Methods and systems for forming silicon nitride layers using low radio frequency plasma processes

Abstract

Methods of forming a treated silicon nitride layer are disclosed. An exemplary method includes forming a silicon nitride layer over a substrate by: providing a silicon precursor to a reaction chamber for a silicon precursor pulse period; providing a nitrogen reactant to the reaction chamber for a reactant pulse period; applying a first plasma power having a first frequency for a first plasma power period during deposition; and applying a second plasma power having a second frequency for a second plasma power period during a treatment step.

Description

Technical Field

[0001] This disclosure generally relates to methods and systems for forming structures suitable for forming electronic devices. More specifically, examples of this disclosure relate to methods and systems for forming layers comprising silicon nitride. Background Technology

[0002] Silicon nitride layers can be used for a variety of purposes in the manufacturing process of electronic devices. For example, silicon nitride layers can be used as linings, gap fillers, etc.

[0003] In some cases, plasma-enhanced processes such as plasma-enhanced ALD (PEALD) can be used to deposit silicon nitride. Compared to methods without plasma, plasma-enhanced processes can operate at relatively lower temperatures and / or exhibit relatively higher deposition rates.

[0004] In liner applications, uniform film quality along the sidewalls of the deposited silicon nitride is generally desirable. Unfortunately, many plasma silicon nitride processes cannot produce silicon nitride layers with the desired quality (e.g., etch rate) uniformity.

[0005] In gap-filling applications, silicon nitride deposited using PEALD on high aspect ratio features (e.g., gaps with an aspect ratio of 3 or greater) tends to form voids in the deposited material because less material is deposited at the bottom of the feature (e.g., on the bottom or side surfaces near the bottom of the gap—compared to the side surfaces of the gap at or near the top). The poor conformal conformality and / or undesirable deposition profile of the deposited silicon nitride can be attributed to the relatively low ion bombardment effect.

[0006] Efforts to improve the poor conformability and / or gap-filling capability of PEALD-deposited silicon nitride have focused on adjusting process parameters, such as plasma exposure time and pressure, to provide sufficient activating material, such as free radicals, near the feature bottom, thereby increasing the amount of material deposited at the feature bottom. However, this effort is limited because free radical recombination is an intrinsic phenomenon.

[0007] To overcome these problems, various techniques have been proposed. For example, U.S. Patent No. 9,887,082 to Pore et al. discloses a method for filling gaps. This method includes providing a precursor into a reaction chamber to form an adsorbate on a substrate surface, exposing the adsorbate to a nitrogen plasma to form a nitrogen-containing material on top of the feature, and providing a reactant plasma to the reaction chamber, wherein nitrogen acts as a reactant inhibitor, resulting in less material deposited on top of the gap compared to conventional PEALD techniques. This technique produces layers with undesirable high wet etch rate variability.

[0008] Therefore, an improved method for forming a silicon nitride layer on the substrate surface is needed. Furthermore, a device structure including the silicon nitride layer is also required. And, a system for performing this method is also desirable.

[0009] Any discussion of the problems and solutions set forth in this section has been included in this disclosure merely to provide background to the disclosure and should not be construed as an admission that any or all of the discussions were known at the time the invention was made. Summary of the Invention

[0010] Various embodiments of this disclosure relate to methods for forming a silicon nitride layer on a substrate surface and systems for forming a silicon nitride layer. The methods described herein can be used in a variety of applications, including the formation of silicon nitride liner layers and / or silicon nitride gap filling processes.

[0011] While the various embodiments of this disclosure address the shortcomings of existing methods and systems in a manner that will be discussed in more detail below, in general, the various embodiments of this disclosure provide improved methods for forming silicon nitride layers with reduced layer quality variation and / or improved gap filling.

[0012] According to an example of this disclosure, a method of forming a silicon nitride layer on a substrate surface includes providing a substrate in a reaction chamber, forming a deposited silicon nitride layer covering the substrate, and processing the deposited silicon nitride layer using a processing plasma. The step of forming the deposited silicon nitride layer includes providing a silicon precursor to the reaction chamber during a silicon precursor pulse cycle, providing a nitrogen reactant to the reaction chamber during a nitrogen reactant pulse cycle, and applying a deposition plasma power having a first frequency during a first plasma power cycle to form an excited material from the nitrogen reactant, thereby forming the deposited silicon nitride layer. The step of processing the deposited silicon nitride layer includes using a processing plasma having a processing plasma power and a second frequency during the processing plasma power cycle. In some cases, the first frequency and the second frequency may be substantially the same (e.g., about 300 kHz and about 500 kHz). In some cases, the first frequency is higher than the second frequency. For example, the first frequency may be between about 13 MHz and about 14 MHz or about 26 MHz and about 28 MHz, and the second frequency may be between about 300 kHz and about 500 kHz. The steps of forming the deposited silicon nitride layer and processing the deposited silicon nitride layer may be repeated to form the silicon nitride layer. In some cases, hydrogen reactants may be supplied to the reaction chamber, for example, during the step of forming the silicon nitride layer. In this case, hydrogen reactants may not be supplied to the reaction chamber during the step of processing the silicon nitride layer deposition. According to a further example of these embodiments, the first plasma power cycle and the second plasma power cycle do not overlap in time or space. According to a further example, the step of processing the silicon nitride layer deposition includes using processing plasma power having a second frequency and a third frequency.

[0013] According to further embodiments of this disclosure, a device structure is provided. The device structure can be formed according to the methods described herein. The device structure may include a substrate and one or more silicon nitride layers as described herein.

[0014] According to another example of this disclosure, a system is provided configured to perform the methods described herein and / or form device structures.

[0015] These and other embodiments will become apparent to those skilled in the art from the following detailed description of certain embodiments with reference to the accompanying drawings; the invention is not limited to any particular embodiment disclosed. Attached Figure Description

[0016] A more complete understanding of exemplary embodiments of the present disclosure can be obtained by considering the following illustrative drawings and by referring to the detailed description and claims.

[0017] Figure 1 The effects of using (a) high-frequency power to form plasma and (b) low-frequency power to form plasma on the material produced are shown.

[0018] Figure 2 A method according to an example of this disclosure is shown.

[0019] Figure 3 The timing of a method applicable to a gap filling process according to an example of this disclosure is shown.

[0020] Figure 4 The timing of a method suitable for forming a liner according to an example of this disclosure is shown.

[0021] Figure 5 STEM images of structures formed with and without low-frequency plasma treatment are shown.

[0022] Figure 6 STEM images of structures formed using high-frequency plasma processing and low-frequency plasma processing are shown.

[0023] Figure 7 It shows Figure 6 The relationship between the thickness ratio and depth of the structure shown.

[0024] Figure 8 STEM images of structures formed using high-frequency plasma processing and structures formed using high-frequency plus low-frequency plasma processing are shown.

[0025] Figure 9 It shows Figure 8 The relationship between the normalized silicon nitride layer thickness and depth in the structure shown.

[0026] Figure 10 A system according to at least one embodiment of the present disclosure is shown.

[0027] It should be understood that the elements in the accompanying drawings are shown 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 aid in understanding the embodiments illustrated in this disclosure. Detailed Implementation

[0028] Although certain embodiments and examples are disclosed below, those skilled in the art will understand that the invention extends beyond the specifically disclosed embodiments and / or uses of the invention and their obvious modifications and equivalents. Therefore, it is intended that the scope of the disclosed invention should not be limited to the specific disclosed embodiments described below.

[0029] This disclosure generally relates to methods for forming a silicon nitride layer on a substrate surface, device structures including a silicon nitride layer, and systems for performing the method and / or forming the device structure. As described in more detail below, exemplary methods can be used to form device structures suitable for forming electronic devices. For example, exemplary methods can be used to form a silicon nitride liner and / or fill gaps or recesses on a substrate surface with silicon nitride.

[0030] In this disclosure, the gas may include materials that are gases at ambient 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 other than process gases, such as gases introduced without passing through gas distribution components like spray heads or other gas distribution devices, may be used, for example, to seal the reaction space, and may include sealing gases, such as rare gases or other inert gases. The term inert gas refers to a gas that does not participate in the chemical reaction to a perceptible degree and / or a gas that can excite precursors when plasma power is applied. The terms precursor and reactant are used interchangeably.

[0031] As used herein, the term "substrate" can refer to any one or more underlying materials that can be used to form or on which devices, circuits, or films can be formed. Substrates can include bulk materials such as silicon (e.g., single-crystal silicon), other group IV materials such as germanium, or compound semiconductor materials such as GaAs, and can include one or more layers covering or located beneath the bulk material. Furthermore, substrates can include various features such as recesses, lines, etc., formed within or on at least a portion of the substrate layers. As a specific example, a substrate can include features (e.g., protrusions, recesses, or gaps) with an aspect ratio of 3 or greater.

[0032] In some embodiments, a membrane refers to a layer extending in a direction perpendicular to the thickness direction to cover the entire target or related surface, or simply a layer covering the target or related surface. In some embodiments, a layer refers to a structure of a certain thickness formed on a surface, or a synonym for a membrane or non-membrane structure. A layer can be continuous or discontinuous. A membrane or layer can consist of discrete single membranes or layers or multiple membranes or layers having certain properties, and the boundaries between adjacent membranes or layers may or may not be clear, and may or may not be established based on physical, chemical and / or any other properties, formation process or sequence and / or the function or purpose of adjacent membranes or layers.

[0033] In this disclosure, "continuous" can mean one or more of the following: without breaking the vacuum, without interrupting the timeline, without any material intervention step, without changing the processing conditions, immediately following, as the next step, or without the intervention of discrete physical or chemical structures between two structures other than those in some embodiments. For example, reactants can be continuously supplied in two or more steps and / or cycles of a method.

[0034] The term “cyclic deposition process” or “cyclic deposition process” can refer to the sequential introduction of precursors (and / or reactants) into a reaction chamber to deposit a layer on a substrate, and includes processing techniques such as atomic layer deposition (ALD), cyclic chemical vapor deposition (cyclic CVD), and hybrid cyclic deposition processes that include ALD and cyclic CVD components.

[0035] As used herein, the term atomic layer deposition (ALD) can refer to a vapor-phase deposition process in which deposition cycles (preferably multiple consecutive or continuous deposition cycles) are performed in a processing chamber. Typically, during each cycle, a precursor is introduced, and the precursor can be chemisorbed onto the deposition surface (e.g., a substrate surface or a previously deposited lower layer surface, such as material from a previous ALD cycle), forming a monolayer or sub-monolayer that is not readily reacting with additional precursors (i.e., a self-limiting reaction). Subsequently, a reactant (e.g., another precursor or a reactive gas) can be introduced into the processing chamber to convert the chemisorbed precursor into the desired material on the deposition surface. Typically, the reactant is capable of further reacting with the precursor. Furthermore, a purging step may also be used during each cycle to remove excess precursor from the processing chamber and / or excess reactant and / or reaction byproducts after the conversion of the chemisorbed precursor. Furthermore, as used herein, the term atomic layer deposition 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 when performed with alternating pulses of a precursor composition, a reactant gas, and a purge gas (e.g., an inert carrier gas). PEALD refers to an ALD process that applies plasma in one or more ALD steps.

[0036] As used herein, the term "purge" can refer to a process of continuously or between two interacting gas pulses to supply an inert or substantially inert gas to a reaction chamber. For example, purging can be provided between precursor pulses and reactant pulses to avoid or at least minimize gas-phase interactions between the precursor and reactant. It should be understood that purging can be performed temporally or spatially, or both. For example, in the case of temporal purging, a purging step can be used, for instance, in the temporal sequence of supplying a first precursor to the reaction chamber, supplying a purge gas to the reaction chamber, and supplying a second precursor or reactant to the reaction chamber, wherein the substrate on which the deposited layer is located remains stationary. In the case of spatial purging, the purging step can take the form of moving the substrate from a first position supplying the first precursor via a purge gas curtain to a second position supplying the second precursor.

[0037] As used herein, silicon nitride refers to a material comprising silicon and nitrogen. Silicon nitride can be represented by the formula Si3N4. In some cases, silicon nitride may not include stoichiometric amounts of silicon nitride. In some cases, silicon nitride may include other elements such as carbon, nitrogen, and hydrogen.

[0038] As used herein, the term "overlap" can refer to a temporal and intra-reaction overlap. For example, when two or more reactant pulse cycles overlap, there is a time period during which each of the two reactants is supplied to the reaction chamber or exists within the reaction chamber.

[0039] Furthermore, in this disclosure, any two numbers of a variable may constitute a working range of the variable, and any range indicated may or may not include endpoints. Additionally, any value of the indicated variable (whether or not it is expressed as “about”) may refer to an exact value or an approximate value, and includes equivalents, and in some embodiments may refer to an average, median, representative value, multi-value, etc. Furthermore, in this disclosure, in some embodiments, the terms “comprising,” “consisting of,” and “having” may independently mean “generally or broadly comprising,” “including,” “substantially constitutes,” or “consisting of.” In this disclosure, in some embodiments, the meaning of any definition does not necessarily exclude the common and customary meaning.

[0040] Examples of this disclosure provide a method for forming a silicon nitride layer on a substrate surface. The exemplary method uses a low-frequency plasma in at least one processing step of the method. It is believed that the low-frequency plasma provides higher bombardment energy for the ions, enabling them to penetrate deeper into recesses on the substrate and / or into the deposited film.

[0041] Figure 1The bombardment depth of (a) ions generated using high-frequency plasma and (b) ions generated using low-frequency plasma are shown. In this document, low-frequency plasma may refer to plasma generated using power frequencies between approximately 300 kHz and approximately 500 kHz. High-frequency plasma may refer to plasma generated using power frequencies between approximately 13 MHz and approximately 14 MHz, or between approximately 26 MHz and approximately 28 MHz. As shown, ions generated by low-frequency plasma penetrate deeper within recess 104 compared to ions generated using high-frequency plasma within recess 102.

[0042] Figure 2 A method 200 for forming a silicon nitride layer on a substrate surface according to an example of the present disclosure is shown. Method 200 includes the steps of: providing a substrate in a reaction chamber (step 202), forming a deposited silicon nitride layer covering the substrate (step 204), and treating the deposited silicon nitride layer using a processing plasma (step 206). As shown, step 204 may include the following sub-steps: providing a silicon precursor (sub-step 208), providing a nitrogen reactant (sub-step 210), and applying a deposition plasma (sub-step 212).

[0043] During step 202, a substrate is provided within the reaction chamber of the reactor system. According to examples of this disclosure, the substrate includes a surface comprising patterned features. Patterned features may include recesses, such as trenches, vias, or regions between adjacent protrusions. The reaction chamber used in step 202 may be or include the reaction chamber of a chemical vapor deposition reactor system configured to perform a cyclic deposition process. The reaction chamber may be a separate reaction chamber or part of a combined tool. The following is combined with... Figure 10 Exemplary suitable reaction chambers are discussed in more detail.

[0044] Step 202 may include heating the substrate to a desired deposition temperature within the reaction chamber. In some embodiments of this disclosure, step 202 includes heating the substrate to a temperature below 800°C. For example, in some embodiments of this disclosure, heating the substrate to the deposition temperature may include heating the substrate to a temperature between about 50°C and about 300°C. In addition to controlling the substrate temperature, the pressure within the reaction chamber may also be adjusted. For example, in some embodiments of this disclosure, during step 102, the pressure within the reaction chamber may be less than 760 Torr or between 0.2 Torr and 760 Torr or between about 1.5 Torr and 22.5 Torr.

[0045] During step 204, a silicon nitride layer is deposited on the substrate provided in step 202. According to an example of this disclosure, step 204 includes a cyclic plasma process, such as the PEALD process.

[0046] In the illustrated example, step 204 includes providing a silicon precursor to the reaction chamber during a silicon precursor pulse cycle (sub-step 208), providing a nitrogen reactant to the reaction chamber during a nitrogen reactant pulse cycle (sub-step 210), and applying a deposition plasma power with a first frequency during a first plasma power cycle to form an excited material from the nitrogen reactant, thereby forming a deposited silicon nitride layer (sub-step 212). The pressure and / or temperature during step 204 may be the same as or similar to the temperature described in conjunction with step 202.

[0047] During sub-step 208, a silicon precursor is provided to the reaction chamber. Exemplary silicon precursors may be selected from the group consisting of aminosilanes, halosilanes, silanes, and disilanes. Aminosilanes and halosilanes include, but are not limited to, Si₂Cl₆, SiCl₂H₂, SiI₂H₂, bis(diethylaminosilane), bis(dimethylaminosilane), hexaethylaminodisilane, tetraethylaminosilane, tert-butylaminosilane, bis(tert-butylaminosilane), trimethylsilyldiethylamine, trimethylsilyldiethylamine, and bis(dimethylaminodimethylsilane). The precursor flow rate with a carrier gas can be in the range of about 500 to about 5000 sccm. The duration of the precursor pulse period 212 can be from about 0.05 to about 5 seconds. The gas containing the carrier gas and the precursor gas can contain about 5% to about 10% of the precursor.

[0048] During sub-step 210, a nitrogen reactant is supplied to the reaction chamber during a nitrogen reactant pulse cycle. Exemplary nitrogen reactants include nitrogen and optionally hydrogen. As a specific example, the nitrogen reactant may include one or more of nitrogen (N2) and NH3. The nitrogen reactant gas flow rate may be in the range of about 100 to about 10,000 sccm. The duration of the nitrogen reactant pulse cycle may be in the range of about 0.05 to about 5 seconds.

[0049] During sub-step 212, a deposition plasma power having a first frequency is applied in the reaction chamber for a first plasma power cycle to form excited material from the nitrogen reactants. According to examples of these embodiments, the first frequency may be between about 13 MHz and about 14 MHz, or between about 26 MHz and about 28 MHz. In these cases, the first frequency is higher than the second frequency. According to other examples of this disclosure, the first frequency and the second frequency are substantially the same (e.g., differing from each other by less than about 10%). In these cases, the first frequency may be between about 300 kHz and about 500 kHz. The plasma power may be, for example, between about 100 W and about 1000 W, or between about 400 W and about 800 W.

[0050] In some cases, method 200 may also include supplying hydrogen reactants to the reaction chamber during a hydrogen reactant pulse cycle (e.g., during the step of forming a deposited silicon nitride layer). Exemplary hydrogen reactants include hydrogen (H2) and hydrocarbons, such as methane.

[0051] Steps 208-212 may be repeated multiple times before method 200 proceeds to step 206. Furthermore, steps 204 and 206 may be repeated multiple times to form a silicon nitride layer.

[0052] Step 206 includes depositing a silicon nitride layer using a processing plasma having a processing plasma power of a second frequency during a processing plasma power cycle. According to various examples of this disclosure, the second frequency may be equal to or less than the first frequency. For example, the second frequency may be between about 300 kHz and about 500 kHz. In some cases, two plasma power frequencies (a second frequency and a third frequency) may be used during step 206. In these cases, the third frequency may be substantially the same (e.g., within about 10%) and / or may be within the range of the first frequency described above. The duration of the processing plasma power cycle may be between about 0.5 and about 60 seconds. During step 206, the plasma power may be, for example, between about 100 W and about 1000 W or between about 400 W and about 800 W.

[0053] As used herein, a pulse period refers to the period during which gas (e.g., precursor, reactant, inert gas, and / or carrier gas) flows into the reaction chamber and / or the period during which power (e.g., the power to generate plasma) is applied. The height and / or width of the pulse period shown do not necessarily represent a specific amount or duration of the pulse.

[0054] Figure 3 An exemplary timing 300 applicable to steps 204 and 206 is shown according to an example of this disclosure. Timing 300 may be particularly useful for methods of forming a silicon nitride layer on a substrate surface to fill gaps on the surface.

[0055] In the illustrated example, a silicon precursor is provided to the reaction chamber during silicon precursor pulse cycle 302, and a nitrogen reactant is provided to the reaction chamber during nitrogen reactant pulse cycle 304. Optionally, a hydrogen reactant is provided to the reaction chamber during one or more hydrogen reactant pulse cycles 306, 306'. A deposition plasma power with a first frequency is applied during a first plasma power cycle 308, and a processing plasma power with a second frequency is applied during a processing plasma power cycle 310. According to an example of this disclosure, pulse cycles 308 and 310 do not overlap in time or space.

[0056] The silicon precursor pulse cycle 302 can be the same as or similar to sub-step 208, the nitrogen reactant pulse cycle 304 can be the same as or similar to sub-step 210, the hydrogen reactant pulse cycle 306 can be as described above, the first plasma power cycle 308 can be the same as or similar to sub-step 212, and the processing plasma power cycle 310 can be as described above in conjunction with step 206.

[0057] In addition to pulse cycles 302-310, the timing sequence may include a source purge step 312 and / or a post-processing purge 314. During the source purge step 312, a carrier gas (e.g., for providing a silicon precursor during the silicon precursor pulse cycle 302), a nitrogen reactant, and / or a hydrogen reactant may be supplied to the reaction chamber to facilitate the distribution and / or removal of some of the silicon precursor and / or its byproducts supplied during the silicon precursor pulse cycle 302. During the post-processing purge step 314, a carrier gas, a nitrogen reactant, and / or a hydrogen reactant may be supplied to the reaction chamber to facilitate the removal of gases from the reaction chamber.

[0058] According to the example shown, the silicon precursor pulse period 302 does not overlap with the source purge step 312, the post-processing purge 314, the first plasma power period 308, or the processing plasma power period 310. Furthermore, the hydrogen reactant pulse periods 306 and 306' do not overlap with the processing plasma power period 310. The nitrogen reactant pulse period 304 can be continuous by at least one combination of forming a deposited silicon nitride layer and processing the deposited silicon nitride layer.

[0059] Figure 4 Another timing 400 applicable to steps 204 and 206 is shown according to an additional example of this disclosure. Timing 400 is particularly useful for methods of forming a silicon nitride layer on the sidewalls of a feature on the surface of a substrate. The silicon nitride layer can be used, for example, as a liner.

[0060] Similar to timing 200, timing 400 includes a silicon precursor pulse cycle 402, a nitrogen reactant pulse cycle 404, one or more optional hydrogen reactant pulse cycles 406, 406', a first plasma power cycle 408, and a processing plasma power cycle 410, which may be the same as or similar to 302-310. Furthermore, timing 400 includes a source purge step 412, a post-deposition purge step 414, a hydrogen purge step 416, and a post-processing purge / hydrogen in step 418. Steps 412 and 418 may be the same as or similar to steps 312 and 314, respectively. The post-deposition purge step 414 may include supplying nitrogen reactant and / or hydrogen reactant to the reaction chamber. The hydrogen purge step 416 may include supplying nitrogen reactant to the reaction chamber without supplying hydrogen reactant.

[0061] Although not shown separately, one or more carrier gases may be supplied to the reaction chamber during one or more (e.g., all) of steps 302-314 and 402-418. The carrier gas may be or include an inert gas, nitrogen, etc.

[0062] Figure 5 Scanning transmission electron microscopy (STEM) images of structures 502, 512, 522, and 532 are shown. Structure 502 includes a substrate 504 on which feature 506 is formed. A silicon nitride layer 508 is formed on the substrate 504 and feature 506. Structure 502 is formed according to method 200, but step 206 of depositing the silicon nitride layer is not performed. Structure 512 includes a substrate 514 on which feature 516 is formed. A silicon nitride layer 518 is formed on the substrate 514 and feature 516. Structure 512 is formed according to method 200, including step 206 of depositing the silicon nitride layer. Structure 522 shows structure 502 after exposure to an etching process (e.g., diluted hydrofluoric acid (HF) etching). As shown, a portion of silicon nitride layer 508 is removed, while silicon nitride layer 510 is retained after the etching process. Structure 532 shows structure 512 after exposure to an etching process. A portion of silicon nitride layer 518 is removed, while silicon nitride layer 520 is retained after the etching process. Compared to silicon nitride layer 508 on sidewall 526, silicon nitride layer 518 exhibits better quality, such as a lower and more consistent etching rate, especially on sidewall 524.

[0063] Figure 6 Structure 602, formed using a high-frequency plasma processing method 200, and structure 604, formed using a low-frequency plasma processing method, are shown. Structure 602 includes a substrate 606 and a silicon nitride layer 608. Structure 604 includes a substrate 610 and a silicon nitride layer 612.

[0064] Figure 7 The diagram illustrates the relationship between the thickness ratio (thickness measured at one location / thickness measured at the feature opening) of structures 602 (line 702) and 604 (line 704) and the depth from the feature opening. Figure 7 As shown, the normalized thickness of the silicon nitride layer 612 on the sidewall 618 of the trench 616 is always larger than the normalized thickness of the silicon nitride layer 608 on the sidewall 620 of the trench 614, indicating that the silicon nitride layer deposited using the method 200 with a low-frequency processing procedure has better gap filling than the silicon nitride layer deposited using the method 200 with a high-frequency processing procedure.

[0065] Figure 8Structure 802, formed using method 200 with a high-frequency plasma processing procedure, and structure 804, formed using both high-frequency and low-frequency plasma processing procedures, are shown. The low-frequency and high-frequency plasma processes can be applied simultaneously or sequentially. Structure 802 includes a substrate 806 and a silicon nitride layer 810. Structure 804 includes a substrate 822 and a silicon nitride layer 824. The plasma processing time for forming structure 804 is less than 3 seconds and can be between about 0.5 and about 2 seconds. The plasma processing time for forming structure 802 is greater than 7 seconds. As shown, when high-frequency and low-frequency power are applied during the plasma processing, a shorter time can be used to form the structure.

[0066] Figure 9 The relationship between the thickness ratio (thickness measured at one location / thickness measured at the feature opening) of structures 802 (line 902) and 804 (line 904) and the depth from the feature opening (e.g., at locations 812-820) is shown. Figure 9 As shown, compared to the normalized thickness of the silicon nitride layer 810 on the sidewall 830 of the trench 832, the normalized thickness of the silicon nitride layer 824 on the sidewall 826 of the trench 828 is always larger. This indicates that the silicon nitride layer deposited using the method 200 with a low-frequency + high-frequency processing procedure has better gap filling than the silicon nitride layer deposited using the method 200 with only a high-frequency processing procedure, even though the plasma processing time for forming structure 804 is shorter than the plasma processing time for forming structure 804.

[0067] Now go to Figure 10 The diagram illustrates a reactor system 1000 according to exemplary embodiments of the present disclosure. The reactor system 1000 can be used to perform one or more steps or sub-steps described herein, and / or to form one or more device structures or portions thereof described herein.

[0068] The reactor system 1000 includes a pair of parallel and facing conductive plate electrodes 1014, 1018 within a reaction chamber 1002, inside a reaction zone 1001. Although one reaction chamber 1002 is illustrated, the system 1000 may include two or more reaction chambers. Plasma can be excited within the reaction chamber 1001 by applying high-frequency (HRF), low-frequency (LRF), or LRF+HRF power, for example, from a plasma power source 1008, to one electrode (e.g., electrode 1018) and electrically grounding the other electrode (e.g., electrode 1014). A temperature regulator 1003 may be disposed in the lower platform 1014 (lower electrode), and the temperature of the substrate 1022 placed thereon can be maintained at a desired temperature, such as the temperature described above. Electrode 1018 may be used as a gas distribution device, such as a spray plate or spray head. One or more gas lines (e.g., reactant gas line 1004 and precursor gas line 1006, respectively coupled to reactant and precursor sources) can be used to introduce precursor gas, reactant gas, and carrier gas or inert gas (if any) into reaction chamber 1002. For example, line 1004 can be used to introduce inert gas and reactants (e.g., as described above) into reaction chamber 1002, and / or line 1006 can be used to introduce precursor and carrier gas (e.g., as described above) into reaction chamber 1002. Although two inlet gas lines 1004, 1006 are shown, reactor system 1000 may include any suitable number of gas lines.

[0069] In reaction chamber 1002, a circular conduit 1020 with an exhaust line 1021 can be provided, through which gas in the interior 1001 of reaction chamber 1002 can be discharged to exhaust source 1010. Furthermore, transfer chamber 1023 may be provided with a sealing gas line 1029 to introduce sealing gas into the interior 1001 of reaction chamber 1002 via the interior of transfer chamber 1023 (transfer zone), wherein a partition plate 1025 (omitted in the figure, through which the substrate is transferred into or out of transfer chamber 1023) can be provided to separate the reaction zone and transfer chamber 1023. Transfer chamber 1023 may also be provided with an exhaust line 1027 coupled to exhaust source 1010. In some embodiments, continuous flow of carrier gas into reaction chamber 1002 can be achieved using a flow-through system (FPS).

[0070] Reactor system 1000 may include one or more controllers 1012 programmed or otherwise configured to enable one or more method steps described herein to be performed. Controllers 1012 are coupled to various power sources, heating systems, pumps, robots, and gas flow controllers or reactor valves, as those skilled in the art will understand. For example, controller 1012 may be configured to control the gas flow of precursors, reactants, and inert gases into at least one of one or more reaction chambers to form a silicon nitride layer on a substrate surface. Controller 1012 may be further configured to provide power (e.g., HRF, LRF, or LRF+HRF) to form a plasma, for example, within reaction chamber 1002. Controller 1012 may similarly be configured to perform additional steps described herein. For example, controller 1012 may be configured to control the gas flow of precursors and reactants into at least one of one or more reaction chambers to form a treated silicon nitride layer covering a substrate, and to provide deposition plasma power and processing plasma power in at least one reaction chamber, wherein the frequency of the deposition power may differ from the frequency of the processing plasma power.

[0071] The controller 1012 may include electronic circuitry and software to selectively operate valves, manifolds, heaters, pumps, and other components included in the system 1000. Such circuitry and components are used to introduce precursors, reactants, and purge gases from appropriate sources. The controller 1012 may control the timing of gas pulse sequences, the temperature of the substrate and / or reaction chamber, the pressure within the reaction chamber, the plasma power, and various other operations to provide appropriate operation of the system 1000, such as during the execution of method 200 or timing 300 or 400.

[0072] The controller 1012 may include control software to electrically or pneumatically control valves to control the inflow and outflow of precursors, reactants, and / or purge gases from the reaction chamber 1002. The controller 1012 may include modules, such as software or hardware components like an FPGA or ASIC, that perform certain tasks. These modules may advantageously be configured to reside on an addressable storage medium of the control system and to perform one or more processes.

[0073] In some embodiments, a dual-chamber reactor (for processing two portions or compartments of a substrate disposed close to each other) may be used, wherein reactant gases and inert gases may be supplied via a shared line, while precursor gases may be supplied via a non-shared line.

[0074] During operation of system 1000, a substrate, such as a semiconductor wafer, is transferred from, for example, substrate processing region 1023 to reaction region 1001. Once the substrate is transferred to reaction region 1001, one or more gases, such as precursors, reactants, carrier gases and / or purge gases, are introduced into reaction chamber 1002.

[0075] The exemplary embodiments disclosed above do not limit the scope of the invention, as these embodiments are merely examples of embodiments of the invention. Any equivalent embodiments are within the scope of the invention. In fact, various modifications to this disclosure, such as alternative and useful combinations of the described elements, will become apparent to those skilled in the art from the description, in addition to the embodiments shown and described herein. Such modifications and embodiments are also intended to fall within the scope of the appended claims.

Claims

1. A method for forming a silicon nitride layer on a substrate surface, the method comprising the following steps: A substrate is provided within the reaction chamber; Forming a deposited silicon nitride layer over a substrate, wherein the step of forming the deposited silicon nitride layer includes: Silicon precursors are supplied to the reaction chamber during the silicon precursor pulse cycle; Nitrogen reactants are supplied to the reaction chamber during the nitrogen reactant pulse cycle; and A deposition plasma power with a first frequency is applied during a first plasma power cycle to form excited material from nitrogen reactants, thereby forming a deposited silicon nitride layer; and During the second plasma power cycle, a silicon nitride layer is deposited using a processing plasma with a processing plasma power having a second frequency. During the formation and treatment of the deposited silicon nitride layer, the nitrogen reactants are provided to the reaction chamber.

2. The method according to claim 1, wherein, The first frequency and the second frequency are the same.

3. The method according to claim 1, wherein, The first frequency is higher than the second frequency.

4. The method according to claim 1 or 3, wherein, The first frequency is between 13MHz and 14MHz or 26MHz and 28MHz.

5. The method according to claim 1, wherein, The second frequency is between 300 kHz and 500 kHz.

6. The method according to claim 1, wherein, Forming a deposited silicon nitride layer also includes repeatedly providing silicon precursors, providing nitrogen reactants, and applying deposition plasma power once or multiple times, wherein the process of depositing the silicon nitride layer is performed after the formation of the deposited silicon nitride layer.

7. The method according to claim 6, wherein, Repeat the formation and treatment of the deposited silicon nitride layer once or multiple times.

8. The method according to claim 1, wherein, The silicon precursor pulse cycle does not overlap with one or more of the first plasma power cycle and the second plasma power cycle.

9. The method of claim 1, further comprising the step of providing hydrogen reactants to the reaction chamber, wherein, The hydrogen reactants include hydrogen gas (H2) or hydrocarbons.

10. The method according to claim 9, wherein, During the step of forming the deposited silicon nitride layer, hydrogen reactants are continuously supplied to the reaction chamber.

11. The method according to any one of claims 9 and 10, wherein, No hydrogen reactants are supplied to the reaction chamber during the process of depositing the silicon nitride layer.

12. The method according to claim 1, wherein, During the formation of the deposited silicon nitride layer, the substrate is heated to a temperature between 50ºC and 300ºC.

13. The method according to claim 1, wherein, The silicon nitride layer fills the recesses formed on the substrate surface.

14. The method according to claim 1, wherein, The silicon precursor includes one or more of aminosilane, halosilane, silane, and silane.

15. The method according to claim 1, wherein, The nitrogen reactants include one or more of nitrogen and NH3.

16. The method according to claim 9, wherein, The hydrogen reactants include hydrogen.

17. The method according to claim 1, wherein, The first plasma power cycle and the second plasma power cycle do not overlap in time or space.

18. The method according to claim 1, wherein, The process of depositing a silicon nitride layer includes using a processing plasma power with a second frequency and a third frequency.

19. The method according to claim 18, wherein, The first frequency and the third frequency are the same.

20. A device structure formed by the method according to claim 1.

21. A system for forming a silicon nitride layer on a substrate surface, comprising: Reaction chamber; Silicon precursor source pipeline; Reactant source pipeline; A plasma power source having a first frequency and a second frequency; Exhaust source; as well as Controller The controller is configured as follows: Control the airflow of silicon precursors and nitrogen reactants entering the reaction chamber; A deposition plasma power with a first frequency is applied during a first plasma power cycle to form excited matter from nitrogen reactants; and A processing plasma with processing plasma power and a second frequency is applied during a second plasma power cycle, wherein the nitrogen reactant is provided to the reaction chamber during the formation of the deposited silicon nitride layer and the processing of the deposited silicon nitride layer.

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