Patent Publication Number: US-2018033659-A1

Title: Gas purge system and method for outgassing control

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims benefit of U.S. provisional patent application Ser. No. 62/368,066, filed Jul. 28, 2016, which is hereby incorporated herein by reference. 
    
    
     BACKGROUND 
     Field of the Disclosure 
     Embodiments of the present disclosure generally relate to the fabrication of integrated circuits. More specifically, embodiments disclosed herein relate to systems, methods, and apparatus for controlling substrate outgassing. 
     Description of the Related Art 
     The manufacture of modern logic, memory, or integrated circuits typically involves more than four hundred process steps. A number of these steps are thermal processes that raise the temperature of the semiconductor substrate to a target value to induce rearrangement in the atomic order or chemistry of thin surface films (e.g., diffusion, oxidation, recrystallization, salicidation, densification, flow). 
     Ion implantation is a method for the introduction of chemical impurities in semiconductor substrates to form the p-n junctions necessary for field effect or bipolar transistor fabrication. Such impurities include P-type dopants, such as boron, aluminum, gallium, beryllium, magnesium, and zinc, and N-type dopants such as phosphorus, arsenic, antimony, bismuth, selenium, and tellurium. Ion implantation of chemical impurities disrupts the crystallinity of the semiconductor substrate over the range of the implant. At low energies, relatively little damage occurs to the substrate. However, the implanted dopants will not come to rest on electrically active sites in the substrate. Therefore, an anneal is necessary to restore the crystallinity of the substrate and drive the implanted dopants onto electrically active crystal sites. 
     During the processing of the substrate in, for example, an RTP chamber, the substrate may tend to outgas impurities implanted therein. These outgassed impurities may be the dopant material, a material derived from the dopant material, or any other material that may escape the substrate during the annealing process, such as the sublimation of silicon. The outgassed impurities may deposit on the colder walls and on the reflector plate of the chamber. This deposition may interfere with temperature pyrometer readings and with the radiation distribution fields on the substrate, which in turn affects the temperature at which the substrate is annealed. Deposition of the outgassed impurities may also cause unwanted particles on the substrates and may also generate slip lines on the substrate. Depending on the chemical composition of the deposits, the chamber is taken offline for a wet clean process. 
     Furthermore, one of the biggest challenges for III-V CMOS (FinFET, TFET) mass production is to control the outgassing from the substrates after a III-V epitaxial growth process and/or an etch clean process. Limitations in current outgassing control include that the thermal back process (&gt;200 degrees Celsius) in either a process chamber or an etch chamber is not suitable after a III-V epitaxial growth or etch process as longer bake times for each substrate is necessary to drive out arsenic related outgassing gasses from the substrate surface and throughput is lowered. Furthermore, a long N 2  purge/pump cycle is less efficient and has a large impact on throughput. Testing has been performed on the prior known methods and results indicate that after ten cycles of pump/purge, arsenic outgassing was still detected at 1.9 parts per billion. 
     Absolute zero parts per billion (ppb) outgassing is typically desired for arsenic residuals due to arsenic toxicity. To minimize toxicity from arsenic outgassing during subsequent handling and processing of substrates, there is a need for an improved system, method, and apparatus for controlling substrate outgassing. 
     SUMMARY 
     Embodiments disclosed herein generally relate to a system, method, and apparatus for controlling substrate outgassing such that hazardous gasses are eliminated from a surface of a substrate after a III-V epitaxial growth process or an etch clean process, and prior to additional processing. In one embodiment, a substrate processing apparatus is disclosed. The substrate processing apparatus includes a loadlock chamber, a support structure, and a gas distribution structure. The loadlock chamber has a body defining a volume therein. The support structure is disposed in the volume and has a plurality of support members. The gas distribution structure is disposed in the volume adjacent the support structure. Furthermore, the gas distribution structure includes a gas supply line and a plurality of distribution lines. The gas supply line is operatively connected to a gas source. Each distribution line is operatively connected to and extends from the gas supply line. At least one distribution line is disposed adjacent each support member, and each distribution line has a plurality of holes disposed therein. Moreover, each distribution line defines a plane. Each gas hole is angled toward a corresponding support member relative to the plane. 
     In another embodiment, a substrate processing apparatus is disclosed. The substrate processing apparatus includes a loadlock chamber, a support structure, and a gas distribution structure. The loadlock chamber has a body defining a volume therein. The support structure has a plurality of support members disposed in the volume. The gas distribution structure is disposed in the volume adjacent the support structure. The gas distribution structure includes a gas supply line and a plurality of distribution lines. The gas supply line is operatively connected to a first gas source and a second gas source. Each distribution line is operatively connected to and extends from the gas supply line. At least one distribution line is disposed adjacent to each support member, and each distribution line has a plurality of gas holes disposed therein. 
     In another embodiment, a substrate processing apparatus is disclosed. The substrate support apparatus includes a loadlock chamber, a support structure, and a gas distribution structure. The loadlock chamber has a body defining a volume therein. The support structure is disposed in the volume and has a plurality of support members. The gas distribution structure is disposed in the volume adjacent the support structure. The gas distribution structure includes a gas supply line operatively connected to an O 2  gas source and a N 2  gas source and a plurality of distribution lines. Each distribution line is operatively connected to and extends from the gas supply line. At least one distribution line is disposed adjacent each support member, and each distribution line has a plurality of gas holes disposed therein. Each gas hole is angled relative to a horizontal axis of the distribution line. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that the manner in which the above recited features of the 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 typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments. 
         FIG. 1  schematically illustrates a side cross-sectional view of a load lock chamber for a gas purge system, according to one embodiment. 
         FIG. 2  schematically illustrates a top view of the load lock chamber of  FIG. 1 , according to one embodiment. 
         FIG. 3  schematically illustrates a front cross-sectional view of the load lock chamber of  FIG. 1 , according to one embodiment. 
         FIG. 4  schematically illustrates a top view of a distribution line, according to one embodiment. 
         FIG. 5  illustrates a schematic flow diagram of a method for controlling outgassing, according to one embodiment. 
         FIG. 6  illustrates a schematic flow diagram of a method for controlling outgassing after a III-V epitaxial process, according to one embodiment. 
         FIG. 7  illustrates a schematic flow diagram of a method for controlling outgassing, according to one embodiment. 
         FIG. 8  schematically illustrates a graph showing operations for controlling outgassing. 
     
    
    
     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 disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation. 
     DETAILED DESCRIPTION 
     Embodiments disclosed herein generally relate to a system, method, and apparatus for controlling substrate outgassing such that hazardous gasses are eliminated from a surface of a substrate after a III-V epitaxial growth process or an etch clean process, and prior to additional processing. An oxygen containing gas is flowed to a substrate in a load lock chamber, and subsequently a non-reactive gas is flowed to the substrate in the load lock chamber. As such, hazardous gases and outgassing residuals are decreased and/or removed from the substrate such that further processing may be performed. 
     A “substrate” or “substrate surface,” as described herein, generally refers to any substrate surface upon which processing is performed. For example, a substrate surface may include silicon, silicon oxide, doped silicon, silicon germanium, germanium, gallium arsenide, glass, sapphire, and any other materials, such as metals, metal nitrides, metal alloys, and other conductive or semi-conductive materials, depending on the application. A substrate or substrate surface may also include dielectric materials such as silicon dioxide, silicon nitride, organosilicates, and carbon dopes silicon oxide or nitride materials. The term “substrate” may further include the term “wafer.” The substrate itself is not limited to any particular size or shape. Although the implementations described herein are generally made with reference to a round substrate, other shapes, such as polygonal, squared, rectangular, curved, or otherwise non-circular workpieces may be utilized according to the implementations described herein. 
       FIG. 1  schematically illustrates a simplified side cross-sectional view of a load lock chamber  102  for a gas purge system  100 , according to one embodiment. The load lock chamber  102  has a body  103  defined by a lid  104 , side walls  106 , and a bottom wall  108 . The body defines a volume  110  therein. In some embodiments, the load lock chamber  102  may be a substrate access chamber, or vice versa, as discussed supra. A support structure  112  is disposed in the volume  110  and includes a plurality of support members  114 . Each support member  114  is configured to support a substrate  116  thereon. The support structure  112  may have one or more support members  114 , and each support member  114  may hold and/or support a portion of the substrate  116  or the entire substrate. In certain embodiments, each support member  114  may contact the substrate  116  at or near the edge of the substrate  116  so as to not interfere with the processing of the substrate  116 . The support structure  112  may be configured to hold and/or support, for example, twenty-five or more substrates in the body  103 . In some embodiments, the plurality of support members  114  may each include a minimum contact surface (not shown). The minimum contact surface may include a plurality of raised surfaces, for examples three bumps, such that a substrate rests on each of the raised surfaces. In certain embodiments, the minimum contact surface may also include a mesh support disposed below, adjacent, and or in contact with the plurality of raised surfaces. The mesh support may be any gas transmissive structure, for example, a structure that allows gas to pass therethrough. The minimum contact surface may allow for processing of a bottom side of the substrate. 
     A gas distribution structure  120  is disposed in the volume  110 . In some embodiments, the gas distribution structure  120  may also extend out of the volume  110  at a first end  122  and/or a second end  124  of the body. The gas distribution structure  120  is disposed adjacent to the support structure  112 . The gas distribution structure  120  includes a gas supply line  126  and a plurality of distribution lines  128 . 
     The gas supply line  126  is operatively connected to a first gas source  130 A. In some embodiments, however, the gas supply line  126  is operatively connected to more than one gas source, such as a first gas source  130 A and a second gas source  130 B. In some embodiments, the first gas source  130 A and/or the second gas source  1306  may be disposed outside of the volume  110 , while in other embodiments, the first gas source  130 A and/or the second gas source  130 B may be disposed inside the volume  110 . The gas supply line  126  is configured to deliver gas from a gas source into the volume  110 . A first valve  132 A is disposed between the first gas source  130 A and the gas supply line  126 . A second valve  132 B is disposed between the second gas source  130 B and the gas supply line  126 . The flow of gas from the first gas source  130 A may be controlled by a first valve  132 A. The first valve  132 A may be operatively connected to the gas supply line  126 . The first valve  132 A is configured to regulate the amount and/or flow of gas supplied by the first gas source  130 A to the gas supply line  126 . The flow of gas from the second gas source  130 B may be controlled by a second valve  132 B. The second valve  132 B may be operatively connected to the gas supply line  126 . The second valve  132 B regulates the amount and/or flow of gas supplied by the second gas source  1306  to the gas supply line  126 . In some embodiments, the first gas source  130 A may be an oxygen containing gas source or a nitrogen containing gas source. In some embodiments, the second gas source  130 B may be an oxygen containing gas source or a nitrogen containing gas source. Although two gas sources are shown, it is contemplated that any number of gas sources, containing any suitable gas, may be operatively connected to the gas supply line  126 . Additionally, any of the gas distribution structure  120 , the gas supply line  126 , and/or the distribution lines may comprise a stainless steel material. 
     In certain embodiments, gas may flow from the first gas source  130 A and/or the second gas source  130 B to the gas supply line  126  upon an opening of the first valve  132 A or the second valve  132 B, respectively. In some embodiments, only the first valve  132 A or only the second valve  132 B may be opened at a time such that only one gas is flowed into the volume  110  at a time. However, in certain embodiments, multiple gases may be flowed into the volume  110  at the same time. For example, in some embodiments, both the first valve  132 A and the second valve  132 B may be opened at the same time. Gas may flow through the gas distribution structure  120  and into the volume  110  as shown by the arrows in  FIG. 1 . Upon exiting each distribution line  128  the gas may flow over and/or across each substrate  116 . After flowing over and/or across each substrate  116 , the gas may be directed toward the bottom wall  108  of the body  103 . In some embodiments, a pump  140  may be disposed at or near the bottom wall  108  of the body  103 . The pump  140  may be disposed in and/or create an opening in the bottom wall  108  such that the pump is configured to pump gas out of and remove gas from the body  103 . 
     Furthermore, each of the gas distribution structure  120 , the gas supply line  126 , and/or each distribution line  128  may be pressurized to ensure the same or similar flow of gas on or across substrates disposed near the lid  104  of the body  103  as is flowed on or across substrates disposed near the bottom wall  108  of the body  103 . 
     As discussed infra, a material is removed from a surface of the substrate  116  by reacting an oxygen containing gas with the surface of the substrate  116 . Typically, a substrate access chamber, such as load lock chamber  102 , maintains an inert environment. The flowing of the oxygen containing gas into the body  103  may expose each substrate  116  therein to the oxygen containing gas. As shown, oxygen containing gas may flow from the first gas source  130 A and/or the second gas source  130 B to the load lock chamber  102 . Upon contacting the substrate  116 , any residual arsenic related species on a surface of the substrate  116 , as well as on the III-V surface, are oxidized. The arsenic residuals are broken down to either stable oxides and/or byproducts which have a high vapor pressure, and therefore evaporate quickly. As such, the deliberate pulsing and/or providing of the oxygen containing gas into the volume  110  may pre-remove arsenic in a controlled manner in order to appropriately abate the arsenic. 
     Flowing an oxygen containing gas into the load lock chamber  102  may allow for stable oxides to form on the surface of the substrate  116 . Also, the oxygen containing gas may allow high vapor pressure byproducts may be removed from the substrate  116 . Moreover, oxidation may have various effects on the substrate  116 . The oxidation may break the bond of the arsenic species (for example between arsenic and OH groups) to carbon to form arsenic oxide which may leave the surface of the substrate more quickly. 
       FIG. 2  schematically illustrates a top view of the load lock chamber  102  of  FIG. 1 , according to one embodiment. As shown, at least one distribution line  128  is disposed adjacent each support member  114 . Each distribution line  128  is operatively connected to the gas supply line  126 . In some embodiments, each distribution line  128  extends from the gas supply line  126 . As shown in  FIG. 2 , at least one distribution line  128  is disposed adjacent each support member  114 . Furthermore, in certain embodiments, the gas supply line  126  may run through each distribution line  128 . In some embodiments, the gas supply line  126  is disposed through the center of each distribution line  128 , while in other embodiments, the gas supply line  126  may be disposed through any section of each distribution line  128 , for example, near a distal end of the distribution line  128 . 
     Each distribution line  128  has an arcuate shape, such that the distribution line conforms to the approximate shape of at least a portion of the substrate  116 . In some embodiments, the distribution line  128  may have a radius of between about two inches and about twenty inches, for example between about four inches and about twelve inches. In certain embodiments, each distribution line  128  may have an angular extent of between about 90 degrees and about 180 degrees, for example between about 100 degrees and about 150 degrees. In some embodiments, however, each distribution line  128  may have a V-shape, a C-shape, a square shape, a rectangular shape, or any other suitable shape, such that the distribution line  128  is configured to distribute gas along and/or across a surface of the substrate  116 . Each distribution line  128  may be a circular tube, however, it is contemplated that any shape distribution line may be suitably utilized. 
     Each distribution line  128  may be disposed adjacent, immediately next two, and/or proximate each substrate  116  held by each support member  114 . A gap  142  may be disposed between each distribution line  128  and each substrate  116 . In some embodiments, the gap  142  between each distribution line  128  and each substrate  116  may be between about 1/16 inch and about one inch, for example between about ⅛ inch and about ¼ inch. 
       FIG. 3  schematically illustrates a front cross-sectional view of the load lock chamber  102  of  FIG. 1 , according to one embodiment. Each distribution line  128  has a plurality of gas holes  150  disposed therein. In some embodiments, each distribution line  128  comprises between about two gas holes  150  and about 50 gas holes  150 , for example between about eight gas holes  150  and about 20 gas holes  150 . It is contemplated, however, that each distribution line  128  may include any suitable number of gas holes  150 . 
     Each gas hole  150  has a diameter between about 1/64 inch and about ½ inch, for example between about 1/32 inch and about ¼ inch. Each of the plurality of gas holes  150  may be uniformly distributed along each distribution line  128 , thus creating an equal amount of spacing between each gas hole  150 . However, in some embodiments, each of the plurality of gas holes  150  may be non-uniformly distributed along each distribution line  128 . As such, the spacing between each gas hole  150  may vary between each gas hole. Therefore, in some embodiments, a higher or lower concentration of gas holes  150  may be disposed, for example, near the center of each distribution line  128  and/or near the distal end of each distribution line  128 . 
     With reference to both  FIG. 2  and  FIG. 3 , each distribution line  128  may be disposed at or above a top surface  117  of each substrate  116 . In some embodiments, a gap  160  may be disposed between the top surface  117  of each substrate  116  and each respective distribution line  128 . The gap  160  may be between about 1/32 inch and about ½ inch, for example between about 1/16 inch and about ¼ inch. Each distribution line  128  defines a plane. Each gas hole  150  may be disposed along the plane. By way of example only, in some embodiments, each distribution line  128  may define a horizontal plane H. By way of continued example, each gas hole  150  may be disposed along the horizontal plane H, such as above the horizontal plane H, or below the horizontal plane H. Each gas hole  150  has a gas flow axis that forms an angle between about five degrees and about twenty-five degrees with the plane. In some embodiments, each gas hole  150  may be angled downward or upward relative to the horizontal plane H of each distribution line  128 . In some embodiments, each gas hole  150  is angled downward or upward relative to the horizontal plane H at an angle between about two degrees and about forty-five degrees, such as between about five degrees and about twenty-five degrees. In some embodiments, however, each gas hole  150  may be angled upward relative to the horizontal plane, for example, during processing of a bottom side of the substrate  116 . The angling of each gas hole  150  toward the top surface  117  or bottom surface of each substrate  116  directs flow of the gas to the top surface  117  or bottom surface of each substrate  116 . As discussed supra, when oxygen gas is flowed across each substrate  116 , outgassing species are efficiently and effectively carried away from the substrate  116 . Furthermore, in some embodiments, the flow rate of the gas exiting the gas holes  150  may range from subsonic to supersonic. 
     With further reference to both  FIG. 2  and  FIG. 3 , each gas hole  150  may be drilled at an angle normal to the distribution line  128 , or, in some embodiments, as an angle non-normal to the distribution line  128 . In certain embodiments, certain gas holes  150  may be drilled at an angle normal to the distribution line  128  while other gas holes  150  may be drilled at an angle non-normal to the distribution line  128 . Also, certain gas holes  150  may be drilled outward on each distribution line  128  to ensure gas coverage of the entire surface of the substrate  116 . As shown in  FIG. 2 , the gas holes  150  proximate the distal end of the distribution line may be configured to direct gas at an angle non-normal to the distribution line  128 . As such, the angle non-normal to the distribution line  128  may increase for subsequent gas hole  150  closer to the distal ends of the distribution line  128 . As further shown in  FIG. 2 , in some embodiments, gas holes  150  disposed closer to the center of the distribution line  128  may be drilled at an angle subsequently closer to an angle normal to the distribution line  128 . As such, in certain embodiments, and as shown in  FIG. 2  and  FIG. 3 , a first sub-plurality of the plurality of gas holes  150  may be disposed at an angle normal to the distribution line and a second plurality of the plurality of gas holes  150  may be disposed at an angle non-normal to the distribution line  128 . 
       FIG. 4  schematically illustrates an embodiment of the distribution line  128  which includes a plurality of nozzles  170  operatively connected to each gas hole  150 . As described supra, each gas hole  150  may be angled, and as such, each respective nozzle  170  may also be angled. However, in some embodiments, each gas hole may be drilled at an angle normal to the distribution line  128 , and each respective nozzle may be movably positioned in order to direct the flow of gas in the proper direction across the substrate  116 . 
       FIG. 5  is a schematic flow diagram of a method  500  for controlling outgassing. The method  500  provides operations for reducing outgassing. Substrate outgassing generally relates to the releasing of a gas or vapor product from the substrate or from a surface of the substrate. Controlling outgassing relates to reducing and/or eliminating residual outgassed materials, for example, arsenic, from a substrate prior to transferring the substrate for downstream processing. 
     At operation  510 , a substrate is delivered into a substrate access chamber. In some embodiments, the substrate access chamber may be a load lock chamber and/or a FOUP (front opening unified pod). In some embodiments, each substrate may be transferred to the substrate access chamber in a non-reactive gas, for example, after a III-V epitaxial growth process and/or after a III-V etch process. 
     At operation  520 , an oxygen containing gas is flowed into the substrate access chamber and, at operation  530 , a material is removed from a surface of the substrate by reacting the oxygen containing gas with the surface of the substrate. Typically, a substrate access chamber maintains an inert environment. The flowing of the oxygen containing gas into the substrate access chamber may expose the substrate therein to the oxygen containing gas. The flowing of the oxygen containing gas into the substrate access chamber may occur via a conduit coupled to an oxygen containing gas source and to the substrate access chamber. The oxygen containing gas may flow from the oxygen containing gas source to the substrate access chamber. Upon contacting the substrate, any residual arsenic related species on a surface of the substrate, as well as on the III-V surface, are oxidized. The arsenic residuals are broken down to either stable oxides and/or byproducts which have a high vapor pressure, and therefore evaporate quickly. As such, the deliberate pulsing and/or providing of the oxygen containing gas into the substrate access chamber may pre-remove arsenic in a controlled manner in order to appropriately abate the arsenic. 
     In some embodiments, the oxygen containing gas is oxygen. It is contemplated that any amount of oxygen containing gas may be flowed into the substrate access chamber, however, in some embodiments, between about 5 sccm and about 1200 sccm of the oxygen containing gas is flowed into the substrate access chamber. 
     The oxygen containing gas is flowed into the substrate access chamber for between about one second and about 60 seconds, for example, between about one second and about 30 seconds, such as about 10 seconds. Furthermore, the oxygen containing gas is flowed into the substrate access chamber at a first pressure (P 1 ). In some embodiments, the first pressure (P 1 ) is between about 60 Torr and about 220 Torr, for example between about 80 Torr and about 200 Torr. 
     Flowing the oxygen containing gas into the substrate access chamber may allow for stable oxides to form on the surface of the substrate. Also, the oxygen containing gas may allow high vapor pressure byproducts to be removed from the substrate. 
     Moreover, oxidation may have various effects on the substrate. The oxidation may break the bond of the arsenic species (for example between arsenic and OH groups) to carbon to form arsenic oxide which may leave the surface of the substrate more quickly. 
     At operation  540 , the flow of the oxygen containing gas into the substrate access chamber is ceased. 
     At operation  550 , a non-reactive gas is flowed into the substrate access chamber. The non-reactive gas is flowed into the substrate access chamber for between about 30 seconds and about 400 seconds, for example, between about 60 seconds and about 300 seconds. In some embodiments, the non-reactive gas is flowed into the substrate access chamber at a second pressure (P 2 ). Furthermore, the second pressure (P 2 ) is greater than the first pressure (P 1 ), discussed supra. In some embodiments, the second pressure (P 2 ) is above about 180 Torr, for example, above about 200 Torr. It is contemplated, however, that the second pressure (P 2 ) may be any pressure greater than the first pressure (P 1 ). The non-reactive gas may include a helium-containing gas, a hydrogen-containing gas, a nitrogen-containing gas, and/or an argon-containing gas, among others. In some embodiments, the non-reactive gas is N 2 . The flowing of the non-reactive gas into the substrate access chamber may occur after the flowing of the oxygen containing gas into the substrate access chamber. The flowing of the non-reactive gas after oxidation drives down outgassing towards to the zero ppb level. The zero ppb level means that the outgassing of toxic species, for example, arsenic, is undetectable. 
     At operation  560 , the flow of the non-reactive gas into the substrate access chamber is ceased. 
     At operation  570 , the non-reactive gas is removed from the substrate access chamber, for example, via a pump cycle. The removing of the non-reactive gas from the substrate access chamber is at a third pressure (P 3 ). The third pressure is less than the first pressure (P 1 ). In some embodiments, the third pressure is less than about 1 Torr. The third pressure (P 3 ) is lower than the second pressure (P 2 ) and/or the first pressure (P 1 ) during the removal of the non-reactive gas such that when the non-reactive gas is reinserted into the substrate access chamber a strong dilution is provided for. Furthermore, the first pressure (P 1 ) being less than the second pressure (P 2 ) provides for efficiency benefits to improve the reaction rate. 
     In some embodiments, operation  550 , operation  560 , and/or operation  570  may be repeated for at least one additional cycle after an initial completion of operation  570 . By repeating the flowing of the non-reactive gas into the substrate access chamber, ceasing the flow of the non-reactive gas into the substrate access chamber, and/or removing the non-reactive gas from the substrate access chamber, outgassing is further driven down towards the zero ppb level. Testing has been completed and results indicate that one oxidation operation, such as operation  520 , operation  530 , and operation  540 , and three non-reactive gas cycles, such as operation  550 , operation  560 , and operation  570 , reduce outgassing to zero ppb. 
     In some embodiments, after outgassing has been reduced, the substrate may be transferred to a FOUP (front opening unified pod) for further down-stream processing. 
       FIG. 6  is a schematic flow diagram of a method  600  for controlling outgassing after a III-V epitaxial process. The method  600  provides a solution for reducing outgassing. 
     At operation  610 , a substrate is delivered to a load lock chamber. 
     At operation  620 , an oxygen containing gas is flowed into the load lock chamber. The flowing of the oxygen containing gas into the load lock chamber may expose the substrate therein to the oxygen containing gas. Upon contacting the substrate, any residual arsenic related species on a surface of the substrate, as well as on the III-V surface, is oxidized. The arsenic residuals are broken down to either stable oxides and/or byproducts which have a high vapor pressure, and therefore evaporate quickly. As such, the deliberate pulsing and/or providing of the oxygen containing gas into the load lock chamber may pre-remove arsenic in a controlled manner in order to appropriately abate the arsenic. 
     In some embodiments, the oxygen containing gas is oxygen. It is contemplated that any amount of oxygen containing gas may be flowed into the load lock chamber, however, in some embodiments, between about 5 sccm and about 1200 sccm of the oxygen containing gas is flowed into the load lock chamber. 
     The oxygen containing gas is flowed into the load lock chamber for between about one second and about 60 seconds, for example, between about one second and about 30 seconds, such as about 10 seconds. Furthermore, the oxygen containing gas is flowed into the load lock chamber at a first pressure (P 1 ). In some embodiments, the first pressure (P 1 ) is between about 60 Torr and about 220 Torr, for example between about 80 Torr and about 200 Torr. 
     Flowing the oxygen containing gas into the load lock chamber may allow for stable oxides to form on the surface of the substrate. Also, the oxygen containing gas may allow high vapor pressure byproducts to be removed from the substrate. 
     At operation  630 , the flow of the oxygen containing gas into the load lock chamber is ceased. 
     At operation  640 , a nitrogen containing gas is flowed into the load lock chamber. The nitrogen containing gas is flowed into the load lock chamber for between about 30 seconds and about 400 seconds, for example, between about 60 seconds and about 300 seconds. In some embodiments, the nitrogen containing gas is flowed into the load lock chamber at a second pressure (P 2 ). Furthermore, the second pressure (P 2 ) is greater than the first pressure (P 1 ), discussed supra. In some embodiments, the second pressure (P 2 ) is above about 180 Torr, for example, above about 200 Torr. In some embodiments, the nitrogen containing gas is N 2 . The flowing of the nitrogen containing gas into the load lock chamber may occur after the flowing of the oxygen containing gas into the load lock chamber. The flowing of nitrogen containing gas after oxidation drives down outgassing towards to the zero ppb level. 
     At operation  650 , the nitrogen containing gas is pumped out of the load lock chamber. The removing of the nitrogen containing gas from the load lock chamber is at a third pressure (P 3 ). The third pressure is less than the first pressure (P 1 ). In some embodiments, the third pressure is less than about 1 Torr. The third pressure (P 3 ) is lower than the second pressure (P 2 ) and/or the first pressure (P 1 ) during the removal of the nitrogen containing gas such that when the nitrogen containing gas is reinserted into the load lock chamber a strong dilution is provided for. Furthermore, the first pressure (P 1 ) being less than the second pressure (P 2 ) provides for efficiency benefits to improve the reaction rate. 
     The method  600  may also include repeating the flowing of the nitrogen containing gas into the load lock chamber as in operation  640  and/or the pumping of the nitrogen-containing gas out of the load lock chamber as in operation  650 , for at least one additional cycle. By repeating the flowing of the nitrogen containing gas into the load lock chamber and removing the nitrogen containing gas from the load lock chamber, outgassing is further driven down towards the zero ppb level. Testing has been completed and results indicate that one oxidation operation and three nitrogen containing gas cycles reduce outgassing to zero ppb. In some embodiments, the method  600  may also include removing a material from a surface of the substrate by reacting the oxygen containing gas with the surface of the substrate. In some embodiments, after outgassing has been reduced, the substrate may be transferred to a FOUP (front opening unified pod) for further down-stream processing. 
       FIG. 7  is a schematic flow diagram of a method  700  for controlling outgassing. The method  700  provides a solution for reducing outgassing. 
     At operation  710 , a substrate is delivered to a load lock chamber. 
     At operation  720 , oxygen gas is flowed into the load lock chamber at a first pressure (P 1 ). The first pressure (P 1 ) is between about 30 Torr and about 300 Torr. The flowing of the oxygen gas into the load lock chamber may expose the substrate therein to the oxygen gas. Upon contacting the substrate, any residual arsenic related species on a surface of the substrate, as well as on the III-V surface, are oxidized. The arsenic residuals are broken down to either stable oxides and/or byproducts which have a high vapor pressure, and therefore evaporate quickly. As such, the deliberate pulsing and/or providing of the oxygen gas into the load lock chamber may pre-remove arsenic in a controlled manner in order to appropriately abate the arsenic. 
     It is contemplated that any amount of oxygen gas may be flowed into the load lock chamber, however, in some embodiments, between about 5 sccm and about 1200 sccm of the oxygen gas is flowed into the load lock chamber. 
     The oxygen gas is flowed into the load lock chamber for between about one second and about 60 seconds, for example, between about one second and about 30 seconds, such as about 10 seconds. Furthermore, the oxygen gas is flowed into the load lock chamber at a first pressure (P 1 ). In some embodiments, the first pressure (P 1 ) is between about 30 Torr and about 300 Torr, for example between about 80 Torr and about 200 Torr. 
     Flowing the oxygen gas into the load lock chamber may allow for stable oxides to form on the surface of the substrate. Also, the oxygen gas may allow high vapor pressure byproducts to be removed from the substrate. 
     At operation  730 , the flow of the oxygen gas into the load lock chamber is ceased. 
     At operation  740 , a non-reactive gas is flowed into the load lock chamber at a second pressure (P 2 ). The second pressure (P 2 ) is above about 180 Torr, for example above about 200 Torr. The non-reactive gas is flowed into the load lock chamber for between about 30 seconds and about 400 seconds, for example, between about 60 seconds and about 300 seconds. In some embodiments, the non-reactive gas is N 2 . The flowing of the non-reactive gas into the load lock chamber may occur after the flowing of the oxygen gas into the load lock chamber. The flowing of the non-reactive gas after oxidation drives down outgassing towards to the zero ppb level. The zero ppb level means that the outgassing of toxic species, for example, arsenic, is undetectable. 
     At operation  750 , the non-reactive gas is pumped out of the load lock chamber at a third pressure (P 3 ). The third pressure is below about 1 Torr. The third pressure (P 3 ) is lower than the second pressure (P 2 ) and/or the first pressure (P 1 ) during the removal of the non-reactive gas such that when the non-reactive gas is reinserted into the load lock chamber a strong dilution is provided for. Furthermore, the first pressure (P 1 ) being less than the second pressure (P 2 ) provides for efficiency benefits to improve the reaction rate. 
     At operation  760 , operation  740  and operation  750  are repeated for at least one additional cycle. By repeating the flowing of the non-reactive gas into the load lock chamber and removing the non-reactive gas from the load lock chamber, outgassing is further driven down towards the zero ppb level. Testing has been completed and results indicate that one oxidation operation and three non-reactive gas cycles reduce outgassing to zero ppb. In some embodiments, the method  700  may also include removing a material from a surface of the substrate by reacting the oxygen containing gas with the surface of the substrate. In some embodiments, after outgassing has been reduced, the substrate may be transferred to a FOUP (front opening unified pod) for further down-stream processing. 
       FIG. 8  schematically illustrates a graph  800  showing operations for controlling outgassing, as discussed supra. As shown, an oxygen containing gas is flowed into the load lock chamber at a first pressure (P 1 ) in the section marked A, between time T 0  and time T 1 . The span of time between T 0  and T 1  may be between about one second and about 60 seconds. At time T 1  the flowing of the oxygen containing gas into the load lock chamber is ceased. The non-reactive gas is flowed into the load lock chamber at a second pressure (P 2 ) in the section marked B, between time T 1  and time T 2 . The span of time between T 1  and T 2  may be between about 30 seconds and about 400 seconds. At time T 2  the flowing of the non-reactive gas into the load lock chamber is stopped. Furthermore, the non-reactive gas is pumped out of the load lock chamber at a third pressure (P 3 ) between time T 2  and time T 3  as shown in the section marked C. The span of time between T 2  and T 2  may be between about 30 seconds and about 400 seconds. A subsequent non-reactive gas flow and removal cycle may occur in the section marked D between time T 3  and time T 5 . 
     Testing has been completed and results indicate that after an exposure to an oxygen containing gas residual arsenic related species on the substrate and/or on the surface of the substrate, as well as on the III-V surface, are oxidized. The arsenic residuals are broken down to either stable oxides or byproducts which have high vapor pressure and evaporate quickly. Also, after oxidation, the non-reactive gas pump/purge cycle is completed, thus driving down outgassing to zero ppb. Results indicate that after one oxidation and three non-reactive gas pump/purge cycles, outgassing was reduced to zero ppb, thus leaving no outgassing residuals and further improving throughput. 
     Benefits of the present disclosure include improved substrate throughput, as well as substrates in which residual arsenic outgassing gasses are eliminated before transfer to a FOUP. Furthermore, fume hoods are not necessary to control outgassing. Outgassing is controlled and removed prior to subsequent processes between chambers and/or tools. 
     Additional benefits include reduced contaminations and cross-contaminations. Also, the present disclosure may be applied to all arsenic and/or phosphate implantations, and is not limited to III-V implantations. 
     To summarize, the embodiments disclosed herein relate to a system, method, and apparatus for controlling substrate outgassing such that hazardous gasses are eliminated from a surface of a substrate after a III-V epitaxial growth process or an etch clean process, and prior to additional processing. An oxygen containing gas is flowed to a substrate in a load lock chamber, and subsequently a non-reactive gas is flowed to the substrate in the load lock chamber. As such, hazardous gases and outgassing residuals are decreased and/or removed from the substrate such that further processing may be performed. 
     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.