Selective deposition of carbon on photoresist layers for lithographic applications

Abstract

A method of etching a hard mask layer includes forming a photoresist layer including an organometallic material on a hard mask layer including a metal-containing material, exposing the photoresist layer to ultraviolet radiation through a mask having a selected pattern, removing unexposed regions of the photoresist layer to pattern the photoresist layer, selectively forming a passivation layer including a carbon-containing material on a top surface of the patterned photoresist layer, and etching the hard mask layer exposed by the patterned photoresist layer having the passivation layer formed thereon.

Description

Technical Field

[0001] The embodiments described herein generally relate to a film stack and an etching process for etching the film stack, which has high selectivity and good contour control for extreme ultraviolet (EUV) lithography exposure and patterning processes. Background Technology

[0002] Reliably generating submicron and smaller features is a key requirement for very large scale integration (VLSI) and ultra-large scale integration (ULSI) of semiconductor devices. However, with the continued miniaturization of circuit technology, the size and spacing of circuit features such as interconnects place additional demands on processing power. At the heart of this technology is multi-level interconnects, which require precise imaging and placement of high aspect ratio features such as vias and other interconnects. The reliable formation of these interconnects is crucial for further increasing device and interconnect density. Furthermore, it is desirable to reduce waste of intermediate materials (such as photoresist and hard mask materials) while forming submicron-sized features and interconnects.

[0003] As feature sizes shrink, the demand for higher aspect ratios (defined as the ratio of feature depth to feature width) steadily increases to 20:1 or even higher. Developing film stacking and etching processes capable of reliably forming features with such high aspect ratios is a significant challenge. However, inaccurate control or low resolution in photolithography exposure and development processes can lead to inaccurate dimensions of the photoresist layer used to transfer features in the film stack, resulting in unacceptable line width roughness (LWR). Large line width roughness (LWR) and undesirable wobble profiles of the photoresist layer caused by photolithography exposure and development processes can lead to inaccurate feature-to-film stack transfer, ultimately resulting in device failure and yield loss.

[0004] Furthermore, during the etching of the film stack, the redeposition or accumulation of byproducts or other materials generated during the etching process may build up on the top and / or sidewalls of the etched features, unintentionally blocking the openings of the features formed in the material layer. Different materials chosen for the film stack may result in different amounts or distributions of redeposited byproducts in the film stack. Additionally, as the openings of the etched features are narrowed and / or sealed by the cumulative redeposited material, reactive etchant is prevented from reaching the lower surface of the features, thus limiting the achievable aspect ratio. Moreover, the accumulation of redeposited material or byproducts may randomly and / or irregularly adhere to the top surface and / or sidewalls of the etched features, and the resulting irregular profiles and growth of the redeposited material may alter the flow path of the reactive etchant, leading to bent or distorted profiles of the features formed in the material layer. Inaccurate shape or structural dimensions may lead to device structural collapse, ultimately resulting in device failure and low product yield. Poor etch selectivity for the materials included in the film stack may lead to inaccurate profile control, ultimately resulting in device failure.

[0005] Therefore, there is a need in the art for a suitable film stack and an etching method for etching features with desired contours and small dimensions in such film stacks. Summary of the Invention

[0006] Methods for forming and etching film stacks to form high aspect ratio features within the film stacks are provided. The methods described herein facilitate contour and dimensional control of features with high aspect ratios by utilizing desired materials selected for the film stack through appropriate sidewall and bottom management schemes. In one or more embodiments, the method for etching a hard mask layer includes forming a photoresist layer comprising an organometallic material on a hard mask layer comprising a metallic material, exposing the photoresist layer to ultraviolet radiation through a mask having a selected pattern, removing unexposed areas of the photoresist layer to pattern the photoresist layer, selectively forming a passivation layer comprising a carbon-containing material on the top surface of the patterned photoresist layer, and etching the hard mask layer exposed by the patterned photoresist layer with the passivation layer formed thereon.

[0007] In other embodiments, the method for etching a film stack includes forming a bottom antireflective coating on the film stack, forming a hard mask layer containing a metal-containing material on the bottom antireflective coating, forming a photoresist layer containing an organometallic material on the hard mask layer, exposing the photoresist layer to ultraviolet radiation through a mask having a selected pattern, removing unexposed areas of the photoresist layer to pattern the photoresist layer, selectively forming a passivation layer containing a carbon-containing material on the top surface of the patterned photoresist layer, etching the hard mask layer exposed by the patterned photoresist layer with the passivation layer formed thereon to pattern the hard mask layer, etching the bottom antireflective coating exposed by the patterned hard mask layer to pattern the bottom antireflective coating, and etching the film stack exposed by the patterned bottom antireflective coating.

[0008] In some embodiments, a method for selectively forming a passivation layer on a patterned photoresist layer includes exposing the photoresist layer containing an organometallic material to ultraviolet radiation through a mask, removing unexposed areas of the photoresist layer, and selectively forming a passivation layer containing a carbon-containing material on the top surface of the photoresist layer. Attached Figure Description

[0009] To obtain and understand in detail the features of the embodiments described herein, a more specific description of the disclosure briefly summarized above can be obtained by referring to the examples shown in the accompanying drawings.

[0010] Figure 1 This is a cross-sectional view of a processing chamber according to one embodiment.

[0011] Figure 2 A flowchart illustrating a patterning process according to one embodiment is shown.

[0012] Figure 3A , Figure 3B , Figure 3C , Figure 3D , Figure 3E , Figure 3F , Figure 3G , Figure 3H and Figure 3I According to one implementation method Figure 2 The image shows a cross-sectional view of the structure formed during the patterning process.

[0013] To facilitate understanding of the embodiments, the same reference numerals are used to denote the same elements in the drawings, where possible. It is contemplated that elements and features of one embodiment may be advantageously incorporated into other embodiments without further description.

[0014] However, it should be noted that the accompanying drawings are merely exemplary examples and should not be considered as limiting its scope, as the invention recognizes other equally effective embodiments. Detailed Implementation

[0015] Methods are provided for forming film stacks and etching them to form high aspect ratio features within the film stacks. The methods described herein facilitate contour and dimensional control of features with high aspect ratios by utilizing desired materials selected for the film stack through appropriate sidewall and bottom management schemes. Specifically, the methods described herein provide a metal-containing photoresist layer having a selectively disposed carbon-containing passivation layer that exhibits high etch selectivity compared to an underlying metal-containing hard mask layer, resulting in greater precision control over the profile of the etched openings in the hard mask layer.

[0016] Figure 1 This is a cross-sectional view of an example of a processing chamber 100, which is adapted to perform a patterning process to etch a film stack having a hard mask layer made of a metallic material. Suitable processing chambers applicable to the teachings disclosed herein include, for example, those available from Applied Materials, Inc., located in Santa Clara, California. or Processing chamber. Although processing chamber 100 is shown as including several features that enable excellent etching performance, it is conceivable that other processing chambers may be adapted to benefit from one or more of the inventive features disclosed herein.

[0017] Processing chamber 100 includes a chamber body 102 and a cover 104 that enclose an internal space 106. The chamber body 102 is typically made of aluminum, stainless steel, or other suitable material. The chamber body 102 typically includes sidewalls 108 and a bottom 110. A substrate support base inlet / outlet (not shown) is typically defined in the sidewall 108 and selectively sealed by a slit valve to facilitate the entry and exit of a substrate 103 from the processing chamber 100. An exhaust port 126 is defined in the chamber body 102 and couples the internal space 106 to a pump system 128. The pump system 128 typically includes one or more pumps and throttle valves for evacuating and regulating the pressure within the internal space 106 of the processing chamber 100. In one or more embodiments, the pump system 128 maintains the pressure within the internal space 106 at an operating pressure typically between about 10 mTorr and about 500 Torr.

[0018] The cover 104 is securely supported on the side wall 108 of the chamber body 102. The cover 104 can be opened to allow excessive access to the interior space 106 of the processing chamber 100. The cover 104 includes a window 142 that facilitates optical process monitoring. In one embodiment, the window 142 is made of quartz or other suitable material that is transmissive to signals utilized by an optical monitoring system 140 mounted outside the processing chamber 100.

[0019] An optical monitoring system 140 is positioned to observe, through a window 142, at least one of the internal space 106 of the chamber body 102 and / or a substrate 103 positioned on a substrate support base assembly 148. In one or more embodiments, the optical monitoring system 140 is coupled to a cover 104 and facilitates an integrated deposition process that uses optical metrology to provide information enabling process adjustments to compensate for introduced substrate patterning inconsistencies (such as thickness) and to provide on-demand process status monitoring (such as plasma monitoring, temperature monitoring, etc.). An optical monitoring system suitable for benefiting from this invention is available from Applied Materials, Inc., Santa Clara, California. Full-spectrum interferometry module.

[0020] Gas panel 158 is coupled to processing chamber 100 to supply processing and / or cleaning gases to internal space 106. Figure 1 In the example shown, inlets 132', 132" are provided in cover 104 to allow gas to be delivered from gas panel 158 to the interior space 106 of processing chamber 100.

[0021] The nozzle assembly 130 is connected to the inner surface 114 of the cover 104. The nozzle assembly 130 includes a plurality of holes that allow gas to flow through the nozzle assembly 130 into the interior space 106 of the processing chamber 100 in a predetermined distribution that covers the entire surface of the substrate 103 being processed in the processing chamber 100.

[0022] A remote plasma source 177 is optionally coupled to a gas panel 158 to facilitate the dissociation of the gas mixture from the remote plasma prior to processing within the interior space 106. A radio frequency (RF) power source 143 is coupled to the nozzle assembly 130 via a matching network 141. The RF power source 143 is typically capable of generating up to approximately 3000 W of power at an tunable frequency ranging from approximately 50 kHz to approximately 200 MHz.

[0023] The nozzle assembly 130 additionally includes a region that transmits optical metering signals. The optical transmission region or channel 138 is adapted to allow the optical monitoring system 140 to observe the interior space 106 and / or the substrate 103 located on the substrate support base assembly 148. The channel 138 may be one or more holes formed or disposed in the nozzle assembly 130, which substantially transmits wavelengths of energy generated by and reflected back to the optical monitoring system 140. In one or more embodiments, the channel 138 includes a window 142 to prevent gas leakage through the channel 138. The window 142 may be a sapphire plate, a quartz plate, or other suitable material. Alternatively, the window 142 may be disposed in the cover 104.

[0024] In one embodiment, the nozzle assembly 130 is configured with multiple regions that allow for individual control of the gas flowing into the interior space 106 of the treatment chamber 100. Figure 1 In the example shown, the nozzle assembly 130 serves as an inner region 134 and an outer region 136, which are coupled to the gas panel 158 via separate inlets 132' and 132" respectively.

[0025] A substrate support base assembly 148 is disposed within an internal space 106 of the processing chamber 100 below the nozzle assembly 130. The substrate support base assembly 148 holds the substrate 103 during processing. The substrate support base assembly 148 typically includes a plurality of lifting pins (not shown) disposed therethrough, the lifting pins being configured to lift the substrate 103 from the substrate support base assembly 148 and facilitate the conventional exchange of the substrate 103 with a robot (not shown). A liner 118 may tightly surround the periphery of the substrate support base assembly 148.

[0026] In one embodiment, the substrate support base assembly 148 includes a mounting plate 162, a base 164, and an electrostatic chuck 166. The mounting plate 162 is coupled to the bottom 110 of the chamber body 102 and includes channels for routing utilities such as fluid, power lines, and sensor leads to the base 164 and the electrostatic chuck 166. The electrostatic chuck 166 includes at least one clamping electrode 180 for holding the substrate 103 below the nozzle assembly 130. The electrostatic chuck 166 is driven by a chuck power source 182 to generate an electrostatic force that holds the substrate 103 to the chuck surface, as is known in the art. Alternatively, the substrate 103 may be held on the substrate support base assembly 148 by clamping, vacuum, or gravity.

[0027] At least one of the base 164 or the electrostatic chuck 166 may include at least one optional embedded heater 176, at least one optional embedded isolator 174, and a plurality of conduits 168, 170 to control the lateral temperature distribution of the substrate support base assembly 148. Conduits 168, 170 are fluidly connected to a fluid source 172, allowing temperature-regulating fluid to circulate through the fluid source 172. The heater 176 is regulated by a power source 178. Conduits 168, 170 and heater 176 are used to control the temperature of the base 164, thereby heating and / or cooling the electrostatic chuck 166, and ultimately heating and / or cooling the temperature distribution of the substrate 103 disposed thereon. A plurality of temperature sensors 190, 192 may be used to monitor the temperature of the electrostatic chuck 166 and the base 164. The electrostatic chuck 166 may further include a plurality of gas channels (not shown), such as grooves, formed in the substrate support base support surface of the electrostatic chuck 166 and fluidly coupled to a heat transfer (or back-side) gas source, such as He. During operation, back gas is supplied to the gas channel at controlled pressure to enhance heat transfer between the electrostatic chuck 166 and the substrate 103.

[0028] In one embodiment, the substrate support base assembly 148 is configured as a cathode and includes clamping electrodes 180 coupled to a plurality of radio frequency bias power sources 184, 186. The radio frequency bias power sources 184, 186 are coupled between the electrodes 180 disposed in the substrate support base assembly 148 and another electrode, such as the nozzle assembly 130 or the cover 104 of the chamber body 102. The radio frequency bias power excites and sustains a plasma discharge formed by a gas disposed in a processing region of the chamber body 102.

[0029] exist Figure 1 In the illustrated example, dual radio frequency bias power sources 184 and 186 are coupled to electrodes 180 disposed in a substrate support base assembly 148 via a matching circuit 188. Signals generated by the radio frequency bias power sources 184 and 186 are transmitted to the substrate support base assembly 148 via a single feed through the matching circuit 188 to ionize the gas mixture provided in the treatment chamber 100, thereby providing the ion energy required to perform deposition or other plasma enhancement processes. The radio frequency bias power sources 184 and 186 are typically capable of generating radio frequency signals with frequencies from about 50 kHz to about 200 MHz and powers from about 0 W to about 8000 W, such as from about 1 W to about 5000 W. An additional bias power source 189 may be coupled to electrodes 180 to control plasma characteristics.

[0030] During operation, substrate 103 is disposed on substrate support base assembly 148 within processing chamber 100. Processing gas and / or gas mixture is introduced into chamber body 102 from gas panel 158 via nozzle assembly 130. Pump system 128 maintains pressure within chamber body 102 while removing deposited byproducts.

[0031] Controller 150 is coupled to processing chamber 100 to control its operation. Controller 150 includes a central processing unit (CPU) 152, memory 154, and support circuitry 156 for controlling the processing sequence and regulating airflow from gas panel 158. CPU 152 can be any type of general-purpose computer processor suitable for industrial environments. Software routines can be stored in memory 154, such as random access memory, read-only memory, floppy disk or hard disk, or other forms of digital storage. Support circuitry 156 is conventionally coupled to CPU 152 and may include cache, clock circuitry, input / output systems, power sources, etc. Bidirectional communication between controller 150 and various components of processing chamber 100 is handled via numerous signal cables.

[0032] Figure 2 This is a flowchart of a patterning process method 200 according to one embodiment described herein. Figures 3A to 3I Is Figure 2 A cross-sectional view of structure 300 formed during a patterning process. Method 200 can be used to form features with desired critical dimensions and contours, such as trenches, vias, openings, etc. In some embodiments, the dimensions of such features are between about 14 nanometers and about 22 nanometers, such as about 18 nanometers. Structure 300 can be used for gate structures, contact structures, or interconnect structures in front-end or back-end processes. Alternatively, method 200 can be advantageously used to etch other types of structures. Those skilled in the art will recognize that the complete process for forming semiconductor devices and related structures is not shown in the figures or described herein. Although various operations are shown in the figures and described herein, no limitation is implied regarding the order of the operations or the presence or absence of the operations. Operations illustrated or described in sequence are for illustrative purposes only and do not preclude the possibility that the individual operations are actually performed at least partially (if not entirely) in parallel or overlapping manner.

[0033] Method 200 involves processing a chamber (such as...) Figure 1 In the processing chamber 100 shown, membrane stack 302 is transferred or provided, as... Figure 3AThe diagram begins at operation 210. In one embodiment, the film stack 302 may have multiple layers vertically stacked on a substrate. The film stack 302 may include one or more metal-containing dielectric layers and one or more silicon-containing dielectric layers. In some embodiments, the metal-containing dielectric layers may be formed of a high-dielectric-constant material with a dielectric constant greater than 4. Suitable examples of high-dielectric-constant materials include alumina (Al2O3), tantalum oxide (Ta2O5), tantalum nitride (TaN), and tantalum oxynitride (TaN2O5). x O y ,0≦x,y≦1), titanium oxide (TiO2), titanium nitride (TiN), zirconium dioxide (ZrO2), hafnium dioxide (HfO2), hafnium silicon oxide (HfSiO4), lanthanum oxide (La2O3), yttrium oxide (Y2O3), strontium titanate (SrTiO3), barium strontium titanate (BST, BaSrTiO3), bismuth-doped strontium titanate (Bi:SrTiO3), and lead zirconate titanate (PZT, Pb[Zr x Ti 1-x [O3, 0≦x≦1), etc. Silicon-containing dielectric layers can be made of silicon oxide (SiO2), silicon nitride (SiN), silicon oxynitride (SiON), silicon carbide (SiC), silicon oxycarbide (SiO2), etc. x C y , 0≦x,y≦1) etc. are formed.

[0034] The substrate can be any of a semiconductor substrate, a silicon wafer, a glass substrate, etc. The substrate can be formed from materials such as crystalline silicon (e.g., Si). <100> or Si <111> Substrates include silicon oxide, strained silicon, silicon-germanium, germanium, doped or undoped polycrystalline silicon, doped or undoped silicon wafers and patterned or unpatterned silicon on-insulator (SOI), carbon-doped silicon oxide, silicon nitride, doped silicon, germanium, gallium arsenide, glass, or sapphire. Substrates can be of various sizes, such as 200 mm, 300 mm, 450 mm, or other diameters, and can also be rectangular or square panels.

[0035] In operation 220, a bottom anti-reflective coating (BARC layer) 304 is formed on the film stack 302, such as... Figure 3A As shown. In some embodiments, the bottom antireflective coating 304 is made of a carbon-containing material, such as boron-doped amorphous carbon. The bottom antireflective coating 304 may be Saphira, manufactured by Applied Materials Inc. in Santa Clara, California. TMAdvanced Patterning Film (APF) Carbon Hard Mask. In some embodiments, the bottom anti-reflective coating 304 is a high-density carbon layer with excellent film quality, such as improved hardness and density. This hardness and density allow the bottom anti-reflective coating 304 to act as a stronger barrier against metal penetration and to prevent and reduce nanodefects to a greater extent than conventional spin-on carbon (SOC) hard masks.

[0036] The bottom anti-reflective coating 304 can be formed by physical vapor deposition (PVD), plasma-enhanced chemical vapor deposition (PECVD), or other suitable deposition processes. In one embodiment, the bottom anti-reflective coating 304 is a diamond-like carbon layer formed by chemical vapor deposition (CVD) (plasma-enhanced and / or thermal) of a hydrocarbon gas mixture, the hydrocarbon gas mixture including precursors such as C2H2, C3H6, CH4, C4H8, 1,3-dimethyladamantane, bicyclo[2.2.1]hept-2,5-diene (2,5-norbornene), adamantane (C 10 H 16 norbornene (C7H) 10 The deposition process can be performed in a temperature range of -50°C to 600°C. The deposition process can be performed within the internal space 106 of the processing chamber 100 at a pressure range of 0.1 mTorr to 10 Torr. The hydrocarbon gas mixture may further include a carrier gas, such as helium, argon, xenon, nitrogen, hydrogen, or a combination thereof; and an etching gas, such as Cl2, CF4, NF3, or a combination thereof, to improve film quality. Plasma (e.g., capacitively coupled plasma) may be formed by top and bottom electrodes or side electrodes of the processing chamber 100. Electrodes may be formed by single-powered electrodes, dual-powered electrodes, or more multi-frequency electrodes, such as, but not limited to, 350 kHz, 2 MHz, 13.56 MHz, 27 MHz, 40 MHz, 60 MHz, and 100 MHz, with multiple frequencies used alternately or simultaneously in the chemical vapor deposition system.

[0037] In operation 230, a hard mask layer 306 is formed on the bottom anti-reflective coating 304, such as Figure 3BAs shown. The hard mask layer 306 may be a metal oxide layer. The material selected for the hard mask layer 306 can affect the reflection and / or absorption efficiency of extreme ultraviolet (EUV) radiation with wavelengths between about 5 nm and about 20 nm (e.g., about 13.5 nm) during the photolithography process. Therefore, by appropriately selecting the material for the hard mask layer 306, the performance of the EUV photolithography process can be improved, such as high lithographic resolution, defect reduction, photoresist layer contour control, energy dose reduction, and / or line edge roughness reduction. For example, materials with higher metal concentrations can provide higher EUV radiation absorption coefficients, so the hard mask layer 306 may be formed of a metal-containing material, such as a metal dielectric layer containing one or more metal elements with atomic numbers greater than 28, such as 29-32, 37-51, and 55-83. Suitable metal elements include tin (Sn), tantalum (Ta), indium (In), gallium (Ga), zinc (Zn), zirconium (Zr), aluminum (Al), or combinations thereof. Furthermore, low concentrations of silicon dopants and / or oxygen in the metallic material can further increase free carriers, thereby improving the absorption coefficient of extreme ultraviolet radiation and reducing the likelihood of defect formation. Suitable examples of metallic materials for the hard mask layer 306 may be tin oxide (SnO), silicon tin oxide (SnSiO), tantalum oxide (TaO), indium tin oxide (InSnO), indium gallium zinc oxide (IGZO), one or more alloys of the above, one or more dopants of the above, or any combination thereof, wherein the ratio of metal to silicon or oxygen (metal:silicon / oxygen) is between about 80:1 / 19 and about 90:1 / 9. The metallic material for the hard mask layer 306 can have a concentration greater than 1 × 10⁻⁶ under extreme ultraviolet radiation in the wavelength range of about 5 nm to about 20 nm. 5 (cm 2 The extreme ultraviolet absorption cross-section is approximately [value missing]. In one or more instances, the thickness of the hard mask layer 306 is approximately [value missing]. With the agreement Between, for example, in about With the agreement Between, for example, in about With the agreement between.

[0038] In some embodiments, the hard mask layer 306 comprises multiple layers. The hard mask layer 306 may have multiple layers formed of different metal-containing materials. The selection of the metal-containing materials for the multiple layers is based on the different absorption coefficients of the metal-containing materials. For example, multiple layers with absorption coefficients ranging from high to low, from low to high, or alternating between high and low may be formed sequentially to enhance the reflection of extreme ultraviolet radiation during the photolithography exposure process. In one or more instances, the metal element selected for one of the multiple layers may have an atomic number greater than 28, such as greater than 35, while another metal element may have an atomic number less than 28.

[0039] In some embodiments, the hard mask layer 306 includes a dual-layer structure having a first portion (e.g., an upper portion or upper layer) and a second portion (e.g., a lower portion or lower layer). The first portion contains metallic elements with atomic numbers greater than 28, such as metallic elements with atomic numbers 29-32, 37-51, and 55-83. The second portion contains elements with atomic numbers less than 28, such as elements with atomic numbers 3-8, 11-16, and 19-27.

[0040] In some embodiments, the hard mask is formed as a gradient in the ratio of metal elements to silicon and / or oxygen elements in the hard mask layer 306 to provide different absorption coefficients along the entire bulk of the hard mask layer 306. For example, the metal element concentration of the hard mask layer 306 may gradually increase or decrease with increasing thickness of the hard mask layer 306. Alternatively, each layer of the bilayer structure or multiple layers of the hard mask layer 306 may also be gradient layers. For example, in the bilayer structure of the hard mask layer 306, the upper part of the hard mask layer 306 may have a low resistivity or even a pure metal layer (e.g., a tin layer) with a relatively high metal element concentration, while the lower part of the hard mask layer 306 may have a high concentration of silicon and / or oxygen.

[0041] The hard mask layer 306 can be formed by chemical vapor deposition, physical vapor deposition, atomic layer deposition (ALD), spin coating, spray coating, or other suitable deposition processes. In some embodiments, a carrier gas and / or an inert gas with a relatively high atomic weight, such as xenon or krypton, can be used during the plasma-enhanced chemical vapor deposition or physical vapor deposition process to form the hard mask layer 306. The temperature controlled during the formation of the hard mask layer 306 can be controlled between -50 degrees Celsius and about 250 degrees Celsius. It is believed that relatively low temperature control, for example below 250 degrees Celsius, can help to form the hard mask layer 306 at a relatively low deposition rate, resulting in a relatively smooth film surface.

[0042] In operation 240, the photoresist layer 308 is formed on the hard mask layer 306, such as Figure 3CAs shown. In the embodiments described herein, the photoresist layer 308 is formed of an organometallic material including organic ligands. The organometallic material layer may be formed of a polymeric metal-side oxygen / hydroxyl network, wherein the metal and the side oxygen ligands (O 2- ) and hydroxyl ligands (OH) - It is bonded to organic ligands, or to polynuclear metal side oxygen / hydroxyl species with organic ligands.

[0043] The photoresist layer 308 can be formed by using a precursor solution containing a metal-side-oxygen cation with organic ligands in an organic solvent, via chemical vapor deposition, physical vapor deposition, atomic layer deposition, spin coating, spray coating, or other suitable deposition processes. Metal (M)-side-oxygen cations refer herein to one or more metal (M) ions that combine with oxygen atoms (O) to form side-oxygen ligands (O). 2- ) and / or hydroxyl ligands (OH) - ) and release hydrogen ions (H+) in aqueous solution. - The metal (M)-side oxygen-hydroxy cation is further bonded to an organic ligand, forming one or more metal-carbon (MC) ligand bonds and / or metal-carboxylate (M-O₂C) ligand bonds. Suitable metals (M) for forming the metal-side oxygen / hydroxy cation include Group 13, 14, and 15 metals, such as tin (Sn), antimony (Sb), and indium (In). Additional metals, such as titanium, zirconium, hafnium, vanadium, cobalt, molybdenum, tungsten, aluminum, gallium, silicon, germanium, phosphorus, arsenic, yttrium, lanthanum, cerium, lutetium, or combinations thereof, can be mixed in the precursor solution to produce more complex polynuclear metal-side oxygen / hydroxy cations (i.e., those comprising two or more metal atoms). The additional metals can be substitutes or additions to tin (Sn), antimony (Sb), and / or indium (In). If a mixture of metal ions is used, in one example, the molar ratio of non-tin / antimony / indium ions to tin / antimony / indium metal ions is as high as about 1, and in other examples, it is between about 0.1 and about 0.75. In some embodiments, tin (Sn) or indium (In) is used in the precursor solution to form a photoresist layer that exhibits strong absorption of extreme ultraviolet radiation at a wavelength of 13.5 nm, and, in combination with an organic ligand, good absorption of ultraviolet radiation at a wavelength of 193 nm. In some embodiments, Hf is used to provide electron beam material and good absorption of extreme ultraviolet radiation. In some embodiments, one or more metal compositions comprising titanium, vanadium, molybdenum, tungsten, or combinations thereof are added to shift the absorption edge to a longer wavelength, thereby providing sensitivity to ultraviolet radiation at a wavelength of 248 nm.

[0044] The organic ligand may be, for example, alkyl (e.g., methyl, ethyl, propyl, butyl, tributyl, aryl (phenyl, benzyl)), alkenyl (e.g., vinyl, allyl), and carboxylic acid esters (e.g., acetate, propionate, benzoyl butyrate). In one embodiment, the ratio of the concentration of the organic ligand to the concentration of the metal-side oxygen-hydroxy cation in the precursor solution is between about 0.25 and about 4, in another embodiment between about 0.5 and about 3.5, in yet another embodiment between about 0.75 and about 3, and in still another embodiment between about 1 and about 2.75. Those skilled in the art will recognize that additional ranges of organic ligand concentrations within the aforementioned defined ranges are conceivable, which are consistent with this disclosure.

[0045] The organic solvent may be an alcohol, an ester, or a combination thereof. In some embodiments, the organic solvent includes aromatic compounds (e.g., xylene, toluene), esters (propylene glycol monomethyl ether acetate, ethyl acetate, ethyl lactate), alcohols (e.g., 4-methyl-2-pentanol, 1-butanol, anisole), ketones (e.g., methyl ethyl ketone), etc.

[0046] In some embodiments, the thickness of the deposited photoresist layer 308 is between about 1 nanometer and about 1 micrometer, for example, between about 8 nanometers and about 13 nanometers.

[0047] In operation 250, the photoresist layer 308 is exposed to radiation according to a selected pattern, which includes features such as trenches, vias, and openings, as well as the desired critical dimensions and contours to be formed in the film stack 302. Figure 3D As shown, a selected pattern is transferred to a corresponding pattern or latent image in the photoresist layer 308, which has irradiated and unirradiated areas. When exposed to radiation, the photoresist layer 308 absorbs radiation energy generated in the irradiated area that breaks the bonds between the metal and organic ligands (i.e., metal-carbon ligand bonds and / or metal-carboxylate ligand bonds). This bond breaking can lead to compositional changes in the irradiated area of ​​the photoresist layer 308, either by forming metal hydroxide (M-OH) ligand bonds or by forming metal-oxygen (MOM) ligand bonds through condensation.

[0048] When sufficient radiation is absorbed, there is a contrast in material properties between the irradiated regions of the photoresist layer 308 with no or substantially no organic ligands and the unirradiated regions of the photoresist layer 308 with intact organic ligands. For example, the unirradiated regions of the photoresist layer 308 with organic ligands are relatively hydrophobic, while the irradiated regions of the photoresist layer 308 without organic ligands are less hydrophobic (i.e., more hydrophilic) than the unirradiated regions of the photoresist layer 308. Using this contrast, the photoresist layer 308 can be patterned with both positive and negative tones (where the irradiated regions become soluble in the developer) using a suitable developer.

[0049] The radiation can be electromagnetic radiation, an electron beam, or other suitable radiation. The radiation can be directed through mask 310 to the photoresist layer 308, or the radiation beam can be controllably scanned across the entire photoresist layer 308. The electromagnetic radiation can have a desired wavelength or wavelength range, such as visible light radiation, ultraviolet radiation (between 100 nm and 400 nm, including extreme ultraviolet between 10 nm and 121 nm and far ultraviolet between 122 nm and 200 nm), or x-ray radiation (soft x-rays between 0.1 nm and 10 nm), depending on the desired spatial resolution of the patterned underlying film stack 302. Higher resolution patterning can be obtained using shorter wavelength radiation, such as ultraviolet radiation, x-ray radiation, or an electron beam. For example, extreme ultraviolet radiation generated by a xenon or tin plasma source excited using a high-energy laser or discharge pulse can be used for 13.5 nm lithography.

[0050] In some implementations, contrast can be enhanced by post-irradiation heat treatment.

[0051] In operation 260, the photoresist layer 308 is developed to pattern the photoresist layer 308 according to a selected pattern, such as... Figure 3E As shown. The patterned photoresist layer 308A defines an opening 312, which exposes the surface 314 of the underlying hard mask layer 306 for etching.

[0052] The developer is used to develop the irradiated photoresist layer 308 and remove the unirradiated areas of the photoresist layer 308 (i.e., negative-tone patterning) to form a patterned photoresist layer 308A. The developer may include an organic solvent, such as the solvent used in the precursor solution. In some embodiments, suitable developers include aromatic compounds (e.g., benzene, xylene, toluene), esters (e.g., propylene glycol monomethyl acetate, ethyl acetate, ethyl lactate, n-butyl acetate, butyrolactone), alcohols (e.g., 4-methyl-2-pentanol, 1-butanol, isopropanol, anisole), ketones (e.g., methyl ethyl ketone, acetone, cyclohexanone), ethers (e.g., tetrahydrofuran, dioxane), etc. In one example, development is performed for about 5 seconds to about 30 minutes; in another example, it is performed for about 8 seconds to about 15 minutes; and for about 10 seconds to about 10 minutes.

[0053] In some embodiments, the developer may include additional components to enhance the developing process, such as improving contrast, sensitivity, and linewidth roughness, and inhibiting the formation and precipitation of metal oxide particles. Suitable additives include, for example, certain dissolving salts containing cations selected from the group consisting of ammonium, d-block metal cations (hafnium, zirconium, lanthanum, etc.), f-block metal cations (cerium, lutetium, etc.), p-block metal cations (aluminum, tin, etc.), alkali metals (lithium, sodium, potassium, etc.), and combinations thereof, and anions selected from the group consisting of fluorides, chlorides, bromides, iodides, nitrates, sulfates, phosphates, silicates, borates, peroxides, butoxides, formates, ethylenediaminetetraacetic acid (EDTA), tungstates, molybdates, and combinations thereof. Other potentially useful additives include, for example, molecular chelating agents such as polyamines, alkanolamines, amino acids, or combinations thereof. If optional additives are present, in one embodiment the developer may include no more than about 10% by weight of the additive, and in another embodiment no more than about 5% by weight of the additive. Those skilled in the art will recognize that additional ranges of additive concentrations within the clearly defined ranges described above are conceivable and consistent with the present disclosure.

[0054] The developer can be applied to the irradiated photoresist layer 308 using spin coating, spray coating, or other suitable coating processes. In some embodiments, spin cleaning and / or drying can be performed to complete the development process. Suitable cleaning solutions include ultrapure water, methanol, ethanol, propanol, and combinations thereof.

[0055] In some embodiments, the patterned photoresist layer 308A may be processed to further condense the material and further dehydrate the material. In some embodiments, the patterned photoresist layer 308A may be heated to a temperature between about 100 degrees Celsius and about 600 degrees Celsius in one instance, to a temperature between about 175 degrees Celsius and about 500 degrees Celsius in another instance, and to a temperature between about 200 degrees Celsius and about 400 degrees Celsius in still other instances. In one instance, heating may be performed for at least about 1 minute, in another instance for about 2 minutes to about 1 hour, and in still other instances for about 2.5 minutes to about 25 minutes. Heating may be performed in an air, vacuum, or inert gas environment, such as argon or nitrogen. Those skilled in the art will recognize that additional temperature and time ranges within the above-described well-defined ranges are conceivable and consistent with this disclosure.

[0056] In some embodiments, the average spacing between adjacent linear segments of adjacent structures does not exceed about 60 nanometers, in some embodiments it does not exceed about 50 nanometers, and in many embodiments it does not exceed about 40 nanometers.

[0057] In operation 270, before etching the hard mask layer 306, a passivation layer 316 is selectively formed on the patterned photoresist layer 308A, such as... Figure 3F As shown. The passivation layer 316 can be formed from a carbon-containing material by supplying a deposition gas mixture in situ onto the patterned photoresist layer in a physical vapor deposition chamber or an etching chamber. In the embodiments described herein, the passivation layer 316 is formed primarily on the top surface 318 of the patterned photoresist layer 308A, rather than on the sidewalls 320 of the patterned photoresist layer 308A or the exposed surface 314 of the hard mask layer 306. Therefore, the contour (e.g., size and geometry) of the opening 312 defined by the patterned photoresist layer 308A remains unchanged, so that the opening 312 can be transferred to the hard mask layer 306 without contour alternation.

[0058] While not wishing to be bound by theory, it is believed that carbon atoms bond to the top surface 318 (i.e., the irradiated area) of the photoresist layer 308, due to the breaking of bonds between the metal and organic ligands (i.e., metal-carbon (MC) ligand bonds and / or metal-carboxylate (M-O2C) ligand bonds), resulting in metal hydroxide (M-OH) and metal-oxygen (MOM) ligand bonds on the top surface. The sidewalls 320 of the patterned photoresist layer 308A retain the composition of the unirradiated photoresist layer 308 with intact organic ligands, and therefore do not contain carbon-bondable metal hydroxide (M-OH) and metal-oxygen (MOM) ligand bonds. The exposed surface 314 of the hard mask layer 306 also does not contain metal hydroxide (M-OH) and metal-oxygen (MOM) ligand bonds, therefore carbon atoms are not bonded to the exposed surface 314 of the hard mask layer 306.

[0059] In one or more embodiments, the deposition gas mixture includes a carbon-containing gas, such as carbon monoxide or methane. As described above, the hard mask layer 306 is formed of a material containing a metallic element, such as tin (Sn), and the photoresist layer 308 is also formed of a material containing a metallic element, such as tin (Sn), resulting in poor etch selectivity between the hard mask layer 306 and the photoresist layer 308. Therefore, if the hard mask layer 306 on which the photoresist layer 308 is disposed is etched, the contour control of the etched openings in the hard mask layer 306 may be inaccurate, ultimately leading to device failure. If a passivation layer 316 is disposed thereon, the patterned photoresist layer 308B can have higher etch selectivity than the hard mask layer 306, thereby allowing for more accurate control of the etched opening contours in the hard mask layer 306.

[0060] In operation 280, the hard mask layer 306 is etched to transfer the opening 312 of the patterned photoresist layer 308A to the hard mask layer 306, as shown. Figure 3GAs shown. A patterned hard mask layer 306A defines an opening 322 that exposes the surface 324 of the underlying bottom anti-reflective coating 304 for etching. In one or more embodiments, the etching process is performed in operation 280 by supplying an etching gas mixture into the processing chamber 100 while maintaining the temperature of the substrate support pedestal assembly 148 at room temperature (e.g., about 23 degrees Celsius) and up to about 150 degrees Celsius.

[0061] In some instances, the etching gas mixture includes at least one halogen-containing gas. Halogen-containing gases may include fluorine-containing, chlorine-containing, or bromine-containing gases. Suitable examples of halogen-containing gases include SF6, SiCl4, Si2Cl6, NF3, HBr, Br2, CHF3, CH2F2, CF4, C2F, C4F6, C3F8, HCl, C4F8, Cl2, HF, CCl4, CHCl3, CH2Cl2, and CH3Cl. In some instances, silicon-containing gases may also be supplied in the etching gas mixture. Suitable examples of silicon-containing gases include SiCl4, Si2Cl6, SiH4, Si2H6, etc. Furthermore, specifically, examples of chlorine-containing gases include HCl, Cl2, CCl4, CHCl3, CH2Cl2, CH3Cl, SiCl4, Si2Cl6, etc., and examples of bromine-containing gases include HBr, Br2, etc. If necessary, reactive gases, such as oxygen-containing gases or nitrogen-containing gases, such as O2, N2, N2O, NO2, O3, H2O, etc., can also be provided in the etching gas mixture.

[0062] In one or more instances, the halogen-containing gas used to etch the hard mask layer 306 includes a chlorine-containing gas or a bromine-containing gas. When the etching gas mixture is supplied to the processing chamber, an inert gas may optionally be supplied to the etching gas mixture to assist in contour control as needed. Examples of inert gases supplied to the gas mixture include argon, helium, neon, krypton, xenon, etc. In a particular instance, the etching gas mixture used to etch the hard mask layer 306, such as that containing a metallic material (e.g., a tin / tin oxide / tin oxide silicon layer), includes hydrogen bromide, chlorine, argon, helium, or a combination thereof.

[0063] During etching, the chamber pressure of the etching gas mixture is also regulated. In one or more embodiments, the processing pressure in the plasma processing chamber is regulated between about 2 mTorr and about 100 mTorr, for example, between about 3 mTorr and 20 mTorr, for example, about 6 mTorr. If necessary, in the presence of the etching gas mixture, a radio frequency source or bias power can be applied to maintain the plasma formed in continuous or pulsed modes. For example, a radio frequency power source with a frequency of about 13.56 MHz can be applied at an energy level between about 200 W and about 1000 W, for example, about 500 W, to an inductively coupled antenna source to maintain the plasma in the etching chamber. Furthermore, a radio frequency bias power with a frequency between about 2 MHz and about 13.56 MHz can be applied at less than 500 W, for example, between about 0 W and about 450 W, for example, about 150 W.

[0064] In one or more instances, during etching in operation 280, the radio frequency (RF) bias power and RF power source can be pulsed in processing chamber 100. The RF bias power and RF power source can be pulsed synchronously or asynchronously into the processing chamber. In some instances, the RF bias power and RF power source are pulsed asynchronously into the processing chamber. For example, the RF power source may be pulsed into the processing chamber before the pulsed RF bias power. For example, the RF bias power may be in a pulsed mode synchronized with the RF power source, or with a time delay relative to the RF power source. In one or more instances, the RF power source and RF bias power are pulsed between approximately 5% and approximately 75% of each duty cycle. For example, each duty cycle between each time unit is between approximately 0.1 milliseconds and approximately 10 milliseconds.

[0065] In one example of operating the etching gas mixture supplied at position 280, oxygen can be supplied into the chamber at a rate between about 0 sccm and about 50 sccm. Halogen-containing gases such as HBr can be supplied at a flow rate between about 25 sccm and about 250 sccm, for example, about 100 sccm.

[0066] In operation 290, the bottom anti-reflective coating 304 is etched to transfer the opening 322 in the patterned hard mask 360A to the bottom anti-reflective coating 304, as... Figure 3HAs shown. The patterned bottom antireflective coating 304A defines an opening 326 that exposes the surface 328 of the underlying film stack 302. The etching gas mixture used in operation 290 to etch the bottom antireflective coating 304 may be the same as the etching gas mixture used in operation 280 to etch the hard mask layer 306. Alternatively, the etching gas mixture used in operation 290 to etch the bottom antireflective coating 304 may be different from the etching gas mixture used in operation 280 to etch the hard mask layer 306. In one or more instances, the etching gas mixture used in operation 290 to etch the bottom antireflective coating 304 may include a chlorine-containing gas, such as hydrogen chloride or chlorine.

[0067] After forming the opening 326 in the bottom anti-reflective coating 304, a scum removal or stripping process can be performed to remove the remaining passivation layer 316 (if any), such as Figure 3I As shown. Note that further etching or patterning processes may be performed to continue transferring the opening 326 into the film stack 302 and to form a selected pattern within the film stack 302 including features such as trenches, vias, openings, etc., which have desired critical dimensions and profiles.

[0068] In the embodiments described herein, a method for forming a metal-containing photoresist layer having a selectively disposed carbon-containing passivation layer thereon, the carbon-containing passivation layer exhibiting high etch selectivity for an underlying metal-containing hard mask layer, thereby resulting in more accurate control over the etched opening profile in the hard mask layer. Therefore, photolithographic exposure accuracy can be improved, such as high resolution, low energy dose, good photoresist profile control, and low line edge roughness.

[0069] Despite the foregoing embodiments relating to this disclosure, other and further embodiments may be devised without departing from its essential scope, the scope of which is determined by the appended claims. All documents described herein are incorporated by reference, including any prior art and / or test procedures inconsistent with this document. It will be apparent from the general description and detailed description above that, although the form of this disclosure has been illustrated and described, various modifications may be made without departing from the spirit and scope of this disclosure. Therefore, this is not intended to limit the disclosure. Similarly, for the purposes of U.S. law, the term “comprising” is considered synonymous with the term “including.” Likewise, whenever a component, element, or group of elements is preceded by the transitional phrase “comprising,” it should be understood that a group of the same components or elements, preceded by the transitional phrases “substantially constitutes…,” “consisting of…,” “selected from…,” or “is…,” is also contemplated before the description of the component, element, or multiple elements, and vice versa.

[0070] This application has described certain embodiments and features using a set of upper and lower numerical limits. It should be understood that, unless otherwise stated, a range including any combination of two values ​​is contemplated, such as any combination of a lower value and any higher value, any combination of two lower values, and / or any combination of two higher values. Certain lower, upper, and range limits appear in one or more of the following claims.

Claims

1. A method for etching a hard mask layer, comprising the following steps: A photoresist layer containing an organometallic material is formed on a hard mask layer containing a metallic material; By exposing the photoresist layer to ultraviolet radiation using a mask with a selected pattern, irradiated and unirradiated areas of the photoresist layer are created. Remove the irradiated or unirradiated areas of the photoresist layer to pattern the photoresist layer; A passivation layer containing carbon-containing material is selectively formed on the top surface of the patterned photoresist layer; and Etching exposes the hard mask layer by removing the patterned photoresist layer on which the passivation layer is formed.

2. The method of claim 1, wherein the organometallic material comprises one or more metal elements and organic ligands.

3. The method of claim 2, wherein the one or more metallic elements include tin (Sn).

4. The method of claim 2, wherein the organic ligand is selected from the group consisting of alkyl, alkenyl and carboxyl groups.

5. The method of claim 1, wherein the step of forming the passivation layer comprises the following steps: A deposition gas containing a gas selected from the group consisting of CO and CH4 is supplied onto the patterned photoresist layer.

6. A method for etching film stacks, comprising the following steps: A bottom anti-reflective coating is formed on the film stack; A hard mask layer containing a metallic material is formed on the bottom anti-reflective coating; A photoresist layer containing an organometallic material is formed on the hard mask layer; By exposing the photoresist layer to ultraviolet radiation using a mask with a selected pattern, irradiated and unirradiated areas of the photoresist layer are created. Remove the irradiated or unirradiated areas of the photoresist layer to pattern the photoresist layer; A passivation layer containing carbon-containing material is selectively formed on the top surface of the patterned photoresist layer; Etching the hard mask layer to expose the irradiated or unirradiated area by removing the patterned photoresist layer on which the passivation layer is formed; The bottom anti-reflective coating exposed by the patterned hard mask layer is etched to pattern the bottom anti-reflective coating; and The film stack is etched to expose the patterned bottom anti-reflective coating.

7. The method of claim 6, wherein the organometallic material comprises one or more metal elements and organic ligands.

8. The method of claim 7, wherein the one or more metallic elements include tin (Sn).

9. The method of claim 7, wherein the organic ligand is selected from the group consisting of alkyl, alkenyl and carboxyl groups.

10. The method of claim 6, wherein the step of forming the passivation layer comprises the following steps: A deposition gas containing a gas selected from the group consisting of CO and CH4 is supplied to the patterned photoresist layer.

11. The method of claim 6, wherein the metal-containing material of the hard mask layer comprises tin (Sn).

12. The method of claim 11, wherein the metal-containing material of the hard mask layer is selected from the group consisting of tin oxide (SnO), silicon tin oxide (SnSiO), indium tin oxide (InSnO), and any combination thereof.

13. The method of claim 6, wherein the bottom antireflective coating comprises a carbon-containing material.

14. A method for selectively forming a passivation layer on a patterned photoresist layer, comprising the following steps: By using a mask to expose a photoresist layer containing an organometallic material to ultraviolet radiation, an irradiated area and an unirradiated area of ​​the photoresist layer are created. Remove the irradiated area or the unirradiated area of ​​the photoresist layer; and A passivation layer containing carbon-containing material is selectively formed on the top surface of the photoresist layer.

15. The method of claim 14, wherein the organometallic material comprises one or more metal elements and organic ligands.

16. The method of claim 15, wherein the one or more metallic elements include tin (Sn).

17. The method of claim 15, wherein the one or more metallic elements are selected from the group consisting of tin (Sn), antimony (Sb) and indium (In) and any combination thereof.

18. The method of claim 15, wherein the organic ligand is selected from the group consisting of alkyl, alkenyl and carboxyl groups.

19. The method of claim 14, further comprising the following steps: The patterned photoresist layer is heated.

20. The method of claim 14, wherein the step of forming the passivation layer comprises the following steps: A deposition gas containing a gas selected from the group consisting of CO and CH4 is supplied onto the patterned photoresist layer.

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