Patent Publication Number: US-2011076623-A1

Title: Method for reworking silicon-containing arc layers on a substrate

Description:
FIELD OF THE INVENTION 
     The invention is related to substrate processing, in particular, to methods for reworking film structures containing a silicon-containing anti-reflective coating (SiARC) layer on a substrate. 
     BACKGROUND OF THE INVENTION 
     Lithographic processes using radiation sensitive material (also referred to herein as “resist”) are widely used in the manufacture of semiconductor devices and other patterned structures. In track photolithographic processing used in the fabrication of semiconductor devices, the following types of processes may be performed in sequence: photoresist coating that coats a photoresist solution on a semiconductor wafer to form a photoresist film, heat processing to cure the coated photoresist film, exposure processing to expose a predetermined pattern on the photoresist film, heat processing to promote a chemical reaction within the photoresist film after exposure, developing processing to develop the exposed photoresist film and form a photoresist pattern, etching a fine pattern in an underlying layer or substrate using the photoresist pattern, etc. 
     In a photolithography process, various parameters may affect a profile of the photoresist pattern. The profile of the photoresist pattern may have some defects caused by the various process parameters of a spin coating process, the heat processing, the exposure processing and the developing processing. When a photoresist pattern having defects is employed in an etching process for forming a fine pattern in a semiconductor device, the fine pattern may also have defects in accordance with defects in the photoresist pattern. Thus, when the photoresist pattern has the defects, a rework process may be performed on the defective photoresist pattern. In the rework process, a new photoresist pattern is formed on the semiconductor substrate after removing the defective photoresist pattern from the semiconductor substrate. The rework process can include a dry cleaning process such as an ashing process using oxygen (O 2 ) plasma, or a wet cleaning process using an organic stripper solution. When the photoresist pattern is removed using an oxygen plasma in an ashing process, an exposed surface of the semiconductor substrate may be damaged and electrical characteristics of a semiconductor device provided on the substrate may deteriorate. 
     In the photolithographic processing, an organic or inorganic anti-reflection coating (ARC) layer may be deposited on a layer to be etched before forming the photoresist pattern. The ARC layer may be used to reduce reflection of light from the layer to etched while forming the photoresist pattern on the ARC layer by an exposure process. For example, the ARC layer may prevent a standing wave effect caused by interference between incident light toward a photoresist film and reflected light from the layer to be etched. 
     Advanced organic and inorganic ARC layers have been developed for increased density of features that improve the cost per function ratio of the microelectronic device being manufactured. As the drive toward smaller and smaller features continues, several new problems in the manufacture of these very small features are becoming visible. Silicon-containing ARC (SiARC) layers are promising candidates for hard masks because Si-content of SiARC layers may be tuned to provide high etch selectivity to photoresist. However, removal of many new materials used in advanced ARC layers, for example SiARC layers, during a rework process, is problematic and new processing methods for removing these materials and other layers are needed for microelectronic device production. 
     SUMMARY OF THE INVENTION 
     Exemplary embodiments of the invention provide methods of reworking a silicon-containing ARC (SiARC) layer on a substrate, for example due to a defective overlying photoresist pattern. According to some embodiments, the SiARC layer may overlie an optical mask layer, for example an organic planarization layer (OPL) coating on the substrate. 
     According to one embodiment, a method is provided for reworking a substrate. The method includes providing a substrate containing a SiARC layer thereon, and a resist pattern formed on the SiARC layer, removing the resist pattern from the SiARC layer, exposing the SiARC layer to a process gas containing ozone (O 3 ) gas to form a modified SiARC layer, treating the modified SiARC layer with a dilute hydrofluoric acid (DHF) liquid, and centrifugally removing the modified SiARC layer from the substrate. 
     According to another embodiment, the method includes providing a substrate containing an OPL coating thereon, a SiARC layer on the OPL coating, and a resist pattern formed on the SiARC layer. The method further includes removing the resist pattern from the SiARC layer, modifying the SiARC layer and the OPL coating by exposing the SiARC layer to a mixture of O 3  gas and water (H 2 O) vapor, treating the modified SiARC layer and the modified OPL coating with a DHF liquid, and centrifugally removing modified SiARC layer and the modified OPL coating from the semiconductor substrate. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with a general description of the invention given above, and the detailed description given below, serve to explain the principles of the invention. 
         FIGS. 1A-1F  are schematic cross-sectional views for a method of reworking a film structure containing a SiARC layer according to an embodiment of the invention; 
         FIG. 2  is a schematic diagram of a processing system for modifying SiARC layers according to an embodiment of the invention; 
         FIG. 3  is a schematic diagram of a wet processing system for treating and centrifugally removing layers from a substrate according to an embodiment of the invention; 
         FIG. 4  shows processing results for removal of SiARC layers using different processing recipes; 
         FIGS. 5A-5F  are schematic cross-sectional views for a method of reworking a film structure containing a SiARC layer and an OPL coating according to another embodiment of the invention; 
         FIG. 6  is a simplified process flow diagram for a method of reworking a film structure containing a SiARC layer according to an embodiment of the invention; and 
         FIG. 7  is a simplified process flow diagram for a method of reworking a film structure containing a SiARC layer and an OPL coating according to another embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF SEVERAL EMBODIMENTS 
     Embodiments of the invention provide methods for reworking film structures containing SiARC layers and other layers utilized for semiconductor device manufacturing. The methods include a first processing step for modifying a SiARC layer and a second wet processing step for removing the modified SiARC layer and optionally one or more underlying layers. The SiARC layers may include Si-containing polymers that are cross-linked that have different Si-contents. Exemplary SiARC layers that are currently used for photolithography may have a silicon-content of 17% Si (SiARC 17%) or a silicon-content of 43% Si (SiARC 43%). For example, SiARC layers are commercially available as Sepr-Shb Aseries SiARC layers from Shin Etsu Chemical Co., Ltd. According to embodiments of the invention, the SiARC layer may have a Si-content between about 10% and about 40%, or a Si-content greater than about 40%. 
     One skilled in the relevant art will recognize that the various embodiments may be practiced without one or more of the specific details, or with other replacement and/or additional methods, materials, or components. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of various embodiments of the invention. Similarly, for purposes of explanation, specific numbers, materials, and configurations are set forth in order to provide a thorough understanding of the invention. Furthermore, it is understood that the various embodiments shown in the figures are illustrative representations and are not necessarily drawn to scale. 
     Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention, but do not denote that they are present in every embodiment. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily referring to the same embodiment of the invention. 
       FIGS. 1A-1F  are schematic cross-sectional views for a method of reworking a film structure containing a SiARC layer according to an embodiment of the invention. In  FIG. 1A , film structure  10  contains a substrate  100 , an optical mask layer  102  on the substrate  100 , and a SiARC layer  104  on the optical mask layer  102 . According to one embodiment, the optical mask layer  102  may contain or consist of an organic planarization layer (OPL coating). According to some embodiments of the invention, the optical mask layer  102  may be omitted and the SiARC layer  104  deposited directly on the substrate  100  or on a dielectric layer, a semiconductor layer, or a conductor layer. The SiARC layer  104  may, for example, be applied using spin coating technology, or a vapor deposition process. 
     The film structure  10  further contains a resist pattern  106  that is used as a mask for defining a pattern to be etched into the SiARC layer  104 , the optical mask layer  102 , and the substrate  100 . According to other embodiments of the invention, the film structure  10  may contain additional layers, for example an oxide layer (not shown) between the optical mask layer  102  and the substrate  100 . In one example the substrate  100  may contain a low-dielectric constant (low-k) layer to be etched and patterned. 
     The resist pattern  106  may contain a 248 nm (nanometer) photoresist, a 193 nm photoresist, a 157 nm photoresist, an EUV (extreme ultraviolet) photoresist, or an electron beam sensitive resist. A resist layer may be deposited using a track system. For example, the track system can comprise a Clean Track ACT 8, ACT 12, or Lithius resist coating and developing system commercially available from Tokyo Electron Limited (TEL). Other systems and methods for forming a photo-resist layer on a substrate are well known to those skilled in the art of spin-on resist technology. 
     Following deposition of a photoresist layer and one or more curing processes, a photolithography process may be performed for transferring a pattern from a reticle or mask to the photoresist layer. After the photoresist layer is selectively exposed to electromagnetic (EM) radiation using the reticle or mask, the exposed photoresist layer is developed by a developer solution to form the photoresist pattern  106  depicted in  FIG. 1A . The photoresist pattern  106  covers areas of the underlying SiARC layer  104 . 
     The exposure to EM radiation through a reticle is performed in a dry or wet photo-lithography system. The image pattern can be formed using any suitable conventional stepping lithographic system, or scanning lithographic system. For example, the photo-lithographic system may be commercially available from ASML Netherlands B.V. (De Run 6501, 5504 DR Veldhoven, The Netherlands), or Canon USA, Inc., Semiconductor Equipment Division (3300 North First Street, San Jose, Calif. 95134. In some examples, the EM radiation can include KrF radiation (248 nm wavelength) or higher wavelength radiation. The developing process can include exposing the substrate to a developing solvent in a developing system, such as a track system. For example, the track system can comprise a Clean Track ACT 8, ACT 12, or Lithius resist coating and developing system commercially available from Tokyo Electron Limited (TEL). 
     The optical mask layer  102  may contain an OPL coating that can include a photo-sensitive organic polymer or an etch type organic compound. For instance, the photo-sensitive organic polymer may be polyacrylate resin, epoxy resin, phenol resin, polyamide resin, polyimide resin, unsaturated polyester resin, polyphenylenether resin, polyphenylenesulfide resin, or benzocyclobutene (BCB). These materials may be formed using spin-on techniques. The OPL coating may be an organic material (e.g., (CH x ) n ) that forms a cross-linked structure during a curing process. 
     Following formation of the photoresist pattern  106 , an after-development-inspection system (ADI) may be used to examine the photoresist pattern  106  at a plurality of test areas to determine if it has been correctly manufactured. The ADI can determine a critical dimension (CD) and alignment or the presence of any residue or debris on the film structure  10 . CD commonly refers to a size or width of a feature formed in the photoresist pattern  106 , or a dimension between features etched in the photoresist pattern  106 . Key requirements for the processing of semiconductor wafers are tight CD control, tight profile control, and tight uniformity control—both within-wafer and wafer-to-wafer. For example, variations in CD measurements, profile measurements, and uniformity measurements are often caused by variations in temperature profile across a wafer, variations in thermal response from wafer to wafer, and variations in temperature profiles between substrate heaters. 
     The ADI may, for example, be a scanning electron microscope (SEM) or a light scattering system such as an optical digital profilometry (ODP) system. The ODP system may include a scatterometer, incorporating beam profile ellipsometry and beam profile reflectometry (reflectometer), commercially available from Therma-Wave, Inc. (1250 Reliance Way, Fremont, Calif. 94539) or Nanometrics, Inc. (1550 Buckeye Drive, Milpitas, Calif. 95035). ODP software is available from Timbre Technologies Inc. (2953 Bunker Hill Lane, Santa Clara, Calif. 95054). 
     If a feature dimension of the photoresist pattern  106  is not within tolerance specification or if a residue/defect is detected, the photoresist pattern  106  must be reworked before etching features in the substrate  100 . According to some embodiments of the invention, the rework includes not only removing the photoresist pattern  106  from the film structure  10  but also the SiARC layer  104  and the optical mask layer  102 . 
     The photoresist pattern  106  in  FIG. 1A  may be removed from the SiARC layer  104  using methods well known to those in the art. In a first example, the photoresist pattern  106  may be removed from the SiARC layer  104  using a conventional dry ashing process, or using a sulfuric acid hydrogen peroxide mixture (SPM) in a wet process or a developer solution/photoresist solvent like propylene glycol monomethyl ether acetate (PGMEA) in a Clean Track system. In a second example, the photoresist pattern  106  may be removed from the SiARC layer  104  by exposure to a process gas containing ozone (O 3 ), followed by a wet spin-off process that centrifugally removes remains of the photoresist pattern  106  in the presence of de-ionized water (DIW) or an alkaline solution. In the second example, removal of the photoresist pattern  106  may be carried out without plasma damage and without formation of residues on the SiARC layer  104 . 
     Removal of the photoresist pattern  106  from the SiARC layer  104  may damage the exposed SiARC layer  104   a .  FIG. 1B  schematically shows a film structure  11  containing a surface roughened region  108  on the SiARC layer  104 . The presence of the surface roughened region  108  can require reworking of the SiARC layer  104  and the optical mask layer  102 . The inventors have realized that conventional dry and wet processing methods are unable to satisfactorily remove the SiARC layer  104 , or the SiARC layer  104  and the optical mask layer  102 . For example, dry ashing methods frequently create non-volatile hard residues that remain on the substrate  100 . Accordingly, embodiments of the invention provide methods for removing the SiARC layer  104 , or the SiARC layer  104  and the optical mask layer  102  from the substrate  100 . The inventive methods may be used to replace conventional ashing methods and combine dry and wet processing on a single wafer platform. The dry processing can modify the photoresist by oxidation to form a water soluble species, without forming a hard residue that remains on the substrate  100 . 
     According to one embodiment of the invention, following removal of the photoresist pattern  106 , the method includes a first process for modifying the SiARC layer  104 . The first process may be performed in a first processing system  200  schematically shown in  FIG. 2 . The first processing system  200  contains a process chamber  210  that includes an upper heater  202 , a lower heater  204 , a substrate holder  212  for supporting the substrate  100 , a process gas inlet  206 , a process gas outlet  208 , a pressure gauge  214  for measuring a gas pressure in the process chamber  210 , and an exhaust system  226  for exhausting the gaseous environment in the process chamber  210  and providing a reduced pressure in the processing region  224 . The first processing system  200  further includes an O 3  generator  218 , a H 2 O vaporizer  216 , a N 2  gas supply system  220 , and a gas heater  222 . The gas heater  222  may be configured for heating a process gas to a temperature between about 80° C. and about 150° C., or between about 100° C. and about 120° C. 
     The first processing system  200  further includes a controller  228  that can be coupled to and control the process chamber  210 , the upper heater  202 , the lower heater  204 , the substrate holder  212 , the pressure gauge  214 , the exhaust system  226 , the O 3  generator  218 , the H 2 O vaporizer  216 , the N 2  gas supply system  220 , and the gas heater  222 . Alternatively, or in addition, controller  228  can be coupled to one or more additional controllers/computers (not shown), and controller  228  can obtain setup and/or configuration information from an additional controller/computer. The controller  228  can comprise a number of applications for controlling one or more of the processing elements described above. For example, controller  228  can include a graphic user interface (GUI) component (not shown) that can provide easy to use interfaces that enable a user to monitor and/or control one or more processing elements. 
     The first processing system  200  may be configured to process 200 mm substrates, 300 mm substrates, or larger-sized substrates. In fact, it is contemplated that the deposition system may be configured to process substrates, wafers, or LCDs regardless of their size, as would be appreciated by those skilled in the art. Therefore, while aspects of the invention will be described in connection with the processing of a semiconductor substrate, the invention is not limited solely thereto. Alternately, a batch first processing system capable of processing multiple substrates simultaneously may be utilized for the first process for modifying the SiARC layer  104  as described in the embodiments of the invention. 
     The first process can include disposing the substrate  100  on the substrate holder  212  in the process chamber  210  and heating the process chamber  210  to a desired temperature using the upper heater  202  and the lower heater  204 . For example, the process chamber  210  may be heated to approximately 105° C. by heaters  202  and  204 . Thereafter, a process gas is flowed from the gas heater  222  into the processing region  224  above the substrate  100  for modifying the SiARC layer  104 . 
     According to one embodiment, the process gas includes O 3  gas that is flowed from the O 3  generator  218  into the gas heater  222  where it is heated and thereafter the process gas is flowed into the process chamber  210  and exposed to substrate  100  in the processing region  224 . Exemplary processing conditions include a gas flow rate of 4 liters/minute with an O 3  gas concentration of 9% by volume (200 g/m 3 ), balance O 2 . A temperature of the gas heater  222  can be approximately 150° C. and a gas pressure in the processing region  224  can be approximately 75 kPa. According to another embodiment, N 2  gas may be provided from the N 2  supply system  220  and mixed with the O 3  gas in the gas heater  222 . 
     According to another embodiment, the process gas includes a mixture of O 3  gas and H 2 O vapor. The H 2 O vapor can be generated in the H 2 O vaporizer at a temperature of approximately 128° C., and mixed with O 3  gas in the gas heater  222 . The process gas containing the heated mixture of O 3  gas and H 2 O vapor is flowed into the process chamber  210  and exposed to the substrate  100  in the processing region  224 . According to another embodiment, N 2  gas may be provided from the N 2  supply system  220  and mixed with the mixture of O 3  gas and H 2 O vapor in the gas heater  222 . 
       FIG. 1C  shows a film structure  12  containing a modified SiARC layer  110  and a modified optical mask layer  122  following a first process using O 3  gas in the absence of H 2 O vapor according to one embodiment of the invention. According to another embodiment, the first process may contain a mixture of O 3  gas and H 2 O vapor. According to some embodiments of the invention, the formation of the modified SiARC layer  110  and the modified optical mask layer  122  enables subsequent complete removal of the modified SiARC layer  110  and the modified optical mask layer  122  in a second wet process that includes exposing the modified SiARC layer  110  and the modified optical mask layer  122  to DHF liquid and centrifugally removing the layers. It is speculated that subsequent complete removal of the modified SiARC layer  110  and modified optical mask layer  122  in the second wet process is facilitated by damage in the form of cracks  112  in the modified SiARC layer  110  and the modified optical mask layer  122 . It is further speculated that the SiARC layer  104  is modified by the O 3  gas exposure, or by the O 3  gas and H 2 O vapor exposure, to become more “SiO 2 -like” and therefore more easily removed in the second wet process. However, although not shown in  FIGS. 1A-1D , according to some embodiments of the invention, the exposure of the SiARC layer  104  to the O 3  gas, or to the O 3  gas and H 2 O vapor, may not damage the optical mask layer  102  prior to removal of the modified SiARC layer  110  and the optical mask layer  102  in the DHF removal step. Exemplary concentrations of the DHF liquid include about 1% (volume:volume) HF in H 2 O, less than about 1% HF in H 2 O, or less than about 0.5% HF in H 2 O. 
     According to embodiments of the invention, the second wet process removes the modified SiARC layer  110  and the modified optical mask layer  122  from the substrate  100 . The second wet process may be performed in a second processing system  300  schematically shown in  FIG. 3 . The second processing system  300  can be a semi-closed wet spin module for treating and centrifugally removing films or layers from a substrate by spinning the substrate. The semi-closed configuration allows fume control and minimizes exhaust volume. The second processing system  300  contains a process chamber  310  that includes a substrate holder  312  for supporting, heating, and rotating (spinning) the substrate containing the film structure  12 , a rotating means  318  (e.g., a motor), and a liquid delivery nozzle  314  configured for providing a liquid  316  to an upper surface of the film structure  12 . According to other embodiments, the second processing system  300  may include additional liquid delivery nozzles (not shown) for providing different liquids. The liquid delivery nozzle  314  may provide atomic spray of the liquid  316  for good film and particle removal without surface damage. The liquid  316  can include a cleaning liquid, DIW, or a combination thereof. The cleaning liquid can, for example, include DHF, SC1 (NH 4 OH/H 2 O 2 /H 2 O), or SC2 (HCl/H 2 O 2 /H 2 O). In some examples, the liquid delivery nozzle  314  may first provide a cleaning liquid to the upper surface of the film structure  12 , and thereafter, provide DIW to remove the cleaning liquid. Exemplary rotating speeds can be between about 500 rpm and about 1500 rpm, for example 1000 rpm, during exposure of the upper surface of the film structure  12  to the liquid  316 . 
     The second processing system  300  further includes a controller  320  that can be coupled to and control the process chamber  310 , the liquid delivery nozzle  314 , and the rotating means  318 . Alternatively, or in addition, controller  320  can be coupled to one or more additional controllers/computers (not shown), and controller  320  can obtain setup and/or configuration information from an additional controller/computer. The controller  320  can comprise a number of applications for controlling one or more of the processing elements described above. For example, controller  320  can include a graphic user interface (GUI) component (not shown) that can provide easy to use interfaces that enable a user to monitor and/or control one or more processing elements. 
     The second processing system  300  may be configured to process 200 mm substrates, 300 mm substrates, or larger-sized substrates. In fact, it is contemplated that the deposition system may be configured to process substrates, wafers, or LCDs regardless of their size, as would be appreciated by those skilled in the art. Therefore, while aspects of the invention will be described in connection with the processing of a semiconductor substrate, the invention is not limited solely thereto. Alternately, a batch first processing system capable of processing multiple substrates simultaneously may be utilized for the second wet process for removing the modified SiARC layer  110  and the modified optical mask layer  122  from the substrate  100  as described in the embodiments of the invention.  FIG. 1D  shows a film structure  13  containing the substrate  100  following a second wet process for removing the modified SiARC layer  110  and the modified optical mask layer  122 . 
     According to one embodiment, the film structure  12  may be exposed to the DHF liquid and, subsequently, without further exposure to the DHF liquid, the substrate may be rotated to centrifugally remove the modified SiARC layer  110  and the modified optical mask layer  122  from the film structure  12 . A DIW exposure and spinning may be used to remove the DHF liquid. 
     According another embodiment, the film structure  12  may be simultaneously exposed to the DHF liquid and the substrate rotated to centrifugally remove the modified SiARC layer  110  and the modified optical mask layer  122  from the film structure  12 . A DIW exposure and spinning may be used to remove the DHF liquid. 
     According to another embodiment, the film structure  10  containing the photoresist pattern  106  and the SiARC layer  104  shown in  FIG. 1A  may be removed using a first process that includes an exposure to O 3  gas in the process chamber  210 , followed by a second wet process that includes treating the modified SiARC layer  110  and the modified optical mask layer  122  to DHF liquid, and centrifugally removing the layers  110  and  122 . A DIW exposure and spinning may be used to remove the DHF liquid. 
     According to another embodiment, the film structure  10  contains the photoresist pattern  106  and the SiARC layer  104  shown in  FIG. 1A  may be removed using a first process that includes an exposure to a mixture of O 3  gas and H 2 O vapor in the process chamber  210 , followed by a second wet process includes exposing the modified SiARC layer  110  and the modified optical mask layer  122  to DHF liquid, and centrifugally removing the layers  110  and  122 . A DIW exposure and spinning may be used to remove the DHF liquid. 
     As shown in  FIG. 1E , following the removal of the modified SiARC layer  110  and the modified optical mask layer  122 , a new optical mask layer  114 , a new SiARC layer  116 , and a new photoresist  118  may be deposited on a substrate  100  and a new photoresist patterning process repeated on the film structure  14 .  FIG. 1F  shows a new film structure  15  that includes a new photoresist pattern  120  formed on the new SiARC layer  116 . 
       FIG. 4  shows processing results for removal of SiARC layers using different processing steps. Two different film stacks were studied. The first film stack included a Si substrate, a 50 nm thick SiO 2  layer on the Si substrate, and a circa 80 nm thick SiARC layer with a 17% Si-content (SiARC 17%). The second film stack included a Si substrate, a 50 nm thick SiO 2  layer on the Si substrate, and a circa 35 nm thick SiARC layer with a 43% Si-content (SiARC 43%). The plots in  FIG. 4  shows SiARC film thickness as a function of processing recipes A-J, where the SiARC film thickness was measured following the processing. Process recipes B-G included a first processing step in the first processing system  200  and a second wet processing step in the second processing system  300  with simultaneous cleaning liquid or DIW exposure and substrate rotation. Process recipe A denotes unprocessed SiARC 17% and SiARC 43% reference film structures; process recipe B denotes a first processing step of 1 minutes O 3  gas/H 2 O vapor exposure followed by a second wet processing step of deionized water (DIW) exposure and substrate rotation; process recipe B denotes a first processing step of 1 minute O 3  gas/H 2 O vapor exposure followed by a second wet processing step of SC1 exposure and substrate rotation; and process recipe C denotes a first processing step of 1 minutes O 3  gas exposure (without H 2 O vapor) followed by a second processing step of DIW exposure and rotation. Process recipe D denotes a first processing step of 1 minute O 3  gas exposure (without H 2 O) followed by a second wet processing step of SC1 exposure with substrate rotation; process recipe E denotes a first processing step of 1 minute O 3  gas exposure (without H 2 O) followed by a second wet processing step of DIW exposure and substrate rotation; and process recipe F denotes a first processing step of 1 minute O 3  gas exposure (without H 2 O) followed by a second wet processing step of SC1 exposure and substrate rotation; and process recipe G denotes a first processing step of 3 minute O 3  gas exposure (without H 2 O) and a second wet processing step of SC1 exposure and substrate rotation. Process recipe H denotes a single processing step of 30 second DHF exposure and substrate rotation in the second processing system  300 . Process recipe I denotes a 3 minute O 3  gas exposure (without H 2 O) in the first processing system  200  and a second wet processing step of 30 second DHF liquid exposure and substrate rotation in the second processing system  300 . Process recipe J denotes a 30 second DHF exposure and rotation in the second processing system  300 , followed by a 3 minute O 3  gas exposure (without H 2 O) in the first processing system  200 . 
     The results in  FIG. 4  show that only process recipe I (3 minute O 3  gas exposure in the first processing system  200 , and a second wet processing step of 30 second DHF liquid exposure and substrate rotation in the second processing system  300 ) resulted in complete or near complete removal of the SiARC 17% and SiARC 43%. Furthermore, process recipes C and G resulted in partial removal of the SiARC 17%. 
     Additional film stacks containing SiARC 43% were studied. The film stacks included a Si substrate, a 50 nm thick SiO 2  layer on the Si substrate, a 200 nm thick OPL coating layer on the SiO 2  layer, and a 35 nm thick SiARC 43%. Process recipes containing a first processing step of O 3  gas/H 2 O vapor exposure of 30 seconds (or greater) followed by a second wet processing step of DHF exposure of 5 seconds (or greater) resulted in complete removal of the OPL coating and the SiARC 43%. 
       FIGS. 5A-5F  are schematic cross-sectional views for a method of reworking a film structure containing a SiARC layer according to another embodiment of the invention. The film structure  50  depicted in  FIG. 5A  is similar to the film structure  10  depicted in  FIG. 1A  but contains a substrate containing a low-k layer  500 , an oxide layer  502  on the low-k layer  500 , an OPL coating  504  on the oxide layer  502 , a SiARC layer  506  on the OPL coating  504 , and a photoresist pattern  508  on the SiARC layer  506 . According to some embodiments of the invention, the oxide layer  502  may be omitted and the OPL coating  504  deposited directly on the low-k layer  500 . 
     The photoresist pattern  508  in  FIG. 5A  may be removed from the SiARC layer  506  in a rework process using methods well known to those in the art. In a first example, the photoresist pattern  508  may be removed from the SiARC layer  506  using a conventional dry ashing process, or using a sulfuric acid hydrogen peroxide mixture (SPM) in a wet process or a developer solution/photoresist solvent like propylene glycol monomethyl ether acetate (PGMEA) in a Clean Track system. In a second example, the photoresist pattern  508  may be removed from the SiARC layer  506  by exposure to a process gas containing O 3  gas, followed by a wet spin-off process that centrifugally removes remains of the photoresist pattern  508  in the presence of de-ionized water (DIW) or an alkaline solution. In the second example, removal of the photoresist pattern  508  may be carried out without plasma damage and without formation of residues on the SiARC layer  506 . 
     Removal of the photoresist pattern  508  from the SiARC layer  506  may damage the exposed SiARC layer  506   a .  FIG. 5B  schematically shows a film structure  51  containing a surface roughened region  510  on the SiARC layer  506 . The presence of the surface roughened region  510  can require reworking of the SiARC layer  506  and the OPL coating  504 . 
     According to one embodiment of the invention, following removal of the photoresist pattern  508 , the method includes a first process for modifying the SiARC layer  506  and the OPL coating  504 . The first process may be performed in the first processing system  200  schematically shown in  FIG. 2  and described above. The first process can include disposing the film structure  51  on the substrate holder  212  in the process chamber  210  and heating the process chamber  210  to a desired temperature using the upper heater  202  and the lower heater  204 . For example, the process chamber  210  may be heated to approximately 105° C. Thereafter, a process gas is flowed from the gas heater  222  and into the processing region  224  above the film structure  51  for modifying the SiARC layer  506  and the OPL coating  504 . 
     According to one embodiment, the process gas includes O 3  gas that is flowed from the O 3  generator  218  into the gas heater  222  where it is heated and thereafter the process gas is flowed into the process chamber  210  and exposed to film structure  51  in the processing region  224 . Exemplary processing conditions include a gas flow rate of 4 liters/minute with an O 3  gas concentration of 9% by volume (200 g/m 3 ), balance O 2 . A temperature of the gas heater  222  can be approximately 150° C. and a gas pressure in the processing region  224  can be approximately 75 kPa. According to another embodiment, N 2  gas may be provided from the N 2  supply system  220  and mixed with the O 3  gas in the gas heater  222 . 
     According to another embodiment, the process gas includes a mixture of O 3  gas and H 2 O vapor. The H 2 O vapor can be generated in the H 2 O vaporizer at a temperature of approximately 128° C. and mixed with O 3  gas in the gas heater  222 . The process gas containing the heated mixture of O 3  gas and H 2 O vapor is flowed into the process chamber  210  and exposed to the substrate  100  in the processing region  224 . According to another embodiment, N 2  gas may be provided from the N 2  supply system  220  and mixed with the mixture of O 3  gas and H 2 O vapor in the gas heater  222 . 
       FIG. 5C  shows a film structure  52  containing a modified SiARC layer  512  and modified OPL coating  524  following a first process using O 3  gas in the absence of H 2 O vapor according to one embodiment of the invention. According to another embodiment, the first process may contain a mixture of O 3  gas and H 2 O vapor. According to embodiments of the invention, the formation of the modified SiARC layer  512  and the modified OPL coating  524  enables subsequent complete removal of the modified SiARC layer  512  and the modified OPL coating  524  in a second wet process that includes exposing the modified SiARC layer  512  and the modified OPL coating  524  to DHF and centrifugally removing the layers ( 512  and  524 ). It is speculated that subsequent complete removal of the modified SiARC layer  512  and the modified OPL coating  524  in the second wet process is facilitated by damage in the form of cracks  514  in the modified SiARC layer  512  and the modified OPL coating  524 . It is further speculated that the SiARC layer  506  is modified by the O 3  gas exposure, or by the O 3  gas and H 2 O vapor exposure, to become more “SiO 2 -like”, and the OPL coating  504  is modified to become more water soluble and therefore more easily removed. 
     According to embodiments of the invention, the second wet process removes the modified SiARC layer  512  and the modified OPL coating  524  from the oxide layer  502 . The second wet process may be performed in a second processing system  300  schematically shown in  FIG. 3  and described above. 
       FIG. 5D  shows a film structure  53  following a second wet process for removing the modified SiARC layer  512  and the modified OPL coating  524 . 
     According to one embodiment, the film structure  52  may be exposed to the cleaning liquid and, subsequently, without further exposure to the cleaning liquid, the substrate may be rotated to centrifugally remove the modified SiARC layer  512  and the modified OPL coating  524  from the film structure  52 . 
     According another embodiment, the film structure  52  may be simultaneously exposed to the DHF liquid and the substrate rotated to centrifugally remove the modified SiARC layer  112  and the modified OPL coating  524  from the film structure  52 . 
     According to another embodiment, the film structure  50  containing the photoresist pattern  508  and the SiARC layer  506  shown in  FIG. 5A  may be removed using a first process that includes an exposure to O 3  gas in the process chamber  210 , followed by a second wet process includes exposing the modified SiARC layer  512  and the modified OPL coating  524  to DHF liquid, and centrifugally removing the layers  512  and  524 . A DIW exposure and spinning may be used to remove the DHF liquid. 
     According to another embodiment, the film structure  50  containing the photoresist pattern  508  and the SiARC layer  506  shown in  FIG. 5A  may be removed using a first process that includes an exposure to a mixture of O 3  gas and H 2 O vapor in the process chamber  210 , followed by a second wet process includes exposing the modified SiARC layer  512  and the modified OPL coating  524  to DHF liquid, and centrifugally removing the layers  512  and  524 . A DIW exposure and spinning may be used to remove the DHF liquid. 
     As shown in  FIG. 5E , following the removal of the modified SiARC layer  512  and the modified OPL coating  524 , a new OPL coating  516 , a new SiARC layer  518 , and a new photoresist  520  are deposited on the oxide layer  502  and the photoresist patterning process is repeated on the film structure  54 .  FIG. 5F  shows a new film structure  55  that includes a new photoresist pattern  522  formed on the new SiARC layer  518 . 
       FIG. 6  is a simplified process flow diagram for a method of reworking a film structure containing a SiARC layer according to an embodiment of the invention. In block  610 , at least one substrate is provided that contains a SiARC layer thereon, and a resist pattern formed on the SiARC layer. 
     In block  620 , the resist pattern is removed from the SiARC layer. 
     In block  630 , the SiARC layer is modified by exposure to a process gas containing O 3  gas and optionally H 2 O vapor. 
     In block  640 , the modified SiARC layer is treated with a DHF liquid. A DIW exposure and spinning may be used to remove the DHF liquid. 
     In block  650 , the modified SiARC layer is centrifugally removed from the substrate. 
     According to one embodiment, the modified SiARC layer may be exposed to the DHF liquid in block  640  and, subsequently, without further exposure to the DHF liquid, the modified SiARC layer may be rotated in block  650  to centrifugally remove the modified SiARC layer from the substrate. 
     According to one embodiment, the processing in blocks  640  and  650  may be performed simultaneously or may at least partially overlap in time. In one example, the modified SiARC layer may be simultaneously exposed to the DHF liquid and rotated to centrifugally remove the modified SiARC layer from the substrate. 
     According to one embodiment, the processing in blocks  620  and  630  may be performed simultaneously by exposing the photoresist pattern and the SiARC layer to O 3  gas, and optionally N 2  gas. Subsequently, the modified SiARC layer and any remains of the resist pattern are treated with DHF liquid in block  640  and centrifugally removed in block  650 . 
     According to another embodiment, the processing in blocks  620  and  630  may be performed simultaneously by exposing the photoresist pattern and the SiARC layer to a process gas containing O 3  gas, H 2 O vapor, and optionally N 2  gas. Subsequently, the modified SiARC layer and any remains of the resist pattern are treated with a liquid containing DHF in block  640  and centrifugally removed in block  650 . 
       FIG. 7  is a simplified process flow diagram for a method of reworking a film structure containing a SiARC layer according to another embodiment of the invention. In block  710 , at least one substrate is provided that contains an OPL coating thereon, a SiARC layer on the OPL coating, and a resist pattern formed on the SiARC layer. 
     In block  720 , the resist pattern is removed from the SiARC layer. 
     In block  730 , the SiARC layer and the OPL coating layer are modified by exposure to a process gas containing O 3  gas and optionally H 2 O vapor. 
     In block  740 , the modified SiARC layer and the OPL coating layer are treated with DHF liquid. A DIW exposure and spinning may be used to remove the DHF liquid. 
     In block  750 , the modified SiARC layer and the modified OPL coating are centrifugally removing from the substrate. 
     According to one embodiment, the modified SiARC layer may be exposed to the DHF liquid in block  740  and, subsequently, without further exposure to the DHF liquid, the modified SiARC layer may be rotated in block  750  to centrifugally remove the modified SiARC layer and the modified OPL coating from the substrate. 
     According to one embodiment, the processing in blocks  740  and  750  may be performed simultaneously or may at least partially overlap in time. In one example, the modified SiARC layer may be simultaneously exposed to the DHF liquid and rotated to centrifugally remove the modified SiARC layer and the modified OPL coating from the substrate. 
     According to one embodiment, the processing in blocks  720  and  730  may be performed simultaneously by exposing the photoresist pattern and the SiARC layer to O 3  gas, and optionally N 2  gas. Subsequently, the modified SiARC layer and any remains of the resist pattern are treated with a liquid containing DHF in block  740  and centrifugally removed in block  650  along with the OPL coating. 
     According to another embodiment, the processing in blocks  720  and  730  may be performed simultaneously by exposing the photoresist pattern and the SiARC layer to a process gas containing O 3  gas, H 2 O vapor, and optionally N 2  gas. Subsequently, the modified SiARC layer and any remains of the resist pattern are treated with a liquid containing DHF in block  740  and centrifugally removed in block  750  along with the modified OPL coating. 
     A plurality of embodiments for reworking film structures containing SiARC layers have been described. The foregoing description of the embodiments of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. This description and the claims following include terms that are used for descriptive purposes only and are not to be construed as limiting. For example, the term “on” as used herein (including in the claims) does not require that a film “on” a substrate is directly on and in immediate contact with the substrate; there may be a second film or other structure between the film and the substrate. 
     Persons skilled in the relevant art can appreciate that many modifications and variations are possible in light of the above teaching. Persons skilled in the art will recognize various equivalent combinations and substitutions for various components shown in the Figures. It is therefore intended that the scope of the invention be limited not by this detailed description, but rather by the claims appended hereto.