JP2003151926A - Polishing composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing composition having high selectivity in which the polishing rate for copper is large but the polishing rate for a tantalum compound is small, in a CMP work process for a semiconductor device having a copper film and a tantalum compound. SOLUTION: The polishing composition is composed of (A) benzotriazole, (B) tartaric acid, (C) hydrogen peroxide, (D) polyvinyl alcohol, (E) quinolinol, and (F) water, where the concentration of (A) benzotriazole in the composite for polishing is 0.01-3 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 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. Further, in step 2, the polishing rate for the tantalum compound is large,
_A smaller polishing rate for ₂ is preferable 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) benzotriazole, (B) tartaric acid, (C) hydrogen peroxide,
A polishing composition comprising (D) polyvinyl alcohol, (E) quinolinol and (F) water, wherein the concentration of (A) benzotriazole in the polishing composition is 0.01 to 3% by weight; A) a concentration of tartaric acid in the polishing composition of 0.05 to 5% by weight; (C) a concentration of hydrogen peroxide in the polishing composition of 0.03 to 5% by weight; The concentration of alcohol in the polishing composition is 0.01
-5% by weight, and the concentration of (E) quinolinol in the polishing composition is 0.01 to 1% by weight. DETAILED DESCRIPTION OF THE INVENTION As a result of various studies to solve the above-mentioned problems, the present invention provides 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 results excellent in the smoothness of the copper film surface can be obtained, and the invention has been completed. Things. The polishing composition of the present invention contains benzotriazole. The concentration in the polishing composition is 0.01 to 3% by weight. 0.01% by weight of benzotriazole
If the amount is less than the above, the polishing rate of the copper film becomes large, and the control of the polished surface becomes difficult, or overpolishing tends to occur. [0015] The polishing composition of the present invention contains tartaric acid. Tartaric acid in the present invention forms a chelate with copper,
This is preferable because the polishing rate of copper can be 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, 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 polishing composition of the present invention contains polyvinyl alcohol. In the polishing composition of the present invention, polyvinyl alcohol has an effect of uniformly dispersing the abrasive in water, makes it difficult for the abrasive to settle even after long-term storage, and easily causes secondary aggregation to generate scratches. Can be prevented. The amount of polyvinyl alcohol added is in the range of 0.01 to 5% by weight in concentration in the polishing composition.
If the amount exceeds 5% by weight, the viscosity of the slurry increases, and the polishing workability decreases, which is not preferable. The polishing composition of the present invention contains quinolinol. In the polishing composition of the present invention, quinolinol has an effect of improving the polishing rate of copper, and is most suitable for increasing the selectivity with metals other than copper. The amount of quinolinol added is in the range of 0.01 to 1% by weight in the polishing composition, and the concentration in the composition is 0.01% by weight.
Less than 1% by weight is not preferable because the effect is not exhibited.
Exceeding the ratio is undesirable because the polishing selectivity with other metals decreases. 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 produced by mixing, dissolving and dispersing benzotriazole, tartaric acid, polyvinyl alcohol, quinolinol and hydrogen peroxide in water. It is preferable that hydrogen peroxide is added to and mixed with a liquid mixture obtained by mixing the above components immediately before polishing. The mixing method 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 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. 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, Comparative Examples 1 to 7> Hydrogen peroxide, benzotriazole (BT), tartaric acid, polyvinyl alcohol,
The concentration of quinolinol and the like is adjusted to a value shown in Table 1 so that the concentration of quinolinol and the like is adjusted to 0.
The mixture was mixed with ion-exchanged water filtered through a 5 μm cartridge filter, stirred with a high-speed homogenizer and uniformly dispersed to obtain polishing compositions of Examples 1 to 8 and Comparative Examples 1 to 7. 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 (USA) is attached to the surface plate of the polishing machine with a special double-sided tape, and a polishing liquid 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 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. In addition, 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 generally good, ×: insufficient smoothness, and 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 diagram of a polishing process of a device having a copper film formed thereon. Cu 2. Ta3. SiO ₂

Claims (1)

Claims: (A) benzotriazole, (B) tartaric acid, (C) hydrogen peroxide, (D) polyvinyl alcohol,
A polishing composition comprising (E) quinolinol and (F) water, wherein the concentration of (A) benzotriazole in the polishing composition is 0.01 to 3% by weight, and (B) a polishing composition of tartaric acid. (C) the concentration in the substance is 0.05 to 5% by weight;
(E) quinolinol, wherein the concentration of hydrogen peroxide in the polishing composition is 0.03 to 5% by weight, the concentration of (D) polyvinyl alcohol in the polishing composition is 0.01 to 5% by weight, The concentration in the polishing composition of 0.01 to 1% by weight.