Selective ETCH of sacrificial light-absorbing material

Abstract

Gas compositions and methods of using the gas composition for selectively etching sacrificial light-absorbing material (SLAM) relative to photoresist material are provided. Methods involve using an etching gas comprising methane gas in combination with fluorocarbon gas and an additive gas to selectively etch SLAM relative to the photoresist material, wherein the etching gas is ignited in a plasma to form plasma species.

Description

Attorney Docket No. LAMRP119WO / 11774- 1WOSELECTIVE ETCH OF SACRIFICIAL LIGHT-ABSORBING MATERIAL CROSS-REFERENCES

[0001] A PCT Request Form is filed concurrently with this specification as part of the present application. Each application that the present application claims benefit of or priority to as identified in the concurrently filed PCT Request Form is incorporated by reference herein in their entireties and for all purposes.BACKGROUND

[0002] Semiconductor processes often involve selective removal of material underlying a developed photoresist after the photoresist is developed. There are challenges to removing such material selectively without substantially damaging the photoresist material.

[0003] The background description provided herein is for the purposes of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.SUMMARY

[0004] One aspect involves a method for processing substrates, the method including: providing a substrate including a developed photoresist having a pattern over a silicon-doped carbon material to a process chamber; exposing the silicon-doped carbon material to an etching gas to selectively etch the silicon-doped carbon material relative to the developed photoresist, whereby the etching gas includes a fluorocarbon gas and methane.

[0005] In various embodiments, etch selectivity of the silicon-doped carbon material relative to the developed photoresist is at least about 6:1.

[0006] In various embodiments, the fluorocarbon gas includes octafluorocyclobutane (C4F8).

[0007] In various embodiments, the etching gas further includes nitrogen.

[0008] In various embodiments, the etching gas further includes an oxygen-containing gas. For example, the oxygen-containing gas may include oxygen (O2).

[0009] In various embodiments, the etching gas further includes an inert gas. In some embodiments, the inert gas is selected from the group consisting of argon, helium, neon, and xenon.

[0010] In various embodiments, the etching gas is argon-free. In various embodiments, the etching gas is ignited in a plasma to form plasma species used to selectively etch the silicon-doped carbon material. In some embodiments, the plasma is a dual frequency plasma. In someAttorney Docket No. LAMRP119WO / 11774- 1WOembodiments, the plasma is a single frequency plasma. In some embodiments, the plasma is a microwave plasma.

[0011] In various embodiments, the etching is performed in a process chamber set to a pressure of about 10 Torr to about 100 mTorr.

[0012] In various embodiments, the photoresist includes carbon.

[0013] In various embodiments, the substrate is used for forming a power layer for backside power delivery in a semiconductor substrate.

[0014] In various embodiments, the pattern includes negative features between patterned photoresist positive features, whereby the bottom of the negative features includes a surface having the silicon-doped carbon material.

[0015] In various embodiments, the negative feature has an aspect ratio of at least about 5:1 or greater.

[0016] In various embodiments, the silicon-doped carbon material has a thickness of at least about 0.44 pm.

[0017] In various embodiments, the silicon-doped carbon material is over a dielectric layer having a thickness at least about four times the thickness of the silicon-doped carbon material.

[0018] In various embodiments, the silicon-doped carbon material is a sacrificial light-absorbing material (SLAM).

[0019] In various embodiments, the silicon-doped carbon material is an anti-reflection coating.

[0020] Another aspect involves a gas composition including: methane; octafluorocyclobutane; and an additive gas selected from the group consisting of nitrogen, oxygen, argon, and combinations thereof, whereby the atomic ratio of methane to octafluorocyclobutane to the additive gas is about 1:1:1.

[0021] In various embodiments, the additive gas includes only nitrogen.

[0022] In various embodiments, the additive gas includes only nitrogen and oxygen.

[0023] These and other aspects are described further below with reference to the drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a process flow diagram depicting operations that may be performed in accordance with certain disclosed embodiments.

[0025] Figures 2A-2C illustrate an embodiment of an adjustable gap capacitively coupled confined RF plasma reactor according to various embodiments herein.

[0026] Figure 3 shows a semiconductor process cluster architecture with various modules that interface with a vacuum transfer module.Attorney Docket No. LAMRP119WO / 11774- 1WODETAILED DESCRIPTION

[0027] In the following description, numerous specific details are set forth to provide a thorough understanding of the presented embodiments. The disclosed embodiments may be practiced without some or all of these specific details. In other instances, well-known process operations have not been described in detail to not unnecessarily obscure the disclosed embodiments. While the disclosed embodiments will be described in conjunction with the specific embodiments, it will be understood that it is not intended to limit the disclosed embodiments.

[0028] In the present disclosure, the terms “semiconductor wafer,” “wafer,” “substrate,” “wafer substrate,” and “partially fabricated integrated circuit” are used interchangeably. One of ordinary skill in the art would understand that the term “partially fabricated integrated circuit” can refer to a silicon wafer during any of many stages of integrated circuit fabrication. A wafer or substrate used in the semiconductor device industry typically has a diameter of 200 mm, or 300 mm, or 450 mm. The following detailed description assumes the present disclosure is implemented on a wafer. However, the present disclosure is not so limited. The work piece may be of various shapes, sizes, and materials. In addition to semiconductor wafers, other work pieces that may take advantage of the present disclosure include various articles such as printed circuit boards and the like.

[0029] Semiconductor device fabrication processes may involve pattern transfer processes where a layer of patterned material is used as a mask to etch a layer under the layer of the patterned material. For example, a photoresist is often used as a mask over a substrate of several layers of material to etch at least one of the layers of the material under a photoresist. Because photoresist material involve exposure to light to etch the photoresist material and form a patterned photoresist, a light-absorbing material is often formed under the photoresist to prevent the light development from affecting layers under the photoresist. The light-absorbing material is often sacrificial and may be referred to as a “sacrificial light-absorbing material” or “SLAM.” In some embodiments, the light-absorbing material is an anti-reflection coating, or a silicon-containing anti-reflection coating, or “SiARC.” While embodiments herein may refer to SLAM, it will be understood that other light-absorbing material may be used, such as an SiARC or another material. The composition is not limited to carbon-doped silicon or carbon-containing silicon material or silicon-and-carbon-containing material.

[0030] The SLAM may have composition that is similar to the photoresist. For example, both materials may include carbon, hydrogen, sulfur, nitrogen and oxygen. After the photoresist is developed, it may be desirable to remove the SLAM between the patterned photoresist material in large regions, but because the materials are similar, it is difficult to etch the SLAM whileAttorney Docket No. LAMRP119WO / 11774- 1WOpreserving the integrity of the patterned photoresist without degrading or eroding regions of the photoresist. Further, because the material underlying the SLAM may be particularly thick, and the patterned photoresist is used as a mask to etch that material, it may be important to preserve the integrity and even the thickness of the patterned photoresist so it can withstand the etching operation that is used to pattern the material underlying the SLAM.

[0031] Existing methods for etching the SLAM involve using primarily a fluorine-containing etch chemistry (such as using only carbon tetrafluoride (CF4) gas, or carbon trifluoride (CHF3) gas, or octafluorocyclobutane (C4F8) gas, or combinations thereof, with optionally added oxygen (O2) gas and / or argon (Ar) gas) which can cause etching on the patterned photoresist. It is difficult to achieve selective etching of the SLAM relative to the patterned photoresist.

[0032] Provided herein are methods and apparatuses for etching SLAM selective to photoresist material with high etch selectivity. Methods involve using a particular etching gas composition that includes a mixture of gases capable of selectively etching SLAM without substantially etching the photoresist material, even for very wide or large features. Methods involve incorporating methane (CH4) and optionally nitrogen (N2) with a fluorocarbon gas such as C4F8, and optionally O2 and / or an inert gas such as Ar. The incorporation of methane results in high selectivity relative to photoresist.

[0033] Figure 1 shows a process flow diagram for performing a method 100 in accordance with certain disclosed embodiments. Operation 101 involves providing a substrate having a patterned photoresist and a SLAM thereon. The substrate can be any wafer, semiconductor wafer, partially fabricated integrated circuit, printed circuit board, display screen, or other appropriate work piece. The substrate may be a silicon wafer, e.g., a 200-mm wafer, a 300-mm wafer, or a 450-mm wafer, including wafers having one or more layers of material, such as dielectric, conducting, or semiconducting material deposited thereon. In various embodiments, the substrate is patterned.

[0034] In some embodiments, the substrate may have a large open ratio, which may be defined as a substrate having an etched area of greater than about 5% or greater than about 10% or greater than about 50% or greater than about 80% compared to the entire wafer surface. For example, the etched area may refer to the regions of the photoresist which were developed which now have exposed SLAM.

[0035] Optionally the SLAM may be formed over a dielectric material, such as an interdielectric material (ILD). The patterned photoresist may be previously developed using photolithography. The material of the patterned photoresist may be carbon material, such as amorphous carbon, diamond-like carbon, or the like. The pattern of the photoresist may involveAttorney Docket No. LAMRP119WO / 11774- 1WOleaving positive features of photoresist material having an aspect ratio of about from 1 : 100 to 100: 1 on the substrate, where the negative feature between the positive features has a width of about 100 nm to about 10 pm. The negative features may have an aspect ratio of about 10:1 to about 1:10. The negative features may be characterized by having photoresist material sidewalls and bottom surfaces having SLAM.

[0036] The SLAM may include silicon-doped carbon, where the carbon content is about 20% to about 90%, or the atomic ratio of carbon to silicon in the SLAM is about 1:1 to about 20:1. . In some embodiments, the SLAM is an organic silicon-containing carbon-rich material or an organic silicon-and-carbon-containing material. The SLAM may include small amounts of hydrogen in some embodiments. The SLAM may include oxygen atoms. The SLAM may be previously deposited using a plasma-enhanced chemical vapor deposition (PECVD) process.

[0037] The SLAM may have a thickness of about 0.1 pm to about 1 pm, or about 0.5 pm. in some embodiments, the SLAM may have a thickness that less than about 4 times the thickness of an underlying material directly under the SLAM.

[0038] The material under and immediately adjacent to the SLAM may be a dielectric material. The dielectric material may be doped and undoped silicon oxide, phosphosilicate glass, and silicon nitride in various embodiments. In various embodiments, the dielectric material may have a thickness of at least about 0.1 pm.

[0039] In an operation 103, the substrate is exposed to a gas mixture having a fluorocarbon gas. The gas mixture may also include a fluorine-free carbon-containing gas. The gas mixture may include both a fluorine-free carbon-containing gas and a fluorine-containing carbon-containing gas

[0040] In some embodiments, the gas mixture includes a carbon-containing gas. The gas mixture may include CH4 gas. The gas mixture may include CH4 and C4F8. The gas mixture may include CH4, C4F8, and one or more additive gases, which may be non-carbon-containing gases. The non-carbon-containing gases may include one or more of the following gases: nitrogen (N2); oxygen-containing gases such as O2 gas, peroxides (such as hydrogen peroxide (H2O2)), gas, or ozone (O3); and an inert gas such as helium (He) or Ar. In one example, the gas mixture includes only CH4, C4F8, and N2 gas. In another example, the gas mixture includes only methane and octafluorocyclobutane. In another example, the gas mixture includes only CH4, C4F8, N2 gas, and O2 gas. In some embodiments, the gas mixture is Ar-free.

[0041] The ratio of flow rates of gases flowed in the gas mixture affects the efficacy of the etching and the selectivity achievable. For example, in some embodiments, a ratio of flow rates of about 1:1:1 of CH4 to C4F8 to N2 may achieve a selectivity of at least about 6:1 of SLAM toAttorney Docket No. LAMRP119WO / 11774- 1WOphotoresist. In some embodiments, there is at least about 5% flow of the gas mixture that includes CH4.

[0042] In various embodiments, the gas mixture may be ignited in a plasma. The plasma may generate an energetic species that may etch the SLAM selectively relative to the photoresist material.

[0043] Any energetic species can be employed during deposition. As used herein, an “energetic species” can include any species that is reactive with one or more components provided during a deposition process. Such components can include a precursor, a deposited layer, and the like. Non-limiting examples of energetic species include radicals, metastables, ions, neutral species, plasma, photons, radiation, excited molecules, excited atoms, a reactive species, or others described herein. In one non-limiting embodiment, the metastable has an energy of about 0.01-1 eV. In another non-limiting embodiment, the ion has an energy of about 100-1000 eV. In yet another non-limiting embodiment, the energetic species has an energy of about 0.01-1000 eV. Any description herein related to radicals and metastables may, in some non-limiting instances, encompass any energetic species described herein.

[0044] The plasma may be generated by any suitable method. The plasma may be generated remotely or in situ. The plasma may be generated and flowed using an ion filter. In some embodiments, an ion filter may not be used. In some embodiments, the plasma is generated by activating one or more gases, such as methane, upstream of the precursor. In some embodiments, the plasma is generated by activating an etching gas mixture. In some embodiments, the plasma is generated in an excitation chamber and the deposition chamber is downstream of the excitation chamber. In some embodiments, the plasma is generated directly. In some embodiments, the plasma is generated indirectly. In some embodiments, one example indirect plasma embodiment may involve using activated inert gas to activate an etching gas mixture which may be performed without an ion filter. In some embodiments, one example indirect plasma embodiment may involve using an activated hydrogen gas to activate an etching gas mixture without using an ion filter.

[0045] The plasma may be generated using inductively coupled plasma (ICP) or capacitively coupled plasma (CCP). The plasma may be generated by microwave plasma.

[0046] The plasma may be generated at various frequencies. The plasma may be generated using single frequency, or dual frequency plasma. Example plasma generation frequencies include but are not limited to about 60 KHz to about 300 MHz or about 60 KHz to about 60 MHz. In some implementations, a LFRF (low frequency radio frequency) generator can provide a low-frequencyAttorney Docket No. LAMRP119WO / 11774- 1WORF signal between about 2 Hz and about 1000 kHz, such as 400 kHz. In some implementations, a HFRF (high frequency radio frequency) generator can provide a high-frequency RF signal between about 1 MHz and about 100 MHz, such as 13.56 MHz.

[0047] For certain disclosed embodiments, the plasma may be generated using a power of about 0W to about 5000W. The plasma power may be up to about 100 kW, or up to lOkW, or about 20W, or about 50W, or about 20W to about 50W.

[0048] The temperature in the environment adjacent to the substrate can be any suitable temperature facilitating the reaction. In some embodiments, the temperature in the environment adjacent to the substrate can be largely controlled by the temperature of a pedestal on which a substrate is supported. In some embodiments, the operating temperature can be between about 25°C and about 600°C. For example, the operating temperature can be between about 250°C and about 400°C or about 250°C to about 550°C, or about 450°C to about 550°C in many integrated circuit applications.

[0049] The pressure in the environment adjacent to the substrate can be any suitable pressure to drive the etching in a reaction chamber. In some embodiments, the pressure can be about 35 Torr or lower. For example, the pressure can be between about 0 mTorr to 100 mTorr. The flow of the additive gas may be about 5 to about 20 times that of the pressure, or at least about 10 times that of the pressure.

[0050] Certain disclosed embodiments also have the technical advantages of resulting in better grain structure of the dielectric underlying the SLAM after removing the SLAM. For example, it may not be desirable to having a surface of the dielectric to have uneven features. Using certain disclosed embodiments enables the surface of the dielectric to be flat and clean after etching the SLAM, which allows patterning of the dielectric to be done with higher accuracy in subsequent operations.

[0051] The etch selectivity of SLAM to photoresist can exceed at least 2:1, such as at least about 3:1, or at least about 4:1, or at least about 5:1, or at least about 6:1.

[0052] Certain disclosed embodiments may be particularly suitable for selectively removing SLAM used in patterning schemes for forming a power layer for backside power delivery in a semiconductor substrate structure.APPARATUS

[0053] Figures 2A-2C illustrate an embodiment of an adjustable gap capacitively coupled confined RF plasma reactor 200 that may be used for performing the etching operations described herein. As depicted, a vacuum chamber 202 includes a chamber housing 204, surrounding anAttorney Docket No. LAMRP119WO / 11774- 1WOinterior space housing a lower electrode 206. In an upper portion of the chamber 202 an upper electrode 208 is vertically spaced apart from the lower electrode 206. Planar surfaces of the upper and lower electrodes 208, 206 are substantially parallel and orthogonal to the vertical direction between the electrodes. Preferably the upper and lower electrodes 208, 206 are circular and coaxial with respect to a vertical axis. A lower surface of the upper electrode 208 faces an upper surface of the lower electrode 206. The spaced apart facing electrode surfaces define an adjustable gap 210 therebetween. During operation, the lower electrode 206 is supplied RF power by an RF power supply (match) 220. RF power is supplied to the lower electrode 206 though an RF supply conduit 222, an RF strap 224 and an RF power member 226. A grounding shield 236 may surround the RF power member 226 to provide a more uniform RF field to the lower electrode 206. As described in commonly-owned U.S. Patent No. 7,732,728, the entire contents of which are herein incorporated by reference, a wafer is inserted through wafer port 282 and supported in the gap 210 on the lower electrode 206 for processing, a process gas is supplied to the gap 210 (e.g., via one or more inlet) and excited into plasma state by the RF power. The upper electrode 208 can be powered or grounded.

[0054] In the embodiment shown in Figures 2A-2C, the lower electrode 206 is supported on a lower electrode support plate 216. An insulator ring 214 interposed between the lower electrode 206 and the lower electrode Support plate 216 insulates the lower electrode 206 from the support plate 216.

[0055] An RF bias housing 230 supports the lower electrode 206 on an RF bias housing bowl 232. The bowl 232 is connected through an opening in a chamber wall plate 218 to a conduit support plate 238 by an arm 234 of the RF bias housing 230. In a preferred embodiment, the RF bias housing bowl 232 and RF bias housing arm 234 are integrally formed as one component, however, the arm 234 and bowl 232 can also be two separate components bolted or joined together.

[0056] The RF bias housing arm 234 includes one or more hollow passages for passing RF power and facilities, such as gas coolant, liquid coolant, RF energy, cables for lift pin control, electrical monitoring and actuating signals from outside the vacuum chamber 202 to inside the vacuum chamber 202 at a space on the backside of the lower electrode 206. The RF supply conduit 222 is insulated from the RF bias housing arm 234, the RF bias housing arm 234 providing a return path for RF power to the RF power supply 220. A facilities conduit 240 provides a passageway for facility components. Further details of the facility components are described in U.S. Patent Nos. 5,948,704 and 7,732,728 and are not shown here for simplicity of description. The gap 210 is preferably surrounded by a confinement ring assembly or shroud (not shown), details of whichAttorney Docket No. LAMRP119WO / 11774- 1WOcan be found in commonly owned published U.S. Patent No. 7,740,736 herein incorporated by reference. The interior of the vacuum chamber 202 is maintained at a low pressure by connection to a vacuum pump through vacuum portal 280 (also referred to as an outlet).

[0057] The conduit support plate 238 is attached to an actuation mechanism 242. Details of an actuation mechanism are described in commonly-owned U.S. Patent No. 7,732,728 incorporated herein by above. The actuation mechanism 242, such as a servo mechanical motor, stepper motor or the like is attached to a vertical linear bearing 244, for example, by a screw gear 246 such as a ball screw and motor for rotating the ball screw. During operation to adjust the size of the gap 210, the actuation mechanism 242 travels along the vertical linear bearing 244. Figure 2A illustrates the arrangement when the actuation mechanism 242 is at a high position on the linear bearing 244 resulting in a small gap 210 a. Figure 2B illustrates the arrangement when the actuation mechanism 242 is at a mid position on the linear bearing 244. As shown, the lower electrode 206, the RF bias housing 230, the conduit support plate 238, the RF power supply 220 have all moved lower with respect to the chamber housing 204 and the upper electrode 208, resulting in a medium size gap 210 b.

[0058] Figure 2C illustrates a large gap 210 c when the actuation mechanism 242 is at a low position on the linear bearing. Preferably, the upper and lower electrodes 208, 206 remain coaxial during the gap adjustment and the facing surfaces of the upper and lower electrodes across the gap remain parallel.

[0059] This embodiment allows the gap 210 between the lower and upper electrodes 206, 208 in the CCP chamber 202 during multi-step process recipes (BARC, HARC, and STRIP etc.) to be adjusted, for example, in order to maintain uniform etch across a large diameter substrate such as 300 mm wafers or flat panel displays. In particular, this chamber pertains to a mechanical arrangement that permits the linear motion necessary to provide the adjustable gap between lower and upper electrodes 206, 208.

[0060] Figure 2 A illustrates laterally deflected bellows 250 sealed at a proximate end to the conduit support plate 238 and at a distal end to a stepped flange 228 of chamber wall plate 218. The inner diameter of the stepped flange defines an opening 212 in the chamber wall plate 218 through which the RF bias housing arm 234 passes. The distal end of the bellows 250 is clamped by a clamp ring 252.

[0061] The laterally deflected bellows 250 provides a vacuum seal while allowing vertical movement of the RF bias housing 230, conduit support plate 238 and actuation mechanism 242. The RF bias housing 230, conduit support plate 238 and actuation mechanism 242 can be referredAttorney Docket No. LAMRP119WO / 11774- 1WOto as a cantilever assembly. Preferably, the RF power supply 220 moves with the cantilever assembly and can be attached to the conduit support plate 238. Figure 2B shows the bellows 250 in a neutral position when the cantilever assembly is at a mid position. Figure 2C shows the bellows 250 laterally deflected when the cantilever assembly is at a low position.

[0062] A labyrinth seal 248 provides a particle barrier between the bellows 250 and the interior of the plasma processing chamber housing 204. A fixed shield 256 is immovably attached to the inside inner wall of the chamber housing 204 at the chamber wall plate 218 so as to provide a labyrinth groove 260 (slot) in which a movable shield plate 258 moves vertically to accommodate vertical movement of the cantilever assembly. The outer portion of the movable shield plate 258 remains in the slot at all vertical positions of the lower electrode 206.

[0063] In the embodiment shown, the labyrinth seal 248 includes a fixed shield 256 attached to an inner surface of the chamber wall plate 218 at a periphery of the opening 212 in the chamber wall plate 218 defining a labyrinth groove 260. The movable shield plate 258 is attached and extends radially from the RF bias housing arm 234 where the arm 234 passes through the opening 212 in the chamber wall plate 218. The movable shield plate 258 extends into the labyrinth groove 260 while spaced apart from the fixed shield 256 by a first gap and spaced apart from the interior surface of the chamber wall plate 218 by a second gap allowing the cantilevered assembly to move vertically. The labyrinth seal 248 blocks migration of particles spalled from the bellows 250 from entering the vacuum chamber interior 205 and blocks radicals from process gas plasma from migrating to the bellows 250 where the radicals can form deposits which are subsequently spalled.

[0064] Figure 2A shows the movable shield plate 258 at a higher position in the labyrinth groove 260 above the RF bias housing arm 234 when the cantilevered assembly is in a high position (small gap 210 a). Figure 2C shows the movable shield plate 258 at a lower position in the labyrinth groove 260 above the RF bias housing arm 234 when the cantilevered assembly is in a low position (large gap 210 c). Figure 2B shows the movable shield plate 258 in a neutral or mid position within the labyrinth groove 260 when the cantilevered assembly is in a mid position (medium gap 210 b). While the labyrinth seal 248 is shown as symmetrical about the RF bias housing arm 234, in other embodiments the labyrinth seal 248 may be asymmetrical about the RF bias arm 234.

[0065] Figure 3 depicts a semiconductor process cluster architecture with various modules that interface with a vacuum transfer module 338 (VTM). The arrangement of transfer modules to “transfer” substrates among multiple storage facilities and processing modules may be referred to as a “cluster tool architecture” system. Airlock 330, also known as a loadlock or transfer module, is shown in VTM 338 with four processing modules 320a-320d, which may be individuallyAttorney Docket No. LAMRP119WO / 11774- 1WOoptimized to perform various fabrication processes. By way of example, processing modules 320a-320d may be implemented to perform substrate etching, deposition, ion implantation, substrate cleaning, sputtering, and / or other semiconductor processes as well as laser metrology and other defect detection and defect identification methods. One or more of the processing modules (any of 320a-320d) may be implemented as disclosed herein, i.e., for etching recessed features into substrates using a multi-stage etch process with a multi-layer hardmask. Airlock 330 and process modules 320a-320d may be referred to as “stations.” Each station has a facet 336 that interfaces the station to VTM 338. Inside the facets, sensors 1-18 are used to detect the passing of substrate 326 when moved between respective stations.

[0066] Robot 322 transfers substrates between stations. In one implementation, the robot may have one arm, and in another implementation, the robot may have two arms, where each arm has an end effector 324 to pick substrates for transport. Front-end robot 332, in atmospheric transfer module (ATM) 340, may be used to transfer substrates from cassette or Front Opening Unified Pod (FOUP) 334 in Eoad Port Module (FPM) 342 to airlock 330. Module center 328 inside process modules 320a-320d may be one location for placing the substrate. Aligner 344 in ATM 340 may be used to align substrates.

[0067] In an exemplary processing method, a substrate is placed in one of the FOUPs 334 in the LPM 342. Front-end robot 332 transfers the substrate from the FOUP 334 to the aligner 344, which allows the substrate 326 to be properly centered before it is etched, or deposited upon, or otherwise processed. After being aligned, the substrate is moved by the front-end robot 332 into an airlock 330. Because airlock modules have the ability to match the environment between an ATM and a VTM, the substrate is able to move between the two pressure environments without being damaged. From the airlock module 330, the substrate is moved by robot 322 through VTM 338 and into one of the process modules 320a-320d, for example process module 320a. In order to achieve this substrate movement, the robot 322 uses end effectors 324 on each of its arms. In process module 320a, the substrate undergoes etching as described. Next, the robot 322 moves the substrate out of processing module 320a to its next desired position.

[0068] It should be noted that the computer controlling the substrate movement can be local to the cluster architecture, or can be located external to the cluster architecture in the manufacturing floor, or in a remote location and connected to the cluster architecture via a network.Attorney Docket No. LAMRP119WO / 11774- 1WOEXPERIMENTALEXPERIMENT 1

[0069] A first substrate having a SLAM and photoresist thickness of 1300 nm is exposed to a fluorine-containing etching gas, such as CF4, CHF3, O2, and Ar. A second substrate having a SLAM and photoresist thickness of 1300 nm is exposed to an etching gas composition having N2, O2, C4F8, and CH4. About 400 nm of SLAM was etched in both substrates.

[0070] The first substrate resulted in the photoresist having a thickness of 295 nm. The second substrate resulted in the photoresist having a thickness of 865 nm. These results suggest reduced consumption of the photoresist when using the second etching gas.CONCLUSION

[0071] Although the foregoing embodiments have been described in some detail for purposes of clarity of understanding, it will be apparent that certain changes and modifications may be practiced within the scope of the appended claims. It should be noted that there are many alternative ways of implementing the processes, systems, and apparatus of the present embodiments. Accordingly, the present embodiments are to be considered as illustrative and not restrictive, and the embodiments are not to be limited to the details given herein.

Claims

Attorney Docket No. LAMRP119WO / 11774- 1WOCLAIMSWhat is claimed is:

1. A method for processing substrates, the method comprising:providing a substrate comprising a developed photoresist having a pattern over a silicon- doped carbon material to a process chamber;exposing the silicon-doped carbon material to an etching gas to selectively etch the silicon- doped carbon material relative to the developed photoresist,wherein the etching gas comprises a fluorocarbon gas and methane.

2. The method of claim 1, wherein etch selectivity of the silicon-doped carbon material relative to the developed photoresist is at least about 6:1.

3. The method of any of claims 1-2, wherein the fluorocarbon gas comprises octafluorocyclobutane (C4F8).

4. The method of any of claims 1-3, wherein the etching gas further comprises nitrogen.

5. The method of any of claims 1-4, wherein the etching gas further comprises an oxygen- containing gas.

6. The method of claim 5, wherein the oxygen-containing gas comprises oxygen (O2).

7. The method of any of claims 1-6, wherein the etching gas further comprises an inert gas.

8. The method of claim 7, wherein the inert gas is selected from the group consisting of argon, helium, neon, and xenon.

9. The method of any of the preceding claims, wherein the etching gas is argon-free.

10. The method of any of the preceding claims, wherein the etching gas is ignited in a plasma to form plasma species used to selectively etch the silicon-doped carbon material.

11. The method of claim 10, wherein the plasma is a dual frequency plasma.

12. The method of claim 10, wherein the plasma is a single frequency plasma.

13. The method of claim 10, wherein the plasma is a microwave plasma.Attorney Docket No. LAMRP119WO / 11774- 1WO14. The method of any of the preceding claims, wherein the etching is performed in a process chamber set to a pressure of about 10 Torr to about 100 mTorr.

15. The method of claim 1, wherein the photoresist comprises carbon.

16. The method of claim 1, wherein the substrate is used for forming a power layer for backside power delivery in a semiconductor substrate.

17. The method of claim 1, wherein the pattern comprises negative features between patterned photoresist positive features, wherein the bottom of the negative features comprises a surface having the silicon-doped carbon material.

18. The method of claim 1, wherein the negative feature has an aspect ratio of at least about 5:1 or greater.

19. The method of claim 1, wherein the silicon-doped carbon material has a thickness of at least about 0.44 pm.

20. The method of claim 1, wherein the silicon-doped carbon material is over a dielectric layer having a thickness at least about four times the thickness of the silicon-doped carbon material.

21. The method of claim 1, wherein the silicon-doped carbon material is a sacrificial lightabsorbing material (SLAM).

22. The method of claim 1, wherein the silicon-doped carbon material is an anti-reflection coating.

23. A gas composition comprising:methane;octafluorocyclobutane; andan additive gas selected from the group consisting of nitrogen, oxygen, argon, and combinations thereof,wherein the atomic ratio of methane to octafluorocyclobutane to the additive gas is about 1:1:1.Attorney Docket No. LAMRP119WO / 11774- 1WO24. The gas composition of claim 23, wherein the additive gas comprises only nitrogen.

25. The gas composition of claim 23, wherein the additive gas comprises only nitrogen and oxygen.

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