Method for depositing a silicon nitride layer, structure formed by the method, and implementation system

Abstract

Methods and systems for pre - treating a surface prior to depositing silicon nitride on the surface are disclosed. An exemplary method includes pre - treating the surface by exposing the surface to reactive species formed from one or more gases including nitrogen and hydrogen. The step of pre - treating may additionally include the step of exposing the surface to a gas including silicon.

Description

Technical Field

[0001] The present disclosure generally relates to methods of forming thin films and to structures that include such thin films. More specifically, the present disclosure relates to methods of depositing silicon nitride layers, structures that include such layers, and apparatuses for depositing such layers. Background Art

[0002] Features formed using silicon nitride films are used in a wide variety of applications. For example, such features can be used as insulating regions, as etch stop regions, as spacers, to protect trench structures, and for etch resistant protection regions during the formation of electronic devices.

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

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

[0005] One method of reducing the incubation time of plasma enhanced silicon nitride film deposition includes increasing the time the precursor is fed into the reaction chamber and increasing the time the radio frequency (RF) power is applied during the initial deposition cycle of the plasma enhanced silicon nitride deposition process. However, this method does not eliminate the incubation growth differences between different materials or materials capped with different bond structures. Additionally, there may still be incubation growth differences between substrates. Further, since the precursor is used during the incubation process, such methods can cause film growth.

[0006] Accordingly, improved methods and systems for forming structures that include silicon nitride films are desired. For example, improved methods for uniformly depositing silicon nitride films on a substrate surface, which can include one or more materials and / or surface capping bonds, and systems for performing such methods are desired. Summary of the Invention

[0007] Various embodiments of the present disclosure relate to methods of forming features comprising silicon nitride, systems for performing the methods, and structures comprising silicon nitride films. While the ways in which various embodiments of the present disclosure address the drawbacks of existing methods and systems are discussed in more detail below, generally, various embodiments of the present disclosure provide improved methods of depositing silicon nitride using a pretreatment process. The exemplary methods described below provide a relatively efficient method of pretreating a substrate surface to allow for a relatively uniform deposition incubation time - even across different materials on the substrate surface and / or across different substrates. Additionally, the exemplary methods can provide a relatively uniform deposition incubation across features, such as along the height of trenches or protrusions on the substrate surface.

[0008] According to at least one embodiment of the present disclosure, a method of forming a silicon nitride layer comprises: providing a substrate in a reaction chamber; exposing the substrate to reactive species formed from one or more gases comprising nitrogen and hydrogen; and depositing a silicon nitride layer on the substrate in the reaction chamber. The one or more gases comprising nitrogen and hydrogen can comprise, for example, one or more of nitrogen (N2), hydrogen (H2), ammonia, and / or hydrazine, which can be combined with a second gas such as one or more of argon, helium, and nitrogen. According to an example of these embodiments, the step of depositing the silicon nitride layer comprises a plasma-enhanced deposition process. The step of exposing the substrate to the reactive species can comprise a pulsed plasma process, such as where the power used to form the plasma is pulsed. The step of depositing the silicon nitride layer can comprise a cyclic process, where at least one of the reactants and precursors is exposed to the plasma to form reactive species. According to other examples, during the step of providing the precursor to the reaction chamber and forming reactive reactant species in the reaction chamber, the reactants are continuously flowed into the reaction chamber.

[0009] According to additional embodiments of the present disclosure, a method of forming a silicon nitride layer comprises: providing a substrate in a reaction chamber; exposing the substrate to a silicon precursor to thermally adsorb silicon onto the surface of the substrate; exposing the substrate to reactive species formed from one or more gases comprising nitrogen and hydrogen; and depositing a silicon nitride layer on the substrate in the reaction chamber. According to an example of these embodiments, the silicon precursor comprises silicon and hydrogen (e.g., silane, such as silane, disilane, trisilane, etc.). The step of exposing the substrate to the reactive species can comprise a pulsed plasma process, such as where the power used to form the plasma is pulsed. The step of depositing the silicon nitride layer can comprise a plasma-enhanced deposition process.

[0010] According to additional embodiments of the present disclosure, a structure comprises features comprising silicon nitride. The features can be formed using the methods described herein.

[0011] According to additional embodiments of the present disclosure, a system is disclosed for performing the methods described herein and / or for forming the structures described herein.

[0012] For the purpose of summarizing the present invention and the advantages achieved over the prior art, certain objectives and advantages of the present invention may have been described above. Of course, it should be understood that not all such objectives or advantages may be achieved with any particular embodiment of the present invention. Thus, for example, those skilled in the art will recognize that the present invention may be embodied or practiced in a manner that achieves or optimizes one advantage or a group of advantages taught or suggested herein but does not necessarily achieve other objectives or advantages that may be taught or suggested herein. For those skilled in the art, these and other embodiments will become apparent from the following detailed description of certain embodiments with reference to the various figures, and the present invention is not limited to any particular embodiment disclosed. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] A more complete understanding of the exemplary embodiments of the present disclosure can be obtained by reference to the detailed description and the claims when considered in conjunction with the following schematic drawings.

[0014] Figure 1 Illustrates a method of forming a silicon nitride layer according to at least one embodiment of the present disclosure.

[0015] Figure 2 Illustrates a structure according to at least one embodiment of the present disclosure.

[0016] Figure 3 Illustrates an RF power application according to an example of the present disclosure.

[0017] Figure 4 Illustrates the film thickness difference of silicon nitride films deposited in the presence and absence of a pretreatment step according to an example of the present disclosure.

[0018] Figure 5 Illustrates the trench width difference of silicon nitride films deposited in the presence and absence of a pretreatment step according to an example of the present disclosure.

[0019] Figure 6 Illustrates the thickness difference of silicon nitride deposited on silicon oxide and silicon cladding as a function of pretreatment time for varying hydrogen concentrations.

[0020] Figure 7 and 8 Illustrates the top and sidewall film thicknesses as a function of pretreatment time.

[0021] Figure 9 Illustrates N 2+ (391 nm) adsorption peak during pretreatment by OES.

[0022] Figure 10 Illustrates the Hα (656 nm) adsorption peak during pretreatment by OES.

[0023] Figure 11 Show structural film thickness points.

[0024] Figure 12 and 13 Show top and sidewall film thicknesses as a function of pretreatment time.

[0025] Figure 14 Show a comparison of only Ar / NH3 plasma pretreatment with the combination of silane thermal adsorption and Ar / NH3 plasma pretreatment.

[0026] Figure 15 Show a system according to an exemplary embodiment of the present disclosure.

[0027] It should be understood that the elements in the figures are shown for simplicity and clarity only 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 understanding of the illustrated embodiments of the present disclosure. Detailed Description

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

[0029] As elaborated in more detail below, examples of the present disclosure provide improved methods and systems for depositing a silicon nitride film on a substrate surface. Exemplary methods include using one or more pretreatment processes to provide a desired substrate surface for subsequent deposition. The one or more pretreatment processes may reduce the incubation cycles of subsequent deposition, or eliminate the incubation for subsequent silicon nitride deposition, and / or may provide more uniform silicon nitride deposition on different materials and / or on materials formed and / or having different thicknesses using different techniques. Additionally or alternatively, examples of the present disclosure may provide improved step coverage of a silicon nitride film deposited on features on a substrate surface.

[0030] As used herein, the term "substrate" may refer to any one or more underlying materials that can be used to form or on which a device, circuit, or film can be formed. A substrate may include a bulk material, such as silicon (e.g., single crystal silicon), and may include one or more layers disposed over the bulk material. Additionally, a substrate may include various features, such as trenches, recesses, protrusions, lines, etc., formed within or on at least a portion of the substrate.

[0031] As used herein, the term "cyclic deposition" may refer to the sequential 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. After introducing one or more precursors and / or reactants, the reaction chamber may be purged.

[0032] As used herein, the term "atomic layer deposition" (ALD) may refer to a vapor deposition process in which deposition cycles are carried out in a processing chamber, typically a plurality of consecutive deposition cycles. Generally, during each cycle, a precursor is chemisorbed onto the deposition surface (e.g., the substrate surface, which may contain previously deposited material from a previous ALD cycle or other materials), thereby forming a monolayer or sub-monolayer of a material that does not readily react with other precursors (i.e., a self-limiting reaction). Thereafter, in some cases, a reactant (e.g., another precursor or reaction gas) may subsequently be introduced into the processing chamber for converting the chemisorbed precursor on the deposition surface into the desired material. The reactant is capable of further reacting with the precursor. In addition, a purge step may also be utilized during each cycle to remove excess precursors and / or to remove excess reactants and / or reaction by-products from the processing chamber after the conversion of the chemisorbed precursor. When performed using alternating pulses of precursor / reaction gas and a purge (e.g., inert) gas, the term atomic layer deposition as used herein is also intended to include processes denoted by related terms such as chemical vapor atomic layer deposition, atomic layer epitaxy (ALE), molecular beam epitaxy (MBE), gas source MBE or organometallic MBE, and chemical beam epitaxy.

[0033] 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 and the volatile precursors react and / or decompose on the substrate to deposit a material.

[0034] A layer comprising silicon nitride (SiN) or a silicon nitride layer may include, consist essentially of, or consist of silicon nitride material. A film consisting of silicon nitride may contain acceptable amounts of impurities such as carbon, chlorine or other halogens, and / or hydrogen, which may be derived from one or more precursors used to deposit the silicon nitride layer. As used herein, SiN or silicon nitride refers to a compound containing silicon and nitrogen. SiN may be represented as SiN x , where x varies, for example, between about 0.5 and about 2.0, where some Si-N bonds are formed. In some cases, x may vary between about 0.9 and about 1.7, about 1.0 and about 1.5, or about 1.2 and about 1.4. In some embodiments, silicon nitride is formed, where Si has an oxidation state of +IV and the amount of nitride in the material may vary.

[0035] In the present disclosure, "continuously" may refer to one or more of the following: without breaking the vacuum, without interruption of the time axis, without any material intervening steps, without immediately changing the processing conditions as the next step, or in some embodiments, there is no intervening discrete physical or chemical structure between two structures other than the two structures themselves.

[0036] In the present disclosure, any two numbers of a variable may form a feasible range of the variable, and any indicated range may include or exclude the endpoints. Additionally, any indicated variable value (whether or not they are indicated with "about") may refer to an exact value or an approximate value and include equivalent values, and in some embodiments, may refer to an average value, a median value, a representative value, a majority value, etc. Further, in the present disclosure, in some embodiments, the terms "comprising", "consisting of", and "having" may independently refer to "usually or broadly including", "including", "substantially consisting of", or "consisting of". In the present disclosure, in some embodiments, any defined meaning does not necessarily exclude the ordinary and customary meanings.

[0037] Turning now to the drawings, Figure 1 A method 100 of forming a silicon nitride layer according to an exemplary embodiment of the present disclosure is shown. 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 surface of the substrate by exposing the substrate to an active species formed from one or more hydrogen-containing and nitrogen-containing gases (step 106); and depositing a silicon nitride layer on the surface of the substrate (step 108).

[0038] During step 102, the substrate is provided into the reaction chamber of the reactor. According to an example of the present disclosure, the reaction chamber may form part of a cyclic deposition or atomic layer deposition (ALD) reactor. Exemplary single-substrate reactors suitable for use in conjunction with method 100 include reactors specifically designed to perform the ALD process, which are available from ASM International NV (Almere, The Netherlands). Exemplary suitable batch ALD reactors are also available from ASM International NV. The various steps of method 100 may be performed in a single reaction chamber, or may be performed in multiple reaction chambers such as those of a cluster tool - for example, without exposing the surface of the substrate to the ambient atmosphere. The reactor including the reaction chamber may have a heater to activate the reaction by raising the temperature of one or more of the substrate and / or the reactants / precursors.

[0039] During step 102, the substrate can be brought to the desired temperature and pressure for step 104 and / or step 106. As an example, the temperature in the reaction chamber (e.g., of the substrate or substrate support) can be between about 50 °C and about 700 °C or between about 200 °C and about 500 °C. The pressure in the reaction chamber can be from about 0.1 to about 50 Torr.

[0040] The substrate provided during step 102 can include a surface containing 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 can be thermally deposited or deposited with the assistance of a plasma.

[0041] Step 104 can be used, for example, to increase the efficiency of method 100 or reduce its total time. For example, by using step 104 of method 100, the total processing time for depositing a silicon nitride film, including pre-treatment, can be reduced. According to an example of the present disclosure, during step 104, the substrate can be exposed to a silicon precursor to, for example, adsorb silicon-containing molecules on the surface of the substrate such that the surface is terminated with Si-H bonds. During subsequent pre-treatment steps, the Si-H bonds can be used, for example, to form one or more low-coordinate Si=N, SiNH4 or Si-NH2 bonds on the surface of the substrate.

[0042] According to various examples of the present disclosure, the silicon precursor thermally adsorbs or thermally reacts with the surface of the substrate. In other words, the silicon precursor is not exposed to a plasma process during step 104. Suitable silicon precursors for use in combination with step 104 can include silicon and hydrogen, such as silanes, e.g., silane, disilane, trisilane, compounds including silane, etc. The flow rate of the silicon precursor into the reaction chamber can be in the range of, for example, about 10 sccm to about 5 slm. A carrier gas such as nitrogen can co-flow with the silicon precursor. The flow rate of the carrier into the reaction chamber can be in the range of, for example, about 0 slm to about 50 slm. During step 104, the pressure in the reaction chamber can be between about 0.1 Torr and about 50 Torr. The temperature of the substrate can be between about 50 °C and about 700 °C. The silicon precursor can flow into the reaction chamber for a period of about 0.05 seconds to about 10 minutes. Then, the flow of the silicon precursor and the carrier can be stopped, and the reaction chamber can be purged.

[0043] During step 106, the substrate is exposed to reactive species formed from one or more gases including nitrogen and hydrogen. During this step, N-H and / or N-H2 groups can form on the surface of the substrate. The formation of such groups on the surface of the substrate promotes the subsequent (e.g., CVD or cyclic) deposition of silicon nitride on the surface of the substrate, even when the surface includes different materials.

[0044] For example, the substrate surface may include native oxide and / or thick silicon oxide film. Without pre-treatment (e.g., optionally, step 104 and step 106), as described herein, the incubation period for plasma-enhanced deposition of silicon nitride may highly depend on the quality of the underlying layer. For example, deposition of silicon nitride on native silicon oxide may be achieved with a relatively low incubation temperature, while incubation of silicon nitride on a thick high-quality silicon oxide film may exhibit a much higher incubation temperature. However, using step 106 alone or in combination with step 104 may reduce or eliminate the incubation period on both surfaces, thereby allowing silicon nitride to be deposited more uniformly on the surface - whether on the same or different substrates. According to an example of the present disclosure, when one or more substrates have multiple material surfaces to be pre-treated, the pre-treatment time is selected to be greater than the minimum pre-treatment of the surface with the longer pre-treatment time, such that surface capping across the material surfaces is substantially similar. According to at least some embodiments of the present disclosure, the incubation difference between two or more material surfaces is less than 0.5 nm. In some cases, the pre-treatment time may be less than 45 seconds. As discussed in more detail below, another advantage of the method described herein is that the uniformity of the silicon nitride film deposited on or within features on the substrate can be improved. For example, silicon nitride may be deposited on one or more features, i.e., features with a high aspect ratio (e.g., having an aspect ratio greater than or equal to 10 or 12), where the step coverage is greater than about 90%, or greater than about 95%, or greater than about 99%, or even substantially equal to 100%. As used herein, the term "step coverage" is defined as the percentage of the thickness of the metal oxide film on the sidewall of a feature (e.g., a trench or a protrusion) to the thickness of the metal oxide on the horizontal surface of the substrate. In these cases, the time period of the pre-treatment process may be selected to obtain the desired step coverage. According to another example, the pre-treatment makes the surface adhesion state of the treated surface substantially uniform.

[0045] According to an example of the present disclosure, one or more gases containing nitrogen and hydrogen include at least one of nitrogen (N2) and hydrogen (H2) - for example, nitrogen or a mixture of nitrogen and hydrogen. The respective concentrations of nitrogen and hydrogen can be selected such that the amount of nitrogen reactive species is saturated. According to a specific example, one or more gases containing nitrogen and hydrogen include more than about 0.3 volume (V)% of hydrogen in nitrogen or from about a few V% (e.g., 2 V% or more) to about 100 V% of hydrogen. Unless otherwise indicated, the percentages of gases refer to volume percentages.

[0046] In some cases, one or more gases containing nitrogen and hydrogen may include one or more of ammonia and hydrazine. In some cases, one or more gases containing nitrogen and hydrogen may further include a second gas. The second gas may include one or more of argon, helium, and nitrogen. A mixture containing the second gas may include from about 0% to about almost 100% of the second gas. By way of illustration, one or more gases containing nitrogen and hydrogen may include nitrogen and hydrogen, nitrogen and ammonia, nitrogen, hydrogen, and ammonia, or any one of these with one or more of helium and argon.

[0047] In some cases, it may be desirable to pulse the plasma-forming power, for example, to reduce any damage to the substrate surface that may occur during the pretreatment process while still achieving a relatively low incubation temperature and a relatively high throughput. Figure 3 (a) shows the constant power applied during the pretreatment step. Figure 3 (b) shows the pulsed power applied during step 106. The on-time duration may be in the range of about 10% to about 90%. The off-time duration may be in the range of about 10% to about 90%. The pulse frequency may be in the range of about 1000 Hz to about 100000 Hz. The on-time duty cycle may be greater than 50%. The power frequency for forming the plasma during the step of exposing the substrate to the active species 106 may be between about 100 kHz and about 2.45 GHz.

[0048] During step 108, silicon nitride is deposited onto the pretreated surface of the substrate. According to an example of the present disclosure, step 108 is performed without breaking the vacuum or exposing the substrate to the ambient atmosphere. According to a further example, step 108 is performed in the same reaction chamber used for one or more of steps 102 - 106. In embodiments where different reaction chambers are used for steps 106 and 108, the substrate may be transferred from the first reaction chamber (for pretreatment) to the second reaction chamber (for silicon nitride deposition) without being exposed to the ambient atmosphere. In other words, the method of the present disclosure may include processing materials in the same semiconductor processing equipment and forming a silicon nitride film on the substrate. The semiconductor processing equipment for steps 106 and 108 may include a cluster tool, which includes two or more reaction chambers and may further include a transfer chamber through which the substrate can be transferred between the first reaction chamber and the second reaction chamber. In some embodiments, the environment in the transfer chamber can be controlled, that is, the temperature, pressure, and ambient gas can be controlled such that the substrate is not exposed to the ambient atmosphere after step 106 and before step 108. Similarly, when step 104 is taken, the substrate may not be exposed to the surrounding environment between steps 104 and 106.

[0049] The step 108 of depositing a silicon nitride layer may include a CVD or a cyclic deposition process. The periodic (e.g., ALD) cycle may include exposing the substrate to a precursor (also referred to as a reactant), removing any unreacted precursor and / or reaction by-products 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), disilicon hexachloride (Si2Cl6), disilicon hexaiodide (Si2I6), and trisilicon octaiodide (Si3I8). In some cases, the precursor may include the same or a similar precursor used during step 104. The second reactant may include a nitrogen source, such as nitrogen gas, ammonia, hydrazine, or alkyl-hydrazine, where alkyl-hydrazine may refer to a hydrazine derivative that may include an alkyl functional group and may also include additional functional groups. Non-limiting exemplary embodiments of alkyl-hydrazine may include at least one of the following: tert-butyl hydrazine (C4H9N2H3), methyl hydrazine (CH3NHNH2), or dimethyl hydrazine ((CH3)2N2NH2). A hydrogen-containing gas, such as hydrogen gas, may be introduced into the reaction chamber together with nitrogen. According to at least some examples of the present disclosure, no plasma is formed when the precursor flows into the reaction chamber.

[0050] During the purge step, the precursor / reactant may be temporarily separated by an inert gas such as argon (Ar), nitrogen (N2), or helium (He) and / or a vacuum pressure to prevent or slow down the gas-phase reaction between the reactants and to enable a self-saturating surface reaction. However, in some embodiments, the substrate may be moved to separately contact the first gas-phase reactant and the second gas-phase reactant. Since, for example, in the case of ALD, the reaction may be self-saturating, strict temperature control of the substrate and precise dosing control of the precursor may not be required. However, a substrate temperature may be desirable such that the incidental gas species neither condense into a monolayer or multilayers nor thermally decompose on the surface.

[0051] In some embodiments, providing a silicon source precursor may include pulse-delivering one or more silicon precursors to the substrate over 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. Additionally, during the pulse delivery of the silicon halide source to the substrate, the flow rate of the silicon halide source may be less than 2000 sccm.

[0052] In some embodiments, providing a reactant may include pulse-delivering one or more reactants to the substrate over 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. During the pulse delivery of the nitrogen source to the substrate, the flow rate of the nitrogen source may be less than 4000 sccm, or less than 2000 sccm, or less than 1000 sccm, or even less than 250 sccm.

[0053] According to other examples of the present disclosure, the deposited silicon nitride layer 108 may include forming reactive species. For example, step 108 may include forming reactive reactant species by forming a plasma when the reaction stream is introduced into the reaction chamber. The 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 for step 108 (e.g., the time of the active plasma) may be in the range of about 1 millisecond to about 5 minutes. The power frequency for forming the plasma during the step of forming reactive reactant species in the reaction chamber may be between about 100 kHz and about 2.45 GHz.

[0054] The cyclic deposition (e.g., ALD) process (step 108) of depositing the silicon nitride layer may be repeated one or more times until the desired thickness of the silicon nitride layer is achieved. The cyclic deposition process may be used to form a silicon nitride film having a thickness between about 0.3 nm and about 30 nm or about 1 nm and about 10 nm.

[0055] Figure 2 Structure 200 according to an exemplary embodiment of the present disclosure is shown. Structure 200 includes a substrate 202, a material 204 in which trenches 208 are formed, and a silicon nitride layer 206 deposited in the trenches (features) 208.

[0056] 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 include silicon, another Group IV semiconductor material, a Group III-V semiconductor, and / or a Group II-VI semiconductor.

[0057] The material 204 may include any of the substrate materials mentioned above. For example, the material 204 may include an oxide, such as a Group IV or metal oxide, or a nitride, such as a Group IV or metal nitride. The silicon nitride layer 206 may include a silicon nitride layer deposited using a PEALD process - such as the PEALD process described herein.

[0058] Figure 4 The differences in the film thickness measurements of silicon nitride films deposited on silicon and silicon oxide features are shown 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 film thickness difference between the films deposited in SiO trenches and silicon trenches without pretreatment is significantly greater than the films deposited after pretreatment with constant power or pulsed power.

[0059] Figure 5Shows film thickness measurement values and shows the trench reduction at the trench entrance for processes without pretreatment and processes pretreated by constant power plasma and pulsed plasma processes. As shown, for the process without pretreatment, the trench reduction at the entrance of the feature is lower than that of the pulsed power pretreatment, and the trench reduction of the pulsed power pretreatment is lower than that of the constant power pretreatment.

[0060] Now turning to Figure 15 , shows a reactor system 1500 according to an exemplary embodiment of the present disclosure. 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.

[0061] The reactor system 1500 includes a pair of conductive flat electrodes 4, 2 that are parallel and face each other in the interior 11 (reaction zone) of the reaction chamber 3. Plasma can be excited in the reaction chamber 3 by applying HRF power (e.g., 100 kHz, 13.56 MHz, 27 MHz, 2.45 GHz, or any value therebetween) from a power supply 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. The electrode 4 can act as a gas distribution device, such as a shower plate. Reactant gases, dilution gases (if any), precursor gases, etc. can be introduced into the reaction chamber 3 through one or more of the gas lines 20, gas line 21, and gas line 22 and through the shower plate 4. Although shown with three gas lines, the reactor system 1500 can include any suitable number of gas lines.

[0062] In the reaction chamber 3, an annular duct 13 with an exhaust duct line 7 is provided, whereby the gas in the interior 11 of the reaction chamber 3 is exhausted. Additionally, a transfer chamber 5 disposed below the reaction chamber 3 has a seal gas line 24 to introduce seal gas into the interior 11 of the reaction chamber 3 through the interior 16 (transfer zone) of the transfer chamber 5, where a separation plate 14 for separating the reaction zone and the transfer zone is provided (the gate valve is omitted in this figure, and the substrate is transferred into or out of the transfer chamber 5 through the gate valve). The transfer chamber is also provided with an exhaust duct line 6. In some embodiments, deposition and / or surface treatment steps are performed in the same reaction space such that two or more (e.g., all) steps can be continuously carried out without exposing the substrate to air or other oxygen-containing atmospheres.

[0063] In some embodiments, the continuous flow of carrier gas to reaction chamber 3 can be achieved using a flow-through system (FPS), where the carrier gas line has a bypass line with a precursor reservoir (bottle), and the main line and the bypass line are switched, where when it is intended to feed only the carrier gas to the reaction chamber, the bypass line is closed, and when it is intended to feed both the carrier gas and the precursor gas to the reaction chamber, the main line is closed, and the carrier gas flows through the bypass line and exits the bottle together with the precursor gas. In this way, the carrier gas can continuously flow into the reaction chamber with substantially no pressure fluctuations in the reaction chamber and can carry the precursor gas in a pulsed manner by switching between the main line and the bypass line.

[0064] Reactor system 1500 can include one or more controllers 26 that are programmed or otherwise configured to cause one or more of the method steps described herein to be performed. As will be appreciated by those skilled in the art, controller 26 is coupled to various power supplies, heating systems, pumps, robotic devices, and gas flow controllers or valves of the reactor.

[0065] In some embodiments, a dual-chamber reactor (two sections or compartments for processing substrates disposed close to each other) can be used, where reactant gas and inert gas can be supplied through a shared line, while the precursor gas is supplied through a non-shared line.

[0066] Specific example

[0067] The examples provided below are only intended to be illustrative. These examples are not intended to limit the scope of the present disclosure or the claims.

[0068] Example 1: N2 / H2 pretreatment

[0069] Two blanket samples (a silicon substrate and a substrate with a thermal silicon oxide layer thereon) are introduced into the deposition reactor. The samples are heated by mounting them on a pedestal heater heated to a temperature of 450 °C. The gap between the lower electrode (pedestal heater) and the upper electrode (showerhead, gas introduction system) is 12 mm. The pressure is increased up to 350 Pa by the introduction of 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 down the introduction of hydrogen below the pedestal unit. 600 W of HRF power is applied between the upper and lower electrodes for durations of 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, and the gap is maintained at 12 mm. The following steps are repeated to achieve the deposition of the desired film thickness:

[0070] The silicon precursor was introduced into the chamber using a 2 slm N2 carrier gas through a tube heated at 75 °C. The feed time was 0.3 seconds.

[0071] The reaction chamber was purged with an N2 gas flow for 1 second.

[0072] 800 W RF power was turned on for 1.6 seconds. During this time, the reactant (nitrogen) continued to flow.

[0073] The reaction chamber was purged for 0.1 second.

[0074] Figure 6 Shows the evolution of the thickness difference between the thermal silicon oxide and the silicon overlay as a function of the H2 treatment time and concentration in nitrogen. It can be observed that increasing the pretreatment time decreases the thickness difference regardless of the hydrogen concentration. Additionally, the introduction of a large hydrogen content, e.g., above 3%, is used to obtain advantages over pure nitrogen plasma treatment.

[0075] Example 2: Hydrogen plasma pretreatment in 10%-20% nitrogen

[0076] Two trench-patterned samples (silicon substrate and substrate with silicon oxide) were introduced into the reaction chamber of the reactor. Both substrates contained trench structures with an aspect ratio of 12. The substrates were mounted on a pedestal heater and heated to a temperature of 450 °C. The gap between the lower electrode (pedestal heater) and the upper electrode (showerhead, gas introduction system) was 12 mm. The pressure was increased up to 350 Pa by the introduction of 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 reactor to slow down / prevent the introduction of hydrogen below the pedestal unit. 800 W of HRF power was applied between the upper and lower electrodes for durations ranging from 0 seconds to 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.

[0077] The following deposition steps were repeated to achieve the desired film thickness.

[0078] The silicon precursor was introduced into the chamber using a 2 slm N2 carrier gas through a tube heated at 75 °C. The feed time was 0.3 seconds.

[0079] The reaction chamber was purged with an N2 gas flow for 1 second.

[0080] 800 W RF power was turned on for 1.6 seconds.

[0081] The reaction chamber was purged for 0.1 second.

[0082] After the final deposition cycle, the reaction chamber was purged and evacuated, and the samples were removed from the reactor. The samples were then analyzed by STEM. Figure 11 Positions A - D are shown in.

[0083] Figure 7 and 8 show the evolution of the top thickness and sidewall thickness for different pretreatment times and H2 concentrations, which are 10% and 20% respectively. It can be seen that for a H2 concentration of 10%, a treatment duration of about 70 seconds may be required to eliminate the growth incubation of silicon and silicon oxide trenches ( Figure 7 ). For a H2 concentration of 20%, this treatment duration can be reduced to 45 seconds ( Figure 8 ). In addition, it can be observed that the thickness difference between points A, C, and D can be reduced compared to without pretreatment, and thus a higher step coverage is observed.

[0084] Example 3: OES analysis during N2 / H2 plasma pretreatment

[0085] The pedestal 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 (pedestal heater) and the upper electrode (showerhead, gas introduction system) is 12 mm.

[0086] The pressure in the reaction chamber is increased to as high as 350 Pa by introducing nitrogen and hydrogen. 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 reactor to prevent / slow down the introduction of hydrogen below the pedestal unit.

[0087] An HRF power of 300 W or 600 W is applied between the upper and lower electrodes for 45 seconds. An optical emission spectroscopy (OES) unit is used to analyze the reactive species emitted during plasma treatment and is connected to the chamber through an optical fiber unit fixed to the chamber wall viewing port. Refer to Figure 9 , it can be observed that the emission of N 2+ (emission wavelength: 391 nm) is highly correlated with the H2 concentration. Compared with pure N2 plasma, the emission increases and reaches saturation starting from a few percent of H2. When increasing the HRF power, the emission of reactive species such as Hα (emission wavelength: 656 nm) originating from H2 is favorable, as shown in Figure 10 . No saturation behavior is observed, which means that increasing the H2 ratio is an effective way to increase the Hα species.

[0088] Example 4: Ar / NH3 plasma pretreatment using the SiNPEALD process

[0089] Two trench-patterned samples (silicon substrate and substrate with a SiO x layer on it) are introduced into the reaction chamber of the reactor. Both substrates contain trench structures (features) with an aspect ratio of 10.

[0090] The sample is heated by heating the susceptor heater to 450 °C. The gap between the lower electrode (susceptor heater) and the upper electrode (spray head, 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 / slow down the introduction of argon and ammonia below the susceptor unit.

[0091] A HRF power of 300 W is applied between the upper and lower electrodes for a time of 45 s for time 1 or 230 s for time 2. The argon and ammonia flows are gradually stopped, and a flow of 12 slm of N2 and 5 sccm of H2 is introduced into the reaction chamber. Then the pressure in the reaction chamber is increased to 2000 Pa, and the gap is increased to 12 mm.

[0092] The following steps are repeated to achieve the desired film thickness deposition:

[0093] The silicon precursor is introduced into the chamber using 2 slm of N2 carrier gas through a tube heated at 75 °C. The feed time is 0.3 s.

[0094] Then the reaction chamber is purged with a N2 gas flow for 1 s.

[0095] 800 W of RF power is turned on for 1.6 s.

[0096] Then the reaction chamber is purged for 0.1 s.

[0097] After the deposition is completed, the chamber is purged and evacuated, and the sample is removed from the reactor.

[0098] The sample is analyzed by scanning transmission electron microscopy (STEM). Figure 12 Shows the evolution of the top and sidewall film thicknesses when the pretreatment time is increased. As shown, there is a difference of approximately 3 nm between the silicon substrate and the film deposited on a substrate containing a layer of SiO x ; for a pretreatment duration of 1, this difference is reduced to 2 nm, while for duration 2 it is less than 0.5 nm. It should also be noted that for a pretreatment time of duration 2, good film thickness uniformity is obtained on each structure. In Figure 12 , duration 1 is 45 s, and duration 2 is 230 s.

[0099] Example 5: N2 / NH3 plasma pretreatment before the SiNPEALD process

[0100] Two trench-patterned samples (silicon substrate and substrate with SiO x thereon) are introduced into the reaction chamber. Both substrates contain a trench structure with an aspect ratio of 10.

[0101] The sample is heated by heating the susceptor heater to 450 °C. The gap between the lower electrode (susceptor heater) and the upper electrode (showerhead, gas introduction system) is 12 mm.

[0102] The pressure in the reaction chamber is increased up to 350 Pa by the introduction of 9.75 slm of nitrogen and 0.25 slm of ammonia. 1.5 slm of N2 is introduced from the bottom of the reactor to prevent / slow down the introduction of ammonia below the susceptor unit.

[0103] An HRF power of 520 W is applied between the upper and lower electrodes for a time of 45 seconds for time 1 or 240 seconds for time 2.

[0104] The ammonia flow is gradually stopped, the N2 flow is increased to 12 slm, and a 5 sccm H2 flow is introduced into the reaction chamber. The pressure in the reaction chamber is increased to 2000 Pa and the gap is maintained at 12 mm.

[0105] The following steps are repeated to achieve the desired film thickness deposition:

[0106] The silicon precursor is introduced into the reaction chamber using 2 slm of N2 carrier gas through a tube heated at 75 °C. The feed time is 0.3 seconds.

[0107] The reaction chamber is purged with an N2 gas flow for 1 second.

[0108] 800 W of RF power is switched on for 1.6 seconds.

[0109] The reaction chamber is purged for 0.1 second.

[0110] After the deposition is completed, the chamber is purged and evacuated, and the sample is removed from the reactor. The sample is then analyzed by STEM. Figure 13 Shows the evolution of the top and sidewall film thicknesses when the pre-treatment time is increased. In the absence of pre-treatment, there is a difference of approximately 3 nm between the silicon substrate and the film deposited on the substrate containing SiO x ; for a pre-treatment duration of 1, this difference is reduced to approximately 1 nm, while for duration 2 it is below 0.6 nm. It should also be noted that for pre-treatment times of duration 1 and 2, good film thickness uniformity is obtained on each structure. In Figure 13 , duration 1 is 45 seconds and duration 2 is 240 seconds.

[0111] Example 6: Comparison of only Ar / NH3 plasma pretreatment and the combination of silane thermal adsorption and Ar / NH3 plasma pretreatment Comparison .

[0112] Two trench-patterned samples (silicon substrate and substrate with SiO x thereon) are introduced into the reaction chamber. Both substrates contain trench structures with an aspect ratio of 10.

[0113] The sample is heated by heating the pedestal heater to 450 °C. The gap between the lower electrode (pedestal heater) and the upper electrode (showerhead, gas introduction system) is 10 mm.

[0114] By introducing 4 slm of nitrogen and 100 sccm of silane, the pressure reaches 2000 Pa. After the pressure stabilizes, the flow of nitrogen and silane continues for 15 seconds. Then, the gas flow is stopped, and the reaction chamber is purged.

[0115] The pressure in the reaction chamber is increased to as high as 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 / slow down the introduction of argon and ammonia gas below the pedestal unit.

[0116] A HRF power of 300 W is applied between the upper and lower electrodes for a time of 45 seconds. The flow of argon and ammonia is gradually stopped, and a flow of 12 slm of N2 and 5 sccm of H2 is introduced into the reaction chamber. Then the pressure in the reaction chamber is increased to 2000 Pa, and the gap is increased to 12 mm.

[0117] The following steps are repeated to achieve the desired film thickness.

[0118] The silicon precursor is introduced into the chamber through a tube heated to 75 °C using 2 slm of N2 carrier gas. The feed time is 0.3 seconds.

[0119] The reaction chamber is purged with a N2 gas flow for 1 second.

[0120] 800 W RF power is turned on for 1.6 seconds.

[0121] Then the reaction chamber is purged for 0.1 seconds.

[0122] After the deposition is completed, the chamber is purged, and the sample is removed from the reactor.

[0123] The sample is analyzed by STEM. Figure 14 The evolution of the top and sidewall film thicknesses with or without the silane thermal adsorption step is shown. In the absence of the silane adsorption step, for the pretreatment duration 1, there is a difference of approximately 2 nm between the silicon substrate and the film deposited on the substrate containing SiO x ; when the silane adsorption step is added, the incubation is reduced to below 0.5 nm. It is also noted that good step coverage is maintained. In Figure 14 , the duration 1 is 45 seconds.

[0124] The example embodiments of the present disclosure described above do not limit the scope of the present invention, since these embodiments are merely examples of embodiments of the present invention, which is defined by the appended claims and their legal equivalents. Any equivalent embodiments are intended to be within the scope of the present invention. Indeed, various modifications of the present disclosure will be apparent to those skilled in the art from this specification, in addition to, for example, alternative applicable combinations of the described elements as shown and described herein. Such modifications and embodiments are also intended to fall within the scope of the appended claims.

Claims

1. A method of forming a silicon nitride layer, the method comprising the steps of: Providing a substrate in a reaction chamber; Exposing the substrate to a precursor containing silicon and hydrogen for thermal adsorption of silicon on the surface of the substrate without exposure to a plasma process; Exposing the substrate to reactive species formed from one or more gases including nitrogen and hydrogen to form N—H and / or N—H2 groups on the substrate surface; And Depositing a silicon nitride layer on the surface of the substrate in the reaction chamber where the N—H and / or N—H2 groups are formed, wherein the deposition process includes: Providing a precursor to the reaction chamber; Purging the reaction chamber; Forming reactive reactant species in the reaction chamber; and Purging the reactive reactant species.

2. The method according to claim 1, wherein the one or more gases including nitrogen and hydrogen include a nitrogen-containing gas and a hydrogen-containing gas.

3. The method according to claim 1, wherein the one or more gases including nitrogen and hydrogen include one or more of nitrogen, hydrogen, ammonia, hydrazine, or in combination with one or more of argon, helium.

4. The method according to claim 1, wherein the step of depositing the silicon nitride layer includes a plasma-enhanced deposition process, wherein a plasma is formed during the step of forming reactive reactant species in the reaction chamber.

5. The method according to claim 1, wherein reactants flow continuously during the steps of providing a precursor to the reaction chamber and forming reactive reactant species in the reaction chamber.

6. The method according to claim 5, wherein the reactants are selected from the group consisting of nitrogen, hydrogen, and ammonia.

7. The method according to claim 1, wherein the step of forming reactive reactant species in the reaction chamber includes forming reactive species from one or more gases including nitrogen and hydrogen.

8. The method according to claim 4, wherein the power frequency for forming a plasma during the step of forming reactive reactant species in the reaction chamber is between 100 kHz and 2.45 GHz.

9. The method according to claim 4, wherein the power for forming a plasma during the step of forming reactive reactant species in the reaction chamber is between 10 W and 4 kW.

10. The method according to claim 1, wherein the step of exposing the substrate to reactive species formed from one or more gases including nitrogen and hydrogen to form N—H and / or N—H2 groups on the substrate surface includes a pulsed plasma process, and the power frequency of the plasma is between 100 kHz and 2.45 GHz.

11. The method according to claim 1, wherein the step of exposing the substrate to reactive species formed from one or more gases including nitrogen and hydrogen to form N—H and / or N—H2 groups on the substrate surface includes a pulsed plasma process, and the power of the plasma is between 10 W and 4 kW.

12. A structure formed by the method according to any one of claims 1 to 11.

13. A system for performing the method according to any one of claims 1 to 11.

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