JP2006316167A - Polishing composition for chemical mechanical polishing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing composition capable of keeping high flatness of a metal surface polished by chemical mechanical polishing (CMP) and a polishing composition for two-stage polishing achieving high polishing speed ratio between the copper layer in the first stage polishing and the barrier layer in the second stage polishing to enable the selective polishing of the copper layer. <P>SOLUTION: The invention provides a polishing composition for CMP (chemical mechanical polishing) containing a hydroxyalkane sulfonic acid fatty acid ester and a polishing composition for CMP containing 0.0001-10 mass% hydroxyalkane sulfonic acid fatty acid ester in the total polishing composition. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a composition for chemical mechanical polishing (hereinafter abbreviated as “CMP”), and is particularly preferably used for removing a copper layer when a wiring is formed by a damascene method in manufacturing a semiconductor device. The present invention relates to a polishing composition for CMP.

  In recent semiconductor manufacturing technology, a multi-layer wiring structure is inevitable with the high integration. Such a multilayer wiring structure is manufactured by repeating the film forming process a plurality of times. However, a process for planarizing the surface is essential after each layer is formed. One such global surface planarization technique is the CMP technique.

  In CMP technology, a wafer to be flattened is basically placed on a rotating plate, a pad (abrasive cloth) is brought into contact with the wafer surface, and a polishing slurry is supplied between the wafer and the pad while the rotating disk and the pad are placed. Both are rotated and polished. In the CMP technique, the wafer surface is polished by the mechanical action of the abrasive particles in the slurry and the pad surface, and at the same time, the wafer surface is flattened by a chemical reaction between the compound in the slurry and the wafer surface.

  When forming a wiring by a damascene method in the manufacture of a semiconductor device, a copper or copper alloy thin film is deposited and embedded on an insulating film in which a groove has been formed in advance, and a layer of excess copper other than the groove and CMP polishing is performed to remove the barrier metal layer. In the two-stage polishing method often performed in this CMP polishing, only the outermost copper layer is selectively polished in the first stage polishing while suppressing the dishing of the wiring portion copper layer to be smaller than the thickness of the tantalum-based barrier layer, In the second stage polishing, it is desired to selectively polish only the tantalum-based barrier layer exposed after polishing the outermost layer copper layer while suppressing erosion of the insulating film and the wiring portion copper layer. In addition to this, recently, it is also demanded that the surface condition and flatness of the metal surface be even better.

  Several proposals have been made as polishing compositions that can be used in CMP. For example, Patent Literature 1 discloses a metal polishing liquid containing a metal oxidizer, a metal oxide solubilizer, a metal anticorrosive, abrasive grains, an abrasive adsorbent, and water. A metal-polishing liquid containing 05-3.0 mass% abrasive grains, an oxidizing agent, a protective film forming agent, an acid and water is disclosed. Further, Patent Document 3 discloses a polishing liquid containing a metal oxidizing agent, a metal oxide dissolving agent, a protective film forming agent, a water-soluble polymer and water, and a polishing rate ratio between the metal and its barrier layer (metal / barrier layer). ) Is 10 or more, and a metal-polishing liquid in which the polishing rate ratio between the metal and the insulating film layer (metal / insulating film layer) is 100 or more is disclosed.

However, the technique described in Patent Document 1 has problems such as large dishing, and the technique described in Patent Document 2 does not have a sufficient polishing rate ratio between the barrier layer and the copper layer. However, the technique described in Patent Document 3 has a problem that the flatness of the polished surface is not sufficient.
JP 2004-319759 A JP 2001-127020 A JP 2002-176015 A

  In the present invention, a polishing composition capable of maintaining a high level of flatness of a metal surface after polishing by CMP, and further providing a high level of surface flatness, and also in a two-step polishing, a copper layer in the first-step polishing. It is an object of the present invention to provide a polishing composition having a high polishing rate ratio with respect to the barrier layer in the second stage polishing and capable of selectively polishing the copper layer.

  The inventors of the present invention have arrived at the present invention as a result of intensive studies in order to solve the above problems. That is, the present invention provides a polishing composition for CMP, which contains a hydroxyalkanesulfonic acid fatty acid ester.

  In the present invention, the content of the hydroxyalkanesulfonic acid fatty acid ester is an amount occupying 0.0001 to 10% by mass in the total amount of the polishing composition; and the water-soluble polymer is 0 in the total amount of the polishing composition. It is preferable to contain in the quantity which occupies 0.001-10 mass%.

  Moreover, in the said this invention, in polishing composition whole quantity, 0.01-30 mass% of abrasive grains, 0.01-30 mass% of oxidizing agents, 0.1-5 mass% of organic acids, and an interface Each containing an activator in an amount of 0.001 to 10% by mass; and the ratio of the polishing rate of the metal layer to the polishing rate of the barrier layer (the polishing rate of the metal layer / the polishing rate of the barrier layer) is 1, 000 or more is preferable.

  According to the present invention, when manufacturing a semiconductor device, particularly when forming wiring by the damascene method, it has excellent surface flatness, high polishing selectivity for the copper layer, and is preferably used for removing the copper layer. A polishing composition for CMP can be provided.

The hydroxyalkanesulfonic acid fatty acid ester contained in the polishing composition for CMP of the present invention has the following general formula (1):
R—O—R ¹ —SO ₃ M (1)
The compound represented by these is mentioned.

In the general formula (1), R ¹ represents an alkylene group, preferably an alkylene group having 2 to 4 carbon atoms. R ¹ is most preferably an ethylene group. When R ¹ is an ethylene group, the compound represented by the general formula (1) is isethionic acid fatty acid esters (acylated isethionic acids).

  In the general formula (1), R represents an acyl group, and the number of carbon atoms constituting the acyl group is preferably 6 to 24, more preferably 8 to 20. Preferred acyl groups include, for example, behenoyl, stearoyl, palmitoyl, decanoyl, nonanoyl, octanoyl, 2-ethylhexanoyl, isooctanoyl, isononanoyl, isodecanoyl, isotridecanoyl, isopalmitoyl, isostearoyl, isobehenoyl, myristylyl, oleyl, linoleoyl And linoleoyl.

In the general formula (1), M represents a hydrogen atom, a metal atom or ammonium. Examples of the metal atom include alkali metal atoms such as lithium, sodium and potassium, alkaline earth metal atoms such as magnesium and calcium (however, since the alkaline earth metal atom is usually divalent, M is M _1/2 As the ammonium, for example, ammonium ammonium; alkylamine ammonium such as methylamine, dimethylamine, ethylamine, diethylamine, (iso) propylamine and di (iso) propylamine; mono Ethanolamine, N-methylmonoethanolamine, N-ethylmonoethanolamine, diethanolamine, triethanolamine, monopropanolamine, dipropanolamine, tripropanolamine, 2-amino-2-methyl-1,3-propane Examples include diols, aminoethylethanolamine, and ammonium alkanolamines such as N, N, N ′, N′-tetrakis (2-hydroxypropyl) ethylenediamine.

  The content of the compound represented by the general formula (1) in the polishing composition for CMP of the present invention is 0 in the total amount of the polishing composition in order to obtain flatness of the metal surface after polishing and a good surface state. An amount occupying 0.0001 to 10% by mass is preferred. If the content of the compound is less than 0.0001% by mass, the flatness and surface state of the metal surface after polishing may be deteriorated. On the other hand, if the content exceeds 10% by mass, the surface state of the metal is Although it is good, the metal polishing rate is very low, and there is a case where the metal is hardly polished practically. As for content of this compound, the range of 0.001-1 mass% is further more preferable. The hydroxyalkanesulfonic acid fatty acid ester contained as an essential component in the polishing composition for CMP of the present invention gives high surface flatness to the polishing composition for CMP of the present invention.

  The CMP polishing composition of the present invention preferably further contains a water-soluble polymer. Examples of the water-soluble polymer include polyethylene glycol, polyvinyl pyrrolidone, polyvinyl alcohol, polyacrylic acid, polymethacrylic acid, polyacrylic hydrazide, and gelatin. The content of the water-soluble polymer is preferably an amount that occupies 0.001 to 10% by mass in the total amount of the polishing composition from the viewpoint of improving the dispersion stability of the abrasive grains. Agglomeration of the grains is promoted. On the other hand, if the content exceeds 10% by mass, it may be disadvantageous in terms of economy. The content of the water-soluble polymer is more preferably in the range of 0.01 to 1% by mass. By containing the water-soluble polymer, it is preferable because the polishing composition for CMP can give high polishing selectivity to the copper layer in addition to the flatness of the metal surface. In particular, a polishing composition for CMP having a polishing rate ratio (metal layer polishing rate / barrier layer polishing rate) of 1,000 or more can be provided. The polishing rate ratio between the metal layer and the barrier layer is more preferably 1,000,000 or less. In the present invention, the barrier layer means a barrier for the metal layer, and includes, for example, a tantalum film or a tantalum alloy film. The insulating layer includes, for example, a silicon oxide film that may be doped with other components.

  As polishing abrasive grains contained in the polishing composition for CMP of the present invention, silicon dioxide, aluminum oxide, cerium oxide, silicon nitride, zirconium oxide, silicon carbide, and manganese dioxide, which are conventionally used as polishing materials for CMP, have been basically used. In general, it is desirable to use silicon dioxide from the viewpoint of stability and the like, and among these, colloidal silica is most preferable. There are many types of colloidal silica having various particle diameters. In the polishing composition for CMP of the present invention, the particle diameter is preferably in the range of 1 to 300 nm, more preferably in the range of 5 to 90 nm.

  The content of the abrasive grains in the polishing composition for CMP of the present invention is preferably an amount occupying 0.01 to 30% by mass in the total amount of the polishing composition in order to improve the flatness of the polished surface, and the content is 0. If it is less than 0.01% by mass, the polishing rate may be slow. On the other hand, if the content exceeds 30% by mass, it may be difficult to suppress erosion. The content of the abrasive grains is more preferably in the range of 0.1 to 5% by mass.

  The CMP polishing composition of the present invention preferably contains an oxidizing agent, and examples of the oxidizing agent include persulfates such as potassium persulfate and ammonium persulfate, and hydrogen peroxide. Of these, ammonium persulfate is preferred. The content of the oxidizing agent is preferably an amount that occupies 0.01 to 30% by mass in the total amount of the polishing composition in order to improve the polishing rate and the flatness of the polished surface. A range is further preferred. If the content is less than 0.01% by mass, the polishing rate may be slow. On the other hand, if the content exceeds 30% by mass, it becomes difficult to suppress etching and dishing, and it is also dangerous in terms of handling. There is.

  The polishing composition for CMP of the present invention preferably contains an organic acid. Examples of the organic acid include lactic acid, acetic acid, oxalic acid, citric acid, malic acid, succinic acid, butyric acid, malonic acid, and glutaric acid. And monobasic acid compounds such as adipic acid, pimelic acid, benzoic acid, salicylic acid and phthalic acid, dibasic acid compounds and trivalent or higher polybasic acid compounds, among which oxalic acid is most preferred. In order to improve the flatness of the polished surface, the content of the organic acid is preferably an amount that occupies 0.1 to 5% by mass in the total amount of the polishing composition. If the content of the organic acid is less than 0.1% by mass, the polishing rate may be slow. On the other hand, if the content exceeds 5% by mass, it may be difficult to suppress dishing or erosion. The content of the organic acid is more preferably in the range of 0.1 to 3% by mass.

  Furthermore, the polishing composition for CMP of the present invention preferably contains a surfactant. As the surfactant, an anionic surfactant, a nonionic surfactant, or an amphoteric ionic surfactant can be used, but an anionic surfactant is preferably used, and a sulfonic acid (or salt thereof) type anionic surfactant. Is more preferable, and dodecylbenzenesulfonic acid or a salt thereof is most preferable. The content of the surfactant is preferably an amount occupying 0.001 to 10% by mass in the total amount of the polishing composition in order to improve the flatness of the polished surface. If the content is less than 0.001% by mass, it may be difficult to suppress dishing. On the other hand, if the content exceeds 10% by mass, the polishing rate may be slow. The content of the surfactant is more preferably in the range of 0.005 to 0.1% by mass.

  The polishing composition for CMP of the present invention preferably contains a pH adjuster. As the pH adjuster, ammonia, potassium hydroxide, ammonium hydroxide, sodium hydroxide, hydroxylamine, trimethylamine hydroxide, ammonium carbonate, potassium carbonate, sodium carbonate, lithium hydroxide, barium hydroxide, strontium hydroxide, etc. are used. be able to. The content of the pH adjusting agent is an amount capable of setting the pH of the polishing composition for CMP of the present invention to 3-11.

The CMP polishing composition of the present invention can contain an anticorrosive agent for the purpose of adjusting the polishing rate of copper. As the anticorrosive, nitrogen-containing compounds and salts thereof are preferable. Among these, benzotriazole and derivatives thereof such as benzotriazole, 2-methylbenzotriazole, 2-phenylbenzotriazole, 2-ethylbenzotriazole and 2-propylbenzotriazole are preferable. Furthermore, among these, benzotriazole is most preferable.
In the content of the polishing composition for CMP of the present invention, the balance is water.

  Preparation of the polishing composition for CMP of the present invention comprises the hydroxyalkanesulfonic acid fatty acid ester, abrasive grains, oxidizing agent, organic acid, surfactant, water-soluble polymer, and pH adjuster, as necessary. An appropriate amount of the anticorrosive agent is mixed in water so that the pH of the solution is in the range of 3 to 11, and each component is uniformly dispersed and dissolved. In this case, all the components may be mixed to form a one-component type composition, or one or more components, for example, only an oxidizing agent may be used and mixed with a mixture of all other components 2 A liquid type composition may be used.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.
[Examples 1-3 and Comparative Examples 1-2]
Colloidal silica with a particle size of 26 nm, ammonium persulfate, oxalic acid, potassium stearoyl isethionate, dodecylbenzenesulfonic acid and polyvinylpyrrolidone (Luvitec K30 Pulver BASF) are mixed in water at the ratios shown in Table 1 and used for various CMPs A polishing composition was prepared.
On the other hand, as the object to be polished, a wafer (1) having a copper film of 7500 mm (750 nm) formed by electrolytic plating, a tantalum nitride film of 150 mm (15 nm) by sputtering, and a tantalum of 150 mm (15 nm) formed on the upper surface thereof, respectively. Film and laminated wafer (2) and wafer (3) having a silicon oxide film of 3000 mm (300 nm) formed by plasma CVD method are prepared, cut into 3 × 3 cm shapes, and each of the above polishing compositions for CMP The film formation surface of each wafer was polished under the following conditions using an object.

(Polishing conditions)
Polishing machine: NF-300 (manufactured by Nano Factor)
Polishing pad: IC1400 (with XY groove) (Rodel Nitta)
Polishing time: 1 minute (tantalum film), 4 minutes (copper film)
Plate rotation speed: 60rpm
Carrier rotation speed: 60rpm
Polishing pressure: 2 psi
Polishing liquid supply rate: 100 ml / min

(Measurement of polishing rate ratio)
After the polishing of the wafers (1) and (2), each wafer is washed and dried, and each polishing rate of the copper layer (wafer (1)) and the tantalum film (wafer (2)) is measured by the following apparatus and method. Asked. The obtained results are shown in Table 1.
Measuring device: Loresta GP (Mitsubishi Chemical)
Measuring method: The polishing rate was calculated from the difference in film thickness before and after polishing.

(Evaluation of flatness and surface condition)
Next, a groove having a depth of 250 nm is formed in the silicon oxide film of the wafer (3), a tantalum nitride film is 150 mm (15 nm) by sputtering, a tantalum film is 150 mm (15 nm) on the upper surface, and an electrolytic plating method is further performed. After forming a copper film of 8000 mm (800 nm) by the above, a test piece for flatness evaluation was obtained by removing excess copper and forming a copper wiring only in the groove. The evaluation test piece was polished under the same conditions as described above except that the polishing time was 2 minutes. The polished specimen was evaluated for flatness and surface condition as follows. The obtained results are shown in Table 1.
Flatness:
○: The difference in height between the wafer surface convex part and the concave part is less than 30 nm. X: The difference in height between the wafer surface convex part and the concave part is 30 nm or more. Surface state:
○: No surface roughness on the copper wiring part ×: Surface roughness on the copper wiring part

[Examples 4 to 6 and Comparative Example 3]
Table 2 shows colloidal silica having a particle size of 26 nm, ammonium persulfate, oxalic acid, potassium myristoyleuisethionate or potassium 2-ethylhexanoylisethionate, dodecylbenzenesulfonic acid, and polyvinylpyrrolidone (Luvitec K30 Pulver BASF). The various polishing compositions for CMP were prepared by mixing with water at the ratio shown in FIG.
Using each of the above polishing compositions for CMP, polishing was performed under the same polishing target and polishing conditions as in Examples 1 to 3, and the polishing rate, flatness, and surface condition were evaluated on the same basis as in Examples 1 to 3 above. did. The results are shown in Table 2.

According to the present invention, when manufacturing a semiconductor device, particularly when forming wiring by the damascene method, it has excellent surface flatness, high polishing selectivity for the copper layer, and is preferably used for removing the copper layer. A polishing composition for CMP can be provided.

Claims (5)

  A chemical mechanical polishing (CMP) composition comprising a hydroxyalkanesulfonic acid fatty acid ester.   The polishing composition for CMP according to claim 1, wherein the content of the hydroxyalkanesulfonic acid fatty acid ester occupies 0.0001 to 10% by mass in the total amount of the polishing composition.   The polishing composition for CMP according to claim 1 or 2, wherein the water-soluble polymer is contained in an amount occupying 0.001 to 10% by mass in the total amount of the polishing composition.   In the total amount of the polishing composition, the abrasive grains are 0.01 to 30% by mass, the oxidizing agent is 0.01 to 30% by mass, the organic acid is 0.1 to 5% by mass, and the surfactant is 0.001 to 10%. The polishing composition for CMP according to any one of claims 1 to 3, which is contained in an amount occupying mass%. The polishing for CMP according to any one of claims 1 to 4, wherein a ratio of the polishing rate of the metal layer to the polishing rate of the barrier layer (the polishing rate of the metal layer / the polishing rate of the barrier layer) is 1,000 or more. Composition.