Patent Application
20080083989
a) through 3(c) are cross-sectional views of relevant part of a semiconductor device according to the first embodiment of the present invention illustrating respective steps for fabricating the semiconductor device.
a) through 6(c) are cross-sectional views of relevant part of a semiconductor device according to the second embodiment of the present invention illustrating respective steps for fabricating the semiconductor device.
a) through 9(c) are cross-sectional views of relevant part of a semiconductor device according to the third embodiment of the present invention illustrating respective steps for fabricating the semiconductor device.
a) through 12(c) are cross-sectional views of relevant part of a semiconductor device according to the fourth embodiment of the present invention illustrating respective steps for fabricating the semiconductor device.
a) and 15(b) are cross-sectional views of relevant part of a semiconductor device according to the fifth embodiment of the present invention illustrating respective steps for fabricating the semiconductor device.
A semiconductor device according to a first embodiment of the present invention and a method for fabricating the semiconductor device will be described with reference to
As shown in
A via hole 10a is formed in the dielectric barrier film 5, the second insulation film 6 and the third insulation film 7 so as to reach the first copper wire 4, and a wiring groove 10b is formed in the fourth insulating film 8 so as to communicate to the via hole 10a. Thus, a recess portion 10c including the via hole 10a and the wiring groove 10b which is to be a dual damascene wiring groove is formed.
Moreover, as shown in
As shown in
Furthermore, a second copper wire 14 which is made of copper and is a wire of an upper layer is formed on the metal film 13 so as to fill the inside of the recess portion 10c. Note that the second copper wire 14 may be a wire, a via plug or a combination of a wire and a via plug. The second copper wire 14 may be formed of a copper alloy containing some other component (for example, a small amount of Si, Al, Mo, Si or the like) than pure copper and copper.
In this case, as the dielectric barrier film 5, a silicon nitride film, a silicon nitride carbide film, a silicon carbide oxide film, a silicon carbide film or a lamination film formed of a combination of these films is preferably used. The dielectric barrier film 5 has the function of preventing diffusion of copper contained in the first copper wire 4 into the second insulation film 6 and the fourth insulation film 8. As the third insulation film 7, the same material as that used for the dielectric barrier film 5 is preferably used. The third insulation film 7 is a film mainly functioning as an etching stopper for forming the wiring groove 10b. When a sufficient etching selection ratio can be obtained between the second insulation film 6 and the fourth insulation film 8 or when etching for forming the wiring groove 10b can be precisely formed, the third insulation film 7 is not necessarily provided.
Moreover, as each of the second insulation film 6 and the fourth insulation film 8, a silicon oxide film, a fluorine-doped silicon oxide film, a silicon oxide carbide film or an insulation film of an organic film is preferably used. Each of these films may be a film formed by chemical vapor deposition or a SOD (spin on dielectric) film formed by spin coating. Moreover, the same material may be used for the second insulation film 6 and the fourth insulation film 8.
As a metal forming the metal oxide film 11, a refractory metal is preferably used. Thus, in the process step of forming a wire of an upper layer after formation of the second copper wire 14, even when heat of about 400° C. is applied, the metal oxide film 11 does not degrade due to the heat treatment. Therefore, a highly reliable semiconductor device can be achieved.
When the metal oxide film 11 has a small thickness, the metal oxide film 11 does not necessarily have conductivity. However, it is preferable that the metal oxide film 11 has conductivity. Hereinafter, the metal oxide film 11 having conductivity will be specifically described.
As a metal forming the metal oxide film 11, titanium (Ti), zirconium (Zr), hafnium (Hf), tantalum (Ta), niobium (Nb), tungsten (W), vanadium (V), molybdenum (Mo), ruthenium (Ru), osmium (Os), rhodium (Rh), iridium (Ir), palladium (Pd) or platinum (Pt) is preferably used.
It is more preferable that as a metal forming the metal oxide film 11, vanadium (V), molybdenum (Mo), ruthenium (Ru), osmium (Os), rhodium (Ru), iridium (Ir), palladium (Pd) or platinum (Pt) is used. Thus, when the metal is oxidized, conductivity is not largely lost (or a resistivity is small), so that the second barrier metal film A1 having a low resistance can be formed.
As a metal forming the metal film 13, titanium (Ti), zirconium (Zr), hafnium (Hf), tantalum (Ta), niobium (Nb), tungsten (W), vanadium (V), molybdenum (Mo), ruthenium (Ru), osmium (Os), rhodium (Rh), iridium (Ir), palladium (Pd) or platinum is preferably used. For example, the resistivity of tantalum is 13 (μΩ·cm), the resistivity of ruthenium is 7.5 (μΩ·cm) and the resistivity of iridium is 6.5 (μΩ·cm).
It is more preferable that vanadium (V), molybdenum (Mo), ruthenium (Ru), osmium (Os), rhodium (Rh), iridium (Ir), palladium (Pd), platinum or the like is used. For example, the resistivity of ruthenium oxide film is 35 (μΩ·cm) and the resistivity of an iridium oxide film is 30 (μΩ·cm). With use of these metals, since the metals do not loose their conductivity (or have a low resistivity) when being oxidized, conductivity is not lost at surfaces of the metal oxide film 11 even when the surfaces of the metal oxide film 11 are oxidized in copper electroplating which will be later described. Accordingly, the second barrier metal film A1 having a low resistance can be formed.
When the second barrier metal film A1 is incorporated in an actual semiconductor device, the second barrier metal film A1 is preferably formed so as to have a thickness of about several to 30 nm in a 65 nm generation semiconductor device. In a 45 nm generation semiconductor device, it is expected that the thickness of the second barrier metal film A1 as a whole has to be about 15 nm or less at most. Note that this is also applied to second barrier metals A2 through A5 which will be described in the following embodiments.
As has been described, in the semiconductor device of the first embodiment of the present invention, the transition layer 12a having substantially the intermediate composition between the respective compositions of the metal film 13 and the metal oxide film 11 exists at the interface between the metal film 13 and the metal oxide film 11. Thus, adhesion between the metal film 13 and the metal oxide film 11 is remarkably improved, compared to the case where the transition layer 12a does not exist at the interface between the metal film 13 and the metal oxide film 13. Furthermore, since the transition layer 12a is formed of a single atomic layer, in addition to improvement of adhesion between the metal film 13 and the metal oxide film 11, a barrier metal film can be formed so as to have a small thickness by reducing the thickness of the transition layer 12a to an absolute minimum even when the barrier metal film has a lamination structure, so that a resistance of a wire can be reduced. Therefore, a highly reliable semiconductor device including a multi-layer wire with a low resistance and excellent adhesion can be achieved.
A metal forming the metal oxide film 11 and a metal forming the metal film 13 may be different elements. In such a case, in a layer structure of the metal film 13/the transition layer 12a/the metal oxide film 11/an insulation film (i.e., each of the second insulation film 6, the third insulation film 7 and the fourth insulation film 8), adhesion between the metal oxide film 11 and the insulation film (i.e., each of the second insulation film 6, the third insulation film 7 and the fourth insulation film 8) can be optimized according to a kind of the insulation film (i.e., each of the second insulation film 6, the third insulation film 7 and the fourth insulation film 8) without degrading adhesion between the metal film 13 and the metal oxide film 11. Therefore, a highly reliable semiconductor device including a multi-layer wire with a low resistance and excellent adhesion can be achieved.
Moreover, a metal forming a metal oxide film and a metal forming a metal film may be the same element. In such a case, adhesion at an interface between the metal film 13 and the transition layer 12a and adhesion at an interface between the transition layer 12a and the metal oxide film 11 can be improved in a layer structure of the metal film 13/the transition layer 12a/the metal oxide film 11. Therefore, a highly reliable semiconductor device including a multi-layer wire with a low resistance and excellent adhesion can be achieved.
Next, a method for fabricating a semiconductor device according to the first embodiment of the present invention will be described with reference to
a) through 3(c) are cross-sectional views of relevant part of a semiconductor device according to the first embodiment of the present invention illustrating respective steps for fabricating the semiconductor device.
First, as shown in
The recess portion 10c including the via hole 10a and the wiring groove 10b is preferably formed by a dual damascene formation method disclosed, for example, in Japanese Laid-Open Publication No. 2002-75994 or the like using known lithography, etching, ashing, and cleaning.
Next, as shown in
Next, as shown in
Hereinafter, a method for forming the second barrier metal film A1, for example, in the case where a metal forming the metal film 13 is ruthenium (Ru) and the metal oxide film 11 is ruthenium oxide (RuO2) will be described in detail.
A known atomic layer deposition technique (Journal of The Electrochemical Society, 151, G109-G112 (2004)) is used to form the metal oxide film 11, the transition layer 12a and the metal film 13 which together form the second barrier metal film A1. Conditions for film formation in this case are as follows. For example, Ru(EtCp)2 (bis(ethylcyclopentadienyl)ruthenium) gas is used as a source gas of ruthenium (Ru). Where the source gas is heated to 80° C., the source gas is diluted with Ar gas of 50 mL/min (standard temperature and pressure, dry) for use. The temperature of a substrate is 250° C. and the degree of vacuum is 4.66×102 Pa. As oxygen gas, a gas obtained by mixing Ar gas of 100 mL/min (standard temperature and pressure, dry) to oxygen gas of 70 mL/min (standard temperature and pressure, dry) is used. An arbitrary composition in the range from metal ruthenium to ruthenium oxide can be obtained by changing a pulse time used for supplying Ru(EtCp)2 gas. The range of the pulse time is from 1 second to 10 seconds. After Ru(EtCp)2 gas is supplied and then purged for a certain period of time, oxygen gas is supplied. When the supply of oxygen gas is stopped, purge is performed for a certain period of time. Thus, a film of a single atomic layer of Ru and O can be grown. This series of steps is assumed to be a cycle. When metal ruthenium is grown, oxygen gas is not supplied.
For example, with a pulse time of 2 seconds for supplying Ru(EtCp)2 gas, a ruthenium oxide (RuO2) film, i.e., the metal oxide film 11 is deposited on the second insulation film 6, the third insulation film 7 and the fourth insulation film 8 to a thickness of 5 nm and then, with a pulse time of 5 seconds for supplying Ru(EtCp)2, a single atomic layer of the transition layer 12a having an intermediate composition between respective compositions of ruthenium oxide is formed. Next, a ruthenium (Ru) film, i.e., the metal film 13 is deposited to a thickness of 5 nm with a pulse time of 10 seconds for supplying Ru(EtCp)2. In the second barrier metal film A1 formed in the above-described manner, a distribution of atomic concentration in the film thickness direction is as shown in
Next, a copper film is formed over the metal film 13 as well as inside the recess portion 10c by copper electroplating so as to fill the recess portion 10c and then parts of the copper film, the metal film 13, the transition layer 12a and the metal oxide film 11 located on the fourth insulation film 8, except for parts thereof located inside the recess portion 10c, are removed by CMP, thereby forming a second copper wire 14 and a via plug which is part of the second copper wire 14. Thus, a semiconductor device having the structure of
As has been described, according to the method for fabricating a semiconductor device according to the first embodiment of the present invention, the transition layer 12a of a single atomic layer having substantially the intermediate composition between the respective compositions of the metal film 13 and the metal oxide film 11 can be formed at the interface between the metal film 13 and the metal oxide film 11 in a simple manner. Moreover, the same effects as those of the above-described semiconductor device can be achieved. Specifically, the transition layer 12a having substantially the intermediate composition between the respective compositions of the metal film 13 and the metal oxide film 11 is formed at the interface between the metal film 13 and the metal oxide film 11, so that adhesion between the metal film 13 and the metal oxide film 11 can be remarkably improved, compared to the case where the transition layer 12a does not exist at the interface between the metal film 13 and the metal oxide film 11. Furthermore, since the transition layer 12a is formed of a single atomic layer, in addition to improvement of adhesion between the metal film 13 and the metal oxide film 11, a barrier metal film can be formed so as to have a small thickness by reducing the thickness of the transition layer 12a to an absolute minimum even when the barrier metal film has a lamination structure, so that a resistance of a wire can be reduced. Therefore, a highly reliable semiconductor device including a multi-layer wire with a low resistance and excellent adhesion can be fabricated.
When the metal oxide film 11, the transition layer 12a and the metal film 13 are formed by atomic layer deposition using different metals for a metal forming the metal oxide film 11 and a metal forming the metal film 13, respectively, the metal oxide film 11, the transition layer 12a and the metal film 13 can be continuously formed, for example, only by changing film formation conditions or a source gas. Accordingly, a second barrier metal film having excellent adhesion can be formed.
When the metal oxide film 11, the transition layer 12a and the metal film 13 are formed by atomic layer deposition using the same element for the metal forming the metal oxide film 11 and the metal forming the metal film 13, the metal oxide film 11, the transition layer 12a and the metal film 13 can be continuously formed, for example, only by changing film formation conditions.
Hereinafter, a semiconductor device according to a second embodiment of the present invention and a method for fabricating the semiconductor device will be described with reference to
As shown in
As has been described, in the semiconductor device according to the second embodiment of the present invention, the transition layer 12b having substantially the intermediate composition between the respective compositions of the metal film 13 and the metal oxide film 11 exists at the interface between the metal film 13 and the metal oxide film 11, so that adhesion between the metal film 13 and the metal oxide film 11 is dramatically improved, compared to the case where the transition layer 12b does not exist at the interface between the metal film 13 and the metal oxide film 11. Accordingly, a barrier metal film having a small thickness and excellent adhesion can be formed. Furthermore, as another effect, the transition layer 12b is formed of a plurality of atomic layers, so that adhesion is further improved, compared to the case where the transition layer 12b provided between the metal film 13 and the metal oxide film 11 is formed of a single atomic layer. Moreover, the composition of the transition layer 12b varies stepwise, so that adhesion is further improved. Therefore, a highly reliable semiconductor device including a multi-layer wire with a low resistance and excellent adhesion can be achieved.
A metal forming the metal oxide film 11 and a metal forming the metal film 13 may be different elements. In such a case, in a layer structure of the metal film 13/the transition layer 12b/the metal oxide film 11/an insulation film (i.e., each of the second insulation film 6, the third insulation film 7 and the fourth insulation film 8), adhesion between the metal oxide film 11 and the insulation film (i.e., each of the second insulation film 6, the third insulation film 7 and the fourth insulation film 8) can be optimized according to a kind of the insulation film (i.e., each of the second insulation film 6, the third insulation film 7 and the fourth insulation film 8) without degrading adhesion between the metal film 13 and the metal oxide film 11. Therefore, a highly reliable semiconductor device including a multi-layer wire with a low cost and excellent adhesion can be achieved.
Moreover, a metal forming a metal oxide film and a metal forming a metal film may be the same element. In such a case, adhesion at an interface between the metal film 13 and the transition layer 12b and adhesion at an interface between the transition layer 12b and the metal oxide film 11 can be improved in a layer structure of the metal film 13/the transition layer 12b/the metal oxide film 11. Therefore, a highly reliable semiconductor device including a multi-layer wire with a low resistance and excellent adhesion can be achieved.
Next, a method for fabricating a semiconductor device according to the second embodiment of the present invention will be described with reference to
First, in the same manner as shown in
Next, as shown in
Next, as shown in
Hereinafter, a method for forming the second barrier metal A2, for example, in the case where a metal forming the metal film 13 is ruthenium (Ru) and the metal oxide film 11 is ruthenium oxide (RuO2) will be described in detail.
A known atomic layer deposition technique (Journal of The Electrochemical Society, 151, G109-G112 (2004)) is used to form the metal oxide film 11, the transition layer 12b and the metal film 13 which together form the second barrier metal film A2. Conditions for film formation in this case are as follows. For example, Ru(EtCp)2 (bis(ethylcyclopentadienyl)ruthenium) gas is used as a source gas of ruthenium (Ru). Where the source gas is heated to 80° C., the source gas is diluted with Ar gas of 50 mL/min (standard temperature and pressure, dry) for use. The temperature of a substrate is 250° C. and the degree of vacuum is 4.66×102 Pa. As oxygen gas, a gas obtained by mixing Ar gas of 100 mL/min (standard temperature and pressure, dry) to oxygen gas of 70 mL/min (standard temperature and pressure, dry) is used. An arbitrary composition in the range from metal ruthenium to ruthenium oxide can be obtained by changing a pulse time used for supplying Ru(EtCp)2 gas. The range of the pulse time is from 1 second to 10 seconds. After Ru(EtCp)2 gas is supplied and then purged for a certain period of time, oxygen gas is supplied. When the supply of oxygen gas is stopped, purge is performed for a certain period of time. Thus, a film of a single atomic layer of Ru and O can be grown. This series of steps is assumed to be a cycle. When metal ruthenium is grown, oxygen gas is not supplied.
For example, with a pulse time of 2 seconds for supplying Ru(EtCp)2 gas, a ruthenium oxide (RuO2) film, i.e., the metal oxide film 11 is deposited on the second insulation film 6, the third insulation film 7 and the fourth insulation film 8 to a thickness of 5 nm and then, with the pulse time for supplying Ru(EtCp)2 changed stepwise to 3 seconds, 5 seconds and then 7 seconds, the transition layer 12b having an intermediate composition between respective compositions of ruthenium oxide and ruthenium is formed, thereby obtaining a structure of three atomic layers. Next, a ruthenium (Ru) film, i.e., the metal film 13 is deposited to a thickness of 5 nm with a pulse time of 10 seconds for supplying Ru(EtCp)2. In the second barrier metal film A2 formed in the above-described manner, a distribution of atomic concentration in the film thickness direction is as shown in
Next, a copper film is formed over the metal film 13 as well as inside the recess portion 10c by copper electroplating so as to fill the recess portion 10c and then parts of the copper film, the metal film 13, the transition layer 12b and the metal oxide film 11 located on the fourth insulation film 8, except for parts thereof located inside the recess portion 10c, are removed by CMP, thereby forming a second copper wire 14 and a via plug which is part of the second copper wire 14. Thus, a semiconductor device having the structure of
As described above, according to the method for fabricating a semiconductor device according to the second embodiment of the present invention, the transition layer 12b having substantially the intermediate composition between the respective composition of the metal film 13 and the metal oxide film 11 and including a plurality of atomic layers can be formed in a simple manner at the interface between the metal film 13 and the metal oxide film 11. Moreover, the same effects as those of the semiconductor device of the second embodiment can be achieved. Specifically, the transition layer 12b having substantially the intermediate composition between the respective compositions of the metal film 13 and the metal oxide film 11 is formed at the interface between the metal film 13 and the metal oxide film 11, so that adhesion between the metal film 13 and the metal oxide film 11 can be remarkably improved, compared to the case where the transition layer 12b does not exist at the interface between the metal film 13 and the metal oxide film 11. Accordingly, a barrier metal film having a small thickness and excellent adhesion can be formed. Furthermore, as another effect, since the transition layer 12b is formed of a plurality of atomic layers, adhesion between the metal film 13 and the metal oxide film 11 is further improved, compared to the case where a transition layer provided between the metal film 13 and the metal oxide film 11 is formed of a single atomic layer. Moreover, adhesion can be further improved by changing the composition of the transition layer 12b stepwise. Therefore, a highly reliable semiconductor device including a multi-layer wire with a low resistance and excellent adhesion can be fabricated.
When the metal oxide film 11, the transition layer 12b and the metal film 13 are formed by atomic layer deposition using different metals for a metal forming the metal oxide film 11 and a metal forming the metal film 13, respectively, the metal oxide film 11, the transition layer 12b and the metal film 13 can be continuously formed, for example, only by changing film formation conditions or a source gas. Thus, a second barrier metal film having excellent adhesion can be formed.
When the metal oxide film 11, the transition layer 12b and the metal film 13 are formed by atomic layer deposition using the same element for the metal forming the metal oxide film 11 and the metal forming the metal film 13, the metal oxide film 11, the transition layer 12b and the metal film 13 can be continuously formed, for example, only by changing film formation conditions.
Hereinafter, a semiconductor device according to a third embodiment of the present invention and a method for fabricating the semiconductor device will be described with reference to
As shown in
A refractory metal is preferably used as a metal for forming the metal oxide which determines the composition of the transition layer 12c. Thus, in the process step of forming a wire of an upper layer after formation of a second copper wire 14, even when heat of about 400° C. is applied, the transition layer 12c does not degrade due to the heat treatment. Therefore, a highly reliable semiconductor device can be achieved.
Moreover, when the transition layer 12c has a small thickness, the transition layer 12c does not necessarily have conductivity. However, the transition layer 12c preferably has conductivity. Hereinafter, the metal oxide which determines the composition of the transition layer 12c having conductivity will be specifically described.
As a metal forming the metal oxide which determines the composition of the transition layer 12c, titanium (Ti), zirconium (Zr), hafnium (Hf), tantalum (Ta), niobium (Nb), tungsten (W), vanadium (V), molybdenum (Mo), ruthenium (Ru), osmium (Os), rhodium (Rh), iridium (Ir), palladium (Pd) or platinum (Pt) is preferably used.
It is more preferable that as the metal forming the metal oxide which determines the composition of the transition layer 12c, vanadium (V), molybdenum (Mo), ruthenium (Ru), osmium (Os), rhodium (Rh), iridium (Ir), palladium (Pd), platinum (Pt) or the like is used. Thus, when the metal is oxidized, conductivity is not largely lost (or a resistivity is small), so that the second barrier metal film A3 having a low resistance can be formed.
As described above, in the semiconductor device according to the third embodiment of the present invention, the transition layer 12c having substantially the intermediate composition between the respective compositions of the metal film 13 and the metal oxide exists at the interface between the metal film 13 and an insulation film (i.e., each of the second insulation film 6, the third insulation film 7 and the fourth insulation film 8), so that adhesion between the metal film 13 and the insulation film (i.e., each of the second insulation film 6, the third insulation film 7 and the fourth insulation film 8) is remarkably improved, compared to the case where the transition layer 12c does not exist at the interface between the metal film 13 and the insulation film (i.e., each of the second insulation film 6, the third insulation film 7 and the fourth insulation film 8). Furthermore, since the transition layer 12c is formed of a single atomic layer, in addition to improvement of adhesion between the metal film 13 and the insulation film (i.e., each of the second insulation film 6, the third insulation film 7 and the fourth insulation film 8), a barrier metal film can be formed so as to have a small thickness by reducing the thickness of the transition layer 12c to an absolute minimum even when the barrier metal film has a lamination structure, so that a resistance of a wire can be reduced. Therefore, a highly reliable semiconductor device including a multi-layer wire with a low resistance and excellent adhesion can be achieved.
A metal forming the metal oxide which determines the composition of the transition layer 12c and a metal forming the metal film 13 may be different elements. In such a case, in a layer structure of the metal film 13/the transition layer 12c/an insulation film (i.e., each of the second insulation film 6, the third insulation film 7 and the fourth insulation film 8), adhesion between the transition layer 12c and the insulation film (i.e., each of the second insulation film 6, the third insulation film 7 and the fourth insulation film 8) can be optimized according to a kind of the insulation film (i.e., each of the second insulation film 6, the third insulation film 7 and the fourth insulation film 8) without degrading adhesion between the metal film 13 and the transition layer 12c. Therefore, a highly reliable semiconductor device including a multi-layer wire with a low resistance and excellent adhesion can be achieved.
Moreover, a metal forming the metal oxide which determines the composition of the transition layer 12c and a metal forming the metal film 13 may be the same element. In such a case, adhesion at an interface between the metal film 13 and the transition layer 12c can be improved in a layer structure of the metal film 13/the transition layer 12c. Therefore, a highly reliable semiconductor device including a multi-layer wire with a low resistance and excellent adhesion can be achieved.
Next, a method for fabricating a semiconductor device according to the third embodiment of the present invention will be described with reference to
a) through 9(c) are cross-sectional views of relevant part of a semiconductor device according to the third embodiment of the present invention illustrating respective steps for fabricating the semiconductor device.
First, in the same manner as shown in
Next, as shown in
Next, as shown in
Hereinafter, a method for forming the second barrier metal A3, for example, in the case where a metal forming the metal film 13 is ruthenium (Ru) and the metal oxide which determines the composition of the transition layer 12c is ruthenium oxide (RuO2) will be described in detail.
A known atomic layer deposition technique (Journal of The Electrochemical Society, 151, G109-G112 (2004)) is used to form the transition layer 12c and the metal film 13 which together form the second barrier metal film A3. Conditions for film formation in this case are as follows. For example, Ru(EtCp)2 (bis(ethylcyclopentadienyl)ruthenium) gas is used as a source gas of ruthenium (Ru). Where the source gas is heated to 80° C., the source gas is diluted with Ar gas of 50 mL/min (standard temperature and pressure, dry) for use. The temperature of a substrate is 250° C. and the degree of vacuum is 4.66×102 Pa. As oxygen gas, a gas obtained by mixing Ar gas of 100 mL/min (standard temperature and pressure, dry) to oxygen gas of 70 mL/min (standard temperature and pressure, dry) is used. An arbitrary composition in the range from metal ruthenium to ruthenium oxide can be obtained by changing a pulse time used for supplying Ru(EtCp)2 gas. The range of the pulse time is from 1 second to 10 seconds. After Ru(EtCp)2 gas is supplied and then purged for a certain period of time, oxygen gas is supplied. When the supply of oxygen gas is stopped, purge is performed for a certain period of time. Thus, a film of a single atomic layer of Ru and O can be grown. This series of steps is assumed to be a cycle. When metal ruthenium is grown, oxygen gas is not supplied.
For example, a single atomic layer of the transition layer 12c having an intermediate composition between respective compositions of ruthenium oxide and ruthenium is formed with a pulse time of 5 seconds for supplying Ru(EtCp)2. Next, with a pulse time of 10 seconds for supplying Ru(EtCp)2, a ruthenium (Ru) film, i.e., the metal film 13 is deposited to a thickness of 5 nm. In the second barrier metal film A3 formed in the above-described manner, a distribution of atomic concentration in the film thickness direction is as shown in
Next, a copper film is formed over the metal film 13 as well as inside the recess portion 10c by copper electroplating so as to fill the recess portion 10c and then parts of the copper film, the metal film 13 and the transition layer 12c located on the fourth insulation film 8, except for parts thereof located inside the recess portion 10c, are removed by CMP, thereby forming a second copper wire 14 and a via plug which is part of the second copper wire 14. Thus, a semiconductor device having the structure of
As has been described, according to the method for fabricating a semiconductor device according to the third embodiment of the present invention, the transition layer 12c of a single atomic layer having substantially the intermediate composition between the respective compositions of the metal film 13 and the metal oxide can be formed at an interface between the metal film 13 and the insulation film (i.e., each of the second insulation film 6, the third insulation film 7 and the fourth insulation film 8) in a simple manner. Moreover, the same effects as those of the above-described semiconductor device can be achieved. Specifically, the transition layer 12c having substantially the intermediate composition between the respective compositions of the metal film 13 and the metal oxide is formed at the interface between the metal film 13 and the insulation film (i.e., each of the second insulation film 6, the third insulation film 7 and the fourth insulation film 8), so that adhesion between the metal film 13 and the insulation film (i.e., each of the second insulation film 6, the third insulation film 7 and the fourth insulation film 8) can be remarkably improved, compared to the case where the transition layer 12c does not exist at the interface between the metal film 13 and the insulation film (i.e., each of the second insulation film 6, the third insulation film 7 and the fourth insulation film 8). Furthermore, since the transition layer 12c is formed of a single atomic layer, in addition to improvement of adhesion between the metal film 13 and the insulation film (i.e., each of the second insulation film 6, the third insulation film 7 and the fourth insulation film 8), a barrier metal film can be formed so as to have a small thickness by reducing the thickness of the transition layer 12c to an absolute minimum even when the barrier metal film has a lamination structure, so that a resistance of a wire can be reduced. Therefore, a highly reliable semiconductor device including a multi-layer wire with a low resistance and excellent adhesion can be fabricated.
When the transition layer 12c and the metal film 13 are formed by atomic layer deposition using different metals for a metal forming the metal oxide and a metal forming the metal film 13, respectively, the transition layer 12c and the metal film 13 can be continuously formed, for example, only by changing film formation conditions or a source gas.
When the transition layer 12c and the metal film 13 are formed by atomic layer deposition using the same element for the metal forming the metal oxide and the metal forming the metal film 13, the transition layer 12c and the metal film 13 can be continuously formed, for example, only by changing film formation conditions.
Hereinafter, a semiconductor device according to a fourth embodiment of the present invention and a method for fabricating the semiconductor device will be described with reference to
As shown in
As has been described, in the semiconductor device according to the fourth embodiment of the present invention, the transition layer 12d having substantially the intermediate composition between the respective compositions of the metal film 13 and the metal oxide exists at the interface between the metal film 13 and an insulation film (i.e., each of the second insulation film 6, the third insulation film 7 and the fourth insulation film 8), so that adhesion between the metal film 13 and the insulation film (i.e., each of the second insulation film 6, the third insulation film 7 and the fourth insulation film 8) is remarkably improved, compared to the case where the transition layer 12d does not exist at the interface between the metal film 13 and the insulation film (i.e., each of the second insulation film 6, the third insulation film 7 and the fourth insulation film 8). Thus, a barrier metal film having a small thickness and excellent adhesion can be formed. Furthermore, as another effect, the transition layer 12d is formed of a plurality of atomic layers, so that adhesion is further improved, compared to the case where the transition layer 12d provided between the metal film 13 and the insulation film (i.e., the second insulation film 6, the third insulation film 7 and the fourth insulation film 8) is formed of a single atomic layer. Moreover, the composition of the transition layer 12d varies stepwise, so that adhesion is further improved. Therefore, a highly reliable semiconductor device including a multi-layer wire with a low resistance and excellent adhesion can be achieved.
A metal forming the metal oxide which determines the composition of the transition layer 12d and a metal forming the metal film 13 may be different elements. In such a case, in a layer structure of the metal film 13/the transition layer 12d/an insulation film (i.e., each of the second insulation film 6, the third insulation film 7 and the fourth insulation film 8), adhesion between the transition layer 12d and the insulation film (i.e., each of the second insulation film 6, the third insulation film 7 and the fourth insulation film 8) can be optimized according to a kind of the insulation film (i.e., each of the second insulation film 6, the third insulation film 7 and the fourth insulation film 8) without degrading adhesion between the metal film 13 and the transition layer 12d. Therefore, a highly reliable semiconductor device including a multi-layer wire with a low resistance and excellent adhesion can be achieved.
Moreover, a metal forming the metal oxide film which determines the composition of the transition layer 12d and a metal forming the metal film 13 may be the same element. In such a case, adhesion at an interface between the metal film 13 and the transition layer 12d can be improved in a layer structure of the metal film 13/the transition layer 12d. Therefore, a highly reliable semiconductor device including a multi-layer wire with a low resistance and excellent adhesion can be achieved.
Next, a method for fabricating a semiconductor device according to the fourth embodiment of the present invention will be described with reference to
a) through 12(c) are cross-sectional views of relevant part of a semiconductor device according to the fourth embodiment of the present invention illustrating respective steps for fabricating the semiconductor device.
First, in the same manner as shown in
As shown in
Next, as shown in
Hereinafter, a method for forming the second barrier metal A4, for example, in the case where a metal forming the metal film 13 is ruthenium (Ru) and the metal oxide which determines the composition of the transition layer 12d is ruthenium oxide (RuO2) will be described in detail.
A known atomic layer deposition technique (Journal of The Electrochemical Society, 151, G109-G112 (2004)) is used to form the transition layer 12d and the metal film 13 which together form the second barrier metal film A4. Conditions for film formation in this case are as follows. For example, Ru(EtCp)2 (bis(ethylcyclopentadienyl)ruthenium) gas is used as a source gas of ruthenium (Ru). Where the source gas is heated to 80° C., the source gas is diluted with Ar gas of 50 mL/min (standard temperature and pressure, dry) for use. The temperature of a substrate is 250° C. and the degree of vacuum is 4.66×102 Pa. As oxygen gas, a gas obtained by mixing Ar gas of 100 mL/min (standard temperature and pressure, dry) to oxygen gas of 70 mL/min (standard temperature and pressure, dry) is used. An arbitrary composition in the range from metal ruthenium to ruthenium oxide can be obtained by changing a pulse time used for supplying Ru(EtCp)2 gas. The range of the pulse time is from 1 second to 10 seconds. After Ru(EtCp)2 gas is supplied and then purged for a certain period of time, oxygen gas is supplied. When the supply of oxygen gas is stopped, purge is performed for a certain period of time. Thus, a film of a single atomic layer of Ru and O can be grown. This series of steps is assumed to be a cycle. When metal ruthenium is grown, oxygen gas is not supplied.
For example, with the pulse time for supplying Ru(EtCp)2 changed in a stepwise manner to 3 seconds, 5 seconds and then 7 seconds, the transition layer 12d having an intermediate composition between respective compositions of ruthenium oxide and ruthenium is formed on the second insulation film 6, the third insulation film 7 and the fourth insulation film 8, thereby obtaining a structure of three atomic layers. Next, with a pulse time of 10 seconds for supplying Ru(EtCp)2, a ruthenium (Ru) film, i.e., the metal film 13 is deposited to a thickness of 5 nm. In the second barrier metal film A4 formed in the above-described manner, a distribution of atomic concentration in the film thickness direction is as shown in
Next, a copper film is formed over the metal film 13 as well as inside the recess portion 10c by copper electroplating so as to fill the recess portion 10c and then parts of the copper film, the metal film 13 and the transition layer 12d located on the fourth insulation film 8, except for parts thereof located inside the recess portion 10c, are removed by CMP, thereby forming a second copper wire 14 and a via plug which is part of the second copper wire 14. Thus, a semiconductor device having the structure of
As has been described, according to the method for fabricating a semiconductor device according to the fourth embodiment of the present invention, the transition layer 12d having substantially the intermediate composition between the respective composition of the metal film 13 and the metal oxide and including a plurality of atomic layers can be formed in a simple manner at the interface between the metal film 13 and the insulation film (i.e., each of the second insulation film 6, the third insulation film 7 and the fourth insulation film 8). Moreover, the same effects as those of the semiconductor device of the fourth embodiment can be achieved. Specifically, the transition layer 12d having substantially an intermediate composition between the respective compositions of the metal film 13 and the metal oxide is formed at the interface between the metal film 13 and the insulation film (i.e., each of the second insulation film 6, the third insulation film 7 and the fourth insulation film 8), so that adhesion between the metal film 13 and the insulation film (i.e., each of the second insulation film 6, the third insulation film 7 and the fourth insulation film 8) can be remarkably improved, compared to the case where the transition layer 12d does not exist at the interface between the metal film 13 and the insulation film (i.e., each of the second insulation film 6, the third insulation film 7 and the fourth insulation film 8). Accordingly, a barrier metal film having a small thickness and excellent adhesion can be formed. Furthermore, as another effect, since the transition layer 12d is formed of a plurality of atomic layers, adhesion between the metal film 13 and the insulation film (i.e., each of the second insulation film 6, the third insulation film 7 and the fourth insulation film 8) is further improved, compared to the case where a transition layer provided between the metal film 13 and the insulation film (i.e., each of the second insulation film 6, the third insulation film 7 and the fourth insulation film 8) is formed of a single atomic layer. Moreover, adhesion can be further improved by changing the composition of the transition layer 12d stepwise. Therefore, a highly reliable semiconductor device including a multi-layer wire with a low resistance and excellent adhesion can be fabricated.
When the transition layer 12d and the metal film 13 are formed by atomic layer deposition using different metals for a metal forming the metal oxide and a metal forming the metal film 13, respectively, the transition layer 12d and the metal film 13 can be continuously formed, for example, only by changing film formation conditions or a source gas.
When the transition layer 12d and the metal film 13 are formed by atomic layer deposition using the same element for the metal forming the metal oxide and the metal forming the metal film 13, the transition layer 12d and the metal film 13 can be continuously formed, for example, only by changing film formation conditions.
Hereinafter, a semiconductor device according to a fifth embodiment of the present invention and a method for fabricating the semiconductor device will be described with reference to
As shown in
As a metal contained in the second barrier metal film A5, a refractory metal is preferably used. Thus, in the process step of forming a wire of an upper layer after formation of the second copper wire 14, even when heat of about 400° C. is applied, the second barrier metal film A5 does not degrade due to the heat treatment. Therefore, a highly reliable semiconductor device can be achieved.
When the second barrier metal film A5 has a small thickness, the second barrier metal film A5 does not necessarily have conductivity. However, it is preferable that the second barrier metal film A5 has conductivity. Hereinafter, the second barrier metal film A5 having conductivity will be specifically described.
As a metal forming the barrier metal film A5, titanium (Ti), zirconium (Zr), hafnium (Hf), tantalum (Ta), niobium (Nb), tungsten (W), vanadium (V), molybdenum (Mo), ruthenium (Ru), osmium (Os), rhodium (Rh), iridium (Ir), palladium (Pd) or platinum (Pt) is preferably used.
It is more preferable that as a metal forming the second barrier metal film A5, vanadium (V), molybdenum (Mo), ruthenium (Ru), osmium (Os), rhodium (Ru), iridium (Ir), palladium (Pd), platinum (Pt) or the like is used. Thus, when the metal is oxidized, conductivity is not largely lost (or a resistivity is small), so that the second barrier metal film A5 having a low resistance can be formed.
As has been described, in the semiconductor device according to the fifth embodiment of the present invention, the oxygen concentration in the second barrier metal film A5 of a film containing oxygen as a component element continuously varies in the direction from a surface of the second barrier metal film A5 which is in contact with an insulation film (i.e., the second insulation film 6, the third insulation film 7 and the fourth insulation film 8) to a surface of the second barrier metal film A5 which is in contact with the second copper wire 14. Thus, the second barrier metal film A5 does not have an interface at which a composition is remarkably changed, so that the strength of the second barrier metal film A5 itself can be largely improved. Therefore, a highly reliable semiconductor device including a multi-layer wire with a low resistance and excellent adhesion can be achieved. Furthermore, by increasing the oxygen concentration in the vicinity of the interface between the second barrier metal film A5 and the insulation film (i.e., each of the second insulation film 6, the third insulation film 7 and the fourth insulation film 8), adhesion between the second barrier metal film A5 and the insulation film (i.e., the second insulation film 6, the third insulation film 7 and the fourth insulation film 8) can be improved. Also, by reducing the oxygen concentration in the vicinity of the interface between the second barrier metal film A5 and the second copper wire 14, adhesion between the second barrier metal film A5 and the second copper wire 14 can be improved.
Next, a method for fabricating a semiconductor device according to the fifth embodiment of the present invention will be described with reference to
First, in the same manner as shown in
Next, as shown in
Hereinafter, a method for forming the second barrier metal A5, for example, in the case where the second barrier metal film A5 has an oxygen concentration which continuously varies from ruthenium (Ru) to ruthenium oxide (RuO2) will be described in detail.
A known atomic layer deposition technique (Journal of The Electrochemical Society, 151, G109-G112 (2004)) is used to form the second barrier metal film A5. Conditions for film formation in this case are as follows. For example, Ru(EtCp)2 (bis(ethylcyclopentadienyl)ruthenium) gas is used as a source gas of ruthenium (Ru). Where the source gas is heated to 80° C., the source gas is diluted with Ar gas of 50 mL/min (standard temperature and pressure, dry) for use. The temperature of a substrate is 250° C. and the degree of vacuum is 4.56×102 Pa. As oxygen gas, a gas obtained by mixing Ar gas of 100 mL/min (standard temperature and pressure, dry) to oxygen gas of 70 mL/min (standard temperature and pressure, dry) is used. An arbitrary composition in the range from metal ruthenium to ruthenium oxide can be obtained by changing a pulse time used for supplying Ru(EtCp)2 gas. The range of the pulse time is from 1 second to 10 seconds. After Ru(EtCp)2 gas is supplied and then purged for a certain period of time, oxygen gas is supplied. When the supply of oxygen gas is stopped, purge is performed for a certain period of time. Thus, a film of a single atomic layer of Ru and O can be grown. This series of steps is assumed to be a cycle. When metal ruthenium is grown, oxygen gas is not supplied.
For example, with the pulse time for supplying Ru(EtCp)2 continuously changed from 2 seconds to 10 seconds, the second barrier metal film A5 is formed on the second insulation film 6, the third insulation film 7 and the fourth insulation film 9 so as to have a thickness of 10 nm. In the second barrier metal film A5 formed in the above-described manner, a distribution of atomic concentration in the film thickness direction is as shown in
Next, a copper film is formed over the second barrier metal film A5 as well as inside the recess portion 10c by copper electroplating so as to fill the recess portion 10c and then parts of the copper film and the second barrier metal film A5 located on the fourth insulation film 8, except for parts thereof located inside the recess portion 10c, are removed by CMP, thereby forming a second copper wire 14 and a via plug which is part of the second copper wire 14. Thus, a semiconductor device having the structure of
As has been described, according to the method for fabricating a semiconductor device according to the fifth embodiment of the present invention, the second barrier metal film A5 of which an oxygen element concentration continuously varies in the film thickness direction can be formed in a simple manner. Moreover, the same effects as those of the semiconductor device of the fifth embodiment can be achieved. Specifically, in the second barrier metal film A5 of a film containing oxygen as a component element, the concentration of oxygen continuously varies in the direction from a surface of the second barrier metal film A5 which is in contact with an insulation film (i.e., each of the second insulation film 6, the third insulation film 7 and the fourth insulation film 8) to a surface of the second barrier metal film A5 which is in contact with the second copper wire 14. Thus, the second barrier metal film A5 does not have an interface at which a composition is remarkably changed, so that the strength of the second barrier metal film A5 itself can be largely improved. Therefore, a highly reliable semiconductor device including a multi-layer wire with a low resistance and excellent adhesion can be achieved. Furthermore, by increasing the oxygen concentration in the vicinity of the interface between the second barrier metal film A5 and the insulation film (i.e., each of the second insulation film 6, the third insulation film 7 and the fourth insulation film 8), adhesion between the second barrier metal film A5 and the insulation film (i.e., the second insulation film 6, the third insulation film 7 and the fourth insulation film 8) can be improved. Also, by reducing the oxygen concentration in the vicinity of the interface between the second barrier metal film A5 and the second copper wire 14, adhesion between the second barrier metal film A5 and the second copper wire 14 can be improved.
In each of the above-described first through fifth embodiments, the case where a dual damascene structure is adopted has been described. However, needless to say, even when a single damascene structure is adopted, the same effects as those in the case of adoption of a dual damascene structure can be achieved. When a single damascene structure is adopted, a wire and a via plug are formed in separate steps. In such a case, the wire and the via plug are included in a buried wire, i.e., the second copper wire 14 of each of the first through fifth embodiments.
As has been described, the present invention is useful to a semiconductor device including a barrier metal film with a low resistance and excellent adhesion and a method for fabricating the semiconductor device.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-182692 | Jun 2004 | JP | national |
This application is the U.S. National Phase under 35 U.S.C. § 371 of International Application No. PCT/JP2005/009269, filed on May 20, 2005, which in turn claims the benefit of Japanese Application No. 2004-182692, filed on Jun. 21, 2004, the disclosures of which Applications are incorporated by reference herein.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP05/09269 | 5/20/2005 | WO | 00 | 5/5/2006 |
