Method for atomic layer deposition of Ru-containing film

Abstract

The invention belongs to the technical field of material deposition, and particularly relates to a method for atomic layer deposition of a Ru-containing film. Firstly, a seed layer deposition cycle is executed, a required seed layer is formed on a substrate, then a conventional deposition cycle is executed, and a Ru-containing layer grows; the seed layer deposition cycle comprises a first Ru precursor pulse, a first co-reactant pulse and a purge pulse which are carried out in sequence, and the first Ru precursor pulse and the first co-reactant pulse coincide for a set time; the conventional deposition cycle includes a second Ru precursor pulse, a precursor pulse purge, a second co-reactant pulse, and a co-reactant pulse purge performed sequentially and independently. The present application improves a deposition method of a seed layer in ALD deposition. Nucleation delay is reduced through overlapped pulses, meanwhile, CVD-like gas phase reaction is avoided through optimization of reaction conditions, and the dual effects of shortening the incubation period and reducing roughness are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of material deposition, and in particular relates to a method for atomic layer deposition of a Ru-containing thin film. Background Art

[0002] Ruthenium (Ru) is a noble metal with excellent thermal and chemical stability, low resistivity (~7.1 μΩ·cm), high work function (4.7 eV), low solid solubility in copper (Cu), and strong adhesion to Cu. Due to these favorable physical, chemical, and electrical properties, Ru thin films have attracted widespread attention for a range of applications in semiconductor devices, such as electrodes for capacitors in dynamic random access memory (DRAM), transistor gates, and seed layers for copper electroplating.

[0003] As the demand for shrinking chip sizes increases, the requirements for growing ruthenium films (including those containing ruthenium) are also increasing. Such applications require deposition technologies with high process controllability, capable of depositing ultra-thin films while maintaining uniformity over large areas. Atomic layer deposition (ALD) is a well-suited solution for these applications. Because ALD utilizes a self-limiting growth mode driven by surface saturation reactions, it achieves atomic-level thickness control, resulting in excellent film quality and high thickness consistency.

[0004] However, the Ru ALD process usually experiences a relatively long incubation period in the initial stage of film deposition, which is related to the delayed nucleation of the film material on the growth surface, that is, no reactants are deposited during the initial growth period.

[0005] Existing studies have reported that using divalent Ru(EtCp)2 and O2 as precursors and second reactants to grow Ru on a tantalum nitride (TaN) substrate requires 100 incubation cycles (SJ. Park, Microelectron Eng. 85 (2008) 39); using trivalent Ru(thd)3 and O2 as precursors and second reactants to grow Ru on an Al2O3 substrate requires 250 incubation cycles (T. Aaltonen. Chem. Vap. Depsition 10 (2004) 217); using zero-valent EBBDRu and O2 as precursors and second reactants, with a P-type Si(100) wafer coated with 100nm thick thermally grown SiO2 as the substrate, Ru film growth requires 15 incubation cycles (S. Yeo. Microelectronic Engineering 137 (2015) 19). Longer incubation cycles not only affect the deposition time, but also lead to greater film roughness and increased resistivity, especially when the film thickness is required to be thin.

[0006] Therefore, providing a method for atomic layer deposition of Ru that can improve the nucleation delay phenomenon in the early stage of Ru growth is a technical problem that still needs to be solved. Summary of the Invention

[0007] In order to solve the above technical problems, the present invention provides a method for atomic layer deposition of Ru-containing thin films.

[0008] The technical solution adopted in the present invention is as follows: A method for atomic layer deposition of a Ru-containing thin film comprises first performing a seed layer deposition cycle, forming a desired seed layer on a substrate, and then performing a conventional deposition cycle to grow a Ru-containing layer; the seed layer deposition cycle comprises a first Ru precursor pulse, a first co-reactant pulse, and a purge pulse performed in sequence, wherein the first Ru precursor pulse and the first co-reactant pulse have a set time overlap; the conventional deposition cycle comprises a second Ru precursor pulse, a precursor pulse purge, a second co-reactant pulse, and a co-reactant pulse purge performed in sequence and independently.

[0009] Preferably, the reaction chamber pressure is 0.1-10 Torr.

[0010] Preferably, in the seed layer deposition cycle, the single first Ru precursor pulse time is 2-5 s, the single first co-reactant pulse time is 2-5 s, and the set time overlaps by at least 1 s, preferably 2-5 s.

[0011] Preferably, in the seed layer deposition cycle, the flow rate of the first co-reactant into the reaction chamber is 50~300sccm, more preferably 80~200sccm; the carrier gas carries the first Ru precursor into the reaction chamber, and the carrier gas flow rate is 20~200sccm, more preferably 40~100sccm.

[0012] Preferably, the seed layer has a thickness of 1 to 10 nm, more preferably 2 to 5 mm.

[0013] Preferably, the first Ru precursor and the second Ru precursor are selected from 0-valent ethylbenzene (1-ethyl-1,4-cyclohexadiene) ruthenium (EBECHRu), (1-methyl-1,4-cyclohexadiene) tricarbonyl ruthenium, (2,3-dimethyl-1,3-butadiene) tricarbonyl ruthenium (Ru(DMBD)(CO)3), divalent bis (ethylcyclopentadienyl) ruthenium (Ru(EtCp)2), bis (2,4-dimethyl 2, bis(2,4-dimethylpentadienyl)ruthenium (Ru(DMPD)2), bis(cyclopentadienyl)ruthenium (Ru(Cp)2), trivalent tri(2,2,6,6-tetramethyl-3,5-heptanedione)ruthenium (Ru(thd)3 / Ru(tmhd)3), triacetylacetonate ruthenium (Ru(acac)3); more preferably ethylbenzene(1-ethyl-1,4-cyclohexadiene)ruthenium, bis(2,4-dimethylpentadienyl)ruthenium, bis(ethylcyclopentadienyl)ruthenium.

[0014] Preferably, the first co-reactant and the second co-reactant are selected from O2, NH3, H2, t BuNH2, N2H4, SiH4, Si2H6, B2H4; more preferably O2.

[0015] Based on the above-mentioned Ru precursors and co-reactants, the Ru-containing films prepared in this application include but are not limited to Ru single-element films, RuO2 films, RuN or Ru-doped nitrogen-containing films, RuSi alloys or S-doped Ru films, RuB alloys or B-doped Ru films.

[0016] Preferably, in the conventional deposition cycle, the time of a single second Ru precursor pulse is 2 to 10 s, and the time of a single second co-reactant pulse is 5 to 20 s.

[0017] Preferably, in the conventional deposition cycle, the flow rate of the second co-reactant into the reaction chamber is 100-500 sccm; the carrier gas carrying the second Ru precursor into the reaction chamber has a carrier gas flow rate of 40-150 sccm.

[0018] Preferably, the deposition temperature of the seed layer deposition cycle is 185-300°C, and the deposition temperature of the conventional deposition cycle is 150-300°C.

[0019] The substrate includes semiconductor material, dielectric material or metal material; the semiconductor material includes any one or more of Si and Ge, the dielectric material includes any one or more of SiO2, HfO2, ZrO2, La2O3, Al2O3, and the metal material includes any one or more of Ti, Al, Ni, Co, TiN, and TaN; the substrate material is more preferably Si, SiO2, TiN, and TaN.

[0020] Preferably, the substrate is a planar substrate or a high aspect ratio (HAR) substrate.

[0021] Preferably, the method comprises the following steps: S1. Place the substrate in the reaction chamber, evacuate the chamber, and adjust the reaction chamber to the set temperature and pressure; S2. Grow a seed layer, selecting any of the following options: A) Adjust the flow rate, carry the first Ru precursor and the first co-reactant into the reaction chamber simultaneously through the carrier gas, and perform pulse purge after the set pulse time m1; repeat the operation until the desired seed layer is obtained; B) Adjust the flow rate, carry the first Ru precursor into the reaction chamber through the carrier gas, introduce the first co-reactant after the set pulse time m2, and then perform pulse purge after the set pulse time m3; repeat the operation until the desired seed layer is obtained; S3. Growing a Ru-containing film: Adjust the flow rate, carry the second Ru precursor into the reaction chamber via the carrier gas, perform pulse purge after a set pulse time n1, then introduce the second co-reactant, and perform pulse purge after a set pulse time n2; repeat the operation until the desired Ru-containing film is obtained.

[0022] Preferably, in the scheme B, the total pulse time of the first Ru precursor is m4, the set pulse time m1, the set pulse time m3 and the total pulse time m4 are 2~5s, the set pulse time m2 is 0~5s but not 0, and m2<m4; the set pulse time n1 is 2~10s, the set pulse time n2 is 5~30s, and the pulse purge time is 8~20s.

[0023] The beneficial effects of the present invention are: The deposition method of the seed layer in ALD (atomic layer deposition) deposition has been improved. During the seed layer deposition process, the nucleation delay problem is significantly reduced by setting the first precursor and the first co-reactant to have overlapping pulses. In the present application, this pulsed method in which the precursor and the co-reactant coexist is similar to CVD (chemical vapor deposition) deposition. It is generally believed in the art that CVD deposition is not conducive to controlling the roughness of the film due to problems such as non-self-limiting growth and side reactions. Therefore, in the preparation of refined films such as Ru, continuous reactions caused by the mixing of precursors and co-reactants are avoided as much as possible. The present application breaks this conventional thinking in the art and reversely introduces the CVD-like technology, which is itself detrimental to the roughness of the film, into the present application. By optimizing the conditions such as the types of seed layer precursors and co-reactants, the pulse overlap time, and the deposition temperature, the occurrence of CVD-like gas phase reactions is avoided, which shortens the incubation period and achieves the dual effect of reducing roughness. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the method for growing a seed layer in this application, wherein Figure (a) corresponds to Scheme A, and Figure (b) corresponds to Scheme B; Figure 2 Schematic diagram of the method for growing Ru thin films in this application.

[0025] Figure 3 TEM morphology images of the Ru seed layer formed after 40 cycles and the ruthenium-containing film formed after 100 cycles in Example 1; Figure 4 This is a TEM morphology image of the ruthenium film formed after 150 cycles in Comparative Example 2. DETAILED DESCRIPTION

[0026] Unless otherwise specified, the terms used herein have the meanings commonly understood by those skilled in the art.

[0027] The technical solution of the present invention is described in more detail below with reference to the embodiments: Example 1 See also Figure 1-Figure 2 , a method for atomic layer deposition of Ru-containing thin films, the steps are as follows: S1. After cleaning and drying the Si substrate, place it in the reaction chamber and secure it. After evacuating the chamber, adjust the temperature to 185°C. Heat the Ru(DMPD)2 source bottle to 65°C and connect it to the reaction chamber via the ALD valve and piping. The reaction chamber base pressure is 1 Torr. S2. Growth seed layer: S21. The first Ru precursor Ru(DMPD)2 and the first co-reactant O2 are simultaneously introduced into the reaction chamber by Ar carrier gas, with an Ar flow rate of 100 sccm, an O2 flow rate of 200 sccm, and a pulse time m1 of 2s; S22. Use Ar to purge the lines and chamber for 15 s at an Ar flow rate of 100 sccm. The above steps S21-S22 constitute one deposition cycle, and 40 deposition cycles are repeated to obtain the desired seed layer; S3. Growth of Ru-containing thin film: S31. A second Ru precursor, Ru(DMPD)2, is introduced into the chamber via an Ar carrier gas with an Ar flow rate of 100 sccm and a pulse time n1 of 5 s. S32. Use Ar to purge the pipeline and chamber for 15 s at an Ar flow rate of 100 sccm. S33. The second co-reactant O2 is carried into the chamber by an Ar carrier gas, with an Ar flow rate of 100 sccm, a pulse time n2 of 10s, an O2 flow rate of 200 sccm, and a Ru layer is formed; S34. Use Ar to purge the lines and chamber for 15 s at an Ar flow rate of 100 sccm. The above steps S31 - S34 constitute a deposition cycle, and steps S31 - S34 are repeated until the desired film thickness is reached.

[0028] Example 2 See also Figure 1-Figure 2 , a method for atomic layer deposition of Ru-containing thin films, the steps are as follows: S1. After cleaning and drying the Si substrate, place it in the reaction chamber and secure it. After evacuating the chamber, adjust the temperature to 225°C. Heat the EBECHRu source bottle to 100°C and connect it to the reaction chamber via the ALD valve and piping. The reaction chamber base pressure is 0.5 Torr. S2. Growth seed layer: S21. The first Ru precursor EBECHRu is introduced into the reaction chamber by Ar carrier gas, with a pulse time m4 of 3 s and a pulse time m2 of 1 s. That is, at the end of the first second of EBECHRu introduction, the first co-reactant O2 is introduced into the reaction chamber with an Ar flow rate of 50 sccm, an O2 flow rate of 100 sccm, and a pulse time m3 of 2 s. S22. Use Ar to purge the pipeline and chamber for 10 seconds at an Ar flow rate of 50 sccm. The above steps S21-S22 constitute one deposition cycle, and 40 deposition cycles are repeated to obtain the desired seed layer; S3. Growth of Ru-containing thin film: S31. A second Ru precursor, Ru(DMPD)2, is introduced into the chamber via an Ar carrier gas with an Ar flow rate of 50 sccm and a pulse time n1 of 7 s. S32. Use Ar to purge the pipeline and chamber, purge time 10s, Ar flow rate 50sccm; S33. The second co-reactant O2 is carried into the chamber by an Ar carrier gas, with an Ar flow rate of 50 sccm, a pulse time n2 of 30s, an O2 flow rate of 500 sccm, and a RuOx layer is formed; S34. Use Ar to purge the pipeline and chamber, purge time 10s, Ar flow rate 50sccm; The above steps S31 - S34 constitute a deposition cycle, and steps S31 - S34 are repeated until the desired film thickness is reached.

[0029] Example 3 See also Figure 1-Figure 2 , a method for atomic layer deposition of Ru-containing thin films, the steps are as follows: S1. After cleaning and drying the Si substrate, place it in the reaction chamber and fix it. After evacuating the chamber, adjust the temperature to 230°C. Heat the Ru(EtCp)2 source bottle to 100°C and connect it to the reaction chamber through the ALD valve and pipeline. The reaction chamber base pressure is 0.5 Torr. S2. Growth seed layer: S21. The first Ru precursor, Ru(EtCp)2, was introduced into the reaction chamber via Ar carrier gas with a pulse time m4 of 5 s. The pulse time m2 was set to 2 s. That is, at the end of the second second of Ru(EtCp)2 introduction, the first co-reactant, O2, was introduced into the reaction chamber with an Ar flow rate of 40 sccm, an O2 flow rate of 80 sccm, and a pulse time m3 of 5 s. S22. Use Ar to purge the lines and chamber for 8 s at an Ar flow rate of 40 sccm. The above steps S21-S22 constitute one deposition cycle, and 60 deposition cycles are repeated to obtain the desired seed layer; S3. Growth of Ru-containing thin film: S31. A second Ru precursor Ru(EtCp)2 is introduced into the chamber by Ar carrier gas with an Ar flow rate of 40 sccm and a pulse time n1 of 10 s. S32. Use Ar to purge the pipeline and chamber for 20 seconds at an Ar flow rate of 40 sccm. S33. The second co-reactant O2 is carried into the chamber by an Ar carrier gas, with an Ar flow rate of 50 sccm, a pulse time n2 of 20s, an O2 flow rate of 100 sccm, and a Ru layer is formed; S34. Use Ar to purge the pipeline and chamber, purge time 15s, Ar flow rate 40sccm; The above steps S31 - S34 constitute a deposition cycle, and steps S31 - S34 are repeated until the desired film thickness is reached.

[0030] Comparative Example 1 A method for atomic layer deposition of a Ru-containing thin film is basically the same as that of Example 1, except that there is no seed layer deposition step.

[0031] Comparative Example 2 A method for atomic layer deposition of a Ru-containing thin film is basically the same as Example 1, except that there is no seed layer deposition step, and before depositing the Ru-containing layer, the substrate is treated with 200W NH3 plasma for 5 minutes, and then the substrate surface is treated with 100sccmO3 for 10 minutes.

[0032] Comparative Example 3 A method for atomic layer deposition of a Ru-containing thin film is basically the same as that of Example 3, except that there is no seed layer deposition step.

[0033] Comparative Example 4 A method for atomic layer deposition of a Ru-containing thin film is basically the same as that of Example 1, except that the number of seed layer deposition cycles is adjusted to 100 times.

[0034] Comparative Example 5 A method for atomic layer deposition of a Ru-containing thin film is basically the same as that of Example 1, except that the seed layer is formed by: S21. Ru(DMPD)2 was introduced into the chamber via Ar carrier gas with an Ar flow rate of 100 sccm and a pulse time of 2 s. S22. O2 is introduced into the chamber by Ar carrier gas, with an Ar flow rate of 200 sccm and a pulse time of 2 s; S23. Use Ar to purge the pipeline and chamber for 15 s at an Ar flow rate of 100 sccm. The above steps S21-S23 constitute one deposition cycle, and 40 deposition cycles are repeated to obtain the desired seed layer.

[0035] test 1. Nucleation delay: Use ellipsometer to measure the film thickness at different deposition cycle numbers to determine whether there is a film formation delay in the initial growth.

[0036] 2. Film surface roughness: Atomic force microscopy (AFM) is used to characterize the roughness of the film surface.

[0037] 3. Use transmission electron microscopy (TEM) to measure the film morphology.

[0038] result The film thickness of ruthenium and the corresponding film roughness results of different deposition cycle numbers in the examples and comparative examples are shown in Tables 1 to 3.

[0039] Table 1 Effect of different deposition cycle numbers on ruthenium film thickness in Examples 1-3 ; Table 2 Effect of different deposition cycle numbers on ruthenium film thickness in comparative examples 1-3 ; Table 3 Effect of different deposition cycle numbers on ruthenium film thickness in comparative examples 4-5 ; By comparing Example 1 with Comparative Examples 1 and 2, and Example 3 with Comparative Example 3, it can be seen that after depositing the Ru seed layer, depositing a Ru-containing layer on the ruthenium seed layer can significantly improve the roughness of the film. As shown in the table, the roughness of Example 1 is 3.68Å (film thickness 5.2nm), 5.15Å (film thickness 8.1nm), the roughness of Comparative Example 1 is 8.89Å (film thickness 6.8nm), 9.65Å (film thickness 9.3nm), the roughness of Comparative Example 2 is 7.91Å (film thickness 7.3nm), 9.37Å (film thickness 10.5nm), the roughness of Example 3 is 8.6Å (film thickness 7.3nm), roughness 15.02Å (film thickness 11.2nm), and the roughness of Comparative Example 3 is 9.39Å (film thickness 5.9nm), roughness 19.5Å (film thickness 8.3nm).

[0040] It can also be seen from the test data that the process method of the present application has better initial film-forming characteristics. In Example 1, a Ru layer of 3.1nm can be obtained after 40 deposition cycles of the Ru seed layer. In Comparative Example 1, no measurable film is obtained after 50 ruthenium deposition cycles. In Comparative Example 2, after the substrate is treated with NH3 plasma and O3, the Ru film thickness obtained after 50 deposition cycles is only 1.8nm. In Example 3, a Ru thin film of 4.5nm is finally obtained after 70 deposition cycles of the Ru seed layer. In Comparative Example 3, no film is produced in the first 50 deposition cycles, and only a 2.6nm Ru thin film is produced after 100 deposition cycles.

[0041] Figure 3 TEM morphology images of the Ru seed layer formed after 40 cycles and the ruthenium-containing film formed after 100 cycles in Example 1; Figure 4 This is a TEM image of the ruthenium film formed after 150 cycles in Comparative Example 2. It can be seen that the Ru film grown by the example method has a smooth surface, while the Ru film grown by the comparative example has a relatively rough surface, indicating that the present invention can better control the roughness of the prepared film.

[0042] The above are merely preferred practical examples of the present invention and are not intended to limit the invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for atomic layer deposition of a Ru-containing thin film, characterized in that: First, a seed layer deposition cycle is performed to form a desired seed layer on a substrate, and then a conventional deposition cycle is performed to grow a Ru-containing layer; the seed layer deposition cycle includes a first Ru precursor pulse, a first co-reactant pulse, and a purge pulse performed in sequence, wherein the first Ru precursor pulse and the first co-reactant pulse have a set time overlap; The conventional deposition cycle includes a second Ru precursor pulse, a precursor pulse purge, a second co-reactant pulse, and a co-reactant pulse purge, all performed sequentially and independently.

2. The method for atomic layer deposition of a Ru-containing thin film according to claim 1, wherein: In the seed layer deposition cycle and the conventional deposition cycle, the reaction chamber pressure is 0.1~10Torr; in the seed layer deposition cycle, the single first Ru precursor pulse time is 2~5s, the single first co-reactant pulse time is 2~5s, and the overlap of the set time is at least 1s.

3. The method for atomic layer deposition of a Ru-containing thin film according to claim 1, wherein: During the seed layer deposition cycle, the flow rate of the first co-reactant into the reaction chamber is 50-300 sccm; the carrier gas carrying the first Ru precursor into the reaction chamber has a carrier gas flow rate of 20-200 sccm.

4. The method for atomic layer deposition of a Ru-containing thin film according to claim 1, wherein: The seed layer has a thickness of 1-10 nm.

5. The method for atomic layer deposition of a Ru-containing thin film according to claim 1, wherein: The first Ru precursor and the second Ru precursor are independently selected from any one of ethylbenzene (1-ethyl-1,4-cyclohexadiene) ruthenium, (1-methyl-1,4-cyclohexadiene) tricarbonyl ruthenium, (2,3-dimethyl-1,3-butadiene) tricarbonyl ruthenium, bis (ethylcyclopentadienyl) ruthenium, bis (2,4-dimethylpentadienyl) ruthenium, bis (2,2,6,6-tetramethyl-3,5-heptanedione) ruthenium, and triacetylacetonate ruthenium; the first co-reactant and the second co-reactant are independently selected from any one of O2, NH3, H2, t Any one of BuNH2, N2H4, SiH4, Si2H6, B2H4.

6. The method for atomic layer deposition of a Ru-containing thin film according to claim 1, wherein: In the conventional deposition cycle, the single second Ru precursor pulse time is 2 to 10 seconds, and the single second co-reactant pulse time is 5 to 20 seconds.

7. The method for atomic layer deposition of a Ru-containing thin film according to claim 1, wherein: In the conventional deposition cycle, the flow rate of the second co-reactant into the reaction chamber is 100-500 sccm; the carrier gas carrying the second Ru precursor into the reaction chamber has a carrier gas flow rate of 40-150 sccm.

8. The method for atomic layer deposition of a Ru-containing thin film according to claim 1, wherein: The deposition temperature of the seed layer deposition cycle is 185-300° C., and the deposition temperature of the conventional deposition cycle is 150-300° C.

9. The method for atomic layer deposition of a Ru-containing thin film according to claim 1, wherein: The substrate includes a semiconductor material, a dielectric material or a metal material; the semiconductor material includes any one or more of Si and Ge, the dielectric material includes any one or more of SiO2, HfO2, ZrO2, La2O3, and Al2O3, and the metal material includes any one or more of Ti, Al, Ni, Co, TiN, and TaN.

10. The method for atomic layer deposition of a Ru-containing thin film according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1. Place the substrate in the reaction chamber, evacuate the chamber, and adjust the reaction chamber to the set temperature and pressure; S2. Grow a seed layer, selecting any of the following options: A) Adjust the flow rate, carry the first Ru precursor and the first co-reactant into the reaction chamber simultaneously through the carrier gas, and perform pulse purge after the set pulse time m1; Repeat the operation until the desired seed layer is obtained; B) Adjust the flow rate, carry the first Ru precursor into the reaction chamber through the carrier gas, introduce the first co-reactant after the set pulse time m2, and then perform pulse purge after the set pulse time m3; repeat the operation until the desired seed layer is obtained; S3. Growth of Ru-containing film: Adjust the flow rate, carry the second Ru precursor into the reaction chamber through the carrier gas, pulse purge after the set pulse time n1, and then introduce the second co-reactant, after the set pulse time n2 after the pulse purge; Repeat the operation until the desired Ru-containing film is obtained; In the scheme B, the total pulse time of the first Ru precursor is m4, the set pulse time m1, the set pulse time m3 and the total pulse time m4 are 2~5s, the set pulse time m2 is 0~5s but not 0, and m2<m4; the set pulse time n1 is 2~10s, the set pulse time n2 is 5~30s, and the pulse purge time is 8~20s.

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