SUBSTRATE CLEANING APPARATUS AND METHOD

Abstract: A substrate (30) may be cleaned by exposing the substrate (30) to an energized stripping gas while maintaining the substrate (30) at a first temperature and exposing the substrate (30) to an energized passivating gas while maintaining the substrate (30) at a second temperature. In another version, the substrate (30) is stripped and passivated in separate chambers. A cleaning chamber (120) may be provided with a heater (320) to heat the top of the substrate (30)

Description: SUBSTRATE CLEANING APPARATUS AND METHOD BACKGROUND This present invention relates to cleaning of a substrate. 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 compounds and alloys. These layers may be etched to form a pattern of etched features, by providing a resist layer of photoresist and/or oxide hard mask on the substrate, and using lithography to expose and pattern the resist layer. The portions of the layers adjacent to the patterned resist features are etched to form a predefined pattern of gates, vias, contact holes, trenches, and/or metal interconnect lines. Etching is typically performed using a capacitively or inductively coupled plasma of halogen-containing gases, 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 etching process may leave (i) remnant resist, (ii) etchant byproducts, and (iii) sidewall deposits on the sidewalls of the etched features. Remnant resist are those residual resist portions that are not etched by the etchant gases, and which remain on the substrate after the etching process. The etchant byproducts may result from adsorption of the halogen-containing etchants on the etched features. The sidewall deposits are formed during the etching process, by reaction of the etchant gases, the metal-containing layers, and the resist, and by condensation of the reaction byproducts on the sidewalls of the features. One method of cleaning an etched substrate is a dry cleaning method in which a plasma of a gas is used to remove remnant resist remaining on the substrate in a stripping (or ashing) process and to remove etchant byproducts on the substrate in a passivating process. The sidewall deposits on the substrate are typically removed by wet chemical etching methods or they can be at least partially removed in a dry cleaning process. Conventional stripping methods which use a plasma of oxygen, nitrogen or water vapor, can be used to strip remnant resist from the substrate. These conventional stripping techniques are sometimes ineffective at stripping all the resist from the substrate, particularly when the polymeric resist is hardened by exposure to a plasma. For oxide hard mask resists, the oxide layer can be stripped or can be left on the substrate. Typically, remnant oxide hard mask is left on the substrate and a dielectric layer is deposited on the remnant oxide in a subsequent process step. In addition, adequate stripping processes generally compromise process throughput. The stripping process may also harden sidewall deposits making the deposits difficult to remove. In passivating techniques, the etchant byproducts on the substrate are removed or inactivated to, for example, reduce post-etch corrosion problems by using a passivating gas, such as ammonia and/or water. Conventional passivating techniques have several limitations. One limitation is that the conventional techniques which have acceptable process throughput, can prevent post-etch corrosion of the substrate only for short periods, typically ranging from about 1 to 5 hours after exposure of the substrate to ambient moisture. The short corrosion resistant period is undesirable because it necessitates that post-etch processing steps be performed within 1 to 2 hours after the substrate is first exposed to the atmosphere, resulting in a tight and inflexible production schedule. Often, the substrate cannot be etched, or if already etched, cannot be removed from the passivating and stripping chamber. Thus, there is a need to be able to clean a substrate to, for example, remove remnant resist and etchant residue on a substrate. It is further desirable to reduce post-etch corrosion. It is still further desirable to be able to clean a substrate without compromising process throughput. SUMMARY The present invention satisfies these needs. In one aspect of the present invention, a method of .cleaning a substrate comprises exposing the substrate to an energized stripping gas while maintaining the substrate at a first temperature and exposing the substrate to an energized passivating gas while maintaining the substrate at a second temperature, the passivating gas comprising at least about 20 volume % H 2 0. In another aspect of the invention, a method of cleaning a substrate comprises supporting the substrate in a first chamber, providing an energized stripping gas in the first chamber, supporting the substrate in a second chamber, and providing an energized passivating gas in the second chamber. In another aspect of the invention, a method of cleaning a substrate in a chamber comprises supporting the substrate in the chamber, maintaining the substrate at a first temperature and providing an energized stripping gas in the chamber, maintaining the substrate at a second temperature and providing an energized passivating gas in the chamber, and cooling the substrate in the chamber. In another aspect of the invention, a method of cleaning a substrate comprises exposing the substrate to an energized cleaning gas while heating the substrate from above the substrate. In another aspect of the invention, a method of processing a substrate comprises exposing the substrate to an energized process gas while heating the substrate from above and cooling the substrate from below. In another aspect of the invention, a method of processing a substrate comprises exposing the substrate to an energized process gas while heating the substrate from above at a rate of at least about 50°C/second. In another aspect of the invention, a substrate cleaning apparatus comprises a substrate support, a gas distributor, a gas energizer, a gas exhaust, and a heater above the support, whereby a substrate received on the support may be heated by the heater and cleaned by gas introduced through the gas distributor, energized by the gas energizer and exhausted by the gas exhaust. In another aspect of the invention^ substrate processing apparatus comprises a substrate support, a gas distributor, a gas energizer, a gas exhaust, and a heater above the support, whereby a substrate received on the support may be heated by the heater and cleaned by gas introduced through the gas distributor, energized by the gas energizer and exhausted by the gas exhaust and wherein the heater is capable of heating the top of the substrate at a rate of at least about 50°C/second. 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 examples of the invention. However, it should 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: Figure 1 a is a schematic sectional side view of a substrate with metal- containing layers thereon; Figure 1 b is a schematic sectional view of the substrate of Figure 1 a following etching; Figure 2 is a schematic view of a multi-chamber apparatus having an etching chamber and a cleaning chamber; Figure 3 is a schematic sectional side view of an etching chamber; Figure 4 is a schematic sectional side view of a cleaning chamber; Figure 5 is a flow chart illustrating a substrate cleaning process; Figure 6 is a flow chart illustrating another version of a substrate cleaning process; Figure 7 is a schematic sectional side view of another version of a cleaning chamber; and Figure 8 is a flow chart illustrating another version of a substrate cleaning process. DESCRIPTION The process and apparatus of the present invention are useful for processing substrates, such as semiconductor wafers, but may also be used for other processes or for processing other substrates, such as printed circuit boards, flat panel displays, and liquid crystal displays. Thus, the description represents illustrative embodiments of the invention and is not intended to limit the invention. In an exemplary process, layers on a substrate 30 may be etched by an etchant gas. Figure 1 a shows a substrate 30 having layers formed on a workpiece 35. The workpiece 35 may comprise semiconducting material, such as silicon, gallium arsenide, and the like. The layers may comprise, in one version, (i) a diffusion barrier layer 40 comprising, for example, silicon oxynitride, organic ARC, titanium, tungsten, titanium-tungsten, or titanium nitride, (ii) an electrically conductive layer 45 comprising, for example, aluminum or alloys of aluminum and copper, and optionally silicon, and (iii) an anti-reflective layer 50 comprising, for example, silicon, titanium nitride, or titanium tungsten. An oxide layer (not shown), such as Si0 2 , may also be provided below the diffusion barrier layer 40. A patterned etch-resistant layer 60 of, for example, photoresist or electron-beam resist overlies the layers. Etchant gas may be provided to etch the exposed portions of the layers to form lines, trenches, holes or vias 65 that extend through one or more of the layers, as schematically illustrated in Figure 1 b. After the etching process, remnant resist 70 along with etchant byproducts 75 remaining on the substrate 30 may be removed in one or more cleaning processes to provide a clean substrate surface for subsequent processing that is resistant to corrosion. The remnant resist 70 may comprise any protective material that is used to prevent etching of underlying layers on the substrate 30. The remnant resist 70 are the portions of the resist 60 that remain on the substrate 30 after the etching process. In one version, the remnant resist 70 comprises residual polymeric photoresist or oxide hard mask. Suitable polymeric photoresist materials are commercially available from Shipley Co., Marlboro, Massachusetts, or Tokyo Ohka Kogyo (TOK) Co., Ltd., Kawasaki, Japan. The etchant byproducts 75 on the features may comprise residual halogen radicals, such as chlorine or fluorine, that remain on the substrate 30 after etching. The etchant byproducts 75 can also comprise byproduct compounds that are formed when residual halogen radicals react with the metal in the etched layers. In one cleaning process, the remnant resist 70 is stripped using an energized stripping (or ashing) gas. In another cleaning process, the etchant byproducts 75 on the substrate 30 are passivated using an energized passivating gas. Sidewall deposits 80 on the sidewalls of the etched features may be formed during the etching process. The sidewall deposits 80 may comprise organic compounds containing (i) carbon and hydrogen, (ii) metal from the metal-containing layers, such as aluminum or titanium, and (iii) etchant gas species such as chlorine, boron and/or nitrogen. The composition and stoichiometry of the sidewall deposits 80 depend upon the chemical composition of the metal-containing layers, the resist, and the etchant gases used to etch the features. At least a portion of the sidewall deposits 80 may be removed by the stripping and/or the passivating gas. A wet chemical etching process is typically used to remove the sidewall deposits 80 remaining on the features after a dry clean process. Referring to Figure 2, the substrate 30 may be etched and cleaned in a multi-chamber apparatus 100 comprising one or more, etching chambers 1 10 for * etching the substrate 30, and one or more cleaning chambers 120 for removing remnant resist 70 and etchant byproducts 75 that remains on the substrate 30 after the etching process. The etching chamber 110, cleaning chamber 120, a transfer chamber 125, and a load lock chamber 130 are all interconnected in a vacuum sealed environment that is maintained at a low pressure to reduce contamination of the substrate 30. During processing, a robotic arm 135 transfers a substrate 30 from the load lock chamber 130 to the transfer chamber 125 and then to one of the processing chambers. The metal containing layers on the substrate 30 may be etched in a process chamber 1 10, such as for example, a DPS Metal Etch Centura chamber, schematically illustrated in Figure 3, and commercially available from Applied Materials Inc. in Santa Clara, California. The particular embodiment of the process chamber 1 10 shown herein is provided only to illustrate the invention, and should not be used to limit the scope of the invention. The chamber 1 10 comprises a support 140 within a process zone 145 in the chamber 110. A substrate 30 may be positioned on the support 140 by the robotic arm 135. The substrate 30 may be held in place during the etching process using a mechanical or electrostatic chuck 150 with grooves 155 in which a coolant gas, such as helium, is held to control the temperature of the substrate 30. During processing of the substrate, the chamber 110 may be maintained at a low pressure and process gas may be introduced into the chamber 1 10 through a gas distributor 160 peripherally disposed about the substrate 30. The process gas may be energized by a gas energizer that couples an energetic electromagnetic field into the process zone 145, such as an inductive, capacitive, or microwave field. In the version shown, an inductor coil 165 adjacent to the process chamber 1 10 forms an inductive electric field in the chamber 110 when powered by a coil power supply 170 operated using, for example, an RF voltage at a source power level that may be from about 200 Watts to about 2000 Watts. Alternatively or additionally, a capacitive electric field may be formed in the chamber 110. At least a portion of the support 140 may be electrically conductive to serve as a cathode electrode 175. The cathode electrode 175, in conjunction with sidewalls of the chamber 1 10 which may be electrically grounded to serve as an anode electrode 180, form process electrodes in the process zone 145 that may capacitively couple to energize the process gas. The cathode 175 may be powered by an electrode power supply 185 operated using, for example, an RF voltage at a power level of from about 10 to about 1000 Watts. The capacitive electric field is substantially perpendicular to the plane of the substrate 30, and accelerates the plasma, species toward the substrate 30 to provide more vertically oriented anisotropic etching of the substrate. The frequency of the RF voltage applied to the process electrodes 175,180, and/or the inductor coil 165 is typically from about 50 KHz to about 60 MHz, and more typically about 13.56 MHz. The ceiling 190 of the process chamber 1 10 can be flat or rectangular shaped, arcuate, conical, dome-shaped, or multi-radius dome-shaped. In one version, the inductor coil 165 is wrapped around the sidewall 180 of the process chamber 1 10 in the form of a multi-radius dome-shaped inductor coil having a "flattened" dome shape that provides more efficient use of plasma source power and increased plasma ion flux uniformity directly over the substrate 30 center. When capacitively generated, the plasma formed in the process zone 145 may also be enhanced using magnetically enhanced reactors (not shown), in which a magnetic field generator, such as a permanent magnet or electromagnetic coils, are used to apply a magnetic field in the process zone 145 to increase the density and uniformity of the plasma. The magnetic field may comprise a rotating magnetic field with the axis of the field rotating parallel to the plane of the substrate 30, as described in U.S. Patent No. 4,842,683, which is incorporated herein by reference in its entirety. Spent process gas and etchant byproducts are exhausted from the process chamber 1 10 through an exhaust system 195 capable of achieving a low pressure in the process chamber 110. A throttle valve 200 is provided in the exhaust for controlling the pressure in the chamber 1 10. Also, an optical endpoint measurement system (not shown) may be used to determine completion of the etching process for a specific layer by measuring, for example, the change in light emission of a particular wavelength corresponding to a detectable gaseous species or by interferometric techniques. The etchant gas composition may be selected to provide high etch rates, and highly selective etching of the layer or layers that are being etched. The etchant gases may comprise one or more of Cl 2 , BCI 3 , CCI 4 , SiCI 4 , CF 4 , NF 3 , SF 6 , Br 2 , HBr, BBr 3 , CHF 3 , N 2 or the like. In an exemplary process, the anti-reflective layer 50 is etched in energized etchant gas comprising about 90 seem Cl 2 and about 30 seem BCI 3 at a pressure of about 8 mTorr, a source power level of about 1600 Watts, a bias power level of about 145 Watts, a backside helium pressure of about 4 Torr and a cathode temperature of about 50°C. The electrically conductive layer 45 may then be then etched in energized etchant gas comprising about 80 seem Cl 2 about 5 seem BCI 3 and about 10 seem CHF 3 at a pressure of about 14 mTorr, a source power level of about 1600 Watts, a bias power level of about 150 Watts, a backside helium pressure of about 8 Torr and a cathode temperature of about 50°C. Thereafter, the diffusion barrier layer 40, and optionally a portion of the oxide layer, may be etched in energized etchant gas comprising about 30 seem Cl 2# about 5 seem BCI 2 and about 30 seem N 2 or Ar at a pressure of about 10 mTorr, a source power level of about 1600 Watts, a bias power level of about 125 Watts, a backside helium pressure of about 8 Torr and a cathode temperature of about 50 C C. After completion of etching, the substrate 30 is dechucked by, for example, a pneumatic lifting apparatus which raises lift pins (not shown) in the support 140 to raise the substrate 30 from the surface of the support 140. The robotic transport arm 135 may be inserted between the substrate 30 and the support 140 to lift the substrate 30 off the lift pins. Thereafter, the lift pins are retracted into the support 140, and the robotic arm 135 transports the substrate 30 out of the etching chamber 1 10 and into the transfer chamber 125. To remove the etchant byproducts 75 and remnant resist 70, the substrate 30 is transferred from the transfer chamber 125 to cleaning chamber 120, such as for example, an "ASP" chamber, schematically illustrated in Figure 4, and commercially available from Applied Materials Inc. in Santa Clara, California. The cleaning chamber 120 shown herein is provided only to illustrate the process of the present invention, and should not be used to limit the scope of the invention, because other cleaning chambers can also be used to remove etchant byproducts 75 or strip remnant resist 70 from the substrate 30. The substrate 30 is placed on a support 210 by the robotic arm 135, and optionally held in place during processing by a mechanical or electrostatic chuck 212. In the cleaning chamber 120, an energized cleaning gas is formed to clean the substrate 30 held on the support 210 in a process zone 215. The support 210 supports the substrate 30 in the process zone 215. Within or below the support 210, a heat source, such as infrared lamps 220, can be used to heat the substrate 30 as will be described. The cleaning gas may be introduced through a gas distributor 222 into a remote plasma generation zone 225 in a remote chamber 230. By "remote" it is meant that the center of the remote chamber 230 is at a fixed upstream distance from the center of a process zone 215 in the cleaning chamber 120. In the remote chamber 230, the cleaning gas is activated by coupling microwave or RF energy into the remote chamber 230, to energize the cleaning gas and cause ionization or dissociation of the cleaning gas components, prior to its introduction through a diffuser 235, such as a showerhead diffuser, into the process zone 215. Spent cleaning gas and byproducts may be exhausted from the cleaning chamber 120 through an exhaust system 240 capable of achieving a low pressure in the cleaning chamber. A throttle valve 245 in the exhaust 240 is used for maintaining a chamber pressure at from about 300 to about 3000 mTorr. In the version illustrated in Figure 4, the remote chamber 230 comprises a tube shaped cavity containing at least a portion of the remote plasma zone 225. Flow of cleaning gas into the remote chamber 230 is adjusted by a mass flow controller or gas valve 250. The remote chamber 230 may comprise walls made of a dielectric material such as quartz, aluminum oxide, or monocrystalline sapphire that is transparent to microwaves and is non-reactive to the cleaning gas. A microwave generator 255 is used to couple microwave radiation to the remote plasma zone 225 of the remote chamber 230. A suitable microwave generator 255 is an "ASTEX" Microwave Plasma Generator commercially available from the Applied Science & Technology, Inc., Woburn, Massachusetts. Typically, the microwave generator assembly 255 comprises a microwave applicator 260, a microwave tuning assembly 265, and a magnetron microwave generator 270. The microwave generator may be operated at a power level of about 200 to about 3000 Watts, and at a frequency of about 800 MHz to about 3000 MHz. In one version, the remote plasma zone 225 is sufficiently distant from the process zone 215 to allow recombination of some of the dissociated or ionized gaseous chemical species. The resultant reduced concentration of free electrons and charged species in the activated cleaning gas minimizes charge-up damage to the active devices on the substrate 30, and provides better control of the chemical reactivity of the activated gas formed in the remote plasma zone 225. In one version, the center of the remote plasma zone 225 is maintained at a distance of at least about 50 cms from the center of the process zone 215. Remnant resist 70 may be removed from the substrate 30 in a stripping (or ashing) process conducted in the cleaning chamber 120. Stripping gases may comprise one or more of 0 2 , N 2 , H 2 0, 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 water vapor, nitrogen gas, 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. A preferred stripping gas composition comprises oxygen and nitrogen in a volumetric flow ratio of about 6:1 to about 200:1 , and more preferably from about 10:1 to about 12:1 . For a 5-liter process chamber 120, a suitable gas flow rate comprises 3000 to 3500 seem of 0 2 and 300 seem of N 2 . In one version, a stripping gas comprises about 3500 seem 0 2 , about 200 seem N 2 and optionally about 300 seem H 2 0 energized at a power level of about 1400 Watts and introduced into the cleaning chamber 120 at a pressure of about 2 Torr for about 15 seconds. In one version, the water vapor content in the stripping gas should be less than about 20% by volume of the combined oxygen and nitrogen gas content to provide adequate stripping rates. A suitable ratio of the volumetric water vapor flow V H20 to the combined volumetric flow of oxygen and nitrogen (V 02 + V N2 ) is from about 1 :4 to about 1 :40, and more preferably about 1 :10. When the remnant resist comprises oxide hard mask, suitable stripping gases are gases capable of stripping oxide, such as halogen containing gases, including CF 4 , C 2 F 6 , CHF 3 , C 3 H 2 F 6 , C 2 H 4 F 2 and HF. The substrate 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 45 seconds. A single stripping step may be performed or multiple stripping steps may be performed, as discussed in U.S. Patent No. 5,545,289, which is incorporated herein by reference in its entirety. The cleaning chamber may also be used to passivate the substrate 30 to remove corrosive etchant byproducts 75 therefrom or to prevent the formation of corrosive or contaminant materials on the etched substrate 30. Passivating gases may comprise one or more of H 2 0, NH 3 , H 2 0 2 , 0 2 , N 2 , CF 4 , C 2 F 6 , CHF 3 , C 3 H 2 F 6 , C 2 H 4 F 2 , CH 3 F. In one version, any gas or vapor containing hydrogen can serve as the passivating gas, including hydrogen, water vapor, ammonia, methanol, hydrogen sulfide, and mixtures thereof. In another version, the passivating gases include (i) ammonia and oxygen, or (ii) water vapor, with optional oxygen and nitrogen. When the passivating gas comprises ammonia and oxygen, the volumetric flow ratio of ammonia to oxygen is preferably from about 1 :1 to about 1 :50, more preferably from about 1 :5 to about 1 :20, and most preferably about 1 :10. For a 5-liter capacity chamber 120, a preferred gas flow comprises 300 seem NH 3 and 3000 seem 0 2 . Alternatively, a passivating gas comprising at least about 80 volume % H 2 O, and preferably about 100 volume % H 2 0, can be used to passivate the etchant byproducts 75. In one version, a passivating gas comprises about 500 seem H 2 O energized at a power level of about 1400 Watts and introduced into the cleaning chamber 20 at a pressure of about 2 Torr for about 15 seconds. When a bubbler is used, an inert carrier gas such as argon or helium can be passed through the bubbler to transport water vapor to the vacuum chamber. Optionally, oxygen, nitrogen or other additive can be added to the passivating gas to enhance passivating. In this version, the passivating gas comprises at least about 20 volume % H 2 0. The effect of the oxygen and nitrogen addition depends on the ratio of the volumetric flow of water vapor (V H20 ) to the combined volumetric flow of oxygen and nitrogen (V 02 + V N2 ). A suitable volumetric ratio of water vapor flow V H20 to combined volumetric flow of oxygen and nitrogen (V 02 + V N2 ) for use as a passivating gas is at least about 1 :2, more preferably from about 1 :2 to about 2: 1 , and most preferably about 1 : 1 . As with the stripping process and as discussed in U.S. Patent No. 5,545,289, the passivation may be either a single step or multiple steps. In one version, the substrate is exposed to the passivating gas for a period of time of from about 10 seconds to about 100 seconds, and more preferably for about 45 seconds. In one version, a multi-cycle passivation process, for example a three cycle process, has been discovered to be particularly effective in preventing corrosion. It has been discovered that a process comprising a relatively low temperature strip and a relatively high temperature passivation provides improved remnant resist 70 and etchant byproduct 75 removal and improved corrosion resistance. The extended corrosion resistance period is desirable so that the partially processed substrate can be stored while waiting for the next processing step. Conventional passivating processes are typically unable to provide these extended corrosion resistant periods. In addition, the low temperature strip and high temperature passivation lessens the hardening of sidewall deposits 80 thereby making them easier to remove in a subsequent wet chemical etch process which increases process throughput. Accordingly, in one version of the present invention, a substrate 30 is stripped at a first temperature and passivated at a second temperature in the cleaning chamber 120. The stripping and passivating may occur in any order and with any number of intermediate steps and with, any number of repetitions. As shown in Figure 5, in one version, the etched substrate 30 may be cleaned in a cleaning chamber by maintaining the temperature of the substrate 30 at a first temperature and then heating the substrate to a second temperature for passivation. In one version, the heat source 220 in the support 210 maintains the substrate at a first temperature less than about 150°C, more preferably from about 20°C to about 100°C, and most preferably about 50°C, during stripping. Thereafter, the heating is increased to maintain the substrate 30 at a second temperature above about 1 50 C C, more preferably above about 200°C, more preferably from about 200°C to about 350°C, and most preferably about 250°C during passivation. In order to increase the substrate fabrication efficiency, the cleaning process throughput of the invention of Figure 5, may be increased. By cleaning process throughput it is meant the number of substrates that can be processed in a certain amount of time. The heat source 220 in the support 210 of the cleaning chamber 120 should be sufficiently powerful to minimize the time required to heat the substrate 30 from the first temperature to the second temperature without adversely affecting the processing of the substrate 30. In one version, the heat source 220 in the support is effective in heating the substrate 30 at a rate of at least 10°C/sec. The throughput may also be increased by providing a separate cooling chamber to allow for cooling of the cleaned substrate 30 while another substrate is being cleaned in the cleaning chamber 120. Another version of the cleaning process useful in further improving throughput is shown in Figure 6 where two cleaning chambers are provided for cleaning a substrate 30. The two cleaning chambers are maintained at different temperatures. For example, a first cleaning chamber may be maintained at a desired stripping temperature and a second cleaning chamber may be maintained at a desired passivating temperature. By providing two cleaning chambers at different temperatures, the step of heating the substrate 30 from the first temperature to the second temperature in a chamber is eliminated thereby reducing the processing time for the substrate. In addition, the cleaning process throughput is further reduced because one substrate may be passivated while another substrate is being stripped. As shown in Figure 7, another version of a cleaning chamber 120 has been developed to even further improve process throughput and stripability. The cleaning chamber 120 of Figure 7 comprises a heater 320 that is positioned to directly heat the top of the substrate 30. For example, the heater 320 may be positioned directly above the substrate 30 (as shown) or may be positioned around the substrate (not shown). In one version, the heater 320, which may comprise one or more infrared lamps in one or more lamp modules that is positionable in or on the cleaning chamber 120 to heat the top surface of the substrate 30. In one version, the heating source 220 is capable of heating the top surface of the substrate 30 at a rate of at least 50°C/second, and more preferably of at least 100°C/second. The support 210 may comprise, in the version shown in Figure 7, a cooled base 330. For example, the base 330 may be provided with channels 335 through which heat transfer fluid from a heat exchanger may be passed to control the temperature of the base 330 and of a substrate 30 on the support 210. In one version, the base 330 is capable of cooling the substrate 30 at a rate of at least about 50°C/second, and more preferably at least about 100°C/second. Alternatively, grooves in which a coolant gas, such as helium, may be held to control the temperature of the substrate 30 can be provided in an electrostatic chuck. As shown in Figure 8, an etched substrate 30 may be transferred to the cleaning chamber 120 of Figure 7 for cleaning. The heater 320 may be operated at a first level to heat and maintain the substrate 30 at a first temperature, which may be, for example, less than about 150°C, more preferably from about 20°C to about 100°C, and most preferably about 50°C, to strip the substrate 30. Thereafter, the heater 320 may be operated at a second level to heat and maintain the substrate 30 at a second temperature, which may be, for example, above about 150 C C, more preferably above about 200°C, more preferably from about 200°C to about 350°C, and most preferably about 250°C to passivate the substrate. Following passivation the base 330 may be used to cool the substrate in the cleaning chamber 120 to a temperature of about 70°C for further processing or storage of the substrate 120. Alternatively, a separate cooling chamber may be provided. The cleaning chamber 120 of Figure 7 is able to heat the top of the substrate 30 rapidly and able to cool the substrate 30 rapidly. Thus, a single chamber may be used to strip and passivate a substrate at different temperatures and still improve throughput over conventional techniques. This unexpected result is believed to be due to the arrangement of the heater 320 and the base 330 in the cleaning chamber 120 shown in Figure 7. The cool down period in the cleaning chamber 120 is less than the cool down period in conventional cooling chambers. This is believed to be due to the rapid cooling ability of the base 330 and to a synergistic temperature effect of the combined top heating and bottom cooling. When a substrate 30 is heated from below, the bottom of the substrate must be at a higher temperature than the desired processing temperature in order to sufficiently heat the top of the substrate 30 to the desired temperature. In contrast, when the substrate 30 is heated from above, as in the version of Figure 7, the top surface is at a higher temperature than the bottom surface. Thus, when the top surface reaches the desired temperature, the bottom of the substrate 30 is less than the desired temperature. As a result, there is less heat to dissipate from the substrate 30 heated with a heater 320 above the substrate 30. This effect may be enhanced by cooling the bottom of the substrate 30 during processing thereby processing a wafer having a large temperature gradient from its top to its bottom. Although the present invention has been described in considerable detail with regard to the preferred embodiments thereof, other embodiments are possible. For example, the order of stripping and passivating may be reversed or multiple cleaning chambers with top heating and bottom cooling may be provided in series to perform a process similar to the process of Figure 6 but with the cooling chamber eliminated. Other similar modifications can be made without departing from the scope of the invention. Therefore, the appended claims should not be limited to the descriptions of the preferred embodiments contained herein.

Claims: What is claimed is: 1 . A method of cleaning a substrate, the method comprising: exposing the substrate to an energized stripping gas while maintaining the substrate at a first temperature; and exposing the substrate to an energized passivating gas while maintaining the substrate at a second temperature, the passivating gas comprising at least about 20 volume % H 2 0. 2. A method according to claim 1 wherein the stripping gas comprises one or more of 0 2 , N 2 , H 2 0, 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 in a volumetric flow rate selected to remove remnant resist from the substrate. 3. A method according to claim 1 wherein the passivating gas further comprises one or more of NH 3 , H 2 0 2 , 0 2 , N 2 , CF 4 , C 2 F 6 , CHF 3 , C 3 H 2 F 6 , C 2 H 4 F 2 , or CH 3 F in a volumetric flow rate selected to remove etchant byproducts from the substrate. 4. A method according to claim 1 wherein the second temperature is higher than the first temperature. 5. A method according to claim 1 wherein the first temperature is below about 1 50°C. 6. A method according to claim 1 wherein the second temperature is above about 1 50°C. 7. A method according to claim 1 wherein the first temperature is below about 1 50°C and the second temperature is above about 150°C. 8. A method according to claim 1 wherein the first temperature is from about 20°C to about 100°C and the second temperature is from about 200°C to about 350°C. 9. A method according to claim 1 wherein the passivating gas comprises at least about 80 volume % H 2 0. 10. A method of cleaning a substrate, the method comprising: supporting the substrate in a first chamber; providing an energized stripping gas in the first chamber; supporting the substrate in a second chamber; and providing an energized passivating gas in the second chamber. 1 1 . A method according to claim 10 wherein the stripping gas comprises one or more of 0 2 , N 2 , H 2 0, 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 in a volumetric flow ratio selected to remove remnant resist from the substrate. 12. A method according to claim 10 wherein the passivating gas comprises one or more of H 2 0, NH 3 , H 2 0 2 , 0 2 , N 2 , CF 4 , C 2 F e , CHF 3 , C 3 H 2 F 6 , C 2 H 4 F 2 , or CH 3 F in a volumetric flow ratio selected to remove etchant byproducts from the substrate. 13. A method according to claim 10 wherein the substrate is maintained at a first temperature in the first chamber and at a second temperature in the second chamber. 14. A method according to claim 13 wherein the first temperature is below about 1 50°C. 1 5. A method according to claim 13 wherein the second temperature is above about 150°C. 16. A method according to claim 13 wherein the first temperature is below about 1 50°C and the second temperature is above about 150°C. 17. A method according to claim 13 wherein the first temperature is from about 20°C to about 100°C and the second temperature is from about 200°C to about 350°C. 18. A method according to claim 10 wherein the stripping gas comprises oxygen and nitrogen. 19. A method according to claim 18 wherein the stripping gas comprises H 2 0. 20. A method according to claim 10 wherein the passivating gas comprises at lea'st about 20 volume % H 2 0. 21 . A method of cleaning a substrate in a chamber, the method comprising: supporting the substrate in the chamber; maintaining the substrate at a first temperature and providing an energized stripping gas in the chamber; maintaining the substrate at a second temperature and providing an energized passivating gas in the chamber; and cooling the substrate in the chamber. 22. A method according to claim 21 wherein the stripping gas comprises one or more of 0 2 , N 2 , H 2 0, 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 in a volumetric flow rate selected to remove remnant resist from the substrate. 23. A method according to claim 21 wherein the passivating gas comprises one or more of H 2 0, NH 3 , H 2 0 2 , 0 2 , N 2 , CF 4 , C 2 F 6 , CHF 3 , C 3 H 2 F 6 , C 2 H 4 F 2 , or CH 3 F in a volumetric flow rate selected to remove etchant byproducts from the substrate. 24. A method according to claim 21 wherein the substrate is cooled to a temperature below about 150°C. 25. A method according to claim 21 wherein the second temperature is above about 150°C. 26. A method according to claim 21 wherein the first temperature is below about 150°C and the second temperature is above about 150 C C. 27. A method of cleaning a substrate, the method comprising: exposing the substrate to an energized cleaning gas while heating the substrate from above the substrate. 28. A method according to claim 27 wherein the cleaning gas comprises stripping gas comprising one or more of 0 2 , N 2 , H 2 0, 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 in a volumetric flow rate selected to remove remnant resist from the substrate. 29. A method according to claim 27 wherein the cleaning gas comprises passivating gas comprising one or more of H 2 0, NH 3 , H 2 0 2 , 0 2 , N 2 , CF 4 , C 2 F 6 , CHF 3 , C 3 H 2 F 6 , C 2 H 4 F 2 , or CH 3 F in a volumetric flow rate selected to remove etchant byproducts from the substrate. 30. A method according to claim 27 wherein the substrate is maintained at the first and second temperatures by heating the substrate from above the substrate. 31 . A method of processing a substrate, the method comprising: exposing the substrate to an energized process gas while heating the substrate from above and cooling the substrate from below. 32. A method according to claim 31 wherein the substrate is heated from above by a heater capable of heating the top of the substrate at a rate of at'least about 50°C/second. 33. A method according to claim 31 wherein the substrate is heated from above by a heater capable of heating the top of the substrate at a rate of at least about 1 50°C/second. 34. A method of processing a substrate, the method comprising: exposing the substrate to an energized process gas while heating the substrate from above at a rate of at least about 50°C/second. 35. A method according to claim 34 wherein the substrate is heated at a rate of at least about 1 50°C/second. 36. A substrate cleaning apparatus comprising: a substrate support; a gas distributor; a gas energizer; a gas exhaust; and a heater above the support, whereby a substrate received on the support may be heated by the heater and cleaned by gas introduced through the gas distributor, energized by the gas energizer and exhausted by the gas exhaust. 37. An apparatus according to claim 36 wherein gas distributor is adapted to introduce stripping gas. 38. An apparatus according to claim 37 wherein the stripping gas comprises one or more of 0 2 , N 2 , H 2 0, 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 and wherein the gas distributor is adapted to introduce the stripping gas at a volumetric flow rate selected to remove remnant resist from the substrate. 39. An apparatus according to claim 36 wherein gas distributor is adapted to introduce passivating gas. 40. An apparatus according to claim 39 wherein the passivating gas comprises one or more of H 2 0, NH 3 , H 2 0 2 , 0 2 , N 2 , CF 4 , C 2 F 6 , CHF 3 , C 3 H 2 F 6 , C 2 H 4 F 2 , or CH 3 F and wherein the gas distributor is adapted to introduce the passivating gas at a volumetric flow rate selected to remove etchant byproducts from the substrate. 41 . An apparatus according to claim 36 wherein the heater is capable of heating the top of the substrate at a rate of at least about 50°C/second. 42. An apparatus according to claim 36 wherein the heater is capable of heating the top of the substrate at a rate of at least about 150°C/second. 43. An apparatus according to claim 36 wherein the support comprises channels adapted to contain heat transfer fluid. 44. An apparatus according to claim 36 wherein the support is capable of cooling the substrate at a rate of at least about 50°C/second. 45. An apparatus according to claim 36 wherein the heater comprises one or more infrared lamps. 46. A substrate processing apparatus comprising: a substrate support; a gas distributor; a gas energizer; a gas exhaust; and a heater above the support, whereby a substrate received on the support may be heated by the heater and cleaned by gas introduced through the gas distributor, energized by the gas energizer and exhausted by the gas exhaust and wherein the heater is capable of heating the top of the substrate at a rate of at least about 50°C/second. 47. An apparatus according to claim 46 wherein the heater is capable of heating the top of the substrate at a rate of at least about 150°C/second. 48. An apparatus according to claim 46 wherein the support comprises channels adapted to contain heat transfer fluid. 49. An apparatus according to claim 46 wherein the support is capable of cooling the substrate at a rate of at least about 50°C/second. 50. An apparatus according to claim 44 wherein the heater comprises one or more infrared lamps.

Inventors: LI QI, MA DIANA, YAN CHUN, LI, QI, MA, DIANA, YAN, CHUN
Applicants: APPLIED MATERIALS INC, APPLIED MATERIALS, INC.
Application year: 2001
Main classification: H01L21
IPC codes: G03F7, H01L21