Low-resistance TiN thin film, preparation method and application thereof

Abstract

The application belongs to the technical field of semiconductors and relates to a low-resistance TiN film and a preparation method and application thereof, and the preparation method at least comprises the following steps: TiCl4 and NH3 are used as precursors, a TiN film is prepared through atomic layer deposition, and the obtained TiN film is treated with SiH4 during the deposition process; wherein the resistance of the TiN film is less than or equal to 305 ohms / square. In the deposition process of the TiN film, a strong reducing gas SiH4 is introduced to selectively reduce the adsorbed oxygen and weakly combined oxygen on the surface of the TiN, so as to reduce the oxygen doping concentration, significantly reduce the film resistance, and fundamentally inhibit the high-resistance problem caused by oxygen doping and lattice defects.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor technology, and relates to a TiN thin film, and more particularly to a low-resistivity TiN thin film, its preparation method and application. Background Technology

[0002] In advanced semiconductor manufacturing processes, the material properties and process compatibility of functional thin films directly determine the electrical performance, thermal stability, and long-term reliability of devices. Titanium nitride (TiN), with its excellent metallic conductivity, high-temperature thermal stability, strong metal diffusion barrier capability, good etching selectivity, and semiconductor process compatibility, has become a key material for device structures such as metal interconnect structures, gate electrodes, diffusion barrier layers, and high aspect ratio MIM (metal-insulator-metal) capacitor electrodes. It is an indispensable functional thin film in the manufacturing processes of semiconductor products such as flash memory and logic chips.

[0003] With the increasing 3D integration of devices and the continuous increase in aspect ratio, traditional physical vapor deposition (PVD) TiN cannot meet the requirements of high aspect ratio structures due to inherent defects such as poor step coverage, insufficient film uniformity, and low sidewall coverage. Atomic layer deposition (ALD) technology, through self-limiting surface chemical reactions, can achieve controllable growth with single-atom-layer precision and film step coverage close to 100%, perfectly adapting to the electrode fabrication requirements of high aspect ratio MIM structures. Therefore, ALD TiN has become an irreplaceable process step in the fabrication of such devices.

[0004] Currently, the ALD TiN process widely used in industrial mass production generally employs titanium tetrachloride (TiCl4) and ammonia (NH3) as reaction precursors. This precursor offers advantages such as low raw material cost, strong compatibility with chamber equipment, high process maturity, and a reaction temperature window adapted to standard semiconductor processes, making it the most widely used ALD TiN preparation method in global semiconductor production lines. However, this process system has inherent technical defects. Influenced by multiple factors such as the precursor reaction path, surface adsorption characteristics, lattice growth kinetics, and chamber environment, it is difficult to achieve ideal stoichiometry and a complete lattice structure in the deposited TiN film.

[0005] The reason for this is that during the ALD reaction of TiCl4 and NH3, chlorine impurities easily remain inside the film. Simultaneously, trace oxygen impurities in the cavity are incorporated into the TiN lattice in the form of adsorbed oxygen, interstitial oxygen, and weakly bound oxygen, forming oxygen doping defects. Furthermore, structural defects such as nitrogen vacancies and lattice distortion generated during the reaction further damage the metallic bonding properties of TiN, reducing carrier mobility and concentration. These defects collectively result in an ALD TiN film prepared by conventional processes having a bulk resistivity greater than 250 μΩ·cm, with a sheet resistance level far exceeding the requirements for advanced device applications.

[0006] In high aspect ratio MIM structures and interconnect systems, the high resistance of TiN electrodes can cause a series of serious device performance problems: First, the RC delay increases significantly, directly reducing the device signal transmission speed and limiting the improvement of chip operating frequency; second, a large amount of Joule heat accumulates when the thin film is conducting, resulting in severe device heating and a decrease in thermal stability and anti-aging ability; third, the uneven electric field distribution caused by high resistance increases leakage current, reduces device breakdown voltage, and significantly degrades device reliability and process yield.

[0007] Currently, the industry lacks an effective solution that balances the conformal deposition characteristics of ALD, precursor process compatibility, and low-resistivity requirements. Simply optimizing ALD cycling parameters, chamber pressure, or deposition temperature is insufficient to fundamentally suppress the high-resistivity issues caused by oxygen doping and lattice defects. Therefore, how to avoid excessively high resistance in ALD TiN films without altering the mainstream TiCl4-NH3 precursor system and without compromising the high aspect ratio filling advantage of the ALD process has become a pressing technical challenge in the fabrication of advanced semiconductor MIM structures and related devices. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention aims to provide a low-resistivity TiN thin film, its preparation method, and its application, thereby solving the problem of excessively high resistance in ALD TiN thin films without altering the mainstream TiCl4-NH3 precursor system or compromising the high aspect ratio filling advantage of the ALD process.

[0009] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing a low-resistivity TiN thin film, comprising at least: using TiCl4 and NH3 as precursors, preparing a TiN thin film by atomic layer deposition, and simultaneously treating the obtained TiN thin film with SiH4 during the deposition process.

[0010] The resistance of the TiN thin film is ≤305Ω / □.

[0011] This invention introduces a strong reducing gas, SiH4, during the deposition of TiN thin films. By increasing the content of highly active Si species and utilizing the thermodynamic stability of Si-O bonds, it selectively reduces adsorbed and weakly bound oxygen on the TiN surface, thereby reducing the oxygen doping concentration and significantly lowering the film resistance. This fundamentally suppresses the high resistance problem caused by oxygen doping and lattice defects, requiring no additional equipment and adapting to the filling requirements of high aspect ratio MIM structures.

[0012] Preferably, TiCl4 and NH3 are used as precursors, and the resulting TiN film is subjected to SiH4 treatment once every 25 growth cycles.

[0013] Preferably, the SiH4 treatment temperature is 300~450℃.

[0014] Preferably, the SiH4 treatment time is 20~40s.

[0015] Preferably, during the SiH4 treatment process, the SiH4 flow rate is 30~100 sccm.

[0016] Preferably, in each growth cycle, the influent flow rate of TiCl4 is 200~500 sccm, and the influent flow rate of NH3 is 200~500 sccm.

[0017] Preferably, the cavity pressure for the atomic layer deposition and the SiH4 treatment is 15~25 torr.

[0018] Preferably, each growth cycle includes sequential NH3 pulse, purging, TiCl4 pulse, and purging.

[0019] Preferably, the duration of the NH3 pulse is 0.2~0.5s.

[0020] Preferably, the duration of the TiCl4 pulse is 0.2~0.5s.

[0021] Preferably, N2 is used as the purging gas.

[0022] In a second aspect, the present invention provides a low-resistivity TiN thin film, which is prepared by the preparation method described in the first aspect.

[0023] Thirdly, the present invention provides a semiconductor device comprising at least a low-resistivity TiN thin film as described in the second aspect.

[0024] Compared with the prior art, the present invention has the following beneficial effects: This invention introduces a strong reducing gas, SiH4, during the deposition of TiN thin films. By increasing the content of highly active Si species and utilizing the thermodynamic stability of Si-O bonds, it selectively reduces adsorbed and weakly bound oxygen on the TiN surface, thereby reducing the oxygen doping concentration and significantly lowering the film resistance. This fundamentally suppresses the high resistance problem caused by oxygen doping and lattice defects, requiring no additional equipment and adapting to the filling requirements of high aspect ratio MIM structures. Detailed Implementation

[0025] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0026] One embodiment of the present invention provides a method for preparing a low-resistivity TiN thin film, which includes at least: using TiCl4 and NH3 as precursors, preparing a TiN thin film by atomic layer deposition, and simultaneously treating the obtained TiN thin film with SiH4 during the deposition process.

[0027] The resistance of the TiN thin film is ≤305Ω / □, for example, it can be 200Ω / □, 210Ω / □, 220Ω / □, 230Ω / □, 240Ω / □, 250Ω / □, 260Ω / □, 270Ω / □, 280Ω / □, 290Ω / □, 300Ω / □ or 305Ω / □, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0028] This invention introduces a strong reducing gas, SiH4, during the deposition of TiN thin films. By increasing the content of highly active Si species and utilizing the thermodynamic stability of Si-O bonds, it selectively reduces adsorbed and weakly bound oxygen on the TiN surface, thereby reducing the oxygen doping concentration and significantly lowering the film resistance. This fundamentally suppresses the high resistance problem caused by oxygen doping and lattice defects, requiring no additional equipment and adapting to the filling requirements of high aspect ratio MIM structures.

[0029] In some embodiments, TiCl4 and NH3 are used as precursors, and the resulting TiN film is subjected to one SiH4 treatment every 25 growth cycles.

[0030] Because TiN continuously adsorbs oxygen impurities during ALD growth, the film thickness is extremely thin (approximately 10 Å) after no more than 25 cycles. During this time, oxygen impurities have not yet diffused deeply into the bulk phase. SiH4 can efficiently extract oxygen from the surface and near-surface layers, thus avoiding the difficulty of removing oxygen from the interior of thick films. Simultaneously, processing in a thin-film state allows for more uniform diffusion, adsorption, and reaction of SiH4 gas on the film surface and within the high aspect ratio structure, effectively preventing inconsistencies in the degree of processing between the inner and outer layers due to thick films and ensuring uniform resistivity across the entire film.

[0031] In some embodiments, the SiH4 treatment temperature is 300~450℃, for example, it can be 300℃, 310℃, 320℃, 330℃, 340℃, 350℃, 360℃, 370℃, 380℃, 390℃, 400℃, 410℃, 420℃, 430℃, 440℃ or 450℃, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0032] The above temperature range can activate SiH4 to generate highly active Si species, thereby stably and efficiently extracting oxygen impurities from TiN, ensuring deoxidation effect without over-reaction. If the processing temperature is below 300℃, the activity of SiH4 is insufficient and the deoxidation effect is poor; if the processing temperature is above 450℃, it is easy to cause TiN lattice damage, film cracking or warping.

[0033] In some embodiments, the SiH4 treatment time is 20 to 40 seconds, for example, 20 seconds, 22 seconds, 24 seconds, 26 seconds, 28 seconds, 30 seconds, 32 seconds, 34 seconds, 36 seconds, 38 seconds or 40 seconds, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0034] In some embodiments, during the SiH4 processing, the SiH4 flow rate is 30~100 sccm, for example, it can be 30 sccm, 40 sccm, 50 sccm, 60 sccm, 70 sccm, 80 sccm, 90 sccm or 100 sccm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0035] In some embodiments, the TiCl4 flow rate in each growth cycle is 200~500 sccm, for example, 200 sccm, 250 sccm, 300 sccm, 350 sccm, 400 sccm, 450 sccm or 500 sccm, and the NH3 flow rate is 200~500 sccm, for example, 200 sccm, 250 sccm, 300 sccm, 350 sccm, 400 sccm, 450 sccm or 500 sccm, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0036] In some embodiments, the cavity pressure for the atomic layer deposition and the SiH4 treatment is 15 to 25 torr, for example, 15 torr, 16 torr, 17 torr, 18 torr, 19 torr, 20 torr, 21 torr, 22 torr, 23 torr, 24 torr or 25 torr, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0037] In some embodiments, each growth cycle includes sequential NH3 pulse, purge, TiCl4 pulse, purge.

[0038] In some embodiments, the duration of the NH3 pulse is 0.2 to 0.5 s, for example, 0.2 s, 0.3 s, 0.4 s or 0.5 s, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0039] In some embodiments, the duration of the TiCl4 pulse is 0.2 to 0.5 s, for example, 0.2 s, 0.3 s, 0.4 s or 0.5 s, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0040] In some embodiments, N2 is used as the purging gas.

[0041] One embodiment of the present invention also provides a low-resistivity TiN thin film, which is prepared by the preparation method described in any of the above embodiments.

[0042] One embodiment of the present invention also provides a semiconductor device comprising at least the low-resistivity TiN thin film described in any of the above embodiments.

[0043] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0044] Example 1 This embodiment provides a low-resistivity TiN thin film and its preparation method, the preparation method including the following steps: (1) After the surface of the semiconductor substrate with the high aspect ratio MIM structure is cleaned by standard cleaning to remove particles and organic contaminants, it is transferred into the process chamber of the ALD equipment; (2) Evacuate the cavity to the basic pressure, then introduce N2 to replace the air, heat to 300°C, and stabilize the cavity pressure at 20±5 torr; (3) Introduce TiCl4 precursor (flow rate 200 sccm), pulse duration 0.5 s; after the pulse ends, stop introducing TiCl4 and simultaneously introduce N2 to purge the cavity; (4) Introduce NH3 precursor (flow rate 200 sccm), pulse duration 0.5 s; after the pulse ends, stop introducing NH3 and simultaneously introduce N2 to purge the cavity; (5) After repeating steps (3) to (4) for a total of 25 cycles (corresponding to a TiN thin layer of about 10 Å thickness), SiH4 (flow rate 30 sccm) is introduced and the treatment time is 40 s; after the treatment is completed, the introduction of SiH4 is stopped and N2 is introduced to purge the cavity. (6) Repeat steps (3) to (5) until the TiN film reaches the target thickness. Then the cavity is cooled and depressurized, and the wafer is transferred out of the process cavity to complete the preparation of the low-resistivity TiN film.

[0045] Example 2 This embodiment provides a low-resistivity TiN thin film and its preparation method, the preparation method including the following steps: (1) After the surface of the semiconductor substrate with the high aspect ratio MIM structure is cleaned by standard cleaning to remove particles and organic contaminants, it is transferred into the process chamber of the ALD equipment; (2) Evacuate the cavity to the basic pressure, then introduce N2 to replace the air, heat to 350°C, and stabilize the cavity pressure at 20±5 torr; (3) Introduce TiCl4 precursor (flow rate 350 sccm), pulse duration 0.4 s; after the pulse ends, stop introducing TiCl4 and simultaneously introduce N2 to purge the cavity; (4) Introduce NH3 precursor (flow rate 350 sccm), pulse duration 0.4 s; after the pulse ends, stop introducing NH3 and simultaneously introduce N2 to purge the cavity; (5) After repeating steps (3) to (4) for a total of 22 cycles (corresponding to a TiN thin layer of about 10 Å thickness), SiH4 (flow rate 65 sccm) is introduced and the treatment time is 30 s; after the treatment is completed, the introduction of SiH4 is stopped and N2 is introduced to purge the cavity. (6) Repeat steps (3) to (5) until the TiN film reaches the target thickness. Then the cavity is cooled and depressurized, and the wafer is transferred out of the process cavity to complete the preparation of the low-resistivity TiN film.

[0046] Example 3 This embodiment provides a low-resistivity TiN thin film and its preparation method, the preparation method including the following steps: (1) After the surface of the semiconductor substrate with the high aspect ratio MIM structure is cleaned by standard cleaning to remove particles and organic contaminants, it is transferred into the process chamber of the ALD equipment; (2) Evacuate the cavity to the basic pressure, then introduce N2 to replace the air, heat to 450°C, and stabilize the cavity pressure at 20±5 torr; (3) Introduce TiCl4 precursor (flow rate 500 sccm) for 0.2 s pulse duration; after the pulse ends, stop introducing TiCl4 and simultaneously introduce N2 to purge the cavity; (4) Introduce NH3 precursor (flow rate 500 sccm), pulse duration 0.2s; after the pulse ends, stop introducing NH3 and simultaneously introduce N2 to purge the cavity; (5) After repeating steps (3) to (4) for a total of 20 cycles (corresponding to a TiN thin layer of about 10 Å thickness), SiH4 (flow rate 100 sccm) is introduced and the treatment time is 20 s; after the treatment is completed, the introduction of SiH4 is stopped and N2 is introduced to purge the cavity. (6) Repeat steps (3) to (5) until the TiN film reaches the target thickness. Then the cavity is cooled and depressurized, and the wafer is transferred out of the process cavity to complete the preparation of the low-resistivity TiN film.

[0047] Comparative Example 1 This comparative example provides a TiN thin film and its preparation method. Except for the absence of SiH4 treatment in step (5), the other steps and conditions are the same as in Example 1, so they will not be described in detail here.

[0048] Comparative Example 2 This comparative example provides a TiN thin film and its preparation method. Except for the absence of SiH4 treatment in step (5), the other steps and conditions are the same as in Example 2, so they will not be described in detail here.

[0049] Comparative Example 3 This comparative example provides a TiN thin film and its preparation method. Except for the absence of SiH4 treatment in step (5), the other steps and conditions are the same as in Example 3, so they will not be described in detail here.

[0050] Performance testing The resistance of the TiN films obtained in Examples 1-3 and Comparative Examples 1-3 was measured using the four-probe method. The relevant test results are shown in Table 1 below.

[0051] Table 1 Therefore, this invention introduces a strong reducing gas SiH4 during the deposition of TiN thin films. By increasing the content of highly active Si species and utilizing the thermodynamic stability advantage of Si-O bonds, it selectively reduces adsorbed oxygen and weakly bound oxygen on the TiN surface, thereby reducing the oxygen doping concentration and significantly lowering the film resistance. This fundamentally suppresses the high resistance problem caused by oxygen doping and lattice defects, requires no additional equipment, and is suitable for the filling requirements of high aspect ratio MIM structures.

[0052] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a low-resistivity TiN thin film, characterized in that, The preparation method includes at least the following steps: using TiCl4 and NH3 as precursors, preparing TiN thin films by atomic layer deposition, and simultaneously treating the obtained TiN thin films with SiH4 during the deposition process; The resistance of the TiN thin film is ≤305Ω / □.

2. The method for preparing a low-resistivity TiN thin film according to claim 1, characterized in that, Using TiCl4 and NH3 as precursors, the obtained TiN film was subjected to one SiH4 treatment every 25 growth cycles.

3. The method for preparing a low-resistivity TiN thin film according to claim 2, characterized in that, The SiH4 treatment temperature is 300~450℃; And / or, the SiH4 treatment time is 20~40s; And / or, during the SiH4 treatment process, the SiH4 flow rate is 30~100 sccm.

4. The method for preparing a low-resistivity TiN thin film according to claim 2, characterized in that, During each growth cycle, the influent flow rate of TiCl4 is 200~500 sccm, and the influent flow rate of NH3 is 200~500 sccm.

5. The method for preparing a low-resistivity TiN thin film according to any one of claims 1 to 4, characterized in that, The cavity pressures for atomic layer deposition and SiH4 treatment are 15~25 torr, respectively.

6. The method for preparing a low-resistivity TiN thin film according to any one of claims 1 to 4, characterized in that, Each growth cycle consists of sequential NH3 pulse, purging, TiCl4 pulse, and purging.

7. The method for preparing a low-resistivity TiN thin film according to claim 6, characterized in that, The duration of the NH3 pulse is 0.2~0.5s; And / or, the duration of the TiCl4 pulse is 0.2~0.5s.

8. The method for preparing a low-resistivity TiN thin film according to claim 6, characterized in that, The purging process uses N2 as the purging gas.

9. A low-resistivity TiN thin film, characterized in that, The low-resistivity TiN thin film is prepared by the preparation method described in any one of claims 1 to 8.

10. A semiconductor device, characterized in that, The semiconductor device contains at least the low-resistivity TiN thin film as described in claim 9.

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