JP2003249468A - Polishing composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing composition for CMP processing which has high selectively of large copper polishing rate but small tantalum compound polishing rate, and is excellent in flatness of a copper film surface in CMP process of a semiconductor device with a copper film and tantalum compound. <P>SOLUTION: The polishing composition consists of (A) a polishing material, (B) pyrazinecarboxylic acid and/or 2,3-pyrazinecarboxylic acid, (C) hydrogen peroxide and (D) water. The polishing material comprises an organic polymer compound whose average grain diameter is in the range of 5 to 100 nm and the concentration in polishing composition of the polishing material is 1 to 30 wt.%. The concentration in polishing composition of element (B) is 0.01 to 10 wt.%. The concentration in polishing composition of hydrogen peroxide is 0.03 to 10 wt.%. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing composition used for polishing semiconductors, substrates for various types of memory hard disks, etc., and more particularly, to planarizing the surface of semiconductor device wafers. The present invention relates to a polishing composition suitably used for processing. [0002] The recent remarkable development of the electronics industry has evolved into transistors, ICs, LSIs, and ultra-LSIs. As the degree of integration of circuits in these semiconductor devices has increased rapidly, The design rules of devices have been miniaturized 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 an increase in wiring resistance due to miniaturization of wiring, copper wiring having a lower electric resistance is being studied from aluminum and tungsten as a wiring material. However, when copper is used for wiring layers and interconnections between wirings, after forming wiring grooves and holes on the insulating film, a copper film is formed by sputtering or plating, and the film is formed by chemical mechanical polishing (CMP). Unnecessary copper on the insulating film is removed. In such a process, copper diffuses into the insulating film to deteriorate device characteristics. Therefore, it is usual to provide a tantalum or tantalum nitride layer as a barrier layer on the insulating film in order to prevent the diffusion of copper. It is becoming. [0005] In the planarization CMP process of a device in which a copper film is formed on the uppermost layer as described above, an unnecessary portion of the copper film is first polished to a tantalum compound surface layer formed on the insulating layer. In the next step, the tantalum compound layer on the insulating film must be polished and the polishing must be completed when the SiO ₂ surface comes out. FIG. 1 shows such a process. In the CMP polishing in such a process, it is necessary that the polishing rate be selectable with respect to different materials such as copper, a tantalum compound, and SiO ₂ . That is, in step 1, the polishing rate for copper is high, and the selectivity is such that there is almost no polishing ability for tantalum compounds. Although further polishing rate is greater for Step 2 in tantalum compound SiO ₂
The smaller the polishing rate is, the more preferable it is because it can prevent excessive removal of SiO ₂ . [0007] Ideally, it is desired that this process can be polished with a single abrasive. However, since the selectivity of the polishing rate for different materials cannot be changed during the process, the process is divided into two steps. Each CMP step is performed with two selective slurries. In order to prevent the copper film in the grooves and holes from being excessively ground (dishing, recess, erosion), the polishing is terminated in step 1 with the copper film on the tantalum compound being left slightly. Then, in step 2, a small amount of copper and tantalum compound remaining using the SiO ₂ layer as a stopper is polished and removed. The polishing composition used in step 1 needs to have a high polishing rate only for the copper film without generating surface defects (scratch) that cannot be recovered in step 2. It is. [0009] Such a polishing composition for a copper film is disclosed in JP-A-7-233485.
At least one selected from aminoacetic acid and amidosulfuric acid
This is a polishing composition containing various organic acids, an oxidizing agent, and water. A relatively large polishing rate is obtained for copper, which is presumed to be because copper ionized by the oxidizing agent forms a chelate with the above-mentioned organic acid and is easily polished mechanically. [0010] However, using the polishing composition,
When a semiconductor device having a copper film and a tantalum compound is polished, the polishing selectivity of copper and the tantalum compound is not sufficient. There was a problem that the smoothness was deteriorated. SUMMARY OF THE INVENTION The present invention has a high selectivity that a polishing rate of copper is high but a polishing rate of tantalum compound is low in a CMP processing process of a semiconductor device having a copper film and a tantalum compound. An object of the present invention is to provide a polishing composition and a polishing composition for a CMP process which is excellent in the smoothness of a copper film surface. The present invention provides (A) an abrasive, (B) pyrazinecarboxylic acid and / or 2,3-pyrazinedicarboxylic acid, (C) hydrogen peroxide, and (D) A polishing composition having water, wherein (A) the polishing material is made of an organic polymer compound having an average particle size in the range of 5 to 100 nm, and the concentration in the polishing composition is 1 to 30% by weight;
(B) the concentration of pyrazinecarboxylic acid and / or 2,3-pyrazinedicarboxylic acid in the polishing composition is 0.01 to 10;
%, And the concentration of (C) hydrogen peroxide in the polishing composition is 0.03 to 10% by weight. DETAILED DESCRIPTION OF THE INVENTION The present invention has been studied in order to solve the above problems, and as a result, by using a polishing composition containing a specific compound, an oxidizing agent and water,
The polishing rate for the copper film is large, the polishing rate for the tantalum compound is small, high selectivity can be obtained, and it has been found that excellent results can be obtained also on the smoothness of the copper film surface, and the invention has been completed. Things. 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 an organic polymer compound obtained by emulsion polymerization of a vinyl monomer or the like and polyester Fine particles of organic molecules obtained by polycondensation such as polyamide, polyimide, and polybenzoxazole, and fine particles of organic polymers obtained by addition condensation of phenol resin, melamine resin, etc., and can be used alone or in any combination. Can be. Preferably, it is a relatively inexpensive vinyl polymer having a uniform particle size and a low polarity. The organic polymer compound is used in the form of fine particles, and has an average particle size in the range of 5 to 100 nm. The average primary particle diameter of the abrasive can be observed with a scanning electron microscope. If the average particle diameter is smaller than the above lower limit, the polishing rate may increase. There is a possibility that scratches are likely to be generated on the surface of the polished material, and it is difficult to suppress the polishing rate of the tantalum compound. It is of course possible to use inorganic fine particles such as colloidal silica together as an abrasive without impairing the properties. The concentration of the abrasive in the polishing composition is from 1 to 30.
% By weight. If the concentration of the abrasive is too low, the mechanical polishing ability decreases and the polishing rate decreases, which is not preferable.If the concentration is too high, the mechanical polishing ability increases and the polishing rate of the tantalum compound cannot be suppressed. This is not preferred because the selectivity decreases. The polishing composition of the present invention contains pyrazine carboxylic acid and / or 2,3-pyrazine dicarboxylic acid. The concentration in the polishing composition is desirably 0.01 to 10% by weight. If the value is less than the lower limit, the polishing rate of the copper film becomes excessively large and control becomes impossible, so that it is not preferable. 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 effect on the copper film and has a function of increasing the polishing rate of the copper film by promoting ionization, but the concentration in the polishing composition is 0.03 to 5% by weight. It is desirable. If the concentration is too high or too low, the polishing rate of the copper film is undesirably reduced. The medium of the polishing composition of the present invention is water,
It is desirable that ionic impurities and metal ions are reduced as much as possible. The amount of water in the polishing composition is 50 to 9
8.6% by weight. If the amount is less than the lower limit, the slurry viscosity is increased and the workability is reduced, and heat is generated at the time of polishing. The polishing composition of the present invention is prepared by mixing, dissolving and dispersing the above-mentioned components such as the abrasive, pyrazinecarboxylic acid and / or 2,3-pyrazinedicarboxylic acid in water. Hydrogen peroxide is added to and mixed with the above mixed solution immediately before polishing, but it is also possible to mix them in advance. These mixing methods can be performed with any device. For example,
A blade-type rotary stirrer, an ultrasonic disperser, a bead mill disperser, a kneader, a ball mill, and the like are applicable. Various polishing aids may be added in addition to the above components. Examples of such polishing aids include dispersing aids, rust preventives, defoamers, pH adjusters, fungicides, and the like, which are used to improve the dispersion storage stability of the slurry and the polishing rate. Added for purpose. Examples of the dispersing aid include sodium hexametaphosphate. Of course, it is needless to say that the dispersibility can be improved by adding various surfactants and the like. Preservatives include benzotriazole and its derivatives. Examples of the pH adjuster include basic compounds such as ammonia and acidic compounds such as acetic acid, hydrochloric acid, and nitric acid. Liquid paraffin as an antifoaming agent,
Examples thereof include dimethyl silicone oil, monostearic acid, a mixture of diglycerides, and sorbitan monopalmitate. EXAMPLES The present invention will be specifically described with reference to Examples. <Examples 1 to 8, Comparative Examples 1 to 6> Abrasive, hydrogen peroxide,
The pyrazine carboxylic acid and / or 2,3-pyrazine dicarboxylic acid was mixed with ion-exchanged water filtered through a 0.5 μm cartridge filter so as to have the concentration shown in Table 1, and stirred uniformly with a high-speed homogenizer. By dispersing, polishing compositions of Examples 1 to 8 and Comparative Examples 1 to 6 were obtained. <Evaluation of Abrasiveness> An object to be polished was prepared by forming a 2000-inch tantalum (Ta) film by sputtering on a 6-inch silicon wafer and a 10000-cm copper film by electrolytic plating, and the copper and Ta surfaces were polished. . For polishing, a single-side polishing machine having a platen diameter of 600 mm was used. A polyurethane polishing pad IC-1000 / Suba400 made by Rodale (USA) is attached to the surface plate of the polishing machine with a special double-sided tape, and the copper and tantalum films are polished for 1 minute while flowing a polishing composition (slurry). did.
The polishing conditions were a load of 300 g / cm ² , a rotation speed of the platen of 40 rpm, a wafer rotation speed of 40 rpm, and a flow rate of the abrasive composition of 200 ml / min. The polishing rate (Å / min) was determined by determining the reduced film thickness after cleaning and drying the wafer. The ratio of the polishing rate of copper to the polishing rate of tantalum was used as the selectivity. The polished surface was observed with an optical microscope to check the polished state, and the following ranking was made. ：: good, ：: only a part of the surface was slightly insufficiently smooth but good in general, ×: insufficiently smooth, XX: significantly corroded and NG. The evaluation results are shown in Table 1. [Table 1] According to the present invention, in a CMP process of a semiconductor device including a copper film and a tantalum film, a polishing composition capable of preferentially polishing a copper film can be obtained, and the semiconductor device can be efficiently used. It can be manufactured in a special way.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of a polishing process of a device having a copper film formed thereon. Cu 2. Ta3. SiO ₂

Claims (1)

Claims 1. An abrasive for polishing comprising (A) an abrasive, (B) pyrazinecarboxylic acid and / or 2,3-pyrazinedicarboxylic acid, (C) hydrogen peroxide, and (D) water. A composition,
(A) The abrasive is composed of an organic polymer compound having an average particle diameter in the range of 5 to 100 nm, and has a concentration of 1 in the polishing composition.
(B) pyrazine carboxylic acid and / or
Alternatively, the concentration of 2,3-pyrazinedicarboxylic acid in the polishing composition is 0.01 to 10% by weight, and the concentration of (C) hydrogen peroxide in the polishing composition is 0.03 to 10% by weight. A polishing composition, comprising: