Nitrogen-doped carbon hardmask films

Abstract

Disclosed herein are methods and apparatus for forming a carbon hard mask that improves deposition uniformity and etch selectivity. The carbon hard mask can be formed in a PECVD process chamber and is a nitrogen-doped carbon hard mask. The nitrogen-doped carbon hard mask is formed using a nitrogen-containing gas, an argon-containing gas, and a hydrocarbon gas.

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE Embodiments of the present disclosure relate generally to the fabrication of integrated circuits, processes for depositing materials on substrates, and structures formed from the materials. [Background technology]

[0002] 2. Description of Related Art Reducing the size of integrated circuits (ICs) leads to improved performance, increased capacity, and / or reduced production costs. Each size reduction requires more advanced techniques for forming ICs. Photolithography is typically used to pattern ICs on a substrate. Producing patterned material on a substrate requires a controlled method for the removal of exposed material. Carbon-based films can be used as hard masks and etch stop layers in semiconductor processing, including during memory and logic device fabrication. As aspect ratios in lithography increase, hard masks require higher etch selectivity.

[0003] Current methods for forming carbon hardmasks use plasma enhanced chemical vapor deposition (PECVD) processes, which result in hardmasks with poor deposition uniformity and low etch selectivity. Therefore, there is a need in the art for methods for forming carbon hardmasks that improve deposition uniformity and etch selectivity. Summary of the Invention

[0004] Embodiments of the present disclosure generally relate to a method for forming a nitrogen-doped carbon hard mask. In one embodiment, the method includes flowing an argon-containing gas into a process chamber, flowing a nitrogen-containing gas into the process chamber, igniting a plasma in the process chamber, flowing a precursor gas into the process chamber after igniting the plasma, performing a deposition process at a temperature between about 560° C. and about 700° C., and forming the nitrogen-doped carbon hard mask.

[0005] In another embodiment, a method includes flowing an argon-containing gas into a process chamber, flowing a nitrogen-containing gas into the process chamber, applying radio frequency power to the argon-containing gas and the nitrogen-containing gas to ignite a plasma, flowing a precursor gas into the process chamber after igniting the plasma, performing a deposition process at a temperature between about 560°C and about 700°C, and forming a nitrogen-doped carbon hard mask.

[0006] In another embodiment, a method includes flowing an argon-containing gas into a process chamber; flowing a nitrogen-containing gas into the process chamber, wherein the ratio of the nitrogen-containing gas to the argon-containing gas is about 1:3 to about 1:10; applying radio frequency power to the argon-containing gas and the nitrogen-containing gas to ignite a plasma; after igniting the plasma, flowing an organic precursor gas into the process chamber; performing a deposition process at a temperature of about 560° C. to about 700° C.; and forming a nitrogen-doped carbon hard mask on a substrate in the process chamber.

[0007] So that the above-recited features of the present disclosure may be understood in detail, a more particular description of the present disclosure briefly summarized above may be made by reference to embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings illustrate only exemplary embodiments and therefore should not be considered limiting of its scope, as other equally effective embodiments may be recognized. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic cross-sectional view of a process chamber equipped to perform a plasma enhanced chemical vapor deposition (PECVD) process. [Figure 2A] 1A-1C are cross-sectional views of a device at various stages in processing. [Figure 2B] 1A-1C are cross-sectional views of a device at various stages in processing. [Figure 2C] 1A-1C are cross-sectional views of a device at various stages in processing. [Figure 3] 1 is a cross-sectional view of a substrate support, a substrate, and a plasma during a PECVD (plasma-enhanced chemical vapor deposition) process. [Figure 4] FIG. 1 illustrates a method for depositing a nitrogen-doped carbon hard mask. [Figure 5] 1 is a graph illustrating mask thickness at the edge of a substrate. [Figure 6] 1 is a chart illustrating the difference in film thickness after a first process and after a second process. DETAILED DESCRIPTION OF THE INVENTION

[0009] To facilitate understanding, like reference numerals have been used, where possible, to designate like 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.

[0010] 1 is a schematic cross-sectional view of a process chamber 100 equipped to perform a plasma enhanced chemical vapor deposition (PECVD) process. The processing chamber 100 features a chamber body 102, a substrate support 104 disposed within the chamber body 102, and a lid assembly 106 coupled to the chamber body 102 and enclosing the substrate support 104 in a processing volume 120. A substrate is provided to the processing volume 120 through an opening 126 that can be sealed for processing using a valve.

[0011] The first electrode 108 is disposed adjacent to the chamber body 102 and separates the chamber body 102 from other components of the lid assembly 106. The first electrode 108 can be part of the lid assembly 106 or can be a separate sidewall electrode. The first electrode 108 can be an annular or ring-shaped member and can be a ring electrode. The first electrode 108 can be a continuous loop around the circumference of the processing chamber 100 surrounding the processing volume 120, or can be discontinuous at selected locations, if desired. The first electrode 108 can be a perforated electrode, such as a perforated ring or mesh electrode. The first electrode 108 can also be a plate electrode, e.g., a secondary gas distributor.

[0012] An isolator 110, which is a dielectric material such as a ceramic or metal oxide, e.g., aluminum oxide and / or aluminum nitride, contacts the first electrode 108 and electrically and thermally isolates the first electrode 108 from a gas distributor 112 and from the chamber body 102. The gas distributor 112 features openings 118 for admitting process gases into the processing volume 120. The gas distributor 112 is coupled to a power source 142, such as an RF generator. DC power, pulsed DC power, and pulsed RF power may also be used.

[0013] The gas distributor 112 can be a conductive gas distributor or a non-conductive gas distributor. The gas distributor 112 can be made of conductive and non-conductive components. For example, the body of the gas distributor 112 can be conductive and the faceplate of the gas distributor 112 is non-conductive. In a plasma processing chamber, the gas distributor 112 can be powered, as shown in FIG. 1, or the gas distributor 112 can be coupled to ground.

[0014] The electrode 108 is coupled to a tuning circuit 128 that controls the path to ground of the processing chamber 100. The tuning circuit 128 includes an electronic sensor 130 and an electronic controller 134, which may be a variable capacitor. The tuning circuit 128 may be an LLC circuit including one or more inductors 332. The tuning circuit 128 may be any circuit that features a variable or controllable impedance under the plasma conditions present in the processing volume 120 during processing. In the embodiment of FIG. 1, which may be combined with other embodiments, the tuning circuit 128 features a first inductor 132A in series with the electronic controller 134 and a second inductor 132B in parallel with the electronic controller 134. The electronic sensor 130 may be a voltage or current sensor and may be coupled to the electronic controller 134 to provide some degree of closed-loop control of the plasma conditions in the processing volume 120.

[0015] A second electrode 122 is coupled to or disposed within the substrate support 104. The second electrode 122 may be a plate, a perforated plate, a mesh, a wire screen, or any other distributed arrangement. The second electrode 122 may be a tuning electrode and may be coupled to a second tuning circuit 136 by a conduit 146 disposed in a shaft 144 of the substrate support 104. The second tuning circuit 136 includes a second electronic sensor 138 and a second electronic controller 140, which may be a second variable capacitor. The second electronic sensor 138 may be a voltage or current sensor and may be coupled to the second electronic controller 140 to provide further control over the plasma conditions in the process volume 120.

[0016] A third electrode 124, which may be a bias electrode and / or an electrostatic chuck electrode, is coupled to the substrate support 104. The third electrode is coupled through a filter 148 to a second power source 150, which may be an impedance matching circuit 180. The second power source 150 may be DC power, pulsed DC power, RF power, pulsed RF power, or a combination thereof.

[0017] 1 can be used with any processing chamber for plasma or thermal processing. One example of a plasma processing chamber with which the lid assembly 106 and substrate support 104 can be beneficially used is the PRODUCER® platform and chamber available from Applied Materials, Inc., located in Santa Clara, California. Chambers from other manufacturers may also be used with the components described above.

[0018] During operation, the processing chamber 100 provides real-time control of plasma conditions in the processing volume 120. A substrate is disposed on the substrate support 104, and process gases are flowed through the lid assembly 106 according to any predetermined flow scheme. For example, process gases are flowed through an inlet 114 into a plenum 116. The process gases then flow from the plenum through an opening 118 into the processing volume. The gases exit the chamber 100 through an outlet 152. Power is coupled to the gas distributor 112 to establish a plasma in the processing volume 120. The substrate can be electrically biased, if desired, using a third electrode 124.

[0019] Upon energizing the plasma in the process volume 120, a potential difference is established between the plasma and the first electrode 108. A potential difference is also established between the plasma and the second electrode 122. Electronic controllers 134 and 140 are then used to adjust the flow characteristics of the ground paths represented by the two tuned circuits 128 and 136. Set points can be communicated to the first tuned circuit 128 and the second tuned circuit 136 to provide independent control of the deposition rate and of the center-to-edge plasma density uniformity. In embodiments in which both electronic controllers are variable capacitors, electronic sensors can independently adjust the variable capacitors to maximize the deposition rate and minimize thickness non-uniformity.

[0020] A controller, such as controller 160, may be part of the processing chamber 100. The controller 160 controls the processes and operations within the processing chamber 100. The controller 160 may also control the supply of power to any of the electrodes described herein, such as the first electrode 108, the second electrode 122, and the third electrode 124.

[0021] Although the figure illustrates a process chamber 100 that may be used with embodiments of the present disclosure, it is contemplated that other process chambers may also benefit from or be used to implement the embodiments described herein.

[0022] 2A-2C are cross-sectional views of device 200a during different operations of processing. Referring to FIG. 2A, device 200a includes a substrate 202, a hard mask layer 204, and a photoresist layer 206. Photoresist layer 206 is disposed on hard mask layer 204. The hard mask layer is disposed on substrate 202.

[0023] Substrate 202 can be any suitable substrate. In one embodiment, substrate 202 can be a silicon substrate, such as a silicon wafer. In another embodiment, substrate 202 can be a doped silicon substrate. Alternatively, substrate 202 can be a combination of multiple semiconductor device layers. While substrate 202 is a continuous layer as shown, other topographies, including device features formed in substrate 202, are contemplated.

[0024] The hard mask layer 204 is a doped carbon hard mask film. The doped carbon hard mask film may be a nitrogen-doped carbon hard mask film. The hard mask layer 204 may be deposited on the substrate 202 by a PECVD process. The hard mask layer 204 in the device 200a is a continuous layer. The hard mask layer 204 is formed over the entire substrate 202. The photoresist layer 204 has a first thickness D1. The first thickness D1 of the hard mask layer 204 is from about 1 μm to about 5 μm, such as from about 1.5 μm to about 4 μm, such as from about 1.7 μm to about 3.5 μm. In some embodiments, the thickness of the hard mask layer 204 is greater than 1.5 μm, such as greater than 1.7 μm.

[0025] In device 200a, photoresist layer 206 has a top resist surface 208 and a bottom resist surface 210. Bottom resist surface 210 contacts top mask surface 212. Top mask surface 212 is the top surface of hard mask layer 204. The bottom surface of hard mask layer 204 is bottom mask surface 214. Bottom mask surface 214 contacts top substrate surface 216. Top substrate surface 216 is the top surface of substrate 202.

[0026] The photoresist layer 206 may be any suitable photoresist material and may be deposited on the substrate by any suitable deposition process. The photoresist layer 206 may be a negative or positive photoresist. In one example, the photoresist is a diazonaphthoquinone-novolac resin. The photoresist layer 206 of the device 200a is a continuous layer of photoresist. The photoresist layer 206 is planar and has a constant, predetermined thickness. The thickness of the photoresist layer 206 is a second thickness D2. The second thickness D2 of the photoresist layer 206 is from about 0.5 μm to about 2.5 μm, such as from about 1 μm to about 2 μm. Another hard mask layer (not shown) may be disposed below the photoresist layer 206 to transfer the pattern to the doped carbon hard mask. The thickness of the other hard mask layer (not shown) may be from about 0.5 μm to about 1.5 μm, such as from about 1 μm.

[0027] 2B is a cross-sectional side view of device 200b at a second point in time. Device 200b is similar to device 200a described in FIG. 2A. In device 200b, photoresist layer 206 is exposed to a photon source, and then opening 220 is subsequently etched through photoresist layer 206.

[0028] The opening 220 includes sidewalls 218. The sidewalls 218 are vertical sidewalls, but may alternatively be formed at an angle. The opening 220 in the photoresist layer 206 extends vertically through the photoresist layer 206. The opening 220 extends through the bottom resist surface 210, and thus the opening 220 exposes a portion of the top mask surface 212. In this embodiment, the opening 220 extends through the entire second thickness D2 of the photoresist layer 206.

[0029] The openings 220 are formed by an exposure process, followed by baking and / or development. The patterned photoresist layer can be patterned by any suitable method, such as exposure to an etchant. The patterned photoresist layer patterns the hard mask layer 204. An etching process that has a relatively high etch selectivity for the hard mask layer 204 is utilized. High etch selectivity increases pattern fidelity and linewidth control.

[0030] 2C is a cross-sectional side view of device 200 at a third point in time. Device 200c is similar to devices 200a and 200b described in FIGS. 2A-2B. In device 200c, hard mask layer 204 is selectively etched and photoresist layer 206 is removed. Hard mask openings 222 are formed in a predetermined pattern through hard mask layer 204.

[0031] The hard mask openings 222 have sidewalls 224 and a bottom surface 226 within each of the hard mask openings 222. The sidewalls 224 are vertical walls that extend into the hard mask layer 204. The bottom surface 226 of the hard mask openings 222 is the bottom resist surface 214, and therefore the depth D3 of the openings 222 is equal to the first thickness D1 of the photoresist layer 204. The hard mask openings 222 have a depth D3 equal to the first thickness D1 of the hard mask layer 204. When the depth D3 of the hard mask openings 222 is equal to the first thickness D1 of the hard mask layer 204, the bottom surface 226 of the hard mask openings 222 is the upper substrate surface 214.

[0032] 3 is a cross-sectional side view of the substrate support 104 during a PECVD process. The substrate support 104 includes a support surface 310, a plurality of support posts 308 disposed on the support surface 310, and an edge ring 302 surrounding the support surface 310. The edge ring 302 and the support surface 310 form a pocket 312 in which the substrate 202 is disposed. The substrate 202 is disposed on the plurality of support posts 308 within the pocket 312. An upper surface 314 of the support posts 308 defines a receiving surface for the substrate 202.

[0033] The top surfaces of the plurality of support posts 308 are substantially coplanar. The plurality of support posts 308 may be any suitable shape, such as rectangular, circular, oval, hexagonal, or other shapes. The support posts 308 are designed to reduce backside damage to the substrate 202 and reduce temperature variations across the substrate 202. The edge ring 302 extends above the top surfaces 324 of the support posts 308 and surrounds the support surface 310. When the substrate 202 is placed on the plurality of support posts 308, the edge ring 302 extends around the outer circumference of the substrate 202. In embodiments in which the substrate 202 is non-circular, the edge ring 302 extends around the outer periphery of the substrate 202.

[0034] A plasma 306 is formed above the substrate 202. The plasma 306 is formed from a combination of process gases, such as a nitrogen-containing gas, argon, and a hydrocarbon precursor. The gases used to form the plasma 306 enter the chamber through the inlet 114 and the opening 118 in the gas distributor 112 (shown in FIG. 1 ). The plasma 306 is formed and controlled by supplying power to a combination of the first electrode 108, the second electrode 122, and / or the third electrode 124. The plasma can be used to deposit a carbon hard mask, such as a nitrogen-doped carbon hard mask.

[0035] 4 is a diagram of a method 400 for depositing a nitrogen-doped carbon hard mask. The nitrogen-doped hard mask is formed using a nitrogen-containing gas, argon gas, and a hydrocarbon precursor gas.

[0036] Method 400 is performed at a temperature between about 560 degrees Celsius (°C) and about 700°C. In some embodiments, method 400 can be performed at a temperature between about 600°C and about 650°C, such as about 620°C and about 640°C, such as about 630°C. Method 400 is performed at a pressure between about 6 Torr and about 12 Torr. In some embodiments, method 400 is performed at a pressure between about 8 Torr and about 10 Torr, such as between 8 Torr and about 9 Torr or between 9 Torr and about 10 Torr.

[0037] The method 400 includes a first operation 402 of flowing an argon-containing gas and a nitrogen-containing gas into a process chamber. The process chamber may be the processing chamber 100 of FIG. 1. The argon-containing gas is elemental argon (Ar). The nitrogen-containing gas may be diatomic nitrogen (N), nitrogen dioxide (NO), ammonia (NH), or other suitable nitrogen-containing gas.

[0038] The argon-containing gas is flowed into the process chamber at a flow rate of about 2000 sccm to about 4000 sccm. In some embodiments that can be combined with other embodiments, the flow rate of the argon-containing gas is about 2100 sccm to about 2750 sccm. In some embodiments that can be combined with other embodiments, the flow rate of the argon-containing gas is about 2100 sccm to about 2200 sccm. In other embodiments that can be combined with still other embodiments, the flow rate of the argon-containing gas is about 3000 to about 4000 sccm, such as about 3250 sccm to about 3750 sccm, such as about 3400 sccm to about 3650 sccm, or about 2500 sccm to about 3550 sccm.

[0039] The nitrogen-containing gas is flowed into the process chamber at a flow rate of about 250 sccm to about 1000 sccm. In some embodiments that can be combined with other embodiments, the flow rate of the nitrogen-containing gas is about 350 to about 900 sccm. In some embodiments that can be combined with other embodiments, the flow rate of the nitrogen-containing gas is about 350 sccm to about 600 sccm, such as about 400 sccm to about 550 sccm, such as about 450 sccm to about 550 sccm. In other embodiments that can be combined with still other embodiments, the flow rate of the nitrogen-containing gas is about 500 sccm to about 1100 sccm, such as about 550 sccm to about 1000 sccm, such as about 650 sccm to about 950 sccm, or such as about 700 sccm to about 900 sccm.

[0040] In some embodiments, which may be combined with other embodiments, the flows of the argon-containing gas and the nitrogen-containing gas may flow at different rates throughout the method 400. In other embodiments, the flow rates of the argon-containing gas and the nitrogen-containing gas are constant throughout the method 400.

[0041] The ratio of the flow rate of the nitrogen-containing gas to the flow rate of the argon-containing gas is about 1:3 to about 1:10. In some embodiments, which may be combined with other embodiments, the ratio of the flow rate of the nitrogen-containing gas to the flow rate of the argon-containing gas is about 1:3 to about 1:6, such as about 1:3 to about 1:5, such as about 1:3.5 to about 1:5, such as about 1:4 to about 1:5.

[0042] In some embodiments that may be combined with other embodiments, the argon-containing gas and the nitrogen-containing gas may begin flowing into the process chamber separately, such that either the argon-containing gas or the nitrogen-containing gas is introduced alone first. In some embodiments that may be combined with other embodiments, the argon-containing gas is flowed into the process chamber first before the nitrogen-containing gas is introduced into the chamber. In other embodiments that may be combined with other embodiments, the nitrogen-containing gas is flowed into the process chamber first before the argon-containing gas is introduced into the chamber. In some embodiments that may be combined with other embodiments, both the argon-containing gas and the nitrogen-containing gas are flowed into the process chamber simultaneously.

[0043] After the first operation 402, a second operation 404 is performed in which a plasma is ignited in the process chamber from the nitrogen-containing gas and the argon-containing gas introduced into the process chamber in the first operation 402.

[0044] Igniting the plasma in the process chamber during the second operation 404 includes applying RF power between about 2000 Watts and about 5500 Watts, such as between about 2000 Watts and about 5000 Watts, such as between about 2000 Watts and about 4000 Watts. In some embodiments, which may be combined with other embodiments, RF power between about 2000 Watts and about 2250 Watts is applied to ignite the plasma in the process chamber. In other embodiments, which may be combined with other embodiments, RF power between about 3000 Watts and about 5500 Watts, such as between about 3250 Watts and about 5000 Watts, such as between about 3250 Watts and about 4500 Watts, or such as between about 3400 Watts and about 4000 Watts is applied to ignite the plasma in the process chamber.

[0045] RF power is applied to the gas distributor 112 (shown in FIG. 1 ) by a power source 142, which ignites a plasma between the gas distributor and the substrate support 104 by applying RF power to the argon-containing gas and the nitrogen-containing gas. The electrode 108 and the second electrode 122 can be separately utilized to control the plasma shape and flow within the process volume 120.

[0046] The RF power is maintained after the initial ignition of the plasma and during subsequent operations, such as the third operation 406 and the fourth operation 408 of the method 400 described herein.

[0047] A third operation 406 of method 400 is performed after second operation 402 and igniting the plasma. In third operation 406, a precursor gas is flowed into the process chamber. The precursor gas is a hydrocarbon or organic compound gas suitable for depositing a carbon hard mask. For example, the precursor gas may be acetylene (C2H2), methane (CH4), ethane (C2H6), propane (C3H8), propene (C3H6), cyclopropane (C3H6), butane (C4H 10 ), pentane (CH 12 ), hexane (CH 14 ), heptane (C7H 16 ), octane (C8H 18), Nonane (C9H 20 ), Decane (C 10 H 22 ), Undecane (C 11 H 24 ), or dodecane (C 12 H 26 ) etc. Other organic compounds may also be utilized.

[0048] The precursor gas flow rate can be from about 300 sccm to about 900 sccm, such as from about 350 sccm to about 800 sccm, such as from about 350 sccm to about 750 sccm. In some embodiments, the precursor gas flow rate can be from about 300 to about 500 sccm, such as from about 350 sccm to about 450 sccm. In other embodiments, the precursor gas flow rate can be from about 500 sccm to about 900 sccm, such as from about 550 sccm to about 800 sccm, such as from about 600 sccm to about 750 sccm, or from about 650 sccm to about 700 sccm.

[0049] The ratio of the flow rate of the precursor gas to the flow rate of the combined argon-containing gas and nitrogen-containing gas can be about 1:15 to about 1:3, such as about 1:10 to about 1:5, such as about 1:9 to about 1:6, such as about 1:8 to about 1:6, such as about 1:7 to about 1:6. Introduction of the precursor gas enables deposition of a carbon hard mask because the precursor gas ionizes as a result of the plasma formed in operation 404. If a larger ratio of the precursor gas to the argon-containing gas and the nitrogen-containing gas is used, the composition of the hard mask changes such that the ratio of nitrogen to carbon in the hard mask decreases. If a smaller ratio of the precursor gas to the argon-containing gas and the nitrogen-containing gas is used, the composition of the hard mask changes such that the ratio of nitrogen to carbon in the hard mask increases.

[0050] After the introduction of the precursor gas into the process chamber, a fourth operation 408 is performed, which is to perform a deposition process. During the deposition process, a nitrogen-doped hard mask is deposited on a substrate, such as substrate 202 of FIGS. 2 and 3. The nitrogen-doped hard mask may be hard mask layer 206 of FIGS. 2A-2C. The deposition rate during fourth operation 408 may be from about 2500 Å / min to about 8000 Å / min, such as from about 3000 Å / min to about 7500 Å / min, such as from about 3000 Å / min to about 5000 Å / min, such as from about 3200 Å / min to about 3500 Å / min. In some embodiments, the deposition rate of the nitrogen-doped hard mask can be between about 3500 Angstroms / min and about 6000 Angstroms / min, such as between about 3750 Angstroms / min and about 5000 Angstroms / min. The deposition rate is affected by the applied RF power for forming the plasma in operation 404. As the applied RF power increases, the deposition rate increases.

[0051] The nitrogen-doped hard mask may be deposited until the hard mask reaches a predetermined thickness, such as about 0.5 μm to about 6 μm, such as about 1 μm to about 5 μm, such as about 1.5 μm to about 4 μm, or about 1.7 μm to about 3.5 μm. In some embodiments, the thickness of the nitrogen-doped hard mask may be about 5 μm or greater. The bow of the nitrogen-doped carbon hard mask may be about 30 μm to about 40 μm, such as about 32 μm to about 38 μm, such as about 33 μm to about 37 μm. The internal stress within the nitrogen-doped carbon hard mask may be about 30 MPa to about 37 MPa, such as about 32 MPa to about 36 MPa, such as about 32.5 MPa to about 35 MPa. The nitrogen composition within the nitrogen-doped hard mask may be less than about 16% atomic concentration of the nitrogen-doped hard mask, such as less than about 15% or less than about 10% atomic concentration of the nitrogen-doped hard mask. In some embodiments, the atomic percent of nitrogen in the nitrogen-doped hard mask is about 2% to about 16%, such as about 3% to about 16%, such as about 4% to about 16%, such as about 5% to about 16%, such as about 6% to about 16%, such as about 7% to about 16%, such as about 8% to about 16%, such as about 1% to about 15%, such as about 1% to about 10%, such as about 2% to about 10%, such as about 3% to about 10%, such as about 4% to about 10%, such as about 5% to about 10%, or about 1% to about 16%. In some embodiments, the atomic percent of nitrogen in the nitrogen-doped hard mask is about 5% to about 9%, such as about 5% to about 8%. Increased RF power increased nitrogen incorporation in the nitrogen-doped carbon hard mask.

[0052] After the nitrogen-doped carbon hard mask reaches a desired thickness, plasma formation is stopped in operation 410. Plasma formation may be stopped by stopping the application of RF power to the gas distributor 112 and stopping the flow of precursor gases into the process chamber. After plasma formation and the flow of precursor gases into the process chamber are stopped, the flows of argon-containing gas and nitrogen-containing gas may be stopped. The process chamber is then evacuated prior to removal of the substrate from the process chamber through an opening, such as opening 126 of processing chamber 100 in FIG. 1 .

[0053] It should be noted that the gas flow rates provided herein apply to 300 mm around the substrate, and that the gas flow rates may be scaled for substrates of other shapes and sizes.

[0054] 5 is a graph 500 illustrating mask thickness at the edge of the substrate for nitrogen-doped and undoped carbon hard masks. The edge of the mask is defined as the outer 20 mm radius of the mask. Mask thickness is shown on the graph with mask thickness as the y-axis and independent variable, and distance from the substrate center in millimeters as the x-axis and dependent variable.

[0055] Mask thickness is graphed for two different compositions of carbon hard mask. In one embodiment, the thickness profile of a nitrogen-doped carbon hard mask is graphed. The nitrogen-doped carbon hard mask is formed using the method 400 described herein. The nitrogen-doped carbon hard mask has an edge drop defined by D4 in FIG. 5. The nitrogen-doped carbon hard mask can have an edge drop D4 of about 55 nm to about 25 nm, such as about 51 nm to about 30 nm.

[0056] In another embodiment, a thickness profile of an undoped (e.g., unnitrogen-doped) carbon hard mask is graphically illustrated. The unnitrogen-doped carbon hard mask is formed using a conventional hard mask formation process. The unnitrogen-doped carbon hard mask has an edge drop defined by D5 in FIG. 5. The unnitrogen-doped carbon hard mask can have an edge drop D5 of about 65 nm to about 75 nm, such as about 67.5 nm to about 72.5 nm.

[0057] In an embodiment where the deposition rate of the carbon hard mask is the same as that illustrated in Graph 5, the edge drop D4 of the nitrogen-doped carbon hard mask can be less than 50% of the edge drop D5 of the non-nitrogen-doped carbon hard mask. By nitrogen-doping the carbon hard mask during hard mask deposition, the edge drop is substantially reduced. The reduced edge drop results in more precise patterning and allows for the achievement of smaller scale integrated circuits.

[0058] FIG. 6 is a chart 600 illustrating pillar location thickness loss for an n-type doped carbon hard mask of the present disclosure as well as for a conventional hard mask. Chart 600 illustrates the average relative thickness loss at locations across a substrate where pillars, such as pillars 308 in FIG. 3, contact the underside of a substrate, such as substrate 202 in FIG. 3, and facilitate support for the substrate 202. Hard mask thickness in the portions of the substrate contacting the pillars is lost due to thermal gradients within the substrate caused by heat conduction from the pillars. Thickness loss in the portions of the hard mask above the pillars results in a slight dishing effect on the surface of the hard mask. Reducing the dishing effect caused by the pillars is generally beneficial, resulting in a planar hard mask and more uniform patterning. More uniform patterning allows higher aspect ratios to be achieved.

[0059] Experimental results showed that the non-nitrogen-doped carbon hard mask had a first average pillar location relative thickness loss 602, and the nitrogen-doped carbon hard mask had a second average pillar location relative thickness loss 604. The thickness loss in chart 600 is a percentage of thickness loss. As shown in graph 600, the percent thickness lost when utilizing the nitrogen-doped carbon hard mask and method 400 described herein is less than half the percent thickness lost when utilizing a conventional non-nitrogen-doped carbon hard mask and related method of hard mask formation. The reduction in percent thickness lost is seen while utilizing methods with similar deposition rates, such as those described herein.

[0060] In some embodiments that may be combined with other embodiments, the first average strut location relative thickness loss is between about 0.45% and about 0.6%, such as between about 0.5% and about 0.55%. In some embodiments that may be combined with other embodiments, the second average strut location relative thickness loss is between about 0.075% and about 0.25%, such as about 0.14%, such as between about 0.1% and about 0.2%.

[0061] In some embodiments, which may be combined with other embodiments, the thickness profile uniformity of the hard mask layer is less than about 3%, such as between about 2.8% and about 2.5%, such as between about 2.9% and about 2.4%. In some embodiments, the thickness profile uniformity of a nitrogen-doped carbon hard mask formed using the methods described herein is about 2.7%. The thickness profile uniformity of the hard mask layer is calculated by subtracting the minimum profile thickness of the hard mask layer from the maximum profile thickness of the hard mask layer to provide a thickness range. The thickness range is then divided by two to produce a half thickness range. The half thickness range is then divided by the average thickness across the hard mask layer and expressed as a percentage. The hard mask layer thickness within 3.2 mm of the wafer edge is ignored when calculating the thickness profile uniformity. Previous methods for forming non-nitrogen-doped carbon hard masks result in thickness profile uniformities greater than about 3%, such as greater than 3.35%.

[0062] While the forgoing is directed to embodiments of the present disclosure, other and further embodiments of the present disclosure may be devised without departing from the basic scope thereof, the scope of which is determined by the following claims.

Claims

1. 1. A method of processing a substrate, comprising: flowing a gas containing argon into a process chamber; flowing a nitrogen-containing gas into the process chamber, wherein a ratio of the nitrogen-containing gas to the argon-containing gas is from about 1:3 to about 1:10; igniting a plasma in the process chamber; flowing a precursor gas into the process chamber after igniting the plasma, wherein a ratio of a flow rate of the precursor gas to a flow rate of the combined argon-containing gas and the nitrogen-containing gas is from about 1:3 to about 1:15; conducting a deposition process at a temperature of about 560°C to about 700°C; forming a nitrogen-doped carbon hard mask; Including, the nitrogen-doped carbon hard mask has an atomic nitrogen composition of about 1% nitrogen to about 16% nitrogen, an edge drop of about 55 nm to about 25 nm, and a relative thickness loss of between about 0.075% and about 0.25%; The method, wherein the bow of the nitrogen-doped carbon hard mask is from about 30 μm to about 40 μm.

2. The method of claim 1 , wherein the argon-containing gas is atomic argon.

3. The method of claim 1 , wherein the nitrogen-containing gas is diatomic nitrogen.

4. The method of claim 1 , wherein the argon-containing gas and the nitrogen-containing gas are introduced simultaneously.

5. The method of claim 1, wherein the nitrogen-containing gas has a flow rate between about 250 sccm and about 1000 sccm.

6. The method of claim 1, wherein the argon-containing gas has a flow rate between about 2000 sccm and about 4000 sccm.

7. 10. The method of claim 1, wherein the pressure during flowing the argon-containing gas and flowing the nitrogen-containing gas is between about 6 Torr and about 12 Torr.

8. The method of claim 1 , wherein the deposition process is carried out at a temperature of about 600° C. to about 650° C.

9. The method described in claim 8, wherein the high frequency power applied during ignition of the plasma is between about 3250 watts and about 5000 watts.

10. 1. A method of processing a substrate, comprising: flowing a gas containing argon into a process chamber; flowing a nitrogen-containing gas into the process chamber, wherein a ratio of the nitrogen-containing gas to the argon-containing gas is from about 1:3 to about 1:10; applying radio frequency power to the argon-containing gas and the nitrogen-containing gas to ignite a plasma, wherein the radio frequency power is between about 3250 watts and about 5000 watts; flowing a precursor gas into the process chamber after igniting the plasma, wherein a ratio of a flow rate of the precursor gas to a flow rate of the combined argon-containing gas and the nitrogen-containing gas is from about 1:3 to about 1:15; conducting a deposition process at a temperature of about 560°C to about 700°C; forming a nitrogen-doped carbon hard mask; Including, the nitrogen-doped carbon hard mask has a thickness of about 0.5 μm to about 6 μm, a thickness profile uniformity of less than about 3%, and an atomic nitrogen composition of about 1% nitrogen to about 16% nitrogen, and a thickness variation of the nitrogen-doped carbon hard mask within an outer 20 mm radius of the nitrogen-doped carbon hard mask is about 55 nm to about 25 nm.

11. The method of claim 10 wherein the precursor gas is a hydrocarbon.

12. The precursor gas is acetylene (C ２ H ２ ), methane (CH ４ ), ethane (C ２ H ６ ), propane (C ３ H ８ ), propene (C ３ H ６ ), cyclopropane (C ３ H ６ ), butane (C ４ H １０ ), pentane (C ５ H １２ ), hexane (C ６ H １４ ), heptane (C ７ H １６ ), octane (C ８ H １８ ), Nonan (C ９ H ２０ ), Decane (C １０ H ２２ ), Undecane (C １１ H ２４ ), or dodecane (C １２ H ２６ 12. The method of claim 11, wherein the method is any one of

13. The hydrocarbon is propene (C ３ H ６ 13. The method of claim 12, wherein

14. The method of claim 13, wherein the precursor gas is introduced at a flow rate between about 300 sccm and about 900 sccm.

15. The method of claim 10, wherein the deposition process is carried out at a deposition rate of about 2500 Angstroms / minute to about 8000 Angstroms / minute.

16. The method of claim 10, wherein the argon-containing gas is atomic argon.

17. The method of claim 10 wherein the nitrogen-containing gas is diatomic nitrogen.

18. A method for processing a substrate, comprising: flowing elemental argon gas into a process chamber; flowing diatomic nitrogen gas into the process chamber, wherein a ratio of the diatomic nitrogen gas to the elemental argon gas is from about 1:3 to about 1:6; applying radio frequency power to the mixture of elemental argon gas and diatomic nitrogen gas to ignite a plasma in the process chamber; flowing a precursor gas into the process chamber after igniting the plasma, wherein a ratio of a flow rate of the precursor gas to a flow rate of the combined elemental argon gas and the diatomic nitrogen gas is from about 1:6 to about 1:9; conducting a deposition process at a temperature of about 600°C to about 650°C; forming a nitrogen-doped carbon hard mask; Including, the nitrogen-doped carbon hard mask has an atomic nitrogen composition of about 3% nitrogen to about 10% nitrogen, and a thickness variation of the nitrogen-doped carbon hard mask within an outer 20 mm radius of the nitrogen-doped carbon hard mask is about 55 nm to about 25 nm.

19. A substrate; 1. A semiconductor device comprising: a nitrogen-doped carbon hard mask disposed on the substrate; wherein the nitrogen-doped carbon hard mask has a thickness of about 0.5 μm to about 6 μm, an atomic nitrogen composition of about 1% nitrogen to about 16% nitrogen, an internal stress of about 30 MPa to about 37 MPa, an edge drop of about 55 nm to about 25 nm, a thickness profile uniformity of less than about 3%, and a relative thickness loss of between about 0.075% and about 0.25%, and a bow of the nitrogen-doped carbon hard mask is about 30 μm to about 40 μm.

20. 20. The semiconductor device of claim 19, wherein the atomic nitrogen composition is between about 5% and about 16%.

Images