JP2002313759A - Polishing composition and polishing method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing composition which can obtain a superior surface by polishing, at a high speed, a semiconductor device which has a layer made of a tantalum contained compound and a layer made of copper, on a substrate. SOLUTION: A polishing composition contains (a) abrasives, (b) a free radical scavenger, (c) a polishing actuator, (d) anticorrosives, (e) a hydrogen peroxide, and (f) water, and a polishing method using the same is also provided. The (b) free radical scavenger prevents generation of surface defects such as recesses by scavenging a free radical such as hydroxy radical generated during polishing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing composition used for polishing substrates for semiconductors, photomasks and various types of memory hard disks, and more particularly to a polishing composition suitable for flattening the surface of a device wafer in the semiconductor industry and the like. The present invention relates to a composition for polishing and a polishing method using the composition.

More specifically, the present invention provides a highly efficient polishing of a semiconductor device to which a so-called chemical mechanical polishing (CMP) technique is applied at the time of processing a device wafer. The present invention relates to a polishing composition having a high selectivity and capable of forming an excellent polishing surface, and a polishing method using the composition.

[0003]

2. Description of the Related Art Recent computers,
The progress of so-called high-tech products has been remarkable, and the components used for it, such as ULSI, are becoming ever more highly integrated and faster. Along with this, the design rules of semiconductor devices have been miniaturized year by year, the depth of focus in the device manufacturing process has become shallower, and the flatness required for the pattern formation surface has become stricter.

Further, in order to cope with an increase in wiring resistance due to miniaturization of wiring on a device, the use of copper instead of tungsten and aluminum conventionally used as wiring materials has been studied. Due to its properties, copper is difficult to process by anisotropic etching. For this reason,
After forming wiring grooves and holes on the insulating film, a copper film for wiring is formed by a sputtering method or a plating method (a so-called damascene method), and then unnecessary copper film deposited on the insulating film is mechanically removed. CMP combining polishing and chemical polishing
A specific process, such as removal by processing, is required.

[0005] However, in the above-described process, copper atoms may diffuse into the insulating film to deteriorate device characteristics. Therefore, for the purpose of preventing the diffusion of copper atoms, it has been studied to provide a barrier layer on an insulating film in which wiring grooves and holes are formed. As a material for such a barrier layer, a tantalum-containing compound such as metal tantalum or tantalum nitride is the most excellent from the viewpoint of device reliability, and is most likely to be adopted in the future.

Accordingly, the CMP process of a semiconductor device containing such a copper and a tantalum-containing compound is performed by first polishing a copper film on the outermost layer and then a tantalum-containing compound film as a barrier layer, and further polishing silicon dioxide or acid. Generally, polishing is terminated when the insulating film such as silicon fluoride is reached. As an ideal process, one kind of polishing composition is used, and in one polishing step, the copper film and the tantalum-containing compound film are uniformly removed,
Further, the polishing is surely terminated at the time of reaching the insulating film. In the present invention, the “tantalum-containing compound” includes metal tantalum in addition to tantalum nitride and the like, and “copper” includes an alloy in which aluminum is mixed with copper.

However, copper and tantalum-containing compounds differ in hardness, chemical stability, and other properties, making it difficult to perform ideal processing by the above-described processing process. To solve this, a two-stage
That is, a polishing method in which the polishing step is divided into two steps is being studied.

In such a two-stage polishing method, first,
In the first polishing step, the copper film is polished using a polishing composition that can polish the copper film with high efficiency, using the tantalum-containing compound film as a stopper until the tantalum-containing compound film appears. At this time, for the purpose of not causing various surface defects such as recess, erosion, and dishing on the copper film surface, immediately before the tantalum-containing compound film appears,
That is, the first polishing step may be terminated when a small amount of the copper film is left. Next, in the second polishing step,
A copper composition is mainly polished by using a polishing composition capable of polishing a tantalum-containing compound film with high efficiency and using an insulating film as a stopper until the copper film reaches the insulating film.

Here, the recess, erosion and dishing are surface defects caused by excessively polishing the wiring portion. The main causes of each surface defect are the etching action on the wiring layer for recess, the difference in pressure applied per unit area for erosion, and the wiring layer (copper film here) for dishing.
And a hardness difference between an insulating layer and a barrier layer (for example, a tantalum-containing compound film). Since such surface defects reduce the cross-sectional area of the wiring layer, when a device is manufactured, the resistance of the wiring at the portion where the surface defects occur as described above increases, and in extreme cases, poor contact occurs. Or Therefore, in the first polishing step, it is important not to generate the above-mentioned surface defects that cannot be removed in the wiring layer in the second polishing step. However, the polishing rate for the copper layer should not be impaired at this time.

In order to meet such a demand, there has been a demand for a polishing composition which has a high polishing rate for a copper layer and does not cause large surface defects on the surface of the copper layer after polishing.

As a polishing composition for polishing a layer made of copper, a polishing liquid containing an organic acid selected from aminoacetic acid (glycine) and amidosulfuric acid, an oxidizing agent and water is used. A method of manufacturing a semiconductor device has been disclosed (JP-A-7-233485). Also disclosed is a polishing liquid containing aminoacetic acid and / or amidosulfuric acid, an oxidizing agent, water, and benzotriazole or a derivative thereof, and a method for manufacturing a semiconductor device using the polishing liquid (Japanese Patent Application Laid-Open No. Hei 8- No. 83780).

The present inventors have also proposed an abrasive, an aliphatic carboxylic acid, a basic compound, a polishing accelerator such as glycine,
A polishing composition comprising an anticorrosive such as benzotriazole and hydrogen peroxide is disclosed (Japanese Patent Application No. 2001-23316).
issue).

In view of these inventions, the present inventors have completed the present invention which exhibits more excellent effects, specifically, an excellent polishing rate and a recess suppressing effect.

<Summary of the Invention> The polishing composition according to the present invention comprises (a) at least one abrasive selected from the group consisting of silicon dioxide, aluminum oxide, cerium oxide, zirconium oxide, and titanium oxide; b) free radical scavenger (c) at least one copper polishing accelerator selected from the group consisting of glycine, α-alanine and histidine; (d) benzotriazole, benzimidazole, triazole, imidazole and tolyltriazole Characterized in that it comprises at least one anticorrosive selected from the group consisting of (e) hydrogen peroxide and (f) water.

Further, the polishing method according to the present invention is directed to a polishing method for polishing a semiconductor device having a layer made of a tantalum-containing compound and a layer made of copper on a substrate in order from the substrate to the surface. The method is characterized in that a layer made of copper is selectively polished using the composition.

According to the present invention, there is provided a polishing composition capable of suppressing surface defects such as recesses while maintaining a high polishing rate for a copper layer. further,
According to the present invention, in the course of polishing a semiconductor device having a layer made of a tantalum-containing compound and a layer made of copper on a substrate in order from the substrate to the surface, in a short manufacturing cycle, generation of a recess is caused. There is provided a polishing method capable of forming an excellent polishing surface.

<Polishing Composition> (a) Abrasive Abrasives suitable for use as the main abrasive among the components of the polishing composition according to the present invention include silicon dioxide, aluminum oxide, cerium oxide, and oxide. It is at least one selected from the group consisting of zirconium and titanium oxide.

There are various types of silicon dioxide, such as colloidal silica, fumed silica, and others having different production methods and properties.

Aluminum oxide includes α-alumina, δ-alumina, θ-alumina, κ-alumina, and other morphologically different ones. There is also one called fumed alumina from the manufacturing method.

Cerium oxide is classified into trivalent and tetravalent cerium oxides in terms of oxidation number, and hexagonal, equiaxed, and face-centered cubic when viewed from the crystal system.

Zirconium oxide includes monoclinic, tetragonal, and amorphous zirconium oxides. Also,
Some are called fumed zirconia from their manufacturing method.

Titanium oxide includes titanium monoxide, dititanium trioxide, titanium dioxide, and others in terms of crystal system. There is also one called fumed titania from the manufacturing method.

In the composition of the present invention, these can be used arbitrarily and in combination as necessary.
When they are combined, the manner of combination and the proportion used are not particularly limited. However, from the viewpoints of the effects of the present invention, and economics and availability, silicon dioxide is preferred, and colloidal silica is particularly preferred.

The above-mentioned abrasive is for polishing the surface to be polished by mechanical action as abrasive grains. Therefore, the particle size of the abrasive greatly affects the surface performance after polishing. From the polishing rate and the surface performance after polishing, the particle size of the abrasive is 2
It is preferably from 50 to 50 nm, more preferably from 5 to 40 nm. In the present invention, the particle size of the abrasive is BET
It is an average particle diameter obtained from the surface area measured by the method, and is calculated from the following formula. D = 6 / ρ · S Here, D is the primary particle diameter of the abrasive, ρ is the true density of the abrasive, and S is the specific surface area measured by the BET method.

The content of the abrasive in the polishing composition is preferably at least 0.1 g / liter in order to achieve a sufficient mechanical polishing rate, and the polishing rate for a layer comprising a tantalum-containing compound is suppressed. However, from the viewpoint of preventing agglomeration of the abrasive, the amount is preferably 150 g / liter or less. A more preferred content of the abrasive is 0.2 to 100 g / liter.

(B) Free radical scavenger In the present invention, the free radical scavenger has an action of scavenging free radicals generated in the polishing composition during the polishing step and amplifying the chemical polishing action. It is. That is, when polishing a layer made of copper, copper ions generated in the polishing composition serve as a catalyst to decompose compounds in the composition, such as hydrogen peroxide and urea. As a result of the decomposition reaction, free radicals such as hydroxyl radicals and nitro radicals are generated, and these free radicals may amplify the chemical polishing action on the copper layer. Since such amplification of the chemical polishing action does not occur uniformly on the film surface, a recess may occur in the copper wiring portion. In the present invention, the free radical trapping agent traps free radicals that cause such surface defects and suppresses the amplification of the chemical polishing action.

Such free radical scavengers include phenolic compounds and nitroso group-containing compounds.
The hydrogen atom in the phenolic hydroxyl group of the phenol compound easily reacts with the free radical. When the free radical is a hydroxy radical, such a reaction produces water,
Such products contribute little to the chemical polishing action. On the other hand, the nitrogen-oxygen bond of the nitroso group-containing compound reacts with a free radical by cleavage of the double bond. By such a reaction, free radicals generated in the composition by the chemical polishing are trapped, and amplification of the chemical polishing action is suppressed.

Specific examples of such a phenol compound include phenol, pyrocatechin, resorcin, hydroquinone, orcin, urushiol, pyrogallol, hydroxyhydroquinone and the like. Further, specific examples of the nitroso group-containing compound include nitrosodimethylaniline, nitrosopiperazine, and nitrosopiperidine. Among these, hydroquinone or nitrosopiperidine is preferred from the viewpoints of solubility in water, resistance to compounds in commonly used containers, and economy.

The amount of the free radical scavenger to be added is preferably 0.1 to 2 g / l, more preferably 0.1 to 2 g / l, from the viewpoint of the effect of suppressing the generation of the recess and the effect of the free radical scavenger on the environment.
0.5-1.5 g / liter.

(C) Copper Polishing Accelerator The polishing composition according to the present invention comprises a copper polishing accelerator (hereinafter sometimes simply referred to as a polishing accelerator). The polishing accelerator is at least one compound selected from the group consisting of glycine, α-alanine, and histidine. These compounds are capable of forming a chelate compound with copper ions, and are capable of dissolving copper when added to an aqueous hydrogen peroxide solution.

The addition amount of the polishing accelerator is preferably 3 g / liter or more in order to sufficiently maintain the chemical polishing effect on the layer made of copper and to exert the effect of promoting the polishing. On the other hand, in order to easily control the polishing rate for the copper layer, the amount of the polishing accelerator is preferably 15 g / liter or less. A more preferred addition amount of the polishing accelerator is 6 to 12 g / liter.

(D) Anticorrosive The polishing composition according to the present invention comprises an anticorrosive. This anticorrosive has the function of protecting the polished copper film surface during and after polishing and suppressing the corrosion of copper. Benzotriazole, benzimidazole, triazole, imidazole, and tolyltriazole And at least one compound selected from the group consisting of Among them, it is preferable to use benzotriazole, which exhibits the effects of the present invention more remarkably, as an anticorrosive.

The amount of the anticorrosive added is preferably at least 0.01 g / liter in order to achieve a sufficient anticorrosive effect on copper. On the other hand, the content is preferably 0.1 g / liter or less from the viewpoint of suppressing the non-uniformity of the polishing action due to the excessive protective film forming action. A more preferable addition amount of the anticorrosive is 0.02 to 0.08 g / liter.

(E) Hydrogen peroxide The polishing composition according to the present invention comprises hydrogen peroxide.
Hydrogen peroxide has an effect of forming an oxide film on the surface of the copper film. The formed oxide film is more susceptible to the polishing action of the polishing composition according to the present invention, so that the polishing rate for the copper layer can be improved. Hydrogen peroxide has a characteristic that it has a sufficient oxidizing power to oxidize a copper film, but easily does not contain metal ions that can be impurities.

When hydrogen peroxide is added, the addition amount is preferably 2.5 to 40 g in order to keep the polishing rate appropriate.
Per liter, more preferably 5 to 20 g / liter.

[0036] (f) The polishing composition of the water present invention, other additives according to the components of the and require (described in detail later) in which is dissolved or dispersed in water. Water as such a medium is
It is preferable to use one having a small amount of impurities so that the effects of the present invention are sufficiently exhibited and a product manufactured using the polishing composition according to the present invention is not contaminated by impurities. Specifically, water, distilled water, etc., from which impurity ions are removed by an ion exchange resin and whose suspended matter is removed by a filter, are used.

(G) Other Additives In addition to the above-mentioned essential components, the polishing composition according to the present invention is used for the purpose of maintaining and stabilizing the quality of the product, the type of the workpiece, the processing conditions, and other properties. Various known additives may be further contained as required for polishing.

For example, the polishing composition according to the present invention optionally contains an aliphatic carboxylic acid. Aliphatic carboxylic acids are considered to have a function of suppressing the chemical etching effect on copper, and can be used to improve the polishing rate and the surface quality after polishing. Preferred aliphatic carboxylic acids are a saturated hydrocarbon skeleton, or 1
It has at least one carboxyl group in an unsaturated hydrocarbon skeleton having up to two unsaturated bonds.
Among these carboxylic acids, those having 10 or more carbon atoms are more preferable. Specific examples of such aliphatic carboxylic acids are lauric acid, linoleic acid, myristic acid, palmitic acid, stearic acid, and oleic acid, and the most preferred aliphatic carboxylic acid is oleic acid.

When the polishing composition according to the present invention contains an aliphatic carboxylic acid, from the viewpoint of sufficiently exhibiting the effect of suppressing the chemical etching action on the layer made of copper, the polishing composition is preferably used.
It is preferably at least 01 g / liter, and 0.2 g from the viewpoint of maintaining a sufficiently high polishing rate by appropriately exerting the chemical etching action suppressing effect, and dissolving sufficiently in the polishing composition. / Liter or less is preferred. A more preferred content of the aliphatic carboxylic acid is 0.025 to 0.1 g / liter.

The polishing composition according to the present invention contains a basic compound as required. This basic compound can be used for the purpose of adjusting the pH of the polishing composition and, when the polishing composition according to the present invention contains the above-mentioned aliphatic carboxylic acid, to assist the dissolution thereof. When the polishing composition according to the present invention contains a basic compound, preferred basic compounds are ammonia, ethylenediamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, potassium hydroxide, sodium hydroxide, piperazine, piperidine, and ethanol. It is selected from the group consisting of amines. In particular, those having a small etching effect on the copper film, hardly causing particles to aggregate, and containing no impurity metal are preferable. From such a viewpoint, when the polishing composition according to the present invention contains a basic compound, the most preferable one is tetramethylammonium hydroxide.

Although the pH of the polishing composition of the present invention is not particularly limited, it is generally from 4 to 4 from the viewpoints of safety when using the polishing composition and impact on the environment related to disposal.
9, preferably 6-8.

A surfactant may be added to the composition as another additive to enhance the dispersibility of the abrasive or to adjust the surface tension or viscosity of the polishing composition. Such surfactants include dispersants, wetting agents, thickeners, defoamers, foaming agents, water repellents, and others. For example, typical surfactants used as dispersants include sulfonic acid, phosphoric acid, carboxylic acid, and nonionic surfactants.

<Preparation of Polishing Composition> The composition according to the present invention is generally prepared by mixing the above-mentioned components in water at a desired content, dispersing the abrasive, and dissolving various additives. . The method of dispersing or dissolving these components in water is arbitrary. For example, the components are stirred by a blade-type stirrer or dispersed by ultrasonic dispersion. In addition, the order of mixing these is arbitrary, and in the polishing composition, either the dispersion of the abrasive or the dissolution of the additive may be performed first, or may be performed simultaneously.

Further, the polishing composition according to the present invention can be prepared as a stock solution having a relatively high concentration, stored or transported, and diluted at the time of actual polishing. The preferred concentration range described above is described as the value at the time of actual polishing. Needless to say, when a method of dilution at the time of use is adopted, a solution having a higher concentration is obtained in a state of being stored or transported. No. Furthermore, it is preferable to manufacture in such a concentrated form from the viewpoint of handleability.

The hydrogen peroxide is a metal ion,
It has the property of decomposing when ammonium ions and the like coexist. Therefore, when using hydrogen peroxide as a component of the polishing composition according to the present invention, it is preferable that hydrogen peroxide is added to the composition immediately before use and mixed before use.

<Polishing Method Using Polishing Composition According to the Present Invention> In the polishing method according to the present invention, a layer made of a tantalum-containing compound and a layer made of copper are formed on a substrate in order from the substrate to the surface. A semiconductor device comprising selectively polishing a layer made of copper using the polishing composition.

The semiconductor device as described above has a two-stage polishing process of a first polishing process for polishing a layer mainly composed of copper and a second polishing process for polishing a layer mainly composed of a tantalum-containing compound. Generally, it is polished.
The polishing method according to the present invention corresponds to using the polishing composition in the first polishing step.

Hereinafter, the polishing composition according to the present invention will be described in detail using examples. In addition, the present invention
The configuration is not limited to the examples described below as long as the gist is not exceeded.

[0049]

EXAMPLES Examples 1-27 and Comparative Examples 1-4 <Contents and Preparation of Polishing Composition> Polishing compositions having the compositions shown in Table 1 were prepared. In each case, colloidal silica having an average primary particle size of 30 nm was used.
Here, in Examples 1 to 5, the addition amounts of hydroquinone, glycine, benzotriazole, and hydrogen peroxide were each fixed, and only the concentration of colloidal silica was changed in the range of 0.1 to 150 g / liter. As the hydrogen peroxide solution, a commercially available 31% aqueous solution was used. However, the contents in the table are based on the actual weight of hydrogen peroxide.

In Examples 6 to 9, only the amount of hydroquinone as a free radical scavenger was changed in the range of 0.1 to 2 g / liter, and the concentration of colloidal silica was kept constant at 20 g / liter. In Examples 10 to 13, only the added amount of glycine was changed in the range of 3 to 15 g / liter, and in Examples 14 to 17, only the added amount of benzotriazole was changed in the range of 0.01 to 0.1 g / liter. In Examples 18 to 21, only the addition amount of hydrogen peroxide was changed in the range of 2.5 to 40 g / liter. In Examples 22 to 26, only the amount of oleic acid added was 0 to 0.
It was changed in the range of 2 g / liter. In Example 27, nitrosopiperidine was used as a free radical scavenger.

Comparative Examples 1 to 4 are examples each containing no free radical scavenger, polishing accelerator, anticorrosive, or hydrogen peroxide. Except for Example 22, tetramethylammonium hydroxide was added as a basic compound so that the pH of the composition became 8.

[0052]

[Table 1]

<Polishing Test> Polishing was performed using a polishing machine for single-sided CMP. The surface plate of the polishing machine has a polyurethane laminated polishing pad (Rodale (USA) IC-1000 / Suba40)
0) was applied, and the processing pressure was 2 psi (about 140 g / cm ² ), the rotation speed of the platen was 70 rpm, the supply amount of the polishing composition was 200 cc / min, and the rotation speed of the carrier was 70 rpm.

To calculate the polishing rate, a copper blanket wafer having a copper layer formed by electrolytic plating and a tantalum blanket wafer having a metal tantalum layer formed by sputtering were used as the objects to be polished. Was. These objects to be polished are polished by using a polishing composition for 1 hour.
The polishing rate was calculated from the difference in film thickness before and after polishing.

As a pattern wafer, SE is used.
MATECH 931 pattern wafer was used. Polishing was terminated when the copper layer to be removed was removed. After polishing, using KLA-Tencor HPR340, 10
The recess amount of the μm wiring portion was measured.

From the results of Examples 1 to 5, it can be seen that as the concentration of colloidal silica increases, the polishing rate for the layer made of copper and the layer made of the tantalum-containing compound tends to increase.

Further, it can be seen that the effects of the present invention are exhibited even when the added amounts of the free radical scavenger, the polishing accelerator and the anticorrosive are changed. Furthermore, the effect of the present invention was exhibited even when the type of the free radical scavenger was changed.

Continuation of front page (72) Inventor Tadahiro Kitamura 2-1-1, Nishibiwajima-cho, Nishi-Kasugai-gun, Aichi Prefecture Inside Fujimi Incorporated, Inc. 2-1-1, Machijiri, Fujimi Incorporated Co., Ltd. (72) Inventor Kenji Sakai 2-1-1, Machijiro, Nishi-Biwajima, Nishi-Kasugai-gun, Aichi Prefecture Fujimi Incorporated, Inc. (72) Inventor Katsuyoshi Ina 2-1-1, Nishibiwajima-cho, Nishi-Kasugai-gun, Aichi Prefecture F term in Fujimi Incorporated, Inc. (reference) 3C058 AA07 CA01 DA02 DA12 DA17

Claims (6)

[Claims] 1. A polishing composition comprising the following (a) to (f). (A) at least one abrasive selected from the group consisting of silicon dioxide, aluminum oxide, cerium oxide, zirconium oxide, and titanium oxide; (b) free radical scavenger (c) glycine, α-alanine, and histidine At least one copper polishing accelerator selected from the group consisting of: (d) at least one anticorrosive selected from the group consisting of benzotriazole, benzimidazole, triazole, imidazole, and tolyltriazole; Hydrogen oxide, and (f) water. 2. The polishing composition according to claim 1, further comprising an aliphatic carboxylic acid. 3. The polishing composition according to claim 1, further comprising a basic compound. 4. The method according to claim 1, wherein said free radical scavenger is hydroquinone or nitrosopiperidine.
Item 14. The polishing composition according to Item 1. 5. The polishing composition according to claim 1, wherein the anticorrosive is benzotriazole. 6. On a substrate, in order from the substrate to the surface,
A semiconductor device comprising a layer made of a tantalum-containing compound and a layer made of copper is selectively polished by using the polishing composition according to any one of claims 1 to 5. A polishing method characterized by the above-mentioned.