JP4984032B2 - Chemical mechanical polishing aqueous dispersion and chemical mechanical polishing method - Google Patents

Description

  The present invention relates to a chemical mechanical polishing aqueous dispersion, a chemical mechanical polishing method, and a kit for preparing the chemical mechanical polishing aqueous dispersion. More specifically, it can be used in a process of forming a copper wiring formed in an interlayer insulating layer having a two-layer structure of a low dielectric constant insulating layer / high dielectric constant insulating layer of a semiconductor device, and various kinds of devices provided on a semiconductor substrate. Chemical mechanical polishing aqueous dispersion capable of effectively chemically mechanically polishing a material to be polished and capable of obtaining a sufficiently flat and highly accurate finished surface, and a chemical mechanical polishing method using the same And a kit for preparing the chemical mechanical polishing aqueous dispersion.

  In recent years, with the increase in the density of semiconductor devices, the miniaturization of wirings formed in the semiconductor devices has progressed. As a technique that can achieve further miniaturization of the wiring, a technique called a damascene method is known. This method forms a desired wiring by embedding a wiring material in a groove or the like formed in an insulating layer and then using chemical mechanical polishing to remove excess wiring material deposited other than the groove. It is. Here, when using copper or copper alloy as the wiring material, in order to avoid migration of copper atoms into the insulator, usually tantalum, tantalum nitride, titanium nitride, etc. are used at the interface between the copper or copper alloy and the insulator. A high-strength, high-dielectric-constant insulating layer (conductive barrier layer) is formed as a material.

  When the damascene method is employed in the manufacture of a semiconductor device using copper or a copper alloy as a wiring material, there are various chemical mechanical polishing methods, and a first polishing step for mainly removing copper or a copper alloy and a mainly conductive method. A two-stage chemical mechanical polishing comprising a second polishing step for removing the conductive barrier layer is preferably performed. This second polishing step not only removes the conductive barrier layer but also polishes the interlayer insulating layer existing under the conductive barrier layer at the same time. Can be obtained.

  In addition, as the miniaturization progresses further, the copper wiring width becomes very narrow, and sufficient electrical characteristics cannot be obtained only by using a low resistance copper wiring, and the dielectric constant is low as an interlayer insulating layer. A wiring structure using a low dielectric constant material (Low-k material) has been applied. In particular, by using a low dielectric constant material having a relative dielectric constant (k) of less than 2.5, it is possible to reduce the electric capacity applied to the interlayer insulating layer between the copper wirings. Electrical characteristics can be maximized. In addition, when a layer is formed using a low dielectric constant material, a large number of holes can be created in the material. Therefore, by adjusting the ratio and size of the holes, the relative dielectric constant of the layer can be adjusted. Can do.

  If the percentage of holes is large, the relative dielectric constant of the layer can be made very low, but the mechanical strength of the material tends to be very weak, so that the resulting layer is subjected to chemical mechanical polishing. There is a possibility that the strength that can withstand the stress applied to the substrate cannot be maintained.

  In addition, since the above-described low dielectric constant insulating layer having holes has a large ratio of holes, the film is easily damaged by chemical mechanical polishing. When such damage occurs in the low-k film, the electrical characteristics of the low dielectric constant insulating layer such as an increase in the dielectric constant and an increase in leakage current after the manufacturing process such as etching, ashing, or wet cleaning are obtained. It may get worse. Such deterioration of electrical characteristics results in deterioration of the reliability of the semiconductor device, which is not preferable.

  As in the above-described technique, when using a hard silicon dioxide film having a high relative dielectric constant and an interlayer insulating layer in the second polishing step, surface defects are not generated on the surface to be polished, and relatively high accuracy is achieved. Flattening is possible.

  However, when a low dielectric constant insulating layer having a low mechanical strength is used, (i) peeling or surface defects called scratches are generated on the surface to be polished by chemical mechanical polishing, and (ii) a fine wiring structure. The polishing rate of the low dielectric constant insulating layer, which is the material to be polished, is remarkably increased when polishing a wafer having the following characteristics: (iii) a barrier layer and A coating film called a cap layer made of silicon dioxide or the like is formed on the upper layer of the low dielectric constant insulating layer for reasons such as poor adhesion to the low dielectric constant insulating layer. / (Upper layer) A method of forming an interlayer insulating layer having a two-layer structure called a high dielectric constant insulating layer (an insulating layer having a higher relative dielectric constant than a low dielectric constant insulating layer) is used.

  When chemical mechanical polishing is performed, it is necessary to quickly remove the high dielectric constant insulating layer as an upper layer and suppress the polishing rate of the lower low dielectric constant insulating layer as much as possible. That is, the polishing rate (RR1) of the high dielectric constant insulating layer and the polishing rate (RR2) of the low dielectric constant insulating layer are required to have a relationship of RR1> RR2.

  When polishing a low dielectric constant insulating layer, not only the polishing rate is suppressed, but also the physical properties (specific dielectric constant, leakage current value, etc.) of the surface to be polished must not be changed. As the miniaturization progresses, it is necessary to further reduce the relative dielectric constant of the low dielectric constant insulating layer, and accordingly, the hole diameter of the material must be increased. As the pore size of the low dielectric constant insulating layer increases, not only does the low dielectric constant insulating layer become brittle, but the physical properties of the low dielectric constant insulating layer may change due to chemical mechanical polishing. A technique for suppressing the polishing rate without changing the thickness is required.

  Thus, since the second polishing step corresponds to a so-called finishing step, in the second polishing step, it is possible to suppress material peeling and surface defects on the fragile surface to be polished, and to physically treat the surface to be polished. A chemical mechanical polishing aqueous dispersion capable of suppressing the polishing rate without changing the properties is required.

  The second polishing step is mainly intended to remove the high dielectric constant insulating layer. From the viewpoint of shortening the polishing process time, it is necessary to have a high polishing rate for the surface to be polished. If it is increased, material peeling or surface defects will occur on the brittle polished surface. In addition, as described above, when a hard cap layer is formed on the low dielectric constant insulating layer, it is necessary to have a high polishing rate for the silicon dioxide film. Therefore, in order to obtain a highly polished surface, it is necessary to polish a high dielectric constant insulating layer at a low polishing pressure, and a high polishing rate for a high dielectric constant insulating layer and a silicon dioxide film even under a low polishing pressure. Is required.

  As a specific example, Patent Document 1 discloses a polishing composition for an alkaline region containing abrasive grains made of silicon oxide, an oxidizing agent, and carbonate. When this polishing liquid is used, the polishing rate of the high dielectric constant insulating layer can be sufficiently obtained, but the polishing rate of the low dielectric constant insulating layer cannot be sufficiently suppressed. If formed, a sufficient polishing rate cannot be obtained for the silicon dioxide film, and the polishing process time becomes long, leading to a reduction in throughput.

Further, Patent Document 2 discloses a polishing composition containing a specific polyether-modified silicone and various additives. By using this polishing liquid, low dielectric constant insulation is achieved by the effect of the polyether-modified silicone. It is disclosed that the polishing rate of the layer can be sufficiently suppressed. However, the film to be polished by the polishing liquid is made of a material having a relative dielectric constant of 2.8, a high dielectric constant, a high mechanical strength, and a physical property that hardly changes. Therefore, when such a polishing liquid is used to polish a low dielectric constant insulating layer having a structure in which pores are present in the film (for example, a layer having a relative dielectric constant of 2.4 or less), the low dielectric constant insulating layer In addition to mechanical damage, the physical properties of the low dielectric constant insulating layer are changed, so that it is not suitable as a polishing liquid used in the second polishing step.
JP 2000-248265 A JP 2005-129637 A

  The object of the present invention has been made in view of the above circumstances, and surface defects such as material peeling and scratches are not polished when the insulating layer is chemically mechanically polished without changing the physical properties of the insulating layer. An aqueous dispersion for chemical mechanical polishing capable of obtaining a highly accurate polished surface without being generated on the surface, a chemical mechanical polishing method using the same, and a kit for preparing the aqueous dispersion for chemical mechanical polishing are provided. It is to be.

The chemical mechanical polishing aqueous dispersion according to the first aspect of the present invention comprises:
(A) Abrasive grain, (B) C4 or higher aliphatic organic acid, (C) oxidizing agent, (D) nonionic surfactant represented by the following general formula (1), and (E) dispersion Contains medium.

・・・・・（１）
（式中、ｎおよびｍはそれぞれ独立に１以上の整数であり、ｎ＋ｍ≦５０を満たす。）

(1)
(In the formula, n and m are each independently an integer of 1 or more and satisfy n + m ≦ 50.)

  In the chemical mechanical polishing aqueous dispersion, the (A) abrasive grains may be inorganic particles having a primary particle diameter of 60 to 90 nm and an association degree of 1.5 to 4.

  In the chemical mechanical polishing aqueous dispersion, the (C) oxidizing agent may be hydrogen peroxide.

  In the chemical mechanical polishing aqueous dispersion, the ratio of the blended amount of the (B) aliphatic organic acid having 4 or more carbon atoms to the blended amount of the (D) nonionic surfactant is 0.1 to 10. be able to.

In the chemical mechanical polishing aqueous dispersion, when each of the copper layer, the barrier metal layer, the first insulating layer, and the second insulating layer having a higher dielectric constant than the first insulating layer is subjected to chemical mechanical polishing under the same conditions, polishing rate of the barrier metal layer _{(R B)} and the polishing rate of the copper layer _{(R M)} and the polishing rate ratio _(R B / _{R M)} is not less than 1.5, the polishing rate of the second insulating layer (R _In-2 ) and the polishing rate (R _M ) between the polishing rate of the copper layer (R _In-2 / R _M ) are 0.9 to 2.5, and the polishing rate of the second insulating layer The polishing rate ratio (R _In-2 / R _In-1 ) between (R _In-2 ) and the polishing rate (R _In-1 ) of the first insulating layer may be 0.5-5.

The method for producing the chemical mechanical polishing aqueous dispersion according to the second aspect of the present invention comprises:
A first polishing step that is provided on the insulating layer having a recess via a stopper layer, and chemically and mechanically polishes the metal layer embedded in the recess until the stopper layer is exposed;
A second polishing step of using the chemical mechanical polishing aqueous dispersion to perform chemical mechanical polishing of the metal layer and the stopper layer until the insulating layer is exposed.

In the method for producing the chemical mechanical polishing aqueous dispersion,
The insulating layer includes a laminate of a first insulating layer and a second insulating layer having a dielectric constant higher than that of the first insulating layer,
The second polishing step may be a step of chemical mechanical polishing the metal layer, the stopper layer, and the second insulating layer.

  In this case, the relative dielectric constant of the first insulating layer may be 3.5 or less. In this case, the stopper layer may be a conductive barrier layer.

A kit for preparing the chemical mechanical polishing aqueous dispersion according to the third aspect of the present invention comprises:
A kit for preparing the chemical mechanical polishing aqueous dispersion by mixing the liquid (I) and the liquid (II),
The liquid (I) includes (A) abrasive grains, (B) an aliphatic organic acid having 4 or more carbon atoms, (D) a nonionic surfactant represented by the above general formula (1), and (E) An aqueous dispersion containing a dispersion medium,
The liquid (II) contains (C) an oxidizing agent.

The kit for preparing the chemical mechanical polishing aqueous dispersion according to the fourth aspect of the present invention comprises:
A kit for preparing the chemical mechanical polishing aqueous dispersion by mixing the liquid (I) and the liquid (II),
The liquid (I) is an aqueous dispersion containing (A) abrasive grains and (E) a dispersion medium,
The liquid (II) contains (B) an aliphatic organic acid having 4 or more carbon atoms, (C) an oxidizing agent, and a nonionic surfactant represented by the general formula (1).

The kit for preparing the chemical mechanical polishing aqueous dispersion according to the fifth aspect of the present invention comprises:
A kit for mixing the liquid (I), the liquid (II), and the liquid (III) to prepare the chemical mechanical polishing aqueous dispersion,
The liquid (I) is an aqueous dispersion containing (A) abrasive grains and (E) a dispersion medium,
The liquid (II) includes (B) an aliphatic organic acid having 4 or more carbon atoms and (D) a nonionic surfactant represented by the general formula (1).
The liquid (III) contains (C) an oxidizing agent.

  In the kit for preparing the chemical mechanical polishing aqueous dispersion, the liquid (I) comprises (B) an aliphatic organic acid having 4 or more carbon atoms, (C) an oxidizing agent, and (D) the above general formula ( One or more components selected from the nonionic surfactants represented by 1) can be further included.

  By performing chemical mechanical polishing of the insulating layer using the above-mentioned chemical mechanical polishing aqueous dispersion, when the insulating layer is chemically mechanically polished, the physical properties of the insulating layer are not changed, and material peeling or scratching can be performed. A surface to be polished with high accuracy can be obtained without causing surface defects on the surface to be polished.

  For example, when chemical mechanical polishing is performed on a semiconductor substrate including an insulating layer having a low mechanical strength (for example, an insulating layer having a relative dielectric constant of 3.5 or less) as an interlayer insulating layer using the chemical mechanical polishing aqueous dispersion. In addition, it is possible to obtain a polished surface with high accuracy without causing surface defects such as material peeling or scratches on the polished surface without changing the physical properties of the insulating layer, and The polishing rate can be sufficiently suppressed. In particular, the chemical mechanical polishing aqueous dispersion is useful when used as an abrasive in the second polishing step when performing the two-step polishing process by the damascene method described above.

  Embodiments of the present invention will be described below with reference to the drawings.

  In addition, this invention is not limited to the following embodiment, Various modifications implemented in the range which does not change the summary of this invention are included.

1. Chemical mechanical polishing aqueous dispersion The chemical mechanical polishing aqueous dispersion of one embodiment of the present invention comprises (A) abrasive grains, (B) an aliphatic organic acid having 4 or more carbon atoms, (C) an oxidizing agent, (D ) A nonionic surfactant represented by the following general formula (1) and (E) a dispersion medium (hereinafter also referred to as “components (A) to (E)”). Hereinafter, each component contained in the chemical mechanical polishing dispersion of one embodiment of the present invention will be described in detail.

・・・・・（１）
（式中、ｎおよびｍはそれぞれ独立に１以上の整数であり、ｎ＋ｍ≦５０を満たす。）

(1)
(In the formula, n and m are each independently an integer of 1 or more and satisfy n + m ≦ 50.)

1.1. (A) Abrasive grains (A) The abrasive grains can be at least one selected from inorganic particles.

  Examples of the inorganic particles include particles such as silica, alumina, titania, zirconia, and ceria, more preferably silica and ceria particles, and still more preferably silica. Examples of the silica include fumed silica, silica synthesized by a sol-gel method, and colloidal silica. Fumed silica can be obtained by reacting silicon chloride or the like with oxygen and water in the gas phase. Silica synthesized by the sol-gel method can be obtained by hydrolysis and / or condensation reaction using an alkoxysilicon compound as a raw material. Colloidal silica can be obtained, for example, by an inorganic colloid method using a raw material purified in advance.

  The (A) abrasive grains preferably have an impurity metal content of 10 ppm or less, more preferably 5 ppm or less, still more preferably 3 ppm or less, and particularly preferably 1 ppm or less with respect to the abrasive grains. Examples of the impurity metal include iron, nickel, and zinc.

  Moreover, the degree of association of (A) abrasive grains is preferably 2 to 5, more preferably 2 to 4. Furthermore, (A) The average primary particle diameter of an abrasive grain becomes like this. Preferably it is 5-500 nm, More preferably, it is 10-200 nm, More preferably, it is 20-100 nm. By using abrasive grains having an association degree and an average primary particle size in this range, a good balance between the polished surface and the polishing rate can be achieved. In particular, when (A) the abrasive grains are inorganic particles, the primary particle diameter is 60 to 90 nm and the degree of association is 1.5 to 4, so that the balance between a good surface to be polished and the polishing rate is good. .

  (A) The quantity of an abrasive grain is 0.05-10 mass% with respect to the total amount of the chemical mechanical polishing aqueous dispersion, Preferably it is 2-7 mass%.

1.2. (B) Aliphatic organic acid having 4 or more carbon atoms (B) The aliphatic organic acid having 4 or more carbon atoms is preferably an aliphatic polycarboxylic acid having 4 or more carbon atoms, hydroxyl acid having 4 or more carbon atoms, or the like. Specific examples of the aliphatic polycarboxylic acid having 4 or more carbon atoms include maleic acid, succinic acid, fumaric acid, glutaric acid, adipic acid and the like. Specific examples of the hydroxyl acid having 4 or more carbon atoms include citric acid, malic acid, tartaric acid and the like. Of these, aliphatic organic acids having 4 to 8 carbon atoms are more preferable, aliphatic organic acids having 4 to 6 carbon atoms are more preferable, and maleic acid, citric acid, and malic acid are particularly preferable.

  The amount of (B) organic acid is preferably 0.005 to 3% by mass, more preferably 0.05 to 2% by mass, and still more preferably based on the total amount of the chemical mechanical polishing aqueous dispersion. 0.1 to 1% by mass.

1.3. (C) Oxidizing agent (C) Examples of the oxidizing agent include persulfates, hydrogen peroxide, inorganic acids, organic peroxides, and polyvalent metal salts. Examples of the persulfate include ammonium persulfate and potassium persulfate. Examples of the inorganic acid include nitric acid and sulfuric acid. Examples of the organic peroxide include peracetic acid, perbenzoic acid, tert-butyl hydroperoxide, and the like. Examples of the polyvalent metal salt include permanganic acid compounds and dichromic acid compounds. Specifically, examples of the permanganic acid compound include potassium permanganate and the like. And potassium chromate. Of these, hydrogen peroxide, persulfates and inorganic acids are preferred, and hydrogen peroxide is particularly preferred.

  (C) The amount of the oxidizing agent is preferably 0.01 to 5% by mass, more preferably 0.05 to 3% by mass, and still more preferably based on the total amount of the chemical mechanical polishing aqueous dispersion. It is 0.05-1.5 mass%.

1.4. (D) Nonionic surfactant (D) A nonionic surfactant is a compound which has a triple bond, and is represented by the said General formula (1). In the general formula (1), n + m ≦ 40 is preferable, and n + m ≦ 30 is more preferable.

  The amount of the (D) nonionic surfactant represented by the general formula (1) or (2) is preferably 0.001 to 10% by mass with respect to the total amount of the chemical mechanical polishing aqueous dispersion. More preferably, it is 0.01-5 mass%.

  Further, in the chemical mechanical polishing aqueous dispersion of one embodiment of the present invention, the ratio of the blending amount of (B) the aliphatic organic acid having 4 or more carbon atoms to the blending amount of (D) the nonionic surfactant is 0. 1 to 10 is preferable. As a result, it is possible to obtain a highly polished surface that is well planarized without damaging the physical properties of the insulating layer.

1.5. (E) Dispersion medium Examples of the dispersion medium (E) include a mixed medium of water, water and alcohol, a mixed medium containing water and an organic solvent compatible with water, and the like. Of these, water or a mixed medium of water and alcohol is preferably used, and water is particularly preferably used.

1.6. Other Components The chemical mechanical polishing aqueous dispersion of one embodiment of the present invention contains the above components (A) to (E) as essential components, but, if necessary, (F) an anticorrosive, ( G) A pH adjusting agent can be contained.

  (F) As an anticorrosive agent, benzotriazole and its derivative (s) can be mentioned. Here, the benzotriazole derivative means one obtained by substituting one or two or more hydrogen atoms of benzotriazole with, for example, a carboxyl group, a methyl group, an amino group, or a hydroxyl group. Examples of the benzotriazole derivative include 4-carboxylbenzotriazole and its salt, 7-carboxybenzotriazole and its salt, benzotriazole butyl ester, 1-hydroxymethylbenzotriazole, 1-hydroxybenzotriazole and the like.

  (F) The amount of the anticorrosive is preferably 0.005 to 0.1% by mass, more preferably 0.01 to 0.05% by mass, based on the total amount of the chemical mechanical polishing aqueous dispersion. .

  (G) As a pH adjuster, an organic base, an inorganic base, or an inorganic acid can be mentioned. Examples of the organic base include tetramethylammonium hydroxide and triethylamine. Examples of the inorganic base include ammonia, potassium hydroxide, sodium hydroxide, calcium hydroxide, magnesium hydroxide and the like. Examples of the inorganic acid include nitric acid, sulfuric acid, hydrochloric acid, acetic acid and the like.

  The pH of the chemical mechanical polishing aqueous dispersion of one embodiment of the present invention is 7-12, preferably 8-11. By setting the pH within this range, a good balance between the polished surface and the polishing rate can be achieved.

  (G) The amount of the pH adjuster is preferably 0.005 to 5% by mass, more preferably 0.01 to 3.5% by mass, based on the total amount of the chemical mechanical polishing aqueous dispersion.

1.7. Kit for Preparing Chemical Mechanical Polishing Aqueous Dispersion The chemical mechanical polishing aqueous dispersion can be supplied in a state where it can be used as a polishing composition as it is after the preparation. Alternatively, a polishing composition (that is, a concentrated polishing composition) containing each component of the chemical mechanical polishing aqueous dispersion at a high concentration is prepared, and the concentrated polishing composition is used at the time of use. It may be diluted to obtain a desired chemical mechanical polishing aqueous dispersion.

  For example, the chemical mechanical polishing aqueous dispersion may be prepared by dividing it into a plurality of liquids (for example, two or three liquids), and these liquids may be mixed and used at the time of use. For example, the chemical mechanical polishing aqueous dispersion can be prepared by mixing a plurality of liquids using the following first to third kits.

1.7.1. First Kit The first kit is a kit for preparing the chemical mechanical polishing aqueous dispersion by mixing the liquid (I) and the liquid (II). In the first kit, the liquid (I) comprises (A) abrasive grains, (B) an aliphatic organic acid having 4 or more carbon atoms, and (D) a nonionic surfactant represented by the above general formula (1). And (E) an aqueous dispersion containing a dispersion medium, and the liquid (II) contains (C) an oxidizing agent.

  When preparing the liquid (I) and the liquid (II) constituting the first kit, the respective components described above are described in the aqueous dispersion obtained by mixing the liquid (I) and the liquid (II). It is necessary to determine the concentration of each component contained in the liquid (I) and the liquid (II) so as to be included in the concentration range. In addition, the liquid (I) and the liquid (II) may contain each component at a high concentration (that is, may be concentrated). In this case, the liquid (I) and the liquid (D) are diluted at the time of use. It is possible to obtain (II). According to the first kit, it is possible to improve the storage stability of the (C) oxidizing agent in particular by separating the liquid (I) and the liquid (II).

  When preparing the chemical mechanical polishing aqueous dispersion using the first kit, it is sufficient that the liquid (I) and the liquid (II) are separately prepared and supplied and integrated together during polishing. The method and timing are not particularly limited.

  For example, the liquid (I) and the liquid (II) may be separately supplied to the polishing apparatus and mixed on the surface plate, or may be mixed before being supplied to the polishing apparatus, or in the polishing apparatus. Or may be mixed in the mixing tank by providing a mixing tank. Further, a line mixer or the like may be used in order to obtain a more uniform aqueous dispersion during line mixing.

1.7.2. Second Kit The second kit is a kit for preparing the chemical mechanical polishing aqueous dispersion by mixing the liquid (I) and the liquid (II). In the second kit, the liquid (I) is an aqueous dispersion containing (A) abrasive grains and (E) a dispersion medium, and the liquid (II) is (B) an aliphatic organic acid having 4 or more carbon atoms, (C) an oxidizing agent, and (D) a nonionic surfactant represented by the general formula (1).

  When preparing the liquid (I) and the liquid (II) constituting the second kit, the respective components described above are contained in the aqueous dispersion obtained by mixing the liquid (I) and the liquid (II). It is necessary to determine the concentration of each component contained in the liquid (I) and the liquid (II) so as to be included in the concentration range. In addition, the liquid (I) and the liquid (II) may contain each component at a high concentration (that is, may be concentrated). In this case, the liquid (I) and the liquid (D) are diluted at the time of use. It is possible to obtain (II). According to the second kit, the storage stability of the aqueous dispersion can be improved by separating the liquid (I) and the liquid (II).

  When the chemical mechanical polishing aqueous dispersion of one embodiment of the present invention is prepared using the second kit, the liquid (I) and the liquid (II) are separately prepared and supplied, and are integrated during polishing. The mixing method and timing are not particularly limited.

  For example, the liquid (I) and the liquid (II) may be separately supplied to the polishing apparatus and mixed on the surface plate, or may be mixed before being supplied to the polishing apparatus, or in the polishing apparatus. Or may be mixed in the mixing tank by providing a mixing tank. Further, a line mixer or the like may be used in order to obtain a more uniform aqueous dispersion during line mixing.

1.7.3. Third Kit The third kit is a kit for preparing the chemical mechanical polishing aqueous dispersion of one embodiment of the present invention by mixing the liquid (I), the liquid (II), and the liquid (III). It is. In the third kit, the liquid (I) is an aqueous dispersion containing (A) abrasive grains and (E) a dispersion medium, and the liquid (II) is (B) an aliphatic organic acid having 4 or more carbon atoms and (D) The nonionic surfactant represented by the general formula (1) is included, and the liquid (III) includes (C) an oxidizing agent and (F) water.

  When preparing liquid (I), liquid (II), and liquid (III) constituting the third kit, an aqueous system obtained by mixing liquid (I), liquid (II), and liquid (III) It is necessary to determine the concentration of each component contained in the liquid (I), the liquid (II), and the liquid (III) so that the above-described components are included in the dispersion in the concentration range described above. In addition, liquid (I), liquid (II), and liquid (III) may each contain a high concentration of each component (that is, it may be concentrated). , Liquid (I), liquid (II), and liquid (III) can be obtained. According to the third kit, the storage stability of the aqueous dispersion can be increased by separating the liquid (I), the liquid (II), and the liquid (III).

  When preparing the chemical mechanical polishing aqueous dispersion of one embodiment of the present invention using the third kit, the liquid (I), the liquid (II), and the liquid (III) are separately prepared and supplied, and There is no particular limitation on the mixing method and timing as long as they are integrated during polishing.

  For example, the liquid (I), the liquid (II), and the liquid (III) may be separately supplied to the polishing apparatus and mixed on the surface plate, or may be mixed before being supplied to the polishing apparatus. Then, line mixing may be performed in the polishing apparatus, or mixing may be performed by providing a mixing tank. Further, a line mixer or the like may be used in order to obtain a more uniform aqueous dispersion during line mixing.

  In the second and third kits, the liquid (I) is represented by (B) an aliphatic organic acid having 4 or more carbon atoms, (C) an oxidizing agent, and (D) the general formula (1). One or more types of components selected from nonionic surfactants can be further included.

1.8. Use The chemical mechanical polishing aqueous dispersion of one embodiment of the present invention can be used as an abrasive for chemical mechanical polishing an insulating layer contained in a semiconductor device. For example, the chemical mechanical polishing aqueous dispersion of one embodiment of the present invention can be used as an abrasive when forming a copper (or copper alloy) damascene wiring by chemical mechanical polishing. In this case, the step of forming the copper (or copper alloy) damascene wiring by chemical mechanical polishing is formed mainly in the first polishing step for removing copper (or copper alloy) and mainly under the copper (or copper alloy). And a second polishing step for removing the conductive barrier layer. In this second polishing step, not only the conductive barrier layer is removed, but also the interlayer insulating layer present under the conductive barrier layer may be polished at the same time. You can get a plane. Here, the chemical mechanical polishing aqueous dispersion of one embodiment of the present invention can be suitably used as an abrasive in the second polishing step. By using the chemical mechanical polishing aqueous dispersion as an abrasive in the second polishing step, more excellent polishing characteristics and low damage to an insulating layer (especially an insulating layer having a relative dielectric constant of 3.5 or less). Can be demonstrated.

In the chemical mechanical polishing aqueous dispersion according to one embodiment of the present invention, the copper layer, the conductive barrier layer, the first insulating layer, and the second insulating layer having a higher dielectric constant than the first insulating layer are chemically treated under the same conditions. When mechanically polished, the polishing rate ratio (R _B / R _M ) between the polishing rate (R _B ) of the conductive barrier layer and the polishing rate (R _M ) of the copper layer is 1.5 or more, and the second insulating layer The polishing rate ratio (R _In-2 / R _M ) between the polishing rate (R _In-2 ) and the polishing rate (R _M ) of the copper layer is 0.9 to 2.5, and the second insulating layer The polishing rate ratio (R _In-2 / R _In-1 ) between the polishing rate (R _In-2 ) and the polishing rate (R _In-1 ) of the first insulating layer can be 0.5 to 5. .

2. Chemical Polishing Method A chemical mechanical polishing method according to an embodiment of the present invention is a method in which a metal layer provided on an insulating layer having a recess via a stopper layer is embedded in the recess until the stopper layer is exposed. A first polishing step for mechanical polishing and a second polishing step for chemical mechanical polishing of the metal layer and the stopper layer until the insulating layer is exposed using the chemical mechanical polishing aqueous dispersion of one embodiment of the present invention. And including. Hereinafter, although the specific example of the chemical mechanical polishing method of one embodiment of this invention is demonstrated with reference to FIGS. 1-3, the chemical mechanical polishing method of one embodiment of this invention is not limited to these.

2.1. First Specific Example FIGS. 1A to 1C are cross-sectional views schematically showing a specific example (first specific example) of a chemical mechanical polishing method according to an embodiment of the present invention.

  Fig.1 (a) shows the grinding | polishing target object 1a of the chemical mechanical polishing method of a 1st specific example. As shown in FIG. 1A, the object to be polished 1a is provided on a substrate 11, an insulating layer 12 including a recess 20 provided on the substrate 11, and a stopper layer 13 on the insulating layer 12. Metal layer 14. The metal layer 14 is embedded in the recess 20. Here, the substrate 11 is, for example, a silicon substrate, the insulating layer 12 may be an inorganic material or an organic material, and the stopper layer 13 is a layer having a different etching rate from the metal layer 14 with respect to the abrasive, The metal layer 14 is generally made of a metal material that can be used as wiring. The insulating layer 12 can be composed of, for example, a PETEOS film or an insulating layer having a relative dielectric constant of 3.5 or less, preferably an insulating layer having a relative dielectric constant of 3.5 or less, more preferably 3.0. The following insulating layers. The stopper layer 13 is preferably made of, for example, a conductive barrier layer. Furthermore, the metal layer 14 can be made of a metal generally used for wiring (for example, a metal such as aluminum, copper, or gold, or an alloy of the metal), and is preferably copper or a copper alloy.

  When the stopper layer 13 is made of a conductive barrier layer, it can be made of, for example, a metal, a metal alloy, or a metal nitride (for example, Ti, TiN, Ta, TaN, TaNb). Here, the material of the stopper layer 13 is particularly preferably Ta and / or TaN. The stopper layer 13 may have a two-layer structure.

  First, in the first polishing step, chemical mechanical polishing is performed until the stopper layer 13 is exposed except for the portion of the metal film 14 buried in the recess 20 (see FIG. 1B). Here, as the abrasive, the chemical mechanical polishing aqueous dispersion described above may be used, or the first polishing aqueous dispersion described later may be used.

  Next, in the second polishing step, the remaining metal layer 14 and the stopper layer 13 are subjected to chemical mechanical polishing until the insulating layer 12 is exposed using the chemical mechanical polishing aqueous dispersion according to the embodiment of the present invention described above ( (Refer FIG.1 (c)). Thereby, the part located in the stopper layer 13 other than the bottom part and inner wall surface of the recessed part 20 is removed. As a result, the wiring structure 1 shown in FIG. 1C is obtained.

  According to this specific example, in the second polishing step, the physical properties of the insulating layer 12 are not changed and the material is peeled off by chemically mechanically polishing the insulating layer 12 using the above-described chemical mechanical polishing aqueous dispersion. A surface to be polished with high accuracy can be obtained without causing surface defects such as scratches and scratches on the surface to be polished. In particular, when the insulating layer 12 is made of an insulating layer having a relative dielectric constant of 3.5 or less, the occurrence of the surface defects on the polished surface can be prevented without changing the physical properties of the insulating layer 12. Very useful in terms.

2.2. Second Specific Example FIGS. 2A to 2C are cross-sectional views schematically showing another specific example (second specific example) of the chemical mechanical polishing method of one embodiment of the present invention. is there.

  Fig.2 (a) shows the grinding | polishing target object 2a of the chemical mechanical polishing method of a 2nd specific example. 2A, except that the insulating layer 112 includes a laminate of the first insulating layer 21 and the second insulating layer 22 having a dielectric constant higher than that of the first insulating layer 21. The same components as those shown in FIG. 1A are given the same reference numerals as those shown in FIG. Here, the second insulating layer 22 functions as a cap layer.

  The second insulating layer 22 is made of, for example, a metal having high hardness such as tantalum or titanium, a nitride or oxide thereof. Alternatively, the second insulating layer 22 is formed of, for example, a silicon oxide film, a boron phosphorus silicate film (BPSG film) obtained by adding a small amount of boron and phosphorus to silicon oxide, or FSG (Fluorine-doped silicon glass) doped with fluorine in silicon oxide. It may be a silicon oxide insulating layer called. Examples of the silicon oxide film include a thermal oxide film, PETEOS (Plasma Enhanced-TEOS film), HDP film (High Density Plasma Enhanced-TEOS film), and a silicon oxide film obtained by a thermal CVD method.

  The first insulating layer 21 is, for example, an HSQ film (Hydrogen Silsesquioxane film) using triethoxysilane as a raw material, an MSQ film (Methyl Silsesquioxane film) using tetraethoxysilane and a small amount of methyltrimethoxysilane, or other silane compounds. It consists of a film made of In addition, by using appropriate organic polymer particles or the like mixed in the raw material for the first insulating layer 21, the polymer is burned out in the heating process to form vacancies, thereby further reducing the dielectric constant. Included membranes are also included. Furthermore, organic polymers such as polyarylene polymers, polyarylene ether polymers, polyimide polymers, and benzocyclobutene polymers are also included in the first insulating layer 21. The first insulating layer 21 is preferably an insulating layer having a relative dielectric constant of 3.5 or less, more preferably an insulating layer having a dielectric constant of 3.0 or less.

  First, in the first polishing step, chemical mechanical polishing is performed until the stopper layer 13 is exposed except for the portion of the metal film 14 buried in the recess 20 (see FIG. 2B). Here, as the abrasive, the chemical mechanical polishing aqueous dispersion of one embodiment of the present invention may be used, or a first polishing aqueous dispersion described later may be used.

  Next, in the second polishing step, the remaining metal layer 14, the stopper layer 13, and the second, using the chemical mechanical polishing aqueous dispersion (second polishing aqueous dispersion) of the embodiment of the present invention described above. The insulating layer 22 is subjected to chemical mechanical polishing until the first insulating layer 21 is exposed (see FIG. 2C). Thereby, the part located in the stopper layer 13 other than the bottom part and inner wall surface of the recessed part 20 is removed. As a result, the wiring structure 2 shown in FIG. 2C is obtained.

  According to this example, the same effect as the first example described above is obtained. In addition, according to the present specific example, in the second polishing step, since the second insulating layer 22 is removed by the chemical mechanical polishing, the damage applied to the first insulating layer 21 by the chemical mechanical polishing is reduced. can do.

2.3. Third Specific Example FIGS. 3A to 3C are diagrams schematically illustrating another specific example (third specific example) of the chemical mechanical polishing method according to the embodiment of the present invention. .

  FIG. 3A shows a polishing object 3a of the chemical mechanical polishing method of the third specific example. 3A has the same structure as that shown in FIG. 1A except that a third insulating layer 31 and a fourth insulating layer 32 are provided below the insulating layer 12. The same components as those shown in FIG. 1A are given the same symbols. Here, the third insulating layer 31 is made of, for example, silicon oxide, and the fourth insulating layer 32 is made of, for example, silicon nitride.

  The chemical mechanical polishing method of this specific example is the same as the chemical polishing method of the first specific example. Further, according to this specific example, the same effect as the first specific example described above is obtained.

2.4. Polishing apparatus and polishing conditions In the chemical mechanical polishing method of one embodiment of the present invention, polishing in the first polishing process and the second polishing process is performed using commercially available chemical mechanical polishing apparatuses (for example, LGP510, LGP552 (hereinafter referred to as lap master SFT). ), EPO-112, EPO-222 (above, manufactured by Ebara Corporation), Mirra (Applied Materials), AVANTI-472 (made by Ipec), etc.) It can be done under conditions.

Preferred polishing conditions should be appropriately set depending on the chemical mechanical polishing apparatus used. For example, when EPO-112 is used as the chemical mechanical polishing apparatus, both the first polishing process and the second polishing process are, for example, the following: It can be a condition.
Surface plate rotation speed: preferably 30 to 130 rpm, more preferably 40 to 130 rpm
Head rotation speed: preferably 30 to 130 rpm, more preferably 40 to 130 rpm
Surface plate rotation speed / head rotation speed ratio: preferably 0.5 to 2, more preferably 0.7 to 1.5
Polishing pressure: preferably 0.5 to 2.5 psi, more preferably 1.0 to 2.0 psi
Chemical mechanical polishing aqueous dispersion supply rate: preferably 50 to 300 ml / min, more preferably 100 to 200 ml / min

2.5. First Polishing Aqueous Dispersion In the first to third specific examples, the first polishing aqueous dispersion that can be used in the first polishing step is the same for each of the metal layer 14 and the stopper layer 13. A chemical machine having a polishing characteristic in which the polishing rate ratio (R _M / R _S ) between the polishing rate (R _M ) of the metal layer 14 and the polishing rate (R _S ) of the stopper layer 13 is 50 or more when chemical mechanical polishing is performed. It can be an aqueous dispersion for polishing. Here, if the polishing rate ratio (R _M / R _S ) is less than 50, after the first polishing step is completed, excessive metal remains in a portion where the metal layer 14 is to be removed, so that the second polishing is performed. A lot of time is required for the process, and a large amount of machining liquid may be required.

The polishing rate ratio (R _M / R _S ) of the first polishing aqueous dispersion is preferably 60 or more, more preferably 70 or more.

The composition of the first aqueous dispersion for polishing is not particularly limited as long as the polishing rate ratio (R _M / R _S ) is in the above range. For example, in the aqueous medium, (A It is preferable to contain at least one ammonia component selected from the group consisting of :) abrasive grains, (B) organic acid, (C) oxidizing agent, (E) dispersion medium, and ammonia and ammonium ions.

  Examples of the (E) dispersion medium used in the first polishing aqueous dispersion include the (E) dispersion medium in the chemical mechanical polishing aqueous dispersion (second polishing aqueous dispersion) of the embodiment of the present invention described above. Among these, it is preferable to use only water as a dispersion medium.

  Examples of the abrasive (A) used in the first polishing aqueous dispersion include, for example, the component (A) in the chemical mechanical polishing aqueous dispersion (second polishing aqueous dispersion) of the embodiment of the present invention described above. What was illustrated as an abrasive grain to comprise is mentioned, At least 1 sort (s) of abrasive grain selected from these can be used. Of these, silicon dioxide, organic particles, or organic-inorganic composite particles are preferably used.

Examples of the (B) organic acid used in the first polishing aqueous dispersion include organic acids constituting the component (B) in the second polishing aqueous dispersion, and among these, a higher polishing rate. Citric acid and malic acid are preferably used in that the ratio (R _M / R _S ) can be obtained.

  Further, the first polishing aqueous dispersion may further contain (F) an anticorrosive, glycine, and alanine. As the (F) anticorrosive used in the first polishing aqueous dispersion, for example, those exemplified as the anticorrosive constituting the component (F) in the second polishing aqueous dispersion can be used. Carboxybenzotriazole is mentioned.

  When the first polishing aqueous dispersion contains the anticorrosive agent constituting the component (F), the blending amount is preferably 5% by mass or less based on the total amount of the first polishing aqueous dispersion, The content is more preferably 0.001 to 5% by mass, still more preferably 0.005 to 1% by mass, and particularly preferably 0.01 to 0.5% by mass.

  Examples of the (C) oxidizing agent used in the first polishing aqueous dispersion include those exemplified as the oxidizing agent constituting the component (C) in the second polishing aqueous dispersion, and are selected from these. At least one oxidizing agent can be used. Of these, hydrogen peroxide or persulfate is preferable, and ammonium persulfate is particularly preferably used.

  The ammonia component contained in the first polishing aqueous dispersion may be present as ammonia, may be present as ammonium ions, or may be a mixture of both. The ammonium ions may be present in a free state, may be present as an ammonium salt of an acid, or both may be present in an equilibrium state. Such ammonia and ammonium ions may be generated by independently adding aqueous ammonia to the first polishing aqueous dispersion, such as the above-mentioned ammonium salts of organic acids or ammonium persulfate added as an oxidizing agent. You may produce | generate from the ammonium salt of an inorganic acid, or you may add as a counter cation of the anionic surfactant mentioned later.

  In the first polishing aqueous dispersion, (A) abrasive grains, (B) organic acid, (C) an oxidizing agent, and at least one ammonia component selected from the group consisting of ammonia and ammonium ions, It is preferable to contain by a ratio.

  (A) The compounding quantity of an abrasive grain is 0.001-3 mass% normally with respect to the total amount of the 1st polishing aqueous dispersion, Preferably it is 0.01-3 mass%, More preferably, it is 0. 0.01 to 2.5% by mass, more preferably 0.01 to 2% by mass.

  (B) The compounding quantity of organic acid is 0.01-10 mass% normally with respect to the total amount of the 1st grinding | polishing aqueous dispersion, Preferably it is 0.1-5 mass%.

  (C) The compounding quantity of an oxidizing agent is 0.01-10 mass% normally with respect to the total amount of the 1st polishing aqueous dispersion, Preferably it is 0.02-5 mass%.

  The compounding amount of the ammonia component is usually 0.005 to 20 mol, preferably 0.01 to 15 mol, more preferably 0.03 to 10 mol, with respect to 1 liter of the first polishing aqueous dispersion. 0.05-10 mol is particularly preferable.

  The first polishing aqueous dispersion may further contain additives such as a surfactant and an antifoaming agent as necessary.

  Examples of the surfactant include a cationic surfactant, an anionic surfactant, an amphoteric surfactant, a nonionic surfactant, a water-soluble polymer, and the like, and in particular, an anionic surfactant and a nonionic surfactant. An agent or a water-soluble polymer is preferably used.

  Examples of the anionic surfactant include carboxylate, sulfonate, sulfate ester salt and phosphate ester salt. Examples of the carboxylate include fatty acid soaps and alkyl ether carboxylates, and examples of the sulfonate include alkylbenzene sulfonate, alkyl naphthalene sulfonate, α-olefin sulfonate, and the like. Examples of the sulfate ester salt include a higher alcohol sulfate ester salt, an alkyl ether sulfate salt, a polyoxyethylene alkylphenyl ether sulfate salt, and the like. Examples of the phosphate ester salt include an alkyl phosphorus salt. Examples include acid ester salts. Of these, sulfonates are preferred, alkylbenzene sulfonates are more preferred, and potassium dodecylbenzene sulfonate is particularly preferred.

  Examples of the nonionic surfactant include a nonionic surfactant such as a polyethylene glycol type surfactant, acetylene glycol, an ethylene oxide adduct of acetylene glycol, and acetylene alcohol.

  Examples of the water-soluble polymer include an anionic polymer, a cationic polymer, an amphoteric polymer, and a nonionic polymer. Examples of the anionic polymer include polyacrylic acid and its salt, polymethacrylic acid and its salt, and polyvinyl alcohol. Examples of the cationic polymer include polyethyleneimine and polyvinylpyrrolidone. Examples of the amphoteric polymer include polyacrylamide, and examples of the nonionic polymer include polyethylene oxide and polypropylene oxide.

  The compounding amount of the surfactant is preferably 20% by mass or less, more preferably 0.001 to 20% by mass, and more preferably 0.01 to 10% with respect to the total amount of the first polishing aqueous dispersion. More preferably, it is 0.05 mass%, Most preferably, it is 0.05-5 mass%.

  The pH of the first polishing aqueous dispersion may be set to any value of an acidic region, a neutral region (from weakly acidic region to weakly alkaline region), and an alkaline region. The pH in the acidic region is preferably 2 to 4, the pH in the region near neutral is preferably 6 to 8, and the pH in the alkaline region is preferably 8 to 12. Among these, pH in the neutral to alkaline region, that is, 6 to 12 is preferable.

  In the present invention, the first polishing step and the second polishing step may be performed continuously by using the same polishing apparatus and sequentially switching the supplied polishing aqueous dispersion while the object to be polished is mounted. In addition, using the same polishing apparatus, after the first polishing step is finished, the polishing object is once taken out, and after switching the polishing aqueous dispersion to be supplied, the removed polishing object is mounted again to perform the second polishing step. You may implement.

  Moreover, you may implement a 1st grinding | polishing process and a 2nd grinding | polishing process using a separate grinding | polishing apparatus. Furthermore, when using a polishing apparatus including a plurality of polishing pads, the first polishing step and the second polishing step may be polished using different types of polishing pads, or the first polishing step and the second polishing step may be performed. The same type of polishing pad may be used in the polishing step.

3. Examples Hereinafter, the present invention will be described by way of examples. However, the present invention is not limited to the examples.

3.1. Preparation of aqueous dispersion containing inorganic particles 3.1.1. Preparation of Aqueous Dispersion Containing Fumed Silica Particles 2 kg of fumed silica particles (manufactured by Nippon Aerosil Co., Ltd., trade name “Aerosil # 90”, average primary particle size 20 nm) are ultrasonically dispersed in 6.7 kg of ion-exchanged water. It was dispersed using a machine. This was filtered with a filter having a pore size of 5 μm to obtain an aqueous dispersion containing 23% by mass of fumed silica particles. The average secondary particle diameter of fumed silica contained in this aqueous dispersion was 220 nm.

3.1.2. Preparation of aqueous dispersion containing colloidal silica particles 3.1.2a. Preparation of aqueous dispersion containing colloidal silica particles C1 A flask was charged with 75 parts by mass of ammonia water having a concentration of 25% by mass, 40 parts by mass of ion-exchanged water, 165 parts by mass of ethanol and 30 parts by mass of tetraethoxysilane, and stirred at a rotational speed of 180 rpm. The temperature was raised to 80 ° C. Stirring was continued for 2 hours while maintaining the temperature at 80 ° C., and then cooled to room temperature. Thereby, an alcohol dispersion of colloidal silica particles C1 was obtained.

  Subsequently, using a rotary evaporator, the operation of removing alcohol while adding ion-exchanged water was repeated several times while maintaining the temperature of the obtained dispersion at 80 ° C. By this operation, an aqueous dispersion containing 25% by mass of colloidal silica particles C1 was prepared.

  The average primary particle diameter of the colloidal silica particles C1 contained in this aqueous dispersion was 60 nm, the average secondary particle diameter was 160 nm, and the average degree of association was 2.7.

3.1.2b. Preparation of water dispersion containing colloidal silica particles C2 to C7 respectively In the above “3.1.2a. Preparation of water dispersion containing colloidal silica particles C1”, use of ammonia water having a concentration of 25%, ethanol and tetraethoxysilane By adjusting the amount and carrying out the same operation as above, water dispersions containing colloidal silica particles C2 to C7 shown in Table 1 were prepared, respectively, and used in Examples 2 to 5 and Comparative Examples 1 and 2, respectively. It was.

3.2. Preparation of first aqueous dispersion for polishing and evaluation of polishing performance 3.2.1. Preparation of first polishing aqueous dispersion Fumed silica particles prepared in the above "3.1.1. Preparation of aqueous dispersion containing fumed silica particles" in an amount corresponding to 1% by mass in terms of silica were prepared. The aqueous dispersion containing the mixture is put in a polyethylene bottle, and 0.5% by mass of quinaldic acid, 2,4,7,9-tetramethyl-5-decyne-4,7-diol-dipolyoxyethylene ether is added thereto. (Air Products Japan Co., Ltd., trade name “Surfinol 465”) 0.05% by mass, 30% by mass hydrogen peroxide in an amount corresponding to 0.1% by mass in terms of hydrogen peroxide And stirred for 15 minutes. Thereafter, the pH was adjusted to 9.5 with a 1N aqueous potassium hydroxide solution, followed by filtration with a filter having a pore size of 5 μm to obtain a first polishing aqueous dispersion.

3.2.2. Evaluation of Polishing Performance of First Aqueous Dispersion for Polishing A polishing pad made of polyurethane foam (made by Nitta Haas Co., product number “IC1000”) is applied to a chemical mechanical polishing apparatus (Applied Materials, model “Mirra”). Wearing and supplying the above chemical mechanical polishing aqueous dispersion, the following various polishing rate measurement substrates are subjected to chemical mechanical polishing for 1 minute under the following polishing conditions, and the polishing rate is calculated by the following method. did.

I. Polishing speed measurement substrate ・ Silicon substrate with an 8-inch thermal oxide film on which a copper film having a film thickness of 15000 mm (corresponding to the metal layer of the present invention) is laminated ・ Tantalum nitride film having a film thickness of 2000 mm (stopper layer of the present invention (conductivity) 8 inch silicon substrate with a thermal oxide film equivalent to a barrier layer) 8 inch silicon substrate with a PETEOS film having a thickness of 10,000 mm (corresponding to the second insulating layer of the present invention)

II. Polishing conditions-Head rotation speed: 130 rpm
・ Platen rotation speed: 130rpm
Head load: 1.5 psi
-Supply rate of chemical mechanical polishing aqueous dispersion: 200 ml / min

III. Polishing speed calculation method For the copper film and the tantalum nitride film, the film thickness after the polishing treatment is measured using an electric conduction type film thickness measuring instrument (model OMNIMAP RS75, manufactured by KLA-Tencor Corporation), The polishing rate was calculated from the film thickness reduced by chemical mechanical polishing and the polishing time.

  For the PETEOS film, the film thickness after polishing treatment was measured using a light interference type film thickness measuring device (manufactured by Nanometrics Japan Co., Ltd., model “Nanospec6100”), and the film thickness decreased by chemical mechanical polishing. The polishing rate was calculated from the polishing time.

IV. Polishing rate-Polishing rate of metal layer (copper) (R _M ): 5500 Å / min-Polishing rate of conductive barrier layer (tantalum nitride layer) (R _B ): 30 Å / min-Polishing rate of insulating layer (PETEOS film) (R _In ): 40 Å / min

3.3. Example 1
3.3.1. Preparation of Second Polishing Aqueous Dispersion (Chemical Mechanical Polishing Aqueous Dispersion of the Present Invention) An aqueous dispersion containing the above “3.1.2a. Colloidal silica particles in an amount corresponding to 4% by mass in terms of silica. The aqueous dispersion containing the colloidal silica particles C1 prepared in “Preparation” was put in a polyethylene bottle, and (D) a nonionic surfactant (2,4,7,9-tetramethyl-5-decyne- 4,7-diol-dipolyoxyethylene ether (n + m = 10) (manufactured by Air Products Japan, trade name “Surfinol 465”)) 0.1 mass%, (B) aliphatic having 4 or more carbon atoms An organic acid (maleic acid) of 0.9% by mass and (C) an oxidizing agent (30% by mass of hydrogen peroxide in an amount corresponding to 0.3% by mass in terms of hydrogen peroxide) were sequentially added. Stir for minutes. Thereafter, (G) 0.98% by mass of a pH adjuster (potassium hydroxide) was added to adjust the pH of the aqueous dispersion to 9.0. Next, ion-exchanged water was added so that the total amount of all the constituent components was 100% by mass, and then filtered through a filter having a pore diameter of 5 μm, thereby obtaining a second polishing aqueous dispersion S1.

3.3.2. Evaluation of polishing performance of second polishing aqueous dispersion Chemical foam polishing device (Applied Materials, Model “Mirra”) and polyurethane foam polishing pad (Nitta Haas, product number “SUPREME”) Wearing and supplying the above chemical mechanical polishing aqueous dispersion, the following various polishing rate measurement substrates are subjected to chemical mechanical polishing for 1 minute under the following polishing conditions, and the polishing rate is calculated by the following method. did.

I. Polishing speed measurement substrate ・ Silicon substrate with an 8-inch thermal oxide film on which a copper film having a film thickness of 15000 mm (corresponding to the metal layer of the present invention) is laminated ・ Tantalum nitride film having a film thickness of 2000 mm (stopper layer of the present invention (conductivity) 8 inch silicon substrate with a thermal oxide film (corresponding to the barrier layer)) 8 inch silicon substrate with a PETEOS film (corresponding to the second insulating layer of the present invention) having a film thickness of 10,000 mm. Applied Materials Japan 8-inch silicon substrate on which a first insulating layer (BD film) with a thickness of 4000 mm (relative dielectric constant k = 2.8) is stacked by the black diamond process developed by Co., Ltd. ・ MSQ type developed by JSR Corporation 8-inch silicon substrate on which a first insulating layer (LKD film) (relative dielectric constant k = 2.3) having a thickness of 5000 mm is stacked

II. Polishing conditions-Head rotation speed: 130 rpm
・ Platen rotation speed: 130rpm
Head load: 1.5 psi
-Supply rate of aqueous dispersion for chemical mechanical polishing: 200 ml / min

III. Polishing speed calculation method For the copper film and the tantalum nitride film, the film thickness after the polishing treatment is measured using an electric conduction type film thickness measuring instrument (model OMNIMAP RS75, manufactured by KLA-Tencor Corporation), The polishing rate was calculated from the film thickness reduced by chemical mechanical polishing and the polishing time.

  For the PETEOS film, BD film, and LKD film, the film thickness after the polishing treatment was measured using an optical interference film thickness measuring device (Nanometrics Japan Co., Ltd., model “Nanospec6100”), The polishing rate was calculated from the film thickness decreased by polishing and the polishing time.

IV. Polishing rate-Polishing rate (R _M ) of metal layer (copper): 250 Å / min-Polishing rate (R _B ) of conductive barrier layer (stopper layer (tantalum nitride layer)): 800 Å / min-Second insulating layer (PETEOS film) polishing rate (R _In-2 ): 380 Å / min ・ First insulating layer (BD film) polishing rate (R _In-1-1 ): 170 Å / min ・ First insulating layer (LKD) Film) polishing rate (R _In-1-2 ): 190 Å / min

  V. Method for evaluating the number of scratches in the first insulating layer

  The presence or absence of peeling at the outer peripheral portion of the first insulating layer after polishing was observed visually and with an optical microscope. Further, using a pattern-less wafer defect inspection apparatus (manufactured by KLA-Tencor Corporation, model “KLA2351”), the number of defects per entire surface to be polished was measured, and the number of scratches was counted. The result is shown in Table 1 as “the number of scratches of the first insulating layer”. Of those counted as defects by the wafer defect inspection apparatus, those that are not scratched include, for example, adhering dust, stains generated during wafer manufacture, and the like.

In the above “V. Evaluation Method for Number of Scratches of First Insulating Layer”, inspection parameters of the defect inspection apparatus are shown below.
Inspection field: bright field Inspection wavelength: visible light Pixel size: 0.39
・ Threshold (defect detection sensitivity): 50

VI. Evaluation of dishing and scratch (i) Fabrication of substrate to be polished on which copper wiring is formed An insulating layer (PETEOS film (thickness 500 mm ) And a BD film (composite film of 4500 mm thickness) were laminated by 5000 mm. Next, a conductive barrier layer (TaN film) having a thickness of 250 mm is formed on the surface of the insulating layer, and then a metal layer (Cu layer) having a thickness of 1.1 μm is formed by sputtering and plating in the groove covered with the TaN film. ) Was deposited.

(Ii) Evaluation after the first polishing step For the wafer prepared in (i) above, using the first polishing aqueous dispersion prepared in “3.2.1. Preparation of first polishing aqueous dispersion”. Polishing was performed at a polishing rate of 5500 mm for 2.25 minutes.

  After completion of the first polishing step, the dishing of the wiring having a width of 100 μm in the surface to be polished was evaluated using a stylus type step gauge (manufactured by KLA-Tencor Co., Ltd., model “HRP240”), and was 400 mm.

  Here, “dishing” is the distance (height difference) between the upper surface of the wafer (a plane formed by an insulating layer or a conductive barrier layer) and the lowest part of the wiring portion.

(Iii) Evaluation after the second polishing step The wafer prepared in (ii) above was polished for the time calculated by the following formula using the aqueous dispersions of Examples 1 to 5 and Comparative Examples 1 and 2.
Polishing time (min) = {(barrier layer thickness (Å)) ÷ (barrier layer (tantalum nitride) calculated in “3.3.2. Evaluation of polishing performance of second polishing aqueous dispersion” above) Polishing speed) + (thickness of first insulating layer (500 mm)) ÷ (first insulating layer (PETEOS) calculated in “3.3.2. Evaluation of polishing performance of second polishing aqueous dispersion”) Polishing speed} + (thickness of second insulating layer (200 mm)) ÷ (second insulating layer (BD) calculated in “3.3.2. Evaluation of polishing performance of second polishing aqueous dispersion” above) Polishing rate)}

  About the surface to be polished, dishing of 100 μm wiring was evaluated using a stylus type step gauge (manufactured by KLA Tencor Co., Ltd., type “HRP240”). The results are shown in Table 1.

  Here, “dishing” is the distance (height difference) between the upper surface of the wafer (a plane formed by an insulating layer or a conductive barrier layer) and the lowest part of the wiring portion.

  In addition, a field region having no pattern (polishing amount of an insulating film in a field region wider than 120 μm × 120 μm is polished using an optical interference film thickness measuring device (manufactured by Nanometrics Japan Co., Ltd., model “Nanospec6100”). When the film thickness after the treatment was measured and calculated as the film thickness decreased from the initial film thickness of 5000 mm, it was 750 to 900 mm in each of Examples 1 to 5 and the aqueous dispersions of Comparative Examples 1 and 2.

  Further, using an optical microscope, in a dark field, the copper wiring portion was observed at 200 random locations with a region of 120 μm × 120 μm as a unit region, and the number of unit regions where the scratch was generated was determined as “Scratch of copper wiring”. Measured as "number". The results are shown in Table 1.

3.4. Examples 2 to 5 and Comparative Examples 1 to 2
In Example 1, the chemistry shown in Table 1 was performed in the same manner as in Example 1 except that the types and amounts of each component of the chemical mechanical polishing aqueous dispersion and the pH of the aqueous dispersion were changed as shown in Table 1. Mechanical polishing aqueous dispersions S2 to S7 and R1 to R2 were prepared. In Table 1, “-” indicates that the component corresponding to the corresponding column was not added.

  Further, evaluation was performed in the same manner as in Example 1 except that each aqueous dispersion synthesized above was used instead of S1 as the aqueous dispersion for chemical mechanical polishing. The evaluation results are shown in Table 1.

  According to Table 1, by using the chemical mechanical polishing aqueous dispersions of Examples 1 to 5, when the insulating layer formed on the semiconductor substrate is subjected to chemical mechanical polishing, the occurrence of scratches and dishing on the polished surface is greatly increased. In addition, the insulating layer can be sufficiently flattened without excessively polishing the insulating layer without significantly changing the relative dielectric constant of the insulating layer, and a highly accurate polished surface can be obtained. I found out. On the other hand, when the chemical mechanical polishing aqueous dispersions of Comparative Examples 1 and 2 were used, dishing after polishing was large.

Fig.1 (a)-FIG.1 (c) are schematic which shows one specific example of the chemical mechanical polishing method of this invention. FIG. 2A to FIG. 2C are schematic views showing another specific example of the chemical mechanical polishing method of the present invention. FIG. 3A to FIG. 3C are schematic views showing another specific example of the chemical mechanical polishing method of the present invention.

Explanation of symbols

1, 2, 3 Wiring structure 1a, 2a, 3a Polishing object 11 Substrate (for example, silicon)
12 Insulating layer (for example, PETEOS film or insulating layer having a relative dielectric constant of 3.5 or less)
13 Stopper layer (for example, barrier layer)
14 Metal layer 20 Recess 21 First insulating layer (for example, an insulating layer having a relative dielectric constant of 3.5 or less)
22 Second insulating layer 31 Third insulating layer (for example, silicon oxide)
32 Fourth insulating layer (eg, silicon nitride)
112 Insulating layer

Claims (8)

(A) Abrasive grain, (B) C4 or higher aliphatic organic acid, (C) oxidizing agent, (D) nonionic surfactant represented by the following general formula (1), and (E) dispersion Containing medium ,
The chemical mechanical polishing aqueous dispersion, wherein a ratio of the blended amount of the (B) aliphatic organic acid having 4 or more carbon atoms to the blended amount of the (D) nonionic surfactant is 0.1 to 10 .

(1)
(In the formula, n and m are each independently an integer of 1 or more and satisfy n + m ≦ 50.) In claim 1,
The chemical mechanical polishing aqueous dispersion, wherein (A) the abrasive grains are inorganic particles having a primary particle diameter of 60 to 90 nm and an association degree of 1.5 to 4. In claim 1 or claim 2,
The chemical mechanical polishing aqueous dispersion, wherein (C) the oxidizing agent is hydrogen peroxide. In claims 1 to any one of claims 3,
When each of the copper layer, the conductive barrier layer, the first insulating layer, and the second insulating layer having a dielectric constant higher than that of the first insulating layer is subjected to chemical mechanical polishing under the same conditions, the polishing rate (R _B) and the polishing rate of the copper layer _{(R M)} and the polishing rate ratio _(which is _R B / R _M) of 1.5 or more, the polishing rate of the second insulating layer _{(R an in-2)} and the copper layer The polishing rate ratio (R _In-2 / R _M ) to the polishing rate (R _M ) is 0.9 to 2.5, and the polishing rate (R _In-2 ) of the second insulating layer is An aqueous dispersion for chemical mechanical polishing, wherein the polishing rate ratio (R _In-2 / R _In-1 ) to the polishing rate (R _In-1 ) of the first insulating layer is 0.5 to 5. A first polishing step in which a copper layer embedded in the recess and provided on the insulating layer having the recess through the stopper layer is subjected to chemical mechanical polishing until the stopper layer is exposed;
A second polishing step of chemically mechanically polishing the copper layer and the stopper layer until the insulating layer is exposed, using the chemical mechanical polishing aqueous dispersion according to any one of claims 1 to 4. ,
A chemical mechanical polishing method comprising: In claim 5 ,
The insulating layer includes a laminate of a first insulating layer and a second insulating layer having a dielectric constant higher than that of the first insulating layer,
The second polishing step is a chemical mechanical polishing method, wherein the copper layer, the stopper layer, and the second insulating layer are chemically mechanically polished. In claim 6 ,
The chemical mechanical polishing method, wherein the first dielectric layer has a relative dielectric constant of 3.5 or less. In claim 5 or claim 6 ,
The chemical mechanical polishing method, wherein the stopper layer is a conductive barrier layer.

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