Method for forming ruthenium thin film

Abstract

The present invention relates to a method for forming a ruthenium thin film using a ruthenium precursor, comprising the following steps: forming a ruthenium thin film using a tricarbonyl group (η 4 Tricarbonyl(η 4 ‑methylene‑1,3‑propanediyl)Ruthenium((CO)3Ru‑TMM)) is used as a ruthenium precursor, and a ruthenium thin film is formed at a temperature in the range of 200 to 350°C by atomic layer deposition using the ruthenium precursor and a reaction gas. As the reaction gas, one or more selected from the group consisting of oxygen, hydrogen, water, and ammonia is preferably used. #imgabs0#

Description

Technical Field

[0001] The present invention relates to a method for forming a ruthenium thin film, and more particularly to a method for forming a ruthenium thin film by atomic layer deposition (ALD). Background Art

[0002] As semiconductor devices become smaller, wiring becomes smaller. The increase in wiring resistance and coupling capacitance between wirings causes RC delay, which hinders the high-speed operation of components. To solve these problems, copper (Cu) with low bulk resistance is used as the wiring material, and a low dielectric constant film (Low-k film) is used as the interlayer insulating film.

[0003] However, as miniaturization progresses further, new problems arise in copper wiring. In the case of wiring of 10nm-class semiconductor elements, the width of the wiring is smaller than the electron mean free path of copper, which is about 38.7nm, resulting in an increase in resistance value caused by scattering. Specifically, the resistance value of the wiring is the bulk resistance value, which is expressed as the sum of the resistivity caused by surface scattering and the resistivity caused by grain boundary scattering. The resistivity caused by surface scattering and the resistivity caused by grain boundary scattering are proportional to the total mean free path. Therefore, when the width of the wiring is smaller than the mean free path of the electrons, collisions with the sides or grain boundaries of the wiring dominate and produce an increase in resistance value caused by scattering. The finer the wiring, the more significant this problem is. Therefore, the actual situation is: the finer the wiring, the less advantages copper has as a wiring material, and it is necessary to study new wiring materials to replace copper.

[0004] As a new wiring material to replace copper, ruthenium (Ru) is being studied, whose bulk resistance is not as low as copper but whose average free path of electrons is shorter than copper. Specifically, the bulk resistance of ruthenium is 7.1μΩ·cm, which is higher than the bulk resistance of copper, 1.7μΩ·cm. However, the average free path of electrons in ruthenium is 10.8nm, which is very short compared to the average free path of copper (38.7nm). Therefore, by applying ruthenium, the more miniaturized the wiring is, the smaller the resistance value of the wiring becomes.

[0005] In addition, the melting point of ruthenium is 2334° C., which is higher than the melting point of copper, 1085° C. Therefore, ruthenium is more advantageous than copper in terms of electromigration resistance, and can improve the life of wiring.

[0006] As described above, ruthenium has many advantages as a wiring material. In addition, in order to use ruthenium for wiring, it is necessary to develop a method for forming a ruthenium thin film with low resistivity at low temperature. Here, as a method for manufacturing a ruthenium thin film for wiring or electrodes of such semiconductor devices, a chemical vapor deposition method such as an atomic layer deposition method is known. In addition, as a ruthenium precursor used in the chemical vapor deposition method,

[0007] (precursor), many organic ruthenium compounds have been known in the past.

[0008] As an organic ruthenium compound used as a raw material for chemical vapor deposition, for example, Patent Document 1 discloses bis(ethylcyclopentadienyl)ruthenium(II). In addition, Patent Document 2 discloses dicarbonyl-bis(tetramethylheptanedione)ruthenium and tri(acetylacetonate)ruthenium. In addition, Patent Document 3 and Non-Patent Document 1 disclose (1,3-cyclohexadiene)tricarbonylruthenium, and Patent Document 4 discloses dicarbonyl-bis(5-

[0009] methyl-2,4-hexanedione)ruthenium.

[0010] Prior art literature

[0011] Patent Literature

[0012] Patent Document 1: Japanese Patent Application Publication No. 2000-281694

[0013] Patent Document 2: U.S. Patent No. 6303809

[0014] Patent Document 3: U.S. Patent No. 5962716

[0015] Patent Document 4: Japanese Patent Application Publication No. 2012-006858

[0016] Non-patent literature

[0017] Non-patent document 1: Materials Research Society Symposium B-Materials, Processes, Intergration and Reliability in Advanced Interconnects for

[0018] Micro-and Nanoelectronics,2007,990.0990-B08-01 Summary of the invention

[0019] Problems to be solved by the invention

[0020] The technical problem to be solved by the present invention is to provide a method for forming a ruthenium thin film with low specific resistance at low temperature.

[0021] Solutions to Solve Problems

[0022] In order to solve the above technical problems, in one embodiment of the method for forming a ruthenium thin film according to the present invention, a ruthenium thin film can be formed by using a tricarbonyl group (η 4 -methylene-1,3-propanediyl)ruthenium (Tricarbonyl(η 4A ruthenium precursor represented by (C7H6O3Ru((CO)3Ru-TMM)) is formed by atomic layer deposition (ALD) at a temperature in the range of 200 to 350°C using the above-mentioned ruthenium precursor and reaction gas.

[0023] In some embodiments of the method for forming a ruthenium thin film according to the present invention, the reaction gas may be selected from oxygen (O2), hydrogen (H2), water (H2O) and ammonia.

[0024] One or more of the group consisting of (NH3).

[0025] In some embodiments of the method for forming a ruthenium thin film according to the present invention, the reaction gas is oxygen (O2), and the ruthenium thin film can be formed at a pressure in the range of 0.1 to 10 Torr.

[0026] In some embodiments of the method for forming a ruthenium thin film according to the present invention, the reaction gas is hydrogen (H2), and the ruthenium thin film can be formed at a pressure in the range of 10 to 50 Torr.

[0027] In some embodiments of the method for forming a ruthenium thin film according to the present invention, the resistivity of the ruthenium thin film may be 20 μΩ·cm or less.

[0028] In some embodiments of the method for forming a ruthenium thin film according to the present invention, the method may further include: after the step of forming the ruthenium thin film, heat treating the ruthenium thin film.

[0029] In some embodiments of the method for forming a ruthenium thin film according to the present invention, the heat treatment step may be performed at a temperature of 500° C. or lower.

[0030] In some embodiments of the method for forming a ruthenium thin film according to the present invention, the resistivity of the ruthenium thin film after the heat treatment may be 10 μΩ·cm or less.

[0031] Effects of the Invention

[0032] According to the present invention, when using a tricarbonyl group (η 4 -methylene-1,3-propanediyl)ruthenium (Tricarbonyl(η 4-methylene-1,3-propanediyl)Ruthenium: When a ruthenium precursor represented by C7H6O3Ru((CO)3Ru-TMM)) is used to form a ruthenium film by the ALD method, a very low ruthenium film with a specific resistivity of 20μΩ·cm can be formed even at a low temperature below 350°C. In addition, in the ruthenium film formation method involved in the present invention, the incubation time is short, the growth rate is very high, and the productivity is high. However, these effects are exemplary, and the effects described above do not limit the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] [ Figure 1 ] is a schematic diagram showing the use of tricarbonyl (η 4 -methylene-1,3-propanediyl)ruthenium (Tricarbonyl(η 4 A flowchart of an implementation process of a method for forming a ruthenium thin film using a ruthenium precursor represented by C7H6O3Ru((CO)3Ru-TMM)).

[0034] [ Figure 2 ] is a diagram simply showing the gas injection process of the atomic layer evaporation method for illustrating an embodiment of the method for forming a ruthenium thin film according to the present invention.

[0035] [ Figure 3 ] is a graph showing the growth rate of the ruthenium thin film corresponding to the supply time of the ruthenium precursor in the ruthenium thin film formation method using the atomic layer evaporation method involved in the present invention.

[0036] [ Figure 4 ] is a graph showing the growth rate of the ruthenium thin film corresponding to the supply time of oxygen as a reaction gas in the ruthenium thin film forming method using the atomic layer evaporation method involved in the present invention.

[0037] [ Figure 5 ] is a graph showing the film thickness according to the number of cycles in the ruthenium thin film forming method using the atomic layer evaporation method involved in the present invention.

[0038] [ Figure 6 ] is a graph showing the growth rate of the ruthenium thin film according to the evaporation temperature in the ruthenium thin film formation method using the atomic layer evaporation method involved in the present invention.

[0039] [ Figure 7 ] is a graph showing the resistivity of the ruthenium thin film according to the evaporation temperature in the ruthenium thin film forming method using the atomic layer evaporation method involved in the present invention.

[0040] [ Figure 8] is a diagram showing the results of X-ray diffraction analysis (XRD) of a ruthenium thin film according to the evaporation temperature in the ruthenium thin film forming method utilizing the atomic layer evaporation method according to the present invention.

[0041] [ Fig. 9 ] is a graph showing the resistivity of the ruthenium thin film according to the heat treatment temperature in the ruthenium thin film forming method involving the present invention.

[0042] [ Fig.10 ] is a diagram showing the XRD results of the ruthenium thin film according to the heat treatment temperature in the ruthenium thin film formation method involved in the present invention. DETAILED DESCRIPTION

[0043] Hereinafter, with reference to the accompanying drawings, embodiments of the present invention are described in detail. The embodiments of the present invention are provided to further fully describe the present invention to those having ordinary knowledge in the technical field. The following embodiments may be transformed into other modes, and the scope of the present invention is not limited to the following embodiments. On the contrary, these embodiments are provided to further enrich and improve the present disclosure and fully convey the idea of ​​the present invention to those skilled in the art.

[0044] In addition, in the accompanying drawings, for example, variations in the shapes illustrated may be expected based on manufacturing techniques and / or tolerances. Therefore, embodiments of the present invention should not be construed as limited to the specific shapes of the regions shown in this specification, but should include variations in shape caused, for example, by manufacturing. The same symbol always represents the same element. In addition, the various elements and regions in the accompanying drawings are schematically depicted. Therefore, the present invention is not limited by the relative sizes or spacings depicted in the accompanying drawings.

[0045] The present invention relates to the use of tricarbonyl (η 4 -methylene-1,3-propanediyl)ruthenium (Tricarbonyl(η 4 -methylene-1,3-propanediyl)Ruthenium: A method for forming a ruthenium thin film using a ruthenium precursor represented by C7H6O3Ru((CO)3Ru-TMM)), wherein the ruthenium thin film is formed by using the ruthenium precursor and a reaction gas through an atomic layer evaporation method. When the ruthenium thin film is formed using the ruthenium precursor and the reaction gas, a ruthenium thin film having a resistivity of less than 20μΩ·cm can be evaporated at a low temperature of less than 350°C. The ruthenium precursor has a structure represented by the following chemical formula 1.

[0046] [Chemical formula 1]

[0047]

[0048] Atomic layer evaporation is a method of alternately supplying a precursor and a reaction gas to a substrate to form a thin film. After the supply of the precursor and the supply of the reaction gas, a purge gas is supplied respectively to purge the precursor and the reaction gas remaining in the chamber. When the precursor is supplied to the substrate, the substrate reacts with the precursor to form a precursor layer on the entire substrate surface. When a layer of precursor layer is formed on the entire substrate surface, even if the precursor is subsequently continued to be supplied, the additionally supplied precursor will accumulate on the layer of precursor layer. The accumulated precursor is removed by the purge gas supplied after the precursor is supplied. In the case of supplying the reaction gas, the thin film is also formed by the same mechanism. That is, when the reaction gas is supplied to the precursor formed on the entire substrate surface, the reaction gas reacts with the precursor, and when all the reactions are completed, no further reaction occurs even if the reaction gas is continued to be supplied. Then, the remaining reaction gas is removed by the purge gas supplied after the reaction gas is supplied.

[0049] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0050] [Method of forming a ruthenium thin film by atomic layer deposition]

[0051] Figure 1 To schematically illustrate the use of tricarbonyl (η 4 -methylene-1,3-propanediyl)ruthenium (Tricarbonyl(η 4 A flowchart of an implementation process of a method for forming a ruthenium thin film using a ruthenium precursor represented by C7H6O3Ru((CO)3Ru-TMM)). Figure 2 This is a diagram simply showing a gas injection process of an atomic layer deposition method for explaining one embodiment of a ruthenium thin film formation method according to the present invention.

[0052] Reference Figure 1 and Figure 2 In a method for forming a ruthenium thin film according to one embodiment of the present invention, first, a tricarbonyl group (η 4 -methylene-1,3-propanediyl)ruthenium (Tricarbonyl(η 4 A ruthenium precursor represented by C7H6O3Ru((CO)3Ru-TMM)) is supplied onto the substrate (S110).

[0053] It should be noted that, when the reaction gas supplied in the later-described S130 stage is oxygen, it is preferred that the pressure of each chamber is adjusted to a range of 0.1 to 10 Torr before the stage of supplying the above-mentioned ruthenium precursor to the substrate. In addition, when the reaction gas supplied in the later-described S130 stage is hydrogen, it is preferred that the pressure of each chamber is adjusted to a range of 10 to 50 Torr before the stage of supplying the above-mentioned ruthenium precursor to the substrate. In order to adjust the pressure in the chamber, an inert gas may be further supplied into the chamber. In this case, the inert gas may use the same gas as the purge gas supplied in the S120 stage or the S140 stage, but is not limited thereto.

[0054] In addition, the temperature of the substrate is preferably adjusted to 200 to 350° C. In addition, if necessary, a pre-cleaning process may be performed before step S110 to remove etching residues or surface impurities that may exist on the substrate. The pre-cleaning process may utilize cleaning using argon (Ar) sputtering or a cleaning process using a wet cleaning agent.

[0055] After the ruthenium precursor is supplied to the substrate, the ruthenium precursor is purged (S120). The purge gas is preferably argon (Ar), helium (He) or nitrogen (N2) gas. The residual by-products and the unadsorbed ruthenium precursor are removed by the purge gas.

[0056] Next, a reaction gas is supplied to the substrate (S130). The reaction gas is a reducing gas for reducing the ruthenium precursor adsorbed on the substrate. The reaction gas is preferably selected from one or more of the group consisting of oxygen (O2), hydrogen (H2), water (H2O) and ammonia (NH3). In particular, when oxygen or hydrogen is used, the properties of the formed ruthenium film are excellent, so they are preferred.

[0057] After the reaction gas is supplied onto the substrate, the reaction gas is purged (S140). The purge gas is preferably argon (Ar), helium (He), or nitrogen (N2) gas.

[0058] The above steps S110 to S140 are performed one by one in the above order, and they form an evaporation cycle. The evaporation cycle can be repeated multiple times according to the target thickness of the ruthenium thin film.

[0059] Then, when a ruthenium film of a target thickness is formed (S150), it is preferred to include a step of heat treating the ruthenium film (S160). The step of heat treating the ruthenium film (S160) can be performed at a temperature below 500°C in a hydrogen (H2) atmosphere for about 10 minutes.

[0060] [Results of Formation of Ruthenium Thin Film According to the Present Embodiment]

[0061] Next, refer to Figures 3 to 10 The present invention will be described centering on the formation results of a ruthenium thin film according to one embodiment of the present invention.

[0062] Figure 3 This is a graph showing the growth rate of the ruthenium thin film corresponding to the supply time of the ruthenium precursor in the ruthenium thin film formation method using the atomic layer evaporation method according to the present invention. Figure 4 This is a diagram showing the growth rate of a ruthenium thin film corresponding to the gas supply time of the reaction gas in the ruthenium thin film forming method using the atomic layer evaporation method according to the present invention. At this time, the ruthenium precursor is a ruthenium precursor having the structure of the above chemical formula 1, the reaction gas is oxygen, and the carrier gas and the purge gas use nitrogen. In addition, the substrate temperature is maintained at 220°C and the chamber pressure is 1 Torr. The purge gas is supplied for 10 seconds.

[0063] Reference Figure 3 and Figure 4 , during the period from the supply time of the ruthenium precursor to the supply time of the reaction gas to 10 seconds, as each supply time increases, the growth rate of the ruthenium film increases. And, when the supply time of the ruthenium precursor and the supply time of the reaction gas are more than 10 seconds, no increase in the growth rate of the ruthenium film is observed. This means that the saturation time of the reaction step of the ruthenium precursor and the reaction gas is 10 seconds. Therefore, in order to suppress the waste of the ruthenium precursor and the reaction gas and shorten the process time, it is preferred to supply the ruthenium precursor and the reaction gas for 10 seconds.

[0064] Figure 5 A diagram showing the relationship between the number of evaporation cycles and the film thickness in the ruthenium film forming method using the atomic layer evaporation method according to the present invention. At this time, the ruthenium precursor is a ruthenium precursor having the structure of the above chemical formula 1, the reaction gas is oxygen, and the carrier gas and the purge gas use nitrogen. In addition, the substrate temperature is maintained at 220°C, and the chamber pressure is set to 1 Torr. Then, the ruthenium precursor, the reaction gas, and the purge gas are supplied for 10 seconds respectively.

[0065] Reference Figure 5 It can be seen that the evaporation thickness of the ruthenium film is constant at about 0.17nm in each evaporation cycle (S110-S140). This shows the typical form of the atomic layer evaporation method. In addition, the incubation cycle is very small, about 15 times, and it can be seen that the ruthenium precursor having the structure of the above chemical formula 1 is very suitable for the precursor used in the atomic layer evaporation method.

[0066] Figure 6 This is a diagram showing the relationship between the evaporation temperature and the growth rate of the ruthenium thin film in the method for forming a ruthenium thin film using the atomic layer evaporation method according to the present invention. Figure 7This is a diagram showing the relationship between the evaporation temperature and the resistivity of the ruthenium thin film in the ruthenium thin film formation method using the atomic layer evaporation method according to the present invention. At this time, the ruthenium precursor is a ruthenium precursor having the structure of the above chemical formula 1, the reaction gas is oxygen, and the carrier gas and the purge gas use nitrogen. In addition, the chamber pressure is set to 1 Torr. Then, the ruthenium precursor, the reaction gas, and the purge gas are respectively supplied for 10 seconds. Referring to these Figure 6 and Figure 7 It can be seen that when the evaporation temperature increases, the growth rate of the ruthenium thin film increases, but the specific resistance of the formed ruthenium thin film decreases.

[0067] When the relationship between evaporation temperature and growth rate is observed in detail ( Figure 6 ), when the evaporation temperature is above 200℃, the growth rate is / cycle or more, showing a very high growth rate. In particular, when the evaporation temperature is set above 220°C, the growth rate is about / cycle or more, showing a very high growth rate. The ruthenium precursor having the structure of the above chemical formula 1 does not undergo thermal decomposition below 260°C, so even if it does not undergo thermal decomposition, it shows a very high growth rate at a vapor deposition temperature of 260°C. / cycle very high growth rate. It can be seen that the ruthenium precursor having the structure of the above chemical formula 1 is a very excellent precursor in the evaporation of ruthenium thin films.

[0068] Then, when the relationship between the evaporation temperature and the specific resistance of the ruthenium thin film is observed in detail ( Figure 7 ), when the evaporation temperature is 180°C, it shows a high resistivity of about 50μΩ·cm, but when the evaporation temperature is above 200°C, it shows a very low resistivity of less than 20μΩ·cm. In particular, when the evaporation temperature is 260°C, it shows a very low resistivity of 12.9μΩ·cm. It can be seen that when the ruthenium precursor having the structure of the above chemical formula 1 is used, a ruthenium thin film with a very low resistivity value can be formed.

[0069] Figure 8 The graph shows the results of X-ray diffraction analysis (XRD) of a ruthenium thin film when the deposition temperature is changed in the method for forming a ruthenium thin film using the atomic layer deposition method according to the present invention.

[0070] Reference Figure 8 It can be seen that the peak of ruthenium oxide (RuO2) does not appear, and the peak of metal ruthenium increases significantly by setting the evaporation temperature to 200°C or above.

[0071] Fig. 9 This is a graph showing the relationship between the heat treatment temperature after vapor deposition and the specific resistance of the ruthenium thin film in the ruthenium thin film formation method according to the present invention. Fig.10This is a diagram showing the XRD results of a ruthenium thin film when the post-evaporation heat treatment temperature is changed in the ruthenium thin film forming method of the present invention. The ruthenium thin film just after evaporation (as-dep) is formed at a temperature of 220°C using a ruthenium precursor having a structure of the above chemical formula 1 and oxygen. Then, the post-evaporation heat treatment is performed in a hydrogen atmosphere for 10 minutes.

[0072] Reference Fig. 9 and Fig.10 It can be seen that as the heat treatment temperature increases, the resistivity of the ruthenium film decreases and the peak value of metallic ruthenium increases. When the change in the resistivity of the ruthenium film caused by the heat treatment temperature is observed in more detail, it can be seen that as the heat treatment temperature increases to 500°C, the resistivity of the ruthenium film decreases, but it slightly increases at a heat treatment temperature of 600°C. Therefore, it can be said that the heat treatment after evaporation is preferably performed at a heat treatment temperature below 500°C. It can be seen that the resistivity of the ruthenium film after the 500°C heat treatment is about 9.8μΩ·cm, which is less than 10μΩ·cm, and an excellent ruthenium film with a volume resistivity of ruthenium that is almost close to (7.1μΩ·cm) can be formed. That is, it can be said that when a ruthenium film is formed using the method of the present invention, a ruthenium film with very excellent resistivity characteristics can be obtained even if a low-temperature film forming process is applied.

[0073] The embodiments of the present invention have been illustrated and described above, but the present invention is not limited to the above-mentioned specific embodiments. Without departing from the gist of the present invention as claimed in the claims, it is natural that anyone with common knowledge in the technical field to which the present invention belongs can carry out various modified implementations, and such changes are also within the scope of the claims.

[0074] The scope of the present invention is indicated by the following claims rather than the above description of the invention, and it must be interpreted that all changes or modifications derived from the meaning and scope of the claims and their equivalents are included in the scope of the present invention.

[0075] Industrial Applicability

[0076] As described above, the present invention is to use a tricarbonyl group (η 4 -methylene-1,3-propanediyl)ruthenium (Tricarbonyl(η 4-methylene-1,3-propanediyl)Ruthenium:C7H6O3Ru((CO)3Ru-TMM)) is used as a ruthenium precursor and a method of forming a ruthenium thin film by atomic layer deposition. According to the present invention, a high-quality ruthenium thin film with low specific resistance can be effectively formed. In addition, the method for forming a ruthenium thin film of the present invention can also cope with low-temperature film formation. The present invention is useful for the wiring formation of semiconductor devices that require further miniaturization in the future, and can contribute to the miniaturization / high performance of various semiconductor devices.

Claims

1. A method for forming a ruthenium thin film, which is a method for forming a ruthenium thin film using a ruthenium precursor, characterized in that it comprises the following steps: A tricarbonyl group (η 4 -methylene-1,3-propanediyl)ruthenium (Tricarbonyl(η 4 -methylene-1,3-propanediyl)Ruthenium((CO)3Ru-TMM)) as the ruthenium precursor, The ruthenium precursor and the reaction gas are used to form a ruthenium thin film at a temperature in the range of 200 to 350° C. by atomic layer evaporation. [Chemical formula 1] 2. The method for forming a ruthenium thin film according to claim 1, wherein: The reaction gas is composed of one or more selected from the group consisting of oxygen (O 2 ), hydrogen (H 2 ), water (H 2 O) and ammonia (NH 3 ).

3. The method for forming a ruthenium thin film according to claim 2, wherein: The reaction gas is oxygen (O2), and the ruthenium film is formed at a pressure in the range of 0.1 to 10 Torr.

4. The method for forming a ruthenium thin film according to claim 2, wherein: The reaction gas is hydrogen (H2), and the ruthenium film is formed at a pressure in the range of 10 to 50 Torr.

5. The method for forming a ruthenium thin film according to any one of claims 1 to 4, wherein: The specific resistance of the ruthenium thin film is less than 20 μΩ·cm.

6. The method for forming a ruthenium thin film according to any one of claims 1 to 5, further comprising: After the step of forming the ruthenium thin film, a step of heat treating the ruthenium thin film is performed.

7. The method for forming a ruthenium thin film according to claim 6, wherein: The heat treatment stage is carried out at a temperature below 500°C.

8. The method for forming a ruthenium thin film according to claim 6 or claim 7, wherein: The specific resistance of the ruthenium thin film formed in the heat treatment stage is 10 μΩ·cm or less.

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