JPH10279926A - Polishing liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polishing liquid capable of polishing the surfaces of metal films at speeds of practical levels, capable of inhibiting the generation of damages on the surfaces of the metal films, and useful for forming the embedded metal wirings of semiconductor devices, etc., by including colloidal alumina and water. SOLUTION: This polishing liquid contains (A) colloidal alumina and (B) water as essential components. In addition to the components A and B, the polishing liquid preferably contains (C) 2-quinoline carboxylic acid and (D) an oxidizing agent in a case of a Cu (alloy)-polishing liquid, the component D and (E) a polish-accelerating agent comprising ferric trichloride or a mixture of trimethyl (ammonium) hydroxide, phosphoric acid-sulfuric acid-acetic acid in a case of an Al (alloy)-polishing liquid, or the component D and (F) a polishing accelerating agent comprising ferric trichloride or ferric trinitrate in a case of a W-polishing liquid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing liquid for polishing various metals, and more particularly to a polishing liquid used for forming embedded metal wiring of a semiconductor device or a liquid crystal display device.

[0002]

2. Description of the Related Art For example, in the formation of a wiring layer, which is one of the manufacturing steps of a semiconductor device, an etch-back technique is employed in order to eliminate a step on the surface. In this etch-back technique, a wiring-shaped groove is formed in an insulating film on a semiconductor substrate, a metal film made of Al, Cu, or the like is deposited on the insulating film including the groove, and the metal film is polished and polished. This is a method in which a buried wiring layer is formed by polishing using a liquid and leaving a metal film only in the groove.

[0003] By the way, as the polishing liquid, α
-A material made of pure water in which abrasive grains are dispersed, such as alumina or γ-alumina, is used. Generally, alumina particles are produced by thermally decomposing a composite salt of alumina to grow grains. At this time, γ-phase and α-phase are separately formed depending on the heat treatment temperature, and γ-alumina having a low heat treatment temperature has a softer property than α-alumina heat-treated at a high temperature. As the alumina-based abrasives, M-50 of trade name manufactured by Showa Denko KK,
M-40, trade name CP2, CP3 manufactured by Baikowski
CP5 and the like are known.

However, when a metal surface is precisely polished with a polishing liquid containing the above-mentioned abrasive grains, scratches are generated on the surface. In particular, when the polishing liquid is applied to the above-described etch-back technique for forming the embedded wiring of the semiconductor device, a scratch having a depth of about 20 nm occurs on the surface of the formed embedded wiring. When an accelerated test is performed on an embedded wiring having such a flaw to determine the quality of the wiring, there is a problem in that the wiring is broken from the location of the flaw.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a polishing liquid which can polish a metal film and can suppress generation of scratches on the surface. Another object of the present invention is to provide a polishing liquid that can polish a metal film made of Cu or the like at a practical level of speed and can also suppress generation of scratches on the surface.

[0006]

The polishing liquid according to the present invention is characterized by containing colloidal alumina and water. Another polishing liquid according to the present invention is Cu
Alternatively, it is a polishing solution for polishing a Cu alloy, which is characterized by containing 2-quinolinecarboxylic acid, an oxidizing agent, colloidal alumina and water.

[0007] Still another polishing liquid according to the present invention is Al.
Or a polishing liquid for polishing an Al alloy, trimethylammonium hydroxide, trimethyl hydroxide,
It is characterized by containing at least one polishing accelerator selected from a mixed acid of phosphoric acid-sulfuric acid-acetic acid and ferric chloride, an oxidizing agent, colloidal alumina, and water.

[0008] Still another polishing liquid according to the present invention is a polishing liquid for polishing W, which comprises at least one polishing accelerator selected from ferric chloride and ferric nitrate, an oxidizing agent, and colloidal alumina. And water.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a polishing liquid according to the present invention will be described in detail. This polishing liquid has a composition containing colloidal alumina and water. The colloidal aluna is obtained by, for example, dissolving aluminum alkoxide such as aluminum triisopropoxide in an organic solvent, adding pure water, hydrolyzing the solution, and drying. The obtained colloidal alumina and the conventionally used γ
X-ray diffraction diagram of alumina, shown in FIGS. 4 and 5, respectively.

[0010] The colloidal alumina is 0.02 to
It preferably has an average particle size of 0.1 μm and has a spherical or spherical shape. When the metal surface is polished with the polishing liquid containing such colloidal alumina, damage to the metal surface can be further suppressed.

The content of the colloidal alumina is 0.1.
The content is preferably set to 1 to 50% by weight. When the content of the colloidal alumina is less than 0.1% by weight, it is difficult to sufficiently achieve the effect. On the other hand, if the content of the colloidal alumina exceeds 50% by weight, the viscosity and the like of the polishing liquid become high, making it difficult to handle. The more preferable content of colloidal alumina is 1 to 20% by weight, and the more preferable content is 1 to 5% by weight.

The polishing liquid according to the present invention further comprises 1 to 10
Allows to contain colloidal silica by weight.
In order to polish a metal film formed on a substrate, for example, with the polishing liquid according to the present invention, a polishing apparatus shown in FIG. 1 is used. That is, the turntable 1 is covered with a polishing pad 2 made of cloth, for example. A supply pipe 3 for supplying a polishing liquid is disposed above the polishing pad 2. Substrate holder 5 having support shaft 4 on upper surface
Is disposed above the polishing pad 2 so as to be vertically movable and rotatable. In such a polishing apparatus,
The substrate 6 is held by the holder 5 so that the metal film side, which is the polished surface thereof, faces the pad 2.
While the polishing liquid 7 having the above-described composition is being supplied, the substrate 6 is given a desired weight toward the polishing pad 2 by the support shaft 4, and the holder 5 and the turntable 1 are rotated in opposite directions. By doing so, the metal film on the substrate is polished.

In order to form wiring of a semiconductor device using the polishing liquid according to the present invention, for example, the following method is employed. That is, a step of forming a groove and / or an opening corresponding to the shape of a wiring layer in an insulating film on a semiconductor substrate, and a wiring material made of Cu or a Cu alloy on the insulating film including the groove and / or the opening. Depositing a film, and polishing the wiring material film using a polishing liquid containing colloidal lunar and water until the surface of the insulating film is exposed, thereby forming an embedded wiring flush with the surface of the insulating film. Forming a layer.

The polishing liquid according to the present invention described above has a γ
-Since it contains colloidal alumina and water which are extremely softer than alumina, for example, when a metal film formed on a substrate is polished, the surface of the metal film can be polished at a practical level, and the metal surface can be damaged. Generation can be suppressed.

In particular, when the polishing liquid of the technique of coating a metal film on an insulating film having a groove on a semiconductor substrate and etching back the metal film using the polishing apparatus shown in FIG. The film can be polished flush with the insulating film, and the generation of scratches on the surface can be suppressed. as a result,
It is possible to form a highly reliable buried wiring that is free from scratches leading to disconnection in the insulating film.

The metal to be polished by the polishing liquid according to the present invention includes, for example, Cu, Cu alloy, Al, Al alloy,
W, Pt, Re and the like can be mentioned. In particular, Cu,
When polishing a metal film made of a Cu alloy, Al, an Al alloy, or W, it is preferable to use a composition containing various additives in addition to the following colloidal alumina.

1) Polishing liquid for copper-based metal This polishing liquid for copper-based metal contains 2-quinolinecarboxylic acid, oxidizing agent, colloidal alumina and water. With such a polishing liquid, the surface of the Cu or Cu alloy is not dissolved at all when the Cu or Cu alloy is immersed, and the Cu or Cu alloy can be polished at a practical rate during the polishing.

As the oxidizing agent, for example, hydrogen peroxide (H ₂ O ₂ ), sodium hypochlorite (NaClO) or the like can be used. It is preferable that the polishing liquid contains the 2-quinolinecarboxylic acid in an amount of 0.1% by weight or more, and the oxidizing agent is at least 10 times the weight of the 2-quinolinecarboxylic acid by weight. Thus, the 2-
The content of the quinoline carboxylic acid and the content ratio of the 2-quinoline carboxylic acid and the oxidizing agent are specified for the following reasons.

If the content of the 2-quinoline carboxylic acid is less than 0.1% by weight, the polishing rate of Cu or Cu alloy during polishing may decrease. More preferably, the content of the 2-quinolinecarboxylic acid is 0.3 to 1.2% by weight.

When the oxidizing agent is less than 10 times the weight of 2-quinolinecarboxylic acid by weight, the resulting polishing liquid and Cu
Alternatively, it may be difficult to form an altered layer (complex layer) that can be easily polished by a polishing treatment upon contact with a Cu alloy. More preferably, the content ratio of 2-quinoline carboxylic acid and oxidizing agent in the polishing liquid is 2-
The oxidizing agent is at least 30 times, more preferably at least 50 times, the quinoline carboxylic acid.

The content of the colloidal alumina is preferably set to 0.1 to 50% by weight for the same reason as described for the polishing liquid. The more preferable content of colloidal alumina is 1 to 20% by weight, and the more preferable content is 1 to 5% by weight.

The polishing liquid is allowed to further contain 1 to 10% by weight of colloidal silica. As the Cu alloy to be polished, for example, a Cu-Si alloy, C
A u-Al alloy, a Cu-Si-Al alloy, a Cu-Ag alloy, or the like can be used.

Since the above-mentioned polishing liquid for copper-based metal contains 2-quinoline carboxylic acid, oxidizing agent, colloidal alumina and water, the above-mentioned Cu or the like is not dissolved at all when Cu or Cu alloy is immersed. Cu or C
The u alloy can be polished at a practical rate while suppressing generation of scratches on the surface. Here, the practical polishing rate means that the polishing rate is 5 to 9 times that in the case of using the above-mentioned polishing liquid containing only colloidal alumina.

That is, 2-, which is a component of the polishing liquid,
Quinolinecarboxylic acid has the property of reacting with a hydrate of Cu (Cu ion) to form a complex that is hardly soluble in water, as shown in the following reaction formula.

Cu (H ₂ O) ₄ ²⁺ + 2C ₁₀ H ₇ NO ₂ →
The complex formed on the surface of Cu (C ₁₀ H ₆ NO ₂ ) ₂ + 4H ₂ O + 2H ²⁺ Cu or a Cu alloy is more fragile than Cu, and thus is easily polished by a polishing treatment with a polishing liquid containing colloidal alumina. Is done.

For example, as shown in FIG.
A Cu film 12 having irregularities is formed on
With a polishing liquid (2-quinoline carboxylic acid, colloidal alumina, colloidal silica and hydrogen peroxide, respectively.
3% by weight, 1.3% by weight, 4.0% by weight, and 16.7% by weight), the deteriorated layer (complex layer) is formed on the surface of the Cu film 12 as shown in FIG. 13 is generated. The surface of the Cu film immersed in the polishing liquid was analyzed by XPS (X-ray photoelectron spectroscopy). As a result, a large amount of carbon was detected on the surface of the Cu film, and only a small amount of Cu was detected. The thickness of the altered layer was examined by AES (Auger electron spectroscopy). As a result, the thickness of the altered layer was about 20 nm.

Then, using the polishing apparatus shown in FIG. 1 and the polishing liquid having the above-mentioned composition, the Cu film 12 having the altered layer 13 formed on the surface shown in FIG. 2B is polished in the presence of the polishing liquid. When polishing with a pad, the altered layer 13 corresponding to the convex portion of the Cu film 12 is mechanically and easily polished by the pad as shown in FIG. 2C, and pure Cu is exposed on the surface. When the Cu surface immediately after this polishing was analyzed by XPS (X-ray photoelectron spectroscopy), only Cu was detected and almost no oxidation was performed. That is, in the polishing process, C
While the altered layer is formed on the surface of the u film, the altered layer is mechanically removed (polished) with a polishing pad or the like, whereby the surface processing of the Cu film proceeds.

Therefore, the polishing liquid for copper-based metal is Cu
Alternatively, when immersing a metal film made of a Cu alloy,
The metal film can be polished at a practical rate (5 to 9 times as fast as the rate when a polishing liquid containing abrasive grains of colloidal alumina is used) during polishing without dissolving u or the like at all. Therefore, it is possible to avoid the problem that the etching amount of the copper-based metal fluctuates depending on the supply timing of the polishing liquid in the polishing process, and the operation can be performed easily.
Moreover, generation of scratches on the metal film surface of Cu or Cu alloy after polishing can be significantly suppressed.

When the Cu film on the substrate is polished by the polishing apparatus, the Cu film is polished only while the polishing pad is in contact (sliding contact) with a predetermined load. Since polishing is stopped immediately after leaving the Cu film, so-called over-etching, in which the Cu film is further etched after the polishing process, can be prevented.

Further, as shown in FIG. 2C, the Cu film 12 having irregularities is not etched from the side in the polishing step, and can be etched sequentially from the surface of the convex portion in contact with the polishing pad. This is extremely suitable for an etch-back technique described later. Moreover, although the above-mentioned altered layer (complex layer) is formed on the surface of the polished Cu film in contact with the polishing solution, the thickness is extremely thin at 20 nm. When the Cu surface is exposed, it is possible to prevent the Cu film from being excessively reduced.

2) Polishing solution for aluminum-based metal This polishing solution for aluminum-based metal comprises at least one polishing accelerator selected from trimethylammonium hydroxide, trimethyl hydroxide, a mixed acid of phosphoric acid-sulfuric acid-acetic acid, and ferric chloride. The composition has a composition containing an agent, an oxidizing agent, colloidal alumina, and water.

As the oxidizing agent, for example, hydrogen peroxide (H ₂ O ₂ ), sodium hypochlorite (NaClO) and the like can be used. The polishing liquid contains 5 parts of the polishing accelerator.
It is preferable that the oxidizing agent be contained in an amount of at least 10% by weight with respect to the polishing accelerator by weight.

The content of the colloidal alumina is preferably set to 0.1 to 50% by weight for the same reason as described for the polishing liquid. The more preferable content of colloidal alumina is 1 to 20% by weight, and the more preferable content is 1 to 5% by weight.

The polishing liquid is allowed to further contain 1 to 10% by weight of colloidal silica. As the Al alloy to be polished, for example, an Al-Si alloy, A
An l-Cu-Si alloy or the like can be used.

The above-mentioned polishing liquid for aluminum-based metals is as follows:
Since it contains at least one polishing accelerator selected from trimethylammonium hydroxide, trimethyl hydroxide, a mixed acid of phosphoric acid-sulfuric acid-acetic acid, and ferric chloride, an oxidizing agent, colloidal alumina, and water, In the above, the polishing accelerator and the oxidizing agent chemically act on the surface of the Al or Al alloy to dissolve and the colloidal alumina performs a mechanical polishing action, so that the surface of the Al or Al alloy can be put to practical use. Can be polished at a specific speed. Here, the practical polishing rate means that the polishing rate is about 10 to 20 times that in the case of using the above-mentioned polishing liquid containing only colloidal alumina. Further, generation of scratches on the surface of the Al or Al alloy can be suppressed.

Therefore, the above-mentioned polishing liquid for aluminum-based metals uses a polishing liquid containing a polishing abrasive of colloidal alumina while suppressing the generation of scratches on the surface of a metal film made of Al or an Al alloy. (About 10 to 20 times as fast as the case), and the Al of the semiconductor device can be polished.
Alternatively, it can be effectively used for forming an embedded wiring made of an Al alloy.

3) Polishing liquid for tungsten This polishing liquid for tungsten has a composition containing at least one polishing accelerator selected from ferric chloride and ferric nitrate, an oxidizing agent, colloidal alumina, and water. Have.

As the oxidizing agent, for example, potassium ferrocyanide, hydrogen peroxide (H ₂ O ₂ ) and the like can be used. The polishing liquid contains 0.1% by weight of the polishing accelerator.
It is preferable that the oxidizing agent is contained in an amount equal to or more than 0.5 times the polishing accelerator in a weight ratio.

The content of the colloidal alumina is preferably set to 0.04 to 20% by weight for the same reason as described for the polishing liquid. A more preferred content of colloidal alumina is 0.04 to 5% by weight.

The polishing liquid may further contain 0.1 to 15% by weight.
Of colloidal silica. Since the above-mentioned polishing slurry for tungsten contains at least one polishing accelerator selected from ferric chloride and ferric nitrate, an oxidizing agent, colloidal alumina, and water, the surface of W is polished during polishing. The surface of the W can be polished at a practical rate by the dissolution of the polishing accelerator and the oxidizing agent due to the chemical action and the mechanical polishing action of the colloidal alumina. Here, the practical polishing rate means that the polishing rate is about 10 to 20 times that in the case of using the above-mentioned polishing liquid containing only colloidal alumina. Further, generation of scratches on the surface of the W can be suppressed.

Therefore, the tungsten polishing liquid can be used at a practical speed while suppressing the generation of scratches on the surface of the metal film made of W (10 to 20 when a polishing liquid containing abrasive grains of colloidal alumina is used). The polishing can be performed at twice or more speed), and it can be effectively used for forming a buried wiring made of W in a semiconductor device.

[0042]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings. (Example 1) First, a Cu film was deposited on a substrate by sputtering deposition. Subsequently, the substrate is held on the substrate holder 5 of the polishing apparatus shown in FIG. 1 so that the deposited Cu film faces the polishing pad 2, and the support shaft 4 of the holder 5 holds the substrate on the turntable 1. A load of 500 g / cm ² was applied to the polishing pad 2 made of Rodel Nitta above; IC1000 / SUBA400,
Each of the turntable 1 and the holder 5 is 100
The polishing liquid is supplied to the polishing pad 2 from the supply pipe 3 at a speed of 20 ml / min while rotating in the opposite directions at a speed of 103 rpm and at a speed of 103 rpm, and the C deposited on the substrate 21.
The u film was polished. Here, the polishing liquid used was pure water containing 1.2% by weight of colloidal alumina having a primary particle diameter of 20 nm.

The polishing rate of the Cu film in the polishing step was measured. As a result, it was 5 nm / min. The surface of the polished Cu film was observed with an optical microscope. As a result, generation of a scratch having a depth of 20 nm or more in a dark field of 500 times was not observed.

Example 2 First, a Cu film was deposited on a substrate by sputtering deposition. The substrate is held on the substrate holder 5 of the polishing apparatus shown in FIG. 1 so that the deposited Cu film faces the polishing pad 2, and the support shaft 4 of the holder 5 holds the substrate on the turntable 1.
300 g / cm ² is applied to the polishing pad 2 made of Nitta Corporation; IC1000 / SUBA400, while the turntable 1 and the holder 5 are rotated in opposite directions at a speed of 100 rpm and 103 rpm, respectively. Was supplied from the supply pipe 3 to the polishing pad 2 at a rate of 20 ml / min to polish the Cu film deposited on the substrate 21. Here, the polishing liquid is 2-
Pure water containing 0.6% by weight of quinoline carboxylic acid, 13% by weight of hydrogen peroxide, 1.2% by weight of colloidal alumina having a primary particle diameter of 20 nm and 4.4% by weight of colloidal silica was used.

Comparative Example 1 0.6% by weight of 2-quinoline carboxylic acid, 13% by weight of hydrogen peroxide, 1.2% by weight of γ-alumina having a primary particle diameter of 30 nm and 4.4% by weight of colloidal silica as a polishing liquid The Cu film was polished by the same method as in Example 1 except that pure water containing Cu was used.

The polishing rates of the Cu film in the polishing steps of Example 2 and Comparative Example 1 were measured. As a result, the polishing rate of the Cu film of Example 2 was 42 nm / min, and the polishing rate of the Cu film of Comparative Example 1 was 50 nm / min.

The polishing process according to Example 2 and Comparative Example 1 was performed using a scratch evaluation device (trade name: Surfscan 6420, manufactured by Tencor Corporation) provided with a microscope function for counting only the number of scratches from the scattering caused by the irradiation of the laser beam. The number of scratches of 0.2 μm or less existing in a 1 mm square visual field on the Cu surface of the subsequent substrate was measured at 50 locations. As a result, in the case of Comparative Example 1, the number of scratches in 50 places (total of 50 places) was 148, whereas in the case of Example 2, the number of scratches in 50 places was 4.

Therefore, the polishing liquid of Example 2 using colloidal alumina as the polishing abrasive was γ
-Although the polishing rate of the Cu film is slightly inferior to that of the polishing liquid of Comparative Example 1 using alumina, it can be seen that the occurrence of scratches on the Cu film leading to disconnection is significantly reduced as compared with Comparative Example 1.

Example 3 First, an Al film was deposited on a substrate by sputtering deposition. An Al film deposited on a substrate holder 5 of the polishing apparatus shown in FIG. 1 is held so as to face the polishing pad 2, and the support shaft 4 of the holder 5 holds the substrate on the turntable 1.
300 g / cm ² is applied to the polishing pad 2 made of Nitta Corporation; IC1000 / SUBA400, while the turntable 1 and the holder 5 are rotated in opposite directions at a speed of 100 rpm and 103 rpm, respectively. Was supplied from the supply pipe 3 to the polishing pad 2 at a rate of 20 ml / min to polish the Cu film deposited on the substrate 21. Here, the polishing liquid used was composed of pure water containing 1.29% by weight of trimethylammonium hydroxide, 0.5% by weight of hydrogen peroxide and 4% by weight of colloidal alumina having a primary particle diameter of 20 nm.

The polishing rate of the Al film in the polishing step was measured. As a result, it was 70 nm / min. The surface of the polished Al film was observed with an optical microscope. as a result,
No generation of a scratch having a depth of 20 nm or more was observed at a dark field of 500 times.

Embodiment 4 First, a W film was deposited on a substrate by sputtering. The W film deposited on the substrate holder 5 of the polishing apparatus shown in FIG. 1 is held so as to face the polishing pad 2, and the support shaft 4 of the holder 5 is provided.
By applying a load of 300 g / cm ² to the polishing pad 2 made of Rodel-Nitta on the turntable 1 with a trade name of IC1000 / SUBA400, the turntable 1 and the holder 5 were respectively
A polishing liquid was supplied from the supply pipe 3 to the polishing pad 2 at a rate of 20 ml / min while rotating in the opposite directions at a speed of 0 rpm and 103 rpm to polish the W film deposited on the substrate 21. Here, as the polishing liquid, 0.1% by weight of ferric chloride, 4% by weight of hydrogen peroxide and a primary particle diameter of 2% were used.
A pure water containing 0.07% by weight of 0 nm colloidal alumina was used.

The polishing rate of the W film in the polishing step was measured. As a result, it was 50 nm / min. The surface of the W film after polishing was observed with an optical microscope. As a result, generation of a scratch having a depth of 20 nm or more in a dark field of 500 times was not observed.

(Embodiment 5) First, as shown in FIG. 3A, on a silicon substrate 21 having a diffusion layer such as a source and a drain (not shown) formed on the surface thereof, for example, a thick film as an interlayer insulating film is formed by a CVD method. after depositing the SiO ₂ film 22 of 1000nm is, the depth 500nm having a shape corresponding to the wiring layer by photoetching technique on the SiO ₂ film 22
Are formed. Subsequently, as shown in FIG. 3B, a barrier layer 24 made of TiN having a thickness of 15 nm and a Cu film 25 having a thickness of 600 nm are formed in this order on the SiO ₂ film 22 including the groove 23 by sputter deposition. Deposited.

Next, the substrate 21 shown in FIG. 3B is held on the substrate holder 5 of the polishing apparatus shown in FIG. 1 so that the wiring forming surface faces the polishing pad 2, and the support shaft of the holder 5 is supported. 4 and the substrate on the turntable 1 by trade name of Rodel-Nitta; IC1000 / SUB
A polishing pad 2 made of A400 is given a load of 300 g / cm ² , and while the turntable 1 and the holder 5 are rotated in directions opposite to each other at a speed of 100 rpm and 103 rpm, a polishing liquid is supplied from the supply pipe 3 at a rate of 20 ml / cm ^2.
Wherein the min Cu film 25 and the barrier layer 24 is supplied to the polishing pad 2 was deposited on the substrate 21 of SiO ₂
Polishing was performed until the surface of the film 22 was exposed. Here, as the polishing liquid, pure water containing 0.6% by weight of 2-quinolinecarboxylic acid, 13% by weight of hydrogen peroxide, 1.2% by weight of colloidal alumina having a primary particle diameter of 20 nm, and 4.4% by weight of colloidal silica is used. Was used. In the polishing step, the polishing liquid did not undergo any etching at the time of contact with the Cu film, and the polishing rate at the time of polishing with the polishing pad was about 80 nm / min. For this reason, in the polishing step, the convex Cu film 25 shown in FIG. 3B is preferentially polished from the surface that is in mechanical contact with the polishing pad,
Further, so-called etch back in which the exposed barrier layer 24 is polished was performed. As a result, FIG.
As shown in FIG. 3, the barrier layer 24 remains only in the groove 23 and the buried Cu wiring layer 26 is flush with the surface of the SiO ₂ film 22 in the groove 23 covered with the barrier layer 24.
Was formed.

The load on the polishing pad 2 by the holder 5 of the polishing apparatus is released, and the turntable 1
And after the rotation of the holder 5 is stopped, the Cu
Etching did not proceed even when the wiring layer 26 was brought into contact with the polishing liquid.

[0056]

As described above, according to the present invention, the metal film can be polished and the generation of scratches on the surface can be suppressed, and when applied to the etch-back technique in the wiring forming process of a semiconductor device, the reliability without disconnection can be improved. It is possible to provide a polishing liquid capable of forming a highly embedded wiring.

Further, according to the present invention, a metal film made of Cu or the like can be polished at a practical level and the generation of scratches on the surface can be suppressed. Further, it is possible to provide a polishing liquid capable of forming a highly reliable embedded wiring without disconnection in a short time.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a polishing apparatus used in a polishing step of the present invention.

FIG. 2 is a cross-sectional view showing a state in which a Cu film having irregularities is immersed in a polishing liquid having a composition composed of 2-quinoline carboxylic acid, hydrogen peroxide, abrasive grains and water, and is polished using a polishing apparatus. FIG.

FIG. 3 is a sectional view showing a manufacturing step of a semiconductor device according to a fifth embodiment of the present invention.

FIG. 4 is an X-ray diffraction diagram of colloidal alumina.

FIG. 5 is an X-ray diffraction diagram of γ-alumina.

[Explanation of symbols]

1 ... turntable 2 ... polishing pad, 3 ... supply pipe, 5 ... holder, 11, 21 ... silicon substrate, 12, 25 ... Cu film, 13 ... oxide layer, 22 ... SiO ₂ film, 23 ... groove, 24 ... Barrier layer, 26 ... Cu wiring layer.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI H05K 3/10 H05K 3/10 E (72) Inventor Shunpei 5-36-2 Kamata, Ota-ku, Tokyo Inside Tama Chemical Company

Claims (4)

[Claims] 1. A polishing liquid comprising colloidal alumina and water. 2. A polishing liquid for polishing Cu or a Cu alloy, which comprises 2-quinolinecarboxylic acid, an oxidizing agent, colloidal alumina and water. 3. A polishing liquid for polishing Al or an Al alloy, comprising at least one polishing accelerator selected from the group consisting of trimethylammonium hydroxide, trimethyl hydroxide, a mixed acid of phosphoric acid-sulfuric acid-acetic acid, and ferric chloride. ,
A polishing liquid comprising an oxidizing agent, colloidal alumina, and water. 4. A polishing liquid for polishing W, comprising at least one polishing accelerator selected from ferric chloride and ferric nitrate, an oxidizing agent, colloidal alumina, and water. Polishing liquid.