JP2003059866A - Cmp abrasive and method of polishing board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an abrasive and a polishing method, which enable the high speed polishing and a high flatness level in a CMP technology, which can plavarize an interlayer insulation film and a shallow trench isolating insulation film, without producing abrasive flaws. SOLUTION: This CMP abrasive contains an insulation film dissolving agent, an agent protecting insulation film from dissolution, and water.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CMP polishing agent used in a step of flattening a substrate surface, which is a semiconductor element manufacturing technique, in particular, a step of flattening an interlayer insulating film and a step of forming shallow trench isolation. And these CMP (Che
medical Mechanical Polish
g) It relates to a method for polishing a substrate using an abrasive.

[0002]

2. Description of the Related Art In the current ultra-large scale integrated circuits, there is a tendency to increase the packaging density, and various fine processing techniques have been researched and developed. Already, the design rules are on the order of sub-half micron. CMP technology is one of the technologies developed to satisfy such strict requirements for miniaturization. This technique can completely flatten the layer to be exposed in the manufacturing process of the semiconductor device, reduce the burden of the exposure technique, and stabilize the yield. Therefore, for example, the flattening of the interlayer insulating film, the shallow trench, etc. Separation (Shallow Trench Isolati
on: STI) is an indispensable technique.

[0003]

Conventionally, in the manufacturing process of a semiconductor device, plasma-CVD (Chemical) is used.
Vapor Deposition, chemical vapor deposition method),
Silica-based and ceria-based polishing agents are generally studied as CMP polishing agents for planarizing an inorganic insulating film layer such as a silicon oxide insulating film formed by a method such as low-pressure CVD.
However, such an abrasive causes polishing scratches on the inorganic insulating film, which causes a decrease in reliability of the semiconductor device. The present invention provides a CMP abrasive capable of reducing polishing scratches on a surface to be polished, which is provided with an insulating film such as a silicon oxide insulating film or a low dielectric constant material.

[0004]

The present invention relates to the following. (1) A CMP abrasive containing an insulating film dissolving agent, an insulating film dissolution protecting agent, and water. (2) The CMP abrasive according to claim 1, wherein the insulating film dissolving agent is a strong alkali. (3) The CMP abrasive according to claim 1, wherein the insulating film dissolving agent is hydrofluoric acid-containing. (4) The dissolution protection agent for the insulating film is polyvinylpyrrolidone, the general formula (I)

Embedded image H (OCH ₂ CH ₂ ) x-NR- (CH ₂ CH ₂ O) yH (I) (x, y: 50 to 200, R: an alkyl group having 14 to 18 carbon atoms) The CMP abrasive according to any one of claims 1 to 3, which is at least one selected from poly-oxyethylene-alkylamine compounds. (5) An insulating film dissolving agent, an insulating film dissolution protecting agent, and a CMP polishing agent containing water are supplied to a polishing cloth on a polishing platen, and contacted with a surface to be polished of a substrate which is a semiconductor chip on which an insulating film is formed. A method for polishing a substrate, characterized in that the surface to be polished and the polishing cloth are moved relative to each other to prevent etching of the film to be polished and to polish the substrate surface while weakening the surface of the film to be polished during CMP polishing. .

When the interlayer insulating film is flattened or the shallow trench is separated by using the above CMP polishing agent, the dissolution protection agent protects the surface of the film to be polished, thereby preventing etching when CMP polishing is not performed. During the CMP polishing, the insulating film dissolving agent chemically acts on the surface of the film to be polished to weaken it while removing the dissolution protecting agent from the surface of the film to be polished, and the CMP polishing having a larger chemical action is performed to thereby cause polishing scratches. It is possible to reduce

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The CMP abrasive according to the present invention is
It is obtained by dispersing the composition containing the insulating film dissolving agent, the insulating film dissolution protecting agent and water prepared by the above method.

As the insulating film dissolving agent, potassium hydroxide,
Examples thereof include strong alkalis such as sodium hydroxide and ammonium hydroxide. These may be used alone or in combination of two or more. When mainly containing strong alkali,
The pH of the abrasive is preferably 9 to 14, and more preferably 11 to 12. If the pH is less than 9, the polishing rate will be significantly reduced and
If it is larger than 4, the surface roughness of the oxide film becomes remarkable.

Further, examples of the insulating film dissolving agent include fluorine-containing acid. As the fluorinated acid, one selected from the following group is suitable. Trifluoroacetic acid, trifluoropropionic acid, F-butyric acid, F-hexanoic acid, F-octanoic acid, F-decanoic acid, F-dodecanoic acid, trifluoroacrylic acid, pentafluorobenzoic acid, pentafluorophenol, trifluoroacetic acid Sodium, potassium trifluoroacetate, ammonium trifluoroacetate, sodium trifluoropropionate, potassium trifluoropropionate, ammonium trifluoropropionate, sodium F-butyrate, potassium F-butyrate, ammonium F-butyrate, sodium F-hexanoate , Potassium F-hexanoate, ammonium F-hexanoate, sodium F-octanoate, potassium F-octanoate, ammonium F-octanoate, sodium F-decanoate, potassium F-decanoate, ammonium F-decanoate , Sodium F-dodecanoate, potassium F-dodecanoate, ammonium F-dodecanoate, sodium trifluoroacrylate, potassium trifluoroacrylate, ammonium trifluoroacrylate, sodium pentafluorobenzoate, potassium pentafluorobenzoate, penta Organic fluorine compounds such as ammonium fluorobenzoate, pentafluorophenol sodium, pentafluorophenol potassium, pentafluorophenol ammonium and ammonium salts thereof; hydrofluoric acid, fluorophosphoric acid, hexafluorosilicic acid, tetrafluoroboric acid, hexafluorotitanic acid , Sodium fluoride, potassium fluoride, ammonium fluoride, ammonium hydrogen difluoride,
Potassium hydrogen difluoride, sodium fluorophosphate, potassium fluorophosphate, ammonium fluorophosphate, sodium hexafluorosilicate, potassium hexafluorosilicate, ammonium hexafluorosilicate, sodium tetrafluoroborate, potassium tetrafluoroborate, ammonium tetrafluoroborate, hexafluoro Inorganic fluorine compounds such as sodium titanate, potassium hexafluorotitanate, and ammonium hexafluorotitanate, and ammonium salts thereof; However, when the substrate to be applied is a silicon substrate for semiconductor integrated circuits or the like, contamination with alkali metals, alkaline earth metals, halides and the like is not desirable, and therefore acids or ammonium salts thereof are desirable. This is not the case when the substrate is a glass substrate or the like. Among them, hydrofluoric acid, F-butyric acid, F-
Hexanoic acid, F-octanoic acid, F-decanoic acid, F-dodecanoic acid, trifluoroacrylic acid, and pentafluorobenzoic acid are more preferable.

The pH of the abrasive when it mainly contains fluorinated acid
Is preferably 1 to 5, more preferably 1.5 to 4,
3 is more preferable. When the pH is less than 1, the surface roughness of the oxide film is remarkably exhibited, and when the pH is more than 5, the polishing rate is remarkably reduced.

As the dissolution protective agent for the insulating film, one selected from the following group is suitable. Polysaccharides such as alginic acid, pectic acid, carboxymethylcellulose, agar, cardan and pullulan; amino acid salts such as glycine ammonium salt and glycine sodium salt; polyaspartic acid, polyglutamic acid, polylysine, polymalic acid, polymethacrylic acid , Polymethacrylic acid ammonium salt, polymethacrylic acid sodium salt, polyamic acid, polymaleic acid, polyitaconic acid, polyfumaric acid, poly (p-styrenecarboxylic acid), polyacrylic acid, polyacrylamide, aminopolyacrylamide, polyacrylic acid ammonium salt , Polyacrylic acid sodium salt, polyamic acid, polyamic acid ammonium salt, polyamic acid sodium salt and polyglyoxylic acid, and other polycarboxylic acids and salts thereof; polyvinyl alcohol, polyvinylpyrroli Vinyl polymers such as ethylene glycol and polyacrolein; polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyethylene glycol alkyl ether, polyethylene glycol alkenyl ether, alkyl polyethylene glycol, alkyl polyethylene glycol. -Alkyl ether ether, alkyl polyethylene glycol alkenyl ether, alkenyl polyethylene glycol, alkenyl polyethylene glycol alkyl ether, alkenyl polyethylene glycol alkenyl ether, polypropylene glycol alkyl ether, polypropylene glycol alkenyl ether
Ether, alkyl polypropylene glycol, alkyl polypropylene glycol alkyl ether, alkyl polypropylene glycol alkenyl ether, alkenyl polypropylene glycol, alkenyl polypropylene glycol alkyl ether and alkenyl polypropylene glycol alkenyl ether, etc. Tell; General formula (I)

[0011]

Embedded image H (OCH ₂ CH ₂ ) x-NR- (CH ₂ CH ₂ O) yH (I) (x, y: 50 to 200, R: an alkyl group having 14 to 18 carbon atoms) Poly-oxyethylene-alkylamine compound; and the like, and one kind or a mixture of two or more kinds may be used. However, when the substrate to be applied is a silicon substrate for semiconductor integrated circuit or the like, contamination with alkali metals, alkaline earth metals, halides and the like is not desirable, and therefore acids or ammonium salts thereof are desirable. This is not the case when the substrate is a glass substrate or the like. Among them, polyvinylpyrrolidone and poly-oxyethylene-alkylamine compounds are preferable.

Abrasive grains may be further added to the CMP polishing agent, if necessary. Examples of the abrasive grains include inorganic abrasive grains such as silica, alumina, ceria, titania, zirconia, germania and silicon carbide, and organic abrasive grains such as polystyrene, polyacryl and polyvinyl chloride.

The amount of the solubilizer component in the insulating film is preferably 0 to 0.05 mol, and 0.00005 mol to 0.005 per 100 g of the total weight of the CMP abrasive.
More preferably, it is mol. This compounded amount is 0.0
If it exceeds 5 mol, it becomes difficult to adjust the pH of the CMP polishing agent within the preferable range.

The amount of the dissolution protection agent component of the insulating film is CM
It is preferably 0.001 to 5% by weight, and more preferably 0.005 to 1% by weight, based on the total weight of the P abrasive. If the content is less than 0.001% by weight, the effect of combined use with the protective film-forming agent may not appear in suppressing etching, and if it exceeds 5% by weight, the CMP rate tends to decrease. The weight average molecular weight of the dissolution protective agent for the insulating film is preferably 500 to 5,000,000, more preferably 2000 to 500,000, and further preferably 5000 to 50,000. CM with a weight average molecular weight of less than 500 is high
There is a tendency that the P speed does not appear, and the weight average molecular weight is 50.
If it is more than 0,000, the solubility will decrease. When using these, it is possible to combine at least two kinds having different weight average molecular weights. The same type of dissolution protecting agent or different types of dissolution protecting agents may be used.

The blending amount of the abrasive grains is preferably 0.01 to 10% by weight with respect to the total weight of the CMP abrasive,
It is more preferable that the content be 0.05% by weight to 5% by weight.
If the blending amount is less than 0.01% by weight, the effect of containing abrasive grains is not exerted, and if it exceeds 10% by weight, the polishing rate by CMP is saturated, and no increase is observed even if it is added more.

Examples of the insulating film in which the CMP polishing agent is used include a silicon oxide insulating film, an organic low dielectric constant material and an inorganic low dielectric constant material. These may be used alone or in combination of two or more. Examples of the method for forming the insulating film include a low pressure CVD method and a plasma CVD method. For example, forming a silicon oxide film by the low pressure CVD method
Monosilane: SiH _{4 is} used as the Si source, and oxygen: O ₂ is used as the oxygen source. This SiH ₄ —O ₂ system oxidation reaction is
It is obtained by carrying out at a low temperature of 00 ° C. or lower. In some cases, heat treatment is performed at a temperature of 1000 ° C. or lower after CVD. When phosphorus: P is doped to achieve surface flattening by high temperature reflow, SiH ₄ —O ₂
It is preferable to use a PH ₃ -based reaction 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 plasma generation methods, a capacitive coupling type and an inductive coupling type. As the reaction gas, SiH ₄ is used as the Si source, and N is used as the oxygen source.
Examples thereof include SiH ₄ —N ₂ O based gas using ₂ O and TEOS—O ₂ based gas (TEOS-plasma CVD method) using tetraethoxysilane (TEOS) as a Si source. Substrate temperature is 250 ° C to 400 ° C, reaction pressure is 67 to 400
The range of Pa is preferable. Thus, the silicon oxide film of the present invention may be doped with elements such as phosphorus and boron. Similarly, the silicon nitride film formation by the low pressure CVD method is
Dichlorosilane: SiH ₂ Cl ₂ is used as the i source, and ammonia: NH ₃ is used as the nitrogen source. This SiH ₂ Cl ₂
It can be obtained by carrying out the —NH ₃ -based oxidation reaction at a high temperature of 900 ° C. In the plasma CVD method, SiH ₄ —NH ₃ system gas using SiH ₄ as a Si source and NH ₃ as a nitrogen source can be used as a reaction gas. Substrate temperature is 3
00 ° C to 400 ° C is preferable.

As a predetermined substrate, a silicon oxide insulating film layer is formed on a semiconductor substrate, that is, a semiconductor substrate in which a circuit element and aluminum wiring are formed, a semiconductor substrate in which a circuit element is formed, and the like. A substrate or the like can be used. By polishing the silicon oxide insulating film layer formed on such a semiconductor substrate with an abrasive, unevenness on the surface of the silicon oxide insulating film layer is eliminated, and a smooth surface is formed over the entire surface of the semiconductor substrate. Here, as a polishing device, a general polishing device 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 used is used. it can. As the polishing cloth, general non-woven cloth, foamed polyurethane, porous fluororesin, etc. can be used without any particular limitation. Further, it is preferable that the polishing cloth is grooved so that the slurry is accumulated. The polishing conditions are not limited, but the rotation speeds of the holder and the surface plate are set to 100 to prevent the semiconductor substrate from popping out.
A low rotation speed of rpm or less is preferable, and the pressure applied to the semiconductor substrate is 100 kPa (1 kPa) so that scratches do not occur after polishing.
g / cm ² ) or less is preferable. During polishing, an abrasive is continuously supplied to the polishing cloth with 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 an abrasive.

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. After the shallow trenches thus flattened are formed, aluminum wirings are formed on the insulating film layer, and the insulating film is formed again between the wirings and on the wirings by the above method. By polishing with, the unevenness of the surface of the 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.

[0019]

Example 1 To 1000 g of deionized water, 0.1 g of polyvinylpyrrolidone (weight average molecular weight: 30,000) was added, and the mixture was stirred and mixed for 30 minutes. Subsequently, hydrofluoric acid was added to adjust the pH to 3, and the mixture was stirred and mixed for 30 minutes to obtain a CMP abrasive.

Using the above-prepared polishing agent, a silicon oxide film (thickness: 1000 nm) on an 8-inch wafer was polished at a polishing load of 30 kPa, a platen and a carrier rotation speed of 50 rpm, a polishing agent supply rate of 200 ml / min, and a polishing time of 1 For 1 minute).

The silicon oxide film after polishing was measured with an interference film thickness meter (Lambda A: manufactured by Dainippon Screen Co., Ltd.) at 10 points in the in-plane XY directions, and the residual film thickness was 900 nm / min.
The in-plane film thickness uniformity was 3%. In addition, the polished silicon oxide film is subjected to a defect inspection device (SFS-6220: KLA-Te).
The number of defects of 0.2 μm or more was 10 / wafer. After that, when the defective portion was observed with a wafer visual inspection microscope (AL2000: made by Olympus), there were no polishing scratches and all were foreign substances.

[0022]

The present invention can provide a CMP abrasive containing an insulating film dissolving agent, an insulating film dissolution protecting agent and water. Further, by using this CMP polishing agent to prevent etching of the film to be polished and to polish while polishing the surface of the film to be weakened during CMP polishing, high-speed polishing without causing polishing scratches, A method of polishing a substrate that can be highly planarized can be applied.

Claims (5)

[Claims] 1. A CMP abrasive containing an insulating film dissolving agent, an insulating film dissolution protecting agent and water. 2. The CMP abrasive according to claim 1, wherein the insulating film dissolving agent is a strong alkali. 3. The CMP polishing agent according to claim 1, wherein the insulating film dissolving agent is hydrofluoric acid-containing. 4. A dissolution protecting agent for an insulating film is polyvinylpyrrolidone, represented by the general formula (I): H (OCH ₂ CH ₂ ) x-NR- (CH ₂ CH ₂ O) yH (I) (x, y : 50 to 200, R: at least one selected from the poly-oxyethylene-alkylamine compounds represented by R: an alkyl group having 14 to 18 carbon atoms). CMP abrasive. 5. A CMP abrasive containing an insulating film dissolving agent, an insulating film dissolution protecting agent and water is supplied to a polishing cloth on a polishing platen,
The surface to be polished is relatively moved by bringing the surface to be polished into contact with the surface to be polished of the substrate which is the semiconductor chip on which the insulating film is formed, and the surface of the film to be polished is weakened during CMP polishing. A method for polishing a substrate, which comprises polishing the surface of the substrate while performing the polishing.