Method for deposition of silicon nitride layer using pretreatment, structure formed using the method, and system for performing the method

Abstract

Methods and systems for pretreating a surface prior to the deposition of silicon nitride are disclosed. An exemplary method includes pretreating the surface by exposing it to an active species formed from one or more gases comprising nitrogen and hydrogen. The pretreatment step may additionally include exposing the surface to a silicon-containing gas.

Description

[Technical Field]

[0001] This invention generally relates to a method for forming a thin film and a structure including the aforementioned thin film. More specifically, this invention relates to a method for depositing a silicon nitride layer, a structure including the aforementioned layer, and an apparatus for depositing the aforementioned layer. [Previous Technology]

[0002] Morphological bodies formed using silicon nitride films are used in a wide variety of applications. For example, these morphological bodies can be used as insulating regions, as etch-termination regions, as spacers, as trench protection structures, and as etch-resistant protection zones in the fabrication of electronic devices.

[0003] In some applications, it may be necessary to deposit a relatively thin (e.g., less than 10 nm or less than 5 nm thick) and uniform silicon nitride film on the surface of a substrate. In addition, it is often necessary to deposit a film of uniform thickness on the three-dimensional surface of the substrate.

[0004] In some applications, plasma-enhanced deposition is used to deposit silicon nitride films to, for example, reduce deposition temperature and / or increase deposition rate. The growth of silicon nitride films by plasma-enhanced deposition is highly dependent on the material of the substrate surface. For example, in the case of depositing silicon nitride on a silicon oxide trench structure using a plasma-enhanced process, a growth of up to 4 nm can be observed. This means that for the desired 4 nm film growth, the target number of cycles equivalent to an 8 nm film can be used to deposit a 4 nm thick film. Therefore, the yield is approximately 50% of the desired yield. Once the initial layer of silicon nitride is deposited on the surface silicon nitride film, growth can be relatively uniform.

[0005] One method for shortening the growth time of plasma-enhanced silicon nitride film deposition includes increasing the time for precursor feed to the reaction chamber and increasing the time for applying radio frequency (RF) power during the initial deposition cycle of the plasma-enhanced silicon nitride deposition process. However, this method does not eliminate growth differences between different materials or materials terminated with different bond structures. Furthermore, growth differences may still exist between substrates. Additionally, such methods can cause film growth issues due to the use of precursors during the growth process.

[0006] Therefore, there is a need for improved methods and systems for forming structures including silicon nitride films. For example, there is a need for improved methods and systems for uniformly depositing silicon nitride films on the surface of a substrate (which may contain one or more materials and / or surface termination bonds). [Summary of the Invention]

[0007] Various specific examples of the present invention relate to methods for forming morphologies including silicon nitride, systems for performing the above methods, and structures including silicon nitride films. Although the ways in which various specific examples of the present invention address the deficiencies of prior methods and systems are discussed in more detail below, in general, various specific examples of the present invention provide improved methods for depositing silicon nitride using pretreatment processes. The exemplary methods described below provide relatively efficient methods for pretreating substrate surfaces to allow relatively uniform deposition growth times, even across different materials on the substrate surface and / or across different substrates. Furthermore, the exemplary methods can provide relatively uniform deposition growth across the entire morphology, such as along the height of trenches or protrusions on the substrate surface.

[0008] According to at least one embodiment of the present invention, a method of forming a silicon nitride layer includes providing a substrate in a reaction chamber; exposing the substrate to an active species formed from one or more gases including nitrogen and hydrogen; and depositing a silicon nitride layer on the substrate in the reaction chamber. The one or more gases including nitrogen and hydrogen may include, for example, one or more of nitrogen (N2), hydrogen (H2), ammonia, and / or hydrazine, which may be combined with a second gas such as argon, helium, and one or more of nitrogen. According to embodiments of these embodiments, the step of depositing the silicon nitride layer includes a plasma-enhanced deposition process. The step of exposing the substrate to the active species may include a pulsed plasma process, for example, wherein power for plasma formation is pulsed. The step of depositing the silicon nitride layer may include a cyclic process in which at least one of the reactants and precursors is exposed to plasma to form the active species. According to other embodiments, during the steps of providing precursors to the reaction chamber and forming active reactant species in the reaction chamber, the reactants continuously flow into the reaction chamber.

[0009] According to other embodiments of the present invention, a method of forming a silicon nitride layer includes providing a substrate in a reaction chamber; exposing the substrate to a silicon-containing precursor to adsorb silicosis onto the substrate surface; exposing the substrate to an active species formed from one or more gases including nitrogen and hydrogen; and depositing a silicon nitride layer on the substrate in the reaction chamber. According to embodiments of these embodiments, the silicon precursor includes silicon and hydrogen (e.g., silanes, such as silane, disilane, trisilane, etc.). The step of exposing the substrate to the active species may include a pulsed plasma process, for example, wherein power for plasma formation is pulsed. The step of depositing the silicon nitride layer may include a plasma-enhanced deposition process.

[0010] According to other specific embodiments of the present invention, the structure includes a morphology containing silicon nitride. The aforementioned morphology can be formed using the methods described herein.

[0011] According to an additional specific example of the invention, a system for performing the methods as described herein and / or for forming the structures as described herein is disclosed.

[0012] To summarize the present invention and the advantages achieved over the prior art, certain objects and advantages of the invention may have been described above. Of course, it should be understood that not all such objects or advantages need to be achieved according to any particular embodiment of the invention. Therefore, for example, those skilled in the art will understand that the invention may be practiced or performed in a manner that achieves or optimizes one or more advantages as taught or suggested herein, without achieving other objects or advantages that may be taught or suggested herein. Those skilled in the art will readily understand these and other embodiments from the following detailed description of certain embodiments with reference to the drawings; the invention is not limited to any particular embodiment disclosed.

Implementation Method

[0013] Although certain specific examples and embodiments are disclosed below, those skilled in the art will understand that the invention extends beyond the specific examples and / or uses disclosed herein and their obvious modifications and equivalents. Therefore, it is intended that the scope of the invention disclosed herein should not be limited to the specific examples described below.

[0014] As described in more detail below, embodiments of the present invention provide an improved method and system for depositing silicon nitride films on a substrate surface. An exemplary method includes using one or more pretreatment processes to provide a desired substrate surface for subsequent deposition. One or more pretreatment processes may provide reduced grow cycles or eliminate grow cycles for subsequent silicon nitride deposition, and / or may provide more uniform deposition of silicon nitride on different materials and / or materials formed using different techniques and / or materials with different thicknesses. Additionally or alternatively, embodiments of the present invention may provide an improved step coverage of the silicon nitride film deposited on a morphology on the substrate surface.

[0015] As used herein, the term "substrate" can refer to any underlying material(s) that can be used to form or on which devices, circuits, or films can be formed. A substrate can include bulk material (such as silicon (e.g., monocrystalline silicon)) and can include one or more layers covering the bulk material. Furthermore, a substrate can include various morphologies, such as trenches, vias, protrusions, etc., formed within or on at least a portion of the substrate.

[0016] As used herein, the term "cyclic deposition" can refer to the continuous introduction of precursors / reactants into a reaction chamber to deposit a layer on a substrate, and may include processing techniques such as atomic layer deposition and cyclic chemical vapor deposition. The reaction chamber may be purged after the introduction of one or more of the precursors and / or reactants.

[0017] As used herein, the term "atomic layer deposition (ALD)" can refer to a vapor deposition process in which deposition cycles (generally multiple consecutive deposition cycles) are performed in a process chamber. Typically, during each cycle, a precursor system is chemisorbed onto the deposition surface (e.g., a substrate surface that may include previously deposited material or other materials from a previous ALD cycle), forming a monolayer or sub-monolayer material that is not readily reacting with additional precursors (i.e., a self-limiting reaction). Subsequently, in some cases, reactants (e.g., another precursor or reactive gas) may be introduced into the process chamber to convert the chemisorbed precursor into the desired material on the deposition surface. The reactants can further react with the precursor. Furthermore, a purging step may be used during each cycle to remove excess precursor from the process chamber and / or excess reactants and / or reaction byproducts from the process chamber after the conversion of the chemisorbed precursor. When performed using alternating pulses of one or more precursor / reactive gases and purging (e.g., inert) gases, the term atomic layer deposition, as used herein, also means processes specified by related terms such as chemical vapor deposition, atomic layer epitaxy (ALE), molecular beam epitaxy (MBE), gas source MBE, or organometallic MBE, and chemical beam epitaxy.

[0018] As used herein, the term “cyclic chemical vapor deposition” may refer to any process in which a substrate is sequentially exposed to two or more volatile precursors, which react and / or decompose on the substrate to deposit material.

[0019] A layer comprising silicon nitride (SiN) or a silicon nitride layer may comprise, consist substantially of, or consist of silicon nitride material. A film composed of silicon nitride may include acceptable amounts of impurities (such as carbon, chlorine, or other halogens, and / or hydrogen) derived from one or more precursors used to deposit the silicon nitride layer. As used herein, SiN or silicon nitride refers to a compound comprising silicon and nitrogen. SiN may be represented as SiNx, where x varies from, for example, about 0.5 to about 2.0, wherein some Si-N bonds are formed. In some cases, x may vary from about 0.9 to about 1.7, from about 1.0 to about 1.5, or from about 1.2 to about 1.4. In some specific examples, silicon nitride is formed, wherein Si has an oxidation state of +IV, and the amount of nitride in the material may vary.

[0020] In some specific examples of the present invention, "continuously" may refer to one or more discrete physical or chemical structures that are not interrupted in vacuum, are uninterrupted in timeline, have no material insertion steps, are not changed in processing conditions, are immediately thereafter, are the next step, or have no insertion between two structures that is different from the two structures.

[0021] In this invention, any two numbers of a variable may constitute a working range of the variable, and any indicated range may include or exclude endpoints. Furthermore, any numerical value of the indicated variable (regardless of whether such numerical value is indicated by "about") may refer to an exact value or an approximate value and include equivalent values, and in some embodiments may refer to an average, median, representative value, multi-value, etc. Further, in this invention, in some specific examples, the terms "including," "constituted by," and "having" may independently mean "typically or broadly comprising," "comprising," "consisting essentially of," or "consisting of." In this invention, in some specific examples, any defined meaning does not necessarily exclude ordinary and conventional meanings.

[0022] Turning now to the figures, FIG1 illustrates a method 100 for forming a silicon nitride layer according to an exemplary embodiment of the present invention. Method 100 includes the following steps: providing a substrate in a reaction chamber (step 102); optionally exposing the substrate to a silicon-containing precursor (step 104); treating the substrate surface by exposing the substrate to an active species formed from one or more hydrogen- and nitrogen-containing gases (step 106); and depositing a silicon nitride layer on the substrate surface (step 106).

[0023] During step 102, a substrate is provided to the reaction chamber of the reactor. According to embodiments of the invention, the reaction chamber may form part of a circulating deposition or atomic layer deposition (ALD) reactor. An exemplary single-substrate reactor suitable for method 100 includes a reactor specifically designed for ALD processes, which is available from ASM International NV (Almere, The Netherlands). An exemplary suitable batch ALD reactor is also commercially available from ASM International NV. The various steps of method 100 may be carried out in a single reaction chamber or in multiple reaction chambers (such as the reaction chamber of a cluster tool), for example without exposing the substrate surface to the ambient atmosphere. The reactor including the reaction chamber may be equipped with a heater to activate the reaction by increasing the temperature of one or more of the substrate and / or reactants / precursors.

[0024] During step 102, the substrate may be brought to the temperature and pressure required for steps 104 and / or 106. For example, the temperature in the reaction chamber (e.g., the temperature of the substrate or substrate support) may be between about 50°C and about 700°C or between about 200°C and about 500°C. The pressure in the reaction chamber may be between about 0.1 and about 50 Torr.

[0025] The substrate provided during step 102 may include a surface comprising one or more materials, sometimes referred to herein as a material surface. Exemplary materials include semiconductor (e.g., Group IV) materials; metals; oxides, such as silicon oxide; metal oxides; metal nitrides; semiconductor (e.g., Group IV) nitrides, such as silicon nitride and silicon oxynitride; other dielectric materials and any combination of such materials, any of which may be thermally deposited or deposited with plasma assistance.

[0026] Step 104 can be used, for example, to improve the efficiency of method 100 or to shorten the total time of method 100. For example, the total process time for depositing a silicon nitride film (including pretreatment) can be shortened by using step 104 of method 100. According to an embodiment of the invention, the substrate may be exposed to a silicon-containing precursor during step 104 to, for example, adsorb silicon-containing molecules onto the substrate surface such that the surface is terminated by Si-H bonds. Si-H bonds can be used, for example, to form one or more low-coordinated Si=N, SiNH4, or Si-NH2 bonds on the substrate surface during subsequent pretreatment steps.

[0027] According to various embodiments of the present invention, the silicon precursor is thermally adsorbed or thermally reacted with the substrate surface. In other words, the silicon precursor is not exposed to the plasma process during step 104. Suitable silicon precursors for step 104 may include silicon and hydrogen, such as silanes, such as silanes, disylases, trisylenes, compounds containing silanes, etc. The flow rate of the silicon precursor in the reaction chamber may be, for example, in the range of about 10 sccm to about 5 slm. A carrier gas, such as nitrogen, may co-flow with the silicon precursor. The flow rate of the carrier gas in the reaction chamber may be, for example, from about 0 slm to about 50 slm. The pressure in the reaction chamber during step 104 may be between about 0.1 Torr and about 50 Torr. The substrate temperature may be between about 50°C and about 700°C. The silicon precursor may flow into the reaction chamber for a period of about 0.05 seconds to about 10 minutes. Subsequently, the flow of silicon precursor and carrier gas can be stopped and the reaction chamber can be purged.

[0028] During step 106, the substrate is exposed to an active species formed from one or more gases including nitrogen and hydrogen. During this step, NH and / or N-H2 groups may be formed on the substrate surface. The formation of these groups on the substrate surface promotes subsequent (e.g., CVD or cycling) deposition of silicon nitride on the substrate surface, even when the surface contains different materials.

[0029] For example, the substrate surface may include native oxide and / or a thick silicon oxide film. Without pretreatment (e.g., steps 104 and 106 may be selected), as described herein, the growth period for plasma-enhanced deposition of silicon nitride can be highly correlated with the quality of the underlying substrate. For example, silicon nitride deposition on native silicon oxide can be achieved with relatively low growth, while silicon nitride growth on a thicker, high-quality silicon oxide film can exhibit much higher growth. However, using step 106 alone or in combination with step 104 can reduce or eliminate the growth period on both surfaces, thereby allowing for more uniform deposition of silicon nitride on the surface, whether on the same substrate or on different substrates. According to embodiments of the invention, when one or more substrates have multiple material surfaces to be pretreated, the pretreatment time should be selected to be greater than the minimum pretreatment time of the surface with the longer pretreatment time, such that the surface termination of the entire material surface is substantially similar. According to at least some specific examples of the invention, the growth difference between two or more material surfaces is less than 0.5 nm. In some cases, the pretreatment time can be less than 45 seconds. As discussed in more detail below, another advantage of the method described herein is the improved uniformity of the silicon nitride film deposited on or within a substrate on a topology. For example, silicon nitride can be deposited on one or more topologies, i.e., high aspect ratio topologies (e.g., aspect ratios greater than or equal to 10 or 12), with step coverage exceeding approximately 90%, or exceeding approximately 95%, or exceeding approximately 99%, or even substantially equal to 100%. As used herein, the term "step coverage" is defined as the percentage of the metal oxide film thickness on the sidewalls of a topology (e.g., a trench or protrusion) to the metal oxide thickness on the horizontal surface of the substrate. In such cases, the timing of the pretreatment process can be selected to obtain the desired step coverage. According to other embodiments, the pretreatment substantially homogenizes the surface adhesion of the treated surface.

[0030] According to embodiments of the present invention, one or more gases including nitrogen and hydrogen include at least one of nitrogen (N2) and hydrogen (H2), such as nitrogen or a mixture of nitrogen and hydrogen. The individual concentrations of nitrogen and hydrogen can be selected such that the amount of nitrogen-reactive species is saturated. According to a particular embodiment, one or more gases including nitrogen and hydrogen include more than about 0.3 volume (V) percent hydrogen or about several V% (e.g., 2 V% or higher) to about 100 V% hydrogen in nitrogen. Unless otherwise indicated, gas percentages refer to volume percentages.

[0031] In some cases, the gas comprising nitrogen and hydrogen may include one or more of ammonia and hydrazine. In some cases, the gas comprising nitrogen and hydrogen may further include a second gas. The second gas may include one or more of argon, helium, and nitrogen. The mixture comprising the second gas may include about 0 to almost 100 percent of the second gas. For illustration, the gas comprising nitrogen and hydrogen may include nitrogen and hydrogen; nitrogen and ammonia; nitrogen, hydrogen, and ammonia; or any of these and one or more of helium and argon.

[0032] In some cases, pulsed plasma formation power may be required to, for example, reduce any damage to the substrate surface that may occur during the pretreatment process, while still achieving lower growth and relatively high throughput. Figure 3(a) illustrates the constant power applied during the pretreatment step. Figure 3(b) illustrates the pulsed power applied during step 106. The on-power duration can range from about 10% to about 90%. The off-power duration can range from about 10% to about 90%. The pulse frequency can range from about 1000 Hz to about 100000 Hz. The on-time duty cycle can be greater than 50%. The power frequency used to form plasma during step 106, which exposes the substrate to active species, can be between about 100 kHz and about 2.45 GHz.

[0033] During step 108, silicon nitride is deposited on the surface of the pretreated substrate. According to an embodiment of the invention, step 108 is performed without vacuum disruption or exposure of the substrate to the ambient atmosphere. According to other embodiments, step 108 is performed in the same reaction chamber used for one or more of steps 102 to 106. In specific examples of using different reaction chambers for steps 106 and 108, the substrate can be transferred from the first reaction chamber (for pretreatment) to the second reaction chamber (for silicon nitride deposition) without exposure to the ambient atmosphere. In other words, the method of the invention can include processing materials and forming a silicon nitride film on a substrate in the same semiconductor processing apparatus. The semiconductor processing apparatus used in steps 106 and 108 may include a clustering tool comprising two or more reaction chambers and may further include a transfer chamber through which the substrate can be transferred between the first and second reaction chambers. In some specific examples, the environment of the transfer chamber can be controlled, that is, the temperature, pressure, and ambient gases can be controlled so that the substrate is not exposed to the ambient atmosphere after step 106 and before step 108. Similarly, when step 104 is used, the substrate may not be exposed to the surrounding environment between steps 104 and 106.

[0034] Step 108 of depositing the silicon nitride layer may include a CVD or cyclic deposition process. A cyclic (e.g., ALD) cycle may include exposing the substrate to a precursor (also referred to as a reactant); removing any unreacted precursors and / or reaction byproducts from the reaction space; and exposing the substrate to the reactant, followed by a second removal step. The precursor may include, for example, a halogen-based precursor. Exemplary silicon halides include silicon tetraiodide (SiI4), silicon tetrabromide (SiBr4), silicon tetrachloride (SiCl4), hexachlorodisilazane (Si2Cl6), hexaiododisilazane (Si2I6), and octaiodotrisilane (Si3I8). In some cases, the precursor may include the same or similar precursor used during step 104. The second reactant may include a nitrogen source, such as nitrogen, ammonia, hydrazine, or alkylhydrazine, wherein the alkylhydrazine may refer to a hydrazine derivative, which may contain an alkyl functional group and may also contain additional functional groups. Non-limiting embodiments of alkyl hydrazines may include at least one of tert-butylhydrazine (C4H9N2H3), methylhydrazine (CH3NHNH2), or dimethylhydrazine (CH3)2N2NH2. A hydrogen-containing gas, such as hydrogen, may be introduced into the reaction chamber along with nitrogen. According to at least some embodiments of the invention, plasma is not formed when the precursor is introduced into the reaction chamber.

[0035] During the purging step, the precursors / reactants can be temporally separated by an inert gas such as argon (Ar), nitrogen (N2), or helium (He) and / or vacuum pressure to prevent or slow down gas-phase reactions between reactants and to achieve a self-saturated surface reaction. However, in some specific examples, the substrate can be moved to separate contact with the first and second gas-phase reactants. For example, in the case of ALD, since the reaction is self-saturable, strict temperature control of the substrate and precise dosage control of the precursor are not required. However, it is desirable that the substrate temperature prevents the incident gas species from condensing into a monolayer or multiple monolayers or from thermally decomposing on the surface.

[0036] In some specific examples, providing a silicon source precursor may include pulsating one or more silicon precursors on the substrate for a period of time between about 0.5 seconds and about 30 seconds, or between about 0.5 seconds and about 10 seconds, or between about 0.5 seconds and about 5 seconds. Furthermore, during the pulsating of the silicon halide source on the substrate, the flow rate of the silicon halide source may be less than 2000 sccm.

[0037] In some specific examples, the reactants may be provided in a period of time on the substrate during which one or more reactants are pulsed for a duration between about 0.5 seconds and about 30 seconds, or between about 0.5 seconds and about 10 seconds, or between about 0.5 seconds and about 5 seconds. During the pulsed nitrogen source on the substrate, the nitrogen source flow rate may be less than 4000 sccm, or less than 2000 sccm, or less than 1000 sccm, or even less than 250 sccm.

[0038] According to other embodiments of the present invention, depositing a silicon nitride layer 108 may include forming active species. For example, step 108 may include forming active reactive species by simultaneously introducing reactive substances into the reaction chamber while forming plasma. Plasma may be formed using, for example, a capacitively coupled plasma (CCP) source, an inductively coupled plasma (ICP) source, or a remote plasma (RP) source. The power used to generate the plasma may be in the range of about 10 W to about 4 kW or about 400 W to about 1 kW. The time of step 108 (e.g., the time for activating the plasma) may be in the range of about 1 millisecond to about 5 minutes. The power frequency used to form the plasma during the step of forming active reactive species in the reaction chamber may be between about 100 kHz and about 2.45 GHz.

[0039] The cyclic deposition (e.g., ALD) process for depositing a silicon nitride layer (step 108) can be repeated one or more times until the desired thickness of the silicon nitride layer is achieved. The cyclic deposition process can be used to form silicon nitride films with thicknesses between about 0.3 nm and about 30 nm or between about 1 nm and about 10 nm.

[0040] FIG2 illustrates a structure 200 according to an exemplary specific example of the present invention. The structure 200 includes a substrate 202, a material 204 having trenches 208 formed therein, and a silicon nitride layer 206 deposited in the trenches (morphology) 208.

[0041] The substrate 202 may include any suitable material, such as semiconductor materials and materials commonly used to form semiconductor devices. For example, the substrate 202 may be or may include silicon, other Group IV semiconductor materials, Group III-V semiconductors and / or Group II-VI semiconductors.

[0042] Material 204 may include any of the substrate materials mentioned above. For example, substrate 204 may include oxides, such as group IV or metal oxides; or nitrides, such as group IV or metal nitrides. Silicon nitride layer 206 may include a silicon nitride layer deposited using a PEALD process, such as the PEALD process described herein.

[0043] Figure 4 illustrates the differences in film thickness measurements of silicon nitride films deposited on silicon and silicon oxide morphologies for structures formed without pretreatment, structures formed by applying constant power during pretreatment, and structures formed by applying pulsed power during pretreatment. This illustrative data indicates that the difference in film thickness between films deposited in SiO trenches and silicon trenches without pretreatment is significantly greater than that between films deposited under constant power or pulsed power pretreatment.

[0044] Figure 5 illustrates the film thickness measurement results, showing the trench reduction at the trench inlet for processes with no pretreatment and with pretreatment via constant power plasma and pulsed plasma processes. As shown, the trench reduction at the inlet of the morphology in the process without pretreatment is less than the reduction in pulsed power pretreatment, which is less than the reduction in constant power pretreatment.

[0045] Turning now to FIG. 15, a reactor system 1500 according to an exemplary specific example of the present invention is illustrated. The reactor system 1500 can be used to perform one or more steps or sub-steps as described herein and / or to form one or more structures or portions thereof as described herein.

[0046] The reactor system 1500 includes a pair of parallel and facing conductive plate electrodes 4, 2 within the interior 11 (reaction zone) of the reaction chamber 3. Plasma can be generated within the reaction chamber 3 by applying, for example, HRF power (e.g., 100 kHz, 13.56 MHz, 27 MHz, 2.45 GHz, or any value between therewith) from a power source 25 to one electrode (e.g., electrode 4) and electrically grounding the other electrode (e.g., electrode 2). A temperature regulator is provided in the lower platform 2 (lower electrode), and the temperature of the substrate 1 placed thereon can be maintained at a desired temperature. Electrode 4 can act as a gas distribution device (such as a spray plate). One or more of gas lines 20, 21, and 22 can be used, and reactant gases, dilution gases (if present), precursor gases, etc., can be introduced into the reaction chamber 3 via the spray plate 4. Although illustrated with three gas lines, the reactor system 1500 may include any suitable number of gas lines.

[0047] In the reaction chamber 3, a circular pipe 13 with an exhaust line 7 is provided to discharge gas from the interior 11 of the reaction chamber 3. Additionally, a transfer chamber 5 installed below the reaction chamber 3 is provided with a sealing gas line 24 to introduce sealing gas into the interior 11 of the reaction chamber 3 via the interior 16 (transfer zone) of the transfer chamber 5. A partition plate 14 is provided to separate the reaction zone from the transfer zone (a gate valve is omitted from this figure; the substrate is transferred to or from the transfer chamber 5 via this gate valve). The transfer chamber is also provided with an exhaust line 6. In some specific examples, the deposition and / or surface treatment steps are performed in the same reaction space so that two or more (e.g., all) of the steps can be performed continuously without exposing the substrate to air or other oxygen-containing atmospheres.

[0048] In some specific examples, the continuous flow of carrier gas to reaction chamber 3 can be accomplished using a flow-through system (FPS), wherein the carrier gas line is provided with a branch line having a precursor reservoir (bottle), and the main line and the branch line are switched. When it is intended to feed only carrier gas to the reaction chamber, the branch line is closed; when it is intended to feed both carrier gas and precursor gas to the reaction chamber, the main line is closed, and the carrier gas flows through the branch line and exits from the bottle together with the precursor gas. In this way, the carrier gas can continuously flow into the reaction chamber without substantial pressure fluctuations, and the precursor gas can be pulsed by switching between the main line and the branch line.

[0049] The reactor system 1500 may include one or more controllers 26, which are programmed or otherwise configured to enable one or more method steps as described herein. As will be understood by those skilled in the art, the one or more controllers 26 are coupled to various power supplies, heating systems, pumps, robotic systems, and airflow controllers or valves of the reactor.

[0050] In some specific examples, a dual-chamber reactor (two sections or compartments for processing substrates that are closely mounted to each other) can be used, wherein reactant gases and rare gases can be supplied via a common pipeline, while precursor gas systems are supplied via a non-common pipeline.

[0051] Specific Embodiments

[0052] The embodiments provided below are intended to be illustrative only. These embodiments are not intended to limit the scope of the invention or the patent application.

[0053] Example 1: N2 / H2 pretreatment

[0054] Two blanket-covered samples (a silicon substrate and a substrate with a thermally oxidized silicon layer thereon) are introduced into the deposition reactor. The samples are heated by a base heater mounted on a base heater heated to 450°C. The gap between the lower electrode (base heater) and the upper electrode (cluster gas introduction system) is 12 mm. The pressure is increased to 350 Pa by introducing nitrogen and hydrogen. The total flow rate is 10 slm and the H2 concentration varies between 0%, 0.3%, 3%, and 10%. 1.5 slm of N2 is introduced from the bottom of the reaction chamber to prevent or slow the introduction of hydrogen below the base unit. 600 W of HRF power is applied between the upper and lower electrodes for 30 seconds, 60 seconds, 1.5 minutes, or 2 minutes. The nitrogen flow rate is increased to 12 slm and the H2 flow rate is adjusted to 5 sccm. The pressure in the reaction chamber is increased to 2000 Pa while the gap remains at 12 mm. Repeat the following steps to achieve the desired film thickness deposition: Introduce the silicon precursor into the chamber using 2 slm N2 carrier gas via a tube heated at 75°C. Feed time is 0.3 seconds. Purge the reaction chamber with an N2 gas flow for 1 second. Turn on 800W RF power for 1.6 seconds. During this time, the reactants (nitrogen) continue to flow. Purge the reaction chamber for 0.1 seconds.

[0055] Figure 6 illustrates the evolution of the thickness difference between the thermally oxidized silicon and the silicon blanket coating for different treatment times and H2 concentrations in nitrogen. It can be observed that increasing the pretreatment time reduces the thickness difference, regardless of the hydrogen concentration. Furthermore, using a larger hydrogen content, for example, exceeding 3%, provides advantages over simple nitrogen plasma treatment.

[0056] Example 2: 10%-20% hydrogen in nitrogen plasma pretreatment

[0057] Two grooved patterned samples (a silicon substrate and a substrate with silicon oxide) were introduced into the reaction chamber of the reactor. Both substrates included a grooved structure with an aspect ratio of 12. The substrates were mounted on a base heater and heated to a temperature of 450°C. The gap between the lower electrode (base heater) and the upper electrode (burst-type gas introduction system) was 12 mm. The pressure was increased to 350 Pa by introducing nitrogen and hydrogen. The total flow rate was 5 slm or 10 slm and the H2 flow rate was fixed at 1 slm. 1.5 slm of N2 was introduced from the bottom of the reaction chamber to slow down / prevent hydrogen from being introduced below the base unit. 800 W of HRF power was applied between the upper and lower electrodes for different durations between 0 seconds and 150 seconds. The nitrogen flow rate was increased to 12 slm and the H2 flow rate was adjusted to 5 sccm. The pressure was increased to 2000 Pa and the gap was maintained at 12 mm.

[0058] Repeat the following deposition steps to achieve the desired film thickness. Introduce the silicon precursor into the chamber using 2 slm N2 carrier gas via a tube heated at 75°C. Feed time is 0.3 seconds. Purge the reaction chamber with N2 gas flow for 1 second. Turn on 800W RF power for 1.6 seconds. Purge the reaction chamber for 0.1 seconds.

[0059] After the final deposition cycle, the reaction chamber was purged and evacuated, and the sample was removed from the reactor. The sample was then analyzed by STEM. Locations AD are shown in Figure 11.

[0060] Figures 7 and 8 illustrate the evolution of top and sidewall thicknesses for different pretreatment times and H2 concentrations (10% and 20%, respectively). It can be seen that for a 10% H2 concentration, a treatment duration of approximately 70 seconds is sufficient for the growth and cultivation of silicon and silicon oxide trenches (Figure 7). For a 20% H2 concentration, this treatment duration can be reduced to 45 seconds (Figure 8). Furthermore, it can be observed that the thickness difference between locations A, C, and D is reduced compared to the case without pretreatment, and thus a higher step coverage is observed.

[0061] Example 3: OES analysis during N2 / H2 plasma pretreatment

[0062] The base heater is heated to 450°C, the upper electrode is heated to 200°C, and the chamber wall is heated to 150°C. The gap between the lower electrode (base heater) and the upper electrode (cluster nozzle gas introduction system) is 12 mm.

[0063] By introducing nitrogen and hydrogen, the pressure inside the reaction chamber is increased to 350 Pa. The total flow rate is 5 slm or 10 slm and the H2 concentration varies between 0% and 20%. 1.5 slm of N2 is introduced from the bottom of the reaction chamber to prevent / decelerate the introduction of hydrogen into the base unit below.

[0064] An HRF power of 300W or 600W was applied between the upper and lower electrodes for 45 seconds. Reactive species emitted during plasma treatment were analyzed using an optical emission spectroscopy (OES) unit connected to the chamber via a fiber optic unit fixed to a viewing port on the chamber wall. Referring to Figure 9, N2+ (emission wavelength: 391 nm) emission was observed to be highly correlated with H2 concentration. Compared to pure N2 plasma, emission increased and saturated by several percent from H2. Increasing the HRF power favored the emission of H2-derived reactive species as Hα (emission wavelength: 656 nm), as shown in Figure 10. No saturation behavior was observed, implying that increasing the H2 ratio is an efficient way to increase Hα species.

[0065] Example 4: Ar / NH3 plasma pretreatment under SiNPEALD process conditions

[0066] Two trench patterned samples (a silicon substrate and a substrate having a SiOx layer thereon) are introduced into the reaction chamber of the reactor. Both substrates include trench structures (morphological bodies) with an aspect ratio of 10.

[0067] The sample is heated by heating the base heater to 450°C. The gap between the lower electrode (base heater) and the upper electrode (cluster gas introduction system) is 10 mm. The pressure in the reaction chamber is increased to 300 Pa by introducing 6.75 slm of argon and 0.25 slm of ammonia. 1.5 slm of N2 is introduced from the bottom of the reactor to prevent / decelerate the introduction of argon and ammonia below the base unit.

[0068] A 300 W HRF power is applied between the upper and lower electrodes for a duration of 45 seconds (1) or 230 seconds (2). The argon and ammonia flows are gradually stopped, and a flow of 12 slm N2 and 5 sccm H2 is introduced into the reaction chamber. The pressure inside the reaction chamber is then increased to 2000 Pa with a gap of 12 mm.

[0069] Repeat the following steps to achieve the desired film thickness deposition: Introduce the silicon precursor into the chamber using 2 slm N2 carrier gas via a tube heated at 75°C. The feed time is 0.3 seconds. Then purge the reaction chamber with an N2 gas flow for 1 second. Turn on 800W RF power for 1.6 seconds. Then purge the reaction chamber for 0.1 seconds.

[0070] After deposition is complete, the chamber is purged and evacuated, and the sample is removed from the reactor.

[0071] The sample was analyzed by scanning transmission electron microscopy (STEM). Figure 12 illustrates the evolution of the film thickness on the top and sidewalls as the pretreatment time increased. As shown, without pretreatment, there is a difference of approximately 3 nm between the films deposited on the silicon substrate and the substrate including the SiOx layer; for pretreatment duration 1, this difference decreases to 2 nm, and for duration 2, it decreases to less than 0.5 nm. It is also noted that for pretreatment time duration 2, good uniformity of film thickness is obtained across the structures. In Figure 12, duration 1 is 45 seconds and duration 2 is 230 seconds.

[0072] Example 5: N2 / NH3 plasma pretreatment between SiNPEALD processes

[0073] Two trench patterned samples (a silicon substrate and a substrate having SiOx on it) are introduced into the reaction chamber. Both substrates include trench structures with an aspect ratio of 10.

[0074] The sample is heated by heating the base heater to 450°C. The gap between the lower electrode (base heater) and the upper electrode (burst head gas introduction system) is 12 mm.

[0075] By introducing 9.75 slm of nitrogen and 0.25 slm of ammonia, the pressure in the reaction chamber is increased to 350 Pa. 1.5 slm of N2 is introduced from the bottom of the reactor to prevent / decelerate the introduction of ammonia into the base unit below.

[0076] A duration of 45 seconds or 240 seconds of HRF power of 520W is applied between the upper and lower electrodes.

[0077] The ammonia flow gradually stops, the N2 flow increases to 12 slm, and a 5 sccm H2 flow is introduced into the reaction chamber. The pressure inside the reaction chamber increases to 2000 Pa while the gap remains at 12 mm.

[0078] Repeat the following steps to achieve the desired film thickness deposition: Introduce the silicon precursor into the reaction chamber using 2 slm N2 carrier gas via a tube heated at 75°C. Feed time is 0.3 seconds. Purge the reaction chamber with N2 gas flow for 1 second. Turn on 800W RF power for 1.6 seconds. Purge the reaction chamber for 0.1 seconds.

[0079] After deposition, the chamber was purged and evacuated, and the sample was removed from the reactor. The sample was then analyzed by STEM. Figure 13 illustrates the evolution of the film thickness on the top and sidewalls as the pretreatment time increased. Without pretreatment, there was a difference of approximately 3 nm between the films deposited on the silicon substrate and the substrate including SiOx; for pretreatment duration 1, this difference decreased to approximately 1 nm, and for duration 2, it decreased to less than 0.6 nm. It is also noted that good uniformity of film thickness was obtained on each structure for pretreatment times of duration 1 and duration 2. In Figure 13, duration 1 is 45 seconds and duration 2 is 240 seconds.

[0080] Example 6: Comparison of Ar / NH3 plasma pretreatment alone and silane thermal adsorption with Ar / NH3 plasma pretreatment

[0081] Two trench patterned samples (a silicon substrate and a substrate having SiOx on it) are introduced into the reaction chamber. Both substrates include trench structures with an aspect ratio of 10.

[0082] The sample is heated by heating the base heater to 450°C. The gap between the lower electrode (base heater) and the upper electrode (burst head gas introduction system) is 10 mm.

[0083] By introducing 4 slm of nitrogen and 100 sccm of silane, the pressure is brought to 2000 Pa. After the pressure stabilizes, the nitrogen and silane flow continues for 15 seconds. Subsequently, the gas flow is stopped and the reaction chamber is purged.

[0084] The pressure in the reaction chamber is increased to 300 Pa by introducing 6.75 slm of argon and 0.25 slm of ammonia. 1.5 slm of N2 is introduced from the bottom of the reactor to prevent / mitigate the introduction of argon and ammonia into the base unit below.

[0085] A 300W HRF power was applied between the upper and lower electrodes for a duration of 45 seconds. The argon and ammonia flows were gradually stopped, and a flow of 12 slm N2 and 5 sccm H2 was introduced into the reaction chamber. The pressure inside the reaction chamber was then increased to 2000 Pa with a gap of 12 mm.

[0086] Repeat the following steps to achieve the desired film thickness. Introduce the silicon precursor into the chamber using 2 slm N2 carrier gas through a tube heated to 75°C. The feed time is 0.3 seconds. Purge the reaction chamber with an N2 gas flow for 1 second. Turn on 800W RF power for 1.6 seconds. Then purge the reaction chamber for 0.1 seconds.

[0087] After deposition is complete, purge the chamber and remove the sample from the reactor.

[0088] Samples were analyzed by STEM. Figure 14 illustrates the evolution of the top and sidewall film thickness with and without the addition of the silane adsorption step. Without the silane adsorption step, for a pretreatment duration of 1, there was a difference of approximately 2 nm between the films deposited on the silicon substrate and the substrate including SiOx; when the silane adsorption step was added, the growth result decreased to less than 0.5 nm. Note also that good step coverage was maintained. In Figure 14, duration 1 is 45 seconds.

[0089] The illustrative examples of the invention described above do not limit the scope of the invention, as these examples are merely embodiments of the invention, and the scope of the invention is defined by the appended claims and their legal equivalents. Any equivalent examples are intended to be within the scope of the invention. In fact, in addition to what is shown and described herein, various modifications to the invention (such as alternatives to the described elements) will be apparent to those skilled in the art from this specification. Such modifications and examples are also intended to fall within the scope of the appended claims. [Simplified Explanation of the Diagram]

[0091] When considered in conjunction with the accompanying illustrative drawings, a more complete understanding of the exemplary embodiments of the present invention can be obtained by referring to the embodiments and the claims. Figure 1 illustrates a method for forming a silicon nitride layer according to at least one embodiment of the present invention. Figure 2 illustrates a structure according to at least one embodiment of the present invention. Figure 3 illustrates an RF power application according to an embodiment of the present invention. Figure 4 illustrates the difference in film thickness of silicon nitride films deposited with and without a pretreatment step according to an embodiment of the present invention. Figure 5 illustrates the difference in trench width of silicon nitride films deposited with and without a pretreatment step according to an embodiment of the present invention. Figure 6 illustrates the change in the difference in silicon nitride thickness deposited on silicon oxide and silicon blanket coatings with pretreatment time for varying hydrogen concentrations. Figures 7 and 8 illustrate the change in top and sidewall film thickness with pretreatment time. Figure 9 illustrates the N2+ (391 nm) adsorption peak according to OES during pretreatment. Figure 10 illustrates the Hα (656 nm) adsorption peak of OES during pretreatment. Figure 11 illustrates the film thickness points on the structure. Figures 12 and 13 illustrate the changes in top and sidewall film thickness with pretreatment time. Figure 14 illustrates a comparison of Ar / NH3 plasma pretreatment alone and a combination of silane thermal adsorption and Ar / NH3 plasma pretreatment. Figure 15 illustrates a system according to an exemplary embodiment of the invention. It will be understood that the elements in the figures are drawn for simplicity and clarity and are not necessarily drawn to scale. For example, the dimensions of some elements in the figures may be exaggerated relative to other elements to help improve the understanding of the specific embodiments illustrated in the invention.

Claims

1. A method for forming a silicon nitride layer, the method comprising the steps of: providing a substrate in a reaction chamber; exposing the substrate to a plurality of active species formed by one or more hydrogen-containing and nitrogen-containing gases, wherein NH and / or N-H2 groups are formed on the surface of the substrate; and depositing a silicon nitride layer over one or more trenches on the substrate in the reaction chamber, wherein the step of exposing the substrate to the active species includes a pulsed plasma process, during which plasma power is pulsed out, and the pulsed plasma process includes a pulsed plasma with an on-time duty cycle greater than 50%, wherein the one or more trenches have an aspect ratio greater than or equal to 10 and the silicon nitride layer has a step coverage of more than 90%.

2. As in request item 1, where, One of the one or more hydrogen-containing and nitrogen-containing gases includes nitrogen.

3. As in request item 1, where, One of the one or more hydrogen-containing and nitrogen-containing gases includes hydrogen.

4. As in request item 1, where, The one or more hydrogen-containing and nitrogen-containing gases include ammonia, hydrazine, nitrogen, or hydrogen.

5. As in request item 1, where, The process of depositing the silicon nitride layer includes a plasma-enhanced deposition process.

6. As in request item 5, wherein, The plasma-enhanced deposition process includes: providing a precursor to the reaction chamber; purging the reaction chamber; forming multiple reactive species in the reaction chamber; and purging the reactive species.

7. As in request item 6, wherein, A reactant is continuously flowed during the steps of supplying the precursor to the reaction chamber and forming the active reactant species within the reaction chamber.

8. As in request item 7, wherein, The reactants are selected from the group consisting of nitrogen, hydrogen, and ammonia.

9. As in request item 6, wherein, The steps for forming these active reactive species in the reaction chamber include forming active species from one or more gases including nitrogen and hydrogen.

10. As in request item 6, wherein, During the steps of forming these active reactant species in the reaction chamber, the power frequency used to form plasma is between approximately 100 kHz and approximately 2.45 GHz.

11. As in request item 6, wherein, The power used to form the plasma during the step of forming these active reactant species in the reaction chamber is between about 10 W and about 4 kW.

12. As in request item 1, wherein, The power frequency used to form plasma during the step of exposing the substrate to the active species is between approximately 100 kHz and approximately 2.45 GHz.

13. As in request item 1, wherein, The power used to form the plasma during the step of exposing the substrate to the active species is between about 10 W and about 4 kW.

14. A method for forming a silicon nitride layer, the method comprising the steps of: providing a substrate in a reaction chamber; exposing the substrate to a silicon-containing precursor to adsorb silicothermic energy onto the surface of the substrate; exposing the substrate to a plurality of active species formed by hydrogen-containing and nitrogen-containing gases, wherein NH and / or N-H2 groups are formed on the surface of the substrate; and depositing a silicon nitride layer over one or more trenches on the substrate in the reaction chamber, wherein the step of exposing the substrate to the active species comprises a pulsed plasma process, during which plasma power is pulsed, and the pulsed plasma process comprises a pulsed plasma with an on-time duty cycle greater than 50%, wherein the one or more trenches have an aspect ratio greater than or equal to 10 and the silicon nitride layer has a step coverage of more than 90%.

15. As in request item 14, wherein, The silicon precursor contains silicon and hydrogen.

16. As in request item 14, wherein, The steps for depositing the silicon nitride layer include a plasma-enhanced deposition process.

17. A semiconductor structure formed according to any one of claims 1 to 16.

18. A reactor system for performing any of the steps described in claims 1 to 16.

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