JPH07233485A - Polishing liquid for copper metal and production of semiconductor device - Google Patents

Abstract

PURPOSE:To develop a polishing liquid which is largely different in etching rate at the time of immersion into the liquid and at the time of a polishing treatment by using an aq. soln. having a specific org. acid, oxidizing agent and polishing abrasive grains as the polishing liquid for copper metals. CONSTITUTION:The surface of a turn table 1 is coated with a polishing pad 2 made of cloth and an Si substrate 6 is supported thereon by a substrate holder 5 in such a manner that the surface to be polished thereof faces the pad 2. A semiconductor is then produced by using a polishing device composed of a revolving and supporting shaft mounted at the holder. At this time, the water-soluble polishing liquid 7 which contains 0.01 to 10wt.% at least one kind of org. acid selected between an amino acetic acid and amide sulfuric acid, contains an oxide, such as H2O2 at >=20 parts per 1 part org. acid, contains 1 to 14wt.% polishing abrasive grains having an average grain size of 0.02 to 0.1mum and is adjusted to pH value of 9 to 14 by an alkali is dropped onto the surface of a copper film 12 having ruggedness on the si substrate 11 from a supply pipe 3 to immerse the substrate 6. The oxides 13 in the projecting parts exclusive of the groove parts are polished away by rotating a supporting shaft 4 while pressing down the shaft, by which a wiring board consisting of the copper film 12 is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copper-based metal polishing liquid and a method for manufacturing a semiconductor device.

[0002]

2. Description of the Related Art Electrochem. So
c. , VoL. 138. No11, 3460 (199
1), VMIC Conference, ISMIC-
101/92/0156 (1992) or VMIC
Conference, ISMIC-102 / 93/0
205 (1993), a slurry of amine colloidal silica or K ₃ Fe (CN) ₆ , K ₄ (CN) ₆ ,
A polishing liquid for a Cu film or a Cu alloy film made of a slurry to which Co (NO ₃ ) ₂ is added is disclosed.

However, since the polishing liquid has no difference in the dissolution rate of the Cu film between the immersion and the polishing, the following problems occur. In forming a wiring layer, which is one of the manufacturing steps of a semiconductor device, an etch-back technique is adopted for the purpose of eliminating a surface step. In this etchback technique, a groove is formed in an insulating film on a semiconductor substrate, a Cu film is deposited on the insulating film including the groove, and the Cu film is polished using a polishing liquid so that only the inside of the groove is formed. This is a method of forming a buried wiring layer by leaving the Cu film left behind. After such an etch-back step, the Cu wiring layer in the groove is brought into contact with the polishing liquid, so that the polishing liquid having the above-mentioned composition, which has no difference in the etching rate of the Cu film between the immersion and the polishing, is used. When used, the Cu wiring layer is further etched by the polishing liquid. As a result, the surface position of the Cu wiring layer in the groove becomes lower than the surface of the insulating film, so that it becomes difficult to form a wiring layer flush with the surface of the insulating film, and flatness is impaired. Further, the formed buried Cu wiring layer has a higher resistance value than the Cu wiring layer buried flush with the surface of the insulating film.

[0004]

The object of the present invention is to etch Cu (Cu) or a copper alloy (Cu alloy) hardly when it is immersed, and to dissolve the Cu or Cu alloy during polishing. Then, it is intended to provide a polishing liquid for copper-based metals, which shows a difference in etching rate of several times to several tens of times between immersion and polishing.

Another object of the present invention is to form a groove and / or an opening in an insulating film on a semiconductor substrate and to form a wiring made of copper (Cu) or a copper alloy (Cu alloy) deposited on the insulating film. An object of the present invention is to provide a method for manufacturing a semiconductor device, which can etch back a material film in a short time and form a buried wiring layer flush with the surface of an insulating film.

Still another object of the present invention is to form a groove and / or an opening in an insulating film on a semiconductor substrate and form a wiring material film made of Cu or Cu alloy on the insulating film in a short time. To provide a method for manufacturing a semiconductor device capable of forming a buried wiring layer flush with an insulating film surface by etching back, and further capable of satisfactorily cleaning the insulating film surface and the like after etching back. It is a thing.

[0007]

The polishing solution for copper-based metals according to the present invention contains at least one organic acid selected from aminoacetic acid and amidosulfuric acid, an oxidizing agent and water. Such a polishing liquid forms an oxide layer functioning as an etching barrier on the surface of the Cu or Cu alloy by the oxidizing action of the oxidizing agent during immersion of Cu or Cu alloy, and when polishing Cu or Cu alloy. The exposed Cu or Cu alloy by mechanically removing the oxide layer is etched with the organic acid. Therefore, when Cu or Cu alloy is immersed in the polishing liquid, etching is suppressed or prevented by the oxide layer, and Cu or Cu alloy exposed during polishing is physically polished and etched by the organic acid in the polishing liquid. Progresses. As a result, it becomes possible to make a sufficiently large difference in etching rate of Cu or Cu alloy between the time of immersion and the time of polishing.

As the oxidizing agent, for example, hydrogen peroxide (H ₂ O ₂ ) or sodium hypochlorite (NaClO) can be used. The polishing liquid contains 0.0% of the organic acid.
It is preferable that the content of the oxidizing agent be 1 to 10% by weight, and the weight ratio of the oxidizing agent to the organic acid is 20 or more. The reason for defining the content of the organic acid and the content ratio of the organic acid and the oxidizing agent in the polishing liquid is as follows.

When the content of the organic acid is less than 0.01% by weight, the polishing rate (mainly the chemical dissolution rate) of Cu or Cu alloy during polishing may decrease. On the other hand, if the content of the organic acid exceeds 10% by weight, the etching of Cu or Cu alloy may proceed excessively when immersed in a polishing liquid, and the etching rate difference between the immersion and the polishing may be similar. There is. The more preferable content of the organic acid is 0.01 to 1% by weight.

20 weight ratio of oxidizer to 1 organic acid
If the amount is less than the range, there is a fear that a sufficient etching rate difference cannot be obtained between the time of dipping Cu or Cu alloy and the time of polishing. The content ratio of the organic acid and the oxidant in the polishing liquid is preferably 40 or more, more preferably 100 or more with respect to 1 organic acid by weight.

The upper limit ratio of the oxidizing agent to the organic acid is preferably defined by the content of the oxidizing agent, and for example, the content of the oxidizing agent is preferably 30% by weight. If the content of the oxidizing agent exceeds 30% by weight, Cu
Alternatively, there is a possibility that an oxide layer is immediately formed on the exposed surface of the Cu alloy during polishing, resulting in a decrease in the polishing rate.

When the content of the organic acid is set to the lower limit value (0.01% by weight) within the above range, the content ratio of the organic acid and the oxidizing agent is 1 by weight with respect to 1 organic acid. Therefore, it is preferable that the oxidizing agent is 40 or more.

The polishing liquid according to the present invention is allowed to contain, in addition to the organic acid and the oxidizing agent, an alkaline agent for adjusting the pH to 9-14. As such an alkaline agent, for example, potassium hydroxide and quinoline are suitable.

The polishing liquid according to the present invention allows addition of polishing abrasives such as silica particles, alumina particles, cerium oxide particles, and zirconia particles in addition to the organic acid and the oxidizing agent. These polishing abrasive grains may be used in the form of a mixture of two or more kinds.

The abrasive grains preferably have an average particle size of 0.02 to 0.1 μm. The abrasive grains are 1
It is preferable to add -14% by weight. If the amount of the abrasive grains added is less than 1% by weight, it becomes difficult to achieve the effect sufficiently. On the other hand, if the amount of the abrasive grains added exceeds 14% by weight, the viscosity of the polishing liquid increases and it becomes difficult to handle. The more preferable amount of abrasive grains added is 3
It is in the range of 10% by weight.

The polishing apparatus shown in FIG. 1 is used to polish a Cu film or a Cu alloy film formed on a substrate, for example, with the copper-based metal polishing liquid according to the present invention. That is, the turntable 1 is covered with a polishing pad 2 made of, for example, cloth. A supply pipe 3 for supplying a polishing liquid is arranged above the polishing pad 2. The substrate holder 5 having the support shaft 4 on the upper surface is arranged above the polishing pad 2 so as to be vertically movable and rotatable. In such a polishing apparatus, the holder 5
Holds the substrate 6 so that its polishing surface (eg, Cu film) faces the pad 2, and while the polishing liquid 7 having the above-described composition is supplied from the supply pipe 3, the substrate 6 is supported by the support shaft 4. A desired weight is applied to the polishing pad 2, and the holder 5 and the turntable 1 are rotated in opposite directions to each other, so that C on the substrate is
The u film is polished.

The copper-based metal-polishing liquid according to the present invention described above contains at least one organic acid selected from aminoacetic acid and amidosulfuric acid, an oxidizing agent, and water.
Cu or the like is hardly etched when u or Cu alloy is immersed (preferably an etching rate of 100 nm / min or less), and an etching rate difference of several times to several tens of times between immersion and polishing is exhibited. .

That is, the organic acid (for example, aminoacetic acid) which is one component of the polishing liquid is C as shown in the following reaction formula.
It has a property of reacting with a hydrate of u to form a complex. Cu (H ₂ O) ₄ ²⁺ + 2H ₂ NCH ₂ COOH → Cu
(H ₂ NCH ₂ COOH) ₂ + 4H ₂ O + 2H ⁺ Cu does not react with the mixed solution of aminoacetic acid and water. In such a reaction system, by adding an oxidizing agent (for example, hydrogen peroxide), the reaction proceeds in the direction shown by the arrow in the above reaction formula, and Cu is etched.

FIG. 2 shows that when the content of aminoacetic acid in the polishing liquid consisting of aminoacetic acid, hydrogen peroxide and water was kept constant at 0.1% by weight, the content of hydrogen peroxide was varied on the substrate. It is a plot of the etching rate during immersion of the formed Cu film and the polishing rate during polishing treatment. The polishing process is performed using the polishing device shown in FIG. That is, the substrate with the Cu film formed on the substrate holder 5 is held upside down so that the Cu film faces the polishing pad 2 side made of, for example, a product name of SUBA800 manufactured by Rodel-Nitta Co., and is supported by the support shaft 4. The substrate is applied to the polishing pad 2 with a weight of 400 g / cm ² ,
Further, while rotating the turntable 1 and the holder 5 in opposite directions at a speed of 100 rpm, respectively, a polishing liquid is supplied from the supply pipe 3 to the polishing pad 2 at a speed of 12.5 ml / min to perform a polishing process. It was

As is apparent from FIG. 2, when the Cu film is dipped, when the polishing liquid containing no hydrogen peroxide is used, the Cu film is not etched at all. It can be seen that the film is rapidly etched. This is because the hydrate of Cu is generated by hydrogen peroxide in the polishing liquid, and aminoacetic acid reacts with this to form a complex to etch Cu. Further, it can be seen that when the content of hydrogen peroxide is further increased, the etching rate of the Cu film becomes slow, and when the content of hydrogen peroxide becomes 5% by weight, the etching rate becomes zero. It is considered that this is because when the content of hydrogen peroxide is increased, an oxide layer is formed on the surface of the Cu film that hinders etching by the polishing liquid.

In fact, as shown in FIG.
A Cu film 12 having irregularities is formed on the substrate 11, and the substrate 11 is immersed in a polishing liquid (containing 0.1% by weight of aminoacetic acid and 13% by weight of hydrogen peroxide) having a slow etching rate for 3 minutes. When immersed, C as shown in FIG.
An oxide layer 13 is formed on the surface of the u film 12. After dipping the substrate in the polishing liquid, the surface of the Cu film is treated with XPS (X-
Ray photoelectron spectroscopy)
From the appearance of the spectrum shown by the solid line, it was confirmed that an oxide layer was generated. The dotted line in FIG. 4 shows the spectrum before processing immediately after the Cu film was formed on the substrate.

When the above-mentioned polishing treatment is carried out using the polishing apparatus shown in FIG. 1 and a polishing liquid containing 0.1% by weight of aminoacetic acid and 13% by weight of hydrogen peroxide, the Cu film is polished as shown in FIG. The speed is about 10 nm compared to when immersed
It was confirmed that there was a difference of / minute. The increase in the polishing rate of the Cu film due to such polishing treatment is caused by the Cu film 12 having the oxide layer 13 shown in FIG.
Is polished with a polishing pad in which the polishing liquid is present, as shown in FIG.
(C), the oxide layer 13 corresponding to the convex portion of the Cu film 12 is mechanically polished by the pad to expose pure Cu on the surface, and the action of aminoacetic acid and hydrogen peroxide in the polishing liquid is exerted. This is because the chemical polishing is rapidly performed.
That is, in the polishing process, pure Cu is always applied to the polished surface of the Cu film.
Is exposed and is chemically etched by aminoacetic acid and hydrogen peroxide in the polishing liquid. In fact, when the Cu film surface immediately after the polishing treatment was analyzed by XPS, the spectrum indicated by the alternate long and short dash line in FIG. 4 appeared, and it was confirmed that Cu was exposed.

Further, FIG. 5 shows that the content of aminoacetic acid in the polishing liquid consisting of aminoacetic acid, hydrogen peroxide and water was 0.
9 is a plot of the etching rate during immersion of a Cu film formed on a substrate and the polishing rate during polishing when the content of hydrogen peroxide was changed, with the content being constant at 9% by weight. The polishing process was performed using the polishing apparatus shown in FIG. 1 in the same procedure as described above. As is clear from FIG. 5, when the Cu film is dipped, when the polishing liquid containing no hydrogen peroxide is used, the Cu film is not etched at all, but when a small amount of hydrogen peroxide is contained, C
It can be seen that the u film is rapidly etched. Further, it can be seen that when the content of hydrogen peroxide is further increased, the etching rate of the Cu film becomes slow, and when the content of hydrogen peroxide becomes about 18% by weight, the etching rate becomes zero.
It is considered that this is because when the content of hydrogen peroxide is increased, an oxide layer is formed on the surface of the Cu film that hinders etching by the polishing liquid. When such a polishing liquid containing 15% by weight of hydrogen peroxide is used to polish the Cu film by the same method as described above, the Cu film is polished at a rate of about 85 nm / min, and when it is immersed. And a sufficient etching rate difference occurs between the polishing process and the polishing process. However, a polishing liquid containing 20% by weight of hydrogen peroxide, which is a condition under which the Cu film is not reliably etched during immersion,
That is, even in a polishing solution in which the content ratio of aminoacetic acid and hydrogen peroxide is about 20 by weight relative to 1 aminoacetic acid, the polishing rate at the time of polishing the Cu film is about 6
It becomes 0 nm / min. Therefore, even when the polishing liquid containing a large amount of hydrogen peroxide is used, a sufficient etching rate difference can be obtained between the immersion and the polishing treatment.

Further, FIG. 6 shows amidosulfuric acid which is an organic acid,
When the content of amido-sulfuric acid in the polishing liquid consisting of hydrogen peroxide and water was kept constant at 0.86% by weight and the content of hydrogen peroxide was changed, the Cu film formed on the substrate was immersed. It is a plot of the etching rate and the polishing rate during polishing. The polishing process was performed using the polishing apparatus shown in FIG. 1 in the same procedure as described above. As is clear from FIG. 6, the Cu film is not etched at all when the polishing liquid containing no hydrogen peroxide is used, but the Cu film is rapidly etched when a small amount of hydrogen peroxide is contained. . Further, it can be seen that when the content of hydrogen peroxide is further increased, the etching rate of the Cu film becomes slow, and when the content of hydrogen peroxide becomes about 22% by weight or more, the etching rate becomes 50 nm / min. It is considered that this is because when the content of hydrogen peroxide is increased, an oxide layer is formed on the surface of the Cu film that hinders etching by the polishing liquid. In such a polishing liquid, one containing 30% by weight of hydrogen peroxide, that is, a polishing liquid in which the content ratio of amidosulfuric acid and hydrogen peroxide is about 35 hydrogen peroxide to 1 aminoacetic acid is used. When the Cu film is polished by the same method as described above,
The Cu film is polished at a rate of about 950 nm / min, and the difference in etching rate between immersion and polishing is about 19 times, which is sufficiently large.

Therefore, the polishing liquid according to the present invention is Cu
Alternatively, the Cu or Cu alloy is hardly etched during immersion of the Cu alloy, and the etching rate difference between the immersion time and the polishing time is several to several tens of times. For this reason, in the polishing process step, C
The problem that the etching amount of u varies and the like can be avoided, and the operation can be performed easily. Further, after the polishing of the Cu film on the substrate by the polishing apparatus is completed, when the Cu film is brought into contact with a polishing liquid, an oxide layer is formed on the Cu film by hydrogen peroxide as described above, and thus the polishing is performed. The Cu film is further etched even after the treatment,
So-called over-etching can be prevented.
Further, as shown in FIG. 3C, the Cu film 12 having irregularities is not etched from the side surface in the polishing step, and can be sequentially etched from the surface of the convex portion contacting the polishing pad, which will be described later. Very suitable for etch back technology.

In the polishing liquid according to the present invention, when an alkali agent such as potassium hydroxide is added to adjust the pH to 9 to 14, when Cu or Cu alloy is dipped in the polishing liquid, Cu or Cu alloy An oxide layer having an excellent etching barrier property against the polishing liquid can be formed on the surface.
In addition, the thickness of the oxide layer formed on the surface of Cu or Cu alloy can be controlled. FIG. 7 shows Cu deposited on a substrate in a polishing liquid containing, for example, 0.9% by weight of aminoacetic acid and 12% by weight of hydrogen peroxide, and adjusting pH to 8.5 to 11 by adding potassium hydroxide. Cu when the film is immersed
It is a characteristic view which shows the thickness change of the oxide layer produced | generated on the film surface. As shown in FIG. 7, as the pH increases, Cu
The thickness of the oxide layer formed on the film surface becomes thicker.

Such a polishing liquid having a pH adjusted to 9 to 14 can form an oxide layer having a high etching barrier property on the surface of the Cu or Cu alloy when immersed in Cu or Cu alloy. Therefore, even if the content of the organic acid such as aminoacetic acid in the polishing liquid is increased, Cu or the like is hardly etched during immersion of Cu or Cu alloy, while the content of the organic acid is contained during polishing. By increasing the amount, the polishing rate of Cu or Cu alloy can be increased. Therefore, the etching rate difference between the immersion time and the polishing time can be increased as compared with the case where no alkali agent is added, and as a result, the polishing time for Cu or Cu alloy can be shortened.

By adding polishing abrasives such as silica particles to the polishing liquid according to the present invention, the polishing rate at the time of polishing Cu or Cu alloy can be improved as compared with the polishing liquid in which the polishing abrasives are not added. . For example, in an aqueous solution containing 0.1% by weight of aminoacetic acid and 13% by weight of hydrogen peroxide, silica particles having an average particle size of 30 nm and an average particle size of 740 nm are used.
About 9% by weight of alumina particles, cerium oxide particles having an average particle diameter of 1300 nm, and zirconia particles having an average particle diameter of 1100 nm were added to prepare a polishing liquid. These polishing liquids were formed on the substrate by the same procedure as described above using the polishing apparatus shown in FIG.
The film was polished. The Cu film polishing rate by each polishing solution is shown in Table 1 below. In Table 1 below, 0.1% by weight of aminoacetic acid and 1% of hydrogen peroxide to which abrasive grains were not added
The polishing rate of the Cu film when using the polishing liquid containing 3% by weight is also shown.

[0029]

[Table 1]

As can be seen from Table 1 above, the polishing liquid containing the polishing abrasive grains can improve the polishing rate of the Cu film as compared with the polishing liquid containing no polishing grains. Further, it is understood that the polishing rate of the Cu film can be controlled by changing the type of polishing abrasive grains.

Further, the silica particles and alumina particles added abrasive liquid is deposited on the substrate by the same procedure as described above with reference to polishing apparatus shown in FIG. 1 to the SiO ₂ film as the abrasive grains, respectively, Si _{The 3} N ₄ film and the boron-added glass film (BPSG film) were polished. Table 2 below shows polishing rates of various insulating films by each polishing liquid. The values in parentheses in Table 2 are speed ratios calculated from (polishing speed of Cu film / polishing speed of each insulating film in the same polishing liquid). When a buried Cu wiring layer is formed in a groove of an insulating film by polishing during the manufacturing of a semiconductor device described later, the Cu content increases as the speed ratio increases.
It is possible to improve the selective policing property of. That is, it is possible to suppress film loss of the underlying insulating film.

[0032]

[Table 2]

Further, the polishing liquid to which polishing abrasive grains such as silica particles are added can be satisfactorily polished without causing cracks or fine scratches on the Cu film or Cu alloy film. This is because in the polishing process using the polishing apparatus shown in FIG. 1, the frictional force between the polishing surface of the Cu film and the polishing pad can be alleviated by the abrasive grains, and the impact force on the Cu film is reduced to cause cracking or the like. This is because it is possible to prevent

Therefore, the polishing liquid to which the polishing particles such as silica particles are added can improve the polishing rate of Cu or Cu alloy as compared with the polishing liquid to which the polishing particles are not added, and the Cu or Cu alloy during the polishing process. The damage to the surface can be suppressed.

Even in a polishing liquid containing an abrasive such as silica particles, the organic acid is amido-sulfuric acid, the polishing rate of Cu or Cu alloy can be improved and the polishing speed can be improved as compared with the polishing liquid not containing the abrasive grains. C during processing
Damage to the u or Cu alloy surface can be suppressed.

A method of manufacturing a semiconductor device according to the present invention is
A step of forming a groove and / or an opening corresponding to the shape of the wiring layer in the insulating film on the semiconductor substrate; and a wiring material film made of Cu or a Cu alloy on the insulating film including the groove and / or the opening. The step of depositing and polishing the wiring material film with a polishing liquid containing at least one organic acid selected from aminoacetic acid and amidosulfuric acid, an oxidizing agent and water until the surface of the insulating film is exposed. Thus, a step of forming a buried wiring layer flush with the surface of the insulating film is provided.

As the insulating film, for example, a silicon oxide film, a silicon nitride film, a two-layer film of a silicon oxide film and a silicon nitride film laminated thereon, a boron-added glass film (B
A PSG film), a phosphorus-containing glass film (PSG film), or the like can be used.

As the Cu alloy, for example, Cu--Si
Alloy, Cu-Al alloy, Cu-Si-Al alloy, Cu-
Ag alloy or the like can be used. Cu or Cu
The wiring material film made of an alloy is deposited by sputtering deposition, vacuum deposition, or the like.

The content of the organic acid in the polishing liquid and the content ratio of the organic acid and the oxidizing agent are preferably in the same range as the above-mentioned polishing liquid for copper-based metal. The polishing liquid has a pH of 9 to 14 in addition to the organic acid and the oxidizing agent.
It is permissible to include an alkaline agent adjusted to. As such an alkaline agent, for example, potassium hydroxide and quinoline are suitable.

The polishing liquid is allowed to contain polishing particles such as silica particles, alumina particles, cerium oxide particles and zirconia particles in addition to the organic acid and the oxidizing agent.
The average particle size and the addition amount of these polishing abrasive grains are preferably in the same range as described for the copper-based metal polishing liquid.

The polishing treatment with the polishing liquid is carried out, for example, by using the polishing apparatus shown in FIG. Figure 1
In the polishing process using the polishing apparatus shown in (1), the load applied to the polishing pad by the substrate held by the substrate holder is appropriately selected according to the composition of the polishing liquid. For example, in a polishing liquid having a composition consisting of an organic acid, an oxidizing agent and water, the weight is preferably 200 to 2000 g / cm ² .
Further, in a polishing liquid having a composition containing polishing particles such as silica particles, the weight is preferably 150 to 1000 g / cm ² .

In the manufacture of the semiconductor device according to the present invention, it is allowed to form a barrier layer on the insulating film including the groove and / or the opening on the semiconductor substrate before depositing the wiring material film. . By forming such a barrier layer on the insulating film including the groove and / or the opening, a wiring material film such as Cu is deposited and an embedded wiring layer surrounded by the barrier layer is formed by etchback. It will be possible. As a result, it is possible to prevent the semiconductor substrate from being contaminated due to the diffusion of Cu, which is a wiring material.

The barrier layer is made of, for example, TiN, Ti, N
It is made of b, W or CuTa alloy. Such a barrier layer preferably has a thickness of 15 to 50 nm.
In the manufacture of the semiconductor device according to the present invention, based on the change of the rotation torque of the table, the change of the temperature of the polishing pad, or the change of the pH of the polishing liquid supplied to the polishing pad of the polishing apparatus shown in FIG. It is allowed to detect the end point of the polishing process. In addition, FIG.
It is allowed to detect the end point of the polishing process based on the change of the rotation torque of the holder of the polishing apparatus shown in FIG.
According to such a method, the end point of the polishing process can be easily detected. As a result, by utilizing this end point detection, it is possible to surely form a buried wiring layer flush with the surface of the insulating film.

In the method for manufacturing a semiconductor device according to the present invention described above, a groove and / or an opening corresponding to a wiring layer is formed in an insulating film on a semiconductor substrate, and the insulating film including the groove and / or the opening is formed. A wiring material film made of Cu or a Cu alloy is deposited on the film, and a polishing liquid containing at least one organic acid selected from aminoacetic acid and amidosulfuric acid, an oxidizing agent, and water, for example, shown in FIG. 1 described above. The wiring material film is polished using a polishing device until the surface of the insulating film is exposed. As described above, the polishing liquid contains the above C when the Cu film or the Cu alloy film is immersed.
The u film or the Cu alloy film is hardly etched, and the etching rate difference between the time of dipping and the time of polishing is several to several tens of times. As a result, in the polishing step, the wiring material film is sequentially polished from its surface, that is, so-called etch back is performed, so that a buried wiring layer made of Cu or a Cu alloy is formed in the groove and / or the opening of the insulating film. It can be formed flush with the surface of the insulating film. Further, although the wiring layer is contacted with the polishing liquid after the etch back process, an oxide layer is formed on the exposed surface of the wiring layer, so that the wiring layer can be prevented from being etched by the oxide layer. . Therefore, it is possible to manufacture a semiconductor device having a highly accurate embedded wiring layer and having a flat surface structure.

Further, by adjusting the pH of the polishing liquid to 9 to 14 with an alkaline agent such as potassium hydroxide, even if the amount of the organic acid such as aminoacetic acid contained in the polishing liquid is increased, the etching is performed. The etching of the wiring layer after the back step can be prevented by the oxide film having a high etching barrier property formed on the surface thereof. Moreover, by increasing the content of the organic acid in the polishing liquid, the polishing rate of the wiring material film can be increased, and as a result, the etchback time can be shortened.

Furthermore, since the polishing rate of the wiring material layer can be improved by using a polishing liquid to which polishing abrasive grains such as silica particles are added, the etchback time can be shortened. Moreover, since it is possible to suppress the occurrence of cracks and scratches in the wiring material film in the etch back step, it is possible to form a highly reliable buried wiring layer in the groove and / or the opening of the insulating film.

Another method of manufacturing a semiconductor device according to the present invention is the step of forming a groove and / or opening corresponding to the shape of a wiring layer in an insulating film on a semiconductor substrate, and the step of forming the groove and / or opening. A step of depositing a wiring material film made of copper or a copper alloy on the insulating film, and a polishing liquid containing at least one organic acid selected from aminoacetic acid and amidosulfuric acid, an oxidizing agent and water, A step of forming a buried wiring layer flush with the surface of the insulating film by exposing the wiring material film until the surface of the insulating film is exposed; and an aqueous ozone solution in which the surface of the insulating film including the wiring layer is dissolved. And a step of further treating with a dilute aqueous solution of hydrofluoric acid.

As the insulating film, for example, a silicon oxide film, a silicon nitride film, a two-layer film of a silicon oxide film and a silicon nitride film laminated thereon, a boron-added glass film (B
A PSG film), a phosphorus-containing glass film (PSG film), or the like can be used.

As the Cu alloy, for example, Cu--Si
Alloy, Cu-Al alloy, Cu-Si-Al alloy, Cu-
Ag alloy or the like can be used. Cu or Cu
The wiring material film made of an alloy is deposited by sputtering deposition, vacuum deposition, or the like.

The content of the organic acid and the content ratio of the organic acid and the oxidizing agent in the polishing liquid are preferably in the same range as the above-mentioned polishing liquid for copper-based metal. The polishing liquid is allowed to contain, in addition to the organic acid and the oxidizing agent, an alkaline agent for adjusting the pH to 9-14. As such an alkaline agent, for example, potassium hydroxide and quinoline are suitable.

The polishing liquid is allowed to contain polishing particles such as silica particles, alumina particles, cerium oxide particles and zirconia particles in addition to the organic acid and the oxidizing agent.
The average particle size and the addition amount of these polishing abrasive grains are preferably in the same range as described for the copper-based metal polishing liquid.

The polishing treatment with the polishing liquid is performed using the polishing apparatus shown in FIG. In the polishing process using the polishing apparatus shown in FIG. 1, the load applied to the polishing pad by the substrate held by the substrate holder is appropriately selected according to the composition of the polishing liquid. For example, in a polishing liquid having a composition consisting of an organic acid, an oxidizing agent and water, the weight is 200
It is preferably about 2000 g / cm ² . Further, in a polishing liquid having a composition containing polishing particles such as silica particles, the weight is preferably 150 to 1000 g / cm ² .

In manufacturing another semiconductor device according to the present invention, a barrier layer may be formed on the insulating film including the groove and / or the opening on the semiconductor substrate before depositing the wiring material film. Tolerate. By forming such a barrier layer on the insulating film including the groove and / or the opening, a wiring material film such as Cu is deposited and an embedded wiring layer surrounded by the barrier layer is formed by etchback. It will be possible. As a result, it is possible to prevent the semiconductor substrate from being contaminated due to the diffusion of Cu, which is a wiring material.

The barrier layer is made of, for example, TiN, Ti, N
It is made of b, W or CuTa alloy. Such a barrier layer preferably has a thickness of 15 to 50 nm.
In the manufacture of another semiconductor device according to the present invention, the change of the rotation torque of the table of the polishing apparatus shown in FIG. 1, the temperature change of the polishing pad, or the pH change of the polishing liquid supplied to the polishing pad is performed. Based on this, it is possible to detect the end point of the polishing process. Further, the end point of the polishing process is allowed to be detected based on the change of the rotation torque of the holder of the polishing apparatus shown in FIG. According to such a method, the end point of the polishing process can be easily detected. As a result, the embedded wiring layer flush with the surface of the insulating film can be surely formed by utilizing the end point detection.

The dissolved ozone aqueous solution preferably has an ozone concentration of 0.1 to 25 ppm. When the ozone concentration of the dissolved ozone aqueous solution is less than 0.1 ppm, Cu or Cu alloy, which is the wiring material remaining on the insulating film, may be converted into an oxide, or contaminants such as organic substances may be oxidatively decomposed. It will be difficult. A more preferable ozone concentration of the dissolved ozone aqueous solution is 5 to 25 ppm.

The dilute aqueous solution of hydrofluoric acid had a hydrofluoric acid concentration of 0.
It is preferably from 05 to 20%. When the hydrofluoric acid concentration of the dilute hydrofluoric acid aqueous solution is less than 0.05%, it becomes difficult to effectively dissolve and remove the oxides of Cu or Cu alloy converted by the treatment with the dissolved ozone aqueous solution.
On the other hand, if the concentration of hydrofluoric acid in the dilute hydrofluoric acid aqueous solution exceeds 20%, when a silicon oxide film is used as the insulating film, the oxide film may be dissolved and removed, resulting in film loss.
More preferable hydrofluoric acid concentration of the dilute hydrofluoric acid aqueous solution is 0.1.
~ 5%.

In another method of manufacturing a semiconductor device according to the present invention described above, a groove and / or an opening corresponding to a wiring layer is formed in an insulating film on a semiconductor substrate, and the groove and / or the opening is formed.
Alternatively, a wiring material film made of Cu or a Cu alloy is deposited on the insulating film including an opening, and a polishing liquid containing at least one organic acid selected from aminoacetic acid and amidosulfuric acid, an oxidizing agent, and water, For example, the wiring material film is polished until the surface of the insulating film is exposed by using the polishing apparatus shown in FIG. As described above, the polishing liquid hardly etches the Cu film or the Cu alloy film at the time of dipping the Cu film or the Cu alloy film, and is several times to several tens of times between the immersion time and the polishing time. The etching rate difference is shown. As a result, in the polishing step, the wiring material film is sequentially polished from its surface, that is, so-called etch back is performed, so that a buried wiring layer made of Cu or a Cu alloy is formed in the groove and / or the opening of the insulating film. It can be formed flush with the surface of the insulating film. Further, although the wiring layer is contacted with the polishing liquid after the etch back process, an oxide layer is formed on the exposed surface of the wiring layer, so that the wiring layer can be prevented from being etched by the oxide layer. .

Furthermore, after the etching back step, the surface of the insulating film including the wiring layer is treated with a dissolved ozone aqueous solution, so that a fine wiring material remaining on the insulating film,
That is, Cu or a Cu alloy can be converted into an oxide, and contaminants such as organic substances can be oxidatively decomposed. By treating with the diluted hydrofluoric acid aqueous solution after the treatment with the dissolved ozone aqueous solution, the oxide of Cu or Cu alloy or the oxidative decomposition product of the contaminant can be easily dissolved and removed on the insulating film.

Therefore, it is possible to manufacture a semiconductor device having a highly accurate embedded wiring layer, a flat surface structure, and a clean surface from which organic substances and residual wiring material on the surface of the insulating film are removed. it can.

Further, by adjusting the pH of the polishing liquid to 9 to 14 with an alkaline agent such as potassium hydroxide, even if the amount of the organic acid such as aminoacetic acid contained in the polishing liquid is increased, etching is performed. The etching of the wiring layer after the back step can be prevented by the oxide film having a high etching barrier property formed on the surface thereof. Moreover, by increasing the content of the organic acid in the polishing liquid, the polishing rate of the wiring material film can be increased, and as a result, the etchback time can be shortened.

Furthermore, since the polishing rate of the wiring material layer can be improved by using a polishing liquid to which polishing abrasive grains such as silica particles are added, the etchback time can be shortened. Moreover, since it is possible to suppress the occurrence of cracks and scratches in the wiring material film in the etch back step, it is possible to form a highly reliable buried wiring layer in the groove and / or the opening of the insulating film.

[0062]

The preferred embodiments of the present invention will be described in detail below. Example 1 First, as shown in FIG. 8A, a silicon substrate 21 having a diffusion layer such as a source and a drain (not shown) formed on its surface.
An interlayer insulating film having a thickness of 10
After depositing the SiO ₂ film 22 nm, the SiO ₂
A plurality of grooves 23 having a shape corresponding to the wiring layer and having a depth of 500 nm were formed in the film 22 by a photoetching technique. Then, as shown in FIG. 8B, a thickness of 1 is formed on the SiO ₂ film 22 including the groove 23 by sputtering deposition.
Barrier layer 24 of 5 nm TiN and thickness 600
The Cu film 25 nm of 25 nm was deposited in this order.

Next, the substrate 21 shown in FIG. 8B is held upside down on the substrate holder 5 of the polishing apparatus shown in FIG. 1 described above, and the substrate is mounted on the turntable 1 by the support shaft 4 of the holder 5. Trade name of Rodel Nitta, Inc .;
300g / cm on polishing pad 2 made of SUBA800
² is applied to the turntable 1 and the holder 5
Of the Cu film 25 and the barrier layer 24 deposited on the substrate 21 by supplying a polishing liquid from the supply pipe 3 to the polishing pad 2 at a speed of 20 ml / min while rotating the respective components in opposite directions at a speed of 100 ppm. Polishing was performed until the surface of the SiO ₂ film 22 was exposed. Here, 0.1% by weight of aminoacetic acid and 13.0% by weight of hydrogen peroxide were used as the polishing liquid.
And pure water containing 8% by weight of silica powder having an average particle diameter of 0.04 μm, and hydrogen peroxide was 130 per 1 aminoacetic acid in a weight ratio. In the polishing step, the polishing solution has an etching rate of zero when it contacts the Cu film, and the polishing rate when polishing with the polishing pad is about 77 nm / min, which is a sufficiently large difference in etching rate as compared with immersion. It was Therefore, in the polishing step, the convex Cu film 25 shown in FIG. 8B is preferentially polished from the surface that mechanically contacts the polishing pad,
Further, the exposed barrier layer 24 was polished, so-called etch back was performed. As a result, FIG. 8 (C)
As shown in FIG. 5, the barrier layer 24 remains only in the groove 23, and the buried Cu wiring layer 26 flush with the surface of the SiO ₂ film 22 is formed in the groove 23 covered with the barrier layer 24.
Was formed. Further, after releasing the load on the polishing pad 2 by the holder 5 of the polishing device and stopping the rotation of the turntable 1 and the holder 5,
Even if the Cu wiring layer 26 was brought into contact with the polishing liquid, the etching did not proceed.

Further, in the polishing step (etchback step) by the above-described polishing apparatus of FIG. 1, the polishing liquid was sequentially sampled from the polishing pad and the pH change was measured by the pH meter. FIG. 9 shows the pH change of the polishing liquid with respect to the polishing time. As is clear from FIG. 9, the pH once drops and then rises again after the substrate is loaded by the holder. This p
When H rises, for example, 8 minutes after the start of weighting,
Was set as the etching end point. By setting the etch back time by detecting such an end point, the SiO ₂
The embedded Cu wiring layer 26 flush with the surface of the SiO ₂ film 22 could be formed in the groove 23 of the film 22 with good reproducibility.

In the polishing step (etchback step) using the polishing apparatus shown in FIG. 1, the temperature change of the polishing pad and the voltage change of the drive motor of the turntable were measured by a temperature sensor. FIG. 10 shows the temperature change of the polishing pad with respect to the polishing time, and FIG. 11 shows the voltage change of the drive motor with respect to the polishing time. In FIG. 10 showing the temperature change, the temperature of the polishing pad rises to a constant temperature immediately after the start of weighting, and the temperature rises again. The time when this temperature rise occurred was defined as the etching end point. In FIG. 11 showing the voltage change, the voltage of the drive motor of the turntable rises to a constant voltage immediately after the start of weighting, and the voltage rises again. The etching end point was when this voltage increased. By setting the etch-back time by such endpoint detection, the SiO ₂ film 22 flush with the surface of buried Cu wiring layer in the groove 23 in the case of pH measurement in the same manner as the SiO ₂ film 22 of the polishing liquid as described above 26 could be formed with good reproducibility.

Further, the substrate on which the embedded wiring layer has been formed is immersed in a dissolved ozone aqueous solution having an ozone concentration of 0.001% for 3 minutes for treatment, and then immersed in a dilute hydrofluoric acid aqueous solution having a hydrofluoric acid concentration of 10% for 90 seconds. Processed. FIG. 12 is a spectrum diagram analyzed by XPS, where the solid line is the spectrum of the surface immediately after the formation of the Cu wiring layer, the dotted line is the spectrum of the Cu wiring layer surface after treatment with the dissolved ozone aqueous solution, and the chain line is after dilute hydrofluoric acid treatment. Is a spectrum of the Cu wiring layer surface. As is clear from FIG. 12, when the substrate after wiring formation is immersed in the dissolved ozone aqueous solution for treatment, the signal of metal Cu seen immediately after the wiring formation disappears as shown by the dotted line spectrum, and the Cu wiring layer surface is oxidized. You can see that it has changed.
After that, when it is treated with a dilute hydrofluoric acid aqueous solution, the signal of CuO found in the treatment with the dissolved ozone aqueous solution disappears as shown by the chain line line, and it can be seen that pure Cu was exposed on the surface of the Cu wiring layer. By thus treating with the dissolved ozone aqueous solution, organic substances such as aminoacetic acid remaining on the surface of the SiO ₂ film 22 and the like can be decomposed, and Cu remaining on the SiO ₂ film 22 can be converted into an oxide. The decomposition products of organic substances and Cu oxides generated by the treatment of the dissolved ozone aqueous solution can be removed by the subsequent treatment of the dilute hydrofluoric acid aqueous solution, and are generated on the surface of the Cu wiring layer 26 by the contact with the polishing liquid. The Cu oxide layer can also be removed. As a result, the surface of the SiO ₂ film 22 can be cleaned, and pure Cu can be exposed on the surface of the Cu wiring layer 26.

Therefore, according to Example 1, the SiO 2
Its depth in the groove 23 of the ₂ film 22 and the Cu wiring layer 26 buried with the same thickness can be formed on the SiO ₂ film 22 flush with the surface of, after formation of the wiring layer 26 substrate 21
It has been possible to flatten the surface. In addition, the Cu wiring layer 26
Since the treatment of the dissolved ozone aqueous solution and the treatment of the dilute hydrofluoric acid aqueous solution are performed after the formation, the surface of the SiO ₂ film 22 is cleaned and the oxide layer which is the resistance component generated by the oxidation of the polishing liquid is removed. It is possible to manufacture a highly reliable semiconductor device having a buried Cu wiring layer having a low resistance inherent to Cu.

In Example 1, as the polishing liquid, 0.86% by weight of amido sulfuric acid, 30% by weight of hydrogen peroxide solution,
When pure water containing 8% by weight of silica powder having an average particle diameter of 0.09 μm was used, a buried wiring layer was formed in the groove of the interlayer insulating SiO ₂ film as in the case of Example 1.
It could be formed flush with the surface of the _two films.

Example 2 First, as shown in FIG. 13A, a silicon substrate 2 having a diffusion layer such as a source and a drain (not shown) formed on the surface thereof.
On the substrate 1 by CVD, for example, 800 nm thick SiO ₂
After forming an interlayer insulating film by depositing the Si ₃ N ₄ film 27 of the film 22 and the thickness of 200nm in this order, the Si ₃ N
₄ film 27 and the SiO ₂ film 22 having a shape corresponding to a wiring layer formed by photo-etching technique and having a depth of 500 n
A plurality of m-shaped grooves 23 were formed. Subsequently, as shown in FIG. 13B, 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 on the Si ₃ N ₄ film 27 including the groove 23 by sputter deposition. Deposited in order.

Next, the substrate 21 shown in FIG. 13B is held upside down on the substrate holder 5 of the polishing apparatus shown in FIG. 1 described above, and the supporting shaft 4 of the holder 5 holds the substrate. Product name: SUBA800 polishing pad 2 is applied with a weight of 300 g / cm ² , and the turntable 1 and holder 5 are each 100 p
While rotating in the opposite directions at a speed of pm, the polishing liquid is supplied from the supply pipe 3 at a speed of 20 ml / min.
The Cu film 25 and the barrier layer 24 which were supplied to the substrate 21 and were deposited on the substrate 21 were polished until the surface of the Si ₃ N ₄ film 27 was exposed. Here, as the polishing liquid, aminoacetic acid of 0.
1% by weight, 13.0% by weight of hydrogen peroxide, and 8% by weight of silica powder having an average particle size of 0.04 μm were used as pure water.
The one that was 0 was used. In the polishing step, the polishing liquid has an etching rate of zero at the time of contact with the Cu film,
The polishing rate during polishing with the polishing pad is about 77.
The difference in etching rate at nm / min was sufficiently larger than that at the time of immersion. Therefore, the convex C shown in FIG.
The u film 25 is preferentially polished from the surface that makes mechanical contact with the polishing pad, and the exposed barrier layer 24
The so-called etch back was done.

As a result, as shown in FIG. 13C, the barrier layer 24 remains only in the groove 23, and the surface of the Si ₃ N ₄ film 27 is covered in the groove 23 covered with the barrier layer 24. A buried Cu wiring layer 26 flush with the above was formed. Further, even after the Cu wiring layer 26 is brought into contact with the polishing liquid after releasing the load on the polishing pad 2 by the holder 5 of the polishing apparatus and stopping the rotation of the turntable 1 and the holder 5, the etching is performed. Never progressed.

Further, in the polishing step using a polishing liquid containing the silica particles as polishing abrasive grains, the interlayer insulating film has a Si ₃ N ₃ surface having excellent polishing resistance.
_Since it is formed of the _four films 27, it is possible to suppress the film loss in the etch back process. Therefore, a semiconductor device including an interlayer insulating film having a good withstand voltage could be manufactured.

Example 3 First, as shown in FIG. 14A, a silicon substrate 2 having a diffusion layer such as a source and drain (not shown) formed on the surface thereof.
1 as a layer insulation film by CVD method, for example, with a thickness of 1
After depositing the 000 nm Si ₃ N ₄ film 27, the Si
A plurality of trenches 23 having a depth of 500 nm and having a shape corresponding to the wiring layer were formed in the ₃ N ₄ film 27 by a photoetching technique. Subsequently, as shown in FIG. 14B, a Cu film 25 having a thickness of 600 nm was deposited on the Si ₃ N ₄ film 27 including the groove 23 by sputter deposition.

Next, the substrate 21 shown in FIG. 14B is held upside down in the substrate holder 5 of the polishing apparatus shown in FIG. 1 described above, and the supporting shaft 4 of the holder 5 holds the substrate. Product name: SUBA800 polishing pad 2 is applied with a load of 400 g / cm ² , and the turntable 1 and holder 5 are each 100 p
While rotating in the opposite directions at a speed of pm, the polishing liquid is supplied from the supply pipe 3 at a speed of 20 ml / min.
The Cu film 25 deposited on the substrate 21 by supplying
Polishing was performed until the surface of the i ₃ N ₄ film 27 was exposed. As the polishing liquid, 0.9% by weight of aminoacetic acid, 22.0% by weight of hydrogen peroxide and 3.7% by weight of potassium hydroxide were used.
Was used, and the pH ratio was 10.5 in which hydrogen peroxide was about 24 per 1 aminoacetic acid in a weight ratio. In the polishing step, the polishing liquid has a zero etching rate when in contact with the Cu film, and the polishing rate when polishing with the polishing pad is about 220 nm / min, which is a sufficiently large etching rate difference as compared with immersion. It was For this reason, the convex Cu film 25 shown in FIG. 14 (B) was subjected to so-called etch back, in which polishing was performed preferentially from the surface that mechanically contacts the polishing pad.

As a result, as shown in FIG. 14C, a buried Cu wiring layer 26 flush with the surface of the Si ₃ N ₄ film 27 was formed in the groove 23. Further, even after the Cu wiring layer 26 is brought into contact with the polishing liquid after releasing the load on the polishing pad 2 by the holder 5 of the polishing apparatus and stopping the rotation of the turntable 1 and the holder 5, the etching is performed. Never progressed.

Further, the interlayer insulating film 27 having the groove 23 in which the embedded Cu wiring layer 26 is formed is made of Si ₃ N _{4 having} an excellent Cu diffusion barrier property. As a result, Cu
Since Cu does not diffuse from the wiring layer 26 to the silicon substrate 21 through the interlayer insulating film, avoiding contamination of the silicon substrate 21 without forming a barrier layer such as TiN on the inner surface of the groove 23. I was able to.

Embodiment 4 First, as shown in FIG. 15A, a p-type silicon substrate 32 having an n ⁺ -type diffusion layer 31 formed on the surface thereof is formed by CVD on the p-type silicon substrate 32 to a thickness of, for example, a first interlayer insulating film. After depositing a 1000 nm SiO ₂ film 33, a via hole 34 was formed in the SiO ₂ film 33 corresponding to the diffusion layer 31 by a photoetching technique. Subsequently, as shown in FIG. 15B, the SiO ₂ film 3 including the via hole 34 is formed.
After depositing a barrier layer 35 of TiN having a thickness of 20 nm on the No. 3 by sputter deposition, a Cu film 36 having a thickness of 1100 nm was deposited by sputter deposition.

Next, the substrate 32 shown in FIG. 15 (B) is held upside down in the holder 5 of the polishing apparatus shown in FIG. 1, and the supporting shaft 4 of the holder 5 holds the substrate by Rodel-Nitta. Product name; SUBA800 polishing pad 2 is applied with a load of 300 g / cm ² , and the turntable 1 and holder 5 are each 100 ppm.
The polishing solution is supplied from the supply pipe 3 to the polishing pad 2 at a speed of 20 ml / min while rotating in the opposite directions at a speed of 10 to form the Cu film 36 and the barrier layer 35 deposited on the substrate 32 into the SiO ₂ film. Polishing was performed until the surface of 33 was exposed. Here, 0.2% by weight of aminoacetic acid, 20.0% by weight of hydrogen peroxide and an average particle size of 0.04 were used as the polishing liquid.
It was made of pure water containing 10% by weight of silica powder having a particle diameter of μm, and hydrogen peroxide was 100 per 1 aminoacetic acid in a weight ratio. In the polishing step, the polishing liquid is C
The etching rate at the time of contact with the u film was zero, and the polishing rate at the time of polishing by the polishing pad was about 70 nm / min, showing a sufficiently large etching rate difference as compared with the time of immersion. Therefore, the convex Cu film 36 shown in FIG.
Was preferentially polished from the surface that mechanically contacts the polishing pad, and the exposed barrier layer 35 was polished, so-called etch back was performed. As a result, as shown in FIG. 15C, the barrier layer 35 remains only in the via hole 34 and the barrier layer 3 is formed.
The SiO ₂ film 33 in the via hole 34 covered with
A via fill 37 made of Cu, which is flush with the surface, was formed. Further, even after the load of the polishing pad 2 by the holder 5 of the polishing device is released and the rotation of the turntable 1 and the holder 5 is stopped, the etching progresses even if the via fill 37 is brought into contact with the polishing liquid. I had nothing to do. Subsequently, the substrate on which the via fill 37 has been formed is immersed in a dissolved ozone aqueous solution having an ozone concentration of 0.002% for 3 minutes and then treated for 9 seconds in a dilute hydrofluoric acid aqueous solution having a hydrofluoric acid concentration of 5%. By Si
The surface of the O ₂ film 33 was cleaned.

Next, as shown in FIG. 16D, a Si ₃ N ₄ film 38 having a thickness of, for example, 800 nm is deposited as a second interlayer insulating film on the SiO ₂ film 33 including the via fill 37 by the CVD method. And then the Si ₃ N ₄ film 38
A plurality of grooves 39 having a depth of 400 nm and having a shape corresponding to the wiring layer were formed by photoetching technique. Further, a through hole 40 was formed in the groove 39 located on the via fill 37 by a photo etching technique. Then, as shown in FIG.
A 900 nm-thickness Cu film 41 was deposited on the Si ₃ N ₄ film 38 including the through holes 40 by sputter deposition.

Next, the substrate 32 shown in FIG. 16 (E) is held upside down on the substrate holder 5 of the polishing apparatus shown in FIG. 1, and the supporting shaft 4 of the holder 5 holds the substrate. Product name: SUBA800 polishing pad 2 is applied with a weight of 300 g / cm ² , and the turntable 1 and holder 5 are each 100 p
While rotating in the opposite directions at a speed of pm, a polishing liquid having the same composition as that used in the above-mentioned etch-back process is supplied from the supply pipe 3 to the polishing pad 2 at a speed of 20 ml / min so that the substrate The Cu film 41 deposited on 32 was polished until the surface of the Si ₃ N ₄ film 38 was exposed. As a result, the convex Cu film 41 shown in (E) of FIG. 16 was subjected to preferential polishing from the surface that mechanically contacts the polishing pad, so-called etch back was performed. By such etching back, as shown in FIG. 16F, a buried Cu wiring layer 42 flush with the surface of the Si ₃ N ₄ film 38 was formed in the groove 39. At the same time, a buried Cu wiring layer 42 connected to the via fill 37 through the through hole 40 was formed. Further, even if the Cu wiring layer 42 is brought into contact with the polishing liquid after releasing the load on the polishing pad 2 by the holder 5 of the polishing device and stopping the rotation of the turntable 1 and the holder 5, the etching is performed. Never progressed.

Therefore, according to the fourth embodiment, the first and second
The first interlayer insulating film 3 having the interlayer insulating films 33 and 39 of
A via-fill 37, which is flush with the surface of the via 3, is formed on
It was possible to manufacture a semiconductor device having a multilayered wiring structure in which a Cu wiring layer 42 flush with the surface of the interlayer insulating film 39 was formed and the surface was flattened.

[0082]

As described above, according to the present invention, C
It is possible to provide a copper-based metal polishing liquid that hardly etches Cu or Cu alloy during immersion of u or Cu alloy and shows a difference in etching rate between immersion and polishing of several times to several tens of times.

Further, according to the present invention, a groove and / or an opening is formed in the insulating film on the semiconductor substrate, and the wiring material film made of Cu or Cu alloy deposited on the insulating film is etched back in a short time. Therefore, it is possible to provide a method for manufacturing a semiconductor device in which a buried wiring layer made of Cu or a Cu alloy is formed in the insulating film so as to be flush with the surface of the insulating film.

Further, according to the present invention, a groove and / or an opening is formed in the insulating film on the semiconductor substrate, and the wiring material film made of Cu or Cu alloy deposited on the insulating film is etched back in a short time. A method for manufacturing a semiconductor device having a clean and flat surface, in which an embedded wiring layer flush with the surface of the insulating film can be formed, and further, organic substances and residual wiring material on the surface of the insulating film after etching back are removed. Can be provided.

[Brief description of drawings]

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

FIG. 2 shows the amount of hydrogen peroxide in a polishing liquid having a composition of 0.1% by weight of aminoacetic acid, hydrogen peroxide and water, the etching rate of a Cu film when immersed in the polishing liquid, and the Cu during polishing treatment. The characteristic view which shows the relationship with the polishing speed of a film.

FIG. 3 is a cross-sectional view showing a state when a Cu film having irregularities is immersed in a polishing liquid having a composition of aminoacetic acid, hydrogen peroxide and water, and subjected to polishing treatment using a polishing device.

FIG. 4 is an XPS spectrum diagram of a Cu film surface before processing, after immersion of a polishing liquid of the present invention, and after polishing treatment.

FIG. 5 shows the amount of hydrogen peroxide in a polishing liquid having a composition of 0.9% by weight of aminoacetic acid, hydrogen peroxide and water, the etching rate of a Cu film when immersed in the polishing liquid, and the Cu during polishing treatment. The characteristic view which shows the relationship with the polishing speed of a film.

FIG. 6 shows the amount of hydrogen peroxide in a polishing liquid composed of amido sulfuric acid, hydrogen peroxide and water, the etching rate of the Cu film when immersed in the polishing liquid, and the polishing speed of the Cu film during polishing treatment. The characteristic diagram which shows a relationship.

FIG. 7 is a characteristic diagram showing changes in pH of the polishing liquid of the present invention and thickness of an oxide layer formed on the surface of a Cu film.

FIG. 8 is a cross-sectional view showing the manufacturing process of the semiconductor device according to the first embodiment of the invention.

FIG. 9 is a characteristic diagram showing a pH change of the polishing liquid in the polishing process (etchback process) of Example 1.

FIG. 10 is a characteristic diagram showing a temperature change of the polishing pad in the polishing process (etchback process) of Example 1.

FIG. 11 is a characteristic diagram showing a voltage change of the drive motor of the turntable in the polishing process (etchback process) of the first embodiment.

FIG. 12 is a spectrum diagram obtained by XPS analysis of the surface immediately after forming the Cu wiring layer, the surface of the Cu wiring layer after the ozone treatment, and the surface of the Cu wiring layer after the dilute hydrofluoric acid treatment in Example 1 of the present invention.

FIG. 13 is a cross-sectional view showing the manufacturing process of the semiconductor device according to the second embodiment of the invention.

FIG. 14 is a cross-sectional view showing the manufacturing process of the semiconductor device according to the third embodiment of the invention.

FIG. 15 is a sectional view showing a manufacturing process of a semiconductor device according to a fourth embodiment of the present invention.

FIG. 16 is a sectional view showing a manufacturing process of a semiconductor device according to a fourth embodiment of the present invention.

[Explanation of symbols]

1 ... Turntable, 2 ... Polishing pad, 3 ... Supply pipe, 5
... Holders, 11, 21, 32 ... Silicon substrates, 12, 2
5, 36, 41 ... Cu film, 13 ... Oxide layer, 22, 33 ...
SiO ₂ film, 23, 39 ... Groove, 24, 35 ... Barrier layer,
26, 42 ... Cu wiring layer, 37 ... Via fill.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H01L 21/304 321 PM 21/3205

Claims (20)

[Claims] 1. A copper-based metal polishing liquid containing at least one organic acid selected from aminoacetic acid and amidosulfuric acid, an oxidizing agent, and water. 2. The polishing liquid for copper-based metals according to claim 1, wherein the oxidizing agent is hydrogen peroxide. 3. The organic acid is 0.01% in the polishing liquid.
The content of the organic acid and the oxidizing agent is 20 wt% or more, and the content ratio of the organic acid and the oxidizing agent is 20 or more with respect to 1 of the organic acid by weight. Polishing solution for copper metal. 4. The polishing solution for copper-based metals according to claim 1, further comprising an alkaline agent for adjusting the pH to 9-14. 5. The polishing liquid for copper-based metals according to claim 1, further containing polishing abrasive grains. 6. The polishing abrasive contains 1 to 1 of the polishing liquid in the polishing liquid.
The copper-based metal polishing liquid according to claim 5, wherein the polishing liquid is contained in an amount of 4% by weight. 7. 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 copper or a copper alloy on the insulating film including the groove and / or the opening. A wiring material film consisting of at least one selected from aminoacetic acid and amidosulfuric acid.
An embedded wiring layer flush with the surface of the insulating film by polishing the wiring material film with a polishing liquid containing a certain organic acid, an oxidizing agent, and water until the surface of the insulating film is exposed. And a step of forming a semiconductor device. 8. The Cu alloy is a Cu—Si alloy, Cu
The method for manufacturing a semiconductor device according to claim 7, wherein the method is a -Al alloy, a Cu-Si-Al alloy, or a Cu-Ag alloy. 9. The polishing process comprises a turntable covered with a polishing pad, a means for supplying the polishing liquid to the polishing pad of the table, the semiconductor substrate held on the lower surface, and the substrate being the polishing pad. 8. The method of manufacturing a semiconductor device according to claim 7, wherein the polishing is performed by using a polishing apparatus having a substrate holder that presses and rotates the substrate holder. 10. The method of manufacturing a semiconductor device according to claim 9, wherein the end point of the polishing process is detected based on a change in the rotation torque of the table of the polishing device. 11. The method of manufacturing a semiconductor device according to claim 9, wherein the end point of the polishing process is detected based on a temperature change of the polishing pad. 12. The method of manufacturing a semiconductor device according to claim 9, wherein the end point of the polishing process is detected based on a change in pH of the polishing liquid supplied to the polishing pad. 13. 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 copper or a copper alloy on the insulating film including the groove and / or the opening. A wiring material film consisting of at least one selected from aminoacetic acid and amidosulfuric acid.
An embedded wiring layer flush with the surface of the insulating film by polishing the wiring material film with a polishing liquid containing a certain organic acid, an oxidizing agent, and water until the surface of the insulating film is exposed. And a step of treating the surface of the insulating film including the wiring layer with a dissolved ozone aqueous solution, and further treating with a dilute hydrofluoric acid aqueous solution. 14. The Cu alloy is a Cu—Si alloy, C
u-Al alloy, Cu-Si-Al alloy or Cu-Ag
14. The method of manufacturing a semiconductor device according to claim 13, wherein the method is an alloy. 15. A turntable covered with a polishing pad, a means for supplying the polishing liquid to the polishing pad of the table, the semiconductor substrate held on the lower surface, and the substrate pressed against the polishing pad to rotate. 14. The method of manufacturing a semiconductor device according to claim 13, wherein the polishing is performed by using a polishing device having a substrate holder for making the substrate holder. 16. The method of manufacturing a semiconductor device according to claim 15, wherein the end point of the polishing process is detected based on a change in the rotation torque of the table of the polishing device. 17. The method of manufacturing a semiconductor device according to claim 15, wherein the end point of the polishing process is detected based on a temperature change of the polishing pad. 18. The method of manufacturing a semiconductor device according to claim 15, wherein the end point of the polishing process is detected based on a change in pH of the polishing liquid supplied to the polishing pad. 19. The dissolved ozone aqueous solution has an ozone concentration of 0.1 to 25 ppm.
3. The method for manufacturing a semiconductor device according to 3. 20. The method of manufacturing a semiconductor device according to claim 13, wherein the dilute hydrofluoric acid solution has a hydrofluoric acid concentration of 0.05 to 20%.