Systems and methods for chemically and thermally wetting substrates prior to metal plating.

Abstract

A wetting tool provides improved wettability and the ability to remove debris from features defined by a patterned resist layer on a substrate. The substrate wetting tool relies on a wetting solution with a pH of 2.0 or lower and / or a temperature range of 20 to 50°C. At a pH of 2.0 or lower, the resist material used to form the feature undergoes a chemical reaction, making it more hydrophilic. Therefore, the wetting solution is attracted to the feature, advantageously reducing the chance of bubble formation and removing debris. At elevated temperatures, the heated wetting solution improves particle stratification and facilitates the dissolution of debris and oxides from the substrate surface.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Application No. 16 / 048,776, filed July 30, 2018, which is incorporated herein by reference for all purposes. Background Technology

[0003] Electroplating is a process that involves depositing a thin layer on a workpiece under an applied electric field.

[0004] In the semiconductor industry, electroplating is commonly used. For example, electroplating is often used to form interconnects between transistors and vias between different layers on a semiconductor wafer.

[0005] Various features on electroplated semiconductor wafers are typically defined by patterned resist layers. For example, a thick resist layer is first formed over a copper seed layer. The resist layer is then patterned to form features that expose the underlying region of the copper seed layer to be plated. The wafer substrate then undergoes an electroplating process to form a metal layer on the exposed portion of the seed layer.

[0006] Electroplating small features on semiconductor substrates can be problematic for several reasons. Typically, bubbles and / or debris can trap within the small features defined by patterned resist, interfering with or hindering the electroplating process. The resulting plated metal layer may be of poor quality, insufficient thickness, uneven, or in severe cases, may not form at all.

[0007] Tools with wetting chambers are commonly used in the semiconductor industry. Using such tools, a wafer substrate is "wetted" within the chamber with a rinsing solution, such as deionized (DI) water or other chemical solutions, typically with a pH level above 2. Wetting the wafer substrate prevents air bubbles and attempts to remove debris from these features before plating.

[0008] During the wetting process, the wafer substrate is placed in a chamber, and a wetting solution is introduced into the chamber via a spray nozzle as the wafer spins. After a predetermined time period, and after one or more spin / wetting cycles, the fluid is drained from the chamber. The wafer substrate is then transported from the chamber to the plating chamber for electroplating.

[0009] Existing wetting tools have several drawbacks. The resists typically used to define the characteristics are usually hydrophobic. As a result, wetting solutions with a pH above 2.0 are often rejected in locations where wetting solutions are needed to remove cavitation and / or debris. Furthermore, the wetting solutions introduced into the wetting chamber are typically at ambient or room temperature, at which temperatures their ability to clean and remove debris is impaired.

[0010] Therefore, there is a need for improved systems and methods for chemical and thermal wetting of semiconductor substrates. Summary of the Invention

[0011] A wetting tool is disclosed that provides improved wetting and the ability to remove debris from features defined by a patterned resist layer on a substrate.

[0012] The substrate wetting tool comprises: a chamber; a substrate base for supporting the substrate within the chamber; and a wetting solution dispensing system for introducing a wetting solution into the chamber. The wetting solution has a pH of 2.0 or less and / or a temperature ranging from 20 to 50°C. At a pH of 2.0 or less, the resist material used to form the feature undergoes a chemical reaction, making it more hydrophilic. As a result, the wetting solution is attracted into the feature, advantageously reducing the chance of bubble formation and aiding in the removal of debris. Additionally, at elevated temperatures, the wetting solution alters surface kinetics, resulting in improved particle stratification from the substrate. The high temperature of the wetting solution can also help dissolve any debris or oxides from the substrate surface. Consequently, the ability of the wetting solution to clean debris within the feature is further enhanced.

[0013] In various implementations, the low pH level and / or heated wetting solution can be used in a variety of different wetting sequences implemented by the tool. Such wetting sequences may include: multiple wetting cycles with a wetting solution with a pH of 2.0 or lower and / or a temperature range of 20 to 50°C; one or more wetting cycles with a wetting solution with a pH of 2.0 or lower and / or a temperature range of 20 to 50°C; additional wetting cycles with a wetting solution lacking one or both of these characteristics (e.g., pH greater than 2.0 and / or temperature less than 20°C); additional wetting cycles with DI water; and so on.

[0014] In other embodiments, the wetting chamber can be implemented in a variety of different types of tools. For example, the tool can be a standalone wetting tool with one or more wetting chambers. Alternatively, the tool can be a type of hybrid tool that includes one or more wetting chambers as well as other capacities, such as one or more electroplating chambers. Attached Figure Description

[0015] The present application and its advantages can be best understood by referring to the following description in conjunction with the accompanying drawings.

[0016] Figure 1 This is a block diagram of a wetting tool that can be used to wet a substrate according to a non-exclusive embodiment of the present invention.

[0017] Figures 2A to 2D This is a cross-sectional view of a feature on a semiconductor substrate being wetted according to a non-exclusive embodiment of the present invention.

[0018] Figure 3 This is a flowchart illustrating a first chemical and heating wetting process according to a non-exclusive embodiment of the present invention.

[0019] Figure 4 This is a flowchart illustrating a second chemical and heating wetting process according to a non-exclusive embodiment of the present invention.

[0020] In the accompanying drawings, similar reference numerals are sometimes used to indicate similar structural elements. It should also be understood that the descriptions in the drawings are schematic and not necessarily drawn to scale. Detailed Implementation

[0021] This application will now be described in detail with reference to some non-exclusive embodiments thereof, as illustrated in the accompanying drawings. Numerous specific details are set forth in the following description to provide a thorough understanding of this disclosure. However, it will be apparent to those skilled in the art that this disclosure may be practiced without some or all of these specific details. In other instances, well-known processing steps and / or structures have not been described in detail to avoid unnecessarily obscuring this disclosure.

[0022] Reference Figure 1 A block diagram of a wetting tool 10 for wetting a substrate is shown. In a non-exclusive embodiment, the wetting tool 10 can be used to wet a semiconductor substrate prior to electroplating.

[0023] The wetting tool 10 includes a chamber 12, a substrate base 14 for supporting a substrate 16 such as a semiconductor wafer, and a mechanism 18 for rotating the substrate base 14 and the substrate 16. In one embodiment, the mechanism 18 is capable of rotating the substrate base 14 and the substrate 16 at a rotational speed (rpm) ranging from 80 to 200. However, in other embodiments, other rpm values ​​or ranges may be used. For example, rpm values ​​of 40, 30, 20, or less may be used at the lower end of the range, while rpm values ​​of 200, 300, 400, or higher may be used at the higher end of the range. It should be noted that although specific rpm values ​​and / or ranges may be provided herein, any suitable rpm value or range may be used. Thus, the specific values ​​or ranges provided herein are merely exemplary and should not be construed as limiting.

[0024] The wetting tool 10 also includes a wetting solution dispensing system 20, which includes one or more wetting solution tanks 22 for storing one or more wetting solutions, a pH control system 24 for measuring and adjusting the pH of one or more wetting solutions stored in the tanks 22, a heater 26 for selectively heating the wetting solution, a deionized (DI) water supply 28, a three-way valve 30, and a nozzle 32 disposed in the chamber 12.

[0025] The wetting solution maintained in tank 22 may contain one or more of the following: (a) an inorganic acid, (b) an organic acid, (c) a dissolved gas in water, (d) a dissolved carbon dioxide in water, (e) DI water, (f) DI and degassed water, (g) carbonic acid, (h) sulfuric acid, and (i) methanesulfonic acid.

[0026] pH control system 24 is arranged to monitor the pH of the solution maintained in the tank. In various embodiments, pH control system 24 may rely on a pH probe, conductivity meter, density meter, or a combination thereof to measure the composition of the wetting solution. In various embodiments, the pH of at least one wetting solution is maintained at 2.0 or less. In other embodiments, the pH of one wetting solution may be 2.0 or less, while the pH of a second wetting solution may be 2.0 or higher. Further details regarding some non-exclusive wetting processes are provided below. The pH of the wetting solution can be adjusted as needed by pH control system 24 through: acid dosing if a decrease in pH is required; base dosing if a increase in pH is required; addition of DI water (whose pH is typically slightly below neutral or 7.0) if a decrease in pH is required; or gas dosing to increase or decrease the pH. For example, carbon dioxide gas can be used to decrease the pH of the wetting solution.

[0027] The heater 26 can be any type of heater capable of heating one or more wetting solutions held in the tank 22. In various non-exclusive embodiments, the heater 26 is capable of heating one or more wetting solutions in a temperature range of 20 to 50°C.

[0028] The three-way valve 30 can be selectively opened and closed to supply one or more wetting solutions held in the tank 22 and / or DI water from the dispenser 28 to the nozzle 32. In an alternative embodiment, the valve 30 can be controlled to supply both the wetting solution and the DI water to the nozzle 32.

[0029] Nozzle 32 is shown positioned at the top of chamber 12 for spraying wetting solution and / or DI water directly downwards onto the top surface of substrate 16. In other embodiments, nozzle 32 may be positioned on or adjacent to a sidewall of chamber 12; and / or multiple nozzles 32 (not shown) may be disposed at different locations within chamber 12. Regardless of the number and / or location of nozzles 32, the purpose is to supply wetting solution and / or DI water to the top surface of substrate 16 while rotating on base 18. In other non-exclusive embodiments, nozzle 32 may supply wetting solution and / or DI water at a rate of 0.6 to 2.4 liters per minute.

[0030] The wetting tool 10 may also optionally include a vacuum pump 34 and a valve 36. When the valve 36 is open and the pump 34 is operable, a vacuum pressure is generated within the chamber 12. In various non-exclusive embodiments, the vacuum pressure can range from 25 to 100 Torr and has a setpoint of approximately 70 Torr. It should be understood that these Torr values / ranges are merely exemplary and other Torr values / ranges may be used. In other embodiments, the wetting tool 10 may not include a vacuum pump 34. In this case, the chamber 12 is maintained at or near atmospheric pressure.

[0031] The wetting tool 10 also includes a gas supply 38 and a valve 40 for ventilation. When the valve 40 is open, gas from the supply 38 is introduced into the chamber 12. In various embodiments, the gas is nitrogen, argon, and / or atmospheric gas. In other embodiments, the ventilation pressure within the chamber 12 is in the range of 740 to 760.

[0032] The wetting tool 10 also includes a drain port 42, a drain valve 44, and an optional recirculation station 46. When the valve 44 is open, the wetting solution and / or DI water in the chamber 12 are removed via the drain port 42. In an optional embodiment, the recirculation station 46 may be used to clean and filter the discharged wetting solution and / or DI water so that it can be reused.

[0033] System controller 48 is used to control the operation of wetting tool 10 before, during, and after wetting of substrate 16. According to various embodiments described in more detail below, system controller 48 controls various components, such as pH control system 24, heater 26, vacuum pump 34, and valves 30, 36, 40, and 44, to cooperate in wetting of substrate 16.

[0034] System controller 48 typically includes one or more non-transient computer-readable media devices for storing system control software or code, and a computer and one or more processors for executing the code. The term "non-transient computer-readable media" is generally used to refer to media such as main memory, secondary memory, removable memory, and storage devices such as hard disks, flash memory, disk drive memory, CD-ROMs, and other forms of permanent memory, and should not be construed as encompassing transient materials such as carrier waves or signals. Processors may include one CPU or computer, multiple CPUs or computers, analog and / or digital input / output connections, motor controller boards, etc.

[0035] In some implementations, the system controller 48 manages all or at least most of the activities of the management tool 10, which runs or executes system control software or code, including activities such as: controlling the timing of wetting operations, the flow rate, pH level and / or temperature of the wetting solution and / or DI water, the pressure level within the processing chamber 12, introducing the substrate 16 into and removing it from the chamber 12, etc.

[0036] The system controller 48 may also include a user interface (not shown). The user interface may include a display screen, a graphical software display indicating the operating parameters and / or processing conditions of the tool 10, and user input devices that allow a human operator to interact with the tool 10, such as an indicator device, keyboard, touch screen, microphone, etc.

[0037] The information transmitted between the various components of the system controller 48 and the tool 10 can be in the form of signals, such as electronic, electromagnetic, optical or other signals, which can be sent and / or received via any communication link that carries the signals and can be implemented using wiring or cable, fiber optic, telephone line, cellular telephone link, wireless or radio frequency link and / or other communication channels.

[0038] Figures 2A to 2D This is a cross-sectional view of the features on the semiconductor substrate before, during, and after wetting in the wetting tool 10.

[0039] Figure 2A A cross-sectional view is shown of substrate 16, copper seed layer 52 formed on substrate 16, and patterned resist layer 54 defining feature 56. Figure 2A Feature 56 is pre-wetting.

[0040] Figure 2BThe substrate 16 is shown during wetting by the wetting solution 58. However, bubbles 60 are present in this figure. As a result, the wetting solution cannot reach the seed layer 52 at the bottom of feature 56. As previously mentioned, the presence of bubbles (or other debris) is problematic because it may prevent or hinder the subsequent electroplating process, resulting in the formation of an uneven or poor-quality metal layer within feature 56 defined by patterned resist 54.

[0041] on the contrary, Figure 2C The substrate 16 is shown with feature 56 being filled downwards into seed layer 52 using wetting solution 58. As a result, the possibility of trapping bubbles 60 in the region above seed layer 52 defined by feature 54 and / or causing debris to accumulate in that region is significantly reduced or completely eliminated.

[0042] Figure 2D The formation of a metal layer 62 in feature 56 after wetting in a subsequent electroplating process step is shown. In this example, the electroplating process forms a high-quality metal layer of uniform thickness, which can be largely attributed to, as Figure 2C As shown, air bubbles and debris were removed in the previous wetting step.

[0043] The applicant has discovered several advantages to using a wetting solution with a pH of 2.0 or lower. Specifically, the resist material used to form feature 56 may be hydrophobic. This property tends to repel the wetting solution in areas where it is most needed (e.g., inside feature 56). However, using a wetting solution with a pH of 2.0 or lower allows for a chemical reaction with the resist material, making it more hydrophilic. As a result, the wetting solution is not repelled but rather attracted into feature 56, advantageously reducing the chance of bubble trapping and aiding in debris removal.

[0044] The applicant also discovered additional benefits by raising the temperature of the wetting solution to 20 to 50°C. At the elevated temperatures, the wetting solution alters surface dynamics, leading to particle delamination from the substrate. The elevated temperature can also facilitate the dissolution of any debris or oxides from the substrate surface.

[0045] Figure 3 Flowchart 70 illustrates the first chemical and / or thermal wetting process performed by tool 10 on substrate 16. The following steps are coordinated by system controller 48. It should be noted that the various parameters and values ​​provided below (e.g., pressure range, rpm rate, temperature range, flow rate, etc.) are exemplary and not intended to be construed as limiting. Other parameters and values ​​may be used.

[0046] In step 72, chamber 12 is closed and valve 36 is opened, thereby allowing vacuum pump 34 to generate a vacuum in chamber 12. In various embodiments, the vacuum pressure ranges from 25 to 100 Torr.

[0047] In step 74, mechanism 18 may be used to rotate substrate base 14 and substrate 16 at a rate that is any value ranging from 20 or less to 400 or more revolutions per minute (rpm). In a non-exclusive embodiment, this rate is 80 rpm. In an optional step 76, the wetting solution is heated by heater 26. In various embodiments, the temperature range is 20 to 50°C. In one particular embodiment, the temperature is 40°C.

[0048] In step 78, the wetting solution dispensing system 20 introduces the wetting solution into chamber 12 via nozzle 32. In a preferred but non-exclusive embodiment, the wetting solution is heated in the range of 20 to 50°C and has a pH level of 2.0 or lower. In an alternative embodiment, the wetting solution may be heated in the range of 20 to 50°C but has a pH level of 2.0 or higher. In yet another embodiment, the wetting solution has a pH level of 2.0 or lower but is not heated. In other embodiments, the wetting solution is introduced at a rate of 0.6 to 1.8 liters per minute.

[0049] In determination 80, system controller 48 tracks the amount of time the substrate has been exposed to the wetting solution. Before the predetermined time period expires, steps 76 and / or 78 are performed, resulting in the wetting solution being sprayed onto the substrate 16 while it is rotated within the chamber. In a non-exclusive embodiment, the predetermined time is 30 seconds. In other embodiments, the predetermined time can range from 10 seconds to 120 seconds. It should be noted that the substrate may undergo a single wetting / rotation cycle or multiple wetting / rotation cycles before the wetting time expires. In the latter case, each cycle may use a different or the same wetting solution.

[0050] In step 82, after the predetermined wetting time has elapsed, system controller 48 activates valve 40 to ventilate chamber 12 with a gas such as nitrogen. In various embodiments, the pressure within chamber 12 is in the range of 740 to 760 Torr during ventilation. In other alternative embodiments, the substrate may be rotated at a high rate after the wetting time has elapsed but before ventilation. By rotating the substrate at a high rate (e.g., about 400 rpm), excess wetting solution is shaken off the substrate.

[0051] In step 84, the system controller 48 activates valve 44, thereby allowing the discharge port 42 to discharge the wetting solution from chamber 12.

[0052] In an optional step 85, the discharged wetting solution can be recycled, filtered as needed, and then returned to the wetting solution tank 22 for later use.

[0053] In step 86, system controller 48 activates valve 30, thereby introducing DI water from supply 28 into chamber 12 via nozzle 32. In a non-exclusive embodiment, the substrate is exposed to DI water for approximately 60 seconds. In other embodiments, the duration of exposure to DI water may be longer or shorter than 60 seconds. Wetting chemicals are removed from the substrate by rinsing with DI water before any subsequent plating steps.

[0054] In step 88, mechanism 18 stops rotating substrate 16.

[0055] In step 90, the substrate is removed from chamber 12.

[0056] In the above embodiments, step 86, rinsing the substrate with DI water, essentially removes the wetting solution from the substrate. As a result, the continued reaction of the resist with the wetting solution is mitigated or eliminated. Removing the chemical wetting solution with DI water also minimizes solution transfer to the plating module. However, it should be noted that rinsing with DI water is optional. If there are no issues with further chemical reaction and chemical transfer of the resist layer, a rinsing step with DI water is unnecessary.

[0057] Reference Figure 4 A flowchart 100 is shown, which depicts a second chemical and / or thermal wetting process performed by tool 10 on substrate 16. Again, the steps outlined below are coordinated by system controller 48. Again, it should be noted that the various parameters and values ​​provided below (e.g., pressure range, rpm rate, temperature range, flow rate, etc.) are exemplary and not intended to be construed as limiting. Other parameters and values ​​may be used.

[0058] In step 101, the system controller 48 guides the mechanism 18 to rotate the substrate 16 on the substrate support 14.

[0059] In optional step 102, system controller 48 directs heater 26 to heat the wetting solution from storage tank 22. In various embodiments, the wetting solution is heated to a temperature range of 20 to 50°C. In one specific embodiment, the temperature is 40°C.

[0060] In optional step 104, system controller 48 opens valve 30, thereby allowing a wetting solution with a pH of 2.0 or lower to be sprayed into the chamber through nozzle 32.

[0061] Note that, for this particular embodiment, the wetting solution is sprayed onto the substrate without evacuating the chamber 12.

[0062] In decision 106, system controller 48 monitors the amount of time the substrate is exposed to a wetting solution with a pH of 2.0 or lower and / or heated to a temperature range of 20 to 50°C. If the predetermined time period has not been exceeded, steps 102 and / or 104 are performed. In various embodiments, the predetermined time period may be in the range of 10 to 120 seconds.

[0063] In step 108, after a predetermined time period has elapsed, the system controller 48 guides the DI water into the chamber via the valve 30. As a result, the rotating substrate 16 is rinsed with DI water sprayed from the nozzle 32. In various embodiments, the DI water rinsing can range from 10 to 120 seconds.

[0064] In step 110, system controller 48 opens valve 44, thereby allowing the wetting solution and DI water to drain from the chamber. In an optional step (not shown), the drained wetting solution and / or DI water can be recirculated by workstation 46.

[0065] In step 112, system controller 48 closes the chamber and opens valve 36. As a result, a vacuum pressure is generated in chamber 12 by vacuum pump 34. In various embodiments, the vacuum pressure can be in the range of 70 to 100 Torr.

[0066] In step 114, the system controller 48 opens valve 30, thereby allowing a wetting solution with a pH greater than 2.0 to be sprayed into chamber 12 through nozzle 32.

[0067] In decision 116, system controller 48 monitors the amount of time the substrate has been exposed to a wetting solution with a pH level greater than 2.0. If a predetermined time period has not been exceeded, step 114 continues. In various embodiments, the predetermined time period can range from 30 to 120 seconds.

[0068] In step 118, after the predetermined time period expires, the system controller 48 opens the valve 40, thereby allowing the chamber 12 to be ventilated with gas from the supply 38.

[0069] In step 120, DI water is sprayed into chamber 12 to rinse the rotating substrate.

[0070] In step 122, system controller 48 opens valve 42, thereby allowing the discharge of wetting solution and DI water. Again, the discharged wetting solution can optionally be recirculated at recirculation station 46.

[0071] Finally, in step 124, the wetted substrate is removed from chamber 12. Afterward, the substrate can be moved to the plating chamber for plating.

[0072] The advantage of the above process is that it makes the resist more hydrophilic while reducing the possibility of damaging the walls of feature 54. Therefore, this specific wetting sequence is advantageous for very small substrate features (e.g., linewidths of approximately 2.0 micrometers or less and spacing of 2.0 micrometers or less).

[0073] It should be noted that the above embodiments are merely exemplary and intended to illustrate possible sequences of wetting solutions using a pH of 2.0 or lower and / or heated in the range of 20 to 50°C. However, these specific processing steps should absolutely not be construed as limiting. Conversely, any processing step using a wetting solution with a pH of 2.0 or lower and / or heated in the range of 20 to 50°C can be combined with other wetting steps using solutions with a pH greater than 2.0, such as DI water.

[0074] In another alternative embodiment, the substrate wetting tool 10 may maintain the chamber 12 under vacuum pressure, wetting the substrate with a wetting solution having a pH level of 2.0 or less and / or heated in the range of 20 to 50°C while the substrate is supported and rotated by the substrate base, ventilating the chamber after a first predetermined time period and stopping wetting the substrate with the wetting solution, draining the wetting solution from the chamber, and wetting the substrate with a second wetting solution while the substrate is supported and rotated by the substrate base and the chamber is ventilated. For this embodiment, the wetting solution and the second wetting solution may be the same or different, may have a pH level of 2.0 or less or greater than 2.0, and / or may have a high temperature ranging from 20 to 50°C.

[0075] In another alternative embodiment, the substrate wetting tool 10 can maintain the chamber 12 under vacuum pressure, wet the substrate with a wetting solution having a pH level of 2.0 or less and / or heated in the range of 20 to 50°C while the substrate is supported and rotated by the substrate base, ventilate the chamber after a predetermined time period and stop wetting the substrate with the wetting solution, rinse the substrate with DI water after ventilating the chamber and stop wetting the substrate with the wetting solution, maintain the chamber under vacuum pressure for a second time, and wet the substrate a second time with a second wetting solution having a pH level greater than 2.0 while the substrate is supported and rotated by the substrate base.

[0076] Furthermore, the time the substrate is exposed to the wetting solution and / or DI water, the rpm rate, the vacuum pressure, the aeration pressure, etc., are all factors that can vary widely between processing steps and should not be construed as limiting the values ​​provided herein.

[0077] In other embodiments, the tool 10 containing the wetting chamber 12 can be implemented in a variety of different types of tools. For example, the tool can be a standalone wetting tool having one or more wetting chambers 12. Alternatively, the tool can be some type of hybrid tool that includes one or more wetting chambers 12 as well as other capacities, such as one or more electroplating chambers.

[0078] In addition, although semiconductor wafer substrates are mentioned in this article, it should be understood that the wetting tools described herein can be used with any type of substrate.

[0079] Although only some embodiments are described in detail, it should be understood that this application may be implemented in many other forms without departing from the spirit or scope of the disclosure provided herein. For example, the substrate may be a semiconductor wafer, a discrete semiconductor device, a flat panel display, or any other type of workpiece.

[0080] Therefore, embodiments of the present invention should be considered illustrative rather than restrictive, and are not limited to the details given herein, but may be modified within the scope of the appended claims and their equivalents.

Claims

1. A substrate wetting tool, comprising: Chamber; A substrate base for supporting a substrate within the cavity, the substrate having a patterned resist layer with defined features; as well as A wetting solution distribution system for introducing a wetting solution into the chamber, the wetting solution having a pH of 2.0 or lower and a temperature ranging from 20 to 50°C, the wetting solution filling the feature downwards to the seed layer of the feature. The resist layer is hydrophobic, and The wetting solution with a pH of 2.0 or lower reacts chemically with the resist layer, thereby making the resist layer more hydrophilic.

2. The substrate wetting tool of claim 1, further comprising a heater for heating the wetting solution to a temperature ranging from 20 to 50°C.

3. The substrate wetting tool of claim 1, further comprising a pH control system for maintaining the pH of the wetting solution at 2.0 or less.

4. The substrate wetting tool of claim 1, further comprising a recycling station for recirculating the wetting solution discharged from the chamber.

5. The substrate wetting tool of claim 1, further comprising a vacuum pump for generating a vacuum in the chamber.

6. The substrate wetting tool according to claim 1, further comprising a vent for venting the chamber.

7. The substrate wetting tool of claim 1, further comprising a discharge port for discharging the wetting solution from the chamber.

8. The substrate wetting tool according to claim 1, further comprising a mechanism for rotating the substrate base supporting the substrate.

9. The substrate wetting tool according to claim 1, wherein, The wetting solution distribution system further includes: a storage tank for storing the wetting solution; and one or more nozzles for spraying the wetting solution into the chamber.

10. The substrate wetting tool according to claim 1, wherein, The wetting solution is one of the following: inorganic acid, organic acid, aqueous gas solution, deionized water, and deionized and degassed water.

11. The substrate wetting tool according to claim 10, wherein, The wetting solution is one of the following: an aqueous solution of carbonic acid, sulfuric acid, methanesulfonic acid, and carbon dioxide.

12. The substrate wetting tool according to claim 1, further configured to: Maintain the chamber under vacuum pressure; The substrate is wetted with the wetting solution while being supported and rotated by the substrate base; After a predetermined time period, the chamber is ventilated and wetting of the substrate with the wetting solution is stopped; and After venting the chamber and stopping the wetting of the substrate with the wetting solution, the substrate is rinsed with deionized water.

13. The substrate wetting tool according to claim 1, further configured to: Maintain the chamber under vacuum pressure; The substrate is wetted with the wetting solution while being supported and rotated by the substrate base; After a first predetermined time period, the chamber is ventilated and the wetting of the substrate with the wetting solution is stopped; Discharge the wetting solution from the chamber; and While the substrate is supported by the substrate base and rotated to ventilate the chamber, the substrate is secondarily wetted with a second wetting solution. in, The wetting solution and the second wetting solution can be the same or different.

14. The substrate wetting tool according to claim 1, further configured to: Maintain the chamber under vacuum pressure; The substrate is wetted with the wetting solution while being supported and rotated by the substrate base; After a predetermined time period, the chamber is ventilated and the wetting of the substrate with the wetting solution is stopped; After venting the chamber and stopping wetting the substrate with the wetting solution, the substrate is rinsed with deionized water. The chamber is maintained at the vacuum pressure for the second time; and While the substrate is supported and rotated by the substrate base, the substrate is second-wetted with a second wetting solution having a pH greater than 2.

0.

15. A substrate wetting tool, comprising: chamber; A substrate base for supporting a substrate within the cavity, the substrate having a patterned resist layer with defined features; as well as A wetting solution distribution system for introducing a wetting solution into the chamber, the wetting solution having a pH of 2.0 or lower, the wetting solution filling the feature downwards to the seed layer of the feature. The resist layer is hydrophobic, and The wetting solution with a pH of 2.0 or lower reacts chemically with the resist layer, thereby making the resist layer more hydrophilic.

16. The substrate wetting tool of claim 15, further comprising a heater for heating the wetting solution to a temperature in the range of 20 to 50°C.

17. The substrate wetting tool of claim 15, further comprising a pH control system for maintaining the pH of the wetting solution at 2.0 or less.

18. The substrate wetting tool of claim 15, further comprising a recycling station for recirculating the wetting solution discharged from the chamber.

19. The substrate wetting tool according to claim 15, wherein, The wetting solution is one of the following: inorganic acid, organic acid, aqueous gas solution, deionized water, and deionized and degassed water.

20. The substrate wetting tool according to claim 19, wherein, The wetting solution is one of the following: an aqueous solution of carbonic acid, sulfuric acid, methanesulfonic acid, and carbon dioxide.

21. The substrate wetting tool of claim 15, further comprising a vacuum pump for generating a vacuum pressure in the chamber when the wetting solution wets the substrate.

22. The substrate wetting tool according to claim 21, wherein, The vacuum pressure is in the range of 25 to 100 Torr.

23. The substrate wetting tool of claim 15, further comprising a base support for supporting and rotating the substrate when the substrate is wetted by the wetting solution.

24. The substrate wetting tool according to claim 23, wherein, The base support rotates the substrate at one of the following rates: (a) Rotational speeds ranging from 80 to 200 per minute; (b) 40 to 300 RPM; (d) 20 to 400 RPM; (e) Rotation speeds exceeding 400 RPM; (f) Less than 20 revolutions per minute.

25. The substrate wetting tool of claim 15, further comprising a vent for venting the chamber after the substrate has been wetted by the wetting solution for a predetermined period of time.

26. The substrate wetting tool of claim 25, comprising a base support for supporting and rotating the substrate after venting the chamber, wherein rotating the substrate after venting the chamber causes the wetting solution to be spun off from the substrate.

27. The substrate wetting tool according to claim 25, wherein, The wetting solution distribution system is also configured to wet the substrate a second time with deionized water.

28. The substrate wetting tool according to claim 27, wherein, The wetting solution distribution system is also configured to wet the substrate a third time with a second wetting solution with a pH greater than 2.

0.

29. The substrate wetting tool according to claim 28, wherein, The second wetting solution is at ambient temperature.

30. The substrate wetting tool according to claim 25, wherein, The wetting solution distribution system is further arranged to wet the substrate a second time with a second wetting solution, wherein the wetting solution and the second wetting solution are the same or different.

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