JP2003347247A - Cmp polishing agent for semiconductor insulating film and method of polishing substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing agent and a polishing method which are capable of effectively and quickly polishing an inorganic insulating film such as a silicon oxide film or the like and enabling process control to be easily carried out in a CMP technique for flattening an interlayer insulating film, a BPSG film, and a shallow trench isolation insulating film. <P>SOLUTION: The CMP polishing agent possessing thixotropic properties of decreasing its viscosity with an increase in shear stress is used for a semiconductor insulating film in the polishing method. A substrate provided with a film to be polished is pressed against the polishing cloth of a polishing platen, the substrate and the polishing platen are moved to polish the film as the CMP polishing agent used for the semiconductor insulating film is fed between the film and the polishing cloth. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device manufacturing technique, which is a step of flattening a substrate surface, particularly an interlayer insulating film,
The present invention relates to a CMP polishing agent for a semiconductor insulating film used in a step of flattening a BPSG (boron or phosphorus-doped silicon dioxide film) film, a step of forming a shallow trench isolation, and a method of polishing a substrate using the CMP polishing agent. .

[0002]

2. Description of the Related Art At present, ultra-large-scale integrated circuits tend to increase the packing density, and various microfabrication techniques have been studied and developed. Already, design rules are on the order of sub-half microns. One of the technologies that have been developed to satisfy such strict requirements for miniaturization is a CMP (Chemical Mechanical Polishing) technology. This technology can completely flatten a layer to be exposed in a semiconductor device manufacturing process, reduce the burden of the exposure technology, and stabilize the yield.
This technique is essential when flattening an interlayer insulating film and a BPSG film, isolating a shallow trench, and the like.

Conventionally, in the process of manufacturing a semiconductor device, an inorganic insulating film layer such as a silicon oxide insulating film formed by a method such as plasma-CVD (Chemical Vapor Deposition) or low-pressure-CVD is flattened. Fumed silica-based polishing agents have been generally studied as CMP polishing agents. Fumed silica-based abrasives are used to grow silica particles by a method such as pyrolysis of silica particles into tetrachlorosilicic acid.
Manufactured with H adjustment. However, such a polishing agent does not have a sufficient polishing rate for the inorganic insulating film, and there has been a technical problem of a low polishing rate for practical use. In the conventional CMP technique for flattening an interlayer insulating film, the polishing rate has a large dependence on the pattern of the film to be polished on the substrate, and the polishing rate of the projections greatly differs depending on the pattern density difference or the size difference.
Further, since the polishing of the concave portion also proceeds, there has been a technical problem that a high level of planarization cannot be realized over the entire surface of the wafer.

In the CMP technique for flattening an interlayer film, it is necessary to finish polishing in the middle of the interlayer film, and a process management method for controlling a polishing amount by a polishing time is generally performed. However, there has been a problem that not only the change in the pattern step shape but also the state of the polishing cloth significantly changes the polishing rate, making process management difficult.
In the generation of the design rule of 0.5 μm or more, LOCOS (local oxidation of silicon) has been used for element isolation in an integrated circuit. After that, when the processing size is further reduced, a technique for narrowing the element isolation width is required, and the shallow trench isolation is being used. In the shallow trench isolation, CMP is used to remove an excess silicon oxide film formed on the substrate, and a stopper film having a low polishing rate is formed below the silicon oxide film to stop polishing. Silicon nitride or the like is used for the stopper film, and it is desirable that the polishing rate ratio between the silicon oxide film and the stopper film is large.

On the other hand, cerium oxide abrasives have been used as abrasives for glass surfaces such as photomasks and lenses. Cerium oxide particles have a lower hardness than silica particles and alumina particles and are therefore less likely to scratch the polished surface, and thus are useful for finish mirror polishing. However, since a cerium oxide abrasive for polishing a glass surface uses a dispersant containing a sodium salt, it cannot be directly used as an abrasive for semiconductors.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a CMP technique for flattening an interlayer insulating film, a BPSG film, and an insulating film for isolating a shallow trench, which enables efficient and high-speed polishing of an inorganic insulating film such as a silicon oxide film. Another object of the present invention is to provide an abrasive and a polishing method capable of easily performing process control.

[0007]

According to the present invention, there is provided a CM for a semiconductor insulating film characterized by exhibiting a thixotropy characteristic or a quasi-viscous flow in which the viscosity decreases with an increase in shear stress.
It relates to a P abrasive (hereinafter, may be referred to as a CMP abrasive). The present invention also provides a CMP for a semiconductor insulating film as described above comprising cerium oxide particles, a dispersant, a fluid property modifier and water.
For abrasives. Preferably, the fluid property modifier is at least one water-soluble polymer. The present invention also relates to a method in which a substrate on which a film to be polished is formed is pressed against a polishing cloth of a polishing platen and pressurized, and the above-described CMP slurry for a semiconductor insulating film is supplied between the film and the polishing cloth. The present invention relates to a substrate polishing method for polishing a film by moving a polishing platen.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Examples of the CMP abrasives of the present invention which exhibit a thixotropic property or a quasi-viscous flow in which the viscosity decreases with an increase in shear stress include cerium oxide particles, a dispersant, a fluid property modifier and water. Is preferred. Generally, cerium oxide is carbonate, nitrate, sulfate,
It is obtained by oxidizing a cerium compound such as oxalate. A cerium oxide abrasive used for polishing a silicon oxide film formed by a TEOS-CVD method or the like can perform high-speed polishing as the primary particle diameter is larger and the crystal distortion is smaller, that is, the crystallinity is better. Polishing scratches tend to occur. Thus, the method for producing the cerium oxide particles used in the present invention is not limited, but the cerium oxide crystallite diameter is preferably 5 nm or more and 300 nm or less. Further, since it is used for polishing a semiconductor chip, the content of alkali metals and halogens is preferably suppressed to 10 ppm or less in the cerium oxide particles.

In the present invention, as a method for producing cerium oxide particles, calcination or an oxidation method using hydrogen peroxide or the like can be used. The firing temperature is preferably from 350 ° C. to 900 ° C. Since the cerium oxide particles produced by the above method are agglomerated, it is preferable to mechanically pulverize the particles.
As the pulverization method, a dry pulverization method using a jet mill or the like or a wet pulverization method using a planetary bead mill or the like is preferable. The jet mill is described in, for example, Chemical Industry Transactions, Vol. 6, No. 5 (198
0) pages 527-532.

[0010] The CMP polishing slurry in the present invention is, for example,
A composition comprising cerium oxide particles having the above characteristics, a dispersant, and water is dispersed to form a dispersion (or slurry),
Further, it is obtained by adding a fluid property modifier. Here, the concentration of the cerium oxide particles in the dispersion 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.

Since the dispersant is used for polishing semiconductor chips, the content of alkali metals such as sodium ions and potassium ions, halogen and sulfur is 1%.
It is preferably suppressed to 0 ppm or less, and for example, a polyammonium acrylate or a polymer dispersant containing an ammonium acrylate as a copolymer component is preferable. Also, a polymer dispersant containing ammonium polyacrylate or ammonium acrylate as a copolymer component, a water-soluble anionic dispersant, a water-soluble nonionic dispersant, a water-soluble cationic dispersant, a water-soluble amphoteric Two or more dispersants including at least one selected from dispersants may be used. Examples of the water-soluble anionic dispersant include triethanolamine lauryl sulfate, ammonium lauryl sulfate, polyoxyethylene alkyl ether triethanolamine sulfate, a special polycarboxylic acid type polymer dispersant, and the like. As a dispersant, for example,
Polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene higher alcohol ether, polyoxyethylene octyl phenyl ether, polyoxyethylene nonyl phenyl ether, polyoxyalkylene alkyl ether , Polyoxyethylene derivatives, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan Trioleate, polyoxyethylene sorbite tetraoleate, polyethylene glycol Coal monolaurate, polyethylene glycol monostearate, polyethylene glycol distearate, polyethylene glycol monooleate, polyoxyethylene alkylamine, polyoxyethylene hydrogenated castor oil, alkyl alkanolamide, etc., and water-soluble cationic dispersion Examples of the agent include polyvinylpyrrolidone, coconutamine acetate, stearylamine acetate, and the like.Examples of the water-soluble amphoteric dispersant include, for example, lauryl betaine, stearyl betaine, lauryl dimethylamine oxide,
2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine and the like.

The amount of the dispersant added may be set to 100 wt. The range is preferably 0.01 part by weight or more and 2.0 parts by weight or less based on parts by weight. The molecular weight of the dispersant is preferably from 100 to 50,000, and from 1,000 to 1
000 is more preferred. When the molecular weight of the dispersant is less than 100, the dispersibility of the cerium oxide particles may be deteriorated, and when the molecular weight of the dispersant exceeds 50,000,
This is because a sufficient polishing rate may not be obtained when polishing a silicon oxide film or a silicon nitride film.

As a method for dispersing the 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. The average particle size (or the median of the particle size distribution) of the cerium oxide particles in the dispersion (or slurry) or the CMP polishing slurry thus prepared is 0.01 μm to
It is preferably 1.0 μm. If the average particle size of the cerium oxide particles is less than 0.01 μm, the polishing rate may be too low, and if it exceeds 1.0 μm, the film to be polished may be easily damaged.

The quasi-viscosity behavior refers to a phenomenon in which the apparent viscosity decreases as the shear rate increases. The thixotropic property is also a property in which the apparent viscosity is reduced when the shear rate is increased, but also refers to a property in which the apparent viscosity is restored to the original viscosity when left still. Such properties are widely used in the fields of paints, foods, cosmetics and the like. CMP of the present invention
The fluid property modifier for imparting thixotropy or quasi-viscosity behavior to the abrasive is not particularly limited, but is preferably at least one compound selected from water-soluble polymers. Examples of the water-soluble polymer include gum arabic, arabinogalactan, alginic acid, alginate, propylene glycol alginate, gati gum, carrageenan, karaya gum, carob bean gum, xanthan gum, guar gum, carboxymethyl cellulose, carboxymethyl cellulose salt, cellulose, tamarind gum, tragacanth gum, Starch glycolic acid, starch glycolate, starch phosphate, starch phosphate, furceleran, curdlan, dextran, pullulan, pectin, polyacrylic acid, polyacrylate,
Polymethacrylic acid, polymethacrylate, polymaleic acid, polymaleate, polystyrenesulfonic acid, polystyrenesulfonate, methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylmethylcellulose, hydroxypropylethylcellulose, polyacrylamide, polyvinyl alcohol,
Polyvinyl pyrrolidone, polyethylene oxide, chitosan, polyethylene imine, polyallylamine and the like are preferably used. The weight average molecular weight of the water-soluble polymer is 500
It is preferable that the amount is not less than the upper limit, but it is preferably 5,000,000 or less from the viewpoint of solubility.

These fluid property modifiers adjust the pH with bases such as sodium hydroxide, potassium hydroxide, calcium hydroxide, ammonia, ethanolamine and N, N-dimethylethanolamine according to the desired pH. However, amines such as ammonia, ethanolamine, and N, N-dimethylethanolamine are preferred from the viewpoint of affecting the semiconductor device after polishing. Also, hydrochloric acid, nitric acid,
The pH may be adjusted with an inorganic acid such as sulfuric acid or an organic acid such as acetic acid or citric acid. The addition amount of the fluid property modifier is preferably in the range of 0.01 to 30 parts by weight based on 100 parts by weight of the CMP abrasive. If the addition amount is too small, the addition effect may not be exhibited, and if it is too large, the polishing rate may decrease.

The concentration of the cerium oxide particles in the CMP polishing slurry of the present invention is not particularly limited, but is usually 0.1 to 0.1.
A range of 10% by weight is preferred. The CMP polishing slurry of the present invention can be stored as a CMP polishing slurry in which a cerium oxide slurry composed of cerium oxide particles, a dispersant, and water, and an additive liquid composed of a fluid property modifier and water are stored separately or in advance. Even when stored as an abrasive containing a fluid property modifier, stable properties can be obtained. When polishing the substrate with the above CMP abrasive, the additive liquid is supplied separately to the cerium oxide slurry on the polishing platen and mixed on the polishing platen or mixed with the cerium oxide slurry immediately before polishing. A method of supplying an abrasive containing a fluid property modifier in advance onto a polishing platen is adopted.

In the method of polishing a substrate according to the present invention, the substrate on which a film to be polished is formed is pressed against a polishing cloth of a polishing platen and pressurized.
While supplying the CMP polishing slurry of the present invention between the film and the polishing cloth, the film is polished by moving the substrate and the polishing platen. here,
Moving the substrate and the polishing platen means moving one or both of the substrate and the polishing platen so that the film and the polishing cloth rub against each other via the CMP polishing agent.

Examples of a method for forming an inorganic insulating film on a substrate, which is an example of a film to be polished using the CMP polishing slurry of the present invention, include a low pressure CVD method and a plasma CVD method.
In forming a silicon oxide film by a low-pressure CVD method, monosilane: SiH _{4 is} used as a Si source, and oxygen: O ₂ is used as an oxygen source. It can be obtained by performing this SiH ₄ —O ₂ -based oxidation reaction at a low temperature of 400 ° C. or less. In some cases, C
After VD, heat treatment is performed at a temperature of 1000 ° C. or lower.
Phosphorus in order to surface planarization by a high temperature reflow: when doped with _P, it is preferable to use a SiH ₄ -O 2 -PH ₃ system reaction gas. The plasma CVD method has an advantage that a chemical reaction requiring a high temperature can be performed at a low temperature under normal thermal equilibrium. The plasma generation method includes two types, a capacitive coupling type and an inductive coupling type. As a reaction gas, Si
SiH ₄ using SiH _{4 as} a source and N ₂ O as an oxygen source
₄ -N ₂ O-based gas and tetraethoxysilane (TEOS)
_{TEOS-O 2} based gas using the Si source (TEOS-
Plasma CVD). Substrate temperature is 250 ° C
The reaction pressure is preferably in the range of 67 to 400 Pa. As described above, the silicon oxide film may be doped with an element such as phosphorus and boron. Similarly, formation of a silicon nitride film by low-pressure CVD is performed by using dichlorosilane as a Si source:
SiH ₂ Cl ₂ and ammonia: NH ₃ are used as a nitrogen source. This SiH ₂ Cl ₂ —NH ₃ system oxidation reaction
It is obtained by performing at a high temperature of 0 ° C. Plasma C
The VD method uses SiH ₄ as a Si gas as a reaction gas,
NH _{3 SiH} 4 -NH ₃ based gas using the like as a nitrogen source. The substrate temperature is preferably from 300C to 400C.

As the substrate, for example, a silicon oxide film layer or a silicon nitride film is formed on a semiconductor substrate such as a semiconductor substrate in which circuit elements and wiring patterns are formed, and a semiconductor substrate in which circuit elements are formed. A substrate on which an inorganic insulating film such as a layer is formed can be used. By polishing the silicon oxide film layer or the silicon nitride film layer formed on such a semiconductor substrate with the above-mentioned CMP polishing agent, unevenness on the surface of the silicon oxide film layer or the silicon nitride film layer is eliminated, and the entire surface of the semiconductor substrate is removed. It can be a smooth surface. It can also be used for shallow trench isolation. For use in shallow trench isolation, it is necessary that the ratio of the polishing rate of the silicon oxide film to the polishing rate of the silicon nitride film and the polishing rate of the silicon oxide film / the polishing rate of the silicon nitride film be 10 or more.
If the ratio is less than 10, the difference between the polishing rate of the silicon oxide film and the polishing rate of the silicon nitride film is small, and it becomes impossible to stop polishing at a predetermined position when performing shallow trench isolation. When the ratio is 10 or more, the polishing rate of the silicon nitride film is further reduced, and the polishing can be easily stopped.
More preferred is a shallow trench isolation. In addition, in order to use it for shallow trench isolation, it is necessary that the generation of scratches during polishing be small.

Here, an apparatus used for polishing includes a holder for holding a substrate such as a semiconductor substrate and a polishing cloth (pad).
A general polishing apparatus having a polishing platen on which a motor or the like whose rotation speed can be changed is attached can be used. As the polishing cloth, general nonwoven fabric, foamed polyurethane, porous fluororesin and the like can be used, and there is no particular limitation. Further, it is preferable that the polishing cloth is subjected to a groove processing for accumulating a CMP abrasive. The polishing conditions are not limited, but the rotation speed of the polishing platen is 200 rpm or less, more preferably 10 to 200 rpm so that a substrate such as a semiconductor substrate does not pop out.
A low rotation speed of rpm is preferable, and the pressure applied to a substrate such as a semiconductor substrate is 9.8 × 10 ⁴ so that no scratch is generated after polishing.
Pa or less (1 kg / cm ² or less), more preferably 1.
It is preferably from 0 to 9.8 × 10 ⁴ Pa (0.1 to 1 kg / cm ² ). During polishing, a CMP abrasive is continuously supplied between the polishing cloth and the film to be polished by a pump or the like. Although there is no limitation on the supply amount, it is preferable that the surface of the polishing cloth is always covered with the CMP polishing agent.
It is preferable to supply at 0 ml / min.

It is preferable that the substrate such as a semiconductor substrate after the polishing is thoroughly washed in running water, and then water drops adhering to the substrate are removed using a spin drier or the like, and then dried. Also, for example, after forming a shallow trench flattened in a semiconductor substrate as described above, an aluminum wiring is formed on the silicon oxide insulating film layer, and between the wirings and on the wirings, again by the above-described method. After the formation of the silicon oxide insulating film, polishing is performed using the above-mentioned CMP polishing agent to eliminate irregularities on the surface of the insulating film and to make a smooth surface over the entire semiconductor substrate. By repeating this process a predetermined number of times, a desired number of semiconductor layers can be manufactured.

A film to be polished having unevenness (such as a silicon oxide film)
In order to achieve the global flattening, it is necessary that the convex portions are selectively polished. When the thixotropic or semi-viscous flow CMP polishing agent of the present invention is used, the shearing force of the projections is high, the viscosity at the projections is reduced, the fluid lubricating film on the film to be polished becomes thinner, and the Polishing becomes easier. On the other hand, a concave portion having a low shear force is hardly polished because a thick fluid lubricating film is formed, and as a result, global flattening can be achieved.

The CMP polishing slurry of the present invention can be used not only for a silicon oxide film formed on a semiconductor substrate, but also for a silicon oxide film formed on a wiring board having predetermined wiring, an inorganic insulating film such as glass and silicon nitride, and a polycrystalline silicon. Silicon, Al, Cu, Ti, TiN,
A film mainly containing W, Ta, TaN, etc., an optical glass such as a photomask, a lens, a prism, etc., an inorganic conductive film such as ITO, an optical integrated circuit / optical switching element / optical waveguide composed of glass and a crystalline material; Optical fiber end face, optical single crystal such as scintillator, solid-state laser single crystal, sapphire substrate for blue laser LED, SiC, Ga
A semiconductor single crystal such as P or GaAs, a glass substrate for a magnetic disk, a magnetic head, or the like can be polished.

[0024]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples of the present invention and Comparative Examples thereof, but the present invention is not limited to these Examples. Example 1 (Preparation of cerium oxide particles) 2 kg of cerium carbonate hydrate
Was placed in a platinum container, and calcined at 800 ° C. for 2 hours in the air to obtain about 1 kg of a yellowish white powder. When this powder was subjected to phase identification by an X-ray diffraction method, it was confirmed that the powder was cerium oxide. The particle diameter of the calcined powder was 30 to 100 μm. When the surface of the fired powder particles was observed with a scanning electron microscope, grain boundaries of cerium oxide were observed. When the primary particle diameter of cerium oxide surrounded by the grain boundaries was measured, the median of the volume distribution was 190 nm and the maximum was 500 nm. 1 kg of cerium oxide powder was dry-ground using a jet mill. Observation of the pulverized particles with a scanning electron microscope revealed that, in addition to the small particles having the same size as the primary particle diameter, large pulverized residual particles of 1 to 3 μm and 0.5 to 1
Residual particles of μm were mixed.

(Preparation of Cerium Oxide Slurry and Cerium Oxide Abrasive) 1 kg of the cerium oxide particles prepared above and an aqueous solution of ammonium polyacrylate (40% by weight) 23
g and deionized water (8977 g) were mixed and subjected to ultrasonic dispersion for 10 minutes while stirring. The obtained slurry was filtered through a 1-micron filter, and further 5% by weight of slurry was obtained by adding deionized water. The slurry pH is 8.
It was 3. As a result of diluting the slurry particles to an appropriate concentration to measure with a laser diffraction type particle size distribution meter,
The median particle size was 190 nm. 600 g of the above-mentioned cerium oxide slurry (solid content: 5% by weight), 18 g of polyacrylamide having a molecular weight of 900,000 as a fluid property modifier, and 2382 g of deionized water were mixed, and cerium oxide polishing to which a fluid property modifier was added. An agent (solid content: 1% by weight) was prepared. The pH of the abrasive was 8.1. Further, in order to measure the cerium oxide particles in the abrasive with a laser diffraction type particle size distribution analyzer, the cerium oxide particles were diluted to an appropriate concentration and measured. As a result, the median value of the particle diameter was 190 nm.

(Polishing of insulating film layer) Si having a diameter of 200 mm
After forming a line portion of Al wiring having a line / space width of 0.05 to 5 mm and a height of 1000 nm on a substrate,
A silicon oxide film is formed thereon by TEOS-plasma CVD method.
A patterned wafer having a thickness of 000 nm is manufactured. The above-mentioned pattern wafer is set on a holder to which a suction pad for attaching a substrate to be held is attached, and the holder is placed on a surface plate having a diameter of 600 mm to which a polishing pad made of porous urethane resin is attached, with the silicon oxide surface down. Further, the processing load was set to 2.94 × 10 ⁴ Pa (300 gf / cm ² ). While the cerium oxide abrasive (solid content: 1% by weight) was dropped on the surface plate at a rate of 200 ml / min, the surface plate and the wafer were rotated at 50 rpm for 2 minutes to polish the silicon oxide film. The polished wafer was thoroughly washed with pure water and then dried. Similarly, the pattern wafer was polished by setting the polishing time to 3 minutes, 4 minutes, 5 minutes, and 6 minutes. The difference in film thickness before and after polishing was measured using an optical interference type film thickness measuring device, and the polishing rate was calculated. Polishing speed of line portions of the line / space width 1 mm _{R 1} and polishing speed _{R 3} of the line portion of the line / space width 3 mm, and the line / space width 5m
The polishing rate ratio R ₅ / R to the polishing rate R _{5 at} the line portion of m
_The values of ₁ and R ₃ / R ₁ increased with the polishing time during the polishing time of 2 to 4 minutes, and were almost constant during the polishing time of 4 to 6 minutes. In the case of a polishing time of 4 minutes when the pattern width dependence of the polishing rate is constant, the line / space width is 1 mm
The polishing rate _{R 1} of the line portion of 344 nm / min (amount of polishing 1377nm), the polishing rate _{R 3} of the line portion of the line / space width 3mm is 335 nm / min (amount of polishing 1338
nm), the polishing rate _{R 5} of the line portion of the line / space width 5mm is 315 nm / min (amount of polishing 1259Nm), the polishing rate ratio _R 5 / _{R 1} and _R 3 / _{R 1} are each 0.91 and 0 0.97. The polishing time is 5
The polishing amount of the line portion of each line / space width in the case of minutes and 6 minutes was almost the same as that in the case of 4 minutes, and it was found that the polishing hardly progressed after 4 minutes.

Comparative Example 1 (Preparation of cerium oxide particles) 2 kg of cerium carbonate hydrate
Was placed in a platinum container, and calcined at 800 ° C. for 2 hours in the air to obtain about 1 kg of a yellowish white powder. When this powder was subjected to phase identification by an X-ray diffraction method, it was confirmed that the powder was cerium oxide. The particle diameter of the calcined powder was 30 to 100 μm. When the surface of the fired powder particles was observed with a scanning electron microscope, grain boundaries of cerium oxide were observed. When the primary particle diameter of cerium oxide surrounded by the grain boundaries was measured, the median of the volume distribution was 190 nm and the maximum was 500 nm. 1 kg of cerium oxide powder was dry-ground using a jet mill. Observation of the pulverized particles with a scanning electron microscope revealed that, in addition to the small particles having the same size as the primary particle diameter, large pulverized residual particles of 1 to 3 μm and 0.5 to 1
Residual particles of μm were mixed.

(Preparation of Cerium Oxide Slurry and Cerium Oxide Abrasive) 1 kg of the cerium oxide particles prepared above and an aqueous solution of ammonium polyacrylate (40% by weight) 23
g and deionized water (8977 g) were mixed and subjected to ultrasonic dispersion for 10 minutes while stirring. The obtained slurry was filtered through a 1-micron filter, and 5% by weight of an abrasive was obtained by adding deionized water. The slurry pH is 8.3
Met. 600 g of the above cerium oxide slurry (solid content: 5% by weight) and 2400 g of deionized water were mixed to prepare a cerium oxide abrasive (solid content: 1% by weight). The pH of the abrasive was 7.4, and the cerium oxide particles in the abrasive were diluted to an appropriate concentration for measurement by a laser diffraction type particle size distribution analyzer. It was 190 nm.

(Polishing of insulating film layer) Si having a diameter of 200 mm
Line / space width on the substrate is high with a width of 0.05 to 5 mm
After forming a line portion of Al wiring having a thickness of 1000 nm,
A silicon oxide film is formed thereon by TEOS-plasma CVD method.
A patterned wafer having a thickness of 000 nm is manufactured. Hold
To the holder to which the suction pad for attaching the substrate
Set the above pattern wafer, made of porous urethane resin
Acid on a 600 mm diameter platen with a polishing pad
Place the holder with the silicon oxide film face down, and further process the load
To 2.94 × 10⁴Pa (300 gf / cm²Set to
did. The cerium oxide slurry (solid content:
1% by weight) at a rate of 200 ml / min.
Then, rotate the platen and the wafer at 50 rpm for 1 minute,
The silicon oxide film was polished. Wash the polished wafer well with pure water
After that, it was dried. Similarly, set the polishing time to 1.5 minutes and 2 minutes.
Thus, the pattern wafer was polished. Line / Spa
Polishing speed R of line part with width 1mm₁And line / s
Pace Polishing speed R of the line part with a width of 3 mm₃, And la
In / space Polishing rate R of line part with 5mm width₅
And polishing rate ratio R ₅/ R₁And R₃/ R₁Is the polishing time
It was almost constant between 1 and 2 minutes. Polishing rate putter
Polishing time in which the width dependence is constant depending on the polishing time.
For 5 minutes, line / space 1mm wide line part
Polishing rate R₁Is 811 nm / min (polishing amount 1216 n
m), line / space Polishing of line part with 3mm width
Speed R ₃Is 616 nm / min (polishing amount 924 nm)
/ Space Polishing speed R of 5mm wide line part₅Is
497 nm / min (polishing amount 746 nm), and polishing rate
Ratio R₅/ R₁And R₃/ R₁Are 0.61 and
0.76. With a polishing time of 2 minutes, line / space
In the line area of 0.05 to 1 mm width, polishing is
It has reached the Al wiring underlying the base film.

Comparative Example 2 (Polishing of insulating film layer)
/ Space width is 0.05-5mm and height is 1000
After forming a line portion of Al wiring of nm, TE
2000-nm silicon oxide film by OS-plasma CVD
The formed pattern wafer is manufactured. Cerium oxide abrasive
Example 1 except that a commercial silica slurry was used in place of
Polishing was performed for 2 minutes in the same manner as described above. This commercial slurry
PH is 10.3 and SiO ₂Contains 12.5 wt% of particles
Is what you are doing. The polishing conditions were the same as in Example 1.
You. Similarly, set the polishing time to 3 minutes, 4 minutes, 5 minutes, and 6 minutes.
The pattern wafer was polished. Optical interference type film thickness measurement
Using a device, measure the difference in film thickness before and after polishing and determine the polishing rate.
Calculated. Line / space 1mm wide line part
Polishing rate R₁And line / space 3mm wide line
Minute polishing rate R₃And line / space width 5mm
Polishing speed R of in part₅And polishing rate ratio R₅/ R₁as well as
R₃/ R₁The polishing time is between 2 and 5 minutes.
The value becomes large, and it is almost constant in the polishing time of 5 to 6 minutes.
there were. Polishing with constant pattern width dependence of polishing rate
If polishing time is 5 minutes, line / space width 1mm
Polishing speed R of in part₁Is 283 nm / min (polishing amount 14
16 nm), line / space 3 mm wide line portion
Polishing rate R₃Is 218 nm / min (polishing amount 1092 n
m), polishing speed of the line portion with a line / space width of 5 mm
Degree R₅Is 169 nm / min (polishing amount 846 nm),
Polishing rate ratio R₅/ R₁And R₃/ R₁Is 0.
60 and 0.77. If the polishing time is 6 minutes,
Polishing rate for each line / space width line
It is almost the same as the case of 5 minutes.
Polishing proceeds at the same rate even after the
I knew it would work.

[0031]

According to the present invention, an interlayer insulating film, BPSG
For flattening film, shallow trench isolation insulating film, etc.
In the MP technology, it is possible to provide a polishing agent and a polishing method capable of efficiently, rapidly, and easily performing process control of an inorganic insulating film such as a silicon oxide film.

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Koji Haga             4-13-1, Higashicho, Hitachi City, Ibaraki Prefecture Hitachi             Seiko Kogyo Co., Ltd., Yamazaki Office F term (reference) 3C058 AA07 CB03 DA02 DA13 DA17

Claims (4)

[Claims] 1. A CMP polishing slurry for a semiconductor insulating film, which exhibits a thixotropy characteristic or a quasi-viscosity flow in which the viscosity decreases as the shear stress increases. 2. The CMP for a semiconductor insulating film according to claim 1, further comprising cerium oxide particles, a dispersant, a fluid property modifier, and water.
Abrasive. 3. The CMP polishing slurry for a semiconductor insulating film according to claim 1, wherein the fluid property modifier is at least one water-soluble polymer. 4. The substrate on which a film to be polished is formed is pressed against a polishing cloth of a polishing platen and pressurized, and the CMP polishing slurry for a semiconductor insulating film according to claim 1 is interposed between the film and the polishing cloth. A substrate polishing method in which a film is polished by moving a substrate and a polishing platen while supplying the substrate.