JP2001196336A - Aqueous dispersant for chemical mechanical polishing used in manufacture of semiconductor device and chemical mechanical polishing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous dispersant for chemical mechanical polishing which can form sufficiently flattened good damascene wiring and is used in the manufacture of a semiconductor device and a chemical mechanical polishing method using the dispersant. SOLUTION: The aqueous dispersant has such a feature that, when a copper film, a barrier metal film, and an insulating film are polished under the same condition, the ratio (RCu/RBM) of the polishing speed RCu of the copper film to that RBM of the barrier metal film becomes 0.5-2 and the ratio (RCu/RIn) of the polishing speed RCu of the copper film to that RIn of the insulating film becomes 0.5-2. The chemical mechanical polishing method uses the aqueous dispersant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous dispersion for chemical mechanical polishing used in the manufacture of semiconductor devices (hereinafter referred to as "aqueous dispersion for chemical mechanical polishing", and may also be abbreviated as "aqueous dispersion". There is). More specifically, in the present invention, in polishing various films to be provided provided on a semiconductor substrate, they can be efficiently polished, and a sufficiently flat and highly accurate finished surface can be obtained. The present invention relates to an aqueous dispersion for chemical mechanical polishing and a chemical mechanical polishing method using the same.

[0002]

2. Description of the Related Art As a recent technology in the manufacture of semiconductor devices, after forming holes or grooves in an insulating film on a process wafer, a barrier metal layer made of a hard metal or the like is formed, and then tungsten, aluminum, In addition, there is a method of forming a wiring by embedding a wiring material such as copper and the like, and then removing the wiring material and the barrier metal layer above the surface of the insulating film by chemical mechanical polishing. Wiring formed by this method is called damascene wiring. There are the following problems in polishing when forming the above damascene wiring. A relatively soft wiring material such as copper is easily polished, and when the width of the wiring portion is wide, the central portion of the wiring is excessively polished, so-called dishing is likely to occur, and a flat finished surface may not be obtained. In addition, the wiring may be disconnected due to scratches or the like. Further, in the case of a porous insulating film having a low dielectric constant, for example, p
If H is low, a sufficient polishing rate cannot be obtained,
If it is high, it will be excessively polished. In any case, it is not easy to suppress the occurrence of scratches. On the other hand, it is not easy to efficiently polish a barrier metal layer made of a metal having high hardness such as tantalum.

Usually, chemical mechanical polishing of a wafer requires another stage of polishing. Most commonly, a two-stage polishing method is employed in which a wiring material such as copper is mainly polished in the first step and a barrier metal layer is mainly polished in the second step. Several methods have been proposed for this two-step polishing, and many aqueous dispersions have been proposed for use therein. As a first method, there is a method in which polishing is performed until copper is completely removed in the first polishing, and then only the barrier metal layer is removed in the second polishing. In this case, there is a problem that dishing that occurs to a considerable extent in the first-stage polishing cannot be corrected by the second-stage polishing mainly for polishing the barrier metal layer, and it may be difficult to form a good damascene wiring. As a second method, in the first-stage polishing, the copper is removed incompletely so that dishing does not occur in the wiring portion, and in the second-stage polishing, the barrier metal layer is removed together with the remaining copper. A method has been proposed. According to this method, when the smoothness of the finished surface is insufficient, or a large amount of time is required to finish polishing,
In some cases, a problem that the cost is further increased occurs.

[0004]

The present invention solves the above-mentioned conventional problems. That is, an aqueous dispersion for chemical mechanical polishing useful in the production of semiconductor devices, which can provide a sufficiently flat finished surface with high precision and can form a good damascene wiring, and a chemical machine using the same. An object of the present invention is to provide a polishing method.

[0005]

In the polishing of a film to be processed provided on a semiconductor substrate, as a result of studying for the purpose of obtaining an aqueous dispersion for chemical mechanical polishing capable of sufficiently flattening a finished surface, When a copper film, a barrier metal layer, and an insulating film are polished under the same conditions, the polishing surface ratio is sufficiently flat when a water-based dispersion having a specific value is used. And reached the present invention.

[0006] The aqueous dispersion for chemical mechanical polishing of the present invention, when the copper film, the barrier metal layer and the insulating film are polished under the same conditions, the polishing rate (R _Cu ) of the copper film and the polishing rate of the barrier metal layer. the ratio of the polishing rate ratio of the _{(R BM) (R Cu /} R BM) is 0.5 to 2, the polishing speed of the polishing rate (R _Cu) and the insulating film of the copper film (R _in) ( R _Cu / R _In ) is 0.
5-2. The aqueous dispersion for chemical mechanical polishing of the present invention is useful as an aqueous dispersion used in a damascene wiring formation step, particularly for the second stage polishing.
The copper forming the “copper film” is not only pure copper, but also copper-
It also includes alloys containing 95% by weight or more of copper, such as silicon and copper-aluminum. The metal forming the “barrier metal layer” includes tantalum, titanium, and the like, and may be a nitride or an oxide thereof. For example, there are tantalum nitride and titanium nitride as nitrides. Further, the above “tantalum, titanium, etc.” is not limited to pure tantalum, pure titanium, for example, tantalum such as tantalum-niobium,
It also includes alloys containing titanium and the like. Furthermore, the above-mentioned "tantalum nitride and titanium nitride" are not limited to pure products. The barrier metal layer is preferably tantalum and / or tantalum nitride.

The above-mentioned insulating film includes, in addition to the SiO ₂ film, an interlayer insulating film having a low dielectric constant for the purpose of improving the performance of the VLSI. Examples of the low dielectric constant insulating film include fluorine-added SiO ₂ (dielectric constant: about 3.3 to 3.5), polyimide resin (dielectric constant: about 2.4 to 3.6, manufactured by Hitachi Chemical Co., Ltd.) Trade name “PIQ”, manufactured by Allied Signal, trade name “FLARE” etc.), benzocyclobutene (dielectric constant: about 2.7, manufactured by Dow Chemical Co., trade name “BCB”)
Etc.), interlayer insulation made of hydrogen-containing SOG (dielectric constant: about 2.5 to 3.5) and organic SOG (dielectric constant: about 2.9, manufactured by Hitachi Chemical Co., Ltd., trade name "HSGR7", etc.) Membrane.

[0008] The above "same conditions" means that a specific type of polishing apparatus is used, the number of rotations of the platen and head, the polishing pressure, the polishing time, the type of polishing pad to be used, and the unit time of the aqueous dispersion per unit time. Means the same supply amount. As for these conditions, appropriate conditions can be adopted as long as they are compared under the same conditions. However, it is desirable to employ actual polishing conditions or conditions close thereto. For example, the platen rotation speed is 30 to 120 rpm, preferably 40 to 120 rpm.
100 rpm, head rotation speed is 30 to 120 rpm
m, preferably 40 to 100 rpm, and the ratio of the platen rotation speed / head rotation speed is 0.5 to 2, preferably 0.7 to 0.7.
1.5, polishing pressure is 100 to 500 g / cm ² ,
Preferably, it is 200 to 350 g / cm ² , and the aqueous dispersion feed rate is 50 to 300 ml / min, preferably 100
Conditions of ~ 200 ml / min can be employed. The "ratio" of the polishing rate can be calculated from the respective polishing rates by separately polishing the copper film, the barrier metal layer, and the insulating film under the same conditions as described above. This polishing,
It can be performed using a wafer provided with a copper film, a barrier metal layer, or an insulating film.

The ratio (R _Cu / R _BM ) of the polishing rate (R _Cu ) of the copper film to the polishing rate (R _BM ) of the barrier metal layer is 0.5 to 0.5.
2, preferably 0.7 to 1.5, particularly preferably 0.8 to 1.2, and more preferably 0.9 to 1.1. When this ratio (R _Cu / R _BM ) is less than 0.5, the copper film is not polished at a sufficient speed, and in the first-stage polishing in the two-stage polishing method, other than grooves or holes on the insulating film. If the removal of the copper film is incomplete, it takes a long time to remove the unnecessary portion of the copper film in the second-stage polishing. On the other hand, the ratio (R _Cu / R _BM )
Exceeds 2, the copper film is excessively polished, causing the occurrence of dishing, and causing a problem that good damascene wiring cannot be formed.

The polishing rate of the copper film (R_Cu) And the insulation film
Polishing rate (R_In) And the ratio (R_Cu/ R _In) Is 0.5-2
But preferably 0.7 to 1.5, especially 0.8 to
1.2, more preferably 0.9 to 1.1.
This R_Cu/ R_InIs over 2, excessive polishing of copper film
This aqueous dispersion is coated on a semiconductor substrate.
When used to polish a processed film, the
High-precision finished surface that is sufficiently flattened
Can not be. On the other hand, R_Cu/ R_InIs less than 0.5
In this case, the insulating film is excessively polished,
Lines cannot be formed.

The present invention makes it clear that at least one of inorganic particles, organic particles and inorganic-organic composite particles can be used as an abrasive. As the inorganic particles, particles made of an oxide of silicon or a metal element such as silica, alumina, ceria, titania, zirconia, iron oxide, and manganese oxide can be used.

The organic particles include (1) a polystyrene and styrene copolymer, (2) a (meth) acrylic resin such as polymethyl methacrylate and an acrylic copolymer,
(3) Polyvinyl chloride, polyacetal, saturated polyester, polyamide, polyimide, polycarbonate, phenoxy resin, and (4) polyolefins and olefins such as polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, etc. Particles made of a thermoplastic resin such as a copolymer can be used.
Further, as the organic particles, those composed of a polymer having a crosslinked structure, obtained by copolymerizing styrene, methyl methacrylate, etc., with divinylbenzene, ethylene glycol dimethacrylate, etc., can also be used. The hardness of the organic particles can be adjusted by the degree of the crosslinking. Further, organic particles made of a thermosetting resin such as a phenol resin, a urethane resin, a urea resin, a melamine resin, an epoxy resin, an alkyd resin, and an unsaturated polyester resin can also be used. Each of these inorganic particles and organic particles may be used alone or in combination of two or more.

The inorganic-organic composite particles are only required to be integrally formed so that the inorganic particles and the organic particles are not easily separated at the time of polishing, and the type, constitution and the like are not particularly limited.
As the composite particles, polysiloxane, aluminum alkoxide, titanium alkoxide, or the like is polycondensed in the presence of polymer particles such as polystyrene and polymethyl methacrylate, and at least the surface of the polymer particles has polysiloxane or the like bonded thereto. Things can be used. The resulting polycondensate may be directly bonded to a functional group of the polymer particles, or may be bonded via a silane coupling agent or the like. In addition, the polycondensate does not necessarily need to be chemically bonded to the polymer particles, particularly in a state where the three-dimensionally grown polycondensate is physically held on the surface of the polymer particles. There may be. In addition, silica particles, alumina particles and the like can be used instead of alkoxysilane and the like. These may be held intertwined with polysiloxane or the like, or may be chemically bonded to the polymer particles by a functional group such as a hydroxyl group contained in them.

As the composite particles, it is possible to use an aqueous dispersion containing inorganic particles and organic particles having different zeta potentials, which particles are combined by electrostatic force. The zeta potential of the polymer particles is
Although it is often negative over a wide range excluding the H range or the low pH range, the polymer particles having a carboxyl group, a sulfonic acid group, etc., make it possible to more surely obtain a polymer having a negative zeta potential. It can be a united particle. In addition, by making the polymer particles having an amino group and the like,
Polymer particles having a positive zeta potential in a specific pH range can also be obtained. On the other hand, the zeta potential of the inorganic particles is highly pH-dependent, and has an isoelectric point at which this potential becomes 0,
Before and after that, the sign of the zeta potential is reversed. Therefore, by combining specific inorganic particles and organic particles and mixing them in a pH range where the zeta potential has the opposite sign, the inorganic particles and the organic particles can be integrally compounded by electrostatic force. In addition, even when the zeta potential has the same sign during mixing, the inorganic particles and the organic particles can be integrated by changing the pH and setting the zeta potential to the opposite sign.

Further, as the composite particles, in the presence of the particles which are integrally composited by the electrostatic force, as described above, the alkoxysilane, the aluminum alkoxide,
Titanium alkoxide or the like may be polycondensed, and at least the surface of the particles may be further combined with a polysiloxane or the like to form a composite.

The average grain size of the abrasive grains is preferably 0.01 to 3 μm. If the average particle size is less than 0.01 μm, an aqueous dispersion having a sufficiently high polishing rate may not be obtained. On the other hand, the average grain size of the abrasive grains is 3 μm
If the average particle diameter exceeds the range, the abrasive grains settle and separate, and it is not easy to obtain a stable aqueous dispersion. This average particle size is 0.05 to 1.0 μm, and further 0.1 to 0.7 μm
m is more preferable. An abrasive having an average particle diameter in this range can provide a stable aqueous dispersion for CMP having a sufficient polishing rate and without causing sedimentation and separation of particles. In addition, this average particle diameter can be measured by observing with a transmission electron microscope.

Further, the content of the abrasive grains is 10
0 parts by weight (hereinafter abbreviated as “parts”),
0.05 to 30 parts, preferably 0.1
It is preferably from 20 to 20 parts, particularly from 0.5 to 10 parts, and more preferably from 1 to 7 parts. When the content of the abrasive grains is less than 0.05 part, the polishing rate becomes insufficient. On the other hand, when the content exceeds 30 parts, the cost is increased and the stability of the aqueous dispersion is undesirably reduced. It is preferable that the shape of the inorganic particles, organic particles, and composite particles functioning as the abrasive grains is spherical. The spherical shape also means a substantially spherical shape having no acute angle portion, and does not necessarily need to be close to a true sphere. By using spherical abrasive grains, polishing can be performed at a sufficient speed, and generation of scratches and the like on the surface to be polished can be suppressed.

The aqueous dispersion of the present invention achieves the above specific polishing rate ratio by containing a polishing rate adjusting component. Such polishing rate adjusting components may include organic acids, and include a wide range of common organic acids such as monofunctional acids, disensitizing acids, viloxyl / carboxylate acids, chelating acids, and non-chelating acids. Acids can be used. Preferred organic acids are acetic acid, adipic acid, butyric acid, capric acid, caproic acid, caprylic acid, citric acid,
Glutaric acid, glycolic acid, formic acid, fumaric acid, lactic acid, lauric acid, malic acid, maleic acid, malonic acid, myristic acid, oxalic acid, palmitic acid, phthalic acid, propionic acid, pyruvic acid, stearic acid, succinic acid, tartaric acid , Balearic acid, and mixtures thereof.

When the organic acid is added to the aqueous dispersion, the dissociation portion may or may not be dissociated. When the organic acid is a divalent or higher polyacid, the dissociation portion may be monovalent or higher. In addition, the cation of the pair of the dissociation portion may be any of a hydrogen ion and a cation derived from an optionally added additive such as an ammonium ion and a potassium ion. Further, the organic acid may be added as an organic acid ion (organic acid salt). In this case, when the organic acid is a divalent or higher polyacid, the dissociation portion is monovalent. Or more. The pair of cations in the dissociation part is a hydrogen ion,
Other cations derived from optionally added additives, such as ammonium ions and potassium ions, may be used.

Of the above organic acids, maleic acid is particularly preferred. The maleic acid dissociates substantially in its entirety in the aqueous dispersion to produce a maleate ion and a counter cation. Here, the paired cation may be a hydrogen ion or a cation derived from an optionally added additive such as an ammonium ion or a potassium ion, but is preferably a potassium ion. The concentration of the maleate ion is preferably from 0.005 to 1 mol / l, particularly preferably from 0.01 to 0.5 mol / l. In order to realize the maleic acid ion concentration range, the addition amount of maleic acid may be set to 0.06 to 11.6% by mass, particularly 0.1 to 5.8% by mass. When the concentration of maleate ions is less than 0.005 mol / liter, the polishing rate of the copper film and the barrier metal may be insufficient. On the other hand, when the concentration of maleate ion exceeds 1 mol / liter, the surface to be polished may be corroded, and a highly accurate and good finished surface may not be obtained. In addition, the concentration of the maleate ion can be measured by ion chromatography.

Potassium ions generated as a pair of cations and the like also have an effect of improving the polishing rate, and an aqueous dispersion having a higher polishing rate can be obtained. The concentration of the potassium ion can be an appropriate concentration, but is preferably 0.01 to 2 mol / l, more preferably 0.02 mol / l.
１1 mol / liter. In this case, if the potassium ion concentration is less than 0.01 mol / l, the effect of improving the polishing rate may not be sufficiently exhibited, while if it exceeds 2 mol / l, scratches may easily occur. In order to generate the above maleate ions and potassium ions, it is most convenient and effective to use potassium maleate. As potassium ions, in addition to those generated from potassium maleate, those generated from potassium hydroxide or the like used for adjusting the pH of the aqueous dispersion, and those derived from other optionally added additives are included. Is also good.

The aqueous dispersion of the present invention preferably contains an oxidizing agent. By containing the oxidizing agent, the polishing rate is improved. As the oxidizing agent, a wide range of oxidizing agents can be used. Suitable oxidizing agents include oxidizing metal salts, oxidizing metal complexes, and nonmetallic oxidizing agents such as peracetic acid, periodate, and iron ions. For example, nitrate, sulfate, EDT
A, citrate, potassium ferricyanide and the like, aluminum salt, sodium salt, potassium salt, ammonium salt, quaternary ammonium salt, phosphonium salt, or other cationic salts of peroxides, chlorates, chlorinates,
Nitrate, manganate, persulfate, and mixtures thereof.

As the "oxidizing agent", hydrogen peroxide is particularly preferred. Hydrogen peroxide is at least partially dissociated to generate hydrogen peroxide ions. In addition, "hydrogen peroxide" means what contains the above-mentioned hydrogen peroxide ion in addition to molecular hydrogen peroxide. The concentration of hydrogen peroxide in the above can be arbitrarily set in the range of 0.01 to 5.0% by mass, but is more preferably 0.05 to 3.0% by mass, and more preferably 0.07 to 1.0% by mass. It is particularly preferable to set the amount to 0% by mass. If the concentration of hydrogen peroxide is less than 0.01% by mass, it may not be possible to polish at a sufficient speed,
On the other hand, if it exceeds 5.0% by mass, the polished surface may be corroded.

The aqueous dispersion of the present invention may contain a polyvalent metal ion which has an effect of promoting the function of hydrogen peroxide as an oxidizing agent and can further improve the polishing rate. Examples of the polyvalent metal ions include metal ions such as aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, germanium, zirconium, molybdenum, tin, antimony, tantalum, tungsten, lead, and cerium. Is mentioned. These may be only one kind or two or more kinds of polyvalent metal ions may coexist. The content of the polyvalent metal ion can be 3000 ppm or less, particularly 10 to 2000 ppm, based on the aqueous dispersion. The polyvalent metal ion can be formed by mixing a salt or a complex such as nitrate, sulfate, acetate or the like containing a polyvalent metal element in an aqueous medium, and is formed by mixing an oxide of the polyvalent metal element. It can also be done. In addition, even if a compound which is mixed with an aqueous medium and generates a monovalent metal ion, a compound in which this ion becomes a polyvalent metal ion by an oxidizing agent can be used. Among various salts and complexes, iron nitrate, which is particularly excellent in the action of improving the polishing rate, is preferable.

The pH of the aqueous dispersion of the present invention is preferably from 8 to 11, more preferably from 8.5 to 10.5, particularly preferably from 9 to 10. This pH adjustment can be performed with an acid such as nitric acid or sulfuric acid, or an alkali such as potassium hydroxide, sodium hydroxide or ammonia. If the pH of the aqueous dispersion is less than 8, etching of a film to be processed such as copper is strong, and dishing and erosion may easily occur. On the other hand, this pH
Exceeds 11, the insulating film may be excessively polished, resulting in a problem that a good wiring pattern cannot be obtained.

The aqueous dispersion of the present invention is useful in the second polishing step of the two-step polishing. In the first polishing step, R _Cu / R _BM is 20 or more, especially 40 or more, and 50 or more.
It is particularly useful in the second polishing step when the above aqueous dispersion is used. When the aqueous dispersion of the present invention is used in the one-step polishing method and / or when used in the first step of the two-step polishing method, it takes a long time for polishing and also requires a large amount of the aqueous dispersion. Therefore, it may be economically disadvantageous. When the aqueous dispersion of the present invention is used in the second stage of the two-stage polishing method, the aqueous dispersion used for the first stage polishing has an R _Cu / R _BM of 20.
If it is less than 1 hour, a large amount of time is required for the first polishing and a large amount of aqueous dispersion is required, which is not preferable.

Polishing of a film to be processed and a barrier metal layer of a semiconductor device is performed by using a commercially available chemical mechanical polishing apparatus (for example, LGP51).
0, LGP552 (above, manufactured by Lapmaster SFT Co., Ltd.), EPO-113, EPO-222 (above, manufactured by Ebara Corporation), Mirra (manufactured by Applied Materials), AVANTI-472 (manufactured by AIPEC)
Etc.). In this polishing,
After polishing, it is preferable to remove the abrasive remaining on the surface to be polished. The removal of the abrasive can be carried out by a usual cleaning method. In the case of organic particles, the surface to be polished can be removed by burning the particles by raising the temperature in the presence of oxygen. Examples of the method of combustion include ashing with plasma, such as exposure to oxygen plasma or supply of oxygen radicals in a downflow manner, so that residual organic particles can be easily removed from the surface to be polished. it can.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail by way of examples. [1] Preparation of Aqueous Dispersion Containing Abrasive Grains (1) Preparation of Aqueous Dispersion Containing Inorganic Particles Preparation of Aqueous Dispersion Containing Fumed Silica or Fumed Alumina 100 g of a 2 liter polyethylene bottle After adding fumed silica particles (manufactured by Nippon Aerosil Co., Ltd., trade name “Aerosil # 90”) and fumed alumina particles (manufactured by Degussa, trade name “Aluminium Oxide C”), ion-exchanged water is put into the vessel, and the total volume Was set to 1000 g. Next, the particles were dispersed by an ultrasonic disperser, and 10
An aqueous dispersion containing a part of fumed silica particles or fumed alumina particles was prepared.

Preparation of Aqueous Dispersion Containing Colloidal Silica In a flask having a capacity of 2 liters, 70 g of 25 mass% ammonia water, 40 g of ion-exchanged water, 175 g of ethanol and 21 g of tetraethoxysilane were charged, and the mixture was heated to 60 ° C. while stirring at 180 rpm. After the temperature was raised and stirring was continued for 2 hours at this temperature, the mixture was cooled to obtain a colloidal silica / alcohol dispersion having an average particle size of 0.23 μm. Next, an operation of removing the alcohol content by adding an ion-exchanged water to the dispersion at a temperature of 80 ° C. by an evaporator was performed several times to remove the alcohol in the dispersion, and to remove water having a solid concentration of 8% by mass. A dispersion was obtained.

(2) Preparation of Water Dispersion Containing Composite Particles Water Dispersion Containing Polymer Particles 90 parts of methyl methacrylate, methoxypolyethylene glycol methacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.
Product name "NK Ester M-90G", # 400) 5 parts,
5 parts of 4-vinylpyridine, 2 parts of an azo-based polymerization initiator (trade name “V50”, manufactured by Wako Pure Chemical Industries, Ltd.) and 400 parts of ion-exchanged water are charged into a flask having a capacity of 2 liters, and placed under a nitrogen gas atmosphere. The temperature was raised to 70 ° C. with stirring, and the polymerization was carried out for 6 hours. As a result, an aqueous dispersion containing polymethyl methacrylate-based particles having a cation of an amino group and a functional group having a polyethylene glycol chain and having an average particle diameter of 0.15 μm was obtained. The polymerization yield was 95%.

100 parts of an aqueous dispersion containing 10% by weight of the polymethyl methacrylate-based particles obtained in the aqueous dispersion containing the composite particles was charged into a 2 liter flask, and 1 part of methyltrimethoxysilane was added. Stirred at 40 ° C. for 2 hours. Then, p with nitric acid
H was adjusted to 2 to obtain an aqueous dispersion (a). Further, the pH of an aqueous dispersion containing 10% by mass of colloidal silica (trade name “Snowtex O” manufactured by Nissan Chemical Industries, Ltd.) was adjusted to 8 with potassium hydroxide to obtain an aqueous dispersion (b). The zeta potential of the polymethyl methacrylate-based particles contained in the aqueous dispersion (a) was +17 mV, and the zeta potential of the silica particles contained in the aqueous dispersion (b) was -40 mV.

Thereafter, 50 parts of the aqueous dispersion (b) were gradually added to 100 parts of the aqueous dispersion (a) over 2 hours, and mixed.
After stirring for an hour, an aqueous dispersion containing preliminary particles in which silica particles adhered to polymethyl methacrylate-based particles was obtained. Next, 2 parts of vinyltriethoxysilane was added to the aqueous dispersion, and the mixture was stirred for 1 hour. 1 part of tetraethoxysilane was added, the temperature was raised to 60 ° C., and stirring was continued for 3 hours.
By cooling, an aqueous dispersion containing the composite particles was obtained. The average particle diameter of the composite particles was 180 nm, and silica particles were attached to 80% of the surface of the polymethyl methacrylate-based particles.

[2] Preparation of Chemical-Mechanical Polishing Aqueous Dispersion Example 1 The aqueous dispersion containing fumed silica prepared in [1] and (1) was mixed with fumed silica in an amount of 5 parts. In addition, potassium maleate and hydrogen peroxide were
It was mixed with ion-exchanged water to a concentration of 0.1% by mass and 0.1% by mass, and the pH was adjusted to 9.5 with potassium hydroxide to obtain an aqueous dispersion for CMP.

Examples 2 to 9 Example 1 was repeated except that the types and mixing amounts of the abrasive grains and the mixing amounts of potassium maleate and hydrogen peroxide were as shown in Table 1.
In the same manner as in the above, an aqueous dispersion for CMP having a specific pH was obtained.

Comparative Example 1 An aqueous dispersion for CMP having a specific pH was obtained in the same manner as in Example 1 except that no polishing rate adjusting component was added. Comparative Examples 2 to 6 Example 1 except that the types and mixing amounts of the abrasive grains, the polishing rate adjusting component, and the mixing amount of hydrogen peroxide were changed as shown in Table 2.
In the same manner as in the above, an aqueous dispersion for CMP having a specific pH was obtained. However, in Comparative Example 5, the specific pH was adjusted using nitric acid instead of potassium hydroxide.

As described above, using the aqueous dispersions for chemical mechanical polishing of Examples 1 to 9 and Comparative Examples 1 to 6, a wafer with an 8-inch copper film, a wafer with an 8-inch titanium film, a wafer with an 8-inch tantalum nitride film, and 8 inch plasma TEO
The wafer with the S film was polished. The results are shown in Tables 1 and 2.

Using a model "LGP-510" manufactured by Lapp Master Co., Ltd. as a polishing apparatus, the film provided on each wafer was polished under the following conditions, and the polishing rate was calculated by the following equation. Table rotation speed: 50 rpm, head rotation speed: 50 rpm
m, polishing pressure: 300 g / cm ² , supply rate of aqueous dispersion: 100 ml / min, polishing time: 1 minute, polishing pad: manufactured by Rodale Nitta Co., Ltd., product number IC1000 / SUB
Polishing rate (構造 / min) = (thickness of each film before polishing−thickness of each film after polishing) / polishing time

The thickness of each film is measured by using a resistivity meter (NPS).
The sheet resistance was measured by a direct current four-probe method using a model “Σ-5” manufactured by the company and calculated from the sheet resistance value and the resistivity of copper, tantalum, tantalum nitride or plasma TEOS by the following equation. Thickness of each film (Å) = [sheet resistance (Ω / cm ² ) x
Resistivity of copper, tantalum, tantalum nitride, or plasma TEOS (Ω / cm)] × 10 ^{8 For} evaluation of scratches on the copper film, spotlight was irradiated in a dark room, and the presence or absence of scratches was confirmed visually.
Evaluation of scratches on the insulating film was performed by taking a photograph with a differential interference microscope and counting the number of scratches in a visual field of 100 μm × 100 μm.

[0039]

[Table 1]

[0040]

[Table 2]

According to the results shown in Table 1, in the aqueous dispersions of Examples 1 to 9 in which 1 to 3 parts of potassium maleate and 0.1 to 3 parts of hydrogen peroxide were mixed, a copper film, a tantalum film and And / or the ratio of the polishing rate with the tantalum nitride film (R _Cu / R _BM ) and the ratio of the polishing rate with the copper film and the insulator (R _Cu / R _In ) are all within the range of 0.5 to 2. Met. In particular, in Examples 4 to 6 using composite particles or a mixture of composite particles and fumed silica as the abrasive, R _Cu / R _BM and R _Cu / R _in were 0.8 to
1.2, and the scratches of the copper film and the insulating film were very small, indicating that a sufficiently flat and highly accurate finished surface could be obtained.

On the other hand, according to the results in Table 2, Comparative Examples 1 to 5
Then, the polishing rate ratio (R _Cu / R _BM ) between the copper film and the tantalum film and / or the tantalum nitride film and the polishing rate ratio (R _Cu / R _In ) between the copper film and the insulator are extremely high. Large or very small values indicate a poorly planarized finished surface. In Comparative Example 6 using the first-stage aqueous dispersion of R _Cu / R _BM = 100, although the polishing rate R _Cu of the copper film was large, the polishing of the copper film and the tantalum film and / or the tantalum nitride film was performed. The rate ratio (R _Cu / R _BM ) and the ratio of the polishing rate between the copper film and the insulator (R _Cu / R _In ) were small, indicating that only a finished surface with insufficient planarization was obtained. .

Example 10 5 and 10 at a depth of 1 μm were formed on the surface of a silicon substrate.
An insulating film having a pattern formed by grooves having widths of 25, 50, 75, and 100 μm was laminated. Then
A TaN film having a thickness of 300 ° was formed on the surface of the insulating film, and then copper was deposited to a thickness of 1.3 μm in a groove covered with the TaN film by sputtering and plating to produce a wafer. Model "LG" manufactured by Wrapmaster SFT Co., Ltd.
Using P-510, the wafer prepared above was polished in two stages under the following conditions. However, in the first-stage polishing, a fumed silica-based aqueous dispersion (R _Cu / R _BM = 30) was used as the aqueous dispersion, and polishing was performed for 3 minutes. Polishing was performed using the same aqueous dispersion as used until the remaining copper and TaN were completely removed. Table rotation speed: 50 rpm, head rotation speed: 50 rpm
m, polishing pressure: 300 g / cm ² , supply rate of aqueous dispersion: 100 ml / min, polishing pad: 2-layer structure of product number IC1000 / SUBA400 manufactured by Rodale Nitta Co., Ltd. After polishing is completed, a surface roughness meter (KLA-Tencor) is used. Company
The dishing in a copper wiring having a width of 100 μm was measured using a type “P-10”) and found to be 450 °.

Example 11 Example 10 was repeated except that the same aqueous dispersion used in Example 6 was used as the aqueous dispersion for polishing in the second stage.
Polishing was performed in the same manner as described above, and dishing in a 100 μm copper wiring was measured. The dishing in the 100 μm copper wiring after polishing was 470 °.

Comparative Example 7 Example 10 was repeated except that the same aqueous dispersion as that used in Comparative Example 3 was used as the second aqueous dispersion for polishing.
Polishing was performed in the same manner as described above, and dishing in a 100 μm copper wiring was measured. The dishing in the 100 μm copper wiring after polishing was 3500 °.

As described above, in Examples 10 and 11 according to the polishing method of the present invention, the dishing in the 100 μm copper wiring after the polishing was completed was less than 500 °, and a sufficiently flat and highly accurate finished surface was obtained. Was. On the other hand, in Comparative Example 7, dishing in the 100 μm copper wiring after polishing was as large as 3500 °, and only a finished surface with insufficient flattening was obtained.

[0047]

According to the present invention, the ratio of the polishing speed between the copper film and the barrier metal layer and the ratio between the polishing speed between the copper film and the insulating film are specified, so that the film to be processed can be formed at an appropriate speed. An aqueous dispersion for chemical mechanical polishing useful in the manufacture of semiconductor devices, which can be polished to the same extent and does not cause scratching or dishing, can be obtained. Further, there is provided a chemical mechanical polishing method capable of obtaining a sufficiently flat finished surface with high precision by using the chemical mechanical polishing aqueous dispersion.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09K 13/00 C09K 13/00 (72) Inventor Nobuo Kawabashi 2-11-24 Tsukiji 2-chome, Chuo-ku, Tokyo J F Co., Ltd. F term (reference) 3C058 AA07 CB01 CB02 CB03 CB05 DA02 DA12 DA17

Claims (8)

[Claims] When a copper film, a barrier metal film, and an insulating film are polished under the same conditions, a ratio of a polishing speed (R _Cu ) of the copper film to a polishing speed (R _BM ) of the barrier metal film (R _BM ) R _Cu / R _BM) is 0.5 to 2, the ratio (R _Cu / R of the polishing rate of (R _Cu) and the insulating film of the copper film (R _{an in)
In} ) is 0.5 to 2, wherein the chemical mechanical polishing aqueous dispersion is used for manufacturing a semiconductor device. 2. The chemical mechanical polishing aqueous dispersion according to claim 1, wherein the barrier metal film is tantalum and / or tantalum nitride. 3. The method according to claim 1, further comprising at least an abrasive, water and a polishing rate adjusting component.
The aqueous dispersion for chemical mechanical polishing according to the above. 4. The chemical mechanical polishing aqueous dispersion according to claim 3, wherein the abrasive is at least one of inorganic particles, organic particles and inorganic-organic composite particles. 5. The chemical mechanical polishing aqueous dispersion according to claim 3, wherein the polishing rate adjusting component is maleate ion. 6. The method according to claim 1, wherein the concentration of the maleate ion is 0.005 to
The chemical mechanical polishing aqueous dispersion according to claim 5, wherein the amount is 1 mol / liter. 7. The chemical mechanical polishing aqueous dispersion according to claim 1, which has a pH of 8 to 11. 8. A chemical mechanical polishing aqueous dispersion having a ratio (R _Cu / R _BM ) of a polishing rate (R _Cu ) of a copper film to a polishing rate (R _BM ) of a barrier metal film of 20 or more is first used. Used as a chemical mechanical polishing aqueous dispersion for the second stage polishing, the chemical mechanical polishing aqueous dispersion according to any one of claims 1 to 7 as a chemical mechanical polishing aqueous dispersion for the second stage polishing. A chemical mechanical polishing method used for manufacturing a semiconductor device, characterized by using the method.