High etching selectivity amorphous carbon film

Abstract

Methods and techniques are provided for depositing an amorphous carbon film on a substrate. In one example, the method includes depositing an amorphous carbon film on an underlayer positioned on a susceptor in a first processing region. The method further includes implanting a dopant or inert species into the amorphous carbon film in a second processing region. A combination of implant species, energy, dose, and temperature can be used to improve the hardness of the hard mask. The method further includes patterning the doped amorphous carbon film. The method further includes etching the underlayer.

Description

[Technical Field]

[0001] The embodiments described herein generally relate to the manufacture of integrated circuits. More specifically, the embodiments described herein provide techniques for depositing amorphous carbon films onto substrates. [Background technology]

[0002] Integrated circuits have evolved into complex devices that can contain millions of transistors, capacitors, and resistors on a single chip. The evolution of chip design continuously requires faster circuits and higher circuit density. This demand for faster circuits with higher circuit density places corresponding demands on the materials used to manufacture such integrated circuits. In particular, as the dimensions of integrated circuit components shrink to the submicron level, low-resistivity conductive materials and low-dielectric-constant insulating materials are used to obtain appropriate electrical performance from these components.

[0003] The demand for higher density integrated circuits has also imposed requirements on the process sequences used to manufacture integrated circuit components. For example, in processing sequences using conventional photolithography techniques, a layer of energy-sensitive resist is formed on top of a stack of material layers deposited on a substrate. This energy-sensitive resist layer is exposed to an image of a pattern to form a photoresist mask. Subsequently, an etching process is used to transfer the mask pattern to one or more of the material layers in the stack. The chemical etchant used in this etching process is selected to have higher etching selectivity for the material layers in the stack than for the energy-sensitive resist mask. In other words, this chemical etchant etches one or more layers of the material stack at a much faster rate than the energy-sensitive resist. The etching selectivity for one or more material layers in the stack above the resist prevents the energy-sensitive resist from being consumed before the pattern transfer is complete.

[0004] As pattern dimensions decrease, the thickness of the energy-sensitive resist is also reduced accordingly to control pattern resolution. Such thin resist layers may be insufficient to mask the underlying material layer during pattern transfer due to attack by chemical etchants. An intermediate layer called a hard mask (e.g., silicon oxynitride, silicon carbide, or carbon film) is often used between the energy-sensitive resist layer and the underlying material layer, and its higher resistance to chemical etchants facilitates pattern transfer. Hard mask materials that possess both high etching selectivity and fast deposition rates are desired. Due to the shrinking critical dimension (CD), existing hard mask materials lack the target etching selectivity compared to the underlying material (e.g., oxides and nitrides) and are often difficult to deposit.

[0005] Therefore, in this technical field, there is a need for improved hard mask layers and methods for depositing improved hard mask layers. [Overview of the project]

[0006] The embodiments described herein generally relate to the manufacture of integrated circuits. More specifically, the embodiments described herein provide techniques for depositing amorphous carbon films on a substrate. One embodiment provides a method for forming an amorphous carbon film. This method includes depositing an amorphous carbon film on a sublayer positioned on a susceptor in a first processing area. This method further includes forming a doped amorphous carbon film by injecting a dopant or inert species into the amorphous carbon film in a second processing area. The dopant or inert species is selected from carbon, boron, nitrogen, nitrogen dimer, silicon, phosphorus, argon, helium, neon, krypton, xenon, or a combination thereof. This method further includes patterning the doped amorphous carbon film and etching the sublayer.

[0007] In another embodiment, a method for forming an amorphous carbon film is provided. This method comprises depositing an amorphous carbon film on a sublayer positioned on a susceptor in a first processing region. This method further comprises forming a doped amorphous carbon film by injecting a dopant into the amorphous carbon film in a second processing region. The dopant or inert species is selected from carbon, boron, nitrogen, nitrogen dimer, silicon, phosphorus, argon, helium, neon, krypton, xenon, or a combination thereof. This method further comprises patterning the doped amorphous carbon film. This method further comprises etching the sublayer, wherein the doped amorphous carbon film has a refractive index of about 2.1 to about 2.2 at 633 nm.

[0008] In yet another embodiment, a hard mask layer containing an amorphous carbon film is provided. This amorphous carbon film is formed by a plasma-enhanced chemical vapor deposition process followed by a carbon injection process. The dopant or inert species is selected from carbon, boron, nitrogen, nitrogen dimer, silicon, phosphorus, argon, helium, neon, krypton, xenon, or a combination thereof. The amorphous carbon film functions as a hard mask layer in an etching process for use in semiconductor applications.

[0009] In yet another embodiment, a method for forming an amorphous carbon film is provided. This method comprises depositing an amorphous carbon film on a sublayer positioned on a susceptor in a first processing region. This method further comprises forming a doped amorphous carbon film by injecting a dopant or inert species into the amorphous carbon film in a second processing region. The dopant or inert species is selected from carbon, boron, nitrogen, silicon, phosphorus, argon, helium, neon, krypton, xenon, beryllium, germanium, or a combination thereof, where the target temperature during dopant or inert species injection is between approximately -100°C and approximately 550°C. This method further comprises patterning the doped amorphous carbon film and etching the sublayer.

[0010] In yet another embodiment, a method for forming an amorphous carbon film is provided. This method comprises depositing an amorphous carbon film on a sublayer positioned on a susceptor in a first processing region. This method further comprises forming a doped amorphous carbon film by implanting a dopant or inert species into the amorphous carbon film in a second processing region. The dopant or inert species is selected from carbon, boron, nitrogen, silicon, phosphorus, argon, helium, neon, krypton, xenon, beryllium, germanium, or a combination thereof, where the target temperature during dopant or inert species implantation is between approximately -100°C and approximately 550°C. This method comprises patterning the doped amorphous carbon film and etching the sublayer, where the doped amorphous carbon film has a refractive index of approximately 2.1 to approximately 2.2 at 633 nm.

[0011] In yet another embodiment, a method for forming an amorphous carbon film is provided. This method comprises depositing an amorphous carbon film on a sublayer positioned on a susceptor in a first processing region. This method further comprises forming a doped amorphous carbon film by injecting a carbon dopant into the amorphous carbon film in a second processing region, where the target temperature during dopant injection is between approximately -100°C and approximately 550°C. This method comprises patterning the doped amorphous carbon film and etching the sublayer, where the doped amorphous carbon film has a hardness (GPa) of approximately 14 GPa to approximately 22 GPa.

[0012] In yet another embodiment, a method for forming an amorphous carbon film is provided. This method comprises depositing an amorphous carbon film on a lower layer positioned on a susceptor in a first processing region. This method further comprises patterning the amorphous carbon layer. This method further comprises forming a doped and patterned amorphous carbon film by injecting a dopant or inert species into the patterned amorphous carbon film in a second processing region. The dopant or inert species is selected from carbon, boron, nitrogen, silicon, phosphorus, argon, helium, neon, krypton, xenon, beryllium, germanium, or a combination thereof, where the target temperature during dopant or inert species injection is between approximately -100°C and approximately 550°C. This method further comprises etching the lower layer.

[0013] In yet another embodiment, a method for forming an amorphous carbon film is provided. This method comprises depositing an amorphous carbon film on a lower layer positioned on a susceptor in a first processing region. This method further comprises patterning the amorphous carbon layer. This method further comprises forming a doped and patterned amorphous carbon film by injecting a dopant or inert species into the patterned amorphous carbon film in a second processing region. The dopant or inert species is selected from carbon, boron, nitrogen, silicon, phosphorus, argon, helium, neon, krypton, xenon, beryllium, germanium, or a combination thereof, where the target temperature during dopant or inert species injection is between approximately -100°C and approximately 550°C. Injection can be performed at a tilt angle of 0 degrees with a specific species that allows for an increased etching rate of the lower layer, or at tilt angles between 0.1 degrees and 80 degrees and associated twist angles between 0 degrees and 360 degrees. Due to the properties of the species that can reduce the etching rate of the underlying layers depending on the associated inclination angle, ions can penetrate only the hard mask. If the lines and spatial features of the carbon hard mask run in one direction rather than two vertical directions, the injection is divided into two injections, with each injection at half the desired dose, for example, 1.0 × 10⁻⁶. 16 Ions / cm 2 The dose is 5.0 × 10 15 Ions / cm 2 It can be divided into doses of 1.0 × 10. The substrate is injected each time it rotates 180 degrees, and therefore, 1.0 × 10 16 Ions / cm 2 The material is accumulated up to the desired dose. As a result, both sides of the feature area of ​​the carbon hard mask are uniformly injected. This method may further include doping a patterned, undoped amorphous carbon film and etching the underlying layer, where the doped amorphous carbon film has a refractive index of about 2.1 to about 2.2 at 633 nm.

[0014] In yet another embodiment, a method for forming an amorphous carbon film is provided. This method comprises depositing an amorphous carbon film on a sublayer positioned on a susceptor in a first processing region. This method further comprises patterning the amorphous carbon layer. This method further comprises forming a doped and patterned amorphous carbon film by injecting a carbon dopant into the patterned amorphous carbon film in a second processing region, where the target temperature during dopant injection is between approximately -100°C and approximately 550°C. This method further comprises etching the sublayer, where the doped and patterned amorphous carbon film has a hardness (GPa) of approximately 14 GPa to approximately 22 GPa.

[0015] In yet another execution mode, instructions that cause a process to perform the operation of the above-mentioned device and / or method, when executed by the processor, are stored on a non-temporary computer-readable medium.

[0016] To better understand the features of this disclosure described above, a more detailed description of the implementations briefly summarized above can be obtained by referring to the implementations. Some implementations are shown in the accompanying drawings. However, it should be noted that the accompanying drawings only show typical implementations of this disclosure, as this disclosure may permit other equally valid implementations, and therefore should not be considered to limit the scope of this disclosure. [Brief explanation of the drawing]

[0017] [Figure 1] A schematic diagram of the equipment that may be used to implement the execution methods described in this book is shown. [Figure 2] The diagram shows a process flow chart for a method for forming an amorphous carbon hard mask layer on a film stack placed on a substrate, according to one or more embodiments of the present disclosure. [Figure 3A-3H] A schematic cross-sectional view of a substrate structure showing a hard mask formation sequence according to one or more embodiments of this disclosure is shown. [Figure 4] This diagram shows a process flow chart for a method for forming an amorphous carbon hard mask layer on a film stack arranged on a substrate, according to one or more embodiments of the present disclosure. [Figure 5A] The plot shows the in-plane strain-to-film stress (MPa) of an amorphous carbon film formed according to an embodiment of the present disclosure, compared to an amorphous carbon film formed using prior art techniques. [Figure 5B] Figure 5A shows a plot of Young's modulus (GPa) versus film stress (MPa) for the amorphous carbon film. [Figure 6] The following is a process flow diagram of another method for forming an amorphous carbon hard mask layer on a film stack placed on a substrate, according to one or more embodiments of the present disclosure. [Figure 7A-7I] A schematic cross-sectional view of a substrate structure showing a hard mask formation sequence according to one or more embodiments of this disclosure is shown. [Modes for carrying out the invention]

[0018] For ease of understanding, the same reference numerals are used to indicate identical elements common to multiple drawings, where possible. It is assumed that elements and features of one implementation can be usefully incorporated into other implementations without further description.

[0019] The following disclosure describes techniques for depositing diamond-like carbon films on substrates. Specific details are presented in the following specification and Figures 1-7I to fully understand the various embodiments of this disclosure. Other details describing well-known structures and systems often associated with plasma processing and ion implantation are not presented in the following disclosure to avoid unnecessarily obscuring the description of the various embodiments.

[0020] Many of the details, dimensions, angles, and other features shown in the figures are merely illustrative of particular embodiments. Thus, other embodiments can have other details, components, dimensions, angles, and features without departing from the spirit and scope of the disclosure. Further, additional embodiments of the disclosure can be implemented without some of the details described below.

[0021] The embodiments described herein are described below with reference to a PECVD deposition process and an ion implantation process that can be performed using any suitable thin film deposition and implantation system. Examples of suitable systems include the CENTURA® system, which can use a DXZ® process chamber, the PRECISION 5000® system, the PRODUCER® system, the PRODUCER® GT TM system, the PRODUCER® XP Precision TM system, the PRODUCER® SE TM system, the Sym3® process chamber, and the Mesa TM process chamber, all of which are commercially available from Applied Materials, Inc., Santa Clara, California. The ion implantation process can be performed by a beamline or plasma implantation tool. Exemplary systems utilized to perform the implantation process include, for example, the VARIAN VIISta® TRIDENT system, the VARIAN VIISta® Thermion system, the VARIAN VIISta® Medium Current Thermion system, the VIISta® 3000XP system, the VIISta® 900XP system, the VIISta® HCP system, the VIISta® Trident Crion TMThis includes the VIISta® PLAD system. Other tools capable of performing PECVD and / or ion implantation processes may also be adapted to benefit from the executions described herein. Furthermore, any system enabling the PECVD and / or ion implantation processes described herein may be used to its advantage. The descriptions of the apparatus described herein are illustrative and should not be understood or interpreted as limiting the scope of the executions described herein.

[0022] Physical constraints in the miniaturization of integrated circuits have led to the orthogonal extension of integrated circuits onto planar wafer surfaces, i.e., high aspect ratio (HAR) and three-dimensional utilization of device space. Nanofabrication strategies to address dynamic etching selectivity and increasingly stringent manufacturing tolerances have led to a library of hard mask (HM) materials, including silicon, titanium, tungsten, or boron-doped carbon films and dielectric silicon oxide / silicon nitride (ON / OP) films. Combining these materials provides advantages in etching selectivity and patterning down to the 1X node. Innovation in amorphous carbon hard mask materials is desired to achieve the high aspect ratio (HAR) benchmark for next-generation device structures. Unlike metallic and dielectric solutions, amorphous carbon is easily ashed, resulting in high selectivity for the underlying ON / OP hard mask film. Another advantage of amorphous carbon hard masks is their corresponding optical properties. These optical properties are tunable and provide transparency to aligned patterned features, eliminating the need for a partial hard mask opening process. However, current integrated hardware and processes for amorphous carbon hard masks have relatively inferior mechanical properties compared to metal-doped and dielectric hard masks. The etching selectivity of current-generation pure carbon films (e.g., nanocrystalline diamond, ultra-nanocrystalline diamond, diamond-like carbon, and physically vapor-deposited carbon) has been found to be highest in high-sp3 content films similar to diamond hybridization. A long-standing and highly valued problem in diamond-like carbon hard masks is the compressive film stress >1 GPa due to sp3 hybridized carbon, which limits patterning performance due to constraints of lithography overlay and electrostatic chucking.

[0023] Next-generation 3D NAND products with 64x layer stacking applications and a 100:1 aspect ratio require thin films that enable patterning while resisting deformation, and simultaneously demonstrate improved lithography overlays. Diamond-like carbon films combine carbon species-specific etching selectivity with excellent structural integrity. These diamond-like carbon films will only remain competitive if they can further improve mechanical properties (indicated by Young's modulus) by reducing stress and in-plane strain ("IPD") values.

[0024] Some embodiments of this disclosure provide processes that utilize existing hardware with little impact on throughput or execution cost. Some embodiments of this disclosure address the high cost problem of lithography overlays and the high stress associated with low Young's modulus (E). Some embodiments of this disclosure provide a unique process that increases the modulus of amorphous carbon by approximately twofold (e.g., from approximately 64 GPa to approximately 138 GPa) by modifying the plasma deposition mechanism. Ion implantation further improves the Young's modulus of amorphous carbon films by 30% (approximately 180 GPa) and reduces compressive stress by 75% (approximately -1200 to approximately -300 MPa), thereby further improving film properties. Furthermore, the combination of PECVD and ion implantation has resulted in amorphous carbon films with significantly reduced in-plane strain (<3 nanometer overlay error) compared to current-generation pure carbon hard mask films.

[0025] In improving the performance of amorphous carbon hard mask films, a first aspect of this disclosure defines a new process window. This new process window aims to improve the modulus of elasticity while suppressing in-plane strain despite high stress (e.g., approximately -1200 GPa). While not bound by theory, it is believed that these improvements can be achieved by reducing the pressure to increase the plasma sheath size and increasing the process interval to lower the plasma temperature. High sheath potential and Bohm velocity were confirmed by a significant decrease in the deposition rate despite the decrease in synthesis temperature. This leads to the formation of more carbon-to-carbon bonds and a decrease in the hydrogen content in the film. In one embodiment, the measured extinction coefficient at 633 nm after deposition was 0.72. This indicates higher C=C, graphiticity. Furthermore, by reducing the plasma density, the mean free path and collision energy increased, and the uniformity of the ion energy distribution function across the wafer surface was improved. Film properties with a weak plasma that minimizes amorphization due to collisions show increased Young's modulus (E), hardness, and density. While not strictly bound by theory, it is believed that a longer mean free path reduces the target in-plane distortion (IPD) in lithography overlays.

[0026] A second aspect of this disclosure, in-line ion implantation, helps reduce the stress component of amorphous carbon films by up to approximately 75% (e.g., from approximately -1200 to approximately -300 MPa), further improve the Young's modulus (e.g., from approximately 138 to approximately 177 GPa), and make the in-plane strain profile more centripetal. Ion implantation can be performed at a range of temperatures (e.g., from approximately -100°C to approximately 550°C). Lowering the ion implantation temperature of amorphous carbon films has been shown to minimize rearrangement of implanted dopants, and beneficial effects of implantation such as densification, sp3 strengthening, and hydrogen reduction have been confirmed. While not bound by theory, ion implantation is thought to help redistribute local stress and reduce the overall wafer stress to, for example, about 25% of the value after film deposition. To avoid high voltage peaks (HVP) of film improvement saturation, a correct implantation process scheme is developed to optimally increase the modulus while reducing stress, based on the incoming wafer modulus.

[0027] The resulting amorphous carbon film has been shown to exhibit 30–50% improved etching selectivity compared to currently available pure carbon hard mask films, and also meets previous overlay requirements.

[0028] In some embodiments of this disclosure, amorphous carbon films are deposited on bare silicon blanket wafers via plasma-enhanced chemical vapor deposition. In some implementations, the carbon precursor is C3H6, and the plasma profile and uniformity are maintained by argon and helium gases. The scope of this study also encompasses the use of C4H8, C2H6, C2H4, C2H2, CO2, and CF4, among others. The high-frequency RF for this application is 13.56 MHz. Single wafer hardware enables deposition at temperatures up to 650°C, and plasma stability from center to edge is maintained using a gas box, showerhead combination, and planar heater-edge ring configuration. The plasma profile and coupling to the wafer surface can be further tuned by superimposing RF so that it is distributed transversely and orthogonally to the wafer surface.

[0029] In some implementations, ion implantation is performed using a single wafer processing tool. A heat exchanger enables temperature control down to -100°C and the development of low-temperature implantation techniques. The species that yield the high performance described herein are ashingable ions that can maintain the pure carbonity of the film.

[0030] Figure 1 is a schematic cross-sectional view of a plasma processing chamber 100 configured according to various embodiments of the present disclosure. For example, the embodiment of the plasma processing chamber 100 in Figure 1 is described in relation to a PECVD system, but any other plasma processing chamber (including other plasma deposition chambers or plasma etching chambers) may fall within the scope of the embodiment. The plasma processing chamber 100 includes walls 102, a bottom 104, and a chamber lid 124, which together surround a susceptor 105 and a processing area 146. The plasma processing chamber 100 includes a vacuum pump 114, a first RF generator 151, a second RF generator 152, an RF matcher 153, a gas source 154, a top RF current regulator 155, a bottom RF current regulator 157, and a system controller 158, each coupled to the outside of the plasma processing chamber 100 as shown.

[0031] The walls 102 and bottom 104 may include conductive materials such as aluminum or stainless steel. A slit valve opening may be present through one or more of the walls 102. The slit valve opening 206 is configured to facilitate insertion of the substrate 110 into the plasma processing chamber 100 and removal of the substrate 110 from the plasma processing chamber 120. A slit valve configured to seal the slit valve opening may be located either inside or outside the plasma processing chamber 100. For clarity, the slit valve and slit valve opening are not shown in Figure 1.

[0032] The vacuum pump 114 is connected to the plasma processing chamber 100 and configured to adjust the vacuum level within it. As shown in the figure, a valve 116 may be connected between the plasma processing chamber 100 and the vacuum pump 114. The vacuum pump 114 evacuates the plasma processing chamber 100 before substrate processing and removes the processing gas from the processing chamber through the valve 116 during processing. The valve 116 may be adjustable to facilitate the adjustment of the evacuation rate of the plasma processing chamber 100. The evacuation rate through the valve 116 and the gas flow rate entering from the gas source 154 determine the chamber pressure and the residence time of the processing gas within the plasma processing chamber 100.

[0033] The gas source 154 is coupled to the plasma processing chamber 100 via a tube 123 that penetrates the chamber lid 124. The tube 123 is fluidly coupled to a plenum 148 between the chamber lid 106 and a gas distribution showerhead 128 contained within the chamber lid 124. During operation, the processing gas introduced into the plasma processing chamber 100 from the gas source 154 fills the plenum 148 and then passes through gas passages 129 formed in the gas distribution showerhead 128 to uniformly enter the processing area 146. In an alternative implementation, the processing gas may be introduced into the processing area 146 via an inlet and / or nozzle (not shown) attached to the wall 102, in addition to or instead of the gas distribution showerhead 128.

[0034] The susceptor 105 may include any technically feasible device for supporting a substrate (such as the substrate 110 in Figure 1) while it is being processed by the plasma processing chamber 100. In some embodiments, the susceptor 105 is positioned on a shaft 112 configured to raise and lower the susceptor 105. In one embodiment, the shaft 112 and the susceptor 105 may be at least partially formed from, or contain, a conductive material (such as tungsten, copper, molybdenum, aluminum, or stainless steel). Alternatively or additionally, the susceptor 105 may be at least partially formed from, or contain, a ceramic material such as aluminum oxide (Al2O3), aluminum nitride (AlN), or silicon dioxide (SiO2). In embodiments where the plasma processing chamber 100 is a capacitively coupled plasma chamber, the susceptor 105 may be configured to include electrodes. In such an implementation, the metal rod 115 or other conductor is electrically coupled to the electrode 113 and configured to provide part of the grounding path for the RF power delivered to the plasma processing chamber 100. That is, the metal rod 115 allows the RF power supplied to the plasma processing chamber 100 to pass through the electrode 113 and be grounded from outside the plasma processing chamber 100.

[0035] In some embodiments, the electrode 113 is also configured to provide an electrical bias from a DC power supply (not shown) to enable electrostatic clamping of the substrate 110 onto the susceptor 105 during plasma processing. In such embodiments, the susceptor 105 generally includes a body containing one or more ceramic materials, such as the ceramic materials described above, or any other ceramic material suitable for use in an electrostatic chuck. In such embodiments, the electrode 113 may be a mesh, such as an RF mesh, or a perforated sheet of a material made of molybdenum (Mo), tungsten (W), or another material having a coefficient of thermal expansion substantially similar to that of the ceramic material or the material contained in the body of the susceptor 105. The electrode 113 and the gas distribution showerhead 128 together define the boundary of the processing area 146 in which the plasma is formed. For example, during processing, the susceptor 105 and the substrate 110 rise and are positioned near the bottom surface of the gas distribution showerhead 128 (e.g., within 10-30 mm) to form a processing area 146 that is at least partially enclosed.

[0036] The first RF generator 151 is a radio frequency (RF) power supply configured to provide high-frequency power to the discharge electrode 126 at a first RF frequency via an RF matching unit 153. Similarly, the second RF generator 152 is an RF power supply configured to provide high-frequency power to the discharge electrode 126 at a second RF frequency via an RF matching unit 153. In some embodiments, the first RF generator 151 includes an RF power supply capable of generating RF current at high frequency (HF), e.g., about 13.56 MHz. Alternatively or additionally, the first RF generator 151 includes a VHF generator capable of generating VHF power (e.g., VHF power with frequencies between about 20 MHz and 200 MHz or higher). In contrast, the second RF generator 152 includes an RF power supply capable of generating so-called low-frequency (LF) RF, e.g., RF current at about 350 kHz. Alternatively or additionally, the second RF generator 152 includes an RF generator capable of generating RF power at frequencies between approximately 1 kHz and approximately 1 MHz. The first RF generator 151 and the second RF generator 152 are configured to facilitate the generation of plasma between the discharge electrode 126 and the susceptor 105.

[0037] The discharge electrode 126 may include a processing gas distribution element, such as a gas distribution showerhead 128 (as shown in Figure 1), and / or an array of gas injection nozzles. Through these, the processing gas is introduced into the processing region 146. The discharge electrode 126, i.e., the gas distribution showerhead 128, may be oriented substantially parallel to the surface of the substrate 110, and capacitively couples the plasma source output to the processing region 146 located between the substrate 110 and the gas distribution showerhead 128.

[0038] The RF matcher 153 can be any technically feasible impedance matching device coupled between the first RF generator 151 and the powered electrode of the plasma processing chamber 100, i.e., the gas distribution showerhead 128. The RF matcher 153 is also coupled between the second RF generator 152 and the powered electrode of the plasma processing chamber 100. The RF matcher 153 is configured to match the load impedance (plasma processing chamber 100) to the source or internal impedance of the drive source (first RF generator 151, second RF generator 152) to enable maximum transmission of RF power from the first RF generator 151 and the second RF generator 152 to the plasma processing chamber 100.

[0039] The upper isolator 107, the adjustment ring 108, and the lower isolator 109 form part of the wall 102. The upper isolator 107 is configured to electrically isolate the adjustment ring 108, which is formed from a conductive material, from a backing plate 106 that is energized with RF power during operation in some embodiments. Thus, the upper isolator 107 is positioned between the backing plate 106 and the adjustment ring 108, preventing RF power from being energized to the adjustment ring 108 via the backing plate 106. In some embodiments, the upper isolator 107 is configured as a ceramic ring or ring band positioned concentrically around the processing area 146. Similarly, the lower isolator 109 is configured to electrically isolate the adjustment ring 108 from the wall 102. The wall 102 is typically formed from a conductive material and can therefore function as a grounding path for a portion of the RF power delivered to the plasma processing chamber 100 during processing. Thus, the lower isolator 109 allows the adjustment ring 108 to be part of a different grounding path for the RF power delivered to the plasma processing chamber 100, distinct from that of the wall 102. In some embodiments, the upper isolator 107 is configured as a ceramic ring or to include a ceramic ring positioned concentrically around the processing area 146.

[0040] The regulating ring 108 is positioned between the upper isolator 107 and the lower isolator 109, is formed from a conductive material, and is located adjacent to the processing area 146. For example, in some embodiments, the regulating ring 108 is formed from a suitable metal such as aluminum, copper, titanium, or stainless steel. In some embodiments, the regulating ring 108 is a metal ring or ring band that is positioned concentrically around the susceptor 105 and the substrate 110 during processing of the substrate 110. Furthermore, the regulating ring 108 is electrically coupled to ground via a conductor 156 through a top RF current regulator 155, as shown in the figure. Thus, the regulating ring 108 is not a powered electrode, but is generally located outside and around the processing area 146. In one example, the regulating ring 108 is positioned in a plane substantially parallel to the substrate 110 and is part of the grounding path for the RF energy used to form plasma within the processing area 146. As a result, an additional RF ground path 141 is established between the gas distribution showerhead 128 and ground via the top RF current regulator 155. Thus, by changing the impedance of the top RF current regulator 155 at a specific frequency, the impedance to the RF ground path 141 at that specific frequency changes, resulting in a change in the RF electric field coupled to the regulating ring 108 at that frequency. Therefore, the shape of the plasma in the processing region 146 can be independently modulated along the + / -X and Y directions with respect to the RF frequencies associated with either the first RF generator 151 or the second RF generator 152. That is, the shape, volume, or uniformity of the plasma formed in the processing region 146 can be independently modulated across the surface of the substrate 110 for multiple RF frequencies, for example, by using the regulating ring 108 or perpendicularly between the substrate 110 and the gas distribution showerhead 128 using the electrode 113.

[0041] The system controller 158 is configured to control the components and functions of the plasma processing chamber 100, including the vacuum pump 114, the first RF generator 151, the second RF generator 152, the RF matcher 153, the gas source 154, the top RF current regulator 155, and the bottom RF current regulator 157. Thus, the system controller 158 receives sensor inputs, such as voltage-current inputs, from the top RF current regulator 155 and the bottom RF current regulator 157 and transmits control outputs for the operation of the plasma processing chamber 100. The functions of the system controller 158 may include any technically feasible implementation, including via software, hardware, and / or firmware, and may be divided among multiple separate controllers associated with the plasma processing chamber 100.

[0042] While not bound by theory, it is believed that the properties of a deposited film can be tuned by delivering RF power of different frequencies to the processing area of ​​the plasma processing chamber during the plasma-enhanced deposition process. For example, tuned to low-frequency RF plasma power and / or frequency delivered to the processing area 146, i.e., forming an RF plasma in the range of 1 kHz to 1 MHz, may be beneficial for tuning some properties of the deposited film, such as film stress, while tuned to high-frequency RF plasma power and / or frequency delivered to the processing area 146, i.e., forming an RF plasma in the range of 1 MHz to 200 MHz, may be beneficial for tuning other properties of the deposited film, such as thickness uniformity. According to various embodiments of this disclosure, the tuner allows for independent control of the flow of RF current within the plasma processing chamber 100 at multiple RF frequencies. In some embodiments, such tuners are used at multiple locations within the plasma processing chamber 100, i.e., top RF current tuner 155 and bottom RF current tuner 157.

[0043] As described above, the top RF current regulator 155 is electrically coupled to the regulating ring 108 and terminated to ground, thereby providing a controllable RF grounding path 141 to the plasma processing chamber 100. Similarly, the bottom RF current regulator 157 is electrically coupled to the metal rod 115 and terminated to ground, thereby providing a different controllable RF grounding path 142 to the plasma processing chamber 100. As described herein, the top RF current regulator 155 and the bottom RF current regulator 157 are each configured to control the flow of RF current to ground at multiple RF frequencies. Thus, the distribution of RF current at a first RF frequency between the regulating ring 108 and the metal rod 115 can be controlled independently of the distribution of RF current at a second RF frequency between the regulating ring 108 and the metal rod 115.

[0044] Plasma 180 is formed in the processing region 146 between electrode 113 and discharge electrode 126. The distance or "gap" between the bottom surface of electrode 113 and the top surface of susceptor 105 is represented by "x".

[0045] Other deposition chambers may also benefit from this disclosure, and the parameters listed above may vary depending on the specific deposition chamber used to form the amorphous carbon layer. Other deposition chambers may be larger or smaller in volume and require gas flow rates greater or less than those described for the deposition chambers available from Applied Materials, Inc. In one embodiment, the boron-carbon film is PRODUCER® XP Precision, commercially available from Applied Materials, Inc., Santa Clara, California. TM It can be deposited using a processing system.

[0046] The atomic percentage of dopant or inactive species incorporation in an amorphous carbon film is calculated as follows: (dopant concentration (cm³) -3 ) is predicted for a carbon film of a certain density, 1 cm -3(Divided by the number of carbon atoms per atom). An amorphous carbon film may contain at least 0.1, 1, or 10 atomic percentages of dopants or inert species. An amorphous carbon film may contain up to 1, 10, or 30 atomic percentages of dopants or inert species. An amorphous carbon film may contain about 1 to about 30 atomic percentages of dopants or inert species. An amorphous carbon film may contain about 10 to about 30 atomic percentages of dopants or inert species. An amorphous carbon film may contain at least 3, 5, or 10 atomic percentages of hydrogen. An amorphous carbon film may contain up to 5, 10, or 15 atomic percentages of hydrogen. An amorphous carbon film may contain about 3 to about 15 atomic percentages of hydrogen.

[0047] In one embodiment where the dopant is carbon, the atomic percentage of carbon incorporation in the amorphous carbon film is calculated as follows: ((C / (H+C))%). The amorphous carbon film may contain at least 85, 90, or 95 atomic percentages of carbon. The amorphous carbon film may contain up to 90, 95, or 97 atomic percentages of carbon. The amorphous carbon film may contain about 85 to about 97 atomic percentages of carbon. The amorphous carbon film may contain about 90 to about 97 atomic percentages of carbon. The amorphous carbon film may contain at least 3, 5, or 10 atomic percentages of hydrogen. The amorphous carbon film may contain up to 5, 10, or 15 atomic percentages of hydrogen. The amorphous carbon film may contain about 3 to about 15 atomic percentages of hydrogen.

[0048] In general, the following exemplary deposition process parameters may be used for the PECVD portion of the amorphous carbon film deposition process described herein. The process parameters may range from about 100°C to about 700°C (e.g., between about 300°C and about 700°C). The chamber pressure may range from about 1 Torr to about 20 Torr (between about 2 Torr and about 8 Torr; or between about 5 Torr and about 8 Torr). The hydrocarbon-containing gas flow rate may range from about 100 sccm to about 5,000 sccm (e.g., between about 100 sccm and about 2,000 sccm; or between about 160 sccm and about 500 sccm). The dilution gas flow rates may range individually from about 0 sccm to about 5,000 sccm (e.g., between about 2,000 sccm and about 4,080 sccm). The flow rate of the inert gas may be individually in the range of about 0 sccm to about 10,000 sccm (e.g., about 0 sccm to about 2,000 sccm; or about 200 sccm to about 2,000 sccm). The RF power may be between 1,000 watts and 3,000 watts. The gap between the top surface of the substrate 110 and the gas distribution showerhead 128 may be set to about 200 mils to about 1,000 mils (e.g., between about 200 mils and about 600 mils; between about 300 mils and about 1,000 mils; or between about 400 mils and about 600 mils). The amorphous carbon film may be deposited to have a thickness between about 10 Å and about 50,000 Å (e.g., between about 300 Å and about 3,000 Å; or between about 500 Å and about 1,000 Å). The above process parameters provide typical deposition rates for amorphous carbon films ranging from approximately 100 Å / min to approximately 5,000 Å / min (e.g., approximately 1,400 Å / min to approximately 3,200 Å / min) and can be performed on 300 mm substrates in a deposition chamber available from Applied Materials, Inc. in Santa Clara, California.

[0049] As-deposited amorphous carbon films before injection may have a refractive index (n) (at 633 nm) greater than 1.9, for example, about 2.2 (e.g., about 2.1 to about 2.5). As-deposited amorphous carbon films may have a k value (k(at 633 nm)) less than 1.0, for example, (e.g., about 0.6 to about 0.8). As-deposited amorphous carbon films may have a Young's modulus (GPa) of about 50 to about 200 GPa (e.g., about 60 to about 140 GPa; or about 100 to about 140 GPa). As-deposited amorphous carbon films may have a hardness (GPa) of about 10 GPa to about 22 GPa (e.g., about 10 GPa to about 15 GPa; or about 12 GPa to about 14 GPa). As-deposited amorphous carbon films can have stresses (MPa) ranging from approximately -1300 MPa to approximately 0 MPa (e.g., approximately -1300 MPa to approximately -250 MPa; approximately -1250 MPa to approximately -1000 MPa). As-deposited amorphous carbon films can have densities (g / cc) ranging from approximately 1.7 g / cc to approximately 1.87 g / cc (e.g., approximately 1.74 g / cc to approximately 1.85 g / cc).

[0050] As-deposited amorphous carbon films after carbon injection may have a refractive index (n) (at 633 nm) greater than 2.04, for example, about 2.2 (e.g., about 2.1 to 2.2). As-deposited amorphous carbon films may have a k value (k(at 633 nm)) less than 1.0, for example, (e.g., about 0.5 to about 0.8; about 0.6 to about 0.7). As-deposited amorphous carbon films after injection may have a Young's modulus (GPa) of about 70 to about 200 GPa (e.g., about 120 to about 180 GPa; or about 130 to about 170 GPa). As-deposited amorphous carbon films after injection may have a hardness (GPa) of about 14 GPa to about 22 GPa (e.g., about 15 GPa to about 20 GPa; or about 16 GPa to about 19 GPa). As-deposited amorphous carbon films after injection may have stresses (MPa) ranging from approximately -600 MPa to approximately 0 MPa (e.g., approximately -400 MPa to approximately 0 Pa; approximately -350 MPa to approximately 0 MPa). As-deposited amorphous carbon films may have densities (g / cc) greater than 1.9 g / cc, for example, approximately 2.1 g / cc (e.g., approximately 1.95 g / cc to approximately 2.1 g / cc).

[0051] Figure 2 shows a flowchart of Method 200 for forming a diamond-like carbon layer on a film stack disposed on a substrate, according to one or more embodiments of the present disclosure. Figures 3A-3H show schematic cross-sectional views of a substrate structure illustrating the hard mask formation sequence according to Method 200. Method 200 is described below in relation to a hard mask layer that can be formed on a film stack, which is used to manufacture a stepped structure in a film stack for a three-dimensional semiconductor device; however, Method 200 may also be advantageously used in other device manufacturing applications. Furthermore, it should be understood that the operations shown in Figure 2 may be performed simultaneously and / or in an order different from that shown in Figure 2.

[0052] Method 200 begins in operation 210 by positioning the substrate 302 within a processing chamber, such as the plasma processing chamber 100 shown in Figure 1. The substrate 302 may be the substrate 101 shown in Figure 1. The substrate 302 may also be part of a film stack 300 formed thereon.

[0053] In one embodiment, the surface of the substrate 110 shown in Figure 1 is substantially flat. Alternatively, the substrate 110 may have a patterned structure. For example, it may have a surface with trenches, holes, or vias formed internally. The substrate 110 may have a substantially flat surface with a target stepped structure formed on or inside the surface. Although the substrate 110 is shown as a single unit, it may contain one or more materials used to form a semiconductor device (such as metal contacts, trench isolation, gates, bit lines, or other arbitrary interconnection features). The substrate 110 may include one or more metal layers, one or more dielectric materials, semiconductor materials, and combinations thereof, which are used to manufacture a semiconductor device. For example, the substrate 110 may include oxide materials, nitride materials, polysilicon materials, etc., depending on the application. In one embodiment targeted at memory applications, the substrate 110 may include silicon substrate material, oxide material, and nitride material (with or without polysilicon present between them).

[0054] In another embodiment, the substrate 110 may include multiple alternating oxide and nitride materials (i.e., oxide-nitride-oxide (ONO)) deposited on the surface of the substrate 110 (not shown). In various realizations, the substrate 110 may include alternating multiple oxide and nitride materials, one or more oxide or nitride materials, polysilicon or amorphous silicon materials, oxides alternating with amorphous carbon, oxides alternating with polysilicon, undoped silicon alternating with doped silicon, undoped polysilicon alternating with doped polysilicon, or undoped amorphous silicon alternating with doped amorphous silicon. The substrate 110 may be any substrate or material surface on which the film treatment is performed. For example, the substrate 110 may be made of materials such as crystalline silicon, silicon oxide, silicon oxynitride, silicon nitride, strained silicon, silicon germanium, tungsten, titanium nitride, 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, sapphire, low dielectric constant dielectrics, and combinations thereof.

[0055] The film stack 300 includes a substrate 302 and an underlying layer 304. The underlying layer 304 used herein includes any layer placed beneath an amorphous carbon hard mask. For example, an amorphous carbon hard mask 306 may be placed directly above the underlying layer 304 such that the amorphous carbon hard mask 306 and the underlying layer 304 are in physical contact with each other. In one embodiment, the underlying layer 304 includes a single layer. In another embodiment, the underlying layer 304 includes a dielectric stack.

[0056] In operation 220, as shown in Figure 3B, an amorphous carbon mask 306 is formed on a lower layer 304 positioned above the substrate 302. The amorphous carbon hard mask 306 is deposited above the lower layer 304 by a blanket deposition process. In some embodiments, the amorphous carbon hard mask 306 is deposited according to method 400 as shown in the process flow diagram of Figure 4. The amorphous carbon hard mask 306 may be deposited to a thickness corresponding to the subsequent etching requirements of the lower layer 304. In one example, the amorphous carbon hard mask has a thickness between about 0.5 μm and about 1.5 μm, for example, about 1.0 μm.

[0057] In operation 230, the ion implantation process dops the amorphous carbon hard mask 306 with a dopant to form a doped amorphous carbon hard mask 312, as shown in Figure 3C. Any suitable doping technique may be used. In one implementation, a plasma immersion ion implantation technique is employed to implant the dopant or inert species. In one implementation, a beamline implantation technique is employed to implant the dopant or inert species. In one implementation, a conformal doping technique such as plasma doping (PLAD) may be employed to implant the dopant or inert species.

[0058] Suitable ionic species can be generated from various precursor materials, such as carbon, boron, nitrogen, silicon, phosphorus, helium, argon, neon, krypton, xenon, beryllium, and germanium-containing materials. In one embodiment, the dopant or inert species is selected from carbon, boron, nitrogen, silicon, phosphorus, argon, helium, neon, krypton, xenon, beryllium, germanium, or combinations thereof. An example of a carbon-containing precursor gas is CH4. In one embodiment, various precursor materials can be generated from combinations of precursor materials, for example, CH4 / N2, CH4 / He, N2 / He, CH4 / Ne, CH4 / Ar, CH4 / Ne, CH4 / Kr, or CH4 / Xe.

[0059] In the schematic diagram, ions 310 collide with the amorphous carbon hard mask 306, largely penetrating it to form a doped amorphous carbon hard mask 312 into which dopants or inert species are implanted. Ions 310 penetrate the amorphous carbon hard mask 306 to varying depths, depending on the type and size of the ions, as well as the power and bias used to activate the ions 310. The species of ions 310 can be adjusted to provide increased etching selectivity of the underlying layer 304. Thus, the implanted species can be any monomer or molecular ion adapted to enhance the etching selectivity of the amorphous carbon hard mask 306.

[0060] The ion implantation process can be carried out by a beamline or plasma implantation tool. Exemplary systems used to carry out the implantation process include, for example, the VARIAN VIISta® Trident system, VARIAN VIISta® Thermion system, VARIAN VIISta® Medium Current Thermion system, VIISta® 3000XP system, VIISta® 900XP system, VIISta® HCP system, and VIISta® PLAD system, all available from Applied Materials, Inc. in Santa Clara, California. While the above systems have been described, systems from other manufacturers may also be used to carry out the ion implantation process.

[0061] In one implementation, the ion implantation process implants dopants or inert species into an amorphous carbon hard mask 306. The dopants or inert species are selected from carbon, boron, nitrogen, silicon, phosphorus, argon, helium, neon, krypton, beryllium, germanium, xenon, or combinations thereof. In one implementation, for 3D NAND applications where the carbon hard mask thickness ranges from 10 kÅ to 50 kÅ, the implantation energy used to energize the dopant is between approximately 60 keV and approximately 300 keV (single or multiple implantation energies may be applied). As an example of carbon implantation, an energy of 300 keV modifies approximately 8 kÅ of the carbon hard mask. Multiple implantation energies may be applied to modify the carbon hard mask. For example, multiple energies of 60 keV, 120 keV, 180 keV, 240 keV, 300 keV, or several variations thereof may be applied. The selection of injection species and multiple energies will depend on the type of dopant used, the type of material used as the amorphous carbon hard mask 306, and the required uniform thickness modification of the carbon hard mask. In other implementations, for other technologies such as DRAM or logic or emerging memory technologies, where the carbon hard mask thickness may range from 500 Å to 4 kÅ, the injection energy used to energize the dopant will be between approximately 1 keV and approximately 60 keV (e.g., between approximately 5 keV and approximately 60 keV; between approximately 1 keV and approximately 15 keV; between approximately 10 keV and approximately 35 keV; between approximately 20 keV and approximately 30 keV; or between approximately 20 keV and approximately 25 keV), depending on the type of dopant used, the type of material used as the amorphous carbon hard mask 306, and the target injection depth.

[0062] In one implementation, for 3D NAND applications where the thickness of the carbon hard mask may range from 10 kÅ to 50 kÅ, the ion dose (ions / cm²) is considered. 2 ) is approximately 1 × 10⁻¹⁶, depending on the type of dopant used, the type of material used as amorphous carbon hard mask 306, and the target injection depth. 13 Ions / cm 2and approximately 5 x 10 15 Ions / cm 2 Between (for example, approximately 1 x 10 14 Ions / cm 2 and approximately 3 x 10 15 Ions / cm 2 Between; approximately 5 x 10 14 Ions / cm 2 and approximately 2 x 10 15 Ions / cm 2 Between;). In another implementation, for DRAM or other techniques, such as logic or emerging memory technologies, where the thickness of the carbon hard mask may range from 500 Å to 4 kÅ, the ion dose (ions / cm²) is... 2 ) is approximately 5 × 10 depending on the type of dopant used, the type of material used as amorphous carbon hard mask 306, and the target injection depth. 13 Ions / cm 2 and approximately 5 x 10 16 Ions / cm 2 Between (for example, approximately 1 x 10 14 Ions / cm 2 and approximately 5 x 10 16 Ions / cm 2 Between; approximately 5 x 10 14 Ions / cm 2 and approximately 2 x 10 16 Ions / cm 2 Between; approximately 1 x 10 15 Ions / cm 2 and approximately 1 x 10 16 Ions / cm 2 It is between these two points.

[0063] In one implementation of the PLAD injection technique, the injection energy used to energize the dopant or inert species is approximately 1 × 10⁻¹⁶. 15 Ions / cm 2 and approximately 5 x 10 17 Ions / cm 2 Between (for example, approximately 3 x 10 15 Ions / cm 2 and approximately 3 x 10 17 Ions / cm 2 Between; approximately 5 x 10 15 Ions / cm 2 and approximately 5 x 10 16Ions / cm 2 Between; approximately 5 x 10 15 Ions / cm 2 and approximately 2 x 10 16 Ions / cm 2 Between; or approximately 5 x 10 15 Ions / cm 2 and approximately 1 x 10 16 Ions / cm 2 In the ion dose range (between), it is between approximately 1 kV and approximately 15 kV (for example, between approximately 1 kV and approximately 15 kV; between approximately 1 kV and approximately 15 kV; between approximately 2 kV and approximately 12 kV; between approximately 4 kV and approximately 10 kV; or between approximately 20 kV and approximately 25 kV). In one embodiment where the dopant is helium, the injection energy used to energize the dopant is approximately 1 × 10⁻¹⁶ 15 Ions / cm 2 and approximately 3 x 10 17 Ions / cm 2 The ion dose range is between approximately 1 kV and approximately 15 kV.

[0064] In one implementation, the target temperature is between approximately -100°C and approximately 550°C (e.g., between approximately -100°C and approximately 200°C; between approximately -100°C and approximately 0°C; between approximately -100°C and approximately 50°C; between approximately 0°C and approximately 100°C; or between approximately 150°C and approximately 550°C). In another implementation, the target temperature is between approximately -100°C and approximately 500°C (e.g., between approximately -100°C and approximately 200°C; between approximately -100°C and approximately 0°C; between approximately -100°C and approximately 50°C; between approximately 0°C and approximately 50°C; or between approximately 50°C and approximately 400°C). In one example, when low-temperature injection is performed, the target injection temperature is between approximately -100°C and approximately 0°C. In another example, when room-temperature injection is performed, the target injection temperature is between approximately 10°C and approximately 100°C. In yet another example, when high-temperature injection is performed, the target injection temperature is approximately 150°C to 550°C.

[0065] In general, increasing the hardness of the amorphous carbon hard mask 306 reduces the bending of lines in the high aspect ratio structure of the underlying layer 304 after the amorphous carbon hard mask 306 is opened. The injected ions 310 are thought to extract residual hydrogen atoms from the dangling carbon-hydrogen bonds of the amorphous carbon hard mask 306, forming carbide structures within the amorphous carbon hard mask 306. These carbide structures indicate increased hardness compared to an undoped hard mask. Furthermore, the injected ions 310 are thought to occupy interstitial voids present within the amorphous carbon hard mask 306, resulting in an increased density of the amorphous carbon hard mask 306. Increased density further enhances the mechanical integrity of the amorphous carbon mask 306.

[0066] In one embodiment, the film stack 300 is heat-treated following the ion implantation process. Appropriate post-ion implantation heat treatments include UV treatment, thermal annealing, and laser annealing. Heat treatment of the doped amorphous carbon hard mask 312 further incorporates the implanted ions 310 into the framework of the doped amorphous carbon hard mask 312. For example, the implanted ions 310 may be redistributed within the doped amorphous carbon hard mask 312 to form a more uniform doping profile. The heat treatment is thought to increase the interaction and binding between the doped amorphous carbon hard mask 312 and the implanted ions 310. The redistribution and binding of the implanted ions 310 may function to further increase the hardness, density, and etching selectivity of the doped amorphous carbon hard mask 312. In one embodiment, the annealing process is carried out in a plasma treatment chamber, such as a plasma treatment chamber 100. In another execution mode, the annealing process is performed in a separate annealing chamber.

[0067] In operation 240, a patterned photoresist layer 320 is formed on top of a doped amorphous carbon hard mask 312, which is doped with a dopant or inert species, as shown in Figure 3D. Features or patterns can be transferred from the photomask to the photoresist layer 320 using an energy source such as light energy. In one embodiment, the photoresist layer 320 is a polymer material, and the patterning process is carried out by a 193 nanometer immersion photolithography process or other similar photolithography process. Similarly, a laser may also be used to carry out the patterning process.

[0068] In operation 250, the doped amorphous carbon hard mask 312 is opened, for example, by a plasma etching process to form a doped and patterned amorphous carbon hard mask 322, as shown in Figure 3E. The plasma etching process may be carried out in a chamber similar to the chamber described with respect to Figure 3C.

[0069] In operation 260, the photoresist layer 320 is removed, as shown in Figure 3F. The photoresist layer 320 can be removed by various advantageous photoresist removal processes.

[0070] In operation 270, the underlying layer 304 is etched, as shown in Figure 3G. The etching of the underlying layer 304 may be carried out in a plasma processing chamber, such as the chamber and system described with respect to Figure 1B. An etchant, such as carbon fluoride, removes the exposed portion of the underlying layer 304. The active species of the etchant do not substantially react with the material of the doped and patterned amorphous carbon hard mask 322, the implanted ions 310. Therefore, the etchant is selective for the underlying layer 304 material. Suitable examples of etchants include, among others, CF4, CHF3, HBr, BCl3, and Cl2. The etchant may be supplied with an inert carrier gas.

[0071] In operation 280, the doped and patterned amorphous carbon hard mask 322 is removed. The doped and patterned amorphous carbon hard mask 322 can be removed by any favorable hard mask removal process. In one example, oxygen plasma is used to remove the doped and patterned amorphous carbon hard mask 322. The resulting film stack 300 includes an underlayer 304 in which features 324, such as high aspect ratio features, are formed. The film stack 300 can then be subjected to further processing to form a functional semiconductor device.

[0072] Figure 4 is a process flow diagram showing one execution of method 400 for depositing an amorphous carbon film according to the execution described herein. In one execution, method 400 may be used to deposit an amorphous carbon film in operation 220. Method 400 is initiated in operation 410 by providing a substrate in the processing area of ​​a processing chamber. The processing chamber may be the plasma processing chamber 100 shown in Figure 1. The substrate may be the substrate 110 shown in Figure 1, or the substrate 302 shown in Figures 3A to 3H.

[0073] In operation 420, a hydrocarbon-containing mixed gas is flowed into the processing area 146. The hydrocarbon-containing mixed gas may be flowed from a gas source 154 through a gas distribution showerhead 128 into the processing area 146. The mixed gas may contain at least one hydrocarbon source and / or carbon-containing source. The mixed gas may further contain an inert gas, a diluent gas, a nitrogen-containing gas, or a combination thereof. The hydrocarbon source and / or carbon-containing source may be any liquid or gas. In one example, the precursor is a vapor at room temperature, which simplifies the hardware for metering, control, and delivery of the material to the chamber.

[0074] In one embodiment, the hydrocarbon source is a gaseous hydrocarbon, such as a straight-chain hydrocarbon. In one embodiment, the hydrocarbon compound is C x H yIt has the general formula, where x is in the range of 1 to 20 and y is in the range of 1 to 20. In one embodiment, the hydrocarbon compound is an alkane. Suitable hydrocarbon compounds include, for example, methane (CH4), acetylene (C2H2), ethylene (C2H4), ethane (C2H6), propylene (C3H6), and butylene (C4H8), cyclobutane (C4H8), and methylcyclopropane (C4H8). Suitable butylenes include 1-butene, 2-butene, and isobutylene. Other suitable carbon-containing gases include carbon dioxide (CO2) and carbon tetrafluoride (CF4). In one example, C3H6 is preferred because it forms a more suitable intermediate species that allows for improved surface mobility.

[0075] In particular, appropriate diluent gases such as helium (He), argon (Ar), hydrogen (H2), nitrogen (N2), ammonia (NH3), or combinations thereof may be added to the gas mixture. Ar, He, and N2 are used to control the density and deposition rate of the amorphous carbon layer. In some cases, the addition of N2 and / or NH3 may be used to control the hydrogen ratio of the amorphous carbon layer, as described later. Alternatively, diluent gases may not be used during deposition.

[0076] A nitrogen-containing gas may be supplied to the plasma processing chamber 100 along with a hydrocarbon-containing mixed gas. Suitable nitrogen-containing compounds include, for example, pyridine, aliphatic amines, amines, nitriles, ammonia, and similar compounds.

[0077] An inert gas such as argon (Ar) and / or helium (He) may be supplied into the plasma processing chamber 100 along with a hydrocarbon-containing mixed gas. Other inert gases such as nitrogen (N2) and nitric oxide (NO) may also be used to control the density and deposition rate of the amorphous carbon layer. Furthermore, a wide variety of other processing gases may be added to the mixed gas to modify the properties of the amorphous carbon material. In one embodiment, the processing gas may be a reactive gas (such as hydrogen (H2), ammonia (NH3), a mixture of hydrogen (H2) and nitrogen (N2), or a combination thereof). The addition of H2 and / or NH3 may be used to control the hydrogen ratio (e.g., carbon-to-hydrogen ratio) of the deposited amorphous carbon layer. The ratio of hydrogen present in the amorphous carbon film controls the layer properties (such as reflectance).

[0078] Optionally, in operation 430, the pressure within the processing area is stabilized for a predetermined RF-on delay time period. The predetermined RF-on delay time period is a fixed-time delay defined as the period between the ingestion of the hydrocarbon-containing gas mixture into the processing area and the collision or generation of the plasma in operation 430. Any appropriate fixed-time delay may be used to achieve the target conditions. The length of the RF-on delay period is typically selected so that the hydrocarbon-containing gas mixture or carbon-containing gas mixture does not begin to thermally decompose, or substantially begins to thermally decompose, within the processing area.

[0079] In operation 440, an RF plasma is generated in the processing area to deposit an amorphous carbon film, such as an amorphous carbon hard mask 306. The plasma is formed by capacitive or inductive means and can be applied by coupling RF power to a precursor gas mixture. The RF power is dual-frequency RF power, having high-frequency and low-frequency components. The RF power is typically applied at power levels between about 50 W and about 2,500 W (e.g., between about 2,000 W and about 2,500 W), which may be all high-frequency RF power (e.g., a frequency of about 13.56 MHz) or a mixture of high-frequency and low-frequency power (e.g., a frequency of about 300 kHz). For many applications, the plasma is maintained for a period of time to deposit an amorphous carbon layer having a thickness between about 100 Å and about 5,000 Å. Once the target thickness of the amorphous carbon film is reached, the flow of the hydrocarbon-containing gas mixture may be stopped. The process of operation 440 may be executed simultaneously, sequentially, or partially overlapping with the processes of operations 420 and 430.

[0080] In any of the PECVD executions described herein, during the deposition of the amorphous carbon film, the chamber, wafer, or both may be maintained at a temperature between approximately 200°C and approximately 700°C (e.g., between approximately 400°C and approximately 700°C; or between approximately 500°C and approximately 700°C). The chamber pressure may range from approximately 1 Torr to approximately 10 Torr (e.g., between approximately 2 Torr and approximately 8 Torr; or between approximately 4 Torr and approximately 8 Torr). The distance between the susceptor and the gas distribution showerhead (i.e., the "gap") may be set between approximately 200 mils and approximately 1,000 mils (e.g., between approximately 200 mils and approximately 600 mils; between approximately 300 mils and approximately 1,000 mils; or between approximately 400 mils and approximately 600 mils).

[0081] Amorphous carbon films can be deposited to have thicknesses between approximately 10 Å and approximately 50,000 Å (for example, between approximately 300 Å and approximately 30,000 Å; between approximately 500 Å and approximately 1,000 Å). Excess treatment gases and by-products derived from the deposition of the season layer can then be removed from the treatment area by performing an optional purging / discharge process.

[0082] Figure 5A shows plots of in-plane strain versus film stress (MPa) for amorphous carbon films (520, 522, and 530, 532) formed according to embodiments of the present disclosure, compared with amorphous carbon films (510, 512, and 514) formed using prior art techniques. Note that the amorphous carbon films (520, 522, and 530, 532) formed according to embodiments of the present disclosure are shown before carbon dopant implantation. Figure 5B shows plots of Young's modulus (GPa) versus film stress (MPa) for the amorphous carbon films of Figure 5A. As shown in Figures 5A-5B, amorphous carbon films (520, 522, and 530, 532) formed according to embodiments described herein achieved low in-plane strain and improved modulus despite high stress (e.g., -1200 MPa). The subsequent carbon dopant injection process described herein reduced the compressive film stress by approximately four times and improved the elastic modulus by approximately 1.4 times.

[0083] Figure 6 shows a flow chart of Method 600 for forming a diamond-like carbon layer on a film stack placed on a substrate, according to one or more embodiments of the present disclosure. Figures 7A-7I show schematic cross-sectional views of a substrate structure illustrating the hard mask formation sequence according to Method 600. Method 600 and Figures 7A-7I illustrate post-patterning implantation, in which an amorphous carbon film is implanted after the amorphous carbon film has been patterned. Post-patterning implantation can be performed at an implantation inclination angle of 0 degrees, or at some angle into the amorphous carbon film, at a relevant twist angle from 0 degrees to about 360 degrees, allowing ions to penetrate only the hard mask. In one example, if the lines and spatial features of the carbon hard mask run in one direction rather than two vertical directions, the implantation can be divided into two implantations, with each implantation at half the desired dose, for example, 1 × 10⁻⁶ 16 Ions / cm 2 The dose is 5.0 × 1015 Ions / cm 2 It can be divided into doses. The substrate is injected each time it rotates 180 degrees, and therefore, 1 × 10 16 Ions / cm 2 The desired dose is accumulated. As a result, both sides of the feature area of ​​the carbon hard mask are uniformly injected. Below, Method 200 is described in relation to a hard mask layer that can be formed on a film stack, which is used to manufacture a stepped structure in a film stack for a three-dimensional semiconductor device, but Method 600 may also be advantageously used in other device manufacturing applications. Furthermore, it should be understood that the operations shown in Figure 6 may be performed simultaneously and / or in an order different from that shown in Figure 6.

[0084] Method 600 begins in operation 610 by positioning the substrate 702 within a processing chamber, such as the plasma processing chamber 100 shown in Figure 1. The substrate 702 may be the substrate 101 shown in Figure 1. The substrate 702 may be part of a film stack 700 having additional layers formed thereon.

[0085] In one embodiment, the surface of the substrate 702 shown in Figure 1 is substantially flat. Alternatively, the substrate 702 may have a patterned structure. For example, it may have a surface with trenches, holes, or vias formed internally. The substrate 702 may have a substantially flat surface with a target stepped structure formed on or inside the surface. Although the substrate 702 is shown as a single unit, it may contain one or more materials used to form a semiconductor device (such as metal contacts, trench isolation, gates, bit lines, or other arbitrary interconnection features). The substrate 702 may include one or more metal layers, one or more dielectric materials, semiconductor materials, and combinations thereof, which are used to manufacture a semiconductor device. For example, the substrate 702 may include oxide materials, nitride materials, polysilicon materials, etc., depending on the application. In one embodiment targeted at memory applications, the substrate 702 may include silicon substrate material, oxide material, and nitride material (with or without polysilicon present between them).

[0086] In another embodiment, the substrate 702 may include multiple alternating oxide and nitride materials (i.e., oxide-nitride-oxide (ONO)) deposited on the surface of the substrate 702 (not shown). In various realizations, the substrate 702 may include alternating multiple oxide and nitride materials, one or more oxide or nitride materials, polysilicon or amorphous silicon materials, oxides alternating with amorphous carbon, oxides alternating with polysilicon, undoped silicon alternating with doped silicon, undoped polysilicon alternating with doped polysilicon, or undoped amorphous silicon alternating with doped amorphous silicon. The substrate 702 may be any substrate or material surface on which the film treatment is performed. For example, the substrate 702 may be made of materials such as crystalline silicon, silicon oxide, silicon oxynitride, silicon nitride, strained silicon, silicon germanium, tungsten, titanium nitride, 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, sapphire, low dielectric constant dielectrics, and combinations thereof.

[0087] The film stack 700 includes a substrate 702 and an underlying layer 704. The underlying layer 704 used herein includes any layer placed beneath the amorphous carbon hard mask. For example, the amorphous carbon hard mask 706 may be placed directly above the underlying layer 704 such that the amorphous carbon hard mask 706 and the underlying layer 704 are in physical contact with each other. In one example, the underlying layer 704 includes a single layer. In another example, the underlying layer 704 includes multiple layers, such as a dielectric stack.

[0088] In operation 620, as shown in Figure 7B, an amorphous carbon mask 706 is formed on a lower layer 704 positioned above the substrate 702. The amorphous carbon hard mask 706 may be deposited above the lower layer 704 by a blanket deposition process. In some embodiments, the amorphous carbon hard mask 706 is deposited according to method 400 as shown in the process flow diagram of Figure 4. The amorphous carbon hard mask 706 may be deposited to a thickness corresponding to the subsequent etching requirements of the lower layer 704. In one example, the amorphous carbon hard mask has a thickness between about 0.5 μm and about 1.5 μm, for example, about 1.0 μm.

[0089] In operation 630, a patterned photoresist layer 720 is formed on top of the amorphous carbon hard mask 706, as shown in Figure 7C. Features or patterns can be transferred from the photomask to the photoresist layer 720 using an energy source such as light energy. In one embodiment, the photoresist layer 320 is a polymer material, and the patterning process is carried out by a 193-nanometer immersion photolithography process or other similar photolithography process. Similarly, a laser may also be used to carry out the patterning process.

[0090] In operation 640, the doped amorphous carbon hard mask 706 is opened, for example, by a plasma etching process to form a patterned amorphous carbon hard mask 722 having openings or holes, as shown in Figure 7D. Any suitable plasma etching process may be used. In one example, the plasma etching process may be carried out in a chamber similar to the chamber described with respect to Figure 7F.

[0091] In operation 650, as shown in Figure 7E, the photoresist layer 720 is removed, exposing the top surface of the patterned amorphous carbon hard mask 722. The photoresist layer 320 can be removed by various advantageous photoresist removal processes.

[0092] In operation 660, the ion implantation process dops the amorphous carbon hard mask 722, which is patterned with a dopant or inert species, to form a doped and patterned amorphous carbon hard mask 732, which is doped with the dopant or inert species, as shown in Figure 7F. The ion implantation process in operation 660 can be carried out at an implantation inclination angle of 0 degrees (perpendicular to the plane defined by the top surface of the patterned amorphous carbon hard mask 722) or at an implantation inclination angle greater than 0 degrees (±θ with respect to the plane defined by the top surface of the patterned amorphous carbon hard mask 722). As shown in Figure 7F, for some ion species that increase the etching rate of the underlying layer 704, the implantation process can be carried out at 0 degrees, as a result of modifying and / or doping the modified portions 742a and 742b. In some examples, selective modification of the underlying layer 704 improves the etching properties of the modified portions 742a and 742b. In another example, for some ion species that result in slowing the etching rate of the lower layer 704, the ion implantation process may be carried out at an implantation gradient angle such that the exposed portions of the lower layer 704 are not modified or doped, as shown in Figure 7G. The implantation gradient angle generally depends on the size of the openings in the patterned amorphous carbon hard mask. Post-patterning implantation may be carried out at an implantation gradient angle of 0 degrees, or at some angle into the amorphous carbon film, with a corresponding twist angle between 0 and about 360 degrees, allowing ions to penetrate only the hard mask. The implantation can be divided into multiple steps, and each implantation can be carried out at a different gradient angle. By dividing the desired total dose into multiple implantations, the dose of each of the multiple implantations can be determined. For example, if the line and spatial features of the carbon hard mask run in one direction rather than two vertical directions, the implantation can be divided into two implantations, with each implantation at half the desired dose, for example, 1 × 10⁻⁶. 16 Ions / cm 2 The dose is 5.0 × 10 15 Ions / cm 2 It can be divided into doses of 1 × 10. The substrate is injected each time it rotates 180 degrees, and therefore, 1 × 1016 Ions / cm 2 The desired dose is accumulated. As a result, both sides of the feature area of ​​the carbon hard mask are uniformly injected. A wide range of injection angles are possible, for example, injection angles from about 0.1 degrees to about 80 degrees (e.g., about 1 degree to about 80 degrees; or about 10 degrees to about 50 degrees), excluding zero degrees, can be used.

[0093] Any suitable doping technique may be used. In one example, plasma immersion ion implantation is employed to implant a dopant or inert species. In another example, beamline implantation is employed to implant a dopant or inert species. In yet another example, conformal doping techniques such as plasma doping (PLAD) are employed to implant a dopant or inert species.

[0094] Suitable ionic species can be generated from various precursor materials, such as carbon, boron, nitrogen, silicon, phosphorus, helium, argon, neon, krypton, xenon, beryllium, and germanium-containing materials. In one embodiment, the dopant or inert species is selected from carbon, boron, nitrogen, silicon, phosphorus, argon, helium, neon, krypton, xenon, beryllium, germanium, or combinations thereof. An example of a carbon-containing precursor gas is CH4. In one embodiment, various precursor materials can be generated from combinations of precursor materials, for example, CH4 / N2, CH4 / He, N2 / He, CH4 / Ne, CH4 / Ar, CH4 / Ne, CH4 / Kr, or CH4 / Xe.

[0095] In the schematic diagram of Figure 7F, ion 710 collides with the patterned amorphous carbon hard mask 722 at an implantation angle of 0 degrees, and penetrates roughly the exposed portions of the patterned amorphous carbon hard mask 722 and the underlying layer 704, forming the doped and patterned amorphous carbon hard mask 732 and modified portions 742a, 742b (modified and / or implanted with dopants or inert species). Ion 710 penetrates the patterned amorphous carbon hard mask 722 and the underlying layer 704 to varying depths, depending on the type and size of the ion, as well as the power and bias used to activate ion 710. The species of ion 710 can be adjusted to provide increased etching selectivity of the underlying layer 704. Thus, the implanted species can be any monomer or molecular ion adapted to enhance the etching selectivity of the patterned amorphous carbon hard mask 722.

[0096] Alternatively, as shown in the schematic diagram of Figure 7G, the injection process or operation 660 is performed at an angle such that the exposed portion of the underlying layer 704 is not modified or doped. The injection inclination angle varies depending on the size of the opening. The injection may further include a twist angle. A wide range of injection inclination angles are possible, for example, injection angles from about 0.1 degrees to about 80 degrees (e.g., about 1 degree to about 80 degrees), excluding zero degrees, and from about -0.1 degrees to about -80 degrees (e.g., -1 degree to about -80 degrees) may be used. The twist angle may be between 0 degrees and 360 degrees, which allows ions to penetrate only the hard mask. As shown in Figure 7G, the ions 750 collide with the patterned amorphous carbon hard mask 722 and generally penetrate the patterned amorphous carbon hard mask 722, but generally do not penetrate the exposed portion of the underlying layer 704.

[0097] The ion implantation process can be carried out by a beamline or plasma implantation tool. Exemplary systems used to carry out the implantation process include, for example, the VARIAN VIISta® Trident system, VARIAN VIISta® Thermion system, VARIAN VIISta® Medium Current Thermion system, VIISta® 3000XP system, VIISta® 900XP system, VIISta® HCP system, and VIISta® PLAD system, all available from Applied Materials, Inc. in Santa Clara, California. While the above systems have been described, systems from other manufacturers may also be used to carry out the ion implantation process.

[0098] In one embodiment, the ion implantation process of operation 660 implants dopants or inert species into the patterned amorphous carbon hard mask 722. The dopants or inert species are selected from carbon, boron, nitrogen, silicon, phosphorus, argon, helium, neon, krypton, xenon, beryllium, germanium, or combinations thereof. In one embodiment, the implantation energy utilized to energize the dopants is between about 60 keV and about 300 keV (e.g., between about 60 keV and about 300 keV). The implantation can be performed at a single energy or multiple energies between 60 keV and 300 keV, depending on the type of dopant utilized, the type of material utilized as the patterned amorphous carbon hard mask 722, and the target depth of implantation. In another embodiment, the implantation energy utilized to energize the dopants is between about 1 keV and about 60 keV (e.g., between about 5 keV and about 60 keV; between about 1 keV and about 15 keV; between about 10 keV and about 35 keV; between about 20 keV and about 30 keV; or between about 20 keV and about 25 keV). The implantation can be performed at a single energy or multiple energies between 1 keV and 60 keV, depending on the type of dopant utilized, the type of material utilized as the patterned amorphous carbon hard mask 722, and the target depth of implantation.

[0099] In one embodiment, the ion dose (ions / cm 2 ) is between about 1×10 13 ions / cm 2 and about 5×10 17 ions / cm 2 , depending on the type of dopant utilized, the type of material utilized as the amorphous carbon hard mask 306, and the target depth of implantation (e.g., between about 1×10 15 ions / cm 2 and about 3×10 17 ions / cm 2 ; between about 1×10 14 ions / cm 2 and about 5×10 16 ions / cm 2 ; between about 1×1014 ions / cm 2 and about 2×10 16 ions / cm 2 ; between about 1×10 15 ions / cm 2 and about 1×10 16 ions / cm 2 ; between about 5×10 15 ions / cm 2 and about 1×10 16 ions / cm 2 ; between). In another embodiment, the ion dose (ions / cm 2 ) is about 5×10 13 ions / cm 2 and about 5×10 17 ions / cm 2 ; for example, between about 1×10 15 ions / cm 2 and about 3×10 17 ions / cm 2 ; between about 1×10 14 ions / cm 2 and about 5×10 16 ions / cm 2 ; between about 1×10 14 ions / cm 2 and about 2×10 16 ions / cm 2 ; between about 1×10 15 ions / cm 2 and about 1×10 16 ions / cm 2 ; between about 5×10 15 ions / cm 2 and about 1×10 16 ions / cm 2 ; between).

[0100] In one embodiment, when the PLAD implantation technique is used, the implantation energy utilized to energize the dopant or the inert species is about 1×10 15 ions / cm 2 and about 5×10 17 ions / cm 2 ; for example, about 2×1015 Ions / cm 2 and approximately 3 x 10 17 Ions / cm 2 Between; approximately 5 x 10 15 Ions / cm 2 and approximately 5 x 10 16 Ions / cm 2 Between; or approximately 1 × 10 16 Ions / cm 2 and approximately 1 x 10 17 Ions / cm 2 In the ion dose range between approximately 1 kV and 15 kV (for example, between approximately 1 kV and 12 kV; between approximately 2 kV and 10 kV). In one example where the dopant is helium, the injection energy used to energize the dopant is approximately 1 × 10⁻¹⁶ 15 Ions / cm 2 and approximately 3 x 10 17 Ions / cm 2 The ion dose range is between approximately 1 kV and approximately 15 kV.

[0101] In one execution mode, the target temperature for the injection process or operation 660 is between approximately -100°C and approximately 550°C (e.g., between approximately -100°C and approximately 200°C; between approximately -100°C and approximately 0°C; between approximately -100°C and approximately 50°C; between approximately 0°C and approximately 100°C; or between approximately 150°C and approximately 550°C). In another execution mode, the target temperature for injection is between approximately -100°C and approximately 500°C (e.g., between approximately -100°C and approximately 200°C; between approximately -100°C and approximately 0°C; between approximately -100°C and approximately 50°C; between approximately 0°C and approximately 50°C; or between approximately 50°C and approximately 400°C). In one example, when low-temperature injection is performed, the target temperature for injection is between approximately -100°C and approximately 0°C. In another example, when room-temperature injection is performed, the target temperature for injection is between approximately 10°C and approximately 100°C. In yet another example, when high-temperature injection is performed, the target injection temperature is approximately 150°C to 550°C.

[0102] In one implementation, the film stack 700 is heat-treated following the ion implantation process. Appropriate post-ion implantation heat treatments include UV treatment, thermal annealing, and / or laser annealing. Heat treatment of the doped and patterned amorphous carbon hard mask 732 further incorporates the implanted ions 710 into the framework of the doped and patterned amorphous carbon hard mask 732. For example, the implanted ions 710 may be redistributed within the doped and patterned amorphous carbon hard mask 732 to form a more uniform doping profile. The heat treatment is thought to increase the interaction and binding between the doped and patterned amorphous carbon hard mask 732 and the implanted ions 710. The redistribution and binding of the implanted ions 710 may function to further increase the hardness, density, and etching selectivity of the doped and patterned amorphous carbon hard mask 732. In one execution mode, the annealing process is carried out in a plasma processing chamber, such as plasma processing chamber 100. In another execution mode, the annealing process is carried out in a separate annealing chamber.

[0103] In general, increasing the hardness of the doped and patterned amorphous carbon hard mask 732 reduces the bending of lines in the high aspect ratio structure of the underlying layer 704. The implanted ions 710 and 750 are thought to extract residual hydrogen atoms from the dangling carbon-hydrogen bonds of the amorphous carbon hard mask 706, forming carbide structures within the amorphous carbon hard mask 706. These carbide structures exhibit increased hardness compared to the undoped hard mask. Furthermore, the implanted ions 710 and 750 are thought to occupy interstitial voids present within the doped and patterned amorphous carbon hard mask 732, resulting in an increased density of the doped and patterned amorphous carbon hard mask 732. In addition, the implanted ions 710 and 750 are thought to contribute to the formation of SPs in the amorphous carbon hard mask 706. 3 It is thought to increase the formation of carbon-to-carbon bonds. As density increases, the mechanical integrity of the doped and patterned amorphous carbon mask 732 further increases.

[0104] In operation 670, the underlying layer 304 is etched, as shown in Figure 7H. Etching of the underlying layer 704 can be carried out in a plasma processing chamber, such as the chamber and system described with respect to Figure 1. An etchant, such as carbon fluoride, removes the exposed portion of the underlying layer 704. The active species of the etchant do not substantially react with the material of the doped and patterned amorphous carbon hard mask 732, the implanted ions 710. Therefore, the etchant is selective for the underlying layer 704 material. Suitable examples of etchants include, among others, CF4, CHF3, HBr, BCl3, and Cl2. The etchant can be supplied with an inert carrier gas.

[0105] In operation 680, the doped and patterned amorphous carbon hard mask 732 is removed, as shown in Figure 7I. The doped and patterned amorphous carbon hard mask 732 can be removed by any favorable hard mask removal process. In one example, oxygen plasma is used to remove the doped and patterned amorphous carbon hard mask 732. The resulting film stack 700 includes an underlayer 704 in which features 724, such as high aspect ratio features, are formed. The film stack 700 can then be subjected to further processing to form a functional semiconductor device.

[0106] Methods 200, 400, and 600 are useful for processes used in front-end processes (FEOLs) before metallization processes in semiconductor device manufacturing processes. The amorphous carbon film formed by Method 400 can function as a hard mask layer during the etching process due to its high etching selectivity. Suitable processes include gate manufacturing applications, contact structure applications, and shallow trench isolation (STI) processes. In some implementations, when the amorphous carbon film is used as an etching stop layer or as a different film for different process purposes, the mechanical or optical properties of the amorphous carbon film can be similarly tailored to meet specific process needs.

[0107] Therefore, the embodiments described herein provide a method for forming a highly etching-selective amorphous carbon film having both target in-plane strain and Young's modulus at low stress by a plasma deposition process and a subsequent carbon implantation process. This method advantageously provides an amorphous carbon film having target mechanical properties such as low stress and high Young's modulus, changes in carbon-to-carbon bonding and hydrogen incorporation, and high etching selectivity. Some embodiments of this disclosure further provide process designs that use existing hardware with little impact on throughput or execution cost. Some embodiments of this disclosure provide unique processes that increase the elastic modulus of an amorphous carbon film by about twofold (e.g., from about 64 GPa to about 138 GPa) by modifying the plasma deposition mechanism. Ion implantation further improves the Young's modulus of the amorphous carbon film by 30% (e.g., from about 180 GPa) and reduces the compressive stress by about 75% (e.g., from about -1200 to about -300 MPa), thereby further improving the film properties. Furthermore, the combination of PECVD and ion implantation resulted in amorphous carbon films with significantly reduced in-plane distortion (<3 nanometer overlay error) compared to current-generation pure carbon hard mask films. The films obtained herein demonstrated 30–50% improved etching selectivity compared to current-generation essentially pure amorphous carbon hard mask films and met previous overlay requirements.

[0108] When describing elements of this disclosure, or exemplary forms or implementations thereof, the articles “a, an” and “the, said” are used to indicate that one or more of the elements exist.

[0109] The words "comprising," "including," and "having" are intended to be comprehensive, meaning that there may be additional elements beyond those listed.

[0110] The above description applies to the embodiments of this disclosure, but other embodiments and further embodiments of this disclosure may be devised without departing from the basic scope of this disclosure, and the scope of this disclosure is defined by the following claims.

Claims

1. 1. A method for treating an underlayer, comprising: depositing an amorphous carbon film on an underlayer positioned on a susceptor in a first processing region; forming a doped amorphous carbon film by implanting a dopant or an inert species into the amorphous carbon film in a second processing region, the dopant or the inert species comprising at least one of beryllium or germanium, and a target temperature during implantation of the dopant or the inert species being between −100° C. and 550° C.; patterning the doped amorphous carbon film; Etching the underlayer; A method comprising:

2. The method of claim 1 , wherein the underlayer comprises a single layer or a dielectric stack.

3. depositing the amorphous carbon film on the underlayer; flowing a hydrocarbon-containing gas mixture through the first processing region; generating an RF plasma in the first processing region to form the amorphous carbon film on the underlayer; The method of claim 1 , comprising:

4. 4. The method of claim 3, wherein the distance between a gas distribution showerhead positioned in the first processing region and the susceptor is between 200 mils and 1,000 mils.

5. 5. The method of claim 4, wherein the pressure in the first processing region is between 4 Torr and 8 Torr.

6. 10. The method of claim 1, wherein the implant energy utilized to energize the dopants or the inert species is between 5 keV and 300 keV.

7. Ion dose is 1 x 10 １３ ions / cm ２ and 5 x 10 １６ ions / cm ２ The method of claim 6, wherein

8. 7. The method of claim 6, wherein implanting the dopant or the inert species into the patterned amorphous carbon film is performed at an angle between 1 degree and 80 degrees relative to a direction normal to a plane defined by a top surface of the patterned amorphous carbon film.

9. 1. A method for treating an underlayer, comprising: depositing an amorphous carbon film on an underlayer positioned on a susceptor in a first processing region; forming a doped amorphous carbon film by implanting a dopant or an inert species into the amorphous carbon film in a second processing region, the dopant or the inert species comprising at least one of beryllium or germanium, and a target temperature during implantation of the dopant or the inert species being between −100° C. and 550° C.; patterning the doped amorphous carbon film; etching the underlayer, wherein the doped amorphous carbon film has a refractive index of 2.1 to 2.2 at 633 nm; A method comprising:

10. 10. The method of claim 9, wherein the doped amorphous carbon film has a k value of less than 1.0 at 633 nm.

11. 10. The method of claim 9, wherein the doped amorphous carbon film has a Young's modulus (GPa) of 70 to 200 GPa.

12. 12. The method of claim 11, wherein the doped amorphous carbon film has a hardness (GPa) of 14 GPa to 22 GPa.

13. The method of claim 12, wherein the doped amorphous carbon film has a stress (MPa) of -600 MPa to 0 MPa.

14. 14. The method of claim 13, wherein the doped amorphous carbon film has a density (g / cc) of 1.95 g / cc to 2.1 g / cc.

15. 15. The method of claim 14, wherein the doped amorphous carbon film has a thickness between 10 Å and 50,000 Å.

16. 1. A method for treating an underlayer, comprising: depositing an amorphous carbon film on an underlayer positioned on a susceptor in a first processing region; forming a doped amorphous carbon film by implanting a dopant into the amorphous carbon film in a second processing region, the dopant comprising carbon and at least one of beryllium or germanium, and a target temperature during implantation of the dopant being between −100° C. and 550° C.; patterning the doped amorphous carbon film; etching the underlayer, wherein the doped amorphous carbon film has a hardness (GPa) of 14 GPa to 22 GPa; A method comprising:

17. 17. The method of claim 16, wherein the doped amorphous carbon film has a refractive index of 2.1 to 2.2 at 633 nm.

18. 18. The method of claim 17, wherein the doped amorphous carbon film has a k value of less than 1.0 at 633 nm.

19. 17. The method of claim 16, wherein the doped amorphous carbon film has a Young's modulus (GPa) of 70 to 200 GPa.

20. The doped amorphous carbon film is Stress (MPa) from -600 MPa to 0 MPa; a density (g / cc) of 1.95 g / cc to 2.1 g / cc; a thickness between 10 Å and 50,000 Å; 20. The method of claim 19, comprising:

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