TW202003369A - Selective deposition of metal silicides - Google Patents

Abstract

Embodiments of the disclosure relate to selective metal silicide deposition methods. In one embodiment, a substrate having a silicon containing surface is heated and the silicon containing surface is hydrogen terminated. The substrate is exposed to sequential cycles of a MoF₆ precursor and a Si₂ H₆ precursor which is followed by an additional Si₂ H₆ overdose exposure to selectively deposit a MoSi_x material comprising MoSi₂ on the silicon containing surface of the substrate.

Description

Selective deposition of metal silicide

The embodiments of the present disclosure generally relate to methods for metal silicide deposition.

Accurate positioning of materials on nanoscale devices is essential to manipulate the atomic properties of next-generation nanoelectrons. For semiconductor manufacturing, the detailed positioning of materials with excellent conformality and stoichiometry is used to meet the demands for cost, yield and yield. As metal oxide semiconductor field-effect transistors (MOSFETs) are scaled to channel lengths of less than <10 nm, it is necessary to overcome limitations resulting from top-down processes, such as damage from reactive ion etching and three-dimensional (3D) Structural complexity of structural alignment on the surface.

Recently, since MOSFET devices have been manufactured in a 3D structure (FinFET), while maintaining the quality of the conformal film, there is increasing interest in selective deposition in the nano-scale region. One method of regioselective deposition is to use a self-assembled monolayer (SAM) as a passivation layer in conjunction with an atomic layer deposition (ALD) process. The passivation layer blocks or eliminates surface functional groups that are reactive with the ALD precursor, so that selectivity can be obtained; however, the SAM method still utilizes selective deposition of the passivation layer. In addition, the selective removal of the passivation layer after selective deposition requires additional process complexity and reduced yield.

Therefore, what is needed in the art is an improved method for selective material deposition.

In one embodiment, a substrate processing method is provided. The method includes the steps of: heating a substrate having a silicon-containing surface to a first temperature, exposing the substrate to a hydrogen-containing plasma, exposing the substrate to a first amount of MoF ₆ precursor, and exposing the substrate to The second amount of Si ₂ H ₆ precursor. Sequentially cycling the step of exposing the substrate to the first dosage and the step of exposing the substrate to the second dosage, and after the sequential cycling step, exposing the substrate to the third dosage of Si ₂ H ₆ precursor .

In another embodiment, a substrate processing method is provided. The method includes the steps of positioning the substrate on a heater in a reaction chamber having a chamber wall, heating the substrate on the heater to a first temperature, and maintaining the chamber wall at a second temperature less than the first temperature Temperature, and exposing the silicon-containing surface of the substrate to hydrogen. Exposing the substrate to a first amount of MoF ₆ precursor, exposing the substrate to a second amount of Si ₂ H ₆ precursor, sequentially cycling the steps of exposing the substrate to the first amount and exposing the substrate to the first A second amount of steps, and after the step of sequential cycling, expose the substrate to a third amount of Si ₂ H ₆ precursor.

In yet another embodiment, a substrate processing method is provided. The method includes the steps of: heating the substrate to a first temperature, exposing the silicon-containing surface of the substrate to a hydrogen-containing plasma, exposing the substrate to a first amount of MoF ₆ precursor, and exposing the substrate to the first Two amounts of Si ₂ H ₆ precursor. Sequentially cycling the step of exposing the substrate to the first dosage and the step of exposing the substrate to the second dosage, after the sequential cycling step, exposing the substrate to the third dosage of Si ₂ H ₆ precursor, And after exposing the substrate to the third amount, the substrate is annealed at a second temperature between about 500°C and about 550°C.

The embodiments described in this book include a method of using ALD precursors for substrate selective reactivity for regioselective deposition. More specifically, the embodiments of the present disclosure are related to the selectivity of substrates using MoF ₆ and Si ₂ H ₆ , with MoSi _x preferentially depositing on Si over Si ₂ , SiON, and SiN _x . To obtain a stoichiometric MoSi ₂ film, the incorporation of additional Si into the film is performed by adding Si ₂ H ₆ to the Mo-rich MoSi _x film after the ALD cycle of MoF ₆ and Si ₂ H ₆ .

Highly selective deposition of MoSi _x on Si over SiO ₂ and SiN _x is achieved by atomic layer deposition (ALD) of MoF ₆ and Si ₂ H ₆ precursors at a temperature of about 120°C. The lack of chemical reactivity between the reactants (MoF ₆ and Si ₂ H ₆ ) and the substrate containing SiO ₂ and SiN _x enables deposition selectivity. In contrast, MoF ₆ nucleates on H-terminal Si in a self-limiting manner, and subsequent Si ₂ H ₆ exposure reduces MoF _x to Mo ⁰ , which is consistent with the formation of Mo-Si bonds.

X-ray photoelectron spectroscopy (XPS) showed that five ALD cycles of MoF ₆ and Si ₂ H ₆ selectively deposited a sub-stoichiometric MoSi ₂ film on the Si substrate. In the ALD process, MoF ₆ and Si ₂ H ₆ precursors are sequentially cycled in a repeating manner, where purification is performed between each successive precursor exposure. The additional amount of Si ₂ H ₆ on the sub-stoichiometric MoSi ₂ film incorporates more Si into the film without disturbing the deposition selectivity for SiO ₂ and SiN _x . In one embodiment, the Si:Mo ratio of the bulk MoSi _x film is from about 1.7 to about 1.9, where the F and O impurities are less than about 10%. It is believed that the embodiments described in this book are superior to the traditional high-pressure Si ALD cycle used for the formation of silicide materials, for example, in the formation of source/drain contact structures.

According to the embodiment described in this book, the deposition selectivity of MoSi _x was analyzed on a patterned Si substrate containing three-dimensional (3D) nano-scale SiO ₂ and SiN _x features. Transmission electron microscopy (TEM) cross-sections indicate selective MoSi _x deposition on nanoscale 3D structures. In one embodiment, SiO ₂ is present in the core is less than about 10 / μm ^2; SiO ₂ since the OH group having from about 10 ⁷ / μm ^2, which corresponds to the OH group on the SiO ₂ and Si The selectivity between Si-H groups is about ¹⁰⁷ :1. Therefore, it is believed that the substrate-dependent selectivity of silicide deposition can eliminate the use of passivating agents (ie, SAM). experiment

Various substrate types are used in the MoSi _x silicide formation process described in this book. Four types of substrates are used: P-type Si (100) (doped with boron, available from Virginia Semiconductor of Fredericksburg, Virginia), and SiO ₂ thermally grown on Si (100) (available from Massachusetts University Wafer of South Boston, SiON (available from Applied Materials, Inc., Santa Clara, California), and Si, SiO ₂ and SiN _x material surfaces on a single substrate Patterned substrate. Unless otherwise stated, the SiON (silicon oxynitride) described in this book is Si ₃ N ₄ , which has been subjected to reactive ion etching and plasma ashing in oxygen during manufacturing. Therefore, the SiON substrate contains oxygen, which is similar to the conditions of Si ₃ N ₄ after processing in an integrated 3D nanoscale device.

The substrate was cut into 12mm × 3mm pieces and degrease was removed with acetone, methanol and deionized (DI) H ₂ O. The native oxide on Si was removed by immersing the cleaned substrate in a 0.5% HF (aq) solution for 30 seconds. In order to maintain consistency during the cleaning process, the same cleaning procedure is performed on SiO ₂ , SiON, and the patterned substrate. It is also expected that a plasma-based native oxide removal process can be used. For example, the NF ₃ /H ₂ and/or NF ₃ NH ₃ plasma cleaning process can be used to clean the silicon-containing surface of the substrate and hydrogen terminate the silicon-containing surface of the substrate. On SiON substrates, it is believed that NF ₃ plasma treatment prevents or substantially reduces the loss of deposition selectivity by passivating active hydroxyl nucleation sites. In certain embodiments, the native oxide removal process is SICONI can be obtained from Santa Clara, California, Applied Materials, Inc. ^® preclean process.

High-purity N ₂ gas is used to blow-dried the substrate. The Si, SiO ₂ , SiON, and patterned substrate are loaded together on a single substrate holder to expose the substrate to the same ALD conditions. The substrate is loaded into a loading gate chamber pumped by a turbo molecular pump and supported by a mechanical pump. The basic pressure of the loading gate is about 2.0×10 ^-7 Torr. Next, the original displacement of the substrate was sent to an ultra-high vacuum chamber with a base pressure of about 3.0×10 ^-10 Torr pumped by an ion pump and a titanium sublimation pump. The ultra-high vacuum chamber is equipped with a monochromatic XPS device (XM 1000 MkII/SPHERA, available from Scienta Omicron, Inc., Denver, Corolla), and a scanning tunneling microscope (STM) (available from Corolla Acquired by Scienta Omicron, Inc. of Denver, multi-state) and an annealing system using pyrolytic boron nitride (PBN) heaters.

First, the substrate was annealed at 120°C in an ultra-high vacuum chamber, and the chemical composition of the substrate was measured using XPS. The original displacement of the substrate is sent to the reaction chamber with a base pressure of about 5.0×10 ^-7 Torr. For MoSi _x deposition, MoF ₆ (99% purity, available from Synquest Laboratories, Alachua, Florida) and Si ₂ H ₆ (99.99% purity, available from Air Liquide USA, LLC, Houston, Texas) precursors were used.

During the ALD cycle, a constant N ₂ (80 mTorr) purge was used, and a leak valve was used to control the pressure of the purge. A pneumatic valve controlled by LabView software (available from National Instruments, Austin, Texas) was used to adjust the amount of MoF ₆ and Si ₂ H ₆ . The volume of MoF ₆ and Si ₂ H ₆ is the expansion volume. The use of an expanded volume includes filling a secondary volume with MoF ₆ or Si ₂ H ₆ and distributing precursors from their respective secondary volumes. The filling time of MoF ₆ is between about 10 ms and about 10 ms, such as about 40 ms. The dosage time of MoF ₆ is between about 10 ms and about 100 ms, such as about 50 ms. The filling time of Si ₂ H ₆ is between about 1 ms and about 50 ms, such as about 18 ms. The dosage time of Si ₂ H ₆ is between about 1 ms and about 50 ms, such as about 18 ms.

Use Langmuirs (L) to calculate the exposure of MoF ₆ and Si ₂ H ₆ , where 1L=1×10 ^-6 Torr×1 second. The peak pressure during the exposure was monitored using a convectron gauge vacuum gauge in the reaction chamber. The dosage is about 1.8 MegaL of MoF ₆ and about 4.2 MegaL of Si ₂ H ₆ , and the waiting time between the dosage is 2 minutes. A PBN heater is used to heat the substrate and maintain the temperature between about 100°C and about 150°C, such as about 120°C. The chamber wall is maintained at a temperature between about 65°C and about 85°C. In one embodiment, the amount of MoF ₆ is between about 1.0 MegaL and about 10 MegaL. In another embodiment, the amount of Si ₂ H ₆ is between about 1.0 MegaL and about 10 MegaL.

After the deposition cycle, the substrate was originally displaced into an ultra-high vacuum chamber for XPS and STM analysis. For XPS measurements, X-rays are generated by Al Kα anodes (1486.7 eV). Use constant analyzer energy (CAE) to obtain XPS data, with a step width of 0.1 eV and a pass energy of 50 eV. Position the XPS detector at 60° from the substrate normal (take-off angle of 30° from the substrate surface), where the detector-acceptance angle is 7°. After using the XPS v.2.3 program to correct each peak area and its corresponding relative sensitivity factor, analyze the XPS spectrum. All chemical components in this work are standardized to the sum of all components. Scanning tunneling microscope inspection was performed using a substrate bias of -1.8V and a constant current of 200pA.

In order to study the elemental composition of the main body of the film, Ar ⁺ sputtering was performed together with XPS. With a lens voltage of 5 kV and an Ar of 6.0×10 ^-7 Torr, the beam current is 1.2 μA; since the grating is used to cover the entire substrate area, the current density is about 1.2 uA/50 mm ² . The MoSi _x substrate was kept at 25°C during sputtering to minimize any thermal desorption. result

FIG. 1A illustrates the data of the XPS chemical composition of Si surfaces cleaned with HF before and after continuous use of MoF ₆ and Si ₂ H ₆ at 120° C. FIG. Two sets of 5.4 MegaL MoF ₆ were used on the HF cleaned Si substrate at 120°C. XPS shows that the saturation of Mo is 16%. Then, 4.2 MegaL of Si ₂ H ₆ and an additional 42 MegaL of Si ₂ H _{6 were} applied to the MoF ₆ saturated Si surface at 120° C., resulting in a 59% saturation of Si. In one embodiment, the amount of MoF ₆ is between about 1 MegaL and about 10 MegaL. In another embodiment, the amount of SI ₂ H ₆ is about 1 MegaL to about 10 MegaL. In another embodiment, the additional amount of Si ₂ H ₆ is between about 20 MegaL and about 50 MegaL.

After HF cleaning, all Si is in the oxidation state 0, which is 9% O and 12% C pollution. It is believed that contamination is caused by accidental hydrocarbon adsorption during substrate transfer to vacuum. HF (aq) is used to eliminate the native oxide on Si and make the Si surface H-terminated. It should be noted that the Si 2p data in FIG. 1 represents the total amount of Si, and the Si(0) data represents the amount of Si in the oxidation state of 0.

After 5.4 MegaL of MoF ₆ at 120°C, 14% Mo and 38% F were deposited on the HF cleaned Si surface. After additional addition of 5.4 MegaL of MoF ₆ at 120°C, the Mo concentration increased from 14% to 16%, and the F concentration increased from 38% to 42%. After an additional 5.4 MegaL of MoF ₆ , this small increase in Mo and F content indicates that the reaction of MoF ₆ on HF-cleaned Si is self-limiting. After the Si surface is saturated with MoF _x , the F/Mo ratio is 2.6 and all Si is in the oxidation state of 0. The continuous application of 4.2 MegaL of Si ₂ H ₆ and 42 MegaL of Si ₂ H ₆ indicates that the Si ₂ H ₆ reaction is also saturated on the MoF _x covered Si surface. It is believed that for thicker sub-stoichiometric MoSi ₂ films, additional Si can be bonded to the surface. However, Si ₂ H ₆ reacts on a thin (monolayer) Mo film in a self-limiting manner.

After Si ₂ H _{6 is} saturated, the Si content is 59%, and F is reduced to 10%. Since the substrate is Si, because F desorption occurs, this increase in Si content after the application of Si ₂ H ₆ can be partially attributed to the substrate. However, the decay of Mo after application of Si ₂ H ₆ was observed, which was consistent with the deposition of Si. The reaction of MoF ₆ and Si ₂ H ₆ on H-terminal Si proves the possibility of MoSi _x ALD on Si-H terminal Si.

FIG. 1B illustrates the XPS chemical composition data of the same series of MoF ₆ and Si ₂ H ₆ saturation amounts described above with respect to FIG. 1A but on a SiON substrate. As shown, no reaction was observed. It should be noted that although the SiON substrate is nominally SiON, XPS shows only a negligible amount of N on the surface, so the substrate is mainly ion damaged (SiO _{x )} . After the first 3 pulses of MoF ₆ , 8% F and negligible Mo (<1%) were observed. For the remaining saturation levels, the SiON surface remains unreactive to both MoF ₆ and Si ₂ H ₆ . Although the SiON used in this study is ion-damaged, Si is in the oxidation state of +3 and +4, and the data are consistent with the strong Si-O, Si-N, and SiO-H bonds, so the formation of Si and Mo is essentially excluded Bonding.

2A and 2B illustrate the XPS spectra of Si 2p and Mo 3d for HF-cleaned Si substrates to compare the oxidation state of each experimental operation. FIG. 2A illustrates the Si 2p peak after continuous application of MoF ₆ and S ₂ H ₆ , which shows that Si remains at an oxidation state of 0 after 10.8 MegaL of MoF ₆ at 120° C. (blue line), which is different from Mo-Si Bonding is formed and Si etching without passing F is consistent. After applying 4.2 MegaL of Si ₂ H ₆ (red line) at 120° C., most of the Si remained in the oxidation state of 0. This is consistent with the formation of a single layer of MoSi ₂ . A small peak of oxidized Si appears at a higher binding energy, which may be SiH _x F _4-x (x = 2 or 3) or SiO _x at the surface. FIG. 2B illustrates the Mo 3d peak after continuous application of MoF ₆ and S ₂ H ₆ , which shows that the Mo 3d peak exists in multiple oxidation states after application of a saturated amount of MoF ₆ (black and blue lines). After applying Si ₂ H ₆ (red line), all Mo was reduced and the peak was concentrated at 227.4 eV, which is consistent with MoSi ₂ .

After the first MoF ₆ of 5.4 MegaL, the Si 2p peak remains at the oxidation state of 0, which is consistent with the formation of Si-Mo bonding. The Mo 3d peak appears in multiple oxidation states, which means that the surface material is MoF _x , where x=4, 5 and 6 (black line). The additional 5.4 MegaL of MoF ₆ did not change the oxidation state of the Si 2p or Mo 3d peak (blue line). These data indicate that Si-Mo-F _x is formed on the surface. Notably, the amount administered ₆ saturated MoF F / Mo ratio of 2.6 (FIG. 1A XPS data), and the oxidation state of Mo is ^4-6; Thus, it is believed that some of Mo-O bond formation. After the application of 4.2 MegaL of Si ₂ H ₆ dosage (red line), a small shoulder peak of higher binding energy (103 eV) appeared on the Si 2p XPS peak. This is consistent with the formation of Si-F or Si-O. The Mo 3d spectrum shows that after a single application of Si ₂ H ₆ , all Mo is reduced to Mo ⁰ , and the binding energy is 227.4 eV. This is consistent with the formation of a single layer of MoSi _x and the transfer of any residual oxygen or fluorine from Mo to Si in the form of Si—O and Si—F bonds. The simplified reaction of MoF ₆ and Si ₂ H ₆ can be described as:

The ALD characteristics of MoSi _x on Si substrates and selectivity to SiO ₂ and SiN _x substrates were verified via XPS deposited via MoSi _x on patterned substrates. FIG. 3A illustrates the chemical composition of a set of three substrates: HF cleaned Si, HF cleaned SiO _2, and HF cleaned patterned substrate. FIG. 3B illustrates the chemical composition of each of the substrates of FIG. 3A after 5 ALD cycles of MoF ₆ and Si ₂ H ₆ at 120°C. This data indicates that MoSi _x lacking Si is selectively deposited on Si instead of SiO ₂ . The Si ⁰ component of the patterned sample is also selectively attenuated by MoSi _x deposition. 3C illustrates the chemical composition of each of the substrates of FIG. 3B after an additional 25.2 MegaL (between 3 pulses and 10 pulses) of Si ₂ H ₆ . The additional Si ₂ H ₆ binds Si to the MoSi _x surface. The selectivity to SiO ₂ is maintained during the additional Si ₂ H ₆ pulse (SiO ₂ has 0% Mo and 0% SiO ₂ throughout the ALD process).

The three substrates are loaded together on a single substrate holder to ensure that they are exposed to the same deposition conditions. Si and SiO ₂ substrates allow verification of selectivity during deposition on patterned substrates. The patterned substrate has a SiO ₂ layer sandwiched by SiN _x on top of the Si substrate. It should be noted that SiN _x on the patterned substrate is actually SiON because it is damaged by ions and ashed in O ₂ during manufacturing. As shown in Figure 3A, 30 seconds (30 s) of HF cleaning removes the native oxide on Si. The thermally grown SiO ₂ is 300 nm thick, and 30-second HF cleaning does not change the elemental composition or oxidation state of SiO ₂ . The patterned substrate cleaned by HF is composed of a mixture of SiN _x , SiO _x and Si ⁰ .

As shown in FIG. 3B, XPS was performed after 5 ALD cycles of MoF ₆ and Si ₂ H ₆ at 120°C. XPS shows the surface composition of 32% Mo and 10% Si on the Si substrate, which corresponds to MoSi _{x which is} highly deficient in Si. There is no MoSi _x deposition on the SiO ₂ substrate, which is consistent with high-selectivity ALD. On the patterned substrate, XPS showed that 5% Mo was deposited, and Si ⁰ was attenuated to 1%. During ALD on the patterned substrate, the ratio of N and O at the surface did not change significantly. This data is consistent with the MoSi _x deposition selectivity lacking Si on 6% Si ⁰ on patterned substrates.

The deposition selectivity on the patterned substrate is consistent with the three aspects of the embodiment described in this specification: (1) MoSi _{x is} deposited on the Si substrate but not on the SiO ₂ substrate. (2) After MoSi _x deposition, Si ⁰ (not the higher oxidation state Si peak from Si-N and Si-O) is attenuated on the patterned substrate. (3) Numerically, about 4% Mo deposition on a patterned substrate with 6% Si ⁰ is proportional to 32% Mo on a Si substrate with 54% Si ⁰ on the HF cleaned surface (proportional ).

1: 2:

Even though a single layer of MoSi ₂ can be deposited on Si in the ALD saturation experiments described in FIGS. 1 and ₂ , continuous ALD cycles will not produce stoichiometric MoSi ₂ . It is believed that the formation of MoSi _x lacking Si is due to the desorption of surface Si-H substances during the elimination of fluorosilane and the residual Mo-F bonds that are not easily removed due to the standard Si ₂ H ₆ dosage. For the first 1-3 monolayers, there is excess Si from the substrate to help fluorine desorption, but for thicker films, Mo-F surface bonds may persist because the only available Si comes from gaseous Si ₂ H ₆ . The entire fluorosilane elimination chemistry using MoF ₆ and Si ₂ H ₆ is consistent with one of the two chemical reactions:

1: 2:

To form MoSi ₂ , three substrates were exposed to an additional 25.2 MegaL (between 3 and 10 pulses, such as 6 pulses) of Si ₂ H ₆ at 120°C (see Figure 3C). After the additional Si ₂ H ₆ exposure, the Si on the Si substrate increased to 20% consistent with the Si incorporated into the film or on the substrate surface. The additional amount of Si ₂ H ₆ did not reduce the selectivity of Si for SiO ₂ deposition.

4A-4C illustrate XPS chemical composition data for selective MoSi _x deposition on HF-cleaned Si, SiO ₂ and SiON with post-deposition annealing. FIG. 4A illustrates the XPS chemical composition of Si, SiO ₂ and SiON substrates after HF cleaning. Figure 4B shows the XPS chemical composition data, which shows that after 5 ALD cycles of MoSi _x followed by an additional 6 pulses (25.2 MegaL) of Si ₂ H ₆ at 120° C., MoSi _x is only selectively deposited on Si . FIG. 4C illustrates the XPS chemical composition data of a post-deposition annealed (PDA) substrate that was performed at 520° C. for 3 minutes. As shown in the figure, the PDA removes F from the MoSi _x film and reduces Mo to Mo ⁰ .

FIG. 4A illustrates that the SiON surface is mainly composed of SiN _x after HF cleaning. After 5 cycles of ALD of MoSi _x followed by the addition of 25.2 MegaL of Si ₂ H ₆ , 24% of Mo and 18% of Si were cleaned on the HF cleaned, while little was detected on the surfaces of SiO _x and SiN _x At 1% Mo, as shown in Figure 4B. Subsequently, the three substrates were annealed at 520°C for 3 minutes, which reduced the F on the Si substrate from 25% to 3%. The 520°C PDA also reduced Mo on the Si substrate to Mo ⁰ and reduced the Si:Mo ratio from about 0.75 to about 0.5 at the surface. This is consistent with the desorption of surface F in the form of SiHF ₃ or SiF ₄ . XPS analysis of the PDA shows that F is removed from the film by the PDA, which reduces the possibility of F diffusion into adjacent MOSFET device structures.

Using in situ STM and ex-situ atomic force microscopy (AFM), surface topographies were studied after deposition on Si and SiO ₂ substrates and after PDA. After 20 cycles of MoF ₆ and Si ₂ H ₆ , separate HF cleaned Si substrates were prepared for in-situ STM. The STM data indicates that the MoSi _x film is atomically flat and normal, with an RMS roughness of about 2.8Å. The above substrate was annealed in situ at 500° C. for 3 minutes in an ultra-high vacuum chamber under a pressure of about 5.0×10 ⁻¹⁰ Torr. After annealing at 500°C, the film becomes flatter with an RMS roughness of about 1.7Å.

After 5 ALD cycles at 120°C followed by in-situ annealing at 550°C, another substrate of Si cleaned by MoSi _x /HF was taken into an ex-situ furnace, balanced at 5% H ₂ and N ₂ (5% H ₂ balanced with N ₂ ) 900 °C peak annealing. After peak annealing at 900°C, AFM was used to obtain the surface morphology. The film maintains sub-nano-level RMS roughness of 4.75Å, indicating that the MoSi _x film has high thermal stability up to about 900°C.

After performing 5 ALD cycles at 120°C followed by in-situ annealing at 550°C for 3 minutes, in order to confirm the selectivity, the ectopic AFM image data on the surface of the SiO ₂ substrate was performed by calculating the number of cores on the substrate surface. The density of nuclei is about 9 nuclei/μm ² , which proves that Si deposition is superior to SiO ₂ . It is believed that by controlling the wall temperature of the reaction chamber and by using short high-pressure Si ₂ H ₆ pulses and longer purification cycles to promote ALD and avoid CVD deposition schemes, the high deposition selectivity of the embodiments described in this specification is further improved .

A depth profile study was also conducted to determine the internal composition of the MoSi _x film. FIG. 5A shows the XPS chemical composition data of Ar ⁺ sputtering on MoF ₆ and Si ₂ H ₆ followed by HF cleaning at 120° C. for five cycles. FIG. 5B illustrates the XPS peak of Si 2p after sequential Ar ⁺ sputtering, and the result shows that the main body of the MoSi _x film is mainly composed of SiO. 5C illustrates a graph of the chemical composition data of the deposited film versus Ar ⁺ sputtering time of Si after 5 cycles of MoF ₆ and Si ₂ H ₆ at 120°C.

The XPS data shown in Figure 5A is derived from the MoSi _x film deposited on the HF-cleaned Si substrate with MoF ₆ and Si ₂ H ₆ at 120°C using 5 ALD cycles without additional Si ₂ H ₆ Combine. As the sputtering time increases, the MoSi _x film becomes thinner until the underlying Si substrate is exposed. The first 10 minutes of sputtering reduced F from 35% to 8%, and Mo was converted from a mixture of oxidized Mo and Mo ⁰ to pure Mo ⁰ . This data is consistent with the surface F mainly bonded to Mo.

After continuous sputtering cycles, the amount of Si increases and the amount of Mo decreases. In addition, the amount of Si ⁰ increases with the total Si, and reaches a maximum value of 43% after 100 minutes of the total sputtering time. The ratio of Si ⁰ to Mo ⁰ is used to distinguish the pure MoSi _x phase because in the pure MoSi _x phase, Mo and Si are bonded to each other and the oxidation state is 0. After removing silicon oxide and MoF _x substances at the substrate surface, the percentage of SiO exceeds the percentage of Mo ⁰ . The Si ⁰ :Mo ⁰ ratio in the main body of the MoSi _x film is 1.41, which corresponds to the MoSi _x film lacking Si. It should be noted that at the center of the film, the Si:Mo ratio is 1.77, therefore, in the absence of background O2/H ₂ O, the ratio of Si ⁰ :Mo ⁰ may be closer to 2.

FIG. 5B illustrates the raw XPS spectrum of Si 2p measured corresponding to each XPS of FIG. 5A. After the fourth sputtering cycle, the Si peak of 99.2eV increased and expanded to a higher binding energy. Conversely, after each sputtering cycle, the energy of the Mo peak corresponds to Mo ⁰ . Therefore, it is believed that the bulk MoSi _x film is mainly Si ⁰ and Mo ^{0 in the} form of MoSi _x , while the top and bottom interfaces are rich in SiO _x . The top SiO _{x is} consistent with the contamination from the chamber environment, while the bottom interface oxide is consistent with the imperfect ex-situ HF cleaning.

The sub-stoichiometric oxide at the bottom interface does not affect the deposition and film quality, which means that the selectivity of MoSi _x ALD is sensitive to the quality of SiO ₂ . FIG. 5C illustrates the percentage of chemical composition obtained from the XPS measurement in FIG. 5A. After the second sputtering cycle (total sputtering time 40 minutes), F drops below 3% and eventually reaches 0%. O<10% in the main body of the film but slowly increased to 15% at the MoSi _x -Si interface, which is consistent with the presence of the interface oxide layer.

To understand the additional amount of Si ₂ H ₆ Si MoSi _x film on: MoSi _x film impact Mo ratio of Si having added additional purposes XPS depth profile. After the end of 5 ALD cycles of MoF ₆ and Si ₂ H ₆ at 120°C, an additional 6 pulses (25.2 MegaL) of Si ₂ H ₆ dosage were applied, followed by annealing at 530°C on the dried and cleaned Si 3 minute. The post-annealing dry cleaning process described in this book uses NF ₃ and NH ₃ plasmas, with Ar as the carrier gas.

6A-6D illustrate XPS profiling data of MoSi _x film after exposure to additional Si ₂ H ₆ dosage. 6A illustrates followed by an additional 6 pulses at 120 deg.] C after 5 cycles MoF ₆ and Si ₂ H ₆ is (25.2MegaL) of Si ₂ H _6, following the dry Ar ⁺ sputter cleaned of Si XPS chemical composition information. 6B illustrates XPS surface composition data after ₅ ALD cycles of MoF ₆ and Si ₂ H ₆ with and without additional Si ₂ H ₆ pulses. For 5 ALDs, the Si:Mo ratio is 0.33, and for 5 ALD+6×Si ₂ H ₆ , the Si:Mo ratio is 0.89, which is consistent with the addition of Si on the surface. FIG. 6C illustrates the XPS body composition data of MoSi _x with and without additional Si ₂ H ₆ pulses after removal of surface contaminants using Ar ⁺ sputtering. For 5 ALDs, the Si:Mo ratio is 1.77, and for 5 ALD+6×Si ₂ H ₆ , the Si:Mo ratio is 1.96. Figure 6D shows the XPS chemical composition data of the MoSi _x film relative to the Ar ⁺ sputtering time on Si after 5 cycles of MoF ₆ and Si ₂ H ₆ followed by an additional Si ₂ H ₆ pulse at 120°C Of the graph.

FIG. 6A shows a series of depth profiling XPS after each operation on the dry-cleaned substrate. After 6×Si ₂ H ₆ /5 ALD cycles, there are 28%F, 20%Si and 28%Mo on the substrate surface. After annealing at 530° C., most of the F on the surface was removed, and all of Mo was reduced to Mo ⁰ , which is consistent with the desorption of F from the surface shown in FIG. 4. In this operation, the Si:Mo ratio is 0.89. In contrast, the Si:Mo ratio of the MoSi _x film without the additional amount of Si ₂ H ₆ is only 0.33, as shown in FIG. 6B.

After removing the surface oxide pollution, for MoSi _x with additional Si ₂ H ₆ pulses, Si ⁰ :Mo ⁰ in the body is 1.32 (Si:Mo = 1.96). This is comparable to Si ⁰ :Mo ⁰ =1.41 (Si:Mo = 1.77) in the MoSi _x body without additional Si ₂ H ₆ added as shown in FIG. 6C (comparable). Therefore, it is believed that after the ALD cycle, additional Si ₂ H ₆ pulses increase the Si content at the Si-deficient MoSi _x surface. In contrast, the Si:Mo ratio in the body of the MoSi _x film is close to the stoichiometric MoSi ₂ . 6D illustrates XPS percentage of each chemical component is a function of Ar ⁺ sputtering time, which coincides with the body forming MoSi _x film of MoSi _x.

In one embodiment, a pneumatic valve was used to introduce 4.2 MegaL of Si ₂ H ₆ into the reaction chamber for a duration of 6 seconds. The Si ₂ H ₆ process characteristics using about 3 times more Si ₂ H ₆ exposed the application dosage duration that is about 10 times shorter than the traditional Si ₂ H ₆ application dosage parameters. Therefore, compared to the traditional application dosage scheme, the embodiment described in this book uses a 30× higher partial pressure during the ALD application dosage. It is believed that a 30-fold higher instantaneous pressure during the application amount can allow the precursor-mediated Si ₂ H ₆ chemisorption layer to remain on the surface long enough to react with Mo to incorporate more Si into the MoSi _x film . It is believed that the addition of Si is self-limiting, which enables the growth rate of MoSi _x to be about 1.2 nm/cycle.

其中k是常數，t是厚度，以及R_max 是所量測的最大電阻。A 4-point probe measurement was used to measure the resistance of the MoSi _x film. For the electricity measurement, an undoped Si (001) with a resistance> 10000 ohm·cm is used as the substrate. For electricity measurement, 10 MoSi _x ALD cycles were deposited on intrinsic (semi-insulating) Si substrates cleaned with HF at 120°C, followed by in-situ annealing at 550°C for 3 minutes, and at 5% H ₂ and Peak annealing at 900°C was performed in N ₂ equilibrium. The Ni spot is deposited as a probe contact. The resistance is 110 ohms, and it is approximated using an infinite board. The resistivity is calculated as follows:

Where k is a constant, t is the thickness, and R _max is the maximum resistance measured.

A cross-sectional TEM study was conducted on the patterned substrate to confirm the selectivity of MoSi _x on the nanostructure pattern. 7 is a cross-sectional TEM image of a MoSi _x /HF cleaned patterned substrate. On the patterned substrate cleaned with HF, 5 cycles of MoSi _x ALD were applied at 120° C., followed by additional addition of 25.2 MegaL of Si ₂ H ₆ . The elemental composition of this substrate in each deposition step is shown in Figures 3A-3C. The TEM image shows the complete selectivity of MoSi _x deposition on Si, but not on SiN _x and SiO ₂ . After 5 ALD cycles, followed by an additional 25.2 MegaL, the thickness of the MoSi _x film deposited on Si was about 6.3 nm, which achieved a growth rate of about 1.2 nm/cycle. Due to the growth rate of each MoSi _x ALD cycle, it is believed that 5 ALD cycles are sufficient for contacting materials and contacting device structures.

Sub-stoichiometric MoSi ₂ selective atomic layer deposition is achieved through selective processes for hydrogen-terminated Si and thermally grown SiO ₂ , ion-damaged SiON, and SiN _x . This selectivity is based on the favorable reactivity of MoF ₆ and Si ₂ H ₆ on H-Si, but not on SiO ₂ or SiN _x because Si-O, Si-N and SiO-H bonds are sufficient Strong, so that they will not be cleaved by the precursor at 120°C. Both MoF ₆ and Si ₂ H ₆ exhibit self-limiting behavior, which allows the deposition of highly orthomorphic and smooth films with a root mean square (RMS) roughness of 2.8Å. Performing the PDA in an ultra-high vacuum at a temperature between about 500°C and 550°C for 3 minutes further reduces the RMS roughness to 1.7Å. Even after peak annealing at 900°C in an H ₂ /N ₂ environment, the quality of the MoSi _x film is maintained, which is consistent with high thermal stability.

In-depth analysis of XPS research shows that the body of the MoSi _x film is close to stoichiometric MoSi ₂ (Si:Mo=1.7-1.9), where oxygen and fluorine are less than 10%. After 5 ALD cycles, the surface of the MoSi _x film showed a highly Si-deficient MoSi _x surface, where the Si:Mo ratio was 0.33, and the Si:Mo ratio at the surface was increased by pulse additional Si ₂ H ₆ to 0.89. Cross-sectional TEM imaging shows that the selectivity is maintained at the nanometer level, and MoSi _x can be selectively deposited on Si without substrate consumption.

The MoSi _x film growth rate of about 1.2 nm/cycle is such that less than 10 ALD cycles (such as 5 ALD cycles) are sufficient to utilize the MoSi _x film as a contact material. Therefore, compared with the traditional ALD process, the process described in this book is used to increase the process output. It is believed that selective MoSi _x deposition eliminates or substantially reduces the reliance on lithography processes for complex 3D MOSFET structures (such as FinFET). The Si-H bond selectivity to SiO-H bond selectivity exceeds ¹⁰⁶ . Therefore, even without using an additional passivation layer, high selectivity can be achieved at the nanometer level. The embodiments described in this specification also illustrate that by changing the partial pressure during the ALD pulse of the reducing agent, the ALD of the silicide to the metal can be easily switched while maintaining selectivity.

Although the foregoing is directed to the embodiments of the present disclosure, other and further embodiments of the present disclosure can be designed without departing from the basic scope of the present disclosure, and the scope of the present disclosure is defined by the scope of the following patent applications Define.

no

This patent or application file contains at least one drawing in color. A copy of this patent or patent application with a color scheme will be provided by the Office upon request and payment of necessary fees.

The features of the present disclosure have been briefly summarized before and discussed in more detail below, and can be understood by referring to the embodiments of the present invention illustrated in the accompanying drawings. However, it is worth noting that the drawings shown only illustrate exemplary embodiments and are not to be considered as a limitation of the scope thereof, and the present disclosure may allow other equivalent embodiments.

FIG. 1A illustrates selective X-ray photoelectron spectroscopy (XPS) data of a MoSi _x film on a silicon substrate according to an embodiment described in this book.

FIG. 1B illustrates selective XPS data of a MoSi _x film on a silicon oxynitride substrate according to an embodiment described in this book.

2A illustrates XPS oxidation state data of Si and Mo on a silicon substrate according to an embodiment described in this book.

2B illustrates XPS oxidation state data of Si and Mo on a silicon substrate according to the embodiment described in this book.

FIG. 3A illustrates XPS chemical composition data of various elements present on different substrate types before the ALD process according to the embodiment described in this book.

3B illustrates XPS chemical composition data of various elements present on different substrate types after 5 ALD cycles according to the embodiment described in this book.

3C illustrates XPS chemical composition data of various elements present on different substrate types after additional ALD cycles according to the embodiment described in this book.

FIG. 4A illustrates the XPS chemical composition data of various elements present on different substrate types before the ALD process according to the embodiment described in this book.

4B illustrates XPS chemical composition data of various elements present on different substrate types after 5 ALD cycles according to the embodiment described in this book.

4C illustrates the XPS chemical composition data of the substrate of FIG. 4B after the annealing process according to the embodiment described in this specification.

FIG. 5A illustrates XPS depth profile data of the MoSi _x film after Ar sputtering according to the embodiment described in this book.

FIG. 5B illustrates the XPS chemical composition data of the MoSi _x film according to the embodiment described in this specification.

FIG. 5C illustrates data representing the chemical composition of the MoSi _x film versus time according to the embodiment described in this book.

FIG. 6A illustrates the XPS depth profile data of the MoSi _x film after Ar sputtering according to the embodiment described in this book.

FIG. 6B illustrates the surface composition data of the MoSi _x film according to the embodiment described in this book.

6C illustrates bulk composition data of the MoSi _x film of FIG. 6B according to an embodiment described in this book.

6D illustrates data representing the chemical composition of the MoSi _x film versus time according to the embodiment described in this book.

7 is a transmission electron microscopy (TEM) cross-sectional view of a MoSi _x film selectively deposited on silicon in preference to other materials present on a substrate according to embodiments described in this book.

For ease of understanding, wherever possible, the same number is used to represent the same element in the illustration. It is expected that the elements and features in one embodiment can be advantageously used in other embodiments without further description.

Domestic storage information (please note in order of storage institution, date, number) No

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Claims (20)

A substrate processing method including the following steps: heating a substrate having a silicon-containing surface to a first temperature; exposing the substrate to a hydrogen-containing plasma; exposing the substrate to a first amount of MoF ₆ precursor The substrate is exposed to a second amount of Si ₂ H ₆ precursor; the step of sequentially exposing the substrate to a first amount and the step of exposing the substrate to a second amount; and After the sequence cycle step, the substrate is exposed to a third amount of Si ₂ H ₆ precursor. The method of claim 1, further comprising the steps of: after exposing the substrate to a third amount, annealing the substrate at a second temperature between 500°C and 550°C. The method according to claim 1, wherein the first temperature is between 100°C and 150°C. The method of claim 1, wherein the sequential loop steps are performed less than 10 times. The method according to claim 4, wherein the step of sequentially looping is performed 5 times. The method of claim 1, wherein the hydrogen-containing plasma is formed from a precursor selected from the group consisting of: NF ₃ , NH ₃ and H. The method according to claim 1, wherein a nitrogen gas purification process using N ₂ is performed during the steps of the sequential cycle. The method according to claim 1, wherein the first amount is applied for a duration between 10ms and 100ms. The method according to claim 8, wherein the first dosage comprises a MoF ₆ flow rate between 1 MegaL and 10 MegaL. The method according to claim 8, wherein the second amount is applied for a duration between 1ms and 50ms. The method according to claim 10, wherein the second amount includes a Si ₂ H ₆ flow rate between 1 MegaL and 10 MegaL. The method according to claim 11, wherein the third amount includes a Si ₂ H ₆ flow rate between 20 MegaL and 50 MegaL. The method according to claim 12, wherein the third amount includes Si ₂ H ₆ between 3 pulses and 10 pulses. The method of claim 1, further comprising the steps of: selectively depositing a MoSi _x film on the silicon-containing surface at a growth rate of 1.2 nm per sequential cycle. A substrate processing method comprising the following steps: positioning the substrate on a heater in a reaction chamber, the reaction chamber having a chamber wall; heating the substrate on the heater to a first temperature; Maintaining the chamber wall at a second temperature lower than the first temperature; exposing a silicon-containing surface of the substrate to hydrogen; exposing the substrate to a first amount of MoF ₆ precursor; the substrate Exposure to a second amount of Si ₂ H ₆ precursor; the step of sequentially cycling the substrate to a first dose and the step of exposing the substrate to a second dose; and after the step of sequentially cycling , The substrate is exposed to a third amount of Si ₂ H ₆ precursor. The method of claim 15, wherein the first temperature is between 100°C and 150°C, and the second temperature is between 65°C and 85°C. The method of claim 15, wherein the first dosage includes a MoF ₆ flow rate between 1 MegaL and 10 MegaL, the second dosage includes a Si ₂ H ₆ flow rate between 1 MegaL and 10 MegaL, and the third Dosage includes a Si ₂ H ₆ flow rate between 20 MegaL and 50 MegaL. The method of claim 15, wherein the step of exposing a silicon-containing surface of the substrate includes the steps of: exposing the silicon-containing surface to one of the following: an electricity from NF ₃ /H ₂ gas Plasma or a plasma from NF ₃ /NH ₃ gas. The method of claim 15, further comprising the following steps: selectively depositing a MoSi _x film containing MoSi ₂ on the silicon-containing surface at a growth rate of 1.2 nm per continuous cycle. A substrate processing method including the following steps: heating the substrate to a first temperature; exposing a silicon-containing surface of the substrate to a hydrogen-containing plasma; exposing the substrate to a first amount of MoF ₆ precursor ; Exposing the substrate to a second amount of Si ₂ H ₆ precursor; sequentially cycling the steps of exposing the substrate to a first amount and the steps of exposing the substrate to a second amount; and in this order After the cycling step, the substrate is exposed to a third amount of Si ₂ H ₆ precursor; and after the substrate is exposed to a third amount, the substrate is exposed to a second temperature between 500°C and 550°C. The substrate is annealed.

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