Patent Publication Number: US-2023151487-A1

Title: Methods of reducing chamber residues

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/857,755, filed Apr. 24, 2020, which claims benefit of U.S. provisional patent application Ser. No. 62/848,337, filed May 15, 2019, each of which is herein incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     Field 
     Embodiments of the present disclosure generally relate to methods and apparatus for minimizing the formation of residues on chamber walls and hardware components during substrate deposition processes, such as hardware components of process chambers during deposition of thin films on semiconductor substrates. 
     Description of the Related Art 
     Plasma-enhanced chemical vapor deposition (PECVD) can be used to form one or more thin films on a substrate for semiconductor device fabrication. As semiconductor devices demand higher memory density due to their continuously decreasing dimensions and the utilization of multi-stack structures, control of film properties of the semiconductor devices is of increasing concern. A major contributor of defects in the film formation process is the presence of residues in the deposition chamber, particularly residues deposited in undesired areas such as the chamber bottom and slit valve areas. The presence of such residues in the chamber not only results in defective semiconductor devices, but also increases cleaning time between deposition cycles, thus reducing overall yield throughput and increasing manufacturing costs. Factors contributing in the buildup of chamber residues include errant dispersion of plasma throughout the chamber and the formation of undesired parasitic plasma. 
     Accordingly, what is needed in the art are improved methods and apparatus for minimizing the deposition and buildup of residues on chamber components. 
     SUMMARY 
     In one embodiment, a method for forming a film comprises introducing a first gas into a process volume of a process chamber at a first flow rate, generating a plasma from the first gas to form a film on a substrate disposed on a substrate support assembly, and introducing a second gas into the process volume at a second flow rate. The second gas is introduced into a lower region of the process volume via a gas introduction port disposed below the substrate support assembly. A ratio of the first flow rate to the second flow rate is between about 0.5 and about 3. 
     In one embodiment, a method for forming a film comprises introducing a first gas into a process volume of a process chamber at a first flow rate, generating a plasma from the first gas to form a film on a substrate disposed on a substrate support assembly, and introducing a second gas into the process volume at a second flow rate that accounts for 40% of a total flow within the process chamber. The second gas is introduced into a lower region of the process volume via a gas introduction port disposed below the substrate support assembly. 
     In one embodiment, a method for forming a film comprises introducing a first gas into a process volume of a process chamber at a first flow rate, generating a plasma from the first process gas to form a film on a substrate disposed on a substrate support assembly, and introducing oxygen gas into the process volume at a second flow rate that accounts for at least 40% of a total flow in the process chamber. A ratio of the first flow rate to the second flow rate is between about 0.5 and about 3. The oxygen gas is introduced into a lower region of the process volume via a gas introduction port disposed below the substrate support assembly and facilitates a spontaneous combustion reaction to consume unreacted species of the plasma below the substrate support assembly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only exemplary embodiments and are therefore not to be considered limiting of its scope, and may admit to other equally effective embodiments. 
         FIG.  1 A  illustrates a cross-sectional schematic view of an exemplary process chamber according to one embodiment of the disclosure. 
         FIG.  1 B  illustrates a cross-sectional schematic view of an exemplary process chamber according to one embodiment of the disclosure. 
         FIG.  2    illustrates a flow diagram of a method according to one embodiment described herein. 
     
    
    
     To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation. 
     DETAILED DESCRIPTION 
     The present disclosure relates to systems and methods for reducing the formation of hardware residue and minimizing secondary plasma formation during substrate processing in a process chamber. The process chamber may include a gas distribution member configured to flow a first gas into a process volume and generate a plasma therefrom. A second gas is supplied into a lower region of the process volume to reduce errant dispersion of the plasma, reduce the presence of active radical species below the wafer plane, and actively clean the lower region. Further, an exhaust port is disposed in the lower region to remove excess gases or by-products from the process volume during or after processing. 
       FIG.  1 A  is a schematic cross-sectional view of a process chamber  100  according to one embodiment. The process chamber  100  may be a plasma enhanced chemical vapor deposition (PECVD) chamber suitable for depositing a chemical vapor deposition film (CVD) film on a substrate, such as substrate  154 . Examples of process chambers that may be adapted to benefit as described herein include the PRODUCER® CVD process apparatus and PRECISION™ process apparatus commercially available from Applied Materials, Inc., Santa Clara, Calif. Other suitably configured process chambers, including those from other manufacturers or for other applications may also be used in accordance with the embodiments described herein. For example, embodiments described herein may be used to benefit etch chambers, ion implantation chambers, and stripping chambers, among others. 
     The process chamber  100  may be used for various plasma processes, including deposition and removal processes. In one aspect, the process chamber  100  is used to perform CVD using one or more precursor gases with or without radio frequency (RF) power sources. In another embodiment, the process chamber  100  is used for PECVD processes. 
     The process chamber includes a chamber body  102  having sidewalls  106  and a chamber bottom  108  at least partially defining a process volume  120 . The process chamber  100  further includes a lid assembly  110  and a substrate support assembly  104 . The substrate support assembly  104  is disposed in the process volume  120  and is configured to support a substrate  154  thereon during processing. The lid assembly  110  is coupled to the chamber body  102  at an upper end thereof, enclosing the substrate support assembly  104  within the process volume  120 . The substrate  154  is transferred to the process volume  120  through a slit valve opening  126  formed in the sidewall  106 . The slit valve opening  126  is selectively opened and closed to enable access to the process volume  120  by a substrate transfer robot (not shown) for substrate transfer. In some embodiments, one or more process gases and cleaning gases may be introduced into the process volume via the slit valve opening  126 . 
     An electrode  109  is disposed adjacent to the chamber body  102  and separates the chamber body  102  from other components of the lid assembly  110 . The electrode  109  may be part of the lid assembly  110 , or may be a separate sidewall electrode. An isolator  107 , which may be formed of a dielectric material such as a ceramic material or metal oxide material, for example aluminum oxide and/or aluminum nitride, contacts the electrode  109  and separates the electrode  109  electrically and thermally from other components of the lid assembly  110  and from the chamber body  102 . In one embodiment, the electrode  109  is sandwiched between opposing isolators  107  such that the isolators  107  are in contact with the sidewalls  106  and the lid assembly  110 . 
     The lid assembly  110  includes a gas distribution member  112  having a plurality of openings  118  for flowing one or more process gases, precursors, or cleaning gases into the process volume  120 . The gases are supplied to the process chamber  100  from a first gas source  111  via a conduit  114 , and the gases are flowed into a mixing plenum  116  prior to flowing into the process volume  120  via the openings  118 . In one example, one or more inert gases may be flowed into the process volume  120  during deposition or cleaning processes, such as argon, nitrogen, oxygen, helium, and the like. Other suitable examples of precursor gases that may be flowed into the process volume  120  during deposition include propene, ammonia, tetraethyl orthosilicate, silane, and the like. The one or more gases are introduced into the process volume  120  at a total flow rate of between about 1000 standard cubic centimeters per minute (sccm) and about 20000 sccm, such as between about 5000 sccm and about 15000 sccm, such as about 10000 sccm. 
     The gas distribution member  112  is further coupled to a power source  142 , such as a radio frequency (RF) power source, configured to provide a power to the gas distribution member  112 . In one embodiment, a continuous or pulsed RF power is utilized to form a plasma in the process volume  120 . In other embodiments, a continuous or pulsed DC power is utilized to form a plasma in the process volume  120 . The power source  142  provides a power of between about 100 Watts and about 3000 Watts at a frequency between about 50 kHz and about 13.6 MHz. 
     In operation, the process gases or precursors are supplied to the process volume  120  from the first gas source  111  and flow through the plurality of openings  118  in the gas distribution member  112 . A plasma is formed in the process volume  120  by activation of the process gases or precursors by RF power supplied by the power source  142  to the gas distribution member  112 . The plasma forms films on, or etches films from, the substrate  154  that is supported by the substrate support assembly  104 . 
     The substrate support assembly  104  is formed from a metallic or ceramic material, such as a metal oxide material, a metal nitride material, metal oxynitride material, or any combination thereof. For example, the substrate support assembly  104  is formed of an aluminum-containing material, an aluminum nitride-containing material, an aluminum oxide-containing material, or an aluminum oxynitride-containing material. The substrate support assembly  104  includes a substrate support surface  180  disposed on a first surface thereof, parallel to a second surface of the substrate support assembly  104  and facing the lid assembly  110 . The substrate support surface  180  is configured to directly support the substrate  154  during processing. The substrate support assembly  104  is coupled to a lift mechanism  147  through a shaft  144 , which extends through an opening  146  in the chamber bottom  108 . The lift mechanism  147  enables the substrate support surface  180  to be moved vertically through the process volume  120  between a lower transfer position and one or more raised process positions. 
     An electrostatic chuck (ESC)  130  is disposed in the substrate support assembly  104 . The electrostatic chuck  130  includes one or more electrodes  122 . The electrodes may be a plate, a perforated plate, a mesh, a wire screen, or any other distributed arrangement. The one or more electrodes  122  are coupled to an electrode power source  124  to provide power to the electrodes  122  and facilitate chucking of the substrate  154  to the substrate support surface  180  during processing of the substrate  154 . In one embodiment, the electrode power source  124  applies a DC voltage to the electrodes  122  for chucking. The electrode power source  124  is capable of producing either or both of continuous or pulsed power. 
     In some embodiments which can be combined with other embodiments, the substrate support assembly  104  includes additional electrodes (not shown) for use in combination with the electrode  109  to generate plasma during the processing of the substrate  154 . The use of the electrode  109  and the additional electrodes disposed in either the substrate support assembly  104  or proximate the substrate support assembly  104  to generate plasma may have a variety of embodiments. For example, an RF field may be created by driving at least one of the electrode  109  and the additional electrodes with drive signals to facilitate formation of a capacitive plasma within the process volume  120 . In one embodiment, the additional electrodes are used in combination with the electrode  109  to bias the plasma in the process volume  120 . The electrode power source  124  provides an RF power to the electrodes  122  or additional electrodes of up to about 1000 W at a frequency of about 13.56 MHz. However, it is contemplated that other frequencies and powers may be provided depending on the application. For example, the electrode power source  124  may provide multiple frequencies, such as 13.56 MHz and 2 MHz. 
     The substrate support assembly  104  further includes a heater apparatus  140  disposed therein and coupled to a heater power source  148 . The heater apparatus  140  is used to heat the substrate  154  and may incidentally heat the process volume  120  during the processing of the substrate  154 . In one embodiment, the heater apparatus  140  is a resistive heater. In another embodiment, the heater apparatus  140  is a channel adapted to receive a flow of heated or cooled fluid, such as air, nitrogen, helium, water, glycol, or the like, therethrough to conduct heat to the substrate  154 . 
     One or more gas introduction ports  162  are disposed through the chamber body  102  below the substrate support assembly  104  and are coupled to a second gas source  113 . In one embodiment, the one or more gas introduction ports  162  are formed through the sidewalls  106  adjacent to a lower region  150  of the process volume  120 . In another embodiment, the one or more gas introduction ports  162  are formed through the chamber bottom  108  separate from the opening  146 , as depicted in  FIG.  1 A . In yet another embodiment, the opening  146  itself functions as a gas introduction port that may be utilized alternatively to or in combination with the one or more gas introduction ports  162 . 
     The second gas source  113  supplies one or more process gases, precursors, cleaning gases, or barrier gases into a lower region  150  of the process volume  120  through the gas introduction ports  162  and/or opening  146 . Alternatively or additionally, one or more gases may be supplied into the lower region  150  via the slit valve opening  126 . The second gas source  113  controls the type of gas and the flow rate of the gas into the process volume  120 , and more specifically, to the lower region  150 . In one embodiment, the second gas source  113  supplies a purge gas into the lower region  150 . The purge gas may be an inert gas. Additionally, the purge gas may be formed of a species having relatively low reactivity (e.g., a non-reactive species) relative to the gases supplied by the first gas source  111  and having a dissociation energy greater than that of diatomic argon. For example, the purge gas may be formed of a species having a dissociation energy greater than about 4.73 kJ mol−1 . For example, the purge gas may be formed of any one of helium, argon, oxygen, nitrogen, hydrogen, ammonia, or any combination thereof. In such an example, ionization of the second gas in the lower region  150  is mitigated or prevented. 
     An exhaust port  152  is in fluid communication with the process volume  120  and extends through the chamber body  102 . In one embodiment, the exhaust port  152  is disposed through a sidewall  106 . It is contemplated that the exhaust port  152  may be an annular pumping channel surrounding the process volume  120 , or a non-annular pumping port adjacent the process volume  120 . In another embodiment, the exhaust port  152  is disposed through the chamber bottom  108 . The exhaust port  152  is coupled to a vacuum pump  156  to remove excess process gases or by-products from the process volume  120  during or after processing of the substrate  154 . 
     In operation, process gases or purge gases are supplied to a lower region  150  below the substrate support assembly  104  from the second gas source  113  via the gas introduction ports  162 , the opening  146 , and/or the slit valve opening  126 . The process gases or purge gases are supplied to the lower region  150  by the second gas source  113  while a plasma is formed above the substrate support assembly  104  to deposit one or more films on the substrate  154 . Thus, the first gas source  111  and the second gas source  113  simultaneously supply gases to the process volume  120 , albeit from different regions of the process chamber  100 . 
     In certain embodiments which can be combined with other embodiments, the gas species supplied by the second gas source  113  react with the activated plasma species to form byproducts that are exhausted through the exhaust port  152 . This may occur, for example, if the activated plasma species diffuses into the lower region  150 , or if the second gas diffuses into an upper region of the process region  150 . In certain embodiments, the gas species supplied by the second gas source  113  has no (or minimal) reactivity with the activated plasma species, but rather dilutes the activated plasma species in the process volume  120  (or in the lower region  150 ) before being exhausted through the exhaust port  152 . In such an example, the dilution mitigates unwanted deposition in the lower region  150 . 
       FIG.  1    B is a schematic cross-sectional view of the process chamber  100  according to another embodiment. The process chamber  100  depicted in  FIG.  1    B is substantially similar to the embodiments described above but further includes a radiation shield  182  disposed below the substrate support assembly  104 . The radiation shield  182  is utilized to modulate radiation heat loss at a bottom surface of the substrate support assembly  104  to compensate for any temperature non-uniformities of the substrate support assembly  104 , and thus, a substrate  154  positioned thereon. 
     The radiation shield  182  includes a radiation shaft  184  and a radiation plate  186 . The radiation shaft  184  is a tubular or cylindrical member surrounding the shaft  144 . A space  176  is formed between the radiation shaft  184  and the shaft  144  through which one or more gases supplied from the second gas source  113  may be flowed. The radiation shaft  184  further supports the radiation plate  186  and is formed of any suitable material for substrate processing, such as a quartz material. 
     The radiation plate  186  is a planar and disc-shaped plate that has substantially similar lateral dimensions to the substrate support assembly  104 . For example, the radiation plate  186  has a diameter that is substantially similar to a diameter of the substrate support assembly  104 . The radiation plate includes a central hole through which the shaft  144  extends. The radiation plate  186  may further include one or more holes disposed radially outward of the shaft  144  to enable lift pins (not shown) to actuate therethrough. In one embodiment, the radiation plate  186  is formed of an aluminum oxide or aluminum nitride material. 
     In operation, the radiation shield  182  may direct one or more gases supplied from the second gas source  113  through the space  176 , along the bottom surface of the substrate support assembly  104 , and towards the sidewalls  106 . For example, the radiation shield  182  may control the flow of the one or more gases such that the gases flow radially outward along the bottom surface of the substrate support assembly  104  and towards the sidewalls  106  in a flow path substantially parallel to the substrate support assembly  104 . Thus, the radially outward flowing gases may form a gas curtain between the lower region  150  and the remainder of the process volume  120  that is substantially parallel to the substrate support assembly  104 . The radiation shield  182  may be used alternatively to or in combination with the gas introduction ports  162  and/or the slit valve opening  126  to introduce gases into the process volume  120 , such as the lower region  150 . 
     As discussed herein, film deposition operations can include the formation of one or more films on the substrate  154  positioned on the substrate support assembly  104 .  FIG.  2    illustrates a flow chart of a method  200  for processing a substrate, according to one or more embodiments. The method  200  may be employed to form one or more films on the substrate  154 . 
     At operation  210 , a plasma is generated in the process volume  120  of the process chamber  100 . For example, a first gas is introduced from the first gas source  111  to the process volume  120  via the conduit  114 . The first gas is introduced into the process volume at a flow rate of between about 1000 sccm and about 20000 sccm, such as between about 8000 sccm and about 12000 sccm. The first gas includes at least a process gas, a precursor gas, an ionizable gas, or a carrier gas, which are activated in the process volume  120  to form the plasma. For example, the power source  142  provides an RF power, such as a continuous or pulsed RF power, to the gas distribution member  112  to activate the first gas into a plasma. Further, the first gas is utilized to form a film on the substrate  154  in the presence of the plasma. 
     At operation  220 , a second gas is introduced into the lower region  150  below the substrate support assembly  104  as plasma is generated above the substrate support assembly  104 . For example, the second gas is introduced into the lower region  150  from the second gas source  113  through one or more gas introduction ports  162  formed in the sidewalls  106  and/or the chamber bottom  108 . In another example, the second gas is introduced into the lower region  150  through the opening  146  between the shaft  144  and the chamber bottom  108 . In yet another example, the second gas is introduced into the lower region  150  through the space  176  between the radiation shaft  184  and the shaft  144 . The second gas is a non-reactive gas or a gas having a relatively low reactivity and may be formed of a species having a dissociation energy greater than that of diatomic argon. For example, the second gas is oxygen. Alternatively or additionally, the second gas may be any one of hydrogen, helium, argon, or ammonia, among others. 
     The second gas may be simultaneously introduced into the process volume  120  along with the first gas and function as a barrier curtain, reducing the amount of errant dispersion of the plasma and unreacted species throughout the process chamber  100 , and particularly into the lower region  150 . For example, the second gas, such as argon or nitrogen, functions as a dispersion trap, localizing the plasma and unreacted species above the substrate support assembly  104  and reducing diffusion (e.g., migration) elsewhere. The reduction of errant dispersion, in turn, reduces the formation of residues on chamber components, such as those components in the lower region  150  (e.g., below the substrate support assembly  104 ). In certain embodiments, the low reactivity of the second gas enables the second gas to function as trap without interacting or mixing with the plasma. Furthermore, the low reactivity of the second gas facilitates the reduction of active plasma species present in the lower region  150 , thus reducing deposition of chamber residues formed by parasitic plasma below the substrate support assembly  104 . 
     In another capacity, the second gas may function as a purge or cleaning gas, aiding in the removal of excess process gases or by-products from the process volume  120  during or after processing via the exhaust port  152 . For example, the second gas may facilitate spontaneous combustion of unreacted process gases that migrate below the substrate support assembly  104 . For example, in embodiments wherein oxygen is utilized as the second gas, the oxygen gas may facilitate a spontaneous combustion reaction consuming unreacted hydrocarbons, such as C 3 H 6 , dispersed below the substrate support assembly  104 , resulting in CO 2  and H 2 O gases which can then be removed via the exhaust port  152 . Thus, the second gas may actively clean the lower region of the process volume  120  as films are simultaneously deposited on the substrate  154  above. 
     In certain embodiments which can be combined with other embodiments, the second gas is provided to the lower processing region  150  to actively induce a reaction between the second gas and any of the first gas (e.g., the activated species) in the lower processing region  150 , while simultaneously providing a barrier for entry of the first gas into the lower region  150 . The first gas and the second gas may react to form a gaseous byproduct which is exhausted from the process chamber  100 , mitigating or avoiding deposition of material in the lower region  150  of the process volume  120 . In such an example, the second gas may be a reactive gas (e.g., a gas which reacts with the excess precursor material). For example, the first gas process may be a hydrocarbon while the second gas is oxygen or ozone. In such an example, the reaction between the first gas and the second gas is a combustion reaction. The combustion reaction may occur in the lower processing region  150 . In one example, the combustion reaction does not occur, or minimally occurs, in the process volume  120  above the substrate  154 . 
     The flow rate and type of second gas may be based on the flow rate of the first gas, the species of the first gas, the amount of plasma to be generated, the characteristics of the deposited film, the amount of first gas to be reacted with the second gas, and/or the amount of plasma dispersion to be prevented. For example, the second gas is flowed into the process volume  120  such that the second gas accounts for greater than about 25% of the total gas flow in the process volume  120  to dilute the first gas. For example, the second gas accounts for greater than about 30% of the total flow in the process volume  120 , such as about 40% of the total flow. In certain embodiments, the flow rate of the second gas is determined based on the concentration of the second gas species in the deposited film (e.g., nitrogen or oxygen). In some embodiments, the flow rate of the second gas is different than the flow rate of the first gas. For example, a ratio of the flow rate of the first gas to a flow rate of the second gas is between about 0.5 and about 3. For example, a ratio of the flow rate of the first gas to a flow rate of the second gas is between about 1 and about 2. In one embodiment, the second gas is flowed into the process volume  120  at a flow rate between about 50 standard cubic centimeters per minute and about 5000 sccm, such as between about 500 sccm and about 4000 sccm. For example, the second gas is flowed into the process volume  120  at a flow rate between about 1000 sccm and about 3000 sccm, such as about 2000 sccm. 
     At operation  230 , the plasma and the second gas are exhausted from the process chamber  100  through the exhaust port  152 . For example, the exhaust port  152  may be coupled to the vacuum pump  156 , and the vacuum pump  156  may remove excess process gases or by-products from the process volume  120  during or after processing of the substrate  154 . 
     Utilizing the systems and methods described above provides numerous improvements in substrate processing operations. In particular, the methods described above provide a proactive approach to reducing or eliminating the undesired formation and buildup of residues on process chamber components by reducing the errant dispersion of plasma and active plasma species below the substrate support. As such, the occurrence of defects in films formed by plasma processes and the cleaning time between plasma processing operations is reduced, resulting in improved overall yield throughput and decreased manufacturing costs. Methods disclosed herein are particularly advantageous in the deposition of carbon or carbon-based hardmasks. Methods herein provide multiple advantages for reducing unwanted deposition, including providing a gas barrier for mitigating activated precursors species in the lower region of the process chamber at the gas/activated species interface at the substrate support plane. Additionally, methods herein facilitate unwanted deposition by inducing combustion reactions. Moreover, methods herein facilitate unwanted deposition by diluting reactive species in the lower region of the process chamber. 
     While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.