Methods of forming thermally stable carbon films

Abstract

A method of processing a substrate is provided that includes flowing a deposition gas including a hydrocarbon compound and a dopant compound into a processing volume having a substrate positioned on a substrate support. The processing volume is maintained at a pressure of about 0.5 millitorr to about 10 millitorr. The method includes generating a plasma at the substrate by applying a first RF bias to the substrate support to deposit a doped diamond-like carbon film on the substrate. The doped diamond-like carbon film includes a dopant in an amount from about 5 atomic percent to about 25 atomic percent and a first stress property. The method includes annealing the doped diamond-like carbon film at about 220 DEG C to about 450 DEG C to form an annealed film. The annealed film includes a second stress property. The absolute value of the second stress property is less than or within 10% of the first stress property.

Description

background Technical Field

[0001] Embodiments of the present disclosure generally relate to methods used in the fabrication of semiconductor devices. More specifically, embodiments of the present disclosure relate to methods of doping and annealing carbon films to form thermally stable diamond-like carbon films. Background Art

[0002] Integrated circuits have evolved into complex devices that can include millions of transistors, capacitors, and resistors on a single chip. Advances in chip design continue to involve faster circuit systems and greater circuit density. The demand for faster circuits with greater circuit density also imposes corresponding demands on the materials used to manufacture such integrated circuits. In particular, as the size of integrated circuit components decreases to the sub-micron level, the trend is to use low-resistivity conductive materials and low dielectric constant insulating materials to obtain suitable electrical properties for such components.

[0003] The demand for greater integrated circuit density also imposes demands on the process sequences used in the manufacture of integrated circuit components. For example, in a process sequence using conventional photolithography, an energy-sensitive resist layer is formed over a stack of material layers, which are disposed on a substrate. The energy-sensitive resist layer is exposed to an image of a pattern to form a photoresist mask. Thereafter, an etching process is used to transfer the mask pattern to one or more of the stacked material layers. The chemical etchant used in the etching process is selected so that the etch selectivity to the stacked material layers is greater than the etch selectivity to the mask of the energy-sensitive resist. That is, the chemical etchant etches one or more layers of the material stack at a much faster rate than the energy-sensitive resist. The etch selectivity to the one or more material layers of the stack that exceeds the resist prevents the energy-sensitive resist from being consumed before the pattern transfer is completed.

[0004] As the pattern size decreases, the thickness of the energy-sensitive resist is correspondingly reduced to control the pattern resolution. Due to the attack of the chemical etchant, such a thin resist layer may not be enough to shield the material layer below during the pattern transfer process. Due to the large resistance to 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 material layer below to facilitate pattern transfer. Hard mask materials with high etching selectivity and high deposition rate are often used. As the critical dimension (CD) decreases, current hard mask materials lack the desired etching selectivity relative to the material below (e.g., oxide and nitride), and are often difficult to deposit.

[0005] Therefore, there is a need in the art for improved hard mask layers and methods for depositing improved hard mask layers. Summary of the invention

[0006] A method for processing a substrate is provided. The method includes flowing a deposition gas including a hydrocarbon compound and a dopant compound into a processing volume of a processing chamber. The processing volume has a substrate disposed in the processing volume and positioned on a substrate support. The processing volume is maintained at a pressure of about 0.5 mTorr to about 10 mTorr. The method further includes generating a plasma at the substrate by applying a first RF bias to the substrate support to deposit a doped diamond-like carbon film on the substrate. The doped diamond-like carbon film includes a dopant in an amount of about 5 atomic percent to about 25 atomic percent. The doped diamond-like carbon film includes a first stress property. The method includes annealing the doped diamond-like carbon film at about 220° C. to about 450° C. to form an annealed film. The annealed film includes a second stress property. The absolute value of the second stress property is less than or within 10% of the first stress property.

[0007] A method for processing a substrate is provided. The method includes flowing a deposition gas. The deposition gas includes a hydrocarbon compound and a dopant compound entering a processing volume of a processing chamber, the dopant compound including silicon. The processing volume includes a substrate disposed in the processing volume and positioned on a substrate support. The substrate support has an adsorption electrode and an RF electrode separated from the adsorption electrode. The processing volume is maintained at a pressure of about 0.5 mTorr to about 10 Torr. The method includes generating a plasma at the substrate by applying a first RF bias to the RF electrode and applying a second RF bias to the adsorption electrode to deposit a doped diamond-like carbon film on the substrate. The doped diamond-like carbon film has a density of greater than 2 g / cc to about 12 g / cc and a first stress of about -300 MPa to about -150 MPa. The method includes annealing the doped diamond-like carbon film at a temperature of about 220° C. to about 450° C. to form an annealed film, the annealed film having a second stress of about -250 MPa to about -100 MPa.

[0008] A method for processing a substrate is provided. The method includes positioning a substrate on a substrate support in a processing volume. The method includes generating a plasma above the substrate by applying an RF bias to the substrate support. The method includes providing a deposition gas including a hydrocarbon compound and a dopant compound into a processing volume of a processing chamber, the dopant compound including boron or silicon. The substrate support has an adsorption electrode and an RF electrode separated from the adsorption electrode. The processing volume is maintained at a pressure of about 0.5 mTorr to about 10 Torr. The method further includes generating a plasma at the substrate by applying a first RF bias to the RF electrode and applying a second RF bias to the adsorption electrode to deposit a doped diamond-like carbon film on the substrate. The doped diamond-like carbon film has a density of greater than 2 g / cc to about 12 g / cc and a stress of about -600 MPa to about -300 MPa. The method includes annealing the doped diamond-like carbon film at a temperature of about 220° C. to about 450° C. to form an annealed film. The annealed film has a second stress of about -250 MPa to about -100 MPa. The method includes: forming a patterned photoresist layer over the annealed film. The method includes: etching the annealed film in a pattern corresponding to the patterned photoresist layer. The method further includes: etching the pattern into the substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In order to be able to understand in detail the manner in which the above-mentioned features of the present disclosure are achieved, a more specific description of the present disclosure briefly summarized above may be obtained by reference to embodiments (some of which are illustrated in the attached drawings). However, it should be noted that the attached drawings only illustrate exemplary embodiments and therefore should not be considered as limiting the scope thereof, and other equivalent embodiments may be allowed.

[0010] Figure 1 is a schematic side cross-sectional view of an illustrative processing chamber according to an embodiment.

[0011] Figure 2 Depicted is a schematic cross-sectional view of a substrate support according to an embodiment.

[0012] Figure 3 A flow chart depicts a method of using a doped diamond-like carbon film according to an embodiment.

[0013] Figure 4A is a film stack formed on a substrate according to an embodiment.

[0014] Figure 4B Depicted is a doped diamond-like carbon film formed in accordance with an embodiment.

[0015] Figure 5Schematic diagram depicting comparative stress results for boron doped and undoped diamond-like carbon films before and after annealing.

[0016] Figure 6 Schematic diagram depicting comparative stress results for silicon-doped and undoped diamond-like carbon films before and after annealing.

[0017] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation. DETAILED DESCRIPTION

[0018] Embodiments of the present disclosure relate to forming a high density carbon hard mask that can withstand high temperatures, such as temperatures above 300 degrees Celsius, as part of substrate processing. Conventional hard masks subjected to high temperatures generally change stress and become more compressed, resulting in bending and warping. These defects create many challenges during subsequent photolithography processes. It has been found that the high density carbon hard mask doped with silicon or boron dopants disclosed herein improves the thermal stability of the hard mask. The high density carbon hard mask described herein is formed using a plasma enhanced chemical vapor deposition (PECVD) chamber.

[0019] Figure 1 is a schematic side cross-sectional view of an illustrative processing chamber 100 suitable for performing a deposition process. Figure 1 One chamber suitable for performing the deposition processes described herein is depicted, but other chambers are also contemplated. In one embodiment, which can be combined with other embodiments described herein, the processing chamber 100 is configured to deposit an advanced patterned film onto a substrate, such as a hard mask film, for example an amorphous carbon hard mask film.

[0020] The processing chamber 100 includes a lid assembly 105, a spacer 110 disposed on a chamber body 192, a substrate support 115, and a variable pressure system 120. The lid assembly 105 includes a lid plate 125 and a heat exchanger 130. In the illustrated embodiment, which can be combined with other embodiments described herein, the lid assembly 105 also includes a showerhead 135.

[0021] The lid assembly 105 is coupled to a first process gas source 140. The first process gas source 140 contains a precursor gas for forming a film on a substrate 145, which is supported on a substrate support 115. As an example, the first process gas source 140 includes a precursor gas, such as a carbon-containing gas, a hydrogen-containing gas, helium, etc. In a specific example, the carbon-containing gas includes acetylene (C2H2). The first process gas source 140 provides the precursor gas to a gas chamber 190 disposed in the lid assembly 105. The lid assembly includes one or more channels for directing the precursor gas from the first process gas source 140 into the gas chamber 190. The precursor gas flows from the gas chamber through the showerhead 135 into the processing volume 160. In some embodiments that can be combined with other embodiments described herein, the second process gas source 142 is fluidly coupled to the processing volume 160 via an inlet 144, which is disposed through the spacer 110. As an example, the second process gas source 142 includes a precursor gas, such as a carbon-containing gas, a hydrogen-containing gas, helium, etc., for example C2H2. In one embodiment that can be combined with other embodiments described herein, the total flow rate of the precursor gas entering the processing volume 160 is about 100 sccm to about 2 slm. The flow of the precursor gas through the second process gas source 142 in the processing volume 160 modulates the flow of the precursor gas flowing through the showerhead 135, so that the precursor gas is evenly distributed in the processing volume 160. In one example, the plurality of inlets 144 are radially distributed around the spacer 110. In such an example, the gas flow to each inlet 144 is separately controlled to further promote gas uniformity within the processing volume 160.

[0022] The lid assembly 105 is also coupled to an optional remote plasma source 150. The remote plasma source 150 is coupled to a cleaning gas source 155 for providing a cleaning gas to a processing volume 160 formed within the spacer 110 between the lid assembly 105 and the substrate 145. In one example, the cleaning gas is provided through a central conduit 191 formed axially through the lid assembly 105. In another example, the cleaning gas is provided through the same channel that guides the precursor gas. Exemplary cleaning gases include oxygen-containing gases (such as oxygen and / or ozone) and fluorine-containing gases (such as NF3), or combinations of the above gases.

[0023] In addition to or as an alternative to the remote plasma source 150, the lid assembly 105 is also coupled to a first or upper radio frequency (RF) power source 165. The first RF power source 165 facilitates the maintenance or generation of a plasma, such as a plasma generated by a cleaning gas. In one example, the remote plasma source 150 is omitted, and the cleaning gas is ionized in situ into a plasma via the first RF power source 165. The substrate support 115 is coupled to a second or lower RF power source 170. The first RF power source 165 is a high frequency RF power source (e.g., about 13.56 MHz to about 120 MHz), and the second RF power source 170 is a low frequency RF power source (e.g., about 2 MHz to about 13.56 MHz). It should be noted that other frequencies are also contemplated. In some embodiments, the second RF power source 170 is a mixed frequency RF power source, providing both high frequency power and low frequency power. The use of a dual frequency RF power source (particularly the second RF power source 170) improves film deposition. In one example, the second RF power source 170 is used to provide dual frequency power. A first frequency of about 2 MHz to about 13.56 MHz improves the injection of species into the deposited film, while a second frequency of about 13.56 MHz to about 120 MHz increases the ionization and deposition rate of the film. Without being bound by theory, it is believed that a low frequency (such as the first frequency) can achieve ion energy control, while a high frequency (such as the second frequency) can be used for ion density control.

[0024] One or both of the first RF power supply 165 and the second RF power supply 170 are used to generate or maintain a plasma in the processing volume 160. For example, the second RF power supply 170 is utilized during a deposition process, and the first RF power supply 165 (either alone or in conjunction with the remote plasma source 150) is utilized during a cleaning process. In some deposition processes, the first RF power supply 165 is used in conjunction with the second RF power supply 170. During a deposition or etching process, one or both of the first RF power supply 165 and the second RF power supply 170 provide power in the processing volume 160 of about 100 watts (W) to about 20,000 W to facilitate ionization of a precursor gas. In one embodiment that can be combined with other embodiments described herein, at least one of the first RF power supply 165 and the second RF power supply 170 is pulsed. In another embodiment that can be combined with other embodiments described herein, the precursor gas comprises helium and C2H2. In one embodiment that may be combined with other embodiments described herein, C2H2 is provided at a flow rate of about 10 sccm to about 1000 sccm, and He is provided at a flow rate of about 50 sccm to about 10000 sccm.

[0025] The substrate support 115 is coupled to an actuator 175 (i.e., a lift actuator) that provides movement of the substrate support in the Z direction. The substrate support 115 is also coupled to a flexible facility cable 178 that allows vertical movement of the substrate support 115 while maintaining communication with the second RF power supply 170 and other power and fluid connections. A spacer 110 is disposed on the chamber body 192. The height of the spacer 110 allows vertical movement of the substrate support 115 within the processing volume 160. The height of the spacer 110 is about 0.5 inches to about 20 inches. In one example, the substrate support 115 can be moved from a first distance 180A to a second distance 180B relative to the lid assembly 105 (e.g., relative to the lower surface of the showerhead 135). In one embodiment, the second distance 180B is about 2 / 3 of the first distance 180A. For example, the difference between the first distance 180A and the second distance is about 5 inches to about 6 inches. Therefore, from Figure 1 Starting from the position shown, the substrate support 115 can move about 5 inches to about 6 inches relative to the lower surface of the showerhead 135. In another example, the substrate support 115 is fixed at one of the first distance 180A and the second distance 180B. In contrast to conventional plasma enhanced chemical vapor deposition (PECVD) processes, the spacer 110 significantly increases the distance between the substrate support 115 and the lid assembly 105 (and thus increases the volume between the substrate support 115 and the lid assembly 105). The increased distance between the substrate support 115 and the lid assembly 105 reduces collisions of ionized species in the volumetric processing volume 160, resulting in deposition of films with less neutral stress (such as less than 2.5 gigapascals (GPa)). Films deposited with less neutral stress contribute to improved flatness (e.g., less bowing) of a substrate on which the film is formed. Reduced bowing of the substrate results in improved precision of downstream patterning operations.

[0026] The variable pressure system 120 includes a first pump 182 and a second pump 184. The first pump 182 is a roughing pump used during the cleaning process and / or substrate transfer process. Roughing pumps are generally configured to move higher volume flow rates and / or operate relatively higher pressures (although still below atmospheric pressure). In one example, the first pump 182 maintains the pressure in the processing chamber to less than 50 millitorr during the cleaning process. In another example, the first pump 182 maintains the pressure in the processing chamber at about 0.5 millitorr to about 10 torr.

[0027] The second pump 184 is one of a turbo pump and a cryogenic pump. The second pump 184 is utilized during the deposition process. The second pump 184 is generally configured to operate at a relatively low volume flow rate and / or pressure. For example, the second pump 184 is configured to maintain the processing volume 160 of the processing chamber at a pressure of less than about 50 mTorr. In another example, the second pump 184 maintains the pressure within the processing chamber at about 0.5 mTorr to about 10 mTorr. When depositing a carbon-based hard mask, the reduced pressure of the processing volume 160 maintained during deposition facilitates the deposition of a layer having a reduced neutral stress and / or increased sp 2 -sp 3 Thus, the processing chamber 100 is configured to use both relatively low pressures to improve deposition and relatively high pressures to improve cleaning.

[0028] In some embodiments that can be combined with other embodiments described herein, both the first pump 182 and the second pump 184 are used during the deposition process to maintain the processing volume 160 of the processing chamber at less than about 50 mTorr. In other embodiments, the first pump 182 and the second pump 184 maintain the processing volume 160 at a pressure of about 0.5 mTorr to about 10 mTorr. The valve 186 is used to control the conduction path to one or both of the first pump 182 and the second pump 184. The valve 186 also provides symmetrical pumping from the processing volume 160.

[0029] The processing chamber 100 also includes a substrate transfer port 185. The substrate transfer port 185 is selectively sealed by an inner door 186A and an outer door 186B. Each of the doors 186A and 186B is coupled to an actuator 188 (i.e., a door actuator). The doors 186A and 186B facilitate vacuum sealing of the processing volume 160. The doors 186A and 186B also provide symmetrical RF application and / or plasma symmetry within the processing volume 160. A seal 116 (such as an O-ring) is disposed at the interface of the spacer 110 and the chamber body 192, which further seals the processing volume 160. A controller 194 coupled to the processing chamber 100 is configured to control various aspects of the processing chamber 100 during processing.

[0030] Figure 2 Depicted in Figure 1Schematic cross-sectional view of a substrate support 115 for use in a processing system of the present invention. The substrate support 115 includes a heater element 270 that is suitable for controlling the temperature of a substrate 145 supported on an upper surface of the substrate support 115. The heater element 270 is embedded in the substrate support 115. The substrate support 115 is resistively heated by applying current from a heater power supply 221 to the heater element 270. The heater power supply 221 is coupled through an RF filter 216. The RF filter 216 is used to protect the heater power supply 221 from RF energy. The heater element 270 is encapsulated in a nickel-iron-chromium alloy (e.g., The heater power supply 221 is made of nickel-chromium wire in a (A) alloy) sleeve. The current supplied from the heater power supply 221 is regulated by the controller 194 to control the heat generated by the heater element 270 to maintain the substrate 145 and the substrate support 115 at a substantially constant temperature during film deposition. The supplied current is adjusted to selectively control the temperature of the substrate support 115 between about -50°C and about 600°C.

[0031] The substrate support 115 includes a chuck electrode 210, which is a mesh of conductive material. The chuck electrode 210 is embedded in the substrate support 115. The chuck electrode 210 is coupled to a chuck power source 212, which electrostatically chucking the substrate 145 to the upper surface of the substrate support 115 when energized.

[0032] The adsorption electrode 210 is coupled to an adsorption power source 212 through an RF filter 214 , and the adsorption power source 212 provides direct current (DC) power to electrostatically fix the substrate 145 to the upper surface of the substrate support 115 .

[0033] The power application system 220 is coupled to the substrate support 115. The power application system 220 includes a heater power supply 221, an adsorption power supply 212, a first radio frequency (RF) power supply 230, and a second RF power supply 240. The power application system 220 includes a controller 194 and a sensor device 250, which communicates with the controller 194 and with both the first RF power supply 230 and the second RF power supply 240. In some embodiments, the controller 194 is used to control the plasma from the process gas by applying RF power from the first RF power supply 230 and the second RF power supply 240 to deposit a material layer on the substrate 145.

[0034] The substrate support 115 also includes a second RF electrode 260, and applies RF power to tune the plasma together with the adsorption electrode 210. The first RF power source 230 is coupled to the second RF electrode 260, and the second RF power source 240 is coupled to the adsorption electrode 210. A first matching network and a second matching network are provided for the first RF power source 230 and the second RF power source 230, respectively.

[0035] The first RF power source 230 and the second RF power source 240 generate power of the same frequency or different frequencies. In one or more embodiments, one or more of the first RF power source 230 and the second RF power source 240 independently generate power at a frequency of about 350 KHz to about 100 MHz (e.g., 350 KHz, 2 MHz, 13.56 MHz, 27 MHz, 40 MHz, 60 MHz, or 100 MHz). In one or more embodiments, the first RF power source 230 generates power at a frequency of 13.56 MHz and the second RF power source 240 generates power at a frequency of 2 MHz, or vice versa. The RF power from one or both of the first RF power source 230 and the second RF power source 240 is varied to tune the plasma. For example, the sensor device 250 is used to monitor the RF energy from one or both of the first RF power source 230 and the second RF power source 240. The data from the sensor device 250 is transmitted to the controller 194, and the controller 194 is used to vary the power applied by the first RF power source 230 and the second RF power source 240.

[0036] In one or more embodiments, the substrate support 115 has an adsorption electrode 210 and an RF electrode separated from each other, and a first RF bias can be applied to the RF electrode 260, and a second RF bias can be applied to the adsorption electrode 210. In one or more examples, the first RF bias is provided at a frequency of about 350 KHz to about 100 MHz and a power of about 10 watts to about 3000 watts, and the second RF bias is provided at a frequency of about 350 KHz to about 100 MHz and a power of about 10 watts to about 3000 watts. In other examples, the first RF bias is provided at a frequency of about 13.56 MHz and a power of about 2500 watts to about 3000 watts, and the second RF bias is provided at a frequency of about 2 MHz and a power of about 800 watts to about 1200 watts.

[0037] In one or more embodiments, a deposition gas containing one or more hydrocarbon compounds and one or more dopant compounds flows or is otherwise introduced into a processing volume of a processing chamber (e.g., a PECVD chamber). The hydrocarbon compound and the dopant compound flow or are independently introduced into the processing volume. In some examples, one or more substrates are positioned on a substrate support in the processing chamber. The substrate support can have an adsorption electrode and an RF electrode separated from each other. A plasma is ignited or otherwise generated at or near the substrate (e.g., substrate level) by applying a first RF bias to the RF electrode and a second RF bias to the adsorption electrode. A doped diamond-like carbon film is deposited or otherwise formed on the substrate. In some embodiments, a patterned photoresist layer is deposited or otherwise formed on the doped diamond-like carbon film, the doped diamond-like carbon film is etched or otherwise formed into a pattern corresponding to the patterned photoresist layer, and the pattern is etched or otherwise formed into the substrate. Carbon film deposition process:

[0038] Figure 3 A flow chart depicting a method 300 for forming a doped diamond-like carbon film on a film stack disposed on a substrate according to one embodiment of the present disclosure. The doped diamond-like carbon film formed on the film stack is used, for example, as a hard mask to form a stair-like structure in the film stack. Figure 4A-4B is a schematic cross-sectional view illustrating a sequence for forming a doped diamond-like carbon film on a film stack disposed on a substrate according to method 300 .

[0039] At activity 302, a substrate (such as substrate 402 depicted in FIG. 4) is positioned in a processing chamber (such as Figure 1 The substrate 402 is disposed on a substrate support in a processing volume of the processing chamber 100 as depicted in FIG. Figure 1 and Figure 2 The substrate 145 shown in FIG. The substrate 402 is a silicon-based material or any suitable insulating material or conductive material as required, and has a film stack 404 disposed on the substrate 402, the film stack 404 forming a structure 400 in the film stack 404, such as a stair-like structure.

[0040] like Figure 4AAs shown in the depicted embodiment, substrate 402 has a substantially flat surface, an uneven surface, or a substantially flat surface with structures formed thereon. Film stack 404 is formed on substrate 402. In one or more embodiments, film stack 404 is used to form a gate structure, a contact structure, or an interconnect structure in a front-end or back-end process. Method 300 is performed on film stack 404 to form a stepped structure in film stack 404 for use in a memory structure (such as a NAND structure). In one or more embodiments, substrate 402 is a material such as crystalline silicon (e.g., Si <100> or Si <111> ), silicon oxide, strained silicon, silicon germanium, doped or undoped polysilicon, doped or undoped silicon substrates and patterned or unpatterned substrates, silicon on insulator (SOI), carbon-doped silicon oxide, silicon nitride, doped silicon, germanium, gallium arsenide, glass, sapphire. Substrate 402 may have various sizes, such as 200 mm, 300 mm, 450 mm or other diameter substrates, and rectangular or square flat panels. Unless otherwise stated, the embodiments and examples described herein are performed on substrates having a 200 mm diameter, 300 mm diameter, or 450 mm diameter substrate. In embodiments where an SOI structure is used for substrate 402, substrate 402 includes a buried dielectric layer disposed on a silicon crystalline substrate. In one or more embodiments described herein, substrate 402 is a crystalline silicon substrate.

[0041] In one or more embodiments, the film stack 404 disposed on the substrate 402 may have a plurality of vertically stacked layers. The film stack 404 may include a plurality of pairs of layers including a first layer (shown as 408a1, 408a2, 408a3, ..., 408a n ) and a second layer (shown as 408b1, 408b2, 408b3, ..., 408b n ), the first layer and the second layer are repeatedly formed in the film stack 404. The plurality of pairs of layers include alternating first layers (shown as 408a1, 408a2, 408a3, ..., 408a n ) and the second layer (shown as 408b1, 408b2, 408b3, ..., 408b n ), the first layer and the second layer are repeatedly formed until a desired number of pairs of the first layer and the second layer are reached.

[0042] The film stack 404 may be part of a semiconductor chip, such as a three-dimensional memory chip. Figure 4A-4B The first layer (shown as 408a1, 408a2, 408a3, ..., 408a n ) and a second layer (shown as 408b1, 408b2, 408b3, ..., 408b n), but it should be noted that any desired number of repeated pairs of the first and second layers may be used as desired.

[0043] In one or more embodiments, the film stack 404 forms a plurality of gate structures of a three-dimensional memory chip. The first layers 408a1, 408a2, 408a3, ..., 408a formed in the film stack 404 n The first dielectric layer may be a first dielectric layer, and the second layers 408b1, 408b2, 408b3, ..., 408b n The first layer 408a1, 408a2, 408a3, ..., 408a may be formed using a suitable dielectric layer. n and the second layers 408b1, 408b2, 408b3, ..., 408b n , including silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, silicon oxycarbide, titanium nitride, a composite of oxide and nitride, at least one or more oxide layers sandwiching a nitride layer, and combinations of the above. In one or more embodiments, the dielectric layer may be a high-k material having a dielectric constant greater than 4. Suitable examples of high-k materials include hafnium oxide, zirconium oxide, titanium oxide, hafnium silicon oxide or hafnium silicate, hafnium aluminum oxide or hafnium aluminate, zirconium silicon oxide or zirconium silicate, tantalum oxide, aluminum oxide, aluminum-doped hafnium dioxide, bismuth strontium titanium (BST) and platinum zirconium titanium (PZT), dopants of the foregoing, or any combination of the foregoing.

[0044] In one or more examples, the first layers 408a1, 408a2, 408a3, . . . 408a n is a silicon oxide layer, and the second layers 408b1, 408b2, 408b3, ..., 408b n It is arranged on the first layer 408a1, 408a2, 408a3, ..., 408a n In one or more embodiments, the first layers 408a1, 408a2, 408a3, . . . , 408a n The thickness of the second layer 408b1, 408b2, 408b3, ..., 408b n The thickness of the film stack 404 is controlled to be about 50 angstroms to about 1000 angstroms, such as about 500 angstroms. The film stack 404 may have a total thickness of about 100 angstroms to about 2000 angstroms. In one or more embodiments, the total thickness of the film stack 404 is about 3 microns to about 10 microns and can vary with technological advances.

[0045] It is noted that the doped diamond-like carbon film may be formed on any surface or any portion of the substrate 402, regardless of whether the film stack 404 is present on the substrate 402. In some embodiments, a clamping voltage is supplied to the substrate support to hold the substrate on the substrate support.

[0046] At activity 304, a plasma is generated above the substrate by applying an RF bias to the substrate support. In some embodiments, one or more RF biases are applied to the substrate support. A first RF bias is applied at a frequency of about 350 KHz to about 100 MHz (e.g., about 350 KHz, about 2 MHz, about 13.56 MHz, about 27 MHz, about 40 MHz, about 60 MHz, or about 100 MHz) with a power of about 10 watts to about 3000 watts. In one or more embodiments, the first RF bias is provided at a frequency of about 13.56 MHz with a power of about 2500 watts to about 3000 watts. In one or more embodiments, the first RF bias is provided to the substrate support 115 via the second RF electrode 260. The second RF electrode 260 may be in electrical communication with the first RF power supply 230, which supplies a bias voltage to the second RF electrode 260. In one or more embodiments, the bias power is about 10 W to about 3000 W, about 2000 W to about 3000 W, or about 2500 W to about 3000 W. The first RF power source 230 can generate power of about 350 KHz to about 100 MHz (e.g., about 350 KHz, about 2 MHz, about 13.56 MHz, about 27 MHz, about 40 MHz, about 60 MHz, or about 100 MHz).

[0047] In one or more embodiments, activity 304 further includes applying a second RF bias to the substrate support. A second RF bias of about 10 watts to about 3000 watts is applied at a frequency of about 350 KHz to about 100 MHz (e.g., about 350 KHz, about 2 MHz, about 13.56 MHz, about 27 MHz, about 40 MHz, about 60 MHz, or about 100 MHz). In some examples, the second RF bias is provided at a frequency of about 2 MHz and a power of about 800 watts to about 1200 watts. In other examples, the second RF bias is provided to the substrate 402 via the adsorption electrode 210. The adsorption electrode 210 can be electrically connected to a second RF power supply 240 that supplies a bias voltage to the adsorption electrode 210. In one or more examples, the bias power is about 10 watts to about 3000 watts, about 500 watts to about 1500 watts, or about 800 watts to about 1200 watts. The second RF power source 240 can generate power at about 350 KHz to about 100 MHz (eg, about 350 KHz, about 2 MHz, about 13.56 MHz, about 27 MHz, about 40 MHz, about 60 MHz, or about 100 MHz). In one or more embodiments, the clamping voltage provided in activity 302 is maintained during activity 304 .

[0048] In some embodiments, a first RF bias is provided to the substrate 402 via the adsorption electrode 210, and a second RF bias may be provided to the substrate 402 via the second RF electrode 260. In one or more examples, the first RF bias is about 2500 Watts (about 13.56 MHz) and the second RF bias is about 1000 Watts (about 2 MHz).

[0049] During activity 306, a deposition gas flows into the processing volume 160 to form a doped diamond-like carbon film on the film stack. The deposition gas contains one or more hydrocarbon compounds and one or more dopant compounds. The hydrocarbon compound can be or include one, two, or more hydrocarbon compounds in any state of matter. Similarly, the dopant compound can be or include one, two, or more dopant compounds in any state of matter.

[0050] In one or more embodiments, the hydrocarbon compound is a gaseous hydrocarbon or a liquid hydrocarbon. The hydrocarbon may be or include one or more alkanes, one or more alkenes, one or more alkynes, one or more aromatic hydrocarbons, or any combination thereof. In some examples, the hydrocarbon compound has the general formula C x H y , wherein x ranges from 1 to about 20, and y ranges from 1 to about 20. Suitable hydrocarbon compounds include, for example, C2H2, C3H6, CH4, C4H8, 1,3-dimethyladamantane, bicyclo[2.2.1]hepta-2,5-diene (2,5-norbornadiene), adamantane (C 10 H16 ), norbornene (C7H 10 ) or any combination thereof. In one or more examples, acetylene is used because a more stable intermediate species is formed, which allows for greater surface mobility.

[0051] The hydrocarbon compound may be or include one or more alkanes (e.g., C n H 2n+2 , wherein n is 1 to 20). Suitable hydrocarbon compounds include, for example, alkanes such as methane (CH4), ethane (C2H6), propane (C3H8), butane (C4H 10 ) and its isomers isobutane, pentane (C5H 12 ), hexane (C6H 14 ) and its isomers isopentane and neopentane, hexane (C6H 14 ) and its isomers 2-methylpentane, 3-methylpentane, 2,3-dimethylbutane and 2,2-dimethylbutane, or any combination thereof.

[0052] The hydrocarbon compound may be or include one or more olefins (e.g., C n H 2n , wherein n is 1 to 20). Suitable hydrocarbon compounds include, for example, olefins such as ethylene, propylene (C3H6), butene and its isomers, pentene and its isomers, etc., dienes such as butadiene, isoprene, pentadiene, hexadiene, or any combination of the above. Additional suitable hydrocarbons include, for example, halogenated olefins such as monofluoroethylene, difluoroethylene, trifluoroethylene, tetrafluoroethylene, monochloroethylene, dichloroethylene, trichloroethylene, tetrachloroethylene, or any combination of the above.

[0053] The hydrocarbon compound may be or include one or more alkynes (e.g., C n H 2n－2 , wherein n is 1 to 20). Suitable hydrocarbon compounds include, for example, alkynes such as acetylene (C2H2), propyne (C3H4), butene (C4H8), vinylacetylene, or any combination thereof.

[0054] The hydrocarbon compound may be or include one or more aromatic hydrocarbon compounds, such as benzene, styrene, toluene, xylene, ethylbenzene, acetophenone, methyl benzoate, phenyl acetate, phenol, cresol, furan, etc., α-terpinene, cymene, 1,1,3,3,-tetramethylbutylbenzene, tert-butyl ether, tert-butylethylene, methyl methacrylate, and tert-butyl furfuryl ether, compounds having the chemical formulas C3H2 and C5H4, halogenated aromatic compounds (including monofluorobenzene, difluorobenzene, tetrafluorobenzene, hexafluorobenzene), or any combination of the foregoing.

[0055] Exemplary silicon precursors can be or include monosilane, disilane, trisilane, butasilane, pentasilane, hexasilane, monochlorosilane, dichlorosilane, trichlorosilane, tetrachlorosilane, hexachlorosilane, substituted silanes, plasma derivatives thereof, or any combination thereof. Exemplary boron precursors can be or include diborane, triborane, butaborane, triethylborane (Et3B), dimethylamine borane, or any combination thereof.

[0056] In one or more embodiments, the deposition gas further comprises one or more diluent gases, one or more carrier gases, and / or one or more purge gases. Suitable diluent gases, carrier gases and / or purge gases such as helium (He), argon (Ar), xenon (Xe), hydrogen (H2), nitrogen (N2), ammonia (NH3), nitric oxide (NO), or any combination thereof, etc., may flow with the deposition gas or otherwise be supplied to the processing volume 160. Argon, helium and / or nitrogen may be used to control the density and deposition rate of the doped diamond-like carbon film. In some cases, the addition of N2 and / or NH3 can be used to control the hydrogen ratio of the doped diamond-like carbon film, as discussed below. Alternatively, no diluent gas may be used during deposition.

[0057] In some embodiments, the deposition gas further comprises an etchant gas. Suitable etchant gases may be or include chlorine (Cl2), fluorine (F2), hydrogen fluoride (HF), carbon tetrafluoride (CF4), nitrogen trifluoride (NF3), or any combination thereof. Without being bound by theory, it is believed that the etchant gas selectively etches the sp 2 Hybridize carbon atoms, thereby increasing the sp 3 The ratio of hybridized carbon atoms increases the etch selectivity of the film.

[0058] In activity 308, a doped diamond-like carbon film is deposited on a substrate. The substrate temperature is about 50°C to about 650°C, such as about 10°C to about 600°C, such as about 300°C to about 550°C. The chamber pressure is about 0.5 mTorr to about 10 Torr (e.g., about 2 mTorr to about 50 mTorr; or about 2 mTorr to about 10 mTorr). The flow rate of the hydrocarbon compound is about 10 sccm to about 1000 sccm (e.g., about 100 sccm to about 200 sccm or about 150 sccm to about 200 sccm). The flow rate of the dopant compound is about 1 sccm to about 500 sccm (e.g., about 10 sccm to about 150 sccm or about 20 sccm to about 100 sccm, such as about 40 sccm to about 60 sccm). The flow rate of the dilution gas or the purge gas is about 50 sccm to about 50,000 sccm (eg, about 50 sccm to about 500 sccm; or about 50 sccm to about 100 sccm). Table 1 below describes process conditions of an example method of the present disclosure. Table 1

[0059] The doped diamond-like carbon film is deposited to a thickness of about 5 angstroms to about 20,000 angstroms (e.g., about 300 angstroms to about 5,000 angstroms; about 2,000 angstroms to about 3,000 angstroms, or about 5 angstroms to about 200 angstroms). The above process parameters depicted in Table 1 provide a deposition chamber (such as Figure 1 Example of process parameters for a 300 mm substrate in a chamber depicted in FIG.

[0060] In some embodiments, the doped diamond-like carbon film includes about 5 atomic percent to about 25 atomic percent of a dopant, such as about 5 atomic percent to about 10 atomic percent, or about 15 atomic percent to about 20 atomic percent, or about 8 atomic percent to about 15 atomic percent of a dopant. In some embodiments, the doped diamond-like carbon film has a density of about 1.5 g / cc to about 3.0 g / cc, such as about 2.0 g / cc to about 2.8 g / cc. Without being bound by theory, it is believed that doping the carbon film with a concentration lower than that disclosed herein will hardly or completely increase thermal stability. In addition, doping with a concentration higher than that disclosed herein will reduce the film modulus and etching selectivity of the resulting film. It has been found that the dopant concentrations advocated can enhance thermal stability while maintaining carbon film properties, such as film modulus and etching selectivity.

[0061] The doped diamond-like carbon film has a first stress property (MPa) less than -100 MPa, such as about -1100 MPa to about -500 MPa, such as about -750 MPa to about -600 MPa. The doped diamond-like carbon film has a density (g / cc) greater than 1.5 g / cc, such as about 2 g / cc or greater, such as about 2.8 g / cc to about 3.0 g / cc. The doped diamond-like carbon film has an elastic modulus (GPa) greater than 75 GPa, such as about 100 GPa to about 175 GPa.

[0062] In activity 310, the doped diamond-like carbon film is annealed at a temperature of about 220°C to about 450°C. In some embodiments, the doped diamond-like carbon film is annealed in the same processing volume 160. Alternatively, the doped diamond-like carbon film is annealed in a second processing chamber (e.g., a high temperature furnace). The doped diamond-like carbon film is annealed for about 1 minute to about 1 hour, such as about 5 minutes to about 30 minutes, such as about 10 minutes to about 20 minutes. The etch selectivity of the annealed doped diamond-like carbon film is about 0.9 to about 1.3. The annealed doped diamond-like carbon film includes a second stress property. The absolute value of the second stress property is less than or within 10% of the first stress property of the doped diamond-like carbon film before annealing. In some embodiments, the second stress property has an absolute value less than the first stress property. In some embodiments, the stress property is tested by measuring the substrate bending using an optical metrology method. In some embodiments, the annealed film includes about 50 atomic percent to about 80 atomic percent, such as about 60 atomic percent to about 70 atomic percent sp 3 Hybridized carbon atoms.

[0063] In some embodiments, the etch selectivity of the annealed doped diamond-like carbon film is substantially equal to or greater than the etch selectivity of the doped diamond-like carbon film before annealing. In some embodiments, the annealed doped diamond-like carbon film has substantially the same modulus as the doped diamond-like carbon film before annealing.

[0064] In activity 312, a patterned photoresist is formed over the annealed film, and in activity 314, the annealed film is etched in a pattern corresponding to the patterned photoresist layer. Example

[0065] Figure 5A diagram schematic 500 is depicted of two comparative samples (e.g., B1, B2) of diamond-like carbon films that do not include a dopant and four samples (e.g., B3, B4, B5, B6) of diamond-like carbon films that include boron doping. The four samples are arranged from the lowest doping concentration to the highest doping concentration, with B3 having the lowest boron concentration and B6 having the highest boron concentration. The stress properties of each sample are tested before and after thermal annealing (such as the annealing described herein). Each comparative sample shows an increase in absolute stress value (e.g., a decrease in stress value). The boron-doped samples with the two lowest boron concentrations also show an increase in absolute stress value. However, the increase is reduced relative to the undoped sample, showing better thermal stability. The remaining doped samples all show a decrease in absolute stress value after annealing. All doped samples substantially maintain similar modulus values ​​and etching selectivities relative to the undoped sample. Without being bound by theory, it is believed that annealing the pure carbon film causes the conversion of carbon-carbon single bonds (CC) to reduced carbon-carbon double bonds (C=C). Providing dopants such as silicon prevents the formation of double bonds that would otherwise occur between carbon atoms because silicon and carbon atoms cannot form silicon-carbon double bonds (Si=C). Dopants such as silicon and boron provide enhanced thermal stability after annealing conditions.

[0066] Similarly, Figure 6 A diagram schematic diagram 600 depicting an undoped diamond-like carbon film sample (e.g., S1) and three silicon-doped diamond-like carbon films (e.g., S2, S3, S4) before and after annealing. The three samples are arranged from the lowest doping concentration to the highest doping concentration, wherein S2 has the lowest silicon doping concentration and S4 has the highest silicon doping concentration. The stress properties of each sample are tested before and after thermal annealing (e.g., annealing described herein). The undoped sample shows the result of an increase in absolute stress after annealing. The silicon-doped sample S2 with the lowest silicon concentration also shows an increase in absolute stress, but the increase is smaller than that of the undoped sample. The remaining samples all show a decrease in absolute stress values. Relative to the undoped sample, all doped samples substantially maintain similar modulus values ​​and etching selectivity. Relative to the boron-doped sample, the silicon-doped sample shows an increased modulus. Relative to the silicon-doped sample, the boron-doped sample shows an increased etching selectivity. Without being bound by theory, it is believed that the silicon dopant in the sample is potentially bonded to the carbon in the film. It is believed that the carbon-silicon bonds exhibit an increased modulus relative to carbon bonds within a film without the silicon dopant.

[0067] Table 2 depicts the physical properties of samples such as Figure 5 and Figure 6As shown in the table below, samples with low concentrations of dopants show enhanced thermal stability relative to undoped samples, as evidenced by the reduced change in stress after annealing of the samples. Samples with higher dopant concentrations show evidence of better thermal stability as the absolute stress values ​​after annealing are further reduced relative to the as deposited samples with dopants. Etch selectivity was also measured after annealing, and the range of etch selectivity across all samples remained in the range of about 0.9% to about 1.4%. Table 2

[0068] In summary, a process is provided herein that includes doping a diamond-like carbon film with silicon or boron dopants. The diamond-like carbon film is further annealed to produce a film with good thermal stability. The process described herein enhances thermal stability while minimizing the impact on other properties such as modulus and etch selectivity.

Claims

1. A method for processing a substrate, comprising: flowing a deposition gas comprising a hydrocarbon compound and a dopant compound into a processing volume of a processing chamber, the processing volume having a substrate positioned on a substrate support, wherein the processing volume is maintained at a pressure of about 0.5 mTorr to about 10 mTorr; generating a plasma at the substrate by applying a first RF bias to the substrate support to deposit a doped diamond-like carbon film on the substrate, the doped diamond-like carbon film including about 5 atomic percent to about 25 atomic percent of a dopant, the doped diamond-like carbon film having a first stress property; and The doped diamond-like carbon film is annealed at about 220° C. to about 450° C. to form an annealed film having a second stress property having an absolute value less than or within 10% of the first stress property.

2. The method of claim 1, wherein the annealed film has a density of about 2.0 g / cc to about 3.0 g / cc.

3. The method of claim 1, wherein the dopant compound comprises boron, silicon, or both.

4. The method of claim 1, wherein the dopant compound comprises: Disilane, diborane, triethylborane, monosilane, disilane, trisilane, derivatives thereof, or any combination thereof.

5. The method of claim 1, wherein the doped diamond-like carbon film comprises about 8 atomic percent to about 15 atomic percent of a dopant.

6. The method of claim 1, wherein the annealed film comprises about 50 atomic percent to about 80 atomic percent sp 3 Hybridized carbon atoms.

7. The method of claim 1, wherein the hydrocarbon compound comprises: Ethylene, propylene, methane, butene, 1,3-dimethyladamantane, bicyclo[2.2.1]hepta-2,5-diene, adamantane, norbornene, or any combination thereof.

8. The method of claim 1, wherein the annealed film has an etch selectivity of about 0.9 to about 1.

3.

9. The method of claim 1, wherein the processing volume is maintained at a pressure of about 5 mTorr to about 10 mTorr, and wherein the substrate is maintained at a temperature of about 0°C to about 50°C.

10. The method of claim 1, wherein the annealed film is a silicon-doped annealed film and has an elastic modulus greater than 150 GPa.

11. The method of claim 1 , wherein generating the plasma at the substrate further comprises: A second RF bias is applied to the substrate support.

12. The method of claim 11, wherein the first RF bias is provided at a power of about 10 Watts to about 3000 Watts at a frequency of about 350 KHz to about 100 MHz, and wherein the second RF bias is provided at a power of about 10 Watts to about 3000 Watts at a frequency of about 350 KHz to about 100 MHz.

13. The method of claim 1, wherein the doped diamond-like carbon film is annealed for a period of about 1 minute to about 30 minutes.

14. A method for processing a substrate, comprising: flowing a deposition gas into a processing volume of a processing chamber, the deposition gas comprising a hydrocarbon compound and a dopant compound, the dopant compound comprising silicon, the processing volume having a substrate positioned on a substrate support, wherein the substrate support has an adsorption electrode and an RF electrode spaced apart from the adsorption electrode, wherein the processing volume is maintained at a pressure of about 0.5 mTorr to about 10 Torr; generating a plasma at the substrate by applying a first RF bias to the RF electrode and a second RF bias to the adsorption electrode to deposit a doped diamond-like carbon film on the substrate, wherein the doped diamond-like carbon film has a density of greater than 2 g / cc to about 12 g / cc and a first stress of about -300 MPa to about -150 MPa; and The doped diamond-like carbon film is annealed at a temperature of about 220° C. to about 450° C. to form an annealed film having a second stress of about −250 MPa to about −100 MPa.

15. The method of claim 14, wherein the doped diamond-like carbon film has a density of about 3 g / cc to about 10 g / cc.

16. The method of claim 14, wherein the annealed film has an etch selectivity of about 0.9 to about 1.

3.

17. The method of claim 14, wherein the doped diamond-like carbon film comprises about 8 atomic percent to about 15 atomic percent of the dopant.

18. A method for processing a substrate, comprising: positioning the substrate on a substrate support in a processing volume; generating a plasma above the substrate by applying an RF bias to the substrate support; providing a deposition gas comprising a hydrocarbon compound and a dopant compound comprising boron or silicon into a processing volume of a processing chamber, wherein the substrate support has an adsorption electrode and an RF electrode spaced apart from the adsorption electrode, wherein the processing volume is maintained at a pressure of about 0.5 mTorr to about 10 mTorr; generating a plasma at the substrate by applying a first RF bias to the RF electrode and a second RF bias to the adsorption electrode to deposit a doped diamond-like carbon film on the substrate, wherein the doped diamond-like carbon film has a density of greater than 2 g / cc to about 12 g / cc and a stress of about -600 MPa to about -300 MPa; annealing the doped diamond-like carbon film at a temperature of about 220° C. to about 450° C. to form an annealed film having a second stress of about −250 MPa to about −100 MPa; forming a patterned photoresist layer over the annealed film; etching the annealed film in a pattern corresponding to the patterned photoresist layer; as well as The pattern is etched into the substrate.

19. The method of claim 18, wherein the doped diamond-like carbon film comprises about 8 atomic percent to about 15 atomic percent of the dopant.

20. The method of claim 18, wherein the annealed film is an annealed silicon doped film and has an elastic modulus greater than 150 GPa.

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