Selective deposition of carbon onto photoresist layers in lithography applications

Abstract

A method for 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 light through a mask having a selected pattern, removing unexposed areas of the photoresist layer to pattern the photoresist layer, selectively forming a passivation layer including a carbon-containing material on top of the patterned photoresist layer, and etching the hard mask layer exposed by the patterned photoresist layer with the passivation layer formed thereon.

Description

[Technical Field]

[0001] FIELD OF THE INVENTION

[0001] Embodiments herein generally relate to film stacks and etching processes for etching such film stacks with high selectivity and good profile control for extreme ultraviolet (EUV) lithography exposure and patterning processes. [Background technology]

[0002]

[0002] Reliable fabrication of submicron features is one of the key requirements for very large-scale integration (VLSI) and ultra-large-scale integration (ULSI) of semiconductor devices. However, as circuit technology continues to shrink, the size and pitch of circuit features, such as interconnects, place ever-increasing demands on processing power. Multilayer interconnects, which are central to this technology, require accurate imaging and placement of high-aspect-ratio features, such as vias and other interconnects. Reliable formation of these interconnects is critical to further increasing device and interconnect densities. It is also desirable to reduce waste of intermediate materials, such as resist and hard mask materials, while forming submicron-sized features and interconnects.

[0003] As feature sizes decrease, the demand for high aspect ratios, defined as the ratio between feature depth and feature width, has steadily increased to 20:1 and beyond. Developing film stacks and etching processes that can reliably form such high aspect ratio features presents significant challenges. However, imprecise control or poor resolution of lithographic exposure and development processes can result in inaccurate dimensions in the photoresist layer used to transfer features into the film stack, resulting in unacceptable line width roughness (LWR). High line width roughness (LWR) and undesirable waviness in the photoresist layer caused by the lithographic exposure and development processes can cause inaccurate feature transfer into the film stack, ultimately resulting in device failure and reduced yield.

[0004] Furthermore, during etching of a film stack, redeposition or accumulation of by-products or other materials generated during the etching process can accumulate on the top and / or sidewalls of the features being etched, thereby undesirably blocking the openings of the features formed in the material layer. Different materials selected for the film stack can result in different amounts or profiles of redeposited by-products in the film stack. Furthermore, the openings of the etched features can be narrowed and / or sealed by the accumulation of redeposited material, preventing the reactive etchant from reaching the underside of the feature, thus limiting the aspect ratios that can be achieved. Furthermore, the accumulation of redeposited material or by-products can adhere randomly and / or irregularly to the top and / or sidewalls of the features being etched, and the resulting irregular profile and growth of redeposited material can alter the flow path of the reactive etchant, thus resulting in bowed or twisted profiles of the features formed in the material layer. Inaccurate profiles and feature dimensions can cause the device structure to collapse, ultimately leading to device failure and reduced product yield. Poor etch selectivity to materials contained in the film stack can lead to undesirably inaccurate profile control and ultimately device failure.

[0005]

[0005] Accordingly, there is a need in the art for suitable film stacks and etching methods for etching features having desired profiles and small dimensions in such film stacks. Summary of the Invention

[0006]

[0006] Methods for forming a film stack and etching it to form high aspect ratio features in the film stack are provided. The methods described herein facilitate profile and dimensional control of high aspect ratio features through appropriate sidewall and bottom management schemes using desired materials selected for the film stack. In one or more embodiments, a method for etching a hard mask layer includes forming a photoresist layer comprising an organometallic material on a hard mask layer comprising a metal-containing material, exposing the photoresist layer to ultraviolet light 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 top of the patterned photoresist layer, and etching the hard mask layer exposed by the patterned photoresist layer on which the passivation layer is formed.

[0007]

[0007] In another embodiment, a method for etching a film stack includes forming a bottom antireflective coating layer on the film stack, forming a hard mask layer comprising a metal-containing material on the bottom antireflective coating layer, forming a photoresist layer comprising an organometallic material on the hard mask layer, exposing the photoresist layer to ultraviolet light 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 top of the patterned photoresist layer, etching the hard mask layer exposed by the patterned photoresist layer on which the passivation layer is formed to pattern the hard mask layer, etching the bottom antireflective coating layer exposed by the patterned hard mask layer to pattern the bottom antireflective coating layer, and etching the film stack exposed by the patterned bottom antireflective coating layer.

[0008]

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

[0009]

[0009] In order that the features of the embodiments of the present specification described above may be realized and understood in detail, the present disclosure summarized above will be more particularly described with reference to examples thereof illustrated in the accompanying drawings. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view of a processing chamber according to one embodiment. [Figure 2] FIG. 1 is a flow diagram illustrating a patterning process according to one embodiment. [Figure 3A-F] 3A-3C are cross-sectional views of structures formed during the patterning process shown in FIG. 2 according to one embodiment. [Figure 3G-I] 3A-3C are cross-sectional views of structures formed during the patterning process shown in FIG. 2 according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011]

[0013] To facilitate an understanding of the embodiments, wherever possible, like reference numerals have been used to designate like elements common to the drawings. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.

[0012]

[0014] It should be noted, however, that the attached drawings merely illustrate illustrative examples and therefore should not be considered as limiting the scope of the invention, which may also allow other equally effective embodiments.

[0013]

[0015] Methods are provided for forming and etching a film stack to form high aspect ratio features in the film stack. The methods described herein facilitate profile and dimensional control of high aspect ratio features through appropriate sidewall and bottom management schemes with desired materials selected for the film stack. Specifically, the methods described herein provide a metal-containing photoresist layer selectively overlaid with a carbon-containing passivation layer that has high etch selectivity from an underlying metal-containing hardmask layer, resulting in precise control of the profile of openings etched in the hardmask layer.

[0014]

[0016] 1 is a cross-sectional view of one embodiment of a processing chamber 100 suitable for performing a patterning process to etch a film stack having a hard mask layer made from a metal-containing material. Suitable processing chambers that may be adapted for use with the teachings disclosed herein include, for example, ENABLER® or C3® processing chambers available from Applied Materials, Inc. of Santa Clara, Calif. While processing chamber 100 is shown including several features that enable superior etching performance, it is contemplated that other processing chambers may also be adapted to benefit from one or more of the inventive features disclosed herein.

[0015]

[0017] The processing chamber 100 includes a chamber body 102 and a lid 104 that enclose an interior region 106. The chamber body 102 is typically fabricated from aluminum, stainless steel, or other suitable materials. The chamber body 102 generally includes sidewalls 108 and a bottom 110. A substrate support pedestal access port (not shown) is typically defined in the sidewall 108 and selectively sealed by a slit valve to facilitate entry and exit of the substrate 103 from the processing chamber 100. An exhaust port 126 is defined in the chamber body 102 and couples the interior region 106 to a pumping system 128. The pumping system 128 typically includes one or more pumps and a throttle valve used to evacuate and adjust the pressure of the interior region 106 of the processing chamber 100. In one or more implementations, the pumping system 128 maintains the pressure within the interior region 106 at an operating pressure typically between about 10 mTorr and about 500 Torr.

[0016]

[0018] The lid 104 is sealingly supported on a sidewall 108 of the chamber body 102. The lid 104 can be opened to allow access to the interior region 106 of the processing chamber 100. The lid 104 includes a window 142 that facilitates optical process monitoring. In one implementation, the window 142 is constructed of quartz or other suitable material that is transparent to signals used by an optical monitoring system 140 mounted outside the processing chamber 100.

[0017]

[0019] The optical monitoring system 140 is positioned to view through the window 142 at least one of the interior region 106 of the chamber body 102 and / or the substrate 103 positioned on the substrate support pedestal assembly 148. In one or more embodiments, the optical monitoring system 140 is coupled to the lid 104 and uses optical metrology to facilitate an integrated deposition process that provides information that allows adjustments to the process, if necessary, to compensate for inconsistencies in incoming substrate pattern features (e.g., thickness) and provides process status monitoring (e.g., plasma monitoring, temperature monitoring). One optical monitoring system that can be adapted to benefit from the present invention is the EyeD® full-spectrum, interferometric metrology module available from Applied Materials, Inc. of Santa Clara, California.

[0018]

[0020] A gas panel 158 is coupled to the processing chamber 100 and supplies process and / or cleaning gases to the interior region 106. In the embodiment shown in Figure 1, inlet ports 132', 132'' are provided in the lid 104 so that gases can be supplied from the gas panel 158 to the interior region 106 of the processing chamber 100.

[0019]

[0021] The showerhead assembly 130 is coupled to the inner surface 114 of the lid 104. The showerhead assembly 130 includes a plurality of apertures that allow gases to flow from inlet ports 132′, 132″ through the showerhead assembly 130 and into the interior region 106 of the processing chamber 100 in a predetermined distribution across the surface of the substrate 103 being processed in the processing chamber 100.

[0020]

[0022] A remote plasma source 177 may optionally be coupled to the gas panel 158 to facilitate dissociation of the gas mixture from the remote plasma before entering the interior region 106 for processing. A radio frequency (RF) power source 143 is coupled to the showerhead assembly 130 through a matching network 141. The RF power source 143 is typically capable of generating up to about 3000 W at an adjustable frequency ranging from about 50 kHz to about 200 MHz.

[0021]

[0023] The showerhead assembly 130 further includes a region that is transparent to optical metrology signals. The optically transparent region or passage 138 is adapted to allow the optical monitoring system 140 to view the interior region 106 and / or the substrate 103 positioned on the substrate support pedestal assembly 148. The passage 138 may be an aperture or apertures formed or disposed in the showerhead assembly 130 that are substantially transparent to the wavelengths of energy generated and reflected back by the optical monitoring system 140. In one or more embodiments, the passage 138 includes a window 142 to prevent gas from leaking through the passage 138. The window 142 may be a sapphire plate, a quartz plate, or other suitable material. The window 142 may alternatively be disposed in the lid 104.

[0022]

[0024] In one implementation, the showerhead assembly 130 is configured with multiple zones that allow separate control of gas flow into the interior region 106 of the processing chamber 100. In the example shown in FIG. 1 , the showerhead assembly 130 has an inner zone 134 and an outer zone 136 that are separately coupled to the gas panel 158 through separate inlet ports 132′, 132″.

[0023]

[0025] The substrate support pedestal assembly 148 is disposed below the showerhead assembly 130 in the interior region 106 of the processing chamber 100. The substrate support pedestal assembly 148 holds the substrate 103 during processing. The substrate support pedestal assembly 148 generally includes a plurality of lift pins (not shown) disposed therethrough that are configured to lift the substrate 103 from the substrate support pedestal assembly 148 and facilitate exchange of the substrate 103 using a robot (not shown) in a conventional manner. An inner liner 118 may closely surround the periphery of the substrate support pedestal assembly 148.

[0024]

[0026] In one implementation, the substrate support pedestal 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 passages for routing utilities such as fluids, power lines, and sensor leads to the base 164 and the electrostatic chuck 166, among other things. The electrostatic chuck 166 includes at least one clamping electrode 180 for holding the substrate 103 below the showerhead assembly 130. The electrostatic chuck 166 is powered by a chuck power supply 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 can be held to the substrate support pedestal assembly 148 by clamps, vacuum, or gravity.

[0025]

[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 for controlling the lateral temperature profile of the substrate support pedestal assembly 148. The conduits 168, 170, which circulate a temperature-regulating fluid therethrough, are fluidly coupled to a fluid source 172. The heater 176 is regulated by a power supply 178. The conduits 168, 170 and the heater 176 are used to control the temperature of the base 164, thereby heating and / or cooling the electrostatic chuck 166 and ultimately controlling the temperature profile of the substrate 103 disposed thereon. The temperatures of the electrostatic chuck 166 and the base 164 may be monitored using a plurality of temperature sensors 190, 192. The electrostatic chuck 166 may further include a plurality of gas passages (not shown), such as grooves, formed in the substrate support pedestal support surface of the electrostatic chuck 166 and fluidly coupled to a source of heat transfer (or backside) gas, such as He. In operation, the backside gas is supplied at a controlled pressure within the gas passages to enhance heat transfer between the electrostatic chuck 166 and the substrate 103.

[0026]

[0028] In one implementation, the substrate support pedestal assembly 148 includes a clamping electrode 180 configured as a cathode and coupled to multiple RF bias power supplies 184, 186. The RF bias power supplies 184, 186 are coupled between the electrode 180 disposed on the substrate support pedestal assembly 148 and another electrode, such as the showerhead assembly 130 or the lid 104 of the chamber body 102. The RF bias power excites and sustains a plasma discharge formed from gases disposed in the processing region of the chamber body 102.

[0027]

[0029] 1 , dual RF bias power supplies 184, 186 are coupled to an electrode 180 disposed on the substrate support pedestal assembly 148 through a matching network 188. The signals generated by the RF bias power supplies 184, 186 are sent as a single supply through the matching network 188 to the substrate support pedestal assembly 148 to ionize the gas mixture supplied to the processing chamber 100, thereby providing the ion energy necessary to perform a deposition or other plasma process. The RF bias power supplies 184, 186 are typically capable of generating RF signals having a frequency from about 50 kHz to about 200 MHz and a power from about 0 watts to about 8000 watts, e.g., from about 1 watt to about 5000 watts. An additional bias power supply 189 may be coupled to the electrode 180 to control the characteristics of the plasma.

[0028]

[0030] During operation, the substrate 103 is positioned on the substrate support pedestal assembly 148 of the processing chamber 100. Process gases and / or gas mixtures are introduced into the chamber body 102 from the gas panel 158 through the showerhead assembly 130. A pumping system 128 maintains pressure within the chamber body 102 while removing deposition by-products.

[0029]

[0031] A controller 150 is coupled to the processing chamber 100 to control its operation. The controller 150 includes a central processing unit (CPU) 152, a memory 154, and support circuits 156 used to control process sequences and regulate gas flows from a gas panel 158. The CPU 152 may be any form of general-purpose computer processor that may be used in an industrial environment. Software routines may be stored in the memory 154, such as random access memory, read-only memory, a floppy or hard disk drive, or other form of digital storage. The support circuits 156 are conventionally coupled to the CPU 152 and may include cache, clock circuits, an input / output system, a power supply, etc. Bidirectional communication between the controller 150 and the various components of the processing chamber 100 is handled through a number of signal cables.

[0030]

[0032] FIG. 2 is a flow diagram of a method 200 for a patterning process according to one embodiment described herein. FIGS. 3A-3I are cross-sectional views of a structure 300 formed during the patterning process of FIG. 2. Method 200 can be used to form features such as trenches, vias, and openings with desired critical dimensions and profiles. In some embodiments, the dimensions of the features are about 14 nm to about 22 nm, e.g., about 18 nm. Structure 300 can be used in gate, contact, or interconnect structures in front-end or back-end processes. Alternatively, method 200 can be beneficially used to etch other types of structures. Those skilled in the art should recognize that the complete process for forming semiconductor devices and related structures is not shown in the drawings or described herein. While various steps are shown in the drawings and described herein, no limitations regarding the order of such steps or the presence or absence of steps are implied. Steps shown or described as sequential are performed so solely for illustrative purposes, unless expressly specified otherwise, and do not exclude the possibility that the steps may actually be performed at least partially, if not completely, simultaneously or overlapping.

[0031]

[0033] The method 200 begins in step 210 by transferring or providing a film stack 302, as shown in FIG. 3A, to a processing chamber, such as the processing chamber 100 shown in FIG. 1. In one embodiment, the film stack 302 may have multiple layers stacked vertically 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 from a high-k material having a dielectric constant greater than 4. Suitable examples of high-k materials include aluminum oxide (Al2O3), tantalum oxide (Ta2O5), tantalum nitride (TaN), tantalum oxynitride (TaN), and the like. 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), lead zirconate titanate (PZT, Pb[Zr x Ti 1-x ]O3, 0≦x≦1), etc. The silicon-containing dielectric layer includes silicon oxide (SiO2), silicon nitride (SiN), silicon oxynitride (SiON), silicon carbide (SiC), silicon oxycarbide (SiO x C y , 0≦x, y≦1), etc.

[0032]

[0034] The substrate may be a semiconductor substrate, a silicon wafer, a glass substrate, etc. The substrate may be crystalline silicon (e.g., Si <100> or Si <111> The substrate may be formed of materials such as silicon oxide, strained silicon, silicon germanium, germanium, doped or undoped polysilicon, doped or undoped silicon wafers and patterned or unpatterned wafers, silicon-on-insulator (SOI), carbon doped silicon oxide, silicon nitride, doped silicon, germanium, gallium arsenide, glass, or sapphire. The substrate may have a variety of dimensions, such as 200 mm, 300 mm, 450 mm, etc., or other diameters, and be a rectangular or square panel.

[0033]

[0035] In step 220, a bottom antireflective coating (BARC) layer 304 is formed on the film stack 302, as shown in FIG. 3A. In some embodiments, the BARC layer 304 is made of a carbon-containing material, such as boron-doped amorphous carbon. The BARC layer 304 may be a Saphira™ Advanced Patterning Film (APF) carbon hard mask manufactured by Applied Materials, Inc., Santa Clara, California. In some embodiments, the BARC layer 304 is a high-density carbon-containing layer and has excellent film qualities, such as improved hardness and density. Due to such hardness and density, the BARC layer 304 acts as a stronger barrier to metal intrusion than conventional spin-on carbon (SOC) hard masks, significantly preventing and reducing nano-failures.

[0034]

[0036] The BARC layer 304 may be formed by a physical vapor deposition (PVD) process, a plasma enhanced chemical vapor deposition (PECVD) process, or other suitable deposition process. In one embodiment, the BARC layer 304 is formed from C2H2, C3H6, CH4, C4H8, 1,3-dimethyladamantane, bicyclo[2.2.1]hepta-2,5-diene (2,5-norbornadiene), adamantane (C 10 H 16 ), norbornene (C7H10 The diamond-like carbon layer is formed by a chemical vapor deposition (CVD) (plasma and / or thermal) process using a hydrocarbon-containing gas mixture containing precursors such as SiO 2 , SiO 3 , or a combination thereof. The deposition process can be performed at a temperature ranging from -50°C to 600°C. The deposition process can be performed in the interior region 106 of the processing chamber 100 at a pressure ranging from 0.1 mTorr to 10 Torr. The hydrocarbon-containing gas mixture can further include a carrier gas such as He, Ar, Xe, N 2 , H 2 , or a combination thereof, and an etching gas such as Cl 2 , CF 4 , NF 3 , or a combination thereof to improve film quality. The plasma (e.g., capacitively coupled plasma) can be formed from either the top and bottom electrodes or the side electrodes of the processing chamber 100. The electrodes can be formed from a single powered electrode, dual powered electrodes, or additional electrodes, with multiple frequencies, such as, but not limited to, 350 KHz, 2 MHz, 13.56 MHz, 27 MHz, 40 MHz, 60 MHz, and 100 MHz, used alternately or simultaneously in the CVD system.

[0035]

[0037] In step 230, as shown in FIG. 3B, a hard mask layer 306 is formed on the BARC layer 304. 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 having a wavelength of about 5 nm to about 20 nm, e.g., about 13.5 nm, during the lithography exposure process. Therefore, by appropriately selecting the material for the hard mask layer 306, the performance of the EUV lithography exposure process can be improved, such as high lithography resolution, defect reduction, photoresist layer profile control, energy dose reduction, and / or line edge roughness reduction. For example, because a material with a higher metal concentration can provide a higher absorption coefficient of EUV radiation, the hard mask layer 306 can be formed from a metal-containing material, such as a metal dielectric layer, including one or more metal elements having an atomic number greater than 28, such as 29 to 32, 37 to 51, and 55 to 83. Suitable metal elements include tin (Sn), tantalum (Ta), indium (In), gallium (Ga), zinc (Zn), zirconium (Zr), aluminum (Al), or combinations thereof. Furthermore, a low concentration of silicon dopant and / or oxygen element in the metal-containing material can further increase free carriers, enhance the absorption coefficient of EUV radiation, and reduce the likelihood of defect generation. Suitable examples of metal-containing materials for the hard mask layer 306 may be or include tin oxide (SnO), silicon tin oxide (SnSiO), tantalum oxide (TaO), indium tin oxide (InSnO), indium gallium zinc oxide (IGZO), one or more alloys thereof, one or more dopants thereof, or any combination thereof having a ratio of metal element to silicon or oxygen element (metal:Si / O) of about 80:1 / 19 to about 90:1 / 9. The metal-containing material for the hard mask layer 306 exhibits a 1×10 5 (cm 2 / mol). In one or more embodiments, the hard mask layer 306 has a thickness of about 10 Å to about 500 Å, such as about 20 Å to about 200 Å, for example, about 50 Å to about 100 Å.

[0036]

[0038] In some embodiments, the hard mask layer 306 includes multiple layers. The hard mask layer 306 can have multiple layers formed from different metal-containing materials. The selection of metal-containing materials for the multiple layers is based on the different absorption coefficients of the metal-containing materials. For example, multiple layers having high to low, low to high, or alternating high and low absorption coefficients can be formed sequentially to enhance reflection of EUV radiation during a lithography exposure process. In one or more embodiments, a metal element selected for one of the multiple layers can have an atomic number greater than 28, such as greater than 35, and another metal element can have an atomic number less than 28.

[0037]

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

[0038]

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

[0039]

[0041] The hard mask layer 306 may be formed by a CVD process, a PVD process, an atomic layer deposition (ALD) process, a spin-on coating process, a spray coating process, or other suitable deposition process. In some embodiments, a carrier gas and / or an inert gas having a relatively high atomic weight, such as Xe or Kr, may be used during the plasma CVD or PVD process for forming the hard mask layer 306. The temperature during the formation of the hard mask layer 306 may be controlled to be between −50° C. and approximately 250° C. It is believed that controlling the temperature during the formation of the hard mask layer 306 to be relatively low, for example, below 250° C., may result in the hard mask layer 306 being formed at a relatively slow deposition rate and may facilitate the formation of a film surface having a relatively smooth surface.

[0040]

[0042] In step 240, a photoresist layer 308 is formed on the hard mask layer 306, as shown in FIG. 3C. In the embodiments described herein, the photoresist layer 308 is formed of an organometallic material containing organic ligands. The organometallic material layer is formed by dissolving a metal in an oxo ligand (O 2- ) and hydroxo ligands (OH - ), as well as polymeric metal oxo / hydroxo networks linked with organic ligands, or polynuclear metal oxo / hydroxo species with organic ligands.

[0041]

[0043] The photoresist layer 308 can be formed by a CVD process, a PVD process, an ALD process, a spin-on coating process, a spray coating process, or other suitable deposition process using a precursor solution containing a metal oxo-hydroxo cation with an organic ligand in an organic solvent. In this context, a metal (M) oxo-hydroxo cation is a metal cation that, in aqueous solution, bonds to an oxygen atom (O) to form a hydrogen ion (H - ) while releasing the oxo ligand (O 2- ) and / or hydroxo ligands (OH -(M) refers to one or more metal (M) ions that form a metal (M) oxo-hydroxocation. The metal (M) oxo-hydroxocation may further bond to an organic ligand to form one or more metal-carbon (MC) and / or metal-carboxylate (M-OC) ligand bonds. Suitable metals (M) for forming metal oxo / hydroxocations include metals from Groups 13, 14, and 15, such as tin (Sn), antimony (Sb), and indium (In). To generate more complex polynuclear metal oxo / hydroxocations (i.e., containing two or more metal atoms), additional metals, such as Ti, Zr, Hf, V, Co, Mo, W, Al, Ga, Si, Ge, P, As, Y, La, Ce, Lu, or combinations thereof, may be blended into the precursor solution. The additional metals may be substituted for or in addition to tin (Sn), antimony (Sb), and / or indium (In). When a blend of metal ions is used, the molar ratio of non-tin / antimony / indium ions per tin / antimony / indium metal ion is up to about 1 in one example, and from about 0.1 to about 0.75 in another example. In some embodiments, tin (Sn) or indium (In) is used in the precursor solution to form a photoresist layer with strong absorption of extreme ultraviolet (EUV) radiation at a wavelength of 13.5 nm and, in combination with organic ligands, good absorption of ultraviolet (UV) radiation at a wavelength of 193 nm. In some embodiments, Hf is used to obtain good absorption of electron beam materials and extreme ultraviolet (EUV) radiation. In some embodiments, one or more metal compositions including Ti, V, Mo, W, or combinations thereof are added to shift the absorption edge to longer wavelengths and obtain sensitivity to ultraviolet (UV) radiation at a wavelength of 248 nm.

[0042]

[0044] The organic ligand can be, for example, alkyl (e.g., methyl, ethyl, propyl, butyl, t-butyl, aryl (phenyl, benzyl)), alkenyl (e.g., vinyl, allyl), and carboxylate (e.g., acetate, propanoate, butanoate, benzoate). The ratio of the concentration of the organic ligand to the concentration of the metal oxo-hydroxo cation in the precursor solution is from about 0.25 to about 4 in one embodiment, from about 0.5 to about 3.5 in another embodiment, from about 0.75 to about 3 in another embodiment, and from about 1 to about 2.75 in another embodiment. A person of ordinary skill in the art will recognize that additional ranges of organic ligand concentrations within the explicit ranges above are contemplated and are within the present disclosure.

[0043]

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

[0044]

[0046] In some embodiments, the deposited photoresist layer 308 has a thickness of about 1 nm to about 1 μm, for example, about 8 nm to about 13 nm.

[0045]

[0047] In step 250, the photoresist layer 308 is exposed to radiation according to a selected pattern that includes features such as trenches, vias, and openings having desired critical dimensions and profiles to be formed in the film stack 302, as shown in FIG. 3D. The selected pattern is transferred to a corresponding pattern, or latent image, in the photoresist layer 308, which has irradiated and non-irradiated areas. Upon exposure to radiation, the photoresist layer 308 absorbs the radiation, which provides energy to sever bonds between metals and organic ligands (i.e., metal-carbon (MC) ligand bonds and / or metal-carboxylate (M-OC) ligand bonds) in the irradiated areas of the photoresist layer 308. This bond severance can result in a compositional change in the irradiated areas of the photoresist layer 308 through the formation of metal-hydroxide (M-OH) ligand bonds or through condensation to form metal-oxygen (MOM) ligand bonds.

[0046]

[0048] Due to the absorption of a sufficient amount of radiation, a contrast in material properties exists between the irradiated areas of the photoresist layer 308, which are free or substantially free of organic ligands, and the non-irradiated areas of the photoresist layer 308, which still retains the organic ligands. For example, the non-irradiated areas of the photoresist layer 308 with the organic ligands are relatively hydrophobic, while the irradiated areas of the photoresist layer 308 without the organic ligands are less hydrophobic (i.e., more hydrophilic) than the non-irradiated areas of the photoresist layer 308. Utilizing this contrast, the photoresist layer 308 can provide positive-tone patterning (irradiated areas become soluble in the developer) and negative-tone patterning (irradiated areas become insoluble in the developer) with an appropriate developer.

[0047]

[0049] The radiation may be electromagnetic radiation, an electron beam, or other suitable radiation. The radiation may be directed at the photoresist layer 308 through a mask 310, or a radiation beam may be controllably scanned across the photoresist layer 308. The electromagnetic radiation may have a desired wavelength or range of wavelengths, such as visible radiation, ultraviolet (UV) radiation (100 nm to 400 nm, including extreme ultraviolet (EUV) from 10 nm to 121 nm and far ultraviolet (FUV) from 122 nm to 200 nm), or X-rays (soft X-rays from 0.1 nm to 10 nm), depending on the desired spatial resolution for patterning the underlying film stack 302. Higher resolution patterns may be achieved using shorter wavelength radiation, such as ultraviolet radiation, X-rays, or an electron beam. For example, EUV radiation generated from a Xe or Sn plasma source excited using a high-energy laser or discharge pulses may be used for 13.5 nm lithography.

[0048]

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

[0049]

[0051] In step 260, the photoresist layer 308 is developed to pattern the photoresist layer 308 according to a selected pattern, as shown in Figure 3E. The patterned photoresist layer 308A defines openings 312 that expose a surface 314 of the underlying hard mask layer 306 for etching.

[0050]

[0052] A developer for developing the irradiated photoresist layer 308 and removing the unirradiated areas of the photoresist layer 308 (i.e., negative-tone patterning) to form the patterned photoresist layer 308A can 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 ester 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), and the like. Development is performed for about 5 seconds to about 30 minutes in one example, about 8 seconds to about 15 minutes, and about 10 seconds to about 10 minutes in other examples.

[0051]

[0053] In some embodiments, the developer solution may contain additional compositions to enhance the development process, for example, by improving contrast, sensitivity, and linewidth roughness, and by inhibiting the formation and precipitation of metal oxide particles. Suitable additives include, for example, molten salts having cations selected from the group consisting of ammonium, d-block metal cations (e.g., hafnium, zirconium, lanthanum), f-block metal cations (e.g., cerium, lutetium), p-block metal cations (e.g., aluminum, tin), alkali metals (e.g., lithium, sodium, potassium), and combinations thereof, and molten salts having anions selected from the group consisting of fluoride, chloride, bromide, iodide, nitrate, sulfate, phosphate, silicate, borate, peroxide, butoxide, formate, ethylenediaminetetraacetic acid (EDTA), tungstate, molybdate, and combinations thereof. Other potentially useful additives include molecular chelating agents, such as polyamines, alcoholamines, amino acids, or combinations thereof. When optional additives are present, the developer solution may contain up to about 10 wt % of the additives in one embodiment, and up to about 5 wt % of the additives in another embodiment. A person of ordinary skill in the art will recognize that additional ranges of additive concentrations within the explicit ranges above are contemplated and are within the present disclosure.

[0052]

[0054] The developer may be applied to the irradiated photoresist layer 308 using a spin-on coating process, a spray coating process, or other suitable coating process. In some embodiments, spin rinsing and / or drying may be performed to complete the development process. Suitable rinsing solutions include ultra-pure water, methyl alcohol, ethyl alcohol, propyl alcohol, and combinations thereof.

[0053]

[0055] In some embodiments, the patterned photoresist layer 308A can be treated to further condense the material and further dehydrate the material. In some embodiments, the patterned photoresist layer 308A can be heated to a temperature of about 100° C. to about 600° C. in one example, about 175° C. to about 500° C. in other examples, and about 200° C. to about 400° C. in other examples. Heating can occur for at least about 1 minute in one example, about 2 minutes to about 1 hour in other examples, and about 2.5 minutes to about 25 minutes in other examples. Heating can occur in air, vacuum, or an inert gas atmosphere such as Ar or N2. A person of ordinary skill in the art will recognize that additional ranges of temperatures and times for heat treatment within the explicit ranges above are contemplated and are within the present disclosure.

[0054]

[0056] In some embodiments, adjacent linear segments of adjacent structures may have an average pitch of about 60 nm or less, in some embodiments about 50 nm or less, and in further embodiments about 40 nm or less.

[0055]

[0057] In step 270, as shown in FIG. 3F , a passivation layer 316 is selectively formed on the patterned photoresist layer 308A prior to etching the hard mask layer 306. The passivation layer 316 may be formed from a carbon-containing material in situ in an etching chamber or by supplying a deposition gas mixture to the patterned photoresist layer in a PVD chamber. In the embodiments described herein, the passivation layer 316 is primarily formed on the top surface 318 of the patterned photoresist layer 308A, but not on the sidewalls 320 of the patterned photoresist layer 308A or the exposed surface 314 of the hard mask layer 306. Thus, the profile (e.g., size and geometry) of the opening 312 defined by the patterned photoresist layer 308A remains unchanged to facilitate transfer of the opening 312 to the hard mask layer 306 without profile change.

[0056]

[0058] Without being bound by theory, it is believed that scission of bonds between the metal and the organic ligands (i.e., metal-carbon (MC) and / or metal-carboxylate (M-OC) ligand bonds) results in carbon atoms being bonded to the top surface 318 (i.e., the irradiated areas) of the photoresist layer 308, which has metal-hydroxide (M-OH) and metal-oxygen (MOM) ligand bonds. The sidewalls 320 of the patterned photoresist layer 308A maintain the composition of the unirradiated photoresist layer 308, which has the organic ligands intact, and therefore do not contain metal-hydroxide (M-OH) and metal-oxygen (MOM) ligand bonds to which carbon atoms could be bonded. Furthermore, the exposed surface 314 of the hard mask layer 306 also does not contain metal-hydroxide (M-OH) and metal-oxygen (MOM) ligand bonds, and therefore no carbon atoms are bonded to the exposed surface 314 of the hard mask layer 306.

[0057]

[0059] In one or more embodiments, the deposition gas mixture includes a carbon-containing gas, such as CO gas or CH gas. As described above, the hard mask layer 306 is formed of a material containing a metal element, such as tin (Sn), and the photoresist layer 308 is also formed of a material containing a metal element, such as tin (Sn), resulting in poor etch selectivity between the hard mask layer 306 and the photoresist layer 308. Therefore, when the hard mask layer 306 with the photoresist layer 308 disposed thereon is etched, the profile of the openings etched in the hard mask layer 306 may be imprecisely controlled, which may ultimately lead to device failure. The presence of the passivation layer 316 thereon increases the etch selectivity of the patterned photoresist layer 308B from the hard mask layer 306, resulting in more precise control of the profile of the openings etched in the hard mask layer 306.

[0058]

[0060] 3G, the hard mask layer 306 is etched to transfer the openings 312 in the patterned photoresist layer 308A into the hard mask layer 306. The patterned hard mask layer 306A defines openings 322 that expose a surface 324 of the underlying BARC layer 304 for etching. In one or more embodiments, the etching process in step 280 is performed 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° C.) to a maximum of about 150° C.

[0059]

[0061] In some embodiments, the etching gas mixture includes at least one halogen-containing gas. The halogen-containing gas may include a fluorine-containing gas, a chlorine-containing gas, or a bromide-containing gas. Suitable examples of halogen-containing gases include SF, SiCl, SiCl, NF, HBr, Br, CHF, CHF, CF, CF, CF, CF, HCl, CF, Cl, HF, CCl, CHCl, CHCl, and CHCl. ​​In some embodiments, a silicon-containing gas may also be provided in the etching gas mixture. Suitable examples of silicon-containing gases include SiCl, SiCl, SiH, SiH, and the like. More specifically, examples of chlorine-containing gases include HCl, Cl, CCl, CHCl, CHCl, CHCl, SiCl, SiCl, and the like, and examples of bromide-containing gases include HBr and Br. Optionally, reactive gases such as oxygen-containing or nitrogen-containing gases, e.g., O2, N2, N2O, NO2, O3, H2O, etc., may also be provided to the etching gas mixture.

[0060]

[0062] In one or more embodiments, the halogen-containing gas used to etch the hard mask layer 306 includes a chlorine-containing gas or a bromide-containing gas. While the etching gas mixture is being supplied into the processing chamber, an inert gas can optionally be supplied to the etching gas mixture to aid in profile control, if desired. Examples of inert gases that can be supplied to the mixture include Ar, He, Ne, Kr, Xe, etc. In one specific example, the etching gas mixture used to etch the hard mask layer 306, such as a metal-containing material (e.g., a Sn / SnO / SnSiO layer), includes HBr, Cl, Ar, He, or a combination thereof.

[0061]

[0063] During etching, the chamber pressure of the etching gas mixture is also adjusted. In one or more embodiments, the process pressure of the plasma processing chamber is adjusted to about 2 mTorr to about 100 mTorr, for example, about 3 mTorr to 20 mTorr, for example, about 6 mTorr. RF source or bias power can be applied in the presence of the etching gas mixture to maintain the formed plasma, either in a continuous or pulsed mode, as needed. For example, to maintain the plasma in the etching chamber, an RF power source having a frequency of about 13.56 MHz can be applied to an inductively coupled antenna source at an energy level of about 200 Watts to about 1000 Watts, for example, about 500 Watts. Furthermore, RF bias power having a frequency of about 2 MHz to about 13.56 MHz can be applied at less than 500 Watts, for example, about 0 Watts to about 450 Watts, for example, about 150 Watts.

[0062]

[0064] In one or more embodiments, the RF bias power and the RF power source may be pulsed in the processing chamber 100 during etching in step 280. The RF bias power and the RF power source may be pulsed synchronously or asynchronously in the processing chamber. In some embodiments, the RF bias power and the RF power source are pulsed asynchronously in the processing chamber. For example, the RF power source may be pulsed into the processing chamber before pulsing the RF bias power. For example, the RF bias power may be in a pulse mode synchronous with the RF power source or may have a time delay relative to the RF power source. In one or more embodiments, the RF power source and the RF bias power are pulsed at about 5% to about 75% of each duty cycle. Each duty cycle, for example, between each time unit, is about 0.1 milliseconds (ms) to about 10 ms.

[0063]

[0065] In one example of the etching gas mixture supplied in step 280, O gas may be supplied into the chamber at a rate of about 0 sccm to about 50 sccm, and a halogen-containing gas, such as HBr, may be supplied at a flow rate of about 25 sccm to about 250 sccm, for example about 100 sccm.

[0064]

[0066] In step 290, BARC layer 304 is etched such that openings 322 in patterned hard mask 360A are transferred to BARC layer 304, as shown in FIG. 3H. Patterned BARC layer 304A defines openings 326 that expose surfaces 328 of underlying film stack 302. The etchant gas mixture used to etch BARC layer 304 in step 290 can be the same as the etchant gas mixture used to etch hard mask layer 306 in step 280. Alternatively, the etchant gas mixture used to etch BARC layer 304 in step 290 can be different from the etchant gas mixture used to etch hard mask layer 306 in step 280. In one or more embodiments, the etchant gas mixture used to etch BARC layer 304 in step 290 can include a chlorine-containing gas, such as HCl or Cl gas.

[0065]

[0067] After openings 326 are formed in BARC layer 304, a descumming or stripping process may be performed to remove remaining passivation layer 316, if any, as shown in FIG. 31. It should be noted that additional etching or patterning processes may be performed to continue the transfer of openings 326 into film stack 302 and form selected patterns in film stack 302, including features such as trenches, vias, openings, etc., having desired critical dimensions and profiles.

[0066]

[0068] Embodiments described herein provide methods for forming a metal-containing photoresist layer selectively overlaid with a carbon-containing passivation layer that has high etch selectivity from an underlying metal-containing hardmask layer, resulting in precise control of the profile of openings etched in the hardmask layer, thereby enabling improved lithography exposure accuracy, such as high resolution, low energy dose, good photoresist profile control, and low line edge roughness.

[0067]

[0069] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the present disclosure may be devised without departing from its basic scope, as determined by the following claims. All documents set forth herein, including any priority documents and / or testing procedures, to the extent not inconsistent therewith, are incorporated herein by reference. While forms of the present disclosure have been illustrated and described, as is evident from the foregoing general description and specific embodiments, various modifications can be made without departing from the spirit and scope of the present disclosure. Accordingly, the present disclosure is not limited thereby. Similarly, the term "comprising" is considered synonymous with the term "including" for purposes of U.S. law. Similarly, whenever the transitional phrase "comprising" precedes a configuration, element, or group of elements, it is understood that the same configuration or group of elements can also be preceded by the transitional phrase "consisting essentially of," "consisting of," "selected from the group consisting of," or "is," and vice versa.

[0068]

[0070] Certain embodiments and features have been described using a set of upper numerical limits and a set of lower numerical limits. It is understood that, unless otherwise specified, ranges including any combination of two values ​​are contemplated, such as any combination of a lower limit with any upper limit, any two lower limits, and / or any two upper limits. Specific lower limits, upper limits, and ranges are set forth in one or more claims below.

Claims

1. 1. A method of etching a hard mask layer, comprising: forming a photoresist layer comprising an organometallic material on a hard mask layer comprising a metal-containing material; exposing the photoresist layer to ultraviolet light through a mask having a selected pattern to create exposed and unexposed areas of the photoresist layer; removing the exposed or unexposed areas of the photoresist layer to pattern the photoresist layer; forming a passivation layer containing a carbon-containing material only on the top surface of the patterned photoresist layer; etching the hard mask layer exposed by the removed irradiated or non-irradiated areas of the patterned photoresist layer on which the passivation layer is formed; A method comprising:

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. 3. The method of claim 2, wherein the organic ligand is selected from the group consisting of alkyl, alkenyl, and carboxylate.

5. forming the passivation layer includes: On the patterned photoresist layer, CO and CH ４ providing a deposition gas comprising a gas selected from the group consisting of The method of claim 1 , comprising:

6. 1. A method of etching a film stack, comprising: forming a bottom anti-reflective coating layer on the film stack; forming a hard mask layer comprising a metal-containing material on the bottom antireflective coating layer; forming a photoresist layer containing an organometallic material on the hard mask layer; exposing the photoresist layer to ultraviolet light through a mask having a selected pattern to create exposed and unexposed areas of the photoresist layer; removing the exposed or unexposed areas of the photoresist layer to pattern the photoresist layer; forming a passivation layer containing a carbon-containing material only on the top surface of the patterned photoresist layer; Etching the hard mask layer exposed by the patterned photoresist layer formed thereon with the passivation layer to pattern the hard mask layer; etching the bottom antireflective coating layer exposed by the removed illuminated or non-illuminated areas of the patterned hard mask layer to pattern the bottom antireflective coating layer; etching the film stack exposed by the patterned bottom antireflective coating layer; A method comprising:

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. 8. The method of claim 7, wherein the organic ligand is selected from the group consisting of alkyl, alkenyl, and carboxylate.

10. forming the passivation layer includes: On the patterned photoresist layer, CO and CH ４ providing a deposition gas comprising a gas selected from the group consisting of The method of claim 6, comprising:

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

12. 7. The method of claim 6, wherein the metal-containing material of the hard mask layer is selected from the group consisting of tin oxide (SnO), silicon tin oxide (SnSiO), tantalum oxide (TaO), indium tin oxide (InSnO), indium gallium zinc oxide (IGZO), and any combination thereof.

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

14. 1. A method for selectively forming a passivation layer on a patterned photoresist layer, comprising: exposing a top surface of a photoresist layer including an organometallic material to ultraviolet light through a mask to create irradiated and non-irradiated areas of the photoresist layer, the organometallic material including one or more metal elements and organic ligands; removing the unexposed areas of the photoresist layer to pattern the photoresist layer; forming a passivation layer containing a carbon-containing material only on the upper surface of the patterned photoresist layer, the passivation layer is formed by bonding carbon atoms to the top surface of the patterned photoresist layer after the exposure to ultraviolet light has severed bonds between the one or more metal elements and the organic ligands, resulting in a metal-hydroxide ligand bond and a metal-oxygen ligand bond; and the sidewalls of the patterned photoresist layer that have not been exposed to ultraviolet light do not have metal hydroxide ligand bonds and metal oxygen ligand bonds, and therefore the passivation layer is not formed on the sidewalls; forming a passivation layer; A method comprising:

15. 15. The method of claim 14, wherein the one or more metallic elements include tin (Sn).

16. 15. The method of claim 14, 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.

17. 15. The method of claim 14, wherein the organic ligand is selected from the group consisting of alkyl, alkenyl, and carboxylate.

18. heating the patterned photoresist layer; The method of claim 14 further comprising:

19. forming the passivation layer includes: On the patterned photoresist layer, CO and CH ４ providing a deposition gas comprising a gas selected from the group consisting of 15. The method of claim 14, comprising:

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