Method for selectively forming silicon nitride film on sidewall of trench

Abstract

A method of forming a layer of dielectric material on a surface of a substrate is provided. The method may include providing a substrate within a reaction chamber; flowing the precursor over the substrate within the reaction chamber; flowing a reactant onto the substrate; and generating a plasma by a dual radio frequency (RF) plasma source including a high frequency (HF) component and a low frequency (LF) component. The precursor reacts with the reactant to form the layer by generating the plasma, and the pressure in the reaction chamber is between 2000 and 4000 Pa at least during the step of providing the plasma.

Description

Technical Field

[0001] The present disclosure generally relates to methods of forming silicon nitride films. More specifically, examples of the present disclosure relate to methods of selectively forming silicon nitride films on trench sidewalls using plasma. Background Art

[0002] In the manufacturing process of large-scale integrated circuits (LSI), there are various processes for forming sidewalls in trenches. The sidewalls are used as spacers or to prevent etching structures from the side surfaces of the trenches. Traditionally, the sidewalls are formed by forming a conformal film on the surface of the trench and then removing the portion formed on the upper surface where the trench is formed and the portion formed on the bottom surface of the trench by asymmetric etching. However, when this formation method is used, over-etching is required to remove the root of the sidewalls, wherein the thickness of the sidewalls increases near the bottom and at the bottom to form a slope. Over-etching causes etching of the lower layer and causes damage to the layer structure.

[0003] One method of forming sidewalls in a trench is to use high RF power at low pressure. An exemplary method is disclosed in US Pat. No. 9,754,779, which is incorporated herein by reference. When forming sidewalls in a trench, it is necessary to use high pressure.

[0004] Any discussion set forth in this section, including discussion of problems and solutions, has been included in the present disclosure merely to provide a context for the present disclosure and should not be considered as an admission that any or all of the discussion was known or constituted prior art at the time the present invention was made. Summary of the invention

[0005] This summary is provided to introduce some concepts in a simplified form. These concepts are further described in detail in the detailed description of the example embodiments disclosed below. This summary is not intended to identify the key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

[0006] According to an exemplary embodiment of the present disclosure, a method for forming a layer in a groove formed in an upper surface of a substrate is provided. The method may include: providing a substrate in a reaction chamber; flowing a precursor on the substrate in the reaction chamber; flowing a reactant onto the substrate; and generating plasma by a dual radio frequency (RF) plasma source including a high frequency (HF) component and a low frequency (LF) component; wherein the precursor reacts with the reactant to form a layer; wherein at least during the step of providing the plasma, the pressure in the reaction chamber is between 2000 and 4000 Pa.

[0007] In various embodiments, the high frequency (HF) power may have a frequency in a range between about 13 MHz and about 27 MHz, and the low frequency (LF) power may have a frequency in a range between about 100 KHz and about 500 KHz.

[0008] In various embodiments, the high frequency RF power may be between about 400 Watts and about 800 Watts, and the low frequency RF power may be between about 400 Watts and about 800 Watts.

[0009] In various embodiments, the reactants may be provided continuously.

[0010] In various embodiments, the duration of flowing the precursor may be between about 0.3 seconds and about 2.0 seconds.

[0011] In various embodiments, the duration of generating the plasma may be between about 0.5 seconds and about 30 seconds.

[0012] In various embodiments, the temperature within the reaction chamber may be between about 350°C and about 450°C.

[0013] In various embodiments, the layer may include a dielectric layer containing Si—N bonds.

[0014] In various embodiments, the thickness of the dielectric layer may be between 4 nm and 15 nm.

[0015] In various embodiments, the precursor may include at least one of: a silane, a silylamine, an aminosilane, or a silicon halide compound.

[0016] In various embodiments, the precursor may include at least one of the following: silane (SiH4), disilane (Si2H6), trisilane (Si3H8), tetrasilane (Si4H10), N(Si2H5)3, trisilylamine N(SiH3)3, N(SiMe3)(SiHMeNMe2)2, 2,2-dimethylsilyltrisilane (Si(SiH3)4), trimethylaminosilane (SiH(NMe2)3), bis(diethylamino)silane (SiH2(NEt2)2)(BEDAS), bis(tert-butylamino)silane (SiH2(NHtBu)2) (BTBAS), diisopropylamino)silane (SiH3(NiPr2))(DIPAS), wherein Me represents methyl, Et represents ethyl, tBu represents tert-butyl, iPr represents isopropyl, trichlorodisilane (Si2Cl3H3), pentachlorodisilane (Si2Cl5H), hexachlorodisilane (Si2Cl6), octachlorotrisilane (Si3Cl8), dichlorosilane (SiCl2H2), dimethyldichlorosilane (SiCl2Me2), tetrachlorosilane (SiCl4), tetraiodosilane (SiI4), triiodosilane (SiI3H) or diiodosilane (SiI2H2).

[0017] In various embodiments, the reactant may include a nitrogen precursor.

[0018] In various embodiments, the nitrogen precursor may include at least one of: N 2 , NH 3 , a mixture of N 2 and H 2 , or a combination thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] A more complete understanding of exemplary embodiments of the present disclosure may be obtained by referring to the detailed description and claims when considered in conjunction with the following illustrative drawings.

[0020] Figure 1 A method according to an exemplary embodiment of the present disclosure is shown.

[0021] Figure 2 A timing sequence according to an exemplary embodiment of the present disclosure is shown.

[0022] Figure 3a A graph showing the relationship between RF power and a wet etching rate of a film formed on a top surface of a trench and a wet etching rate of a film formed on a sidewall of the trench in a prior art reference.

[0023] Figure 3b A graph showing the relationship between RF power and a wet etching rate of a film formed on a top surface of a trench and a wet etching rate of a film formed on a sidewall of the trench according to an exemplary embodiment of the present disclosure is shown.

[0024] Figure 4A scanning transmission electron microscope image of a structure according to an exemplary embodiment of the present disclosure is shown.

[0025] Figure 5 A plasma reactor system according to an exemplary embodiment of the present disclosure is shown.

[0026] It should be understood that the elements in the drawings are shown for simplicity and clarity and are not necessarily drawn to scale. For example, the size of some elements in the drawings may be exaggerated relative to other elements to help understand the illustrated embodiments of the present disclosure. DETAILED DESCRIPTION

[0027] 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. Therefore, it is intended that the scope of the disclosed invention should not be limited by the specifically disclosed embodiments described below.

[0028] As used herein, the term "substrate" may refer to any one or more underlying materials, including any one or more underlying materials that may be modified or on which a device, circuit, or film may be formed. A "substrate" may be continuous or non-continuous; rigid or flexible; solid or porous; and combinations thereof. A substrate may be in any form, such as a powder, a plate, or a workpiece. A plate-like substrate may include wafers of various shapes and sizes. A substrate may be made of semiconductor materials, including, for example, silicon, silicon germanium, silicon oxide, gallium arsenide, gallium nitride, and silicon carbide.

[0029] For example, a substrate in powder form may have applications in pharmaceutical manufacturing. A porous substrate may comprise a polymer. Examples of workpieces may include medical devices (e.g., stents and syringes), jewelry, tooling equipment, components for battery manufacturing (e.g., anodes, cathodes, or separators), or components for photovoltaic cells, etc.

[0030] The continuous substrate may extend beyond the boundaries of the processing chamber in which the deposition process occurs. In some processes, the continuous substrate may be moved through the processing chamber so that the process continues until the end of the substrate is reached. The continuous substrate may be provided from a continuous substrate feed system to allow the continuous substrate to be manufactured and output in any suitable form.

[0031] Non-limiting examples of continuous substrates may include sheets, nonwoven films, rolls, foils, meshes, flexible materials, bundles of continuous filaments or fibers (eg, ceramic fibers or polymer fibers). A continuous substrate may also include a carrier or sheet on which a discontinuous substrate is mounted.

[0032] The illustrations presented herein are not meant to be actual views of any particular material, structure, or device but are merely idealized representations used to describe embodiments of the present disclosure.

[0033] The specific embodiments shown and described are illustrations of the present invention and its best mode and are not intended to limit the scope of these aspects and embodiments in any way. In fact, for the sake of brevity, the traditional manufacturing, connection, preparation and other functional aspects of the system may not be described in detail. In addition, the connecting lines shown in the various figures are intended to represent exemplary functional relationships and / or physical connections between various elements. Many alternative or additional functional relationships or physical connections may exist in actual systems, and / or may not exist in some embodiments.

[0034] It should be understood that the configuration and / or method described herein are exemplary in nature, and these specific embodiments or examples should not be considered restrictive, because many variations are possible. The specific routine or method described herein can represent one or more of any number of processing strategies. Therefore, the various actions shown can be performed in the order shown, in other orders, or omitted in some cases.

[0035] The subject matter of the present disclosure includes all novel and nonobvious combinations and subcombinations of the various processes, systems and configurations, and other features, functions, acts and / or properties disclosed herein, and any and all equivalents thereof.

[0036] In the present disclosure, "gas" may include materials that are gaseous at normal temperature and pressure, evaporated solids, and / or evaporated liquids, and may be composed of a single gas or a gas mixture depending on the situation. Gas introduced without passing through a gas supply unit (e.g., a shower plate, etc.) may be used, for example, to seal a reaction space, and may include sealing gases such as rare gases or other inert gases. The terms inert gas, carrier gas, and diluent gas refer to gases that do not participate in chemical reactions to an appreciable degree and / or gases that are capable of exciting precursors when plasma power is applied.

[0037] As used herein, the terms "film" and "thin film" may refer to any continuous or discontinuous structure and material deposited by the methods disclosed herein. For example, "film" and "thin film" may include 2D materials, nanorods, nanotubes or nanoparticles, or even partial or complete molecular layers or partial or complete atomic layers or clusters of atoms and / or molecules. "Film" and "thin film" may include materials or layers with pinholes, but still at least partially continuous.

[0038] Figure 1A method 100 for selectively forming a film on a trench sidewall according to an exemplary embodiment of the present disclosure is shown. The method 100 includes: providing a substrate 102 in a reaction chamber; flowing a precursor on the substrate in the reaction chamber 104; flowing a reactant onto the substrate 106; and generating a plasma 108 by a dual radio frequency (RF) plasma source including a high frequency (HF) component and a low frequency (LF) component. By providing the plasma, the precursor reacts with the reactant to form a layer. In addition, at least during the step of providing the plasma, the pressure in the reaction chamber is between 2000 and 4000 Pa.

[0039] like Figure 1 As shown, a substrate is provided into a reaction chamber of a gas phase reactor during step 102. According to an example of the present disclosure, the reaction chamber may form a part of an atomic layer deposition reactor, such as a plasma enhanced atomic layer deposition (PEALD) reactor.

[0040] During step 102, the substrate may be brought to a desired temperature and the reaction chamber may be brought to a desired pressure, such as a temperature and pressure suitable for subsequent steps. For example, the temperature within the reaction chamber (e.g., the temperature of the substrate or substrate support) may be between 350° C. and 450° C. According to a specific example of the present disclosure, the substrate includes one or more features, such as grooves.

[0041] During the step 104 of flowing the precursor on the substrate to the reaction chamber, a precursor for forming a film is introduced into the reaction chamber. Exemplary precursors may include at least one of the following: silane, silylamine, aminosilane, or a halogenated silicon compound. Exemplary precursors may include at least one of the following: silane (SiH4), disilane (Si2H6), trisilane (Si3H8), tetrasilane (Si4H10), N(Si2H5)3, trisilylamine N(SiH3)3, N(SiMe3)(SiHMeNMe2)2, 2,2-disilyltrisilane (Si(SiH3)4), trimethylaminosilane (SiH(NMe2)3), bis(diethylamino)silane (SiH2(NEt2)2)(BEDAS), bis(tert-butylamino)silane (SiH2(NHtBu)2)(BT BAS), diisopropylamino)silane (SiH3(NiPr2))(DIPAS), wherein Me represents methyl, Et represents ethyl, tBu represents tert-butyl, iPr represents isopropyl, trichlorodisilane (Si2Cl3H3), pentachlorodisilane (Si2Cl5H), hexachlorodisilane (Si2Cl6), octachlorotrisilane (Si3Cl8), dichlorosilane (SiCl2H2), dimethyldichlorosilane (SiCl2Me2), tetrachlorosilane (SiCl4), tetraiodosilane (SiI4), triiodosilane (SiI3H) or diiodosilane (SiI2H2).

[0042] During step 106, reactants may be provided to the reaction chamber. Exemplary reactants provided in step 106 may include a nitrogen precursor. Exemplary nitrogen precursors may include at least one of: N2, NH3, a mixture of N2 and H2, or a combination thereof.

[0043] During the step of providing plasma 108, plasma 108 is generated using a direct plasma system by a dual radio frequency (RF) plasma source including a high frequency (HF) component and a low frequency (LF) component. By providing plasma, the precursor reacts with the reactant to form a layer. The high frequency (HF) may have a frequency in a range between about 13 MHz and about 27 MHz, and the low frequency (LF) power may have a frequency in a range between about 100 KHz and about 500 KHz. The high frequency RF power may be between about 400 watts and about 800 watts, and the low frequency RF power may be between about 400 watts and about 800 watts.

[0044] Figure 2 The timing according to an exemplary embodiment of the present disclosure is shown. The reactants may be provided continuously. The duration of flowing the precursor may be between about 0.3 seconds and about 2.0 seconds. The duration of generating the plasma may be between about 0.5 seconds and about 30 seconds. Step 110 may be repeated multiple times, such as 200-800 cycles, to form the layer. The thickness of the dielectric layer may be between 4 nm and 15 nm.

[0045] Figure 3a A graph showing the relationship between HRF power and the wet etching rate of a film formed on the top surface of a trench and the wet etching rate of a film formed on the sidewall of a trench in a prior art reference is shown. The pressure is 350 Pa. The wet etching rate of the sidewall portion decreases as the HRF power increases, while the wet etching rate of the top / bottom portion increases as the HRF power increases, wherein the line representing the former and the line representing the latter intersect at an HRF power of about 600 W. That is, the threshold HRF power is about 600 W, and it can be understood that when the HRF power applied between the electrodes is higher than about 600 W, the top / bottom portion of the film can be selectively removed relative to the sidewall portion of the film, and when the HRF power applied between the electrodes is lower than about 600 W, the sidewall portion of the film can be selectively removed relative to the top / bottom portion of the film.

[0046] Figure 3b A graph showing the relationship between the HRF power and the wet etching rate of the film formed on the top surface of the trench and the wet etching rate of the film formed on the sidewall of the trench according to an exemplary embodiment of the present disclosure is shown. Under a high pressure of 3000 Pa, as the HRF power increases, the wet etching rate of the sidewall portion and the top / bottom portion is maintained.

[0047] Example

[0048] A SiN film was formed on a Si substrate (0300 mm) having a groove by PEALD. Figure 4 The PEALD apparatus shown was subjected to one cycle under the conditions shown in Table 1 below. After the substrate was taken out of the reaction chamber, the substrate was wet etched under the conditions shown in Table 1 below.

[0049] Table 1

[0050]

[0051]

[0052] (Numbers are approximate)

[0053] Figure 4 A scanning transmission electron microscope image of a structure according to an exemplary embodiment of the present disclosure is shown. By using dual frequency HRF / LRF (ie, also adding LRF), reverse topological selectivity (RTS) can be achieved even at high voltages.

[0054] Figure 5 A plasma reactor system 500 is shown according to an exemplary embodiment of the present disclosure. The plasma reactor system 500 can be used to perform one or more steps or sub-steps described herein, and / or form one or more structures described herein, or portions thereof.

[0055] The plasma reactor system 500 may include a pair of conductive plate electrodes 4, 2 that are parallel and face each other in the interior 11 (reaction zone) of the reaction chamber 3. Plasma can be ignited in the reaction chamber 3 by applying HF power (e.g., 13.56 MHz or 27 MHz) and LF power (e.g., 450 kHz) from a power source 25 to one electrode (e.g., electrode 4) and electrically grounding the other electrode (e.g., electrode 2). A temperature regulator may be provided in the lower platform 2 (lower electrode), and the temperature of the substrate 1 placed thereon may be maintained at a desired temperature. The electrode 4 may be used as a gas distribution device, such as a shower plate. Reactant gas, dilution gas (if any), precursor gas, etc. may be introduced into the reaction chamber 3 through the shower plate 4 using one or more of the gas pipelines 20, gas pipelines 21, and gas pipelines 22, respectively. Although three gas pipelines are shown, the reactor system 500 may include any suitable number of gas pipelines.

[0056] In the reaction chamber 3, a circular duct 13 with an exhaust line 7 may be provided, through which the gas in the interior 11 of the reaction chamber 3 may be exhausted. In addition, the transfer chamber 5 disposed below the reaction chamber 3 may be provided with a sealed gas line 24 to introduce the sealed gas into the interior 11 of the reaction chamber 3 via the interior 16 (transfer zone) of the transfer chamber 5, wherein a partition plate 14 for separating the reaction zone and the transfer zone may be provided (a gate valve through which the wafer is transferred into or out of the transfer chamber 5 is omitted in this figure). The transfer chamber may also be provided with an exhaust line 6. In some embodiments, the deposition and treatment steps may be performed in the same reaction space, so that two or more (e.g., all) steps may be performed continuously without exposing the substrate to air or other oxygen-containing atmospheres.

[0057] In some embodiments, the continuous flow of inert gas or carrier gas to the reaction chamber 3 can be achieved using a flow system (FPS), wherein the carrier gas line can be provided with a detour line having a precursor reservoir (bottle), and the main line and the detour line can be switched, wherein when only the carrier gas is intended to be supplied to the reaction chamber, the detour line is closed, and when both the carrier gas and the precursor gas are intended to be supplied to the reaction chamber, the main line can be closed, the carrier gas can flow through the detour line, and out of the bottle together with the precursor gas. In this way, the carrier gas can flow continuously into the reaction chamber, and the precursor gas can be delivered in pulses by switching between the main line and the detour line without significantly fluctuating the pressure of the reaction chamber.

[0058] Those skilled in the art will appreciate that the apparatus includes 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. The controller is in communication with various power sources, heating systems, pumps, robots, and gas flow controllers or valves of the reactor, as those skilled in the art will appreciate.

[0059] In some embodiments, a multi-chamber reactor (two or more sections or compartments located close together for processing wafers) may be used, wherein reactant gases and inert gases may be supplied through shared lines, while precursor gases are supplied through non-shared lines.

[0060] The exemplary embodiments disclosed above do not limit the scope of the present invention, because these embodiments are merely examples of embodiments of the present invention. Any equivalent embodiments are within the scope of the present invention. In fact, various modifications of the present disclosure, such as alternative useful combinations of the described elements, will become apparent to those skilled in the art from the description, except those 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 layer in a groove formed in an upper surface of a substrate, comprising: providing a substrate within a reaction chamber; flowing a precursor over a substrate within a reaction chamber; flowing reactants over a substrate within a reaction chamber; as well as generating a plasma by a dual radio frequency (RF) plasma source including a high frequency (HF) component and a low frequency (LF) component; wherein a precursor reacts with a reactant to form a layer; Therein, at least during the step of providing the plasma, the pressure in the reaction chamber is between 2000 and 4000 Pa.

2. The method according to claim 1, wherein: The high frequency (HF) power has a frequency in a range between about 13 MHz and about 27 MHz, and the low frequency (LF) power has a frequency in a range between about 100 KHz and about 500 KHz.

3. The method according to any one of claims 1 and 2, wherein: The high frequency RF power is between about 400 Watts and about 800 Watts, and the low frequency RF power is between about 400 Watts and about 800 Watts.

4. The method according to any one of claims 1 to 3, wherein: The reactants are provided continuously.

5. The method according to any one of claims 1 to 4, wherein: The duration of flowing the precursor is between about 0.3 seconds and about 2.0 seconds.

6. The method according to any one of claims 1 to 5, wherein: The duration of generating the plasma is between about 0.5 seconds and about 30 seconds.

7. The method according to any one of claims 1 to 6, wherein: The temperature within the reaction chamber is between about 350°C and about 450°C.

8. The method according to any one of claims 1 to 7, wherein: The layers include a dielectric layer containing Si-N bonds.

9. The method according to claim 8, wherein: The thickness of the dielectric layer is between 4 nm and 15 nm.

10. The method according to any one of claims 1 to 9, wherein: The precursor includes at least one of the following: silane, silylamine, aminosilane or a silicon halide compound.

11. The method according to claim 10, wherein: The precursor includes at least one of the following: silane (SiH4), disilane (Si2H6), trisilane (Si3H8), tetrasilane (Si4H10), N(Si2H5)3, trisilylamine N(SiH3)3, N(SiMe3)(SiHMeNMe2)2, 2,2-dimethylsilyltrisilane (Si(SiH3)4), trimethylaminosilane (SiH(NMe2)3), bis(diethylamino)silane (SiH2(NEt2)2)(BEDAS), bis(tert-butylamino)silane (SiH2(NHtBu)2)(BTB AS), diisopropylamino)silane (SiH3(NiPr2))(DIPAS), wherein Me represents methyl, Et represents ethyl, tBu represents tert-butyl, iPr represents isopropyl, trichlorodisilane (Si2Cl3H3), pentachlorodisilane (Si2Cl5H), hexachlorodisilane (Si2Cl6), octachlorotrisilane (Si3Cl8), dichlorosilane (SiCl2H2), dimethyldichlorosilane (SiCl2Me2), tetrachlorosilane (SiCl4), tetraiodosilane (SiI4), triiodosilane (SiI3H) or diiodosilane (SiI2H2).

12. The method according to any one of claims 1 to 11, wherein: The reactants include a nitrogen precursor.

13. The method according to claim 12, wherein: The nitrogen precursor includes at least one of: N2, NH3, a mixture of N2 and H2, or a combination thereof.

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