JP2001115146A - Abrasive for barrier film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an abrasive for a barrier film which can polish a barrier film at a polishing speed equal to or higher than that in the case of polishing a metal film, can polish a metal film and an insulation film at about the same speed, and can finish the surface of a semiconductor substrate flatly. SOLUTION: This abrasive, for polishing a barrier film and a metal film simultaneously, comprises silica particles and water and has a pH adjusted to in the range of 8.5-10.5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel polishing agent for a barrier film. Specifically, the present invention provides a polishing slurry for a barrier film which can polish a barrier film at a polishing rate equal to or higher than that of a metal film and can finish the surface of a semiconductor substrate extremely flat.

[0002]

2. Description of the Related Art Along with the high integration of semiconductor devices, wiring technology has been increasingly miniaturized and multilayered. The multi-layered wiring technology increases the level difference on the surface of the semiconductor substrate. As a result, there is a problem in that the processing accuracy and reliability of wiring formed thereon are reduced, and miniaturization is hindered.

In order to solve the above-mentioned problems caused by the multi-layering, a technique has been developed in which a layer on which wiring patterns, electrodes, etc. (hereinafter, referred to as wirings, etc.) are formed is flattened, and further wirings, etc. are formed thereon. ing.

That is, an insulating film having a concave portion for metal wiring is formed on the surface of a semiconductor substrate, and a metal film is formed thereon so as to fill the concave portion via a barrier film. A polishing method of a semiconductor substrate in which a film and a barrier film are removed by polishing to form a flat surface of an insulating film and a metal film present in a concave portion has been developed.

In the above polishing method, the barrier film has a function of preventing aluminum or copper used as a metal film from diffusing into the insulating film and improving the adhesion of the metal film to the surface of the semiconductor substrate. In general, titanium nitride, tantalum nitride, or the like is used.

In order to realize high polishing performance, the above-mentioned polishing method employs a method in which mechanical polishing is used in combination with a chemical reaction which promotes the polishing. This method is called a chemical mechanical polishing (hereinafter, abbreviated as CMP) method, and various compositions of polishing agents to be used according to a polishing target such as a metal film, an insulating film, and a barrier film have been proposed. The general composition of the above-mentioned abrasive is composed of abrasive grains and a chemical.

As a polishing method using such an abrasive,
A polishing method for performing a first-stage polishing, which is a step of polishing and removing the uppermost metal film, and then performing a second-step polishing, which is a step of polishing and removing the barrier film to flatten the entire surface of the semiconductor substrate It has been known.

The abrasive used in the first-stage polishing is called a first abrasive, and the abrasive used in the second-stage polishing is called a second abrasive.

In the case where the ratio of the polishing rate of the metal film to the barrier film (hereinafter, also referred to as the selectivity) is large, the first polishing agent can use the barrier film as a polishing stop layer. This is advantageous in manufacturing a device with good reproducibility and high accuracy.

However, in the first stage polishing described above,
When a polishing agent having a high selectivity is used, the metal film is preferentially polished, so that the portion of the metal film is dented after polishing is stopped (hereinafter, this phenomenon is referred to as dishing), and some unevenness is generated. This needs to be polished and finely adjusted.

Therefore, in the second-stage polishing, the barrier film can be polished and removed at a practical polishing rate, and furthermore, the metal film and, in some cases, the insulating film can be polished at a practical polishing rate. It is extremely important to make the surface of the semiconductor substrate flat by eliminating steps on the surface.

[0012]

However, there are hardly any conventional abrasives capable of meeting such requirements, and in particular, those using silica particles as the abrasive have not yet been proposed. Not in.

Accordingly, it is an object of the present invention to provide a barrier film polishing agent which can polish a barrier film at a practical speed and a polishing speed equal to or higher than that of a metal film. It is another object of the present invention to provide a polishing agent which can polish a metal film and an insulating film at substantially the same polishing rate. Still another object of the present invention is to provide an abrasive in which generation of scratches on a polished surface due to polishing is suppressed to a low level.

[0014]

Means for Solving the Problems The present inventors have intensively studied to achieve the above object. As a result, a specific p
By using an abrasive made of silica particles and water adjusted to the H range, all of the above objects can be achieved, the barrier film can be efficiently polished, and the flatness of the polished semiconductor substrate surface is extremely excellent. Have been found, and the present invention has been proposed.

That is, the present invention is an abrasive for simultaneously polishing a barrier film and a metal film, comprising silica particles and water, and having a pH adjusted to a range of 8.5 to 10.5. It is an abrasive for barrier films characterized by the following.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the abrasive according to the present invention will be described in detail.

In the present invention, it is important to use silica particles as abrasive grains. That is, when other types of abrasive grains, for example, alumina particles are used as the abrasive grains, there is a problem that scratches are often generated. If a scratch occurs in the polishing step, the wiring of the device will be disconnected or short-circuited, which will greatly reduce the yield of the device.

The silica particles used in the present invention include:
Known ones can be used without particular limitation. For example, fumed silica produced by burning silicon tetrachloride or silane-based gas in a flame, or sol-gel silica produced by hydrolysis using alkoxysilane as a raw material (hereinafter, also referred to as high-purity colloidal silica) And wet silica produced by using sodium silicate as a raw material and neutralized with a mineral acid, and colloidal silica produced by using the sodium silicate as a raw material by the Ostwald process. Preferably, silica particles synthesized in a liquid phase such as a sol-gel method and produced without passing through a drying step are used.

That is, the silica particles synthesized in the liquid phase are excellent in dispersibility, and the shape of the particles is spherical and soft, so that the generation of scratches to be polished during polishing is very small. . Colloidal silica produced by the sol-gel method is extremely high in purity, and thus is suitable for use in a semiconductor device manufacturing process that is resistant to impurity contamination such as heavy metals.

In the present invention, the specific surface area of the silica particles is not particularly limited. A preferred range is 10 to 40
Silica particles in the range of 0 m ² / g can be employed. If the specific surface area of the silica particles is less than 10 m ² / g, the silica particles tend to settle, and if it exceeds 400 m ² / g, the silica particles tend to aggregate.

In particular, the specific surface area of the silica particles is 20 to
When it is in the range of 100 m ² / g, the polishing rate of the barrier film is high, which is preferable.

In the present invention, the silica particles are dispersed in water. In this case, the concentration of the silica particles is 1
The range of -20% by weight is suitably adopted. That is, when the concentration of the silica particles is less than 1% by weight, the polishing rate tends to decrease, and when it exceeds 20% by weight, aggregation of silica tends to occur, and stable polishing is difficult in industrial practice. It tends to be.

The abrasive of the present invention can efficiently polish a barrier film by adjusting the silica particle concentration and adjusting the pH described later in detail, but the metal film, the insulating film and the barrier film can be efficiently polished. Is characterized in that the polishing rate can be appropriately adjusted by the concentration of the silica particles.

Therefore, by changing the silica particle concentration, the polishing rate of each film is controlled to a desired value as a polishing slurry for the barrier film, and a polishing slurry having an optimum selection ratio for the target polishing is prepared. It is possible to

The polishing slurry for barrier film of the present invention has a pH of 8.5.
It is extremely important that the content be adjusted to the range of １10.5, preferably 9-10. That is, by adjusting the pH of the abrasive to the above range, while maintaining the polishing rate of the barrier film high, the polishing rate of other films can also be maintained in a practical range, as described above, silica particles By changing the concentration, the selectivity with other films can be easily adjusted to a desired range.

That is, when the pH is lower than 8.5,
The polishing rate of the metal film may be lower than the polishing rate of the insulating film. If the pH exceeds 10.5, the polishing rate of the insulating film may be excessively high as compared with the polishing rates of other films, and there is a concern that the flatness of the semiconductor substrate surface after polishing may be reduced. You.

When alumina particles are used in the above pH range, the particles tend to aggregate, and it is particularly important to use the silica particles from the viewpoint of the stability of the abrasive grains.

In the present invention, a known basic compound can be added in order to adjust the pH of the abrasive to the above range. The basic compound is not particularly limited, but ammonia, various amines, or salts thereof can be suitably used.

The basic compound may be added in such an amount that the pH of the silica slurry is adjusted to the range of 8.5 to 10.5.

The polishing slurry for a barrier film of the present invention has a high polishing rate for the barrier film and a practical polishing for a metal film which is polished simultaneously with the barrier film in the polishing of the semiconductor substrate. It has a speed and its selectivity can be adjusted precisely by mainly changing the concentration of the silica particles.

Further, the polishing slurry for a barrier film of the present invention is characterized in that the polishing rates of the metal film and the insulating film are very close to each other. After the film is simultaneously polished, it is also useful for simultaneous polishing of a metal film and an insulating film.

In particular, in the simultaneous polishing of the barrier film and the metal film, the selection ratio of the barrier film to the metal film (barrier film / metal film).
A metal film having a thickness of 1 to 3 is preferably used.

That is, when the selectivity is less than 1, the metal film may be polished too much more than the barrier film, and dishing may occur. Also, if the end of the first-stage polishing is too early, a metal film may partially remain on the barrier film in some cases. In such a case, it is necessary to polish the barrier film thereunder while polishing and removing the residual metal film in the second stage polishing. However, when the selectivity exceeds 3, only the barrier film is removed. Is polished, and the remaining metal film cannot be efficiently removed, and there is a concern that a situation may occur in which the barrier film cannot be completely removed.

The polishing rate of the barrier film abrasive of the present invention with respect to the barrier film is generally in the range of 100 to 500 angstroms as the thickness of the barrier film formed on the semiconductor substrate. In the range of 50-1000 Å / min, preferably 100-50
When the thickness is in the range of 0 Å / min, the polishing can be easily controlled, and the time required for removing the barrier film is preferably 2 minutes or less, more preferably 1 minute or less.

That is, if the polishing rate is less than 50 angstroms / min, productivity may decrease, and
At a rate of more than 00 Å / min, not only the barrier film but also the underlying insulating film or the metal film of the wiring may be polished, and it becomes difficult to stop the polishing at a desired position, resulting in poor controllability. There is.

The concentration of silica particles in the polishing slurry for a barrier film is preferably 1 to 20% by weight.

In the above polishing, after the barrier film is polished and removed, the underlying insulating film is exposed. In this case, if the polishing rate of the insulating film is too high with respect to the metal film, the insulating film is polished. There is a possibility that the insulating film is dished too much.

For this reason, it is preferable that the polishing slurry of the present invention can polish a metal film and an insulating film at substantially the same polishing rate. Specifically, it is preferable that the selection ratio of the insulating film to the metal film (insulating film / metal film) is adjusted to a range of 0.5 to 2.

The preferred silica particle concentration of the above-mentioned abrasive for barrier film is 1 to 15% by weight, particularly 2 to 10% by weight.

Accordingly, the concentration of the silica particles is 2 to 10% by weight.
By using the polishing agent of (1), a polishing agent satisfying all of the above conditions can be formed, and simultaneous polishing of the barrier film and the metal film, and simultaneous polishing of the metal film and the insulating film (partial barrier (Including the film) can be continuously performed with the same barrier film polishing agent.

The abrasive for a barrier film of the present invention has a selectivity between a barrier film and a metal film or a selectivity between a metal film and an insulating film within the range not significantly impairing the effects of the present invention. Oxidizing agents, salts, water-soluble polymers or other additives can be added to adjust to a preferred value.

For example, when it is desired to increase the polishing rate of the metal film, it is effective to use an oxidizing agent in combination, and when it is desired to adjust the polishing rates of both the metal film and the insulating film, it is effective to add salts.

However, in this case, when the oxidizing agent and the salt are added in combination, there is a tendency that the selectivity of the barrier film to other films tends to decrease. Therefore, these additives are used alone. It is preferred to add so as to achieve a suitable selectivity.

As the oxidizing agent, known ones can be used without any particular limitation. For example, peroxides, perchlorates, persulfates, oxidizable metal salts, oxidizable metal complexes and the like, among them, hydrogen peroxide and ammonium persulfate in terms of ease of handling, purity, etc. preferable.

As the above salts, known salts can be used without any particular limitation. Preferred representative examples include ammonium salts such as ammonium chloride, ammonium sulfate, ammonium nitrate, ammonium carbonate, ammonium phosphate, ammonium borate, ammonium acetate, ammonium oxalate, ammonium tartrate, ammonium phthalate, ammonium succinate, and ammonium alginate. And salts in which a part of the ammonia in the ammonium salt is replaced with hydrogen, and furthermore, a part or all of the ammonia in the ammonium salt is a cation such as Na, K, Ca, Mg and ethylenediamine, diethylenetriamine, triethylamine, triethanolamine and the like. Salts substituted with various amines are exemplified.

As the salts, those showing basicity such as ammonium carbonate can be used also as the above-mentioned basic compounds.

In the present invention, the concentration of silica particles and the pH range of the abrasive mentioned above mainly describe the optimum concentration and range when used as an abrasive, and those higher than such concentrations and ranges are determined in advance. There is no problem in producing and diluting with pure water at the time of use.

The manufacture of a semiconductor device using the abrasive for a barrier film of the present invention is performed by laminating an insulating film, a barrier film, and a metal film on a semiconductor substrate in a predetermined pattern and polishing them. .

The above-mentioned semiconductor substrate is typically a silicon substrate used for a semiconductor device such as an IC or LSI, but a semiconductor substrate such as germanium or a compound semiconductor is also used.

The insulating film is used for electrical isolation between wiring layers, and is not particularly limited as long as it is insulating. Generally, a silicon oxide film (plasma-TEO)
S film and SOG film) and organic SOG
A membrane or the like is used.

Further, the barrier film is a thin film formed between the insulating film and the metal film in order to prevent the diffusion of the wiring metal into the insulating film and to improve the adhesion of the metal film to the insulating film. In addition, a tantalum film, a tantalum nitride film, a titanium film, a titanium nitride film, a tungsten nitride film, and the like can be given. Among them, a titanium nitride film and a tantalum nitride film are preferable.

Further, the metal film is a wiring material for forming a wiring pattern and an electrode, and examples thereof include an aluminum film, a copper film, and a tungsten film. The abrasive for a barrier film of the present invention exhibits a particularly remarkable effect when a copper film is used as a metal film and a tantalum nitride film is used as a barrier film.

A typical polishing method using the barrier film polishing agent of the present invention will be described in detail with reference to FIG.

The recess A provided in the insulating film formed on the surface of the semiconductor substrate is a groove or a connection hole formed on the insulating film for forming a wiring or the like.

First, (a) the insulating film 2 having the concave portion A
By selectively polishing the barrier film 3 and the metal film 4 which are sequentially laminated thereon by using (b) a metal film polishing agent,
The polishing is stopped at the position where the barrier film 3 exists (first-stage polishing).

In the first stage polishing, the metal film is
It is possible to select and use a known metal film polishing agent that can polish at a high polishing rate of Angstroms / min or more and can selectively remove a metal film from a barrier film while suppressing generation of scratches and dishing. preferable.

Next, (c) using the abrasive for a barrier film of the present invention having the preferred (barrier film / metal film) selectivity described above, simultaneously polishing the barrier film and the metal film, and forming a recess in the insulating film. The remaining barrier film is polished and removed. (Second stage polishing).

Further, if necessary, subsequent to the second polishing step, the insulating film underlying the barrier film and the surface of the metal film embedded in the concave portion of the insulating film are simultaneously polished to flatten the surface of the semiconductor substrate. (Hereinafter, this polishing is also referred to as a third polishing and the polishing agent used for this is also referred to as a third polishing agent).

Since it is necessary to completely remove the barrier film other than the concave portion of the insulating film, it is desirable to perform the two-stage polishing relatively long. That is, it is desirable to continue polishing for several seconds to several hundred seconds longer than the time when it is considered that the barrier film is almost removed. By doing so, the barrier film other than the concave portion of the insulating film can be completely removed, and the step between the insulating film and the metal film can be effectively removed. At that time, the polishing agent of the present invention is not only a barrier film, but also the polishing rate of the metal film and the insulating film is suppressed relatively low,
High controllability, suitable for two-stage polishing. That is, even if the above-described excessive polishing is performed, the thickness of the insulating film is too thin, or the cross-sectional area of the wiring is reduced, so that there is little possibility that the reliability of the semiconductor device is reduced. I have.

As described above, by using the polishing slurry for a barrier film of the present invention as the second polishing slurry, the barrier film can be efficiently removed, and the surface of the semiconductor substrate can be highly flattened. It is possible.

After the second-stage polishing, a third-stage polishing can be performed if necessary. It is preferable that the third polishing agent used for such polishing can polish the metal film, the barrier film, and the insulating film at substantially the same polishing rate. Particularly preferably, the selectivity between the metal film and the barrier film with respect to the insulating film (the polishing rate ratio of the insulating film / metal film and the polishing rate ratio of the barrier film / metal film) is preferably in the range of 0.5 to 2. Is more preferably in the range of 0.7 to 1.4.

If it exceeds the above range, either of the films is selectively polished, dishing occurs, and there is a concern that the flatness of the surface of the semiconductor substrate is reduced.

The third polishing agent may be used by selecting the one having the above selection ratio from known polishing agents, or may be used from the second polishing agent, that is, the polishing agent for barrier film of the present invention. Alternatively, one having the above selection ratio may be selected and used. In the latter case, the second-stage polishing and the third-stage polishing can be performed continuously, which is preferable.

[0064]

As will be understood from the above description, the polishing slurry for a barrier film of the present invention can polish a barrier film at a polishing rate equal to or higher than that of a metal film, and furthermore, the metal film and the insulating film can be polished. Since the polishing can be performed at substantially the same polishing rate, the surface of the semiconductor substrate can be extremely flat.

Further, an insulating film having a concave portion for metal wiring is formed on the surface of the semiconductor substrate, and a metal film is formed thereon so as to fill the concave portion via a barrier film, and then the metal film and the barrier film are polished. In forming the planarized surface of the insulating film and the metal film present in the concave portion by removing the metal film, after selectively polishing the metal film, and then using the polishing agent according to the present invention, the metal film And the barrier film are simultaneously polished,
By simultaneously polishing the metal film and the insulating film, a highly flat semiconductor substrate surface can be obtained.

[0066]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited to these Examples.

(Polishing test) Copper (Cu) film, tantalum nitride (TaN) film, or silicon oxide (SiO ₂ )
A polishing test was performed using a 4-inch silicon wafer having a film formed on the surface. Rodel IC for polishing pad
Using 1000 / SUBA400, processing pressure 300g /
cm ² , platen rotation speed 40 rpm, abrasive dripping speed 80
A polishing test was performed under the condition of ml / min, and a polishing rate was obtained.

(Solubility Test) A solubility test was performed using a silicon wafer having a Cu film formed on the surface. The test pieces were immersed in an abrasive, and the container containing them was placed in a thermostatic shaker maintained at 50 ° C. After 10 minutes, the test piece was taken out of the container, and the abrasive remaining on the surface was washed away.
The dissolution rate of the Cu film was determined from the change in the thickness of the Cu film before and after immersion.

Example 1 and Comparative Example A high-purity colloidal silica particle having a specific surface area of 30 m ² / g, pure water and ammonia water were mixed in predetermined amounts, and the silica particle concentration was 5% by weight and the pH was 9.5. Agents were prepared and evaluated. Also, instead of silica particles, the specific surface area is 70 m ^2.
/ G of γ-alumina particles was prepared in the same manner as above, and an alumina-based abrasive was prepared and evaluated.

Table 1 shows the results of the polishing test. Note that N
o. 2 is a comparative example.

In the case of a silica-based polishing agent, the barrier film T
The polishing rate of the aN film is relatively high at 432 angstroms / min, and the ratio of the polishing rate of the TaN film to the Cu film (hereinafter, abbreviated to the selection ratio of TaN / Cu) is 2.1.
It has been found that the polishing agent of the present invention can polish a barrier film at a polishing rate equal to or higher than that of a metal film, and a polishing rate ratio of a SiO ₂ film to a Cu film (hereinafter, SiO ₂ / Cu).
Is abbreviated to 0.93), which means that the metal film and the insulating film can be polished at almost the same polishing rate, which is suitable for flattening the surface of the semiconductor substrate.

On the other hand, in the case of an alumina-based abrasive, the abrasive was weakly agglomerated, and phase separation occurred when the abrasive was allowed to stand for several hours. When a polishing test was carried out while stirring the abrasive well, a sufficient polishing rate could be obtained for the Cu film, but the TaN film and the SiO ₂ film had a polishing rate much lower than that of the Cu film. Was lower than 1 and the selectivity of SiO ₂ / Cu was lower than 0.5.

When the surface of the wafer with the Cu film after polishing was observed, no scratch was observed on the wafer polished with the silica-based abrasive under a microscope. Was observed. Therefore, it was found that silica particles were suitable as the abrasive grains of the abrasive of the present invention.

[0074]

[Table 1] Example 2 and Comparative Example Example 1, No. 1 except that the pH of the slurry was changed by variously changing the amount of added ammonia. An abrasive was prepared and evaluated in the same manner as in Example 1.

Table 2 shows the results of the polishing test. Note that N
o. Reference numerals 1 and 4 are comparative examples.

When the pH of the abrasive is in the range of 8.5 to 10.5, the selectivity of TaN / Cu is in the range of 1 to 3, and the selectivity of SiO ₂ / Cu is 0.5. ~ 2, which proved to be suitable for use in the second polishing.

When the pH is lower than 8.5, the polishing rate of the Cu film is low, the selectivity of TaN / Cu is higher than 3, and the selectivity of SiO ₂ / Cu is higher than 2. Was. On the other hand, when the pH is higher than 10.5, SiO 2
_Since the polishing rate of the _two films was high, the selectivity ratio of SiO ₂ / Cu was higher than 2.

The dissolution rate of the Cu film was better in the vicinity of neutrality, but was 30 angstrom / min or less even in the pH range of 8.5 to 10.5. It was confirmed that there was.

[0079]

[Table 2] Example 3 Example 1 was repeated except that various types of silica particles having different specific surface areas were used and the concentration of the silica particles was further changed. An abrasive was prepared and evaluated in the same manner as in Example 1.

Table 3 shows the results of the polishing test.

In all cases, the polishing rate of the TaN film was about 30.
0 Angstroms / min and TaN / C
The selectivity of u was in the range of 1-3. Furthermore, SiO ₂ /
The selectivity of Cu was also in the range of 0.5 to 2, which proved to be suitable for the second polishing.

[0082]

[Table 3] Example 4 A test was conducted using several compounds instead of ammonia as the basic compound. A high-purity colloidal silica particle having a specific surface area of 30 m ² / g, a predetermined amount of pure water and ethylenediamine are mixed, and the concentration of the silica particle is 5% by weight and the pH is 9.
5 abrasives were prepared. In addition, the specific surface area is 30 m ² / g
A predetermined amount of high-purity colloidal silica particles, pure water, ammonium carbonate and ammonia are mixed, and the concentration of silica particles is 4
Wt%, the concentration of ammonium carbonate is 2000 ppm, p
An abrasive having H of 9.0 was prepared. Others are Example 1, N
o. An abrasive was prepared and evaluated in the same manner as in Example 1.

Table 4 shows the results of the polishing test.

Even when ethylenediamine or ammonium carbonate is used as the basic compound, the polishing rate of the TaN film is 400 Å / min or more, the selection ratio of TaN / Cu is in the range of 1 to 3, and the selection ratio of SiO ₂ / Cu is also selected. Was in the range of 0.5 to 2 and was found to be suitable for the second polishing.

[0085]

[Table 4] Example 5 Here, the performance of the abrasive for a barrier film of the present invention was examined using a patterned wafer.

First, 7% by weight of high-purity colloidal silica particles having a specific surface area of 75 m ² / g, 0.6% by weight of ammonium carbonate, and 4% by weight of aqueous hydrogen peroxide were alkaline (pH 9.3). A first abrasive was prepared. In addition, in Example No. 1, 1 was used as the second abrasive.

SiO ₂ formed on silicon wafer surface
A wiring groove having a width of 0.35 to 100 μm is formed on the film,
Using a TEG wafer on which a TaN film having a thickness of about 200 angstroms and a Cu film having a thickness of about 1.2 μm were sequentially stacked, the silicon wafer surface was first polished with a first abrasive for about 200 seconds.

As a result, the Cu film on the portion other than the wiring groove of the SiO ₂ film is removed, and the TaN film and the Cu of the wiring groove are removed.
The film was exposed. Then, 1 second with the second abrasive
After polishing for 20 seconds, the TaN film on the SiO ₂ film other than the wiring groove was completely removed, and the SiO ₂ film and the Cu film in the wiring groove were exposed. When the surface of the polished silicon wafer was observed with an electron microscope, no scratch or dishing was observed, and the SiO
There is almost no step on the surface of the Cu film of the ₂ film and the wiring groove,
It was confirmed that a flat surface was formed.

From the above results, after the metal film is polished and removed with the first abrasive, the barrier film and the metal film are simultaneously polished using the barrier film abrasive of the present invention, and the insulating film and the metal film are further polished. It has been found that an extremely flat semiconductor substrate surface can be formed by simultaneous polishing.

For reference, Table 5 shows the respective polishing rates of the first polishing agent and the second polishing agent with respect to the Cu film, the TaN film, and the SiO ₂ film. As can be seen, the first abrasive used here can selectively polish the metal film with respect to the barrier film. On the other hand, it can be seen that the second abrasive can polish the barrier film at a polishing rate equal to or higher than the metal film, and can polish the metal film and the oxide film at substantially the same polishing rate.

[0091]

[Table 5]

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a typical embodiment of a polishing method using the polishing agent of the present invention.

[Explanation of symbols]

 A recess 1 semiconductor substrate 2 insulating film 3 barrier film 4 metal film

Claims (6)

[Claims] An abrasive for simultaneously polishing a barrier film and a metal film, wherein the abrasive is made of silica particles and water, and has a pH adjusted to a range of 8.5 to 10.5. Abrasive for barrier film. 2. The barrier film abrasive according to claim 1, wherein the concentration of the silica particles is in the range of 1 to 20% by weight. 3. The silica particles have a specific surface area of 10 to 400 m.
^The abrasive for a barrier film according to claim 1, which is in the range of ² / g. 4. The ratio of the polishing rate of the barrier film to the metal film (barrier film / metal film) is in the range of 1 to 3.
The abrasive for a barrier film according to the above. 5. The polishing agent for a barrier film according to claim 1, wherein the ratio of the polishing rate of the insulating film to the metal film (insulating film / metal film) is in the range of 0.5 to 2. 6. The polishing agent for a barrier film according to claim 1, wherein the polishing rate of the barrier film is in the range of 50 to 1000 Å / min.