JP2005082791A - Polishing composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a polishing composition solving such problems that, in polishing a semiconductor device having a copper film and a tantalum compound, the polishing selection ratio for the copper and the tantalum compound is inadequate, or when the selection ratio to the copper is raised, the copper film at wiring grooves or holes is overshaved or the smoothness of the surface of the copper film is impaired. <P>SOLUTION: This polishing composition is obtained by mixing a cocondensate, which has a mean particle size of 40 nm, of polymethyl methacrylate(PMMA) and divinylbenzene, glycine, benzotriazole, quinaldic acid, hydrogen peroxide and ethanolamine into ion-exchange water filtered through a 0.5 μm cartridge filter so that their concentrations come to specific values, respectively, followed by carrying out an agitation by using a high-speed homogenizer to effect their homogeneous dispersion. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a polishing composition used for polishing semiconductors, various memory hard disk substrates and the like, and more particularly to a polishing composition suitably used for surface planarization of semiconductor device wafers.

  Recent advances in the electronics industry have evolved into transistors, ICs, LSIs, and ultra-LSIs. As the degree of circuit integration in these semiconductor elements has increased rapidly, the design rules for semiconductor devices have become finer year by year. The depth of focus in the device manufacturing process has become shallower, and the flatness of the pattern formation surface has become increasingly severe

  On the other hand, in order to cover the increase in wiring resistance due to the miniaturization of wiring, copper wiring having a smaller electrical resistance has been studied as a wiring material from aluminum or tungsten. However, when copper is used for interconnection between wiring layers and wirings, after forming wiring grooves and holes on the insulating film, a copper film is formed by sputtering or plating, and unnecessary portions are chemically and mechanically polished. It is necessary to remove unnecessary copper on the insulating film by (CMP).

  In such a process, copper diffuses into the insulating film and deteriorates the device characteristics. Therefore, it is common to provide a tantalum or tantalum nitride layer as a barrier layer on the insulating film to prevent copper diffusion. It has become.

In the planarization CMP process of the device having the copper film formed as the uppermost layer in this manner, the unnecessary portion of the copper film is first polished to the surface layer of the tantalum compound formed on the insulating layer, and the next step Then, the tantalum compound layer on the insulating film must be polished and the polishing must be completed when the SiO ₂ surface comes out. Such a process is shown in FIG. 1, and CMP polishing in such a process requires that the polishing rate be selective with respect to different materials such as copper, a tantalum compound, and SiO ₂ .

That is, in Step 1, the polishing rate with respect to copper is high and the tantalum compound needs to be selective enough to have no polishing ability. Further, in step 2, the polishing rate for the tantalum compound is large, but the smaller the polishing rate for SiO ₂ is, the more preferable it is because it is possible to prevent excessive polishing of SiO ₂ .

Ideally, this process can be polished with a single abrasive, but the selectivity of the polishing rate for different materials cannot be changed during the process, so the process is divided into two steps and has different selectivity. Each CMP step is performed with two slurries. In order to prevent excessive etching (dishing, recessing, erosion) of the copper film in the normal groove or hole, the polishing is finished in step 1 with a little copper film on the tantalum compound left. In step 2, the remaining copper and tantalum compound are removed by polishing using the SiO ₂ layer as a stopper.

  For the polishing composition used in Step 1, it is necessary to have a large polishing rate only for the copper film without causing surface defects (scratches) that cannot be corrected in Step 2.

As such a polishing composition for a copper film, Patent Document 1 discloses a polishing composition containing at least one organic acid selected from aminoacetic acid and amidosulfuric acid, an oxidizing agent, and water. . This polishing composition has a relatively high polishing rate with respect to copper, and this is because copper ionized by an oxidizing agent forms a chelate with the above organic acid and is easily mechanically polished. It can be estimated that this is because
However, when polishing a semiconductor device having a copper film and a tantalum compound using the polishing composition, the polishing selectivity of copper and tantalum compound is not sufficient, or if the selectivity to copper is increased, the wiring trench and hole copper There have been problems such as excessive film shaving and loss of smoothness on the copper film surface.
JP-A-7-233485

  An object of the present invention is to provide a polishing composition having a high selectivity in which the polishing rate of copper is high but the polishing rate of tantalum compound is low in the CMP process of a semiconductor device having a copper film and a tantalum compound. It is a polishing composition for CMP processing excellent in smoothness of the copper film surface.

The present invention
(1) Polishing composition containing (A) abrasive, (B) amino acid, (C) benzotriazole, (D) quinaldic acid, (E) amine, (F) hydrogen peroxide and (G) water. And (A) the abrasive is an organic polymer compound having an average particle size in the range of 5 to 500 nm, the concentration of the abrasive in the polishing composition is 0.1 to 20% by weight, and (B) The main component of the amino acid is glycine, the concentration in the polishing composition is 0.01 to 5% by weight, and the concentration of (C) benzotriazole in the polishing composition is 0.0001 to 0.5% by weight. (D) the concentration of quinaldic acid in the polishing composition is 0.0001 to 0.5% by weight, and (E) the amine is selected from the group consisting of monoethanolamine, diethanolamine, triethanolamine, and ethylenediamine At least one A concentration of 0.001 to 0.5% by weight in the polishing composition, and (F) a concentration of hydrogen peroxide in the polishing composition is 0.01 to 5% by weight. A polishing composition characterized by
(2) The polishing composition according to item (1), wherein the polishing composition has a pH of 5.5 to 7.5,
It is.

  ADVANTAGE OF THE INVENTION According to this invention, the polishing composition which can grind | polish a copper film preferentially in the CMP processing process of the semiconductor device containing a copper film and a tantalum film is obtained, and a semiconductor device can be manufactured efficiently.

  As a result of various investigations to solve the above-mentioned problems, the present invention uses a polishing composition containing a specific abrasive, compound, oxidant and water, so that the polishing rate for a copper film is large and tantalum is used. The inventors have found that the polishing rate with respect to the compound is small, that high selectivity can be obtained, and that the smoothness of the copper film surface is excellent, and that the present invention has been completed.

  The abrasive used in the present invention is an organic polymer compound and is not particularly limited as long as it is an organic polymer. For example, fine particles of organic polymer compound obtained by emulsion polymerization of a vinyl monomer, polyester, polyamide, Examples thereof include organic polymer fine particles obtained by polycondensation such as polyimide and polybenzoxazole, and organic polymer fine particles obtained by addition condensation such as phenol resin and melamine resin, which can be used alone or in any combination. . A vinyl polymer having a relatively low price and a uniform particle size is preferred. The organic polymer compound is used in the form of fine particles, and the average particle diameter is composed of an organic polymer compound in the range of 5 to 500 nm.

  The average primary particle diameter of the abrasive can be observed with a scanning electron microscope, but is preferably in the range of an average particle diameter of 5 nm to 500 nm. If the thickness is less than 5 nm, the polishing rate is difficult to increase, which is not preferable. If the thickness exceeds 500 nm, scratches are easily generated on the surface of the object to be polished, and particles are liable to settle, which is not preferable. It is also possible to use inorganic fine particles such as colloidal silica as an abrasive so long as the properties are not impaired.

  The concentration of the abrasive in the polishing composition is preferably 0.1 to 20% by weight. If the concentration of the abrasive is less than 0.1% by weight, the mechanical polishing ability is reduced and the polishing rate is lowered, which is not preferable, and if it exceeds 20% by weight, it becomes difficult to disperse the particles, such as aggregation and sedimentation. It is not preferable because defects are likely to occur.

  The polishing composition of the present invention contains an amino acid. The amino acid in the present invention is most preferably glycine, and the amount added is in the range of 0.01 to 5% by weight in the polishing composition. If the amount is less than 0.01% by weight, the polishing rate is insufficient. If the amount exceeds 5% by weight, the polishing rate cannot be controlled, and excessive polishing or surface corrosion of the copper film is likely to occur.

The polishing composition of the present invention contains benzotriazole. The concentration in the polishing composition is preferably 0.0001 to 0.5% by weight. If it is less than 0.0001% by weight, the polishing rate of the copper film cannot be controlled sufficiently, which is not preferable, and if it exceeds 0.5% by weight, the polishing rate of the copper film extremely decreases, which is not preferable.

  The polishing composition of the present invention contains quinaldic acid. The concentration in the polishing composition is preferably 0.0001 to 0.5% by weight. If it is less than 0.0001% by weight, the polishing rate of the copper film becomes excessively large and cannot be controlled, and it is not preferable, and if it exceeds 0.5% by weight, the polishing rate of the copper film extremely decreases.

  The polishing composition of the present invention contains at least one compound selected from the group consisting of monoethanolamine, diethanolamine, triethanolamine, and ethylenediamine. These amines are mainly used for adjusting the pH of the polishing composition and controlling the polishing rate of the copper film. The concentration in the polishing composition is preferably 0.001 to 0.5% by weight. If it is less than 0.001% by weight, it is insufficient for controlling the polishing rate, and if it is 0.5% by weight or more, the polishing rate is excessively suppressed.

  The polishing composition of the present invention contains hydrogen peroxide. In the polishing composition of the present invention, hydrogen peroxide acts as an oxidizing agent. Hydrogen peroxide exerts an oxidizing action on the copper film and works to increase the polishing rate of the copper film by promoting ionization, but the concentration in the polishing composition is 0.01 to 5% by weight. It is desirable. If the concentration in this range is too high or too low, the polishing rate of the copper film decreases, which is not preferable.

  The medium of the polishing composition of the present invention is water, and it is desirable to reduce ionic impurities and metal ions as much as possible.

  The polishing composition of the present invention preferably has a pH of 5.5 to 7.5. If the pH is less than 5.5 or more than 7.5, the etching rate of the copper film is difficult to control, and overpolishing or corrosion of the copper film surface tends to occur, which is not preferable.

  The polishing composition of the present invention is produced by mixing, dissolving, and dispersing the above-described components, the abrasive, amino acid, benzotriazole, quinaldic acid, and amine in water. Hydrogen peroxide is added to and mixed with the above-mentioned liquid mixture immediately before polishing, but can also be mixed in advance. The mixing method can be performed with any apparatus. For example, a blade-type rotary stirrer, an ultrasonic disperser, a bead mill disperser, a kneader, a ball mill, and the like are applicable.

In addition to the above components, various polishing aids may be blended. Examples of such polishing aids include dispersants, rust inhibitors, antifoaming agents, fungicides and the like, and these are added for the purpose of improving the dispersion storage stability of the slurry and the polishing rate. Needless to say, the dispersibility can be improved by adding a water-soluble polymer such as polyvinyl alcohol. Examples of the antifoaming agent include liquid paraffin, dimethyl silicone oil, a mixture of stearic acid monoglyceride and diglyceride, sorbitan monopalmitate and the like.

The present invention will be specifically described with reference to examples, but the present invention is not limited thereto.
<Example 1>
As an abrasive, a co-condensate of polymethyl methacrylate (PMMA) having an average particle size of 40 nm and divinylbenzene, hydrogen peroxide, glycine, quinaldic acid, and monoethanolamine is 0.5 μm so as to have the concentrations shown in Table 1. Was mixed with ion-exchanged water filtered through a cartridge filter of No. 1 and stirred uniformly with a high-speed homogenizer to uniformly disperse to obtain the polishing composition of Example 1.

<Abrasiveness evaluation>
The object to be polished was prepared by forming a 1500-inch tantalum (Ta) film by sputtering on an 8-inch silicon wafer and 15000-thick copper film by electrolytic plating, and polishing the copper and Ta surfaces.

For polishing, a single-side polishing machine having a surface plate diameter of 600 mm was used. A polishing pad IC-1000 / Suba400 made by Rodel (USA) was attached to the surface plate of the polishing machine with a special double-sided tape, and the copper and tantalum films were polished for 1 minute while flowing the polishing composition (slurry). . The polishing conditions were a load of 300 g / cm ² , a platen rotation speed of 40 rpm, a wafer rotation speed of 40 rpm, and a polishing composition flow rate of 200 ml / min.

The polishing rate (Å / min) was determined by determining the film thickness that decreased after washing and drying the wafer. The ratio of the polishing rate of copper to the polishing rate of tantalum was taken as the selection ratio. Further, the polished surface was examined by observing the polished surface with an optical microscope, and the following ranking was performed.
◎: Good, ○: Partially slightly smooth but usable, △: Good smoothness but partial corrosion, ×: Corrosion occurred

<Examples 2-6, Comparative Examples 1-6>
A high-speed homogenizer was prepared by mixing abrasive C1-C3, hydrogen peroxide, amino acid, benzotriazole, quinaldic acid, and amine with ion-exchanged water filtered through a 0.5 μm cartridge filter so that the concentrations shown in Table 1 were obtained. The mixture was stirred and dispersed uniformly to prepare a polishing composition in the same manner as in Example 1, and the polishing property was evaluated in the same manner as in Example 1.
The evaluation results are shown in Table 1.

  The polishing composition of the present invention is suitably used for surface planarization of a semiconductor device wafer.

Schematic of polishing process for devices with copper film

Explanation of symbols

1 Cu
2 Ta
3 SiO ₂

Claims (2)

A polishing composition comprising (A) an abrasive, (B) amino acid, (C) benzotriazole, (D) quinaldic acid, (E) amine, (F) hydrogen peroxide and (G) water, (A) The abrasive is an organic polymer compound having an average particle size of 5 to 500 nm, the concentration of the abrasive in the polishing composition is 0.1 to 20% by weight, and (B) the main amino acid The component is glycine, the concentration in the polishing composition is 0.01 to 5% by weight, the concentration of (C) benzotriazole in the polishing composition is 0.0001 to 0.5% by weight, (D) The concentration of quinaldic acid in the polishing composition is 0.0001 to 0.5% by weight, and (E) at least the amine is selected from the group consisting of monoethanolamine, diethanolamine, triethanolamine, and ethylenediamine One or more compounds The concentration in the polishing composition is 0.001 to 0.5% by weight, and the concentration of (F) hydrogen peroxide in the polishing composition is 0.01 to 5% by weight. A polishing composition. The polishing composition according to claim 1, wherein the polishing composition has a pH of 5.5 to 7.5.

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