Patent Grant
8844461
This application is related to U.S. patent application Ser. No. 11/735,984, filed on even date herewith, entitled “Wafer Electroless Plating System and Associated Methods,” and U.S. patent application Ser. No. 11/735,987, filed on even date herewith, entitled “Method and Apparatus for Wafer Electroless Plating,” and U.S. patent application Ser. No. 11/639,752, filed on Dec. 15, 2006, entitled “Controlled Ambient System for Interface Engineering,” and U.S. Pat. No. 7,045,018, entitled “Substrate Brush Scrubbing and Proximity Cleaning-Drying Sequence Using Compatible Chemistries, and Method, Apparatus, and System for Implementing the Same,” and U.S. patent application Ser. No. 11/016,381, filed on Dec. 16, 2004, entitled “System Method and Apparatus for Dry-in, Dry-out Low Defect Laser Dicing Using Proximity Technology,” and U.S. patent application Ser. No. 10/882,716, filed on Jun. 30, 2004, entitled “Proximity Substrate Preparation Sequence, and Method, Apparatus, and System for Implementing the Same,” and U.S. patent application Ser. No. 11/382,906, filed on May 11, 2006, entitled “Plating Solution for Electroless Deposition of Copper,” and U.S. patent application Ser. No. 11/427,266, filed on Jun. 28, 2006, entitled “Plating Solutions for Electroless Deposition of Copper,” and U.S. patent application Ser. No. 11/639,012, filed on Dec. 13, 2006, entitled “Self Assembled Monolayer for Improving Adhesion Between Copper and Tantalum,” and U.S. patent application Ser. No. 11/591,310, filed on Oct. 31, 2006, entitled “Methods of Fabricating a Barrier Layer with Varying Composition for Copper Metallization,” and U.S. patent application Ser. No. 11/552,794, filed on Oct. 25, 2006, entitled “Apparatus and Method for Substrate Electroless Plating,” and U.S. Pat. No. 7,153,400, entitled “Apparatus and Method for Depositing and Planarizing Thin Films of Semiconductor Wafers,” and U.S. patent application Ser. No. 11/539,155, filed on Oct. 5, 2006, entitled “Electroless Plating Method and Apparatus,” and U.S. patent application Ser. No. 11/611,758, filed on Dec. 15, 2006, entitled “Method for Gap Fill in Controlled Ambient System.” The disclosure of each of the above-identified related applications is incorporated herein by reference.
In the fabrication of semiconductor devices such as integrated circuits, memory cells, and the like, a series of manufacturing operations are performed to define features on semiconductor wafers (“wafers”). The wafers include integrated circuit devices in the form of multi-level structures defined on a silicon substrate. At a substrate level, transistor devices with diffusion regions are formed. In subsequent levels, interconnect metallization lines are patterned and electrically connected to the transistor devices to define a desired integrated circuit device. Also, patterned conductive layers are insulated from other conductive layers by dielectric materials.
To build an integrated circuit, transistors are first created on the surface of the wafer. The wiring and insulating structures are then added as multiple thin-film layers through a series of manufacturing process steps. Typically, a first layer of dielectric (insulating) material is deposited on top of the formed transistors. Subsequent layers of metal (e.g., copper, aluminum, etc.) are formed on top of this base layer, etched to create the conductive lines that carry the electricity, and then filled with dielectric material to create the necessary insulators between the lines.
Although copper lines are typically comprised of a PVD seed layer (PVD Cu) followed by an electroplated layer (ECP Cu), electroless chemistries are under consideration for use as a PVD Cu replacement, and even as a ECP Cu replacement. Electroless copper (Cu) and electroless cobalt (Co) are potential techniques for improving interconnect reliability and performance. Electroless Cu can be used to form a thin conformal seed layer on a conformal barrier to optimize a gapfill process and minimize void formation. Further, deposition of a selective Co capping layer on planarized Cu lines can improve adhesion of the dielectric barrier layer to the Cu lines, and suppress void formation and propagation at the Cu-dielectric barrier interface.
During the electroless plating process, electrons are transferred from a reducing agent to the Cu (or Co) ions in the solution resulting in the deposition of reduced Cu (or Co) onto the wafer surface. The formulation of the electroless copper plating solution is optimized to maximize the electron transfer process involving the Cu (or Co) ions in solution. The plating thickness achieved through the electroless plating process is dependent on the residency time of the electroless plating solution on the wafer. Because the electroless plating reactions occur immediately and continuously upon exposure of the wafer to the electroless plating solution, it is desirable to perform the electroless plating process in a controlled manner and under controlled conditions. To this end, a need exists for an improved electroless plating apparatus.
In one embodiment, a fluid handling module for a semiconductor wafer electroless plating chamber is disclosed. The fluid handling module includes a supply line, a mixing manifold, and a chemical fluid handling system. The first supply line is connected to supply an electroless plating solution to a fluid bowl within the chamber. The mixing manifold includes a fluid output connected to the first supply line. The mixing manifold also includes a number of fluid inputs for respectively receiving a number of chemicals. The mixing manifold is defined to mix the number of chemicals to form the electroless plating solution. The chemical fluid handling system is defined to supply the number of chemicals to the number of fluid inputs of the mixing manifold in a controlled manner.
In another embodiment, a fluid handling system for a semiconductor wafer electroless plating process is disclosed. The fluid handling system includes a number of fluid recirculation loops. Each fluid recirculation loop is defined to pre-condition a chemical component of an electroless plating solution. Each fluid recirculation loop is also defined to control a supply of the chemical component to be used to form the electroless plating solution. The fluid handling system also includes a mixing manifold defined to receive the chemical component from each fluid recirculation loop and mix the received chemical components to form the electroless plating solution. The mixing manifold is further defined to supply the electroless plating solution to be disposed over a wafer.
In another embodiment, a method is disclosed for operating a fluid handling system to support a semiconductor wafer electroless plating process. The method includes an operation for recirculating each of a number of chemical components of an electroless plating solution in a separate and pre-conditioned state. The number of chemical components are mixed to form the electroless plating solution. Mixing of the chemical components is performed downstream and separate from the recirculation of the chemical components. The method also includes an operation for flowing the electroless plating solution to a number of dispense locations within an electroless plating chamber. The mixing is performed at a location so as to minimize a flow distance of the electroless plating solution to the number of dispense locations.
Other aspects and advantages of the invention will become more apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the present invention.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without some or all of these specific details. In other instances, well known process operations have not been described in detail in order not to unnecessarily obscure the present invention.
For more information on electroless plating, reference can be made to: (1) U.S. patent application Ser. No. 11/382,906, filed on May 11, 2006, entitled “Plating Solution for Electroless Deposition of Copper,” (2) U.S. patent application Ser. No. 11/427,266, filed on Jun. 28, 2006, entitled “Plating Solutions for Electroless Deposition of Copper,” (3) U.S. patent application Ser. No. 11/639,012, filed on Dec. 13, 2006, entitled “Self Assembled Monolayer for Improving Adhesion Between Copper and Tantalum,” (4) U.S. patent application Ser. No. 11/591,310, filed on Oct. 31, 2006, entitled “Methods of Fabricating a Barrier Layer with Varying Composition for Copper Metallization,” (5) U.S. patent application Ser. No. 11/552,794, filed on Oct. 25, 2006, entitled “Apparatus and Method for Substrate Electroless Plating,” (6) U.S. Pat. No. 7,153,400, entitled “Apparatus and Method for Depositing and Planarizing Thin Films of Semiconductor Wafers,” (7) U.S. patent application Ser. No. 11/539,155, filed on Oct. 5, 2006, entitled “Electroless Plating Method and Apparatus,” and (8) U.S. patent application Ser. No. 11/611,758, filed on Dec. 15, 2006, entitled “Method for Gap Fill in Controlled Ambient System,” each of which is incorporated herein by reference.
The chamber 100 is equipped to receive a wafer in a dry state from an interfacing module, such as the MTM. The chamber 100 is equipped to perform an electroless plating process on the wafer within the chamber 100. The chamber 100 is defined to perform a drying process on the wafer within the chamber 100. The chamber 100 is defined to provide the wafer in a dry state back to the interfacing module. It should be appreciated that the chamber 100 is defined to perform the electroless plating process and the drying process on the wafer within a common internal volume of the chamber 100. Additionally, a fluid handling system (FHS) is provided to support the wafer electroless plating process and the wafer drying process within the common internal volume of the chamber 100.
The chamber 100 includes a first wafer processing zone defined within an upper region of an internal volume of the chamber 100. The first wafer processing zone is equipped to perform the drying process on the wafer when disposed within the first wafer processing zone. The chamber 100 also includes a second wafer processing zone defined within a lower region of the internal volume of the chamber 100. The second wafer processing zone is equipped to perform the electroless plating process on the wafer when disposed within the second wafer processing zone. Additionally, the chamber 100 includes a platen that is vertically movable between the first and second wafer processing zones within the internal volume of the chamber 100. The platen is defined to transport the wafer between the first and second processing zones and support the wafer within the second processing zone during the electroless plating process.
With regard to
The chamber 100 is defined to sit atop a frame assembly 109. It should be understood that other embodiments may utilize a frame assembly that is different from the exemplary frame assembly 109 depicted in
Following the electroless plating process within the lower region of the chamber, the wafer 207 is lifted via the platen 209 and platen lift assembly 115 back to the position where it can be engaged by the drive roller assembly 303 and the stabilizer assembly 305. Once securely engaged by the drive roller assembly 303 and the stabilizer assembly 305, the platen 209 is lowered to a position within the lower region of the chamber 100. The wafer 207, having been subjected to the electroless plating process, is then dried by way of an upper proximity (“prox” hereafter) head 203 and a lower prox head 205. The upper prox head 203 is defined to dry an upper surface of the wafer 207. The lower prox head is defined to dry a lower surface of the wafer 207.
By way of the prox head drive mechanism 113, the upper and lower prox heads 203/205 are defined to move in a linear manner across the wafer 207 when the wafer 207 is engaged by the drive roller assembly 303 and the stabilizer assembly 305. In one embodiment, the upper and lower prox heads 203/205 are defined to move to a center of the wafer 207 as the wafer 207 is rotated by the drive roller assembly 303. In this manner, the wafer 207 upper and lower surfaces can be completely exposed to the upper and lower prox heads 203/205, respectively. The chamber 100 further includes a prox head docking station 201 for receiving each of the upper and lower prox heads 203/205 when retracted to their home position. The prox head docking station 201 also provides for a smooth transition of the meniscus associated with each of the upper and lower prox heads 203/205 as the meniscus transitions onto the wafer 207. The prox head docking station 201 is positioned within the chamber so as to ensure that when the upper and lower prox heads 203/205 are retracted to their respective home positions, the upper and lower prox heads 203/205 do not interfere with the drive roller assembly 303, the stabilizer assembly 305, or the platen 209 when raised to receive the wafer 207.
As shown in
The inner liner 301 provides a chemical boundary and acts as a separator to keep chemicals within the chamber from reaching the outer structural walls 103. The inner liner 301 is formed of an inert material that is chemically compatible with the various chemicals that may be present within the chamber 100. In one embodiment, the inner liner 301 is formed of an inert plastic material. It should be understood, however, that essentially any other chemically inert material that can be appropriately shaped can be used to form the inner liner 301. It should also be understood that the inner liner 301 is not required to provide a vacuum boundary. As previously mentioned, the outer structural walls 103 are defined to provide the vacuum boundary. Additionally, in one embodiment, the inner liner 301 can be removed from the chamber 100 to facilitate cleaning or to simply be replaced with a new inner liner 301.
The chamber 100 is defined to be ambient controlled to facilitate the wafer electroless plating process and protect the wafer surface from undesirable reactions, e.g., oxidation. To this end, the chamber 100 is equipped with an internal pressure control system and an internal oxygen content control system. In one embodiment, the chamber 100 is capable of being pumped down to a pressure of less than 100 mTorr. In one embodiment, it is anticipated that the chamber 100 will be operated at approximately 700 Torr.
It should be appreciated that the oxygen concentration within the chamber 100 internal volume is an important process parameter. More specifically, a low oxygen concentration is required in the wafer processing environment to ensure that undesirable oxidation reactions are avoided at the wafer surface. It is anticipated that the oxygen concentration within the chamber 100 internal volume will be maintained at a level less than 2 ppm (parts per million) when the wafer is present within the chamber 100. The oxygen concentration within the chamber 100 is reduced by evacuating the chamber, by way of a vacuum source plumbed to the internal volume of the chamber 100, and refilling the chamber 100 internal volume with high purity nitrogen. Therefore, the oxygen concentration within the chamber 100 internal volume is reduced from atmospheric levels, i.e., about 20% oxygen, by pumping the chamber 100 internal volume down to a low pressure and refilling the chamber 100 internal volume with ultra pure nitrogen which has a negligible oxygen content. In one embodiment, pumping the chamber 100 internal volume down to 1 Torr and refilling it to atmospheric pressure with ultra pure nitrogen three times should bring the oxygen concentration within the chamber 100 internal volume down to about 3 ppm.
The electroless plating process is a temperature sensitive process. Therefore, it is desirable to minimize the influence of the chamber 100 internal volume ambient conditions on the temperature of the electroless plating solution when present on the wafer surface. To this end, the chamber 100 is defined such that gases can be introduced into the chamber 100 internal volume through air gaps present between the outer structural walls 103 and the inner liner 301, so as to avoid flowing of gases directly over the wafer. It should be appreciated that a flow of gas directly over the wafer when electroless plating solution is present on the wafer surface could cause an evaporative cooling effect that would reduce the temperature of the electroless plating solution present on the wafer, and correspondingly modify the electroless plating reaction rate. In addition to the capability of indirectly introducing gas into the chamber 100 internal volume, the chamber 100 is also equipped to allow a vapor pressure within the chamber 100 internal volume to be raised to a saturated state when the electroless plating solution is applied over the wafer surface. With the chamber 100 internal volume in a saturated state relative to the electroless plating solution, the above-mentioned evaporative cooling effect would be minimized.
With reference back to
Also with reference back to
With reference back to
In various embodiments, the platen 209 can be defined to accommodate a 200 mm wafer or a 300 mm wafer. Additionally, it should be appreciated that the platen 209 and chamber 100 can be defined to accommodate essentially any size wafer. For a given wafer size, a diameter of the platen 209 upper surface, i.e., clamping surface, is defined to be slightly less than a diameter of the wafer. This platen-to-wafer sizing arrangement enables the edge of the wafer to extend slightly beyond the upper peripheral edge of the platen 209, thus enabling engagement between the wafer edge and each of the stabilizer roller 605 and drive rollers 701 when the wafer is sitting upon the platen 209.
As previously mentioned, the electroless plating process is a temperature sensitive process. The platen 209 is defined to be heated so that the temperature of the wafer 207 can be controlled. In one embodiment, the platen 209 is capable of maintaining a temperature up to 100° C. Also, the platen 209 is capable of maintaining a temperature as low as 0° C. It is anticipated that a normal platen 209 operating temperature will be about 60° C. In the embodiment where the platen 209 is sized to accommodate a 300 mm wafer, the platen 209 is defined with two interior resistive heating coils so as to form an inner heating zone and an outer heating zone, respectively. Each heating zone includes its own control thermocouple. In one embodiment, the inner heating zone utilizes a 700 Watt (W) resistive heating coil, and the outer zone utilizes a 2000 W resistive heating coil. In the embodiment where the platen 209 is sized to accommodate a 200 mm wafer, the platen 209 includes a single heating zone defined by a 1250 W interior heating coil and corresponding control thermocouple.
The fluid bowl 211 is defined to receive the platen 209 when the platen 209 is fully lowered within the chamber 100. The fluid holding capability of the fluid bowl 211 is completed when the platen 209 is lowered to engage a fluid bowl seal 909 defined about an inner periphery of the fluid bowl 211. In one embodiment, the fluid bowl seal 909 is an energized seal which forms a liquid tight seal between the platen 290 and fluid bowl 211, when the platen 209 is lowered to fully contact the fluid bowl seal 909. It should be appreciated that when the platen 209 is lowered to engage the fluid bowl seal 909, a gap exists between the platen 209 and the fluid bowl 211. Thus, engagement of the platen 209 with the fluid bowl seal 909 allows an electroless plating solution to be injected into the bowl so as to fill the gap that exists between the platen 209 and the fluid bowl 211 above the fluid bowl seal 909, and well-up over the periphery of the wafer 207 that is clamped on the upper surface of the platen 209.
In one embodiment, the fluid bowl 211 includes eight fluid dispense nozzles for dispensing of the electroless plating solution within the fluid bowl 211. The fluid dispense nozzles are distributed in a uniformly spaced manner around the fluid bowl 211. Each of the fluid dispense nozzles is fed by a tube from a distribution manifold such that a fluid dispense rate from each fluid dispense nozzle is substantially the same. Also, the fluid dispense nozzles are disposed such that fluid emanating from each of the fluid dispense nozzles enters the fluid bowl 211 at a location below the upper surface of the platen 209, i.e., below the wafer 207 that is clamped on the upper surface of the platen 209. Additionally, when the platen 209 and wafer 207 are not present in the fluid bowl 211, the fluid bowl 211 can be cleaned by injecting a cleaning solution into the fluid bowl 211 through the fluid dispense nozzles. The fluid bowl 211 can be cleaned at a user defined frequency. For example, the fluid bowl can be cleaned as frequently as after processing of every wafer, or as infrequently as once every 100 wafers.
The chamber 100 also includes a rinse bar 901, which includes a number of rinse nozzles 903 and a number of blowdown nozzles 905. The rinse nozzles 903 are directed to spray rinse fluid on the top surface of the wafer 207 when the platen 209 is moved to place the wafer 207 in rinse position. At the rinse position, a space will exist between the platen 209 and the fluid bowl seal 909 to enable flow of rinse fluid into the fluid bowl 211 from which it can be drained. In one embodiment, two rinse nozzles 903 are provided for rinsing a 300 mm wafer, and one rinse nozzle 903 is provided for rinsing a 200 mm wafer. The blowdown nozzles 905 are defined to direct an inert gas, such as nitrogen, toward the top surface of the wafer to assist in removing fluid from the top surface of the wafer during the rinsing process. It should be appreciated that because the electroless plating reactions continuously occur when the electroless plating solution is in contact with the wafer surface, it is necessary to promptly and uniformly remove the electroless plating solution from the wafer upon completion of the electroless plating period. To this end, the rinse nozzles 903 and blowdown nozzles 905 enable prompt and uniform removal of the electroless plating solution from the wafer 207.
It should be appreciated that the wafer handoff position is also the wafer drying position within the chamber 100. The wafer handoff and drying processes occur within an upper region 1007 of the chamber 100. The fluid bowl 211 resides in a lower region 1009 of the chamber 100, directly below the wafer-handoff position. This configuration enables the platen 209 to be raised and lowered to enable movement of the wafer 207 from the wafer-handoff position to the wafer processing position in the lower region 1009. During the wafer handoff process, the platen 209 is in a fully lowered position to avoid interference of the platen 209 with the robotic wafer handling device.
Following receipt of the wafer 207 within the chamber 100, the wafer 207 is moved to the lower region 1009 of the chamber 100 for processing. By way of the platen lift assembly 115 and shaft 801, the platen 209 is used to transport the wafer 207 from the upper region 1007 of the chamber 100 to the lower region 1009 of the chamber 207.
The platen 209 is heated to a user specified temperature, and the wafer 207 is held on the platen 209 for a user specified duration to allow the wafer 207 to heat up. The platen 209 with wafer thereon is then lowered to a hovering position just above a position at which the platen 209 would engage the fluid bowl seal 909, i.e., just above the sealing position.
When the platen 209 with the wafer 207 thereon is in the hovering position, the electroless plating process can commence. Prior to the electroless plating process, the FHS is operated to recirculate the electroless plating chemicals in a pre-mixed state. While the platen 209 is maintained in the hovering position, a flow of the electroless plating solution 1003 into the fluid bowl 211 by way of fluid dispense nozzles 1001 is initiated. The flow of electroless plating solution 1003 when the platen 209 is in the hovering position is referred to as a stabilizing flow. During the stabilizing flow, the electroless plating solution 1003 flows from the fluid dispense nozzles down between the platen 209 and fluid bowl seal 909 into the fluid bowl 211 drain basin. The fluid dispense nozzles 1001 are disposed in a substantially uniformly spaced manner about a periphery of the fluid bowl 211 so as to be positioned uniformly about a periphery of the underside of the platen 209 when the platen 209 is lowered to engage the fluid bowl seal 909. Also, each of the fluid dispense nozzles 1001 is positioned so that electroless plating solution 1003 dispensed therefrom is dispensed at a location below the wafer 207 held atop the platen 209.
The stabilizing flow allows the flow of electroless plating solution 1003 to each of the fluid dispense nozzles 1001 to stabilize prior to lowering of the platen 209 to engage the fluid bowl seal 909. The stabilizing flow continues until either a user specified amount of time has elapsed or until a user specified volume of electroless plating solution 1003 has been dispensed from the fluid dispense nozzles 1001. In one embodiment, the stabilizing flow continues for a period of time extending from about 0.1 second to about 2 seconds. Also, in one embodiment, the stabilizing flow continues until a volume of electroless plating solution 1003 extending from about 25 mL to about 500 mL has been dispensed from the fluid dispense nozzles 1001.
At the conclusion of the stabilizing flow, the platen 209 is lowered to engage the fluid bowl seal 909.
In one embodiment, after the fluid bowl seal 909 has been engaged by the platen 209, an additional volume of electroless plating solution 1003 extending from about 200 mL to about 1000 mL is dispensed from the fluid dispense nozzles 1001. Dispensing of the additional electroless plating solution 1003 may take from about 1 second to about 10 seconds. Following the dispensing of the additional electroless plating solution 1003 so as to cover the entire wafer 207 surface with electroless plating solution 1003, a user defined period of time is allowed to elapse during which electroless plating reactions occur on the wafer surface.
Immediately following the user defined time period for electroless plating reaction, the wafer 207 is subjected to a rinsing process.
Following the wafer rinsing process, the wafer 207 is moved to the wafer drying position, which is the same as the wafer handoff position. With reference back to
Wafer rotation during the drying process is initiated at an initial rotation speed and adjusted as the prox heads 203/205 are scanned across the wafer. In one embodiment, during the drying process, the wafer will be rotated a rate extending from about 0.25 revolution per minute (rpm) to about 10 rpm. The wafer rotation speed will vary as a function of the prox head 203/205 radial position over the wafer. Also, a scanning speed of the upper and lower prox heads 203/205 is initiated at an initial scan speed and adjusted as the prox heads 203/205 are scanned across the wafer. In one embodiment, the prox heads 203/205 are scanned across the wafer at a rate extending from about 1 mm/sec to about 75 mm/sec. At the conclusion of the drying process, the upper and lower prox heads 203/205 are moved to the prox head docking station 201, the IPA flow to the prox heads 203/205 is stopped, the nitrogen flow to the prox heads 203/205 is stopped, and the vacuum supply to the prox heads 203/205 is stopped.
During the drying process, the upper and lower prox heads 203/205 are positioned in close proximity to a top surface 207A and a bottom surface 207B of the wafer 207, respectively. Once in this position, the prox heads 203/205 may utilize the IPA and DIW source inlets and a vacuum source outlet(s) to generate wafer processing meniscuses 1011A/1011B in contact with the wafer 207 which are capable of applying and removing fluids from the top and bottom surfaces of the wafer 207. The wafer processing meniscuses 1011A/1011B may be generated in accordance with the descriptions provided with regard to
The portion of the DIW that is in the region between the prox heads 203/205 and the wafer 207 is the dynamic liquid meniscus 1011A/1011B. It should be appreciated that as used herein, the term “output” can refer to the removal of fluid from a region between the wafer 207 and a particular prox head 203/205, and the term “input” can be the introduction of fluid to the region between the wafer 207 and the particular prox head 203/205.
It should be appreciated that any suitable combination of source inlets and source outlets may be utilized as long as at least one combination exists where at least one of the source inlet 1107 is adjacent to at least one of the source outlet 1109 which is in turn adjacent to at least one of the source inlet 1111. The IPA may be in any suitable form such as, for example, IPA vapor where IPA in vapor form is inputted through use of a nitrogen carrier gas. Moreover, although DIW is utilized herein, any other suitable fluid may be utilized that may enable or enhance the substrate processing such as, for example, water purified in other ways, cleaning fluids, and other processing fluids and chemistries. In one embodiment, an IPA inflow 1105 is provided through the source inlet 1107, a vacuum 1113 is applied through the source outlet 1109, and DIW inflow 1115 is provided through the source inlet 1111. If a fluid film resides on the wafer 207, a first fluid pressure may be applied to the substrate surface by the IPA inflow 1105, a second fluid pressure may be applied to the substrate surface by the DIW inflow 1115, and a third fluid pressure may be applied by the vacuum 1113 to remove the DIW, IPA, and the fluid film on the substrate surface.
It should be appreciated that by controlling the fluid flow amount onto the wafer surface 207A and by controlling the vacuum applied, the meniscus 1011A may be managed and controlled in any suitable manner. For example, in one embodiment, by increasing the DIW flow 1115 and/or decreasing the vacuum 1113, the outflow through the source outlet 1109 may be nearly all DIW and the fluids being removed from the wafer surface 207A. In another embodiment, by decreasing the DIW flow 1115 and/or increasing the vacuum 1113, the outflow through the source outlet 1109 may be substantially a combination of DIW and IPA as well as fluids being removed from the wafer surface 207A. Following the wafer drying process, the wafer 207 can be returned to the external module, e.g., MTM.
By removing all or most of the oxygen from the MTM 1203 and replacing it with an inert gas, the MTM 1203 will provide a transition environment which does not expose a just-processed wafer before or after an electroless plating process is performed thereon in the chamber 100. In specific embodiments, the other processing modules 1207B-1207D may be electroplating modules, electroless plating modules, dry-in/dry-out wet process modules, or other types of modules that will enable the application, formation, removal, or deposition of a layer on top of a wafer surface or feature, or other types of wafer processing.
In one embodiment, monitoring and control of the chamber 100 and interfacing equipment, e.g., FHS, is provided through a graphical user interface (GUI) operating on a computer system that is remotely located with respect to the processing environment. Various sensors within the chamber 100 and interfacing equipment are connected to provide a read out in the GUI. Each electronically actuated control within the chamber 100 and interfacing equipment can be actuated through the GUI. The GUI is also defined to display warnings and alarms based on various sensor readings within the chamber 100 and interfacing equipment. The GUI is further defined to indicate a process state and system conditions.
The chamber 100 of the present invention incorporates a number of advantageous features. For example, the implementation of upper and lower prox heads 203/205 within the chamber 100 provides the chamber 100 with a dry-in/dry-out wafer electroless plating process capability. The dry-in/dry-out capability enables the chamber 100 to interface with the MTM, enables tighter control of chemical reactions on the wafer surface, and prevents the carrying of chemicals outside of the chamber 100.
The double walled configuration of the chamber 100 also provides advantages. For example, the outer structural wall provides for strength and interface precision, while the inner liner provides a chemical boundary to keep chemicals from reaching the outer structural wall. Because the outer structure wall is responsible for providing the vacuum boundary, the inner liner does not have to be capable of providing a vacuum boundary, thus enabling the inner wall to be fabricated from inert materials such as plastic. Additionally, the inner wall is removable to facilitate chamber 100 cleaning or re-equipping. Also, the strength of the outer wall enables a decrease in time required to achieve an inert ambient condition within the chamber 100.
The chamber 100 provides for control of ambient conditions within the chamber 100. Use of an inert ambient condition during drying enables creation of a surface tension gradient (STG) which in turn enables the prox head processes. For example, a carbon dioxide ambient condition can be established within the chamber 100 to assist with creation of STG during the prox head drying process. The integration of STG drying, i.e., prox head drying, within a wet process chamber, i.e., within an electroless plating chamber, enables a multi-stage process capability. For example, the multi-stage process may include a pre-clean operation by way of the prox heads in the upper region of the chamber, an electroless plating process in the lower region of the chamber, and post-clean and drying operations by way of the prox heads in the upper region of the chamber.
Furthermore, the chamber 100 is configured to minimize an amount of required electroless plating solution, thereby enabling use of single-shot chemistry, i.e., single use and discard chemistry. Also, a point of use mixing approach is implemented to control electrolyte activation before deposition on wafer. This is accomplished by use of the mixing manifold which incorporates an injector tube, where the activating chemistry is injected into a flow stream of chemicals surrounding the injector tube, as close as possible to the fluid bowl dispense locations. This increases reactant stability, and reduces defects. Additionally, the quenching rinse capability of the chamber 100 provides for greater control over electroless plating reaction time on the wafer. The chamber 100 is further configured to be easily cleaned by introducing a “backflush” chemistry into the limited volume of the fluid bowl. The “backflush” chemistry is formulated to remove metal contaminants that may be introduced by the electroless plating solution. In other embodiments, the chamber 100 can be further configured to incorporate various types of in-situ metrology. Also, in some embodiments, the chamber 100 can include radiant or absorptive heating sources to initiate electroless plating reactions on the wafer.
Operations of the chamber 100 are supported by a fluid handling system (FHS). In one embodiment, the FHS is defined as a separate module from the chamber 100 and is connected in fluid communication with various components within the chamber 100. The FHS is defined to service the electroless plating process, i.e., the fluid bowl dispense nozzles, rinse nozzles, and blowdown nozzles. The FHS is also defined to service the upper and lower prox heads 203/205. A mixing manifold is disposed between the FHS and the supply line that services each of the fluid dispense nozzles within the fluid bowl 211. Thus, the electroless plating solution that flows to each of the fluid dispense nozzles within the fluid bowl 211 is pre-mixed prior to reaching the fluid bowl 211.
Fluid supply lines are disposed to fluidly connect the mixing manifold to the various fluid dispense nozzles within the fluid bowl 211, such that the electroless plating solution will flow into the fluid bowl 211 from each fluid dispense nozzle in a substantially uniform manner, e.g., at a substantially uniform flow rate. The FHS is defined to enable a nitrogen purge of the fluid supply lines disposed between the mixing manifold and the fluid dispense nozzles within the fluid bowl 211, so as to enable clearing of the fluid supply lines of electroless plating solution. The FHS is also defined to support the wafer rinsing process by providing rinsing fluid to each of the rinse nozzles 903 and by providing inert gas to each of the blowdown nozzles 905. The FHS is defined to enable manual setting of a pressure regulator to control the liquid pressure emanating from the rinse nozzles 903.
In one embodiment, the FHS includes three primary modules: 1) a chemical FHS 1401, 2) a chemical supply FHS 1403, and 3) a rinse FHS 1405.
In one embodiment, the chemical FHS 1401 is defined to include four fluid recirculation loops 1407 for pre-conditioning a fluid prior to supplying the fluid to the chamber 100, and for controlling the supply of the fluid to the chamber 100. In one embodiment, three of the recirculation loops 1407 are utilized to pre-condition and control the supply of processing chemicals to the chamber 100, and the fourth recirculation loop 1407 is utilized to pre-condition and control supply of deionized water (DIW) to the chamber 100. It should be appreciated that in other embodiments, the chemical FHS 1401 can include a different number, i.e., fewer than four or more than four, of fluid recirculation loops 1407, and the various recirculation loops 1407 can be utilized to supply different types of fluids to the chamber 100.
In one embodiment, the heater 1415 is a resistive heater defined to heat the fluid as it is circulated through the recirculation loop 1407. The degasser 1413 is used to remove gas from the fluid as it is circulated through the recirculation loop 1407. The degasser 1413 has vacuum on one side of a gas permeable membrane over which the fluid is circulated. Thus, gases dissolved in the fluid pass through the membrane out of the fluid.
A multiposition valve 1425 is provided to control whether the fluid is recirculated through the recirculation loop 1407 or directed to the mixing manifold for ultimate provision to the fluid bowl 211. In one embodiment, a manual needle valve 1423 is provided to enable matching of the pressure drop from the multiposition valve 1425 to the surge tank 1409 with the pressure drop from the multiposition valve 1425 to the fluid bowl 211. This pressure drop matching prevents a significant spike in flowrate when the multiposition valve 1425 is activated to direct the fluid to the fluid bowl 211.
The recirculation loop 1407 can be operated in three modes: 1) startup mode, 2) fluid heating mode, and 3) pre-dispense/dispense mode. In startup mode, it is assumed that the surge tank 1409 starts completely empty. The goal of the startup mode is to prime the pump 1411 and fill the recirculation loop 1407. Before the pump 1411 is started, the surge tank 1409 should be filled to a level that will prevent gas from being pulled into the fluid stream. To fill the surge tank 1409, a valve 1427 is activated to allow chemical from the chemical supply FHS 1403 to enter the surge tank 1409. The pump 1411 is then started at a slow speed. The pump 1411 speed is gradually increased as additional chemical is supplied to the tank through the valve 1427.
When fluid is added to the recirculation loop 1407, either as a result of system startup or because fluid was added during normal operation, the fluid should be heated by the heater 1415 during the fluid heating mode. In normal operation, it is expected that about 200 mL will be added to the recirculation loop 1407 during a refill cycle. It is expected that up to 3 L can be added during startup. In one embodiment, an optimum flowrate for heating the fluid is about 2 L/min. The flowrate of fluid through the recirculation loop 1407 can be controlled to the optimum flowrate during the heating mode. It is expected to take about 150 seconds to bring about 200 mL of fluid from room temperature up to about 60° C.
Prior to dispensing the fluid to the fluid bowl 211 in the pre-dispense/dispense mode, the flowrate of fluid through the recirculation loop 1407 should be set to the flow rate expected during dispensing of the fluid to the fluid bowl 211. In one embodiment, the flow rates used for dispensing fluid to the fluid bowl 211 can vary from about 0.25 L/min to about 2.4 L/min. This correlates to about 21.6 mL to about 200 mL of fluid being dispensed to the fluid bowl 211 during a 5 second dispense period. It should take about 20 seconds for the flowrate in the loop to stabilize when being adjusted in this range. Dispensing of fluid from the recirculation loop 1407 to the fluid bowl 211, by way of the mixing manifold, is achieved by activating the multiposition valve 1425 to direct fluid to the fluid bowl 211 for an appropriate dispense period. The multiposition valve 1425 of each recirculation loop 1407 should be actuated at substantially the same time to ensure that the appropriate mixture of chemicals is provided to the fluid bowl 211. As previously discussed with regard to
The chemical FHS also includes a syringe pump 1457 for injecting a fourth chemical into the fluid supply just before the fluid bowl 211. In one embodiment, the syringe pump 1457 is filled prior to initiating the fluid dispense mode of operation. The syringe pump 1457 includes a rotary valve that allows different ports to be opened to the syringe. In one embodiment, the syringe pump 1457 is a positive displacement pump and has a 50 mL maximum charge. The syringe pump 1457 is filled by setting the rotary valve so the syringe is opened to a desired chemical supply. The syringe pump 1457 is dispensed by setting the rotary valve so the syringe pump 1457 is opened to the fluid stream as it flows to the fluid bowl 211. In one embodiment, the dispense rate from the syringe pump 1457 can vary from about 10 mL/min to about 1000 mL/min. It should be appreciated that the syringe pump 1457 discussed above is but one embodiment of a number of possible embodiments. Additionally, it should be understood that the dispense of chemicals 1-3, DIW, and chemical 4 are coordinated to prevent imprecise chemical mixtures from reaching the fluid bowl 211 and wafer 207.
With further regard to
The chemical supply FHS 1403 is defined to supply the various chemicals to the chemical FHS 1401 from respective chemical supply tanks. In one embodiment, the various chemicals are pressurized for delivery to the chemical FHS 1401. The pressures in the various chemical supply tanks are controlled by pressure regulators. Also, each chemical supply tank has a fluid level sensor. Each fluid level sensor can be monitored to verify that sufficient chemical is present in the chemical supply tank to proceed with the process to be performed within the chamber 100. The chemical supply FHS 1403 includes the ability to deliver a fifth chemical to the fluid bowl. In one embodiment, the fifth chemical is defined as a cleaning chemistry for cleaning the fluid bowl 211. The cleaning chemistry is used to prevent or remove plating deposits in the electroless plating solution delivery lines and fluid bowl 211. The cleaning chemistry may or may not be pressurized. In one embodiment, the cleaning chemistry is delivered by a syringe pump present in the chemical supply FHS 1403.
The rinse FHS 1405 includes a portion for IPA generation and delivery and a portion for rinsing fluid delivery and extraction from the chamber 100. An IPA system is housed in a separate stainless steel enclosure of the rinse FHS 1405 to keep the flammable IPA from heaters and other chemicals within the overall FHS system. The rinse FHS 1405 enclosure also includes ports for facilities entry and waste exit. In one embodiment, facilities enter and waste exits the bottom of the rinse FHS 1405 enclosure. Also, in one embodiment, an upper portion of the rinse FHS 1405 enclosure includes vacuum tanks, evacuation pumps, and flow controllers associated with the upper and lower prox heads 203/205.
The IPA system supports generation of IPA vapor and supply of IPA vapor to the upper and lower prox heads 203/205. A nitrogen/IPA supply line is connected to supply IPA vapor to each of the upper and lower prox heads 203/205. In one embodiment, independent control of the IPA vapor flow and nitrogen flow is provided for each of the upper and lower prox heads 203/205. In one embodiment, two on-board tanks contain IPA, wherein each tank is defined to have a capacity of 2 L with 1 L of usable volume. These two tanks are used in an alternate manner to supply IPA to a vaporizer system. As one tank supplies IPA, the other tank can be replenished. Sensors are utilized to monitor fluid levels within each tank. Also, each tank is equipped with an overpressure relief valve, which will vent into an exhaust.
In one embodiment, a single vaporizer system services both the upper and lower prox heads 203/205. Liquid IPA is dispensed from one of the tanks through a liquid mass flow controller at a mass flowrate up to 30 g/min. A nitrogen carrier gas is dispensed through a mass flow controller at a flowrate up to 30 SLPM (standard liters per minute), and is combined with the IPA and then injected into the vaporizer system. Hot IPA vapor leaving the vaporizer system is mixed with a post vaporizer nitrogen dilutor to dilute the concentration of IPA within the hot vapor. The amount of post vaporizer nitrogen is controlled by a mass flow controller at a flowrate up to 200 SLPM. The IPA vapor is then delivered to the upper and lower prox heads 203/205.
As previously mentioned, the amount of IPA vapor flow to each prox head 203/205 can be controlled independently. In one embodiment, a rotometer is used to control the flow of IPA to each prox head 203/205. The rotometer allows the user to adjust the ratio of flow going to the upper and lower prox heads 203/205. In one embodiment, the various nitrogen flow rates are monitored via the mass flow controllers and are reported to an operator. A warning or alarm can be triggered by the nitrogen flow rate being too low or too high relative to a user defined trigger point.
The fluid delivery and extraction features of the rinse FHS 1405 support getting liquid to and from the prox heads 203/205. Fluid deliver to the prox heads 203/205 includes supplying a flow of DIW to the upper and lower prox heads 203/205. In one embodiment, separate flow controllers are used to control delivery of DIW to inner and outer portions, respectively, of a meniscus formed by the upper prox head 203. In one embodiment, each of these flow controllers is operated to control DIW flow within a range extending from about 200 mL/min to about 1250 mL/min. The DIW flow rate is settable both manually and by recipe. Also, valves are provided to activate DIW flow to each portion of the meniscus for the upper prox head 203. In one embodiment, DIW flow is provided to a single zone in the meniscus formed by the lower prox head 205. In one embodiment, a flow controller is used to control flow of DIW to the lower prox head 205 within a range extending from about 200 mL/min to about 1250 mL/min.
The rinse FHS 1405 provides for removal of fluid from the upper and lower prox heads 203/205 through a set of vacuum tanks and vacuum generators. In one embodiment, the rinse FHS 1405 includes a total of four vacuum generators and respective vacuum tanks. More specifically, a vacuum tank/generator combination is provided for each of the upper prox head 203 outer zone, the upper prox head 203 inner zone, the lower prox head 205, and the drive rollers 701 and stabilizer roller 605. Valves are used to control the vacuum supply to the upper prox head 203, lower prox head 205, and rollers 701/605, respectively. These valves are operated to generate and control the vacuum in the vacuum tanks. Valves are also used to activate the vacuum at each of the upper prox head 203, lower prox head 205, and rollers 701/605. Also, sensors are provided to monitor the fluid level within each vacuum tank.
Drain pumps are also provided to pump out the vacuum tanks. In one embodiment, the drain pumps are pneumatically actuated diaphragm pumps. Each tank has a drain valve to enable independent control of the pumping of the tank by its drain pump. Additionally, sensors are provided to monitor the pressure within each vacuum tank. In one embodiment, each vacuum tank is operated at a pressure within a range extending from about 70 mmHg to about 170 mmHg. A pressure alarm can also be provided to notify if the pressure within the vacuum tank is out of operating range.
The chamber 100 includes a number of fluid drain locations. In one embodiment, three separate fluid drain locations are provided within the chamber 100: 1) a primary drain from the fluid bowl 211, 2) a chamber floor drain, and 3) a platen vacuum tank drain. Each of these drains is connected to a common facility drain provided within the rinse FHS 1405. The fluid bowl 211 drain is plumbed from the fluid bowl 211 to a chamber drain tank. A valve is provided to control the draining of fluid from the fluid bowl 211 to the chamber drain tank. In one embodiment, this valve is configured to open when fluid is present within the drain line that connects the fluid bowl 211 to the chamber drain tank.
A chamber floor drain is also connected to the chamber drain tank. In the event of a liquid spill within the chamber 100, liquid will drain from the port in the chamber floor to the chamber drain tank. A valve is provided to control the draining of fluid from the chamber floor to the chamber drain tank. In one embodiment, the valve is configured to open when fluid is present within the drain line that connects the chamber floor to the chamber drain tank. The platen vacuum tank has its own drain tank. The platen drain tank also serves as a vacuum tank. A vacuum generator is connected to the platen drain tank and is the source of the backside wafer vacuum. Valves are provided to control the vacuum present at the backside of the wafer. Also, sensors are also provided to monitor the pressure present at the backside of the wafer. The platen drain tank and chamber drain tank share a common drain pump. However, each of the platen drain tank and chamber drain tank has its own isolation valve between the tank and the pump to enable emptying of each tank independently.
While this invention has been described in terms of several embodiments, it will be appreciated that those skilled in the art upon reading the preceding specifications and studying the drawings will realize various alterations, additions, permutations and equivalents thereof. Therefore, it is intended that the present invention includes all such alterations, additions, permutations, and equivalents as fall within the true spirit and scope of the invention.
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