JP2003017445A - Cmp abrasive and method for polishing substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide abrasives, capable of reducing polishing damages by improving a particle removal performance in cleaning after polishing, and to provide a method for polishing a substrate using the abrasives. SOLUTION: The CMP abrasives comprise cerium oxide particles, having a complex-forming agent concentration range of cerium of 0.1 wt.% to 10.0 wt.%, a water-soluble polymer, a complex-forming agent with the cerium and water. The method for polishing the substrate comprises the steps of supplying the CMP abrasives containing the cerium oxide particles, the water-soluble polymer, the complex-forming agent with the cerium and the water to a polishing pad on a polishing platen, contacting the pad with a surface to be polished of the substrate of the semiconductor chip formed with a silicon oxide insulating film, making the surface to be polished and the pad to move relatively, and polishing the surface of the substrate via the cerium oxide particles complex formed on the surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CMP (Chemical Mechanical) used in a semiconductor element manufacturing process, such as a flattening process of a substrate surface, particularly an interlayer insulating film, a shallow trench isolation forming process, or the like.
Polishing) Abrasive and substrate polishing method.

[0002]

2. Description of the Related Art Various microfabrication techniques have been researched and developed in order to increase the packaging density in the field of ultra-large scale integrated circuits, and the design rule has already been in the order of sub-half micron. The CMP polishing technique is one of the techniques for satisfying such strict miniaturization requirements.
This technique enables miniaturization by completely flattening the layer to be exposed in the manufacturing process of the semiconductor device and can improve the yield, so that, for example,
This is a technique required when flattening the interlayer insulating film and separating shallow trenches.

Conventionally, LOCO is used for element isolation in an integrated circuit.
Although the S (silicon local oxidation) method has been used, the shallow trench isolation method has been used in recent years in order to narrow the element isolation width. In the shallow trench isolation method, CMP is indispensable to remove the excess silicon oxide film formed on the wafer substrate, and a silicon nitride film is formed as a stopper under the silicon oxide film to stop polishing. It is common to

In the process of manufacturing a semiconductor device, plasma-CVD (Chemical Vapor Depos) is used.
CMP for planarizing a silicon oxide insulating film and the like formed by a method such as an ionization method, a chemical vapor deposition method) or a low pressure-CVD method.
As the polishing agent, conventionally, an alkaline silica-based polishing agent having fumed silica as polishing particles and having a pH of more than 9 has been widely used. On the other hand, an abrasive containing cerium oxide as abrasive particles, which has been frequently used as a glass surface abrasive for photomasks, lenses and the like, has recently attracted attention as a CMP abrasive. This technique is disclosed in, for example, Japanese Patent Laid-Open No. 5-326.
It is disclosed in Japanese Patent Publication No. 469. Cerium oxide-based abrasives are superior to silica-based abrasives in that they have a faster polishing rate for silicon oxide films and comparatively less polishing scratches, so various application studies have been conducted, and some of them have been commercialized as semiconductor abrasives. It is supposed to be done. This technique is disclosed in, for example, Japanese Patent Laid-Open No. 9-270402.

In recent years, as the number of layers of semiconductor elements has increased and the resolution has increased, further improvement in the yield and throughput of semiconductor elements has been demanded. Along with this, even with respect to the CMP process using an abrasive, polishing scratch-free and higher-speed polishing is desired. Examples of methods for further reducing polishing scratches in the CMP process using a cerium oxide abrasive include a method for improving the polishing pressure or the number of rotations of the platen, and an method for improving the abrasive such as reducing the concentration or density of abrasive grains. However, there is a problem in that the polishing rate is lowered regardless of which method is used.

[0006]

The inventions according to claims 1 to 4 improve the particle removal performance in the cleaning after polishing,
The present invention provides an abrasive having a high polishing rate and high flatness and capable of reducing polishing scratches. The invention according to claim 5 improves particle removal performance in cleaning after polishing, has a high polishing rate and high flatness, and can reduce polishing scratches, and is excellent in yield and workability. is there.

[0007]

According to the present invention, cerium oxide particles, a water-soluble polymer, a complexing agent with cerium and water, and the concentration of the complexing agent with cerium are 0.1% by weight or more and 10.
It relates to a CMP abrasive which is 0% by weight or less. Further, in the present invention, the complexing agent is represented by the general formula (I).

[Chemical 2] (In the formula, R ¹ and R ² represent a substituted or unsubstituted alkyl group, and R ³ represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms), which is a β-diketone. Of CMP abrasives. The present invention also relates to the above CMP abrasive, wherein the complexing agent is acetylacetone. The present invention also relates to any of the above CMP abrasives, wherein the water-soluble polymer is at least one selected from the group consisting of water-soluble anionic surfactants and water-soluble nonionic surfactants. The present invention also provides a semiconductor chip on which a silicon oxide insulating film is formed by supplying a CMP abrasive containing cerium oxide particles, a water-soluble polymer, a complexing agent with cerium and water to a polishing pad on a polishing platen. The present invention relates to a method for polishing a substrate, which comprises bringing the surface to be polished into relative contact with the surface to be polished of the substrate and moving the polishing pad relatively to polish the surface of the substrate through the cerium oxide particles complexed on the surface. The complex formation of the β-diketone represented by the general formula (I) with the cerium particles is represented by the general formula (II).

[Chemical 3] (In the formula, R ¹ , R ² and R ³ have the same meanings as in formula (I)). By complexing the surface of the cerium oxide particles in this manner, the surface of the cerium particles is covered with the hydrophobic organic functional group, so that the interaction with the film having a hydrophilic metal such as silicon oxide on the surface is reduced, It is presumed that the effect of preventing the cerium oxide particles from adhering to the surface of the silicon oxide film is exhibited.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The cerium oxide particles in the present invention are obtained by calcining or oxidizing a cerium compound such as carbonate, nitrate, sulfate and oxalate. In the examples of the present invention, firing or oxidation with hydrogen peroxide or the like can be used as a method for producing the cerium oxide powder. The firing temperature is preferably 350 ° C or higher and 900 ° C or lower.

Since the cerium oxide particles produced by the above method are agglomerated, it is preferable to mechanically grind them. As the crushing method, a dry crushing method using a jet mill or a wet crushing method using a planetary bead mill is preferable. A jet mill is, for example, a collection of chemical industry papers Vol. 6 No. 5 (19
80) pp. 527-532.

The CMP abrasive is obtained by washing the cerium oxide particles synthesized by the above method and dispersing the composition containing a water-soluble polymer, a cerium complex-forming agent, water and, if necessary, a dispersant. Obtained by For washing, a method in which solid-liquid separation is repeated several times by centrifugation or the like can be used.

The pH of the CMP abrasive is preferably 3 or more and 9 or less, and more preferably 5 or more and 8 or less. When the pH is less than 3, the chemical action becomes small and the polishing rate is lowered. When the pH is higher than 9, the particles tend to aggregate to reduce the contact area with the film to be polished and the polishing rate to decrease. Further, since it is used for polishing semiconductor chips, it is preferable to keep the content of alkali metals and halogens in the cerium oxide particles to 10 ppm or less.

It is generally considered that the cerium oxide particles dispersed in water are not completely separated one by one, and the measured value of the particle diameter of cerium oxide dispersed in water is in a powder state. It is larger than the primary particle size measurement value obtained by using a method such as SEM photography.

The secondary particle size of cerium oxide dispersed in water is preferably 1 nm or more and 300 nm or less.
If the secondary particle diameter is smaller than 1 nm, the effect of the abrasive grains on the film to be polished is reduced, and the polishing rate is reduced. When the secondary particle diameter is larger than 300 nm, the contact area with the film to be polished becomes small and the polishing rate tends to decrease. The particle size is determined by the photon correlation method (for example, Zetasizer 300 manufactured by Malvern Instruments Ltd.).
0HS).

The primary particle diameter of cerium oxide is 0n.
It is necessary to be larger than m and 300 nm or less. When the primary particle size is 0 nm, the silicon oxide film is not polished at all.
If the crystallite size is larger than 300 nm, the secondary particle size will be larger than 300 nm and the polishing rate will decrease. The concentration of the cerium oxide particles is not limited, but is preferably in the range of 0.5% by weight or more and 20% by weight or less from the viewpoint of easy handling of the dispersion liquid.

As the water-soluble polymer, polyvinyl sulfonic acid, polymethacrylic acid, polystyrene sulfonic acid, polyacrylic acid, polyacrylic acid derivative, poly (4-vinylpyridinium salt), poly (1 (3-sulfonyl) -2
-Vinylpyridinium betaine-co-p-styrene sulfonic acid), polyvinyl alcohol derivative, polyacrolein, poly (vinyl acetate-co-methyl methacrylate), poly (styrene-co-maleic anhydride), poly (olefin-co- Maleic anhydride), polyacrylamide partial hydrolyzate, poly (acrylamide-co-
Acrylic acid), alginic acid, polymethyl acrylate, polymethyl methacrylate, and water-soluble anionic surfactants such as ammonium salts, amine salts or potassium salts of polyacrylic acid or polymethacrylic acid; water-soluble polyvinylpyrrolidone, etc. At least one selected from nonionic surfactants can be used, and preferably,
Polymethacrylic acid, polyacrylic acid, polyvinyl alcohol derivative, polyacrylamide partial hydrolyzate, poly (acrylamide-co-acrylic acid), ammonium salt of polyacrylic acid or polymethacrylic acid, and amine salt can be used. Here, the amine salt is N,
Examples thereof include salts with N-dimethylaminoethanol. The weight average molecular weight of the water-soluble polymer (value measured by GPC and converted into standard polystyrene) is 1,000 to 1
0,000 is preferred.

The ratio of the number of moles of the monomer unit of the water-soluble polymer / the number of moles of the water-soluble polymer and the amine forming a salt is not particularly limited, but since the pH of the polishing agent must be 3 or more and 9 or less,
It is preferably 10/7 or more and 10/14 or less. The amount of the water-soluble polymer is 1 to the cerium oxide particles.
It is necessary to mix with the CMP polishing agent so that the amount is 3 times by weight. If it is less than 1 times by weight, the effect of the water-soluble polymer is weakened and the flattening property is deteriorated, and if it exceeds 3 times by weight, the polishing rate tends to be low. Further, the concentration of the water-soluble polymer is preferably 1 to 5 weight from the viewpoint of handleability, mixing workability and the like.

The complexing agent with cerium is not particularly limited as long as it can form a complex with cerium, and examples thereof include α-diketone and general formula (I).

[Chemical 4] (In the formula, R ¹ and R ² represent a substituted or unsubstituted alkyl group, and R ³ represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms). At least one selected from diketones such as diketone, diamines such as ethylenediamine and ethylenediaminetetraacetic acid can be used, and β-diketone is preferable from the viewpoint of high complex forming ability.

In the general formula (I), R ¹ and R ² each represent a substituted or unsubstituted alkyl group, and in consideration of handling as an aqueous polishing agent solution, the number of carbon atoms which becomes more polar and hydrophilic is 1 to 3. Is more preferable in terms of high solubility in water, and a methyl group is particularly preferable. Further, R ³ represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms, and in view of handling as an aqueous polishing agent solution, a hydrogen atom or a methyl group is more preferable, and a hydrogen atom is particularly preferable. preferable. That is, R ¹ and R ² are methyl groups and R ³ is H, 2,
4-Pentanedione (conventional name: acetylacetone) is particularly preferred. The complex formation of the β-diketone represented by the general formula (I) with the cerium particles is represented by the general formula (II).

[Chemical 5] (In the formula, R ¹ , R ² and R 3 have the same meanings as in formula (I)). By complexing the surface of the cerium oxide particles in this manner, the surface of the cerium particles is covered with the hydrophobic organic functional group, so that the interaction with the film having a hydrophilic metal such as silicon oxide on the surface is reduced, It is presumed that the effect of preventing the cerium oxide particles from adhering to the surface of the silicon oxide film is exhibited.

The concentration of the above complex-forming agent is 0.1% by weight from the viewpoint of handleability, mixing workability, etc. in consideration of solubility in water.
It is necessary to be 10% by weight or less and more preferably 0.5% by weight or more and 2% by weight or less. If it is less than 0.1% by weight, the amount of cerium added is insufficient, and the desired effect of reducing polishing scratches tends not to be obtained. If it is more than 10% by weight, the solubility in water may decrease.

As the CMP abrasive, a composition in which a dispersant is added to the abrasive as necessary to disperse the composition can be used. As the dispersant, in addition to the above-mentioned water-soluble polymer, at least one selected from water-soluble anionic dispersants, water-soluble nonionic dispersants, water-soluble cationic dispersants, and water-soluble amphoteric dispersants. It is possible to use two or more dispersants including

Examples of the water-soluble anionic dispersant include lauryl sulfate triethanolamine, ammonium lauryl sulfate, polyoxyethylene alkyl ether sulfate triethanolamine, and the like. Anionic water-soluble polymers described later are used. Good.

Examples of the water-soluble nonionic dispersant include polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene higher alcohol ether, polyoxyethylene octyl. Phenyl ether, polyoxyethylene nonylphenyl ether, polyoxyalkylene alkyl ether, polyoxyethylene derivative, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tri Stearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate, tetrao Inoxy acid polyoxyethylene sorbit, polyethylene glycol monolaurate, polyethylene glycol monostearate, polyethylene glycol distearate, polyethylene glycol monooleate, polyoxyethylene alkylamine, polyoxyethylene hydrogenated castor oil, alkyl alkanolamide, etc. To be

Examples of the water-soluble cationic dispersant include coconut amine acetate and stearyl amine acetate, and examples of the water-soluble amphoteric dispersant include lauryl betaine, stearyl betaine, lauryl dimethylamine oxide, and 2 -Alkyl-N-carboxymethyl-N-hydroxyethyl imidazolinium betaine and the like can be mentioned.

The amount of these dispersants added is 0.01 parts by weight or more and 2.0 parts by weight or more with respect to 100 parts by weight of the cerium oxide particles in view of dispersibility and prevention of sedimentation, and the relationship between polishing scratches and the amount of the dispersants added. The following range is preferable. As a method for dispersing these cerium oxide particles in water, a homogenizer, an ultrasonic disperser, a wet ball mill, or the like can be used in addition to the usual dispersion treatment using a stirrer.

As a method for producing an inorganic insulating film to be polished with a CMP polishing agent, a constant pressure CVD method, a plasma CVD method and the like can be mentioned.

Silicon oxide insulating film formation by constant pressure CVD method
Is a monosilane as a Si source: SiH _Four, As an oxygen source
Oxygen: O_TwoTo use. This SiH_Four-O_TwoSystem oxidation reaction
Obtained by performing at a low temperature of about 400 ° C or less
It Phosphorus for surface flattening by high temperature reflow:
When doping P, SiH_Four-O_Two-PH_ThreeAntithesis
It is preferable to use a reactive gas.

The plasma CVD method has an advantage that a chemical reaction that requires a high temperature under normal thermal equilibrium can be performed at a low temperature. There are two types of plasma generation methods, capacitive coupling type and inductive coupling type.
One is. As the reaction gas, Si as the Si source
H _{4, SiH 4} -N ₂ O-based gas and _{TEOS-O 2} based gas using tetraethoxysilane (TEOS) to Si source using _{N 2} O as oxygen source (TEOS-plasma CVD
Law). The substrate temperature is preferably 250 ° C. to 400 ° C., and the reaction pressure is preferably 67 to 400 Pa. Elements such as phosphorus and boron may be doped in the silicon oxide insulating film.

Similarly, for forming a silicon nitride film by the low pressure CVD method, dichlorosilane: SiH ₂ Cl ₂ as a Si source,
Ammonia: NH ₃ is used as a nitrogen source. This SiH
The ₂ Cl ₂ -NH ₃ based oxidation reaction can be obtained by performed at a high temperature of 900 ° C.. In the plasma CVD method, SiH ₄ − using SiH ₄ as a Si source and NH ₃ as a nitrogen source is used.
NH ₃ based gas may be used. Substrate temperature is 300-400
C is preferred.

As the substrate, as shown in FIGS. 1A and 1B, a semiconductor substrate, that is, a semiconductor substrate at a stage where a circuit element and a wiring pattern are formed, a semiconductor substrate at a stage where a circuit element is formed, and the like. A substrate having a silicon oxide film or a silicon oxide film and a silicon nitride film formed thereon can be used. By polishing the silicon oxide film layer formed on such a semiconductor substrate with the above-mentioned polishing agent, unevenness on the surface of the silicon oxide film layer is eliminated, and a smooth surface is formed over the entire surface of the semiconductor substrate.

Specifically, a CMP abrasive containing cerium oxide particles, a water-soluble polymer, a complexing agent with cerium, and water was supplied to a polishing pad on a polishing platen to form a silicon oxide insulating film. The surface of the substrate, which is a semiconductor chip, is brought into contact with the surface of the substrate and the polishing pad is moved relatively to polish the surface of the substrate through the cerium oxide particles complexed on the surface.

In the case of shallow trench isolation, the lower silicon nitride layer is polished while eliminating the irregularities of the silicon oxide film layer, leaving only the silicon oxide film embedded in the element isolation portion. At this time, if the polishing rate ratio with respect to the silicon nitride serving as the stopper is large, the polishing process margin becomes large. Further, in order to use for shallow / trench separation, it is also necessary that the number of scratches generated during polishing is small.

Here, as a polishing apparatus, a general polishing having a holder for holding a semiconductor substrate and a surface plate to which a polishing cloth (pad) is attached (a motor or the like whose rotation speed is changeable is attached) is used. The device can be used. FIG. 2 is a schematic diagram showing a CMP apparatus used in the present invention. On the polishing pad 17 attached on the polishing platen 18,
CMP abrasive containing cerium oxide particles, water-soluble polymer, complexing agent with cerium and water is supplied, and the silicon oxide insulating film 14 formed on the substrate 13 which is a semiconductor chip is attached to the wafer holder 11 as the surface to be polished. Then, the silicon oxide insulating film 14 is brought into contact with the polishing pad to relatively move the surface to be polished and the polishing pad, specifically, the wafer holder 11 and the polishing platen 18.
Is rotated to perform CMP, that is, polishing of the substrate.

As the polishing pad, general nonwoven fabric, foamed polyurethane, porous fluororesin, etc. can be used without any particular limitation. Further, it is preferable that the polishing pad is grooved so that the polishing agent is accumulated. There are no restrictions on the polishing conditions, but the rotation speed of the surface plate is 10 so that the semiconductor does not jump out.
A low rotation speed of 0 min ^-1 or less is preferable. The pressing pressure of the semiconductor substrate having the film to be polished against the polishing pad is 10 to 1
00 kPa is preferable, and in order to satisfy the uniformity of the polishing rate in the wafer surface and the flatness of the pattern, 2
It is more preferably 0 to 50 kPa. During polishing, a polishing agent is continuously supplied to the polishing pad by a pump or the like. Although there is no limitation on the supply amount, it is preferable that the surface of the polishing pad is always covered with the abrasive.

FIG. 3 is a diagram showing the CMP process in the present invention. In order to perform CMP with the surface state of the polishing pad always the same, a polishing pad conditioning step is inserted before CMP. Specifically, polishing is performed with a liquid containing at least water using a dresser with diamond particles. Subsequently, the polishing step of the present invention is performed, and further, 1) brush cleaning for removing foreign matters such as particles attached to the substrate after polishing, 2) megasonic cleaning for replacing the polishing agent with water, 3) Add a wafer cleaning step consisting of spin drying for removing water from the substrate surface.

It is preferable that the semiconductor substrate after the polishing is thoroughly washed in running water, and then water droplets adhering to the semiconductor substrate are removed by using a spin dryer or the like and then dried. Thus, after forming the shallow trench isolation on the Si substrate, the silicon oxide insulating film layer and the aluminum wiring are formed thereon, and the silicon oxide insulating film formed thereon is flattened. A second layer of aluminum wiring is formed on the flattened silicon oxide insulating film layer, and a silicon oxide film is formed again between the wirings and on the wiring by the above method, and then polished with the above polishing agent. As a result, the unevenness on the surface of the silicon oxide insulating film is eliminated and the entire surface of the semiconductor substrate is made smooth. By repeating this process a predetermined number of times, a semiconductor having a desired number of layers is manufactured.

The CMP abrasive is not only a silicon oxide film or a silicon nitride film formed on a semiconductor substrate, but also a silicon oxide film formed on a wiring board having a predetermined wiring, an inorganic insulating film such as glass or silicon nitride, Optical glass such as photomasks, lenses and prisms, inorganic conductive films such as ITO, optical integrated circuits, optical switching elements and optical waveguides composed of glass and crystalline materials, optical fiber end faces, optics such as scintillators It is used for polishing substrates such as semiconductor single crystals for lasers, solid-state lasers single crystals, LED sapphire substrates for blue lasers, semiconductor single crystals for SiC, GaP, GaAs, etc., glass substrates for magnetic disks, magnetic heads, etc. .

[0037]

EXAMPLES The present invention will be described below with reference to examples.

Example 1 (Preparation of Additive A) A polyacrylic acid ammonium salt having a weight average molecular weight of 6000 and a molar number of ammonium ions / a molar number of carboxyl groups in polyacrylic acid = 1 was diluted with deionized water. A 3% by weight aqueous solution (additive solution A) was used.

(Preparation of Additive Liquid B) Cerium Carbonate Hydrate 2
1 kg of yellow-white cerium oxide particles by putting 1 kg in a platinum container and baking in air at 850 ° C. for 2 hours.
Obtained. 1 g of the cerium oxide particles prepared above, 10 g of acetylacetone, 23 g of an aqueous solution of ammonium polyacrylate (weight average molecular weight: 15,000, 40% by weight) and 8967 g of deionized water were mixed and ultrasonically dispersed for 10 minutes while stirring. The obtained slurry was filtered through a 1 μm filter, and deionized water was further added to dilute it twice (cerium oxide particle concentration 5% by weight).

(Preparation of Abrasive) CMP polishing with the above additive solution A / additive solution B / deionized water in a weight ratio of 2/1 and a cerium oxide particle concentration of 1.7% by weight and a polymer concentration of 2% by weight. The agent was created. The pH of the polishing agent was 6.8. When the secondary particle diameter was measured by a photon correlation method using an abrasive stock solution, the median value was 270 nm.

(Polishing of Insulating Film Layer and Shallow Trench Separation Layer) Al wiring Li having a Line / Space width of 0.05 to 5 mm and a height of 1000 nm is formed on an 8-inch Si substrate.
After forming the ne portion, TEOS-plasma CV is formed on the ne portion.
An insulating film layer patterned wafer having a silicon oxide film formed to a thickness of 2000 nm is manufactured by the D method. Polished for 3 minutes with the above CMP polishing agent (plate rotation number: 50 min ⁻¹ , polishing load: 30 k
Pa, abrasive supply rate: 200 ml / min). As a result, the step difference between the convex portion and the concave portion after polishing was 40 nm, which showed high flatness.

Further, as shown in FIG. 1 (a), 8 inches S
An i substrate is formed with a convex portion having a side of 350 nm to 0.1 mm square and a concave portion having a depth of 400 nm, and the convex portion density is 2 to 2, respectively.
A shallow trench isolation layer pattern wafer having a 40% content was produced. Subsequently, as shown in FIG. 1B, a nitric oxide film having a thickness of 100 nm is formed on the convex portion, and TEOS- is formed thereon.
A silicon oxide film having a thickness of 600 nm was formed by the plasma CVD method.
This patterned wafer was polished for 2 minutes with the above CMP polishing agent (plate rotation number: 50 min ⁻¹ , polishing load: 30 kP
a, supply amount of abrasive: 200 ml / min). as a result,
As shown in FIG. 1C, polishing of the convex portion was stopped by the silicon nitride film, and the step difference after polishing was 40 nm, which showed high flatness. No polishing scratches were observed in any polishing.

(Polishing of Insulating Film Layer Blanket Wafer) Next, an 8-inch silicon oxide film blanket wafer and a silicon nitride blanket wafer were each polished with the above CMP polishing agent (plate rotation speed: 50 min ⁻¹ , polishing load: 30 kP
a, supply amount of abrasive: 200 ml / min). After polishing, the wafer was removed from the holder and washed with a PVA sponge brush while flowing deionized water. After cleaning, the wafer was rotated on a spin dryer at 1000 min ⁻¹ for 1 minute to remove water droplets. Finally, the number of foreign substances on the dried wafer surface was counted using a laser scattering type foreign substance inspection device.

As a result, with respect to the silicon oxide film, the polishing rate is 150 nm / min, and foreign matters of 0.2 μm or more are detected on the wafer 1.
It was 30 per sheet. Further, with respect to the silicon nitride film, the polishing rate was 5 nm / min, and the number of foreign matters of 0.2 μm or more was 50 per wafer. Further, no polishing scratch was observed in any polishing.

Example 2 (Preparation of Abrasive) The amount of acetylacetone used in the preparation of the additive liquid B of Example 1 was changed from 10 g to 1000 g, and the amount of deionized water was accordingly changed from 8967 g to 7977.
A CMP polishing slurry was produced in the same manner as in Example 1 except that the amount was g. The pH of the abrasive was 6.6, and the median secondary particle diameter was 250 nm.

(Polishing of Insulating Film Layer and Shallow Trench Separation Layer) Using the CMP polishing agent prepared as described above, the same insulating film layer patterned wafer as in Example 1 was polished under the same polishing conditions for 5 minutes. As a result, the step difference between the convex portion and the concave portion after polishing was 55 nm.

Further, using the above CMP abrasive, a nitric oxide film having a thickness of 100 nm was formed on the convex portion of the shallow trench isolation layer pattern wafer in the same manner as in Example 1, and TEO was formed thereon.
A silicon oxide film having a thickness of 600 nm formed by the S-plasma CVD method was polished for 4 minutes under the same polishing conditions as in Example 1.
As a result, the step difference after polishing was 42 nm, which showed high flatness. No polishing scratches were observed in any polishing.

(Polishing of Insulating Film Layer Blanket Wafer) Next, the same 8-inch silicon oxide film blanket wafer and silicon nitride film blanket wafer as in Example 1 were also processed in the same manner as in Example 1 by using the above CMP abrasive. Each was polished under the polishing conditions.

As a result, with respect to the silicon oxide film, the polishing rate was 80 nm / min, and the number of foreign matters of 0.2 μm or more was 20 per wafer. Regarding the silicon nitride film,
The polishing rate was 6 nm / min, and there were 40 foreign matters of 0.2 μm or more per wafer. Further, no polishing scratch was observed in any polishing.

Comparative Example 1 (Preparation of Abrasive) The amount of acetylacetone used in the preparation of the additive liquid B of Example 1 was eliminated from 10 g to 0, and accordingly, the amount of deionized water was 8967 g to 8977 g.
A CMP polishing slurry was produced in the same manner as in Example 1 except that The pH of the abrasive was 6.8, and the median secondary particle diameter was 280 nm.

(Polishing of Insulating Film Layer and Shallow Trench Separation Layer) Using the CMP polishing agent prepared as described above, the same insulating film layer patterned wafer as in Example 1 was polished for 3 minutes under the same polishing conditions. As a result, the step difference between the convex portion and the concave portion after polishing was 45 nm.

Further, using the above CMP abrasive, a nitric oxide film having a thickness of 100 nm was formed on the convex portion of the shallow trench isolation layer pattern wafer in the same manner as in Example 1, and TEO was formed thereon.
A silicon oxide film having a thickness of 600 nm formed by the S-plasma CVD method was polished for 2 minutes under the same polishing conditions as in Example 1.
As a result, the step difference after polishing was 40 nm, indicating high flatness. No polishing scratches were observed in any polishing.

(Polishing of Insulating Film Layer Blanket Wafer) Next, the same 8-inch silicon oxide film blanket wafer and silicon nitride film blanket wafer as in Example 1 were also processed in the same manner as in Example 1 using the above CMP abrasive. Each was polished under the polishing conditions.

As a result, with respect to the silicon oxide film, the polishing rate is 160 nm / min, and foreign matter of 0.2 μm or more is removed from the wafer 1.
It was 200 pieces per sheet. For the silicon nitride film, the polishing rate was 6 nm / min, and there were 200 foreign particles of 0.2 μm or more per wafer. Regarding polishing scratches due to polishing, slight scratches were observed only on the silicon oxide film blanket wafer.

The concentration of the complexing agent with cerium is 0.1% by weight.
Comparative Example 1 is equivalent in polishing rate to Example 1 using a CMP abrasive containing 10.0% by weight or less of cerium oxide particles, a water-soluble polymer, a complexing agent with cerium and water. However, the performance of removing foreign matters, that is, particles by cleaning after polishing is poor. Regarding polishing scratches, Example 1 was superior to Comparative Example 1, and it was found that high polishing rate, high flatness, and low polishing scratches were compatible.

[0056]

The invention according to claims 1 to 4 provides a polishing agent which improves particle removal performance in cleaning after polishing, has a high polishing rate and high flatness, and can reduce polishing scratches. It is provided. The invention according to claim 5 improves particle removal performance in cleaning after polishing, has a high polishing rate and high flatness, and can reduce polishing scratches, and is excellent in yield and workability. is there.

[Brief description of drawings]

FIG. 1 is an explanatory view showing flattening of unevenness on a substrate surface of the present invention.

FIG. 2 is a diagram showing a CMP apparatus embodying the present invention.

FIG. 3 is an explanatory diagram showing a CMP process of the present invention.

[Explanation of symbols]

1 Si Substrate 2 Silicon Nitride Film 3 Silicon Oxide Film 11 Wafer Holder 12 Retainer 13 Semiconductor Chip Substrate 14 Silicon Oxide Insulating Film 15 Abrasive Supplying Mechanism 16 Cerium Oxide Particles, Water-Soluble Polymer, Complexing Agent with Cerium and Water Polishing agent including 17 Polishing pad 18 Polishing surface plate

Claims (5)

[Claims] 1. A CMP containing cerium oxide particles, a water-soluble polymer, a complexing agent with cerium, and water, and the concentration of the complexing agent with cerium is 0.1% by weight or more and 10.0% by weight or less.
Abrasive. 2. The complexing agent has the general formula (I): (Wherein R ¹ and R ² represent a substituted or unsubstituted alkyl group, and R ³ represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms). Item 1. The CMP abrasive according to Item 1. 3. The CMP abrasive according to claim 1, wherein the complexing agent is acetylacetone. 4. The CMP polishing according to claim 1, wherein the water-soluble polymer is at least one selected from the group consisting of water-soluble anionic surfactants and water-soluble nonionic surfactants. Agent. 5. A semiconductor chip on which a silicon oxide insulating film is formed by supplying a CMP abrasive containing cerium oxide particles, a water-soluble polymer, a complexing agent with cerium and water to a polishing pad on a polishing platen. A method for polishing a substrate, which comprises bringing the surface to be polished into contact with the surface to be polished of a substrate and moving the polishing pad relative to each other to polish the surface of the substrate through cerium oxide particles complexed on the surface.