Patent Grant
11214890
The present technology relates to cleaning operations in semiconductor processing. More specifically, the present technology relates to systems and methods that perform in situ cleaning for electroplating systems.
Integrated circuits are made possible by processes which produce intricately patterned material layers on substrate surfaces. After formation, etching, and other processing on a substrate, metal or other conductive materials are often deposited or formed to provide the electrical connections between components. Because this metallization may be performed after many manufacturing operations, problems caused during the metallization may create expensive waste substrates or wafers. One common problem is non-uniform formation of metal across a substrate surface.
Uniformity issues during metallization may be caused from a number of situations related to the process or the equipment. One example is plating on components of the chamber that are or become conductive, and which may cause local loss of metal on the substrate. Material may be plated on the contact ring, contact seal, or any other component that may be within the system. This errant formation may limit the amount of plating on the substrate, which can lead to insufficient plating, increased cost, and device failure.
Thus, there is a need for improved systems and methods that can be used to produce high quality devices and structures. These and other needs are addressed by the present technology.
The present technology may include systems and methods for cleaning electroplating system components, which may include a seal cleaning assembly incorporated with an electroplating system. The seal cleaning assembly may include an arm pivotable between a first position and a second position. The arm may be rotatable about a central axis of the arm. The seal cleaning assembly may also include a cleaning head including a bracket portion coupled with a distal portion of the arm. The cleaning head may be characterized by a front portion formed to interface with a seal of the electroplating apparatus. The cleaning head may define a trench along the front portion, and the cleaning head may define a plurality of fluid channels through the cleaning head, each fluid channel of the plurality of fluid channels fluidly accessing a backside of the trench.
In some embodiments the front portion of the cleaning head may be at least partially characterized by an arcuate profile configured to accommodate an annular seal. The cleaning head may also include a contact pin at least partially extending through the trench and configured to be in direct contact with the seal. The cleaning head may also include a clearance pin at least partially extending through the trench and configured to define a gap between the clearance pin and the seal when the contact pin is in direct contact with the seal. The plurality of fluid channels of the cleaning head may include a first channel fluidly accessing a first position along the trench, and may include a second channel fluidly accessing a second position along the trench radially offset from the first position in a direction of rotation of the seal. The clearance pin may be positioned between the first position and the second position. In some embodiments the cleaning head may be or include a hydrophobic material.
Embodiments of the present technology additionally encompass electroplating systems that may include a system head having a rotor. The system head may be configured to hold a substrate for processing. The systems may include a seal positioned on the rotor. The systems may include a head lifter coupled with the system head and configured to position the system head. The systems may also include a seal cleaning assembly. The seal cleaning assembly may include an arm pivotable between a first position and a second position where a distal portion of the arm may be vertically aligned with an interior region of the system head. The arm may be rotatable about a central axis of the arm. The seal cleaning assembly may also include a cleaning head including a bracket portion coupled with a distal portion of the arm. The cleaning head may be characterized by a front portion formed to interface with an interior surface of the seal. The cleaning head may define a trench along the front portion, and the cleaning head may define a plurality of fluid channels through the cleaning head. Each fluid channel of the plurality of fluid channels may fluidly access a backside of the trench.
In some embodiments, the arm may be located in the second position, and the distal portion of the arm may be configured to rotate the cleaning head from a retracted position into direct contact with the seal. The system may include a torque-controlled motor configured to drive the arm and maintain contact between the cleaning head and the seal while the rotor rotates the seal across the cleaning head. The seal may be characterized by an annular form, and the front portion of the cleaning head may be at least partially characterized by an arcuate profile configured to accommodate an inner annular sidewall of the seal. The cleaning head may also include a contact pin at least partially extending through the trench and configured to be in direct contact with the seal during a cleaning operation. The cleaning head may also include a clearance pin at least partially extending through the trench and configured to define a gap between the clearance pin and the seal when the contact pin is in direct contact with the seal. The plurality of fluid channels may include a first channel fluidly accessing a first position along the trench and a second channel fluidly accessing a second position along the trench radially offset from the first position in a direction of rotation of the seal. The clearance pin may be positioned between the first position and the second position. The system may include a fluid delivery tube extending along the arm and configured to provide a fluid to the first channel. The system may also include a fluid removal tube extending along the arm and configured to remove the fluid from the second channel. In some embodiments a vacuum may be maintained through the fluid removal tube during operation.
Embodiments of the present technology may also encompass methods of cleaning an electroplating system contact seal. The methods may include delivering an acidic solution in a first fluid channel of a cleaning head. The cleaning head may be positioned to physically contact the electroplating system contact seal. The methods may include rotating the electroplating system contact seal across the cleaning head. The methods may also include extracting the acidic solution from the cleaning head through a second fluid channel radially offset from the first fluid channel in a direction of rotation of the electroplating system contact seal. In some embodiments the acidic solution may be substantially maintained within a volume defined in part by an inner surface of the electroplating system contact seal, a trench formed within a front portion of the cleaning head, and a contact pin at least partially extending through the trench proximate a leading edge of the cleaning head in a direction of rotation of the electroplating system contact seal.
Such technology may provide numerous benefits over conventional technology. For example, the present technology may reduce cleaning times by allowing in situ cleaning of a contact seal to be performed. Additionally, the apparatus used may facilitate an improved cleaning of the contact seal without compromising other system components with the cleaning solution. These and other embodiments, along with many of their advantages and features, are described in more detail in conjunction with the below description and attached figures.
A further understanding of the nature and advantages of the disclosed embodiments may be realized by reference to the remaining portions of the specification and the drawings.
Several of the figures are included as schematics. It is to be understood that the figures are for illustrative purposes, and are not to be considered of scale unless specifically stated to be of scale. Additionally, as schematics, the figures are provided to aid comprehension and may not include all aspects or information compared to realistic representations, and may include exaggerated material for illustrative purposes.
In the figures, similar components and/or features may have the same numerical reference label. Further, various components of the same type may be distinguished by following the reference label by a letter that distinguishes among the similar components and/or features. If only the first numerical reference label is used in the specification, the description is applicable to any one of the similar components and/or features having the same first numerical reference label irrespective of the letter suffix.
Various operations in semiconductor manufacturing and processing are performed to produce vast arrays of features across a substrate. As layers of semiconductors are formed, vias, trenches, and other pathways are produced within the structure. These features may then be filled with a conductive or metal material that allows electricity to conduct through the device from layer to layer. As device features continue to shrink in size, so too does the amount of metal providing conductive pathways through the substrate. As the amount of metal is reduced, the quality and uniformity of the fill may become more critical to ensure adequate electrical conductivity through the device. Accordingly, manufacturing may attempt to reduce or remove imperfections and discontinuities in the pathways.
Electroplating operations may be performed to provide conductive material into vias and other features on a substrate. Electroplating utilizes an electrolyte bath containing ions of the conductive material to electrochemically deposit the conductive material onto the substrate and into the features defined on the substrate. The substrate on which metal is being plated operates as the cathode. An electrical contact, such as a ring or pins, may allow the current to flow through the system. This contact may be protected from the electrolyte by a seal, which may prevent metal from being plated on other conductive components. The seal is often a non-conductive material, however, over time the seal may become conductive due to residues formed on the seal during plating operations. When sufficiently conductive, plating may occur on the seal, which may reduce local plating on the substrate, causing uniformity issues, which may result in scrapped substrates or wafers.
Conventional technologies often halt operations between wafers to clean residues from this seal. The system may be partially disassembled, and the seal may be cleaned and scrubbed manually before being replaced in the tool. This process is time consuming, and abrasive scrubbing may further roughen the seal surfaces increasing the amount of conductive residue that may remain on the seal during processing.
The present technology overcomes these issues by incorporating a cleaning system that may perform an in situ clean of the seal. The system may include a nozzle or head that may be extended against the seal, and a cleaning solution may be flowed against the seal to remove any residues. By utilizing cleaning systems according to the present technology, cleaning may be performed more easily, and surface damage to the seal may be limited or reduced. After describing an exemplary chamber for which embodiments of the present technology may be performed, the remaining disclosure will discuss aspects of the systems and processes of the present technology.
Turning to
As previously explained, residues may form on the seal during electroplating operations. In some embodiments of the present technology, subsequent a plating operation, the substrate may be removed, and the seal may be cleaned. The seal may be cleaned on the same platform on which the bowl resides, or the head may be repositioned to a separate module either associated with or connected to system 20. Head 22 may be inverted, and a seal cleaning assembly may be used to clean the seal while the seal is still connected with the head.
As illustrated, seal cleaning assembly 300 may include an arm 305, and a cleaning head 310. Arm 305 may be a swing arm or other device associated with the electroplating system or a maintenance system for the head, and may be pivotable between a number of positions including a first position, which may be retracted, and a second position, which may be an operational position and may position a distal portion of arm 305, with which cleaning head 310 may be coupled, at a location that may be vertically aligned with an interior region of the system head 22. Arm 305 may also be rotatable about a central axis of the arm, which may allow the cleaning head to be raised and lowered to an operational position in which the cleaning head may be in contact with a seal. Arm 305 may be an L-shaped or otherwise retractable or extendable arm, and may be coupled with a torque-controlled motor, which may be incorporated with the arm or connected with the arm. The torque-controlled motor may drive the arm between the first and second positions, and may also be configured to maintain contact between the cleaning head and the seal to be cleaned.
Arm 305 may also include one or more fluid delivery tubes 307a or fluid removal tubes 307b that may extend along the arm. The tubes may be coupled with one or more reservoirs or other materials that may be used for the cleaning operation, and may couple or fluidly connect with cleaning head 310. For example, fluid delivery tube 307a may provide one or more cleaning solutions into the cleaning head, while fluid removal tube 307b may remove the cleaning solution subsequent interaction with the seal to be cleaned. Cleaning head 310 may allow the cleaning solution to be delivered to and removed from the seal without contacting other chamber components, dripping, or otherwise interacting with system head 22. The seal contact and cleaning operations will be described in more detail below.
Cleaning head 310 may be multiple components coupled together, or may be a single piece machined design that incorporates one or more aspects in the design. Cleaning head 310 may include a bracket portion 312, by which the cleaning head 310 may be coupled with arm 305, such as with a distal portion of arm 305. The bracket portion 312 may be coupled with the head rigidly with any number of components including fastening components, adhesive, or the bracket portion may include a form configured to accommodate snap-fitting the cleaning head on the arm. Any number of aspects of the arm or the cleaning head bracket portion may be adjusted to provide a coupling between the components.
A front portion 314 of cleaning head 310 may extend from bracket portion 312 in a first direction, and a back portion 316 of cleaning head 310 may extend from bracket portion 312 in a second direction opposite the front portion. Front portion 314 may be formed to interface with a seal of the electroplating system head. For example, the contact seal may be an annular component, and thus may be characterized by a curved profile along the inner and outer surfaces. Accordingly, front portion 314 may be at least partially characterized by an arcuate profile configured to accommodate the curvature of the seal. This may allow an improved contact to be afforded between the components to reduce the opportunity for fluid leaks or dripping.
Cleaning head 310 may define a trench 318 along the front portion 314. Trench 318 may be defined by an upper sidewall 320 and a lower sidewall 322, and may face the seal to be cleaned. One or both of the upper sidewall 320 and the lower sidewall 322 may exhibit the arcuate profile in embodiments. For example, in some embodiments lower sidewall 322 may exhibit an arcuate profile along the front portion 314 of the cleaning head 310. The lower sidewall may be characterized by a curvature equivalent to the curvature of the seal to limit any fluid leakage out of the trench through a space formed between the components.
Cleaning head 310 may be made of any number of materials or combinations of materials. In some embodiments, the cleaning head 310 may include a polymeric material that may be resistant to damage from cleaning solutions that may be used. For example, as will be explained in relation to the operational method below, the cleaning solutions may include an acidic solution in some embodiments. Accordingly, cleaning head 310 may include materials that are resistant to acidic solutions that may flow through the cleaning head. Additionally, water, either in the acidic solutions or with a separate delivery, may be flowed through the cleaning head 310. In some embodiments cleaning head 310 may include a hydrophobic material that may resist wetting by the cleaning fluids, and may facilitate movement and removal of the cleaning fluids through the cleaning head 310. By utilizing hydrophobic materials, the cleaning fluid may better fill the volume of the trench because it may be repelled from the cleaning head forming a high contact angle of the cleaning solution on the surfaces of the cleaning head, such as greater than 90°. This may ensure that the entire surface of the seal is contacted by the cleaning solution. For example, cleaning head 310 may be or include a similar or identical material to the seal to be cleaned, and may be any of the materials previously described. Cleaning head 310 may also be or include a fluoropolymer, including polyvinyl fluorides, fluoroethylene compounds including polytetrafluoroethylene, fluoropropylene compounds, and other compounds that may resist any materials used in electroplating or in the cleaning operations to be discussed.
Previously described
The cleaning head may include one or more contact pins that may interact with the seal to be cleaned. As illustrated, cleaning head 310 may contact seal 510 on contact pin 328 and contact pin 330. In operation, the system head rotor may rotate seal 510 across cleaning head 310. The direction of rotation as illustrated may begin at a leading edge 332 of cleaning head 310 and extend laterally or radially along the cleaning head to trailing edge 334. Contact pin 328 may at least partially extend through trench 318, and may be positioned vertically through front portion 314 of cleaning head 310. Contact pin 328 may be positioned proximate leading edge 332 of cleaning head 310. The contact pin 328 may be configured to be in direct contact with seal 510 during a cleaning operation. Additionally, contact pin 330 may be identical to contact pin 328, and may be positioned proximate trailing edge 334 of cleaning head 310 in the direction of rotation of seal 510 across the cleaning head. By having the contact pins extend only partially within trench 318 in some embodiments, the seal may at least partially recess within the trench both above and below the seal. Accordingly, a cleaning volume may be defined within trench 318 between the first contact pin 328, the seal 510, and the second contact pin 330. This volume may be configured to maintain cleaning fluid delivered through the fluid channels of the cleaning head to limit or prevent any leakage from the cleaning head.
Cleaning head 310 may also include a clearance pin 336 positioned between the first contact pin 328 and the second contact pin 330. Clearance pin 336 may at least partially extend through the trench 318 similar to the contact pins. Unlike the contact pins, clearance pin 336 may not contact seal 510 in some embodiments. Clearance pin 336 may instead define a gap between the clearance pin and the seal when the contact pins are in direct contact with the seal 510. Consequently, clearance pin 336 may facilitate contact between a delivered cleaning fluid and the seal to ensure complete wetting of the seal during the seal rotation. As previously described, the components of cleaning head 310 may be hydrophobic, and thus depending on the gap distance between the trench and the seal, cleaning fluid may flow from a fluid delivery channel to a fluid removal channel without contacting the seal, or intermittently contacting the seal.
By including a clearance pin 336, a reduced gap may be maintained that may be utilized to ensure contact entirely along the surface of the seal as it rotates across the cleaning head. In some embodiments, the gap may be less than or about 1 cm, and may be less than or about 9 mm, less than or about 8 mm, less than or about 7 mm, less than or about 6 mm, less than or about 5 mm, less than or about 4 mm, less than or about 3 mm, less than or about 2 mm, less than or about 1 mm, less than or about 0.5 mm, less than or about 0.2 mm, or less, depending on the size of the system, and surfaces to be cleaned. Contact pins 328, 330 and clearance pin 336 may be similar or different materials from the seal or cleaning head, and may be or include any of the materials previously described. The pins may be common plastics including polyethylene, or any other long chain polymeric material, which may provide low friction or other beneficial properties, such as impact strength for when the cleaning head impacts the seal. Additionally, the pins may include any other polymer that may resist abrasion as the contact pins may be in direct contact with the seal, although the material may be compatible with the seal material to limit damage to the seal. Each of the pins may also be accessible from below the cleaning head allowing replacement if necessary.
The clearance pin 336 may be positioned within the cleaning head between inlet channels and outlet channels for the cleaning fluid. For example, as illustrated, first fluid channel 326a may extend inward of contact pin 328 and into trench 318 at a first position. Second fluid channel 326b, as well as third fluid channel 326c, may fluidly access a second position, and third position respectively, along the trench radially or laterally offset from the first position in a direction of rotation of the seal. Clearance pin 336 may be positioned between the first fluid channel and the second fluid channel, and may be positioned at least partially within the trench between the first position and the second position.
A cleaning solution may be flowed or pumped into first fluid channel 326a, such as by delivering the cleaning solution through fluid delivery tube 307a to the first delivery port in the cleaning head 310. Second fluid channel 326b, as well as third fluid channel 326c, may be used to retrieve the cleaning solution after it has contacted and interacted with seal 510 about clearance pin 336. The second fluid channel and third fluid channel may be coupled through the fluid removal tubes with a vacuum system, such as an aspirator, which may allow a suction action to be performed to draw the cleaning fluid from the trench 318 and from the cleaning head 310. The seal may be rotated during the flow of cleaning solution to enable the entire seal to be cleaned on one or more surfaces. As mentioned previously, a torque-controlled motor may be coupled with the arm on which the cleaning head is coupled, and may ensure the cleaning head maintains contact with the seal all along the seal as it is rotated.
The systems and components previously described may be used in a number of methods for in situ component cleaning.
In some embodiments, the cleaning solution may be or include an acidic solution. The residues may include metal ions or materials on the surface of the seal, which may be removed by an acid wash. The acidic solution may be selected based on the metal being electroplated, and may include nitric acid, acetic acid, sulphuric acid, or any other organic or inorganic acid as well as acid mixture that may facilitate removal of copper materials, nickel materials, tin-silver solders, or other materials that may be electroplated and may cause residues to form on the seal, including metal-organic materials and complexed metals, such as, for example, silver in a tin silver bath.
As previously explained, the cleaning head may be formed of a hydrophobic material, which may limit or prevent wetting of the cleaning solution onto the cleaning head materials. The delivery of the cleaning solution, removal of the cleaning solution, and rotation of the seal may also be performed in a manner to limit contact of the solution with surfaces of the cleaning head, as well as to limit dripping or leakage of the solution from the cleaning head into contact with any other component of the system head. For example, an acid solution may cause damage to contacts if it is allowed to interact with the contacts, accordingly, by carefully controlling the delivery and removal of the solution, acidic solutions may be used in the present technology, unlike other in situ systems that may be limited to water. Utilizing the present technology, the cleaning solution may be substantially maintained within a volume defined in part by an inner surface of the contact seal, a trench formed within a front portion of the cleaning head, and one or more contact pins at least partially extending through the trench proximate leading and trailing edges of the cleaning head in a direction of rotation of the contact seal across the cleaning head.
In some embodiments a water rinse may be performed with water, such as deionized water, subsequent delivery and removal of the cleaning solution. The water may be delivered in substantially the same fashion as the cleaning solution. In some embodiments the water may be delivered at a greater volumetric flow rate than the cleaning solution. By delivering additional water relative to the removal rate, the water may be flowed further within the volume, such as to interact with contact pin 328, or contact pin 330, which may allow any residual cleaning solution to be effectively flushed from the cleaning head. Additionally, an amount of water may be leaked or ejected from the cleaning head, which may allow a rinse of the underlying contact on the system head. The present technology provides the ability to clean contact seals in situ, which limits down time of electroplating equipment, while also limiting conductive residue formation on exposed tool surfaces, which may affect plating uniformity on a substrate. Accordingly, improved throughput and quality may be afforded by systems and methods according to the present technology.
In the preceding description, for the purposes of explanation, numerous details have been set forth in order to provide an understanding of various embodiments of the present technology. It will be apparent to one skilled in the art, however, that certain embodiments may be practiced without some of these details, or with additional details. For example, other substrates that may benefit from the wetting techniques described may also be used with the present technology.
Having disclosed several embodiments, it will be recognized by those of skill in the art that various modifications, alternative constructions, and equivalents may be used without departing from the spirit of the embodiments. Additionally, a number of well-known processes and elements have not been described in order to avoid unnecessarily obscuring the present technology. Accordingly, the above description should not be taken as limiting the scope of the technology.
Where a range of values is provided, it is understood that each intervening value, to the smallest fraction of the unit of the lower limit, unless the context clearly dictates otherwise, between the upper and lower limits of that range is also specifically disclosed. Any narrower range between any stated values or unstated intervening values in a stated range and any other stated or intervening value in that stated range is encompassed. The upper and lower limits of those smaller ranges may independently be included or excluded in the range, and each range where either, neither, or both limits are included in the smaller ranges is also encompassed within the technology, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included. Where multiple values are provided in a list, any range encompassing or based on any of those values is similarly specifically disclosed.
As used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise. Thus, for example, reference to “a material” includes a plurality of such materials, and reference to “the channel” includes reference to one or more channels and equivalents thereof known to those skilled in the art, and so forth.
Also, the words “comprise(s)”, “comprising”, “contain(s)”, “containing”, “include(s)”, and “including”, when used in this specification and in the following claims, are intended to specify the presence of stated features, integers, components, or operations, but they do not preclude the presence or addition of one or more other features, integers, components, operations, acts, or groups.
This application claims the benefit of U.S. Provisional Application No. 62/625,277, filed Feb. 1, 2018, and which is hereby incorporated by reference in its entirety for all purposes.
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