JP2008041781A - Composition for polishing, and polishing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composition for polishing that can be used more suitably in an application for polishing a conductive layer made of copper in a semiconductor wiring process, and to provide a polishing method using the composition for polishing. <P>SOLUTION: The composition for polishing contains an anion surface-active agent, such as polyoxyethylenelaurylether ammonium sulfate, a protective film forming agent, such as benzotriazole, and a nonion surface-active agent, such as polyoxyethylenealkylether. The pH of the composition for polishing ranges from 2 to 9. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a polishing composition used for polishing a copper conductive layer in a semiconductor wiring process and a polishing method using the same.

  In the semiconductor wiring process, usually, a barrier layer and a conductor layer are sequentially formed on an insulator layer having a trench. Thereafter, at least a portion of the conductor layer (outside portion of the conductor layer) located outside the trench and a portion of the barrier layer (outside portion of the barrier layer) located outside the trench are removed by chemical mechanical polishing. Patent Documents 1 and 2 disclose a polishing composition that can be used for polishing to remove an outer portion of a conductor layer when the conductor layer is made of copper.

  The polishing composition of Patent Document 1 includes compounds having a heterocyclic ring such as quinaldic acid and benzotriazole, surfactants such as sulfonates (anionic surfactants), oxidation such as ammonium persulfate and hydrogen peroxide. Agent and abrasive grains such as silica. The polishing composition of Patent Document 2 includes a compound having a heterocyclic ring such as quinaldic acid and benzotriazole, a surfactant having a triple bond such as acetylene glycol (nonionic surfactant), ammonium persulfate and hydrogen peroxide. Such an oxidizing agent and abrasives such as silica are contained, and if necessary, ammonium dodecylbenzenesulfonate (anionic surfactant) is further contained.

The polishing composition used for polishing for removing the outer portion of the conductor layer is required to have at least the following two performances.
(1) To suppress the occurrence of a phenomenon called dishing in which the level of the upper surface of the conductor layer is reduced by removing the portion of the conductor layer (inner portion of the conductor layer) located in the trench.

(2) The polishing rate of the conductor layer with the polishing composition is high, that is, the removal rate of the conductor layer with the polishing composition is high.
However, the polishing compositions of Patent Documents 1 and 2 do not sufficiently satisfy these required performances, and there is still room for improvement.
JP 2002-12854 A JP 2002-256256 A

  The objective of this invention is providing the polishing composition which can be used more suitably for the use which grind | polishes the conductor layer which consists of copper in a semiconductor wiring process, and the grinding | polishing method using the same.

In order to achieve the above object, the invention described in claim 1 has the chemical formula: R1-Y1 or R1-X1-Y1 (wherein R1 represents an alkyl group, an alkylphenyl group or an alkenyl group, and X1 represents a polyoxy It represents an ethylene group, a polyoxypropylene group or a poly (oxyethylene / oxypropylene) group, and Y1 represents an SO ₃ M1 group or an SO ₄ M1 group (where M1 represents a counter ion). At least one anionic surfactant, a protective film forming agent different from the anionic surfactant, and a chemical formula: R2-X2 (where R2 represents an alkyl group, X2 is a polyoxyethylene group, a polyoxypropylene group) Or a poly (oxyethylene / oxypropylene) group) and at least one nonio having an HLB value of 10 to 16. And a polishing composition characterized by having a pH of 2 to 9.

  In the invention according to claim 2, the average number of repeating units in the polyoxyethylene group, polyoxypropylene group or poly (oxyethylene oxypropylene) group of the nonionic surfactant is 2 to 20. The polishing composition according to 1, is provided.

  In the invention according to claim 3, the average number of repeating units in the polyoxyethylene group, polyoxypropylene group or poly (oxyethylene / oxypropylene) group of the anionic surfactant is 6 or less. Alternatively, the polishing composition according to 2 is provided.

  The invention according to claim 4 provides the polishing composition according to any one of claims 1 to 3, wherein M1 in the anionic surfactant is a potassium cation, an ammonium cation, or an amine cation.

  According to a fifth aspect of the present invention, a conductor layer made of copper is provided on an insulator layer having a trench, and an outer portion where the conductor layer is located outside the trench and an inner portion located inside the trench are provided. A method for polishing an object to be polished is provided. The method includes any of the steps of removing most of the outer portion of the conductor layer by polishing using the preliminary polishing composition, and a final polishing composition different from the preliminary polishing composition. And a step of removing the remainder of the outer portion of the conductor layer by polishing using the polishing composition according to one item.

  ADVANTAGE OF THE INVENTION According to this invention, the polishing composition which can be used more suitably for the use which grind | polishes the conductor layer which consists of copper in a semiconductor wiring process, and the grinding | polishing method using the same are provided.

Hereinafter, an embodiment of the present invention will be described.
First, the semiconductor wiring process will be described with reference to FIGS. 1 (a) to 1 (d). The semiconductor wiring process usually includes the following steps.

  First, as shown in FIG. 1A, a barrier layer 13 and a conductor layer 14 are sequentially formed on an insulator layer 12 provided on a semiconductor substrate (not shown) and having a trench 11. Prior to the formation of the conductor layer 14, the barrier layer 13 is formed on the insulator layer 12 so as to cover the surface of the insulator layer 12. The thickness of the barrier layer 13 is smaller than the depth of the trench 11. Following the formation of the barrier layer 13, the conductor layer 14 is formed on the barrier layer 13 so that at least the trench 11 is filled.

  Thereafter, at least a portion of the conductor layer 14 located outside the trench 11 (outside portion of the conductor layer 14) and a portion of the barrier layer 13 located outside the trench 11 (outside portion of the barrier layer 13) are removed by chemical mechanical polishing. To do. As a result, as shown in FIG. 1 (d), at least a part of the portion of the barrier layer 13 (inner portion of the barrier layer 13) located in the trench 11 and a portion of the conductor layer 14 located in the trench 11 At least a part of (the inner portion of the conductor layer 14) remains on the insulator layer 12. That is, a part of the barrier layer 13 and a part of the conductor layer 14 remain inside the trench 11. Thus, the portion of the conductor layer 14 remaining inside the trench 11 functions as a wiring.

  When removing at least the outer portion of the conductor layer 14 and the outer portion of the barrier layer 13 by chemical mechanical polishing, first, most of the outer portion of the conductor layer 14 is removed as shown in FIG. Next, as shown in FIG. 1C, the remainder of the outer portion of the conductor layer 14 is removed to expose the upper surface of the outer portion of the barrier layer 13. Thereafter, as shown in FIG. 1D, the outer portion of the barrier layer 13 is removed to expose the upper surface of the insulator layer 12 and to obtain a flat surface.

  The polishing composition of the present embodiment is used for polishing the conductor layer 14 in such a semiconductor wiring process when the conductor layer 14 is made of copper. More specifically, the outer side of the conductor layer 14 is used. It is particularly suitable for use in polishing to remove the remainder of the outer portion of the conductor layer 14 after most of the portion has been removed.

  The polishing composition of this embodiment is obtained by mixing a predetermined amount of an anionic surfactant, a protective film forming agent, and a nonionic surfactant with water, preferably together with a predetermined amount of an oxidizing agent, an etching agent, and abrasive grains. It is manufactured so that the pH is 2-9. Therefore, the polishing composition of this embodiment contains an anionic surfactant, a protective film forming agent, a nonionic surfactant and water, and preferably further contains an oxidizing agent, an etching agent and abrasive grains.

  The anionic surfactant contained in the polishing composition of the present embodiment has an action of forming a protective film by being electrically adsorbed on the surface of the conductor layer 14 in a neutral to acidic pH range. In the neutral to acidic pH range, the surface potential of the conductor layer 14 made of copper is positive. Therefore, an anionic group that is a hydrophilic portion of the anionic surfactant is bonded to the surface of the conductor layer 14, and a hydrophobic portion of the anionic surfactant is located on the side opposite to the surface of the conductor layer 14. Therefore, the surface of the protective film made of an anionic surfactant has hydrophobicity. When a protective film made of an anionic surfactant is formed on the surface of the conductor layer 14, the affinity between the surface of the conductor layer 14 and the abrasive grains decreases, and the polishing rate of the conductor layer 14 by the polishing composition decreases. To do. As a result, excessive removal of the inner portion of the conductor layer 14 is suppressed, and the occurrence of dishing (see FIG. 2) is suppressed.

The anionic surfactant contained in the polishing composition contains at least one compound selected from compounds represented by the chemical formula: R1-Y1 or R1-X1-Y1. However, R1 represents an alkyl group, an alkylphenyl group, or an alkenyl group, X1 represents a polyoxyethylene group, a polyoxypropylene group, or a poly (oxyethylene / oxypropylene) group, and Y1 represents an SO ₃ M1 group or SO ₄ M1. Represents a group. M1 in the SO ₃ M1 group and SO ₄ M1 group represents a counter ion. The counter ions are not particularly limited, for example, ammonium cations, amine cations, and alkali metal cations such as lithium cations, sodium cations, and potassium cations. Among them, from the viewpoint of improving the polishing rate of the conductor layer 14 by the polishing composition, it is preferably a potassium cation, an ammonium cation or an amine cation, more preferably an ammonium cation or a triethanolamine cation, most preferably It is an ammonium cation.

  The content of the anionic surfactant in the polishing composition is closely related to the suppression of dishing and the polishing rate. If this amount is too small, a protective film sufficient to strongly suppress excessive polishing of the conductor layer 14 is not formed on the surface of the conductor layer 14, and as a result, the occurrence of dishing may not be suppressed so strongly. From the viewpoint of strongly suppressing the occurrence of dishing, the content of the anionic surfactant in the polishing composition is preferably 0.01 g / L or more, more preferably 0.03 g / L or more, and further Preferably it is 0.05 g / L or more, still more preferably 0.08 g / L or more, and most preferably 0.1 g / L or more. On the other hand, when the content of the anionic surfactant in the polishing composition is too large, the polishing of the conductor layer 14 may be excessively suppressed due to the excessive formation of the protective film on the surface of the conductor layer 14. . In order to keep the polishing rate of the conductor layer 14 with the polishing composition high, the content of the anionic surfactant in the polishing composition is preferably 10 g / L or less, more preferably 5 g / L or less, More preferably, it is 1 g / L or less, More preferably, it is 0.5 g / L or less, Most preferably, it is 0.3 g / L or less.

  When the anionic surfactant contained in the polishing composition contains a compound represented by the chemical formula: R1-X1-Y1, the average number of repeating units in X1 is the metal corrosion of the wiring edge portion in the conductor layer 14 There is a close relationship. When this is too much, there is a possibility that metal corrosion called a slit may occur at the wiring edge portion. From the viewpoint of suppressing the occurrence of metal corrosion at the wiring edge portion, the average number of repeating units in X1 is preferably 6 or less, more preferably 4 or less, and most preferably 2 or less.

  The protective film forming agent contained in the polishing composition of the present embodiment has an action of forming a protective film by adsorbing to the surface of the conductor layer 14. The surface of the protective film formed by this protective film forming agent is hydrophobic. When a protective film with a protective film forming agent is formed on the surface of the conductor layer 14, the affinity between the surface of the conductor layer 14 and the abrasive grains decreases, and the polishing rate of the conductor layer 14 with the polishing composition decreases. To do. As a result, excessive removal of the inner portion of the conductor layer 14 is suppressed, and the occurrence of dishing is suppressed.

  The protective film forming agent contained in the polishing composition may be benzotriazole or a benzotriazole derivative. The benzotriazole derivative is formed by replacing the hydrogen atom bonded to the five-membered ring of benzotriazole with another atomic group. From the viewpoint of suppressing the occurrence of dishing more strongly, the protective film forming agent contained in the polishing composition is preferably benzotriazole. The protective film made of benzotriazole has a hydrophobic surface because the five-membered ring portion of benzotriazole is bonded to the surface of the conductor layer 14 and the benzene ring portion of benzotriazole is located on the side opposite to the surface of the conductor layer 14. have. The protective film of the benzotriazole derivative is formed by bonding the five-membered ring portion of the benzotriazole derivative to the surface of the conductor layer 14 and positioning the benzene ring portion of the benzotriazole derivative on the side opposite to the surface of the conductor layer 14. Has hydrophobicity.

  The content of the protective film forming agent in the polishing composition is closely related to the suppression of dishing and the polishing rate. If this amount is too small, a protective film sufficient to strongly suppress excessive polishing of the conductor layer 14 is not formed on the surface of the conductor layer 14, and as a result, the occurrence of dishing may not be suppressed much. From the viewpoint of suppressing the occurrence of dishing more strongly, the content of the protective film forming agent in the polishing composition is preferably 0.001 g / L or more, more preferably 0.01 g / L or more. . On the other hand, when the content of the protective film forming agent in the polishing composition is too large, there is a possibility that the polishing of the conductor layer 14 is excessively suppressed due to the excessive formation of the protective film on the surface of the conductor layer 14. . In order to keep the polishing rate of the conductor layer 14 with the polishing composition high, the content of the protective film forming agent in the polishing composition is preferably 1 g / L or less, more preferably 0.2 g / L. It is as follows.

  The nonionic surfactant contained in the polishing composition of the present embodiment has an action of forming a protective film by adsorbing to the hydrophobic surface of the protective film by the anionic surfactant and the protective film forming agent. The hydrophobic part of the nonionic surfactant binds to the hydrophobic surface of the protective film formed by the anionic surfactant and the protective film forming agent, and the hydrophilic part of the nonionic surfactant forms the protective film formed by the anionic surfactant and the protective film forming agent. Located on the opposite side of the hydrophobic surface. For this reason, the surface of the protective film made of the nonionic surfactant formed on the hydrophobic surface of the protective film made of the anionic surfactant and the protective film forming agent has hydrophilicity. When the protective film by the nonionic surfactant is formed on the hydrophobic surface of the protective film by the anionic surfactant and the protective film forming agent, the affinity between the surface of the conductor layer 14 and the abrasive grains is improved, and polishing is performed. The polishing rate of the conductor layer 14 by the composition for use is improved. As a result, an excessive decrease in the polishing rate of the conductor layer 14 by the polishing composition due to the use of the anionic surfactant and the protective film forming agent is suppressed.

  The nonionic surfactant contained in the polishing composition contains at least one selected from nonionic surfactants represented by the chemical formula: R2-X2 and having an HLB value of 10 to 16. However, R2 represents an alkyl group, and X2 represents a polyoxyethylene group, a polyoxypropylene group or a poly (oxyethylene / oxypropylene) group.

  The content of the nonionic surfactant in the polishing composition is closely related to the reduction in polishing rate and the suppression of dishing. When this is too small, there is a possibility that an excessive decrease in the polishing rate of the conductor layer 14 is not suppressed so strongly. From the viewpoint of more strongly suppressing an excessive decrease in the polishing rate of the conductor layer 14, the content of the nonionic surfactant in the polishing composition is preferably 0.01 g / L or more, more preferably 0. 0.05 g / L or more, more preferably 0.1 g / L or more, and most preferably 0.3 g / L or more. On the other hand, when the content of the nonionic surfactant in the polishing composition is too large, the dishing suppression action by the anionic surfactant and the protective film forming agent may be weakened. As a result, dishing is likely to occur. There is a fear. In addition, the ability of the polishing composition for polishing the conductor layer 14 may decrease instead. From the viewpoint of suppressing the occurrence of dishing more strongly, the content of the nonionic surfactant in the polishing composition is preferably 20 g / L or less, more preferably 10 g / L or less, and even more preferably 5 g / L. L or less, most preferably 3 g / L or less.

  The nonionic surfactant contained in the polishing composition of this embodiment has a physical parameter called cloud point. This cloud point is closely related to the strength of the corrosive action of the polishing composition. When the clouding point of the nonionic surfactant contained in the polishing composition is too high, the corrosive action of the polishing composition may be excessively increased. From the viewpoint of suppressing an excessive increase in the corrosive action of the polishing composition, the cloud point of the nonionic surfactant contained in the polishing composition is preferably 90 ° C. or less, more preferably 50 ° C. or less. Most preferably, it is 35 ° C. or lower.

  The average number of repeating units in X2 of the nonionic surfactant contained in the polishing composition is closely related to the solubility of the nonionic surfactant in water. When this amount is too small, the nonionic surfactant becomes difficult to dissolve in water. From the viewpoint of increasing the solubility of the nonionic surfactant in water, the average number of repeating units in X2 is preferably 2 or more, more preferably 3 or more. On the other hand, when the average number of repeating units in the nonionic surfactant X2 contained in the polishing composition is too large, metal corrosion may occur in the wiring edge portion of the conductor layer 14. From the viewpoint of suppressing the occurrence of metal corrosion at the wiring edge portion, the average number of repeating units in X2 is preferably 20 or less, more preferably 15 or less, and most preferably 10 or less.

  The HLB value of the nonionic surfactant contained in the polishing composition is closely related to the reduction in polishing rate and the suppression of dishing. If this is too low, an excessive decrease in the polishing rate of the conductor layer 14 may not be suppressed so strongly. From the viewpoint of more strongly suppressing an excessive decrease in the polishing rate of the conductor layer 14, the nonionic surfactant contained in the polishing composition preferably has an HLB value of 10 or more, more preferably 10.5 or more. More preferably, it is 11 or more, and most preferably 11.5 or more. On the other hand, when the HLB value of the nonionic surfactant contained in the polishing composition is too high, the dishing suppression action by the anionic surfactant and the protective film forming agent may be weakened. As a result, dishing is likely to occur. There is a risk of becoming. From the viewpoint of suppressing the occurrence of dishing more strongly, the HLB value of the nonionic surfactant in the polishing composition is preferably 16 or less, more preferably 15 or less, still more preferably 14 or less, and most preferably 13.5 or less. In addition, the HLB value of a nonionic surfactant is calculated | required by the Griffin method, for example.

  It is preferable that the polishing composition of this embodiment further contains an oxidizing agent. The oxidizing agent has an action of oxidizing the conductor layer 14 and functions to improve the polishing rate of the conductor layer 14 by the polishing composition. The oxidizing agent contained in the polishing composition may be a peroxide such as hydrogen peroxide and ammonium persulfate. Hydrogen peroxide is preferable from the viewpoint of reducing metal contamination of the conductor layer 14 derived from the oxidizing agent.

  When there is too little content of the oxidizing agent in polishing composition, the grinding | polishing speed | rate of the conductor layer 14 by polishing composition does not improve so much. From the viewpoint of greatly improving the polishing rate of the conductor layer 14 with the polishing composition, the content of the oxidizing agent in the polishing composition is preferably 1 g / L or more, more preferably 3 g / L or more. Most preferably, it is 5 g / L or more. On the other hand, when there is too much content of the oxidizing agent in polishing composition, there exists a possibility that the polishing capability of the polishing composition with respect to the conductor layer 14 may become high, and dishing may occur easily. From the viewpoint of suppressing the occurrence of dishing more strongly, the content of the oxidizing agent in the polishing composition is preferably 30 g / L or less, more preferably 20 g / L or less, and most preferably 15 g / L or less. It is.

  It is preferable that the polishing composition of this embodiment further contains an etching agent. An etching agent has the effect | action which etches the conductor layer 14, and functions to improve the grinding | polishing speed | rate of the conductor layer 14 by polishing composition. The etching agent contained in the polishing composition may be an α-amino acid such as glycine, alanine, or valine. From the viewpoint of greatly increasing the polishing rate of the conductor layer 14 with the polishing composition, glycine is preferable.

  When the content of the etching agent in the polishing composition is too small, the polishing rate of the conductor layer 14 by the polishing composition is not greatly improved. From the viewpoint of greatly improving the polishing rate of the conductor layer 14 with the polishing composition, the content of the etching agent in the polishing composition is preferably 0.5 g / L or more, more preferably 1 g / L. L or more, more preferably 3 g / L or more, and most preferably 5 g / L or more. On the other hand, when there is too much content of the etching agent in polishing composition, there exists a possibility that the polishing capability of the polishing composition with respect to the conductor layer 14 may become high, and dishing may occur easily. From the viewpoint of suppressing the occurrence of dishing more strongly, the content of the etching agent in the polishing composition is preferably 50 g / L or less, more preferably 30 g / L or less, and even more preferably 20 g / L or less. Most preferably, it is 15 g / L or less.

  It is preferable that the polishing composition of this embodiment further contains abrasive grains. The abrasive has a role of mechanically polishing the conductor layer 14 and functions to improve the polishing rate of the conductor layer 14 by the polishing composition. The abrasive grains contained in the polishing composition may be silica. From the viewpoint of reducing surface defects of the conductor layer 14 after polishing, colloidal silica is preferable.

  When there is too little content of the abrasive grain in polishing composition, the grinding | polishing speed | rate of the conductor layer 14 by polishing composition does not improve so much. From the viewpoint of greatly improving the polishing rate of the conductor layer 14 with the polishing composition, the content of abrasive grains in the polishing composition is preferably 0.5 g / L or more, more preferably 1 g / L. L or more, most preferably 5 g / L or more. On the other hand, if the content of abrasive grains in the polishing composition is too large, the polishing ability of the polishing composition for the conductor layer 14 becomes too high, and dishing may easily occur. From the viewpoint of suppressing the occurrence of dishing more strongly, the content of abrasive grains in the polishing composition is preferably 100 g / L or less, more preferably 50 g / L or less, and most preferably 20 g / L or less. It is.

  When the average primary particle diameter of the abrasive grains contained in the polishing composition is too small, the polishing rate of the conductor layer 14 by the polishing composition is not greatly improved. From the viewpoint of greatly improving the polishing rate of the conductor layer 14 with the polishing composition, the average primary particle diameter of the abrasive grains contained in the polishing composition is preferably 3 nm or more, more preferably 5 nm or more, Most preferably, it is 8 nm or more. On the other hand, when the average primary particle diameter of the abrasive grains contained in the polishing composition is too large, the abrasive grains easily settle in the polishing composition. From the viewpoint of preventing the settling of the abrasive grains, the average primary particle diameter of the abrasive grains contained in the polishing composition is preferably 200 nm or less, more preferably 100 nm or less, and most preferably 50 nm or less. The average primary particle diameter of the abrasive grains is calculated from the specific surface area of the abrasive grains measured by the BET method.

  The pH of the polishing composition of this embodiment is closely related to the adsorption action of the anionic surfactant on the surface of the conductor layer 14. In order for this adsorption action to work suitably, the pH of the polishing composition is required to be acidic from near neutrality. However, since considerable dishing occurs when the pH of the polishing composition is in a strongly acidic region, it is essential that the polishing composition has a pH of 2 or more. Further, from the viewpoint of suppressing the occurrence of dishing more strongly, the pH of the polishing composition is preferably 4 or more, more preferably 6 or more. On the other hand, when the pH of the polishing composition is in the alkaline region, the etching agent in the polishing composition is easily decomposed over time, and the pot life of the polishing composition is greatly reduced. Therefore, it is essential that the polishing composition has a pH of 9 or less. Moreover, when pH of polishing composition exceeds 9, there exists a possibility that formation of the protective film by an anionic surfactant may be prevented. From the viewpoint of further improving the pot life of the polishing composition, the pH of the polishing composition is preferably 8.5 or less, more preferably 8 or less.

According to the present embodiment, the following advantages can be obtained.
The polishing composition of the present embodiment contains an anionic surfactant and a protective film forming agent as components that function to suppress the occurrence of dishing, and an anionic surface activity of the polishing rate of the conductor layer 14 by the polishing composition. Nonionic surfactant is contained as a component which functions to suppress excessive reduction due to the use of the agent and the protective film forming agent. Therefore, according to the polishing composition of this embodiment, both the required performance related to dishing and the required performance related to the polishing rate can be satisfied. Therefore, the polishing composition of the present embodiment can be suitably used for the purpose of polishing the conductor layer 14 in the semiconductor wiring process.

The embodiment may be modified as follows.
-The polishing composition of the said embodiment may be prepared by diluting a concentrate concentrate before use.

-You may add well-known additives, such as a pH adjuster, antiseptic | preservative, and an antifoamer, to the polishing composition of the said embodiment as needed.
Next, examples and comparative examples of the present invention will be described.

  For polishing Examples 1 to 26 and Comparative Examples 1 to 10 by appropriately mixing an anionic surfactant, a protective film forming agent, a nonionic surfactant, an oxidizing agent, an etching agent, abrasive grains, and a pH adjuster with water. A composition was prepared. Tables 1 and 2 show the details of the anionic surfactant, the protective film forming agent, the nonionic surfactant, the oxidizing agent, the etching agent, the abrasive grains, and the pH adjusting agent in each polishing composition, and the pH of each polishing composition. As shown in

  In the “polishing rate” column of Tables 1 and 2, a copper blanket wafer having a diameter of 200 mm was polished under the polishing conditions shown in Table 3 using the polishing compositions of Examples 1 to 26 and Comparative Examples 1 to 10. The polishing rate sometimes obtained is shown. The polishing rate was determined by dividing the difference in thickness of each wafer before and after polishing by the polishing time. For measuring the thickness of the wafer, a sheet resistance measuring machine “VR-120” manufactured by Kokusai Electric System Service Co., Ltd. was used.

  In the "Dishing" column of Tables 1 and 2, the dishing amount was measured with a copper pattern wafer (854 mask pattern) of SEMATEC that was polished using the polishing compositions of Examples 1 to 26 and Comparative Examples 1 to 10. The results are shown. Specifically, a copper pattern wafer of SEMATEC is formed by sequentially providing a barrier layer made of tantalum and a copper conductor layer having a thickness of 1000 nm on an insulator layer made of silicon dioxide having a trench, and having a depth of 500 nm. Initial recesses on the top surface. Before polishing this copper pattern wafer with the polishing compositions of Examples 1 to 26 and Comparative Examples 1 to 10, using a polishing material “PLANERLITE-7105” manufactured by Fujimi Incorporated, Pre-polishing was performed under the polishing conditions shown in Table 3 until the thickness reached 300 nm. Subsequently, using the polishing compositions of Examples 1 to 26 and Comparative Examples 1 to 10, the copper pattern wafer after preliminary polishing was polished under the polishing conditions shown in Table 3 until the upper surface of the barrier layer was exposed. Thereafter, using a profiler “HRP340” which is a contact surface measuring device manufactured by KLA-Tencor Corporation, the dishing amount was measured in each wafer region in which trenches having a width of 100 μm were formed in isolation.

  In the “pot life” column of Tables 1 and 2, the results of evaluating the pot life of the polishing compositions of Examples 1 to 26 and Comparative Examples 1 to 10 are shown. Specifically, the polishing compositions of Examples 1 to 26 and Comparative Examples 1 to 10 immediately after preparation, and Examples 1 to 26 and Comparative Examples 1 to 26 which were allowed to stand in a thermostatic bath at 25 ° C. after preparation for 14 days. The copper blanket wafer was polished under the polishing conditions shown in Table 3 using each of the 10 polishing compositions. Then, the polishing rate is calculated by dividing the difference in thickness of each wafer before and after polishing by the polishing time, and the polishing rate at the polishing composition immediately after preparation and the polishing composition kept at 25 ° C. for 14 days. Based on the comparison of the polishing rate, the pot life of each polishing composition was evaluated. In the “pot life” column, ○ (good) indicates that the rate of decrease in the polishing rate was 5% or less, Δ (somewhat poor) indicates that the rate of decrease in the polishing rate is 5 to 10%, and × (defect) indicates It shows that the reduction rate of the polishing rate was 10% or more.

  In the “Corrosive” column of Tables 1 and 2, the results of evaluating the strength of the corrosive action of the polishing compositions of Examples 1 to 26 and Comparative Examples 1 to 10 are shown. Specifically, in the wiring edge portion of the 0.25 μm wide wiring in the SEMATEC copper pattern wafer polished using the polishing compositions of Examples 1 to 26 and Comparative Examples 1 to 10, Hitachi High-Technology's The presence or absence of corrosion was observed using the review SEM RS-400. Based on the observation results, the strength of the corrosive action of each polishing composition was evaluated. In the “Corrosive” column, ○ (good) indicates that no corrosion was observed, and × indicates that corrosion was observed.

表１及び表２の“アニオン界面活性剤”欄中、Ａ１はオキシエチレン単位の平均繰り返し数が２であるポリオキシエチレンラウリルエーテル硫酸アンモニウムを表し、Ａ２はオキシエチレン単位の平均繰り返し数が１．５であるポリオキシエチレンラウリルエーテル硫酸トリエタノールアミンを表し、Ａ３はオキシエチレン単位の平均繰り返し数が２であるポリオキシエチレンラウリルエーテルスルホン酸アンモニウムを表し、Ａ４はラウリルスルホン酸アンモニウムを表し、Ａ５はラウリルベンゼンスルホン酸アンモニウムを表し、Ａ６はラウリル硫酸アンモニウムを表す。

In the “anionic surfactant” column in Tables 1 and 2, A1 represents polyoxyethylene lauryl ether ammonium sulfate having an average number of repeating oxyethylene units of 2, and A2 has an average number of repeating oxyethylene units of 1.5. Polyoxyethylene lauryl ether sulfate triethanolamine, A3 represents polyoxyethylene lauryl ether sulfonate ammonium having an average number of repeating oxyethylene units of 2, A4 represents ammonium lauryl sulfonate, and A5 represents lauryl. A6 represents ammonium benzenesulfonate, and A6 represents ammonium lauryl sulfate.

In the “protective film forming agent” column of Tables 1 and 2, B1 represents benzotriazole.
In the column of “nonionic surfactant” in Tables 1 and 2, C1 represents a polyoxyethylene alkyl ether having an average number of oxyethylene unit repeats of 7, and C2 has an average number of repeats of oxyethylene units of 4.2. Represents a certain polyoxyethylene lauryl ether, C3 represents a polyoxyethylene lauryl ether having an average number of repeating oxyethylene units of 9, C4 represents acetylenic diol, and C5 has an average number of repeating oxyethylene units of 30 Polyoxyethylene lauryl ether is represented, and C6 represents polyoxyethylene lauryl ether having an average number of repeating oxyethylene units of 2. In addition, carbon number of the alkyl group in polyoxyethylene alkyl ether is 12-14.

In the “oxidant” column of Tables 1 and 2, D1 represents hydrogen peroxide.
In the “Etching Agent” column of Tables 1 and 2, E1 represents glycine.
In the “Abrasive Grain” column in Tables 1 and 2, F1 represents colloidal silica.

  In the “pH adjuster” column of Tables 1 and 2, G1 represents potassium hydroxide, and G2 represents nitric acid.

表１及び表２に示すように、実施例１〜２６においては研磨速度、ディッシング、ポットライフ及び腐食性のいずれに関しても実用上満足できる結果が得られた。それに対し、比較例１〜１０においては、研磨速度、ディッシング及びポットライフのうち少なくともいずれか一つに関して実用上満足できる結果が得られなかった。なお、比較例１，４，５，７，１１，１３の“ディッシング”欄、“ポットライフ”欄及び“腐食性”欄のハイフン（−）は、研磨速度が低すぎて測定又は評価が不能であったことを示す。

As shown in Tables 1 and 2, in Examples 1 to 26, practically satisfactory results were obtained with respect to any of the polishing rate, dishing, pot life and corrosiveness. On the other hand, in Comparative Examples 1 to 10, practically satisfactory results were not obtained with respect to at least one of the polishing rate, dishing, and pot life. The hyphens (-) in the "Dishing" column, "Pot life" column, and "Corrosive" column of Comparative Examples 1, 4, 5, 7, 11, and 13 are too slow to be measured or evaluated. It shows that it was.

(A)-(d) is sectional drawing of the grinding | polishing target object for demonstrating a semiconductor wiring process. Sectional drawing of the grinding | polishing target object for demonstrating dishing.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Trench, 12 ... Insulator layer, 14 ... Conductor layer.

Claims (5)

Chemical formula: R1-Y1 or R1-X1-Y1 (where R1 represents an alkyl group, an alkylphenyl group or an alkenyl group, and X1 represents a polyoxyethylene group, a polyoxypropylene group or a poly (oxyethylene / oxypropylene) group) Y1 represents an SO ₃ M1 group or an SO ₄ M1 group (where M1 represents a counter ion); and at least one anionic surfactant represented by:
A protective film forming agent different from the anionic surfactant;
Chemical formula: R2-X2 (wherein R2 represents an alkyl group, X2 represents a polyoxyethylene group, a polyoxypropylene group or a poly (oxyethylene / oxypropylene) group), and has an HLB value of 10 to 10. A polishing composition comprising at least one nonionic surfactant that is 16 and a pH of 2 to 9.   The polishing composition according to claim 1, wherein the average number of repeating units in the polyoxyethylene group, polyoxypropylene group or poly (oxyethylene / oxypropylene) group of the nonionic surfactant is 2 to 20.   The polishing composition according to claim 1 or 2, wherein the average number of repeating units in the polyoxyethylene group, polyoxypropylene group or poly (oxyethylene / oxypropylene) group of the anionic surfactant is 6 or less. .   The polishing composition according to any one of claims 1 to 3, wherein M1 in the anionic surfactant is a potassium cation, an ammonium cation, or an amine cation. A method of polishing an object to be polished having a conductor layer made of copper on an insulator layer having a trench, the conductor layer having an outer portion located outside the trench and an inner portion located inside the trench. There,
Removing most of the outer portion of the conductor layer by polishing with a pre-polishing composition;
Removing the remainder of the outer portion of the conductor layer by polishing using the polishing composition according to any one of claims 1 to 4 as a final polishing composition different from the preliminary polishing composition. How to prepare.

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