Source: https://patents.justia.com/patent/10196542
Timestamp: 2019-10-18 10:53:43
Document Index: 768028726

Matched Legal Cases: ['Application No. 2014', 'Application No. 102112789', 'Application No. 201380026398', 'Application No. 2014', 'Application No. 2013800262597', 'Application No. 2014', 'Application No. 2014', 'Application No. 201380010364', 'Application No. 201180005050', 'Application No. 2012', 'Application No. 201180055799', 'Application No. 201180055798', 'Application No. 201310317864', 'Application No. 201310335723', 'Application No. 102110935', 'Application No. 2014', 'Application No. 201380026857', 'Application No. 2014', 'Application No. 2014', 'Application No. 2013', 'Application No. 102112791', 'Application No. 102112787', 'Application No. 201380026259', 'Application No. 2014', 'Application No. 201310335599']

US Patent for Abrasive, abrasive set, and method for abrading substrate Patent (Patent # 10,196,542 issued February 5, 2019) - Justia Patents Search
Justia Patents PolishesUS Patent for Abrasive, abrasive set, and method for abrading substrate Patent (Patent # 10,196,542)
Oct 21, 2015 - HITACHI CHEMICAL COMPANY, LTD
The present invention relates to a polishing agent, a polishing agent set and a polishing method for a base substrate using the polishing agent or the polishing agent set. In particular, the invention relates to a polishing agent and polishing agent set to be used in a flattening step of a base substrate surface as a production technique for a semiconductor element, and to a polishing method for a base substrate using the polishing agent or the polishing agent set. More specifically, the invention relates to a polishing agent and polishing agent set to be used in a flattening step for a Shallow Trench Isolation (hereunder, “STI”) insulating material, a pre-metal insulating material or an interlayer insulating material, and to a polishing method for a base substrate using the polishing agent or the polishing agent set.
[Patent Literature 1] Japanese Unexamined Patent Application Publication HEI No. 10-106994
[Patent Literature 2] Japanese Unexamined Patent Application Publication HEI No. 08-022970
[Patent Literature 3] Japanese Unexamined Patent Application Publication No. 2009-212378
[Patent Literature 4] International Patent Publication No. WO2002/067309
[Patent Literature 5] Japanese Unexamined Patent Application Publication No. 2006-249129
[Non-Patent Literature 1] Complete Works of Dispersion Technology, Johokiko Co., Ltd., July, 2005, Chapter 3, “Dispersers: Recent development trends and selection criteria”
[In formula (I), m is an integer of 3 or greater.]
[In formula (II), n represents an integer of 2 or greater, and R1, R2 and the multiple R3 each independently represent hydrogen atom, a group represented by general formula (III) below or a group represented by general formula (IV) below. The case where R1, R2 and the multiple R3 are all hydrogen atom is excluded.]
[In formula (III), p represents an integer of 1 or greater.]
[In formula (IV), q represents an integer of 1 or greater.]
Throughout the present specification, “polyglycerin” refers to polyglycerin having a glycerin mean polymerization degree of 3 or greater (polyglycerin that is a trimer or more). Also, throughout the present specification, “diglycerin derivative” refers to a compound having a functional group introduced into diglycerin, and “polyglycerin derivative” refers to a compound having a functional group introduced into polyglycerin that has a glycerin mean polymerization degree of 3 or greater.
The weight-average molecular weight of the glycerin compound is preferably 250 or greater and 10×103 or less. This can further increase the polishing rate for insulating materials while also further improving polishing selectivity for insulating materials with respect to stopper materials.
The abrasive grains contain a hydroxide of a tetravalent metal element. Throughout the present specification, the term “hydroxide of a tetravalent metal element” refers to a compound containing a tetravalent metal (M4+) and at least one hydroxide ion (OH−). The hydroxide of a tetravalent metal element may contain an anion other than a hydroxide ion (for example, a nitrate ion NO3− and sulfate ion SO42−). For example, the hydroxide of a tetravalent metal element may contain an anion (for example, a nitrate ion NO3− and sulfate ion SO42−) bonded to a tetravalent metal element.
The “mean particle diameter” of the abrasive grains is the mean secondary particle size of the abrasive grains. For example, the mean particle diameter of the abrasive grains can be measured for the polishing agent or the slurry of the polishing agent set described hereunder, using an optical diffraction scattering particle size distribution meter (for example, trade name: N5 by Beckman Coulter, Inc. or trade name: Zetasizer 3000HSA by Malvern Instruments, Inc.).
The abrasive grains preferably comprise a hydroxide of a tetravalent metal element and also satisfy at least one of the following conditions (a) and (b). An “aqueous dispersion” having an abrasive grain content adjusted to a prescribed content is a liquid containing a prescribed content of abrasive grains and water.
With regard to the condition (a), the polishing rate can be even further increased by using abrasive grains that produce absorbance of 1.00 or greater for light with a wavelength of 400 nm in an aqueous dispersion having the abrasive grain content adjusted to 1.0 mass %. The reason for this is not fully understood, but the present inventors conjecture as follows. Specifically, it is thought that particles, containing M(OH)aXb composed of a tetravalent metal (M4+), 1 to 3 hydroxide ions (OH−) and 1 to 3 anions (Xc−) (wherein a+b×c=4), are produced as part of the abrasive grains, depending on the production conditions for the hydroxide of a tetravalent metal element (such particles are also “abrasive grains containing a hydroxide of a tetravalent metal element”). In the formula M(OH)aXb, presumably, the electron-withdrawing anion (Xc−) acts to increase the hydroxide ion reactivity, thus the polishing rate increases as the abundance of M(OH)aXb increases. Also, since the particles containing M(OH)aXb absorb light with a wavelength of 400 nm, presumably an increased abundance of M(OH)aXb causes increased absorbance for light with a wavelength of 400 nm, and increases the polishing rate.
Abrasive grains containing a hydroxide of a tetravalent metal element presumably contain not only M(OH)aXb but also M(OH)4, MO2 and the like. The anion (Xc−) may be NO3− and SO42−, for example.
It is possible to confirm that the abrasive grain containing a hydroxide of a tetravalent metal element includes M(OH)aXb by the method of detecting the peak corresponding to the anion (Xc−) with FT-IR ATR method (Fourier transform Infra Red Spectrometer Attenuated Total Reflection method) after thoroughly washing the abrasive grain with purified water. The presence of the anion (Xc−) can be also confirmed by XPS method (X-ray Photoelectron Spectroscopy method).
The absorption peak of M(OH)aXb (for example, M(OH)3X) at a wavelength of 400 nm has been confirmed to be much lower than the absorption peak at a wavelength of 290 nm described below. In this regard, as a result of studying degrees of absorbance using aqueous dispersions with relatively high abrasive grain contents of 1.0 mass %, which allow absorbance to be easily detected as high absorbance, the present inventors have found that the effect of increasing polishing rate is superior when using abrasive grains that produce absorbance of 1.00 or greater for light with a wavelength of 400 nm in the aqueous dispersion. Incidentally, since it is thought that the absorbance for light with a wavelength of 400 nm derives from the abrasive grains, as explained above, it is difficult to obtain the effect of increased polishing rate with a polishing agent containing a substance (such as a pigment component exhibiting a yellow color) that produces absorbance of 1.00 or greater for light with a wavelength of 400 nm, instead of abrasive grains that produce absorbance of 1.00 or greater for light with a wavelength of 400 nm.
With regard to the condition (b), the polishing rate can be even further increased by using abrasive grains that produce absorbance of 1.000 or greater for light with a wavelength of 290 nm in an aqueous dispersion having the abrasive grain content adjusted to 0.0065 mass %. The reason for this is not fully understood, but the present inventors conjecture as follows. Specifically, particles containing M(OH)aXb (for example, M(OH)3X) that are produced depending on the production conditions for the hydroxide of a tetravalent metal element have a calculated absorption peak near a wavelength of 290 nm, and for example, particles composed of Ce4+(OH−)3NO3− have an absorption peak at a wavelength of 290 nm. Consequently, it is believed that the polishing rate is increased in accordance with the increase in absorbance for light with a wavelength of 290 nm due to the increase in the abundance of M(OH)aXb.
Also, hydroxides of the tetravalent metal element (such as M(OH)aXb) tend not to exhibit absorption for light with wavelengths of 450 nm or greater, and especially for light with wavelengths of 450 to 600 nm. Therefore, from the viewpoint of minimizing adverse effects on polishing by the presence of impurities and accomplishing polishing of insulating materials at even more excellent polishing rates, the abrasive grains preferably produce absorbance of 0.010 or less for light with a wavelength of 450 to 600 nm in an aqueous dispersion having the abrasive grain content adjusted to 0.0065 mass % (65 ppm). Specifically, the absorbance preferably does not exceed 0.010 for all light within a wavelength range of 450 to 600 nm in an aqueous dispersion having the abrasive grain content adjusted to 0.0065 mass %. The upper limit for the absorbance for light with a wavelength of 450 to 600 nm is more preferably 0.005 or less and even more preferably 0.001 or less. The lower limit for the absorbance for light with a wavelength of 450 to 600 nm is preferably 0.
In the case of low light transmittance in an aqueous dispersion having an abrasive grain content of 1.0 mass %, the abrasive grains present in the aqueous dispersion presumably have relatively more particles with large particle diameters (hereunder referred to as “coarse particles”). When an additive (such as polyvinyl alcohol (PVA)) is added to a polishing agent containing such abrasive grains, other particles aggregate around the coarse particles as nuclei, as shown in FIG. 1. As a result, the number of abrasive grains acting on the surface to be polished per unit area (the effective abrasive grain number) is reduced, thus the specific surface area of the abrasive grains contacting with the surface to be polished is reduced, whereby presumably reduction in polishing rate occurs.
Conversely, in the case of high light transmittance in an aqueous dispersion having an abrasive grain content of 1.0 mass %, the abrasive grains present in the aqueous dispersion presumably have fewer “coarse particles”. In such cases with a low abundance of coarse particles, as shown in FIG. 2, few coarse particles are available as nuclei for aggregation, and therefore aggregation between abrasive grains is inhibited or the sizes of the aggregated particles are smaller than the aggregated particles shown in FIG. 1, even when an additive (such as polyvinyl alcohol) is added to the polishing agent. As a result, the number of abrasive grains acting on the surface to be polished per unit area (the effective abrasive grain number) is maintained, thus the specific surface area of the abrasive grains contacting with the surface to be polished is maintained, whereby presumably reduction in the polishing rate hardly occur.
Sample solution: Polishing agent 100 μL
Detector: UV-VIS Detector by Hitachi, Ltd., trade name: “L-4200”, wavelength: 400 nm
Integrator: GPC integrator by Hitachi, Ltd., trade name: “D-2500”
Pump: Trade name: “L-7100” by Hitachi, Ltd.
Column: Aqueous HPLC packed column, trade name: “GL-W550S” by Hitachi Chemical Co., Ltd.
Flow rate: 1 mL/min (pressure: approximately 40-50 kg/cm2)
The hydroxide of a tetravalent metal element can be produced by reacting a tetravalent metal element salt (metal salt) with an alkaline source (base). The hydroxide of a tetravalent metal element is preferably produced by mixing a tetravalent metal element salt with an alkali solution (for example, an aqueous alkali solution). This will allow particles with extremely fine particle diameters to be obtained, so that the polishing agent with an even more excellent effect of reducing polishing scratches can be obtained. This method is disclosed in Patent Literature 5, for example. The hydroxide of a tetravalent metal element can be obtained by mixing a metal salt solution of a tetravalent metal element salt (for example, an aqueous metal salt solution) with an alkali solution. When either or both the tetravalent metal element salt and alkaline source is to be supplied to the reaction system in a liquid state, there is no limitation to the means for mixing the liquid mixture. For example, there may be mentioned a method of stirring the liquid mixture using a rod, plate or propeller-shaped stirrer or a stirring blade rotating around a rotating shaft, a method of stirring the liquid mixture by rotating a stirrer in a rotating magnetic field using a magnetic stirrer that transmits mechanical power from outside of the container, a method of stirring the liquid mixture with a pump installed outside of the tank, and a method of stirring the liquid mixture by blowing in pressurized external air with force into the tank. The tetravalent metal element salt used may be a known one without any particular restrictions, and this includes M(NO3)4, M(SO4)2, M(NH4)2(NO3)6, M(NH4)4(SO4)4 (where M represents a rare earth metal element), Zr(SO4)2.4H2O and the like. M is preferably chemically active cerium (Ce).
In order to increase the absorbance for light with a wavelength of 400 nm, the absorbance for light with a wavelength of 290 nm and light transmittance for light with a wavelength of 500 nm, the method for producing the hydroxide of a tetravalent metal element is preferably more “moderate”. Here, “moderate” means a moderate (slow) pH increase when the pH of the reaction system increases as the reaction proceeds. Conversely, in order to decrease the absorbance for light with a wavelength of 400 nm, the absorbance for light with a wavelength of 290 nm and light transmittance for light with a wavelength of 500 nm, the method for producing the hydroxide of a tetravalent metal element is preferably more “intense”. Here, “intense” means an intense (rapid) pH increase when the pH of the reaction system increases as the reaction proceeds. In order to adjust the absorbance and light transmittance values to the prescribed ranges, it is preferred to optimize the method for producing the hydroxide of a tetravalent metal element based on these tendencies. A method of controlling the absorbance and light transmittance will now be explained in greater detail.
The upper limit for the mixing rate is preferably 5.00×10−3 m3/min (5 L/min) or less, more preferably 1.00×10−3 m3/min (1 L/min) or less, even more preferably 5.00×10−4 m3/min (500 mL/min) or less and especially preferably 1.00×10−4 m3/min (100 mL/min) or less, from the viewpoint of further inhibiting rapid reaction while further inhibiting local imbalance of the reaction. The lower limit for the mixing rate is not particularly restricted, but is preferably 1.00×10−7 m3/min (0.1 mL/min) or greater from the viewpoint of productivity.
From the viewpoint of further inhibiting local imbalance of the reaction and obtaining excellent mixing efficiency, the lower limit for the stirring speed is preferably 30 min−1 or greater, more preferably 50 min−1 or greater and even more preferably 80 min−1 or greater. The upper limit for the stirring speed is not particularly restricted, and it will need to be appropriately adjusted depending on the size and shape of the stirring blade, but it is preferably 1000 min−1 or less from the viewpoint of preventing splashing of liquid.
The liquid temperature is, for example, the temperature in the liquid mixture as read from a thermometer set in the liquid mixture, and it is preferably 0° C. to 100° C. The upper limit for the liquid temperature is preferably 100° C. or less, more preferably 60° C. or less, even more preferably 55° C. or less, especially preferably 50° C. or less and extremely preferably 45° C. or less, from the viewpoint of allowing rapid reaction to be inhibited. From the viewpoint of facilitating progression of the reaction, the lower limit for the liquid temperature is preferably 0° C. or greater, more preferably 10° C. or greater and even more preferably 20° C. or greater.
The polishing agent of this embodiment comprises an additive. Here, “additive” refers to a substance that is added to the polishing agent in addition to water and abrasive grains, in order to adjust the polishing properties such as polishing rate and polishing selectivity; the polishing agent properties such as abrasive grain dispersibility and storage stability; and the like.
In formula (I), the structural unit of the [C3H5(OH)O] portion may be, for example, a structural unit represented by any of formulas (Va) to (Vc) below. The compound represented by formula (I) may be a compound having one type from among formulas (Va) to (Vc), or it may be a compound having more than one from among formulas (Va) to (Vc). In a compound having more than one from among formulas (Va) to (Vc), the arrangement of the structural units may be as desired. For example, it may have any desired form such as (a) the form of a block copolymer with the same structural units in continuity, (b) the form of a random copolymer having a structural unit A and a structural unit B arranged in no particular order, or (c) the form of an alternating copolymer having a structural unit A and a structural unit B in an alternating arrangement. An example of compounds represented by formula (I) includes compounds represented by formula (VIa) below and compounds represented by formula (VIb) below.
[In formula (VIa), r1 represents an integer of 0 or greater, s1 represents an integer of 0 or greater, and r1+s1 is an integer of 3 or greater.]
[In formula (VIb), r2 represents an integer of 0 or greater, s2 represents an integer of 0 or greater, and r2+s2 is an integer of 3 or greater.]
The compound represented by formula (VIa) may lack one of the [CH2CH(OH)CH2O] portion and [CH2CH(CH2OH)O] portion (i.e. r1=0 or s1=0 may be satisfied). The compound represented by formula (VIb) may lack one of the [CH2CH(OH)CH2O] portion and [CH(CH2OH)CH2O] portion (i.e. r2=0 or s2=0 may be satisfied). The arrangement of the structural unit in the curly brackets in formula (VIa) and formula (VIb) (that is, the [CH2CH(OH)CH2O] portion and [CH2CH(CH2OH)O] portion in formula (VIa), and the [CH2CH(OH)CH2O] portion and [CH(CH2OH)CH2O] portion in formula (VIb)) may be as desired.
The “HLB value” is a value representing the hydrophilic/lipophilic balance of a compound. The HLB value can be determined by calculation even when the type of hydrophobic group, the type of hydrophilic group, the copolymerization ratio or the like are different in a single compound.
Several methods have been proposed for calculating the HLB value. For example, the HLB value is calculated by the Griffin method, represented by the following formula.
HLB value=20×(total molecular weight of hydrophilic portion)/(entire molecular weight)
An example of hydrophilic group includes hydroxyl group, glyceryl group, oxyethylene group, oxypropylene group, hydroxypropyl group, carboxyl group and sulfonic acid group. For example, the compound represented by formula (II) has an R1 group, an OR2 group and an OC3H5OR3 group. R1, R2 and R3 are all hydrophilic groups, and the OR2 group and OC3H5OR3 group are hydrophilic group portions. Thus, the HLB value of a compound represented by formula (II) is calculated to be about 20.0.
The HLB value of a glycerin compound in a polishing agent can be determined by separation of the glycerin compound from the polishing agent using centrifugation, chromatography, filtration, distillation or the like, followed by concentration or the like if necessary, and identification of the structure of the compound using 13C-NMR, 1H-NMR, GPC, MALDI-MS (Matrix Assisted Laser Desorption/Ionization-Mass Spectrometry) or the like. For example, the proportion of structural units or the like can be determined from the 1H-NMR spectrum. Also, the proportion of structural units and the terminal structure can be identified from the MALDI-MS spectrum. In addition, the copolymerization form of the structural units or the like can be analyzed from the 13C-NMR spectrum.
The upper limit for the weight-average molecular weight of the first additive is not particularly restricted, but from the viewpoint of workability and foamability, it is preferably 10×103 or less, more preferably 5.0×103 or less, even more preferably 3.0×103 or less and especially preferably 2.0×103 or less. When the first additive is a polyglycerin derivative or diglycerin derivative, the weight-average molecular weight of the first additive is more preferably 5.0×103 or less, even more preferably 3.0×103 or less and especially preferably 2.0×103 or less, from the viewpoint of avoiding reduced polishing rate due to overly excessive molecular weight of the functional groups in the derivative. The lower limit for the weight-average molecular weight of the first additive is preferably 250 or greater, more preferably 400 or greater and even more preferably 500 or greater, from the viewpoint of further increasing the polishing rate for insulating materials. When the first additive is polyglycerin, it is preferably 250 or greater, more preferably 400 or greater, even more preferably 500 or greater, especially preferably 750 or greater, very preferably 1.0×103 or greater and extremely preferably 1.2×103 or greater, from the viewpoint of further increasing the polishing rate for insulating materials. From these viewpoints, the weight-average molecular weight of the first additive is more preferably 250 or greater and 10×103 or less.
An amino acid has an effect of improving the dispersibility of the abrasive grains containing the hydroxide of a tetravalent metal element, and further increasing the polishing rate for insulating materials. An example of the amino acid includes arginine, lysine, aspartic acid, glutamic acid, asparagine, glutamine, histidine, proline, tyrosine, tryptophan, serine, threonine, glycine, alanine, β-alanine, methionine, cysteine, phenylalanine, leucine, valine and isoleucine. An amino acid has a carboxyl group, but it is defined as one different from a carboxylic acid.
The polishing agent of this embodiment may comprise a water-soluble polymer, for the purpose of adjusting the polishing properties such as flatness, in-plane uniformity, polishing selectivity for silicon oxide with respect to silicon nitride (polishing rate for silicon oxide/polishing rate for silicon nitride), and polishing selectivity for silicon oxide with respect to polysilicon (polishing rate for silicon oxide/polishing rate for polysilicon). A “water-soluble polymer” is defined as a polymer dissolved to at least 0.1 g in 100 g of water. The first additive is not included in the term “water-soluble polymer”.
The weight-average molecular weight of the water-soluble polymer is preferably 100 or greater, more preferably 300 or greater, even more preferably 500 or greater and especially preferably 1.0×103 or greater, from the viewpoint of further improving the polishing selectivity for insulating materials with respect to stopper materials. The weight-average molecular weight of the water-soluble polymer is preferably 300×103 or less, more preferably 100×103 or less, even more preferably 50×103 or less and especially preferably 30×103 or less, from the viewpoint of further improving the polishing selectivity for insulating materials with respect to stopper materials. From these viewpoints, the weight-average molecular weight of the water-soluble polymer is more preferably 100 or greater and 300×103 or less. The weight-average molecular weight of the water-soluble polymer can be measured by the same method as for the weight-average molecular weight of the first additive.
The lower limit for the pH (25° C.) of the polishing agent of this embodiment is preferably 3.0 or greater, more preferably 4.0 or greater, even more preferably 4.5 or greater and especially preferably 5.0 or greater, from the viewpoint of further increasing the polishing rate for insulating materials. Also, the upper limit for the pH is preferably 12.0 or less, more preferably 11.0 or less, even more preferably 10.0 or less, especially preferably 9.0 or less and extremely preferably 8.0 or less, from the viewpoint of further increasing the polishing rate for insulating materials. From these viewpoints, the pH of the polishing agent is more preferably 3.0 or greater and 12.0 or less.
The pH of the polishing agent of this embodiment can be measured with a pH meter (for example, a Model PHL-40 by DKK Corp.). Specifically, for example, after 2-point calibration of a pH meter using phthalate pH buffer solution (pH 4.01) and a neutral phosphate pH buffer solution (pH 6.86) as standard buffer solutions, the pH meter electrode was placed in the polishing agent, and then the value was measured after at least 2 minutes passed for stabilization. Here, the liquid temperature of the standard buffer solution and polishing agent are both 25° C.
The polishing method for a base substrate of this embodiment may comprise a polishing step of polishing the surface to be polished of a base substrate using the one-pack polishing agent, or it may comprise a polishing step of polishing the surface to be polished of a base substrate using the polishing agent obtained by mixing the slurry and the additive solution of the polishing agent set. Also, the polishing method for a base substrate of this embodiment may be a polishing method for a base substrate having an insulating material and polysilicon, and for example, it may comprise a polishing step of selectively polishing the insulating material with respect to the polysilicon using the one-pack polishing agent, or the polishing agent obtained by mixing the slurry and the additive solution of the polishing agent set. In this case, the base substrate may have a member comprising the insulating material and a member comprising the polysilicon, for example. “Selectively polish material A with respect to material B” means that the polishing rate for material A is higher than the polishing rate for material B under the same polishing conditions. More specifically, it means, for example, that material A is polished with the polishing rate ratio of the polishing rate for material A with respect to the polishing rate for material B being 10 or greater.
Silicon oxide is obtained using low-pressure CVD method, for example, by thermal reaction of monosilane (SiH4) and oxygen (O2). Silicon oxide is also obtained using normal-pressure CVD method, for example, by thermal reaction of tetraethoxysilane (Si(OC2H5)4) and ozone (O3). As another example, silicon oxide is likewise obtained by plasma reaction of tetraethoxysilane and oxygen.
In order to stabilize the materials such as silicon oxide, polysilicon and silicon nitride that are obtained by such methods, heat treatment may be carried out at a temperature of 200° C. to 1000° C. as necessary. The silicon oxide obtained by such methods may also contain small amounts of boron (B), phosphorus (P), carbon (C) or the like in order to increase the embedding property.
There are no particular restrictions on the polishing conditions, but the rotational speed of the polishing platen is preferably 200 min−1 or less so that the semiconductor substrate does not fly out, the polishing pressure (machining load) on the semiconductor substrate is preferably 100 kPa or less from the viewpoint of adequately inhibiting the generation of polishing scratches. The polishing agent is preferably continuously supplied to the abrasive pad with a pump or the like during polishing. The amount supplied is not particularly restricted, but preferably the surface of the abrasive pad is covered by the polishing agent at all times.
175 g of Ce(NH4)2(NO3)6 was dissolved in 8000 g of purified water to obtain a solution. Next, while stirring the solution, 750 g of an aqueous imidazole solution (10 mass % aqueous solution, 1.47 mol/L) was added dropwise at a mixing rate of 5 mL/min to obtain a dispersion (yellowish white) containing 29 g of particles of hydroxide of cerium. The particles of hydroxide of cerium were synthesized at a temperature of 25° C. and a stirring speed of 400 min−1. The stirring was carried out using a 3-blade pitch paddle with a total blade section length of 5 cm.
The obtained dispersion of particles of hydroxide of cerium was subjected to solid-liquid separation by centrifugal separation (4000 min−1, 5 minutes), and a precipitate at a solid content of approximately 10% was taken out. Water was mixed with the precipitate obtained by solid-liquid separation so that a cerium hydroxide content was adjusted to 1.0 mass %, and an ultrasonic cleaner was used to disperse the particles in the water to prepare a cerium hydroxide slurry storage solution.
Upon measurement of the mean particle diameter of the particles of hydroxide of cerium in the cerium hydroxide slurry storage solution using an N5, trade name of Beckman Coulter, Inc., a value of 25 nm was obtained. The measuring method was as follows. First, approximately 1 mL of measuring sample (aqueous dispersion) containing 1.0 mass % of particles of hydroxide of cerium was placed in a 1 cm-square cell, and the cell was set in the N5. Measurement was performed at 25° C. with the refractive index of the measuring sample adjusted to 1.333 and the viscosity of the measuring sample adjusted to 0.887 mPa·s, and the value indicated as Unimodal Size Mean was read off.
A suitable amount of the cerium hydroxide slurry storage solution was taken and vacuum dried to isolate the abrasive grains, and then thoroughly washed with purified water to obtain a sample. The obtained sample was measured by FT-IR ATR, and a peak for nitrate ion (NO3−) was observed in addition to a peak for hydroxide ion (OH−). The same sample was measured by XPS (N-XPS) for nitrogen, and a peak for nitrate ion was observed while no peak for NH4+ was observed. These results confirmed that the abrasive grains in the cerium hydroxide slurry storage solution at least partially contain particles having nitrate ion bonded to cerium element. Also, since it also at least partially contains particles having hydroxide ion bonded to cerium element, this confirmed that the abrasive grains contained hydroxide of cerium.
SC-E450 (diglycerin polyether (polyoxyethylene diglyceryl ether) by Sakamoto Yakuhin Kogyo Co., Ltd., compound satisfying the formula (II) (R1: group represented by the formula (III), R2: hydrogen atom, R3: hydrogen atom, n=2, p=6)
SC-E2000 (diglycerin polyether (polyoxyethylene diglyceryl ether) by Sakamoto Yakuhin Kogyo Co., Ltd., compound satisfying the formula (II) (R1: group represented by the formula (III), R2: hydrogen atom, R3: hydrogen atom, n=2, p=40)
SC-E4500 (diglycerin polyether (polyoxyethylene diglyceryl ether) by Sakamoto Yakuhin Kogyo Co., Ltd., compound satisfying the formula (II) (R1: group represented by the formula (III), R2: hydrogen atom, R3: hydrogen atom, n=2, p=90)
Measuring temperature: 25±5° C.
Measuring method: After 2-point calibration using standard buffer solution (phthalate pH buffer solution: pH: 4.01 (25° C.), neutral phosphate pH buffer solution: pH 6.86 (25° C.)), the electrode was placed in the CMP polishing agent, and then the pH was measured with the measuring apparatus described above after at least 2 minutes passed for stabilization.
The mean particle diameter of the particles of hydroxide of cerium in the CMP polishing agent was measured using an N5, trade name of Beckman Coulter, Inc. The measuring method was as follows. First, approximately 1 mL of the CMP polishing agent was placed in a 1 cm-square cell and the cell was set in the N5. Measurement was performed at 25° C. with the refractive index of the measuring sample adjusted to 1.333 and the viscosity of the measuring sample adjusted to 0.887 mPa·s, and the value indicated as Unimodal Size Mean was read off.
Substrates to be polished: A substrate having a 1 μm-thick silicon oxide film formed on a silicon substrate by plasma CVD method, and a substrate having a 0.2 μm-thick polysilicon film formed on a silicon substrate by CVD method.
The polishing rates for films to be polished (silicon oxide film and polysilicon film) that had been polished and cleaned under the conditions described above (silicon oxide polishing rate: SiO2RR, polysilicon polishing rate: p-SiRR) were determined by the following formula. The difference in film thickness of the film to be polished before and after polishing was determined using a light-interference film thickness meter (trade name: F80 by Filmetrics Japan, Inc.).
(Polishing rate: RR)=(Film thickness difference of film to be polished before and after polishing (nm))/polishing time (min))
Also, a polished substrate (blanket wafer substrate having a silicon oxide film) that had been polished and cleaned under the conditions described above was dipped for 15 seconds in an aqueous solution of 0.5 mass % hydrogen fluoride and washed with water for 60 seconds. Next, the surface of the polished film was cleaned for 1 minute using a polyvinyl alcohol brush while supplying water, and was dried. Complus by Applied Materials, Inc. was used to detect defects of 0.2 μm or greater on the surface of the polished film. Also, upon observation of the surface of the polished film using the defect detection coordinates obtained by the Complus, and using an SEM Vision by Applied Materials, Inc., the number of polishing scratches of 0.2 μm or greater at the surface of the polished film was about 0 to 3 (per wafer) in both the examples and the comparative examples, indicating that generation of polishing scratches was adequately inhibited.
Table 1 shows the silicon oxide polishing rate (SiO2RR), the polysilicon polishing rate (p-SiRR), the polishing selectivity ratio, i.e. silicon oxide polishing rate/polysilicon polishing rate, and the like, for Examples 1 to 8 and Comparative Examples 1 to 7. The HLB value of the additives of Examples 1 to 8 was 20.0. The polyglycerol fatty acid ester of Comparative Example 7 (polyglycerin mean polymerization degree: 4, the HLB value: 12.2) is not a compound represented by formula (I) or (II), since it is a fatty acid ester.
TABLE 1 Additive Weight-average SiO2RR p-SiRR Polishing selectivity ratio (mass %) molecular weight (nm/min) (nm/min) (SiO2RR/p-SiRR)
Example 1 Polyglycerin tetramer 300 200 19 11 (0.5) Example 2 Polyglycerin hexamer 420 225 21 11 (0.5) Example 3 Polyglycerin decamer 680 280 24 12 (0.5) Example 4 Polyglycerin icosamer 1300 315 22 14 (0.5) Example 5 SC-E450 450 230 17 14 (0.5) Example 6 SC-E2000 2000 210 15 14 (0.5) Example 7 SC-E4500 4500 195 16 12 (0.5) Example 8 Polyglycerin icosamer 1300 270 23 12 (0.05) Comparative None — 160 100 1.6 Example 1 Comparative Glycerin 92 115 — — Example 2 (0.05) Comparative Diglycerin 166 165 — — Example 3 (0.05) Comparative Polyvinyl alcohol 10000 180 — — Example 4 (0.05) Comparative α-cyclodextrin 972 180 — — Example 5 (0.05) Comparative Polyoxyethylene sorbitan 346 130 — — Example 6 monolaurate (0.05) Comparative Polyglycerin fatty acid ester 492 162 23 7.0 Example 7 (0.05)
1. A polishing agent comprising: in formula (I), m is an integer of 3 or greater.
abrasive grains containing a hydroxide of tetravalent cerium, wherein the abrasive grains produce absorbance of 1.000 or greater for light with a wavelength of 290 nm in an aqueous dispersion having the abrasive grain content adjusted to 0.0065 mass %, and
at least one glycerin compound represented by general formula (I) below:
2. A polishing agent comprising:
at least one glycerin compound selected from the group consisting of polyglycerin, diglycerin derivatives and polyglycerin derivatives, and
HLB value of the at least one glycerin compound being 19.8 to 20.0.
8. The polishing agent according to claim 1, wherein a weight-average molecular weight of the at least one glycerin compound is 250 or greater and 10×103 or less.
12. A polishing agent set comprising constituent components of the polishing agent according to claim 1 separately stored as a first liquid and a second liquid,
the first liquid containing the abrasive grains and water, and
the second liquid containing the at least one glycerin compound and water.
15. A polishing method for a base substrate having an insulating material and polysilicon,
the polishing method comprising a step of selectively polishing the insulating material with respect to the polysilicon using the polishing agent according to claim 1.
16. A polishing method for a base substrate having an insulating material and polysilicon,
the polishing method comprising a step of selectively polishing the insulating material with respect to the polysilicon using a polishing agent obtained by mixing the first liquid and the second liquid of the polishing agent set according to claim 12.
20. The polishing agent according to claim 2, wherein a weight-average molecular weight of the at least one glycerin compound is 250 or greater and 10×103 or less.
24. A polishing agent set comprising constituent components of the polishing agent according to claim 2 separately stored as a first liquid and a second liquid,
27. A polishing method for a base substrate having an insulating material and polysilicon,
the polishing method comprising a step of selectively polishing the insulating material with respect to the polysilicon using the polishing agent according to claim 2.
28. A polishing method for a base substrate having an insulating material and polysilicon,
the polishing method comprising a step of selectively polishing the insulating material with respect to the polysilicon using a polishing agent obtained by mixing the first liquid and the second liquid of the polishing agent set according to claim 24.
29. A polishing agent comprising: in formula (I), m is an integer of 3 or greater.
abrasive grains containing a hydroxide of tetravalent cerium, wherein the abrasive grains produce light transmittance of 50%/cm or greater for light with a wavelength of 500 nm in an aqueous dispersion having the abrasive grain content adjusted to 1.0 mass %, and
33. The polishing agent according to claim 29, wherein a weight-average molecular weight of the at least one glycerin compound is 250 or greater and 10×103 or less.
37. A polishing agent set comprising constituent components of the polishing agent according to claim 29 separately stored as a first liquid and a second liquid,
40. A polishing method for a base substrate having an insulating material and polysilicon,
the polishing method comprising a step of selectively polishing the insulating material with respect to the polysilicon using the polishing agent according to claim 29.
41. A polishing method for a base substrate having an insulating material and polysilicon,
the polishing method comprising a step of selectively polishing the insulating material with respect to the polysilicon using a polishing agent obtained by mixing the first liquid and the second liquid of the polishing agent set according to claim 37.
42. A polishing agent comprising:
48. The polishing agent according to claim 42, wherein a weight-average molecular weight of the at least one glycerin compound is 250 or greater and 10×103 or less.
52. A polishing agent set comprising constituent components of the polishing agent according to claim 42 separately stored as a first liquid and a second liquid,
55. A polishing method for a base substrate having an insulating material and polysilicon,
the polishing method comprising a step of selectively polishing the insulating material with respect to the polysilicon using the polishing agent according to claim 42.
56. A polishing method for a base substrate having an insulating material and polysilicon,
the polishing method comprising a step of selectively polishing the insulating material with respect to the polysilicon using a polishing agent obtained by mixing the first liquid and the second liquid of the polishing agent set according to claim 52.
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Patent Publication Number: 20160040041
Inventors: Hisataka Minami (Hitachi), Toshiaki Akutsu (Hitachi), Tomohiro Iwano (Hitachi), Koji Fujisaki (Kokubunji)
Application Number: 14/918,834
International Classification: C09K 13/00 (20060101); C09G 1/02 (20060101); H01L 21/3105 (20060101); C09K 3/14 (20060101); H01L 21/306 (20060101); H01L 21/762 (20060101);