Patent Publication Number: US-2017370017-A1

Title: Wet processing system and method of operating

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to methods and systems for electro-chemical deposition including electroplating of various workpieces, such as semiconductor substrates. 
     Electrochemical deposition systems, or workpiece surface wet process conditioning systems, are well known for both wafer type geometries (e.g., semiconductor wafers), characterized by relatively rigid silicon circular disks, and for panel type geometries, characterized by much larger and more flexible rectangular shaped substrates. There is a need in the industry for equipment that can process the panel workpiece with a resulting precision of deposited metal comparable to that resulting from the various wafer equipment, and yet has the economical productivity comparable or better than existing panel processing equipment. 
     Electrochemical deposition (ECD), among other processes, is used as a manufacturing technique for the application of films to various structures and surfaces, such as to semiconductor wafers and silicon work pieces, or substrates. Such films can include metal and metal alloys, such as tin, silver, nickel, copper, or other metal layers, or alloys thereof. Electrochemical deposition involves positioning a substrate within a solution that includes metal ions, and then applying an electrical current to cause metal ions from the solution to be deposited on the substrate. Typically, electrical current flows between two electrodes, namely, between a cathode and an anode. When a substrate is used as the cathode, metal can be deposited thereon. A plating solution can include one or more metal ion types, acids, chelating agents, complexing agents, and any of several other types of additives that assist with plating a particular metal. Such additives can help enable adhesion and uniform plating, and reduce film stress, among other benefits. As plating occurs, metal from the plating solution is consumed and thus needs to be replaced to continue electrochemical deposition operations. 
     In panel processing, conventional systems use a continuous or serial process conveyor type of handling system with panel orientation either horizontal or vertical. As indicated above, panel processing systems, in part as a result of their conveyor systems, suffer from poor process uniformity and particle generation. More generally, these systems suffer from poor environment control. Thus, the inventors have recognized there is a need for improved panel handling and deposition uniformity. 
     SUMMARY 
     Embodiments relate to methods and systems for electrochemical deposition including electroplating of various workpieces, such as semiconductor substrates and panels. 
     An important feature of systems used for electrochemical deposition is their ability to produce films with uniform and repeatable characteristics such as film thickness, composition, and profile relative to an underlying workpiece profile. Electrochemical deposition systems can use a primary electrolyte (process electrolyte) that requires replenishment upon depletion. By way of example, in metal applications the replenishment of a metal cation solution may be required upon depletion. And, when such replenishment cannot be performed in-situ, the replenishment procedure may be expensive as a function of the application, and may require significant down time of the electrochemical deposition tool or sub module for service and process re-qualification, which adversely affects the cost of ownership of the deposition tool. 
     Techniques disclosed herein, among others, include an electrochemical deposition apparatus that provides robust workpiece handling, improved environment control, a simplified electrolyte circulation system, including improved chemical management for more reliable and uniform plating, as well as short maintenance times for greater tool availability. 
     According to one embodiment, an electrochemical deposition system having two or more electrochemical deposition modules arranged on a common platform and configured for depositing one or more metals on a substrate is described. Each electrochemical deposition module includes an anode compartment configured to contain a volume of anolyte fluid, a cathode compartment configured to contain a volume of catholyte fluid, and a membrane separating the anode compartment from the cathode compartment. Each electrochemical deposition module further includes a loading port configured to receive a set of flexible workpieces, each flexible workpiece defining through holes to be filled with metal, and a loader module configured to receive a flexible workpiece from the loading port and position the flexible workpiece in a workpiece holder while holding the flexible workpiece using an air cushion on each opposing planar surface of the flexible workpiece. The workpiece holder has a header member separating first and second leg members, wherein the workpiece holder is configured to hold opposing edges of the flexible workpiece between the first and second leg members via a clamping mechanism that applies electrical contacts to the opposing planar surfaces of the flexible workpiece with the electrical contacts surrounded by an elastomeric seal, and the header member provides tension to the flexible workpiece when held by the workpiece holder. Further yet, each electrochemical deposition module includes a transportation mechanism configured to transport flexible workpieces, via workpiece holders, from the loader module to a given electrochemical deposition module and lower a given workpiece into the given electrochemical deposition module. An electrical system is configured to apply an electrical current to each opposing planar surface of the flexible workpiece when held within the given electrochemical deposition module such that each opposing planar surface is plated with metal and the through holes are filled with metal. An unloader module is configured to remove the flexible workpiece from the workpiece holder and convey the flexible workpiece to an unloading port configured to receive the set of flexible workpieces. 
     The systems and techniques disclosed herein provide several advantages. Robust workpiece handling and environment control, as well as efficient workpiece flows, enable improved process performance and reduced particle contamination, including process uniformity and yield. Simplified chemical flow management eliminates cost and complexity. Moreover, having chemical generation systems on-board or off board proximate the processing system provides easier management of chemical concentration. 
     Of course, the order of discussion of the different steps and features as described herein has been presented for clarity sake. In general, these steps can be performed in any suitable order. Additionally, although each of the different features, techniques, configurations, etc. herein may be discussed in different places of this disclosure, it is intended that each of the concepts can be executed independently of each other or in combination with each other. Accordingly, the present invention can be embodied and viewed in many different ways. 
     Note that this summary section does not specify every embodiment and/or incrementally novel aspect of the present disclosure or claimed invention. Instead, this summary only provides a preliminary discussion of different embodiments and corresponding points of novelty over conventional techniques. For additional details and/or possible perspectives of the invention and embodiments, the reader is directed to the Detailed Description section and corresponding figures of the present disclosure as further discussed below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete appreciation of various embodiments of the invention and many of the attendant advantages thereof will become readily apparent with reference to the following detailed description considered in conjunction with the accompanying drawings. The drawings are not necessarily to scale, with emphasis instead being placed upon illustrating the features, principles and concepts. 
         FIG. 1  illustrates a schematic representation of an electrochemical deposition system according to an embodiment. 
         FIGS. 2A and 2B  provide views of an electrochemical deposition module according to another embodiment. 
         FIG. 3  provides a cross-sectional view of an electrochemical deposition module according to another embodiment. 
         FIG. 4  provides a perspective view of an electrochemical deposition system according to yet another embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Techniques disclosed herein include an electrochemical deposition apparatus that provides a robust workpiece handling system, a simplified circulation system, an improved chemical management system for more reliable and uniform plating, as well as short maintenance times for greater tool availability 
     Systems and techniques disclosed herein can be embodied as an electrochemical deposition systems or module of a system, or workpiece surface wet process conditioning system. Example systems include a wet processing system capable of treating or conditioning workpieces of various types and sizes, including both wafer type geometries (e.g., semiconductor wafers), characterized by relatively rigid silicon circular disks, and panel type geometries, characterized by much larger and more flexible rectangular shaped substrates. One embodiment includes an electrochemical deposition apparatus for depositing metal onto a substrate.  FIG. 1  illustrates a schematic representation of an electrochemical deposition system  100  according to an embodiment. The electrochemical deposition system  100  includes two or more processing modules, to be described below, such as electrochemical deposition modules, arranged on a common platform and configured for depositing one or more metals on a workpiece. Each processing module, e.g., each electrochemical deposition module, includes an anode compartment configured to contain a volume of anolyte fluid, a cathode compartment configured to contain a volume of catholyte fluid, and a membrane separating the anode compartment from the cathode compartment. 
     The electrochemical deposition system  100  has a loading port to receive a set of workpieces, including a loader module  110  for receiving the workpieces that enter electrochemical deposition system  100  through load/input stage  112  and loading each received workpiece into a workpiece holder  125 , such as a flexible panel holder (PH). Each workpiece may include a flexible panel, e.g., a flexible, rectangular panel of various dimensions. The workpiece may include one or more blind holes, or one or more through-holes to be filled with material, such as metal. The filling of the one or more holes can include one-side deposition, i.e., deposition from one side of the workpiece, or two-sided deposition, i.e., deposition from both sides of the workpiece (e.g., in the case where the hole is a through-hole). 
     To control the environment surrounding each workpiece during loading into the workpiece holder, the loader may use an apparatus to execute substantially contact-free handling of the workpiece by applying an air cushion against each opposing planar surface of the flexible workpiece during workpiece movement and loading. According to some embodiments, the workpiece holder  125  can include a gripable header member separating first and second leg members, wherein the workpiece holder is configured to hold opposing edges of the flexible workpiece between the first and second leg members via a clamping mechanism that optionally applies electrical contacts to the opposing planar surfaces of the flexible workpiece with the electrical contacts surrounded by an elastomeric seal. The header member can also provide tension to the flexible workpiece when held by the workpiece holder  125 . 
     Further yet, the electrochemical deposition system  100  includes a transportation mechanism configured to transport flexible workpieces, via workpiece holder  125 , from the loader module  110  to a given processing module, e.g., electrochemical deposition module, and lower a given workpiece into the given processing module. For example, referring to  FIG. 1 , once the workpiece holder  125 , designated for processing, is loaded, it can proceed along a process path  115  (see PH process path in  FIG. 1 ) to be pre-processed, as needed, in one or more pre-processing modules  120 ; processed in one or more processing modules  130 ,  132 ,  134 ,  136 ,  138 ; and post-processed, as needed, in one or more post-processing modules  140 . Pre-processing may include, but not be limited to, cleaning and/or wetting the workpiece to be processed. Processing may include, but not be limited to, depositing material, such as metal, onto the workpiece. And, post-processing may include, but not be limited to, rinsing and/or drying the workpiece. 
     The electrochemical deposition system  100  further includes an unloader module configured to remove the flexible workpiece from the workpiece holder and convey the flexible workpiece to an unloading port configured to receive the set of flexible workpieces. For example, in some embodiments shown in  FIG. 1 , following processing, the workpiece holder  125 , carrying a processed workpiece, can proceed to an unloader module  150 , wherein each workpiece is unloaded and transferred to an unload/output stage  152  for exiting electrochemical deposition system  100 . Once unloaded, the workpiece holder  125  can return to the loader module  110  along return path  155  (see PH return path in  FIG. 1 ) to receive another workpiece. Note that multiple workpiece holders can be used, with some workpiece holders held in a storage buffer. A more detailed description of an example workpiece holder is found in U.S. patent application Ser. No. 15/193,595, filed on Jun. 27, 2016, which is herein incorporated by reference in its entirety. A more detailed description of an example workpiece loader module is found in U.S. patent application Ser. No. 15/193,890, filed on Jun. 27, 2016, which is herein incorporated by reference in its entirety. 
     The electrochemical deposition system  100  further includes a chemical management system  160  for managing processing fluid in the one or more processing cells, i.e., modules  120 ,  130 ,  132 ,  134 ,  136 ,  138 ,  140 . Chemical management may include, but not be limited to, supplying, replenishing, dosing, heating, cooling, circulating, recirculating, storing, monitoring, draining, abating, etc. Further yet, the electrochemical deposition system  100  includes an electrical management system  170  for controlling the operability of electrochemical deposition system  100 . Electrical management may include, but not be limited to, scheduling, coordinating, monitoring, adjusting, communicating, etc. For example, the electrical management system  170  can transmit and receive signals in accordance with computer encoded instructions to control workpiece movement through electrochemical deposition system  100 , or control chemical properties, such as chemical composition, temperature, flow rate(s), etc., of the plural modules  120 ,  130 ,  132 ,  134 ,  136 ,  138 ,  140 . Additionally, the electrical management system  170  can be configured to apply an electrical current to one or both opposing planar surfaces of the flexible workpiece when held within the given electrochemical deposition module. In doing so, one or both opposing surfaces can be plated with metal and blind holes and/or through-holes are filled with metal. 
     Turning now to  FIG. 2A , a view of an electrochemical deposition module having plural ECD cells is provided according to another embodiment. As shown,  FIG. 2A  provides a top view of an anolyte reservoir  230  configured to contain a volume of anolyte fluid  232 , plural cathode compartments configured to contain a volume of catholyte fluid, and a membrane separating the anolyte fluid  232  from the plural cathode compartments  200 . The anolyte reservoir  230  includes an anolyte reservoir, containing the anolyte fluid  232 , within which the plural cathode compartments  200  are positioned. The anolyte reservoir  230  may include an anolyte supply and storage reservoir  262 , wherein anolyte can be recirculated, replenished, and/or reconditioned, and then exchanged with the anolyte reservoir  230  using anolyte pumping system  264 . Furthermore, the anolyte reservoir  230  may include a catholyte supply and storage reservoir  266 , wherein catholyte can be recirculated, replenished, and/or reconditioned, and then exchanged with the plural cathode compartments  200  using catholyte pumping system  268 . Chemical management system  260  can interface with the anolyte and catholyte supply and storage reservoirs  262 ,  266 , and among other things, manage fluid levels, chemical composition, chemical quality, chemical temperature, chemical dosing, etc. For example, the chemical management system  260  may rejuvenate the anolyte and/or catholyte solution, including adding or replacing water, acid, anion solution, cation solution, chelating agents, complexing agents, leveling agents, accelerating or decelerating agents, etc. 
     According to some embodiments, workpiece W can include a flexible, rectangular substrate having dimensions ranging from approximately 50 cm by 50 cm to 100 cm by 100 cm in size. Consequently, the fluid depth in the anolyte reservoir  230  may range from 90 cm to 150 cm deep, and the width of the anolyte reservoir  230  may range from 90 cm to 150 cm. Each ECD module may be designed comparatively narrow, for example, the width may be designed to be less than 20 cm anode-to-anode, or anode-to-cathode. Consequently, plural cathode comparts  200  (ECD modules) can be arranged within an anolyte reservoir ranging up to 120 cm in length. Immersion or partial immersion of plural cathode compartments  200  within the anolyte reservoir  230  provides an efficient utilization of space. And thus, one advantage, among others, of this embodiment is a single container of anolyte fluid  232  with a simplified chemical and fluid management system serving plural ECD modules in an economical arrangement, conserving expenditure for equipment, chemistry, and factory footprint. 
       FIG. 2B  provides a top view of cathode compartment  200  positioned between opposing anode assemblies  240 ,  241 . A workpiece holder  215  containing a workpiece W is positioned within a frame  210  which advantageously and repeatably positions the workpiece holder  215  precisely within plus or minus 0.1 to 1.0 mm, preferably within plus or minus 0.5 mm, with respect to other important elements of the ECD module which influence the uniformity of the electric field and fluid flow field at the surface of the workpiece W. The cathode compartment  200  can include electric field shaping elements  201 ,  204  positioned between approximately 3 and 10 mm of the surfaces of the workpiece W, preferably 4 mm from the surfaces of the workpiece W. The cathode compartment  200  can further include fluid agitating elements  202 ,  205  positioned proximate the surfaces of the workpiece W, preferably within 10 mm of the surfaces of the workpiece W. 
     Ion-exchange membranes  203 ,  206  define the boundaries between the cathode compartment  200  and the anode compartment containing the opposing anode assemblies  240 ,  241 , and provide separation between the anolyte fluid  232  within the anode compartment and catholyte  220  in the cathode compartment  200 . One benefit, among others, is the compact geometry provided by defining the boundaries between the anolyte fluid  232  and the catholyte  220 , wherein during operation the fluid pressure of anolyte fluid  232  and catholyte  220  are balanced across the flexible, ion-exchange membrane so that it is not necessary to incorporate an extensive wall structure to contain the hydrostatic pressure of the catholyte for each workpiece W. 
     Each opposing anode assembly  240 ,  241  can include a multi-zone anode  242 , e.g., anodes arranged as rings in a radial direction, or anodes arranged on a grid in orthogonal directions, for example. In this embodiment, two opposing anode assemblies  240 ,  241  are shown opposing the cathode compartment. However, in other embodiments, a single anode assembly may face the cathode compartment. 
       FIG. 3  provides a detailed, cross-sectional view of an ECD module according to an embodiment. Workpiece holder  315  positions workpiece W between electric field shaping elements  330 , fluid agitating elements  310 , ion-exchange membranes  325  held by support structure  320 , and anode assemblies  340  holding anodes  342 . As illustrated, the electric field shaping elements  330  extend proximate the exposed surfaces of the workpiece W, and are arranged to improve uniformity of the deposition process. Additionally, as illustrated, the fluid agitating elements  310  extend proximate the exposed surfaces of the workpiece W, and are arranged to increase fluid shear and enhance mass, momentum, and thermal transport near the exposed surfaces of the workpiece W. 
       FIG. 4  provides a perspective view of an electrochemical deposition system according to yet another embodiment. The electrochemical deposition system  500  includes loader module  510  and unloader module  550  with plural processing modules  520 ,  530 ,  540  disposed there between. Processing modules  520  may include pre-processing modules such as pre-rinse modules. Processing modules  530  may include electrochemical deposition modules. And, processing modules  540  may include post-processing modules such as rinse or drying modules. While the loader module  510  and the unloader module  550  are shown to be at distal ends of the electrochemical deposition system  500 , these loading and unloading modules may be arranged proximate the same end of the overall system. Workpiece W can be loaded into workpiece holder  525 , translated via workpiece transfer system  560 , and oriented for positioning within the plural processing modules  520 ,  530 ,  540 . 
     Using systems herein, an electrochemical deposition system can be created that uses plating solution efficiently, and has a relatively small foot print compared to conventional deposition systems. For example, each electrochemical deposition module can be configured to hold less than about thirty liters of plating solution. In some embodiments, the common platform can includes less than about 16 electrochemical deposition modules, and can be configured to plate 100 flexible workpieces per hour. The common platform can cover a floor space of less than about 250 square feet. Thus, systems herein can provide relatively high throughput with a relatively small system and relatively little plating solution used per workpiece. 
     In the preceding description, specific details have been set forth, such as a particular geometry of a processing system and descriptions of various components and processes used therein. It should be understood, however, that techniques herein may be practiced in other embodiments that depart from these specific details, and that such details are for purposes of explanation and not limitation. Embodiments disclosed herein have been described with reference to the accompanying drawings. Similarly, for purposes of explanation, specific numbers, materials, and configurations have been set forth in order to provide a thorough understanding. Nevertheless, embodiments may be practiced without such specific details. Components having substantially the same functional constructions are denoted by like reference characters, and thus any redundant descriptions may be omitted. 
     Various techniques have been described as multiple discrete operations to assist in understanding the various embodiments. The order of description should not be construed as to imply that these operations are necessarily order dependent. Indeed, these operations need not be performed in the order of presentation. Operations described may be performed in a different order than the described embodiment. Various additional operations may be performed and/or described operations may be omitted in additional embodiments. 
     “Substrate” or “target substrate” as used herein generically refers to an object being processed in accordance with the invention. The substrate may include any material portion or structure of a device, particularly a semiconductor or other electronics device, and may, for example, be a base substrate structure, such as a semiconductor wafer, reticle, or a layer on or overlying a base substrate structure such as a thin film. Thus, substrate is not limited to any particular base structure, underlying layer or overlying layer, patterned or un-patterned, but rather, is contemplated to include any such layer or base structure, and any combination of layers and/or base structures. The description may reference particular types of substrates, but this is for illustrative purposes only. 
     Those skilled in the art will also understand that there can be many variations made to the operations of the techniques explained above while still achieving the same objectives of the invention. Such variations are intended to be covered by the scope of this disclosure. As such, the foregoing descriptions of embodiments of the invention are not intended to be limiting. Rather, any limitations to embodiments of the invention are presented in the following claims.