Patent Publication Number: US-6905800-B1

Title: Etching a substrate in a process zone

Description:
BACKGROUND 
     The invention relates to etching a substrate in a process zone. 
     In the manufacture of integrated circuits, active and passive devices are formed on a substrate, such as a semiconductor wafer, by alternately depositing and etching layers of dielectric, semiconducting, and conducting materials, such as silicon dioxide, polysilicon, and metal-containing materials. These layers may be etched to form a pattern of etched features in a predefined pattern of gates, vias, contact holes, trenches, and/or metal interconnect lines. Etching is typically performed using an energized etchant gas, such as a halogen-containing gas, as for example described in  Silicon Processing for the VLSI Era , Vol. 1, Chapter 16, by Wolf and Tauber, Lattice Press, 1986, which is incorporated herein by reference. 
     The predefined pattern may be formed by providing photoresist over an underlying material to be etched. The photoresist may be patterned by lithography to expose portions of the underlying material. However, when photoresist is used it often is difficult to maintain the critical dimensions of the etched features. It is also difficult to obtain good etching selectivity for etching underlying material relative to the photoresist, especially when the underlying material is an oxide. In addition, while etching the underlying material, process conditions are generally selected to preserve the photoresist to prevent premature removal of the photoresist and also to reduce deposition of process residues on chamber or substrate surfaces. Furthermore, residual photoresist portions that are not etched by the etchant gases and which remain on the substrate after the etching process may need to be removed in a post processing step. Conventional photoresist removal processes, also known as stripping or ashing, are sometimes ineffective in removing all the resist from the substrate without overexposing a processed substrate to the energized stripping gas. In addition, resist removal processes compromise process throughput by adding a process step and a separate process chamber. 
     The process chambers used in processing a substrate are periodically cleaned to remove process residue deposits and contaminants that are formed on the surfaces in the chamber, otherwise these deposits may flake off and contaminate the substrate. In etching processes, after etching every 100 to 300 wafers, the chamber is often opened to the atmosphere and cleaned in a “wet-cleaning” process, in which an operator uses an acid or solvent to scrub off or dissolve accumulated etch residue on the chamber surfaces. After cleaning, the chamber is pumped down in a vacuum for 2 to 3 hours to outgas volatile species, and a series of etching runs are performed on dummy wafers until the chamber provides consistent etching properties. However, the downtime of the etching chamber during the cleaning process can substantially increase the cost per substrate. Also, because the wet cleaning process is manually performed, the cleanliness of the chamber surfaces often vary from one cleaning session to another. 
     Therefore, it is desirable to be able to etch a substrate with improved critical dimension control and etching selectivity. It is further desirable to process the substrate with increased throughput. It is still further desirable to process a substrate in a substantially clean process chamber to reduce the possibility of contaminating the substrate. It is still further desirable to remove sufficient amounts of etch resistant material from the substrate without undesirably etching the substrate with the energized gas. 
     SUMMARY 
     The present invention satisfies these needs. In one aspect of the invention, a substrate processing method comprises providing a substrate in a process zone, the substrate comprising etch resistant material over an underlying material, removing the etch resistant material in the process zone, and after the etch resistant material is removed, providing an energized process gas in the process zone to etch the underlying material. 
     In another aspect of the invention, a substrate processing method comprises providing a substrate in a process zone, the substrate comprising a first and a second etch resistant material, providing an energized process gas in the process zone to form apertures in the first etch resistant material, and removing the second etch resistant material in the process zone. 
     In another aspect of the invention, a substrate processing method comprises providing a substrate in a process zone, the substrate comprising etch resistant material, and removing the etch resistant material while detecting radiation emanating from the process zone. 
     In another aspect of the invention, a substrate processing method comprises providing a substrate in a process chamber, providing an energized process gas in the chamber to process the substrate, thereby depositing process residue on surfaces of the process chamber, providing an energized process gas in the chamber to simultaneously remove a material from the substrate and at least partially remove the process residue from the surfaces of the process chamber, and providing an energized process gas in the chamber to further process the substrate. 
     In another aspect of the invention, a substrate processing method comprises providing a first substrate in a process chamber, providing an energized process gas to etch the first substrate, thereby depositing first residue on the surfaces of the process chamber, providing a second substrate in the process chamber, and providing an energized process gas to process the second substrate and simultaneously remove the first residue from the surfaces of the process chamber. 
     In another aspect of the invention, a substrate processing method comprises providing a first substrate in a process chamber, providing an energized process gas to etch the first substrate, thereby depositing first residue on the surfaces of the process chamber, providing a second substrate in the process chamber, and providing an energized process gas to at least partially remove the first residue from the surfaces of the process chamber, and removing the second substrate from the chamber. 
     In another aspect of the invention, a substrate processing method comprises providing a substrate in a process chamber, providing a first energized process gas to etch a material on the substrate, thereby depositing residue on the surfaces of the process chamber, providing a second energized process gas to remove substantially all of the residue deposited from the surfaces of the process chamber, and removing the second substrate from the chamber. 
     In another aspect of the invention, a substrate processing method comprises providing a substrate in a process zone, the substrate comprising resist material over mask material, providing an energized process gas in the process zone to form apertures in the mask material, providing an energized process gas in the process zone to remove the resist material, and providing an energized process gas in the process zone to etch a layer under the mask material. 
    
    
     
       DRAWINGS 
       These features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings which illustrate exemplary features of the invention. However, it is to be understood that each of the features can be used in the invention in general, not merely in the context of the particular drawings, and the invention includes any combination of these features, where: 
         FIG. 1  is a schematic sectional side view of a process chamber with a process zone adapted to process a substrate according to the present invention; 
         FIGS. 2   a  through  2   d  are schematic sectional side views of a substrate that is processed according to one version of the present invention; 
         FIGS. 3   a  through  3   c  are schematic sectional side views of a substrate that is processed according to another version of the present invention; 
         FIGS. 4   a  through  4   e  are schematic sectional side views of a substrate that is processed according to yet another version of the present invention; 
         FIG. 5  is a schematic sectional side view of a substrate processing apparatus and endpoint detection system according to the present invention; and 
         FIG. 6  is an illustrative block diagram of a structure of a computer program suitable for operating the chamber and monitoring a process performed therein. 
     
    
    
     DESCRIPTION 
     The present invention relates to processing a substrate in an apparatus, for example to fabricate integrated circuits on the substrate and is particularly useful for processing layers, such as etch resistant, silicon-containing, metal-containing, dielectric, and/or conductor layers on the substrate. Although the process is illustrated in the context of etching one or more of the layers on the substrate, the present invention can be used in other processes such as chemical vapor deposition (CVD), physical vapor deposition (PVD), evaporation, post etch treatment, and other substrate fabrication processes and should not be limited to the examples provided herein. 
     An apparatus  100  suitable for processing a substrate  105  according to the principles of the present invention comprises a process chamber  110 , such as a “DPS” chamber, schematically illustrated in  FIG. 1 , and commercially available from Applied Materials Inc., Santa Clara, Calif. The particular embodiment of the apparatus  100  shown herein is suitable for processing substrates  105 , such as semiconductor wafers, and may be adapted by those of ordinary skill to process other substrates  105 , such as flat panel displays, polymer panels, or other electrical circuit receiving structures. The apparatus  100  is provided only to illustrate the invention, and should not be used to limit the scope of the invention or its equivalents to the exemplary embodiments provided herein. The apparatus  100  may be attached to a mainframe unit that contains and provides electrical, plumbing, and other support functions for the apparatus  100 . Exemplary mainframe units compatible with the illustrative embodiment of the apparatus  100  are currently commercially available as the Precision 5000™ systems from Applied Materials, Inc., of Santa Clara, Calif. The multichamber system has the capability to transfer a wafer between its chambers without breaking the vacuum and without exposing the wafer to moisture or other contaminants outside the multichamber system. An advantage of the multichamber system is that different chambers in the multichamber system may be used for different purposes in the entire process. For example, one chamber may be used for etching a substrate  105 , another for the deposition of a metal film, another may be used for rapid thermal processing, and yet another may be used for depositing an anti-reflective layer. The process may proceed uninterrupted within the multichamber system, thereby preventing contamination of substrates  105  that may otherwise occur when transferring substrates  105  between various separate individual chambers (not in a multichamber system) for different parts of a process. 
     Generally, the apparatus  100  comprises a chamber  110  comprising walls typically fabricated from metal or ceramic materials. Metals commonly used to fabricate the chamber  110  include aluminum, anodized aluminum, “HAYNES 242,” “AI-6061,” “SS 304,” “SS 316,” and INCONEL, of which anodized aluminum is preferred. In the embodiment shown, the chamber  110  comprises a wall which may comprise a ceiling  115 , sidewalls  117 , and a bottom wall  118 . The ceiling  115  may comprise a substantially arcuate portion, or in other versions, the ceiling  115  may comprise a dome, substantially flat, or multi-radius shaped portion. The chamber  110  typically comprises a volume of at least about 5,000 cm 3 , and more typically from about 10,000 to about 50,000 cm 3 . In operation, process gas is introduced into the chamber  110  through a gas supply  120  that includes a process gas source  122 , conduits  124  having flow control valves  126 , and gas outlets  128  around a periphery of the substrate  105  which may be held on a support  130 . As an alternative to the configuration shown in  FIG. 1 , the process gas may be introduced through a showerhead (not shown) mounted on or near the ceiling  115  of the chamber. Spent process gas and etchant byproducts are exhausted from the chamber  110  through an exhaust system  132  which includes a pumping channel  134  that receives spent process gas, a throttle valve  136  to control the pressure of process gas in the chamber  110 , and one or more exhaust pumps  138 . The exhaust system  132  may also contain a system for abating undesirable gases from the exhaust. 
     The process gas is energized to process the substrate  105  by a gas energizer  150  that couples energy to the process gas in the process zone  155  of the chamber  110  (as shown) or in a remote zone upstream from the chamber  110  (not shown). In one version, the gas energizer  150  comprises an antenna  160  comprising one or more inductor coils which may have a circular symmetry about the center of the chamber  110 . Typically, the inductor coils  160  comprises solenoids having from about 1 to about 20 turns. A suitable arrangement of solenoids is selected to provide a strong inductive flux linkage and coupling to the process gas. When the antenna  160  is positioned near the ceiling  115  of the chamber  110 , the adjacent portion of the ceiling may be made from a dielectric material, such as silicon dioxide, which is transparent to RF or electromagnetic fields. An antenna power supply  165  provides, for example, RF power to the antenna  160  at a frequency of typically about 50 KHz to about 60 MHz, and more typically about 13.56 MHz; and at a power level of from about 100 to about 5000 Watts. An RF match network may also be provided. 
     In one version, the gas energizer  150  may also or alternatively comprise process electrodes that may be powered by a power supply  157  to energize or further energize the process gas. Typically, the process electrodes include one electrode in a wall, such as a sidewall  117  or ceiling  115  of the chamber  110  that may be capacitively coupled to another electrode, such as an electrode in the support  130  below the substrate  105 . The electrode may comprise a dielectric ceiling  115  that serves as an induction field transmitting window that provides a low impedance to an RF induction field transmitted by the antenna  160  above the ceiling  115 . Suitable dielectric materials that can be employed include materials such as aluminum oxide or silicon dioxide. Generally, the electrodes may be electrically biased relative to one another by an electrode voltage supply (not shown) that includes an AC voltage supply for providing an RF bias voltage. The RF bias voltage may comprise frequencies of about 50 kHz to about 60 MHz, and is preferably about 13.56 MHz, and the power level of the RF bias current is typically from about 50 to about 3000 watts. Alternatively or additionally, the gas energizer  150  may comprise a microwave gas activator (not shown) that transmits microwaves to the gas to energize the gas. 
     The support  130  may comprise an electrostatic chuck  170  which comprises a base  172  for supporting a dielectric  174  which comprises a portion  176  which at least partially covers a chucking electrode  178  and which may include a substrate receiving surface  180 . The electrode  178  may also serve as one of the process electrodes discussed above (as shown in FIG.  5 ). Alternatively, the base  172  may serve as a process electrode (as shown in FIG.  1 ). The base  172  may have channels (not shown) through which heat transfer fluid is circulated to heat or cool the substrate  105 . The base  172  may be generally shaped and sized to match the shape and size of the substrate  105  to maximize heat transfer to the substrate. For example, for a substrate  105  having a circular or disk shape, the base  172  may be of generally right cylindrical shape. In one version, the base  172  comprises an electrically conducting material, such as aluminum, and is surrounded by an insulating shield or jacket made of, for example, an insulating polymeric or ceramic material, such as quartz. In one version, the base  172  may be electrically biased by a voltage supply. 
     The dielectric  174  of the support  130  or electrostatic chuck  170  isolates, or partially isolates, the electrode  178  from the substrate  105  and the energized gas in the chamber  120 . In an alternative configuration, the dielectric  174  may cover the base  172  which serves as the electrode. As shown, the dielectric  174  comprises a monolith in which the electrode  178  is embedded. The dielectric  174  may be made from a dielectric material that is resistant to erosion by the gas or plasma and capable of withstanding high temperatures. Suitable dielectric materials include, for example, ceramic materials, such as Al 2 O 3 , AlN, BN, Si, SiC, Si 3 N 4 , TiO 2 , ZrO 2 , and mixtures and compounds thereof, and polymeric materials such as polyimide, polyamide, polyetherimide, polyketone, polyetherketone, polyacrylate, fluoroethylene, or mixtures thereof or the like. The thickness of the portion of dielectric material  176  overlying the electrode  178  is typically from about 100 micrometers to about 1000 micrometers. 
     The support  130  or electrostatic chuck  170  may also comprise temperature controlling devices. For example, the dielectric  174  may comprise one or more conduits (not shown) extending therethrough, such as for example, a gas conduit provided to supply heat transfer gas from a heat transfer gas supply (not shown) to an interface between the surface  180  of the dielectric  174  and the substrate  105 . The heat transfer gas, typically helium, promotes heat transfer between the substrate  105  and the support  130  or electrostatic chuck  170 . Other conduits may, for example, allow lift pins (not shown) to extend through the dielectric  174  for loading or unloading of the substrate  105  by a lift mechanism. The support  130  may also comprise a heating system  182 . In one version the heating system may comprise a heating element  184 , such as a resistively heated plate, wire, mesh or coil, through which a current may pass to cause the element to increase in temperature. A heater power supply  186  may be provided to provide a heating voltage to the heating element  184  under the control of a system controller. 
     The electrode  178  may be capable of generating an electrostatic charge for electrostatically holding the substrate  105  to the support  130  or electrostatic chuck  170 . A DC voltage supply  188  provides the chucking voltage to the electrode  178  through an electrical connector  190  such as a banana jack inserted through the dielectric  174 . The DC chuck power supply  188  typically provides a DC chuck voltage of 250 to 2000 volts to the electrode  178 . The voltage supply  188  can also include a system controller for controlling the operation of the electrode  178  for chucking or dechucking the substrate  105 . 
     In another chamber embodiment (not shown), the energized gas, such as a capacitively generated plasma, may be substantially confined to the process zone  155  immediately above the surface of the substrate  105  by a magnetic field (not shown) that is substantially perpendicular to the plane of the substrate. The magnetic field is generated by permanent magnets or electromagnets (neither shown) adjacent to the chamber  110 , as for example, described in U.S. Pat. No. 4,842,683, issued Jun. 27, 1989, which is incorporated herein by reference. 
     Processing a Substrate 
     The apparatus  100  illustrated herein can be used to process material on a substrate  105 , for example to etch material from the substrate  105 ; remove contaminant deposits or residues deposited on surfaces in the chamber  110 , such as on the surfaces of walls of the chamber  110  and the surfaces of components in the chamber  110 ; perform post processing treatment of a substrate  110 , or the like. For example, in one version, the apparatus  100  may be used to etch a substrate  105 , such as a substrate  105  comprising one or more layers of material. Such layers are often superimposed on one another and may comprise dielectric layers comprising, for example, silicon dioxide, undoped silicate glass, phosphosilicate glass (PSG), borophosphosilicate glass (BPSG), Si 3 N 4 , or TEOS deposited glass; semiconducting layers comprising, for example, silicon-containing layers such as polysilicon or a silicon compound; and conductive layers such as metal-containing layers comprising, for example, aluminum, copper, or metal silicide such as tungsten silicide and cobalt silicide. Suitable etchant gases for etching layers on the substrate  105 , include for example, HCl, BCl 3 , HBr, Br 2 , Cl 2 , CCl 4 , SiCl 4 , SF 6 , F, NF 3 , HF, CF 3 , CF 4 , CH 3 F, CHF 3 , C 2 H 2 F 2 , C 2 H 4 F 6 , C 2 F 6 , C 3 F 8 , C 4 F 8 , C 2 HF 5 , C 4 F 10 , CF 2 Cl 2 , CFCl 3 , O 2 , N 2 , He, and mixtures thereof. The etchant gas is selected to provide high etch rates, and highly selective etching of the particular layers or materials that are being etched. When multiple layers are sequentially etched, first, second, third, etc., etchant gas compositions may be sequentially introduced into the chamber to etch each particular layer, 
     To etch one or more of the layers on the substrate  105  in the process chamber  110 , process gas comprising etchant gas is introduced from the gas supply  120  into the process zone  155  and energized by the gas energizer  150  to form an energized gas. The gas may be energized by inductively and/or capacitively coupling energy into the process zone  155  of the chamber  110 , or by applying microwaves thereto or to an etchant gas in a remote zone of a remote chamber (not shown) that is at a location remote from the process zone  155 . By “energized process gas” it is meant that the process gas is activated or energized so that one or more dissociated species, non-dissociated species, ionic species, and neutral species are excited to higher energy states in which they are more chemically reactive. In the version shown in  FIG. 1 , the process gas is energized by applying an RF source current to the inductor antenna  160  adjacent to the chamber  110  and optionally by also applying an RF bias voltage to process electrodes. The energized etchant gas etches one or more layers on the substrate  105  to form volatile gaseous species that are exhausted from the chamber  110  by exhaust system  132 . 
     An example of a substrate  105  which may be etched in accordance with the present invention is shown in  FIG. 2   a . In the version of  FIG. 2   a , the substrate  105  comprises etch resistant material  210  overlying a workpiece  220 , which may comprise one or more layers of material. The etch resistant material  210  is resistant to etch by process gas which is introduced into a process zone  155  under process conditions selected to etch into and/or through an underlying material, such as the workpiece  220  which may be a wafer or layers on a wafer as will be discussed. The etch resistant material  210  may be patterned to expose portions of the underlying material for etching. For example, the etch resistant material  210  may comprise resist material  230 , such as polymeric or organic resist. The resist material  230  may be patterned by conventional photolithographic methods or may be patterned by etching the resist material  230  in a process chamber  110 . In one version, the etch resistant material  210  comprises an organic, polymeric photoresist that is transparent to ultraviolet light frequencies and does not block incident light beams having wavelengths in the ultraviolet range. Alternatively or additionally, the etch resistant material  210  may comprise mask material  240  comprising, for example, a dielectric material or hard mask, such as silicon oxide, TEOS, silicon nitride, or equivalents. In the version of  FIG. 2   a , the substrate  105  comprises an etch resistant material  210  comprising a patterned resist material  230  over a mask material  240 . 
     The mask material  240  may be patterned by providing the substrate in a process zone  155  and introducing process gas into the process zone  155  to etch into the exposed portion  250  of the mask material  240  to form apertures  245  therein in accordance with the pattern of the resist material  230 . For example, the process gas may comprise a mask material etching gas comprising one or more gases selected to etch into the mask material  240 . In one version, a process gas comprising a mask material etching gas is introduced to etch into and through the mask material  240  to open the mask and form the apertures  245 , as shown in  FIG. 2   b , to expose a portion  260  of the workpiece  220 . In one version, the mask material etching gas comprises a halogen containing gas, such as a fluorine containing gas. For example, the mask etching gas may comprise one or more of HCl, BCl 3 , HBr, Br 2 , Cl 2 , CCl 4 , SiCl 4 , SF 6 , F 2 , NF 3 , HF, CF 3 , CF 4 , CH 3 F, CHF 3 , C 2 H 2 F 2 , C 2 H 4 F 6 , C 2 F 6 , C 3 F 8 , C 4 F 8 , C 2 HF 5 , C 4 F 10 , CF 2 Cl 2 , CFCl 3  or equivalents. In one particular version, the mask material comprises one or more of silicon oxide, TEOS, and silicon nitride and the mask material etching gas comprises one or more of CF 4 , C 2 F 6 , SF 6 , and NF 3 . The process gas may further comprise a carrier or inert gas, such as one or more of Ar and He to aid in controlling etch sputtering and/or dilution. 
     The resist material  230  may be removed from the substrate by introducing an energized stripping gas into the process zone  155 . The stripping gas may comprise one or more of O 2 , N 2 , H 2 O, NH 3 , CF 4 , C 2 F 6 , CHF 3 , C 3 H 2 F 6 , C 2 H 4 F 2 , or CH 3 F. A suitable stripping gas for stripping the polymeric resist comprises (i) oxygen, and (ii) an oxygen activating gas or vapor, such as nitrogen gas, water vapor, or fluorocarbon gas, the fluorocarbon gases including any of those listed above. The oxygen activating gas increases the concentration of oxygen radicals in the stripping gas. In one version, the stripping gas comprises oxygen and nitrogen in a volumetric flow ratio of about 1:2 to about 200:1, and more preferably from about 0.8:1 to about 12:1, and most preferably about 1:1. For a 5000 cm 3  process chamber  110 , a suitable gas flow rate comprises about 100 sccm of O 2  and about 100 sccm of N 2 . The substrate  105  may be exposed to the stripping gas for a period of time of from about 10 seconds to about 1000 seconds, and more preferably for about 60 seconds. A single stripping step may be performed or multiple stripping steps may be performed, as discussed in U.S. Pat. No. 5,545,289, which is incorporated herein by reference in its entirety. 
     In one version of the invention, the resist material  230  may be removed from the substrate  105  before the workpiece  220  is etched. For example, following forming the apertures  245  to pattern the mask material  240 , the resist material  230  may be removed, as shown in  FIG. 2   c , leaving patterned mask material  240  over the workpiece  220 . The resist material  230  may be removed by exposing the resist material  230  or remnant resist material to an energized stripping gas, for example. After removal of the resist material  230 , the exposed portions  260  of the workpiece  220  may be etched by introducing etchant gas, for example halogen-containing gas, to form features  270 , such as apertures that may be used to form, for example, gates, vias, contact holes, trenches, and/or metal interconnect lines, as shown in  FIG. 2   d.    
     Removing the resist material  230  before etching features  270  in the workpiece  220  has several advantages over post-etch removal of the resist material  230 . For example, when the resist material  230  is removed and an underlying mask material  240  serves as the etch resistant material  210  for defining the pattern that will be etched into the workpiece  220 , an improved etch of the workpiece  220  may be performed. The mask material  240  is often more resistant to the etchant gas introduced to etch the workpiece  220  than the resist material  230  and thereby provides better selectivity to etching the underlying material. This allows for improved critical dimension (CD) control. In addition, by eliminating the necessity to preserve the resist material  230 , more aggressive workpiece etchant process conditions may be utilized, thereby allowing for an increased etch rate of the workpiece  220 . Also, when resist material  230  is present during etching of a silicon-containing material in the workpiece  220 , partial removal or sputtering of the resist material  230  and etchant byproducts from the etching of the workpiece  220  can create a sandwich type of residue that can deposit on the substrate  105  and/or on surfaces of the chamber  110 . The sandwich type deposit, such as layered silicon oxide and polymer, are difficult to clean and potentially can flake-off and affect the quality of the processed substrate  105 . By removing the resist material  230  before etching the workpiece  220 , the formation of the sandwich type deposits during etching of the workpiece  220  can be substantially avoided. 
     In one version, the resist material  230  is removed from the substrate  105  and the workpiece  220  is etched in the same process zone  155 . The resist material  230  may also be removed before the workpiece  220  is etched. Removing resist material  230  and etching the workpiece  220  in the same process zone improves process throughput. For example, by not transferring the substrate from an etching chamber to a resist removal chamber, throughput can be substantially increased. Additionally, eliminating the necessity of a resist removal chamber in a multichamber system can provide space for parallel processing of substrates, further increasing throughput. In another version, The mask material  240  is patterned and the resist material  230  is removed in the same process zone  155 . This version also increases throughput and provides additional processing space in a multichamber system by avoiding the need to have a separate mask material  240  etching chamber and resist material  230  removal chamber. 
     In another version, apertures are formed in the mask material  240 , the resist material  230  is removed, and the workpiece  220  is etched in the same process zone  155 . This version further increases throughput by using a single chamber instead of three chambers and provides even more utilizable space in a multichamber system. In addition, performing all three of these steps in a single process zone  155  provides unexpected results. For example, among the unexpected advantages are improved chemistry compatibilities, synergistic chamber cleaning treatment, simplified post processing treatment, and enhanced etch performance. 
     By using a single process zone  155  to form apertures in the mask material  240 , remove resist material  230 , and etch the workpiece  220 , the process conditions may be selected to result in simultaneous chamber cleaning and substrate processing. For example, when mask material  240 , which may comprise silicon oxide, silicon nitride, or TEOS, is opened in a mask patterning process gas, polymeric residue may be formed on the substrate and on surfaces  275  in the chamber  110 . These surfaces  275  include the surfaces of walls of the chamber  110  and the surfaces of components within or near the chamber  110 . The process residue may be removed during the removal of the resist material  230 . For example, the process gas comprising stripping gas may be introduced under process conditions selected to simultaneously remove the resist material  230  from the substrate  105  and remove the residue deposited on the chamber surfaces  275  during etching of the mask material  240 . This provides a chamber  110  with surfaces  275  substantially devoid of residue when etching of the workpiece  220  is initiated. During etching of the workpiece  220 , particularly during etching of silicon-containing layers or material in or on the workpiece  220 , etchant residue may be deposited on the surfaces  275  in the chamber  110 . The etchant residue may comprise, for example, silicon oxide. Thus, when the substrate  105  is removed from the chamber  110 , and a second substrate  105  is provided in the process zone  155  and process gas comprising mask material etching gas is introduced to open the mask material  240  of the second substrate  105 , the mask material etching gas may be introduced under process conditions selected to also remove residue on the chamber surfaces  275  that was generated during the etching of the workpiece  220  of the previously processed substrate  105 . The residue then formed during etching of the mask material  240  is deposited directly on the chamber surfaces  275  rather than on top of previously formed etchant residue, and this residue is then removed as discussed above. This cyclical etching and cleaning process may continue throughout processing of a batch of substrates  105  with the mask material patterning step simultaneously cleaning etchant residue formed during processing of a previous substrate, the resist material removal step simultaneously removing residue formed during mask patterning of the present substrate. Thus, a consistently clean chamber is continuously present for the initiation of etching of each substrate  105  in the batch of substrates. 
     In one version, a two-step mask material etch may be performed. For example, a first step may comprise exposing mask material  240  to process gas comprising a composition that is substantially absent a polymer forming gas and the second step may comprise exposing the mask material  240  to process gas having a composition comprising a polymer forming gas. In one particular version, the first mask material etchant gas may comprise a fluorine-containing gas, for example, in one version, the first mask material etchant gas comprises one or more of CF 4 , C 2 F 6 , NF 3 , and SF 6 , and the second mask material etchant gas may comprise one or more of CHF 3 , CH 2 F 2 , and CH 3 F, with or without one or more of CF 4 , C 2 F 6 , NF 3 , and SF 6 . The first or second mask material etchant gases may also comprise an inert or carrier gas, such as Ar, He, or N to aid in controlling sputtering and/or dilution. In this version, the etchant residue formed during processing of a previous substrate may be cleaned from the chamber surfaces  275  before polymeric residues are formed and deposited thereon. This can result in easier removal of the etchant deposits. Sandwich deposits comprising a layer of silicon-containing etchant residue and a layer of polymer can be difficult to clean and can result in flaking during substrate processing that can affect the quality of the processing. By first introducing a non-polymerizing mask etching gas, the mask material  240  may be etched and the etchant residue may be cleaned from the chamber surfaces  275  before the polymeric residue  13  formed and deposited on the chamber surfaces  275 . It is advantageous to use the mask material etchant gas comprising polymer forming gas because it aids in etch process performance. 
     Another advantage of performing the mask material  240  patterning step, the resist material  230  removal step, and the workpiece  220  etching step in the same process zone  155  is that post processing treatment of the substrate  105  may be simplified. For example, the etch resistant material  210  may, in one version, comprise an anti-reflective coating (ARC), material  280  between the resist material  230  and the mask material  240 , as shown in  FIG. 3   a . Anti-reflective coating material, such as SiON, or SiN, assists in photolithographic processes. As shown in  FIG. 3   b , after the mask material  240  has been opened and the resist material  230  has been removed, a top layer of ARC material  280  remains on the substrate. Typically, the ARC material  280  is removed from the substrate in a separate post processing treatment step. However, in one version of the invention, the workpiece  220  may be etched and the ARC material  280  may be simultaneously removed by exposing the workpiece  220  and the ARC material  280  to process gas comprising etching gas under process conditions selected to etch into the workpiece  220  and remove the ARC material  280 , as shown in  FIG. 3   c . In one version, the process gas comprises a fluorine-containing gas, such as CF 4 , and a halogen-containing gas, such as Cl 2  and, optionally nitrogen or argon. The resulting processed substrate  105  does not need a separate ARC material removal step in another process chamber. 
     One particular version of the invention is shown in  FIGS. 4   a - 4   e . This version is merely exemplary and is not intended to limit the invention. As shown in  FIG. 4   a , a substrate  105  that may be processed in accordance with the present invention may include etch resistant material  210  overlying a workpiece  220 . The etch resistant material may comprise resist material  230 , such as photoresist, and mask material  240 , such as silicon oxide, TEOS, or silicon nitride, with anti-reflective material  280 , such as TiN, silicon oxynitride, silicon nitride, or organic anti-reflective material, therebetween. The workpiece  220  may comprise a base  290 , such as a wafer comprising silicon or a compound semiconductor, such as gallium arsenide, which may have doped regions. A semiconducting or conducting material  300 , for example a silicon-containing layer such as doped or undoped polysilicon or a silicon compound such as metal silicide overlies the base  290 . Between the semiconducting or conducting material  300 , a gate oxide material  310  may be provided. The gate oxide material may comprise an oxide material, such as silicon oxide, having a thickness of from about 10 Å to about 300 Å. Other versions of substrates  105  may alternatively be processed. For example, one or more of the above described layers may be removed and/or a metal containing layer or a diffusion barrier layer, comprising for example one or more of Ti, TiN, Ta, TaN, W, and WN may be provided. 
     Table 1 summarizes an example of process conditions including process gas compositions which may be used to process the substrate  105  of  FIG. 4   a  and clean the process chamber  110  in accordance with one version of the present invention. After providing the substrate  105  in the process zone  155 , an anti-reflective coating etch step comprises providing energized process gas comprising reactive and non-reactive gas, such as CF 4  and Ar, respectively, in the process zone  155  to etch the anti-reflective coating  280 , if present. In one version, the volumetric flow ratio of non-reactive to reactive gas is from about 0:1 to about 5:1, more preferably from about 1:1 to about 2:1, and most preferably about 1.5:1. The mask material  240  may be etched in two steps. A first mask material etch step comprises providing energized process gas comprising reactive and non-reactive gas, such as CF 4  and Ar, respectively, in the process zone  155  to etch the mask material  240  and to remove etchant residue that may have been formed during the processing of previous substrates. In one version, the volumetric flow ratio of non-reactive to reactive gas is from about 0:1 to about 5:1, more preferably from about 1:1 to about 2:1, and most preferably about 1.5:1. A second mask material etch step comprises providing energized process gas comprising reactive gas and non-reactive gas in the process zone  155  to further etch the mask material  240 . In one version, the reactive gas comprises a polymer generating gas, such as CHF 3 , CH 2 F 2 , or CH 3 F. Optionally, an additional reactive gas, such as CF 4 , may be provided. The volumetric flow ratio of non-reactive to reactive gas may be from about 0:1 to about 5:1, more preferably from about 1:1 to about 2:1, and most preferably about 1.5:1.  FIG. 4   b  shows a substrate  105  with the mask material  240  etched to form a patterned mask layer. The next step comprises removing remnant resist material  230 , and optionally removing polymeric residue on the chamber surfaces  275  formed during etching of the mask material  240 , by providing an energized stripping gas, such as O 2  and N 2  in a volumetric flow ratio of oxygen to nitrogen of about 1:0 to about 1:5, more preferably from about 2:1 to about 1:2, and most preferably about 1:1, or other stripping gas as discussed above. The mask material  240  may then serve as etch resistant material  210  to form a pattern in the underlying material, as shown in  FIG. 4   c.    
     
       
         
           
               
               
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                   
                   
                 Source 
                 Bias 
                   
                 Temper- 
               
               
                   
                 Process Gas 
                 Power 
                 Power 
                 Pressure 
                 ature 
               
               
                 Material 
                 Flow Ratio 
                 (Watts) 
                 (Watts) 
                 (mTor) 
                 (° C.) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 Anti-reflective 
                 3/2 
                 600 
                 150 
                 4 
                 50 
               
               
                 Coating Etch 
                 Ar/CF 4   
               
               
                 Mask Material 
                 3/2 
                 600 
                 150 
                 4 
                 50 
               
               
                 First Etch 
                 Ar/CF 4   
               
               
                 Mask Material 
                 6/1/3 
                 600 
                 150 
                 4 
                 50 
               
               
                 Second Etch 
                 Ar/CF 4 /CHF 3   
               
               
                 Resist 
                 1/1 
                 1000 
                 100 
                 150 
                 50 
               
               
                 Stripping 
                 O 2 /N 2   
               
               
                 Metal Silicide 
                 2/2/1 
                 400 
                 75 
                 4 
                 50 
               
               
                 Etch 
                 CF 4 /Cl 2 /N 2   
               
               
                 Polysilicon 
                 60/1 
                 300 
                 60 
                 15 
                 50 
               
               
                 First Etch 
                 HBr/O 2   
               
               
                 Polysilicon 
                 72.5/1 
                 450 
                 120 
                 65 
                 50 
               
               
                 Second Etch 
                 HBr/O 2   
               
               
                   
               
            
           
         
       
     
     The workpiece  220  may then be etched in the process zone  155 . The semiconducting or conducting material  300  may comprise a metal suicide layer and/or a polysilicon layer. A metal silicide layer, such as WSi, may be etched by providing an energized process gas comprising non-reactive gas and reactive gas in a volumetric flow ratio of from about 0:1 to about to about 4:1, more preferably from about 0:1 to about 1:1, and most preferably about 1:4. The reactive gas may comprise, for example, one or more of the earlier mentioned etchant gases, such as one or more of CF 4 , C 2 F 6 , NF 3 , SF 6 , Cl 2 , Br 2 , HBR, and HCl. The non-reactive gas may comprise N 2 , Ar, or the like. In one version, a polysilicon layer may be etched by providing an energized process gas comprising a halogen-containing gas, such as one or more of HBr, HCl, Br 2 , Cl 2 , CF 4 , NF 3 , and SF 6 , and optionally an oxygen-containing gas, such as one or more of O 2 , O 3 , and He-O 2 . In one version, the polysilicon layer may be etched in a two steps, such as shown in Table 1, to provide controlled etch feature shape, as desired. As shown in  FIGS. 4   d  and  4   e , as the semiconducting or conducting material  300  is being etched, the ARC material  280  may be removed. 
     Since the workpiece  220  is not susceptible to the energized stripping gas used to remove the resist material  230 , process conditions can be selected to remove the resist material  230  at a high rate. For example, a bias power of from about 20 watts to about 500 watts, more preferably from about 100 watts to about 200 watts, and most preferably about 100 watts, can be applied during the resist material removal. The bias power has been shown to aid in sputtering the resist material  230  or other residue on the substrate  105 . Additionally, the chamber pressure can be increased to at least about 4 mTorr, and more preferably at least about 100 mTorr, to help facilitate the resist removal by increasing oxygen concentration. To further increase the resist material removal rate, the substrate  105  can be heated, such as by shutting off the circulation of cooling fluid in the support  130 , to a temperature of at least about 100 degrees C. The substrate  105  may then be cooled down to etch the workpiece  220 . 
     To remove sufficient amounts of the resist material  230  without overexposing the substrate  105  to energized stripping gas, the apparatus  100  and chamber  110  may comprise a process monitoring system  410  which may include an endpoint detection system to detect the occurrence of an endpoint of, for example, resist material removal, as shown in FIG.  5 . Endpoint detection methods are used to measure the endpoint of a process to prevent over processing of a material by stopping or changing the process conditions when an endpoint is detected. Endpoint measurement techniques include, for example, plasma emission analysis, interferometry, and ellipsometry, which detect radiation emanating from the chamber  110 . Plasma emission analysis involves analyzing the emission spectra of energized gas in the process zone  155  to determine a change in chemical composition that corresponds to a change in the chemical composition of the material being etched, as disclosed in U.S. Pat. No. 4,328,068 which is incorporated herein by reference in its entirety. Optical emission detection for endpoint determination is also discussed in Chapter 16, of  Silicon Processing for the VLSI Era. Volume  1:  Process Technology , by Stanley Wolf et al., Lattice Press (1986), which is incorporated herein by reference in its entirety. The present invention is useful for monitoring events, such as events related to an endpoint, in an apparatus via a radiation measuring technique. 
     In the version shown in  FIG. 5 , the chamber  110  comprises a process monitoring system  410  to monitor the process being performed on the substrate  105 . The process monitoring system  410  comprises a radiation source  415  that may be outside or inside the chamber  110 . The radiation source  415  may provide radiation such as ultraviolet (UV), visible or infrared radiation; or it may provide other types of radiation such as X-rays. The radiation source  410  may comprise, for example, an emission from an energized gas, such as a plasma, generated inside the chamber  110 , the plasma emission being generally multispectral, i.e., providing radiation having multiple wavelengths extending across a spectrum. The radiation source  410  may also be positioned outside the chamber  110  so that a radiation beam  420  may be transmitted from the source  415  through a window  425  and into the chamber  110 . The radiation source  415  may also provide radiation having predominant wavelengths, or a single wavelength, such as monochromatic light, for example, a He-Ne or Nd-YAG laser. Alternatively, the radiation source  415  may provide radiation having multiple wavelengths, such as polychromatic light, which may be selectively filtered to a single wavelength. Suitable radiation sources  415  for providing polychromatic light include Hg discharge lamps that generate a polychromatic light spectrum having wavelengths in a range of from about 180 to about 600 nanometers, arc lamps such as xenon or Hg—Xe lamps and tungsten-halogen lamps, and light emitting diodes (LED). 
     The process monitoring system  410  further comprises a radiation detector  430  for detecting radiation emanating from the chamber  110 . For example, the emanating radiation may be from a plasma emission or may be radiation  435  reflected by the substrate  105 . The radiation detector  430  may comprise a radiation sensor, such as a photovoltaic cell, photodiode, photomultiplier, or phototransistor, which provides an electrical output signal in response to an emission spectra from the plasma or a measured intensity of reflected radiation  435 , for example. The signal may comprise a change in the level of a current passing through an electrical component or a change in a voltage applied across an electrical component. A suitable system for coupling the radiation detector  430  to the chamber  110  comprises a fiberoptic cable  440  leading to the sensor of the radiation detector  430 . 
     Optionally, a lens assembly  445  may be used to focus radiation emitted by the plasma onto the radiation detector  430 , to focus a radiation beam  420  emitted by the radiation source  415  onto the substrate  105 , or to focus a radiation beam  435  reflected back from the substrate  105  onto the sensor of the radiation detector  430 . For example, for a radiation source  415  comprising a Hg-discharge lamp located outside the chamber  110 , the lens assembly  445  may comprise a plurality of convex lenses  446  that may be used to focus a radiation beam  420  from the lamp, through the window  425 , and as a beam spot  450  on the substrate  105 . The area of the beam spot  450  should be sufficiently large to provide an accurate measurement of the surface topography of the substrate  105 . The lenses may also be used to focus reflected radiation  435  back onto the sensor of the radiation detector  430  in the reverse direction or may be used to focus radiation from the energized gas to the radiation detector  430  which is especially useful when the radiation source  415  is an emission spectra from a plasma. 
     The chamber  110  and monitoring system  410  may be operated by a controller  460  that executes a computer-readable process control program on a computer system  470  comprising a central processor unit (CPU)  475 , such as for example a 68040 microprocessor, commercially available from Synergy Microsystems, Calif., or a Pentium Processor commercially available from Intel Corporation, Santa Clara, Calif., that is coupled to a memory and peripheral computer components. The memory comprises a computer-readable medium having the computer-readable program  480  embodied therein. Preferably, the memory includes a hard disk drive  485 , a removable media drive such as a floppy disk drive  490 , a ZIP™ drive, or a CD recordable drive, and random access memory  495 . The computer system further comprises a controller interface  500  which may comprise plurality of interface cards including, for example, analog and digital input and output boards, interface boards, and motor controller boards. The interface between an operator and the controller  460  can be, for example, via a display  510  and a light pen  515 . The light pen detects light emitted by the monitor with a light sensor in the tip of the light pen. To select a particular screen or function, the operator touches a designated area of a screen on the monitor and pushes the button on the light pen. Typically, the area touched changes color, or a new menu is displayed, confirming communication between the user and the controller  460 . 
     Computer-readable programs such as those stored on other memory including, for example, a floppy disk or other computer program product inserted in a floppy disk drive or other appropriate drive, or stored on the hard drive, may also be used to operate the controller  460 . The process control program  600  generally comprises process control software  605  comprising program code to operate the chamber  110  and its components, process monitoring software  610  to monitor the processes being performed in the chamber  110 , safety systems software, and other control software. The computer-readable program  600  may be written in any conventional computer-readable programming language, such as for example, assembly language, C ++ , Pascal, or Fortran. Suitable program code is entered into a single file, or multiple files, using a conventional text editor and stored or embodied in computer-usable medium of the memory of the computer system  470 . If the entered code text is in a high level language, the code is compiled, and the resultant compiler code is then linked with an object code of precompiled library routines. To execute the linked, compiled object code, the user invokes the object code, causing the CPU  475  to read and execute the code to perform the tasks identified in the program. 
       FIG. 6  is an illustrative block diagram of a hierarchical control structure of a specific embodiment of a process control program  600  according to the present invention. Using a light pen interface, a user enters a process set and chamber number into a process selector program  615  in response to menus or screens displayed on the CRT terminal. The process chamber program  605  includes program code to set the timing, gas composition, gas flow rates, chamber pressure, chamber temperature, RF power levels, support position, heater temperature, and other parameters of a particular process. The process sets are predetermined groups of process parameters necessary to carry out specified processes. The process parameters are process conditions, including without limitations, gas composition, gas flow rates, temperature, pressure, gas energizer settings such as RF or microwave power levels, cooling gas pressure, and wall temperature. In addition, parameters needed to operate the process monitoring program  610  are input by a user into the process selector program  615 . These parameters include known properties of the materials being processed, especially radiation absorption and reflection properties, such as reflectance and extinction coefficients; process monitoring algorithms that are modeled from empirically determined data; tables of empirically determined or calculated values that may be used to monitor the process; and properties of materials being processed on the substrate  105 . 
     The process sequencer program  620  comprises program code to accept a chamber type and set of process parameters from the process selector program  615  and to control its operation. The sequencer program  620  initiates execution of the process set by passing the particular process parameters to a chamber manager program  625  that controls multiple processing tasks in the process chamber  110 . Typically, the process chamber program  605  includes, among others, a substrate positioning program  630 , a gas flow control program  635 , a gas pressure control program  640 , a gas energizer control program  645 , and a heater control program  650 . Typically, the substrate positioning program  630  comprises program code for controlling chamber components that are used to load the substrate  105  onto the support  130  and optionally, to lift the substrate  105  to a desired height in the chamber  110  to control the spacing between the substrate  110  and the gas outlets  128  of the gas delivery system  120 . The gas flow control program  635  has program code for controlling the flow rates of different constituents of the process gas. The process gas control program  635  controls the open/close position of the safety shut-off valves, and also ramps up/down a gas flow controller to obtain the desired gas flow rate. The pressure control program  640  comprises program code for controlling the pressure in the chamber  110  by regulating the aperture size of the throttle valve  136  in the exhaust system  132  of the chamber  110 . The gas energizer control program  645  comprises program code for setting low and high-frequency RF power levels applied to the process electrodes in the chamber  110  and/or to the inductor coil  160 . Optionally, the heater control program  650  comprises program code for controlling the temperature of the heater element  184  used to resistively heat the support  130  and substrate  105 . 
     The process monitoring program  610  comprises program code that obtains sample or reference signals from the radiation source  415  or radiation detector  430  and processes the signal according to preprogrammed criteria. Typically, a radiation amplitude or spectrum trace is provided to the controller  460  by an analog to digital converter board in the radiation detector  430 . The process monitoring program  610  may also send instructions to the controller  460  to operate components such as the radiation source  415 , radiation detector  430 , the lens assembly  445 , filters, and other components. The program may also send instructions to the chamber manager program  605  or other programs to change the process conditions or other chamber settings. 
     To define the parameters of the process monitoring program  610 , initially, one or more substrates  105  having predetermined thicknesses of material are selected for processing. Each substrate  105  is placed at one time into the process chamber  110  and process conditions are set to process a material or an underlying material on the substrate  105 . Radiation reflected from the substrate and/or emitted from the plasma in the chamber  110  are monitored using one or more radiation detectors  430 . After a series of such traces are developed, they are examined to identify a recognizable change in a property of the trace, which is used as input for the computer program, in the form of an algorithm, a table of values, or other criteria for suitable for evaluating an event in the chamber  110  or a property of the substrate  105 . For example, the process monitoring program  610  may include program code to evaluate a signal corresponding to an intensity of reflected radiation which may be used to detect both an onset and completion of processing of the substrate  105 . As another example, the computer program  600  comprises program code to evaluate first and second signals that correspond to radiation emitted from the plasma and/or reflected from the substrate  105 . In one particular version for determining the endpoint of resist material removal, the computer program  600  may comprise program code to evalutate radiation emitted from the energized gas in the process zone  155 , particularly radiation having a wavelength of about 4835 angstroms. 
     Thus, the process monitoring program  610  may comprise program codes to monitor a process, as shown in FIG.  6 . For example, the process monitoring program  610  may comprise radiation source program code  655  to analyze the radiation from the radiation source  415 , radiation detector program code  660  to analyze an incoming signal trace provided by the radiation detector  430  and determine a process endpoint or completion of a process stage when a desired set of criteria is reached, such as when an attribute of the detected signal is substantially similar to a pre-programmed value, and signal evaluation program code  465  to detect errors or anomalies in the monitored signals. The process monitoring program  610  may also be used to detect a property of a material being processed on the substrate  105  such as a thickness, or other properties, for example, the crystalline nature, microstructure, porosity, electrical, chemical and compositional characteristics of the material on the substrate  105 . The computer program  600  may also be programmed to detect both an onset and completion of processing of the substrate  105 , for example, by detecting a change in amplitude or a rate of change of amplitude of radiation. The desired criteria are programmed into process monitoring program  610  as preset or stored parameters and algorithms. The program  610  may also include program code for modeling a trace of radiation, selecting a feature from the modeled trace or allowing a user to select the feature, storing the modeled trace or the feature, detecting a portion of an incoming signal from a radiation detector  430 , evaluating the measured signal relative to the stored trace or feature, and calling an end of a process stage of the process being performed on the substrate  105  or displaying a measured property of a material on the substrate  105 . 
     In one version, the process monitoring software comprises program code for continuously analyzing a trace of a measured amplitude of reflected radiation by drawing a box or “window” around the end portion of the trace and back in time, with signal height and time length established in the preprogrammed algorithm. A set of windows may be programmed to detect a valley or peak in the trace of the reflected intensity, trigger on an upward slope to detect a later endpoint, or to trigger on a downward slope to detect an endpoint before a valley in the trace. The first criterion is met when the signal in the trace becomes too steep and exits or moves out of the preprogrammed box (“WINDOW OUT”) or when it becomes gradual and enters the box (“WINDOW IN”). Additional windows are sequentially applied on the moving trace to generate the complete set of criteria to make a determination on whether the change in signal measured in the real time trace is an endpoint of the process, such as an onset or completion of the process, a change in the property of the material, or is only noise. The direction of entering or exiting a box may also be specified as part of the preprogrammed input criteria for operating the process monitoring program  610 . Upon detecting an onset or completion of a process, the process monitoring program signals the process chamber program  605  which sends instructions to the controller  460  to change a process condition in a chamber  110  in which the substrate  105  is being processed. 
     The data signals received by and/or evaluated by the controller  460  may be sent to a factory automation host computer (not shown). The factory automation host computer may comprise a host software program that evaluates data from several systems, platforms or chambers, and for batches of substrates or over an extended period of time, to identify statistical process control parameters. A suitable host software program comprises a WORKSTREAM™ software program available from aforementioned Applied Materials. The factory automation host computer may be further adapted to provide instruction signals to (i) remove particular substrates from the processing sequence, for example, if a substrate property is inadequate or does not fall within a statistically determined range of values, or if a process parameter deviates from an acceptable range; (ii) end processing in a particular chamber, or (iii) adjust process conditions upon a determination of an unsuitable property of the substrate or process parameter. The factory automation host computer may also provide the instruction signal at the beginning or end of processing of the substrate in response to evaluation of the data by the host software program. 
     While the present invention has been described in considerable detail with reference to certain preferred versions, many other versions should be apparent to those of ordinary skill in the art. For example, deposition of materials may be monitored for endpoint and etch resistant materials other than resist material may be removed from the substrate in the process zone. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred versions contained herein.