KR20120059592A - Polishing agent for copper polishing and polishing method using the same - Google Patents

Abstract

The abrasive for copper polishing according to the present invention is selected from the group consisting of tetrazole, derivatives of the tetrazole, triazoles and derivatives of the triazoles (except benzotriazole and derivatives of the benzotriazole). At least one leveling agent, an inorganic acid, an amino acid, a protective film-forming agent, an abrasive, an oxidizing agent, and water, and an inorganic acid content of at least 0.080 mol / kg, and an amino acid content of 0.200 mol / kg. The content of the protective film forming agent is 0.020 mol / kg or more, and the ratio of the content of the inorganic acid to the content of the protective film forming agent is 3.0 or more.

Description

Copper polishing abrasive and polishing method using same {POLISHING AGENT FOR COPPER POLISHING AND POLISHING METHOD USING THE SAME}

The present invention relates to an abrasive for copper polishing and a polishing method using the same. The present invention further relates to a high polishing rate copper polishing abrasive suitable for use in a chemical mechanical polishing (CMP) process and a polishing method using the same.

In order to improve the performance of the LSI, the use of a copper alloy has been advanced in place of the conventional aluminum alloy as a wiring material. The copper alloy is difficult to be finely processed by the dry etching method frequently used in the formation of conventional aluminum alloy wirings. Therefore, a copper alloy thin film is deposited on the insulating film in which the groove portion (concave portion) and the ridge portion (convex portion) are formed in advance, and the copper alloy is embedded in the groove portion, and then the copper alloy thin film (copper alloys other than the groove portion) is deposited. The so-called damascene method which removes a thin film by CMP and forms a buried wiring is mainly employ | adopted for the fine processing of a copper alloy (for example, refer following patent document 1).

The general method of CMP with respect to metals, such as a copper alloy, adheres a polishing cloth (polishing pad) on a circular polishing platen (platen), immerses the polishing cloth surface in a metal abrasive, and forms a base metal film. The surface is pressed against the surface of the polishing cloth, and the polishing surface is rotated while applying a predetermined pressure (hereinafter referred to as "polishing pressure") from the back surface to the metal film, and mechanical friction between the abrasive and the metal film on the ridges. This removes the metal film on the ridge.

The abrasive for metals used for CMP generally contains an oxidizing agent and solid abrasive grains (henceforth only "grip"), and also contains a metal oxide dissolving agent and a protective film forming agent as needed. The basic mechanism of CMP using an abrasive containing an oxidizing agent is that the metal film surface is first oxidized by the oxidizing agent to form an oxide layer, and the metal layer is considered to be polished by the abrasive layer being scraped off by abrasive grains. .

In such a polishing method, the oxide layer on the surface of the metal film deposited on the groove portion of the insulating film does not come into contact with the polishing cloth very much, and the effect of shaping by the abrasive grains does not have an effect, but the oxide layer on the surface of the metal film deposited on the raised portion is a polishing cloth. The cutting is carried out in contact with. Therefore, as the CMP progresses, the metal film on the ridge is removed and the surface of the base is flattened (see, for example, Non-Patent Document 1 below).

Generally, in manufacture of LSI, the film thickness of the copper alloy to be polished is about 1 micrometer, and the abrasive | polishing agent whose polishing rate is about 5000 mW / min is used (for example, refer patent document 2 below).

On the other hand, CMP treatment of copper alloy is intended to be applied to the production of high performance and fine wiring boards such as package substrates, and to forming through-through vias (TSVs), which are attracting attention as new mounting methods.

Patent Document 1: Japanese Patent Application Laid-Open No. 2-278822 Patent Document 2: Japanese Patent Publication No. 2003-124160

Non-Patent Document 1: Journal of the Electrochemical Society, Vol. 138, No. 11 (published in 1991), pages 3460-3464

However, in these applications, since the film thickness of a metal film | membrane is thick compared with LSI, the conventional abrasive | polishing agent for LSI has a subject that the grinding | polishing rate is low and productivity falls. In particular, in the case of forming TSV, for example, a copper alloy having a film thickness of 10 µm or more needs to be polished, and therefore, an abrasive capable of higher-speed polishing is required.

In addition, when the solubility of copper in an abrasive | polishing agent etc. is increased in order to further raise a grinding | polishing rate, since corrosiveness with respect to copper becomes high, it exists in the tendency for the copper surface after grinding | polishing to become rough, and flatness will fall. In addition, when excessively increasing the protective film-forming agent (anticorrosive agent) in the abrasive to prevent the copper surface from roughening, the hydrophobicity of the copper reaction layer formed by the copper and the abrasive becomes too high, so that the polishing pad after polishing is colored. There is a problem to say. Pad coloring is caused by the copper reaction layer remaining on the polishing pad even after the polishing process, which causes a deterioration in polishing characteristics such as a decrease in the polishing rate.

This invention is made | formed in view of such a situation, and an object of this invention is to provide the polishing agent for copper polishing which can grind | polish a copper film at high polishing speed and smoothly, without pad coloring, and the polishing method using the same.

The present invention has been made by finding that an abrasive capable of polishing the copper film at high polishing speed and smoothly without pad coloring is obtained by controlling the content of the inorganic acid, the amino acid and the protective film forming agent, the kind of the smoothing agent, and the like. That is, the polishing agent for copper polishing according to the present invention is a group consisting of tetrazole, derivatives of the tetrazole, triazole and derivatives of the triazole (except benzotriazole and derivatives of the benzotriazole). At least one smoothing agent selected from among, an inorganic acid, an amino acid, a protective film-forming agent, an abrasive grain, an oxidizing agent, and water, and an inorganic acid content of 0.080 mol / kg or more, and an amino acid content of 0.200 mol. It is / kg or more, content of a protective film forming agent is 0.020 mol / kg or more, and the ratio (content of an inorganic acid / content of a protective film forming agent) of content of an inorganic acid with respect to content of a protective film forming agent is 3.0 or more.

According to the copper polishing abrasive according to the present invention, the copper film can be polished at a high polishing rate and smoothly without pad coloring. As a result, even in applications where a thick metal film (for example, a metal film having a film thickness of 10 µm or more) is required to be polished, such as a high-performance wiring board or TSV, the polishing process can be performed in a short time, and sufficient productivity can be ensured. .

In addition, in this invention, unless there is a restriction | limiting in particular, "copper" shall also include the metal containing copper (for example, copper alloy, copper oxide, and copper alloy oxide) other than pure copper. In addition, in this invention, unless there is a restriction | limiting in particular, "copper polishing agent" is an abrasive | polishing agent for polishing the metal film (copper film) containing copper, and "metal film containing copper (copper film)" The term "metal film made of pure copper, a metal film containing copper (for example, a copper alloy film, an oxide film of copper and an oxide film of copper alloy), or a laminated film of these metal films and another metal film.

It is preferable that a smoothing agent is at least 1 sort (s) chosen from the group which consists of a compound represented by following formula (I) and a compound represented by following formula (II). In this case, the effect of improving the polishing rate, the effect of reducing the surface roughness and the effect of suppressing the pad coloring can be more highly compatible.

[Formula 1]

[In formula, R <^1> represents a hydrogen atom, a C1-C12 alkyl group, or an amino group.]

[Formula 2]

[Wherein, R ² and R ³ each independently represent a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or an amino group]

It is preferable that an inorganic acid is at least 1 sort (s) chosen from the group which consists of sulfuric acid and phosphoric acid.

It is preferable that pKa1 of an amino acid is 2-3. In addition, "pKa1" means the acid dissociation constant of the 1st dissociable acidic group, and is the negative commercial logarithm of the equilibrium constant Ka of the group.

It is preferable that a protective film forming agent is at least 1 sort (s) chosen from the group which consists of a benzotriazole and the derivative of this benzotriazole.

The abrasive grain is at least one selected from the group consisting of colloidal silica and colloidal alumina, and the average grain size of the abrasive is preferably 100 nm or less.

The oxidizing agent is preferably at least one selected from the group consisting of hydrogen peroxide, persulfate and persulfate.

Moreover, it is preferable that pHs of the abrasive | polishing agent for copper polishing which concerns on this invention are 1.5-4.0. In this case, the copper polishing abrasive according to the present invention contains an inorganic acid and an amino acid having a strong dissolving action and is a pH buffer solution having a pH of 1.5 to 4.0. It's hard to get up. For this reason, it is possible to maintain a stable and high polishing rate without depending on the degree of progress of polishing.

Moreover, this invention provides the grinding | polishing method provided with the process of grind | polishing the metal film containing copper using the said copper polishing abrasive, and removing at least one part of a metal film.

According to this polishing method, the copper film can be polished at a high polishing rate and smoothly without pad coloring. As a result, even in applications in which a thick metal film needs to be polished, such as in the manufacture of high-performance wiring boards or TSVs, polishing can be performed in a short time, and sufficient productivity can be ensured. According to such a grinding | polishing method, the improvement of productivity and the improvement of a product yield can be made compatible.

ADVANTAGE OF THE INVENTION According to this invention, the copper polishing abrasive and the polishing method using the same can be provided with respect to copper which shows the polishing rate which is remarkably quicker than a normal abrasive without pad coloring, keeping the copper surface after grinding smoothly. According to the present invention, in particular, since the polishing rate for copper is more than 30000 kPa / min (preferably 40000 kPa / min), it is possible to polish copper in large quantities in a short time as in the manufacture of high-performance wiring boards and TSVs. The copper polishing abrasive and the polishing method using the same which are optimal for the use which are needed can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is the 1st process chart which shows the usage method at the time of using the abrasive | polishing agent which concerns on one Embodiment of this invention for VIA-LAST.
FIG. 2 is a second process chart showing a use method in the case where the abrasive according to one embodiment of the present invention is used in VIA-LAST. FIG.
FIG. 3 is a third process chart showing a use method when the abrasive according to one embodiment of the present invention is used for VIA-LAST. FIG.

The copper polishing abrasive according to the present embodiment (hereinafter, simply referred to as "polishing agent") is tetrazole, a derivative of the tetrazole, a triazole and a derivative of the triazole (however, benzotriazole and the benzotria). At least one leveling agent selected from the group consisting of sol derivatives), inorganic acids, amino acids, protective film forming agents, abrasive grains, oxidizing agents, and water. In the present embodiment, the content of the inorganic acid is 0.080 mol / kg or more, the content of the amino acid is 0.200 mol / kg or more, the content of the protective film forming agent is 0.020 mol / kg or more, and the content of the inorganic acid with respect to the content of the protective film forming agent. The ratio of content is 3.0 or more.

Moreover, even if each inorganic acid or an amino acid is used independently, although a grinding | polishing speed can be improved to some extent, in this case, the improvement effect of the grinding | polishing rate suitable for content cannot be acquired. On the other hand, according to the abrasive | polishing agent which concerns on this embodiment, the polishing rate of an abrasive | polishing agent can be drastically improved by using an inorganic acid and an amino acid together, and making their content into the said specific amount. In addition, as another aspect, the abrasive according to the present embodiment can reduce the content of the inorganic acid and the amino acid necessary for obtaining the improvement effect of the predetermined polishing rate, as compared with the case where the inorganic acid or the amino acid is used alone. Has an effect.

Moreover, in the conventional abrasive | polishing agent, use of the protective film forming agent has the effect of suppressing the etching of copper by forming a protective film on the copper surface, and generally suppressed the polishing rate. In contrast, according to the abrasive according to the present embodiment, by using the specific amount of the inorganic acid and the amino acid in combination, and then using the specific amount of the protective film forming agent, the effect of suppressing the etching rate can be obtained while maintaining the polishing rate at a high level. .

In addition, the reason why the improvement effect of a polishing rate is acquired by the abrasive | polishing agent which concerns on this embodiment is not necessarily clear, but the present inventors guess as follows. That is, a "reaction layer" containing a protective film forming agent and copper ions is formed on the copper surface by the action of the protective film forming agent and the inorganic acid. In addition, when an amino acid chelates with copper ions, it is thought that the reaction layer is more easily removed and polishing is accelerated.

It is thought that such a plurality of polishing processes do not proceed independently and simultaneously in parallel, but rather that each polishing process proceeds in association with another polishing process. Therefore, even if only one component of an inorganic acid, an amino acid, and a protective film forming agent is increased, it is thought that the polishing process by another component becomes a bottleneck (speeding process), and the polishing rate as a whole does not improve efficiently. On the other hand, in the abrasive | polishing agent which concerns on this embodiment, it is thought that by using a specific amount of each component, each grinding | polishing process is accelerated | stimulated and a polishing rate can be improved efficiently.

In addition, in order to further increase the polishing rate, when an amount of a copper dissolving agent such as an inorganic acid or an organic acid is increased, the content of the protective film forming agent is relatively low, and the corrosion resistance to copper is increased. Therefore, the copper surface after grinding | polishing becomes rough and there exists a tendency for flatness to fall. On the other hand, when excessively increasing the protective film forming agent in an abrasive in order to prevent a copper surface from roughening, there exists a problem that the polishing pad after grinding becomes colored because the hydrophobicity of the copper reaction layer formed by copper and an abrasive becomes too high. Therefore, only by adjusting the content of the protective film forming agent, it is difficult to achieve high compatibility between suppression of coloring of the polishing pad and reduction of roughness of the copper surface after polishing. In addition, in addition to reducing the content of the protective film-forming agent, it is possible to increase the solubility of copper such as inorganic acid and organic acid, etc. to solve the pad coloring. However, as described above, it is considered that all adverse effects are caused on the surface roughness. do.

Therefore, the inventors of the present invention have a content of the protective film forming agent in a range where the degree of pad coloring is sufficiently low and the copper etching rate is sufficiently low, and then a smoothing agent is added to improve the polishing rate, the surface roughness reduction effect, and the pad coloring. It has been found that the inhibitory effect is highly compatible.

By adding a fixed amount of a protective film forming agent, the roughness in the copper surface after grinding | polishing can be reduced by the suppression effect of the etching of copper, but there exists a possibility that pad coloring may occur at the same time. In addition, the smoothing agent which the abrasive | polishing agent which concerns on this embodiment contains does not necessarily reduce an etching rate. Such a smoothing agent differs from the protective film forming agent in that the roughness on the copper surface after polishing is not only reduced, but also pad coloring does not occur, even at an added amount in which the etching rate does not decrease.

The reason why the smoothing agent reduces the roughness is not necessarily clear, but the following reasons can be considered. That is, although the protective film forming agent can reduce the etching rate by acting on the whole surface of the protective effect, it is thought that the effect of reducing the unevenness | corrugation of a copper surface is low. On the other hand, it is thought that the smoothing agent reduces the unevenness | corrugation by the protective effect of a copper surface acting locally on a convex part, and promoting polishing of a convex part.

Hereinafter, each containing component of the abrasive | polishing agent concerning this embodiment is demonstrated more concretely.

(PH of abrasive)

The pH of the abrasive is preferably in the range of 1.5 to 4.0, in that the polishing rate of copper by CMP is higher, and corrosion is not caused to the copper film. Moreover, if pH is 1.5 or more, the surface roughness of a copper film can be reduced further, and it is more preferable that pH is 2.0 or more from a viewpoint. When pH is 4.0 or less, the polishing rate by CMP increases and it becomes a more practical abrasive | polishing agent, and it is more preferable that pH is 3.0 or less from a viewpoint.

The abrasive | polishing agent concerning this embodiment is a pH buffer solution containing an inorganic acid. The inorganic acid is generally a strong acid, and when the abrasive contains a large amount of the inorganic acid, the pH of the abrasive may be excessively lowered, which may make it difficult to adjust the pH to the range of 1.5 to 4.0. However, in the abrasive | polishing agent concerning this embodiment, an amino acid is included in addition to an inorganic acid, and an abrasive | polishing agent can be easily made into pH buffer solution of pH1.5-4.0 by adjusting content of an inorganic acid and an amino acid.

The abrasive | polishing agent concerning this embodiment can contain an acidic component or an alkaline component as a pH adjuster, in order to adjust to desired pH. As such a pH adjuster, organic acids, such as oxalic acid, tartaric acid, maronic acid, maleic acid, malic acid, citric acid, hydrochloric acid, nitric acid, ammonia, sodium hydroxide, tetramethylammonium hydroxide, etc. are mentioned, for example. These can be used individually by 1 type or in combination of 2 or more types. Of course, when the pH of the abrasive is not in the range of 1.5 to 4.0 without including the pH adjuster, the abrasive does not need to contain the pH adjuster.

PH of an abrasive | polishing agent can be measured with a pH meter (for example, Horiba production company, pH meter F8E). As a measurement of pH, after two-point calibration using standard buffer (phthalate pH buffer, pH: 4.01 (25 degreeC); neutral phosphate pH buffer, pH6.86 (25 degreeC)), an electrode was put into an abrasive, The value after having stabilized after 2 minutes or more can be employ | adopted.

(Inorganic acid)

As an inorganic acid, a well-known thing can be used without a restriction | limiting in particular, For example, hydrochloric acid, hydrobromic acid, hydroiodic acid, sulfuric acid, phosphoric acid, nitric acid are mentioned. These can be used individually by 1 type or in combination of 2 or more types. Among the inorganic acids described above, at least one selected from the group consisting of sulfuric acid, phosphoric acid, a mixture of sulfuric acid and phosphoric acid is preferable, because the polishing rate by CMP is high and the surface roughness of the copper film can be further reduced. Moreover, you may use the inorganic acid like a pH adjuster, and may use another inorganic acid.

The content of the inorganic acid is 0.080 mol / kg or more, preferably 0.090 mol / kg or more, and more preferably 0.100 mol / kg or more, based on the polishing rate, in terms of excellent polishing rate. Since the content of the inorganic acid tends not to increase the polishing rate even if the inorganic acid is added to a certain amount or more, the content of the inorganic acid is preferably 1.000 mol / kg or less, and more preferably 0.800 mol / kg or less in view of suppressing an increase in the content of the inorganic acid. Do. In addition, when an abrasive contains two or more types of inorganic acids, "content of an inorganic acid" is taken as the sum total of content of each inorganic acid. In addition, when using inorganic acids, such as hydrochloric acid and nitric acid, as a pH adjuster, "content of an inorganic acid" shall contain content of the inorganic acid used as a pH adjuster.

(amino acid)

Amino acid is used for the purpose of adjusting pH and dissolving copper. There is no restriction | limiting in particular as these amino acids, even if it melt | dissolves in water at least a little, For example, glycine, alanine, varine, leucine, isoleucine, serine, threonine, cysteine, cycithin, methionine, aspartic acid, glutamic acid, lysine, arginine, Phenylalanine, tyrosine, histidine, tryptophan, proline, oxyproline, etc. are mentioned. These can be used individually by 1 type or in combination of 2 or more types.

Among the said amino acids, it is preferable to use the amino acid whose pKa1 is 2-3 because it is easy to adjust pH of an abrasive to 1.5-4.0 more. Examples of such amino acids include glycine, alanine, varin, leucine, isoleucine, serine, threonine, methionine, aspartic acid, glutamic acid, lysine, arginine, and tryptophan, and the effect of improving the polishing rate is given. In particular, glycine is preferable in that it is high and inexpensive. In addition, about the value of "pKa1", a chemical handbook and basic edition II (5th edition, Maruzen Co., Ltd.) can be referred.

The content of amino acid is 0.200 mol / kg or more, more preferably 0.230 mol / kg or more, and more preferably 0.250 mol / kg or more, based on the polishing rate. Since the polishing rate does not tend to increase even if the amount of the amino acid is added to a certain amount or more, the amount of the amino acid is preferably 2.000 mol / kg or less, more preferably 1.800 mol / kg or less from the viewpoint of suppressing an increase in the content of the amino acid. Do.

(Protective Film Forming Agent)

A protective film forming agent means the substance which has an effect | action which forms a protective film with respect to the copper surface. However, as mentioned above, it is considered that the protective film forming agent comprises the "reaction layer" removed at the time of the polishing progress, and does not necessarily form the "protective film" for preventing copper from being polished.

As a protective film forming agent, what is necessary is just to have effective water solubility, in order to exhibit the addition effect of a protective film forming agent, A conventionally well-known substance can be used without a restriction | limiting in particular. Examples of the protective film forming agent include quinalic acid, anthranilic acid, salicylicoxime, benzotriazole compound, imidazole compound, pyrazole compound and the like, and among these, benzotriazole compound is preferable. These can be used individually by 1 type or in combination of 2 or more types.

As a benzotriazole compound, at least 1 sort (s) chosen from the group which consists of a benzotriazole and a benzotriazole derivative is preferable at the point which is excellent in the balance of a polishing rate and an anticorrosive property. Examples of the benzotriazole derivatives include 1-hydroxybenzotriazole, 1-dihydroxypropylbenzotriazole, 2,3-dicarboxypropylbenzotriazole, 4-hydroxybenzotriazole and 4-car Compound (-1H-) benzotriazole, 4-carboxyl (-1H-) benzotriazole methyl ester, 4-carboxyl (-1H-) benzotriazole butyl ester, 4-carboxyl (-1H-) benzo Triazoleoctyl ester, 5-hexylbenzotriazole, [1,2,3-benzotriazol-1-methyl] [1,2,4-triazolyl-1-methyl] [2-ethylhexyl] amine, tolyl Triazole, naphthotriazole, bis [(1-benzotriazolyl) methyl] phosphonic acid, and the like.

As an imidazole compound, 2-methylimidazole, 2-ethylimidazole, 2-isopropylimidazole, 2-propylimidazole, 2-butylimidazole, 4-methylimidazole, for example. Sol, 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, 2-aminoimidazole and the like.

As a pyrazole compound, 3, 5- dimethyl pyrazole, 3-amino-5-methylpyrazole, 4-methylpyrazole, 3-amino-5-hydroxypyrazole, etc. are mentioned, for example.

Since the content of the protective film forming agent can make the etching rate of the metal smaller, the amount of the protective film forming agent is 0.020 mol / kg or more, preferably 0.025 mol / kg or more, and more preferably 0.030 mol / kg or more based on the total amount of the abrasive. The content of the protective film forming agent tends not to increase the polishing rate even when the protective film forming agent is added to a predetermined amount or more. Therefore, the content of the protective film forming agent is preferably 0.300 mol / kg or less, and is 0.250 mol or less in terms of suppressing an increase in the content of the protective film forming agent. It is more preferable that it is / kg or less.

The ratio of the content of the inorganic acid (mol / kg) to the content of the protective film forming agent (mol / kg) (content of the inorganic acid / content of the protective film forming agent) is improved from the viewpoint of reducing the pad coloring while improving the polishing rate. It is 3.0 or more, It is preferable that it is 3.2 or more, It is more preferable that it is 3.5 or more. It is preferable that it is 12 or less, and, as for the said ratio, further suppressing increase of surface roughness, it is more preferable that it is 10 or less.

(Smoothing agent)

A smoothing agent means the substance which has the effect | action which keeps the copper surface after grinding smooth in the range of content which does not have a big influence on an etching rate, a polishing speed, and pad coloring. In the abrasive according to the present embodiment, the leveling agent consists of a tetrazole, a derivative of the tetrazole, a triazole, and a derivative of the triazole (except benzotriazole and a derivative of the benzotriazole). At least one selected from the group. These can be used individually by 1 type or in combination of 2 or more types. As a smoothing agent, in order to exhibit the addition effect of a smoothing agent, it is preferable to have effective water solubility.

As a tetrazole and the derivative of this tetrazole, the compound represented by following formula (I) is preferable. As a compound represented by following formula (I), it is 1H- tetrazole; More preferred are derivatives such as 5-amino-1H-tetrazole, 5-methyl-1H-tetrazole, and 5-phenyl-1H-tetrazole.

(3)

[In formula, R <^1> represents a hydrogen atom, a C1-C12 alkyl group, or an amino group.]

As the triazole and the derivatives of the triazole, 1,2,3-triazole and its derivatives, 1,2,4-triazole and its derivatives are preferable. As 1,2,3-triazole and its derivatives, for example, 1H-1,2,3-triazole, 2H-1,2,3-triazole, 4H-1,2,3- 1,2,3-triazole such as triazole; Derivatives such as 1-amino-4-methyl-1H-1,2,3-triazole, 5-methyl-1H-1,2,3-triazol-1-amine, and the like. As 1,2,4-triazole and its derivative (s), the compound represented by following formula (II) is preferable, For example, 1H-1,2,4-triazole; 3-amino-1H-1,2,4-triazole, 3-mercapto-1,2,4-triazole, 3-nitro-1,2,4-triazole, 1,2,4-triazole Derivatives such as -3-carboxamide, 3-amino-5-mercapto-1,2,4-triazole, 3,5-diamino-1,2,4-triazole, and the like.

[Formula 4]

[Wherein, R ² and R ³ each independently represent a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or an amino group]

The content of the smoothing agent is preferably 0.0001 mol / kg or more, more preferably 0.0005 mol / kg or more, more preferably 0.0010 mol / kg or more, based on the total amount of the abrasive, in that the roughness of the copper surface after polishing can be made smaller. More preferred. Since the copper surface roughness after grinding | polishing tends not to fall even if content of a smoothing agent adds a fixed amount or more, it is preferable that it is 0.500 mol / kg or less from the point which suppresses the increase of content of a smoothing agent, and is 0.250 mol It is more preferable that it is / kg or less.

(Grip)

The abrasive grains are not particularly limited, and examples thereof include inorganic abrasive grains such as silica, alumina, zirconium oxide, ceria, titania, and silicon carbide, and organic abrasive grains such as polystyrene, polyacryl, and polyvinyl chloride. Among these, silica and alumina are preferable in that the dispersion stability in the abrasive is good and the number of scratches (scratches) generated by CMP is small, the particle size is easy to control, and the polishing properties are superior. In the above, colloidal silica and colloidal alumina are more preferable. As a method for producing colloidal silica, a method by hydrolysis of silicon alkoxide or ion exchange of sodium silicate is known. As a manufacturing method of colloidal alumina, the method by the hydrolysis of aluminum nitrate is known. These can be used individually by 1 type or in combination of 2 or more types.

In addition, it is preferable that the average particle diameter of an abrasive grain is 100 nm or less from the point which is further excellent in a grinding | polishing speed, and can make surface roughness after grinding | polishing smaller. When the average particle diameter of an abrasive grain is 100 nm or less, at least 1 sort (s) chosen from the group which consists of colloidal silica and colloidal alumina is more preferable. In addition, the average particle diameter of an abrasive grain is D50 when the particle diameter of the abrasive grain in an abrasive | polishing agent is measured by the laser diffraction type particle size distribution analyzer (For example, Master Sizermicroplus by Malvern Instruments, refractive index: 1.9285, light source: He-Ne laser, absorption 0). It is the value (median diameter of the volume distribution, cumulative median).

It is preferable that it is 0.1 weight% or more with respect to abrasive whole quantity, and, as for content of an abrasive grain, since a physical grinding action is fully acquired and polishing rate becomes high, it is more preferable that it is 0.2 weight% or more. In addition, even if the abrasive contains a large amount of abrasive grains, the polishing rate is saturated and the polishing rate is difficult to increase, so that the increase in the content of the abrasive grains can be suppressed, and the aggregation of the abrasive grains and the increase in the scratches can be further suppressed. It is preferable that it is 20 weight% or less, it is more preferable that it is 10 weight% or less, and, as for content of an abrasive grain, it is still more preferable that it is 5 weight% or less.

(Oxidizer)

The oxidizing agent can be used without particular limitation as long as it has an oxidation effect on copper. As the oxidizing agent, for example, hydrogen peroxide (H ₂ O ₂ ); Persulfate; Persulfates such as ammonium persulfate and potassium persulfate; Periodic acid; Periodic acid salts, such as sodium periodate and potassium periodate, etc. are mentioned, At least 1 sort (s) chosen from the group which consists of hydrogen peroxide, a persulfate, and a persulfate is preferable at the point which is excellent in a polishing rate. These oxidizing agents can be used individually by 1 type or in combination of 2 or more types.

It is preferable that it is 0.1 weight% or more with respect to an abrasive | polishing agent whole quantity, and, as for content of an oxidizing agent, since a favorable polishing rate is easy to be obtained, it is more preferable that it is 0.2 weight% or more. Moreover, even if an abrasive contains an excessive amount of an oxidizing agent, since a polishing rate may not improve or may fall rather, it is preferable that content of an oxidizing agent is 20 weight% or less, and it is more preferable that it is 15 weight% or less.

(water)

Although water in particular as a medium of an abrasive | polishing agent is not restrict | limited, Deionized water, ion-exchange water, ultrapure water, etc. are preferable. The content of water in the abrasive may be the remainder of the content of the above-described components, and is not particularly limited as long as it is contained in the abrasive. In addition, the abrasive may further contain a solvent other than water, for example, a polar solvent such as ethanol, acetic acid, acetone, or the like, if necessary.

In addition to the above components, the abrasive may further contain a material generally used for the abrasive, such as a dispersant and a coloring agent, in a range that does not impair the effect of the abrasive.

(Preservation method of the polishing agent)

There is no restriction | limiting in particular in the storage method of an abrasive | polishing agent, You may preserve | saved as a one-component abrasive containing all the constituents, and may store it as a concentrated one-component abrasive which reduced the content of water from this one-component abrasive.

Moreover, you may divide and preserve the structural component of the said abrasive | polishing agent at least into a slurry (1st liquid) and an addition liquid (2nd liquid) so that it may mix with each other and become an objective abrasive. In the case of a two-component abrasive, for example, it is divided into a slurry containing an abrasive, a leveling agent, an inorganic acid, an amino acid, and a protective film forming agent, and an additive liquid containing an oxidizing agent. Moreover, you may divide and store into the concentrated slurry and the concentrated addition liquid which respectively reduced content of water from the slurry and the addition liquid. If the slurry and the additive are stored without mixing, the storage stability of the abrasive can be improved. Moreover, you may divide and store the structural component of an abrasive | polishing agent into three or more liquids.

(Polishing method)

The grinding | polishing method concerning this embodiment is equipped with the grinding | polishing process of grinding | polishing the metal film containing copper using the said abrasive | polishing agent, and removing at least one part of a metal film. In the polishing step, the substrate and the polishing plate are relatively moved by feeding the abrasive between the metal film and the polishing cloth while pressing the metal film of the substrate on which the metal film (the polishing film) is formed on the polishing cloth of the polishing platen. It is desirable to polish the film.

In the case of a two-component abrasive, the polishing method according to the present embodiment includes, for example, an abrasive preparation step of mixing the slurry and the additive liquid to obtain an abrasive, and the substrate of the substrate by the polishing method. And a polishing step of polishing the polishing surface.

The abrasive | polishing agent which concerns on this embodiment has the characteristic that the grinding | polishing speed is extremely quick compared with the conventional abrasive | polishing agent for copper grinding | polishing, For example, the manufacturing process of the high performance fine wiring board represented by package substrates, such as LSI, etc. It can use suitably especially for grind | polishing the thick metal film in. More specifically, it can use especially suitably when grind | polishing the board | substrate whose thickness of the metal film containing copper to be polished is 4 micrometers or more.

Thus, as a process which needs to grind a very thick metal film, the process of forming a through-via via (TSV) is mentioned. Various methods have been proposed for the formation of TSVs, but as a specific example, there is a method called VIA-LAST for forming vias after forming elements. Hereinafter, the usage method at the time of using the abrasive | polishing agent concerning this embodiment in a VIA-LAST process is demonstrated, referring drawings.

FIG. 1: is a schematic cross section which shows the process of forming the copper layer 4 on the silicon substrate 1. FIG. As shown in FIG. 1A, the element 2 is formed at a predetermined position on the silicon substrate 1. Next, as shown in FIG.1 (b), the recessed part 3 for making a through via is formed by methods, such as plasma etching. Next, copper is laminated so as to fill the recess 3 by a method such as sputtering or electroplating to form a copper layer 4 to obtain a substrate 100 having a structure shown in FIG. 1 (c). .

FIG. 2: is a schematic cross section which shows the process of grinding the board | substrate 100 formed in this way, and forming bump 5 in one surface. As shown in FIG.2 (b), supplying the said abrasive | polishing agent between the surface of the copper layer 4 in FIG.2 (a), and a polishing cloth (not shown), the element 2 will expose. The copper layer 4 is polished until it is.

More specifically, the copper layer 4 is pressed against the polishing cloth of the polishing plate while supplying the abrasive between the copper layer 4 of the substrate 100 and the surface of the polishing cloth of the polishing platen. The copper layer 4 is polished by moving the polishing plate and the substrate 100 relatively. Instead of the polishing cloth, a brush made of metal or resin may be used. Moreover, you may grind by blowing an abrasive | polishing agent at predetermined pressure.

As the polishing apparatus, for example, when polishing with a polishing cloth, a general polishing apparatus having a polishing table capable of attaching the polishing cloth and a holder to hold the substrate to be polished, while being connected to a motor capable of changing the rotation speed, etc. Can be used. As a material of an abrasive cloth, a general nonwoven fabric, foamed polyurethane, a porous fluororesin, etc. can be used, There is no restriction | limiting in particular.

Although there are no limitations on the polishing conditions, the rotation speed of the polishing platen is preferably low rotation of 200 rpm or less so that the substrate does not protrude. The pressure (polishing pressure) strongly pressed against the polishing cloth of the substrate having the surface to be polished is preferably 1 to 100 kPa, and in order to improve the uniformity in the surface to be polished and the flatness of the pattern at the CMP speed, the pressure is 5 to 50 kPa. It is more preferable. While polishing, the polishing cloth can be continuously supplied with a pump or the like. Although this supply amount is not limited, it is preferable that the surface of the polishing cloth is always covered with an abrasive.

It is preferable to dry the board | substrate after completion | finish of grinding | polishing after flowing well in flowing water, after dropping the water droplet which adhered on the board | substrate using spin dry etc. In order to carry out CMP with the surface state of the polishing cloth always the same, it is preferable to include a conditioning step of polishing cloth before polishing. For example, the polishing cloth is adjusted with a liquid containing at least water using a dresser with diamond particles. Then, it is preferable to perform the CMP grinding | polishing process by this embodiment, and to further add a board | substrate washing | cleaning process.

Subsequently, as shown in FIG.2 (c), the bump 5 is formed in the surface part of the exposed copper layer 4 by methods, such as electroplating, and the board | substrate which has bump 5 in one surface is shown. Get 200. Copper etc. are mentioned as a material of the bump 5.

FIG. 3: is a schematic cross section which shows the process of forming the bump 6 in the other surface. In the board | substrate 200 of the state shown to FIG. 3 (a), the surface in which the bump 5 in the silicon substrate 1 is not formed (opposite surface of the surface in which the bump 5 is formed), The copper layer 4 is exposed by polishing by a method such as CMP (Fig. 3 (b)). Next, the bumps 6 are formed by the same method as that for forming the bumps 5 to obtain a substrate 300 on which TSVs are formed (FIG. 3 (c)).

Example

Hereinafter, although an Example demonstrates this invention, this invention is not restrict | limited to such an Example. In addition, unless otherwise indicated, "%" shall mean "weight%."

(Production of polishing agent)

(Example 1)

10.2 g of sulfuric acid at 96% concentration, 11.5 g of phosphoric acid at 85% concentration, 40.6 g of glycine, 4.Og of benzotriazole, 1.Og of 1,2,4-triazole, and ammonia solution of tetraethoxysilane as an abrasive. 50 g of colloidal silica (solid content 20%) having an average particle diameter of 70 nm produced by hydrolysis of was added to 600 g of pure water to dissolve components other than colloidal silica. After further adding 25% aqueous ammonia to adjust the pH of the liquid to 2.6, pure water was further added to make the total amount 700 g. To this was added 300 g of hydrogen peroxide water (reagent grade, 30% aqueous solution) to obtain an abrasive 1 having a total amount of 1000 g.

(Example 2)

Abrasive 2 was prepared in the same manner as in Example 1 except that 3-amino-1H-1,2,4-triazole 1.Og was added instead of 1,2,4-triazole 1.Og.

(Example 3)

Abrasive 3 was produced in the same manner as in Example 1 except that 0.1 g of 1H-tetrazole was added instead of 1,2 g of 1,2,4-triazole.

(Example 4)

Abrasive 4 was prepared in the same manner as in Example 1 except that 0.1 g of 5-amino-1H-tetrazole was added instead of 1,2 g of 1,2,4-triazole.

(Example 5)

Abrasive 5 was produced in the same manner as in Example 1 except that 0.1 g of 5-methyl-1H-tetrazole was added instead of 1,2 g of 1,2,4-triazole.

(Comparative Example 1)

Example 1 except that the amount of sulfuric acid was 2.6g, the amount of phosphoric acid was 2.9g, the amount of glycine was 10.2g, the amount of benzotriazole was 2.Og, and 1,2,4-triazole was not added. Abrasive X1 was produced in the same manner as in the above.

(Comparative Example 2)

Abrasive X2 was produced in the same manner as in Comparative Example 1 except that the amount of sulfuric acid was 5.1 g and the amount of phosphoric acid was 5.8 g.

(Comparative Example 3)

Abrasive X3 was produced in the same manner as in Comparative Example 1 except that the amount of glycine was 20.3 g, and 36% hydrochloric acid was used in place of aqueous ammonia for pH adjustment.

(Comparative Example 4)

Abrasive X4 was produced in the same manner as in Comparative Example 1 except that the amount of benzotriazole was 4.Og.

(Comparative Example 5)

Abrasive X5 was produced in the same manner as in Comparative Example 1 except that the amount of sulfuric acid was 5.1 g, the amount of phosphoric acid 5.8 g, the amount of glycine 20.3 g, and the amount of benzotriazole was 4.Og.

(Comparative Example 6)

Abrasive X6 was produced in the same manner as in Comparative Example 1 except that the amount of sulfuric acid was 10.2 g, the amount of phosphoric acid was 11.5 g, the amount of glycine was 40.6 g, and the amount of benzotriazole was 8.Og.

(Comparative Example 7)

Abrasive X7 was produced in the same manner as in Comparative Example 6 except that the amount of benzotriazole was 6.Og.

(Comparative Example 8)

Abrasive X8 was produced in the same manner as in Comparative Example 6 except that the amount of benzotriazole was 4.Og.

(Comparative Example 9)

Abrasive X9 was produced in the same manner as in Comparative Example 8 except that 1.Og of imidazole was further added.

(Comparative Example 10)

Abrasive X10 was produced in the same manner as in Comparative Example 8 except that 1.Og of 2,4-dimethylimidazole was further added.

(Comparative Example 11)

Abrasive X11 was produced in the same manner as in Comparative Example 8 except that 1.Og of pyrazole was further added.

(Comparative Example 12)

Abrasive X12 was produced in the same manner as in Comparative Example 8 except that 1.Og of 3,5-dimethylpyrazole was further added.

(Comparative Example 13)

Abrasive X13 was produced in the same manner as in Comparative Example 8 except that 1.Og of 3-hydroxybenzotriazole was further added.

(Comparative Example 14)

Abrasive X14 was produced in the same manner as in Comparative Example 8 except that 0.1 g of dodecylbenzenesulfonic acid was further added.

(PH measurement of the abrasive)

The pH of the said abrasive 1-5, X1-X14 was measured using the pH meter F8E of Horiba Corporation. As a measurement of pH, after two-point calibration using a standard buffer solution (phthalate pH buffer solution, pH: 4.01 (25 degreeC); neutral phosphate pH buffer, pH6.86 (25 degreeC)), an electrode was put into an abrasive, The value after having stabilized after 2 minutes or more was employ | adopted.

(Polishing of substrate)

The board | substrate (purchased from Advantech Co., Ltd.) which formed the 20-micrometer-thick copper film on the silicon substrate of diameter 8 inches (20.3 cm) (phi) size was prepared. Using this board | substrate, CMP grinding | polishing was implemented, adding the said abrasive | polishing agent 1-5 and abrasive | polishing agent X1-X14 to the polishing cloth stuck to the surface plate of the grinding | polishing apparatus.

In addition, polishing conditions are as follows.

Polishing device: platen diameter 600 mm (φ), rotary type

Abrasive cloth: Expanded polyurethane resin (IC-1010, Rohm and Haas, Inc., brand name) having an independent bubble

Polishing pressure: 32kPa

Polishing plate / head rotation speed: 93/87 rpm

Abrasive Flow Rate: 200ml / min

[Evaluation Items and Evaluation Methods of Polishing Test]

(Polishing speed, surface roughness, pad coloring)

With respect to the substrate polished as described above, the polishing rate of copper by CMP (hereinafter, simply referred to as "polishing rate") and surface roughness were measured, and the degree of coloring of the pad surface after polishing (hereinafter, simply " Pad coloring ”).

Polishing rate: The film thickness difference of the board | substrate before and behind CMP was calculated | required in conversion from sheet resistance change, and also the polishing rate was computed. The measurement apparatus used the resistivity meter Model RT-7 by Napson. The average value of 77 points of radial directions of the wafer (excluding the 5 mm portion from the edge) was calculated as the resistance value.

Surface roughness (arithmetic mean roughness Ra): The surface roughness of the polished copper film was measured by AFM (Atomic Force Microscope: SPA-400, manufactured by SIA INano Technology Co., Ltd.). The measurement was performed in the area range of 5 micrometers x 5 micrometers in the location 50 mm away from the board | substrate center in the radial direction.

Pad coloring: The surface of the pad after completion of polishing was visually observed and evaluated according to the following criteria.

No pigmentation observed: A

Little staining observed: B

Full coloring observed: C

(Etching speed)

The abrasive | polishing agent was stirred at room temperature (25 degreeC) (600 rpm), and the silicon substrate (copper base) which deposited the copper film of thickness 1500nm was immersed in the said abrasive | polishing agent. The film thickness difference of the copper film of the copper base before and after immersion was calculated | required in conversion from the electrical resistance value.

Table 1-Table 3 show the evaluation results of the abrasives 1 to 5, the components contained in X1 to X14, the pH of each abrasive and the polishing test.

[Table 1]

TABLE 2

[Table 3]

The following can be seen from the results shown in Tables 1 to 3. That is, each abrasive in Examples 1-5 showed the favorable grinding | polishing rate. Moreover, surface roughness and the etching rate were also favorable, and pad coloring was not observed.

On the basis of the polishing rate of Comparative Example 1, the polishing rates of Comparative Examples 2 to 4 were increased and decreased as follows. When it was made to be the same as Comparative Example 1 except that the content of the inorganic acid was 0.080 mol / kg or more (Comparative Example 2), the polishing rate was increased to 3000 Pa / min. When it was the same as Comparative Example 1 (Comparative Example 3) except that the content of amino acid was 0.200 mol / kg or more, the polishing rate was reduced to 3,000 Pa / min. When the content was the same as that of Comparative Example 1 (Comparative Example 4) except that the content of the protective film forming agent was 0.020 mol / kg or more, the polishing rate was reduced by 3,000 Pa / min.

From the change of the polishing rate of these comparative examples 2-4, the polishing rate at the time of containing the inorganic acid of the same amount with the comparative example 2, the amino acid of the same amount with the comparative example 3, and the protective film formation agent of the same amount with the comparative example 4 is the comparative example 1 It can be expected that the 3000 Å / min plus the increase or decrease in the polishing rate of Comparative Examples 2 to 4 relative to each other decreases. However, in the comparative example 5 containing an inorganic acid, an amino acid, and a protective film formation agent at such content, the polishing rate became 11000 dl / min. Moreover, in the comparative example 6 whose content of an inorganic acid is 0.080 mol / kg or more, the content of an amino acid is 0.200 mol / kg or more, and the content of a protective film forming agent is 0.020 mol / kg or more, the polishing rate is 21000 kPa / compared with the comparative example 1 min was increased. From these results, when content of each component reached the required amount, it was confirmed that the polishing rate improves, suppressing the increase of surface roughness. However, regarding Comparative Examples 5 and 6, there is a problem that pad coloring is observed, and the improvement of the polishing rate, the reduction of the surface roughness, and the suppression of the pad coloring are not simultaneously achieved.

On the other hand, when the content of benzotriazole was reduced in comparison with Comparative Example 6 as in Comparative Examples 7, 8, the polishing rate was improved while suppressing pad coloring, but the surface roughness deteriorated.

In Examples 1 to 5, the required amount of the smoothing agent was added to Comparative Example 8 in which the surface roughness was insufficient, and while the pad coloring could be suppressed while maintaining the polishing rate high, the surface roughness was added by the effect of the smoothing agent. Could be reduced to 10 nm or less.

On the other hand, the effect of improving the surface roughness was not found in the case where a substance having a relatively similar structure to the leveling agent of Examples 1 to 5 was added to Comparative Example 8 (Comparative Examples 9 to 12). Moreover, although the effect of reducing surface roughness and the etching rate was confirmed in the comparative example 13 which added the benzotriazole derivative, pad coloring generate | occur | produced. Moreover, about the comparative example 14 which added dodecyl benzene sulfonic acid, although the etching rate drastically decreased, the improvement effect of surface roughness was not confirmed.

By optimizing the contents of the inorganic acid, the amino acid, and the protective film forming agent and adding an appropriate leveling agent, the polishing agent exhibits a polishing rate significantly higher than that of the usual polishing agent with respect to copper, and there is no pad coloring, and the copper surface after polishing is smooth. Was obtained. In particular, an abrasive having a polishing rate of more than 30000 kPa / min for copper is most suitable for a use (for example, a TSV forming use) that requires a large amount of polishing of copper in a short time.

One… Silicon substrate; Element; Copper layer, 5, 6... Bump, 100, 200, 300... Board

Claims (9)

At least one smoothing agent selected from the group consisting of tetrazole, derivatives of the tetrazole, triazoles and derivatives of the triazoles (except benzotriazoles and derivatives of the benzotriazoles), and inorganic acids; , Amino acids, protective film forming agents, abrasive grains, oxidizing agents, water,
The content of the inorganic acid is 0.080 mol / kg or more,
Content of the said amino acid is 0.200 mol / kg or more,
The protective film forming agent content is 0.020 mol / kg or more,
The abrasive | polishing agent for copper abrasives whose ratio of content of the said inorganic acid with respect to content of the said protective film forming agent is 3.0 or more. The method of claim 1,
The said abrasive | polishing agent is at least 1 sort (s) chosen from the group which consists of a compound represented by following formula (I) and a compound represented by following formula (II), The abrasive for copper polishing.
[Formula 1]

[In formula, R <^1> represents a hydrogen atom, a C1-C12 alkyl group, or an amino group.]
(2)

[Wherein, R ² and R ³ each independently represent a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or an amino group] The method according to claim 1 or 2,
An abrasive for copper polishing, wherein the inorganic acid is at least one selected from the group consisting of sulfuric acid and phosphoric acid. 4. The method according to any one of claims 1 to 3,
The abrasive | polishing agent for copper grinding | polishing whose pKa1 of the said amino acid is 2-3. 5. The method according to any one of claims 1 to 4,
The said abrasive | polishing film former is at least 1 sort (s) chosen from the group which consists of a benzotriazole and the derivative of this benzotriazole, The abrasive for copper polishing. The method according to any one of claims 1 to 5,
Said abrasive grain is at least 1 sort (s) chosen from the group which consists of colloidal silica and colloidal alumina, The abrasive grain for copper polishing whose average particle diameter of this abrasive grain is 100 nm or less. The method according to any one of claims 1 to 6,
The said abrasive | polishing agent is at least 1 sort (s) chosen from the group which consists of hydrogen peroxide, persulfate, and persulfate, The abrasive for copper polishing. The method according to any one of claims 1 to 7,
Copper polishing abrasive with a pH of 1.5-4.0. A polishing method comprising the step of polishing a metal film containing copper by using the copper polishing abrasive according to any one of claims 1 to 8, and removing at least a part of the metal film.

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