Novel precursors for depositing films with high elastic modulus

Abstract

SUMMARY OF THE INVENTION A method for producing a dense organosilicon film having improved mechanical properties includes providing a substrate in a reaction chamber; introducing a gaseous composition comprising a hydrido-dimethyl-alkoxysilane into the reaction chamber; and applying energy to the gaseous composition comprising the hydrido-dimethyl-alkoxysilane in the reaction chamber to induce a reaction of the gaseous composition comprising the hydrido-dimethyl-alkoxysilane to deposit an organosilicon film on the substrate, wherein the organosilicon film has a dielectric constant of about 2.70 to about 3.50, an elastic modulus of about 6 to about 36 GPa, and an atomic % carbon of about 10 to about 36 as measured by XPS.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Application No. 63 / 003,068, filed March 31, 2020, and U.S. Provisional Application No. 63 / 104,440, filed October 22, 2022. Both provisional applications are incorporated by reference in their entireties into this application. [Background technology]

[0002] Described herein are compositions and methods for the formation of dense organosilica dielectric films using a novel class of hydrido-dimethyl-alkoxysilanes as film precursors. More specifically, described herein are compositions and chemical vapor deposition (CVD) methods for forming dense films having a dielectric constant k≧2.7, with the as-deposited films having higher electric field at breakdown, lower leakage current, higher resistance to plasma-induced damage (PID), and higher mechanical properties at the same value of dielectric constant compared to films made from prior art precursors.

[0003] The electronics industry uses dielectric materials as an insulating layer between circuit and integrated circuit (IC) components and associated electronic devices. Line dimensions continue to shrink to increase the speed and memory storage capacity of microelectronic devices (e.g., computer chips). As line dimensions decrease, the insulating requirements of the interlayer dielectric (ILD) become much more stringent. The shrinking line spacing requires a lower dielectric constant to minimize the RC time constant, where R is the resistance of the conductive line and C is the capacitance of the insulating dielectric interlayer. The capacitance (C) is inversely proportional to the line spacing and proportional to the dielectric constant (k) of the interlayer dielectric (ILD). Conventional silica (SiO2) CVD dielectric films produced from SiH4 or TEOS (Si(OCH2CH3)4, tetraethyl orthosilicate) and O2 have a dielectric constant k greater than 4.0. There are several methods that the industry has attempted to produce silica-based CVD films with lower dielectric constants, the most successful of which is doping insulating silicon oxide films with organic groups, providing dielectric constants in the range of about 2.7 to about 3.5. These organosilica glasses (or low-k films) are typically produced as dense films (density about 1.5 g / cm3) from organosilicon precursors, such as methylsilane or siloxane, and an oxidizer, such as O2 or NO. 3) as the dielectric constant or "k" value decreases below 2.7 at higher device densities and smaller dimensions, the industry has exhausted most suitable low-k compositions for dense films and is turning to various porous materials for improved insulating performance. Unfortunately, while the incorporation of organic groups and / or the introduction of porosity into the silicon oxide network decreases the dielectric constant, it also significantly decreases the mechanical properties of the film. In fact, as taught in U.S. Pat. Nos. 8,137,764 and 9,922,818, the mechanical properties of dense low-k films decrease much more rapidly than the dielectric constant as the percentage of organic groups in the low-k silicon oxide-based network increases (FIG. 1). Similarly, the mechanical properties of porous low-k films decrease more rapidly than the dielectric constant as the percentage of porosity of the low-k silicon oxide-based network increases. However, at the most advanced technology nodes at the lowest level of back-end interconnect processing, dense low-k materials with the highest possible mechanical properties are required. In addition to providing benefits to chip packaging and CMP, improved mechanical properties in low-k films reduce line edge roughness of patterned features, reduce pattern breakage, and provide greater internal mechanical stresses in interconnects, reducing electromigration-induced failures. The need for improved mechanical properties becomes more critical as pitch decreases at advanced technology nodes, especially at the bottom layers of back-end interconnect processing. This requirement is forcing the search for novel dense low-k films with relatively high dielectric constants (k<3.5) and the highest possible mechanical properties.

[0004] Many methods have been reported to improve the mechanical properties of low-k films. These include, but are not limited to, thermal treatment (US Pat. No. 6,846,515), broadband ultraviolet (UV) curing (US Pat. No. 8,951,342), and the use of curing agents (US Pat. No. 8,137,764). However, the simplest method to improve mechanical properties is to use low-k precursors that inherently result in the deposition of low-k films with superior mechanical properties. For example, US Pat. No. 6,846,515 shows that diethoxymethylsilane (DEMS®) precursor deposits low-k films with k of 3.5 or less, which have unexpectedly superior mechanical properties, as expressed by Young's modulus and nanoindentation hardness, compared to other precursors trimethylsilane (TMS) and dimethyldimethoxysilane (DMDMOS). This was attributed to the DEMS®-based films having a higher oxygen content and lower carbon content relative to other films at the same value of dielectric constant. The increased oxygen content is believed to result in better three-dimensional network connectivity and therefore improved mechanical properties. The use of a single low-k precursor that inherently results in the deposition of low-k films with excellent mechanical properties without additional post-deposition steps (i.e., in the as-deposited film) also results in a simplified process regime with the lowest cost of ownership since throughput is maximized (no post-deposition steps are required) and no additional tooling (i.e., UV anneal chambers) is required.

[0005] It has also been observed that in high density low k films, as the number of silicon-alkoxy groups (e.g., Si-OCH3, Si-OCH2CH3, etc.) in the low k precursor increases and the number of silicon-carbon bonds (e.g., Si-CH3, Si-CH2CH3, etc.) in the precursor decreases, the dielectric constant and mechanical properties of the as-deposited films increase and the carbon content in the films decreases. Thus, films deposited using precursors containing four silicon-alkoxy groups and no silicon-carbon bonds per silicon atom in the precursor (e.g., TEOS) have higher dielectric constants, greater mechanical properties, and less carbon than films deposited using precursors containing three silicon-alkoxy groups per silicon and no more than one silicon-carbon bond per silicon (e.g., triethoxysilane or TES and methyltriethoxysilane or MTES), which in turn have higher dielectric constants, greater mechanical properties, and less carbon than films deposited using precursors containing two silicon-alkoxy groups and one or two silicon-carbon bonds per silicon (e.g., DEMS® and DMDMOS), which in turn have higher elastic moduli than films deposited using precursors containing only one silicon-alkoxy group and no more than three silicon-carbon bonds per silicon (e.g., diethylisopropoxymethylsilane and trimethylsilane). Indeed, in US Patent No. 8,137,764, this concept was used to enhance the mechanical properties of dense low-k films by depositing the films with a controlled mixture of two different precursors during the deposition process. One precursor (hardener) selected to improve the mechanical properties of the film, e.g., TEOS and triethoxysilane (TES), contained 3-4 silicon-oxygen bonds per silicon atom and no silicon-carbon bonds. The second precursor, a low-k precursor, e.g., DEMS® or DMDMOS, contained one or more silicon-carbon bonds. A representative example was the deposition of a low-k film with a mixture of TES (50%) and DEMS® (50%).The resulting k=3.17 film deposited using the mixture of TES and DEMS® had a higher hardness (1.76 GPa) than the film deposited using only DEMS® (1.58 GPa) at similar values ​​of dielectric constant. The higher hardness of the low-k film deposited from the mixture of TES and DEMS® was attributed to the higher oxygen content, and possibly lower carbon content, of the film relative to the film deposited using only DEMS®. The increased oxygen content and decreased carbon content likely result in better three-dimensional network connectivity and therefore improved mechanical properties.

[0006] While low-k films deposited using a combination of low-k precursors and hardeners containing silicon-carbon bonds have improved mechanical properties, this strategy reduces the carbon content of the film and results in greater plasma or process-induced damage (PID). Plasma or process-induced damage in low-k films is caused by the removal of carbon during plasma exposure, especially during etching and photoresist removal processes (e.g., NH3-based removal processes). Carbon depletion causes the plasma-damaged region to change from hydrophobic to hydrophilic. Exposure of the hydrophilic plasma-damaged region to a dilute HF-based wet chemical post-plasma treatment results in rapid dissolution of this damaged region and an increase in the k of the film (the hydrophobic damage layer increases moisture renewal). In patterned low-k films (produced using etching and photoresist removal processes), exposure to a dilute HF-based post-plasma treatment causes profile erosion. Profile erosion can result in the formation of recessed features (leading to metallization defects) and reduced spacing between metal lines (leading to increased capacitance). This is especially problematic in advanced logic devices, where the depth of profile erosion can be a significant percentage of the logic 1 / 2 pitch. Typically, the greater the carbon content of the low-k film, the smaller the depth of PID. Process-induced damage and the resulting profile erosion in low-k films are significant issues that device manufacturers must overcome when incorporating low-k materials into ULSI interconnects, especially at the lowest levels of back-end wiring. It is therefore desirable to deposit low-k films with both the highest possible mechanical strength and the greatest resistance to PID. Unfortunately, those two factors often work against each other, and while films with the highest carbon content exhibit greater resistance to PID, higher carbon content usually results in the incorporation of more terminal silicon-methyl groups (Si-Me or Si(CH3)x) in the oxide network, reducing the mechanical strength of the film (Figure 1).

[0007] Molecular dynamics (MD) simulations show that the type of carbon incorporated into a low-k film (i.e., SiOCH matrix) can significantly affect its mechanical properties. In particular, MD simulations show that low-k films with carbon incorporated as bridging methylene groups (-SiCH2Si-) have higher elastic modulus than low-k films with carbon incorporated as terminal methyl groups (-SiCH3). Bridging carbon atoms maintain the three-dimensional network connectivity, while terminal carbon atoms destroy the three-dimensional network connectivity. The destruction of the three-dimensional network connectivity results in reduced mechanical properties of the low-k film. U.S. Pat. No. 7,892,648 teaches that one way to incorporate bridging carbon groups, such as -SiCH2Si- or -SiCH2CH2Si-, into a low-k film is to deposit the low-k film by a plasma-enhanced chemical vapor deposition (PECVD) process using carbosilane precursors with -SiCH2Si- or -SiCH2CH2Si- functional groups. Alternatively, crosslinkable carbosilane precursors can be added to current low-k PECVD processes. However, there are three significant limitations associated with this approach. The first limitation is that carbosilane precursors are expensive. The second limitation is that crosslinked carbosilane precursors usually have high boiling points due to increased molecular weights since they have two silicon groups. The elevated boiling point can adversely affect the manufacturing process by making it difficult to deliver the chemical precursor into the reaction chamber as a gas-phase reagent without it collapsing in the vapor delivery line or process pump exhaust. The third limitation is that adding an expensive crosslinked carbosilane precursor to a current deposition process increases the complexity of the deposition process. For example, three supply lines would be required in a PECVD tool to increase the density of -SiCH2Si- or -SiCH2CH2Si- groups in a porous low-k film using this approach: one liquid supply line would be required for the structure former, one liquid supply line would be required for the porogen, and one liquid supply line would be required for the added carbosilane.As noted above, many carbosilanes are also high molecular weight compounds that have low vapor pressure and, depending on the end groups, are extremely flammable.

[0008] US 2011 / 10113184 discloses a class of low-k precursors that can be used to deposit insulating films by PECVD with an increased density of -SiCH2Si- groups and a dielectric constant in the range of ∼k=2.4 to k=2.8. In US 2011 / 10113184, low-k films are deposited using Si-based precursors in which at least one branched hydrocarbon group R (e.g., isobutyl, isopentyl, neopentyl, or neohexyl group) is bonded to the silicon atom of the low-k precursor via a methylene group (SiCH2R). The inventors claim that during the deposition process, a high density of SiCH2Si groups is formed in the film by plasma dissociation of the bonds connecting the branched hydrocarbon group R to the methylene group in SiCH2R. This approach has three significant limitations. The first limitation is that the incorporation of large branched alkyl groups into the precursor is expensive. A second limitation is that the incorporation of one or more large branched alkyl groups into a precursor usually results in a precursor with a very high boiling point due to the increased molecular weight due to the large branched alkyl groups. The increased boiling point can adversely affect the manufacturing process by making it difficult to deliver the chemical precursor as a gas phase reagent into the reaction chamber without it condensing in the vapor delivery line or the exhaust of the process pump. A third limitation is that the high density of SiCH2Si groups in the low-k films reported in US Patent Application Publication No. 2011 / 10113184 appears to form after the as-deposited films are UV annealed. Thus, the formation of SiCH2Si groups in the low-k films described in this patent application appears to be due to the UV cure (i.e., post-treatment after the deposition process) rather than the choice of precursor. It is understood that the increase in the density of SiCH2Si groups upon exposure of low-k films to ultraviolet radiation is well documented. A fourth limitation is that most of the dielectric constant values ​​reported in this work are low, below 2.8. It is well established that the lowest dielectric constant achievable in a dense low-k film with suitable mechanical properties is about 2.7-2.8.Thus, the approach disclosed in U.S. Patent Application Publication No. 2011 / 10113184 is not directed to the deposition of dense low-k films without post-deposition processing (i.e., UV annealing), but is more similar to the constrained porogen approach to produce porous low-k films.

[0009] Low-k films with inherent electrical properties, such as lower leakage current density and higher electric breakdown field, are preferred for the fabrication of advanced integrated circuits, with minimum inherent electrical requirements typically being 1×10 at an electric field strength of 1 MV / cm. -9 A / cm 2These include leakage current densities of less than 1000 kV and breakdown fields of 4MV / cm or greater. Since the breakdown fields of device structures decrease with decreasing dimensions (i.e., as device scale shrinks according to Moore's Law), low-k materials with the highest possible breakdown fields are preferred (>4MV / cm). This is particularly important at the lowest levels of the BEOL, where small dimensions can result in high field strengths. It has also been reported that low leakage current levels ensure good reliability in integrated circuits. Since small dimensions at the lowest levels of the BEOL can result in high field strengths, it is particularly important that low-k films exhibit the lowest possible leakage currents at higher field strengths (≧4MV / cm). Unfortunately, the deposition of low-k films with inherently low leakage current densities is accompanied by many challenges. For example, it has been reported that the use of a single structure-forming precursor results in high leakage current densities, possibly due to defects related to oxygen vacancies. Furthermore, low leakage current densities are also dependent on post-deposition processing, such as UV annealing. For example, it has been reported that as-deposited low-k films always have a higher leakage current density than the same films after UV annealing. This is a significant limitation because UV annealing increases equipment cost, process complexity, and reduces throughput. Thus, there is a demand for as-deposited low-k films deposited from a single composition-forming precursor that have better intrinsic electrical properties, especially the lowest possible leakage current density, and the highest possible dielectric breakdown field (≧4MV / cm), especially at high electric field strengths (>2MV / cm). Summary of the Invention [Problem to be solved by the invention]

[0010] Therefore, especially at the lowest level of back-end interconnect processing, for a given value of dielectric constant (k≦3.5), high mechanical strength, strong resistance to plasma-induced losses, and a dielectric constant of 1×10 at high electric field strengths (≧4 MV / cm) are required. -9 A / cm 2There is a need for volatile, structure-forming low-k precursors that can be used to deposit dense low-k films with leakage current densities less than 1000 nm and high breakdown voltages (>5 MV / cm). The precursors need to have high vapor pressure (low molecular weight) to facilitate delivery into the reaction chamber as gas-phase reagents without condensing in the delivery lines or process pump exhaust. Furthermore, films deposited from such precursors do not require post-deposition treatments, such as UV curing, to improve the mechanical strength of the film or the electrical properties of the film. That is, the inherent properties of the as-deposited film must meet the requirements of integrated circuit manufacturing such that no post-deposition steps (i.e., UV curing) are required. [Means for solving the problem]

[0011] The methods and compositions described herein satisfy one or more of the above requirements. The methods and compositions described herein use hydrido-dimethyl-alkoxysilane compounds, such as dimethyl-sec-butoxysilane (DMSBOS), as structure-forming agents to deposit dense low-k dielectric films that, after removal from the deposition chamber, have mechanical properties equal to or higher than those of films deposited from prior art structure-forming agents, such as DEMS®, at the same value of dielectric constant. Furthermore, these films deposited using the hydrido-dimethyl-alkoxysilane precursors described herein as structure-forming agent precursors contain relatively high amounts of carbon incorporated as disilylmethylene groups, as measured by infrared spectroscopy (relative SiCH2Si density >10, as measured by infrared spectroscopy). Furthermore, the total carbon content of films deposited using the hydrido-dimethyl-alkoxysilane precursors is relatively low (<about 25 atomic %), as measured by XPS. Thus, the percentage of total carbon that constitutes disilylmethylene groups in films deposited using the hydrido-dimethyl-alkoxysilane precursor is high (>0.65, calculated as the ratio of the relative SiCH2Si density measured by infrared spectroscopy to the XPS carbon content of the film) compared to other prior art structure-former precursors, such as DEMS® and 1-methyl-1-isopropoxy-1-silacyclopentane (MIPSCP). Furthermore, the hydrido-dimethyl-alkoxysilane precursors described herein have a lower molecular weight relative to other prior art structure former precursors, such as crosslinking precursors (e.g., carbosilanes such as 1,1,4,4-tetraethoxy-1,4-disilabutane or disiloxanes such as hexaethoxy-disiloxane), which inherently have two silicon groups and have higher molecular weights (MW) and higher boiling points, thereby making the hydrido-dimethyl-alkoxysilane precursors described herein more process-friendly, such as in high volume manufacturing processes.

[0012] Described here is the formula Si v O wC x H y where v+w+x+y=100%, v is 10-35 atomic %, w is 10-65 atomic %, x is 5-45 atomic %, and y is 10-50 atomic %, and where the film has a dielectric constant of about 2.70 to about 3.5. In certain embodiments, the film exhibits reduced carbon removal depth as measured by examining carbon content as measured by dynamic SIMS depth profile when exposed to, for example, O2 or NH3 plasma. Additionally, in certain embodiments, the film exhibits reduced carbon removal depth as measured by Hg probe at a field strength of ≧1×10 -9 A / cm 2 The films have a leakage current density of less than 1000 nm and a breakdown field of ≥ 5 MV / cm. Desirable film properties are observed in the as-deposited films from the hydrido-dimethyl-alkoxysilane precursors, without the need for post-deposition processing steps, such as UV curing.

[0013] In one embodiment, a composition for vapor deposition of dense dielectric films is provided that includes a hydrido-methyl-alkoxysilane compound having a formula given in Formula 1. (1) H(Me)2SiOR In the formula, R is a branched or cyclic C3-C 10 and alkyl, such as isopropyl, sec-butyl, isobutyl, tert-butyl, 2-pentyl, 3-pentyl, 3-methyl-2-pentyl, tert-pentyl, cyclopentyl, or cyclohexyl, and the compound is substantially free of one or more impurities selected from the group consisting of halide compounds, water, metals, oxygen-containing impurities, nitrogen-containing impurities, and combinations thereof.

[0014] In a further aspect, there is provided a chemical vapor deposition method for producing a dense dielectric film, comprising the steps of: Providing a substrate in a reaction chamber; introducing a gaseous reagent into the reaction chamber, the gaseous reagent comprising a structure-forming precursor comprising a hydrido-dimethyl-alkoxysilane having a structure given by formula (1); (1) H(Me)2SiOR In the formula, R is a branched or cyclic C 10 R is an alkyl group such as isopropyl, sec-butyl, isobutyl, tert-butyl, 2-pentyl, 3-pentyl, 3-methyl-2-pentyl, tert-pentyl, cyclopentyl, or cyclohexyl, preferably the alkyl groups are selected such that the boiling points of the molecules are below 200° C., preferably below 150° C., and R is also an alkyl group such that the R group is an SiO—R bond (e.g., [ka] wherein R can be selected to form a secondary or tertiary radical upon homolytic bond cleavage of a secondary or tertiary radical, such as an isopropyl radical, a sec-butyl radical, a tert-butyl radical, a sec-pentyl radical, a tert-pentyl radical, a cyclopentyl radical, or a cyclohexyl radical; and applying energy to a gaseous composition comprising a hydrido-dimethyl-alkoxysilane in a reaction chamber to induce a reaction of the gaseous composition comprising the hydrido-dimethyl-alkoxysilane to deposit an organosilicon film on the substrate, wherein the dense organosilica film deposited has a dielectric constant of about 2.70 to about 3.50. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 shows the expected relationship between dielectric constant and hardness as the C / Si ratio of the material increases, assuming that all parameters of the material are normalized to those of SiO2 and that all C is incorporated in the material as methyl groups bonded to silicon.

[0016] [Diagram 2]2 shows the IR spectra between 3500 cm-1 and 500 cm-1 for Comparative Example 1, Inventive Example 2, Inventive Example 4, and Inventive Example 5. The absorbance was normalized to the film thickness, the background was corrected for a bare Si wafer, and the baseline was offset for clarity.

[0017] [Diagram 3] 3 shows the IR spectra between 1390 cm-1 and 1330 cm-1 for Comparative Example 1 and Inventive Example 2, Inventive Example 4, and Inventive Example 5. The absorbance was normalized to the film thickness, the background was corrected for a bare Si wafer, and the baseline was offset for clarity.

[0018] [Figure 4] 4 shows the IR spectra between 1300 cm-1 and 1240 cm-1 for Comparative Example 1 and Inventive Example 2, Inventive Example 4, and Inventive Example 5. The absorbance was normalized to the film thickness, the background was corrected for a bare Si wafer, and the baseline was offset for clarity.

[0019] [Diagram 5] FIG. 5 shows the relationship between dielectric constant and XPS carbon content for a series of low dielectric films deposited using the inventive compound DMTBOS versus a series of low dielectric films deposited using the comparative compound DEMS®.

[0020] [Figure 6] FIG. 6 shows the relationship between dielectric constant and relative SiCH2Si density as measured by infrared spectroscopy for a series of low-k dielectric films deposited using the inventive compound DMTBOS, versus a series of low-k dielectric films deposited using the comparative compound DEMS®.

[0021] [Figure 7]FIG. 7 shows the relationship between dielectric constant and hardness for a series of low dielectric films deposited using the inventive compound DMTBOS versus a series of low dielectric films deposited using the comparative compound DEMS®.

[0022] [Figure 8] FIG. 8 shows the measured current density as a function of applied electric field strength for Comparative Example 3 and Inventive Example 6.

[0023] [Figure 9] FIG. 9 shows the measured current density as a function of applied electric field strength for Inventive Example 1, Inventive Example 7 and Inventive Example 8.

[0024] [Figure 10] FIG. 10 shows the carbon removal durability of Comparative Membrane 1, Comparative Membrane 2, Inventive Membrane 1, and Inventive Membrane 5 after the membranes were damaged using NH3 plasma.

[0025] [Figure 11] FIG. 11 shows the measured current density as a function of applied electric field strength for both the as-deposited and UV-annealed films for Comparative Example 4.

[0026] [Figure 12] FIG. 12 shows the measured current density as a function of applied electric field strength for both the as-deposited and UV-annealed films for inventive Example 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Described herein is a chemical vapor deposition method for the production of dense organosilica films, the method comprising the steps of: Providing a substrate in a reaction chamber; Introducing into a reaction chamber a gaseous composition comprising at least one hydrido-dimethyl-alkoxysilane compound, such as dimethyl-sec-butoxysilane (DMSBOS), and a gaseous oxidant, such as O2 or N2O, and an inert gas, such as He; and applying energy to a gaseous composition comprising hydrido-dimethyl-alkoxysilane in a reaction chamber to induce reaction of the gaseous reactants to deposit an organosilica film on a substrate, wherein the organosilica film has a dielectric constant of about 2.70 to about 3.50. It is also understood that organosilica films having desirable film properties can be deposited using gaseous compositions that do not contain an oxidizer.

[0028] The hydrido-dimethyl-alkoxysilane compounds described herein offer unique properties that allow for the deposition of dense, as-deposited OSG films with relatively low dielectric constants and surprisingly low leakage current densities at high electric field strengths (4 MV / cm) compared to films made using other prior art structure former precursors, such as diethoxymethylsilane (DEMS®). Surprisingly, the dielectric breakdown field (E BD ) is also significantly greater compared to as-deposited films made with other prior art structure-forming agent precursors, such as DEMS®.

[0029] A further unique property of the as-deposited films from hydrido-dimethyl-alkoxysilane structure former precursors is that they have a relatively low total carbon content (typically less than 25 atomic percent by XPS) and yet exhibit exceptionally high resistance to carbon removal when exposed to NH3 or O2 plasma. It is well established that resistance to carbon removal from dielectric films improves as the total carbon content of the film increases. That is, films with high total carbon content exhibit a smaller carbon removal depth when exposed to NH3 or O2 plasma than films with lower total carbon content. This is shown in U.S. Pat. No. 9,922,818, where the carbon removal depth of a low-k film containing 36% carbon (XPS, atomic %) is 20% less than a low-k film containing 23% carbon (XPS, atomic %) (35 nm compared to 44 nm). It is therefore unexpected that dielectric films made using hydrido-dimethyl-alkoxysilane structure former precursors containing relatively low total carbon content (< about 25%, as measured by XPS) can exhibit the same depth of carbon removal when exposed to NH3 or O2 plasma as dielectric films made using precursors designed to deposit films with high total carbon content (> about 25%, as measured by XPS). As disclosed in U.S. Patent No. 9,922,818, precursors such as 1-methyl-1-isopropoxy-1-silacyclopentane (MIPSCP) can be used to produce films with high total carbon content (> about 25%) and exceptional resistance to carbon removal when exposed to NH3 or O2 plasma.

[0030] The unique properties of the hydrido-dimethyl-alkoxysilane compounds of formula (1) also allow dense OSG films to achieve relatively low dielectric constants and to exhibit mechanical properties comparable to or greater than those of films deposited from prior art structurant precursors designed for high mechanical strength, such as DEMS®. For example, DEMS® provides a mixed ligand system with two alkoxy groups, one methyl, and one hydride, which provides a balance of reactive sites and allows for the formation of more mechanically robust films while maintaining a desired dielectric constant. It is also understood that for dense low dielectric films, as the number of silicon-alkoxy groups (e.g., Si-OCH3, Si-OCH2CH3, etc.) in the low-k precursor increases and as the number of silicon-carbon groups (e.g., Si-CH3, Si-CH2CH3, etc.) in the precursor decreases, the dielectric constant and mechanical properties of the as-deposited film improve and the carbon content of the film decreases. Therefore, it is expected that a film made with a precursor containing two silicon-alkoxy groups and one silicon-carbon bond per silicon atom in the precursor, such as the structure former of the prior art designed for high mechanical strength of DEMS®, will have a higher mechanical strength and a lower carbon content than a film made with a precursor containing only one silicon-alkoxy group and two silicon-carbon bonds per silicon, such as the hydrido-dimethyl-alkoxysilane compound of formula (1). Surprisingly, the film made with the hydrido-dimethyl-alkoxysilane compound of formula (1) has similar or greater mechanical properties at the same value of the dielectric constant than a film made with the DEMS® structure former. Also, other than that, the film made with the hydrido-dimethyl-alkoxysilane compound of formula (1) has a similar total carbon content, measured by XPS, to the film made with the DEMS® structure former at the same value of the dielectric constant. Preferred examples of the hydrido-dimethyl-alkoxysilane compound represented by general formula (1) include, but are not limited to, the following hydrido-dimethyl-alkoxysilane compounds having the corresponding structures: [ka]

[0031] The hydrido-dimethyl-alkoxysilane compounds described herein provide unique properties that allow for the incorporation of different distributions of carbon types in dielectric films compared to prior art structure former precursors, such as diethoxymethylsilane (DEMS®) and MIPSCP. For example, in dense OSG films deposited using DEMS® as the structure former, the carbon in the film is present primarily in the form of terminal Si-Me groups, with a small density of disilylmethane groups (SiCH2Si) also present in the film. While the hydrido-dimethyl-alkoxysilane precursors described herein, such as dimethyl-sec-butoxysilane (DMSBOS), can be used to deposit dense OSG films with nearly the same total carbon content as DEMS®-based films at a given dielectric constant value, the distribution of carbon in films made using the hydrido-dimethyl-alkoxysilane precursors is different. Films made using hydrido-dimethyl-alkoxysilane precursors have a lower concentration of terminal Si-Me groups (Si(CH3)) and a much higher concentration of bridging SiCH2Si groups. That is, a much larger percentage of the total carbon in films deposited from the hydrido-dimethyl-alkoxysilane precursors of the present invention is incorporated as bridging SiCH2Si groups compared to the prior art structure former precursors, e.g., DEMS®, since the total carbon content of films made using the prior art structure former DEMS® is nearly the same as films made using the present invention's hydrido-dimethyl-alkoxysilane precursors.

[0032] Prior art silicon-containing structure-forming precursors, such as DEMS®, once energized in a reaction chamber, polymerize to form structures with -O- bonds (e.g., -Si-O-Si or Si-OC-) in the polymer backbone, whereas hydrido-dimethyl-alkoxysilane compounds, such as DMTBOS molecules, polymerize in such a way that some of the -O- bonds in the backbone are replaced with -CH2-methylene bonds. In films deposited using DEMS® as structure-forming precursor, where carbon is present mainly in the form of terminal Si-Me groups, there is a relationship between %Si-Me and mechanical strength, e.g., see the predicted relationship between hardness as the C / Si ratio of the material increases, assuming that all C is incorporated into the material as methyl groups bonded to silicon, in this case the replacement of the bridging Si-O-Si groups with two terminal Si-Me groups reduces the mechanical properties because the network structure is disrupted. Without being bound by theory, it is believed that in the case of hydrido-dimethyl-alkoxysilane compounds, the precursor structure promotes a reaction in the plasma that converts a high percentage of the two terminal Si-Me groups (Si(CH3)) in the structure-forming agent back into bridging methylene groups (disilylmethylene, SiCH2Si) in the structure. In this way, carbon in the form of bridging groups can be incorporated, so that from the standpoint of mechanical strength, the network structure is not disrupted by the increase in carbon content in the film. This also adds carbon to the film, making it more tolerant to carbon depletion from processes such as etching the film, plasma ashing of photoresist, and NH3 plasma treatment of copper surfaces. Another unique property of films made with hydrido-dimethyl-alkoxysilane compounds of formula (1), such as DMSBOS, is that the total carbon content is rather low (<25%), and the percentage of the total carbon content that is composed of SiCH2Si groups is high compared to prior art structure-forming agents, such as DEMS® and MIPSCP.

[0033] Other prior art structure former precursors, such as 1-methyl-1-isopropoxy-1-silacyclopentane (MIPSCP), can deposit dense OSG films with a high concentration of disilamethylene groups (SiCH2Si). However, dense OSG films deposited from MIPSCP, including those with a high concentration of disilamethylene groups (SiCH2Si), also have a high total carbon content, resulting in a smaller percentage of the total carbon incorporated as disilylmethylene groups, as compared to dense OSG films deposited from the hydrido-dimethyl-alkoxysilane precursors described herein, such as dimethyl-sec-butoxysilane (DMSBOS). Furthermore, dense OSG films deposited from MIPSCP also have a high concentration of terminal Si-Me groups (Si(CH3) x As shown in Figure 1, a high concentration of terminal Si-Me groups adversely affects the mechanical strength of the film, ultimately limiting the maximum mechanical strength that can be obtained using MIPSCP as a structure-forming agent.

[0034] The hydrido-dimethyl-alkoxysilanes provide unique properties that allow dense organosilica films to have relatively low dielectric constants and surprisingly exhibit superior mechanical properties compared to prior art structure former precursors such as diethoxymethylsilane (DEMS) and 1-ethoxy-1-methylsilacyclopentane (MESCP). Without being bound by theory, it is believed that the hydrido-dimethyl-alkoxysilanes of the present invention are characterized by the fact that R is a branched or cyclic C3-C 10It is believed that alkyl, when selected from the group consisting of isopropyl, sec-butyl, isobutyl, tert-butyl, sec-pentyl, tert-pentyl, cyclopentyl, or cyclohexyl, can provide stable radicals, such as (CH3)2CH, (CH3)(CH3CH2)HC, (CH3)3C, sec-pentyl, tert-pentyl, cyclopentyl, and cyclohexyl (depending on the alkoxy groups in the hydrido-dimethyl-alkoxysilane), during plasma enhanced chemical vapor deposition. The higher density of stable radicals, such as (CH3)2CH, (CH3)(CH3CH2)HC, (CH3)3C, sec-pentyl, tert-pentyl, cyclopentyl, and cyclohexyl, in the plasma increases the probability of abstraction of a hydrogen atom (forming SiCH2) from one of the terminal silicon methyl groups (Si-(CH3)2) in the precursor and promotes the formation of crosslinkable Si-CH2-Si groups in the as-deposited film. Presumably, in the case of HMe2SiOR, the presence of two terminal silicon methyl groups in the precursor promotes the formation of a high density of disilylmethylene groups (Si-CH2-Si) in the as-deposited film relative to precursors containing only one terminal methyl group per silicon atom. Presumably, in the case of HMe2SiOR, the presence of Si-H bonds promotes easy access to two terminal methyl groups per silicon in the precursor and promotes the formation of a high density of disilylmethylene groups (Si-CH2-Si) in the as-deposited film relative to precursors containing ligands larger than H atoms.

[0035] Some advantages of films made with hydrido-dimethyl-alkoxysilane compounds of formula (1) over films made with prior art bis-alkoxysilane based silicon precursors include, but are not limited to: Lower leakage current density at high electric field strength High dielectric breakdown field Higher resistance to plasma-induced losses ·Same or higher mechanical properties Higher cross-linked SiCH2Si density A higher percentage of the total carbon content consisting of bridging SiCH2Si groups

[0036] The hydrido-dimethyl-alkoxysilane having formula (1) according to the present invention is preferably substantially free of halide ions. When referring to halide ions (or halides), such as chloride (i.e., chlorine-containing species, such as HCl or silicon compounds having at least one Si-Cl bond) and fluoride, bromide, and iodide, the term "substantially free" means less than 5 ppm (by weight) as measured by ion chromatography (IC), preferably less than 3 ppm as measured by IC, and more preferably less than 1 ppm as measured by IC, and most preferably 0 ppm as measured by IC. Chloride is known to act as a decomposition catalyst for silicon precursor compounds having formula (1). A significant level of chloride in the final product may cause the silicon precursor compounds to decompose. The gradual decomposition of silicon precursor compounds may directly affect the decomposition process of the film, making it difficult for semiconductor manufacturers to meet the film specifications. Furthermore, shelf life or stability is adversely affected by the higher decomposition rate of the silicon precursor compounds, thereby making it difficult to guarantee a shelf life of 1-2 years. The accelerated decomposition of the silicon precursor compounds thus creates safety and performance issues associated with their formation of flammable and / or pyrophoric gaseous by-products. The hydrido-dimethyl-alkoxysilanes having formula 1 are preferably substituted with metal ions, such as Li + , Na + , K + , Mg 2+ , , Ca 2+ , Al 3+ , Fe 2+ , Fe 2+ , Fe 3+ , Ni 2+ , Cr 3+As used herein, the term "substantially free" refers to less than 5 ppm (by weight), preferably less than 3 ppm, and more preferably less than 1 ppm, and most preferably 0.1 ppm, as measured by ICP-MS, with respect to Li, Na, K, Mg, Ca, Al, Fe, Ni, Cr. In some embodiments, the silicon precursor compound having formula 1 is free of metal ions, such as Li + , Na + , K + , Mg 2+ , Ca 2+ , Al 3+ , Fe 2+ , Fe 2+ , Fe 3+ , Ni 2+ , Cr 3+Free of. As used herein, the term "free" refers to less than 1 ppm, preferably less than 0.1 ppm (by weight), and most preferably less than 0.05 ppm (by weight), as measured by ICP-MS, as measured by ICP-MS or other analytical methods for measuring metals, as measured by ICP-MS or other analytical methods for measuring metals. Furthermore, the hydrido-dimethyl-alkoxysilane having formula 1 has a purity of preferably 98% by weight or more, more preferably 99% by weight or more, as measured by GC, when used as a precursor for depositing silicon-containing films. Importantly, the hydrido-dimethyl-alkoxysilane having formula 1 is preferably substantially free of oxygen-containing or nitrogen-containing impurities, which may be derived from either the starting materials used during synthesis or by-products generated during synthesis. Examples include, but are not limited to, tetramethyldisiloxane, tetramethyldisilazane, organic amines such as trimethylamine, triethylamine, tri-n-butylamine, N,N-dimethylaniline, N,N-diethylaniline, pyridine, 4-methylpyridine, 3-methylpyridine, 2-methylpyridine, 2,6-dimethylpyridine, and any other organic amines used to promote the reaction. As used herein, the term "free" of oxygen- or nitrogen-containing impurities means, when referring to tetramethyldisiloxane, tetramethyldisilazane, organic amines such as triethylamine, pyridine, and any other organic amines, 1000 ppm or less as measured by GC, preferably 500 ppm (by weight) as measured by GC, and most preferably 100 ppm or less as measured by GC or other analytical method for ash. Oxygen-containing impurities as defined herein are compounds that have at least one oxygen atom and are derived from either the starting material or from the synthesis of the hydrido-dimethyl-alkoxysilane having formula 1. These oxygen-containing impurities may have boiling points close to those of the hydrido-dimethyl-alkoxysilanes having formula 1 and therefore remain in the product after purification.Similarly, nitrogen-containing impurities, as defined herein, are compounds having at least one nitrogen atom, either originating from the starting materials or from the synthesis of the hydrido-dimethyl-alkoxysilanes. These nitrogen-containing impurities may have boiling points close to those of the hydrido-dimethyl-alkoxysilane compounds having formula 1, and therefore remain in the product after purification.

[0037] Low-k dielectric films are organo-silica glass ("OSG") films or materials. Organosilicates are used in the electronics industry, for example, as low-k materials. The properties of the material depend on the chemical composition and structure of the film. Since the type of organosilicon precursor has a strong effect on the structure and composition of the film, it is beneficial to use a precursor that provides the desired film properties to ensure that the addition of the amount of porosity required to reach the desired dielectric constant does not produce a mechanically unsound film. The methods and compositions described herein provide a method for producing low-k dielectric films with a desirable balance of electrical and mechanical properties, as well as other beneficial film properties, such as a relatively low total carbon content, and with a distribution of carbon types in the film that provides improved integrated plasma damage resistance.

[0038] In some embodiments of the methods and compositions described herein, a layer of silicon-containing dielectric material is deposited on at least a portion of a substrate by a chemical vapor deposition (CVD) process using a reaction chamber. The method thus includes providing a substrate in the reaction chamber. Suitable substrates include, but are not limited to, semiconductor materials such as gallium arsenide ("GaAs"), silicon, and silicon-containing compositions such as crystalline silicon, polysilicon, amorphous silicon, epitaxial silicon, silicon dioxide ("SiO2"), silicon glass, silicon nitride, fused silica, glass, quartz, borosilicate glass, and combinations thereof. Other suitable materials include chromium, molybdenum, and other materials commonly used in semiconductor, integrated circuit, flat panel display, and flexible display applications. The substrate can have additional layers, such as silicon, SiO2, organosilicate glass (OSG), fluorinated silicate glass (FSG), boron carbonitride, silicon carbide, hydrogenated silicon carbide, silicon nitride, hydrogenated silicon nitride, silicon carbonitride, hydrogenated silicon carbonitride, boron nitride, organic-inorganic composites, photoresists, organic polymers, porous organic and inorganic materials and composites, metal oxides, such as aluminum oxide, and germanium oxide. Still further layers can be germanosilicates, aluminosilicates, copper and aluminum, and diffusion barrier materials, such as, but not limited to, TiN, Ti(C)N, TaN, Ta(C)N, Ta, W, or WN.

[0039] The reaction chamber is typically, for example, a thermal CVD or plasma-enhanced CVD reactor or a batch furnace type reactor of various processes. In one embodiment, a liquid delivery system can be used. In a liquid delivery system, the precursors described herein can be delivered in neat liquid form or can be used in a solvent formulation or composition that includes a solvent. Thus, in an embodiment, the precursor formulation can include a solvent component of suitable characteristics as desired and advantageous for a given end use to form a film on a substrate.

[0040] The methods described herein include introducing a gaseous composition comprising hydrido-dimethyl-alkoxysilane into a reaction chamber. In some embodiments, the composition can include additional reactants, such as oxygen-containing species, e.g., O2, O3, and N2O, gaseous or liquid organics, alcohols, CO2, or CO. In one specific embodiment, the reaction mixture introduced into the reaction chamber includes at least one oxidizing agent selected from the group consisting of O2, N2O, NO, NO2, CO2, water, H2O2, and combinations thereof. In other embodiments, the reaction mixture does not include an oxidizing agent.

[0041] The compositions for depositing dielectric films described herein include about 40 to about 100 weight percent hydrido-dimethyl-alkoxysilane.

[0042] In some aspects, the gaseous composition comprising hydrido-dimethyl-alkoxysilane can be used in conjunction with a curing agent to further increase the elastic modulus of the as-deposited film.

[0043] In some embodiments, the gaseous composition comprising the hydrido-dimethyl-alkoxysilane is substantially free or free of halides, such as chloride.

[0044] In addition to the hydrido-dimethyl-alkoxysilanes, additional materials can be introduced into the reaction chamber during and / or after the deposition reaction, such as inert gases (e.g., He, Ar, N2, Kr, Xe, etc.), which can be used as carrier gases for less volatile precursors and / or which can promote hardening of the as-deposited material and potentially provide a more stable final film if desired.

[0045] Any of the reagents used, including the hydrido-dimethyl-alkoxysilanes, can be delivered to the reactor individually from separate sources or as a mixture. These reagents can be delivered to the reaction system by any number of means, preferably using pressurizable stainless steel vessels with appropriate valves and fittings that allow the delivery of liquids to the process reactor. Preferably, the precursors are delivered as gases into the process vacuum chamber, i.e., the liquid must be evaporated before it is delivered into the process chamber.

[0046] The method disclosed herein includes adding energy to a gaseous composition comprising hydrido-dimethyl-alkoxysilane in a reaction chamber to induce reaction of the gaseous composition comprising hydrido-dimethyl-alkoxysilane to deposit an organosilica film on a substrate, where the organosilica film has a dielectric constant in some embodiments of about 2.70 to about 3.50, in other embodiments of 2.70 to 3.30, and in more preferred embodiments of 2.80 to 3.20, an elastic modulus of about 6 to about 36 GPa, and about 10 to about 45 atomic % carbon as measured by XPS. Energy is added to the gaseous reagents to induce the hydrido-dimethyl-alkoxysilane and other reagents, if present, to react and form a film on the substrate. Such energy can be provided by, for example, plasma, pulsed plasma, helicon plasma, high density plasma, inductively coupled plasma, remote plasma, hot filament, and thermal (i.e., non-filament) methods. A secondary radio frequency source can be used to modify the characteristics of the plasma at the substrate surface. Preferably, the film is formed by plasma enhanced chemical vapor deposition ("PECVD").

[0047] The flow rates of each of the gaseous reagents preferably range from 10 to 5000 sccm, more preferably 30 to 3000 sccm, per single 300 mm wafer. The actual flow rates required may depend on the wafer size and chamber configuration, and are in no way limited to 300 mm wafers or single wafer chambers.

[0048] In certain embodiments, the film is deposited at a deposition rate of about 5 to about 400 nanometers (nm) / minute. In other embodiments, the film is deposited at a deposition rate of about 30 to about 200 nanometers (nm) / minute.

[0049] The pressure in the reaction chamber during deposition typically ranges from about 0.01 to about 600 Torr, or from about 1 to 15 Torr.

[0050] The film is preferably deposited to a thickness of 0.001 to 500 microns, however, the thickness can be varied as desired. Blanket films deposited on unpatterned surfaces have excellent uniformity, with thickness variations of less than 3% at 1 standard deviation across the substrate, excluding the relevant edges, where, for example, the outermost 5 mm edges of the substrate are not included in the statistical calculation of uniformity.

[0051] In addition to the OSG products of the invention, the invention includes the process by which the products are made, methods of using the products, and compounds and compositions useful for preparing the products. For example, a process for making integrated circuits on semiconductor devices is disclosed in U.S. Patent No. 6,583,049, which is incorporated herein by reference.

[0052] Dense organosilica films produced by the disclosed methods exhibit excellent resistance to plasma-induced loss, particularly during etching and photoresist removal processes.

[0053] Dense organosilica films produced by the disclosed methods exhibit superior mechanical properties at a given dielectric constant relative to dense organosilica films having the same dielectric constant, but made using precursors that are not monoalkoxysilanes. The resulting organosilica films (as deposited) typically have a dielectric constant in some embodiments from about 2.70 to about 3.50, in other embodiments from about 2.80 to about 3.20, and in still other embodiments from about 2.70 to about 3.10, an elastic modulus of about 6 to about 36 GPa, and about 10 to about 45 atomic % carbon as measured by XPS. In other embodiments, the resulting organosilica film has a dielectric constant of about 2.70 to about 3.50 in some embodiments, about 2.80 to 3.20 in other embodiments, and about 2.80 to about 3.10 in still other embodiments, an elastic modulus of about 6 to about 36 GPa, and a carbon content of about 12 to about 43 atomic % as measured by XPS. In some embodiments, the nitrogen content is 0.1 atomic % or less, preferably 0.1 atomic % or less, and most preferably 0.01 atomic % or less, as measured by XPS or SIMS or RBS or any other analytical means. In some embodiments, it is believed that the incorporation of nitrogen can potentially increase the dielectric properties of the dense organosilica film, and therefore, it is contemplated that the nitrogen content is 0.1 atomic % or less, preferably 0.1 atomic % or less, and most preferably 0.01 atomic % or less, as measured by XPS, SIMS or RBS or any other analytical method. Further, the organosilica film has a relative disilylmethylene density of from about 1 to about 30, or from about 5 to about 30, or from about 10 to about 30, or from about 1 to about 20. It is contemplated that the organosilica film is deposited at a rate of from about 5 nm / min to about 2000 nm / min, or from about 5 nm / min to about 1000 nm / min, or from about 50 nm / min to about 1000 nm / min, or from about 100 nm / min to about 2000 nm / min.

[0054] Additionally, the resulting organosilica film, once deposited, can be subjected to post-treatment processes. Thus, as used herein, the term "post-treatment" refers to treating the film with energy (heat, plasma, photons, electrons, microwaves, etc.) or chemicals to further enhance the material properties.

[0055] The conditions under which post-treatment is carried out can vary widely, for example, post-treatment can be carried out under high pressure or in a vacuum environment.

[0056] UV annealing is the preferred method, which is carried out under the following conditions:

[0057] The environment can be inert (e.g., nitrogen, CO2, noble gases (He, Ar, Ne, Kr, Xe), etc.), oxidizing (e.g., oxygen, air, dilute oxygen environment, oxygen-enriched environment, ozone, nitrous oxide, etc.), or reducing (dilute or enriched water, hydrocarbons (saturated, unsaturated, straight or branched, aromatic), etc.). The pressure is preferably from about 1 Torr to about 1000 Torr. However, a vacuum environment is preferred for the thermal anneal as well as any other post-treatment means. The temperature is preferably 200-500°C, and the ramp rate is 0.1-100°C / min. The total UV anneal time is preferably from 0.01 min to 12 h.

[0058] The present invention will be described in more detail with reference to the following examples, which should not be considered limiting. It is also understood that the precursors described in the present invention can also be used to deposit porous low-k films with similar process advantages over existing porous low-k films (i.e., higher elastic modulus and greater resistance to plasma-induced losses for a given value of dielectric constant). EXAMPLES

[0059] All experiments were performed on a 300 mm AMAT Producer® SE, with films deposited on two wafers simultaneously. The precursor and gas flow rates therefore correspond to the flow rates required to deposit films on two wafers simultaneously. The RF power per wafer listed is accurate because each wafer processing station has its own independent RF power source. The deposition pressures listed are accurate because both processing stations are maintained at the same pressure. After deposition, some films were subjected to a UV anneal. The UV anneal was performed on a 300 mm AMAT Producer® Nanocure™ UV curing module, with the wafers held under helium gas flow at one or more pressures below 10 Torr and at one or more temperatures below 400°C.

[0060] Although illustrated and described above with reference to certain specific embodiments and examples, the present invention is not intended to be limited to the details shown. Rather, various changes can be made in the details within the scope of the claims and their equivalents and without departing from the spirit of the present invention. For example, all ranges broadly described herein are expressly intended to include within their scope all narrower ranges that are within the broader range. It is also understood that the hydrido-dimethyl-alkoxysilanes disclosed in the present invention can be used as structure-forming agents for the deposition of porous low-k films with high mechanical strength, high resistance to plasma-induced damage, leakage current density, and high breakdown voltage at a given dielectric constant value (k<3.5).

[0061] The thickness and refractive index were measured with a Woollam Model M2000 spectroscopic ellipsometer. The dielectric constant was measured with a Hg probe on medium resistivity p-type wafers (range 8-12 ohm-cm). FTIR spectra were measured with a Thermo Fisher Scientific Model iS50 spectrometer equipped with a nitrogen purged Pike Technologies Map300 for handling 12-inch wafers. The FTIR spectra, measured by infrared spectroscopy, were used to calculate the relative density of bridging disilylmethylene groups in the films. The relative density of bridging disilylmethylene groups in the films (i.e., SiCH2Si density), measured by infrared spectroscopy, was found to be approximately 1250 cm -1 ~920cm -1 SiO in the range x Divided by the area of ​​the band, 1360 cm -1 The area of ​​the SiCH2Si infrared band centered around the Si surface was determined as 1E4 times the area of ​​the SiCH2Si infrared band centered around the Si surface. The mechanical properties were measured using a KLA iNano Nano Indenter.

[0062] Compositional data were obtained by X-ray photoelectron spectroscopy (XPS) on either a PHI 5600 (73560, 73808) or a Thermo K-Alpha (73846) and are given in atomic mass percent. The atomic mass percent (%) values ​​reported in the tables do not include hydrogen.

[0063] Blanket low-k films were damaged by exposure to a capacitively coupled ammonia plasma in a TEOS / FSG chamber at an Applied Materials Producer® SE. The process parameters used to damage the blanket low-k films were the same for all blanket low-k films: ammonia flow rate = 900 standard cubic centimeters per minute (sccm), chamber pressure of 6.0 Torr, pedestal temperature of 300°C, RF power of 300 Watts (13.56 MHz), and exposure time of 25 seconds.

[0064] Dynamic SIMS profiles were acquired using a continuous focused beam of low-energy Cs+ ions to remove material from the surface of the low-k films by sputtering. Low-energy Cs+ ions were used to reduce atomic mixing due to collision cascades and maximize depth resolution. The sputtering rate was calibrated by sputtering very close to the film-wafer interface and then measuring the sputtered depth with a stylus profilometer. RBS / HFS data of a dense low-k film similar to the one analyzed was used to quantify the SIMS profile. The parameters used to acquire the dynamic SIMS depth profile were the same for all plasma-damaged low-k films investigated.

[0065] For each of the example precursors listed below, deposition conditions were optimized to yield films with high mechanical strength at the targeted dielectric constant.

[0066] Comparative Example 1: Deposition of dense OSG films from diethoxymethylsilane (DEMS®)

[0067] Dense DEMS®-based films were deposited in a 300 mm process using the following process conditions: DEMS® precursor was delivered to the reaction chamber by direct liquid injection (DLI) at a flow rate of 2500 mg / min, with a He carrier gas flow of 1250 standard cubic centimeters per minute (sccm), 25 sccm O2, 380 mil showerhead / heated pedestal spacing, 350° C. pedestal temperature, and 7.5 Torr chamber pressure, to which a 615 watt 13.56 MHz plasma was applied. Various properties of the films, such as dielectric constant (k), refractive index, elastic modulus and hardness, Si(CH3) by infrared spectroscopy, and Si(CH3) by infrared spectroscopy were measured. x The relative densities of and SiCH2Si, and atomic compositions by XPS (atomic percent carbon, atomic percent oxygen, and atomic percent silicon) were obtained as described above and are given in Tables 1, 2, and 5.

[0068] Comparative Example 2: Deposition of dense OSG films from 1-methyl-1-isopropoxy-1-silacyclopentane (MIPSCP)

[0069] Dense 1-methyl-1-isopropoxy-1-silacyclopentane (MIPSCP) based films were deposited on a 300 mm process using the following process conditions: 1-methyl-1-isopropoxy-1-silacyclopentane precursor was delivered to the reaction chamber by direct liquid injection (DLI) at a flow rate of 850 mg / min with a He carrier gas flow of 750 standard cubic centimeters per minute (sccm), 8 sccm O2, 380 milliinch showerhead / heated pedestal spacing, 390° C. pedestal temperature, 7.5 Torr chamber pressure, to which a 275 watt 13.56 MHz plasma was applied. Various properties of the films, such as dielectric constant (k), refractive index, elastic modulus and hardness, Si(CH3) by infrared spectroscopy, and Si(CH3) by infrared spectroscopy were measured. x The relative densities of and SiCH2Si, and atomic compositions by XPS (atomic percent carbon, atomic percent oxygen, and atomic percent silicon) were obtained as described above and are given in Tables 1 and 5.

[0070] Comparative Example 3: Deposition of Dense OSG Films from DEMS®

[0071] Dense DEMS®-based films were deposited on a 300 mm process using the following process conditions: DEMS® precursor was delivered to the reaction chamber by direct liquid injection (DLI) at a flow rate of 2000 mg / min, with a He carrier gas flow of 1500 standard cubic centimeters per minute (sccm), 25 sccm O2, 380 mil showerhead / heated pedestal spacing, 400° C. pedestal temperature, and 7.5 Torr chamber pressure, to which a 217 watt 13.56 MHz plasma was applied. Various properties of the films, such as dielectric constant (k), refractive index, elastic modulus and hardness, Si(CH3) by infrared spectroscopy, were measured. x The relative densities of and SiCH2Si, and atomic compositions by XPS (atomic percent carbon, atomic percent oxygen, and atomic percent silicon) were obtained as described above and are given in Table 3.

[0072] Comparative Example 4: Deposition of Dense OSG Films from DEMS®

[0073] Dense DEMS®-based films were deposited in a 300 mm process using the following process conditions: DEMS® precursor was delivered to the reaction chamber by direct liquid injection (DLI) at a flow rate of 875 mg / min, with a He carrier gas flow of 750 standard cubic centimeters per minute (sccm), 90 sccm O2, 380 mil showerhead / heated pedestal spacing, 345° C. pedestal temperature, 10 Torr chamber pressure, where a 400 watt 13.56 MHz plasma was applied. In some cases, the resulting films were then UV annealed. Various properties of the as-deposited and then UV annealed films, such as dielectric constant (k), refractive index, elastic modulus and hardness, Si(CH3) by infrared spectroscopy, and Si(CH3) by infrared spectroscopy were analyzed. x The relative densities of and SiCH2Si, and atomic compositions by XPS (atomic percent carbon, atomic percent oxygen, and atomic percent silicon) were obtained as described above and are given in Table 6.

[0074] Example 1: Deposition of dense OSG films from dimethyl-sec-butoxysilane (DMSBOS)

[0075] Dense dimethyl-sec-butoxysilane based films were deposited on a 300 mm process using the following process conditions: Dimethyl-sec-butoxysilane precursor was delivered to the reaction chamber by direct liquid injection (DLI) at a flow rate of 1289 mg / min with a He carrier gas flow of 975 standard cubic centimeters per minute (sccm), O2 = 53 sccm, 380 mil showerhead / heated pedestal spacing, 400°C pedestal temperature, 6.1 Torr chamber pressure, to which a 390 watt 13.56 MHz plasma was applied. Various properties of the films, such as dielectric constant (k), refractive index, elastic modulus and hardness, Si(CH3) by infrared spectroscopy, and Si(CH3) xThe relative densities of and SiCH2Si, and atomic compositions by XPS (atomic percent carbon, atomic percent oxygen, and atomic percent silicon) were obtained as described above and are given in Tables 1, 4, and 5.

[0076] Example 2: Deposition of dense OSG films from dimethyl-isopropoxysilane (DMIPOS)

[0077] Dense dimethyl-isopropoxysilane-based films were deposited on a 300 mm process using the following process conditions: Dimethyl-isopropoxysilane precursor was delivered to the reaction chamber by direct liquid injection (DLI) at a flow rate of 1100 mg / min, with a He carrier gas flow of 750 standard cubic centimeters per minute (sccm), O2 = 40 sccm, 380 mil showerhead / heated pedestal spacing, 400°C pedestal temperature, 6.5 Torr chamber pressure, to which a 400 watt 13.56 MHz plasma was applied. Various properties of the films, such as dielectric constant (k), refractive index, elastic modulus and hardness, Si(CH3) by infrared spectroscopy, x The relative densities of and SiCH2Si, and atomic compositions by XPS (atomic percent carbon, atomic percent oxygen, and atomic percent silicon) were obtained as described above and are given in Tables 1 and 2.

[0078] Example 3: Deposition of dense OSG films from dimethyl-tert-butoxysilane (DMTBOS)

[0079] Dense dimethyl-tert-butoxysilane-based films were deposited on a 300 mm process using the following process conditions: Dimethyl-tert-butoxysilane precursor was delivered to the reaction chamber by direct liquid injection (DLI) at a flow rate of 1500 mg / min, with a He carrier gas flow of 975 standard cubic centimeters per minute (sccm), O2=19 sccm, 380 mil showerhead / heated pedestal spacing, 400°C pedestal temperature, 6.7 Torr chamber pressure, to which a 350 watt 13.56 MHz plasma was applied. Various properties of the films, such as dielectric constant (k), refractive index, elastic modulus and hardness, Si(CH3) by infrared spectroscopy, and Si(CH3) x The relative densities of and SiCH2Si, and atomic compositions by XPS (atomic percent carbon, atomic percent oxygen, and atomic percent silicon) were obtained as described above and are given in Table 1.

[0080] Example 4: Deposition of dense OSG films from dimethyl-sec-butoxysilane (DSBOS)

[0081] Dense dimethyl-sec-butoxysilane-based films were deposited on a 300 mm process using the following process conditions: Dimethyl-sec-butoxysilane precursor was delivered by direct liquid injection (DLI) into the reaction chamber at a flow rate of 1200 mg / min, with a He carrier gas flow of 975 standard cubic centimeters per minute (sccm), O2 = 45 sccm, 380 mil showerhead / heated pedestal spacing, 400°C pedestal temperature, 6.5 Torr chamber pressure, to which a 390 watt 13.56 MHz plasma was applied. In some cases, the resulting films were then UV annealed. Various properties of the as-deposited and UV annealed films, such as dielectric constant (k), refractive index, elastic modulus and hardness, S(CH3) by infrared spectroscopy, were analyzed. x The relative densities of and SiCH2Si, and atomic compositions by XPS (atomic percent carbon, atomic percent oxygen, and atomic percent silicon) were obtained as described above and are given in Tables 2 and 6.

[0082] Example 5: Deposition of dense OSG films from dimethyl-tert-butoxysilane (DMTBOS)

[0083] Dense dimethyl-tert-butoxysilane-based films were deposited on a 300 mm process using the following process conditions: Dimethyl-tert-butoxysilane precursor was delivered to the reaction chamber by direct liquid injection (DLI) at a flow rate of 1300 mg / min, with a He carrier gas flow of 975 standard cubic centimeters per minute (sccm), O2=19 sccm, 380 mil showerhead / heated pedestal spacing, 400°C pedestal temperature, 6.7 Torr chamber pressure, to which a 425 watt 13.56 MHz plasma was applied. Various properties of the films, such as dielectric constant (k), refractive index, elastic modulus and hardness, Si(CH3) by infrared spectroscopy, x The relative densities of and SiCH2Si, and the atomic compositions by XPS (atomic percent of carbon, atomic percent of oxygen, and atomic percent of silicon) were obtained as described above and are given in Table 2.

[0084] Example 6: Deposition of dense OSG films from dimethyl-sec-butoxysilane (DSBOS)

[0085] Dense dimethyl-sec-butoxysilane based films were deposited on a 300 mm process using the following process conditions: Dimethyl-sec-butoxysilane precursor was delivered to the reaction chamber by direct liquid injection (DLI) at a flow rate of 1100 mg / min, with a He carrier gas flow of 850 standard cubic centimeters per minute (sccm), O2=24 sccm, 380 mil showerhead / heated pedestal spacing, 400°C pedestal temperature, 7.0 Torr chamber pressure, to which a 300 watt 13.56 MHz plasma was applied. Various properties of the films, such as dielectric constant (k), refractive index, elastic modulus and hardness, Si(CH3) by infrared spectroscopy, and Si(CH3) by infrared spectroscopy were measured. x The SiCH2Si and SiCH2Si relative densities, and atomic compositions by XPS (atomic percent carbon, atomic percent oxygen, and atomic percent silicon) were obtained as described above and are given in Table 3.

[0086] Example 7: Deposition of dense OSG films from dimethyl-tert-butoxysilane (DMTBOS)

[0087] Dense dimethyl-tert-butoxysilane-based films were deposited on a 300 mm process using the following process conditions: Dimethyl-tert-butoxysilane precursor was delivered to the reaction chamber by direct liquid injection (DLI) at a flow rate of 1300 mg / min, with a He carrier gas flow of 975 standard cubic centimeters per minute (sccm), O2=8 sccm, 380 mil showerhead / heated pedestal spacing, 400°C pedestal temperature, 6.7 Torr chamber pressure, to which a 350 watt 13.56 MHz plasma was applied. Various properties of the films, such as dielectric constant (k), refractive index, elastic modulus and hardness, Si(CH3) by infrared spectroscopy, and Si(CH3) x The relative densities of and SiCH2Si, and atomic compositions by XPS (atomic percent carbon, atomic percent oxygen, and atomic percent silicon) were obtained as described above and are given in Table 4.

[0088] Example 8: Deposition of dense OSG films from dimethyl-iso-propoxysilane (DMIPOS)

[0089] Dense dimethyl-iso-propoxysilane based films were deposited on a 300 mm process using the following process conditions: Dimethyl-iso-propoxysilane precursor was delivered to the reaction chamber by direct liquid injection (DLI) at a flow rate of 1100 mg / min, with a He carrier gas flow of 750 standard cubic centimeters per minute (sccm), O2=40 sccm, 380 mil showerhead / heated pedestal spacing, 400°C pedestal temperature, 6.5 Torr chamber pressure, to which a 400 watt 13.56 MHz plasma was applied. Various properties of the films, such as dielectric constant (k), refractive index, elastic modulus and hardness, Si(CH3) by infrared spectroscopy, xThe relative densities of and SiCH2Si, and atomic compositions by XPS (atomic percent carbon, atomic percent oxygen, and atomic percent silicon) were obtained as described above and are given in Table 4.

[0090] Example 9: Synthesis of dimethyl-sec-butoxysilane and other hydrido-dimethyl-alkoxysilane precursors

[0091] 214 g (2.88 mol) of 2-butanol was added dropwise to 300 g (3.17 mol) of chlorodimethylsilane in 300 mL of pentane at reflux. A nitrogen purge was introduced to purge out the HCl. After the addition was complete, reflux was continued for 1 hour and then the reaction was allowed to cool to room temperature. An organic amine was added to drive the reaction to completion. The resulting reaction slurry was filtered and the solvent was removed by distillation at atmospheric pressure. Vacuum distillation at 98° C. and 760 mm Hg produced 175 g of dimethyl-sec-butoxysilane with a purity of 99.5% as determined by GC. GC also showed some impurities such as tetramethyldisiloxane. The yield was 46%. Dimethyl-iso-propoxysilane, dimethyl-tert-butoxysilane, dimethyl-tert-pentoxysilane, dimethyl-cyclopentoxysilane, and dimethyl-cyclohexoxysilane were prepared by the same method as in Example 9 and characterized by GC-MS. The molecular weight (MW), structure, and corresponding main MS fragment peaks of each component are given below to confirm their identification.

[0092] [Table 1]

[0093] In Figure 1, plots of predicted hardness and dielectric constant are given for non-porous SiO2 films with increasing amounts of added methyl groups. Hardness can be predicted by applying the theory of Boolchand et al. (P. Boolchand, M. Zhang, B. Goodman, Phys. Rev. B, 53 11488, 1996) to methyl groups instead of atoms and examining the effect of terminal methyl groups on mechanical properties. Dielectric constant can be predicted by the group contribution method, which predicts dielectric constant for polymers and for three-dimensionally connected amorphous materials. Hardness (assumed to be proportional to modulus) and dielectric constant are normalized to that of hydroxyl-free silica, which has a dielectric constant of 3.8 and a modulus of 72 GPa. Using those values, Figure 1 shows that there is a 19% decrease in dielectric constant and a corresponding 66% decrease in hardness when the C / Si ratio in the film increases from 0 to about 0.6. However, further increase of the C / Si ratio to 1 results in only an additional 4% decrease in dielectric constant while the hardness approaches 0. It is therefore desirable to have a means to limit the percentage of Si atoms substituted with terminal methyl groups since this may maximize mechanical properties at a given dielectric constant. It is even more desirable to have a means to add carbon to the film in the form of SiCH2Si bridging groups. Incorporating carbon in the form of bridging groups is desirable because, from a mechanical strength standpoint, the network structure is not broken by the increase in carbon content and the terminal Si(CH3) x This is because a higher mechanical strength can be obtained for the same amount of carbon incorporation in the film in the form of SiCH2Si bridging groups. The addition of carbon to the film in the form of SiCH2Si bridging groups also allows the film to be more resilient to carbon depletion of the OSG film from processes such as etching the film, plasma ashing of photoresist, and NH3 plasma treatment of copper surfaces. Carbon depletion in the OSG film can result in an increase in the effective dielectric constant of the film, etching of the film and feature bowing problems during wet cleaning steps, and / or integration problems when depositing copper diffusion barriers.

[0094] Table 1 shows that films made using the hydrido-dimethyl-alkoxysilane precursors described in this invention, DMSBOS, DMIPOS, and DMTBOS as structurers have comparable or greater mechanical strength at similar dielectric constants than films made using DEMS structurers or MIPSCP structurers. For example, the elastic modulus of the DMSBOS-based films of this invention is 60% greater than that of the comparative DEMS-based films. Furthermore, films made using the hydrido-dimethyl-alkoxysilane precursors have a total carbon content by XPS equivalent to that of films made using the DEMS structurer (~20%C), but significantly less than that of films made using the MIPSCP structurer (~34%). Most importantly, the percentage of total carbon in the films consisting of disilylmethylene groups, defined by the ratio of the relative density of disilylmethylene groups measured by IR spectroscopy to the value of the total carbon content of the film measured by XPS (for example, in the DEMS® system, this ratio is 6 / 18=0.33), is much higher than those made with the DEMS® or MIPSCP structurers, i.e., as shown in Table 1, this ratio is greater than 0.65 for DMSBOS, DMIPOS, and DMTBOS. Table 1 also shows that films deposited with the DMSBOS structurer exhibit unique properties relative to films deposited from two other inventive hydrido-dimethyl-alkoxysilane compounds, DMIPOS and DMTBOS. Films deposited with the DMSBOS structurer have significantly higher mechanical properties relative to films deposited from the DMIPOS and DMTBOS structurer precursors. For example, the elastic modulus and hardness of films deposited using DMSBOS structuring agent are 14% and 41% higher, respectively, than those of films deposited using DMIPOS structuring agent. Similarly, the elastic modulus and hardness of films deposited using DMSBOS structuring agent are 19% and 37% higher, respectively, than those of films deposited using DMTBOS structuring agent.

[0095] [Table 2]

[0096] 3500 cm for films made using the hydrido-dimethyl-alkoxysilane precursors described in this invention, DMSBOS, DMIPOS, and DMTBOS as structure-forming agents, and for films made using DEMS structure-forming agent. -1 ~500cm -1 The transmission infrared spectra of the films are shown in Figure 2. All four films have a dielectric constant in the range of 3.0 to 3.1 (Table 2). Figure 3 shows the IR spectra of the films at 1360 cm for all four films. -1 Zoomed-in images of the disilylmethylene (SiCH2Si) infrared band centered near the 1273 cm ... -1 Terminal silicon methyl infrared bands centered near (Si(CH3) x ) for films made with DMSBOS, DMIPOS, and DMTBOS structure-former precursors. x ) infrared band peak absorption is the (Si(CH3) x ) infrared band peak absorbance is in the range of 20% to 24% smaller. Thus, the infrared spectra show that films made with DMSBOS, DMIPOS, and DMTBOS structure-former precursors have a higher concentration of SiCH2Si groups and a smaller concentration of Si(CH3) relative to films made with the DEMS structure-former precursor. x It indicates that the aryl group has a substituent.

[0097] The properties of the inventive and comparative dense OSG films in FIG. 2 are given in Table 2. All four films have a dielectric constant in the range of 3.0-3.1. As shown in Table 2, the relative SiCH2Si density (determined from their infrared spectra) for films made with the inventive DMSBOS, DMIPOS and DMTBOS structure-forming precursors is 167%-250% greater than the relative SiCH2Si density of the film made with the DEMS structure-forming agent. Further insight into the unique carbon distribution in the films made with the DMSBOS, DMIPOS and DMTBOS structure-forming precursors is gained by calculating the relative percentage of the total carbon in those films that consists of disilylmethylene (SiCH2Si) groups. The relative percentage of the total carbon that consists of disilylmethylene (SiCH2Si) groups can be calculated as the ratio of the relative SiCH2Si density (measured by IR spectroscopy) to the total carbon content in the film (measured by XPS). As shown in Table 2, the relative percentage of total carbon consisting of disilylmethylene (SiCH2Si) groups for films made using the DMSBOS, DMIPOS and DMTBOS structure forming precursors of the present invention is 131% to 160% greater than the relative percentage of total carbon consisting of disilylmethylene (SiCH2Si) groups for films deposited using the DMSBOS structure forming agent.

[0098] [Table 3]

[0099] A series of depositions of dense low-k dielectric films were deposited using either DMSBOS or DEMS® as the low-k precursor in a 300 mm PECVD reactor under various process conditions of plasma power from 225 to 550 watts, chamber pressure from 5.5 to 10 Torr, substrate temperature from 345 to 400°C, O2 gas flow from 0 to 60 sccm, He carrier gas flow from 750 to 2250 sccm, precursor liquid flow from 0.750 to 2.500 g / min, and electrode spacing of 0.380 inches. The atomic percent of carbon was measured by XPS as described herein. Figure 5 shows the relationship between XPS carbon content (atomic %) for dense OSG films made with DMSBOS and DEMS® with different dielectric constants. As shown in Figure 5, the film made using the prior art precursor DEMS® has a slightly smaller, but similar XPS carbon content to the film made using the DMSBOS precursor at the same value of dielectric constant while the dielectric constant increases from about 2.9 to about 3.3. For both films, the XPS carbon content falls within a relatively narrow range: ∼19.5 ± 3%.

[0100] A series of depositions of dense low-k dielectric films were deposited using either DMSBOS or DEMS® as the low-k precursor in a 300 mm PECVD reactor under various process conditions of plasma power of 225-550 watts, chamber pressure of 5.5-10 Torr, substrate temperature of 345-400°C, O2 gas flow of 0-60 sccm, He carrier gas flow of 750-2250 sccm, precursor liquid flow of 0.750-2.500 g / min, and electrode spacing of 0.380 inches. The density of the SiCH2Si group was calculated from the infrared spectrum for each film as described herein. Figure 6 shows the relationship between the density of the SiCH2Si group for dense OSG films made using DMSBOS and DEMS® precursors with different dielectric constants. As shown in FIG. 6, the prior art DEMS® low-k film has a much smaller density of SiCH2Si groups at the same value of dielectric constant compared to DMSBOS-based films. This shows one of the important advantages of using hydrido-dimethyl-alkoxysilane compounds of formula (1), such as DMSBOS, to deposit dense low-k dielectric films with the same value of dielectric constant, in that the hydrido-dimethyl-alkoxysilane precursor DMSBOS can be used to deposit films with similar or higher density of SiCH2Si groups than other prior art structure formers. In this way, carbon in the form of bridging groups can be incorporated, so that from the standpoint of mechanical strength, the network structure is not broken by increasing the carbon content in the film. This also shows that Adding carbon to the film allows the film to be more resilient to carbon depletion from processes such as etching the film, plasma ashing of the photoresist, and NH3 plasma treatment of the copper surface. However, one unique property of films made with hydrido-dimethyl-alkoxysilane compounds of formula (1), such as DMSBOS, is that the total carbon content is somewhat smaller (<25%) and the percentage of the total carbon content that consists of SiCH2Si groups is higher compared to prior art structure formers such as DEMS® and MIPSCP.

[0101] A series of depositions of dense low-k dielectric films were deposited using either DMSBOS or DEMS® as the low-k precursor in a 300 mm PECVD reactor under various process conditions of plasma power of 225-550 watts, chamber pressure of 5.5-10 Torr, substrate temperature of 345-400°C, O2 gas flow of 0-60 sccm, He carrier gas flow of 750-2250 sccm, precursor liquid flow of 0.750-2.500 g / min, and electrode spacing of 0.380 inches. The hardness of the films was measured by nanoindentation as described herein. Figure 7 shows the relationship between the hardness of dense OSG films made using DMSBOS and DEMS® precursors with different dielectric constants. As shown in Figure 7, the prior art DEMS® low-k films have a lower hardness at the same value of dielectric constant versus DMSBOS-based films while the dielectric constant increases from about 2.9 to about 3.3. This demonstrates one of the key properties of using hydrido-dimethyl-alkoxysilane compounds of formula (1), such as DMSBOS, over other prior art structure formers for depositing dense low-k dielectric films at the same value of dielectric constant; films deposited using hydrido-dimethyl-alkoxysilane compounds of formula (1), such as DMSBOS, can be used to deposit films with similar or higher hardness, even when using prior art structure formers, such as DEMS® structure former precursors, that are specifically designed to deposit films with high mechanical properties, over other prior art structure former precursors.

[0102] FIG. 8 shows the leakage current density as a function of electric field strength from 1 MV / cm to 7 MV / cm for dense OSG films made with DEMS® structurer and from DMSBOS structurer. The electric field at breakdown is defined as a sudden rise in leakage current density of at least 2X. Thus, the electric field at breakdown for films made with DMSBOS precursor occurs at an electric field strength of 5.3 MV / cm, while the electric field at breakdown for films made with DMSBOS precursor occurs at an electric field strength of 4.6 MV / cm. Since the electric field at breakdown for device structures decreases with decreasing dimensions, low dielectric constant films with the highest possible electric field at breakdown are preferred for integrated circuit fabrication (>4 MV / cm). Higher electric field at breakdown is especially important at the lowest levels of the BEOL, where small dimensions can result in high electric field strengths. FIG. 8 shows that films made using hydrido-dimethyl-alkoxysilane compounds of formula (1), such as DMSBOS, have a higher dielectric breakdown field relative to prior art structure formers, such as DEMS®, and are therefore preferred for integrated circuit fabrication. Low dielectric constant films with low leakage current density provide improved reliability for integrated circuits. Low leakage current density is especially important at high field strengths, ≧4MV / cm, as device dimensions continue to shrink. As shown in FIG. 8, the leakage current density of films made using DMSBOS precursor at a field strength of 4MV / cm is 0.27×10 -9 A / cm 2 and the leakage current density of the film made with the DEMS® precursor was 1.24×10 -9 A / cm 2 ) is 78% lower. This example shows that films made with hydrido-dimethyl-alkoxysilane compounds of formula (1), such as DMSBOS, have lower leakage current density at high electric field strengths (≧4 MV / cm) relative to films made with prior art structure formers, such as DEMS®, and therefore may be preferred for integrated circuit fabrication.

[0103] The properties of the two films shown in FIG. 8 are shown in Table 3. Both films have a dielectric constant of 3.0. The film made with DMSBOS structurer has higher mechanical properties than the film made with DEMS structurer, with its elastic modulus and hardness being 27% and 48% greater, respectively, than the film made with DEMS structurer. The relative disilylmethylene (SiCH2Si) density, measured by IR spectroscopy, of the film made with DMSBOS structurer is 260% greater than the relative disilylmethylene density of the film made with DEMS structurer. The percentage of total carbon incorporated as disilylmethylene groups is 183% greater for the film made with DMSBOS structurer versus the film made with DEMS structurer. Thus, films made using hydrido-dimethyl-alkoxysilane compounds of formula (1), such as DMSBOS, have unique properties that result in a unique combination of favorable film properties: unexpectedly high mechanical properties, unexpectedly high dielectric breakdown field (≧5MV / cm), and unexpectedly low leakage current density at high field strengths (≧4MV / cm) relative to films deposited from prior art low-k structure formers, such as DEMS®. Without being bound by theory, these unique film properties are attributed to the unique distribution of carbon in these films, the relatively low total carbon content (<25%), with a high density of disilylmethylene groups (>10), and with a high percentage of the total carbon content consisting of disilylmethylene groups (>0.65). Such unique films can be deposited using hydrido-dimethyl-alkoxysilane compounds described in formula (1), such as DMSBOS.

[0104] [Table 4]

[0105] In Figure 9, the leakage current density for dense OSG films made with three different inventive hydrido-dimethyl-alkoxysilane compounds, DMIPOS, DMSBOS, and DMTBOS, is shown as a function of electric field strength from 1 MV / cm to 7 MV / cm. All three films have unexpectedly high dielectric breakdown fields of >5 MV / cm. Furthermore, all three films have a dielectric breakdown field of >1x10 at 4 MV / cm. -9 A / cm 2 9 also shows that films deposited using the DMSBOS structuring agent exhibit unique properties relative to films deposited from two other inventive hydrido-dimethyl-alkoxysilane compounds, DMIPOS and DMTBOS. Films deposited using the DMSBOS structuring agent have lower leakage current densities at high electric field strengths (>4MV / cm) relative to films deposited from the DMIPOS and DMTBOS structuring agent precursors.

[0106] The properties of three dense OSG films made using the DMIPOS, DMSBOS, and DMTBOS structurer precursors of the present invention are shown in Table 4. The dielectric constants of all three films are similar, ranging from 3.1 to 3.2. All three films have similar or better mechanical properties at the same values ​​of dielectric constant than films deposited from prior art low-k structurers, such as DEMS®, designed to result in films with high mechanical strength (see, for example, film properties of films deposited using DEMS® structurer in Tables 3 and 7). All three dense OSG films made using the DMIPOS, DMSBOS, and DMTBOS structurer precursors have a higher density of disilylmethylene (SiCH2Si) groups (>10) relative to films deposited using the DEMS® structurer precursor. Furthermore, all three dense OSG films made using DMIPOS, DMSBOS, and DMTBOS structurer precursors all have a higher percentage of their total carbon content (>0.65) consisting of disilylmethylene (SiCH2Si) groups relative to films deposited using the DEMS structurer precursor. Thus, films made using hydrido-dimethyl-alkoxysilane compounds of formula (1), such as DMIPOS, DMSBOS, and DMTBOS, have unique properties that result in unexpectedly high mechanical properties, unexpectedly high electric fields of breakdown (≧5MV / cm), and unexpectedly low leakage current densities at high electric field strengths (≧4MV / cm) relative to films deposited from prior art low-k structurers, such as DEMS. Without being bound by theory, these unique film properties are attributed to the unique carbon distribution in these films, with a high density of disilylmethylene groups (>10), and a high percentage of the total carbon content consisting of disilylmethylene groups (0.65), a relatively low total carbon content (<25%). Furthermore, films deposited using DMSBOS structure formers exhibit unique properties relative to films deposited from two other inventive hydrido-dimethyl-alkoxysilane compounds, DMIPOS and DMTBOS.In particular, films deposited with DMTBOS structurer have lower leakage current density at high electric field strengths (>4MV / cm) relative to films deposited from DMIPOS and DMTBOS structurer precursors.

[0107] [Table 5]

[0108] Figure 10 shows dynamic SIMS profiles of comparative film 1 (deposited with DEMS® structuring agent), comparative film 2 (deposited with MIPSCP structuring agent), inventive film 1 (deposited with DMSBOS structuring agent), and inventive film 5 (deposited with DMTBOS structuring agent) after they were damaged with NH3 plasma. All four films were exposed to NH3 plasma for 25 seconds with a plasma power of 300 W to match the plasma damage conditions seen in the integration. The carbon removal depth (also referred to as plasma-induced damage depth) is indicated by the depth to which carbon was removed from the film as shown by the dynamic SIMS depth profile.

[0109] The properties of the four films in FIG. 10 are shown in Table 5. The dielectric constants of these films range from 3.0 to 3.1. The mechanical strength of the films deposited using the full hydrido-dimethyl-alkoxysilane structurer family, DMSBOS and DMTBOS, is much greater than that of the films deposited using the prior art structurer precursors DEMS® and DIPSCP. The relative SiCH2Si densities measured by IR spectroscopy of the films deposited using DMSBOS, DMTBOS, and MIPSCP structurer precursors are all high (>10), while the relative SiCH2Si density of the film deposited using the DEMS® structurer precursor is low (6). The film deposited using the prior art structurer MIPSCP has both the highest total carbon content (atomic % carbon=34%) and the highest relative SiCH2Si density (19) as determined from its SIMS depth profile. Similarly, the film deposited using the prior art structuring agent DEMS® has the lowest carbon content (atomic % carbon=16%) as determined from its SIMS depth profile, and the lowest relative SiCH2Si density (6). The percentage of total carbon consisting of SiCH2Si groups, as specified in Table 5, is highest for the films deposited using DMSBOS and DMTBOS, and lowest for the films deposited using the prior art structuring agents DEMS® and MIPSCP.

[0110] [Table 6]

[0111] It is well established that the resistance of dielectric films to carbon removal increases as the total carbon content of the film increases. For example, to our knowledge, films deposited using the prior art precursor MIPSCP, or its derivatives, such as 1-methyl-1-ethoxy-1-silacyclopentane, or MIPSCP, have the strongest resistance to carbon removal when exposed to NH3 plasma of any dense low-k film deposited to date (U.S. Pat. No. 9,922,818). This is due to the very high carbon content of those films (typically >30). This is explained in US Patent No. 9,922,818, where the carbon removal depth of a low-k film made using a combination of MIPSCP structure former precursor and cyclooctane containing 36% carbon (XPS, atomic %) after exposure to NH3 plasma is 20% lower (35 nm compared to 44 nm) than a low-k film made using a combination of DEMS structure former precursor and cyclooctane containing 23% carbon (XPS, atomic %). It has also been reported that the resistance of carbon removal from a dielectric film increases as the concentration of bridging SiCH2Si groups in the film increases. Thus, for the four films listed in Table 5, the film deposited using MIPSCP structure former precursor should have the highest resistance to carbon removal when exposed to NH3 plasma, while the film deposited using DEMS structure former precursor should have the lowest resistance to carbon removal when exposed to NH3 plasma.

[0112] For the films made with DMSBOS, DMTBOS, and MIPSCP structure former precursors, the carbon removal depth after exposure to NH3 plasma as determined by SIMS depth profile is about 15 nm, while for the film made with DEMS structure former precursor, the carbon removal depth after exposure to NH3 plasma is much larger, about 24 nm. For the film made with DEMS structure former precursor, the large carbon removal depth is expected since this film has the lowest total carbon content and the lowest SiCH2Si group density. Unexpectedly, the carbon removal depth from the film made with MIPSCP is not the smallest, even though the MIPSCP-based film has the highest carbon content (34 atomic % carbon as determined by its SIMS depth) and the highest density of SiCH2Si groups (relative SiCH2Si density by IR = 19). More surprisingly, the two films made with the hydrido-dimethyl-alkoxysilane compounds described in formula (1), such as DMSBOS and DMTBOS, have a small depth of carbon removal as determined by SIMS depth profiles, similar to the films made with the MIPSCP structurer of the prior art. This is highly unexpected, since the films made with DMSBOS and DMTBOS structurer compounds have both a lower carbon content (41% and 38% lower carbon, respectively) and a lower density of SiCH2Si groups as determined by their SIMS depth profiles, relative to the films made with the MIPSCP structurer. This is another unique property of the films made with the hydrido-dimethyl-alkoxysilane compounds described in formula (1), such as DMSBOS and DMTBOS, that the films made with the hydrido-dimethyl-alkoxysilane compounds described in formula (1) have a much higher resistance to carbon removal when exposed to NH3 plasma than would be expected for films with a relatively low total carbon content (<about 25 atomic %).Without being bound by theory, this unique film property is attributed to the unique distribution of carbon in those films, the relatively low total carbon content (<25%) with a high density of disilylmethylene groups (>10 as measured by IR spectroscopy) and a high percentage of the total carbon content consisting of disilylmethylene groups (>0.65 as determined by a combination of IR spectroscopy and XPS). To explain, the films made with the DMSBOS and DMTBOS structurer precursors in Table 5 both have the highest percentage of the total carbon content consisting of disilylmethylene groups (0.84 and 0.91, respectively) versus films made with the prior art structurers MIPSCP (0.56) and DEMS® (0.33). In fact, the prior art structurer MIPSCP was specifically designed to deposit films with a high percentage of carbon to provide a strong resistance to carbon removal after exposure to NH3 plasma. Although this film contains a high percentage of total carbon (34 atomic % as measured from its SIMS depth profile) and a high density of SiCH2Ci groups as determined by its infrared spectrum, it also contains other forms of carbon, such as a high density of terminal methyl groups. Thus, although a higher carbon content in a low-k dielectric film can confer a high resistance to carbon removal when exposed to NH3 plasma, the type of carbon in the film also plays an important role. In particular, as shown in FIG. 10 and Table 5, films having a relatively low total carbon content (<25%), a high density of disilylmethylene groups (>10 as determined by IR spectroscopy), and a high percentage of the total carbon content consisting of disilylmethylene groups (>0.65 as determined from a combination of IR spectroscopy and XPS) exhibit the same resistance to carbon removal on exposure to NH3 plasma as films having much higher total carbon contents made using prior art structure former precursors, such as MIPSP, which is a structure former precursor specifically designed to impart high resistance to carbon removal when exposed to NH3 plasma.

[0113] The leakage current density of a dense OSG film made with the DEMS® structurer precursor (Comparative Example 4) both before and after UV annealing is shown in Figure 11 as a function of electric field strength from 1 MV / cm to 7 MV / cm. The properties of a dense OSG film made with the DEMS® structurer both before and after UV annealing are shown in Table 6. The as-deposited film has a breakdown field of 3.5 MV / cm and a leakage current density of 259 x 10 at an electric field of 4 MV / cm. -9 A / cm 2 After UV annealing, the film has a dielectric breakdown field of 4.2 MV / cm and a leakage current density of 7.9 × 10 at an electric field of 4 MV / cm. -9 A / cm 2 100%. Thus, in Comparative Example 4, with UV annealing, the breakdown field increases (+20%) and the leakage current density decreases (97% less at a field strength of 4 MV / cm), as shown in FIG. 11. The electrical behavior of the film made with the structure former precursor DEMS® in FIG. 11 is representative of the film made with the structure former of the prior art. It has been reported that the film made with a single structure former precursor results in a high leakage current density. Furthermore, the low leakage current density depends on the post-deposition treatment, e.g., UV annealing. To explain, it has been reported that the as-deposited low-k film always has a higher leakage current density than the same film after UV annealing. This is a significant limitation of dense OSG films deposited from a single structure former precursor, since UV annealing increases equipment cost, process complexity, reduces throughput, and reduces the film's resistance to plasma-induced losses.

[0114] [Table 7]

[0115] FIG. 12 shows the leakage current density of a dense OSG film made with the DMSBOS structurer precursor of the present invention (Inventive Example 4) both before and after UV annealing as a function of electric field strength from 1 MV / cm to 7 MV / cm. The properties of the dense OSG film made with the DMSBOS structurer precursor both before and after UV annealing are shown in Table 6. Both the as-deposited and UV annealed films have a dielectric breakdown field of 5.1 MV / cm. That is, the UV anneal has no effect on the dielectric breakdown field. Also, there is a very small difference in leakage current density between the as-deposited and UV annealed films. For example, at a field strength of 4 MV / cm, the leakage current density of the as-deposited film is 0.39×10 -9 A / cm 2 and after UV annealing, the leakage current density of the film is 0.57×10 -9 A / cm 2 Although there is a small increase in leakage current density after UV annealing, the leakage current density is still low (<1×10 -9 A / cm 2 ). This is another unique property of films made using the hydrido-dimethyl-alkoxysilane compounds described in formula (1), such as DMSBOS, because the as-deposited films made using the hydrido-dimethyl-alkoxysilane compounds described in formula (1) have low leakage current densities (<1×10) at high electric field strengths (≧4 MV / cm). -9 A / cm 2 ) and require post-deposition steps, such as UV annealing. That is, the desired electrical film properties are observed in as-deposited films from hydrido-dimethyl-alkoxysilane compounds described in formula (1) without the need for UV annealing.

[0116] Thus, the hydrido-dimethyl-alkoxysilane compounds given by formula (1) satisfy the urgent need for dense, as-deposited low-k materials in integrated circuit fabrication, especially for lowest level back-end interconnect processes. The hydrido-dimethyl-alkoxysilane compounds given by formula (1), such as DMSBOS, DMIPOS, and DMTBOS, are volatile structure-forming low-k materials that exhibit high mechanical strength, strong resistance to plasma-induced damage, and a surface area of ​​1×10 at high electric field strengths (≧4 MV / cm). -9 A / cm 2 They can be used to deposit dense low-k films with leakage current densities of less than 1000 nm and high breakdown voltages (>5 MV / cm) at a given value of dielectric constant (k≦3.5). Their precursors have high vapor pressures (low molecular weights), facilitating delivery as gas-phase reagents into the reaction chamber without condensation in the vapor delivery lines or process pump exhausts. Furthermore, films deposited from such precursors do not require post-deposition treatments, such as UV curing, to improve the mechanical or electrical properties of the film. That is, the inherent properties of their as-deposited films meet the requirements for integrated circuit fabrication, so that no post-deposition steps (i.e., UV curing) are required. Furthermore, DMSBOS structurer precursors exhibit unique properties within the class of hydrido-dimethyl-alkoxysilane compounds given by formula (1). In particular, films deposited using DMSBOS structure-forming precursor have the highest mechanical properties and the lowest leakage current density at high electric fields (4 MV / cm) relative to other films deposited using hydrido-dimethyl-alkoxysilane compounds given by formula (1), such as DMIPOS and DMTBOS.

Claims

1. 1. A method for depositing an organosilica film, the method comprising: Providing a substrate in a reaction chamber; In the reaction chamber, (1) H (M) ２ SiOR wherein R is selected from the group consisting of isopropyl, sec-butyl, tert-butyl, 2-pentyl, 3-pentyl, 3-methyl-2-butyl, tert-pentyl, cyclopentyl, and cyclohexyl; introducing a gaseous composition comprising a hydrido-dimethyl-alkoxysilane having a structure given by applying energy to the gaseous composition in the reaction chamber to induce reaction of the hydrido-dimethyl-alkoxysilane and thereby deposit the organosilica film on the substrate; Including, the organosilica film having a dielectric constant of about 2.70 to about 3.50, an elastic modulus of about 6 to about 36 GPa, and an XPS carbon content of about 10 to about 36 atomic %; method.

2. 2. The method of claim 1, wherein the composition comprising the hydrido-dimethyl-alkoxysilane of formula (1) is substantially free of one or more impurities selected from the group consisting of halide compounds, water, metals, oxygen-containing impurities, nitrogen-containing impurities, and combinations thereof.

3. The method of claim 1 , wherein the gaseous composition comprising hydrido-dimethyl-alkoxysilane does not include a curing agent.

4. The method of claim 1 , wherein the method is a chemical vapor deposition method.

5. The method of claim 1 , wherein the method is a plasma enhanced chemical vapor deposition method.

6. The gaseous composition comprising hydrido-dimethyl-alkoxysilane is ２ , N ２ O, NO, NO ２ , CO ２ , CO, water, H ２ O ２ 10. The method of claim 1, further comprising at least one oxidizing agent selected from the group consisting of ozone, alcohol, and combinations thereof.

7. The method of claim 1 , wherein the gaseous composition comprising hydrido-dimethyl-alkoxysilane does not include an oxidizer.

8. The reaction chamber is filled with He, Ar, N during the applying step. ２ 2. The method of claim 1, further comprising at least one gas selected from the group consisting of Kr, Ne, and Xe.

9. The reaction chamber is adapted to receive O during the applying step. ２ , N ２ O, NO, NO ２ , CO ２ , CO, water, H ２ O ２ 9. The method of claim 8, further comprising at least one oxidizing agent selected from the group consisting of ozone, alcohol, and combinations thereof.

10. The method of claim 1, wherein the organosilica film has a refractive index of about 1.3 to about 1.7 at 632 nm.

11. The method of claim 1 , wherein the organosilica film is deposited at a rate of about 5 nm / min to about 400 nm / min.

12. The organosilica film has a relative bridged methylene (SiCH) ratio of about 10 to about 30 as measured by IR spectroscopy. ２ Si) density value and a relative SiCH ２ 2. The method of claim 1, further comprising a Si Density* / Total Carbon (Atomic % XPS) ratio.

13. The organosilica film has a resistance of 1×10 －９ A / cm ２ The method of claim 1 , wherein the leakage current density has a value of less than 100 nm.

14. 2. The method of claim 1, wherein R is sec-butyl.

15. Formula (1), (1) H (M) ２ SiOR wherein R is selected from the group consisting of isopropyl, sec-butyl, tert-butyl, 2-pentyl, 3-pentyl, 3-methyl-2-butyl, tert-pentyl, cyclopentyl, and cyclohexyl; 1. A composition for vapor deposition of a dielectric film comprising a hydrido-dimethyl-alkoxysilane having the structure given in the dielectric film having a dielectric constant of about 2.70 to about 3.50, an elastic modulus of about 6 to about 36 GPa, and an XPS carbon content of about 10 to about 36 atomic %; composition.

16. 16. The composition of claim 15, wherein the composition is substantially free of one or more impurities selected from the group consisting of halide compounds, water, oxygen-containing impurities, nitrogen-containing impurities, and metals.

17. 16. The composition of claim 15, wherein the composition is substantially free of chloride compounds.

18. 20. The composition of claim 17, wherein the chloride compounds, if present, are present in a concentration of 10 ppm or less as measured by IC.

19. 18. The composition of claim 17, wherein the chloride compounds, if present, are present in a concentration of 5 ppm or less as measured by IC.

20. 20. The composition of claim 17, wherein the chloride compounds, if present, are present in a concentration of 1 ppm or less as measured by IC.

21. 16. The composition of claim 15, wherein the composition is substantially free of nitrogen-containing impurities.

22. 22. The composition of claim 21, wherein the nitrogen-containing impurities, if present, are present in a concentration of about 1000 ppm or less as measured by GC.

23. 22. The composition of claim 21, wherein the nitrogen-containing impurities, if present, are present in a concentration of about 500 ppm or less as measured by GC.

24. 2. The method of claim 1, wherein the organosilica film has a refractive index (RI) of about 1.3 to about 1.6 at 632 nm and a nitrogen content of 0.1 atomic % or less as measured by XPS or SIMS or RBS.

25. 16. The composition of claim 15, wherein the hydrido-dimethyl-alkoxysilane is selected from the group consisting of dimethyl-iso-propoxysilane, dimethyl-sec-butoxysilane, dimethyl-tert-butoxysilane, dimethyl-2-pentoxysilane, dimethyl-3-pentoxysilane, dimethyl-3-methyl-2-pentoxysilane, dimethyl-tert-pentoxysilane, dimethyl-cyclopentoxysilane, and dimethyl-cyclohexoxysilane.

26. The composition of claim 15, wherein the composition comprises dimethyl-iso-propoxysilane.

27. The composition of claim 15, wherein the composition comprises dimethyl-tert-pentoxysilane.

28. The composition of claim 15, wherein the composition comprises dimethyl-2-pentoxysilane.

29. The method of claim 1, wherein the hydrido-dimethyl-alkoxysilane is dimethyl-sec-butoxysilane.

30. The method of claim 1, wherein the hydrido-dimethyl-alkoxysilane is dimethyl-cyclopentoxysilane.

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