JP4327763B2 - Polishing liquid for copper metal and method for polishing copper metal - Google Patents

Description

  The present invention relates to a copper-based metal polishing liquid and a copper-based metal polishing method.

Non-Patent Documents 1 to 3 include a Cu film or a Cu alloy film made of an amine-based colloidal silica slurry or a slurry to which K ₃ Fe (CN) ₆ , K ₄ (CN) ₆ , or Co (NO ₃ ) ₂ is added. A polishing liquid is disclosed.

  However, the polishing solution has the following problems because there is no difference in the dissolution rate of the Cu film between the immersion and the polishing.

In the formation of a wiring layer, which is one of the manufacturing processes of a semiconductor device, an etch back technique is employed for the purpose of eliminating a surface level difference. In this etch-back 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, the Cu film is polished using a polishing liquid, and only in the groove. In this method, the embedded wiring layer is formed by leaving the Cu film. After such an etch-back process, the Cu wiring layer in the groove is in contact with the polishing liquid, so that the polishing liquid having the above-described composition with 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, since the surface position of the Cu wiring layer in the groove is lower than the surface of the insulating film, it becomes difficult to form a wiring layer flush with the surface of the insulating film, and the flatness is impaired. Further, the formed embedded Cu wiring layer has a higher resistance value than the Cu wiring layer embedded flush with the surface of the insulating film.
J. et al. Electrochem. Soc. , VoL. 138. No11, 3460 (1991) VMIC Conference, ISMIC-101 / 92/0156 (1992) VMIC Conference, ISMIC-102 / 93/0205 (1993)

  It is an object of the present invention to hardly etch Cu or the like when dipping copper (Cu) or a copper alloy (Cu alloy), and dissolve the Cu or Cu alloy at the time of polishing treatment, and at the time of dipping and polishing treatment. Therefore, it is an object of the present invention to provide a polishing slurry for copper-based metal that exhibits an etching rate difference of several times to several tens of times.

The copper-based metal polishing liquid according to the present invention is a copper-based metal polishing liquid containing amidosulfuric acid, hydrogen peroxide, and water,
The amide sulfuric acid, the is contained in an amount of in the polishing liquid 0.01 to 10 wt%, and the hydrogen peroxide relative to the amide acid 1 content ratio of the said amide acid hydrogen peroxide in a weight ratio Is 20 or more.

In the method for polishing a copper-based metal according to the present invention, a substrate on which a copper film or a copper alloy film is formed is held on a substrate holder, and the copper film or the copper alloy film on the substrate is applied to a polishing pad provided on a turntable. A method for polishing a copper-based metal that presses and rotates the turntable and the substrate holder and supplies a polishing liquid between the polishing pad and a copper film or a copper alloy film of the substrate,
The polishing liquid contains amidosulfuric acid, hydrogen peroxide, and water,
The amide sulfuric acid, the is contained in an amount of in the polishing liquid 0.01 to 10 wt%, and the hydrogen peroxide relative to the amide acid 1 content ratio of the said amide acid hydrogen peroxide in a weight ratio Is 20 or more.

  According to the present invention, when Cu or Cu alloy is immersed, Cu or Cu alloy is hardly etched, and the difference in etching rate is several to several tens times between immersion and polishing. A polishing liquid can be provided.

  According to the present invention, copper or Cu alloy is hardly etched at the time of immersion of Cu or Cu alloy, and an etching rate difference of several to several tens of times can be taken between immersion and polishing. A method for polishing a metal can be provided.

  Hereinafter, embodiments of the present invention will be described in detail.

  The copper-based metal polishing liquid according to the embodiment contains 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 during polishing of Cu or Cu alloy. The Cu or Cu alloy exposed by mechanically removing the oxide layer is etched with the organic acid. Therefore, when the Cu or Cu alloy is immersed in the polishing liquid, etching is suppressed or prevented by the oxide layer, and the Cu or Cu alloy exposed during the polishing is physically polished and etched by the organic acid in the polishing liquid. Progresses. As a result, the difference in etching rate of Cu or Cu alloy between immersion and polishing can be made sufficiently large.

As the oxidizing agent, for example, hydrogen peroxide (H ₂ O ₂ ), sodium hypochlorite (NaClO), or the like can be used.

  The polishing liquid preferably contains 0.01 to 10% by weight of the organic acid, and the oxidant is 20 or more with respect to the organic acid 1 by weight. The reason why the content of the organic acid in the polishing liquid and the content ratio of the organic acid and the oxidizing agent are defined in this way is as follows.

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

  If the oxidizer is less than 20 with respect to the organic acid 1 by weight, there is a fear that a sufficient etching rate difference cannot be obtained between the immersion of Cu or Cu alloy and the polishing. It is desirable that the content ratio of the organic acid and the oxidizing agent in the polishing liquid is 40 or more, more preferably 100 or more, with respect to the organic acid 1 by weight.

  The upper limit ratio of the oxidant to the organic acid is desirably defined from the content of the oxidant. For example, the content of the oxidant is preferably 30% by weight. If the content of the oxidizing agent exceeds 30% by weight, an oxidized layer may be immediately formed on the exposed surface during polishing of Cu or Cu alloy, leading to a decrease in polishing rate.

  In addition, when making content of the said organic acid into the lower limit (0.01 weight%) side within the said range, the content ratio of the said organic acid and an oxidizing agent is an oxidizing agent with respect to the organic acid 1 in a weight ratio. Is preferably 40 or more.

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

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

  The abrasive grains preferably have an average particle size of 0.02 to 0.1 μm.

  The abrasive grains are preferably added in an amount of 1 to 14% by weight. When the addition amount of the abrasive grains is less than 1% by weight, it is difficult to sufficiently achieve the effect. On the other hand, if the addition amount of the abrasive grains exceeds 14% by weight, the viscosity of the polishing liquid becomes high and handling becomes difficult. The addition amount of the abrasive grains is more preferably in the range of 3 to 10% by weight.

  For polishing, for example, a Cu film or a Cu alloy film formed on a substrate with the copper-based metal polishing liquid according to the present invention, a polishing apparatus shown in FIG. 1 is used. That is, a polishing pad 2 made of, for example, a cloth is covered on the turntable 1. A supply pipe 3 for supplying a polishing liquid is disposed above the polishing pad 2. A substrate holder 5 having a support shaft 4 on its upper surface is disposed above the polishing pad 2 so as to be vertically movable and rotatable. In such a polishing apparatus, the substrate 5 is held by the holder 5 so that the polishing surface (for example, Cu film) faces the pad 2, and the polishing liquid 7 having the above composition is supplied from the supply pipe 3. The support shaft 4 gives the substrate 6 a desired load toward the polishing pad 2, and the Cu film on the substrate is polished by rotating the hold 5 and the turntable 1 in opposite directions. The

  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. Etc. are preferably etched (preferably an etching rate of 100 nm / min or less), and an etching rate difference of several times to several tens of times is exhibited between immersion and polishing.

  That is, an organic acid (for example, aminoacetic acid), which is a component of the polishing liquid, has a property of forming a complex by reacting with Cu hydrate as shown in the following reaction formula.

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 indicated by the arrow in the reaction formula, and Cu is etched.

FIG. 2 shows a film formed on a substrate when the content of aminoacetic acid is constant at 0.1% by weight in a polishing liquid comprising aminoacetic acid, hydrogen peroxide and water, and the content of hydrogen peroxide is changed. 2 is a plot of the etching rate during immersion of the Cu film and the polishing rate during polishing. The polishing process is performed using the polishing apparatus shown in FIG. That is, the substrate on which the Cu film is 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 manufactured by Rodel Nitta Co .; While applying a load of 400 g / cm ² to the polishing pad 2 on the substrate and rotating the turntable 1 and the holder 5 in directions opposite to each other at a speed of 100 rpm, the polishing liquid is supplied from the supply pipe 3 to 12.5 ml / min. A polishing process was performed by supplying the polishing pad 2 at a speed of 5 mm.

  As is apparent from FIG. 2, when a polishing solution to which hydrogen peroxide is not added is used at the time of immersion of the Cu film, the etching of the Cu film does not occur at all. It can be seen that it is etched. This is because Cu hydrate is generated by hydrogen peroxide in the polishing liquid, and amino acetate reacts with this to form a complex, thereby etching Cu. It can also be seen that when the hydrogen peroxide content is further increased, the etching rate of the Cu film is decreased, and when the hydrogen peroxide content is 5% by weight, the etching rate becomes zero. This is considered to be because when the hydrogen peroxide content is increased, an oxide layer is formed on the surface of the Cu film that prevents etching by the polishing liquid.

  In fact, as shown in FIG. 3A, a Cu film 12 having projections and depressions is formed on the substrate 11, and the substrate 11 is polished with a polishing liquid (aminoacetic acid 0.1.degree. When immersed in 3% by weight), the oxide layer 13 is formed on the surface of the Cu film 12 as shown in FIG. Further, after immersing the substrate in the polishing liquid and analyzing the surface of the Cu film by XPS (X-ray photoelectron spectroscopy), the spectrum shown by the solid line in FIG. 4 appears, and therefore an oxide layer is formed. Was confirmed. In addition, the dotted line of FIG. 4 shows the spectrum before a process immediately after forming Cu film | membrane on a board | substrate.

  When the polishing process described above is performed 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 polishing rate of the Cu film is immersed as shown in FIG. It was confirmed that a difference of about 10 nm / min occurred compared to the case. The increase in the polishing rate of the Cu film by such a polishing process is shown in FIG. 3 when the Cu film 12 having the oxide layer 13 formed on the surface thereof shown in FIG. 3B is polished with a polishing pad containing the polishing liquid. (C), the oxide layer 13 corresponding to the convex portion of the Cu film 12 is mechanically polished by the pad so that pure Cu is exposed on the surface, and the action of aminoacetic acid and hydrogen peroxide in the polishing liquid. This is because of the rapid chemical polishing. That is, in the polishing process, pure Cu is always exposed on the polished surface of the Cu film, and chemical etching with aminoacetic acid and hydrogen peroxide in the polishing liquid is performed. In fact, when the surface of the Cu film immediately after the polishing treatment was analyzed by XPS, the spectrum shown by the one-dot chain line in FIG. 4 appeared and it was confirmed that Cu was exposed.

  FIG. 5 shows a film formed on a substrate when the content of aminoacetic acid is constant at 0.9% by weight in a polishing liquid comprising aminoacetic acid, hydrogen peroxide and water, and the content of hydrogen peroxide is changed. The etching rate at the time of immersion of the prepared Cu film and the polishing rate at the time of polishing treatment are plotted. The polishing process was performed by the same procedure as described above using the polishing apparatus shown in FIG. As is apparent from FIG. 5, when a polishing liquid to which hydrogen peroxide is not added is used during the immersion of the Cu film, the etching of the Cu film does not occur at all. It can be seen that it is etched. It can also be seen that when the hydrogen peroxide content is further increased, the etching rate of the Cu film is decreased, and when the hydrogen peroxide content is about 18% by weight, the etching rate becomes zero. This is considered to be because when the hydrogen peroxide content is increased, an oxide layer is formed on the surface of the Cu film that prevents etching by the polishing liquid. In such a polishing liquid, when a Cu film is polished by the same method as described above using a solution containing 15% by weight of hydrogen peroxide, the Cu film is polished at a rate of about 85 nm / min. There is a sufficient difference in etching rate between the polishing process and the polishing process. However, a polishing solution containing 20% by weight of hydrogen peroxide, which is a condition that the Cu film is not reliably etched during immersion, that is, the content ratio of aminoacetic acid to hydrogen peroxide is 1% by weight with respect to aminoacetic acid. Even with a polishing liquid of about 20, the polishing rate during the polishing of the Cu film is about 60 nm / min. Therefore, even when a polishing liquid having a large hydrogen peroxide content is used, a sufficient etching rate difference can be obtained between the time of immersion and the time of polishing.

  Further, FIG. 6 shows a substrate when the content of hydrogen peroxide is changed with the content of amidosulfuric acid being constant at 0.86% by weight in the polishing liquid composed of organic acids amidosulfuric acid, hydrogen peroxide and water. The etching rate at the time of immersion of the Cu film | membrane formed into a film above and the polishing rate at the time of a grinding | polishing process are plotted. The polishing process was performed by the same procedure as described above using the polishing apparatus shown in FIG. As can be seen from FIG. 6, when a polishing solution to which hydrogen peroxide is not added is used, etching of the Cu film does not occur at all. However, when a small amount of hydrogen peroxide is contained, the Cu film is rapidly etched. . It can also be seen that when the hydrogen peroxide content is further increased, the etching rate of the Cu film is decreased, and when the hydrogen peroxide content is about 22% by weight or more, the etching rate is 50 nm / min. This is considered to be because when the hydrogen peroxide content is increased, an oxide layer is formed on the surface of the Cu film that prevents etching by the polishing liquid. In such a polishing liquid, a polishing liquid containing 30% by weight of hydrogen peroxide, that is, a polishing liquid in which the content ratio of amidosulfuric acid to hydrogen peroxide is about 35% hydrogen peroxide with respect to aminoacetic acid 1 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 the immersion and the polishing process can be sufficiently large, about 19 times.

  Therefore, the polishing liquid according to the present invention hardly etches Cu or Cu alloy when Cu or Cu alloy is immersed, and exhibits an etching rate difference of several times to several tens of times between immersion and polishing. For this reason, the problem that the etching amount of Cu fluctuates depending on the supply timing of the polishing liquid in the polishing process can be avoided, and the operation can be easily performed. In addition, after the polishing of the Cu film on the substrate by the polishing apparatus, when the Cu film comes into contact with the polishing liquid, an oxide layer is formed on the Cu film by hydrogen peroxide as described above. Even after the treatment, so-called over-etching, in which the Cu film is further etched, can be prevented. Further, as shown in FIG. 3C, the concave and convex Cu film 12 is not etched from the side surface in the polishing process, and can be sequentially etched from the surface of the convex portion in contact with the polishing pad. Very suitable for etch-back technology.

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

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

In the polishing liquid according to the present invention, by adding abrasive grains such as silica particles, the polishing rate at the time of polishing Cu or Cu alloy can be improved as compared with the polishing liquid to which the abrasive grains are not added. For example, silica particles having an average particle size of 30 nm, alumina particles having an average particle size of 740 nm, cerium oxide particles having an average particle size of 1300 nm, and an average particle size of 1100 nm in an aqueous solution containing 0.1% by weight of aminoacetic acid and 13% by weight of hydrogen peroxide A polishing liquid was prepared by adding about 9 wt% of each zirconia particle. Using these polishing liquids, a polishing process was performed on a Cu film having irregularities formed on a substrate by the same procedure as described above using the polishing apparatus shown in FIG. Table 1 below shows the Cu film polishing rate for each polishing liquid. In Table 1 below, the polishing rate of the Cu film in the case of using a polishing liquid containing 0.1% by weight of aminoacetic acid and 13% by weight of hydrogen peroxide to which no abrasive grains are added is shown.

  As apparent from Table 1, it can be seen that the polishing liquid to which the abrasive grains are added can improve the polishing rate of the Cu film as compared with the polishing liquid to which no abrasive grains are added. It can also be seen that the polishing rate of the Cu film can be controlled by changing the type of 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 ₃ N ₄ The film and the boron-added glass film (BPSG film) were each polished. Table 2 below shows the polishing rate of various insulating films by each polishing liquid. The values in parentheses in Table 2 are speed ratios obtained from (polishing speed of Cu film / polishing speed of each insulating film with the same kind of polishing liquid). When a buried Cu wiring layer is formed by polishing in a groove of an insulating film during the manufacture of a semiconductor device, which will be described later, the greater the speed ratio, the better the selective polishing of Cu. That is, the decrease in the thickness of the underlying insulating film can be suppressed.

  Furthermore, the polishing liquid to which abrasive grains such as silica particles are added can be polished well without causing cracks or fine scratches in 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 relaxed by the abrasive grains, and the impact force on the Cu film can be reduced to reduce cracks, etc. It is because it can prevent.

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

  It should be noted that the polishing rate of Cu or Cu alloy can be improved even in a polishing liquid containing amidosulfuric acid such as silica particles and the polishing liquid to which the polishing abrasive grains are not added as compared with a polishing liquid to which the polishing abrasive is not added. Damage to the surface of Cu or Cu alloy can be suppressed.

A method of manufacturing a semiconductor device according to the present invention includes 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,
Depositing a wiring material film made of Cu or Cu alloy on the insulating film including the groove and / or the opening; 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, thereby insulating film And a step of forming a buried wiring layer flush with the surface thereof.

  Examples of the insulating film include a silicon oxide film, a silicon nitride film, a silicon oxide film and a silicon nitride film laminated thereon, a boron-added glass film (BPSG film), and a phosphorus-added glass film (PSG film). Etc. can be used.

  As said Cu alloy, Cu-Si alloy, Cu-Al alloy, Cu-Si-Al alloy, Cu-Ag alloy etc. can be used, for example.

  The wiring material film made of Cu or Cu alloy is deposited by sputtering vapor deposition, vacuum vapor deposition or the like.

  It is preferable that the content of the organic acid in the polishing liquid and the content ratio of the organic acid and the oxidizing agent are in the same range as the above-described polishing liquid for copper-based metal.

  The polishing liquid is allowed to contain an alkaline agent that adjusts the pH to 9 to 14 in addition to the organic acid and the oxidizing agent. As such an alkali agent, for example, potassium hydroxide and quinoline are suitable.

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

  The polishing process using the polishing liquid is performed using, for example, the polishing apparatus shown in FIG.

In the polishing process using the polishing apparatus shown in FIG. 1, the weight applied to the polishing pad with 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 comprising 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 abrasive grains such as silica particles, the load 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 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 opening, a buried wiring layer surrounded by the barrier layer is formed by depositing and etching back a wiring material film such as Cu. It becomes possible. As a result, it is possible to prevent contamination of the semiconductor substrate due to diffusion of Cu as a wiring material.

  The barrier layer is made of, for example, TiN, Ti, Nb, W, or a 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 a change in rotational torque of the table, a change in temperature of the polishing pad, or a change in pH of the polishing liquid supplied to the polishing pad in the polishing apparatus shown in FIG. It is allowed to detect the end point of the polishing process. Further, it is allowed to detect the end point of the polishing process based on the change in the rotational 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 using this end point detection, it is possible to reliably form a buried wiring layer flush with the surface of the insulating film.

  In the semiconductor device manufacturing method according to the present invention described above, a groove and / or 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 opening is formed on the insulating film. A polishing liquid containing a wiring material film made of Cu or Cu alloy and further containing at least one organic acid selected from aminoacetic acid and amidosulfuric acid, an oxidizing agent and water, and the polishing apparatus shown in FIG. The wiring material film is polished until the surface of the insulating film is exposed. As described above, the polishing liquid hardly etches the Cu film or the Cu alloy film when dipping the Cu film or the Cu alloy film, and is several times to several tens of times between the dipping 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 the surface thereof, so-called etch back is performed. Therefore, a buried wiring layer made of Cu or Cu alloy is formed in the groove and / or opening of the insulating film. It can be formed flush with the surface of the insulating film. Further, the wiring layer after the etch-back process is brought into contact with the polishing liquid, but 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, a semiconductor device having a highly accurate embedded wiring layer and a flat surface can be manufactured.

  Further, by adjusting the pH of the polishing liquid to 9 to 14 with an alkaline agent such as potassium hydroxide, the amount of organic acid such as aminoacetic acid contained in the polishing liquid can be increased even after the etch-back step. Etching of the wiring layer can be prevented by an oxide film having a high etching barrier property formed on the surface thereof. In addition, by increasing the content of the organic acid in the polishing liquid, it is possible to increase the polishing speed of the wiring material film, and as a result, it is possible to shorten the etch back time.

  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 etch back time can be shortened. In addition, since the generation of cracks and scratches in the wiring material film can be suppressed in the etch back process, a highly reliable embedded wiring layer can be formed in the groove and / or opening of the insulating film.

Another method of manufacturing a semiconductor device according to the present invention includes a step of forming a groove and / or an opening corresponding to the shape of the wiring layer in an insulating film on a semiconductor substrate;
Depositing a wiring material film made of copper or a copper alloy on the insulating film including the groove and / or the opening; 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, thereby insulating film Forming a buried wiring layer flush with the surface thereof,
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.

  Examples of the insulating film include a silicon oxide film, a silicon nitride film, a silicon oxide film and a silicon nitride film laminated thereon, a boron-added glass film (BPSG film), and a phosphorus-added glass film (PSG film). Etc. can be used.

  As said Cu alloy, Cu-Si alloy, Cu-Al alloy, Cu-Si-Al alloy, Cu-Ag alloy etc. can be used, for example.

  The wiring material film made of Cu or Cu alloy is deposited by sputtering vapor deposition, vacuum vapor deposition or the like.

  It is preferable that the content of the organic acid and the content ratio of the organic acid and the oxidizing agent in the polishing liquid are in the same range as the above-described polishing liquid for copper-based metal.

  The polishing liquid is allowed to contain an alkaline agent that adjusts the pH to 9 to 14 in addition to the organic acid and the oxidizing agent. As such an alkali agent, for example, potassium hydroxide and quinoline are suitable.

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

  The polishing process using 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 weight applied to the polishing pad with 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 comprising 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 abrasive grains such as silica particles, the load is preferably 150 to 1000 g / cm ² .

  In manufacturing another semiconductor device according to the present invention, a barrier layer is allowed to be formed on the insulating film including the groove and / or opening on the semiconductor substrate before the wiring material film is deposited. By forming such a barrier layer on the insulating film including the groove and / or opening, a buried wiring layer surrounded by the barrier layer is formed by depositing and etching back a wiring material film such as Cu. It becomes possible. As a result, it is possible to prevent contamination of the semiconductor substrate due to diffusion of Cu as a wiring material.

  The barrier layer is made of, for example, TiN, Ti, Nb, W, or a 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, a change in rotational torque of the table, a change in temperature of the polishing pad, or a change in pH of the polishing liquid supplied to the polishing pad in the polishing apparatus shown in FIG. Based on this, it is allowed to detect the end point of the polishing process. Further, it is allowed to detect the end point of the polishing process based on the change in the rotational 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 using the end point detection, a buried wiring layer flush with the surface of the insulating film can be reliably formed.

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

  The dilute hydrofluoric acid aqueous solution preferably has a hydrofluoric acid concentration of 0.05 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 oxide 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 solution exceeds 20%, when a silicon oxide film is used as the insulating film, the oxide film may be dissolved and removed. More preferably, the dilute hydrofluoric acid aqueous solution has a hydrofluoric acid concentration of 0.1 to 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 insulating film including the groove and / or the opening is formed. A wiring material film made of Cu or a Cu alloy is deposited thereon, and further contains a polishing liquid containing at least one organic acid selected from aminoacetic acid and amidosulfuric acid, an oxidizing agent, and water, for example, the polishing shown in FIG. The wiring material film is polished using an apparatus until the surface of the insulating film is exposed. As described above, the polishing liquid hardly etches the Cu film or the Cu alloy film when dipping the Cu film or the Cu alloy film, and is several times to several tens of times between the dipping 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 the surface thereof, so-called etch back is performed. Therefore, a buried wiring layer made of Cu or Cu alloy is formed in the groove and / or opening of the insulating film. It can be formed flush with the surface of the insulating film. Further, the wiring layer after the etch-back process is brought into contact with the polishing liquid, but 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, by treating the surface of the insulating film including the wiring layer after the etch back step with a dissolved ozone aqueous solution, the fine wiring material remaining on the insulating film, that is, converting Cu or Cu alloy into an oxide, It can oxidize and decompose pollutants such as organic matter. By treating with a dilute hydrofluoric acid solution after the treatment with such a dissolved ozone aqueous solution, the oxide of Cu or Cu alloy and 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, and a clean surface from which organic substances and residual wiring material on the surface of the insulating film are removed.

  Further, by adjusting the pH of the polishing liquid to 9 to 14 with an alkaline agent such as potassium hydroxide, the amount of organic acid such as aminoacetic acid contained in the polishing liquid can be increased even after the etch-back step. Etching of the wiring layer can be prevented by an oxide film having a high etching barrier property formed on the surface thereof. In addition, by increasing the content of the organic acid in the polishing liquid, it is possible to increase the polishing speed of the wiring material film, and as a result, it is possible to shorten the etch back time.

  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 etch back time can be shortened. In addition, since the generation of cracks and scratches in the wiring material film can be suppressed in the etch back process, a highly reliable embedded wiring layer can be formed in the groove and / or opening of the insulating film.

  Hereinafter, preferred embodiments of the present invention will be described in detail.

Example 1
First, as shown in FIG. 8A, a SiO ₂ film 22 having a thickness of, for example, 1000 nm as an interlayer insulating film is formed by CVD on a silicon substrate 21 on which diffusion layers such as source and drain (not shown) are formed on the surface. After the deposition, a plurality of grooves 23 having a depth of 500 nm and having a shape corresponding to the wiring layer were formed in the SiO ₂ film 22 by a photoetching technique. Subsequently, as shown in FIG. 8B, 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 sputtering deposition. Deposited.

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 supported on the load table on the turntable 1 by the support shaft 4 of the holder 5. Product name made by Nitta Co .; a polishing pad 2 made of SUBA800 is given a load of 300 g / cm ² , and the polishing liquid is supplied from the supply pipe 3 while rotating the turntable 1 and the holder 5 in directions opposite to each other at a speed of 100 ppm. The Cu film 25 and the barrier layer 24 supplied to the polishing pad 2 at a rate of 20 ml / min and deposited on the substrate 21 were polished until the surface of the SiO ₂ film 22 was exposed. Here, the polishing liquid is composed of pure water containing 0.1% by weight of aminoacetic acid, 13.0% by weight of hydrogen peroxide and 8% by weight of silica powder having an average particle size of 0.04 μm. On the other hand, a hydrogen peroxide of 130 was used. In the polishing step, the polishing liquid has an etching rate of zero when in contact with the Cu film, and the polishing rate at the time of polishing with the polishing pad is about 77 nm / min. It was. For this reason, in the polishing process, the convex Cu film 25 shown in FIG. 8B is preferentially polished from the surface in mechanical contact with the polishing pad, and the exposed barrier layer 24 is further polished. Etchback was done. As a result, as shown in FIG. 8C, the barrier layer 24 remains only in the groove 23 and the groove 23 covered with the barrier layer 24 is flush with the surface of the SiO ₂ film 22. A Cu wiring layer 26 was formed. Further, after the weight applied to the polishing pad 2 by the holder 5 of the polishing apparatus is released and the rotation of the turntable 1 and the holder 5 is stopped, the etching is performed even if the Cu wiring layer 26 comes into contact with the polishing liquid. Did not progress.

Further, in the polishing process (etchback process) by the polishing apparatus of FIG. 1 described above, the polishing liquid was sequentially collected from the polishing pad, and the change in pH was measured with a pH meter. FIG. 9 shows the pH change of the polishing liquid with respect to the polishing time. As is apparent from FIG. 9, the pH decreases once after the substrate is loaded by the holder and then increases again. When this pH rises, for example, when 8 minutes have elapsed after the start of weighting, the etching end point was determined. By setting the etch-back time by such endpoint detection, said SiO ₂ layer 22 flush with the surface of buried Cu wiring layer 26 can be reproducibly formed in the groove 23 of the SiO ₂ film 22.

In the polishing process (etchback process) by the polishing apparatus of FIG. 1 described above, the temperature change of the polishing pad and the voltage change of the drive motor of the turntable were measured by the 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 regarded as the etching end point. In FIG. 11 showing the voltage change, immediately after the start of weighting, the voltage of the drive motor of the turntable rises to a constant voltage, and the voltage rises again. The time when this voltage increased was regarded as the etching end point. 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 after the formation of the buried wiring layer was treated by immersing it in a dissolved ozone aqueous solution having an ozone concentration of 0.001% for 3 minutes, and then immersed in a dilute hydrofluoric acid aqueous solution having a hydrofluoric acid concentration of 10% for 90 seconds. . FIG. 12 is a spectrum diagram analyzed by XPS, the solid line is the surface spectrum 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 one-dot chain line is after the dilute hydrofluoric acid treatment Of the Cu wiring layer surface. As is apparent from FIG. 12, when the substrate after wiring formation is immersed in a dissolved ozone aqueous solution and processed, the signal of metal Cu seen immediately after the wiring formation disappears as shown by the dotted line, and the surface of the Cu wiring layer is oxidized. You can see that it has changed. Thereafter, when treated with a dilute hydrofluoric acid aqueous solution, the CuO signal seen in the treatment of the dissolved ozone aqueous solution disappeared as shown by the dashed line, and it can be seen that pure Cu was exposed on the surface of the Cu wiring layer. By treating with the dissolved ozone aqueous solution in this way, 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 in the SiO ₂ film 22 can be converted into an oxide. The decomposition product of organic matter and Cu oxide generated by the treatment with the dissolved ozone aqueous solution can be removed by the subsequent treatment with the dilute hydrofluoric acid aqueous solution, and also produced on the surface of the Cu wiring layer 26 by 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, it is possible to form the Cu wiring layer 26 buried with the depth in the groove 23 and the same thickness of the SiO ₂ film 22 according to the first embodiment in the SiO ₂ film 22 flush with the surface of the wiring The surface of the substrate 21 after the formation of the layer 26 could be planarized. Further, after the formation of the Cu wiring layer 26, the treatment of the dissolved ozone aqueous solution and the treatment of the dilute hydrofluoric acid aqueous solution are performed to clean the surface of the SiO ₂ film 22 and to form an oxide layer serving as a resistance component generated by oxidation of the polishing liquid. Since the removal is performed, it is possible to manufacture a highly reliable semiconductor device having an embedded Cu wiring layer having a low resistance inherent in Cu.

In Example 1, the polishing liquid used was pure water containing 0.86% by weight of amidosulfuric acid, 30% by weight of hydrogen peroxide, and 8% by weight of silica powder having an average particle size of 0.09 μm. as in example 1, it was possible to form a wiring layer embedded in the groove of the interlayer insulating SiO ₂ film on the insulating SiO ₂ film surface flush.

Example 2
First, as shown in FIG. 13A, a SiO ₂ film 22 having a thickness of, for example, 800 nm and a Si film having a thickness of 200 nm are formed on a silicon substrate 21 having a diffusion layer such as a source and drain (not shown) formed on the surface by CVD. _{After the 3} N ₄ film 27 is deposited in this order to form an interlayer insulating film, the Si ₃ N ₄ film 27 and the SiO ₂ film 22 have a shape corresponding to the wiring layer by a photoetching technique with a depth of 500 nm. A plurality of 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 sputtering 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 and the substrate is supported by the support shaft 4 of the holder 5 under the trade name of Rodel Nitta. ; the polishing pad 2 consisting of SUBA800 give a load of 300 g / cm ^2, the rate of the while rotating in opposite directions the turntable 1 and the holder 5 at a rate of 100ppm respectively, 20 ml / min polishing liquid from the supply pipe 3 Then, the Cu film 25 and the barrier layer 24 supplied to the polishing pad 2 and deposited on the substrate 21 were polished until the surface of the Si ₃ N ₄ film 27 was exposed. Here, the polishing liquid is composed of pure water containing 0.1% by weight of aminoacetic acid, 13.0% by weight of hydrogen peroxide and 8% by weight of silica powder having an average particle size of 0.04 μm. On the other hand, a hydrogen peroxide of 130 was used. In the polishing step, the polishing liquid has an etching rate of zero when in contact with the Cu film, and the polishing rate at the time of polishing with the polishing pad is about 77 nm / min. It was. For this reason, the convex Cu film 25 shown in FIG. 13B is polished preferentially from the surface that is in mechanical contact with the polishing pad, and the exposed barrier layer 24 is further polished so-called etch back. Was made.

As a result, as shown in FIG. 13C, the barrier layer 24 remains only in the groove 23 and is flush with the surface of the Si ₃ N ₄ film 27 in the groove 23 covered with the barrier layer 24. A buried Cu wiring layer 26 was formed. Further, after the weight applied to the polishing pad 2 by the holder 5 of the polishing apparatus is released and the rotation of the turntable 1 and the holder 5 is stopped, the etching is performed even if the Cu wiring layer 26 comes into contact with the polishing liquid. Did not progress.

Further, in the polishing process using a polishing liquid containing the silica particles as polishing abrasive grains, the interlayer insulating film is formed of the Si ₃ N ₄ film 27 having excellent polishing resistance on the surface side, so the etch back process It was possible to suppress film loss at the same time. For this reason, the semiconductor device provided with the interlayer insulation film which has a favorable dielectric strength voltage was able to be manufactured.

Example 3
First, as shown in FIG. 14A, a Si ₃ N ₄ film having a thickness of, for example, 1000 nm as an interlayer insulating film is formed by CVD on a silicon substrate 21 on which diffusion layers such as source and drain (not shown) are formed on the surface. After depositing 27, a plurality of grooves 23 having a depth of 500 nm and having a shape corresponding to the wiring layer were formed in the Si 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 sputtering deposition.

Next, the substrate 21 shown in FIG. 14B is held upside down on the substrate holder 5 of the polishing apparatus shown in FIG. 1 and the substrate is supported by the support shaft 4 of the holder 5 under the trade name of Rodel Nitta. ; the polishing pad 2 consisting of SUBA800 give a load of 400 g / cm ^2, the rate of the while rotating in opposite directions the turntable 1 and the holder 5 at a rate of 100ppm respectively, 20 ml / min polishing liquid from the supply pipe 3 The Cu film 25 supplied to the polishing pad 2 and deposited on the substrate 21 was polished until the surface of the Si ₃ N ₄ film 27 was exposed. Here, the polishing liquid comprises pure water containing 0.9% by weight of aminoacetic acid, 22.0% by weight of hydrogen peroxide and 3.7% by weight of potassium hydroxide, and is peroxidized with respect to aminoacetic acid 1 by weight. A pH of 10.5 with about 24 hydrogen was used. In the polishing step, the polishing liquid has an etching rate of zero when in contact with the Cu film, and the polishing rate at the time of polishing with the polishing pad is about 220 nm / min. It was. Therefore, the convex Cu film 25 shown in FIG. 14B is so-called etched back that is preferentially polished from the surface that is in mechanical contact with the polishing pad.

As a result, a buried Cu wiring layer 26 flush with the surface of the Si ₃ N ₄ film 27 was formed in the groove 23 as shown in FIG. Further, after the weight applied to the polishing pad 2 by the holder 5 of the polishing apparatus is released and the rotation of the turntable 1 and the holder 5 is stopped, the etching is performed even if the Cu wiring layer 26 comes into contact with the polishing liquid. Did not progress.

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} excellent Cu diffusion barrier properties. As a result, Cu does not diffuse from the Cu wiring layer 26 to the silicon substrate 21 through the interlayer insulating film. Therefore, the contamination of the silicon substrate 21 can be achieved without forming a barrier layer such as TiN on the inner surface of the groove 23. Could be avoided.

Example 4
First, as shown in FIG. 15A, a SiO ₂ film 33 having a thickness of, for example, 1000 nm as a first interlayer insulating film is formed by CVD on a p-type silicon substrate 32 having an n ⁺ -type diffusion layer 31 formed on the surface. Then, 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, a barrier layer 35 made of TiN having a thickness of 20 nm is deposited on the SiO ₂ film 33 including the via hole 34 by sputtering, and then the thickness of 1100 nm is deposited by sputtering. A Cu film 36 was deposited.

Next, the substrate 32 shown in FIG. 15B is held upside down in the holder 5 of the polishing apparatus shown in FIG. 1 described above, and the substrate is supported by the support shaft 4 of the holder 5 under the trade name of Rodel Nitta Co .; giving a load of 300 g / cm ² to the polishing pad 2 consisting of SUBA800, the turntable 1 and the holder 5 is rotated in the opposite directions at a rate of 100ppm respectively, the polishing liquid from the supply pipe 3 20 ml / min of rate The Cu film 36 and the barrier layer 35 supplied to the polishing pad 2 and deposited on the substrate 32 were polished until the surface of the SiO ₂ film 33 was exposed. Here, the polishing liquid comprises pure water containing 0.2% by weight of aminoacetic acid, 20.0% by weight of hydrogen peroxide, and 10% by weight of silica powder having an average particle size of 0.04 μm. On the other hand, a hydrogen peroxide of 100 was used. In the polishing step, the polishing liquid has an etching rate of zero when in contact with the Cu film, and the polishing rate at the time of polishing with the polishing pad is about 70 nm / min. It was. For this reason, the convex Cu film 36 shown in FIG. 15B is preferentially polished from the surface that is in mechanical contact with the polishing pad, and the exposed barrier layer 35 is further polished so-called etch back. Was made. As a result, as shown in FIG. 15C, the barrier layer 35 remains only in the via hole 34, and the via hole 34 covered with the barrier layer 35 has a Cu that is flush with the surface of the SiO ₂ film 33. A via fill 37 made of was formed. In addition, after the weight applied to the polishing pad 2 by the holder 5 of the polishing apparatus is released and the rotation of the turntable 1 and the holder 5 is stopped, the etching proceeds even if the via fill 37 comes into contact with the polishing liquid. I never did. Subsequently, the substrate after the formation of the via fill 37 is treated by immersing in a dissolved ozone aqueous solution having an ozone concentration of 0.002% for 3 minutes, and then immersed in a dilute hydrofluoric acid aqueous solution having a hydrofluoric acid concentration of 5% for 9 seconds. As a result, the surface of the SiO ₂ film 33 was cleaned.

Next, as shown in FIG. 16D, after depositing a Si ₃ N ₄ film 38 having a thickness of, for example, 800 nm as a second interlayer insulating film on the SiO ₂ film 33 including the via fill 37 by a CVD method, A plurality of grooves 39 having a depth of 400 nm and having a shape corresponding to a wiring layer were formed in the Si ₃ N ₄ film 38 by a photoetching technique. Further, a through hole 40 was formed in the groove 39 located on the via fill 37 by a photoetching technique. Subsequently, as shown in FIG. 16E, a Cu film 41 having a thickness of 900 nm was deposited on the Si ₃ N ₄ film 38 including the groove 39 and the through hole 40 by sputtering 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 substrate is supported by the support shaft 4 of the holder 5 under the trade name of Rodel Nitta. ; the polishing pad 2 consisting of SUBA800 give a load of 300 g / cm ^2, while rotating the turntable 1 and the holder 5 in opposite directions at 100ppm rate of each, similar to that used in the etch-back step described above A polishing liquid having a composition was supplied from the supply pipe 3 to the polishing pad 2 at a rate of 20 ml / min, and the Cu film 41 deposited on the substrate 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 FIG. 16E was so-called etched back that is preferentially polished from the surface that is in mechanical contact with the polishing pad. By such etch back, a buried Cu wiring layer 42 flush with the surface of the Si ₃ N ₄ film 38 was formed in the groove 39 as shown in FIG. At the same time, a buried Cu wiring layer 42 connected to the via fill 37 through the through hole 40 was formed. Further, after the weight applied to the polishing pad 2 by the holder 5 of the polishing apparatus is released and the rotation of the turntable 1 and the holder 5 is stopped, the etching is performed even if the Cu wiring layer 42 comes into contact with the polishing liquid. Did not progress.

  Therefore, according to the fourth embodiment, the first and second interlayer insulating films 33 and 39 are provided, and a via fill 37 that is flush with the surface of the first interlayer insulating film 33 is formed. In addition, a semiconductor device having a multilayer wiring structure in which a Cu wiring layer 42 flush with the surface thereof is formed and the surface is flattened can be manufactured.

Schematic which shows the polishing apparatus used for the grinding | polishing process of this invention. The amount of hydrogen peroxide in a polishing liquid composed of 0.1% by weight aminoacetic acid, hydrogen peroxide and water, the etching rate of the Cu film when immersed in the polishing liquid, and the polishing rate of the Cu film during polishing The characteristic view which shows the relationship. Sectional drawing which shows the state at the time of grind | polishing using a polishing apparatus, when Cu film | membrane which has an unevenness | corrugation is immersed in the polishing liquid of the composition which consists of aminoacetic acid, hydrogen peroxide, and water. The spectrum figure by XPS of the Cu film | membrane surface after immersion of the polishing liquid of this invention and after a grinding | polishing process before a process. The amount of hydrogen peroxide in a polishing liquid composed of 0.9% by weight of aminoacetic acid, hydrogen peroxide and water, the etching rate of the Cu film when immersed in the polishing liquid, and the polishing rate of the Cu film during the polishing process The characteristic view which shows the relationship. Characteristic showing the relationship between the amount of hydrogen peroxide in a polishing liquid composed of amidosulfuric acid, hydrogen peroxide and water, the etching rate of the Cu film when immersed in the polishing liquid, and the polishing rate of the Cu film during polishing Figure. The characteristic view which shows pH of the polishing liquid of this invention, and the thickness change of the oxide layer produced | generated on the Cu film | membrane surface. Sectional drawing which shows the manufacturing process of the semiconductor device in Example 1 of this invention. The characteristic view which shows the pH change of the polishing liquid in the grinding | polishing process (etch-back process) of Example 1. FIG. The characteristic view which shows the temperature change of polishing cloth in the grinding | polishing process (etch-back process) of Example 1. FIG. The characteristic view which shows the voltage change of the drive motor of the turntable in the grinding | polishing process (etch-back process) of Example 1. FIG. The spectrum figure obtained by XPS analysis of the surface immediately after Cu wiring layer formation in Example 1 of this invention, the Cu wiring layer surface after ozone treatment, and the Cu wiring layer surface after dilute hydrofluoric acid treatment. Sectional drawing which shows the manufacturing process of the semiconductor device in Example 2 of this invention. Sectional drawing which shows the manufacturing process of the semiconductor device in Example 3 of this invention. Sectional drawing which shows the manufacturing process of the semiconductor device in Example 4 of this invention. Sectional drawing which shows the manufacturing process of the semiconductor device in Example 4 of this invention.

Explanation of symbols

1 ... turntable 2 ... polishing pad, 3 ... supply pipe, 5 ... holder, 11,21,32 ... silicon substrate, 12,25,36,41 ... Cu film, 13 ... oxide layer, 22 and 33 ... SiO ₂ Film, 23, 39 ... groove, 24, 35 ... barrier layer, 26, 42 ... Cu wiring layer, 37 ... via fill.

Claims (10)

A polishing liquid for copper-based metals containing amidosulfuric acid, hydrogen peroxide and water,
The amide sulfuric acid, the is contained in an amount of in the polishing liquid 0.01 to 10 wt%, and the hydrogen peroxide relative to the amide acid 1 content ratio of the said amide acid hydrogen peroxide in a weight ratio The polishing liquid for copper-based metals, characterized in that is 20 or more.   Furthermore, the alkali agent for adjusting pH to 9-14 contains, The polishing liquid for copper-type metals of Claim 1 characterized by the above-mentioned.   The polishing slurry for copper-based metals according to claim 1 or 2, further comprising abrasive grains.   The said polishing abrasive is at least 1 sort (s) chosen from a silica, a zirconia, a cerium oxide, and an alumina, The polishing liquid for copper-type metals of Claim 3 characterized by the above-mentioned.   The said polishing abrasive is contained in the said polishing liquid in the quantity of 1-14 weight%, The polishing liquid for copper type metals of Claim 3 or 4 characterized by the above-mentioned. A substrate on which a copper film or a copper alloy film is formed is held by a substrate holder, the copper film or copper alloy film of this substrate is pressed against a polishing pad provided on the turntable, and the turntable and the substrate holder are rotated. And a polishing method for a copper-based metal that supplies a polishing liquid between the polishing pad and the copper film or copper alloy film of the substrate,
The polishing liquid contains amidosulfuric acid, hydrogen peroxide, and water,
The amide sulfuric acid, the is contained in an amount of in the polishing liquid 0.01 to 10 wt%, and the hydrogen peroxide relative to the amide acid 1 content ratio of the said amide acid hydrogen peroxide in a weight ratio A method for polishing a copper-based metal, characterized in that is 20 or more.   The copper-based metal polishing method according to claim 6, wherein the polishing liquid further contains abrasive grains.   The method for polishing a copper-based metal according to claim 7, wherein the polishing abrasive is at least one selected from silica, zirconia, cerium oxide, and alumina.   The method for polishing a copper-based metal according to claim 7 or 8, wherein the abrasive grains are contained in the polishing liquid in an amount of 1 to 14% by weight.   The method for polishing a copper-based metal according to any one of claims 6 to 9, wherein the polishing liquid further contains an alkali agent for adjusting the pH to 9 to 14.

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