JP2001007200A - Method for forming wiring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize superior electric characteristic with high reliability without increasing an area of a semiconductor chip in a wiring process required for burying a through hole of a high aspect ratio. SOLUTION: A first metal wiring 2 and an insulation film 3 are formed on an insulation substrate 1, and a surface of the insulation film 3 is flattened to form a through hole 4. The through hole 4 is buried with a metal material 5 such as tungsten, etc., by a film forming technology superior in a burying characteristic. The metal material 5 is removed at a depth or more of a trench 7 to be formed later. Etching is performed by use of a resist 6 as a mask to form the trench 7. A metal material 8 superior in reliability and electric characteristic is deposited as a wiring in the through hole 4 or the trench 7. At this time, since the metal material 5 has been already buried in the through hole 4 to reduce an aspect ratio, a void or a seam is not generated. Thereafter, the unnecessary metal material 8 is removed to form a second metal wiring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a method for forming a wiring which requires a high aspect ratio through hole to be embedded.

[0002]

2. Description of the Related Art A conventional method for forming a so-called damascene wiring will be described below with reference to the drawings. FIG.
1A to 1F are cross-sectional views showing a conventional wiring forming method, wherein 1 is an insulating substrate, 2 is a first metal wiring formed on an insulating substrate 1, 3 is an insulating film, and 4 is an insulating film. Through hole,
4a is a through hole in which no trench is formed, 6 is a resist, 7 is a trench formed in the insulating film 3, 8 is a metal material excellent in reliability and electric characteristics as wiring, and 9 is a seam or void. FIG. 6G is a cross-sectional view formed by another conventional method.

[0003] First, the insulating substrate 1 may be provided with a transistor element or the like formed on the substrate, or a plurality of metal wirings may be formed on the insulating substrate 1. Omitted. A first metal wiring 2 is formed on the insulating substrate 1, and an insulating film 3 is formed by a CVD method or the like. Then, the surface of the insulating film 3 is flattened by a chemical mechanical polishing technique or a dry etching technique (FIG. 6A). The first metal wiring 2 and the insulating film 3 are filled with a metal material after forming a trench in the insulating film, unnecessary portions are removed by using a chemical mechanical polishing technique, and the insulating film is deposited. It may be formed. Note that the first metal wiring 2 and the insulating film 3 may each have a laminated structure of two or more layers.

Next, through holes 4 are formed in the insulating film 3 according to the design (FIG. 6- (b)), and a trench pattern is formed in the resist 6 (FIG. 6- (c)). And
Using the resist 6 on which the trench pattern is formed as a mask, a trench 7 is formed in the insulating film 3 using a dry etching technique (FIG. 6D). Here, a through hole 4a in which the trench 7 is not formed exists in a part of the through hole 4.

Next, a metal material 8 having excellent reliability and electrical characteristics is deposited as wiring such as copper so as to fill the through holes 4 and trenches 7 formed in the insulating film 3 (FIG. 6- (e). )). Immediately before depositing the metal material 8, a titanium film, a titanium nitride film, or the like may be deposited in order to improve the adhesion and the barrier property of the buried metal material, but these are not shown.

Thereafter, unnecessary metal material 8 is removed by using a chemical mechanical polishing method or the like, and a second metal wiring made of metal material 8 is formed (FIG. 6- (f)).

After that, the next metal wiring layer and the wiring layer for wire bonding may be formed, but these are not shown.

[0008]

However, according to the conventional method for forming a wiring, if the ratio of the thickness of the insulating film 3 to the hole diameter of the through hole 4a (hereinafter referred to as the aspect ratio) becomes large, the wiring as the wiring is formed. When the metal material 8 having excellent reliability is formed by using a film forming technique having low embedding characteristics, voids or seams 9 are generated in the through holes 4a due to incomplete embedding (FIG. 6). (E), (f)). When the voids and the seam 9 are generated, the electromigration resistance is deteriorated, and there is a problem that the high reliability of the metal material 8 cannot be realized. For example, when copper having excellent reliability and electrical characteristics is formed as a wiring by a plating technique, if the aspect ratio becomes 7 or more, a void or a seam 9 is generated, so that electromigration resistance is deteriorated.

As shown in FIG. 6G, through holes 4 are formed in the insulating film 3 and metallization is immediately performed using a film forming technique having excellent filling characteristics, as shown in FIG. The material 5 is buried, the insulating film 3 is deposited again, and then the trench 7 is formed. This time, the wiring is buried with a metal material 8 which is inferior in burying characteristics but excellent in reliability and electric characteristics as wiring. Then, there is a method of forming a wiring. However, in this case, the trench 7 must be formed on the through hole 4 without fail. In order to realize a through-hole 4a in which no trench is formed as shown in FIG. 6D by this process, a trench pattern having the same size as the through-hole 4a must be formed with a resist. However, in the lithography technique, a trench pattern having the same size as the through hole 4a cannot be formed simultaneously with another trench pattern, and as shown in FIG. A trench 7 having a large size must be formed, which is larger than the case of FIG. Therefore, there is a problem that the area of the semiconductor chip becomes large.

An object of the present invention is to realize high reliability and excellent electrical characteristics of a wiring without increasing the area of a semiconductor chip in a wiring process in which a through hole having a high aspect ratio must be buried.

[0011]

According to a first aspect of the present invention, there is provided a process of forming a through hole in an insulating film, and a step of forming a through hole with a first metal material by using a film forming technique having excellent filling characteristics. A step of burying the hole, a step of selectively removing only the first metal material, and a step of lowering the surface of the first metal material in the through hole to a height equal to or lower than the vicinity of a bottom surface of a trench to be formed later; A step of forming a trench in a surface portion of the insulating film by etching the insulating film using the patterned resist as a mask; and forming a trench and a through hole with a second metal material excellent in reliability and electrical characteristics as a wiring. And a step of removing an unnecessary portion of the second metal material deposited on the surface of the insulating film. Even if the through hole has a high aspect ratio, The second metal material, which is excellent in reliability and electrical characteristics, is buried as a wiring on the first metal material buried by using a film forming technology having excellent embedding characteristics, so that voids and seams do not occur. In addition, high reliability and excellent electrical characteristics as wirings of the second metal material can be realized, and according to this method, it is not necessary to increase the area of the semiconductor chip.

According to a second aspect of the present invention, a step of forming a through hole in an insulating film, a step of growing a first metal material from a bottom of the through hole, and a step of forming a first metal material in the through hole are performed. A step of embedding a first metal material so that the surface has a height equal to or lower than the vicinity of a bottom surface of a trench to be formed later; and etching the insulating film using a resist in which a trench pattern is formed as a mask, thereby forming a surface of the insulating film. Forming a trench in the portion, filling the trench and the through hole with a second metal material excellent in reliability and electrical characteristics as a wiring, and forming a second portion of an unnecessary portion deposited on the surface of the insulating film. And removing the metal material. Even if the through hole has a high aspect ratio, the first On top of the material, on the reliability and as a wiring
Since the second metal material excellent in electric characteristics is embedded, high reliability and excellent electric characteristics as a wiring of the second metal material can be realized without generating voids and seams. In this case, there is no need to increase the semiconductor chip area.

According to a third aspect of the present invention, in the method for forming a wiring according to the second aspect, the first hole is formed in the through hole.
This is characterized by reversing the order of the step of embedding the metal material and the step of forming a trench in the surface portion of the insulating film, and has the same effect as the second aspect.

According to a fourth aspect of the present invention, a step of forming a through hole in an insulating film, a step of burying the through hole with a first metal material using a film forming technique having excellent filling characteristics, Removing a portion of the first metal material deposited on the surface of the insulating film other than the through hole;
Etching is performed under a dry etching condition in which an etching selectivity of the insulating film with respect to the first metal material is 1 to 0.5 using the resist in which the trench pattern is formed as a mask. A step of lowering the surface of the first metal material in the through hole directly connected to the trench to a height equal to or lower than the bottom of the trench, and forming the trench and the through hole with a second metal material excellent in reliability and electrical characteristics as a wiring And a step of removing an unnecessary portion of the second metal material deposited on the surface of the insulating film. Even if the through-hole has a high aspect ratio, it has excellent filling characteristics. On top of the first metal material embedded using membrane technology,
Since the second metal material, which is excellent in reliability and electrical characteristics, is embedded as wiring, no voids or seams are generated.
High reliability and excellent electrical characteristics as the wiring of the second metal material can be realized, and according to this method, it is not necessary to increase the area of the semiconductor chip.

According to a fifth aspect of the present invention, a step of forming a through hole in an insulating film, a step of burying the through hole with a first metal material using a film forming technique having excellent filling characteristics, Removing a portion of the first metal material deposited on the surface of the insulating film other than the through hole;
By etching the insulating film using the resist with the trench pattern formed as a mask, a trench is formed on the surface portion of the insulating film, and at the same time, the surface of the first metal material formed in the through hole directly connected to the trench is formed by the trench. A step of selectively etching only the first metal material by a thickness of 1 to 2 times the depth of the trench, and a wiring excellent in reliability and electrical characteristics. The method includes a step of embedding the trench and the through hole with a second metal material and a step of removing an unnecessary portion of the second metal material deposited on the surface of the insulating film. Even if there is a second metal material having excellent reliability and electrical characteristics as a wiring, the first metal material is buried by using a film forming technique having excellent burying characteristics. Embed Therefore, without creating a void or seam, the second can achieve high reliability and excellent electrical characteristics as a wiring which metal material has, and there is no need to increase the semiconductor chip area according to this method.

According to a sixth aspect of the present invention, there is provided a method for forming a through hole in an insulating film, and etching the insulating film using a resist having a trench pattern as a mask, thereby forming a trench on a surface portion of the insulating film. Forming a through hole with a first metal material by using a film forming technique having excellent filling characteristics; and selectively removing only the first metal material to form a first hole in the through hole.
A step of lowering the surface of the metal material to a height equal to or less than the vicinity of the bottom surface of the trench to be formed later, and embedding the trench and the through hole with a second metal material excellent in reliability and electrical characteristics as a wiring; Removing the unnecessary portion of the second metal material deposited on the surface of the insulating film, even if the through hole has a high aspect ratio.
1st embedded using film forming technology with excellent embedding characteristics
Since the second metal material, which is excellent in reliability and electrical characteristics, is embedded as a wiring on the metal material of the above, the wiring has high reliability and excellentness as the wiring of the second metal material without generating voids or seams. In addition, according to this method, it is not necessary to increase the area of the semiconductor chip.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, also in the embodiment of the present invention,
As in the conventional example, the process of damascene wiring will be described.

(First Embodiment) Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIGS. 1A to 1H are process cross-sectional views showing a method for forming a wiring according to a first embodiment of the present invention, wherein 1 is an insulating substrate, and 2 is a first insulating substrate formed on the insulating substrate 1. Metal wiring,
3 is an insulating film formed on the first metal wiring 2, 4 is a through hole, 4a is a through hole in which no trench is formed, 5 is a metal material, 6 is a resist, 7 is a trench formed in the insulating film 3, Reference numeral 8 denotes a metal material having excellent wiring reliability and electrical characteristics.

First, the insulating substrate 1 may be provided with a transistor element or the like formed on the substrate, or a plurality of metal wirings may be formed on the insulating substrate 1. It is not shown because it is not directly related to the above. A first metal wiring 2 is formed on the insulating substrate 1, and an insulating film 3 is formed by a CVD method or the like.
Then, the surface of the insulating film 3 is flattened by a chemical mechanical polishing technique or a dry etching technique (FIG. 1).
(A)). The first metal wiring 2 and the insulating film 3
May be formed by embedding a metal material after forming a trench in an insulating film, removing unnecessary portions using a chemical mechanical polishing technique, and further depositing an insulating film. Note that the first metal wiring 2 and the insulating film 3
Each may have a laminated structure of two or more layers.

Next, through holes 4 are formed in the insulating film 3 according to the design (FIG. 1- (b)). It should be noted that a part of the through hole 4 does not have a trench.
a exists.

Then, a metal material 5 such as tungsten is deposited by using a blanket vapor phase growth method or the like having excellent filling characteristics to completely fill the through hole 4 (FIG. 1).
-(C)). At this time, a titanium film, a titanium nitride film, or the like may be deposited to improve the adhesion and the barrier property of the embedded metal material. These are not shown because they do not directly relate to the present invention. Only unnecessary portions of the deposited metal material 5 are etched, and the metal material 5 is removed such that the height of the surface of the metal material 5 after the etching is lower than the bottom surface of the trench 7 to be formed later ( FIG. 1- (d)). The amount of the metal material 5 to be removed at this time may be determined by the embedding characteristics of the metal material 8 which is excellent in reliability and electrical characteristics as a wiring to be formed later.

Thereafter, a trench pattern is formed by the resist 6 (FIG. 1- (e)). At this time, no trench pattern is formed by the resist 6 on the through hole 4a. Using the resist 6 as a mask, a trench 7 is formed in the insulating film 3 using a dry etching technique (FIG. 1- (f)).

Next, a metal material 8 such as copper which is excellent in reliability and electrical characteristics as a wiring is deposited in the through holes 4 and the trenches 7 formed in the insulating film 3 (FIG. 1).
(G)). Immediately before depositing the metal material 8, a titanium film, a titanium nitride film, or the like may be deposited in order to improve the adhesion and the barrier property of the embedded metal material. These are not shown because they do not directly relate to the present invention. At this time, since the metal material 5 is already buried in the through holes 4 and 4a, the aspect ratio becomes small, and the metal material 8 is deposited without generating voids or seams even when the burying characteristics of the film forming technique of the metal material 8 are low. Can do things.

Thereafter, unnecessary metal material 8 is removed by using a chemical mechanical polishing method or a dry etching technique, and a second metal wiring made of metal material 8 is formed. (FIG. 1- (h)) At this time, since there is no void or seam in the second metal wiring in the through-holes 4 and 4a, the high reliability and excellent electric power that the metal material 8 has Characteristics can be realized.

As described above, according to the present embodiment, even if the through holes 4 and 4a have a high aspect ratio, they are excellent in reliability and electrical characteristics as wiring on the metal material 5 previously buried. Since the metal material 8 is buried in the metal material 8, high reliability and excellent electrical characteristics of the wiring of the metal material 8 can be realized without generating voids or seams. Also,
According to this method, it is not necessary to increase the area of the semiconductor chip.

In the present embodiment, the height of the surface of the metal material 5 after etching in the step of FIG.
Although the lower surface is made lower than the bottom surface of the trench 7 to be formed later, the surface of the metal material 5 after etching becomes the same height as the bottom surface of the trench 7 to be formed later, and is slightly higher than the bottom surface of the trench 7. It does not matter. However, when a large amount of the metal material 8 is buried in place of the metal material 5, the electrical characteristics such as low resistance are excellent.

(Second Embodiment) A second embodiment of the present invention will be described below with reference to the drawings. 2A to 2G are cross-sectional views showing the steps of a method for forming a wiring according to the second embodiment of the present invention, in which the same components as those in FIG. 1 are denoted by the same reference numerals.

First, the insulating substrate 1 may be provided with a transistor element or the like formed on the substrate, or a plurality of metal wirings may be formed on the insulating substrate 1. It is not shown because it is not directly related to the above. A first metal wiring 2 is formed on the insulating substrate 1, and an insulating film 3 is formed by a CVD method or the like.
Then, the surface of the insulating film 3 is flattened by a chemical mechanical polishing technique or a dry etching technique (FIG. 2).
(A)). The first metal wiring 2 and the insulating film 3
May be formed by embedding a metal material after forming a trench in an insulating film, removing unnecessary portions using a chemical mechanical polishing technique, and further depositing an insulating film. Note that the first metal wiring 2 and the insulating film 3
Each may have a laminated structure of two or more layers.

Next, through holes 4 are formed in the insulating film 3 according to the design (FIG. 2B). At this time, a part of the through hole 4 has a through hole 4a in which no trench is formed.

Then, a metal material 5 such as tungsten is deposited on the through hole 4 by using a film forming technique such as a selective vapor deposition method.
(FIG. 2- (c)). At this time, the height of the surface of the metal material 5 deposited in the through hole 4 is lower than the bottom of the trench 7 to be formed later. What is necessary is just to determine with the embedding characteristic of the film-forming technique of the excellent metal material 8.

After that, a trench pattern is formed by the resist 6 (FIG. 2D). At this time, no trench pattern is formed by the resist 6 on the through hole 4a. Using the resist 6 as a mask, a trench 7 is formed in the insulating film 3 using a dry etching technique (FIG. 2E).

Next, a metal material 8 such as copper which is excellent in reliability and electrical characteristics as a wiring is deposited in the through holes 4 and the trenches 7 formed in the insulating film 3 (FIG. 2).
(F)). Immediately before depositing the metal material 8, a titanium film, a titanium nitride film, or the like may be deposited in order to improve the adhesion and the barrier property of the embedded metal material. These are not shown because they do not directly relate to the present invention. At this time, since the metal material 5 is already buried in the through holes 4 and 4a, the aspect ratio becomes small, and the metal material 8 is deposited without generating voids or seams even when the burying characteristics of the film forming technique of the metal material 8 are low. Can do things.

Thereafter, the unnecessary metal material 8 is removed by using a chemical mechanical polishing method or a dry etching technique to form a second metal wiring made of the metal material 8 (FIG. 2G). . At this time, since there is no void or seam in the second metal wiring in the through holes 4 and 4a, the high reliability and excellent electrical characteristics of the metal material 8 can be realized.

As described above, also in this embodiment, the through holes 4 and 4a are buried with the metal material 8 which is excellent in reliability and electric characteristics as wiring on the metal material 5 which has been buried earlier. The same effect as in the first embodiment can be obtained.

In this embodiment, the height of the surface of the metal material 5 deposited in the through hole 4 in the step of FIG. 2C is lower than the bottom of the trench 7 to be formed later. However, the height may be the same as the bottom surface of the trench 7 or slightly higher than the bottom surface of the trench 7. However, the more the metal material 8 is buried instead of the metal material 5, the better the electrical characteristics such as low resistance.

In this embodiment, the through holes 4
After the formation, a metal material 5 is deposited in the through hole 4, and then the insulating film 3 is etched using the resist 6 as a mask to form a trench 7. After the through hole 4 is formed, the resist 6 having the trench pattern formed is used as a mask. The order may be changed so that the insulating film 3 is etched to form the trench 7, and then the metal material 5 is deposited in the through hole 4.

(Third Embodiment) A third embodiment of the present invention will be described below with reference to the drawings. 3A to 3H are cross-sectional views showing the steps of a method for forming a wiring according to the third embodiment of the present invention, and the same components as those in FIG. 1 are denoted by the same reference numerals.

First, the insulating substrate 1 may be provided with a transistor element or the like formed on the substrate, or a plurality of metal wirings may be formed on the insulating substrate 1. It is not shown because it is not directly related to the above. A first metal wiring 2 is formed on the insulating substrate 1, and an insulating film 3 is formed by a CVD method or the like.
Then, the surface of the insulating film 3 is flattened by a chemical mechanical polishing technique or a dry etching technique (FIG. 3).
(A)). The first metal wiring 2 and the insulating film 3
May be formed by embedding a metal material after forming a trench in an insulating film, removing unnecessary portions using a chemical mechanical polishing technique, and further depositing an insulating film. Note that the first metal wiring 2 and the insulating film 3
Each may have a laminated structure of two or more layers.

Next, through holes 4 are formed in the insulating film 3 according to the design (FIG. 3B). At this time, a part of the through hole 4 has a through hole 4a in which no trench is formed.

Then, a metal material 5 such as tungsten is deposited by using a blanket vapor phase growth method or the like having excellent filling characteristics to completely fill the through holes 4 (FIG. 3).
(C)). At this time, a titanium film, a titanium nitride film, or the like may be deposited to improve the adhesion and the barrier property of the embedded metal material. These are not shown because they do not directly relate to the present invention. An unnecessary portion of the metal material 5 deposited on the surface of the insulating film 3 is removed by using a dry etching technique, a chemical mechanical polishing technique, or the like, and the metal material 5 embedded in the surface of the insulating film 3 and the through hole 4 is removed. 5 is made almost the same height (FIG. 3- (d)).

After that, a trench pattern is formed by the resist 6 (FIG. 3E). At this time, no trench pattern is formed by the resist 6 on the through hole 4a. Using this resist 6 as a mask, etching is performed under dry etching conditions in which the etching selectivity of the insulating film 3 to the metal material 5 is about 1 to 0.5 to form a trench 7 in the insulating film 3 (FIG. 3 (f)). )). At this time, the metal material 5 has a depth of 1
Etching is performed up to about twice as thick.

Next, a metal material 8 such as copper, which is excellent in reliability and electrical characteristics as a wiring, is deposited in the through holes 4 and the trenches 7 formed in the insulating film 3 (FIG. 3).
(G)). Immediately before depositing the metal material 8, a titanium film, a titanium nitride film, or the like may be deposited in order to improve the adhesion and the barrier property of the embedded metal material. These are not shown because they do not directly relate to the present invention. At this time, since the metal material 5 is already buried in the through hole 4, the aspect ratio becomes small,
Even when the embedding characteristics of the metal material 8 film forming technique are low, the metal material 8 can be deposited without generating voids or seams.

Thereafter, the unnecessary metal material 8 is removed by using a chemical mechanical polishing method or a dry etching technique to form a second metal wiring made of the metal material 8 (FIG. 3H). . At this time, since there is no void or seam in the second metal wiring in the through hole 4, the high reliability and excellent electrical characteristics of the metal material 8 can be realized.

As described above, according to the present embodiment, the through-hole 4a in which the trench 7 is not formed is filled with the metal material 5 such as tungsten by using a film forming technique having excellent filling characteristics. In the through hole 4 in which the trench 7 is formed, the metal material 5 previously buried is buried with a metal material 8 excellent in reliability and electrical characteristics as a wiring, so that the same as in the first embodiment is used. The effect is obtained.

(Fourth Embodiment) Hereinafter, a fourth embodiment of the present invention will be described with reference to the drawings. FIGS. 4A to 4I are process cross-sectional views illustrating a method of forming a wiring according to a fourth embodiment of the present invention, and the same components as those in FIG. 1 are denoted by the same reference numerals.

First, the insulating substrate 1 may be provided with a transistor element or the like formed on the substrate, or a plurality of metal wirings may be formed on the insulating substrate 1. It is not shown because it is not directly related to the above. A first metal wiring 2 is formed on the insulating substrate 1, and an insulating film 3 is formed by a CVD method or the like.
Then, the surface of the insulating film 3 is flattened by a chemical mechanical polishing technique or a dry etching technique (FIG. 4).
(A)). The first metal wiring 2 and the insulating film 3
May be formed by embedding a metal material after forming a trench in an insulating film, removing unnecessary portions using a chemical mechanical polishing technique, and further depositing an insulating film. Note that the first metal wiring 2 and the insulating film 3
Each may have a laminated structure of two or more layers.

Next, through holes 4 are formed in the insulating film 3 according to the design (FIG. 4B). At this time, a part of the through hole 4 has a through hole 4a in which no trench is formed.

Then, a metal material 5 such as tungsten is deposited by using a blanket vapor phase epitaxy method or the like having excellent filling characteristics to completely fill the through holes 4 (FIG. 4).
(C)). At this time, a titanium film, a titanium nitride film, or the like may be deposited to improve the adhesion and the barrier property of the embedded metal material. These are not shown because they do not directly relate to the present invention. An unnecessary portion of the metal material 5 deposited on the surface of the insulating film 3 is removed by using a dry etching technique, a chemical mechanical polishing technique, or the like, and the metal material 5 embedded in the surface of the insulating film 3 and the through hole 4 is removed. 5 is made substantially the same height (FIG. 4D).

Thereafter, a trench pattern is formed by the resist 6 (FIG. 4E). At this time, no trench pattern is formed by the resist 6 on the through hole 4a. Using the resist 6 as a mask, etching is performed under dry etching conditions in which the etching selectivity of the insulating film 3 to the metal material 5 is 1 or more, thereby forming a trench 7 in the insulating film 3 (FIG. 4F). At this time, the metal material 5 protrudes from the bottom of the trench 7. In addition,
FIG. 4F shows a case where the metal material 5 is hardly etched and only the insulating film 3 is etched. When the etching selectivity of the insulating film 3 to the metal material 5 is 1, the bottom of the trench 7 and the surface of the metal material 5 have the same height.

Then, only the metal material 5 is selectively etched by a thickness of 1 to 2 times the depth of the trench 7 by using a wet etching technique or the like.
Is made to be lower than the bottom surface of the trench 7 (FIG. 4).
-(G)).

Next, a metal material 8 such as copper which is excellent in reliability and electrical characteristics as a wiring is deposited on the through holes 4 and the trenches 7 formed in the insulating film 3 (FIG. 4).
(H)). Immediately before depositing the metal material 8, a titanium film, a titanium nitride film, or the like may be deposited in order to improve the adhesion and the barrier property of the embedded metal material. These are not shown because they do not directly relate to the present invention. At this time, since the metal material 5 is already buried in the through holes 4 and 4a, the aspect ratio becomes small, and the metal material 8 is deposited without generating voids or seams even when the burying characteristics of the film forming technique of the metal material 8 are low. Can do things.

Thereafter, the unnecessary metal material 8 is removed by using a chemical mechanical polishing method or a dry etching technique to form a second metal wiring made of the metal material 8 (FIG. 4- (i)). . At this time, since there is no void or seam in the second metal wiring in the through holes 4 and 4a, the high reliability and excellent electrical characteristics of the metal material 8 can be realized.

As described above, also in the present embodiment, the through holes 4 and 4a are buried with the metal material 8 which is excellent in reliability and electric characteristics as wiring on the metal material 5 which has been buried earlier. The same effect as in the first embodiment can be obtained.

(Fifth Embodiment) Hereinafter, a fifth embodiment of the present invention will be described with reference to the drawings.
5A to 5H are cross-sectional views showing the steps of a method for forming a wiring according to a fifth embodiment of the present invention, and the same components as those in FIG. 1 are denoted by the same reference numerals.

First, as for the insulating substrate 1, transistors and the like may be formed on the insulating substrate 1, and a plurality of metal wirings may be formed on the insulating substrate 1. It is not shown because it is not directly related to the above. A first metal wiring 2 is formed on the insulating substrate 1, and an insulating film 3 is formed by a CVD method or the like.
Then, the surface of the insulating film 3 is flattened by a chemical mechanical polishing technique or a dry etching technique (FIG. 5).
(A)). The first metal wiring 2 and the insulating film 3
May be formed by embedding a metal material after forming a trench in an insulating film, removing unnecessary portions using a chemical mechanical polishing technique, and further depositing an insulating film. Note that the first metal wiring 2 and the insulating film 3
Each may have a laminated structure of two or more layers.

Next, through-holes 4 are formed in the insulating film 3 according to the design (FIG. 5B), and a trench pattern of a resist 6 is formed on the insulating film 3 (FIG. 5B).
(C)). At this time, a part of the through hole 4 has a through hole 4a in which a trench pattern by the resist 6 is not formed. Then, using the resist 6 as a mask, a trench 7 is formed in the insulating film 3 using a dry etching technique (FIG. 5D).

Then, a metal material 5 such as tungsten is deposited so as to completely fill the through hole 4 by using a blanket vapor phase growth method or the like having excellent filling characteristics (FIG. 5E). Thereby, the metal material 5 is also deposited in the trench 7. At this time, a titanium film, a titanium nitride film, or the like may be deposited to improve the adhesion and the barrier property of the embedded metal material. These are not shown because they do not directly relate to the present invention. Only the unnecessary portion of the deposited metal material 5 is removed by using a dry etching technique or a cleaning technique, and the height of the surface of the metal material 5 is set to be equal to or less than the bottom of the trench 7 (FIG. 5).
(F)). At this time, a part of the metal material 5 may remain on the side surface of the trench 7.

Next, a metal material 8 such as copper which is excellent in reliability and electrical characteristics as a wiring is deposited in the through holes 4 and the trenches 7 formed in the insulating film 3 (FIG. 5).
(G)). Immediately before depositing the metal material 8, a titanium film, a titanium nitride film, or the like may be deposited in order to improve the adhesion and the barrier property of the embedded metal material. These are not shown because they do not directly relate to the present invention. At this time, since the metal material 5 is already buried in the through holes 4 and 4a, the aspect ratio becomes small, and the metal material 8 is deposited without generating voids or seams even when the burying characteristics of the film forming technique of the metal material 8 are low. Can do things.

Subsequently, the unnecessary metal material 8 is removed by using a chemical mechanical polishing method or a dry etching technique to form a second metal wiring made of the metal material 8 (FIG. 5H). ). At this time, since there is no void or seam in the second metal wiring in the through holes 4 and 4a, the high reliability and excellent electrical characteristics of the metal material 8 can be realized.

As described above, according to the present embodiment as well, the through holes 4 and 4a are buried with the metal material 8 which is excellent in reliability and electrical characteristics as wiring on the metal material 5 previously buried. The same effect as in the first embodiment can be obtained.

In the present embodiment, the height of the surface of the metal material 5 is set to be lower than the bottom of the trench 7 in the step of FIG. It can be higher. However, when a large amount of the metal material 8 is buried in place of the metal material 5, the electrical characteristics such as low resistance are excellent.

In the first, third, fourth, and fifth embodiments, as a method of depositing the metal material 5, a selective CVD method can be used in addition to the blanket vapor deposition method. Further, aluminum may be used as the metal material 5 in addition to tungsten.

In the first to fifth embodiments,
As the metal material 8, a material having high reliability (improvement in electromigration resistance) and excellent electric characteristics (low resistance can be used) as wiring, such as gold and silver, can be used in addition to copper.

[0064]

As described above, according to the wiring forming method of the present invention, even if the through hole has a high aspect ratio, the first metal material embedded by using the film forming technique excellent in the embedding characteristic can be obtained. In order to embed a second metal material excellent in reliability and electric characteristics as wiring on the top, high reliability and excellent electric characteristics as wiring of the second metal material can be obtained without generating voids and seams. In addition, according to this method, it is not necessary to increase the area of the semiconductor chip.

[Brief description of the drawings]

FIG. 1 is a process cross-sectional view illustrating a method for forming a wiring according to a first embodiment of the present invention.

FIG. 2 is a process cross-sectional view illustrating a method for forming a wiring according to a second embodiment of the present invention.

FIG. 3 is a process cross-sectional view illustrating a method for forming a wiring according to a third embodiment of the present invention.

FIG. 4 is a process sectional view illustrating a method of forming a wiring according to a fourth embodiment of the present invention.

FIG. 5 is a process sectional view illustrating a method of forming a wiring according to a fifth embodiment of the present invention.

FIG. 6 is a process cross-sectional view showing a conventional wiring forming method.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 insulating substrate 2 insulating film 3 first metal wiring 4, 4 a through hole 5 metal material 6 resist 7 trench 8 metal material

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takashi Uehara 1-1, Sachimachi, Takatsuki-shi, Osaka Matsushita Electronics Co., Ltd. (72) Inventor Shuji Hirao 1-1-1, Sachimachi, Takatsuki-shi, Osaka Matsushita Electronics F-term in the company (reference) 4M104 BB02 BB14 BB18 BB30 DD07 DD08 DD43 DD46 DD65 DD75 FF13 FF17 FF18 FF21 FF22 HH01 HH13 HH14 5F033 HH11 HH18 HH33 JJ18 JJ19 JJ33 KK07 MM01 NN06 NN07 QQQNN PPQ

Claims (6)

[Claims] 1. A method for forming a wiring to be buried in a trench formed in a surface portion of an insulating film, the method comprising: forming a through hole in the insulating film; Embedding the through hole with one metal material, selectively removing only the first metal material, and removing the surface of the first metal material in the through hole from the bottom surface of the trench to be formed later Forming a trench in a surface portion of the insulating film by etching the insulating film using a resist in which a trench pattern is formed as a mask; Embedding the trench and the through hole with a second metal material having excellent characteristics; and forming an unnecessary portion of the second metal on the surface of the insulating film. Removing the metal material. 2. A method for forming a wiring to be embedded in a trench formed in a surface portion of an insulating film, comprising: forming a through hole in the insulating film; and forming a first metal material from a bottom of the through hole. Growing and embedding the first metal material so that the surface of the first metal material in the through-hole has a height equal to or lower than the vicinity of the bottom surface of the trench to be formed later; and forming a trench pattern. Forming the trench in the surface portion of the insulating film by etching the insulating film using the resist thus formed as a mask; and forming the trench and the trench with a second metal material having excellent reliability and electrical characteristics as wiring. Forming a wiring including a step of filling a through hole; and a step of removing an unnecessary portion of the second metal material deposited on a surface of the insulating film. Law. 3. The method according to claim 2, wherein the step of embedding the first metal material in the through hole and the step of forming the trench in the surface portion of the insulating film are reversed. . 4. A method for forming a wiring to be embedded in a trench formed in a surface portion of an insulating film, the method comprising: forming a through hole in the insulating film; Embedding the through hole with the first metal material, removing a portion of the first metal material deposited on the surface of the insulating film other than the through hole, removing the resist having the trench pattern formed thereon. The trench is formed in the surface portion of the insulating film and is directly connected to the trench by etching under a dry etching condition in which an etching selectivity of the insulating film to the first metal material is 1 to 0.5 as a mask. Setting the surface of the first metal material in the through hole to a height equal to or lower than the bottom of the trench; A step of filling the trench and the through hole with a second metal material having excellent electrical characteristics, and a step of removing an unnecessary portion of the second metal material deposited on a surface of the insulating film. Method of forming wiring. 5. A method for forming a wiring to be buried in a trench formed in a surface portion of an insulating film, the method comprising: forming a through hole in the insulating film; Embedding the through hole with the first metal material, removing a portion of the first metal material deposited on the surface of the insulating film other than the through hole, removing the resist having the trench pattern formed thereon. By etching the insulating film as a mask, the trench is formed in the surface portion of the insulating film, and at the same time, the surface of the first metal material formed in the through hole directly connected to the trench is removed. A step of raising the height of the bottom metal or higher;
A step of selectively etching by twice the thickness; a step of embedding the trench and the through hole with a second metal material excellent in reliability and electrical characteristics as a wiring; and depositing on the surface of the insulating film Removing the second unnecessary portion of the second metal material. 6. A method for forming a wiring to be buried in a trench formed in a surface portion of an insulating film, the method comprising: forming a through hole in the insulating film; and forming the insulating film using a resist having a trench pattern as a mask. Forming a trench in a surface portion of the insulating film by etching a film, filling the through hole with a first metal material using a film forming technique having excellent filling characteristics; Selectively removing only the metal material and setting the surface of the first metal material in the through hole to a height equal to or lower than the vicinity of the bottom of the trench to be formed later; Embedding the trench and the through hole with a second metal material having excellent characteristics; and forming an unnecessary portion of the second metal on the surface of the insulating film. Removing the metal material.