Method for depositing silicon nitride film in substrate groove

Abstract

A method of depositing a silicon nitride film is provided. The method may include the steps of: (a) placing a substrate on a susceptor in a reaction chamber; wherein the substrate comprises a trench; (b) introducing a silicon precursor into the reaction space; (c) exposing the substrate to a nitrogen-containing gas to purge the excess silicon precursor and by-products; (d) introducing a silicon precursor into the reaction space; (e) exposing the substrate to a nitrogen-containing gas to purge the excess silicon precursor and by-products; (f) exposing the substrate to a reactive species generated by the plasma from the nitrogen-containing gas; and (g) exposing the substrate to a nitrogen-containing gas to purge excess reactive species and by-products.

Description

Technical Field

[0001] The present disclosure generally relates to methods for forming silicon nitride films. More specifically, examples of the present disclosure relate to methods for forming silicon nitride films in trenches within a substrate. Background Art

[0002] In the manufacturing process of large-scale integrated circuits (LSI), several processes are used to form sidewalls in trenches. Sidewalls serve as spacers or to block etching of structures from the side surfaces of the trench. Sidewalls can be formed by depositing a conformal film on the surface of the trench.

[0003] Silicon nitride (SiN) films can be used as sidewalls. One method for forming SiN films is a plasma enhanced atomic layer deposition (PEALD) process. SiN can be formed by providing a silicon-containing precursor and using N2 to generate a plasma. An exemplary method is disclosed in U.S. Patent No. US10,424,477, which is incorporated herein by reference.

[0004] There is a need to improve the conformality of SiN films in trenches of a substrate.

[0005] Any discussion set forth in this section (including discussions of problems and solutions) has been included in this disclosure merely for the purpose of providing context for the disclosure and should not be construed as an admission that any or all of the discussions were known or otherwise constituted prior art at the time the invention was made. Summary of the Invention

[0006] This summary is provided to introduce a selection of concepts in a simplified form. These concepts are further described in detail in the detailed description of example embodiments of the present disclosure below. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

[0007] According to an exemplary embodiment of the present disclosure, a method for forming a silicon nitride thin film is provided. The method may include the following steps: (a) placing a substrate on a susceptor in a reaction chamber; wherein the substrate includes a trench; (b) introducing a silicon precursor into the reaction space; (c) exposing the substrate to a nitrogen-containing gas to purge excess silicon precursor and byproducts; (d) introducing the silicon precursor into the reaction space; (e) exposing the substrate to a nitrogen-containing gas to purge excess silicon precursor and byproducts; (f) exposing the substrate to reactive species generated by plasma from the nitrogen-containing gas; and (g) exposing the substrate to the nitrogen-containing gas to purge excess reactive species and byproducts.

[0008] According to further exemplary embodiments of the present disclosure, the nitrogen-containing gas may be provided continuously.

[0009] According to another exemplary embodiment of the present disclosure, the method may further include step (h): introducing a hydrogen-containing gas during step (b).

[0010] According to another exemplary embodiment of the present disclosure, the method may further include step (i): introducing a hydrogen-containing gas from before step (b) to the end of step (c).

[0011] According to further exemplary embodiments of the present disclosure, steps (i), (b), and (c) may be repeated N times, and steps (d) to (g) may be repeated M times.

[0012] According to further exemplary embodiments of the present disclosure, the silicon precursor may include at least one of HSiI3, H2SiI2, H3SiI, H2Si2I4, H4Si2I2, H5Si2I, H2SiCl2, or H2SiBr2.

[0013] According to further exemplary embodiments of the present disclosure, the method may be performed at a temperature between 275°C and 550°C.

[0014] According to further exemplary embodiments of the present disclosure, the method may be performed at a pressure between 2 Torr and 22.5 Torr.

[0015] According to further exemplary embodiments of the present disclosure, the RF power of the plasma may be between 100W and 2000W.

[0016] According to further exemplary embodiments of the present disclosure, the silicon nitride thin film may exhibit more than 90% conformality.

[0017] According to another exemplary embodiment of the present disclosure, conformality may be a ratio of the sidewall thickness at a point 110 nm from the top in the trench depth direction to the film thickness at the top of the trench, multiplied by 100.

[0018] According to further exemplary embodiments of the present disclosure, the duration of step (b) may be between 0.3 and 3 seconds.

[0019] According to further exemplary embodiments of the present disclosure, the duration of step (c) may be between 0.1 and about 1.5 seconds.

[0020] According to further exemplary embodiments of the present disclosure, the duration of step (d) may be between 0.3 and about 3 seconds.

[0021] According to further exemplary embodiments of the present disclosure, the duration of step (e) may be between 0.1 and about 1.5 seconds.

[0022] According to further exemplary embodiments of the present disclosure, the duration of step (f) may be between 3 and about 30 seconds.

[0023] According to further exemplary embodiments of the present disclosure, the duration of step (g) may be between 0.1 and about 2 seconds. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] A more complete understanding of exemplary embodiments of the present disclosure can be obtained by referring to the detailed description and claims when considered in conjunction with the following illustrative drawings.

[0025] Figure 1 A method according to an exemplary embodiment of the present disclosure is shown.

[0026] Figure 2 A schematic diagram showing a structure according to an exemplary embodiment of the present disclosure.

[0027] Figure 3 A timing sequence according to an exemplary embodiment of the present disclosure is shown.

[0028] Figure 4 Another timing sequence according to an exemplary embodiment of the present disclosure is shown.

[0029] Figure 5 Another timing sequence according to an exemplary embodiment of the present disclosure is shown.

[0030] Figure 6 The timing sequence in the prior art is shown.

[0031] Figure 7 Shown Figure 6 Schematic diagram of step 402 in FIG.

[0032] Figure 8 Shown Figure 5 Schematic diagram of steps 301 and 302 in FIG.

[0033] Figure 9 A scanning transmission electron microscope image of a structure according to an exemplary embodiment of the present disclosure is shown.

[0034] Figure 10 Additional scanning transmission electron microscope images of structures according to exemplary embodiments of the present disclosure are shown.

[0035] Figure 11 A plasma reactor system according to an exemplary embodiment of the present disclosure is shown.

[0036] It should be understood that the elements in the drawings are illustrated for simplicity and clarity and are not necessarily drawn to scale. For example, the dimensions of some elements in the drawings may be exaggerated relative to other elements to help understand the illustrated embodiments of the present disclosure. DETAILED DESCRIPTION

[0037] Although certain embodiments and examples are disclosed below, those skilled in the art will appreciate that the invention extends beyond the specifically disclosed embodiments and / or uses of the invention and obvious modifications and equivalents thereof. Accordingly, it is intended that the scope of the disclosed invention should not be limited by the specific disclosed embodiments described below.

[0038] As used herein, the term "substrate" may refer to any underlying material or materials, including any underlying material or materials that can be modified or on which a device, circuit, or film can be formed. A "substrate" can be continuous or discontinuous; rigid or flexible; solid or porous; and combinations thereof. A substrate can be in any form, such as a powder, a sheet, or a workpiece. Sheet-form substrates can include wafers of various shapes and sizes. Substrates can be made of semiconductor materials, including, for example, silicon, silicon germanium, silicon oxide, gallium arsenide, gallium nitride, and silicon carbide.

[0039] As an example, a substrate in powder form may have applications in pharmaceutical manufacturing. A porous substrate may comprise a polymer. Examples of workpieces may include medical devices (e.g., stents and syringes), jewelry, tooling, components for battery manufacturing (e.g., anodes, cathodes, or separators), or components for photovoltaic cells.

[0040] The continuous substrate may extend beyond the boundaries of the processing chamber in which the deposition process occurs. In some processes, the continuous substrate may be moved through the processing chamber, such that the process continues until the end of the substrate is reached. The continuous substrate may be supplied from a continuous substrate feed system to allow for the manufacture and output of the continuous substrate in any suitable form.

[0041] Non-limiting examples of continuous substrates may include sheets, nonwoven films, rolls, foils, meshes, flexible materials, bundles of continuous filaments or fibers (eg, ceramic fibers or polymer fibers).The continuous substrate may also include a carrier or sheet on which a discontinuous substrate is mounted.

[0042] The illustrations presented herein are not intended to be actual views of any particular material, structure, or device, but are merely idealized representations used to describe embodiments of the present disclosure.

[0043] The specific embodiments shown and described are illustrative of the present invention and its best mode and are not intended to limit the scope of the various aspects and embodiments in any way. In fact, for the sake of brevity, the conventional manufacturing, connection, preparation and other functional aspects of the system may not be described in detail. In addition, the connecting lines shown in the various figures are intended to represent exemplary functional relationships and / or physical connections between the various elements. Many alternative or additional functional relationships or physical connections may exist in actual systems and / or may not exist in some embodiments.

[0044] It should be understood that the configurations and / or approaches described herein are exemplary in nature, and these specific embodiments or examples should not be considered limiting, as many variations are possible. The specific routines or methods described herein may represent one or more of any number of processing strategies. Thus, the various actions shown may be performed in the order shown, in other orders, or in some cases omitted.

[0045] The subject matter of the present disclosure includes all novel and nonobvious combinations and subcombinations of the various processes, systems and configurations, and other features, functions, acts, and / or properties disclosed herein, as well as any and all equivalents thereof.

[0046] In the present disclosure, "gas" may include materials that are gaseous at normal temperature and pressure, evaporated solids, and / or evaporated liquids, and may consist of a single gas or a mixture of gases, depending on the context. Gases introduced without passing through a gas supply unit (e.g., a shower plate, etc.) may be used, for example, to seal the reaction space, and may include sealing gases such as noble gases or other inert gases. The terms inert gas, carrier gas, and diluent gas refer to gases that do not participate in the chemical reaction to an appreciable extent when plasma power is applied and / or gases that can excite precursors.

[0047] As used herein, the terms "film" and "thin film" can refer to any continuous or non-continuous structure and material deposited by the methods disclosed herein. For example, "film" and "thin film" can include 2D materials, nanorods, nanotubes or nanoparticles or even partial or complete molecular layers or partial or complete atomic layers or clusters of atoms and / or molecules. "Film" and "thin film" can include materials or layers that have pinholes but are still at least partially continuous.

[0048] Figure 1 A method 100 according to an exemplary embodiment of the present disclosure is shown. The method 100 may include: (a) placing a substrate on a susceptor in a reaction chamber (step 101); (b) introducing a silicon precursor into the reaction space (step 102); (c) exposing the substrate to a nitrogen-containing gas (e.g., N2) to purge excess silicon precursor and byproducts (step 103); (d) introducing the silicon precursor into the reaction space (step 104); (e) exposing the substrate to a nitrogen-containing gas to purge excess silicon precursor and byproducts (step 105); (f) exposing the substrate to reactive species generated by plasma from the nitrogen-containing gas (step 106); and (g) exposing the substrate to a nitrogen-containing gas to purge excess reactive species and byproducts (step 107). According to the method 100, a thin film including silicon nitride having a desired thickness can be formed in the trench.

[0049] like Figure 1As shown, a substrate is provided into a reaction chamber of a gas phase reactor during step 101. According to an example of the present disclosure, the reaction chamber may form part of a plasma enhanced atomic layer deposition (PEALD) reactor.

[0050] During step 101, the substrate can be brought to a desired temperature, and the reaction chamber can be brought to a desired pressure, such as a temperature and pressure suitable for subsequent steps. For example, the temperature within the reaction chamber (e.g., the temperature of the substrate or substrate support) can be in a range between 275° C. and 550° C. For example, the pressure within the reaction chamber can be in a range between 2 Torr and 22.5 Torr. The substrate can include one or more features, such as grooves.

[0051] Figure 2 A schematic diagram of a structure according to an exemplary embodiment of the present disclosure is shown. During step 102, a precursor for forming a film can be introduced into a reaction chamber. Exemplary precursors can include at least one of the following: HSiI3, H2SiI2, H3SiI, H2Si2I4, H4Si2I2, H5Si2I, H2SiCl2, or H2SiBr2.

[0052] During step 103 (the shut-off purge step), a nitrogen-containing gas may be supplied to the reaction chamber to purge excess silicon precursor and byproducts. This step may reduce physical adsorption, expose unoccupied chemical adsorption sites, and increase chemical adsorption probability, thereby producing a more uniform and densely packed film.

[0053] Again, a silicon precursor may be introduced into the reaction chamber during step 104 , and a nitrogen-containing gas may be provided to the reaction chamber during step 105 , thereby purging excess silicon precursor and byproducts.

[0054] During step 106, a plasma may be generated using a direct plasma system using a radio frequency (RF) plasma source including a high frequency (HF) component and / or a low frequency (LF) component 108. By providing the plasma, the precursor reacts with the reactant to form a film. The high frequency (HF) power may have a frequency in the range of between about 13 MHz and about 27 MHz, and the low frequency (LF) power may have a frequency in the range of between about 100 kHz and about 500 kHz. The high frequency RF power may be between 100 watts and 2000 watts.

[0055] Figure 31 shows a timing sequence according to an exemplary embodiment of the present disclosure. The nitrogen-containing gas may be provided continuously. Step 102 may last between 0.3 and 3 seconds. Step 103 may last between approximately 0.1 and 1.5 seconds. Step 104 may last between 0.3 and 3 seconds. Step 105 may last between approximately 0.1 and 1.5 seconds. Step 106 may last between 3 and 30 seconds. Step 107 may last between approximately 0.1 and 2 seconds.

[0056] Figure 4 Another timing sequence according to an exemplary embodiment of the present disclosure is shown. Figure 3 The difference in the timing between the two is whether a hydrogen-containing gas (e.g., H2) is introduced simultaneously with the precursor (step 202). By adding step 103 after step 202, it can give more freedom to introduce a hydrogen-containing gas as a co-reactant, thereby resulting in an increase in GPC (growth per cycle).

[0057] Figure 5 Another timing sequence according to an exemplary embodiment of the present disclosure is shown. Figure 4 The difference in the timing of the steps 301 and 302 is whether the hydrogen-containing gas is introduced before the precursor is provided (step 301). By introducing the hydrogen-containing gas before the precursor, more active chemical adsorption sites can be promoted. Steps 301, 302, and 103 can be repeated N times, and steps 104 to 107 can be repeated M times.

[0058] Figure 6 The timing sequence in the prior art is shown. The timing sequence includes: introducing a silicon precursor into a reaction space (step 402); exposing a substrate to a nitrogen-containing gas to purge excess silicon precursor and byproducts (step 403); exposing the substrate to reactive species generated by a plasma from the nitrogen-containing gas (step 404); exposing the substrate to a nitrogen-containing gas to purge excess reactive species and byproducts (step 405); introducing a hydrogen-containing gas into the reaction space (step 406); exposing the substrate to reactive species generated by a plasma from the hydrogen-containing gas and the nitrogen-containing gas (step 407); and exposing the substrate to a nitrogen-containing gas to purge excess reactive species and byproducts (step 408).

[0059] Figure 7 Shown Figure 6 Schematic diagram of step 402 in FIG. The precursor can be SiX2H2. X can be, for example, iodine, chlorine, or bromine. Figure 7 As shown, the Xs may cause steric hindrance, which may hinder the chemical adsorption of other SiX2H2 molecules.

[0060] Figure 8 Shown Figure 5Schematic diagram of steps 301 and 302 in FIG. During step 301, a hydrogen-containing gas is introduced before providing SiX2H2. By introducing the hydrogen-containing gas, it can promote more active chemical adsorption sites. Therefore, SiX2H2 can be uniformly chemically adsorbed during step 302.

[0061] Figure 9 A scanning transmission electron microscope image of a structure according to an exemplary embodiment of the present disclosure is shown. As described, Figure 3 and Figure 4 Each of the timing sequences in the embodiment includes a step of exposing the substrate to a nitrogen-containing gas between the silicon precursor feeding steps. By adding this step, conformality and film quality on the three-dimensional structure can be improved.

[0062] Figure 10 Other scanning transmission electron microscope images of structures according to exemplary embodiments of the present disclosure are shown. As described, Figure 5 The timing sequence in

[15] includes a step of introducing a hydrogen-containing gas before the precursor. By adding this step, the conformality and film quality of the three-dimensional structure can be further improved.

[0063] Figure 11 A plasma reactor system 500 is shown according to an exemplary embodiment of the present disclosure. The plasma reactor system 500 can be used to perform one or more steps or sub-steps as described herein and / or form one or more structures or portions thereof as described herein.

[0064] Plasma reactor system 500 may include a pair of parallel, facing conductive plate electrodes 4 and 2 within interior 11 (reaction zone) of reaction chamber 3. Plasma may be ignited within reaction chamber 3 by applying HF power (e.g., 13.56 MHz or 27 MHz) and / or LF power (e.g., 450 kHz) from power supply 25 to one electrode (e.g., electrode 4) and electrically grounding the other electrode (e.g., electrode 2). A temperature regulator may be provided in lower platform 2 (lower electrode) to maintain the temperature of substrate 1 placed thereon at a desired temperature. Electrode 4 may function as a gas distribution device, such as a shower plate. Precursor gases, reactant gases, dilution gases, and the like may be introduced into reaction chamber 3 through shower plate 4 using one or more of gas lines 20, 21, and 22, respectively. Although illustrated as having three gas lines, reactor system 500 may include any suitable number of gas lines.

[0065] In the reaction chamber 3, a circular duct 13 with an exhaust line 7 may be provided, through which the gas in the interior 11 of the reaction chamber 3 can be exhausted. In addition, the transfer chamber 5 provided below the reaction chamber 3 may be provided with a sealing gas line 24 to introduce a sealing gas into the interior 11 of the reaction chamber 3 via the interior 16 (transfer zone) of the transfer chamber 5, wherein a separation plate 14 for separating the reaction zone and the transfer zone may be provided (a gate valve is omitted in this figure, through which the wafer is transferred into or out of the transfer chamber 5). The transfer chamber may also be provided with an exhaust line 6. In some embodiments, the deposition and treatment steps may be performed in the same reaction space, so that two or more (e.g., all) steps may be performed continuously without exposing the substrate to air or other oxygen-containing atmospheres.

[0066] Those skilled in the art will appreciate that the apparatus includes one or more controllers 26 that are programmed or otherwise configured to carry out one or more of the method steps described herein. As those skilled in the art will appreciate, the controllers are in communication with various power supplies, heating systems, pumps, robots, and gas flow controllers or valves of the reactor.

[0067] In some embodiments, a multi-chamber reactor (two or more sections or compartments for processing wafers positioned close to each other) may be used, wherein reactant gases and noble gases may be supplied through common lines, while precursor gases are supplied through non-common lines.

[0068] The exemplary embodiments of the present disclosure described above do not limit the scope of the present invention, because these embodiments are merely examples of embodiments of the present invention. Any equivalent embodiments are intended to fall within the scope of the present invention. In fact, in addition to those shown and described herein, various modifications of the present disclosure, such as alternative useful combinations of the elements, can become apparent to those skilled in the art from the description. Such modifications and embodiments are also intended to fall within the scope of the appended claims.

Claims

1. A method for depositing a silicon nitride film, The method comprises the following steps: (a) placing a substrate on a susceptor in a reaction chamber; wherein the substrate includes a trench; (b) introducing a silicon precursor into the reaction space; (c) exposing the substrate to a nitrogen-containing gas to purge excess silicon precursor and byproducts; (d) introducing a silicon precursor into the reaction space; (e) exposing the substrate to a nitrogen-containing gas to purge excess silicon precursor and byproducts; (f) exposing the substrate to reactive species generated by the plasma from the nitrogen-containing gas; and (g) Exposing the substrate to a nitrogen-containing gas to purge excess reactive species and byproducts.

2. The method according to claim 1, wherein The nitrogen-containing gas is continuously provided.

3. The method according to claim 1, further comprising the step (h) of introducing a hydrogen-containing gas during step (b).

4. The method according to claim 1, further comprising step (i): introducing a hydrogen-containing gas from before step (b) to the end of step (c).

5. The method according to claim 4, wherein Steps (i), (b) and (c) are repeated N times, and steps (d) to (g) are repeated M times.

6. The method according to claim 1, wherein The silicon precursor includes at least one of the following: HSiI3, H2SiI2, H3SiI, H2Si2I4, H4Si2I2, H5Si2I, H2SiCl2 or H2SiBr2.

7. The method according to claim 1, wherein The process is carried out at a temperature between 275°C and 550°C.

8. The method according to claim 1, wherein The process is carried out at a pressure between 2 Torr and 22.5 Torr.

9. The method according to claim 1, wherein The RF power of the plasma is between 100W and 2000W.

10. The method according to claim 1, wherein The silicon nitride film exhibits greater than 90% conformality.

11. The method according to claim 10, wherein: The conformality is the ratio of the sidewall thickness at a point 110 nm from the top in the trench depth direction to the film thickness at the top of the trench, multiplied by 100.

12. The method according to claim 1, wherein The duration of step (b) is between 0.3 and 3 seconds.

13. The method according to claim 1, wherein The duration of step (c) is between 0.1 and about 1.5 seconds.

14. The method according to claim 1, wherein The duration of step (d) is between 0.3 and about 3 seconds.

15. The method according to claim 1, wherein The duration of step (e) is between 0.1 and about 1.5 seconds.

16. The method according to claim 1, wherein The duration of step (f) is between 3 and about 30 seconds.

17. The method according to claim 1, wherein The duration of step (g) is between 0.1 and about 2 seconds.

18. A substrate processing apparatus for performing the steps according to claim 1.

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