JP3359622B2 - Wiring formation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dual damascene wiring forming method capable of stably forming a metal wiring having excellent electric characteristics.

[0002]

2. Description of the Related Art A conventional wiring forming method will be described with reference to the drawings.

FIGS. 9 (a) to 9 (d), 10 (a) and 10 (b) show cross-sectional structures in the order of steps of a conventional wiring forming method using a dual damascene method.

First, as shown in FIG. 9A, a first insulating film 102 is deposited on an insulating substrate 101, and a first trench pattern is formed in the deposited first insulating film 102. Subsequently, a first wiring material 104 made of copper (Cu) or the like is buried in the first trench pattern via the first barrier film 103 and flattened, so that the first barrier film 1 is formed.
The first metal wiring 105 made of the first wiring material 03 and the first wiring material 104 is formed. Subsequently, a second insulating film 106 made of a silicon nitride film or the like for protecting the first wiring material 104 is deposited on the first insulating film 102 and the first metal wiring 105, and the second insulating film 106 is formed. On the insulating film 106, an interlayer insulating film 107 made of a silicon oxide film or the like is deposited.

Next, as shown in FIG. 9B, a through hole 107a is formed in the interlayer insulating film 107 above the first metal wiring 105.

[0009] Next, as shown in FIG. 9 C, a positive resist pattern 108 for forming a second trench pattern having an opening including a through hole 107 a is formed on the interlayer insulating film 107. At this time, the through hole 10
When the opening size of the resist pattern 7a or the opening size of the resist pattern 108 becomes smaller and smaller, the resist pattern 108 becomes smaller.
Since the exposure light does not sufficiently reach the inside of the through hole 107a in the exposure step of
The resist material embedded in 07a becomes difficult to be exposed, and the resist material 108a remains in the through hole 107a. The resist material 108a remains in a region above the position corresponding to the bottom of the second trench pattern formed in the interlayer insulating film 107 in a later step.
Further, in order to avoid damage to the first metal wiring 105 when forming the second trench pattern, a resist or the like may be buried in the through hole 107a. In such a case, the resist shown in FIG. The result is equivalent to that of the material 108a.

[0009] Next, as shown in FIG. 9 D, the interlayer insulating film 107 is etched using the resist pattern 108 as a mask to form a second trench connected to the through hole 107 a in the interlayer insulating film 107. Pattern 10
After the formation of 7b, the resist pattern 108 and the resist material 108a are removed. At this time, the insulating etching residue 110 of the resist material 108a filled in the through hole 107a remains in the second trench pattern 107b.

Next, as shown in FIG. 10A, the through hole 107a formed in the interlayer insulating film 107 and the second
The second barrier film 111 is formed in the trench pattern 107b of FIG.
Followed by a second wiring material 11 such as copper (Cu).
Embed 2

Next, as shown in FIG. 10B, unnecessary portions of the second barrier film 111 and the second wiring material 112 are removed, and the second barrier film 111 and the second wiring material 1 are removed.
A second metal wiring 113 made of Twelve 12 is formed.

[0010]

However, in the conventional wiring forming method, as shown in FIG. 9D, an insulating property called an inner crown is formed in the second trench pattern 107b of the interlayer insulating film 107. Etching residue 110
Remain, the second metal wiring 113 has a high resistance,
Furthermore, there is a problem that the wire is broken.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned conventional problems and to prevent a resistance increase or disconnection of a wiring due to an etching residue in a dual damascene method.

[0012]

As a result of various studies, the inventors of the present invention have found that, in a trench-shaped trench pattern formed on an insulating film for embedding a wiring material, a through hole connected to the trench pattern is filled. It is ascertained that the inner crown is formed by the growth of the insulating etching residue from the stepped interface between the resist material and the insulating film.

Therefore, when forming a resist pattern for forming a trench pattern, the present inventors form a resist material for forming a trench pattern in a through hole exposed in an opening of the resist pattern in a later step. It has been found that the inner crown can be prevented by not leaving the trench pattern above the bottom of the trench pattern.

Specifically, in order to achieve the above object,
The wiring forming method according to the present invention includes a step (a) of forming a through hole in an insulating film on a substrate, a step (b) of forming a photosensitive mask material on the insulating film including the through hole, and a photosensitive mask. (C) forming a mask pattern for forming a trench having an opening including a through hole by patterning the material, and performing etching to a predetermined depth on the insulating film using the mask pattern By
A step (d) of forming a trench pattern connected to the through hole above the insulating film, a step (e) of filling the through hole and the trench pattern with a conductive material, and a mask before the step (d). (F) forming a pattern such that the photosensitive mask material does not remain in the through hole above the bottom of the trench pattern.

According to the wiring forming method of the present invention, before forming the trench pattern, the mask pattern for forming the trench does not leave the photosensitive mask material in the through hole above the bottom of the trench pattern. As a result, the mask material does not remain on the upper portion of the through hole due to the etching, so that it is possible to prevent the wiring from having high resistance or disconnection due to the etching residue.

In the method of forming a wiring according to the present invention, the step (c) includes exposing the photosensitive mask material to an exposure amount necessary to sensitize the thickness of the photosensitive mask material formed on the insulating film. It is preferable to include a step of forming a mask pattern from the photosensitive mask material by developing the exposed photosensitive mask material.

In the wiring forming method of the present invention, it is preferable that the step (d) includes a step of giving a round shape to a shape of a connection portion between an upper portion of the through hole in the insulating film and a bottom portion of the trench pattern.

In the method of forming a wiring according to the present invention, as a step (f), a step of forming a negative resist as a photosensitive mask material in the step (b) and in a step (c), the inside of the through hole is filled. A step of leaving the negative resist unexposed and removing the unexposed negative resist by development.

In the method of forming a wiring according to the present invention, the step (f) includes, after the step (a) and before the step (b), filling a filler in the through hole; Forming a photosensitive mask material on the insulating film including the through hole filled with the filler, and selectively removing the filler after the step (c) and before the step (d). It is preferable to have

Further, in this case, in the step of selectively removing the filler, it is preferable to leave a portion of the filler filled in the through hole below the bottom of the trench pattern.

In this case, it is preferable that the photosensitive mask material is a positive resist and the filler is a resist that is exposed in a wavelength region longer than the wavelength at which the positive resist is exposed.

In the wiring forming method of the present invention, as the step (f), after the step (a) and before the step (b), a step of forming a closing film on the insulating film to close the opening of the through hole. Forming a photosensitive mask material on the insulating film on which the blocking film is formed in the step (b); and etching the blocking film and the insulating film using the mask pattern in the step (d). And forming a trench pattern.

Further, in this case, it is preferable that the closing film is formed by a vapor deposition method having a low step coverage.

In the method of forming a wiring according to the present invention, the step (f) includes forming a through hole using a first exposure mask in the step (a), and the first exposure mask in the step (c). Exposing a through-hole portion of the photosensitive mask material using a second exposure mask for forming a trench including the through-hole portion, and developing the exposed photosensitive mask material. And a step of forming a mask pattern.

Furthermore, in this case, by optimizing the exposure amount in the exposure step using the first exposure mask, after development, the trench pattern of the photosensitive mask material filled in the through-hole is developed. It is preferable to leave a portion below the bottom.

[0026]

(First Embodiment) A first embodiment of the present invention.
An embodiment will be described with reference to the drawings.

FIGS. 1 (a) to 1 (d) and FIGS. 2 (a) to 2 (a)
FIG. 2C shows a cross-sectional configuration in a process order of a wiring forming method by a dual damascene method according to the first embodiment of the present invention.

First, as shown in FIG. 1A, an insulating film 12 made of a silicon oxide film or the like is deposited on an insulating substrate 11. Here, the insulating substrate 11 includes a substrate in which an insulating film is formed on a semiconductor substrate. Although not shown, an active element such as a transistor may be formed. May be formed. continue,
After a first trench pattern is formed in the insulating film 12 using lithography and etching, the first trench pattern is formed on the side and bottom surfaces of the first trench pattern as necessary.
A first barrier film 13 made of a tantalum nitride film or the like for preventing diffusion of a wiring material made of metal and improving the reliability of the wiring is formed by an evaporation method or the like. After that, the first wiring material 14 containing copper (Cu) is embedded. Subsequently, unnecessary portions of the first barrier film 13 and the first wiring material 14 are removed by chemical mechanical polishing, and the upper surfaces thereof are flattened. A first metal wiring 15 made of one wiring material 14 is formed. Thereafter, a protection insulating film 16 made of a silicon nitride film or the like for protecting the first metal wiring 15 is formed on at least the upper surface of the first metal wiring 15, and then a silicon oxide film or the like is formed on the protection insulating film 16. An interlayer insulating film 17 is formed. Here, the interlayer insulating film 17 may have a laminated structure.
The protective insulating film 16 is not always necessary.

Another method of forming the first metal wiring 15 shown in FIG. 1A may be as follows. First, a first barrier film 13 and a first wiring material 14 are deposited on an insulating substrate 11, and subsequently, a first metal wiring 15 is patterned using a lithography method, an etching method, or the like. An insulating film 12 and an interlayer insulating film 17 are deposited. Thereafter, unnecessary portions of the interlayer insulating film 17 are removed by using a chemical mechanical polishing method or the like. In this case,
The first barrier film 13 is formed on both side surfaces of the first metal wiring 15.
Is not formed.

Next, as shown in FIG. 1B, a through hole (contact hole) 17a is formed in the interlayer insulating film 17 above the first metal wiring 15 by using lithography and etching. . At this time, the protection insulating film 16 may also be etched to expose the first metal wiring 15 to the through hole 17a. After the formation of the through-hole 17a, the through-hole 1 is formed to protect the surface of the protective insulating film 16 or the first metal wiring 15 exposed in the through-hole 17a.
A portion (deep portion) below the bottom (depth) of the second trench pattern formed in a later step may be filled with a protective resist or the like in 7a.

Next, as shown in FIG. 1C, the entire surface of the interlayer insulating film 17 including the through holes 17a is
A negative resist 18 is applied so that the exposed portion remains without being developed.

Subsequently, exposure light is applied to the negative resist 18 using an exposure mask (reticle) 30 for a negative resist in which the second trench pattern forming region is transferred to a light-shielding film pattern 30a such as chrome. Then, the negative resist exposure section 18B is exposed. At this time, the exposure mask 3
The light-shielding film pattern 30a formed in the negative resist 18 causes the second resist pattern 18 to be filled in the second trench pattern formation region and the through hole 17a located in the second trench pattern formation region. Since 18A is not irradiated with exposure light, it remains unexposed.

Next, as shown in FIG. 1D, the negative resist 18 is developed by developing the negative resist 18.
Unexposed negative resist 18 out of 8
The mask pattern 18C having an opening in the second trench pattern formation region is formed by removing A and exposing the exposed negative type resist exposed portion 18B. Here, the negative resist unexposed portion 18A embedded in the through hole 17a is removed because it is not exposed.

Next, as shown in FIG. 2A, the interlayer insulating film 17 is etched to a predetermined depth using the mask pattern 18C, so that the upper portion of the interlayer insulating film 17 is etched. A second trench pattern 17b whose bottom is connected to the through hole 17a is formed. As etching conditions at this time, by performing dry etching with a strong sputtering property using a mixed gas containing CH ₄ , CHF ₃ and Ar, the upper portion of the through hole 17a in the interlayer insulating film 17 and the second trench pattern 17b are formed. The connection portion 17c with the bottom portion has a rounded shape. In addition, since a resist or the like is not buried in a portion above the bottom of the second trench pattern 17b in the through hole 17a, no etching residue is generated in the opening pattern of the interlayer insulating film 17. Subsequently, when the first metal wiring 15 is not exposed to the through hole 17a, the portion of the protective insulating film 16 exposed to the through hole 17a is removed by etching, and
The first metal wiring 15 is exposed on the bottom surface of 7a.

Next, as shown in FIG. 2B, after removing the mask pattern 18C, the entire surface including the through hole 17a and the second trench pattern 17b is formed on the interlayer insulating film 17 as necessary. Second barrier film 1 made of a tantalum nitride film or the like for improving the reliability of metal wiring
9 is formed. Subsequently, a second wiring material 20 containing Cu is filled over the entire surface including the through hole 17a and the second trench pattern 17b on the second barrier film 19. At this time, since the connection portion 17c between the upper portion of the through hole 17a and the bottom portion of the second trench pattern 17b has a round shape, the second wiring is formed even when the opening diameter of the through hole 17a is small. The material 20 can be reliably filled to the lower part of the through hole 17a. For this reason, since the disconnection of the connection portion between the first metal wiring 15 and the second metal wiring 21 is less likely to occur, it is possible to prevent a decrease in the reliability of the wiring due to a defective embedding.

Next, as shown in FIG. 2C, unnecessary portions of the second barrier film 19 and the second wiring material 20 on the interlayer insulating film 17 are removed by using a chemical mechanical polishing method or the like. By flattening these upper surfaces, the second barrier film 1
9 and a second wiring material 20, and a second metal wiring 21 electrically connected to the first metal wiring 15 is formed. The first barrier film 13 and the second barrier film 19
May not be the same material, and the first wiring material 14 and the second wiring material 20 may not be the same material.

Thereafter, an upper metal wiring layer or a wiring layer for wire bonding may be formed.

As described above, according to the first embodiment, when patterning the trench structure connected to the through hole 17a above the interlayer insulating film 17, a negative type resist is used for forming the second trench pattern. Resist 1
8, the unexposed portion 18A of the negative resist that has entered the through hole 17a is not exposed, and is dissolved and removed during development. Therefore, since the wiring is not interrupted by the etching residue of the second trench pattern forming resist inside the second metal wiring 21, it is possible to prevent the metal wiring from increasing in resistance or disconnection. As a result, it is possible to form a metal wiring by a dual damascene method, which has excellent electrical characteristics and improved reliability.

(Second Embodiment) Hereinafter, a second embodiment of the present invention will be described with reference to the drawings.

FIGS. 3 (a) to 3 (d) and FIGS. 4 (a) to 4 (a)
FIG. 4D shows a cross-sectional configuration in a process order of a wiring forming method by a dual damascene method according to the second embodiment of the present invention. 3A to FIG. 4D, FIG.
2C are denoted by the same reference numerals.

First, using the same method as in the first embodiment, as shown in FIG. 3A, the first barrier film 13 and the first barrier film 13 are embedded in the insulating film 12 on the insulating substrate 11. The first metal wiring 15 made of the wiring material 14 is formed.
Here, the insulating substrate 11 includes a substrate in which an insulating film is formed on a semiconductor substrate. Although not shown, active elements such as transistors and multilayer wiring may be formed. Subsequently, a protective insulating film 16 and an interlayer insulating film 17 are sequentially formed on the insulating film 12 and the first metal wiring 15.

Next, as shown in FIG. 3B, a through hole 17a is formed in the interlayer insulating film 17 above the first metal wiring 15. At this time, the protective insulating film 16
The first metal wiring 15 may be exposed by etching the portion exposed in the through hole 17a in FIG.

Next, as shown in FIG. 3C, a first positive type used for i-line exposure with a wavelength of about 365 nm, for example, as a filler, is formed on the entire surface of the interlayer insulating film 17 including the through holes 17a. Apply resist. Subsequently, the interlayer insulating film 17 is formed on the first positive resist without using a mask.
The first positive resist 22 is left in the through-hole 17a by performing development after performing exposure with an exposure amount capable of exposing the film thickness of the first positive resist formed above to the thickness. At this time, the first positive resist 22
Is preferably aligned with the upper surface of the interlayer insulating film 17.

Next, as shown in FIG. 3D, over the entire surface including the first positive resist 22 on the interlayer insulating film 17, KrF sensitive to exposure light having a wavelength of 248 nm or less.
A second positive-type resist is applied. After that, the second positive resist having a wavelength of 248 nm or less is subjected to pattern exposure and development to form a second trench having an opening 23a for forming a second trench pattern.
Is formed. At this time, the first positive type resist 22 is not exposed at the wavelength of the exposure light used for exposing the second positive type resist 23, and therefore remains in the through hole 17a.

Next, as shown in FIG. 4A, the first positive resist 22 remaining in the through hole 17a is subjected to i-line exposure and then to a predetermined development. Only the first positive type resist 22 inside the through hole 17a is selected while maintaining the pattern shape of the second positive type resist 23 provided with the opening 23a for forming the second trench pattern. Can be removed. At this time, since the positive resist 23 is not exposed by i-line exposure, it can remain as it is. Thus, the first exposure light having different exposure wavelengths is formed in the through hole 17a.
Is filled as a filler so that when the second positive resist 23 for forming the second trench pattern is applied, the second positive resist 23 is filled in the through hole 17a. Never get into it. Here, in the first positive resist 22, which is a filler, a portion below the bottom of the second trench pattern formed in a later step is left, so that the protective insulating film 16 or the first metal wiring is formed. The portion exposed to the through hole 17a in 15 may be protected.

Next, as shown in FIG. 4B, the interlayer insulating film 17 is etched to a predetermined depth using a resist pattern made of the second positive resist 23 as a mask. A second trench pattern 17b whose bottom is connected to the through-hole 17a is formed above the interlayer insulating film 17. At this time, the etching is performed so that the connection portion 17c between the top of the through hole 17a and the bottom of the second trench pattern 17b in the interlayer insulating film 17 is rounded. In addition, the first positive resist 22 is pre-filled and selectively removed in a portion of the through hole 17a above a position which is the bottom of the second trench pattern 17b. Therefore, the second positive type resist 23 for forming the second trench pattern 17b is not buried in the through hole 17a, so that the second positive type resist 23 is formed on the inner surface of the second trench pattern 17b in the interlayer insulating film 17. No etching residue of the resist 23 remains. Subsequently, the first metal wiring 15
Is not exposed to the through hole 17a, the portion of the protective insulating film 16 exposed to the through hole 17a is removed by etching to expose the first metal wiring 15 on the bottom surface of the through hole 17a.

After that, the second embodiment is the same as the first embodiment, and as shown in FIG.
3 is removed, the through holes 17 on the interlayer insulating film 17 are removed.
a and the entire surface including the second trench pattern 17b.
After the barrier film 19 is formed, the second wiring material 20 is filled. Subsequently, as shown in FIG. 4D, unnecessary second barrier film 19 and second wiring material 20 on interlayer insulating film 17 are removed and their upper surfaces are planarized.
A second metal wiring 21 electrically connected to the first metal wiring 15 is formed.

As described above, according to the second embodiment, before the patterning of the trench structure connected to the through hole 17a is performed on the upper part of the interlayer insulating film 17, the filler for filling the through hole 17a is A first positive resist 22 for i-line exposure is used, and a second positive resist 23 for KrF having a different exposure wavelength from the first positive resist 22 is used as a resist for forming a second trench pattern. ing. As a result, after forming the second positive resist 23 provided with the opening 23a for forming the second trench pattern 17b, the through hole is formed without impairing the pattern shape of the second positive resist 23. The first positive type resist 22 filled in the inside of 17a can be selectively removed. For this reason, since the wiring is not interrupted by the etching residue of the second trench pattern forming resist inside the second metal wiring 21, it is possible to prevent the metal wiring from having high resistance or disconnection. As a result, it is possible to form a metal wiring by a dual damascene method, which has excellent electrical characteristics and improved reliability.

Further, since the connecting portion 17c between the upper portion of the through hole 17a and the bottom of the second trench pattern 17b has a round shape, even if the opening diameter of the through hole 17a is small, the second connecting portion 17c has the second shape. Since the wiring material 20 can be reliably filled into the lower portion of the through hole 17a, disconnection due to poor embedding can be prevented.

Further, the first barrier film 13 and the protective insulating film 16 are not always necessary.

As the first positive type resist 22,
Although a resist for i-line exposure was used, the present invention is not limited to this.
Any resist can be used as long as it is photosensitive at a longer wavelength than the positive resist 23 described above. Here, the second positive resist 23
Since a KrF resist having an exposure wavelength of 248 nm is used as the first positive resist 22, for example,
A resist sensitive to g-rays having an exposure wavelength of about 436 nm may be used.

(Third Embodiment) Hereinafter, a third embodiment of the present invention will be described with reference to the drawings.

FIGS. 5A to 5 D and FIGS.
FIG. 6C shows a sectional configuration in the order of steps of a wiring forming method by a dual damascene method according to the third embodiment of the present invention. 5A to FIG. 6C, FIG.
2C are denoted by the same reference numerals.

First, using the same method as in the first embodiment, as shown in FIG. 5A, the first barrier film 13 and the first barrier film 13 are embedded in the insulating film 12 on the insulating substrate 11. The first metal wiring 15 made of the wiring material 14 is formed.
Here, the insulating substrate 11 includes a substrate in which an insulating film is formed on a semiconductor substrate, and although not shown, active elements such as transistors and multilayer wiring may be formed. Subsequently, a protective insulating film 16 and an interlayer insulating film 17 are sequentially formed on the insulating film 12 and the first metal wiring 15.

Next, as shown in FIG. 5B, a through hole 17a is formed in the interlayer insulating film 17 above the first metal wiring 15. At this time, the protective insulating film 16
The first metal wiring 15 may be exposed by etching the portion exposed in the through hole 17a in FIG.

Next, as shown in FIG. 5C, a vapor phase growth method using a low step coverage, for example, a plasma CVD method using a parallel plate type monosilane gas is used.
On the interlayer insulating film 17, a closing insulating film 25 made of a silicon oxide film (plasma oxide film) is formed so as to cover the upper part of the opening of the through hole 17a.

Next, as shown in FIG. 5D, a second trench pattern having a larger opening width than the through hole 17a is formed on the closing insulating film 25 at a position corresponding to the through hole 17a. A resist pattern 26 having an opening is formed. At this time, since the upper portion of the opening of the through hole 17a is closed by the closing insulating film 25, the resist does not enter the through hole 17a.

Next, as shown in FIG. 6A, after the closing insulating film 25 is etched using the resist pattern 26 as a mask, the interlayer insulating film 17 is etched to a predetermined depth. Then, a second trench pattern 17b whose bottom is connected to the through hole 17a is formed above the interlayer insulating film 17. At this time, the interlayer insulating film 1
Etching is performed so that the connection portion 17c between the upper portion of the through hole 17a and the bottom portion of the second trench pattern 17b in FIG. 7 has a rounded shape. In addition, since the resist does not enter into the through-hole 17a in which the upper part of the opening is closed by the closing insulating film 25,
No etching residue occurs in the opening pattern of the interlayer insulating film 17. Subsequently, when the first metal wiring 15 is not exposed to the through hole 17a, a portion of the protective insulating film 16 exposed to the through hole 17a is removed by etching, and a first surface is formed on the bottom surface of the through hole 17a. The metal wiring 15 is exposed.

After that, as in the first embodiment, as shown in FIG. 6B, after removing the resist pattern 26, the through hole 17a on the interlayer insulating film 17 and the second trench are formed. After forming the second barrier film 19 on the entire surface including the pattern 17b, the second wiring material 20 is filled. Subsequently, as shown in FIG. 6C, the interlayer insulating film 17 is formed.
Unnecessary second barrier film 19 and second wiring material 20
Is removed to planarize these upper surfaces, thereby achieving the first
The second metal wiring 21 electrically connected to the metal wiring 15 is formed. At this time, the closing insulating film 25 may be removed at the same time.

As described above, according to the third embodiment, before patterning the trench structure connected to the through hole 17a above the interlayer insulating film 17, the upper portion of the opening of the through hole 17a is removed. The second metal wiring 21 is covered with a second
The wiring is not interrupted due to the etching residue of the trench pattern forming resist. As a result, the resistance of the metal wiring can be prevented from being increased or the wire can be prevented from being broken, so that the metal wiring can be formed by the dual damascene method which has excellent electrical characteristics and improved reliability.

Since the connecting portion 17c between the upper portion of the through hole 17a and the bottom of the second trench pattern 17b has a round shape, even if the opening diameter of the through hole 17a is small, the second connecting portion 17c has the second shape. Since the wiring material 20 can be reliably filled into the lower portion of the through hole 17a, disconnection due to poor embedding can be prevented.

Note that the first barrier film 13 and the protective insulating film 16 are not always necessary.

(Fourth Embodiment) Hereinafter, a fourth embodiment of the present invention will be described with reference to the drawings.

FIGS. 7 (a) to 7 (d) and FIGS. 8 (a) to 8 (a)
FIG. 8C shows a cross-sectional configuration in a process order of a wiring forming method by a dual damascene method according to the fourth embodiment of the present invention. 7A to 8C, FIG.
2C are denoted by the same reference numerals.

First, using the same method as in the first embodiment, as shown in FIG. 7A, the first barrier film 13 and the first barrier film 13 are embedded in the insulating film 12 on the insulating substrate 11. The first metal wiring 15 made of the wiring material 14 is formed.
Here, the insulating substrate 11 includes a substrate in which an insulating film is formed on a semiconductor substrate. Although not shown, active elements such as transistors and multilayer wiring may be formed.
Subsequently, a protective insulating film 16 and an interlayer insulating film 17 are sequentially formed on the insulating film 12 and the first metal wiring 15.

Thereafter, a first positive type resist 27 is applied on the interlayer insulating film 17, and an exposure mask (reticle) 31 for the positive type resist obtained by transferring a through-hole forming pattern to a light-shielding film pattern 31a of chrome or the like. Is used to irradiate the first positive type resist 27 with exposure light to expose a first positive type resist exposed portion 27A to be a through hole formation region. At this time, the first positive resist unexposed portion 27B to which the exposure light is not irradiated remains unexposed due to the light shielding film pattern 31a formed on the exposure mask 31 of the first positive resist 27.

Next, as shown in FIG. 7B, by developing the first positive type resist 27,
The first positive resist exposed portion 27A that is exposed and exposed to the exposure light is removed, and the first positive resist unexposed portion 27B that remains unexposed is left, so that the first metal wiring 15 A first mask pattern 27C having an opening for forming a through hole is formed above the first mask pattern 27C. Subsequently, using the first mask pattern 27C,
By etching the interlayer insulating film 17, a through hole 17 a is formed in the interlayer insulating film 17 above the first metal wiring 15. At this time, the portion of the protective insulating film 16 that is exposed to the through hole 17a may be etched to expose the first metal wiring 15.

Next, as shown in FIG. 7C, after removing the first mask pattern 27C, a second positive resist 28 is applied on the entire surface including the through hole 17a on the interlayer insulating film 17. I do. Subsequently, by using the exposure mask 31 used in the through-hole forming step again, the second positive-type resist exposed portion 28A of the second positive-type resist 28 filled in the through-hole 17a can be exposed. Exposure is performed at the exposure amount. At this time, the interlayer insulating film 17
The second positive resist unexposed portion 28B located above remains unexposed.

Next, as shown in FIG.
The second positive resist 28 is exposed using an exposure mask (not shown) having an opening for forming a second trench pattern including the through hole 17a and having a larger opening width than the through hole 17a. And the second exposed
By developing the positive resist 28, the second positive resist exposed portion 28A is formed inside the through hole 17a.
, A second mask pattern C having an opening for forming a second trench pattern is formed from the second positive resist. Here, by optimizing the exposure conditions and the like, the portion inside the through hole 17a in the second positive resist exposed portion 28A and below the bottom of the second trench pattern formed in a later step May be left to protect a portion of the protective insulating film 16 or the first metal wiring 15 exposed to the through hole 17a.

Next, as shown in FIG. 8A, the interlayer insulating film 17 is etched to a predetermined depth using the second mask pattern 28C, so that the interlayer insulating film 17 is etched. A second trench pattern 17b whose bottom is connected to the through hole 17a is formed on the upper part. At this time, the connection portion 17 between the upper portion of the through hole 17a and the bottom portion of the second trench pattern 17b in the interlayer insulating film 17 is formed.
Etching is performed so that c has a rounded shape. In addition, from a region above the position of the bottom of the second trench pattern 17b in the through hole 17a, a second exposure is performed by using the exposure mask 31 used in the through hole forming process again, and a subsequent development is performed. 2
Is removed in advance.
Thus, no etching residue occurs in the opening pattern of the interlayer insulating film 17. Subsequently, when the first metal wiring 15 is not exposed to the through hole 17a, a portion of the protective insulating film 16 exposed to the through hole 17a is removed by etching, and the through hole 17a is removed.
The first metal wiring 15 is exposed on the bottom surface of the substrate.

Thereafter, as in the first embodiment, as shown in FIG. 8B, the entire surface including the through hole 17a and the second trench pattern 17b on the interlayer insulating film 17 is covered with the second After the barrier film 19 is formed, the second wiring material 20 is filled. Subsequently, as shown in FIG. 8C, the unnecessary second barrier film 19 and the second wiring material 20 on the interlayer insulating film 17 are removed, and the upper surfaces thereof are planarized, whereby the first The second metal wiring 21 electrically connected to the metal wiring 15 is formed.

As described above, according to the fourth embodiment, when patterning the trench structure connected to the through hole 17a above the interlayer insulating film 17, the exposure mask 31 for forming the through hole is used again. In order to expose the second positive resist exposure portion 28A filled in the through hole 17a of the second positive resist 28 with an exposure amount capable of exposing the through hole 17a, the through hole 17a is exposed.
Since the light can be exposed to the bottom of the second positive type resist exposed portion 28A that has entered, it can be dissolved and removed by subsequent development. Therefore, since the wiring is not interrupted by the etching residue of the second trench pattern forming resist inside the second metal wiring 21, it is possible to prevent the metal wiring from increasing in resistance or disconnection. As a result, it is possible to form a metal wiring by a dual damascene method, which has excellent electrical characteristics and improved reliability.

Further, since the connecting portion 17c between the upper portion of the through hole 17a and the bottom of the second trench pattern 17b has a round shape, even if the opening diameter of the through hole 17a is small, the second connecting portion 17c has the second shape. Since the wiring material 20 can be reliably filled into the lower portion of the through hole 17a, disconnection due to poor embedding can be prevented.

Note that the first barrier film 13 and the protective insulating film 16 are not always necessary.

[0075]

According to the wiring forming method of the present invention, when forming a trench pattern connected to a through hole formed on an insulating film, the portion above the bottom of the trench pattern is formed. Since no resist is left in the trench pattern, no etching residue is generated inside the trench pattern. As a result, interruption of the wiring due to the etching residue does not occur, and the resistance of the wiring can be prevented from being increased or the wiring can be prevented from being broken.

[Brief description of the drawings]

FIGS. 1A to 1D are cross-sectional views in the order of steps showing a wiring forming method according to a first embodiment of the present invention.

FIGS. 2A to 2C are cross-sectional views in a process order showing a wiring forming method according to a first embodiment of the present invention.

FIGS. 3A to 3D are cross-sectional views in the order of steps showing a wiring forming method according to a second embodiment of the present invention.

FIGS. 4A to 4D are cross-sectional views in the order of steps showing a wiring forming method according to a second embodiment of the present invention.

FIGS. 5A to 5D are cross-sectional views in the order of steps showing a wiring forming method according to a third embodiment of the present invention.

FIGS. 6A to 6C are cross-sectional views in the order of steps showing a wiring forming method according to a third embodiment of the present invention.

FIGS. 7A to 7D are cross-sectional views in the order of steps showing a wiring forming method according to a fourth embodiment of the present invention.

FIGS. 8A to 8C are cross-sectional views in the order of steps showing a wiring forming method according to a fourth embodiment of the present invention.

FIGS. 9A to 9D are cross-sectional views in the order of steps showing a method of forming a wiring by a conventional damascene method.

FIGS. 10A and 10B are cross-sectional views in the order of steps showing a conventional wiring forming method by a damascene method.

[Explanation of symbols]

 Reference Signs List 11 Insulating substrate 12 Insulating film 13 First barrier film 14 First wiring material 15 First metal wiring 16 Protective insulating film 17 Interlayer insulating film 17a Through hole 17b Second trench pattern 17c Connection 18 Negative resist 18A Negative resist unexposed part 18B Negative resist exposed part 18C Mask pattern 19 Second barrier film 20 Second wiring material 21 Second metal wiring 22 First positive resist 23 Second positive resist 23a Second Trench forming pattern 25 closing insulating film (blocking film) 26 resist pattern 27 first positive resist 27A first positive resist exposed portion 27B first mask pattern unexposed portion 27C first mask pattern 28 second Of the positive resist 28A of the second positive resist exposed portion 28B of the second mask Pattern unexposed portion 28C second mask pattern 30 exposing mask 30a shielding film pattern 31 exposing mask 31a shielding film pattern

Continuation of the front page (72) Inventor Tetsuya Ueda 1-1, Sachimachi, Takatsuki City, Osaka Prefecture Inside Matsushita Electronics Corporation (56) References JP-A-9-222371 (JP, A) JP-A-3-288438 (JP, A) JP-A-10-340952 (JP, A) JP-A-10-229122 (JP, A) JP-A-10-199972 (JP, A) JP-A-2000-58647 (JP, A) JP JP-A-11-162882 (JP, A) JP-A-11-154703 (JP, A) JP-A-2000-12538 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/3205 H01L 21/321 H01L 21/3213 H01L 21/768

Claims (8)

(57) [Claims] A step of forming a through hole in an insulating film on a substrate; and a step of filling a filler only in the through hole.
(C) forming a photosensitive mask material on the insulating film including the through hole filled with the filler, and patterning the photosensitive mask material to form an opening including the through hole. (D) forming a mask pattern for forming a trench having; (e) selectively removing the filler after the step (d); and forming the mask pattern after the step (e). Forming a trench pattern connected to the through hole above the insulating film by etching the insulating film to a predetermined depth using the mask as a mask (f).
When the e Bei a through hole and a step of filling a conductive material in said trench pattern in (g), the photosensitive mask material is a positive resist, the filler, the positive resist sensitive Than the wavelength
Wherein the resist is photosensitive in a long wavelength region . 2. The wiring forming method according to claim 1 , wherein, in the step (e), a portion of the filler filled in the through hole, which is lower than a bottom of the trench pattern, is left. A wiring forming method characterized by the above-mentioned. 3. The wiring forming method according to claim 1 , wherein in the step (f), a round shape is formed at a connection portion between the upper part of the through hole and the bottom part of the trench pattern in the insulating film. A wiring forming method characterized by the above-mentioned. 4. A step (a) of forming a through hole in an insulating film on a substrate, and after the step (a), the through hole is formed on the insulating film by using a vapor deposition method having a low step coverage. (B) forming an occlusion film covering the opening of (c), and (c) forming a photosensitive mask material on the occlusion film.
Patterning the photosensitive mask material to form a mask pattern for forming a trench having an opening including the through hole; and (d) etching the blocking film using the mask pattern as a mask. (E) forming a trench pattern connected to the through hole on the insulating film by etching the insulating film to a predetermined depth; and forming a conductive pattern in the through hole and the trench pattern. A step (f) of filling a conductive material. 5. The wiring forming method according to claim 4 , wherein in the step (e), a round shape is formed at a connection portion between the upper part of the through hole and the bottom part of the trench pattern in the insulating film. Characteristic wiring forming method. 6. A step (a) of forming a through hole in an insulating film on a substrate using a first exposure mask, and a step (b) of forming a photosensitive mask material on the insulating film including the through hole. After exposing a through-hole portion in the photosensitive mask material using the first exposure mask, exposure was performed using a second exposure mask for forming a trench including the through-hole portion, and the exposure was performed. (C) forming a mask pattern for forming a trench having an opening including the through hole by performing development on a photosensitive mask material; (D) forming a trench pattern connected to the through hole on the insulating film by etching to a predetermined depth; Wiring forming method characterized by comprising the step (e) filling a conductive material in Le and the trench pattern within. 7. The wiring forming method according to claim 6 , wherein the exposure amount in the exposure step using the first exposure mask is optimized to fill the through hole after development. A wiring forming method, wherein a portion of a photosensitive mask material below a bottom of the trench pattern is left. 8. The wiring forming method according to claim 6 , wherein in the step (d), a round shape is formed at a connection portion between the upper part of the through hole and the bottom part of the trench pattern in the insulating film. A wiring forming method characterized by the above-mentioned.