JP2000192015A - Polishing agent for use in cmp and method for polishing substrate therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing agent which can be easily disposed of when it becomes a waste liquor and a method for polishing the surface of a substrate without leaving scratches thereon. SOLUTION: Provided are a polishing agent for use in CMP comprising cerium oxide particles, a dispersant, a biodegradable surfactant, and water and a method for polishing a substrate which comprises pressing a substrate on which a surface to be polished is formed against the polishing cloth of a polishing surface plate under applied pressure and polishing the surface by moving the substrate and the plate while feeding the polishing agent into the gap between the plate and the cloth.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing method used in a semiconductor device manufacturing technique, and more particularly to a polishing method for a substrate surface, particularly for an interlayer insulating film and a shallow trench isolation forming step. The present invention relates to a CMP polishing agent to be used and a method for 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 completely flattens the layer to be exposed in the semiconductor device manufacturing process, reducing the burden of the exposure technology,
Since the yield can be stabilized, the technique is indispensable when performing, for example, planarization of an interlayer insulating film, isolation of 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 used to planarize. Colloidal silica-based polishing agents have been generally studied as CMP polishing agents. Colloidal silica-based abrasives are produced by subjecting silica particles to grain growth by a method such as thermal decomposition of silicic acid tetrachloride and adjusting the pH. However, such a polishing agent does not have a sufficient polishing rate for the inorganic insulating film, and there is a technical problem of a low polishing rate for practical use.

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 dimensions are further reduced, the technology for narrowing the element separation width is required,
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. The conventional colloidal silica-based polishing agent has a small polishing rate ratio of about 3 between the silicon oxide film and the stopper film, and does not have practically usable characteristics for shallow trench isolation.

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] Recently, the treatment of industrial waste is becoming a social problem. CMP abrasives are difficult to recycle, and used CMP abrasives are discarded as industrial waste. C
Abrasive particles contained in the MP abrasive waste liquid cannot be subjected to sewage treatment, and must be separated from waste water. When additives other than the abrasive particles are added to the CMP abrasive, it is desirable to separate the additives from the wastewater, but at present, there is little simple separation technology.

[0007]

SUMMARY OF THE INVENTION The first aspect of the present invention is to provide a CMP polishing agent which can easily treat a waste liquid. According to a second aspect of the present invention, there is provided, in addition to the first aspect, a CMP polishing agent capable of polishing a surface to be polished such as a silicon oxide insulating film at a high speed without any damage.
A third aspect of the present invention provides a CMP abrasive having improved storage stability in addition to the first or second aspect of the present invention. A fourth aspect of the present invention provides a CMP polishing slurry in which the ratio of the polishing rate of the silicon oxide insulating film to the polishing rate of the silicon nitride insulating film is 10 or more, in addition to the first to third aspects of the present invention. The fifth aspect of the present invention provides a substrate polishing method capable of polishing a surface to be polished of a substrate without damage.

[0008]

The present invention relates to the following. (1) A CMP polishing slurry containing cerium oxide particles, a dispersant, a biodegradable surfactant, and water. (2) surfactants having biodegradability include polyamino acids and derivatives thereof, polyethers and derivatives thereof, polyvinyl alcohols and derivatives thereof, polyacetal carboxylic acids and derivatives thereof, unsaturated mono- or dicarboxylic acids and vinyl alcohol, The CMP polishing slurry according to item (1), which is a polycarboxylic acid and a derivative thereof obtained by copolymerizing vinyl acetate or cyclohexenone, a polyester having a carboxyl group in a side chain and a derivative thereof, and a polysaccharide and a derivative thereof.

(3) The CMP polishing slurry according to item (1) or (2), comprising a cerium oxide slurry containing cerium oxide particles, a dispersant and water, and an additive liquid containing a biodegradable surfactant and water. . (4) The C according to any one of (1) to (3), wherein the ratio of the polishing rate of the silicon oxide film to the polishing rate of the silicon nitride film is 10 or more.
MP abrasive.

(5) The substrate on which the film to be polished is formed is pressed against the polishing cloth of the polishing platen and pressurized, and the CMP polishing slurry according to any of (1) to (4) is applied to the polishing film and the polishing cloth. A substrate polishing method for polishing a film to be polished by moving a substrate and a polishing platen while supplying between the substrates.

[0011]

DETAILED DESCRIPTION OF THE INVENTION Generally, cerium oxide is a carbonate,
It is obtained by oxidizing cerium compounds of nitrates, sulfates and oxalates. 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. Therefore, the cerium oxide particles used in the present invention are not limited to the production method, but the cerium oxide crystallite diameter is 5 nm or more and 300 nm or more.
It is preferably not more than nm. Further, since it is used for polishing semiconductor chips, it is preferable that the content of alkali metals and halogens be suppressed to 10 ppm or less in the cerium oxide particles.

In the present invention, as a method for producing cerium oxide powder, 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 them. 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) described on pages 527-532.

In the present invention, for example, the CMP abrasive is
It can be obtained by dispersing a composition comprising cerium oxide particles having the above characteristics, a dispersant, and water, and further adding a biodegradable surfactant. Here, the concentration of the cerium oxide particles is not limited, but is preferably in the range of 0.3% by weight or more and 20% by weight or less, more preferably in the range of 0.5% by weight or more and 10% by weight or less from the viewpoint of easy handling of the dispersion. preferable.

Further, since it is used as a dispersant for polishing semiconductor chips, the content of alkali metals such as sodium ions and potassium ions, halogen and sulfur is 10%.
It is preferably and preferably suppressed to ppm or less.

The dispersant is selected from polymer dispersants, water-soluble anionic surfactants, water-soluble nonionic surfactants, water-soluble cationic surfactants and water-soluble amphoteric surfactants. One or more compounds are used.

Examples of the polymer dispersant include a polymer of an unsaturated carboxylic acid such as acrylic acid, methacrylic acid and maleic acid, or an ammonium salt thereof, and acrylic acid as a copolymer component;
Unsaturated carboxylic acids such as methacrylic acid and maleic acid; alkyl acrylates such as methyl acrylate and ethyl acrylate; hydroxyalkyl acrylates such as hydroxyethyl acrylate; alkyl methacrylate such as methyl methacrylate and ethyl methacrylate; methacrylic acid Hydroxyalkyl methacrylates such as hydroxyethyl acid, vinyl acetate, copolymers with copolymerizable monomers such as vinyl alcohol, or ammonium salts thereof, and the like, and in these polymers or copolymers, unsaturated carboxylic acid is It may be converted into an ammonium salt before the polymerization. In these polymers or copolymers, the proportion of unsaturated carboxylic acid is 1 to 10
It is preferably 0 mol%, and particularly preferably 10 to 100 mol%.

Since it is used as a dispersant for polishing semiconductor chips, the content of alkali metals such as sodium ions and potassium ions, halogen and sulfur is preferably suppressed to 10 ppm or less. For example, ammonium acrylate is used as a copolymer component. Polymer dispersants containing salts are preferred.

Examples of the water-soluble anionic surfactant include triethanolamine lauryl sulfate, ammonium lauryl sulfate, polyoxyethylene alkyl ether triethanolamine sulfate, and a special polycarboxylic acid type polymer surfactant.

Examples of the water-soluble nonionic surfactant include 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 derivative, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxy Ethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbite tetraoleate, polyethylene glycol monolaurate, polyethylene glycol monostearate, polyethylene Glycol distearate, polyethylene glycol monooleate, poly Carboxymethyl ethylene alkyl amines, polyoxyethylene hardened castor oil, and alkyl alkanolamide. Examples of the water-soluble cationic surfactants, for example, coconut amine acetate, stearyl amine acetate, and the like.

Examples of the water-soluble amphoteric surfactant 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 is preferably 0.00.0 parts by weight based on 100 parts by weight of the cerium oxide particles in view of the dispersibility of the particles in the slurry and the prevention of sedimentation.
The range is preferably from 1 part by weight to 2.0 parts by weight.

The molecular weight of the dispersant is 100 to 50,000 as a weight average molecular weight measured by gel permeation chromatography using a standard polystyrene calibration curve.
0 is preferable, and 1,000 to 10,000 is more preferable. If the molecular weight of the dispersant is too small, a sufficient polishing rate cannot be obtained when polishing a silicon oxide film or a silicon nitride film, and if the molecular weight of the dispersant is too large, the viscosity becomes high and the CMP slurry is stored. Stability decreases.

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 of the cerium oxide particles in the thus prepared CMP abrasive is 0.01 μm to 1.0 μm.
It is preferred that If the average particle size of the cerium oxide particles is too small, the polishing rate will be too low, and if it is too large, the film to be polished will be easily damaged.

In the present invention, surfactants having biodegradability include poly (aspartic acid), poly (glutamic acid), poly (lysine), aspartic acid-glutamic acid copolymer, aspartic acid-lysine copolymer, Polyamino acids such as glutamic acid-lysine copolymers and derivatives thereof, polyethers and derivatives thereof such as polyethylene glycol, polypropylene glycol and polytetraethylene glycol, and polyvinyl alcohols and derivatives thereof such as polyvinyl alcohol and poly (ether-ketone) , Polyacetal carboxylic acids such as polyglyoxylic acid and derivatives thereof, acrylic acid-vinyl alcohol copolymer, acrylic acid-cyclohexenone copolymer, methacrylic acid-vinyl alcohol copolymer, methacrylic acid-cyclohexenone copolymer , Fumaric acid-vinyl alcohol copolymer, fumaric acid-cyclohexenone copolymer, maleic acid-vinyl alcohol copolymer, maleic acid-cyclohexenone copolymer and other unsaturated mono- and dicarboxylic acids and vinyl alcohol, acetic acid Polycarboxylic acids and their derivatives obtained by copolymerization with vinyl or cyclohexenone, poly (α-malic acid), poly (β-malic acid), poly (α, β-malic acid), etc. Polyester having a carboxyl group and its derivatives, starch, chitosan,
Preferred are polysaccharides such as alginic acid, carboxymethylcellulose, methylcellulose, pullulan and curdlan, and derivatives thereof.

The amount of the biodegradable surfactant added is 100 parts by weight of the cerium oxide particles in view of the dispersibility of the particles in the CMP abrasive and the prevention of sedimentation and the relationship between the polishing scratches and the amount of the surfactant added. 0.01 parts by weight or more
The range is preferably not more than 00 parts by weight, and more preferably not less than 30 parts by weight. The molecular weight of the biodegradable surfactant is preferably 100 to 500,000, more preferably 1,000 to 50,000, as a weight average molecular weight measured by gel permeation chromatography using a standard polystyrene calibration curve. Is preferred. If the molecular weight of the surfactant is too small, a sufficient polishing rate cannot be obtained when polishing a silicon oxide film or a silicon nitride film,
If the molecular weight of the surfactant is too large, the viscosity increases,
The storage stability of the CMP abrasive decreases.

If a cerium oxide slurry composed of cerium oxide particles, a dispersant, and water and an additive solution composed of a biodegradable surfactant and water are stored as a separate CMP abrasive, the cerium oxide particles do not agglomerate. This is preferable because storage stability is increased, polishing scratches are prevented from occurring, and the polishing rate is stabilized. When polishing a substrate with the above-mentioned CMP polishing agent, the additive liquid is supplied separately to the polishing platen and the cerium oxide slurry and mixed on the polishing platen, or mixed with the cerium oxide slurry immediately before polishing to polish. The method of supplying on a surface plate is taken.

The CMP polishing slurry of the present invention further comprises N,
Additives such as N-diethylethanolamine, N, N-dimethylethanolamine, aminoethylethanolamine and the like may be added.

As a method of forming an inorganic insulating film using the CMP polishing slurry of the present invention, low pressure CVD, plasma CVD, etc.
And the like. In forming a silicon oxide film by low-pressure CVD, monosilane: SiH _{4 is} used as a Si source, and oxygen: O ₂ is used as an oxygen source. The SiH4-O ₂ system oxidation reaction 4
It is obtained by performing at a low temperature of 00 ° C. or less. In some cases, heat treatment is performed at a temperature of 1000 ° C. or lower after CVD. When doping phosphorus: P for planarizing the surface by high-temperature reflow, SiH ₄ —O ₂ −
It is preferable to use a PH ₃ based reaction gas. Plasma C
The VD method has an advantage that a chemical reaction requiring a high temperature can be performed at a low temperature under ordinary thermal equilibrium. In the plasma generation method,
There are two types, a capacitive coupling type and an inductive coupling type. As a reaction gas, a SiH ₄ -N ₂ O-based gas using SiH ₄ as a Si source and N ₂ O as an oxygen source and a TEOS-O ₂ -based gas (TEOS-) using tetraethoxysilane (TEOS) as a Si source are used. Plasma CVD). The substrate temperature is preferably in the range of 250 ° C. to 400 ° C., and the reaction pressure is preferably in the range of 67 to 400 Pa. As described above, the silicon oxide film of the present invention may be doped with an element such as phosphorus and boron.

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

As a substrate, a silicon oxide film layer or a silicon nitride film layer 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. Substrate can be used.

By polishing the silicon oxide film layer or 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 is eliminated, and the entire surface of the semiconductor substrate is smoothed. Plane. 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 this ratio is 10 or more, the polishing rate of the silicon nitride film is further reduced, and the polishing can be easily stopped, which is more suitable for 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.

As an apparatus for polishing, a general polishing apparatus having a holder for holding a semiconductor substrate and a platen on which a polishing cloth (pad) is attached (a motor or the like capable of changing the number of rotations is attached) is used. it can. As the polishing cloth, general nonwoven fabric, foamed polyurethane, porous fluororesin and the like can be used, and there is no particular limitation. The polishing cloth is CMP
It is preferable to perform a groove process in which the abrasive is accumulated. The polishing conditions are not limited, but the rotation speed of the surface plate is preferably 200 rpm or less so that the semiconductor substrate does not pop out, and the pressure applied to the semiconductor substrate is 1 kg / cm ² or less so that scratches do not occur after polishing. Is preferred. During polishing, the slurry is continuously supplied to the polishing cloth by a pump or the like. Although the supply amount is not limited, it is preferable that the surface of the polishing pad is always covered with the slurry.

After the polishing, the semiconductor substrate is preferably washed well in running water, and then dried using a spin drier or the like to remove water droplets adhering to the semiconductor substrate. After forming the shallow trench thus flattened, an aluminum wiring is formed on the silicon oxide insulating film layer, and a silicon oxide insulating film is formed again between the wirings and on the wiring by the above method. By polishing using the above-mentioned CMP polishing agent, irregularities on the surface of the insulating film are eliminated, and a smooth surface is formed over the entire surface of the semiconductor substrate. By repeating this process a predetermined number of times, a semiconductor having a desired number of layers is manufactured.

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, Optical glasses such as masks, lenses, prisms, etc .; inorganic conductive films such as ITO; optical integrated circuits, optical switching elements, optical waveguides composed of glass and crystalline materials, end faces of optical fibers, optical single crystals such as scintillators, solids A laser single crystal, a sapphire substrate for a blue laser LED, a semiconductor single crystal such as SiC, GaP, and GaAs, a glass substrate for a magnetic disk, and a magnetic head can be polished.

[0037]

Next, the present invention will be described by way of examples.

Preparation Example 1 (Preparation of Cerium Oxide Particles) 2 kg of cerium carbonate hydrate was placed in a platinum container at 700 ° C.
The mixture was calcined in the air for 2 hours 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. Cerium oxide powder was mixed with deionized water so as to have a concentration of 10% by weight, and pulverized at 1,400 rpm for 120 minutes using a horizontal wet ultrafine particle pulverizer. The obtained polishing liquid was dried at 110 ° C. for 3 hours to obtain cerium oxide particles. Observation with a transmission electron microscope showed that the cerium oxide particles had a particle size of 5 nm to 60 nm, and that the specific surface area measured by the BET method was 39.5 m ² / g.

Preparation Example 2 (Preparation of Cerium Oxide Particles) 2 kg of hydrated cerium carbonate was placed in a platinum container at 700 ° C.
The mixture was calcined in the air for 2 hours 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. 1 kg of cerium oxide powder was dry-ground using a jet mill. Observation with a transmission electron microscope revealed that the cerium oxide particles had a particle diameter of 5 nm to 60 nm, and furthermore, had a specific surface area measured by the BET method that was 41.2 m ² / g.

Preparation Example 3 (Preparation 1 of Cerium Oxide Slurry) 125 g of the cerium oxide particles prepared in Preparation 1 of cerium oxide particles, acrylic acid and methyl acrylate were used in a ratio of 3: 1.
Ammonium salt aqueous solution (40% by weight) of a polyacrylic acid copolymer having a weight average molecular weight of 10,000 copolymerized with
g and 2372 g of deionized water were mixed and ultrasonically dispersed while stirring. Dispersion was performed at an ultrasonic frequency of 40 kHz and a dispersion time of 10 minutes. The resulting slurry was filtered through a 0.8 micron filter, and 2% by weight cerium oxide slurry (A-1) was added by adding deionized water.
I got The pH of the cerium oxide slurry (A-1) was 8.5.
Met. When the particle size distribution of the cerium oxide slurry (A-1) was examined with a laser diffraction type particle size distribution analyzer, it was found that the average particle size was as small as 0.20 μm. Also, 1.
95.0% of the particles were 0 μm or less.

Preparation Example 4 (Preparation of cerium oxide slurry 2) A cerium oxide polishing liquid except that the cerium oxide particles prepared in Preparation 2 of cerium oxide particles were used instead of the cerium oxide particles prepared in Preparation 1 of cerium oxide particles. A cerium oxide slurry (A-2) was prepared in the same manner as in Preparation 1 above. The pH of the cerium oxide slurry (A-2) was 8.7. Examination of the particle size distribution of the cerium oxide slurry (A-2) revealed that the average particle size was as small as 0.21 μm. In addition, particles of 1.0 μm or less
It was 5.0%.

Examples 1 to 4 (Polishing of insulating film layer) A TEOS-plasma CVD method was applied to a holder on which a suction pad for attaching a substrate was attached on a surface plate on which a polishing pad made of porous urethane resin was attached. A silicon wafer having a diameter of 125 mm on which the formed silicon oxide film was formed was set with the insulating film face down, and the polishing load was 300.
A weight was placed so as to give g / cm ² . The cerium oxide slurry (solid content: 2% by weight) shown in Table 1 and the additive liquid were each sent at a rate of 25 ml / min onto the surface plate, and the nozzle was adjusted and dropped immediately before the surface plate so that one solution was obtained. While the surface plate is 40rpm
For 2 minutes to polish the insulating film. After polishing, the wafer was removed from the holder, washed well with running water, and further washed with an ultrasonic cleaner for 20 minutes. After washing, water droplets were removed with a spin drier, and dried with a dryer at 120 ° C. for 10 minutes. The change in film thickness before and after polishing was measured using an optical interference type film thickness measuring device, and the polishing rate was calculated. Similarly, instead of a silicon oxide film formed by the TEOS-plasma CVD method, a silicon nitride film formed by a low-pressure CVD method was polished under the same conditions, a change in film thickness before and after polishing was measured, and a polishing rate was calculated. Table 1 shows the results.

From the results of the film thickness measurement, in each of the examples, the silicon oxide film formed by the TEOS-plasma CVD method and the silicon nitride film formed by the low-pressure CVD method have a uniform thickness over the entire surface of the wafer. I understand. Further, no damage was observed on the surface of the insulating film by visual observation under a light source of a mercury lamp.

(Evaluation of Biodegradability) The biodegradability of the surfactant was evaluated according to JIS K 6950. In a glass culture bottle (300 ml) equipped with a burette, 200 ml of activated sludge suspension and 0.8 ml of inorganic salt solution (K ₂ HPO
_{4 0.46%, Na 2 HPO 4} · 12H 2 O 1.16
_{%, MgSO 4 · 7H 2 O} 0.05%, FeCl 3 · 6
H ₂ O 0.01%, CaCl ₂ .2H ₂ O 0.005
%, NH ₄ Cl 0.1%) and about 1 ml of the sample solution, and the mixture was added at 25 ° C. using a BOD measuring device equipped with a thermostat.
A decomposition test was performed. The BOD (biochemical oxygen consumption) was measured over time for about 28 days. A value obtained by subtracting a blank test value to correct a change in the BOD value due to a change in the atmospheric pressure was defined as a true BOD value. Biodegradation is (true BOD value)
÷ (theoretical oxygen consumption) × 100. Table 1 shows the results.

[0045]

[Table 1]

As is apparent from Table 1, C according to the present invention is
The biodegradability of the surfactant contained in the MP abrasive is good,
It can be seen that waste liquid treatment is easy. Further, by using the CMP polishing slurry and the substrate polishing method of the present invention, the substrate can be polished without being damaged, and the ratio of the polishing rate of the silicon oxide film / the polishing rate of the silicon nitride film is set to 10 or more. CMP
It can be seen that an abrasive and a method for polishing a substrate using these CMP abrasives can be obtained.

[0047]

According to the first aspect of the present invention, the CMP polishing slurry can easily treat a waste liquid and is suitable for a polishing method used in a semiconductor device manufacturing technique. The CMP abrasive according to the second aspect is the first aspect of the invention.
The effect described above is exhibited, and further, the surface to be polished such as a silicon oxide insulating film can be polished at high speed without being damaged.
The CMP polishing agent according to the third aspect has the effect of the second aspect, and is further excellent in that storage stability is improved. The CMP polishing agent according to the fourth aspect has the effect of the third aspect and is suitable for shallow trench isolation in that the ratio of the polishing rate of the silicon oxide insulating film to the polishing rate of the silicon nitride insulating film is 10 or more. is there. The method for polishing a substrate according to claim 5,
It is excellent in polishing a surface to be polished of a substrate without being damaged, and is suitable for a polishing method used in a semiconductor element manufacturing technique.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshihiko Akahori 4-3-1, Higashicho, Hitachi City, Ibaraki Prefecture Inside the Ibaraki Research Laboratory, Hitachi Chemical Co., Ltd. 1 Ibaraki Research Laboratory, Hitachi Chemical Co., Ltd. (72) Inventor Naoyuki Koyama 48, Wadai, Tsukuba, Ibaraki Prefecture Hitachi Chemical Co., Ltd. F-term in Tsukuba Development Laboratories (reference) 3C058 AA07 AC04 CA01 CB01 CB02 CB06 CB10 DA02 DA12 4G076 AA02 AA24 AA26 AB02 AB09 BA39 BA46 BB08 CA02 CA15 CA21 CA26 CA28 DA30

Claims (5)

[Claims] 1. A CMP polishing slurry containing cerium oxide particles, a dispersant, a biodegradable surfactant and water. 2. A biodegradable surfactant is a polyamino acid and a derivative thereof, a polyether and a derivative thereof, a polyvinyl alcohol and a derivative thereof, a polyacetal carboxylic acid and a derivative thereof, an unsaturated mono- or dicarboxylic acid and a vinyl. The CMP polishing slurry according to claim 1, which is a polycarboxylic acid and a derivative thereof obtained by copolymerizing alcohol, vinyl acetate or cyclohexenone, a polyester and a derivative thereof having a carboxyl group in a side chain, and a polysaccharide and a derivative thereof. 3. The CM according to claim 1, comprising a cerium oxide slurry containing cerium oxide particles, a dispersant and water, and an additive liquid containing a biodegradable surfactant and water.
P abrasive. 4. The CMP polishing slurry according to claim 1, wherein a ratio between a polishing rate of the silicon oxide film and a polishing rate of the silicon nitride film is 10 or more. 5. 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 abrasive according to claim 1 is supplied between the polishing film and the polishing cloth. A substrate polishing method for polishing a film to be polished while moving a substrate and a polishing platen.