Patent Application
20090087339
1. Field of the Invention
The present invention relates to a method for forming a ruthenium (Ru) film for metal wiring structures that can be used favorably in the creation of fine semiconductor elements in general.
2. Description of the Related Art
Ru film is drawing the attention for its property to improve the adhesion with Cu, when a Ru film is formed at the interface between Cu and barrier metal in a Cu wiring structure which is the main wiring structure used in high-speed logic elements such as MPUs, and thereby significantly enhance the reliability of wiring. Methods are being studied to form a Ru film that provides a Cu diffusion barrier metal on a TaN film or WN film and then form a Cu film on top of the Ru film (one example of such method relating to a combination of Ru and TaN is described in C. C. Yong et al., “Physical, Electrical, and Reliability Characterization of Ru for Cu Interconnects,” IITC 2006, pp. 187-189). To be specific, Cu liners having a laminated structure constituted by Ru/TaN, etc., are being studied.
With Cu liner films constituted by Ru/TaN, etc., which are examined for utilization as Cu wiring liners, the Cu wiring volume becomes relatively smaller as the thickness of the Cu liner film increases, and accordingly the Cu wiring resistance tends to become higher when the film is thicker. For this reason, it is necessary to form as thin a film as possible. In reality, however, a laminated structure constituted by a copper diffusion barrier film and Ru film prevents the formation of continuous film when the Ru film is made thinner, and the barrier film is partially exposed as a result. Consequently, an interface of Cu wiring and barrier film is created and this interface can present problems. On the other hand, making the Ru film thicker as a way to form a continuous film increases the Cu wiring resistance. In other words, it is desirable to form a thin but continuous Ru film. It is also desirable that this Ru film be formed in a reducing atmosphere in order to prevent the aforementioned barrier film from being oxidized when the Ru film is formed on a copper diffusion barrier film such as a TaN film or TaNC film.
According to U.S. Patent Laid-open No. 2006/0177601A, a Ru film can be formed in a reducing atmosphere through a step to supply a Ru material containing a ligand constituted by a cyclopentadienyl group and another step to treat a substrate using NH3 gas activated by high frequency.
In an embodiment of the present invention, at least one of the problems described below can be solved.
Although TaN and TaCN films are excellent copper diffusion barriers, when a Ru film is formed in an oxidizing atmosphere in the process of forming a Ru/TaCN or Ru/TaN laminated structure, it is possible that TaN or TaCN is oxidized. When Ru is formed by means of NH3 plasma, on the other hand, TaN or TaCN may be nitrided. Either way, the resistance will increase. This is probably because the very high resistance of the tantalum nitride having a Ta3N5 composition causes the nitrogen content to increase as a result of nitriding of TaN/TaCN, thereby resulting in higher resistance. There are also reports that when the preferred orientation of the crystal of Ru film becomes (002), the adhesion with Cu film becomes more favorable (for example, refer to Hoon Kim et al., “Cu Wettability and Diffusion Barrier Property of Ru Thin Film for Cu Metallization,” Journal of The Electrochemical Society, 152 (8) G594-G600 (2005)), which means that controlling the crystalline property of Ru film is very important. According to U.S. Patent Laid-open No. 2006/0177601A, a Ru film can be formed in a reducing atmosphere through a step to supply a Ru material containing a ligand constituted by a cyclopentadienyl group and another step to treat a substrate using NH3 gas activated by high frequency. However, the Ru film obtained this way tends to have a random crystalline orientation. Accordingly, a method for forming a Ru film having a greater preferred orientation along (002) is desired.
In an embodiment, the present invention provides a method for depositing a thin ruthenium (Ru) film on a substrate in a reaction chamber, wherein this method comprises: step (i) to supply at least one type of gas of a ruthenium precursor being a β-diketone-coordinated ruthenium complex and cause the gas to be adsorbed to the substrate in the reaction chamber; step (ii) to supply a reducing gas into the reaction chamber and excite the reducing gas, or supply an excited reducing gas into the reaction chamber, in order to activate the ruthenium precursor adsorbed to the substrate; and step (iii) to repeat steps (i) and (ii) to form a thin ruthenium film on the substrate. “Activate” means, in an embodiment, severing the β-diketone ligand bond with the ruthenium precursor and thereby discharging β-diketone, which in turn means promoting the formation of a purer ruthenium film.
In an embodiment, the ruthenium complex coordinated by β-diketone has the structure shown below:
Here, X1 and X2 are hydrocarbons that are independent of each other or for each ligand, where X1 and X2 may form a hydrocarbon ring. Both X1 and X2 are desirably an alkyl group (such as an alkyl group having 1 to 4 carbon atoms), expressed by CR1R2R3 in an embodiment, where R1, R2 and R3 are hydrogen or CmH2 m+1 (m=1 to 3) (preferably a hydrogen or ethyl group) and independent of one another. Also, n is a value between 1 and 4, or 2 or 3 in an embodiment. Each β-diketone coordinated to ruthenium may be the same or different. In some cases, each group may be further substituted by other group. It is easy to form a nucleus and obtain a desired orientation with ruthenium complexes described above, which is extremely effective in an early step of the film formation process. It is also possible to form a film constituted by such ruthenium complex to reduce the resistivity of the obtained ruthenium film without using ammonia plasma as required in conventional methods.
In an embodiment, the coordination of β-diketone and ruthenium is achieved by conjugation of the second ketone group and C═C double bonds. In other words, β-diketone assumes a conjugated structure upon coordination.
If two β-diketones are coordinated to ruthenium to form a conjugated structure, for example, a structure like the one illustrated below may be obtained:
Here, in an embodiment, X1 to X4 are independently —CH3, —C(CH3)3, —CH(CH3)2 or —CH2(CH3). X1=X4 and X2=X3 may be established, and if X1=X4, then X2≠X3 may be true. X1 may be the same as or different from X2, and X3 may be the same as or different from X4. Also, X1 and X2, or X3 and X4, may together constitute a ring such as 1,3-cyclohexane dione.
There are cases where coordination is achieved without forming a conjugated structure.
An example where three β-diketones are coordinated to ruthenium by means of conjugated bonding is shown below:
Here, examples of β-diketone (1,3-diketone) include diketone having 5 carbon atoms expressed as follows:
X1 and X2 are the same as the corresponding items in the formula mentioned earlier.
This structure may be 2,4-pentendione, for example, where there may be hydrogen at both ends or each end may be substituted by an alkyl group having around 1 to 3 carbon atoms. Specific examples of β-diketone include acetyl acetone, dipivaloyl methane, diisobutyryl methane and isopivaloyl methane.
One or more types of ruthenium complexes coordinated by β-diketone may be used alone or in combination. Also, such one or more types of β-diketone-coordinated ruthenium complexes may be combined with one or more types of ruthenium complexes coordinated by a ligand other than β-diketone. As for such other ruthenium complexes, those disclosed in U.S. patent application Ser. No. 11/469,828 (U.S. Patent Laid-open No. 2008/0054472) and U.S. patent application Ser. No. 11/557,891 (U.S. Patent Laid-open No. 2008/0124484), both filed by the same applicant for the present application for patent, can be used. The disclosure of each of the above U.S. applications, specifically the disclosure of a ruthenium complex and method for forming a film using such ruthenium complex, is herein incorporated by reference in its entirety. In other words, any part of each of the above U.S. applications may be adopted in any embodiment with respect to the type, forming condition or any other aspect of any reducing gas, oxidizing gas, metal underlayer, laminated structure containing other ruthenium complex layer, copper wiring layer, or the like, disclosed in the present application for patent, without being specifically stated in the present application for patent.
β-diketone-coordinated ruthenium complexes can be synthesized by chemical synthesis manufacturers and therefore can be obtained from chemical synthesis manufacturers.
For purposes of summarizing aspects of the invention and the advantages achieved over the related art, certain objects and advantages of the invention are described in the present disclosure. Of course, it is to be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.
Further aspects, features and advantages of this invention will become apparent from the detailed description which follows.
These and other features of this invention will now be described with reference to the drawings of preferred embodiments which are intended to illustrate and not to limit the invention.
a) shows the molecular structure of a Ru precursor used in an embodiment of the present invention.
b) shows the molecular structure of a Ru precursor used in an embodiment of the present invention.
a) shows the sequence of a Ru formation process used in an embodiment of the present invention.
b) shows the sequence of a Ru formation process used in an embodiment of the present invention.
a) to (f) provide a schematic view showing one process based on a process flow of (a)→(b)→(c)→(d)→(e)→(f), used to apply a Ru film forming process conforming to an embodiment of the present invention in a dual damascene Cu wiring process.
a) is a TEM cross-section image of a 5-nm Cu-CVD film formed on a Ru film having (002)-preferred orientation.
b) is a TEM cross-section image of a Cu-CVD film of 5 nm or equivalent formed on a conventional Ru film having a random orientation.
a) to (f) provide a schematic view showing one process based on a process flow of (a)→(b)→(c)→(d)→(e)→(f), used to apply a Ru film forming process conforming to an embodiment of the present invention in a dual damascene Cu wiring process.
The present invention will be explained with reference to preferred embodiments and drawings. However, the preferred embodiments and drawings are not intended to limit the present invention.
Favorable embodiments included in the aforementioned embodiments of the present invention are explained below. It should be noted, however, that the present invention is not at all limited to these embodiments.
In an embodiment conforming to one of the aforementioned methods, at least one type of ruthenium complex having a Xa-Ru-Xa or Xa-Ru-Xb structure can be used, where Xa and Xb are different β-diketone ligands and each may have a side chain bonded to at least one of carbon 1 and carbon 5. Take note that each of these side chains may be an alkyl group or non-alkyl group, as long as severance of the bond between the β-diketone group and ruthenium atom is not obstructed.
In an embodiment conforming to one of the aforementioned methods, at least one of Xa and Xb is a β-diketone complex selected from the group that includes an acetyl acetone group, dipivaloyl methane group, diisobutyryl methane group and isopivaloyl methane group.
In an embodiment conforming to one of the aforementioned methods, the excited reducing gas may be generated by applying high frequency to a reducing gas. In an embodiment, the reducing gas is hydrogen, gas containing hydrogen, or gas constituted by hydrogen atoms. In an embodiment, the excited reducing gas is plasma of hydrogen, gas containing hydrogen, or gas constituted by hydrogen atoms. Take note, however, that if nitriding of the underlayer must be avoided, then it is desirable that the excited reducing gas be plasma of hydrogen or mixture gas of hydrogen and inert gas not containing nitrogen atoms.
In an embodiment conforming to one of the aforementioned methods, such method can further include a step, after step (i), to purge the ruthenium precursor gas from the reaction chamber and a step, after step (ii), to purge the excited reducing gas from the reaction chamber.
In an embodiment conforming to one of the aforementioned methods, a thin ruthenium film with a thickness of 0.5 m or more, but not exceeding 2.0 nm, can be formed by repeating steps (i) and (ii).
In an embodiment conforming to one of the aforementioned methods, a thin ruthenium film having a preferred crystalline orientation along Ru (002) can be formed by repeating steps (i) and (ii). This film thickness can also be controlled to a range of 0.5 to 2.0 nm.
In an embodiment, one of the aforementioned methods being used can include a step to add a metal film before steps (i) to (iii) for forming a thin ruthenium film on a metal film. The metal film may be at least one type selected from the group that includes WNC, WN, TaN, RuTaN, Ta, RuTa, TaNC, RuTaNC, TiN, RuTiN, Ti, RuTi, Cu, Al, Co and Ni.
In an embodiment conforming to one of the aforementioned methods, the gas of the ruthenium precursor in step (i) can be used as a first gas, while a further step can be included in step (i) to supply a second gas of a different ruthenium precursor into the reaction chamber simultaneously as the first gas. This different ruthenium precursor may be one having a pentadienyl group coordinated to Ru. Since it is easy to form a nucleus in an initial stage when the Ru precursor having β-diketone is used that constitutes the first gas, a thin ruthenium film can be formed effectively by combining the first gas and different ruthenium precursor.
In other embodiment, one of the aforementioned methods being used can further include, after step (iii) consisting of repetition of steps (i) and (ii) for a specified number of times: step (iv) to supply into the reaction chamber a ruthenium precursor which is the same as or different from the ruthenium precursor supplied in step (i) and cause this ruthenium precursor to be adsorbed to the substrate; step (v) to supply into the reaction chamber an oxidizing gas or excited oxidizing gas so as to activate the different ruthenium precursor adsorbed to the substrate; and step (vi) to repeat steps (iv) and (v) and thereby form a thin ruthenium film or ruthenium oxide film on the substrate. If an oxidizing gas is used, the deposition speed becomes faster and the productivity also improves. The Ru film formed in step (iii) can prevent the oxidization of the metal underlayer.
In other embodiment, one of the aforementioned methods being used can further include, after step (iii) consisting of repetition of steps (i) and (ii) for a specified number of times: step (iv) to supply into the reaction chamber a second gas of a different ruthenium precursor and cause the second gas of the different ruthenium precursor to be adsorbed to the substrate; step (v) to supply an excited reducing gas into the reaction chamber so as to activate the different ruthenium precursor adsorbed to the substrate; and step (vi) to repeat steps (iv) and (v) and thereby form a thin ruthenium film on the substrate. Here, a pentadienyl-group-coordinated form of Ru can be used as the different ruthenium precursor.
In other embodiment, one of the aforementioned methods being used can further include a step, after step (iii), to form a thin ruthenium film or thin ruthenium oxide film on the thin ruthenium film by means of CVD. In this case, oxidization of the underlayer can be prevented by the Ru film formed beforehand, even when CVD is implemented using an oxidizing gas, and thus the underlying metal film will not be oxidized. Also, a ruthenium film can be formed productively using CVD.
In an embodiment conforming to one of the aforementioned methods, a step may be included, after step (iii) or (vi) or after step (iii), to form a copper film on the thin ruthenium film formed by means of CVD. This copper film may be formed based on CVD or ALD or by supplying the gas of a copper precursor to the substrate.
In other embodiment, one of the aforementioned methods being used can further include a step, after step (iii), to form a copper film on the thin ruthenium film having (002)-preferred crystalline orientation. This copper film may be formed based on CVD or ALD or by supplying the gas of a copper precursor to the substrate. Also, the thickness of the film formed in step (iii) is preferably controlled to a range of 2 to 0.5 μm, and also the film preferably has (002)-preferred orientation.
A thin ruthenium film can be formed using a ruthenium complex containing β-diketone. The substrate may have a metal film, and a thin ruthenium film may be formed on the metal film. For this metal film, at least one type can be selected from the group that includes WNC, WN, TaN, RuTaN, Ta, RuTa, TaNC, RuTaNC, TiN, TuTiNi, Ti, RuTi, Cu, Al, Co and Ni. Such metal wiring structure containing ruthenium can further have a copper film on the thin ruthenium film.
The aforementioned metal wiring structure containing ruthenium can also have a thin ruthenium film with a thickness of 0.5 to 2 μm and preferred crystalline orientation along Ru (002), and a copper film can also be provided on this thin ruthenium film.
In an embodiment, the metal film is made of a metal containing Cu, Al or Co, or metal containing Ni, while the thin ruthenium film formation structure may also have a thin ruthenium film with a thickness of 0.5 to 2 nm and preferred crystalline orientation along Ru (002), and furthermore it can be provided as a metal wiring structure containing a ruthenium film characterized in that a metal film made of any metal selected from the group that includes WNC, WN, TaN, RuTaN, Ta, RuTa, TaNC, RuTaNC, TiN, RuTiN, Ti and RuTi is formed on this thin ruthenium film to prevent diffusion of copper. In addition, a copper film can be formed after forming a thin ruthenium film on this metal film for blocking copper diffusion. The purpose here is to form at each of the interfaces with copper films for upper/lower wirings a ruthenium film conforming to an embodiment of the present invention, and then form between these ruthenium films a copper diffusion blocking film made of any metal selected from the group that includes WNC, WN, TaN, RuTaN, Ta, RuTa, TaNC, RuTaNC, TiN, RuTiN, Ti and RuTi, in order to form a favorable interface between ruthenium and copper and thereby enhance the reliability of wiring.
In an embodiment conforming to one of the aforementioned methods, the thickness of the diffusion blocking film formed as a lower layer of the Ru film should be 1 to 10 nm, or preferably be 1 to 3 nm. If a Ru-containing metal film (such as Ru—Ta alloy film or Ru-—Ti alloy film) is used as this lower layer, adhesion with the Ru film can be increased further. A Ru-containing metal film can be implemented based on, for example, the methods disclosed in U.S. patent application Ser. No. 12/129,345 (filed on May 29, 2008) and U.S. patent application Ser. No. 11/955,275 (filed on Dec. 12, 2007), both filed by the same applicant for the present application for patent and the disclosure of each of which is herein incorporated by reference in its entirety for Ru alloy film formation.
The foregoing explained the specific purposes and advantages of embodiments of the present invention in order to summarize the superior advantages offered by these embodiments of the present invention as well as related technologies achieved therein. Each embodiment of the present invention represents a method for forming a ruthenium film, as well as a wiring structure using a ruthenium film formed by such method conforming to an embodiment of the present invention, together with the advantages offered by such ruthenium film and wiring structure. By using as a structure a ruthenium film formed by such method conforming to an embodiment of the present invention, a highly reliable wiring structure can be obtained. In this sense, the ruthenium forming method conforming to an embodiment of the present invention provides an effective invention, not only in respect of the forming method itself, but also in respect of the thin ruthenium film structure and metal wiring structure formed by such method.
Yet other embodiments, characteristics and advantages of the present invention should be revealed through the detailed explanation of favorable embodiments given below.
The aforementioned characteristics of some embodiments of the present invention are explained below by referring to drawings illustrating favorable embodiments.
In the present disclosure where conditions and/or structures are not specified, the skilled artisan in the art can readily provide such conditions and/or structures, in view of the present disclosure, as a matter of routine experimentation.
An embodiment of the present invention is characterized in that it provides a Ru film forming method including a step to supply to a substrate a ruthenium precursor having a Xa-Ru-Xb or Xa-Ru-Xa structure and where Xa and Xb are ligands constituted by β-diketone, and another step to use a reducing gas excited by high frequency to treat the substrate. This embodiment is also characterized in that a Ru film formed by the aforementioned forming method is used.
In an embodiment, the ruthenium precursor having a Xa-Ru-Xb or Xa-Ru-Xa structure and where Xa and Xb are ligands constituted by β-diketone may have an acetyl acetone group, dipivaloyl methane group, diisobutyryl methane group or isopivaloyl methane group as a ligand, or it can also have a ligand having a side chain constituted by at least one carbon in the carbon positions at both ends of β-diketone (carbon positions 1 and 5 in the case of 2,4-pentenedione). The molecular structures shown in
a) and (b) show ruthenium precursors having a Xa-Ru-Xa structure and Xa-Ru-Xb structure, respectively. In
Under U.S. Patent Laid-open No. 2006/0177601A1, structures are limited to those having a cyclopentadienyl group and use of other Ru compounds is prohibited. This is because the cyclopentadienyl group is extremely stable chemically and therefore easy to handle. However, severing and removing cyclopentadienyl groups requires ammonia plasma, and this is understood, by the inventor of the present invention, as a key point of the aforementioned invention. On the other hand, a problem exists where the TaN film used as a Cu barrier film will be nitrided if ammonia plasma is used, and this will increase the resistance, as described as the problems to be solved by the present invention. Accordingly, after examining Ru precursors the inventor found that in many cases ligands constituted by β-diketone could be removed from Ru precursors containing β-diketone by using hydrogen plasma, and that the resistivity of ruthenium film could therefore be lowered without using ammonia plasma. It was also revealed that a Ru film formed by this method could be easily oriented to (002) on a metal film. The (002) orientation represents an extremely advantageous orientation to have when a Cu film is to be formed on this Ru film. Accordingly, the method proposed in each embodiment of the present invention presents an extremely advantageous method and innovative technology to achieve a desirable crystalline orientation without having to expose the underlying metal film to nitrogen plasma, which was not possible under the conventional Ru-ALD process.
a) and (b) show basic processes in embodiments. Take note, however, that the embodiments explained below are not intended to limit the present invention in any way.
In
Next, the supply of Ru material is stopped and the aforementioned gas is purged (using an inert gas supplied at a flow rate of 1,000 to 3,000 sccm) to discharge the remaining Ru material gas from the reaction chamber. Thereafter, hydrogen gas is introduced and when the process pressure stabilizes, 200 to 1,000 W of high-frequency output (including 300 W, 500 W, 700 W and any other output between the foregoing numbers) based on a high frequency of 13.56 kHz is used to apply high frequency and thereby excite hydrogen (H2) gas supplied as a reducing gas at a flow rate in a range of 200 to 700 sccm (preferably 300 to 500 sccm), in order to activate the Ru precursor adsorbed to the substrate surface and sever the bond between the Ru element and β-diketone, and also discharge the resulting reaction products from the reaction chamber. Next, introduction of high frequency and that of hydrogen gas, used as reducing gas, are stopped and an inert gas is used to purge the reaction chamber. These steps can be repeated to grow the Ru film.
In
Next, in an embodiment the aforementioned gas is purged (using an inert gas supplied at a flow rate of 1,000 to 3,000 sccm) to discharge the remaining Ru material gas from the reaction chamber. Thereafter, hydrogen gas that has been excited by microwave beforehand is introduced into the reaction chamber. The Ru precursor adsorbed to the substrate surface is activated by this so-called hydrogen radicals, and as a result the bond of β-diketone with ruthenium is dissociated and β-diketone is discharged from the reaction chamber. H2 gas can be supplied at a flow rate in a range of 200 to 700 sccm (preferably 300 to 500 sccm). As for the inert gas, Ar can be supplied at a flow rate in a preferable range of 300 to 2,000 sccm (or more preferable range of 500 to 1,200 sccm). The pressure condition can be adjusted to an optimal level between 1 and 3 torr. In an embodiment, the reducing gas is a gas containing hydrogen, and using H2, or mixture gas of Ar and H2 or He and H2, should not present problems. The mixing ratio of H2 and N2 is in a range of 0.01 to 1000 in an embodiment, or preferably in a range of 0.1 to 100. The mixing ratio of H2 and Ar or H2 and He is in a range of 0.01 to 10 in an embodiment, or preferably in a range of 0.1 to 10.
In addition, the upper diffusion chamber 38 and lower diffusion chamber 7, both installed at the shower plate 4, have exhaust valves 9, 32 for purging the gas introduced into the diffusion chambers, and it is possible to introduce a purge gas from purge gas introduction valves 20, 40. These functions are provided for the purpose of quickly introducing a purge gas and thus exhausting a reaction gas after the reaction gas has been introduced into the showerhead through valves 21, 23.
How the processes shown in
The process shown in
This process of introducing hydrogen radicals supplies hydrogen gas from a valve 36, and at the same time a valve 34 is opened and a radical source 35 is started roughly simultaneously. The radical source is designed so that microwave can be introduced, and the introduced hydrogen turns into hydrogen radicals. These hydrogen radicals are supplied onto the substrate 15 through the upper diffusion chamber 38 and gas outlet from upper diffusion chamber 12. After hydrogen radicals have been introduced for a specified time, the radical source 35 is stopped and the gas valves 36, 34 are closed. By replacing the hydrogen plasma process in
Specific examples are explained using
Application of a Ru film to semiconductor copper wiring using the process sequence shown in
a) to (f) show a process for forming a Cu wiring by forming a Cu barrier film via dual damascene wiring and then forming a Cu seed layer, followed by Cu plating and Cu CMP. In
Table 2 summarizes optimal conditions for this process. Formation of a Ru film using the apparatus illustrated in
In
As explained above, a Cu wiring offering extremely favorable adhesion and high reliability owing to a smooth Cu seed layer, even after plating, can be formed by using a Ru film conforming to an embodiment of the present invention, and a Cu/Ru/TaNC structure containing such Ru film. Also, use of Ru conforming to an embodiment of the present invention can enhance the reliability of Cu wiring dramatically.
Application of a Ru film to capacitor electrodes of a dynamic random access memory, among various semiconductor memory devices, is explained using the schematic cross-section structure views of capacitor electrodes shown in
a) shows the condition before the lower-layer electrode of a memory capacity is formed in the manufacturing process for dynamic random access memory cells having laminated capacitor electrodes. A silicon substrate 212 is in a so-called active range, being surrounded by an element separation range 213. Numeral 214 indicates a diffusion layer, and a conductive contact plug 216 is formed on the diffusion layer. Numeral 217 indicates a gate electrode, while numeral 219 indicates a conductive wire that becomes a bit wire. Numeral 218 is an inter-layer insulation film, numeral 221 is formed by the insulation film, and numeral 222 is a hole opening provided in a manner allowing a capacitor to be formed. A conductive layer connecting to the conductive plug is provided at the bottom of this hole opening 222. In
Table 3 summarizes optimal conditions for this process. Formation of a Ru film using the apparatus illustrated in
Accordingly, a Ru film offering favorable coverage can be formed, even over structures requiring high levels of coverage, by using a method conforming to an embodiment of the present invention.
Application of a Ru film to semiconductor copper wiring using the process sequence in
a) to (f) show a process for forming a Cu wiring by forming a Cu barrier film via dual damascene wiring and then forming a Cu seed layer, followed by Cu plating and Cu CMP. In
Table 2 summarizes optimal conditions for this process. Formation of a Ru film using the apparatus illustrated in
Here, a sequence similar to the Ru forming sequence shown in
Table 6 summarizes optimal conditions for this process. Formation of a Ru film using the apparatus illustrated in
As shown in this example, the Ru film 113, TaNC film 114 and Ru film 115 are formed at the same temperature, and accordingly they could be formed successively in vacuum inside the same reactor shown in
As explained above, a wiring exhibiting extremely favorable adhesion can be formed using a Ru film conforming to an embodiment of the present invention, and a Cu/Ru/TNC structure containing such Ru film. Also, the underlying TaNC layer is not nitrided and can be formed continuously with ease, which provides the effect of improving productivity compared when a conventional Ru film is used. In the aforementioned applications, you can substitute the TaNC film by a Ru-containing metal film such as RuTa, RuTaNC, RuTaN, RuTi, RuTiNC or RuTiN film, and still achieve similar effects. In particular, adhesion with the Ru film increases further by adding Ru to the lower layer.
The present invention includes the above mentioned embodiments and other various embodiments including the following:
1) A method for depositing a thin ruthenium (Ru) film on a substrate in a reaction chamber, comprising: step (i) of supplying at least one type of gas of a ruthenium precursor being a β-diketone-coordinated ruthenium complex and causing the gas to be adsorbed to the substrate in the reaction chamber; step (ii) of supplying a reducing gas into the reaction chamber and exciting the reducing gas, or supplying an excited reducing gas into the reaction chamber, thereby activating the ruthenium precursor adsorbed to the substrate; and step (iii) of repeating steps (i) and (ii) to form a thin ruthenium film on the substrate.
2) A method according to 1), wherein the ruthenium complex has a Ru(X)n structure (X is a β-diketone ligand, while n is 2 or 3), or more preferably a Xa-Ru-Xb or Xa-Ru-Xa structure where Xa and Xb represent different β-diketone ligands.
3) A method according to 2), characterized in that the β-diketone group expressed by Xa is a 2,4-pentenedione group where at least one of carbon 1 and carbon 5 is bonded to an alkyl group.
4) A method according to 2), characterized in that the β-diketone group expressed by Xb is a 2,4-pentenedione group where at least one of carbon 1 and carbon 5 is bonded to an alkyl group.
5) A method according to 3), wherein the β-diketone group expressed by Xa is an acetyl acetone group, dipivaloyl methane group, diisobutyryl methane group or isopivaloyl methane group.
6) A method according to 4), wherein the β-diketone group expressed by Xb is an acetyl acetone group, dipivaloyl methane group, diisobutyryl methane group or isopivaloyl methane group.
7) A method according to 1), wherein the gas supplied in step (ii) is a reducing gas and this reducing gas is at least one of hydrogen, gas containing hydrogen, or gas constituted by hydrogen atoms.
8) A method according to 1), wherein the gas supplied in step (ii) is an excited reducing gas and this step includes a step of generating a reducing gas that has been excited by applying high-frequency power to the reducing gas upstream of the reaction chamber.
9) A method according to 1), further comprising a step of purging the ruthenium precursor from the reaction chamber after step (i) and a step of purging the excited reducing gas from the reaction chamber after step (ii).
10) A method according to 1), wherein steps (i) and (ii) are repeated until the thickness of the formed thin ruthenium film becomes 0.5 nm or more, but not exceeding 2.0 nm.
11) A method according to 1), wherein steps (i) and (ii) are repeated until the preferred crystalline orientation of the formed thin ruthenium film becomes Ru (002).
12) A method according to 1), wherein steps (i) and (ii) are repeated until the thickness of the formed thin ruthenium film becomes 0.5 nm or more, but not exceeding 2.0 nm and also until the preferred crystalline orientation of the ruthenium film becomes Ru (002).
13) A method according to any one of 1) to 12), further comprising a step to form a metal film on the substrate before the start of steps (i) to (iii) for forming a thin ruthenium film.
14) A method according to 13), wherein the metal film is at least one type selected from the group that includes WNxCy, WN, TaN, Ta, TaNxCy, TiN and Ti.
15) A method according to 1), wherein the gas of the ruthenium precursor in step (i) is used as a first gas, while a further step is included in step (i) to supply a second gas of a different ruthenium precursor into the reaction chamber simultaneously as the first gas.
16) A method according to 1), further comprising after step (iii): step (iv) of supplying gas of a ruthenium precursor into the reaction chamber and causing the gas to be adsorbed to the substrate; step (v) of supplying into the reaction chamber an oxidizing gas or molecules constituted by oxygen atoms so as to activate the ruthenium precursor adsorbed to the substrate; and step (vi) of repeating steps (iv) and (v) and thereby forming a thin ruthenium film or thin ruthenium oxide film on the thin ruthenium film formed in step (iii).
17) A method according to 1), further comprising after step (iii): step (iv) of supplying into the reaction chamber a second gas of a different ruthenium precursor and causing the second gas of the different ruthenium precursor to be adsorbed to the substrate; step (v) of supplying a reactant gas to activate the second gas of the different ruthenium precursor adsorbed to the substrate; and step (vi) of repeating steps (iv) and (v) and thereby forming a thin ruthenium film or thin ruthenium oxide film on the thin ruthenium film formed in step (iii).
18) A method according to any one of 1) to 12), further comprising a step of forming on the thin ruthenium film after step (iii) a thin ruthenium film or thin ruthenium oxide film by means of CVD.
19) A method according to any one of 1) to 12), further comprising a step of forming a copper film on the thin ruthenium film after step (iii).
20) A method according to any one of 16) to 18), further comprising a step of forming a copper film on the thin ruthenium film or thin ruthenium oxide film formed in the step following step (iii).
21) A method according to 11), further comprising a step of forming a copper film on the thin ruthenium film having (002)-preferred crystal orientation after step (iii).
22) A method according to 12), further comprising a step of forming a copper film on the thin ruthenium film having a thickness of 0.5 nm or more, but not exceeding 2.0 μm as well as (002)-preferred crystal orientation after step (iii).
23) A method according to any one of 15) to 22), further comprising a step of adding a metal film on the substrate before the start of steps (i) to (iii) for forming a thin ruthenium film, and a step of forming a copper film on the thin ruthenium film after steps (i) to (iii).
24) A method according to 23), wherein the metal film is at least one type selected from the group that includes WNxCy, WN, TaN, Ta, TaNxCy, TiN and Ti.
25) A method according to any one of 19) to 24), wherein the copper film is formed by supplying onto the substrate a copper precursor gas generated by means of CVD or ALD.
26) A thin ruthenium film formation structure, comprising a substrate and a thin ruthenium film formed on the substrate by any one of the methods according to 1) to 25).
27) A thin ruthenium film formation structure according to 26), wherein the thin ruthenium film has (002)-preferred crystal orientation.
28) A thin ruthenium film formation structure according to 26) or 27), wherein the thin ruthenium film has a thickness of 0.5 μm or more, but not exceeding 2.0 nm.
29) A thin ruthenium film formation structure according to 26), 27) or 28), wherein the substrate has a metal film and the thin ruthenium film is formed on the metal film.
30) A thin ruthenium film formation structure according to 29), wherein the metal film is at least one type selected from the group that includes WNC, WN, TaN, Ta, TaNC, TiN, Ti, Cu, Al, Co and Ni.
31) A thin ruthenium film formation structure according to 26), 27) or 28), wherein the thin ruthenium film has on its top at least one type of metal film selected from the group that includes WNC, WN, TaN, Ta, TaNC, TiN and Ti and Cu is formed on top of this metal film.
It will be understood by those of skill in the art that numerous and various modifications can be made without departing from the spirit of the present invention. Therefore, it should be clearly understood that the forms of the present invention are illustrative only and are not intended to limit the scope of the present invention.
This application claims the benefit of U.S. Provisional Application No. 60/976,378, filed Sep. 28, 2007, and the disclosure of which is herein incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 60976378 | Sep 2007 | US |
