JP3298628B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for removing a resist film and a deposit after performing dry etching using a resist film as a mask.

[0002]

2. Description of the Related Art In a process of manufacturing a semiconductor device, a process of forming a through hole or a wiring groove is performed by using a lithography technique. Usually, after a resist film is formed, dry etching is performed using the resist film as a mask, and then a resist film is formed. Is performed. Here, in order to remove the resist film, a wet process using a stripping solution is generally performed after plasma ashing. Various types of stripping solutions have been developed conventionally, and organic sulfonic acid-based stripping solutions containing alkylbenzenesulfonic acid as a main component, organic amine-based stripping solutions containing organic amines such as monoethanolamine as a main component, A hydrofluoric acid-based stripping solution containing hydrofluoric acid as a main component is known. Further, for example, a resist stripper in which a saccharide or an aromatic hydroxy compound is added as a corrosion inhibitor to a hydrofluoric acid-based stripper has been proposed.

However, in recent years, the miniaturization and speeding-up of semiconductor devices have been increasingly advanced, and various processes that have not been used conventionally have been adopted. Have to meet different requirements.

[0004] For example, due to a demand for a high-speed semiconductor device, a low-resistance material such as copper has been used as a wiring material. However, in the copper wiring layer forming process, it is necessary to remove a residue that has not been generated in the conventional manufacturing process. In addition, copper is inferior in corrosion resistance to a chemical solution as compared with a conventional wiring material such as aluminum, and therefore, it is necessary to suppress corrosion of copper wiring due to a resist stripping solution. These points will be described below by taking a step of forming an interlayer connection plug on a copper wiring by a single damascene process as an example.

First, a buried copper wiring is formed on a silicon substrate as shown in FIG. After a silicon oxide film 1, a silicon nitride film 2, and a silicon oxide film 3 are formed on a semiconductor substrate (not shown) on which elements such as transistors are formed, a copper wiring 2 is formed using a known damascene process.
0 is formed. After forming the silicon nitride film 6 and the silicon oxide film 21 thereon, a resist film 22 patterned in a predetermined shape is further provided thereon. As the resist material, for example, a chemically amplified resist is used.

Next, the silicon oxide film 21 is dry-etched using the resist 22 as a mask until the silicon nitride film 6 is exposed to form a through hole (FIG. 13).
(B)). The opening diameter of the through hole is about 0.2 μm. As an etching gas, a gas that can etch a silicon oxide film faster than a silicon nitride film is used. After the etching, a deteriorated resist layer 24 is formed in the opening of the resist film 22.

Although the silicon nitride film 6 is used as a copper diffusion preventing film, it also has a function as an etching stopper film. However, as shown in FIG. 13B, the dry etching may not be stopped on the silicon nitride film 6 with good controllability. This is for the following reason.

Generally, through holes having various opening diameters are formed on a substrate. However, in a hole having a small opening diameter, the progress of etching is slowed by a microloading effect. For this reason, it is necessary to provide a certain degree of over-etching time for the etching for forming the through-hole, and this causes the silicon nitride film to be etched and a part of the copper wiring to be exposed. Further, for example, when a concave portion called dishing is formed on the upper surface of the copper wiring 20, a thin film portion of the silicon nitride film is generated, and the silicon nitride film is etched at this portion, and a part of the copper wiring may be exposed. These phenomena become more remarkable as the aspect ratio of the opening increases.

If the silicon nitride film 6 is formed thick in the step shown in FIG. 13A, a part of the copper wiring 20 is formed even when the silicon oxide film 21 is over-etched and the silicon nitride film 6 is etched. Exposure can be prevented. However, in such a case, the line capacitance of the adjacent copper wiring becomes large and the high-speed operation of the semiconductor element is hindered. Therefore, it is not preferable to form the silicon nitride film 6 thick.

After completion of the etching, oxygen plasma ashing is performed, and further, a wet process is performed with a resist stripper to remove the resist 22.

Thereafter, the etching of the silicon nitride film 6 is performed by changing the etching gas from the above-mentioned etching. Thereafter, inside the through hole, a barrier metal film 26 and a tungsten film 27 in which Ti and TiN are laminated in this order.
Film is formed, and then chemically and mechanically polished (Chemical Mechani
An interlayer connection plug is formed by flattening by cal polishing (CMP) (FIG. 13C).

However, the above process has the following problems when the resist is stripped in the state shown in FIG.

As shown in FIG. 13B, a silicon oxide film 21 is formed.
Is etched, a deteriorated resist layer 24 is formed in the opening of the resist 22. The deteriorated resist layer 24 is considered to have as its main component a reaction product of various film materials formed on the substrate and the etching gas. In this process, the resist modified layer 24 is formed by reacting the silicon nitride film or copper film with the etching gas. It is believed that it also includes reaction products. If the deteriorated resist layer 24 remains, a failure in forming a barrier metal film or the like occurs during the subsequent formation of the upper wiring, which causes a decrease in yield. Further, a part of the deteriorated resist layer 24 may fall into the through-hole and be buried in a subsequent step, so that the burying failure of the metal film in the hole may occur. Therefore, in the stripping solution treatment step, it is necessary to almost completely remove the deteriorated resist layer 24. However, this layer is generally difficult to remove, and after the stripping solution treatment, as shown in FIG. 24 may remain. In order to prevent such residual resist deteriorated layer 24 from remaining, it is necessary to use a stripping solution having a strong stripping action.
In this case, there arises a problem that the corroded portion 28 is generated on the exposed surface of the copper wiring 20 as shown in FIG. The problem of wiring corrosion has not been a serious problem in the case of conventional aluminum-based wiring. However, in the case of using copper, which corrodes more easily than aluminum or the like, it is important to take measures against the corrosion problem.

[0014] With the miniaturization of elements, the thickness of the copper film is now being reduced, and even if the surface layer is slightly altered, the wiring resistance and the contact resistance are significantly increased. Further, there may be a problem that peeling occurs between the copper film and the barrier metal film in the interlayer connection recess. Therefore, when a corrosive metal such as copper is used as a wiring material, prevention of corrosion of the metal is a very important technical problem.

As described above, with the conventional resist stripping technique, it is difficult to effectively remove a layer which is difficult to remove such as a deteriorated resist layer while preventing deterioration of a corrosive metal film such as a copper film. Met.

Further, in order to effectively remove the difficult-to-remove layer such as the deteriorated resist layer as described above, it is necessary to enhance the peeling action of the stripping solution. Increase. Therefore, it is necessary to increase the effect of preventing corrosion of copper in correspondence with increasing the peeling action.

Conventionally, an anticorrosive such as benzotriazole (BTA) has been added to a stripping solution.
However, it has been difficult to obtain a sufficient anticorrosion effect when the release effect of the release liquid is enhanced as described above.

Further, the conventional anticorrosive agent tends to vary its anticorrosive performance depending on the temperature, and there is still room for improvement in this respect. The resist stripping process using a stripper is performed by immersing a plurality of wafers in a bath filled with the stripper for a predetermined time. Here, if a temperature control mechanism is provided in a stripping apparatus having a tank filled with a stripping solution, the size of the stripping apparatus becomes large and the price becomes high. For this reason, a stripping apparatus using a stripping solution that can be processed at room temperature is not usually provided with a temperature control mechanism. Under such circumstances, the temperature of the stripping solution changes depending on the temperature around the area where the stripping device is installed. The temperature of the entire room in which a semiconductor device is manufactured is controlled to about 23 ° C., but the temperature may be high depending on the location. For example,
Various semiconductor manufacturing devices are arranged around the place where the peeling device is installed.These devices have a heat source such as a heating or cooling device, and heat is released from these devices to the outside of the device. ing. If only the stripping device is in the air-conditioned room, the temperature of the resist stripping solution falls within about 23 to 25 ° C. even if the resist stripping process is performed. However, if there is a heat source around the stripper, the temperature of the resist stripper may exceed 30 ° C. Further, the temperature of the stripping solution differs to a certain extent depending on the position where the wafer is arranged. When such temperature fluctuations occur, even if an anticorrosive is added to the conventional stripping solution, fluctuations in anticorrosion performance due to temperature are inevitable.
When a resist stripping process is performed on a substrate on which a corrosive metal film such as copper is formed using a conventional stripping solution, corrosion of the metal film may occur on some wafers.

Further, when the resist is stripped by a conventional method, residues may adhere to the substrate surface after the resist is stripped and then rinsed with pure water. This residue is considered to be a component contained in the stripping solution or a reaction product between the component and the resist film. However, if such a residue is generated, a film formation failure occurs in a subsequent film formation process. And so on.

[0020]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to prevent the deterioration of a corrosive metal film such as a copper film and prevent the removal of a hardly removable layer such as a deteriorated resist layer. It is an object of the present invention to provide a resist stripping technique that efficiently removes rust, has low temperature dependence of anticorrosion performance, and has little residue after rinsing.

[0021]

According to the present invention for solving the above-mentioned problems, (a) after forming a copper-based metal film on a semiconductor substrate, forming an insulating film thereon, and further forming a resist thereon Forming a film, (b) performing dry etching using the resist film as a mask to form a concave portion reaching the copper-based metal film in the insulating film, and (c) forming at least a part of the resist film. A step of performing a peeling treatment;
A method of manufacturing a semiconductor device, comprising: a step of performing a wet treatment using a resist stripping solution containing a benzotriazole derivative; and (e) a step of embedding a conductive film in the recess.

According to the present invention, (a) after forming a copper-based metal film on a semiconductor substrate, a copper diffusion preventing film and an insulating film are formed thereon in this order, and a resist film is further formed thereon. Forming; (b) performing a dry etching using the resist film as a mask to form a concave portion reaching the copper diffusion preventing film in the insulating film; and (c) removing at least a part of the resist film. (D) performing a wet treatment using a resist stripping solution containing a benzotriazole derivative, and (e) embedding a conductive film in the concave portion after removing the copper diffusion preventing film. And a method of manufacturing a semiconductor device characterized by including the following.

When dry etching is performed using the resist film as a mask, a deteriorated resist layer is formed on the side wall of the resist film at the opening of the resist. In order to remove this, it is necessary to enhance the stripping action of the stripper, but in this case, corrosion of the copper-based metal film becomes a problem. Therefore, the present invention
This problem is solved by performing a wet process using a resist stripper containing a benzotriazole derivative.

In the method for manufacturing a semiconductor device,
It is desirable that the wet process of the step (d) remove the deteriorated resist layer generated by the dry etching of the step (b).

Further, between the steps (c) and (d),
It is desirable to include a step of removing an etching residue attached to the inner wall of the recess. The etching residue is formed by the dry etching in the step (b). Conventionally, the etching residue is often performed at the same time as the removal of the resist residue, and a special treatment for removing the etching residue is rarely performed. The step of removing the etching residue can be performed, for example, by a treatment using an amine-containing liquid. This step of removing the etching residue is preferably performed before wet treatment using a resist stripping solution containing a benzotriazole derivative. By doing so, the etching residue and the altered layer of the resist can be more efficiently removed.

Further, according to the present invention, in the step (e), after the copper diffusion preventing film is removed by dry etching,
The etching residue generated during this dry etching is
It is preferable to remove by a treatment using a choline-containing solution. Since this etching residue contains a reaction product between the copper diffusion preventing film and the copper-based metal film provided thereunder and the etching gas, it is difficult to remove the etching residue with a normal stripping solution. If a treatment using a choline-containing solution is performed on such an etching residue, efficient removal can be achieved.
Therefore, by performing the treatment with the choline-containing solution in combination with the above-described treatment with the resist stripping solution containing the benzotriazole derivative, the damaged copper-based metal film is not damaged, and the damaged resist layer, holes (through holes) or wirings are not damaged. Residues adhering to the grooves can be efficiently removed, and a wiring structure having excellent performance can be realized.

As the choline-containing solution, for example, a solution in which choline is dissolved in an organic solvent is preferably used. In this case, the choline content is preferably 1 to 60% by weight, more preferably 20 to 50% by weight.

Further, according to the present invention, (a) after forming a copper-based metal film on a semiconductor substrate, a copper diffusion preventing film is formed thereon;
Forming a multilayer film in which a first insulating film, an etching stopper film, and a second insulating film are laminated in this order, and further forming a first resist film thereon; Perform dry etching using a resist film as a mask, in the multilayer film, provided a hole reaching the copper-based metal film,
Removing the first resist film, (c) forming a second resist film on the second insulating film, and (d) performing dry etching using the second resist film as a mask,
Forming a wiring groove reaching the etching stopper film in the second insulating film; (e) removing at least a portion of the second resist film; and (f) removing the resist containing a benzotriazole derivative. A method of manufacturing a semiconductor device, comprising: performing a wet process using a liquid; and (g) burying a conductive film in the hole and the wiring groove.

Further, according to the present invention, (a) after forming a copper-based metal film on a semiconductor substrate, a copper diffusion preventing film is formed thereon;
Forming a multilayer film in which a first insulating film, an etching stopper film, and a second insulating film are laminated in this order, and further forming a first resist film thereon; Dry etching using the resist film as a mask to form a hole in the multilayer film reaching the copper diffusion preventing film, and thereafter removing the first resist film; and (c) forming a second resist film on the second insulating film. Forming a second resist film; (d) performing dry etching using the second resist film as a mask to form a wiring groove in the second insulating film reaching the etching stopper film; A step of stripping at least a part of the second resist film, a step of (f) performing a wet process using a resist stripping solution containing a benzotriazole derivative, and (g) removing the copper diffusion preventing film. The hole and the wiring Burying a conductive film inside of
And a method for manufacturing a semiconductor device, comprising:

When dry etching is performed using the resist film as a mask, a deteriorated resist layer is formed on the side wall of the resist film at the opening of the resist. In order to remove this, it is necessary to enhance the stripping action of the stripper, but in this case, corrosion of the copper-based metal film becomes a problem. Therefore, the present invention
This problem is solved by performing a wet process using a resist stripper containing a benzotriazole derivative.

In the above method for manufacturing a semiconductor device,
It is desirable that the wet process of the step (f) remove the deteriorated resist layer caused by the dry etching of the step (d).

Further, between the step (e) and the step (f),
It is desirable to include a step of removing an etching residue attached to the inner wall of the recess. The etching residue is formed by, for example, dry etching performed before. Conventionally, the etching residue is often performed at the same time as the removal of the resist residue, and a special treatment for removing the etching residue is rarely performed. The step of removing the etching residue can be performed, for example, by a treatment using an amine-containing liquid. This step of removing the etching residue is preferably performed before wet treatment using a resist stripping solution containing a benzotriazole derivative. By doing so, the etching residue and the altered layer of the resist can be more efficiently removed.

Further, according to the present invention, in the step (g), after the copper diffusion preventing film is removed by dry etching,
The etching residue generated during this dry etching is
It is preferable to remove by a treatment using a choline-containing solution. Since this etching residue contains a reaction product between the copper diffusion preventing film and the copper-based metal film provided thereunder and the etching gas, it is difficult to remove the etching residue with a normal stripping solution. If a treatment using a choline-containing solution is performed on such an etching residue, efficient removal can be achieved.
Therefore, by performing the treatment with the choline-containing solution in combination with the above-described treatment with the resist stripping solution containing the benzotriazole derivative, the damaged copper-based metal film is not damaged, and the damaged resist layer, holes (through holes) or wirings are not damaged. Residues adhering to the grooves can be efficiently removed, and a wiring structure having excellent performance can be realized.

As the choline-containing solution, for example, a solution in which choline is dissolved in an organic solvent is preferably used. In this case, the choline content is preferably 1 to 60% by weight, more preferably 20 to 50% by weight.

In the method of manufacturing a semiconductor device, the multilayer film formed in step (a) includes not only a copper diffusion prevention film, an etching prevention film, and the first and second insulating films but also other films. You can go out.

[0036]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The copper-based metal film in the present invention is:
A film containing copper as a main component and having a copper content of 90% by weight or more.

The step of stripping at least a part of the (second) resist film in the present invention is an ashing process using oxygen plasma or the like, or a process using a resist stripping solution. When the ashing process is adopted, a process can be taken in which most of the resist film is removed by ashing, and then the resist residue and the altered layer of the resist are removed with a resist stripper. If you do this,
Since the wet processing time with the stripping solution can be reduced, the corrosion of the copper-based metal film can be further prevented. on the other hand,
When the treatment with the resist stripping solution is adopted, an advantage of preventing the degree of oxidation of the copper-based metal film or the interlayer insulating film can be obtained by appropriately selecting the type of the stripping solution. When this method is adopted, a process of removing most of the resist film with the first resist stripper, and then removing the resist residue and the altered layer of the resist with the second resist stripper is used. The first and second resist stripping solutions may be the same or different.

In the present invention, the thickness of the copper wiring is preferably 350 nm or less, more preferably 300 nm or less. Although there is no particular lower limit, for example, 50
nm or more. If the film thickness is too large, the parasitic capacitance between adjacent wirings increases, crosstalk occurs, and it is difficult to achieve high-speed operation. The main purpose of using the copper wiring is to realize a higher-speed operation than the conventional aluminum wiring.
It is desirable that the thickness be not more than 00 nm. However, when the thickness of the copper wiring is reduced, the thickness of the corroded layer relative to the entire copper wiring layer becomes relatively large, and an increase in wiring resistance due to corrosion of the copper surface becomes a particular problem. According to the present invention, such corrosion can be effectively prevented, so that high-speed operation can be realized by reducing the thickness of the copper wiring, and the problem of the increase in the wiring resistance can be solved.

As the benzotriazole derivative in the present invention, those having a structure represented by the following general formula (1) are preferably used.

[0040]

Embedded image

Here, R ₁ and R ₂ represent a hydroxyalkyl group or an alkoxyalkyl group having 1 to 3 carbon atoms, and R ₃ and R ₄ each independently represent a hydrogen atom or a 1 to 3 carbon atom. Represents an alkyl group. R ₁ and R ₂ may be the same or different, and similarly, R ₃ and R ₄ may be the same or different.

The anticorrosive effect of the above anticorrosive agent on copper is several orders of magnitude better than that of benzotriazole (BTA) represented by the following formula (2). There is little generation of things.

[0043]

Embedded image

As the benzotriazole derivative represented by the above general formula (1), Irgamet series, specifically Irgamet 42, commercially available from Ciba Specialty Chemicals is preferably used. If such a benzotriazole derivative is used, particularly excellent anticorrosion performance can be obtained.

The Irgamet 42 is (2,2'-
[[(Methyl-1H-benzotriazol-1-yl)
Methyl] imino] bis-ethanol) and has a structure as shown in the following formula (3).

[0046]

Embedded image

The upper limit of the amount of the benzotriazole derivative is preferably 10% by weight, particularly preferably 5% by weight.
The lower limit is preferably 0.1% by weight, particularly preferably 0.5% by weight. With such an amount, more favorable anticorrosion performance can be realized.

The resist stripping solution used in the present invention preferably contains a salt of hydrofluoric acid and a base containing no metal ions. By including such a component, a layer that is difficult to remove such as a deteriorated resist layer can be efficiently removed. As such a salt, for example, ammonium fluoride or the like can be used.

The salt of a base containing no metal ion with hydrofluoric acid may be, for example, a commercially available hydrogen fluoride of 50 to 60.
It can be produced by adding a base containing no metal ion to a concentration of 5% hydrofluoric acid so that the pH becomes about 5 to 8.

The upper limit of the amount of the salt of the base containing no metal ion and hydrofluoric acid is preferably 30% by weight, particularly preferably 20% by weight. The lower limit is preferably 0.2% by weight, and particularly preferably 0.5% by weight. With such a compounding amount, a layer which is difficult to remove such as a deteriorated resist layer can be more efficiently removed while maintaining good anticorrosion performance.

The above-mentioned salt of hydrofluoric acid and a base containing no metal ion can efficiently remove a difficult-to-remove layer such as a deteriorated resist layer, but has a strong corrosive property to a copper-based metal film. Therefore, when a salt of the above hydrofluoric acid and a base containing no metal ion is used, it is desirable to use, for example, a benzotriazole derivative represented by the above general formula (1) in combination. By using these together, it becomes possible to more effectively prevent the deterioration of the easily corroded metal film such as the copper film and more efficiently remove the difficult-to-remove layer such as the deteriorated resist layer. .

Various resist films can be used in the present invention. For example, (i) a positive resist containing a naphthoquinonediazide compound and a novolak resin, (ii) a compound that generates an acid upon exposure, a compound that is decomposed by an acid to increase the solubility in an aqueous alkali solution, and a positive resist containing an alkali-soluble resin. Resist, (iii) a compound capable of generating an acid upon exposure, a positive resist containing an alkali-soluble resin having a group that is decomposed by the acid and increases in solubility in an alkaline aqueous solution, (iV)
A negative resist containing a compound generating an acid by light, a crosslinking agent and an alkali-soluble resin can be used.

[0053]

Embodiment 1 This embodiment is an example in which the present invention is applied to a so-called dual damascene process. Hereinafter, the process will be described with reference to FIGS. First, as shown in FIG. 1A, a buried copper wiring is formed on a silicon substrate. A silicon oxide film 1, a silicon nitride film 2, and a silicon oxide film 3 are formed on a semiconductor substrate (not shown) on which elements such as transistors are formed.
Was formed, a copper wiring composed of the Ta film 4 and the copper film 5 was formed using a known damascene process. The copper film was formed by a plating method. After forming the copper wiring, a silicon nitride film 6 having a thickness of about 50 nm, a silicon oxide film 7 having a thickness of about 500 nm, and a silicon oxynitride film 8 having a thickness of about 50 nm are formed thereon.
A silicon oxide film 9 having a thickness of about 300 nm was formed in this order (FIG. 1B). Further, a resist film 12 patterned in a predetermined shape was provided thereon (FIG. 2).
(A)). PEX4 (manufactured by Tokyo Ohka Kogyo Co., Ltd.), which is a positive resist material for KrF, was used as a resist material.

Next, the silicon oxide film 9, the silicon oxynitride film 8 and the silicon oxide film 7 are dry-etched using the resist 12 as a mask until the silicon nitride film 6 is exposed, thereby forming through holes (FIG. 2B). ). At this time, as shown in FIG.
May not stop. The opening diameter of the through hole was about 0.2 μm. As an etching gas, a gas capable of etching a silicon oxide film faster than a silicon nitride film was used. At this time, the resist residue 10 adheres to the inner wall of the hole and a deteriorated resist layer 14 is formed at the opening of the resist film 12.

After the resist film 12 was removed from the state shown in FIG. 2B by oxygen plasma ashing, a wet treatment was performed using a resist stripper containing an aliphatic amine and a benzotriazole derivative. Processing temperature is 90
C. and the treatment time was 20 minutes. Subsequently, NO. A wet treatment was performed using the resist stripping solution of No. 1. The wet treatment was performed by immersing in the above-mentioned resist stripping solution at 23 ° C. for 10 minutes. With this process,
The deteriorated resist layer 14 is removed. Note that N
O. The wet treatment using the first resist stripping solution can be omitted in some cases.

[0056]

[Table 1] * In the table, Irgamet 42 is (2,2 ′-[[(methyl-1H-benzotriazol-1-yl) methyl] methyl).
[Imino] bis-ethanol).

Next, an antireflection film 30 made of a resist material was applied so as to fill the inside of the through hole (FIG. 2C). Thereafter, a resist film 15 having an opening wider than the width of the through hole was provided (FIG. 3).
(A)). The resist material used was PEX4 described above.
Dry etching was performed again using the resist film 15 as a mask to form a groove in the silicon oxide film 9 (FIG. 3).
(B)). In this sectional view, a narrow portion is a through hole, and a wide portion is a wiring groove. After the etching is completed, a deteriorated resist layer 16 is formed in the opening of the resist film 15.

Next, after the resist film 15 was removed by oxygen plasma ashing (FIG. 3C), a wet treatment was performed using a resist stripping solution containing an aliphatic amine and a benzotriazole derivative. Processing temperature is 90 ° C,
The processing time was 20 minutes.

Subsequently, NO. A wet treatment was performed using the resist stripping solution of No. 1. The wet treatment was performed by immersing in the above-mentioned resist stripping solution at 23 ° C. for 10 minutes. By this processing, the deteriorated resist layer 1
6 is removed.

After that, the silicon nitride film 6 was removed by etching by changing the etching gas. At this time, the etching residue 35 adheres to the side wall of the through hole. Next, a wet treatment was performed using a resist stripping solution containing an aliphatic amine and a benzotriazole derivative. The processing temperature was 90 ° C. and the processing time was 20 minutes. Subsequently, in order to remove the etching residue 35, a wet treatment was performed using a stripping solution (choline content: 30% by weight) in which choline was dissolved in an organic solvent. The processing temperature was 70 ° C., and the processing time was 20 minutes. The state after the processing is shown in FIG. Subsequently, the Ta film 17 and the copper film 1 are so filled as to fill the trench.
8 was formed, and the surface was flattened by CMP to produce a wiring structure (FIG. 4C).

Thereafter, an upper layer wiring and the like were further formed, and a multilayer wiring structure in which copper wiring was laminated in multiple layers was manufactured. The obtained multilayer wiring structure was excellent in high-speed operation and exhibited good performance.

The following SEM (scanning electron microscope) was performed using a silicon wafer which had been subjected to the same process as described above.
Observations were made. SEM observation (1): From the stage of FIG.
Wet treatment was performed using the resist stripping solution of No. 1 and, after the treatment was completed, appearance observation and cross-sectional observation by SEM were performed. SEM observation (2): From the stage of FIG. 4 (a), a wet treatment using a choline-containing stripper was performed, and after the treatment was completed (the state of FIG. 4 (b)), external appearance observation and cross-sectional observation by SEM were performed. went.

As a result, in each evaluation, the resist and the resist residue were almost completely removed.
Further, no corrosion of the exposed portion of the copper film was observed.

In the present embodiment, since the present invention is applied to the wiring groove forming process, it becomes more difficult to remove the altered resist layer as compared with the case where the present invention is applied to the hole forming etching process. The deteriorated resist layer formed after the hole formation etching has a form as shown in FIG. That is, the affected layer 5 is formed so as to surround the hole 53.
4 remain. On the other hand, the deteriorated resist layer 51 generated after the etching for forming the wiring groove 50 has a form as shown in FIG. That is, the wall-shaped cured layer extends along the wiring groove 50. Therefore, the deteriorated resist layer generated after the etching for forming the wiring groove generates a larger amount of a hardened layer and is more difficult to remove.
Further, in this case, a groove is formed by further etching the upper silicon oxide film in a state where the silicon nitride film (copper diffusion preventing film) covering the copper wiring 52 is exposed.
The silicon nitride film is more etched than when the holes are formed (FIG. 5B), and the area where the copper wiring is exposed increases. For this reason, it is necessary to prevent corrosion of the copper wiring 52 more sufficiently, and a high level of anticorrosion performance is required for the stripping liquid. From the results of this example, it was confirmed that according to the method of manufacturing a semiconductor device of the present invention, the above-mentioned difficult-to-remove wall-shaped deteriorated resist layer can be efficiently removed while preventing corrosion of copper wiring.

Comparative Example 1 A process similar to that of Example 1 was performed except for the following points. From the stage of FIG. From the stage of FIG. 4 (a), the wet treatment using the choline-containing stripping solution was not performed, and only the wet processing using the aliphatic amine-containing resist stripping solution was performed. Performed points The following SEM observations (1) and (2) were performed on the silicon wafer subjected to the above process. SEM observation (1): From the stage of FIG.
Wet processing was performed using the resist stripping solution of No. 2, and after the processing was completed, external appearance observation and cross-sectional observation were performed by SEM. SEM observation (2): From the stage of FIG. 4 (a), wet treatment using a resist stripper containing an aliphatic amine and a benzotriazole derivative was performed, and the treatment was completed (the state of FIG. 4 (b)). Was used to observe the external appearance and the cross section by SEM.

As a result, in SEM observation (1),
Although the residue and the like were almost completely removed, some corrosion was observed in the exposed portion of the copper film. Further, in the SEM observation (2), although corrosion of the exposed portion of the copper film was not recognized, many residues remained.

Comparative Example 2 The same process as in Example 1 was performed except for the following points. From the stage of FIG. The point of performing the wet treatment using the resist remover of No. 3 From the stage of FIG. 4A, the wet treatment using the choline-containing remover was not performed, and only the wet treatment using the aliphatic amine-containing resist remover was performed. Performed points The following SEM observations (1) and (2) were performed on the silicon wafer subjected to the above process. SEM observation (1): From the stage of FIG.
A wet treatment was performed using the resist stripper of No. 3, and after the treatment was completed, the external appearance and the cross section were observed by SEM. SEM observation (2): From the stage of FIG. 4 (a), wet treatment using a resist stripper containing an aliphatic amine and a benzotriazole derivative was performed, and the treatment was completed (the state of FIG. 4 (b)). Was used to observe the external appearance and the cross section by SEM.

As a result, in SEM observation (1),
Although the residue and the like were almost completely removed, some corrosion was observed in the exposed portion of the copper film. Further, in the SEM observation (2), although corrosion of the exposed portion of the copper film was not recognized, many residues remained.

Example 2 From the stage of FIG. When performing the wet treatment using the resist stripping solution of No. 1, the temperature of the stripping solution is
The same process as in Example 1 was performed except that the temperature was changed to ° C. NO. When the external appearance observation and the cross-sectional observation were performed by SEM in a state where the wet treatment with the resist stripper was completed, it was confirmed that the resist and the resist residue were almost completely removed. Further, no corrosion of the exposed portion of the copper film was observed.

Comparative Example 3 When wet processing is performed from the stage of FIG.
O. The same process as in Example 2 was performed except that the resist stripping solution of No. 2 was used. NO. SEM after completion of the wet process using the resist stripper
As a result of observation of the external appearance and cross-section, the residue and the like were almost completely removed, but corrosion of the exposed portion of the copper film was observed.

Comparative Example 4 When the wet processing is performed from the stage of FIG.
O. A process similar to that of Example 2 was performed except that the resist stripping solution of No. 3 was used. NO. SEM after the wet treatment with the resist stripper of Step 3 is completed
As a result of observation of the external appearance and cross-section, the residue and the like were almost completely removed, but corrosion of the exposed portion of the copper film was observed.

Embodiment 3 This embodiment is an example of a dual damascene process as in Embodiment 1, but differs from Embodiment 1 in that the thickness of the silicon nitride film on the copper wiring is reduced. In the present embodiment, the silicon nitride film has no function as an etching stopper film, and is provided for the purpose of preventing the diffusion of the copper film. Hereinafter, the process will be described with reference to FIGS.

First, an embedded copper wiring is formed on a silicon substrate as shown in FIG. After a silicon oxide film 1, a silicon nitride film 2, and a silicon oxide film 3 are formed on a semiconductor substrate (not shown) on which elements such as transistors are formed, a Ta film 4 and a copper film 5 are formed using a known damascene process. Was formed. The copper film was formed by a plating method. After forming the copper wiring, a film thickness of about 20
6 nm, a silicon oxide film 7 having a thickness of about 550 nm, a silicon oxynitride film 8 having a thickness of about 20 nm, and a silicon oxide film 9 having a thickness of about 300 nm were formed in this order (FIG. 6B). . Further, a resist film 12 patterned in a predetermined shape was provided thereon (FIG. 7A). PEX4 (manufactured by Tokyo Ohka Kogyo Co., Ltd.), which is a positive resist material for KrF, was used as a resist material.

Next, the silicon oxide film 9, the silicon oxynitride film 8 and the silicon oxide film 7 were dry-etched using the resist 12 as a mask until the silicon nitride film 6 was exposed, thereby forming through holes (FIG. 7B). ). The opening diameter of the through hole was about 0.2 μm. As an etching gas, a gas capable of etching a silicon oxide film faster than a silicon nitride film was used. At this time, the resist residue 10 adheres to the inner wall of the hole and a deteriorated resist layer 14 is formed at the opening of the resist film 12.

After the resist film 12 was removed from the state shown in FIG. 7B by oxygen plasma ashing, a wet treatment was performed using a resist stripper containing an aliphatic amine and a benzotriazole derivative. Processing temperature is 90
C. and the treatment time was 20 minutes. By this processing, the etching residue 10 is removed. Subsequently, Table 1 of Example 1
NO. A wet treatment was performed using the resist stripping solution of No. 1. Wet treatment is performed on the above resist stripper,
This was performed by immersion at 23 ° C. for 10 minutes. By this processing, the deteriorated resist layer 14 is removed. Note that the NO. The wet treatment using the first resist stripping solution can be omitted in some cases.

Thereafter, a resist film 15 having an opening wider than the width of the through hole was provided. The resist material used was PEX4 described above. Dry etching was performed again using the resist film 15 as a mask to form a groove in the silicon oxide film 9 (FIG. 8A). In the sectional view of FIG. 8A, a narrow portion is a through hole, and a wide portion is a wiring groove. After the etching is completed, the etching residue 10 adheres to the inner wall of the through hole, and a deteriorated resist layer 16 is formed at the opening of the resist film 15.

Next, after the resist film 15 was removed by oxygen plasma ashing (FIG. 8B), a wet treatment was performed using a resist stripping solution containing an aliphatic amine and a benzotriazole derivative. Processing temperature is 90 ° C,
The processing time was 20 minutes. By this processing, the etching residue 10 is removed (FIG. 8C). Subsequently, the NO. A wet treatment was performed using the resist stripping solution of No. 1. The wet treatment was performed by immersing in the above-mentioned resist stripping solution at 23 ° C. for 10 minutes. By this process, the deteriorated resist layer 16 is removed (FIG. 9A).

Subsequently, the Ta film 1 is formed so as to fill the trench.
7 and a copper film 18 were formed, and the surface was flattened by CMP to produce a wiring structure (FIG. 9B).

Thereafter, an upper layer wiring and the like were further formed, and a multilayer wiring structure in which copper wiring was laminated in multiple layers was manufactured. The obtained multilayer wiring structure was excellent in high-speed operation and exhibited good performance.

Using a silicon wafer that had been subjected to the same process as above, the silicon wafer at the stage where the above-mentioned wet processing was completed (FIG. 9 (a)) was subjected to external observation and cross-sectional observation by SEM. As a result, the resist and the resist residue were almost completely removed, and no corrosion of the exposed portion of the copper film was observed.

Embodiment 4 This embodiment is an example in which an interlayer connection plug on a copper wiring is formed by a single damascene process.

First, a buried copper wiring was formed on a silicon substrate as shown in FIG. After a silicon oxide film 1, a silicon nitride film 2, and a silicon oxide film 3 are formed on a semiconductor substrate (not shown) on which elements such as transistors are formed, a copper wiring 2 is formed using a known damascene process.
0 was formed. The thickness of the copper film constituting the copper wiring 20 is 30
It was set to 0 nm.

On the silicon nitride film 6 having a thickness of 20 nm
And after forming a 900 nm thick silicon oxide film 21,
Further, a resist film 22 patterned in a predetermined shape was provided thereon (FIG. 10B). PEX4 (manufactured by Tokyo Ohka Kogyo Co., Ltd.), which is a positive resist material for KrF, was used as a resist material.

Next, the silicon oxide film 21 was dry-etched using the resist 22 as a mask until the silicon nitride film 6 was exposed to form a through hole (FIG. 10).
(C)). The opening diameter of the through hole was about 0.2 μm. As an etching gas, a gas capable of etching a silicon oxide film faster than a silicon nitride film was used. After the etching, a deteriorated resist layer 24 is formed in the opening of the resist film 22.

Here, the silicon nitride film 6 also has a function as an etching stopper film. However, as shown in FIG. 10C, the dry etching cannot be stopped on the silicon nitride film 6 with good controllability. There is.

After the etching, the resist film 22 was removed by oxygen plasma ashing (FIG. 11A).
Next, a wet treatment was performed using a resist stripping solution containing an aliphatic amine and a benzotriazole derivative. The processing temperature was 90 ° C. and the processing time was 20 minutes. This process removes the etching residue 10 (FIG. 11).
(B)). Subsequently, the NO. 1
Wet treatment was carried out using the resist stripping solution. The wet treatment was performed by immersing in the above-mentioned resist stripping solution at 23 ° C. for 10 minutes. By this process, the altered resist layer 24 is removed (FIG. 12A).

Then, the silicon nitride film 6 was etched by changing the etching gas from the above-mentioned etching. At this time, the etching residue 35 adheres to the side wall of the through hole (FIG. 12B). Next, a wet treatment was performed using a resist stripping solution containing an aliphatic amine and a benzotriazole derivative. The processing temperature was 90 ° C. and the processing time was 20 minutes. Subsequently, wet processing was performed using a stripping solution (choline content: 20% by weight) in which choline was dissolved in an organic solvent. Thereby, the etching residue 35 is removed. FIG. 12C shows the state after the processing. Thereafter, inside the through hole, a barrier metal film 26 and a tungsten film 27 in which Ti and TiN are laminated in this order.
Was formed and then planarized by CMP to form an interlayer connection plug (FIG. 12D). afterwards,
An upper layer wiring and the like were formed, and a multilayer wiring structure in which copper wiring was laminated in multiple layers was produced. The obtained multilayer wiring structure was excellent in high-speed operation and exhibited good performance.

Further, using a silicon wafer subjected to the same process as described above, the NO. The stage after the completion of the wet process using the resist stripper (see FIG. 12)
For the silicon wafer of (a)) and the silicon wafer after the completion of the wet treatment with the choline-containing liquid (FIG. 12 (c)), appearance observation and cross-sectional observation were respectively performed by SEM. As a result, any of the above SEM
In observation, residues etc. were almost completely removed,
Further, no corrosion of the exposed portion of the copper film was observed.

[0089]

As described above, in the method of manufacturing a semiconductor device according to the present invention, after the step of stripping at least a part of the resist film, the wet processing is performed using a resist stripping solution containing a benzotriazole derivative. Therefore, it is possible to efficiently remove a layer that is difficult to remove, such as a deteriorated resist layer, while preventing deterioration of the copper-based metal film that is easily corroded by the stripping solution.

Further, according to the present invention, the following effects can be obtained.

In order to prevent copper metal from diffusing into the semiconductor element formation region, a silicon nitride film is indispensable. There is no need to secure a silicon nitride film thickness. Therefore, a silicon oxide film having a lower dielectric constant than the silicon nitride film is predominantly formed between the adjacent wirings, so that the capacitance between the wirings can be reduced. As a result, the operation speed of the semiconductor element can be improved.

Further, since the resist stripping solution of the present invention contains a benzotriazole derivative, the temperature dependency of the anticorrosion action is small, and the temperature margin of the anticorrosion action can be widened. Therefore, even when a strong stripping action is applied to the stripping solution such that a layer that is difficult to remove such as a deteriorated resist layer can be removed, a sufficient anticorrosion effect can be obtained over a wide temperature range. Therefore, the anticorrosion performance can be maintained without providing a temperature control mechanism in the peeling device, and the size, cost, and power consumption of the peeling device can be reduced, and the manufacturing cost of the semiconductor device can be significantly reduced. Furthermore, even if there is a heat source such as a heating or cooling device around the peeling device, the anticorrosion performance can be maintained. become.

[Brief description of the drawings]

FIG. 1 is a process sectional view showing a copper wiring forming process of the present invention.

FIG. 2 is a process sectional view showing a copper wiring forming process of the present invention.

FIG. 3 is a process sectional view showing a copper wiring forming process of the present invention.

FIG. 4 is a process cross-sectional view showing a copper wiring forming process of the present invention.

FIG. 5 is a schematic diagram showing a form of a deteriorated resist layer generated when dry etching for forming a wiring groove and a through hole is performed.

FIG. 6 is a process sectional view showing a copper wiring forming process of the present invention.

FIG. 7 is a process sectional view showing a copper wiring forming process of the present invention.

FIG. 8 is a process sectional view illustrating a copper wiring forming process of the present invention.

FIG. 9 is a process cross-sectional view showing a copper wiring forming process of the present invention.

FIG. 10 is a process sectional view showing the copper wiring forming process of the present invention.

FIG. 11 is a process cross-sectional view showing a copper wiring forming process of the present invention.

FIG. 12 is a process cross-sectional view showing a copper wiring forming process of the present invention.

FIG. 13 is a process cross-sectional view showing a process for forming a through hole on a copper wiring.

FIG. 14 is a process sectional view illustrating a process of forming a through hole on a copper wiring.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 silicon oxide film 2 silicon nitride film 3 silicon oxide film 4 Ta film 5 copper film 6 silicon nitride film 7 silicon oxide film 8 silicon nitride film 9 silicon oxide film 10 etching residue 12 resist film 14 resist deteriorated layer 15 resist film 16 resist deterioration Layer 17 Ta film 18 Copper film 20 Copper wiring 21 Silicon oxide film 22 Resist film 24 Resist deteriorated layer 26 Barrier metal film 27 Tungsten film 28 Copper corroded part 50 Wiring groove 51 Resist deteriorated layer 52 Copper wiring 53 Hole 54 Resist deteriorated layer 55 Copper wiring

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/3205-21/3213 H01L 21/768

Claims (13)

(57) [Claims] (A) forming a copper-based metal film on a semiconductor substrate, forming an insulating film thereon, and further forming a resist film thereon; and (b) masking the resist film. Forming a recess reaching the copper-based metal film in the insulating film, and (c) stripping off at least a part of the resist film;
A method for manufacturing a semiconductor device, comprising: (d) performing a wet process using a resist stripper containing a benzotriazole derivative; and (e) embedding a conductive film in the recess. (A) forming a copper-based metal film on a semiconductor substrate, forming a copper diffusion preventing film and an insulating film thereon in this order, and further forming a resist film thereon;
(B) a step of performing a dry etching using the resist film as a mask to provide a concave portion reaching the copper diffusion preventing film in the insulating film; and (c) a step of stripping at least a part of the resist film; d) performing a wet treatment using a resist stripper containing a benzotriazole derivative; and (e) embedding a conductive film in the recess after removing the copper diffusion preventing film. Semiconductor device manufacturing method. 3. In the step (e), after the copper diffusion preventing film is removed by dry etching, an etching residue generated in the dry etching is removed by a treatment using a choline-containing solution. The method for manufacturing a semiconductor device according to claim 2. 4. The wet treatment of the step (d),
4. The method of manufacturing a semiconductor device according to claim 1, wherein the affected layer generated by the dry etching in the step (b) is removed. 5. The semiconductor according to claim 1, further comprising a step of removing an etching residue attached to an inner wall of the recess between the steps (c) and (d). Device manufacturing method. 6. The step of removing the etching residue,
The method according to claim 5, wherein the method is performed by a treatment using an amine-containing liquid. 7. (a) After a copper-based metal film is formed on a semiconductor substrate, a copper diffusion preventing film, a first insulating film, an etching stopper film, and a second insulating film are laminated thereon in this order. Forming a multi-layered film, and further forming a first resist film thereon, and (b) performing dry etching using the first resist film as a mask to form the copper-based metal film in the multi-layered film. Forming a hole reaching the first resist film, then removing the first resist film, (c) forming a second resist film on the second insulating film, and (d) masking the second resist film. Performing dry etching as a step of forming a wiring groove reaching the etching stopper film in the second insulating film;
(E) a step of stripping at least a part of the second resist film, (f) a wet step using a resist stripper containing a benzotriazole derivative, and (g)
Embedding a conductive film in the hole and the wiring groove. 8. (a) After a copper-based metal film is formed on a semiconductor substrate, a copper diffusion preventing film, a first insulating film, an etching stopper film, and a second insulating film are laminated thereon in this order. Forming a multi-layered film, and further forming a first resist film thereon, and (b) performing dry etching using the first resist film as a mask to form a copper diffusion preventing film in the multi-layered film. A step of forming a hole to reach, and then removing the first resist film; (c) a step of forming a second resist film on the second insulating film; and (d) using the second resist film as a mask. Performing dry etching to form a wiring groove reaching the etching stopper film in the second insulating film;
(E) a step of stripping at least a portion of the second resist film, (f) a wet step using a resist stripper containing a benzotriazole derivative, and (g)
Burying a conductive film inside the hole and the wiring groove after removing the copper diffusion preventing film. 9. In the step (g), after the copper diffusion preventing film is removed by dry etching, an etching residue generated during the dry etching is removed by a treatment using a choline-containing solution. The method of manufacturing a semiconductor device according to claim 8. 10. The wet treatment in the step (f),
The method for manufacturing a semiconductor device according to claim 7, wherein the deteriorated resist layer generated by the dry etching in the step (d) is removed. 11. The method according to claim 7, further comprising a step of removing an etching residue attached to the hole or the inner wall of the wiring groove between the steps (e) and (f).
0. A method for manufacturing a semiconductor device according to any one of [1] to [10]. 12. The method according to claim 11, wherein the step of removing the etching residue is performed by a process using an amine-containing solution. 13. The semiconductor device according to claim 1, wherein the resist stripping solution containing the benzotriazole derivative further contains a salt of hydrofluoric acid and a base not containing a metal ion. Manufacturing method.