JP2005236275A - Water disperse form for chemical mechanical polishing and chemical mechanical polishing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water disperse form for a chemical mechanical polishing capable of decreasing polishing damages without reducing any polishing speed, and to provide a chemical mechanical polishing method using the water disperse form for the polishing, capable of removing excess insulating films in a refined element isolation process. <P>SOLUTION: The water disperse form for the chemical mechanical polishing contains abrasive grains A including ceria, an anion nature soluble polymer B, and a cation nature surfactant C. It is characterized in that a content of the anion nature soluble polymer B is 60 to 600 parts by weight per the abrasive grains A of 100 parts by weight including the ceria, and a content of the cation nature surfactant C is 0.1 to 100ppm to the whole water disperse form for the chemical mechanical polishing. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an aqueous dispersion for chemical mechanical polishing and a chemical mechanical polishing method. More specifically, the chemical mechanical polishing aqueous dispersion suitably used for removal of an extra insulating film in a miniaturization element isolation (trench isolation) process, and the above-described polishing capable of flattening an interlayer insulating film in a miniaturization element isolation process The present invention relates to a chemical mechanical polishing method using an aqueous dispersion.

  As the degree of integration of semiconductor devices is increased and multilayer wiring is increased, the storage capacity of memory devices is dramatically increasing. This is supported by the progress of miniaturization of processing technology, but despite the fact that multilayer wiring has been made, the chip size has increased, and the number of processes has increased along with miniaturization. Incurs high costs. Under such circumstances, chemical mechanical polishing technology has been introduced for polishing processed films and the like, and has attracted attention. By applying this chemical mechanical polishing technique, many miniaturization techniques such as planarization have been realized.

  As such a miniaturization technique, for example, a so-called STI technique, known as Shallow Trench Isolation, is known. In this STI technique, chemical mechanical polishing is performed in order to remove an extra insulating layer formed on a wafer substrate. In this chemical mechanical polishing step, the flatness of the surface to be polished is important, and various polishing agents have been studied for that purpose.

  For example, in Patent Document 1 and Patent Document 2, in the chemical mechanical polishing process of STI, by using an aqueous dispersion using ceria as polishing abrasive grains, the polishing rate is increased and the coating with relatively few polishing flaws is provided. It is disclosed that a polished surface can be obtained.

  In recent years, as the number of layers of semiconductor elements has increased and the definition has been increased, further improvements in yield and throughput of semiconductor elements have been demanded. Along with this, there has been a demand for polishing at a high speed without causing any scratches on the polished surface after the chemical mechanical polishing step.

  Regarding the reduction of polishing scratches on the surface to be polished, a dispersant such as a polycarboxylic acid type polymer compound containing ammonium acrylate, chitosan acetate (Patent Document 3), dodecylamine (Patent Document 4), polyvinylpyrrolidone ( There is a report that an abrasive combined with a surfactant (additive) such as Patent Document 5) is effective. However, in these abrasives, from the viewpoint of dispersibility and settling prevention of cerium oxide particles in the slurry and reduction of polishing scratches, the dispersant is 0.01 parts by weight or more with respect to 100 parts by weight of cerium oxide particles. It is said that 0 parts by weight or less and the surfactant is preferably 0.01 parts by weight or more and 1000 parts by weight or less.

  Further, Patent Document 6 discloses an abrasive comprising 5% by weight or less of cerium oxide and a cationic surfactant having a critical micelle concentration or less, and this abrasive further comprises 2 to 6% by weight of an anion. It is also disclosed that an ionic surfactant may be included. However, the types of anionic surfactants are not specifically disclosed, and the cationic surfactants are only exemplified by ammonium compounds and pyridinium compounds having an alkyl group having 6 to 18 carbon atoms. is there.

Patent Document 7 discloses an abrasive containing ceria and a nitrogen atom-containing surfactant, and further discloses that this abrasive may further contain a dispersing agent such as high molecular weight polyacrylic acid. Has been. However, this publication does not specifically disclose the combined use of a nitrogen atom-containing surfactant and a dispersant.

Furthermore, according to these techniques, although an effect is seen in reducing polishing scratches, the polishing rate is reduced, and an improvement in throughput has not yet been achieved.
JP-A-5-326469 JP-A-9-270402 JP 2000-109809 A JP 2001-7061 A JP 2001-185514 A US Patent 6,443,811 JP 2002-190458 A

  In view of the situation of the above STI technique, the present invention removes an aqueous dispersion for chemical mechanical polishing that can reduce polishing scratches without reducing the polishing rate, and an extra insulating film in the miniaturization element separation step. An object of the present invention is to provide a chemical mechanical polishing method using the above polishing aqueous dispersion.

  In the chemical mechanical polishing aqueous dispersion containing abrasive grains containing ceria, the present inventors have used the above object by combining a specific amount of an anionic water-soluble polymer and a specific amount of a cationic surfactant. Has been found to be achieved, and the present invention has been completed.

That is, the chemical mechanical polishing aqueous dispersion according to the present invention is a chemical mechanical polishing aqueous dispersion containing abrasive grains (A) containing ceria, an anionic water-soluble polymer (B), and a cationic surfactant (C). A dispersion,
The content of the anionic water-soluble polymer (B) is 60 to 600 parts by mass per 100 parts by mass of the abrasive grains (A) containing ceria,
The content of the cationic surfactant (C) is 0.1 to 100 ppm with respect to the entire chemical mechanical polishing aqueous dispersion.

  The chemical mechanical polishing method according to the present invention is characterized in that an excess insulating film in the fine element separation step is removed using the chemical mechanical polishing aqueous dispersion.

  According to the present invention, it is possible to reduce polishing scratches without reducing the polishing rate in the step of removing excess insulating film in the miniaturization element separation step.

Hereinafter, each component of the chemical mechanical polishing aqueous dispersion according to the present invention will be described in detail.
The abrasive (A) blended in the chemical mechanical polishing aqueous dispersion according to the present invention contains ceria as a constituent component. As this ceria, abrasive grains obtained by firing cerium hydroxide, cerium carbonate, cerium oxalate or the like can be used. Further, the content of ceria in the abrasive grains (A) is preferably 20 to 100 mass%, more preferably 50 to 100 mass%, still more preferably 80 to 100 mass% with respect to the entire abrasive grains (A). %.

The abrasive grains (A) may be ceria alone, ceria, silica, alumina, titanium oxide, chromium oxide, manganese dioxide, dimanganese trioxide, iron oxide, zirconium oxide, silicon carbide, boron carbide, diamond, barium carbonate, etc. It may be a mixture with other components. Moreover, you may use the abrasive grain which coat | covered a part or whole of the ceria particle surface with these other components as said abrasive grain (A).

Moreover, in this invention, well-known organic particle | grains, organic-inorganic composite particle | grains, etc. can be used together with the abrasive grain (including the said mixture) which consists of said ceria.
Examples of the organic material constituting the organic particles include polyvinyl chloride, polystyrene, styrene copolymer, polyacetal, saturated polyester, polyamide, polycarbonate, polyethylene, polypropylene, poly-1-butene, and poly-4-methyl-1-pentene. Such as polyolefin, olefin copolymer, phenoxy resin, thermoplastic resin such as (meth) acrylic resin such as polymethyl methacrylate; styrene, methyl methacrylate, etc. are copolymerized with divinylbenzene, ethylene glycol dimethacrylate, etc. And a copolymer resin having a crosslinked structure obtained by thermosetting resin such as phenol resin, urea resin, melamine resin, epoxy resin, alkyd resin, and unsaturated polyester resin.

  The organic particles made of these materials can be used singly or in combination of two or more. In addition, organic particles made of these materials can be produced by various methods such as an emulsion polymerization method, a suspension polymerization method, an emulsion dispersion method, and a pulverization method.

  The organic / inorganic composite particles include, for example, particles in which alkoxysilane is polycondensed in a state where inorganic particles and organic particles are mixed and polysiloxane is bonded to at least the surface of the organic particles, silica, ceria, and the like. Examples thereof include particles in which inorganic particles are combined with organic particles by electrostatic force or the like. The polysiloxane or the like may be directly bonded to the anion group of the organic particles, or may be indirectly bonded through a silane coupling agent or the like.

  The average particle diameter of the abrasive grains (A) is preferably 0.01 to 3 μm, more preferably 0.02 to 1 μm, and still more preferably 0.04 to 0.7 μm. If the average particle size is too small, the polishing rate tends to be insufficient. On the other hand, if the average particle size is too large, the abrasive grains may settle or separate, and a stable polishing aqueous dispersion may not be obtained. The average particle diameter can be measured by an apparatus such as dynamic light scattering or laser scattering diffraction, or a transmission electron microscope. Moreover, you may calculate from the specific surface area data of the dry abrasive grain.

  The compounding amount of the abrasive grains (A) in the chemical mechanical polishing aqueous dispersion according to the present invention is preferably 5% by mass or less, more preferably 0.02 to 5% by mass, based on 100% by mass of the entire polishing aqueous dispersion. %, More preferably 0.05 to 3% by mass, particularly preferably 0.1 to 2% by mass. The content of ceria is preferably 0.02 to 5% by mass, more preferably 0.05 to 3% by mass, and further preferably 0.1 to 2% by mass, based on 100% by mass of the entire polishing aqueous dispersion. %. If the ceria content is too low, efficient polishing may not be achieved. On the other hand, if the content is too high, the polishing aqueous dispersion may be easily dried, resulting in generation of coarse dry powder and an increase in scratches. is there.

  The chemical mechanical polishing aqueous dispersion according to the present invention further contains an anionic water-soluble polymer (B). Examples of the anionic water-soluble polymer (B) include (1) polycarboxylic acid, polystyrene sulfonic acid, polyisoprene sulfonic acid and polyglutamic acid, and (2) a monomer containing an anionic group and other simple units. A copolymer with a monomer, (3) a salt of the acid (1), (4) a mixture of the acid (1) and the salt (3), and (5) an anionic property of the copolymer (2). Examples thereof include a salt compound having a neutralized group, and (6) a mixture of the copolymer (2) and the salt compound (5).

As said polycarboxylic acid, poly (meth) acrylic acid etc. can be mentioned, for example.
Examples of the monomer having an anionic group include (meth) acrylic acid, styrene sulfonic acid, naphthalene sulfonic acid, and isoprene sulfonic acid. Examples of the other monomer include ( Examples thereof include (meth) acrylamide, (meth) acrylic acid ester, styrene, butadiene, and isoprene. Examples of the (meth) acrylic acid ester include methyl (meth) acrylate, ethyl (meth) acrylate, benzyl (meth) acrylate, and the like.

  When the salt compound (5) or the mixture (6) of the copolymer (2) and the salt compound (5) is used as the anionic water-soluble polymer (B), Ammonium ions, alkylammonium ions, potassium ions and the like can be mentioned.

  When using the salt compound (5) or the mixture (6) of the copolymer (2) and the salt compound (5) as the anionic water-soluble polymer (B), a monomer containing an anionic group And other monomers may be copolymerized and then all or part of the anionic group of the copolymer may be neutralized to form a salt compound (5) or a mixture (6) thereof, or Alternatively, a monomer containing an anionic group and / or a salt thereof and another monomer may be copolymerized to form a salt compound (5) or a mixture (6) thereof.

  The weight average molecular weight of the anionic water-soluble polymer (B) in terms of polyethylene glycol measured by gel permeation chromatography (GPC) using water as a solvent is preferably 3,000 to 30,000, more preferably. Is 4,000 to 20,000, more preferably 5,000 to 15,000. By using the anionic water-soluble polymer (B) having a weight average molecular weight within this range, an aqueous dispersion for chemical mechanical polishing having a good balance between polishing speed and flattening performance can be obtained.

  The compounding amount of the anionic water-soluble polymer (B) in the chemical mechanical polishing aqueous dispersion according to the present invention is 60 to 600 parts by mass, preferably 60 parts per 100 parts by mass of the abrasive (A) containing ceria. It is -500 mass parts. More preferably, it is 60-450 mass parts. By blending the anionic water-soluble polymer (B) in an amount within this range, an aqueous dispersion for chemical mechanical polishing excellent in the balance between the dispersibility of the abrasive grains (A) containing ceria and the polishing rate can be obtained. it can.

  The chemical mechanical polishing aqueous dispersion of the present invention further contains a cationic surfactant (C). As the cationic surfactant (C), a cationic surfactant having a nitrogen atom can be used, and a cationic surfactant having a nitrogen atom and no oxygen atom is preferred. Specifically, alkyltrimethylammonium chloride containing an alkyl group having 12 to 18 carbon atoms such as lauryltrimethylammonium chloride, cetyltrimethylammonium chloride, stearyltrimethylammonium chloride; 12 to 18 carbon atoms such as distearyldimethylammonium chloride. Examples thereof include dialkyldimethylammonium chloride, alkylimidazoline, benzalkonium chloride, polyethyleneimine, laurylamine acetate, stearylamine acetate, and compounds having a structure represented by the following formula (1).

Of these cationic surfactants (C), lauryltrimethylammonium chloride, polyethyleneimine, and a compound having a structure represented by the above formula (1) are preferable.
The molecular weight of the cationic surfactant (C) is preferably 500 or more, more preferably 500 to 1,000,000, further preferably 1000 to 500,000, and particularly preferably 1000 to 250,000. The molecular weight is a theoretical value calculated from the chemical formula when the cationic surfactant (C) is a monomer, and is a weight average molecular weight measured by GPC in the case of a polymer. The weight average molecular weight is a value measured for each polymer using an appropriate solvent and converted by an appropriate standard substance. For example, in the case of polyethyleneimine, a 0.2 mol / liter monoethanolamine aqueous solution (adjusted to pH = 5.1 with acetic acid) as a solvent, and sugars such as maltotriose, maltoheptaose, and pullulan as standard substances. use. In the case of the compound having the structure represented by the above formula (1), an aqueous solution containing 5 mol / liter of acetic acid and 0.2 mol / liter of sodium nitrate is used as a solvent, and polyethylene glycol is used as a standard substance.

  When a compound having a structure represented by the above formula (1) is used as the cationic surfactant (C), a surfactant having a structure in which the structure represented by the above formula (1) is continuous is preferable. . The molecular weight of the compound having the structure represented by the formula (1) is not particularly limited, but the viscosity at 25 ° C. of an aqueous solution of 40% by mass of the cationic surfactant (C) is 5,000 to 50, The molecular weight is preferably 000 mPa · s, more preferably 7,500 to 20,000 mPa · s, and particularly preferably 10,000 to 15,000 mPa · s. As a commercial item of such a compound, for example, Adeka thioace PD-50 (manufactured by Asahi Denka Kogyo Co., Ltd.) can be mentioned.

  The compounding amount of the cationic surfactant (C) in the chemical mechanical polishing aqueous dispersion according to the present invention is 0.1 to 100 ppm, preferably 1 to 50 ppm, based on the entire polishing aqueous dispersion. More preferably, it is 1-20 ppm. By adding the cationic surfactant (C) in an amount within this range, an aqueous dispersion for chemical mechanical polishing having a good balance between the polishing rate and the effect of reducing polishing scratches on the polished surface after polishing can be obtained. it can.

  The chemical mechanical polishing aqueous dispersion according to the present invention may further contain an acid (D), thereby stabilizing the polishing aqueous dispersion and improving the selectivity. This acid (D) is not particularly limited, and either an organic acid or an inorganic acid can be used.

  Examples of organic acids include p-toluenesulfonic acid, isoprenesulfonic acid, gluconic acid, lactic acid, citric acid, tartaric acid, malic acid, glycolic acid, malonic acid, formic acid, oxalic acid, succinic acid, fumaric acid, maleic acid, and phthalic acid Is mentioned.

Examples of inorganic acids include nitric acid, hydrochloric acid and sulfuric acid.
These organic acids and inorganic acids can be used singly or in combination of two or more, and an organic acid and an inorganic acid can be used in combination.

The compounding amount of the acid (D) is preferably 2% by mass or less, more preferably 1% by mass or less, based on 100% by mass of the entire chemical mechanical polishing aqueous dispersion.
In the present invention, the chemical mechanical polishing aqueous dispersion contains a base (E), and the pH is adjusted according to the constituent material of the abrasive used, thereby further improving the dispersibility, polishing rate, and selectivity of the abrasive. be able to. This base (E) is not particularly limited, and either an organic base or an inorganic base can be used.

Examples of the organic base include nitrogen-containing organic compounds such as ethylenediamine and ethanolamine.
Examples of the inorganic base include ammonia, potassium hydroxide, sodium hydroxide, lithium hydroxide and the like.

These organic bases and inorganic bases can be used singly or in combination of two or more, and an organic base and an inorganic base can be used in combination.
The blending amount of the base (E) is preferably 1% by mass or less, more preferably 0.5% by mass or less, based on 100% by mass of the entire chemical mechanical polishing aqueous dispersion.

  Examples of the medium of the chemical mechanical polishing aqueous dispersion according to the present invention include water, a mixed medium of water and alcohol (such as methanol), a mixed medium of water and further other components, and the like. Of these, water is preferably used.

  The pH of the chemical mechanical polishing aqueous dispersion is preferably 5 to 12. If the pH is within this range, it is possible to obtain a chemical mechanical polishing aqueous dispersion capable of obtaining a polished surface with a high polishing rate and reduced polishing scratches, and also the stability of the polishing aqueous dispersion itself. Excellent.

  The polishing aqueous dispersion according to the present invention contains the above-described components in the above amounts, and this polishing aqueous dispersion can be stored and transported in a concentrated state. The concentrated polishing aqueous dispersion is diluted when used in the chemical mechanical polishing step, and is used by adjusting the blending amount of each component within the above range.

  When concentrating the polishing aqueous dispersion according to the present invention, it is preferable that the amount of abrasive grains (A) containing ceria does not exceed 20% by mass of the entire polishing aqueous dispersion. By concentrating to a concentration in this range, the polishing aqueous dispersion can be stably stored for a long period of time.

  The chemical mechanical polishing aqueous dispersion according to the present invention can be preferably used for removing an excess insulating film in a miniaturization element isolation (STI) process in the manufacture of a semiconductor device. Specifically, polishing of an object to be polished such as a semiconductor substrate having a concavo-convex surface formed on a substrate made of silicon or the like in which a groove for element isolation is formed, and an insulating film exemplified below. Can be used.

The insulating film composed of the insulating material, a silicon oxide film (SiO ₂ film), a boron phosphorus silicate film obtained by adding a small amount of boron and phosphorus in SiO ₂ (BPSG film), SiO ₂
Examples thereof include an insulating film called FSG (Fluorine doped silicate glass) doped with fluorine, a silicon oxide insulating film having a low dielectric constant, and the like.

Examples of the silicon oxide film include a thermal oxide film, a PETEOS film (Plasma Enhanced-TEOS film), an HDP film (High Density Plasma Enhanced-TEOS film), a silicon oxide film obtained by a thermal CVD method, and the like.

The boron phosphorus silicate film (BPSG film) can be manufactured by an atmospheric pressure CVD method (AP-CVD method) or a low pressure CVD method (LP-CVD method).
The insulating film called FSG can be manufactured by chemical vapor deposition using high-density plasma as an acceleration condition.

  The low dielectric constant silicon oxide insulating film can be obtained by applying a raw material on a substrate by a spin coating method or the like and then heating in an oxidizing atmosphere. As such a silicon oxide insulating film, for example, an HSQ film (Hydrogen Silsesquioxane film) using triethoxysilane as a raw material, or an MSQ film (Methyl) containing methyltrimethoxysilane as a part of the raw material in addition to tetraethoxysilane is used. Silsesquioxane film).

The thermal oxide film can be manufactured by exposing high temperature silicon to an oxidizing atmosphere and chemically reacting silicon and oxygen or silicon and moisture.
The PETEOS film can be manufactured by chemical vapor deposition using tetraethylorthosilicate (TEOS) as a raw material and using plasma as an accelerating condition.

The HDP film can be manufactured by chemical vapor deposition using tetraethylorthosilicate (TEOS) as a raw material and using high-density plasma as a promoting condition.
The silicon oxide film obtained by the thermal CVD method can be manufactured by an atmospheric pressure CVD method (AP-CVD method) or a low pressure CVD method (LP-CVD method).

As an object to be polished having such an insulating film, for example, a wafer having the structure shown in FIG. 2 can be cited.
Polishing by the chemical mechanical polishing method according to the present invention is performed by chemical mechanical polishing apparatuses such as “EPO-112” and “EPO-222” manufactured by Ebara Manufacturing Co., Ltd., and “LGP-” manufactured by Lapmaster SFT. Chemical mechanical polishing equipment such as “510” and “LGP-552”, chemical mechanical polishing equipment such as “Mirra” manufactured by Applied Materials, chemical mechanical polishing equipment such as “Teres” manufactured by Lam Research, Speed Fam -Model “AVANTI” manufactured by IPEC
It can be performed under known polishing conditions using a chemical mechanical polishing apparatus such as “472”.

  The chemical mechanical polishing method according to the present invention will be specifically described with reference to FIG. 1, but the present invention is not limited to this method. First, the polishing pad 1 is fixed on the surface plate 2 that rotates about the axis. On the other hand, the workpiece 4 is attached to one end of the pressure head 3. The pressure head 3 can rotate and move while pressing the object to be polished 4 against the surface of the polishing pad 1 to slide the object to be polished 4 on the surface of the polishing pad 1. The chemical mechanical polishing method according to the present invention is performed by sliding the chemical mechanical polishing aqueous dispersion according to the present invention on the surface of the polishing pad 1 from above (slurry supply unit 5 and the like), thereby performing extra sliding. This is a polishing method for removing the insulating film.

As preferable polishing conditions, the platen rotation speed is usually 50 to 150 rpm, preferably 80 to 120 rpm, and the pressure head rotation speed is usually 50 to 150 rpm, preferably 80 to 120 rpm. The head rotation speed is usually 0.5 to 2, preferably 0.7 to 1.5, and the polishing pressure is usually 200 to 800 g / cm ² , preferably 400 to 6.
Was 200 g / cm ^2, polishing aqueous dispersion supply rate is usually 50 to 300 / min, preferably 100-200 ml / min.

As the polishing pad, known ones can be used. For example, trade names “IC1000 / SUBA400”, “IC1010, SUBA series, Polytex series” manufactured by Rodel Nitta Co., etc. can be used. Moreover, you may change into a polishing pad from which a kind differs on the way in the case of grinding | polishing.

According to the chemical mechanical polishing method of the present invention, the insulating film can be polished at a polishing rate of preferably 10 nm / min or more, more preferably 20 nm / min or more.
[Example]
Hereinafter, the present invention will be described more specifically with reference to examples.

[Example 1]
<Preparation of aqueous dispersion for chemical mechanical polishing>
After bastonite was dissolved in nitric acid, recrystallization was repeated three times to obtain high-purity cerium carbonate. This was heated in air at 900 ° C. for 5 hours to obtain ceria. The ceria was pulverized by a bead mill using zirconia beads, and then classified by a water tank process.

  The ceria particles thus obtained were dispersed in ion-exchanged water so as to have a content of 5.0% by mass in the presence of nitric acid, the pH was adjusted to 6, and the average particle size (secondary particle size) 0. An aqueous dispersion containing 24 μm of ceria (hereinafter referred to as “ceria aqueous dispersion”) was obtained.

  Next, ion-exchanged water is added to this ceria aqueous dispersion to dilute to 0.5% by mass, and an aqueous solution of ammonium polyacrylate having a weight average molecular weight of 7,000 (anionic water-soluble polymer (B)) (Concentration: 30% by mass) was added in an amount such that ammonium polyacrylate was 1.6% by mass with respect to the entire chemical mechanical polishing aqueous dispersion and stirred for 5 minutes. Further, as the cationic surfactant (C), polydimethylmethylenepiperidinium chloride (weight average molecular weight: 120,000) corresponding to a compound having a structure in which structural units of the following formula (1) are continuously formed is used. Addition of aqueous solution (trade name “Adeka thioace PD-50”, manufactured by Asahi Denka Kogyo Co., Ltd.) to an amount of 10 ppm in terms of polydimethylmethylenepiperidinium chloride with respect to the total amount of chemical mechanical polishing aqueous dispersion Then, the mixture was stirred for 5 minutes to prepare an aqueous dispersion for chemical mechanical polishing having a pH of 6.3. The weight-average molecular weight of polydimethylmethylenepiperidinium chloride was measured by GPC using an aqueous solution containing acetic acid 0.5 mol / liter and nitric acid 0.2 mol / liter as a solvent and polyethylene glycol as a standard substance. .

<Chemical mechanical polishing of insulating film>
Using the chemical mechanical polishing aqueous dispersion, chemical mechanical polishing was performed under the following conditions using a PETEOS film having a diameter of 8 inches (without a step) as a material to be polished.
(Polishing conditions)
Polishing equipment: Model “EPO-112” manufactured by Ebara Corporation
Polishing pad: Rodel Nitta Co., Ltd., “IC1000 / SUBA400”
Surface plate rotation speed: 100 times / minute Polishing head rotation speed: 107 times / minute Polishing head pressing pressure: 490 g / cm ²
Polishing aqueous dispersion supply rate: 200 ml / min Polishing time: 5 minutes <Evaluation of polishing rate>
Using an optical interference film thickness meter “NanoSpec 6100” (manufactured by Nanometrics Japan Co., Ltd.), the film thickness of the material to be polished is measured before and after polishing, and the difference is divided by the polishing time to calculate the polishing rate. did. The polishing rate is shown in Table 1.

When this value exceeds 20 nm / min, the polishing rate is extremely good. When the value is 10 to 20 nm / min, the polishing rate is good. When the value is less than 10 nm / min, the polishing rate is usually judged as poor.
<Evaluation of the number of scratches>
The PETEOS film after polishing was inspected for defects by “KLA2351” manufactured by KLA-Tencor Corporation. First, the number of “KLA2351” counted as “defects” was measured for the entire range of the wafer surface under the conditions of a pixel size of 0.39 μm and a threshold value of 50. Next, 250 of these “defects” are randomly extracted and observed, whether each “defect” is a scratch or adhering dust, and the ratio of scratches in these “defects” is calculated. From this, the number of scratches per wafer was calculated. The results are shown in Table 1.

  When this value is 500 pieces / face or less, the number of scratches is very good, when it is 501-2,000 pieces / face, the number of scratches is good, and when it is 2,001 pieces / face or more, the number of scratches is usually poor. It is determined.

[Example 2]
A chemical machine having a pH of 6.3 in the same manner as in Example 1 except that the amount of Adekathioace PD-50 was changed to 100 ppm in terms of polydimethylmethylenepiperidinium chloride based on the total amount of the chemical mechanical polishing aqueous dispersion. A polishing aqueous dispersion was prepared and its polishing characteristics were evaluated. The results are shown in Table 1.

[Comparative Example 1]
A chemical mechanical polishing aqueous dispersion having a pH of 6.4 was prepared in the same manner as in Example 1 except that the cationic surfactant (C) was not used, and the polishing characteristics were evaluated. The results are shown in Table 1.

[Comparative Examples 2 to 4]
The same procedure as in Example 1 was conducted except that the blending amount of Adeka thioace PD-50 was changed to the polydimethyldimethylmethylenepiperidinium chloride equivalent amount shown in Table 1 with respect to the total amount of the chemical mechanical polishing aqueous dispersion. A pH 6.3 chemical mechanical polishing aqueous dispersion was prepared and its polishing characteristics were evaluated. The results are shown in Table 1.

[Example 3]
Except for adding 10 ppm of lauryltrimethylammonium chloride (theoretical molecular weight: 263.5) as a cationic surfactant (C) to the total amount of the chemical mechanical polishing aqueous dispersion instead of polydimethylmethylenepiperidinium chloride. Then, a chemical mechanical polishing aqueous dispersion having a pH of 6.3 was prepared in the same manner as in Example 1, and the polishing characteristics were evaluated. The results are shown in Table 1.

[Comparative Example 5]
A chemical mechanical polishing aqueous dispersion having a pH of 6.3 as in Example 3 except that 10000 ppm of lauryltrimethylammonium chloride as a cationic surfactant (C) was added to the total amount of the chemical mechanical polishing aqueous dispersion. And the polishing characteristics were evaluated. The results are shown in Table 1.

[Examples 4 to 8]
Example 1 except that polyethyleneimine having the weight average molecular weight described in Table 1 was used as the cationic surfactant (C) in place of polydimethyldimethylmethylenepiperidinium chloride in the amounts shown in Table 1, respectively. Similarly, an aqueous dispersion for chemical mechanical polishing at pH 6.3 was prepared and evaluated for polishing characteristics. The results are shown in Table 1. The weight-average molecular weight of polyethyleneimine was measured by GPC using a 0.2 mol / liter monoethanolamine aqueous solution adjusted to pH = 5.1 with acetic acid as a solvent and the following saccharides as standard substances. .

Maltotriose: Molecular weight = 504
Maltoheptaose: molecular weight = 1153
Pullulan: molecular weight = 5800, 12200, 23700, 48000,
100000, 186000, 380000,
853000
[Comparative Example 6]
A chemical mechanical polishing aqueous dispersion having a pH of 6.3 in the same manner as in Example 6 except that polyethyleneimine was added as a cationic surfactant (C) in an amount of 0.05 ppm based on the total amount of the chemical mechanical polishing aqueous dispersion. And the polishing characteristics were evaluated. The results are shown in Table 1.

[Comparative Example 7]
A chemical mechanical polishing aqueous dispersion having a pH of 6.3 was prepared in the same manner as in Example 4 except that polyethyleneimine was added as a cationic surfactant (C) at 1000 ppm based on the total amount of the chemical mechanical polishing aqueous dispersion. Then, the polishing characteristics were evaluated. The results are shown in Table 1.

[Comparative Example 8]
A chemical mechanical polishing aqueous dispersion having a pH of 6.3 was prepared in the same manner as in Example 7 except that polyethyleneimine was added as a cationic surfactant (C) in an amount of 500 ppm based on the total amount of the chemical mechanical polishing aqueous dispersion. Then, the polishing characteristics were evaluated. The results are shown in Table 1.

From the results of the above Examples and Comparative Examples, when the cationic surfactant (C) is not blended (Comparative Example 1), and the blending amount of the cationic surfactant (C) is the total amount of the chemical mechanical polishing aqueous dispersion. On the other hand, when it was less than 0.1 ppm (Comparative Examples 3 and 6), the polishing rate was good, but the number of scratches was poor. Moreover, when the compounding quantity of the cationic surfactant (C) exceeded 100 ppm with respect to the total amount of the chemical mechanical polishing aqueous dispersion, the polishing rate was slow although the number of scratches was small. (Comparative Examples 2, 4, 5, 7, and 8). None of these were found to be suitable for practical use.

  On the other hand, in Examples 1 to 8, both the polishing rate and the number of scratches are extremely good or good, and these chemical mechanical polishing aqueous dispersions are used for the polishing water system used in the step of removing the excess insulating film in the fine element separation step. It was confirmed that the dispersion has very good performance.

  According to the present invention, an excess insulating film can be removed at a good polishing rate, and a substrate having an insulating film with a small number of scratches can be manufactured.

FIG. 1 is a schematic view showing an example of an embodiment of a chemical mechanical polishing method according to the present invention. FIG. 2 is a schematic view showing an example of an object to be polished (for example, a wafer).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Polishing pad 2 Surface plate 3 Pressure head 4 Polishing object 41 Silicon substrate 42 Insulating film (for example, PETEOS film)
43 Insulating film (for example, SiO ₂ film)
44 Stopper layer (eg silicon nitride layer)
45 Ideal surface after polishing 5 Slurry supply section

Claims (2)

An aqueous dispersion for chemical mechanical polishing comprising abrasive grains (A) containing ceria, an anionic water-soluble polymer (B) and a cationic surfactant (C),
The content of the anionic water-soluble polymer (B) is 60 to 600 parts by mass per 100 parts by mass of the abrasive grains (A) containing ceria,
A chemical mechanical polishing aqueous dispersion, wherein the content of the cationic surfactant (C) is 0.1 to 100 ppm based on the entire chemical mechanical polishing aqueous dispersion. A chemical mechanical polishing method comprising removing an excess insulating film in the fine element isolation step using the chemical mechanical polishing aqueous dispersion according to claim 1.

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