JP2000114367A - Manufacture of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-resistance copper wiring without using a barrier metal by improving tight-contact property of Cu and BCB(benzocyclobutane). SOLUTION: Prior to a Cu film 25 is deposited on the surface of an inter- layer insulating film 21 comprising BCB, Ti is implanted in to the surface of the inter-layer insulating film 21 comprising the BCB using a Ti ion 23 extracted from an ionized plasma of Ti. As a result, an oxide film on the surface of BCB 21 is removed. Further, the Ti is implanted near the BCB surface and a reaction region 24 between BCB and Ti is formed, for enhanced tight contact between the BCB and Cu. The Cu film 25 is deposited through a CVD method and then is polished to provide a Cu wiring 26. Due to the effect of a part 24 where BCB was nitrided by Ti ion, no peeling of the Cu film 25 takes place during polishing or that of the Cu wiring 26 in a post process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a copper wiring in a semiconductor device.

[0002]

2. Description of the Related Art FIG. 5 is a sectional view of a conventional copper wiring. In FIG. 5, reference numeral 51 denotes an interlayer insulating film made of silicon oxide; 52, a barrier metal made of TaN;
u wiring. The wiring width is 200 nm and the wiring height is 300 nm.

A copper wiring 53 is surrounded on three sides by a barrier metal 52 made of TaN for the purpose of preventing diffusion of Cu into an interlayer insulating film 51 made of silicon oxide. 30nm TaN film thickness required to guarantee barrier properties against Cu
It is. TaN has a resistivity of about 250 μΩcm, which is at least two orders of magnitude greater than the resistivity of Cu of about 2 μΩcm, so that TaN hardly contributes to electric conduction. Therefore, the introduction of the barrier metal increases the resistance of the copper wiring by about 1.7 times. Therefore, it is desirable that the barrier metal film thickness be as thin as possible.

[0004]

However, in the conventional structure, when the barrier metal is thinned, diffusion of Cu into the interlayer insulating film cannot be prevented, or the barrier metal is broken due to insufficient strength.

On the other hand, Benzocyclobutene is used as an interlayer insulating film.
(Hereinafter referred to as BCB) is known (JP-A-8-264962). However, when BCB is used, diffusion of Cu can be prevented, but there is a problem that adhesion between Cu and BCB is poor.

An object of the present invention is to realize a low-resistance copper wiring without using a barrier metal by improving the adhesion between a material containing copper as a main component and a BCB.

[0007]

Means for Solving the Problems To solve this problem, a copper wiring of the present invention has a structure in which an interlayer film composed of BCB and a Cu or Cu alloy film are in contact at an interface with improved adhesion. ing. As a result, even if barrier metal is not used, Cu
Can be avoided, so that a low-resistance copper wiring can be obtained.

According to the present invention, the surface of an interlayer film composed of BCB is modified with N ₂ plasma before Cu is deposited, and the oxide film on the surface of the BCB is removed and the BCB near the surface is nitrided. This has the effect of increasing the adhesion between BCB and Cu.

According to the present invention, Ti ions or Ta ions are implanted into the surface of an interlayer film composed of BCB with ionized metal plasma before Cu is deposited. The reaction between BCB and Ti or Ta has the effect of increasing the adhesion between BCB and Cu.

The present invention is obtained by depositing Cu to which Ti or Ta is added, and has the effect of increasing the adhesion between BCB and Cu by reacting BCB near the surface with Ti or Ta.

According to the present invention, by heating in a hydrogen atmosphere, BCB in the vicinity of the surface reacts with Ti or Ta added to Cu, thereby increasing the adhesion between BCB and Cu and reducing the natural oxide film on the Cu surface. This has the effect of improving the film quality of a CVD-Cu film deposited continuously without exposure to the atmosphere.

[0012]

(Embodiment 1) Hereinafter, the first embodiment of the present invention will be described.
An embodiment will be described with reference to the drawings.

FIG. 1 shows a method of manufacturing a copper wiring according to a first embodiment of the present invention. In FIG.
In composed interlayer insulating film, 12 is an interlayer insulating film 11 formed on a surface width 200nm of depth 300nm groove pattern of 13 N ₂
14 is a portion where the BCB is nitrided by N ₂ ions 13, and 15 is a 600 nm thick Cu deposited by the CVD method.
Reference numeral 16 denotes a Cu wiring formed by polishing the Cu film 15.

In the method of forming a copper wiring according to the present embodiment, an interlayer insulating film 11 composed of BCB is deposited and
A concave portion is formed in the interlayer insulating film 11, and thereafter, the entire interlayer insulating film 11 including the concave portion is irradiated with N ₂ plasma to thereby form the interlayer insulating film 1.
1 (especially the surface of the concave portion). Thereafter, a step of depositing a film containing copper as a main component on the entire film 11 including the concave portion is formed.

A method of manufacturing a semiconductor device including the step of forming the copper wiring configured as described above will be described in detail.

First, before depositing Cu 15 on the surface of the interlayer insulating film 11 made of BCB, N ₂ ions 13 extracted from N ₂ plasma are used to deposit the interlayer insulating film 11 made of BCB.
Inject nitrogen into the surface. Energy of N ₂ ions 300e
V, the dose is 1 × 10 ¹⁵ cm ² . As a result, BCB1
The oxide film on one surface is removed. Furthermore, the BCB near the surface is nitrided, and the adhesion between the BCB and Cu can be increased. If the energy is less than 100 eV, the BCB surface oxide film cannot be completely removed. When the energy is 1 keV or more, the BCB surface is locally heated to 350 ° C. or more, and the BCB is decomposed. If the dose is 1 × 10 ¹⁴ cm ² or less, the BCB surface oxide film cannot be completely removed. When the dose is 1 × 10 ¹⁶ cm ² or more, the BCB surface is also locally heated to 350 ° C. or more, and the BCB is decomposed. Thereafter, a Cu film 15 is deposited by a CVD method,
The Cu wiring 16 is obtained by polishing the film 15. N ₂
Due to the effect of the portion 14 in which the BCB is nitrided by the ions, the peeling of the Cu film 15 during polishing and the peeling of the Cu wiring 16 in a later step do not occur.

As described above, according to this embodiment, the barrier metal is not used by providing the step of modifying the surface of the interlayer insulating film composed of BCB with N ₂ plasma before depositing Cu. However, it is possible to improve the adhesion between BCB and Cu and realize a copper wiring with low wiring resistance. In this embodiment,
Although the CVD method is used as the method for depositing the Cu film, the same effect can be obtained by using the electroless plating method.

(Embodiment 2) Hereinafter, a second embodiment of the present invention will be described with reference to the drawings.

FIG. 2 shows a method of forming a copper wiring according to a second embodiment. In FIG. 2, reference numeral 21 denotes an interlayer insulating film composed of BCB, and reference numeral 22 denotes a film formed on the surface of the interlayer insulating film 21. A groove pattern having a width of 200 nm and a depth of 300 nm, 23 is a Ti ion, 24 is a reaction region of BCB and Ti formed by the Ti ion 23, and 25 is a 600 nm thick film deposited by a CVD method.
Cu films 26 are Cu wirings formed by polishing the Cu film 25.

In this method for manufacturing a copper wiring, after depositing an interlayer insulating film composed of BCB, Ti is injected into the surface of the interlayer insulating film by ionized metal plasma, and Cu is deposited on the last implanted portion. And the step of performing.

The method of manufacturing the copper wiring will be described in more detail.
I will explain it. First, the interlayer insulating film 21 composed of BCB
Before depositing Cu25 on the surface of Ti, ionized plasma of Ti
Layer composed of BCB with Ti ions 23 extracted from
Ti is implanted into the surface of the interlayer insulating film 21. Energy of Ti ion
-300 eV, the dose is 1x10^Fifteencm^TwoIt is. The result
As a result, the oxide film on the surface of the BCB 21 is removed. More BCB surface
Ti is implanted in the vicinity to form a reaction region 24 between BCB and Ti.
By doing so, the adhesion between BCB and Cu can be increased. Ti
When the ON energy is 100 eV or less, the BCB surface oxide film
It cannot be completely removed. Ti ion energy of 1 keV or more
In this case, the BCB surface is locally heated to 350 ° C or more.
BBC decomposes. The dose of Ti ion is 1x10 ¹⁴cm^TwoLess than
In the case below, the BCB surface oxide film cannot be completely removed. Ti
1x10 on dose¹⁶cm^TwoIn the case above, it is deposited on the BCB surface
The thickness of the resulting Ti becomes about 20 nm, and the Cu wiring resistance increases.
Thereafter, a Cu film 25 is deposited by a CVD method, and
By polishing 5, a Cu wiring 26 is obtained. Ti Io
Due to the effect of the portion 24 where the BCB is nitrided by
The peeling of the u film 25 and the peeling of the Cu wiring 26 in a later process occur.
do not do.

As described above, according to the present embodiment, the step of modifying the surface of the interlayer insulating film composed of BCB with the ionized plasma of Ti before depositing Cu is provided.
Increases the adhesion between BCB and Cu without using barrier metal,
Copper wiring with low wiring resistance can be realized. In this example, the BCB surface was modified with Ti ions extracted from the ionized plasma, but the same effect can be obtained by modifying the BCB surface using Ta ions extracted from the ionized plasma of Ta. . Also, as a deposition method of Cu film
Although the CVD method is used, the same effect can be obtained by using the electroless plating method.

(Embodiment 3) Hereinafter, a third embodiment of the present invention will be described with reference to the drawings.

FIG. 3 shows a method of manufacturing a copper wiring according to this embodiment. In FIG. 3, reference numeral 31 denotes an interlayer insulating film made of BCB, and 32 denotes a 200 nm width formed on the surface of the interlayer insulating film 31. A groove pattern having a depth of 300 nm; 33 a Cu film having a thickness of 30 nm to which 5 atm% of Ti was added; 34 a Ti film included in the Cu film 33.
And BCB reaction area, 35 is the film thickness deposited by CVD method
Cu film of 600 nm, 36 is a C film formed by polishing the Cu film 35.
u wiring.

In this method of manufacturing a copper wiring, an interlayer insulating film composed of BCB is deposited, Cu to which Ti is added is deposited, and BCB is deposited.
It consists of a step of heat-treating the above-mentioned Cu to which Ti has been added at a temperature of 300 ° C to 500 ° C.

The method for manufacturing the copper wiring of the present invention configured as described above will be described in more detail.

First, a Cu film 3 containing 5 atm% of Ti is added to an interlayer insulating film 31 composed of BCB in which a groove pattern 32 is formed.
3 is deposited. Thereafter, the wafer is heated at 330 ° C. for 10 in a hydrogen atmosphere.
Anneal for minutes, and react BCB with Ti added to Cu. When the annealing temperature is lower than 300 ° C., the reaction between BCB and Ti does not proceed. When the annealing temperature is 500 ° C. or higher, BCB is decomposed. Therefore, annealing is preferably performed at 300 to 500 ° C. More preferably, it is 300 to 350 ° C.

The annealing in the hydrogen atmosphere is for reducing the natural oxide film on the surface of the Cu film 33. Reaction region 34 between Ti and BCB formed by this annealing process
, The adhesion between BCB and Cu is enhanced. Thereafter, a Cu film 35 is deposited by the CVD method, and the Cu film 35 is polished to obtain a Cu wiring 36. Due to the effect of the reaction region 34 between Ti and BCB, peeling of the Cu film 35 during polishing and peeling of the Cu wiring 36 in a later step do not occur.

As described above, according to the present embodiment, by using Cu to which Ti is added, the adhesion between BCB and Cu can be improved without using a barrier metal, and a copper wiring with low wiring resistance can be realized. Can be.

In the above invention, 33 is Cu to which Ti is added, but 33 may be Cu to which Ta is added. In this embodiment, the CVD method is used as the Cu film deposition method. However, the same effect can be obtained by using the electroless plating method.

(Embodiment 4) Hereinafter, a fourth embodiment of the present invention will be described with reference to the drawings.

FIG. 4 shows a method of manufacturing a copper wiring according to the fourth embodiment. In FIG. 4, reference numeral 41 denotes an interlayer insulating film made of BCB, and reference numeral 42 denotes a film formed on the surface of the interlayer insulating film 41. A groove pattern having a width of 200 nm and a depth of 300 nm, 43 is 5 atm% Ti
Is a 30 nm thick Cu film, 44 is a natural oxide film formed on the surface of the Cu film 43, 45 is Ti and BC contained in the Cu film 43.
B reaction area, 46 is a film thickness of 600 n deposited by the CVD method
The Cu film 47 of m is a Cu wiring formed by polishing the Cu film 46.

In the method of manufacturing a copper wiring, an interlayer film composed of BCB is deposited, Cu to which Ti or Ta is added is deposited,
Heat treatment of Ti-added Cu on BCB in a hydrogen atmosphere at a temperature of 300 to 350 ° C, and continuous CVD without exposure to air
And a step of depositing Cu by a method.

The method for manufacturing the copper wiring of the present invention having the above-described structure will be described in more detail.

First, a Cu film 4 containing 5 atm% of Ti is added to an interlayer insulating film 41 composed of BCB in which a groove pattern 42 is formed.
3 is deposited. Up to this point, the operation is the same as in FIG. When this film is left in the air, a natural oxide film 44 having a thickness of about 10 nm grows on the surface of the Cu film 43. Thereafter, the wafer was annealed at 330 ° C. for 10 minutes in a hydrogen atmosphere, and Ti added in BCB and Cu.
And the natural oxide film 44 is reduced. When the annealing temperature is lower than 300 ° C., the reaction between BCB and Ti does not proceed. When the annealing temperature is 350 ° C. or higher, BCB is decomposed. Due to the presence of the reaction region 45 between Ti and BCB formed by this annealing treatment, the adhesion between BCB and Cu is enhanced.
After the natural oxide film 44 is removed, the CV
By depositing the Cu film 46 by the D method, a highly pure Cu film having an oxygen content of 2 atm% or less can be formed. Since the Cu film 46 has a low oxygen concentration, the average crystal grain size is about
It is as large as 0.5 μm, and has good orientation in the (111) direction. Further Cu
The Cu wiring 47 is obtained by polishing the film 46. Ti
Of the Cu film 46 during polishing due to the effect of the reaction region 45 of
Of the Cu wiring 47 in the subsequent step does not occur.

As described above, according to the present embodiment, using Ti-added Cu, the Ti-added Cu is annealed in a hydrogen atmosphere at a temperature of 300 ° C. to 350 ° C. and continuously exposed without being exposed to the air. By depositing Cu by the CVD method, the adhesion between BCB and Cu can be increased without using a barrier metal, and copper wiring with low wiring resistance can be realized. Further, since the quality of the copper film is good, a long life for electromigration can be obtained.

In the above invention, 43 is Cu to which Ti is added. However, 43 may be Cu to which Ta is added.

[0038]

As described above, according to the present invention, the following effects can be obtained. (1) By providing a step of modifying the surface of the interlayer insulating film composed of BCB with N ₂ plasma before depositing Cu,
An object of the present invention is to provide an excellent method for manufacturing a copper wiring which can realize a low-resistance copper wiring without using a barrier metal. (2) BCB with ionized metal plasma before depositing Cu
By providing a step of implanting Ti ions or Ta ions on the surface of the interlayer insulating film composed of, it is possible to realize an excellent method of manufacturing a copper wiring which can realize a low-resistance copper wiring without using a barrier metal. . (3) By using Cu to which Ti or Ta is added, it is possible to realize an excellent copper wiring manufacturing method capable of realizing a low-resistance copper wiring without using a barrier metal. (4) By using Cu with Ti or Ta added, heating in a hydrogen atmosphere and depositing a CVD-Cu film continuously without exposure to the atmosphere, low-resistance copper wiring without barrier metal and oxygen-containing An excellent method for manufacturing a copper wiring capable of realizing a low-reliability copper wiring with a small amount can be realized.

[Brief description of the drawings]

FIG. 1 is a process sectional view showing a method for manufacturing a copper wiring according to a first embodiment of the present invention;

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

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

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

FIG. 5 is a sectional view of a conventional copper wiring.

[Explanation of symbols]

Reference Signs List 11 Interlayer insulating film composed of BCB 12 Groove pattern formed on surface of interlayer insulating film 11 13 N ₂ ion 14 Portion where BCB is nitrided by N ₂ ion 13 15 Cu film deposited by CVD method 16 Cu film Cu wiring formed by polishing 15 Interlayer insulating film composed of BCB 22 Groove pattern formed on surface of interlayer insulating film 21 Ti ion 24 BCB and Ti reaction region formed by Ti ion 23 25 CVD method Cu film deposited by polishing 26 Cu wiring formed by polishing the Cu film 25 31 Interlayer insulating film composed of BCB 32 Groove pattern formed on the surface of the interlayer insulating film 31 Cu film doped with 5 atm% of Ti 34 Reaction region of Ti and BCB contained in Cu film 33 35 Cu film deposited by CVD method 36 Cu wiring formed by polishing Cu film 35 41 Interlayer insulating film composed of BCB 42 Interlayer insulating film 4 1. Groove pattern formed on the surface of 1 43 Cu film doped with 5 atm% of Ti 44 Natural oxide film formed on Cu film 43 45 Reaction region between Ti and BCB contained in Cu film 43 46 CVD method Cu film deposited 47 Cu wiring formed by polishing the Cu film 46

Claims (4)

[Claims] A step of depositing an interlayer film composed of BCB, a step of modifying the surface of the interlayer film with N ₂ plasma,
Depositing a material containing copper as a main component on the modified surface. 2. A step of depositing an interlayer film composed of BCB, a step of implanting Ti or Ta into the surface of the interlayer film by ionized metal plasma, and a step of depositing a material containing copper as a main component on the implanted surface. And a step of depositing the semiconductor device. A step of depositing an interlayer film made of BCB, a step of depositing Cu with Ti or Ta added on the interlayer film, and a step of depositing Cu with Ti or Ta on the BCB.
A method for manufacturing a semiconductor device, comprising a step of performing a heat treatment at a temperature of 300 to 500 ° C. 4. A step of depositing an interlayer film composed of BCB, a step of depositing Cu with Ti or Ta added on the interlayer film, and a step of depositing Cu with Ti added on the BCB from 300 ° C. to 500 ° C. A method of manufacturing a semiconductor device, comprising: a step of performing a heat treatment in a hydrogen atmosphere at a temperature of, and a step of continuously depositing Cu by a CVD method without exposing to air.