Method of depositing low dielectric constant materials

Abstract

Methods and systems for forming structures including a layer of low dielectric constant material on a surface of a substrate and structures and devices formed using the methods or systems are disclosed. An exemplary method includes providing a substrate within a reaction chamber of a reactor system, providing one or more precursors to the reaction chamber, providing one or more reactants, including a mixture of a nitrogen and oxygen containing reactant and a hydrogen containing reactant, and providing pulsed plasma power to polymerize the one or more precursors within the reaction chamber.

Description

Technical Field

[0001] This disclosure generally relates to methods for depositing layers and methods for forming structures suitable for manufacturing electronic devices. More specifically, examples of this disclosure relate to methods for forming structures including dielectric layers, to structures and devices including such layers, and to systems for performing the method and / or forming the structures and / or devices. Background Technology

[0002] During the fabrication of devices (such as semiconductor devices), it is generally desirable to fill features (such as trenches or gaps) on the substrate surface with dielectric materials. In some cases, it may be necessary to fill features with materials with low dielectric constants (low k), such as carbon materials (e.g., silicon carbide) or other dielectric materials, such as silicon oxide (SiO2). x ), silicon nitride (SiN) x For example, dielectric materials can be used as inter-metal dielectric layers on patterned metal features, gap fillers for fully aligned vias in back-end processes, internal isolation layers for gate-enclosed devices, and insulating layers in resistive random access memory (ReRAM) devices.

[0003] Some dielectric material deposition processes can use organosilanes or oxysilanes and oxidants to form initially flowable materials. Thermal energy or remote plasma can be used to deposit the material to activate the oxidant. This technique typically involves relatively long curing or annealing steps to increase the density of the deposited material and reduce its dielectric constant.

[0004] While these techniques work well for some applications, filling features using conventional deposition techniques has several drawbacks, especially as the size of the features to be filled decreases. For example, using conventional techniques, the dielectric constant of cured or annealed materials can change significantly (e.g., shift upwards), leading to undesirable variations in device performance. Furthermore, dielectric materials formed using typical techniques may be prone to blistering. Additionally, deposition steps and / or post-deposition steps (e.g., annealing or curing) can be relatively long.

[0005] Therefore, there is a need for improved methods for forming low dielectric constant materials on substrate surfaces, particularly methods for filling gaps on substrate surfaces with such materials, which mitigate variations in the dielectric constant of the material and / or provide desired material properties (e.g., less or no bubbling) and / or can be performed relatively quickly.

[0006] Any discussion set forth in this section (including discussions of problems and solutions) is included in this disclosure for the purpose of providing background information and should not be construed as an admission that any or all of the discussions were known at the time of making this invention or otherwise constitute prior art. Summary of the Invention

[0007] Various embodiments of this disclosure relate to methods for forming structures suitable for forming electronic devices. While various embodiments of the invention address the disadvantages of prior methods and structures in more detail below, in general, exemplary embodiments of the invention provide improved methods for forming structures comprising low-dielectric-constant materials, structures comprising low-dielectric-constant materials, and systems for performing said methods and / or forming said structures. The methods described herein can be used to fill features on a substrate surface. According to examples of this disclosure, low-dielectric-constant materials exhibit relatively little blistering and / or dielectric constant shift over time.

[0008] According to various embodiments of this disclosure, a method for depositing a low-dielectric-constant material on the surface of a substrate is provided. Examples of this method include providing a substrate within a reaction chamber, the substrate having gap features on its surface thereon, providing one or more precursors into a reaction space within the reaction chamber, providing reactants into the reaction space, and providing pulsed plasma power to at least one electrode to form a plasma within the reaction space, thereby forming the low-dielectric-constant material. According to aspects of these examples, the reactants comprise (e.g., 4 vol% or more) a mixture of nitrogen- and oxygen-containing reactants and (e.g., the remainder) hydrogen-containing reactants. For example, the reactants may consist, alone or together with an inert gas, of or substantially composed of nitrogen- and oxygen-containing reactants and hydrogen-containing reactants. In some cases, the hydrogen-containing reactants comprise nitrogen. For example, the hydrogen-containing reactants may be or include NH3 or C. x H y One or more of NH2, wherein x is between 1 and 3, and y is between 3 and 7. Nitrogen and oxygen reactants may be or include N. x O y Where x is 1-2 and y is 1-4. According to examples of this disclosure, the reactants do not include O2, O3, H2O, and / or H2O2. According to various aspects of these examples, one or more precursors include alkoxysilane precursors. Alkoxysilane precursors may be derived from the formula SiO2. x C y H z The formula is represented as follows: x is between 1 and 4, y is between 3 and 10, and z is between 9 and 24. In some cases, at least one of the precursors comprises a cyclic structure containing a chemical formula represented by -(Si(R1,R2)-O)n-, where n is in the range of about 3 to about 10, and where R1 and R2 are independently selected from H, CH3, C2H5, C2H3, CH(CH3)2, CH2CH(CH3)2, OCH3, OC2H5, C3H6-NH2. In some cases, at least one of the precursors comprises a linear structure containing a chemical formula represented by R3-(Si(R1,R2)-O)n-. m -O (m-1)The chemical formula is represented by )-R4, where m can range from about 1 to about 7, and where R1, R2, R3, and R4 are independently selected from H, CH3, C2H5, C2H3, CH(CH3)2, CH2CH(CH3)2, OCH3, OC2H5, and C3H6-NH2. According to another aspect, the duty cycle of the power applied to at least one electrode during the step of providing pulsed plasma power to at least one electrode is between 1% and 50%. According to another example, the method includes the step of curing a low-dielectric-constant material to form a cured low-dielectric-constant material. In this case, the method may further include the step of treating the cured low-dielectric-constant material to form a treated low-dielectric-constant material.

[0009] According to further exemplary embodiments of this disclosure, a structure is formed at least in part according to the methods described herein. The structure may include a low-dielectric-constant material. The low-dielectric-constant material may be deposited on features with an aspect ratio of 1:1 or greater. According to examples of this disclosure, the dielectric constant of the low-dielectric-constant material varies by less than 2% over three days or more in the surrounding environment. In some cases, the dielectric constant of the low-dielectric-constant material decreases in the surrounding environment. According to another example, the leakage current of the low-dielectric-constant material decreases in the surrounding environment.

[0010] According to another example of this disclosure, a device may be formed and / or include the structures described herein using methods. The device may be, or include, for example, a FinFET, a gate-enclosed nanowire FET, a cross-point cell, a memory device, or a logic device.

[0011] According to yet another exemplary embodiment of this disclosure, a system is provided for performing the methods described herein and / or for forming structures as described herein.

[0012] 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

[0013] Exemplary embodiments of this disclosure can be more fully understood when considered in conjunction with the following illustrative drawings, and by referring to the detailed description and claims.

[0014] Figure 1 A method according to an exemplary embodiment of the present disclosure is shown.

[0015] Figure 2 The normalized dielectric constant values ​​are shown as a function of time for various process conditions, including those according to this disclosure.

[0016] Figure 3Optical emission spectra from the UV region of the deposited plasma, measured by a spectrometer, are shown for various process conditions (including those according to this disclosure).

[0017] Figure 4A and Figure 4B The FTIR absorption spectrum of the material deposited according to an exemplary embodiment of the present disclosure is shown, normalized by film thickness (in nm).

[0018] Figure 5 Gap-filling performance under various process conditions is illustrated, including those according to exemplary embodiments of this disclosure.

[0019] Figure 6 An example of reduced bubbling of low dielectric constant materials during post-deposition processing is shown according to the present disclosure.

[0020] Figure 7 The substrate after a two-step process according to an example of this disclosure is shown.

[0021] Figure 8 The generation of OH in a plasma with a combination of N2O and NH3, as measured by OES, is shown.

[0022] Figure 9 A pulsed plasma step according to an example of this disclosure is shown.

[0023] Figure 10 The structure of another example according to this disclosure is shown.

[0024] Figure 11 A reactor system according to an embodiment of the present disclosure is shown.

[0025] Figure 12 A FinFET structure including a dielectric material layer is shown according to an exemplary embodiment of the present disclosure.

[0026] Figure 13 A gate-enclosed device structure including a dielectric material layer is shown according to another exemplary embodiment of the present disclosure.

[0027] Figure 14 An exemplary embodiment of the present disclosure is shown, comprising a cross-point device structure including a dielectric material layer.

[0028] Figure 15 A device structure including a back-end process intermetallic dielectric gap filling layer is shown according to an exemplary embodiment of the present disclosure.

[0029] Figure 16 A device structure including a back-end fully aligned via structure and a gap-filling layer is shown according to an exemplary embodiment of the present disclosure.

[0030] 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 may be exaggerated relative to other elements to aid in understanding the embodiments shown in this disclosure. Detailed Implementation

[0031] Although certain embodiments and examples are disclosed below, those skilled in the art will understand that the invention extends beyond the specific embodiments and / or uses disclosed herein, as well as their obvious modifications and equivalents. Therefore, it is intended that the scope of the disclosed invention should not be limited to the specific embodiments described below.

[0032] This disclosure generally relates to methods for depositing low-dielectric-constant materials on the surface of a substrate, methods for forming structures and devices, structures and devices formed using the methods, and systems for performing the methods and / or forming structures and devices. For example, the methods described herein can be used to fill features, such as gaps (e.g., trenches or vias), on the surface of a substrate with a low-dielectric-constant material. The terms gap and recess are used interchangeably herein.

[0033] To mitigate void and / or gap formation during the gap-filling process, the deposited material may initially be flowable and flow within the gap to fill it. The exemplary structures described herein can be used in a variety of applications and devices, including but not limited to cell isolation in 3D cross-point memory devices, self-aligned vias, dummy gates, inverse tone patterns, PCRAM isolation, diced hard masks, DRAM memory node contact (SNC) isolation, inter-metal gap-filling layers as patterned metal features (which may include one or more of, for example, Ru, Co, Cu, Ta, TaN, Ti, TiN, W), gap filling for fully aligned vias in back-end process (BEOL) processes, dielectrics on dielectrics in BEOL processes (e.g., for memory or logic devices), internal isolation for gate-enclosed devices, insulating layers in resistive random access memory (ReRAM) devices, shallow trench isolation layers in FinFET devices, and the like.

[0034] As described in more detail below, exemplary methods can be used to form structures comprising low-dielectric-constant materials. According to examples of this disclosure, the deposited low-dielectric-constant material exhibits a relatively low dielectric constant shift (i.e., the dielectric constant does not change significantly over time). Alternatively or additionally, the methods described herein can be used to deposit low-dielectric-constant materials that exhibit relatively little bubbling during post-processing.

[0035] In this disclosure, "gas" can refer to materials that are gases at room temperature and pressure, evaporated solids, and / or evaporated liquids, and may consist of a single gas or a mixture of gases, depending on the circumstances. Gases other than process gases, i.e., gases introduced without passing through gas distribution components (such as spray heads, other gas distribution devices, etc.), can be used, for example, to seal the reaction space, including sealing gases, such as rare gases. In some cases, such as in the context of material deposition, the term "precursor" can refer to a compound that participates in a chemical reaction to produce another compound, particularly a compound constituting the membrane matrix or the membrane backbone, while the term "reactant" can refer, in some cases, to a compound other than a precursor, which activates, modifies, or catalyzes the reaction of the precursor; when, for example, power (e.g., radio frequency (RF) power) is applied, the reactant can provide elements (e.g., O, H, N, C) to the membrane matrix and become part of the membrane matrix. In some cases, the terms "precursor" and "reactant" are used interchangeably. In some cases, the reactant can include multiple compounds. The term inert gas refers to a gas that does not participate in a chemical reaction to a perceptible degree and / or that excites precursors (e.g., to promote the polymerization of precursors) when power is applied, such as RF power, but unlike reactants, it may not become part of the membrane matrix to a perceptible degree. Exemplary inert gases include argon, helium, nitrogen, and any mixtures thereof.

[0036] 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 are formed. A substrate may comprise a bulk material, such as silicon (e.g., single-crystal silicon), other group IV materials (e.g., germanium), or compound semiconductor materials (e.g., group III-V or II-VI semiconductors), and may comprise one or more layers overlying or underlying the bulk material. Furthermore, a substrate may include various features such as gaps (e.g., recesses or vias), lines, or protrusions, such as lines with gaps formed therebetween, formed on or within at least a portion of the layers or bulk material of the substrate. For example, one or more features may have a width of about 10 nm to about 100 nm, a depth or height of about 30 nm to about 1000 nm, and / or an aspect ratio of about 1, 3, 10, 100, or greater.

[0037] In some embodiments, a membrane refers to a layer extending in a direction perpendicular to the thickness direction. In some embodiments, a layer refers to a material of a certain thickness formed on a surface, and can be synonymous with a membrane or non-membrane structure. A membrane or layer may 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 based on the physical, chemical and / or any other properties, formation process or sequence, and / or function or purpose of adjacent membranes or layers. A layer or membrane may be continuous or discontinuous. Furthermore, a single membrane or layer may be formed using one or more deposition cycles and / or one or more deposition and processing cycles.

[0038] As used herein, the terms low dielectric constant material or low-k material layer or low-k material can refer to a material with a dielectric constant less than that of silicon dioxide or less than 3.8 or between about 2.5 and about 3.

[0039] As used herein, the term structure can refer to a device structure that is partially or fully fabricated. For example, a structure can be a substrate or a substrate having one or more layers and / or features formed thereon.

[0040] As used herein, the term cyclic deposition process can refer to a vapor phase deposition process in which deposition cycles (typically multiple consecutive deposition cycles) are performed in a processing chamber. Cyclic deposition processes can include cyclic chemical vapor deposition (CVD) and atomic layer deposition (ALD) processes. A cyclic deposition process may include one or more cycles, each cycle involving plasma activation of precursors, reactants, and / or inert gases.

[0041] In this disclosure, "continuous" can refer to the immediate following of a step without breaking the vacuum, without interruption as a timeline, without any material intervention step, without change in processing conditions, or, in some embodiments and depending on the circumstances, to discrete physical or chemical structures that do not involve intervention between two structures other than the two structures described.

[0042] Liquidity (e.g., initial liquidity) can be determined as follows:

[0043] Table 1

[0044]

[0045] Here, B / T refers to the ratio of the film thickness deposited at the bottom of the recess before it is filled to the film thickness deposited on the top surface forming the recess. Typically, wide recesses with an aspect ratio of about 1:1 or smaller are used to evaluate flowability because generally, the higher the aspect ratio of the recess, the higher the B / T ratio becomes. A higher aspect ratio of the recess usually results in a higher B / T ratio. As used herein, flowable films or materials exhibit good or better flowability.

[0046] As explained in more detail below, when one or more precursors are polymerized using, for example, stimulated polymerization with plasma, a material flowability can be temporarily achieved. The resulting polymer material may exhibit temporarily flowable behavior. When the deposition step is complete and / or after a short period of time (e.g., about 3.0 seconds), the film may no longer be flowable and instead solidify, thus eliminating the need for a separate curing process. In some cases, a curing step may be used.

[0047] In this disclosure, any two numbers of a variable may constitute a feasible range of the variable, and any range indicated may include or exclude endpoints. Furthermore, any value of the indicated variable (whether or not it is indicated by an approximation) may refer to an exact value or an approximate value and include equivalents, and in some embodiments may refer to an average, median, representative value, multi-value, etc. Additionally, in this disclosure, the terms "comprising," "consisting of," and "having," etc., in some embodiments may independently mean generally or broadly comprising, including, substantially consisting of, or composed of. The meaning of any definition in this disclosure does not necessarily exclude the common and customary meaning in some embodiments.

[0048] Now turn to the attached image. Figure 1 A method 100 for depositing a low dielectric constant material on a substrate surface according to an exemplary embodiment of the present disclosure is illustrated. Method 100 includes the steps of: providing a substrate in a reaction chamber (step 102), providing one or more precursors to the reaction chamber (step 104), providing reactants (step 106), and providing pulsed plasma power to polymerize one or more precursors in the reaction chamber (step 108). Method 100 may further include a processing step (step 110) and / or a curing step (step 112). As shown, method 100 may include repeating steps 104-110 (loop 114) multiple times prior to step 112 and / or repeating steps 104-112 multiple times (loop 116).

[0049] During step 102, the substrate is provided into the reaction chamber of the vapor phase reactor. According to examples of this disclosure, the reaction chamber may form part of a chemical vapor deposition reactor, such as a plasma-enhanced chemical vapor deposition (PECVD) reactor or a plasma-enhanced atomic layer deposition (PEALD) reactor. Various steps of the methods described herein may be performed in a single reaction chamber or in multiple reaction chambers (e.g., reaction chambers of clustered tools). The following is in conjunction with… Figure 11 An exemplary reactor is described in more detail.

[0050] During step 102, the substrate may be brought to a desired temperature and / or the reaction chamber may be brought to a desired pressure, such as a temperature and / or 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 less than or equal to 450°C, less than or equal to 300°C, or less than or equal to 200°C.

[0051] As mentioned above, for typical low-dielectric-constant material deposition techniques, especially those performed at temperatures less than or equal to 200°C, the dielectric constant of the low-dielectric-constant material can shift or change over time. This leads to a degradation in device performance. The deposition techniques described herein mitigate or eliminate these problems.

[0052] During step 104, when providing one or more precursors to the reaction chamber, one or more precursors for forming a low-dielectric-constant material layer are provided to the reaction space within the reaction chamber. Exemplary precursors may include compounds comprising carbon and / or silicon. According to examples of this disclosure, one or more precursors include compounds comprising a cyclic structure. The cyclic structure may include silicon, such as silicon and oxygen. One or more precursors may include compounds comprising Si-O bonds. One or more precursors may include compounds comprising organosilicon compounds, such as cyclic organosilicon compounds. One or more precursors may include compounds comprising siloxanes and / or alkoxysilanes. An exemplary alkoxysilane precursor may be derived from the formula SiO x C y H z This indicates that z is between 1 and 4, y is between 3 and 10, and z is between 9 and 24.

[0053] Specific exemplary precursors include one or more of the following: octamethylcyclotetrasiloxane (OMCTS), tetramethylcyclotetrasiloxane (TMCTS), octamethoxydodecylsiloxane (OMODDS), octamethoxycyclotetrasiloxane (OMOCTS), dimethyldimethoxysilane (DM-DMOS), diethoxymethylsilane (DEMS), dimethoxymethylsilane (DMOMS), vinylmethyldimethoxysilane (VMDMOS), phenoxydimethylsilane (PODMS), dimethyldioxosilylcyclohexane (DMDOSH), 1,3-dimethoxytetramethyldisiloxane (DMOTMDS), dimethoxydiphenylsilane (DMDPS), and dicyclopentyldimethoxysilane (DcPDMS).

[0054] According to another example of this disclosure, one or more precursors comprise amino-alkylsiloxane precursors, such as 1,3-bis(3-aminopropyl)tetramethyldisiloxane. According to another example of this disclosure, at least one of the precursors comprises a ring structure comprising a chemical formula represented by -(Si(R1,R2)-O)n-, wherein n is in the range of about 3 to about 10 or about 3 to about 6, and wherein R1 and R2 are independently selected from H, CH3, C2H5, C2H3, CH(CH3)2, CH2CH(CH3)2, OCH3, OC2H5, C3H6-NH2.

[0055] As a specific example, n can be 4 and R1=R2=CH3; or n can be 4, R1=H, and R2=CH3. According to another example, at least one of one or more precursors comprises a linear structure consisting of R3–(Si(R1,R2)). m -O (m-1) The chemical formula is represented by )-R4, where m can range from about 1 to about 7 or from about 1 to about 4, and where R1, R2, R3, and R4 are independently selected from H, CH3, C2H5, C2H3, CH(CH3)2, CH2CH(CH3)2, OCH3, OC2H5, and C3H6-NH2. As a specific example, m can be 1, R1=R2=CH3, and R3=R4=OCH3; m can be 2, R1=R2=CH3, and R3=R4=OCH3; or m can be 2, R1=C3H6-NH2, R2=CH3, and R3=R4=CH3.

[0056] The flow rate of one or more precursors to the reaction chamber can vary depending on other process conditions. For example, the flow rate can be from about 100 sccm to about 3000 sccm. Similarly, the duration of each step in which the precursor is supplied to the reaction chamber can vary, depending on various considerations.

[0057] During step 106, one or more reactants are provided to the reaction chamber. The one or more reactants may flow into the reaction space of the reaction chamber simultaneously with or concurrently with the step of providing one or more precursors to the reaction chamber. In this case, a CVD reaction can occur. In some cases, reactants and / or one or more precursors may be pulsed into the reaction chamber for a cyclic process, such as a cyclic CVD or ALD process.

[0058] The exemplary reactants provided during step 106 comprise a mixture of 4 vol% or more of a nitrogen- and oxygen-containing reactant and a hydrogen-containing reactant. The nitrogen- and oxygen-containing reactant may be or includes N... x O y Where x is between 1 and 2, and y is between 1 and 4. Hydrogen-containing reactants include nitrogen and / or carbon in addition to hydrogen. In some cases, hydrogen-containing reactants include NH3 and C. x H y One or more of NH2, wherein x is between 1 and 3, and y is between 3 and 7. In some cases, hydrogen-containing reactants include one or more of any combination of NH3, mixtures of nitrogen and hydrogen, and amino-group reactants (e.g., hydrazine, monomethylamine, dimethylamine, trimethylamine, monoethylamine, and diethylamine). According to examples of this disclosure, reactants do not include O2, O3, H2O, and / or H2O2 (e.g., greater than trace amounts—e.g., less than 1 or 0.5 or 0.1 volume%).

[0059] Using certain oxidants, such as O2, O3, H2O, and / or H2O2, it is possible to generate OH or H2O in the plasma, which undesirably increases the dielectric constant of low-dielectric-constant materials. Furthermore, some combinations of alkoxysilane precursors with oxidants and / or reactants can generate hydrophilic functional groups, such as CO or OH, in the film, which cause the dielectric constant of low-dielectric-constant materials to decrease (e.g., increase) over time by absorbing moisture.

[0060] According to examples of this disclosure, the use of nitrogen- and oxygen-containing reactants, particularly in conjunction with alkoxysilane precursors, produces low-dielectric-constant materials exhibiting relatively low dielectric constant variations over time. Furthermore, the use of nitrogen- and oxygen-containing reactants allows for an increase in precursor variety while maintaining the desired properties of low-dielectric-constant materials.

[0061] In some cases, an inert gas may be supplied to the reaction space during method 100. Exemplary inert gases include helium or argon, or mixtures thereof.

[0062] During step 108, pulsed plasma power is supplied to at least one electrode to form a plasma within the reaction space, thereby forming a low dielectric constant material. For example, during step 108, one or more precursors or derivatives thereof are polymerized into an initial viscous material using an excited substance. The initial viscous carbon material can become a solid material—for example, through further reaction with the excited substance and / or during curing step 110.

[0063] The plasma formed during step 108 can be generated using a direct plasma system, such as the direct plasma system described in more detail below in conjunction with reactor system 1100, and / or a remote plasma system. The power used to generate the plasma during step 106 can be between 10 W and 2000 W, or between about 300 W and about 500 W. For single or dual (e.g., RF) power supplies, the power frequency can be in the range of 1000 kHz to 200 MHz. In some cases, the power frequencies used to provide pulsed plasma power include high RF frequencies (e.g., above 1 MHz or about 13.56 MHz) and low RF frequencies (e.g., less than 500 kHz or about 430 kHz). The low-frequency power can be applied to the anode or cathode of the plasma generation system. The pulse on-time of the low RF frequency power can be from about 1 kHz to about 100 kHz, and the duty cycle can be from about 10% to about 100%, or less than 50%, or between 1% and 50%.

[0064] During the step of providing pulsed plasma power to at least one electrode, the pressure within the reaction space can be between 10 Pa and 10,000 Pa. The temperature during step 108 can be below 200°C.

[0065] Figure 9 A pulsed plasma step 900 according to an example of this disclosure is shown. Figure 1 and Figure 9 As shown, step 104, which provides one or more precursors, can begin at time t1. Optionally, one or more reactants can be provided to the reaction chamber at t1 or before t2. Subsequently, at t2, plasma power is provided to polymerize one or more precursors. At t3, the flow of one or more precursors and / or reactants is stopped, and at t4, the power to form the plasma is reduced to extinguish the plasma. The example shown could be a pulsed plasma-enhanced chemical vapor deposition method.

[0066] During the time interval between t2 and t4, the plasma power can be pulsed, such as... Figure 9The enlarged portion is shown. The pulse may include a pulse on-time 902 and a pulse off-time 904, which can be repeated during t2-t4. The pulse on-time 902 of the pulsed plasma power can be less than 50 microseconds, or about 10 microseconds to about 20 microseconds. The pulse off-time 904 can be longer than the pulse on-time 902—for example, 2 or 5 times longer than the pulse on-time, or about 7 to about 10 times longer than the pulse on-time. Alternatively, the RF duty cycle can be less than 50% (e.g., between 1% and 50%). The RF on-time and RF off-time are considered to be able to control the flowable deposition process by influencing the adhesion coefficient of the polymer precursor. If a long RF on-time is applied, too much precursor excitation may occur in the gas phase, resulting in the formation of large particles, such as flakes, in the gas phase. Furthermore, a short RF off-time may lead to particle and void formation due to insufficient surface migration. By controlling the chemical reaction and adhesion coefficient of the precursor at the substrate surface using pulsed plasma, good gap-filling capability and high film quality of the deposited dielectric material layer are achieved.

[0067] Return again Figure 1 Method 100 may include a curing step 110. During step 110, a low-dielectric-constant material is used to form the cured low-dielectric-constant material. Step 110 may be or include thermal curing—that is, the substrate may not be exposed to plasma during thermal curing. During step 110, an oxidant and / or an inert gas and / or hydrogen and helium may be provided. The oxidant may be selected from, for example, any combination of CO. x One or more of O2, O3, isopropanol, H2O, or other oxidants described herein. The substrate temperature may be below 500°C during the thermal curing step. In some cases, as described in more detail below, step 110 may include two or more steps.

[0068] As shown in the figure, method 100 may further include a processing step 112. During step 112, the cured low dielectric constant material is processed to form a processed low dielectric constant material.

[0069] During step 112, one or more of the following can be used: capacitively coupled plasma (CCP) with an inert gas, microwave excitation, very high frequency (VHF) excitation, and ultraviolet (UV) excitation, to, for example, densify the deposited material, reduce the dielectric constant of the deposited material, etc. During the post-deposition processing steps, the substrate temperature may be below 500°C.

[0070] Figure 2The normalized dielectric constant (k-value) and leakage shift over time are shown for various combinations of reactants and oxidants used to form the low dielectric constant material. The addition of O2 as an oxidant shows the worst shift over time, while the addition of N2O (a nitrogen- and oxygen-containing reactant) as an oxidant shows no shift over time. According to examples of this disclosure, the dielectric constant of the low dielectric constant material changes by less than 2% over three days or more in the ambient environment. In some cases, the dielectric constant leakage current of the low dielectric constant material decreases over time (e.g., over three days or more) in the ambient environment.

[0071] Figure 3 The optical emission spectra of the UV region from the deposition plasma, measured by a spectrometer, are shown. OH peaks are clearly detected in the O2-added plasma, while no OH peaks are shown in the spectrum of the N2O-added plasma. The plasma without added reactants and oxidants (He / precursor) also does not exhibit OH peaks in the optical emission spectra from the plasma. OH substances in the plasma are thought to be absorbed into the film as -OH terminators or H2O, which reduces the reliability of the k-value and leakage current, especially for low-temperature deposition processes, as it cannot enhance the thermal reaction of OH to generate stable Si-O bonds.

[0072] Figure 4A and Figure 4B The FTIR absorption spectra normalized to film thickness (nm) are shown. The deposited film with O2 in plasma at 3450 ± 20 nm... cm-1 A distinct OH peak is shown at the location, such as Figure 4A As shown. This is related to the OH detected in the light emission of the plasma. Figure 4B The CO region of the FTIR absorption spectrum is shown. The deposited film with O2 in plasma at 1725 ± 20°C... cm-1 A distinct CO peak is observed. These OH and CO bonds make the membrane hydrophilic, which increases the membrane's water uptake. The deposited membrane with N2O-added plasma exhibits smaller OH and CO peaks than when O2 is used as an oxidant.

[0073] Figure 5 The gap-filling performance under various process conditions is shown. The oxidant-free condition exhibits clear voids in the trenches; however, the oxidant-based condition shows good gap-filling performance.

[0074] Figure 6 An example of reduced bubbling of low dielectric constant materials is shown during post-deposition processing (e.g., steps 110 and / or 112). Figure 6A comparison is shown between precursor + He (inert gas) + N₂O deposition and precursor + He + N₂O + NH₃ (hydrogen-containing reactant) deposition. The elastic modulus (EM) of the deposited film increases with increasing NH₃ flow rate. The higher EM of the deposited film suppresses bubble generation in the post-processing steps. The highest NH₃ flow rate conditions show K₃ and EM of 18 GPa, as well as good gap filling without foaming.

[0075] Figure 7 The silicon substrate after the two-step process is shown. As illustrated, the sample without NH3 deposition exhibits severe blistering after the two-step process. In the example shown, the two-step process comprises a first low-temperature treatment (e.g., in N2O plasma, at a temperature between 50°C and 200°C for a duration between approximately 30 seconds and approximately 400 seconds) and a second curing treatment (e.g., in hydrogen and helium plasma, at a temperature between 200°C and 400°C for a duration between approximately 30 seconds and approximately 400 seconds).

[0076] Figure 8 The image shows OH generation in a plasma containing a combination of N2O and NH3, as measured by OES. Darker shaded areas indicate OH generation, while lighter shaded areas do not.

[0077] Figure 10 A structure 1000 according to another example of this disclosure is shown. Structure 1000 can be formed using, for example, method 100.

[0078] Structure 1000 includes a substrate 1002, one or more features 1004, 1006, a gap 1008 between features 1004, 1006, and a low-dielectric-constant material 1010. Structure 1000 can be used to fabricate various devices and / or for various applications, including shallow trench isolation layers for FET devices, including FinFET shallow trench isolation gap filling applications, gate-surrounded nanowire device isolation gap filling applications, crossover devices, memory or logic devices, etc.

[0079] Substrate 1002 may be or include any suitable substrate material, such as the substrate (bulk and / or layer) materials mentioned herein. In some cases, substrate 1002 may include an insulating or dielectric material. In these cases, the structure may include a dielectric-on-dielectric (DOD) gap-filling structure comprising a dielectric material layer 1010. DOD gap-filling structures are useful in BEOL processes, particularly in the fabrication of logic and memory devices.

[0080] Features 1004 and 1006 can be formed of various materials, such as insulating, semi-conductive, or conductive materials. For example, features 1004 and 1006 can be intermetallic features comprising one or more of Ru, Co, Cu, Ta, TaN, Ti, TiN, and W, wherein a low-dielectric-constant material layer 1010 forms an intermetallic gap-filling layer between two or more of features 304 and 306.

[0081] According to examples of this disclosure, the low dielectric constant material layer 1010 comprises silicon, oxygen, and carbon. The low dielectric constant material layer 1010 may include various properties of the dielectric material layers described herein.

[0082] Figure 12 A FinFET structure 1200 according to another example of the present disclosure is shown. The FinFET structure 1200 includes a substrate 1202, fins 1204, gate features 1208-1212, and a low dielectric constant material 1214.

[0083] Substrate 1202 may comprise any suitable substrate material, such as those described herein. Fin 1204 may comprise one or more lateral nanowires, including at least one of, for example, silicon, germanium, silicon-germanium, combinations thereof, or other semiconductor materials. Gate structures 1208-1212 may comprise, for example, a dielectric layer and a conductive layer. Low-dielectric-constant material 1214 may comprise a low-dielectric-constant material formed using the methods described herein.

[0084] Figure 13 A gate-enclosed device structure 1300 according to another exemplary embodiment of the present disclosure is illustrated. The gate-enclosed device structure 1300 includes a substrate 1302, fins 1304-1310, and a low-dielectric-constant material 1312. The substrate 1302 may include any suitable substrate material, such as those described herein. The fins 1304-1310 may include semiconductor materials, such as at least one of silicon, germanium, silicon-germanium, or combinations thereof. The gate structure may include, for example, a dielectric layer and a metal layer. The low-dielectric-constant material 1312 may be or include a dielectric material layer formed using the methods described herein.

[0085] Figure 14 A cross-point (e.g., memory) device structure 1400 according to another exemplary embodiment of the present disclosure is illustrated. The cross-point device structure 1400 includes a plurality of bit lines 1402, a plurality of word lines 1404, a plurality of memory elements 1406, a plurality of selector devices 1408, and a low-dielectric-constant material 1410 surrounding at least a portion of the memory elements 1406 and / or selector devices 1412. The low-dielectric-constant material 1410 may include a dielectric material layer formed using the methods described herein.

[0086] Figure 15 A device structure 1500 according to another exemplary embodiment of the present disclosure is shown. Structure 1500 includes a first device 1502, a second device 1504, conductive plugs 1506-1516, interconnect structures 1518-1528, and a low-dielectric-constant material 1530 surrounding at least a portion of the interconnect structures 1518-1528. The low-dielectric-constant material 1530 may include a dielectric material layer formed using the methods described herein. Figure 15 The method described herein is illustrated for use in back-end process (BEOL) intermetallic dielectric (IMD) gap filling applications.

[0087] Figure 16 A device structure 1600 according to another exemplary embodiment of the present disclosure is shown. Device structure 1600 includes conductive features 1604-1608 formed within an insulating material 1602, insulating structures 1610-1616, and a low-dielectric-constant material 1618 covering the conductive lines 1604-1608 and the insulating structures 1610-1616. The low-dielectric-constant material 1618 may include a dielectric material layer formed using the methods described herein. Figure 16 The use of dielectric material layer 1618 in a fully aligned through-via (FAV) structure in back-end process (BEOL) fabrication is shown.

[0088] Now go to Figure 11 The diagram illustrates a reactor system 1100 according to exemplary embodiments of the present disclosure. The reactor system 1100 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.

[0089] The reactor system 1100 includes a pair of parallel, facing conductive plate electrodes 4, 2 within the interior 11 (reaction zone) of the reaction chamber 3. Plasma can be excited within the reaction chamber 3 by applying HRF power (e.g., 13.56 MHz or 27 MHz) and / or low-frequency power 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 can be provided in the lower platform 2 (lower electrode), and the temperature of the substrate 1 placed thereon can be maintained at a desired temperature. Electrode 4 can serve as a gas distribution device, such as a spray plate. Reactant gases, dilution gases (if any), precursor gases, etc., can be introduced into the reaction chamber 3 via gas lines 20, 21, and 22, respectively, and through the spray plate 4. Although shown with three gas lines, the reactor system 1100 may include any suitable number of gas lines.

[0090] In the reaction chamber 3, a circular pipe 13 with an exhaust line 7 is provided, through which gases in the interior 11 of the reaction chamber 3 can be discharged. Additionally, a transfer chamber 5 located below the reaction chamber 3 is provided with a sealing gas line 24 to introduce sealing gas into the interior 11 of the reaction chamber 3 via the interior 16 (transfer zone) of the transfer chamber 5. A separation plate 14 for separating the reaction zone and the transfer zone is provided (a gate valve is omitted from the figure; this gate valve is used to transfer the wafer into or out of the transfer chamber 5). The transfer chamber is also provided with an exhaust line 6. In some embodiments, the deposition and processing steps are performed in the same reaction space, allowing two or more (e.g., all) steps to be performed consecutively without exposing the substrate to air or other oxygen-containing atmospheres.

[0091] In some embodiments, a flow-through system (FPS) can be used to achieve continuous flow of inert gas or carrier gas to reaction chamber 3. The carrier gas line is provided with a bypass line having a precursor reservoir (bottle), and the main line and bypass line are switched. When only carrier gas is intended to be fed into the reaction chamber, the bypass line is closed; when both carrier gas and precursor gas are intended to be fed into the reaction chamber, the main line is closed, and the carrier gas flows through the bypass line and exits from the bottle along with the precursor gas. In this way, the carrier gas can flow continuously into the reaction chamber, and the precursor gas can be carried in pulses by switching between the main line and the bypass line, with minimal pressure fluctuations in the reaction chamber.

[0092] Those skilled in the art will understand that the device includes one or more controllers 26, which are programmed or otherwise configured to cause one or more method steps as described herein to be performed. As those skilled in the art will understand, the controllers communicate with valves of various power sources, heating systems, pumps, robots, and airflow controllers or reactors.

[0093] In some embodiments, a dual-chamber reactor (for processing two sections or compartments of a wafer positioned close to each other) may be used, wherein reactant gases and rare gases may be supplied via a shared pipeline, while precursor gases may be supplied via a non-shared pipeline.

[0094] 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 intended to fall within the scope of the invention. In fact, various modifications to this disclosure, such as alternative useful combinations of the described elements, in addition to those shown and described herein, will become apparent to those skilled in the art from the description. These modifications and embodiments are also intended to fall within the scope of the appended claims.

Claims

1. A method for depositing a low dielectric constant material on the surface of a substrate, the method comprising: A substrate is provided in the reaction chamber, and the surface of the substrate contains gap features. Provide one or more precursors to the reaction space within the reaction chamber; Provide reactants to the reaction space; and Pulsed plasma power is supplied to at least one electrode to form plasma within the reaction space, thereby forming a low dielectric constant material. The reactants comprise a mixture of nitrogen- and oxygen-containing reactants and hydrogen-containing reactants at a volume percentage of 4% or more.

2. The method according to claim 1, wherein, One or more precursors include alkoxysilane precursors.

3. The method according to claim 2, wherein, The alkoxysilane precursor is made of the formula SiO z C y H z This indicates that z is between 1 and 4, y is between 3 and 10, and z is between 9 and 24.

4. The method according to claim 3, wherein, At least one of the one or more precursors comprises a ring structure comprising a chemical formula represented by -(Si(R1,R2)-O)n-, wherein n is in the range of about 3 to about 10, and wherein R1 and R2 are independently selected from H, CH3, C2H5, C2H3, CH(CH3)2, CH2CH(CH3)2, OCH3, OC2H5, C3H6-NH2.

5. The method according to claim 3, wherein, At least one of the one or more precursors comprises a linear structure consisting of R3-(Si(R1,R2)). m -O (m-1) The chemical formula is represented by )-R4, where m can be in the range of about 1 to about 7, and where R1, R2, R3 and R4 are independently selected from H, CH3, C2H5, C2H3, CH(CH3)2, CH2CH(CH3)2, OCH3, OC2H5, C3H6-NH2.

6. The method according to claim 3, wherein, The alkoxysilane precursors include one or more of the following: octamethylcyclotetrasiloxane (OMCTS), tetramethylcyclotetrasiloxane (TMCTS), octamethoxydodecylsiloxane (OMODDS), octamethoxycyclotetrasiloxane (OMOCTS), dimethyldimethoxysilane (DM-DMOS), diethoxymethylsilane (DEMS), dimethoxymethylsilane (DMOMS), vinylmethyldimethoxysilane (VMDMOS), phenoxydimethylsilane (PODMS), dimethyldioxosilylcyclohexane (DMDOSH), 1,3-dimethoxytetramethyldisiloxane (DMOTMDS), dimethoxydiphenylsilane (DMDPS), and dicyclopentyldimethoxysilane (DcPDMS).

7. The method according to claim 1, wherein, The hydrogen-containing reactants include nitrogen.

8. The method according to claim 5, wherein, The hydrogen-containing reactants include NH3 and C. x H y One or more of NH2, wherein x is between 1 and 3 and y is between 3 and 7.

9. The method according to claim 1, wherein, The nitrogen- and oxygen-containing reactants contain N x O y , where x is between 1 and 2, and y is between 1 and 4.

10. The method of claim 1, further comprising providing an inert gas, wherein the inert gas comprises helium or argon.

11. The method according to claim 1, wherein, The reactants do not contain O2.

12. The method according to claim 1, wherein, The method described is pulsed plasma enhanced chemical vapor deposition.

13. The method according to claim 1, wherein, The temperature is below 200°C during the step of providing pulsed plasma power to at least one electrode.

14. The method according to claim 1, wherein, The power applied to the at least one electrode is between 10W and 2000W.

15. The method according to claim 1, wherein, The duty cycle of the power applied to the at least one electrode during the step of providing pulsed plasma power to the at least one electrode is between 1% and 50%.

16. The method according to claim 1, wherein, During the step of providing pulsed plasma power to at least one electrode, the pressure within the reaction space is between 10 Pa and 10,000 Pa.

17. The method according to claim 1, wherein, The hydrogen-containing reactants include NH3.

18. The method of claim 1, further comprising the step of curing the low dielectric constant material to form a cured low dielectric constant material.

19. The method of claim 18, further comprising the step of treating the cured low dielectric constant material to form a treated low dielectric constant material.

20. The method according to claim 1, wherein, The dielectric constant of the low dielectric constant material changes by less than 2% over three days or more in the surrounding environment.

21. The method according to claim 1, wherein, The dielectric constant of the low dielectric constant material decreases in the surrounding environment.

22. The method according to claim 1, wherein, The leakage current of the low dielectric constant material is reduced in the surrounding environment.

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