JP2003100673A - Abrasive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an abrasive composition for CMP showing such high selectivity that the composition has a high polishing rate against copper, but a low polishing rate against a tantalum compound and, in addition, can highly smoothly polish the surface of a copper film in the CMP process of a semiconductor device having the copper film and tantalum compound. SOLUTION: This abrasive composition is composed of (A) an abrasive, (B) 1-hydroxybenzotriazole, (C) malic acid, (C) hydrogen peroxide, and (E) water. The abrasive (A) is composed of an organic high-molecular compound having a mean particle diameter of 5-100 nm and contained in this abrasive composition at a concentration of 5-30 wt.%. The concentration of the 1- hydroxybenzotriazole and malic acid in this composition are respectively adjusted to 0.1-5 wt.% and 0.05-5 wt.%. In addition, the concentration of the hydrogen peroxide in this composition is adjusted to 0.03-3 wt.%.

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. 2. Description of the Related Art With recent remarkable developments in the electronics industry, transistors, ICs, LSIs, and super LSIs have been evolving. As the degree of integration of circuits in these semiconductor devices has rapidly increased, semiconductors have been developed. 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 unnecessary parts are chemically and mechanically polished. Unnecessary copper on the insulating film is removed by the (CMP). 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. Although such a process is shown in FIG. 1, 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 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, but since the selection ratio of the polishing rate for different materials cannot be changed in the course of the process, the process is divided into two steps and different selections are made. Each CMP step is performed with two slurries having properties. 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 due to the fact that 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. Means for Solving the Problems (A) Abrasive, (B) 1
-Hydroxybenzotriazole, (C) malic acid,
A polishing composition comprising (D) hydrogen peroxide and (E) water, wherein the abrasive is a composition comprising an organic polymer compound having an average particle size in the range of 5 to 100 nm; The concentration of the 1-hydroxybenzotriazole in the polishing composition is 0.1 to 5% by weight, and the concentration of the 1-hydroxybenzotriazole in the polishing composition is 5 to 30% by weight. The polishing composition has a concentration in the polishing composition of 0.05 to 5% by weight and a concentration of the hydrogen peroxide in the polishing composition of 0.03 to 3% by weight. DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention has been studied in various ways to solve the above-mentioned problems, and as a result, it has been found that a polishing composition containing a specific abrasive, a compound, an oxidizing agent and water is used. It has been found that the polishing rate for the copper film is large, the polishing rate for the tantalum compound is small, high selectivity can be obtained, and excellent results can also be obtained on the smoothness of the copper film surface. It is a thing. 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 an organic polymer obtained by polycondensation such as polyamide, polyimide, and polybenzoxazole, and fine particles of an organic polymer obtained by addition condensation of a phenol resin, a melamine resin, etc., and used alone or in any combination. be able to. 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. These abrasives have a relatively small particle diameter so as to prevent the generation of scratches due to the abrasive on the surface of the object to be polished, and to prevent precipitation and change in composition during storage. Is preferred. The average primary particle diameter of the abrasive can be observed with a scanning electron microscope.
More preferably, it is in the range of 100 nm to 100 nm. 5 nm
If it is smaller, the polishing rate is difficult to increase, which is not preferable. If it exceeds 100 nm, it is not preferable because scratches easily occur on the surface of the object to be polished and it becomes 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 5 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 1-hydroxybenzotriazole. The concentration in the polishing composition is desirably 0.1 to 5% by weight. When the amount of 1-hydroxybenzotriazole is small, the polishing rate of the copper film is decreased, which is not preferable. When the amount is excessively large, the polishing rate of the copper film is increased, so that the control of the polished surface becomes difficult or overpolishing tends to occur. Not preferred. In particular, excessive use is not preferred because the smoothness of the surface of the object to be polished is impaired. The polishing composition of the present invention contains malic acid. Malic acid in the present invention is preferred because it forms a chelate with copper and the polishing rate of copper is easily controlled. The amount added is in the range of 0.05 to 5% by weight in the polishing composition. If it is less than 0.05% by weight, the effect of forming a chelate is insufficient. 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. The concentration in the polishing composition is desirably 0.03 to 3% by weight. If the concentration is too high or too low, the polishing rate of the copper film is undesirably reduced. [0021] 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 80 to 9
4% by weight. If the amount is less than 80% by weight, the slurry viscosity becomes high and the workability decreases, and heat is generated during polishing, which is not preferable. If the amount exceeds 94% by weight, the polishing rate decreases, and the polishing selectivity decreases. Absent. The polishing composition of the present invention is prepared by mixing, dissolving and dispersing the above components, an abrasive, 1-hydroxybenzotriazole, malic acid and the like in water. It is preferable that hydrogen peroxide is added to and mixed with the above mixed solution immediately before polishing. 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 can be applied. Various polishing aids other than the above components may be blended. 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. As the pH adjuster, acetic acid, hydrochloric acid, nitric acid and the like can be mentioned. Examples of the antifoaming agent include liquid paraffin, 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 and Comparative Examples 1 to 4> Hydrogen peroxide, 1-hydroxybenzotriazole (1-HBT), and malic acid were shown in Table 1 using the organic polymer compound of Table 1 as an abrasive. The mixture was mixed with ion-exchanged water filtered through a 0.5 μm cartridge filter so as to have a concentration, stirred with a high-speed homogenizer and uniformly dispersed to obtain the polishing compositions of Examples 1 to 8 and Comparative Examples 1 to 4. Obtained. Hydrogen peroxide was mixed and used immediately before polishing. <Evaluation of Abrasiveness> The 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 polishing pad IC-1000 / Suba400 made by Rodale Inc. (USA) is attached to the surface plate of the polishing machine with a special double-sided tape, and a polishing composition (slurry) is attached.
The copper and tantalum films were polished for 1 minute while flowing. 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 flow rate of the polishing composition of 200 ml / min. After the wafer was washed and dried, the reduced film thickness was determined to determine the polishing rate (Å / min). The ratio of the polishing rate of copper to the polishing rate of tantalum was used as the selectivity. In addition, the polished surface was observed with an optical microscope to check the polished state, and the following ranking was made. ：: good, ：: slightly poorly smooth, but generally good, x: poorly smooth, XX: markedly 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 efficiency of the semiconductor device can be improved. 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 on which a copper film is formed. [Explanation of reference numerals] Cu 2. Ta3. SiO ₂

Claims (1)

Claims: 1. A polishing composition comprising (A) an abrasive, (B) 1-hydroxybenzotriazole, (C) malic acid, (D) hydrogen peroxide, and (E) water. Wherein the abrasive is a composition comprising an organic polymer compound having an average particle diameter in the range of 5 to 100 nm, and the concentration of the abrasive in the polishing composition is 5 to 30% by weight; The concentration of 1-hydroxybenzotriazole in the polishing composition is from 0.1 to
5% by weight, the concentration of malic acid in the polishing composition is 0.05 to 5% by weight, and the concentration of hydrogen peroxide in the polishing composition is 0.03 to 3% by weight. A polishing composition comprising: