxide film formed by high-density plasma chemical vapor deposition) is laminated thereon, and the pattern recess has a thickness of 670 nm after etching a silicon wafer by 400 nm to form a groove. This is a structure in which an HDP silicon oxide film is formed.

  In the polishing of the pattern wafer, the time when the silicon oxide film on the convex silicon nitride film of the pattern (i) disappears due to the polishing is referred to as just polishing, and the film thickness of the silicon oxide film and silicon nitride film of the pattern (i) in the just polishing The pattern step was measured. Thereafter, the pattern wafer is further polished for a time corresponding to 15% of the polishing time required for just polishing, a model test at the time of overpolishing is performed, and the film thickness and level difference of pattern (i) are measured again. The film thicknesses (ii) to (iv) were measured.

  The amount of polishing of the silicon nitride film of the pattern (i) being overpolished additionally after the just polishing was evaluated as “erosion amount”, and the amount of polishing of the silicon oxide film of the pattern (i) being overpolished was determined as “dishing amount” ". In any case, a smaller value is preferred.

  The measurement results are shown in the following table. In the following comparative examples, there was a film in which the convex silicon oxide films of the patterns (ii) to (iv) remained even after polishing until the overpolishing time. Therefore, in the following table | surface, the value of the convex part silicon oxide film thickness was also described.

  The film thickness (the total value of the thickness of the silicon nitride film and the thickness of the silicon oxide film on the silicon nitride film) of each pattern protrusion after overpolishing is a relative value {[pattern ( ii) to (iv) convex film thickness] − [pattern (i) convex film thickness]}. In any case, a smaller absolute value is preferable because a difference in polishing amount depending on the pattern shape is small. And the difference of the maximum value of the convex part film thickness of pattern (i)-(iv) and the minimum value was evaluated as "the maximum film thickness difference of a convex part." A smaller value is preferable because it is uniformly polished regardless of the pattern shape.

[Example 1]
1.0 g of polyethyleneimine having a number average molecular weight of 1200 (“Epomin SP-012” manufactured by Nippon Shokubai Co., Ltd.), 4.0 g of N-methylglucamine having a molecular weight of 195, and 40 g of sucrose having a molecular weight of 342 were dissolved in 1355 g of pure water. Thereafter, the slurry was uniformly mixed with 600 g of silica slurry (silica having an average particle size of 170 nm, “Semi-Sperse 25” manufactured by Cabot Micronics) to prepare a slurry for chemical mechanical polishing. The polyethyleneimine concentration in the slurry is 0.05 mass%, the N-methylglucamine concentration is 0.2 mass%, the sucrose concentration is 2.0 mass%, and the silica abrasive concentration is 7.5 mass%. The pH of the slurry was 10.9.

  As a result of evaluating the polishing performance of the pattern wafer, as shown in Table 2, the chemical mechanical polishing slurry of Example 1 has an extremely small erosion amount of 6 nm and a dishing amount of 20 nm in the pattern (i). The silicon nitride film and the silicon oxide film were extremely excellent in the polishing suppressing effect. Moreover, as shown in Table 2, the slurry had a small difference in the maximum film thickness of the protrusions as small as 9 nm, and was excellent in pattern uniformity.

[Examples 2 to 5]
A slurry for chemical mechanical polishing was prepared in the same manner as in Example 1 except that the components and concentration of the chemical mechanical polishing slurry were changed as shown in Table 1. The pH of the slurry was as shown in Table 1.

  As a result of evaluating the polishing performance of the pattern wafer, as shown in Table 2, the chemical mechanical polishing slurries of Examples 2 to 5 had both a small amount of erosion and a small amount of dishing, and were excellent in polishing suppression effect during overpolishing. . Further, as shown in Table 2, the slurry had a small maximum film thickness difference between the convex portions and was excellent in pattern uniformity.

[Examples 6 to 10]
A slurry for chemical mechanical polishing was prepared in the same manner as in Example 1 except that the components and concentration of the chemical mechanical polishing slurry were changed as shown in Table 3. However, in Examples 6 and 7, potassium hydroxide was added at a rate of 1.7 g with respect to 1 kg of the slurry. The pH of the slurry was as shown in Table 3. In addition, “Epomin SP-006” manufactured by Nippon Shokubai Co., Ltd. was used as polyethyleneimine having a number average molecular weight of 600, and “Epomin SP-018” manufactured by Nippon Shokubai Co., Ltd. was used as polyethyleneimine having a number average molecular weight of 1800. Moreover, what removed the low molecular-weight component of "PAS-21" by Nitto Boseki Co., Ltd. by preparative chromatography was used as poly (diallylamine) with a number average molecular weight of 3200.

  As a result of evaluating the polishing performance of the pattern wafer, as shown in Table 4, the chemical mechanical polishing slurries of Examples 6 to 10 had both a small amount of erosion and a small amount of dishing, and were excellent in polishing suppression effect during overpolishing. . Further, as shown in Table 4, the slurry had a small maximum film thickness difference between the convex portions and was excellent in pattern uniformity.

[Comparative Examples 1-5]
A chemical mechanical polishing slurry was prepared in the same manner as in Example 1 except that the components and concentration of the chemical mechanical polishing slurry were changed as shown in Table 5. The pH of the slurry was as shown in Table 5.

  As a result of evaluating the polishing performance of the pattern wafer, as shown in Table 6, the chemical mechanical polishing slurries of Comparative Examples 3 and 5 have a large erosion amount and dishing amount. It was inferior to the polishing suppression effect. Further, the slurry had a large difference in maximum film thickness at the convex portions and was inferior in pattern uniformity. On the other hand, the chemical mechanical polishing slurries of Comparative Examples 1, 2, and 4 had a small maximum erosion amount and dishing amount, but had a large maximum film thickness difference between the convex portions and were inferior in pattern uniformity.

[Comparative Examples 6-8]
A chemical mechanical polishing slurry was prepared in the same manner as in Example 1 except that the components and concentration of the chemical mechanical polishing slurry were changed as shown in Table 7. The pH of the slurry was as shown in Table 7.

  As a result of evaluating the polishing performance of the pattern wafer, as shown in Table 8, the chemical mechanical polishing slurries of Comparative Examples 6 and 7 had a small maximum erosion amount and dishing amount, but a large maximum film thickness difference between the convex portions, The pattern uniformity was poor. On the other hand, the chemical mechanical polishing slurry (ie, silica slurry) of Comparative Example 8 had a large amount of erosion and dishing and was inferior in pattern uniformity.

  As can be seen from Examples 1 to 10 above, the slurry for chemical mechanical polishing of the present invention containing the compound (a), the compound (b) and the compound (c) is the convex portion when the pattern wafer is polished. The maximum film thickness difference is small and the pattern uniformity is excellent. Further, the chemical mechanical polishing slurry of the present invention has both a small amount of erosion and a low amount of dishing, and is excellent in polishing suppression effect during overpolishing.

  On the other hand, as can be seen from Comparative Examples 1 to 8, the slurry for chemical mechanical polishing not containing any of the compound (a), the compound (b) and the compound (c) is the maximum film thickness of the convex portion. The difference is large and the pattern uniformity is poor.

  If the chemical mechanical polishing slurry containing the chemical mechanical polishing erosion inhibitor of the present invention is used, erosion and dishing can be effectively suppressed, and variations in the polishing amount due to the pattern shape can be suppressed. The chemical mechanical polishing erosion inhibitor and the chemical mechanical polishing slurry of the present invention are particularly useful in the STI formation step for separating semiconductor elements.

1 Pattern wafer 2 Oxide insulating film (silicon oxide, etc.)
3 Stop film (silicon nitride, etc.)
4 Insulating film (silicon oxide, etc.)
D1 Initial film thickness of stop film D2 Erosion amount D3 Dishing amount

Claims (14)

  Compound (a) having 4 or more hydroxyl groups and no amino group, Compound (b) having 4 or more hydroxyl groups and 1 amino group, and Compound (c) having 4 or more amino groups An anti-erosion agent for chemical mechanical polishing containing   The erosion inhibitor for chemical mechanical polishing according to claim 1, wherein the compound (a) has a molecular weight of 100 to 100,000 and a hydroxyl group content of 5 to 40 mmol / g.   The erosion inhibitor for chemical mechanical polishing according to claim 1 or 2, wherein the compound (a) has a skeleton derived from a monosaccharide.   The erosion for chemical mechanical polishing according to any one of claims 1 to 3, wherein the compound (a) is at least one selected from the group consisting of a compound to which 2 to 50 monosaccharides are bonded and a derivative thereof. Inhibitor.   The erosion inhibitor for chemical mechanical polishing according to any one of claims 1 to 4, wherein the molecular weight of the compound (b) is 150 to 1,000.   The erosion inhibitor for chemical mechanical polishing according to any one of claims 1 to 5, wherein the compound (b) is at least one selected from glucamine and derivatives thereof.   The erosion inhibitor for chemical mechanical polishing according to any one of claims 1 to 6, wherein the compound (c) has a molecular weight of 200 to 100,000 and an amino group content of 3 to 30 mmol / g. .   The compound (c) is a polyalkyleneimine (c1); allylamine, N-alkylallylamine, N, N-dialkylallylamine, diallylamine, N-alkyldiallylamine, vinylamine, vinylpyridine and (meth) acrylic acid-N, N- At least one monomer selected from the group consisting of dialkylaminoethyl (wherein the alkylene represents a divalent alkylene group having 1 to 6 carbon atoms, and the alkyl represents a monovalent alkyl group having 1 to 4 carbon atoms). Selected from the group consisting of a polymer (c2) obtained by polymerizing 25 to 100% by mass and 75 to 0% by mass of another monomer having an unsaturated double bond; and derivatives thereof The erosion inhibitor for chemical mechanical polishing according to any one of claims 1 to 7, wherein the erosion inhibitor is for chemical mechanical polishing.   A chemical mechanical polishing slurry comprising the chemical mechanical polishing erosion inhibitor according to any one of claims 1 to 8, abrasive grains (d), and water.   The slurry for chemical mechanical polishing according to claim 9, wherein the abrasive grains (d) are silica. In slurry for chemical mechanical polishing,
The concentration of the compound (a) is 0.01 to 10% by mass,
The concentration of the compound (b) is 0.001 to 10% by mass,
The concentration of the compound (c) is 0.001 to 5% by mass,
The concentration of the abrasive grains (d) is 0.2 to 30% by mass,
The slurry for chemical mechanical polishing according to claim 9 or 10.   The slurry for chemical mechanical polishing according to any one of claims 9 to 11, wherein the pH is 9 to 13.   The chemical mechanical polishing method of grind | polishing an insulating film using the slurry for chemical mechanical polishing as described in any one of Claims 9-12.   The chemical mechanical polishing method according to claim 13, wherein the silicon oxide film on the silicon nitride film is polished.