JP2003273211A - Method of manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a semiconductor device which forms openings having uniform diameters in a via pattern for forming vias at high reproducibility in a trench preforming type dual damascene method. <P>SOLUTION: The semiconductor device method comprises steps of: forming a first organic film 31 containing an acid generating agent so as to cover recesses 21a; forming a second organic film 32 on the first organic film for forming a cross-linked layer 33 with acid; diffusing acid generated in the first organic film 31 into the second organic film 32 to form a cross linked layer 33 and removing non cross-linked portions of the second organic film 32; exposing the cross-linked layer 33 coated with a resin to form a via pattern for forming vias in lower portions of the recesses 21a; and etching to form vias using the via pattern as a mask. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of manufacturing a semiconductor device applied to a step of forming a wiring groove and a via hole in an interlayer insulating film by a dual damascene method.

[0002]

2. Description of the Related Art Copper has been used as a wiring material because of the demand for higher speed and lower power consumption of semiconductor circuits.
As a technique for processing a copper wiring, a groove wiring method such as a single damascene method or a dual damascene method is often used because dry etching of copper is generally not easy. Among them, in particular, in the dual damascene method, a wiring groove and a via hole communicating with this wiring groove are formed in the interlayer insulating film, and a conductive film such as copper is embedded in these recesses to simultaneously form the wiring and the via plug. It is the one that forms and is considered promising.

In the above dual damascene method, a first via type in which a mask pattern (via hole pattern) for forming a via hole is formed on an interlayer insulating film and then a mask pattern for forming a wiring groove (wiring groove pattern) is formed. Then, after forming the wiring groove pattern, it is classified into a front groove type for forming a via hole pattern.

Here, an example of forming a wiring groove and a via hole by a front groove type dual damascene method is shown in FIG.
4 to 15 are shown. First, as shown in FIG. 14A, a mask layer (not shown) is formed on the interlayer insulating film 11 and is etched using a photomask to form a wiring groove pattern 21 having an opening. . Since this opening is formed to have a concave cross-section with the interlayer insulating film 11 as the bottom, it will be referred to as a recess 21a hereinafter.

Next, as shown in FIG. 14B, the recess 2
The antireflection film 3 is formed on the wiring groove pattern 21 so as to cover 1a.
5 is formed. The antireflection film 35 is used to prevent fluctuations in the intensity of the substrate reflected light when a resist is applied on the antireflection film 35 in a step described later and a via hole pattern is formed in the resist by a photolithography technique. .

Then, as shown in FIG. 14C, a resist 51 is applied on the antireflection film 35, and a photomask 41 is formed.
To expose the interlayer insulating film 1 below the recess 21a.
A via hole pattern for forming a via hole is transferred to the resist 51.

Next, as shown in FIG. 15D, the resist 51 (see FIG. 14C) is developed and the opening 22 is formed.
A via hole pattern 22 having A is formed, and the via hole pattern 22 is used as a mask to etch the antireflection film 35 and the interlayer insulating film 11 to form a via hole 61 in the interlayer insulating film 11 below the recess 21a. To do. Then, as shown in FIG. 15E, the via-hole pattern 22 and the antireflection film 35 (see FIG.
4 (d)), the wiring groove pattern 21 is used as a mask to etch the interlayer insulating film 11 up to the middle thereof to form a wiring groove 62 communicating with the upper portion of the via hole 61 in the interlayer insulating film 11.

After the via hole 61 and the wiring groove 62 are formed in this way, a conductive film made of copper is buried and the excess conductive film and the wiring groove pattern 21 are removed, so that the via plug and the wiring are simultaneously formed. Can be formed.

[0009]

However, as shown in FIG.
As shown in (b), when the antireflection film 35 is formed on the wiring groove pattern 21 so as to cover the recess 21a, the antireflection film 35 is formed in the recess 21a in such a shape that the opening width is narrowed toward the bottom. Therefore, the film thickness in the recess 21a is not uniform. When the resist 51 is applied on such an antireflection film 35, as shown in FIG.
Regarding the effective film thickness of the resist 51 on 1a, the film thickness t1 in the central portion of the recess 21a is thicker, and the film thickness t2 near the sidewall is thinner than t1.

As described above, since the film thickness of the resist 51 varies depending on the position in the recess 21a, the light absorption amount also varies due to the light interference effect and the bulk effect in the resist 51,
As shown in FIG. 15D, when the resist 51 is exposed to form the via hole pattern 22, the opening 22 is formed.
It was difficult to control the pore size of A. Further, even if a positional deviation occurs during exposure, the film thickness of the resist 51 varies depending on the position, so that it is difficult to form the opening 22A having a uniform hole diameter with good reproducibility.

Therefore, when forming a via hole pattern by the above-described groove-dual dual damascene method, there is a demand for a method of forming an opening portion having a uniform hole diameter with good reproducibility in the via hole pattern.

[0012]

In order to solve the above problems, a method of manufacturing a semiconductor device according to the present invention is a method of manufacturing a semiconductor device in which a hole is formed on a surface of a substrate having a concave step. A step of forming a first organic film containing an acid generator so as to cover the concave step, and a step of forming a second organic film forming a crosslinked layer with an acid on the first organic film. And a step of diffusing the acid generated in the first organic film into the second organic film to form a crosslinked layer, and then removing an uncrosslinked portion of the second organic film, and a resist on the crosslinked layer. Characterized by comprising a step of applying and exposing to form a resist pattern for forming a hole under the concave step, and a step of forming a hole by etching using the resist pattern as a mask There is.

According to the method of manufacturing a semiconductor device of the present invention,
An acid is generated from the first organic film formed so as to cover the concave step, and the acid is diffused into the second organic film formed on the first organic film to form the crosslinked layer. Is formed with a film thickness that depends on the density of the acid that diffuses into the second organic film. Here, the first organic film is formed in a shape in which the opening width is narrowed toward the bottom in the concave step, and
It is thin near the upper corner and thicker in the concave step than near the upper corner. As a result, when the acid is diffused into the second organic film formed on the first organic film, the film thickness of the first organic film is thin near the upper corner of the concave step, and thus the second organic film is formed. The density of the acid that diffuses in is low. On the other hand, the thickness of the first organic film is large in the concave step, and the second organic film formed on the first organic film has a narrower opening width as it approaches the bottom, especially in the center. On the other hand, since the acid is diffused from the first organic film in the bottom direction and the sidewall direction, the density of the acid diffused in the second organic film is increased.

As a result, the cross-linking layer formed on the second organic film is thin in the upper corner portion of the concave step and thick in the central portion, so that the concave step is filled with the cross-linking layer before the resist application. The surface on the concave step can be flattened. Therefore, since the film thickness of the resist to be applied later can be formed uniformly, it is possible to suppress the optical interference effect and the bulk effect due to the fluctuation of the resist film thickness when forming the resist pattern. The hole diameter of the opening can be controlled, and a resist pattern having an opening with a uniform hole diameter can be formed with good reproducibility regardless of the position in the concave step.

Further, in the invention described in claim 3 of the present invention, the first organic film generates an acid by light irradiation, and after forming the first organic film, a mask pattern is used. The feature is that an acid is generated by irradiating the concave step with light.

According to such a method, after the first organic film is formed so as to cover the concave step, the concave step is irradiated with light using a mask pattern to remove the acid from the first organic film. generate. Then, the generated acid is diffused into the second organic film formed on the first organic film to form a crosslinked layer on the second organic film. The film thickness of this cross-linking layer depends on the density of the acid diffused in the second organic film, and the acid density depends on the coating shape of the first organic film in the concave step and the intensity of the irradiated light. According to this method, the light intensity is highest at the center of the opening of the mask pattern by irradiating the concave step with light using the mask pattern. Therefore, the intensity of the light irradiated in the concave step is near the sidewall. The center is higher than the center.

Therefore, in the vicinity of the corner of the concave step, the thickness of the first organic film is thin and the intensity of the irradiated light is low, so that the density of the acid diffused into the second organic film is low. on the other hand,
The film thickness of the first organic film is large in the concave step, and the opening width is narrowed toward the bottom, especially in the central part, so that the film is formed in the bottom direction and the side wall direction with respect to the second organic film. Acid diffuses from the first organic film. In addition to this, the intensity of the radiated light is high, so the second part is
The density of the acid diffused into the organic film becomes high. Therefore,
In the concave step, the cross-linking layer is formed thin in the upper corner portion and thicker in the central portion, so that the surface on the concave step before the resist application can be flattened more. In addition, according to such a method, since the cross-linking layer is formed only in the concave step, as compared with the case where the cross-linking layer is formed in other than the concave step, the cross-section is formed on the concave step and other portions. The surface can be entirely planarized.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. (First Embodiment) FIGS. 1 to 2 are sectional views showing manufacturing steps of a method for manufacturing a semiconductor device according to a first embodiment of the present invention.
In the present embodiment, an example of forming a wiring groove and a via hole by a front groove type dual damascene method will be described. The same components as those of the conventional technique will be described with the same numbers.

As shown in FIG. 1A, elements are formed on a semiconductor substrate (not shown) by a normal LSI process, and an interlayer insulating film 11 made of, for example, silicon oxyfluoride is formed above the elements. It is assumed that Then, the wiring groove pattern 21 having the recess 21 a is formed on the interlayer insulating film 11. The recess 21a is formed, for example, by forming a silicon nitride film and then etching the film using a photomask. The opening width of the recess 21a is, for example, 20.
It is assumed to be 0 nm. Here, the portion from the semiconductor substrate to the wiring groove pattern 21 corresponds to the substrate according to claim 1, and the concave portion 21a corresponds to the concave step.

Next, as shown in FIG. 1B, a semiconductor substrate (not shown) is heated on a hot plate, for example, at 210 ° C. for 90 seconds to vaporize the solvent contained in the first organic film 31. Meanwhile, the first organic film 31 containing the acid generator is spin-coated on the wiring groove pattern 21 so as to cover the recess 21a. The first organic film 31 is composed of an acid generator, a resin, a crosslinking agent, a plasticizer, and a solvent, and has a function as an antireflection film.

The acid generator is a compound which generates an acid by heating here, for example, a compound such as an ester or an amine salt to which acetic acid, carboxylic acid, sulfonic acid, etc. are added.

The resin may be, for example, novolac resin, phenyl resin, acrylic resin or the like. To make the first organic film 31 function as an antireflection film, a resist is applied to form a via hole pattern. What absorbs the exposure light at the time of performing is desirable. For example, when exposing with a KrF excimer laser beam, a novolac resin is used and A
When exposing with rF excimer laser light, the exposure light can be absorbed by using a novolac resin or a phenyl resin. Alternatively, a chromophore that absorbs exposure light may be added to the above resin. KrF excimer laser light, A
Anthracene groups and the like are examples of chromophores that absorb rF excimer laser light.

The plasticizer has the purpose of improving the coatability of the first organic film 31 in the recess 21a, and examples thereof include anthracene compounds, phenolic compounds, and alkylphthalate compounds. Examples of the solvent include propanol, toluene, propylene glycol monomethyl ether, ethyl lactate and the like.

In the present embodiment, as the first organic film 31, for example, an amine salt of arylsulfonic acid is used as an acid generator,
A resin containing a novolac resin, a plasticizer containing a phenolic compound having an additional carbocyclic aryl substituent, and a solvent containing propylene glycol monomethyl ether is used.

By applying such a first organic film 31 on the wiring groove pattern 21 while heating it so as to cover the recess 21a as described above, the acid generator of the first organic film 31 can be formed. Here, the amine salt of arylsulfonic acid is thermally decomposed to generate an acid. In addition, the first organic film 31 has the concave portion 2
It is formed with a non-uniform film thickness within 1a. Specifically, the opening width is narrowed toward the bottom, and the opening is thin near the upper corner and thick in the recess 21a.

Next, as shown in FIG. 1C, a semiconductor substrate (not shown) is heated on a hot plate, for example, at 85 ° C. for 70 seconds to vaporize the solvent contained in the second organic film 32. However, the second organic film 3 that forms a cross-linked layer with an acid
2 is spin-coated on the first organic film 31.

The second organic film 32 is formed of a material that can be selectively removed with respect to the cross-linked layer formed on the second organic film 32 in a step described later, and is composed of a cross-linking agent, a resin, and a solvent. . The cross-linking agent causes a cross-linking reaction in the presence of an acid, and examples thereof include urea compounds and melamine compounds. The resin is for holding this cross-linking agent,
Considering the subsequent washing step, it is preferably water-soluble. Examples thereof include polyvinyl alcohol-based resin, polyacrylic acid-based resin, and polyvinyl acetal-based resin. The solvent is water.

The second organic film 32, like the first organic film 31, also functions as an antireflection film, so that it is desirable that the second organic film 32 has a high absorptivity for exposure light. Therefore, a chromophore that absorbs exposure light may be added. In the present embodiment, as the second organic film 32, for example, one containing a methylol melamine derivative as a cross-linking agent, a polyvinyl alcohol resin as a resin, an anthracene derivative as a chromophore, and water as a solvent is used. Although both the first organic film 31 and the second organic film 32 have a function as an antireflection film here, the first organic film 31 and the second organic film 31 containing at least an acid generator are used. It suffices that either one of the organic films 32 has the function of the antireflection film, and the crosslinked layer formed in the second organic film 32 has the function of the antireflection film.

Next, a semiconductor substrate (not shown) is, for example,
By heating with a hot plate at 30 ° C. for 70 seconds, the acid generated in the above process is diffused into the second organic film 32.

Then, as shown in FIG. 1D, the second organic film 32 in the vicinity of the boundary with the first organic film 31 is cross-linked by the diffused acid to form the second organic film 32. The crosslinked layer 33 is formed. Next, the surface of the second organic film 32 is washed with pure water to remove the uncrosslinked portion of the second organic film 32 and expose the crosslinked layer 33. afterwards,
Dry the entire device.

Next, as shown in FIG. 2 (e), the crosslinked layer 3
3 is spin-coated with a resist 51 made of, for example, a positive chemically amplified KrF excimer laser resist, and exposed by using a photomask 41 made of a halftone phase shift mask having a background transmittance of 6%, for example, The hole pattern is transferred to the resist 51.

Subsequently, a semiconductor substrate (not shown) is heated at, for example, 120 ° C. for 90 seconds, developed with an alkali developing solution, further washed with pure water, and the entire apparatus is dried. Then, as shown in FIG. 2F, the opening 2 is formed on the recess 21a.
A via hole pattern 22 (resist pattern) having 2A is formed. After that, although not shown here, the cross-linking layer 3 is formed using the via hole pattern 22 as a mask.
3, the first organic film 31 and the interlayer insulating film 11 are etched. As a result, a via hole (hole portion) is formed in the interlayer insulating film 11. Then, using the wiring groove pattern 21 as a mask, the interlayer insulating film 11 is partially etched to form a wiring groove communicating with the upper portion of the via hole. Then, a dual damascene wiring structure is obtained through a conductive film embedding step and a chemical mechanical polishing (CMP) step.

According to such a method of manufacturing a semiconductor device, after the first organic film 31 is formed in the recess 21a, the second organic film 32 is formed and heated, whereby the first organic film 32 is formed. The acid generated from the organic film 31 is diffused into the second organic film 32, and the crosslinked layer 33 is formed on the second organic film 32 by the diffused acid. The film thickness of the cross-linking layer 33 depends on the density of the acid diffused in the second organic film 32. In the recess 21a, since the thickness of the first organic film 31 is thin in the upper corner portion, the density of the acid diffused in the second organic film 32 is low, and the film thickness of the first organic film 31 is in the recess 21a. Is thick, and in particular, in the central part, since the opening width is narrowed toward the bottom, the acid is diffused from the first organic film 31 in the side wall direction and the second organic film 32 in the bottom direction. , The acid density increases.

Therefore, since the cross-linking layer 31 is formed so that the upper corner portion of the recess 21a is thin and the central portion thereof is thick, the recess 21a has a shape that fills the recess 21a.
It is possible to substantially flatten the surface of the resist a before applying the resist 51. This allows the resist 51 to be applied thereafter.
Can be formed with a uniform film thickness on the recess 21a.

Therefore, when the via hole pattern 22 is formed, the hole diameter of the opening 22A does not vary regardless of the position of the opening 22A formed on the recess 21a.
The opening 22A having a uniform hole diameter can be formed with good reproducibility. By using this via hole pattern as a mask, a highly accurate via hole (hole) can be formed in the lower portion of the recess 21a.

(Second Embodiment) FIGS. 3 to 5 show a second embodiment of the present invention.
6A to 6C are cross-sectional views of manufacturing steps of the method for manufacturing the semiconductor device according to the embodiment. In the first embodiment, the first organic film 31 containing an acid generator that generates an acid by heating was used, but in the present embodiment, the first organic film 31 containing an acid generator contains an acid generator that generates an acid by light irradiation. An example using the organic film 34 of No. 1 will be described. The same components as those in the first embodiment will be described with the same reference numerals.

As shown in FIG. 3A, a wiring groove pattern 21 made of, for example, silicon nitride is formed on the interlayer insulating film 11 made of, for example, silicon oxyfluoride. The wiring groove pattern 21 has two openings, and since these are formed in a concave shape in cross section with the interlayer insulating film 11 at the bottom, they will be referred to as recesses 21b and 21c hereinafter. The opening width of the recess 21c is made wider than that of the recess 21b.
The opening widths of b and 21c are 180 nm and 1800 n, respectively.
m.

First, as shown in FIG. 3B, a semiconductor substrate (not shown) is heated on a hot plate, for example, at 210 ° C. for 90 seconds to vaporize the solvent contained in the first organic film 34. A first organic film 34 containing an acid generator is spin-coated on the wiring groove pattern 21 so as to cover the recesses 21b and 21c. The first organic film 34 is composed of an acid generator, a resin, a cross-linking agent, a plasticizer, and a solvent, and has a function as an antireflection film.

In the present embodiment, the acid generator is a compound that generates an acid upon irradiation with light, and examples thereof include compounds such as sulfonium salts and iodonium salts. Other components such as the resin, the cross-linking agent, the plasticizer, and the solvent are the same as those of the first organic film 31 described in the first embodiment.

In this embodiment, as the first organic film 34, for example, triphenylsulfonium triflate is used as an acid generator, a novolac resin is used as a resin, a phenolic compound having an additional carbocyclic aryl substituent is used as a plasticizer, and propylene glycol is used as a solvent. The one containing monomethyl ether is used. The first organic film 34 as described above is formed in the recess 2
When applied on the wiring groove pattern 21 so as to cover the wiring patterns 1b and 21c, the first organic film 34 is formed in a shape in which the opening width is narrowed toward the bottoms of the recesses 21b and 21c, and at the upper corners. It is thin and thick in the recesses 21b and 21c. Further, when comparing the coating shapes of the recess 21b and the recess 21c, the film thickness of the first organic film 34 is formed thinner in the recess 21c having a wider opening width.

Next, as shown in FIG. 3C, the recesses 21b, 21 are formed by using the photomask 42 used during the exposure for forming the recesses 21b, 21c in the wiring groove pattern 21.
ArF excimer laser light is irradiated only on c. As a result, acid is generated from the first organic film 34 that covers the insides of the recesses 21b and 21c. The light intensity is generally high at the center of the opening of the pattern of the photomask 42 and is higher when the opening width is wider.
Therefore, the intensity of light applied to the recesses 21b and 21c is high in the center of the recesses 21b and 21c and low near the sidewalls, as shown in the graph in which the horizontal axis indicates the position of the recess and the vertical axis indicates the light intensity. . Further, in the concave portion 21c having a wide opening width, the intensity of the emitted light becomes higher than that in the concave portion 21b.

Then, as shown in FIG. 4D, the semiconductor substrate (not shown) is heated on a hot plate, for example, at 85 ° C. for 70 seconds to vaporize the solvent contained in the second organic film 32. , The second organic film 32 forming a cross-linked layer with an acid is spin-coated on the first organic film 34. Here, the second organic film 32 is formed of a material that can be selectively removed with respect to the first organic film 34 and the cross-linking layer formed on the second organic film 32 in a process described later. Here, it is assumed that the same configuration as that of the first embodiment is used.

Next, as shown in FIG. 4E, the semiconductor substrate (not shown) is heated by a hot plate at 130 ° C. for 50 seconds, for example. The acid generated thereby is diffused into the second organic film 32, and the second organic film 32 in the vicinity of the boundary with the first organic film 34 undergoes a cross-linking reaction, so that the second organic film 32 has a cross-linking layer 33. To form. Then, by cleaning the surface of the second organic film 32 with pure water, the second organic film 32 is removed.
The uncrosslinked portion of is removed to expose the crosslinked layer 33. Then, the entire device is dried.

Here, light irradiation is performed before forming the second organic film 32 to generate an acid from the first organic film 34, but the second organic film 32 is formed on the first organic film 34. After the formation, the recesses 21b and 21c may be irradiated with light.

Next, as shown in FIG. 4 (f), a resist 51 is spin-coated on the first organic film 34 and the cross-linking layer 33 and exposed using a photomask 41 to form a via hole pattern. Is transferred to the resist 51. here,
In the vicinity of the side wall of the recess 21a in the resist 51 (51
a), the via hole pattern is transferred so that the central portion (51b) of the recess 21b and the vicinity of the side wall (51c) of the recess 21b become openings.

Next, a semiconductor substrate (not shown) is, for example,
Heat at 20 ° C for 90 seconds and develop with an alkaline developer,
Further, it is washed with pure water and the entire device is dried. And
As shown in FIG. 4 (g), the opening 22 is formed on the recess 21b.
B, a via hole pattern 22 having openings 22C and 22D is formed on the recess 21c. By using the via hole pattern 22 as a mask, the cross-linking layer 3 is etched.
3 Etch the first organic film 34 and the interlayer insulating film 11,
A via hole is formed in the interlayer insulating film 11.

According to such a semiconductor device manufacturing method, after the first organic film 34 is formed in the recesses 21b and 21c, the photomask 42 is used to irradiate only the recesses 21b and 21c with light. As a result, acid is generated from the first organic film 34 in the recesses 21b and 21c. And the second
Of the second organic film 3 is formed on the first organic film 34 by diffusing the generated acid into the second organic film 32.
The cross-linked layer 33 is formed on the surface 2. The film thickness of the cross-linking layer 33 depends on the density of the acid diffused in the second organic film 32, and the density of the acid is the coating shape of the first organic film 34 in the recesses 21b and 21c and the intensity of the irradiated light. Depends on.

When the photomask 42 is used to irradiate the recesses 21b and 21c with light, the intensity of the irradiated light is low at the upper corner and the second organic film 34 is thin, so that the second The density of the acid diffused in the organic film 32 is low. On the other hand, the first organic film 34 has a large film thickness in the recesses 21b and 21c, and in particular, in the central part, the opening width is narrowed toward the bottom part. Therefore, the first organic film 34 in the side wall direction and the bottom part direction is formed. The acid diffuses from 31 to the second organic film 32. In addition to this, since the intensity of the irradiated light is also high, the density of the acid diffused in the second organic film 32 is high in the central portion. Therefore, the bridging layer 31 is formed thin at the upper corner and thicker at the center.

In the recesses 21b and 21c, the first organic film 34 is thinly formed in the recess 21c having a wide opening width, but since the irradiated light intensity is higher in the recess 21c, the first organic film 34 is bridged in the recess 21c. Since the layer 33 is formed thicker, the recesses 21b and 21c before the application of the resist 51 are formed.
The top surface can be planarized to approximately the same height. Further, using the photomask 42, the concave portions 21b, 2
By irradiating 1c with light, the cross-linking layer 33 can be formed only in the recesses 21b and 21c. Therefore, as compared with the first embodiment, on the recesses 21b and 21c and the recesses 21b and 21c.
The surface of the wiring groove pattern 21 other than that before the resist 51 is applied can be entirely flattened.

Therefore, the resist 5 to be applied after that
1 can be applied with a substantially uniform film thickness without being affected by the steps of the recesses 21b and 21c. Therefore, when forming the via hole pattern 22, the recesses 21b and 21c are formed.
No matter where it is formed, the hole diameter does not change,
It is possible to form the openings 22B, 22C, 22D having a uniform hole diameter. Further, by etching using the via pattern 22 as a mask, the concave portions 21b, 21
A highly accurate via hole (hole) can be formed in the lower part of c.

In this embodiment, the photomask 42 is used to irradiate only the first organic film 34 in the recesses 21b and 21c with light, but the present invention is not limited to this. If the first organic film 34 generates acid by light irradiation, the entire first organic film 34 may be irradiated with light. The timing of the light irradiation is at the time of forming the first organic film 34 or when the first organic film 34 is formed.
It may be after the film formation and before the second organic film 32 is formed.
Alternatively, the organic film 32 may be formed.

As described above, when the entire first organic film 34 is irradiated with light, there is no difference in the intensity of the irradiated light in the recesses 21b and 21c, so that the same effect as in the first embodiment is obtained. Obtainable.

As described above, according to the semiconductor device manufacturing methods of the first and second embodiments, the antireflection film is formed on the mask pattern so as to fill the recesses in order to prevent the variation in the resist film thickness. Since it is not necessary to flatten the antireflection film by applying a thick coating and etching back to a desired thickness, it is possible to suppress TAT (Turn Around Time).

Example 1 Next, an example of forming a wiring groove and a via hole by a dual damascene method using the method for manufacturing a semiconductor device described in the first embodiment will be described with reference to FIGS. To do.

As shown in FIG. 5A, after an element is formed on a semiconductor substrate (not shown) by a normal LSI process, an interlayer insulating film made of silicon oxyfluoride is formed thereon. A wiring 71 made of copper reaching the surface of the interlayer insulating film 12 is formed on the surface 12.

First, the interlayer insulating film 12 and the wiring 71 are formed.
On top of this, an etching stopper film 1 made of silicon nitride
3 was formed to a film thickness of 70 nm, and an interlayer insulating film 14 made of silicon oxyfluoride was formed thereon to a film thickness of 500 nm. Furthermore, an etching stopper film 15 made of silicon nitride and an interlayer insulating film 16 made of silicon oxyfluoride were sequentially formed on the interlayer insulating film 14. The film thicknesses of the etching stopper film 15 and the interlayer insulating film 16 are 50 nm and 350 nm, respectively.

Then, a mask layer (not shown) made of a silicon nitride film having a film thickness of 150 nm is formed on the interlayer insulating film 16 and is etched using an exposure mask (not shown) to form two layers. A wiring groove pattern 21 having recesses 21b and 21c was formed. The opening widths of the recesses 21b and 21c are 200 nm and 2000 nm, respectively.

Next, as shown in FIG. 5 (b), the semiconductor substrate (not shown) is heated by a hot plate at 210 ° C. for 90 seconds while the first organic film 3 containing the acid generator is added.
1 so as to cover the concave portions 21b and 21c.
1 was spun on. As the first organic film 31, one containing an amine salt of arylsulfonic acid as an acid generator, a novolac resin as a resin, a phenolic compound having an additional carbocyclic aryl substituent as a plasticizer, and a solvent containing propylene glycol monomethyl ether as a solvent. Using.

Here, the first covering the inside of the recesses 21b and 21c
When the height of the organic film 31 is measured with the surface of the wiring groove pattern 21 as a reference S, it is +30 nm at the upper corner of the recess 21b, −70 nm at the center thereof, and the recess 21c.
Was +20 nm at the upper corner and −80 nm at the center.

Next, as shown in FIG. 5C, the semiconductor substrate (not shown) is heated by a hot plate at 85 ° C. for 70 seconds, while the second organic film 3 is formed with an acid to form a crosslinked layer.
2 was spin-coated on the first organic film 31. The coating film thickness is 500 on the wiring groove pattern 21 other than the concave portions 21b and 21c.
nm. As the second organic film 32, one containing a methylol melamine derivative as a crosslinking agent, a polyvinyl alcohol resin as a resin, an anthracene derivative as a chromophore, and water as a solvent was used.

Next, the substrate (not shown) is heated to 130 ° C. and 70 ° C.
Heated on a hot plate for 2 seconds. As a result, the amine salt of arylsulfonic acid, which is the acid generator in the first organic film 31, was thermally decomposed, and the generated acid was diffused into the second organic film 32.

Then, as shown in FIG. 6D, the second organic film 32 in the vicinity of the boundary with the first organic film 31 was cross-linked by the diffused acid to form a cross-linked layer 33. Then, the surface of the second organic film 32 was washed with pure water to remove the uncrosslinked portion of the second organic film 32 and expose the crosslinked layer 33. After that, the entire device was dried.

Then, the first in the recesses 21b, 21c
The total height of the organic film 31 and the cross-linking layer 31 was measured using the surface of the wiring groove pattern 21 as a reference S. As a result, the upper corner of the recess 21b was +40 nm, and the central portion was +8 n.
m, which was +30 nm at the upper corner of the recess 21c and +4 nm at the center.

Next, as shown in FIG. 6 (e), a resist 51 consisting of an acetal-based positive chemically amplified KrF excimer laser resist was spin-coated at a film thickness of 560 nm to obtain a background transmittance of 6%. Exposure was performed using a photomask 41 formed of a halftone phase shift mask, and the via hole pattern was transferred to the resist 51. The exposure machine
A KrF excimer laser scanner with a reduced projection magnification of 1/4 was used, and the numerical aperture (NA) was set to 0.68 and the numerical aperture ratio (σ) was set to 0.5.

Specifically, the concave portion 2 in the resist 51
1a near the side wall (51a) and the central portion of the recess 21b (51a).
b), transfer was performed so as to form an opening near the side wall (51c) of the recess 21b. The target hole diameter of the via hole pattern here is φ180 nm, and the allowable width is 160 nm.
~ 200 nm. 51a, 51 of the resist 51
The film thicknesses a, b, and c at the positions of b and 51c were measured by extending the center line of the opening of the photomask 41,
A = 550 nm, b = 560 nm, c = 55, respectively
It was 4 nm and was applied with a substantially uniform film thickness.

Next, the semiconductor substrate (not shown) is heated to 120 ° C.
After being heated for 90 seconds at 90 ° C., it was developed with an alkali developing solution, further washed with pure water, and the entire apparatus was dried. Then, as shown in FIG. 7F, the opening 22B is formed on the recess 21b,
A via hole pattern 22 having openings 22C and 22D was formed on the recess 21c. These pore diameters (bottom diameter) are 188 nm, 176 nm, and 184 nm, respectively.
It was possible to form uniformly within the allowable range for the target pore diameter of 180 nm.

Next, as shown in FIG. 7G, the cross-linking layer 33, the first organic film 31, and the interlayer insulating film 16 are removed by dry etching using the via hole pattern 22 as a mask to form the recess 21b. , 21c and holes 16B in which openings 22B, 22C, 22D are transferred to the interlayer insulating film 16 below,
16C and 16D were formed.

Then, as shown in FIG. 8H, the via hole pattern 22, the cross-linking layer 33, the first organic film 31.
After ashing removal (see FIG. 3 (g) above), the etching stopper film 15 exposed at the bottoms of the holes 16B, 16C, 16D was removed by dry etching. By this etching, the surface of the wiring groove pattern 21 formed of the same silicon nitride as the etching stopper film 15 was also removed by the same thickness as the etching stopper film 15.

Next, as shown in FIG. 8I, the inter-layer insulating film 16 and the inter-layer insulating film 14 are simultaneously dry-etched using the wiring groove pattern 21 and the etching stopper film 15 as a mask, and the inter-layer insulating film 16 is then etched. A wiring groove 62 was formed in the interlayer insulating film 14 and a via hole 61 was formed in the interlayer insulating film 14.

Then, as shown in FIG. 8J, the etching stopper film 13 exposed at the bottom of the via hole 61 was removed by etching. Also in this etching, as described in FIG. 8H, the wiring groove pattern 21 is formed.
The surface of was removed by the same thickness as the etching stopper film 13.

After that, as shown in FIG. 9K, the inner walls of the wiring groove 62 and the via hole 61 are cleaned to form a barrier metal layer (not shown) made of tantalum nitride and a plating seed layer (shown in FIG. 9) made of copper. (Not shown) were sequentially formed. After that, a conductive film (not shown) made of, for example, copper is further embedded in the wiring groove 62 and the via hole 61 by electrolytic plating, and an extra conductive film on the upper surface, a plating seed layer,
Barrier metal layer, wiring groove pattern 21 (FIG. 8 (j) above)
(See) was polished by the CMP method to flatten the surface. Thus, the via plug 72 and the wiring 73 reaching the wiring 71 formed on the interlayer insulating film 12 were formed. As described above, a dual damascene wiring structure made of copper was created.

By the method as described above, the recesses 21b, 2
In the via hole pattern 22 on 1c, the openings 22B, 22C and 22D having a uniform hole diameter could be formed. Further, by using this via hole pattern as a mask to perform etching, it was possible to form the via hole 61 (hole portion) having a uniform hole diameter under the concave portions 21b and 21c.

On the other hand, as a comparative example to this, FIG.
In (b), a commercially available organic antireflection film is applied on the wiring groove pattern 21 so as to cover the recesses 21b and 21c, and then a resist 51 is applied thereon. A similar method was done. In this case, the hole diameters (bottom diameters) of the openings 22B, 22C, 22D of the via hole pattern 22 were measured to be 192 nm and 145n.
m, 175 nm, and the opening 22B formed in the center of the recess 21b is not formed to have a hole diameter within the allowable range.
It was confirmed that the hole diameter varied depending on the position within 1b. Therefore, using the via hole pattern 22 as described above,
When a via hole was formed under 1b and 21c,
Via holes with non-uniform pore size were formed.

(Example 2) Next, an example of forming a wiring groove and a via hole by a dual damascene method using the method for manufacturing a semiconductor device described in the second embodiment will be described. The same components as those in the second embodiment will be described with the same numbers.

As shown in FIG. 10A, in the interlayer insulating film 12 made of silicon oxycarbide, a wiring 71 made of, for example, copper reaching the surface of the interlayer insulating film 12 is formed.
An etching stopper film 13 made of, for example, silicon nitride having a thickness of 60 nm is formed on the interlayer insulating film 12 and the wiring 71.
And an interlayer insulating film 14 made of silicon oxycarbide having a film thickness of 400 nm. further,
As the upper layer, an etching stopper film 15 made of silicon nitride and an interlayer insulating film 16 made of silicon oxycarbide are formed.
And were sequentially laminated. The thicknesses of the etching stopper film 15 and the interlayer insulating film 16 are 40 nm and 250, respectively.
nm.

Then, the recess 21 is formed on the interlayer insulating film 16.
The wiring groove pattern 21 made of silicon nitride and having b and 21c was formed to a film thickness of 140 nm. Recesses 21b, 2
The opening widths of 1c are 140 nm and 1800 nm, respectively.

First, as shown in FIG. 10B, a semiconductor substrate (not shown) is heated with a hot plate at 210 ° C. for 90 seconds, and a first organic film 34 containing an acid generator is formed.
The wiring groove pattern 21 so as to cover the concave portions 21b and 21c.
Spin coated on top. As the first organic film 34, triphenylsulfonium triflate which generates an acid by irradiation with an acid generator, a novolac resin as a resin, a phenolic compound having an additional carbocyclic aryl substituent as a plasticizer, and propylene glycol monomethyl as a solvent. The one containing ether was used.

The first portion that covers the inside of the recesses 21b and 21c
When the height of the organic film 34 is measured with the surface of the wiring groove pattern 21 as a reference S, it is +35 nm at the upper corner of the recess 21b, −55 nm at the center thereof, and the recess 21c.
Was +20 nm at the upper corner and −80 nm at the center.

Next, as shown in FIG. 11C, the recesses 21b, 2 are formed by using the photomask 42 used during the exposure for forming the recesses 21b, 21c in the wiring groove pattern 21.
The ArF excimer laser beam was irradiated only on 1c. As a result, acid was generated from the first organic film 34 covering the insides of the recesses 21b and 21c.

Then, as shown in FIG. 11 (d), while heating the semiconductor substrate (not shown) with a hot plate at 85 ° C. for 70 seconds, a second organic film 32 for forming a cross-linking layer is formed by acid. 1 was spin-coated on the organic film 34. The coating film thickness was 500 nm on the wiring groove pattern 21. Here, the second organic film 32 has the same structure as that of the first embodiment.

Next, as shown in FIG. 12E, a semiconductor substrate (not shown) is heated on a hot plate at 130 ° C. for 50 seconds to diffuse the generated acid into the second organic film 32. A crosslinked layer 33 was formed on the second organic film 32. Then, the surface of the second organic film 32 is washed with pure water, and the second
The non-crosslinked portion of the organic film 32 was removed to expose the crosslinked layer 33. Then, the entire device was dried.

Here, when the combined height of the first organic film 34 containing the acid generator and the cross-linking layer 31 in the recesses 21b and 21c is measured with the surface S of the wiring groove pattern 21 as a reference S, The direction is +40 nm, the center is +42 nm, the upper corner of the recess 21c is +41 nm, and the center is +42 nm.
The non-uniformity of the film thickness in b and 21c was improved, and the same height was shown on the recesses 21b and 21c.

Next, as shown in FIG. 12 (f), a resist 51 consisting of an acetal-based positive chemically amplified KrF excimer laser resist was spin-coated with a film thickness of 460 nm to obtain a background transmittance of 6%. Exposure was performed using a photomask 41 formed of a halftone phase shift mask, and the via hole pattern was transferred to the resist 51. A KrF excimer laser scanner with a reduced projection magnification of 1/4 was used as an exposure device, and NA was set to 0.73 and σ was set to 0.5.

Specifically, the concave portion 2 in the resist 51
1a near the side wall (51a) and the central portion of the recess 21b (51a).
b), the via hole pattern was transferred so as to form an opening near the side wall (51c) of the recess 21b. The target hole diameter of the opening of the via hole pattern here is φ120.
nm, and the allowable width is 118 nm to 132 nm.
The film thicknesses a, b, and c at the positions 51a, 51b, and 51c in the resist 51 are a = 460 nm at the center position of the transferred via hole pattern, respectively.
It was evenly applied with b = 460 nm and c = 459 nm.

Next, the substrate was heated at 120 ° C. for 90 seconds, developed with an alkali developing solution, further washed with pure water and dried. Then, as shown in FIG. 13G, a via hole pattern 22 having openings 22B, 22C, 22D was formed, and the hole diameters (bottom diameters) of these were measured to be 122 nm, 122 nm, and 119 nm, respectively. It was formed uniformly within an allowable range for a target pore diameter of 120 nm. The subsequent steps are the same as in Example 1,
Similarly, a uniform via hole 61 was formed.

On the other hand, as a comparative example to this, FIG.
In (b), a commercially available organic antireflection film is applied on the wiring groove pattern 21 so as to cover the recesses 21b and 21c, and then a resist 51 is applied thereon. I went the same way. In this case, the hole diameters (bottom diameters) of the openings 22B, 22C, 22D of the via hole pattern 22 are 130 nm, 102 nm, 114 nm, and the opening 22B formed in the central portion of the recess 21b is formed within the allowable range. However, the variation of the hole diameter depending on the position in the recess 21b was recognized. Therefore, even when using the via pattern 22 as a mask to form via holes (holes) in the lower portions of the recesses 21b and 21c, the via holes were formed with non-uniform hole diameters.

[0087]

As described above, according to the method of manufacturing a semiconductor device of the present invention, an acid is generated from the first organic film formed so as to cover the concave step, and this acid is used as the first organic film. Since the cross-linking layer is formed by diffusing it into the second organic film formed above, the cross-linking layer is formed to have a film thickness depending on the density of the acid diffusing into the second organic film. Since the density of the acid diffused into the second organic film is low near the upper corner of the concave step and the acid density is high at the central part, the cross-linking layer is thin at the upper corner of the concave step and thick at the central part. As a result, the recessed step is shaped so as to be embedded, and the surface on the recessed step before resist coating can be flattened.

Therefore, according to the method for manufacturing a semiconductor device of the present invention, since the film thickness of the resist to be applied thereafter can be formed uniformly, the light caused by the variation in the film thickness of the resist when forming the resist pattern can be obtained. The interference effect and the bulk effect can be suppressed, the hole diameter of the opening of the resist pattern can be controlled, and the resist pattern having an opening having a uniform hole diameter with good reproducibility regardless of the position in the concave step. Can be formed. Thereby, the hole diameter of the hole formed in the lower part of the concave step can be controlled, and the hole having a uniform hole diameter can be formed regardless of the position in the concave step.

Further, the first organic film generates acid by light irradiation, and after forming the first organic film, light is irradiated to the concave step using the mask pattern to generate acid. In this case, since the intensity of light applied to the concave step is higher in the central portion than in the vicinity of the side wall, the density of the acid diffused into the second organic film in the central portion is higher.

Therefore, in the concave step, the cross-linking layer can be formed thinner in the upper corner portion and thicker in the central portion, so that the surface on the concave step before the resist application can be made more flat. In addition, according to such a method, since the cross-linking layer is formed only in the concave step, as compared with the case where the cross-linking layer is formed in other than the concave step, the cross-section is formed on the concave step and other portions. The surface can be entirely planarized.

[Brief description of drawings]

FIG. 1 is a manufacturing process sectional view for explaining the manufacturing method of the semiconductor device according to the first embodiment (No. 1).

FIG. 2 is a manufacturing process sectional view for explaining the manufacturing method of the semiconductor device according to the first embodiment (No. 2).

FIG. 3 is a manufacturing process sectional view for explaining the manufacturing method of the semiconductor device according to the second embodiment (No. 1).

FIG. 4 is a manufacturing process sectional view for explaining the manufacturing method of the semiconductor device according to the second embodiment (No. 2).

FIG. 5 is a manufacturing process sectional view for explaining the manufacturing method of the semiconductor device according to the first embodiment (No. 1).

FIG. 6 is a manufacturing process sectional view for explaining the manufacturing method of the semiconductor device according to the first embodiment (No. 2).

FIG. 7 is a manufacturing process sectional view for explaining the manufacturing method of the semiconductor device according to the first embodiment (No. 3).

FIG. 8 is a manufacturing process sectional view for explaining the manufacturing method of the semiconductor device according to the first embodiment (No. 4).

FIG. 9 is a manufacturing process sectional view for explaining the manufacturing method of the semiconductor device according to the first embodiment (No. 5).

FIG. 10 is a manufacturing process sectional view for explaining the manufacturing method of the semiconductor device according to the second embodiment (No. 1).

FIG. 11 is a manufacturing process sectional view for explaining the manufacturing method of the semiconductor device according to the second embodiment (No. 2).

FIG. 12 is a manufacturing process sectional view for explaining the manufacturing method of the semiconductor device according to the second embodiment (No. 3).

FIG. 13 is a manufacturing process sectional view for explaining the manufacturing method of the semiconductor device according to the second embodiment (No. 4).

FIG. 14 is a manufacturing process sectional view for explaining the manufacturing method of the semiconductor device, which shows the problem in the conventional technique (No. 1).

FIG. 15 is a manufacturing process sectional view for explaining the manufacturing method of the semiconductor device, showing the problems in the conventional technique (No. 2).

[Explanation of symbols]

11, 14, 16 ... Interlayer insulating film, 21 ... Wiring groove pattern, 21a, 21b, 21c ... Recesses, 31, 34 ... First
Organic film, 32 ... Second organic film, 33 ... Cross-linking layer, 22 ...
Via hole pattern, 22B, 22C, 22D ... Opening portion, 42 ... Photomask, 51 ... Resist, 61 ... Via hole, 62 ... Wiring trench

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4M104 BB04 BB32 CC01 DD07 DD08                       DD15 DD17 DD20 DD22 DD52                       DD75 EE08 EE12 EE14 EE17                       EE18 FF18 FF22 HH12 HH14                 5F033 HH11 HH32 JJ01 JJ11 JJ32                       KK11 MM02 MM12 MM13 NN06                       NN07 PP27 PP33 QQ01 QQ04                       QQ09 QQ10 QQ11 QQ21 QQ25                       QQ28 QQ37 QQ48 QQ74 QQ92                       RR01 RR06 RR11 SS22 TT02                       XX01 XX03 XX33

Claims (4)

[Claims] 1. A method of manufacturing a semiconductor device, wherein a hole is formed on a surface of a substrate having a concave step, and a step of forming a first organic film containing an acid generator so as to cover the concave step. And a step of forming a second organic film on the first organic film to form a cross-linking layer with an acid, and diffusing the acid generated in the first organic film into the second organic film. After forming a cross-linking layer, a step of removing an uncross-linked part of the second organic film, and applying a resist on the cross-linking layer to perform exposure to form a hole under the concave step. And a step of forming the hole portion by etching using the resist pattern as a mask. 2. The first organic film generates an acid by heating or light irradiation.
A method for manufacturing a semiconductor device as described above. 3. The first organic film is for generating an acid by light irradiation, and after the first organic film is formed, light is irradiated to the concave step using a mask pattern, The method of manufacturing a semiconductor device according to claim 1, wherein an acid is generated. 4. The concave step is an opening pattern of a wiring groove, and the hole is a via hole. After the via hole is formed, the via hole is formed by etching using the opening pattern as a mask. 2. The method for manufacturing a semiconductor device according to claim 1, wherein a wiring groove communicating with the via hole is formed in an upper portion.