Patent Publication Number: US-2016233114-A1

Title: Chambers for particle reduction in substrate processing systems

Description:
FIELD 
     The present disclosure relates to substrate processing systems, and more particularly to particle reduction in substrate processing systems. 
     BACKGROUND 
     The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure. 
     Referring now to  FIG. 1 , an example of a substrate processing tool  20  includes a transport handling chamber  21  and multiple reactors each with one or more substrate processing chambers. A substrate  25  enters the substrate processing tool  20  from a cassette and/or pod  23 , such as a front opening unified pod (FOUP). A robot  24  includes one or more end effectors to handle the substrate  25 . A pressure of the transport handling chamber  21  may be at atmospheric pressure. Alternately, the transport handling chamber  21  may be at vacuum pressure (with ports acting as isolation valves). 
     The robot  24  moves the substrates  25  from the cassette and/or pod to a loadlock chamber  30 . For example, the substrate  25  enters the loadlock chamber  30  through a port  32  (or isolation valve) and is placed on a loadlock pedestal  33 . The port  32  to the transport handling chamber  21  closes and the loadlock chamber  30  is pumped down to an appropriate pressure for transfer. Then a port  34  opens and another robot  36  (also with one or more end effectors) in a processing handling chamber  35  places the substrates through one of the ports  37 - 1 ,  37 - 2 ,  37 - 3  (collectively ports  37 ) corresponding to a selected reactor  40 - 1 ,  40 - 2 , and  40 - 3  (collectively reactors  40 ). 
     A substrate indexing mechanism  42  may be used to further position the substrates relative to the substrate processing chambers. In some examples, the indexing mechanism  42  includes a spindle  44  and a transfer plate  46 . 
     The processing chambers or stations of the reactors  40  may be capable of performing semiconductor processing operations, such as a material deposition or etching, sequentially or simultaneously with the other stations. One or more of the stations may perform semiconductor processing operations using plasma. 
     The substrate is moved from one station to the next in the reactor  40  using the substrate indexing mechanism  42 . One or more of the stations of the reactors  40  may be capable of performing RF plasma deposition or etching. During use, the substrates are moved to one or more of the reactors  40 , processed and then returned. 
     The substrate processing tool  20  may include one or more metrology chambers or stations  48 , such as a mass metrology station. In  FIG. 1 , while the metrology station  48  is connected to the transport handling chamber  21 , the metrology station  48  may be connected to the processing handling chamber  35 . In some examples, the substrate processing tool  20  includes one or more buffer stations  49 . 
     For example, a substrate may be received, moved to one of the reactors  40 - 1  for processing, moved to the metrology station  48 , moved to another one of the reactors  40 - 2  for processing, moved to the metrology station  48 , moved to another one of the reactors  40 - 3  for processing and then returned to the cassette. 
     During movement through the substrate processing tool  20 , suspended particles or particles on chamber surfaces in the load lock or processing chamber may travel to the substrate being processed. The particles may be generated during processing or caused by contamination. One method for removing the particles from the chambers so that they do not contaminate the substrate involves pumping purge gas and venting (hereinafter “pump/vent method”). The pump/vent method transports the particles that are suspended and/or located on the chamber surfaces using a vacuum pump and purge gas. The pump/vent method provides limited particle improvement. However, the pump/vent method can be done at times when the substrate processing tool is idle and therefore does not impact system uptime. 
     Another method for removing particles from chambers involves wet cleaning, which uses clean room wipes and solvent to mechanically remove particles from the chamber. Wet cleaning requires that all processes on the substrate processing tool stop. The chambers are opened to atmosphere while the wet cleaning is performed manually. This approach impacts both uptime and cost of ownership. 
     For logistical purposes, the processing chambers are also cleaned when the platform goes down for wet cleaning. This allows platform wet cleaning and process chamber wet cleaning to occur in parallel. While the parallel cleaning consolidates downtime, when the platform mean wafers between cleans (MWBC) is shorter than a processing chamber module MWBC, the platform cleaning frequency determines the system uptime. 
     SUMMARY 
     A substrate processing system includes a chamber configured to process a semiconductor substrate. At least one surface of the chamber includes a high surface area finish. A purge/vent system is configured to selectively supply purge gas over the high surface area finish of the at least one surface to trap particles in the high surface area finish without opening the chamber. The high surface area finish on the at least one surface of the chamber has a porosity within a predetermined range from 30-60%. The porosity is defined by a normalized density of the high surface area finish relative to an underlying native bulk material of the at least one surface of the chamber. 
     In other features, the chamber includes a processing chamber configured to treat a substrate. The chamber further includes a substrate support. The high surface area finish is arranged on the substrate support. The chamber includes a top surface, a bottom surface and side surfaces. A removable plate portion includes the high surface area finish and is arranged adjacent to at least one of the top surface, the bottom surface and the side surfaces. 
     In other features, the chamber includes a loadlock. The loadlock includes an upper plate and a lower plate. The high surface area finish is located on at least one of a lower surface of the upper plate and an upper surface of the lower plate. The loadlock includes an upper plate, a lower plate, and a removable plate portion arranged adjacent to one of the upper plate and the lower plate. An outer surface of the removable portion includes the high surface area finish. 
     A substrate processing system includes a chamber configured to process a semiconductor substrate. At least one surface of the chamber includes a high surface area finish. A purge/vent system is configured to selectively supply purge gas over the high surface area finish of the at least one surface to trap particles in the high surface area finish without opening the chamber. The high surface area finish on the at least one surface of the chamber has an average pore size in a predetermined range from 1 micrometer to 10 micrometers. 
     In other features, the chamber includes a processing chamber configured to treat a substrate. The chamber further includes a substrate support. The high surface area finish is arranged on the substrate support. The chamber includes a top surface, a bottom surface and side surfaces. A removable plate includes the high surface area finish and is arranged adjacent to at least one of the top surface, the bottom surface and the side surfaces. The chamber includes a loadlock. The loadlock includes an upper plate and a lower plate. The high surface area finish is located on at least one of a lower surface of the upper plate and an upper surface of the lower plate. The loadlock includes an upper plate, a lower plate and a removable plate portion arranged adjacent to one of the upper plate and the lower plate. An outer surface of the removable portion includes the high surface area finish. 
     A method for operating a substrate processing system includes providing at least one surface of a chamber configured to process a semiconductor substrate with a high surface area finish; and selectively supplying purge gas over the high surface area finish of the at least one surface to trap particles in the high surface area finish without opening the chamber. The high surface area finish on the at least one surface of the chamber has a porosity within a predetermined range from 30-60%. The porosity is defined by a normalized density of the high surface area finish relative to an underlying native bulk material of the at least one surface of the chamber. 
     In other features, the chamber includes a processing chamber configured to treat a substrate. The chamber further includes a substrate support. The method includes arranging the high surface area finish on the substrate support. The chamber includes a top surface, a bottom surface and side surfaces. The method includes providing a removable plate portion including the high surface area finish; and arranging the removable plate portion adjacent to at least one of the top surface, the bottom surface and the side surfaces. 
     In other features, the chamber includes a loadlock. The loadlock includes an upper plate and a lower plate. The method further includes locating the high surface area finish on at least one of a lower surface of the upper plate and an upper surface of the lower plate. The loadlock includes an upper plate, a lower plate and a removable plate portion arranged adjacent to one of the upper plate and the lower plate. The method includes locating the high surface area finish on an outer surface of the removable plate portion. 
     In other features, the method includes opening the chamber and removing the removable plate portion. The method includes cleaning particulates from the removable plate portion; re-installing the removable plate portion; and closing the chamber. The method includes replacing the removable plate portion with another removable plate portion. 
     A method for operating a substrate processing system includes providing at least one surface of a chamber configured to process a semiconductor substrate with a high surface area finish without opening the chamber; and selectively supplying purge gas over the high surface area finish of the at least one surface to trap particles in the high surface area finish. The high surface area finish on the at least one surface of the chamber has an average pore size in a predetermined range from 1 micrometer to 10 micrometers. 
     In other features, the chamber includes a processing chamber configured to treat a substrate. The chamber further includes a substrate support. The method further includes arranging the high surface area finish on the substrate support. 
     In other features, the chamber includes a top surface, a bottom surface and side surfaces. The method further includes providing a removable plate portion including the high surface area finish; and arranging the removable plate portion adjacent to at least one of the top surface, the bottom surface and the side surfaces. 
     In other features, the chamber includes a loadlock. The loadlock includes an upper plate and a lower plate. The method further includes locating the high surface area finish on at least one of a lower surface of the upper plate and an upper surface of the lower plate. 
     In other features, the loadlock includes an upper plate, a lower plate and a removable plate portion arranged adjacent to one of the upper plate and the lower plate. The method includes locating the high surface area finish on an outer surface of the removable plate portion. 
     In other features, the method includes opening the chamber and removing the removable plate portion. The method includes cleaning particulates from the removable plate portion; re-installing the removable plate portion; and closing the chamber. The method includes replacing the removable plate portion with another removable plate portion. 
     Further areas of applicability of the present disclosure will become apparent from the detailed description, the claims and the drawings. The detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein: 
         FIG. 1  is a functional block diagram of an example of a substrate processing tool according to the prior art; 
         FIG. 2  is a side cross-sectional view of an example of a loadlock according to the prior art; 
         FIG. 3  is a plan view of an example of a loadlock bottom plate according to the prior art; 
         FIG. 4  is a side cross-sectional view of an example of a loadlock according to the present disclosure; 
         FIG. 5  is a plan view of an example of a loadlock bottom plate according to the present disclosure; 
         FIG. 6  is a side cross-sectional view of another example of a loadlock with a removable portion including a particle trapping surface according to the present disclosure; 
         FIG. 7  is a functional block diagram of an example of a system for removing particles according to the present disclosure; 
         FIG. 8  is a flowchart illustrating steps of a method for removing particles from a processing chamber or loadlock according to the present disclosure; and 
         FIG. 9  is a functional block diagram of an example of a processing chamber including one or more particle trapping surfaces. 
     
    
    
     In the drawings, reference numbers may be reused to identify similar and/or identical elements. 
     DETAILED DESCRIPTION 
     The present disclosure utilizes the pump/vent method to collide particles onto high surface area particle trapping surfaces that can trap the particles inside of the chambers. By trapping the particles in the high surface area particle trapping surfaces, the particles are prevented from travelling to the substrates being processed and defects are reduced. After a longer service interval, the high surface area particle trapping surfaces are removed, discarded and replaced, removed, cleaned and reinstalled or cleaned in situ. 
     In some examples, removable hardware such as a plate with the high surface area particle trapping surface is used and mounted to one or more chamber surfaces. After a longer service interval, the removable hardware is removed and replaced or removed, cleaned and reinstalled. In other words, the particle trapping surfaces are used to “clean” the chamber without requiring the chamber to be opened. As a result, MWBC may be increased. 
     In other examples, the particle trapping surface may be permanently integrated with one or more surfaces in the chambers and cannot be readily removed. The permanent particle trapping surfaces will require cleaning in the clean room. 
     In other examples, the particle trapping surface is integrated with removable components that have an existing alternative function and can be readily removed. Once removed, the particle trapping surface may be removed, cleaned and reinstalled or removed and replaced. Examples include wafer pedestals, wafer supports, and removable chamber top or bottom surfaces. 
     Using the systems and methods described herein will tend to decrease cost for one or more reasons. Time between cleans will be longer thereby decreasing the number of wet cleans. Furthermore, consumables in process modules may be unnecessarily replaced to maximize time between wet cleans. For example, the wet clean frequency due to the platform may be 25 k wafers and the process module consumables may have a usable lifetime of 30 k wafers. The customer typically replaces the process module consumables at the same time to ensure the entire system can go for another 25 k wafers. Otherwise the process module would have to be cleaned at 5 k wafers. In other words, 5 k wafers lifetime is lost. Fewer wet cleans translates into more time to run production (increased uptime). 
     Referring now to  FIGS. 2-3 , an example of a loadlock  60  according to the prior art is shown. In  FIG. 2 , the loadlock includes an upper plate  64  having a handle  65  attached thereto and a lower surface  66 . A lower plate  68  includes upper surfaces  70 ,  72  and  74 . The upper and lower plates  64  and  68  are arranged between outer walls  76 ,  78  defining an opening  80 . The surface  74  defines a ledge to support the substrate during use. A pump annulus  82  is provided below the lower plate  68 . A vent annulus  84  is provided around the upper plate  64 . In  FIG. 3 , a plan view of the lower surface  66  of the upper plate or an upper surface of the lower plate  68  is shown. 
     Referring now to  FIGS. 4-5 , an example of a loadlock  90  according to the present disclosure is shown. In  FIG. 4 , the loadlock  90  includes the upper plate  64  having a handle  65  attached thereto and a lower surface  66 . A lower plate  92  includes upper surfaces  94 ,  96  and  98  facing the lower surface  66 . The upper and lower plates  64  and  92 , respectively are arranged between walls  76 ,  78  defining the opening  80 . The surface  98  defines a ledge to support the substrate during transfer. A pump annulus  82  is provided around and below the lower plate  92 . A vent annulus  84  is provided around the upper plate  64 . In  FIG. 5 , a plan view of the lower plate  92  shows a high surface area finish  100  that acts as a particle trapping surface on one or more of the upper surfaces  94 ,  96  and  98 . 
     Referring now to  FIG. 6 , another example of a loadlock  104  is shown. In this example, a removable plate portion  114  is located adjacent to the lower plate  92 . The removable plate portion  110  includes one or more surfaces  114 ,  116  and  118  that are generally arranged adjacent to one or more of the upper surfaces  94 ,  96  and  98 , respectively. One or more of the surfaces  114 ,  116  and  118  may include the high surface area finish  100  that acts as a particle trapping surface. The removable plate portion  110  may be attached to the lower plate  92  using one or more fasteners  122 . As will be described further below, a purge/vent system may be used to direct purge gas along the high surface area finish  100  on the surfaces  114 ,  116  and/or  118 . As a result, particles are trapped and the loadlock may remain in service for a longer period before requiring maintenance. 
     As used herein, porosity may be used to characterize the surfaces having a high surface area finish. As used herein, porosity is defined as a normalized density relative to a native bulk material. For example only, stainless steel may be used for the chamber surface with the high surface area finish. In this example, porosity is defined by the normalized density of a stainless steel filter medium divided by the density of stainless steel. In some examples, the porosity is defined by density in a predetermined range from 30-60%. In other examples, the high surface area finish is defined by a surface with an average pore size in a range from 1-10 micrometers (μm). 
     Referring now to  FIG. 7 , a system  200  for removing particles from a loadlock or chamber is shown. The system  200  includes a loadlock or other processing chamber  210  in a substrate processing system. The loadlock or other processing chamber  210  includes a chamber surface with a fixed particle trapping surface  214  and/or a removable particle trapping surface  218 . The system  200  may employ the pump/vent method to remove particles from the loadlock or other processing chamber  210 . A purge gas source  230  may be supplied via a valve  234  to the chamber  210 . A valve  238 , a pump  242  and an exhaust system  246  may be used to vent the chamber  210 . A controller  250  may communicate with the valve  234 , the valve  238 , and the pump  242  to control the pump/vent cycling. 
     Referring now to  FIG. 8 , a method  300  for removing particles from a chamber is shown. At  310 , a chamber surface with fixed or removable particle trapping surface is arranged in a chamber of a substrate processing system. At  314 , control determines whether the system is ready for a purge/vent process. If not, control returns to  314 . Otherwise, control continues at  318  and determines whether the system is ready for wet cleaning of the particle trapping surface. If not, the purge/vent process is executed at  322  and control returns to  314 . 
     The system may be ready for wet cleaning of the chamber surface with particle trapping surface after a predetermined period, a predetermined number of purge/vent cycles, or using another event. When  318  is true, the chamber is opened and the chamber surface with the removable particle trapping surface is removed or the fixed particle trapping surface is cleaned in situ at  326 . At  330 , if the removable particle trapping surface is used, it is cleaned and replaced (or a spare is used). When the removable particle trapping surface is replaced or the fixed particle trapping surface is cleaned, the chamber is closed. Control returns to  314 . 
     Referring now to  FIG. 9 , an example of a substrate processing system  410  for removing mechanical particles using RF cycling and purging is shown. The substrate processing system  410  includes a processing chamber  412 . Gas may be supplied to the processing chamber  412  using a gas distribution device  414  such as showerhead or other device. A substrate  418  such as a semiconductor wafer may be arranged on a substrate support  416  during processing. The substrate support  416  may include a pedestal, an electrostatic chuck, a mechanical chuck or other type of substrate support. 
     A gas delivery system  420  may include one or more gas sources  422 - 2 ,  422 - 2 , . . . , and  422 -N (collectively gas sources  422 ), where N is an integer greater than one. Valves  424 - 1 ,  424 - 2 , . . . , and  424 -N (collectively valves  424 ), mass flow controllers  426 - 1 ,  426 - 2 , . . . , and  426 -N (collectively mass flow controllers  426 ), or other flow control devices may be used to controllably supply precursor, reactive gases, inert gases, purge gases, and mixtures thereof to a manifold  430 , which supplies the gas mixture to the processing chamber  412 . 
     A controller  440  may be used to monitor process parameters such as temperature, pressure etc. (using sensors) and to control process timing. The controller  440  may be used to control process devices such as the gas delivery system  420 , a pedestal heater  442 , and/or a plasma generator  446 . The controller  440  may also be used to evacuate the processing chamber  412  using a valve  450  and pump  452 . 
     The RF plasma generator  446  generates the RF plasma in the processing chamber. The RF plasma generator  446  may be an inductive or capacitive-type RF plasma generator. In some examples, the RF plasma generator  446  may include an RF supply  460  and a matching and distribution network  464 . While the RF plasma generator  446  is shown connected to the gas distribution device  414  with the pedestal grounded or floating, the RF generator  446  can be connected to the substrate support  416  and the gas distribution device  414  can be grounded or floating. 
     In  FIG. 9 , one or more particle trapping surfaces are integrated with removable components that have an existing alternative function and can be readily removed. For example only, a particle trapping surface  480  may be located on an upwardly-facing surface of the substrate support  416 . Alternately, removable plate portions  490  may be arranged on side walls of the processing chamber  412  or removable plate portions  494  and  496  may be arranged on bottom or top surfaces of the processing chamber  412 . The removable plate portions  490 ,  494  and/or  496  may include the particle trapping surfaces. As can be appreciated, the particle trapping surfaces can be integrated with existing structures or removable plate portions can be used. Fasteners or other mechanical attachments may be used to secure the removable plate portions as shown in  FIG. 6 . 
     Large particles (&gt;500 nm) are transported with the bulk flow of the purge gas. When the purge gas flow impinges on a surface, the particle experiences an inelastic collision with the surface. The particle physically deforms and becomes part of the surface. However the motion of small particles (&lt;100 nm) is not determined by the bulk gas flow. Rather, the small particles travel on a random walk throughout the gas (diffusion). The small particles will not have the same momentum as the large particles and therefore do not experience inelastic collision. Small particle can diffuse into a porous medium and then not find their way out. If the small particles collide with a surface, they can adhere by induced electrostatic forces (van der Waals). 
     The foregoing description is merely illustrative in nature and is in no way intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent upon a study of the drawings, the specification, and the following claims. As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean “at least one of A, at least one of B, and at least one of C.” It should be understood that one or more steps within a method may be executed in different order (or concurrently) without altering the principles of the present disclosure. 
     In some implementations, a controller is part of a system, which may be part of the above-described examples. Such systems can comprise semiconductor processing equipment, including a processing tool or tools, chamber or chambers, a platform or platforms for processing, and/or specific processing components (a wafer pedestal, a gas flow system, etc.). These systems may be integrated with electronics for controlling their operation before, during, and after processing of a semiconductor wafer or substrate. The electronics may be referred to as the “controller,” which may control various components or subparts of the system or systems. The controller, depending on the processing requirements and/or the type of system, may be programmed to control any of the processes disclosed herein, including the delivery of processing gases, temperature settings (e.g., heating and/or cooling), pressure settings, vacuum settings, power settings, radio frequency (RF) generator settings, RF matching circuit settings, frequency settings, flow rate settings, fluid delivery settings, positional and operation settings, wafer transfers into and out of a tool and other transfer tools and/or loadlocks connected to or interfaced with a specific system. 
     Broadly speaking, the controller may be defined as electronics having various integrated circuits, logic, memory, and/or software that receive instructions, issue instructions, control operation, enable cleaning operations, enable endpoint measurements, and the like. The integrated circuits may include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as application specific integrated circuits (ASICs), and/or one or more microprocessors, or microcontrollers that execute program instructions (e.g., software). Program instructions may be instructions communicated to the controller in the form of various individual settings (or program files), defining operational parameters for carrying out a particular process on or for a semiconductor wafer or to a system. The operational parameters may, in some embodiments, be part of a recipe defined by process engineers to accomplish one or more processing steps during the fabrication of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and/or dies of a wafer. 
     The controller, in some implementations, may be a part of or coupled to a computer that is integrated with the system, coupled to the system, otherwise networked to the system, or a combination thereof. For example, the controller may be in the “cloud” or all or a part of a fab host computer system, which can allow for remote access of the wafer processing. The computer may enable remote access to the system to monitor current progress of fabrication operations, examine a history of past fabrication operations, examine trends or performance metrics from a plurality of fabrication operations, to change parameters of current processing, to set processing steps to follow a current processing, or to start a new process. In some examples, a remote computer (e.g. a server) can provide process recipes to a system over a network, which may include a local network or the Internet. The remote computer may include a user interface that enables entry or programming of parameters and/or settings, which are then communicated to the system from the remote computer. In some examples, the controller receives instructions in the form of data, which specify parameters for each of the processing steps to be performed during one or more operations. It should be understood that the parameters may be specific to the type of process to be performed and the type of tool that the controller is configured to interface with or control. Thus as described above, the controller may be distributed, such as by comprising one or more discrete controllers that are networked together and working towards a common purpose, such as the processes and controls described herein. An example of a distributed controller for such purposes would be one or more integrated circuits on a chamber in communication with one or more integrated circuits located remotely (such as at the platform level or as part of a remote computer) that combine to control a process on the chamber. 
     Without limitation, example systems may include a plasma etch chamber or module, a deposition chamber or module, a spin-rinse chamber or module, a metal plating chamber or module, a clean chamber or module, a bevel edge etch chamber or module, a physical vapor deposition (PVD) chamber or module, a chemical vapor deposition (CVD) chamber or module, an atomic layer deposition (ALD) chamber or module, an atomic layer etch (ALE) chamber or module, an ion implantation chamber or module, a track chamber or module, and any other semiconductor processing systems that may be associated or used in the fabrication and/or manufacturing of semiconductor wafers. 
     As noted above, depending on the process step or steps to be performed by the tool, the controller might communicate with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, neighboring tools, tools located throughout a factory, a main computer, another controller, or tools used in material transport that bring containers of wafers to and from tool locations and/or load ports in a semiconductor manufacturing factory.