JP2002118169A - Semiconductor device and its fabricating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce line resistance, connection resistance and interconnection capacitance while enhancing electromigration resistance by preventing diffusion of copper even if an interconnection trench and a via hole made in an insulation film are directly filled with a metal principally comprising copper. SOLUTION: An SiN film 406, a BCB(benzocyclobutene) insulation film 407, an SiC film 408, a BCB insulation film 409, an SiC film 410 and an SiO2 film 411 are deposited on a Cu interconnection 405, a via hole 413 is opened by selective etching (d) and then an interconnection trench 414 is made (e). Subsequently, a Cu seed film 415 is deposited by MOCVD and a Cu film 416 is formed using the Cu seed film as an electrode (f). Excess Cu film is then removed by CMP, a Cu interconnection 417 connected with the Cu interconnection 405 through the via hole is formed, and then an SiC film 418 is formed (g).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor device and a method of manufacturing the same, and more particularly, to a semiconductor device having a wiring structure using an organic polymer insulating film as an insulating film and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, aluminum (Al) or an Al alloy has been widely used as a wiring material of an integrated circuit, and a silicon oxide film (SiO ₂ ) has been widely used as an insulating film between wirings and between wiring layers. However, with the progress of miniaturization of LSIs, copper (Cu) is used as a wiring material to reduce wiring resistance and to reduce capacitance between wirings in suppressing and reducing signal transmission delay in wiring. As the insulating film between the wirings and between the wiring layers, a silicon oxide film containing an organic substance having a low dielectric constant or a hole has been used. However, in a wiring containing Cu as a main component, diffusion of Cu in an insulating film such as silicon (Si) or SiO ₂ is faster than that of Al. It is necessary to form a barrier film for preventing diffusion around Cu in order to prevent the deterioration of the withstand voltage and the like and secure the reliability.

[Conventional Example 1] A structure and a manufacturing method for covering the lower surface and side surfaces of a Cu film with a conductor film serving as a Cu diffusion prevention (barrier) film will be described below. FIG. 7 is a cross-sectional view in the order of steps showing a method of manufacturing a wiring having a damascene structure generally used at present. A silicon oxide film 502, a silicon oxynitride film (SiON) film 503, and a silicon oxide film 504 are sequentially deposited on a silicon substrate 501.
4. A wiring groove is formed by selectively removing the silicon oxynitride film 503. Next, a conductive barrier film 505 and C
u film is deposited, and a chemical mechanical polishing (Chemical Me
Excessive Cu film and barrier film 505 are removed by chemical polishing (CMP) to form a Cu wiring 506 [FIG. 7A].

Next, an insulating barrier film 507 is formed on the silicon oxide film 504 in which the lower Cu wiring 506 is embedded.
A silicon oxide film 508, a silicon oxynitride film 509, and a silicon oxide film 510 are sequentially deposited (FIG. 7B), and a resist film 511 having an opening in a via hole formation region is formed thereon.
Is formed [FIG. 7 (c)]. Then, silicon oxide film 510, silicon oxynitride film 509, and silicon oxide film 50 are anisotropically etched using resist film 511 as a mask.
8 are sequentially etched, and then the resist film 511 is removed to form a via hole 512 (FIG. 7D).

Next, a resist film 513 having an opening in a wiring groove forming region is formed on the silicon oxide film 510 [FIG.
(E)], anisotropic etching is performed using the resist film 513 as a mask, and the silicon oxide film 51 corresponding to the wiring groove 514 is formed.
Remove 0. Then, after removing the resist film 513, the barrier film 507 at the bottom of the via hole 512 is removed by etching to form a via hole with Cu exposed at the bottom (FIG. 7F). Next, after a conductive barrier film 515 is formed on the entire surface, a Cu seed film is deposited by a sputtering method, and Cu is deposited by an electrolytic plating method using the Cu seed film as an electrode to form a Cu film 516 [FIG. 7 (g)]. Subsequently, the excess Cu film 516 and the excess barrier film 515 other than the wiring groove and the via hole are removed by the CMP method, and the Cu plug 517 in the via hole and the Cu connected to the lower Cu wiring 506 by the Cu plug 517 are removed.
The wiring 518 is formed. Then, an insulating barrier film 519 is formed thereon [FIG. 7 (h)].

[0006] By the above process, the lower surface, the side surface and the upper surface are all covered with the conductive or insulating barrier film.
Wiring 506, Cu plug 517 and Cu wiring 518
Is formed. By the way, among the barrier films used in these damascene processes, a conductive barrier film has a high ability to prevent diffusion of Cu, an insulating film serving as a base, and a Cu film.
It is required to have high adhesiveness to the wiring part and high thermal stability in the process, and titanium (Ti) and tantalum (T
a), a metal such as tungsten (W) and a nitride or silicide thereof or a laminate thereof. A semiconductor device having such a copper wiring having a damascene structure is known, for example, from Japanese Patent Application Laid-Open No. H11-186274.

[Conventional example 2] As described above, in order to form a Cu film having a damascene structure, a copper seed film is formed on a conductive barrier film by sputtering, and then this is used as an electrode to form a Cu film by electrolytic plating. However, if the via hole diameter is reduced to 0.1 μm, it becomes difficult to uniformly and continuously form a copper seed film by sputtering on the surface of the wiring groove or the via hole.

[0008]

Embedded image

As a method of improving the filling of the fine opening, Cu film formation by the MOCVD method has been studied. The reaction formula of the Cu film formation by the MOCVD method is represented by Formula 1.
(However, the coefficient is omitted). In this Cu growth method,
Hexafluoroacetylacetone dihydrate [hexa
Hexafluoroacetylacetonate copper [hexafluoro-acetylaceto] with an additive (Hhfac ・ tmvs) consisting of fluoro-acetylacetone dihydrate (Hhfacs)] and trimethylvinylsilane (tmvs)
nate copper; Cu (hfac)] and trimethylvinylsilane [tr
i-methylvinylsilane (tmvs)]
fac) tmvs is vaporized and introduced on a substrate heated to about 200 ° C. in a vacuum chamber by a nitrogen carrier gas.
Therefore, Cu is liberated by a thermochemical reaction of Cu (hfac) tmvs, and a Cu film is deposited on the substrate.

[Prior art 3] As described above, an organic substance is used as a low dielectric constant material used as an interlayer insulating film. Benzocyclobene is particularly preferable.
(utene: BCB) An organic polymer insulating film obtained by using a monomer as a starting material is considered to be promising. FIG. 8 is a diagram for explaining a reaction process of a thermal polymerization method generally used conventionally to form a BCB insulating film. In this thermal polymerization method, a benzocyclobutene-monomer film applied on a substrate is heated to about 300 ° C. to cause a ring-opening reaction of a four-membered carbon ring. A BCB insulating film is obtained by causing a thermal polymerization reaction.
The relative permittivity of the BCB film obtained by this thermal polymerization method is 2.
About 7 (the relative permittivity of the silicon oxide film is about 3.8)
The heat resistance is about 350 ° C.

Japanese Patent Application Laid-Open No. Hei 8-264962 discloses a technique for forming a Cu wiring on a BCB insulating film using a thermal polymerization method without using a conductive barrier film. That is, after coating a benzocyclobutene resin to be an interlayer insulating film on a substrate and curing it using a thermosetting method,
If necessary, a via hole is formed, a Cu film is directly formed on the BCB resin film by sputtering or a combination of sputtering and plating, and the Cu film is patterned to obtain a Cu wiring.

[0012]

As described in Conventional Example 1, when a Cu wiring is formed using a silicon oxide film as an interlayer insulating film, the lower surface and side surfaces of the Cu wiring or Cu plug are formed of a conductive barrier film. The area of the Cu film in the cross section of the wiring is reduced. In order to prevent the diffusion of Cu by the barrier metal, a certain thickness or more is required. Therefore, as the LSI design rule is reduced, both the wiring width and the via hole diameter are reduced to 0.1 μm or less. When miniaturized, the ratio of the barrier metal to the entire wiring increases. The resistivity of many barrier metals is about 200 μΩ · cm or more, and the resistivity of Cu is about 2 μΩ · cm.
cm or more, the resistance of the copper wiring increases. In addition, since the lower Cu wiring and the upper Cu plug are joined with a barrier film having a high resistance interposed therebetween, it is difficult to reduce the wiring resistance. Therefore, the wiring delay increases, and the effect of adopting low specific resistance Cu as the wiring material is hindered. Further, the wiring temperature rises due to the high resistance of the conductive barrier film, and electro-migration (electro-migration) is performed.
ionic) is reduced.

In the method of forming a Cu film by the MOCVD method described in the conventional example 2, the thermochemical reaction is performed when the underlying film is a conductive barrier film, for example, Ta or TaN, and the organic copper complex Cu (hfac ) Fluorine contained in tmvs reacts with Ta to form TaF on Cu / Ta or Cu / TaN interface.
Fluoride such as ₅ is formed. Fluoride with these conductive barrier films has a very high resistance and releases fluorine at 300 ° C. or higher, deteriorating the adhesion. This is because MOCV which is excellent in the embedding property in a fine opening is
This is a factor that hinders practical use of Cu film formation by the D method.

On the other hand, when a Cu film is formed on a BCB film which is a low dielectric constant film, its heat resistance becomes a problem. Since the copper film grown by filling the via hole has small crystal grains,
Annealing at about 400 ° C. is required for crystallization.
However, the BCB insulating film formed by the thermal polymerization method has a problem that the heat resistance is 350 ° C. and sufficient crystal growth cannot be performed. Further, in the BCB insulating film formed by the thermal polymerization method, when the Cu film is directly grown by the MOCVD method, a problem occurs in that the source gas reacts with the BCB and Cu diffuses into the BCB insulating film.

An object of the present invention is to solve the above-mentioned problems of the prior art, and an object of the present invention is to make it possible to form a copper film directly on a BCB film, which is a low dielectric constant film, by an MOCVD method so that wiring can be performed. It is an object of the present invention to reduce the resistance and the wiring capacitance, and to perform a heat treatment for crystallization of a Cu film.

[0016]

According to the present invention, there is provided, according to the present invention, copper as a main component in a wiring groove and a via hole formed in an organic polymer insulating film on a substrate on which a semiconductor element is formed. In a semiconductor device having a wiring and a connection plug formed by filling a metal wiring material, the organic polymer insulating film has an organic skeleton composed of divinylsiloxane benzocyclobutene or a derivative thereof produced by a plasma polymerization method. A semiconductor device is provided, wherein the semiconductor device is a polymer insulating film, and at least one layer of wiring and a connection plug connected thereto are formed in direct contact with the organic polymer film. In order to achieve the above object, according to the present invention, there is provided a semiconductor device in which a wiring made of a metal wiring material containing copper as a main component is embedded in an organic polymer insulating film on a substrate on which a semiconductor element is formed. The organic polymer insulating film is an organic polymer insulating film having divinylsiloxane benzocyclobutene or a derivative thereof as a skeleton prepared by a plasma polymerization method, and the side surface of the wiring is directly on the organic polymer film. A semiconductor device characterized by being formed in contact is provided. And
Preferably, an inorganic barrier insulating film is interposed between the organic polymer insulating films. Preferably, at least a bottom surface and an outer peripheral portion of the wiring and the connection plug are M
It is formed by the OCVD method.

In order to achieve the above object, according to the present invention, there is provided (1) a method using a vaporized benzocyclobutene monomer on a substrate on which a semiconductor element is formed and a lower wiring is formed thereon. Forming an organic polymer insulating film containing benzocyclobutene or a derivative thereof as a skeleton by a polymerization method; and (2) selectively removing the organic polymer insulating film by etching to form an organic polymer insulating film.
Forming a wiring groove and / or a via hole; and (3) depositing a metal wiring material containing copper as a main component so as to directly contact the organic polymer insulating film. A method for manufacturing a semiconductor device is provided. And, preferably, the benzocyclobutene is divinylsiloxane benzocyclobutene. Preferably, in the step (3), a metal wiring material containing copper as a main component is deposited by MOCVD using an organic copper complex as a starting material at least at the beginning of the step.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to use Cu as a wiring material without using a special barrier material, it is necessary to use an insulating film having a low Cu diffusion coefficient and a high adhesion to Cu. As such an organic insulating film, a BCB insulating film is known. In the present invention, as a method of forming the BCB insulating film, there is a plasma polymerization method in which divinylsiloxane benzocyclobutene monomer is vaporized, and the vaporized monomer is introduced into a plasma such as He to obtain a polymerized BCB film. Used. Note that a method of forming a BCB film using a plasma polymerization method is described in JP-A-2000-100803.
No. 6,086,045.

In the plasma polymerization method, for example, 0.1 g /
The evaporation temperature of the BCB monomer supplied in min.
° C, and sent to the reaction chamber with a He carrier gas at a flow rate of 500 sccm, a BCB monomer gas was supplied into the He plasma from a shower head to which RF power of 13.56 MHz was applied, and plasma polymerization BCB was applied to the substrate heated to 400 ° C. Growing an insulating film. The relative permittivity of the plasma polymerized BCB insulating film is 2.5 to 2.6.
It is smaller than the CB insulating film.

FIG. 5 shows a Fourier transform infrared spectrum of the plasma polymerized BCB insulating film and the BCB insulating film (thermopolymerized BCB insulating film) obtained by the thermal polymerization method. From this figure, it is confirmed that the structure of the plasma polymerized BCB insulating film does not completely match the structure of the thermally polymerized BCB insulating film, but its basic skeleton is maintained. The structure of the plasma polymerized BCB insulating film is presumed to have a structure containing a molecular chain pore in which a part of a benzene ring or a part of a 6-membered carbon ring is opened as shown in Chemical formula 2. I have. It has been confirmed that this plasma-polymerized BCB insulating film achieves heat resistance of 400 ° C. or higher, improves chemical stability, and has sufficient mechanical strength.

[0021]

Embedded image

FIG. 6 shows the low C of the plasma polymerized BCB insulating film.
5 shows a SIMS profile indicating u-diffusion. After forming a plasma-polymerized BCB insulating film to a thickness of 0.3 μm on a Si substrate, MOCVD using an organic copper complex Cu (hfac) tmvs
A Cu film was formed to a thickness of 0.2 μm by a method and heat-treated at 400 ° C. for 7 hours. SIMS measurement was performed on the obtained sample from the Si substrate side. SiO ₂ for comparison
The measurement results of a sample having a Cu film formed thereon are also shown. Although it is desired that the concentration of Cu in the insulating film be 10 ¹⁶ (atoms / cm ³ ) or less, in the case of SiO ₂ , the depth to change to this concentration is about 0.15 μm. On the other hand, in the case of the BCB insulating film formed by the plasma method, the thickness is set to 0.1.
It is about 03 μm. From this, the plasma polymerization BC
It can be seen that the B insulating film has a small amount of Cu incorporated into the insulating film when Cu is formed by MOCVD and has high resistance to thermal diffusion of Cu.

The remaining problem is the problem of the adhesion between copper and the organic film. If this problem can be solved, it is possible to realize an LSI using a copper wiring having a small capacitance between wirings and a small specific resistance. In order to evaluate the adhesion between Cu and the BCB insulating film, MOCVD was performed on the plasma polymerized BCB insulating film.
Film by Cu method, Sumitomo 3M Scotch tape (S
cotch Brand Tape No. 56) was used to evaluate the adhesion at the Cu / BCB interface. 1mm x 1
As a result of performing a tape test evaluation on 100 portions obtained by cutting out a mesh of mm, no peeling was confirmed in any of the samples, and it was confirmed that the Cu / BCB interface had strong adhesion.

The same results were obtained when a BCB insulating film was formed on Cu. Further, Cu was buried in the wiring groove pattern formed in the plasma-polymerized BCB insulating film by MOCVD,
After crystallization annealing at 0 ° C. for 30 minutes, polishing was performed by a CMP method to form a BCB / Cu wiring.
Wiring can be manufactured without using a barrier film.
It was confirmed that the adhesion at the u / BCB interface had sufficient strength to withstand the device fabrication process. Further, even if the wiring was annealed at 400 ° C. for 10 hours, no increase in leakage current between the wirings was observed, and a sufficient insulation resistance of about 10 ⁻⁹ A / cm ² was secured.

Copper film by MOCVD and plasma polymerization B
The reason why the adhesion to the CB insulating film has been improved is as follows.
First, there is no metal or nitride thereof which reacts with fluorine contained in the starting material Cu (hfac) tmvs, which is not present on the base. Furthermore, as is clear from the structure of Cu (hfac) tmvs, the Cu atom has a good affinity for carbon π electrons as seen in a vinyl group. This means that carbon atoms such as benzene rings and vinyl groups are unsaturated bonds,
MOCVD-
The Cu film means good adhesion, which was also confirmed by experiments.

As described above, plasma polymerization BCB
By combining the insulating film and the MOCVD-Cu film, high diffusion resistance to Cu that can eliminate the use of a barrier metal, embedding of a copper film in a fine pattern such as 0.1 μm or less, and lowering by eliminating the barrier film are achieved. It is possible to simultaneously solve the technical problems of increasing the resistance and reducing the capacitance between wirings.

[0027]

EXAMPLE Next, a plasma polymerized BCB insulating film and an MOCV
Regarding the embodiment of the present invention in combination with the D-Cu film,
This will be described in detail with reference to the drawings. [First Embodiment] FIG. 1 is a sectional view showing a method of manufacturing a wiring structure according to a first embodiment of the present invention in the order of steps. A plasma polymerized BCB insulating film 10 is formed on a semiconductor substrate on which an element is formed.
1 is deposited to a thickness of 0.6 μm. Here, 0.1 g / m
The evaporation temperature of the BCB monomer supplied at 200 ° C.
Then, a BCB monomer gas is supplied into the He plasma from a shower head to which 13.56 MHz RF power is applied by supplying a He carrier gas having a flow rate of 500 sccm to the reaction chamber, and plasma polymerization B is applied onto the substrate heated to 400 ° C.
A CB insulating film was grown.

On the upper surface, a SiC film 102 is formed to a thickness of 0.03 μm by a plasma CVD method using trimethylsilane as a raw material.
An m-thick film is formed. This SiC film is plasma-polymerized BCB
It functions as an etch stop film when forming a wiring groove in the insulating film. In addition, a 0.4 μm thick plasma polymerized BCB
The insulating film 103 and a film thickness of 0.
A 03 μm SiC film 104 is formed. These SiC films 102 and 104 can be changed to SiN films [FIG. 1 (a)].

A photoresist film having an opening in the shape of a wiring groove is formed by lithography, and the SiC film 104 is anisotropically etched with a fluorine-based etching gas, for example, CF ₄ / Ar / O ₂ gas using the photoresist film as a mask. The plasma polymerization BCB insulating film 103 is etched to form the wiring groove 107 while removing the photoresist film by switching the etching gas to N ₂ / O ₂ system. Where N ₂ / O ₂
Since the SiC films 102 and 104 are not etched with the system gas, the depth of the wiring groove is kept constant even if over-etching is performed until the photoresist is completely removed (FIG. 1B).

A Cu film 105 having a thickness of 0.6 μm is formed on the entire surface by MOCVD. Here, the MOCVD-Cu film was grown at a substrate temperature of 195 ° C. [FIG. 1 (c)]. After performing crystallization annealing of the Cu film at 400 ° C. for 20 minutes, the excess Cu other than the wiring groove is removed by CMP.
Is removed, and a Cu wiring 108 is formed. In this CMP, a polishing solution (slurry) in which hydrogen peroxide (H ₂ O ₂ ) was mixed with an abrasive mainly composed of silica (SiO ₂ ) was used. Here, in the CMP of Cu, it was confirmed that the adhesion between the BCB insulating film produced by plasma polymerization and MOCVD-Cu was sufficiently high, and no peeling or the like occurred (FIG. 1D). Next, the plasma polymerization BCB insulating film 10
6 is formed to a thickness of 0.4 μm, so that the Cu wiring side and upper surfaces are covered with a plasma polymerized BCB insulating film.
The wiring 108 is obtained [FIG. 1 (e)].

A pair of adjacent 10 mm-long wires was formed at an interval of 0.28 μm by the above process, and after annealing at 400 ° C. for 10 hours, a leak current between the wires was measured to be about 10 ⁻⁹ A / cm ^2. It was confirmed that sufficient insulation resistance was secured even after annealing. further,
As a result of comparing the wiring resistance with the case where a 0.03 μm thick Ta / TaN film as a conductive barrier film is used, the wiring resistivity is reduced by about 25% from 2.5 μΩ · cm to 2.0 μΩ · cm. Was also confirmed.

[Second Embodiment] In the first embodiment, a single-layer upper wiring is formed by embedding and polishing on a lower wiring portion, that is, a single damascene (Single D) method.
A dual damascene (Dual Dama) method in which an upper wiring groove and a via hole connected to a lower wiring are formed in an interlayer insulating film, and a wiring material is buried in both of them and then polished.
The present invention can be similarly applied to the scene) method. Hereinafter, the embodiment will be described in detail with reference to the drawings. FIG. 2 is a sectional view in the order of steps showing a method for manufacturing a wiring structure according to a second embodiment of the present invention. FIG. 2 shows FIG.
A method similar to the above is applied to a dual damascene method.

A Cu wiring 108 is formed by the single damascene process through the steps up to FIG.
(A)]. 0.6 μm of plasma polymerized BCB insulating film 201
The thickness of the SiC film 202 as an etch stop film is 0.0
3 μm thick film, and plasma-polymerized BCB insulating film 2
03 having a thickness of 0.3 μm and serving as an etching hard mask S
An iC film 204 is formed to a thickness of 0.03 μm [FIG.
(B)]. After forming a photoresist film (not shown) having an opening of a via hole pattern to be formed by lithography, a SiC film 204, a plasma-polymerized BCB insulating film 203, and an etch stop film are formed with CF ₄ / Ar / O ₂ gas. Is etched anisotropically, and the etching gas is changed to N ₂ / O ₂ gas to remove the photoresist, and the plasma polymerized BCB insulating film 20 is removed.
Then, a via hole 207 is formed in FIG. 1 (FIG. 2C).

Subsequently, after forming a photoresist film (not shown) having an opening having a pattern shape of a wiring groove to be formed by lithography, the SiC film 204 is anisotropically etched using N ₂ / O ₂ gas. A wiring groove 208 is formed in the plasma-polymerized BCB insulating film 203 while removing the upper photoresist (FIG. 2D). After the remaining photoresist is completely removed by organic cleaning, a Cu film 205 having a thickness of 0.8 μm is formed on the entire surface by MOCVD. At this time, since Cu of the underlying wiring exists at the bottom of the via hole, MOCVD-Cu grows using this Cu as a catalyst.
A u interface is formed [FIG. 2 (e)]. After crystallization annealing at 400 ° C. for 20 minutes, the wiring trench 2 is formed by CMP.
2 and the Cu wiring 209 and the Cu plug 210 are formed by removing the excess Cu other than the wirings 08 and the via holes 207 [FIG.
(F)].

Further, the plasma polymerized BCB insulating film 206
To form the Cu wiring 209 and the Cu plug 2
Cu around 10 covered with plasma polymerized BCB insulating film
A wiring structure is formed. However, in this case, the Cu wiring 209
There is a SiC film 202 serving as an etch stop film on the bottom surface of the substrate, but since the SiC film also has an excellent Cu diffusion barrier property, there is no fear of Cu diffusion. That is, this wiring structure forms a Cu wiring structure in which a high-resistance conductive barrier film such as a Ta / TaN film does not exist on the via hole connection portion, the wiring bottom surface, and the wiring side surface [FIG.
(G)].

Adjacent at an interval of 0.28 μm by the above steps
To form a 10 mm long wire pair,
Measurement of inter-wiring leakage current after annealing
10 ^-9A / cm^TwoAfter annealing for a long time.
It is confirmed that sufficient insulation resistance is secured even if
Was. Further, a conductive barrier film having a thickness of 0.03 μm
The result of comparing the wiring resistance with the case using Ta / TaN film
As a result, the wiring resistivity is from 2.5 μΩ · cm to 2.0 μΩ · c.
m to about 25%, and via-hole connection resistance is about 1Ω
From 0.1 to 0.1 Ω or less.

FIG. 3 shows an example in which this embodiment is applied to a substrate on which a semiconductor element is formed. An SiO ₂ film 301 is formed on a semiconductor substrate on which an element has been formed, and a contact hole serving as a junction with the semiconductor element is opened by lithography and anisotropic etching to connect the semiconductor element and the upper multilayer wiring. A W contact plug 302 is formed. Thereafter, a plasma-polymerized BCB insulating film 303 and a SiC film 304 are deposited, and a wiring groove serving as a joint with a semiconductor element is opened by lithography and anisotropic etching. A total of 0.04 of Ta / TaN laminated barrier film 305 is formed on the entire surface.
The film is formed to a thickness of μm. The barrier metal film is used only for the lowermost first wiring. This is, under the bottom wiring,
This is because the SiO ₂ film 301 exists.

Next, a Cu film 306 is formed by MOCVD.
Is formed to a thickness of 0.6 μm, Cu is embedded in the wiring groove, and C
Excess Cu film is removed by MP to form a first layer Cu wiring. After the second layer wiring, a laminated film of a plasma-polymerized BCB insulating film and a SiC film is deposited, then wiring grooves and via holes are formed, and Cu is directly deposited by MOCVD to form a CMP.
To form a Cu wiring and a Cu plug, thereby forming a multilayer wiring. In the embodiment of the present invention, it is important that the conductive barrier film does not exist on the side surface of the wiring groove portion and the side surface and the bottom surface of the via hole before the Cu film is formed. Need not be. For example, in the steps from FIG. 2C to FIG. 2D, a via hole may be formed after a wiring groove is formed first. Further, the hard mask and the inorganic film serving as the etch stop film can be omitted.

[Third Embodiment] FIG. 4 is a sectional view showing a method of manufacturing a wiring structure according to a third embodiment of the present invention in the order of steps. In the third embodiment, a barrier insulating film layer serving as a cover film is inserted on the upper surface of the Cu wiring to protect the upper surface of the Cu during workability such as etching or ashing. Further, a double hard mask was used for etching the organic polymer film, and the MOCVD method and the electrolytic plating method were combined to bury Cu. First, a plasma polymerized BCB insulating film 401 is formed on a semiconductor substrate on which an element is formed.
Deposit to a thickness of 6 μm. An SiC film 402 is formed on the upper surface by a plasma CVD method using trimethylsilane as a raw material.
Is formed to a thickness of 0.03 μm. This SiC film functions as an etch stop film for a wiring groove formed in the plasma polymerized BCB insulating film.

Furthermore, a 0.4 μm thick plasma polymerized BC
B insulating film 403 and SiC serving as an etching hard mask
The film 404 is formed to a thickness of 0.03 μm. Plasma polymerized BCB insulating film 4 by lithography and anisotropic etching
03, a wiring groove was formed, and Cu was added to the substrate by MOCVD.
A Cu wiring 405 is formed by forming a film to a thickness of 6 μm and removing excess Cu other than the wiring groove by CMP. Thereafter, an SiC film 406 having a thickness of 0.03 μm is formed as a barrier insulating film layer serving as a cover film on the upper surface of the Cu wiring [FIG. 4A].

The plasma-polymerized BCB insulating film 407 has a thickness of 0.6
The thickness of the SiC film 408, which is an etch stop film, is
A 0.3 μm thick plasma-polymerized BCB insulating film 409, and a lower hard mask SiC
A film 410 is formed to a thickness of 0.03 μm, and a silicon oxide film 411 is formed to a thickness of 0.06 μm as an upper hard mask [FIG. 4B]. Photolithography and CF ₄ /
A wiring groove pattern 412 is formed in the upper hard mask by anisotropic etching with Ar gas, and the photoresist is removed by oxygen plasma treatment [FIG. 4C].

A photoresist film (not shown) having a patterned opening of a via hole to be formed by photolithography is formed, and using this as a mask, CF ₄ / A
SiC film 41 as a lower hard mask with r / O ₂ gas
0, anisotropically etching the plasma polymerized BCB insulating film 409 and the SiC film 408 serving as an etch stop film, and then switching the etching gas to N ₂ / O ₂ to remove the photoresist and remove the plasma polymerized BCB insulating film 407.
Is anisotropically etched to form a via hole 413. At this time, etching at the bottom of the via hole
It stops at the SiC film 406 of the cover film located on the wiring 405 [FIG. 4D].

Further, using the silicon oxide film 411 as the upper hard mask in which the wiring groove pattern 412 is opened as a mask, the SiC film 410 as the lower hard mask is
The plasma polymerized BCB insulating film 409 is N-coated with F ₄ / Ar gas.
Wiring groove pattern 4 by etching with ₂ / O ₂ gas
14, and finally, the SiC cover film 406 existing at the bottom of the via hole is removed with CF ₄ / Ar gas [FIG.
(E)]. Next, after organic cleaning, a Cu seed film 415 having a thickness of 0.2 μm is formed by MOCVD. At this time, since the underlying wiring Cu exists at the bottom of the via hole,
Since MOCVD-Cu grows using this Cu as a catalyst, a clean Cu / Cu interface is formed at the bottom of the via hole. Since the via hole diameter is 0.3 μmφ here, the inside of the via hole 413 is filled with a MOCVD-Cu seed film. That is, by setting the MOCVD-Cu seed film thickness to be equal to or larger than the via hole radius, the inside of the via hole can be completely filled with the MOCVD-Cu film.
Thereafter, using the MOCVD-Cu seed film as an electrode, a plated Cu film 416 is deposited by an electrolytic plating method to fill remaining wiring grooves [FIG. 4 (f)].

After performing crystallization annealing at 400 ° C. for 20 minutes, excess Cu other than wiring grooves and via holes is removed by CMP to form Cu plugs and Cu wirings 417, and a cover film is formed on the upper surface of the Cu wirings. A 0.03 μm thick SiC film 418 is deposited as a barrier insulating film layer [FIG. 4 (g)]. Further, by repeating the steps from FIG. 4B to FIG. 4G, a multilayer wiring of three or more layers can be formed.

Also in the manufacturing method of this embodiment, it is possible to realize a copper wiring structure in which a conductive barrier film does not exist on the side surfaces and bottom surfaces of the wiring grooves and via holes. This MOCVD-
The method of using the Cu seed film and the electrolytic plating Cu film together is as follows:
The feature is that a fine via hole is completely buried with a MOCVD-Cu film to maintain a Cu / Cu interface with an underlying Cu wiring, and that a wiring portion can be formed with a low-production cost and high-throughput electrolytic plating Cu film. Even if a pair of adjacent 10 mm-long wires is formed at an interval of 0.28 μm by the above process and annealed at 400 ° C. for 10 hours, the leak current between the wires is about 10 ⁻⁹ A / cm ² , and sufficient insulation resistance is obtained. It was confirmed that it was secured. Furthermore, as a result of comparing the wiring resistance with the case of using a 0.03 μm thick Ta / TaN film as a conductive barrier film, the wiring resistivity was 2.5 μm.
It was also confirmed that the resistance was reduced by about 25% from Ω · cm to 2.0 μΩ · cm, and the via-hole connection resistance was reduced from about 1Ω to 0.1Ω or less. As a result, the electromigration resistance of the via hole was improved by 10 times or more.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and can be appropriately modified without departing from the gist of the present invention. Things. For example, in the embodiments, the insulating film using divinylsiloxane bisbenzocyclobutene has been described, but the present invention is not limited thereto, and a polymer insulating film having a derivative thereof as a skeleton may be used.
In the embodiment, the step of forming the Cu plug alone in the BCB film was not particularly described, but after the Cu plug embedded in the BCB insulating film was formed, the Cu plug was embedded in the BCB insulating film thereon. It is also possible to form a multilayer wiring by forming a Cu wiring and repeating this process. Further, if the embedding property does not matter when forming the Cu film in contact with the BCB film, the MOCVD
A film forming method other than the method, for example, a sputtering method can also be used.

[0047]

As described above, according to the present invention, since a Cu film is directly deposited on a BCB insulating film formed by a plasma polymerization method, a low dielectric constant film, a low wiring resistance and a low via hole connection resistance are obtained. Can be realized, wiring delay can be suppressed, and high resistance to electromigration can be maintained. Also, Cu
Since the film can be heat-treated at 400 ° C. or higher, it is possible to further reduce the resistance of the wiring. further,
Since the MOCVD-Cu film can be formed directly on the BCB insulating film, highly reliable embedding can be realized even in a fine opening of 0.1 μm or less.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a method of manufacturing a semiconductor device according to a first embodiment of the present invention in the order of steps.

FIG. 2 is a sectional view illustrating a method of manufacturing a semiconductor device according to a second embodiment of the present invention in the order of steps.

FIG. 3 is a sectional view of a semiconductor device formed by using the second embodiment of the present invention.

FIG. 4 is a sectional view illustrating a method of manufacturing a semiconductor device according to a third embodiment of the present invention in the order of steps.

FIG. 5 is an FTIR spectrum of a plasma polymerized BCB insulating film and a thermally polymerized BCB insulating film.

FIG. 6 is a SIMS profile of a Cu concentration in an insulating film.

FIG. 7 is a cross-sectional view in the order of steps showing a conventional method for manufacturing a semiconductor device.

FIG. 8 is a diagram showing a polymer chemical reaction process of a BCB insulating film by a thermal polymerization method.

[Explanation of symbols]

101, 103, 106 Plasma-polymerized BCB insulating film 102, 104 SiC film 105 Cu film 107 Wiring groove 108 Cu wiring 201, 203, 206 Plasma-polymerized BCB insulating film 202, 204 SiC film 205 Cu film 207 Via hole 208 Wiring groove 209 Cu wiring 210 Cu plug 301 SiO ₂ film 302 W contact plug 303 Plasma-polymerized BCB insulating film 304 SiC film 305 Ta / TaN laminated barrier film 306 Cu film 401, 403, 407, 409 Plasma-polymerized BCB
Insulating film 402, 404, 406, 408, 410, 418 S
iC film 405, 417 Cu wiring 411 silicon oxide film 412, 414 wiring groove pattern 413 via hole 415 Cu seed film 416 plated Cu film 501 silicon substrate 502, 504, 508, 510 silicon oxide film 503, 509 silicon oxynitride film 505, 515 Conductive barrier film 506, 518 Cu wiring 507, 519 Insulating barrier film 511, 513 Resist film 512 Via hole 514 Wiring groove 516 Cu film 517 Cu plug 518 Cu wiring

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Jun Kawahara 5-7-1 Shiba, Minato-ku, Tokyo Inside NEC Corporation (72) Yoshihiro Hayashi 5-7-1 Shiba, Minato-ku, Tokyo Japan F-term in the Electric Company (reference)

Claims (11)

[Claims] A wiring and a connection plug formed by filling a wiring groove and a via hole formed in an organic polymer insulating film on a substrate on which a semiconductor element is formed with a metal wiring material containing copper as a main component. In the semiconductor device, the organic polymer insulating film is an organic polymer insulating film having a skeleton of divinylsiloxane benzocyclobutene or a derivative thereof manufactured by a plasma polymerization method, and is connected to at least one layer of wiring. A semiconductor device, wherein a connection plug is formed in direct contact with the organic polymer film. 2. A semiconductor device in which a wiring made of a metal wiring material containing copper as a main component is buried in an organic polymer insulating film on a substrate on which a semiconductor element is formed, wherein the organic polymer insulating film has a plasma weight. An organic polymer insulating film having a skeleton of divinylsiloxane benzocyclobutene or a derivative thereof produced by a legal method, and a side surface of the wiring is formed in direct contact with the organic polymer film. Semiconductor device. 3. The semiconductor device according to claim 1, wherein an inorganic barrier insulating film is interposed between the organic polymer insulating films. 4. The semiconductor device according to claim 3, wherein said inorganic barrier insulating film is formed of one of SiN and SiC. 5. The wiring and the connection plug, or the wiring, at least a bottom surface and an outer peripheral portion are MO.
3. The semiconductor device according to claim 1, wherein the semiconductor device is formed by a CVD (metal organic chemical vapor deposition) method. 6. An organic compound containing benzocyclobutene or its derivative as a skeleton by plasma polymerization using a vaporized benzocyclobutene monomer on a substrate on which a semiconductor element is formed and a lower wiring is formed thereon. A step of forming a polymer insulating film; and (2) a step of selectively etching away the organic polymer insulating film to form a wiring groove and / or a via hole in the organic polymer insulating film. (3) a method of depositing a metal wiring material containing copper as a main component so as to directly contact the organic polymer insulating film. 7. The method according to claim 6, wherein the benzocyclobutene is divinylsiloxane benzocyclobutene. 8. In the step (3), a metal wiring material containing copper as a main component is deposited by MOCVD using an organic copper complex as a starting material at least at the beginning of the step. Item 7. A method for manufacturing a semiconductor device according to Item 6. 9. The first (3) step includes the first half of depositing a first metal wiring material mainly composed of copper by MOCVD using an organic copper complex as a starting material, and the first half. 7. The latter half of the step of depositing a second metal wiring material mainly composed of copper by an electrolytic plating method using the formed first metal wiring material as an electrode. Of manufacturing a semiconductor device. 10. The semiconductor according to claim 8, wherein the thickness of the metal wiring material formed by MOCVD is equal to or larger than the radius of the via hole formed in the organic polymer insulating film. Device manufacturing method. 11. The method according to claim 1, further comprising, after the step (1), prior to the step (2), a step of depositing an inorganic insulating film on the organic polymer insulating film. A method for manufacturing a semiconductor device according to claim 6.