Silicon compounds and methods of depositing films using the same

Abstract

A chemical vapor deposition method for preparing a dielectric film, the method comprising: providing a substrate into a reaction chamber; introducing a gaseous reagent into the reaction chamber, wherein the gaseous reagent comprises a silicon precursor comprising a silicon compound having the formula R n H 4‑n Si as defined herein, and applying energy to the gaseous reagent in the reaction chamber to induce a reaction of the gaseous reagent to deposit a film on the substrate. The deposited film is suitable for its intended use without the need to apply an optional additional curing step to the film as deposited.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Provisional Patent Application Serial No. 62 / 888,019, filed August 16, 2019, the entire contents of which are incorporated herein by reference. Background of the Invention

[0004] This document describes compositions and methods for forming dielectric films using hydrogenated alkylsilane compounds. More specifically, this document describes compositions and methods for forming low-dielectric-constant (“low-k” films or films having a dielectric constant of about 3.2 or less) films, wherein the method for depositing the film is a chemical vapor deposition (CVD) method. The low-dielectric films produced by the compositions and methods described herein can be used as insulating layers, for example, in electronic devices.

[0005] The electronics industry uses dielectric materials as insulating layers between circuits and components in integrated circuits (ICs) and related electronic devices. To improve the speed and memory storage capabilities of microelectronic devices (e.g., computer chips), line sizes are being reduced. As line sizes decrease, the insulation requirements for interlayer dielectrics (ILDs) become much more stringent. Reducing the spacing requires a lower dielectric constant to minimize the RC time constant, where R is the resistance of the conductor and C is the capacitance of the insulating dielectric layer. The capacitance (C) is inversely proportional to the spacing and directly proportional to the dielectric constant (k) of the interlayer dielectric (ILD). Conventional silicon dioxide (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. Several industrial methods have attempted to produce silicon dioxide-based CVD films with lower dielectric constants; the most successful is the doping of insulating silicon dioxide films with organic groups, providing a dielectric constant of approximately 2.7 to approximately 3.5. This type of silicone glass is typically formed by depositing a dense film (density approximately 1.5 g / cm³) of silicone precursors (e.g., methylsilanes or siloxanes) and an oxidizing agent (e.g., O₂ or N₂O). 3 Organosilicon glass will be referred to as OSG in this paper. As the carbon content of OSG increases, the mechanical strength of the film, such as the film hardness (H) and elastic modulus (EM), tends to decrease rapidly with the decrease of dielectric constant.

[0006] One challenge recognized in industry is that films with low dielectric constants typically have lower mechanical strength, leading to increased defects in narrow-pitch films, such as delamination, warping, and increased electromigration (e.g., observed in wires made of copper embedded in dielectric films with reduced mechanical properties). Such defects can cause premature dielectric breakdown or voids in the conductive copper wires, resulting in premature device failure. Carbon depletion in OSG films can also lead to one or more of the following problems: increased dielectric constant of the film; film etching and feature bending during wet cleaning steps; pattern collapse of fine features during wet cleaning steps after patterning etching due to the absorption of moisture into the film by hydrophobic loss; and / or integration problems when depositing subsequent layers (e.g., but not limited to, copper diffusion barrier layers, such as Ta / TaN or advanced Co or MnN barrier layers).

[0007] One possible solution to one or more of these problems is to use an OSG membrane with increased carbon content while maintaining mechanical strength. Unfortunately, the relationship between increasing Si-Me content generally leads to a decrease in mechanical properties, so membranes with more Si-Me will negatively impact mechanical strength (which is important for integration).

[0008] One proposed solution is to use the general formula R. x (RO) 3-x Si(CH2) y SiR z (OR) 3-z Ethylene or methylene-bridged alkoxysilanes, where x = 0-3, y = 1 or 2, z = 0-3. The use of bridging materials is thought to avoid negative mechanical effects by replacing bridging oxygen with bridging carbon chains, as the network connectivity will remain the same. This stems from the belief that replacing bridging oxygen with terminal methyl groups would reduce mechanical strength by decreasing network connectivity. In this way, oxygen atoms can be replaced with 1-2 carbon atoms to increase the atomic weight percentage (%) of C without reducing mechanical strength. However, these bridging precursors typically have very high boiling points because the presence of two silicon groups increases the molecular weight. This increased boiling point can negatively impact the manufacturing process by making it difficult to transport the chemical precursor as a gaseous reagent to the reaction chamber without condensation in the steam delivery line or process pump exhaust.

[0009] Therefore, there is a need in the art for a dielectric precursor that provides a film with increased carbon content during deposition without suffering the aforementioned disadvantages. Invention Overview

[0011] The methods and compositions described herein satisfy one or more of the above-mentioned needs. The methods and compositions described herein use hydrogenated alkylsilanes (such as, for example, triethylsilane or tri-n-propylsilane) as silicon precursors, which can be used for deposition to provide a low-k interlayer dielectric, or can be subsequently treated with thermal, plasma, or ultraviolet energy sources to modify film properties, such as providing chemical crosslinking to improve mechanical strength. Furthermore, films deposited using the silicon compounds described herein as silicon precursors contain a relatively high amount of carbon. In addition, the silicon compounds described herein have a lower mw compared to other prior art silicon precursors (such as bridging precursors that inherently have two silicon groups (e.g., alkoxysilane precursors) with higher molecular weights (mw) and higher boiling points), thus making silicon precursors with boiling points of 250°C or lower, more preferably 200°C or lower, easier to process, for example, in high-volume manufacturing processes.

[0012] This article describes a dielectric film based on a single precursor, comprising: Si v O w C x H y F z The material is represented as follows, where v + w + x + y + z = 100%, v is 10 to 35 atomic%, w is 10 to 65 atomic%, x is 5 to 45 atomic%, y is 10 to 50 atomic%, and z is 0 to 15 atomic%. The membrane has a volumetric porosity of 0 to 30.0%, a dielectric constant of 2.5 to 3.2, and mechanical properties such as a hardness of 1.0 to 7.0 gigapascals (GPa) and an elastic modulus of 4.0 to 40.0 GPa. In some embodiments, the membrane contains a high carbon content (10-40%) as measured by X-ray photoelectron spectroscopy (XPS) and exhibits a reduced carbon removal depth when exposed to plasmas such as O2 or NH3, as determined by examining the carbon content determined by XPS depth profiling.

[0013] In one aspect, a chemical vapor deposition method for preparing a dielectric film is provided, comprising: providing a substrate into a reaction chamber; introducing a gaseous reagent into the reaction chamber, wherein the gaseous reagent comprises at least one oxygen source and a silicon precursor, the silicon precursor comprising having the formula R n H 4-n Hydrogenated alkylsilane compounds of Si, wherein each R is independently selected from straight-chain, branched, or cyclic C2 to C3. 10 An alkyl group, wherein n is 2-3; and energy is applied to a gaseous reagent in a reaction chamber to induce a reaction of the gaseous reagent, thereby depositing a film on a substrate. The film thus deposited can be used with or without additional treatment, such as thermal annealing, plasma exposure, or UV curing.

[0014] On the other hand, a chemical vapor deposition or plasma-enhanced chemical vapor deposition method for preparing low-k dielectric films is provided, comprising: providing a substrate into a reaction chamber; introducing a gaseous reagent into the reaction chamber, wherein the gaseous reagent comprises at least one oxygen source and a reagent having the formula R n H 4-n Hydrogenated alkylsilane compounds of Si, wherein each R is independently selected from straight-chain, branched, or cyclic C2 to C3. 10 The method comprises an alkyl group, wherein n is 2-3; and applying energy to a gaseous reagent in a reaction chamber to induce a reaction of the gaseous reagent to deposit a film on a substrate; applying energy to a gaseous reagent in a reaction chamber to induce a reaction of the gaseous reagent to deposit a film on a substrate. Optionally, the method includes an additional step of applying energy to the deposited film, wherein the additional energy is selected from thermal annealing, plasma exposure, and UV curing, wherein the additional energy alters chemical bonding to enhance the mechanical properties of the film. The silicon-containing film deposited according to the method disclosed herein has a dielectric constant of less than 3.3. In some embodiments, the silicon precursor further comprises a hardening additive. Invention Details

[0016] This article describes a chemical vapor deposition method for preparing dielectric films, comprising: providing a substrate into a reaction chamber; introducing a gaseous reagent into the reaction chamber, wherein the gaseous reagent comprises a silicon precursor and at least one oxygen source, the silicon precursor comprising having the formula R n H 4-n Hydrogenated alkylsilane compounds of Si, wherein each R is independently selected from straight-chain, branched, or cyclic C2 to C3. 10 Alkyl groups and n is 2-3; and energy is applied to the gaseous reagent in the reaction chamber to induce a reaction of the gaseous reagent, thereby depositing a film on the substrate. The film can be used as is, or it can be subsequently treated with additional energy selected from thermal energy (annealing), plasma exposure, and ultraviolet curing to modify the chemical properties of the film by increasing the mechanical strength of the film and producing a dielectric constant less than 3.3.

[0017] Compared to existing structures forming precursors such as diethoxymethylsilane (DEMS), the hydrogenated alkylsilane compounds described herein offer unique properties that allow for the incorporation of greater carbon content into the dielectric film with less impact on the mechanical properties of low-k dielectric films. For example, DEMS provides a mixed ligand system containing two alkoxy groups, one silane-methyl (Si-Me), and one silane-hydride, offering a balance of reactive sites and allowing for the formation of mechanically stronger films while retaining the desired dielectric constant. An advantage of using hydrogenated alkylsilane compounds is the absence of silane-methyl groups in the precursor, which tends to reduce mechanical strength, while providing carbon from higher alkyl groups to the OSG film to reduce the dielectric constant and impart hydrophobicity. Although there are no methyl groups in the precursor, the resulting OSG film contains some methyl groups as well as some alkyl groups bridging two distinct silicon atoms, presumably formed due to fragmentation occurring within the plasma itself.

[0018] Low-k dielectric films are silicone glass (“OSG”) films or materials. Organosilicones are candidates for low-k materials. Since the type of silicone precursor has a significant impact on the film structure and composition, it is beneficial to use a precursor that provides the desired film properties to ensure that the addition of the required amount of carbon achieves the desired dielectric constant without producing a mechanically undesirable film. The methods and compositions described herein provide a means of producing low-k dielectric films with an ideal balance of electrical and mechanical properties, as well as other beneficial film properties such as high carbon content, to provide improved integrated plasma damage resistance.

[0019] In certain embodiments of the methods and compositions described herein, a silicon-containing dielectric layer is deposited on at least a portion of a substrate by chemical vapor deposition (CVD) or plasma-enhanced chemical vapor deposition (PECVD), preferably using a reaction chamber PECVD process. Suitable substrates include, but are not limited to, semiconductor materials such as gallium arsenide (“GaAs”), silicon, and silicon-containing compositions, such as crystalline silicon, polycrystalline silicon, amorphous silicon, epitaxial silicon, silicon dioxide (“SiO2”), silicon glass, silicon nitride, fused silicon, glass, quartz, borosilicate glass, and combinations thereof. Other suitable materials include chromium, molybdenum, and other metals commonly used in semiconductor, integrated circuit, flat panel display, and flexible display applications. The substrate may have additional layers, such as, for example, silicon, SiO2, organosilicon 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, such as metal oxides of alumina and germanium oxide. Further layers may also be germanium silicates, 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.

[0020] In some embodiments, a silicon-containing dielectric layer is deposited on at least a portion of a substrate by introducing a gaseous reagent comprising at least one silicon precursor into a reaction chamber, wherein the silicon precursor comprises a silicon compound but does not contain a pore-forming agent precursor. In another embodiment, a silicon-containing dielectric layer is deposited on at least a portion of a substrate by introducing a gaseous reagent comprising at least one silicon precursor into a reaction chamber, wherein the silicon precursor comprises a hydrogenated alkylsilane compound having a hardening additive.

[0021] The methods and compositions described herein use formula R n H 4-n Silicon precursors of Si, wherein each R is independently selected from linear, branched, or cyclic C2 to C3. 10 Alkyl group and n is 2-3.

[0022] In the above formula and throughout the specification, the term "alkyl" refers to a straight-chain, branched, or cyclic functional group having 2 to 10 carbon atoms. Exemplary straight-chain alkyl groups include, but are not limited to, ethyl, n-propyl, butyl, pentyl, and hexyl. Exemplary branched alkyl groups include, but are not limited to, isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, tert-pentyl, isohexyl, and neohexyl. Exemplary cyclic alkyl groups include, but are not limited to, cyclopentyl, cyclohexyl, or methylcyclopentyl.

[0023] Throughout this specification, the term "oxygen source" refers to a gas containing oxygen (O2), a mixture of oxygen and helium, a mixture of oxygen and argon, carbon dioxide, carbon monoxide, or a combination thereof.

[0024] Throughout the specification, the term "dielectric film" refers to a film containing silicon and oxygen atoms, with a composition of Si. v O w C x H y F z Where v+w+x+y+z=100%, v is 10 to 35 atoms, w is 10 to 65 atoms, x is 5 to 40 atoms, y is 10 to 50 atoms, and z is 0 to 15 atoms.

[0025] Each R is independently selected from straight, branched, or cyclic C2 to C3. 10 Alkyl groups with n = 2-3 of the formula R n H 4-n Examples of embodiments of Si are as follows: triethylsilane, diethylsilane, tri-n-propylsilane, di-n-propylsilane, ethyl di-n-propylsilane, diethyl n-propylsilane, di-n-propylsilane, di-n-butylsilane, tri-n-butylsilane, triisopropylsilane, diethylcyclopentylsilane, or diethylcyclohexylsilane.

[0026] The hydrogenated alkylsilanes described herein, as well as the methods and compositions comprising them, are preferably substantially free of one or more impurities, such as, but not limited to, halide ions and water. As used herein, the term “substantially free” in relation to each impurity means 100 ppm or less, 50 ppm or less, 10 ppm or less, 5 ppm or less, and 1 ppm or less of each impurity (e.g., but not limited to chlorides or water).

[0027] In some embodiments, the hydrogenated alkylsilane compounds disclosed herein are substantially free of or free of halide ions (or halides), such as, for example, chlorides and fluorides, bromides and iodides. As used herein, the term “substantially free” means 100 ppm or less, 50 ppm or less, 10 ppm or less, 5 ppm or less, 1 ppm or less of halide impurities. As used herein, the term “free” means 0 ppm of halides. For example, chlorides are known to be used as decomposition catalysts for hydrogenated alkylsilane compounds and as potential contaminants detrimental to the performance of manufactured electronic devices. The gradual degradation of hydrogenated alkylsilane compounds can directly affect film deposition processes, making it difficult for semiconductor manufacturers to meet film specifications. Furthermore, shelf life or stability is negatively affected by the high degradation rate of silicon compounds, making it difficult to guarantee a shelf life of 1-2 years. Therefore, the accelerated decomposition of hydrogenated alkylsilane compounds presents safety and performance issues related to the formation of these flammable and / or spontaneously combustible byproducts. The silicon compounds are also preferably substantially free of metal ions, such as Al. 3+ Ions, Fe 2+ Fe 3+ Ni 2+ Cr 3 As used in this article, with Al 3+ Ions, Fe 2+ Fe 3+ Ni 2+ Cr 3+ The term “substantially free” means less than 5 ppm (by weight), preferably less than 3 ppm, more preferably less than 1 ppm, and most preferably less than 0.1 ppm.

[0028] The compositions according to the invention that are substantially free of halides can be obtained by: (1) reducing or eliminating chloride sources during chemical synthesis, and / or (2) implementing an efficient purification process to remove chlorides from the crude product, such that the final purified product is substantially free of chlorides. During synthesis, chloride sources can be reduced by using halide-free reagents (e.g., chlorosilane, bromosilane, or iodosilane), thereby avoiding the generation of halide-containing byproducts. Furthermore, the aforementioned reagents should be substantially free of chloride impurities so that the resulting crude product is substantially free of chloride impurities. Similarly, the synthesis should not use halogenated solvents, catalysts, or solvents containing unacceptably high levels of halide contamination. The crude product can also be treated by various purification methods to make the final product substantially free of halides such as chlorides. Such methods are well described in the prior art and may include, but are not limited to, purification processes such as distillation or adsorption. Distillation is commonly used to separate impurities from the desired product by utilizing differences in boiling points. Adsorption can also be used to achieve separation by utilizing the differential adsorption properties of components, so that the final product is substantially free of halides. Adsorbents, such as commercially available MgO-Al2O3 mixtures, can be used to remove halides such as chlorides.

[0029] Although existing silicon-containing precursors, such as DEMS, polymerize upon energy supply in a reaction chamber to form structures with -O-bonds (e.g., -Si-O-Si- or -Si-OC-) in the polymer backbone, it is believed that hydrogenated alkylsilane compounds, such as triethylsilane molecules, polymerize to form structures in which some -O-bridges in the backbone are replaced by -CH2-methylene or -CH2CH2-ethylene bridges. In films deposited using DEMS as a structure-forming precursor, where carbon is primarily present in the form of terminal Si-M groups, there is a relationship between %Si-Me (directly related to %C) and mechanical strength, where replacing bridging Si-O-Si groups with two terminal Si-Me groups reduces mechanical properties because the network structure is disrupted. Similarly, it is also believed that some Si-Me groups, along with bridging methylene or ethylene groups, are formed during plasma deposition of, for example, triethylsilane. In this way, carbon can be incorporated in the form of bridging groups so that, from a mechanical strength perspective, the network structure is not disrupted by increasing the carbon content in the film. Unbound by any particular theory, this property is believed to add carbon to the film, making it more resilient to carbon depletion in porous OSG films caused by processes such as film etching, plasma ashing of photoresist, and NH3 plasma treatment of the copper surface. Carbon depletion in OSG films can lead to an increase in the defective dielectric constant of the film, as well as problems with film etching and feature bending during wet cleaning steps, and / or integration issues when depositing copper diffusion barrier layers.

[0030] Although the phrase “gaseous reagent” is sometimes used in this article to describe reagents, the phrase is intended to cover reagents that are delivered directly to the reactor as a gas, as a vaporized liquid, as a sublimated solid, and / or delivered to the reactor via an inert carrier gas.

[0031] Furthermore, reagents can be transported to the reactor individually or as mixtures from different sources. Reagents can be delivered to the reactor system in various ways, with pressurized stainless steel containers equipped with appropriate valves and fittings being preferred to allow the delivery of liquids to the process reactor.

[0032] In addition to the structure-forming material (i.e., the compound of formula I), other materials may be introduced into the reaction chamber before, during, and / or after the deposition reaction. Such materials include, for example, inert gases (e.g., He, Ar, N2, Kr, Xe, etc., which can be used as carrier gases for lower volatility precursors and / or can promote the solidification of such deposited materials and provide a more stable final film) and reactive substances, such as oxygen-containing substances like O2, O3, and N2O, gaseous or liquid organic substances, CO2, or CO. In one specific embodiment, the reaction mixture introduced into the reaction chamber contains at least one oxidant selected from O2, N2O, NO, NO2, CO2, water, H2O2, ozone, and combinations thereof. In an alternative embodiment, the reaction mixture does not contain an oxidant.

[0033] Energy is applied to a gaseous reagent to induce a gaseous reaction and form a film on a substrate. This energy can be provided, for example, by plasma, pulsed plasma, helical wave 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 plasma characteristics at the substrate surface. Preferably, the film is formed by plasma-enhanced chemical vapor deposition (“PECVD”).

[0034] The flow rate range for each gaseous reagent is preferably 10 to 5000 sccm per single 200 mm wafer, more preferably 30 to 1000 sccm. A single rate is selected to provide the required amounts of silicon, carbon, and oxygen in the film. The actual flow rate required may depend on the wafer size and chamber configuration, and is by no means limited to 200 mm wafers or single-wafer chambers.

[0035] In some implementations, the film is deposited at a deposition rate of approximately 50 nanometers (nm) per minute.

[0036] The pressure in the reaction chamber during deposition ranges from about 0.01 to about 600 Torr or from about 1 to 15 Torr.

[0037] The film is preferably deposited to a thickness of 0.002 to 10 micrometers, although this thickness can be varied as needed. Blanket-coated films deposited on unpatterned surfaces exhibit excellent uniformity, with a thickness variation of less than 2% over the entire substrate with one standard deviation, provided there is reasonable edge exclusion, where, for example, the outermost 5 mm edge of the substrate is not included in the statistical calculation of uniformity.

[0038] A preferred embodiment of the present invention provides a thin film material that, compared to other porous low-k dielectric films deposited using other structural formation precursors known in the art, exhibits a low dielectric constant and improved mechanical properties, thermal stability, and chemical resistance (to oxygen, aqueous oxidizing environments, etc.). The structural formation precursors described herein, comprising hydrogenated alkylsilane compounds having the stated formula, provide higher carbon incorporation in the film (preferably primarily in the form of organic carbon, -CH). x (where x is 1 to 3), thereby using specific precursors or network-forming chemicals for depositing films. In some embodiments, most of the hydrogen in the film is bonded to carbon.

[0039] The low-k dielectric films deposited according to the compositions and methods described herein comprise: (a) about 10 to about 35 atomic percent, more preferably about 20 to about 30 atomic percent, of silicon; (b) about 10 to about 65 atomic percent, more preferably about 20 to about 45 atomic percent, of oxygen; (c) about 10 to about 50 atomic percent, more preferably about 15 to about 40 atomic percent, of hydrogen; and (d) about 5 to about 40 atomic percent, more preferably about 10 to about 45 atomic percent, of carbon. The films may also comprise about 0.1 to about 15 atomic percent, more preferably about 0.5 to about 7.0 atomic percent, of fluorine to improve one or more material properties. Smaller amounts of other elements may also be present in some films of the present invention. OSG materials are considered low-k materials because their dielectric constant is lower than that of silicon glass, a standard material conventionally used in industry.

[0040] Depending on the process conditions and desired final membrane properties, the total porosity of the membrane can be from 0 to 15% or greater. The membranes of the present invention preferably have a density of less than 2.3 g / ml, or optionally less than 2.0 g / ml or less than 1.8 g / ml. The total porosity of the OSG membrane can be affected by post-deposition treatments, including exposure to heat or UV curing, or plasma sources. While preferred embodiments of the invention do not include the addition of pore-forming agents during membrane deposition, porosity can be induced by post-deposition treatments such as UV curing. For example, UV treatment can result in a porosity approaching 15% to about 20%, preferably between about 5% and about 10%.

[0041] The membrane of the present invention may also contain fluorine in the form of inorganic fluorine (e.g., Si-F). When present, the fluorine content is preferably in the range of about 0.5 to about 7 atomic percent.

[0042] The membrane of the present invention is thermally stable and has good chemical resistance. In particular, the preferred membrane after annealing exhibits an average weight loss of less than 1.0 wt% / hour under N2 at an isotherm of 425°C. Furthermore, the membrane preferably exhibits an average weight loss of less than 1.0 wt% / hour in air at an isotherm of 425°C.

[0043] The film is suitable for a variety of applications. It is particularly well-suited for deposition on semiconductor substrates and is especially suitable for use as, for example, insulating layers, interlayer dielectric layers, and / or intermetallic dielectric layers. The film can form conformal coatings. The mechanical properties exhibited by these films make them particularly suitable for aluminum subtractive processing and copper damascene or dual damascene processes.

[0044] The film is compatible with chemical mechanical polishing (CMP) and anisotropic etching, and can adhere to a variety of materials, such as silicon, SiO2, Si3N4, OSG, FSG, silicon carbide, hydrogenated silicon carbide, silicon nitride, hydrogenated silicon nitride, silicon carbonitride, hydrogenated silicon carbonitride, boron nitride, antireflective coatings, photoresists, organic polymers, porous organic and inorganic materials, metals such as copper and aluminum, and diffusion barrier layers such as, but not limited to, TiN, Ti(C)N, TaN, Ta(C)N, Ta, W, WN, or W(C)N. The film is preferably able to adhere to at least one of the aforementioned materials sufficiently to pass conventional tensile tests, such as the ASTM D3359-95a tape tensile test. If no significant film removal is observed, the sample is considered to have passed the test.

[0045] Therefore, in some embodiments, the film is an insulating layer, an interlayer dielectric layer, an intermetallic dielectric layer, a capping layer, a chemical mechanical polishing (CMP) or etch stop layer, a barrier layer, or an adhesive layer in an integrated circuit.

[0046] While the present invention is particularly well-suited for providing films, and the products of the present invention are primarily described herein as films, the invention is not limited thereto. The products of the present invention can be provided in any form capable of being deposited by CVD, such as coatings, multilayer components, and other types of objects that are not necessarily planar or thin, and a wide range of objects not necessarily used in integrated circuits. Preferably, the substrate is a semiconductor.

[0047] In addition to the OSG product of this invention, this disclosure includes methods for preparing the product, methods for using the product, and compounds and compositions that can be used to prepare the product. For example, a process for fabricating integrated circuits on a semiconductor device is disclosed in U.S. Patent No. 6,583,049, which is incorporated herein by reference.

[0048] The composition of the present invention may further include, for example, at least one pressurizable container (preferably stainless steel) equipped with suitable valves and fittings to allow delivery of substances having R n H 4-nFrom silicon precursor to process reactor, where R can be independently selected from linear, branched, or cyclic C2 to C3. 10 Alkyl groups, and n can be 2-3, for example, triethylsilane.

[0049] The initial (or thus deposited) film can be further processed through a curing step, i.e., applying an additional energy source to the film, which can include thermal annealing, chemical treatment, in-situ or remote plasma treatment, photocuring (e.g., ultraviolet light), and / or microwave curing. Other in-situ or post-deposition treatments can be used to enhance material properties such as hardness, stability (to shrinkage, air exposure, etching, wet etching, etc.), integrity, uniformity, and adhesion. Therefore, the term "post-treatment" as used herein refers to treating the film with energy (e.g., heat, plasma, photons, electrons, microwaves, etc.) or chemicals to enhance material properties.

[0050] The conditions for post-processing can vary greatly. For example, post-processing can be performed under high pressure or vacuum.

[0051] UV annealing is the preferred curing method and is typically carried out under the following conditions.

[0052] The environment can be inert (e.g., nitrogen, CO2, rare gases (He, Ar, Ne, Kr, Xe), etc.), oxidizing (e.g., oxygen, air, depleted oxygen environment, oxygen-enriched environment, ozone, nitrous oxide, etc.), or reducing (dilute or concentrated hydrogen, hydrocarbons (saturated, unsaturated, straight-chain or branched, aromatics), ammonia, hydrazine, methylhydrazine, etc.). The pressure is preferably from about 1 Torr to about 1000 Torr, more preferably atmospheric pressure. However, a vacuum environment can also be used for thermal annealing and any other post-treatment methods. The temperature is preferably 200-500°C, with a heating rate of 0.1 to 100°C / min. The total UV annealing time is preferably from 0.01 minutes to 12 hours.

[0053] The OSG membrane was chemically treated under the following conditions.

[0054] The properties of the final material are enhanced by fluorination (HF, SIF4, NF3, F2, COF2, CO2F2, etc.), oxidation (H2O2, O3, etc.), chemical drying, methylation, or other chemical treatments. The chemicals used in such treatments can be in solid, liquid, gaseous, and / or supercritical fluid states.

[0055] Plasma treatment for possible chemical modification of OSG membranes was performed under the following conditions.

[0056] The environment can be inert (nitrogen, CO2, rare gases (He, Ar, Ne, Kr, Xe), etc.), oxidizing (e.g., oxygen, air, depleted oxygen environment, oxygen-rich environment, ozone, nitrous oxide, etc.), or reducing (e.g., dilute or concentrated hydrogen, hydrocarbons (saturated, unsaturated, straight-chain or branched, aromatics), ammonia, hydrazine, methylhydrazine, etc.). The plasma power is preferably 0-5000 W. The temperature is preferably from approximately ambient temperature to approximately 500°C. The pressure is preferably from 10 mTorr to atmospheric pressure. The total curing time is preferably from 0.01 minutes to 12 hours.

[0057] UV curing for chemical crosslinking of organosilicon films is typically carried out under the following conditions.

[0058] The environment can be inert (e.g., nitrogen, CO2, rare gases (He, Ar, Ne, Kr, Xe), etc.), oxidizing (e.g., oxygen, air, depleted oxygen environment, oxygen-rich environment, ozone, nitrous oxide, etc.), or reducing (e.g., dilute or concentrated hydrocarbons, hydrogen, etc.). The temperature is preferably from about ambient temperature to about 500°C. The power is preferably from 0 to about 5000 W. The wavelength is preferably IR, visible light, UV, or deep UV (wavelength <200 nm). The total UV curing time is preferably from 0.01 minutes to 12 hours.

[0059] Microwave post-treatment of organosilicon membranes is typically performed under the following conditions.

[0060] The environment can be inert (e.g., nitrogen, CO2, rare gases (He, Ar, Ne, Kr, Xe), etc.), oxidizing (e.g., oxygen, air, depleted oxygen environment, oxygen-rich environment, ozone, nitrous oxide, etc.), or reducing (e.g., dilute or concentrated hydrocarbons, hydrogen, etc.). The temperature is preferably from approximately ambient temperature to approximately 500°C. The power and wavelength are variable and can be adjusted for specific bonds. The total curing time is preferably from 0.01 minutes to 12 hours.

[0061] Electron beam post-processing, used to improve film properties, is typically performed under the following conditions.

[0062] The environment can be vacuum, inert (e.g., nitrogen, CO2, rare gases (He, Ar, Ne, Kr, Xe), etc.), oxidizing (e.g., oxygen, air, depleted oxygen environment, oxygen-rich environment, ozone, nitrous oxide, etc.), or reducing (e.g., dilute or concentrated hydrocarbons, hydrogen, etc.). The temperature is preferably ambient temperature to 500°C. Electron density and energy can vary and can be adjusted for specific bonds. The total curing time is preferably from 0.001 minutes to 12 hours and can be continuous or pulsed. Further guidance on the general use of electron beams is available in publications such as: S. Chattopadhyay et al., Journal of Materials Science, 36(2001)4323-4330; G. Kloster et al., Proceedings of IITC, June 3-5, 2002, SF, CA; and U.S. Patents 6,207,555 B1, 6,204,201 B1, and 6,132,814 A1. The use of electron beam treatment can provide the removal of pore-forming agents and the enhancement of membrane mechanical properties through the bond-forming process in the matrix.

[0063] The invention will be described in more detail with reference to the following embodiments, but it should be understood that the invention is not to be considered limited thereto. Example

[0064] Exemplary films or 200mm wafers were fabricated using a plasma-enhanced CVD (PECVD) process from a variety of different chemical precursors and process conditions in a 200mm DxZ or DxL reaction chamber or a vacuum chamber equipped with an Advance Energy 200 RF generator using an Applied Materials Precision-5000 system. The PECVD process typically includes the following basic steps: initial setup and stabilization of the gas flow, deposition of the film onto a silicon wafer substrate, and purging / evacuation of the chamber prior to substrate removal. Following deposition, some films underwent UV annealing. UV annealing was performed using a Fusion UV system with a broadband UV lamp at one or more pressures below <10 Torr and one or more temperatures below 400°C, with the wafer held under a helium flow. Experiments were conducted on p-type silicon wafers (resistivity range = 8–12 ohm-cm).

[0065] Thickness and refractive index were measured using an SCI FilmTek 2000 Reflectometer. Dielectric constant was determined on p-type wafers with moderate resistivity (range 8–12 ohm-cm) using Hg probe technology. Mechanical properties were determined using an MTS Nano Indenter in Examples 1 and 2.

[0066] Example 1: Deposition of OSG film from triethylsilane (3ES) without subsequent UV curing:

[0067] OSG films were deposited onto 200 mm Si wafers using 3ES under the following process conditions. The precursor was delivered to the reaction chamber via direct liquid injection (DLI) at a flow rate of 1400 mg / min, a helium carrier gas flow rate of 200 sccm, an O2 nozzle-to-wafer spacing of 60 sccm, a wafer chuck temperature of 390 °C, and a chamber pressure of 8 tonnes. A 700 W plasma was then applied for 60 seconds. The resulting film was 704 nm thick with a refractive index (RI) of 1.49 and a dielectric constant (k) of 3.0. The film hardness was measured to be 2.7 GPa, and the Young's modulus was 16.3 GPa. The elemental composition was measured by XPS. The film composition was 32.7% C, 36.6% O, and 30.7% Si.

[0068] Example 2: Deposition of OSG film from triethylsilane (3ES), followed by UV curing for 4 minutes:

[0069] OSG films were deposited onto 200 mm Si wafers using 3ES under the following process conditions. The precursor was delivered to the reaction chamber via direct liquid injection (DLI) at a flow rate of 1400 mg / min, a helium carrier gas flow rate of 200 sccm, an O2 nozzle-to-wafer spacing of 60 sccm, a wafer chuck temperature of 390 °C, and a chamber pressure of 8 tbsp. A 700 W plasma was then applied for 60 seconds. After deposition, the wafer was moved to the UV curing chamber using load locking and the film was cured by UV irradiation at 400 °C for 4 minutes. The resulting film was 646 nm thick, with a refractive index (RI) of 1.48 and a dielectric constant (k) of 3.0. The film hardness was measured to be 3.2 GPa, and the Young's modulus was 18.8 GPa. Elemental composition, measured by XPS, was 26.8% C, 41.2% O, and 32% Si.

[0070] Example 3: Deposition of OSG film from tri-n-propylsilane (3nPS) without subsequent UV curing

[0071] OSG films were deposited from 3nPS onto a 200 mm Si wafer using the following process conditions. The 3nPS precursor was fed into the reaction chamber via direct liquid injection (DLI) at a flow rate of 1500 mg / min, a helium carrier gas flow rate of 200 sccm, an O2 nozzle-to-wafer spacing of 60 sccm, a wafer chuck temperature of 390 °C, and a chamber pressure of 6 Torr. A 600 W plasma was applied for 60 seconds. The resulting film had a thickness of 528 nm, a refractive index (RI) of 1.45, and a dielectric constant of 3.0. The film hardness was measured to be 2.6 GPa, and the Young's modulus was 15.6 GPa. Elemental composition determined by XPS was 26.1% C, 43.0% O, and 30.9% Si.

[0072] Example 4: Deposition of OSG film from tri-n-propylsilane (3nPS), followed by 4 minutes of post-deposition UV curing.

[0073] OSG films were deposited onto 200 mm Si wafers using 3 nPS under the following process conditions. The precursor was delivered to the reaction chamber via direct liquid injection (DLI) at a flow rate of 1500 mg / min, a helium carrier gas flow rate of 200 sccm, an O2 nozzle-to-wafer spacing of 60 sccm, a wafer chuck temperature of 390 °C, and a chamber pressure of 6 Torr. A 600 W plasma was then applied for 60 seconds. After deposition, the wafer was moved to the UV curing chamber using load locking, and the film was cured by UV irradiation at 400 °C for 4 minutes. The resulting film had a thickness of 495 nm, a refractive index (RI) of 1.437, and a dielectric constant of 3.2. The film hardness was measured to be 3.7 GPa, and the Young's modulus was 23.4 GPa. Elemental composition, measured by XPS, was 18.8% C, 49% O, and 32.2% Si.

[0074] Comparative Example 1: OSG films were deposited from 1-methyl-1-ethoxy-1-silanecyclopentane (MESCAP) without subsequent UV curing.

[0075] OSG films were deposited from 1-methyl-1-ethoxy-1-silanecyclopentane in a DxZ chamber for 200 mm processing using the following process conditions. The precursor was delivered to the reaction chamber via direct liquid injection (DLI) at a flow rate of 1500 mg / min, a helium carrier gas flow rate of 200 sccm, 10 sccm O2, a nozzle / wafer spacing of 350 m / inch, a wafer chuck temperature of 400 °C, and a chamber pressure of 7 Torr, to which a 600 W plasma was applied. The resulting in-place deposited film exhibited a dielectric constant (k) of 3.03, a hardness (H) of 2.69 GPa, and a refractive index (RI) of 1.50.

[0076] Comparative Example 2: OSG films were deposited from 1-methyl-1-ethoxy-1-silanecyclopentane (MESCAP) and subsequently UV-cured.

[0077] OSG films were deposited from 1-methyl-1-ethoxy-1-silanecyclopentane in a DxZ chamber for 200 mm processing using the following process conditions. The precursor was delivered to the reaction chamber via direct liquid injection (DLI) at a flow rate of 1000 mg / min, a helium carrier gas flow rate of 200 sccm, 10 sccm O2, a nozzle / wafer spacing of 350 m / inch, a wafer chuck temperature of 400 °C, and a chamber pressure of 7 Torr, to which a 400 W plasma was applied. The resulting in-situ deposited film had a dielectric constant (k) of 3.01, a hardness (H) of 2.06 GPa, and a refractive index (RI) of 1.454. After UV curing, k was 3.05, H was 3.58 GPa, and RI was 1.46. This example demonstrates a significant improvement in mechanical strength with minimal increase in k.

[0078] Although the invention has been described and illustrated above with reference to certain specific embodiments and examples, it is not intended to be limited to the details shown. Rather, various modifications may be made to the details within the scope of the claims and their equivalents without departing from the spirit of the invention. For example, all scopes widely referenced herein expressly indicate that they encompass all narrower scopes falling within the broader scope.

Claims

1. A chemical vapor deposition method for preparing dielectric films, the method comprising: Provide a substrate in the reaction chamber; A gaseous reagent without a porogen precursor is introduced into the reaction chamber, wherein the gaseous reagent comprises: Includes R n H 4-n Silicon precursors of Si, wherein each R is independently selected from linear, branched, or cyclic C2 to C3. 10 Alkyl groups with n being 2-3, and At least one oxygen source; and Energy is applied to the gaseous reagent in the reaction chamber to induce a reaction of the gaseous reagent, thereby depositing the film on the substrate, wherein the film is an organosilicon glass film containing the composition Si. v O w C x H y F z , where v+w+x+y+z=100%, v is 10 to 35 atoms, w is 10 to 65 atoms, x is 5 to 40 atoms, y is 10 to 50 atoms, z is 0 to 15 atoms, and the dielectric constant ranges between 2.5 and 3.

3.

2. The method according to claim 1, wherein the silicon precursor is selected from at least one of the following: triethylsilane, diethylsilane, tri-n-propylsilane, ethyl di-n-propylsilane, diethyl-n-propylsilane, di-n-propylsilane, di-n-butylsilane, tri-n-butylsilane, triisopropylsilane, diethylcyclopentylsilane, and diethylcyclohexylsilane.

3. The method according to claim 1, wherein the deposition method is a plasma-enhanced chemical vapor deposition method.

4. The method according to claim 1, wherein the oxygen source comprises at least one oxygen source selected from O2, N2O, NO, NO2, CO2, water, H2O2 and ozone.

5. The method according to claim 1, wherein, while applying energy, at least one gas selected from He, Ar, N2, Kr, Xe, NH3, H2, CO2 or CO is combined with the gaseous reagent in the reaction chamber.

6. The method of claim 1, further comprising the step of applying additional energy to the deposited film.

7. The method of claim 6, wherein the additional energy is selected from at least one of heat treatment, ultraviolet (UV) treatment, electron beam treatment, and gamma radiation treatment.

8. The method of claim 7, wherein the additional energy comprises UV treatment and heat treatment, wherein the UV treatment occurs during at least a portion of the heat treatment.