Liquid dispenser apparatus and apparatus for liquid treatment of a wafer-shaped article

Abstract

A liquid dispenser apparatus for use in an apparatus for liquid treatment of a wafer-shaped article, the liquid dispenser apparatus being configured to dispense a liquid, the liquid dispenser apparatus comprising: a part configured to contact the liquid; and a voltage supply configured to apply a voltage between the part and a reference point.

Description

[0001] LIQUID DISPENSER APPARATUS AND APPARATUS FOR LIQUID TREATMENT OF A WAFER-SHAPED ARTICLE

[0002] Field of the Invention

[0003] The present invention relates to a liquid dispenser apparatus and to an apparatus for liquid treatment of a wafer-shaped article that includes such a liquid dispenser apparatus.

[0004] Background

[0005] Wafers such as semiconductor wafers may be subjected to various surface treatment processes, such as etching, cleaning, polishing and material deposition.

[0006] At least some of these surface treatment processes involve applying a liquid to a surface of the wafer. For example, the surface of the wafer may be etched by applying an etching liquid such as hydrofluoric acid to the surface of the wafer. Alternatively, the surface of the wafer may be cleaned by applying a cleaning liquid or rinse liquid such as isopropyl alcohol or de-ionised water to the surface of the wafer.

[0007] The wafer may be spun when the liquid is applied to the surface of the wafer, for example using a rotatable chuck that holds the wafer, to assist the distribution of the liquid over the surface of the wafer. Where the liquid is a cleaning liquid or a rinse liquid, such a process may be referred to as a spin-clean process.

[0008] In addition, the surface of the wafer may subsequently be dried by heating the wafer to cause evaporation of the liquid on the surface of the wafer.

[0009] FIG. 1 is a schematic illustration of an apparatus 1 for liquid treatment of a wafer W, such as a semiconductor wafer, previously used by the present inventors

[0010] As shown in FIG. 1 , the apparatus 1 comprises a chuck 2 for holding a wafer W. For example, the chuck 2 may comprise a series of rotatable gripping pin assemblies that are rotatable to grip an outer edge of the wafer W to hold the wafer W on the chuck 2. The wafer W may be held spaced apart from an upper surface of the chuck 2.

[0011] The chuck 2 is mounted on a rotatable shaft 3, which can be driven to rotate by a motor. Therefore, the chuck 2 and thus the wafer W held by the chuck 2 can be driven to rotate. The chuck 2 may therefore be referred to as a spin chuck.

[0012] Typically, the chuck 2 is positioned within a chamber, to isolate the environment around the wafer W from an external environment.

[0013] As shown in FIG. 1 , a liquid dispenser 4 is positioned above the chuck 2, for selectively dispensing liquid onto an upper surface of the wafer W. The liquid dispenser 4 comprises a liquid dispenser arm 5 that is connected to a supply of a liquid. The supply of the liquid is generally indicated by element 6 in FIG. 1 , and may include a tank of the liquid and a pump for pumping the liquid from the tank to the liquid dispenser arm 5, for example. The liquid may be an etching liquid or a cleaning or rinse liquid, for example.

[0014] The liquid dispenser 4 further comprises a nozzle 7 at a distal end of the liquid dispenser arm 5. The liquid is dispensed from the liquid dispenser 4 onto the surface of the wafer W via the nozzle 7.

[0015] The liquid dispenser arm 5 includes a flow passage for providing the liquid to the nozzle 7 from the supply of the liquid 6. Typically, the flow passage comprises one or more tubes, which are typically made of a material that is not reactive to the liquid being dispensed. For example, the one or more tubes may comprise or be made of perfluoroalkoxy (PFA) or polytetrafluoroethylene (PTFE).

[0016] The liquid dispenser arm 5 may be pivotable or movable linearly to a standby position in which it does not overlie the wafer W, to facilitate loading and unloading of the wafer W on the chuck 2.

[0017] Generally, a controller 8 controls the overall operation of the apparatus 1 , including coordinating the action of the motor to rotate the chuck 2 and the action of the liquid dispenser 4 to dispense liquid from the supply of the liquid 6, so that liquid is controllably dispensed onto the surface of the wafer W while the wafer W is rotated.

[0018] A heating arrangement may be provided to selectively heat the wafer W to evaporate the liquid after the processing of the wafer W. For example, an array of LED heating elements may be located within the chuck 2 and arranged to heat an underside of the wafer W held by the chuck 2.

[0019] When the liquid flows through the one or more tubes in the liquid dispenser arm 5, the liquid can become electrically charged. In particular, the liquid may become electrically charged due to the triboelectric effect between the liquid and the one or more tubes through which the liquid flows.

[0020] Typically, when the liquid flows through a tube made of PFA or PTFE, the liquid becomes positively charged and the tube becomes negatively charged.

[0021] Such charging of the liquid can have effects on the wafer or on processing of the wafer. For example, if the liquid dispensed onto the surface of the wafer is electrically charged, this may lead to electrical discharge occurring between the liquid and the wafer or between the liquid and part of the apparatus, which may lead to damage to the wafer or the apparatus, for example.

[0022] In addition, or alternatively, such charging of the liquid may change a chemical or physical behaviour of the liquid, and therefore subsequent chemical reactions between the wafer and the liquid may be sped up or slowed down. In addition, or alternatively, such charging of the liquid may lead to airborne particles being attracted to the liquid which may cause contamination problems. In addition, or alternatively, such charging of the liquid may lead to corrosion of one or more parts of the apparatus, for example corrosion of a copper part of the apparatus.

[0023] To try to address these problems, the present inventors have previously passed the liquid through a conductive part that is electrically connected to ground before the liquid is dispensed onto the surface of the wafer. Electrical charge can therefore be substantially removed from the liquid via the grounded conductive part. This has been found to effectively reduce the charge of the liquid when the liquid is dispensed on the wafer.

[0024] The present inventors have now realised that in some cases it may be advantageous for the liquid that is dispensed on the wafer to have either a positive or a negative electrical charge, and for that electrical charge to be controlled.

[0025] For example, the present inventors have realised that if the liquid has a controlled negative charge, this may help in reducing or preventing metal oxidation in some applications. Conversely, the present inventors have realised that if the liquid has a controlled positive charge, this may be used to modify an electrochemical process involving the liquid in some applications.

[0026] The present invention has been devised in light of the above considerations.

[0027] Summary of the Invention

[0028] The present inventors have realised that the charge of the dispensed liquid can be controlled by contacting the liquid with a part to which a voltage is applied before the liquid is dispensed onto the wafer.

[0029] Therefore, at its most general, the present invention relates to contacting the liquid with a part to which a voltage is applied before the liquid is dispensed onto the wafer.

[0030] According to a first aspect of the present invention there is provided a liquid dispenser apparatus for use in an apparatus for liquid treatment of a wafer-shaped article, the liquid dispenser apparatus being configured to dispense a liquid, the liquid dispenser apparatus comprising: a part configured to contact the liquid; and a voltage supply configured to apply a voltage between the part and a reference point.

[0031] With the first aspect of the present invention, the charge of the dispensed liquid can be controlled by controlling the voltage applied between the part and the reference point. For example, a magnitude of the charge may be changed by changing a magnitude of the applied voltage, and / or a sign of the charge (positive or negative) may be changed by changing a sign of the applied voltage (positive or negative).

[0032] The apparatus according to the first aspect of the present invention may have any one, or where compatible any combination, of the following optional features.

[0033] The liquid dispenser apparatus may alternatively be referred to as a liquid dispenser device, a liquid dispenser assembly, or a liquid dispenser, for example.

[0034] The liquid dispenser apparatus may be or comprise a mechanism, or system, or arrangement, or article, for dispensing liquid.

[0035] Dispensing a liquid may mean supplying or providing a liquid.

[0036] The liquid dispenser apparatus may be configured to be used in an apparatus for liquid treatment of a wafer-shaped article. Liquid treatment of a wafer-shaped article may comprise applying a liquid to at least part of a surface of the wafer-shaped article.

[0037] Liquid treatment of a wafer-shaped article may comprise etching the wafer-shaped article using an etching liquid, or cleaning or rinsing the wafer-shaped article using a cleaning or rinsing liquid such as water, deionised water or isopropyl alcohol, for example.

[0038] The wafer-shaped article may be a wafer, for example a semiconductor wafer such as a silicon wafer.

[0039] The wafer-shaped article may have a predetermined diameter, for example 300mm.

[0040] The part is configured to contact the liquid before the liquid is dispensed on a surface of the wafer-shaped article.

[0041] The part may be configured to contact the liquid while the liquid is flowing in the liquid dispenser apparatus.

[0042] The part may be configured to contact an outside of a flow of the liquid.

[0043] For example, the liquid may be configured to flow through the part such that the part surrounds and contacts a circumferential surface of the flow of the liquid.

[0044] The part may alternatively be referred to as an element, or a component, for example.

[0045] The part may have a length of greater than or equal to 20mm and less than or equal to 50mm, for example. For example, for a flow rate of the liquid of less than 300ml / min a length of the part may be approximately 30mm, whereas for a flow rate of the liquid of greater than or equal to 300ml / min the part may have a length of 40mm.

[0046] A length of the part may be predetermined or calculated based on a predetermined flow rate of the liquid in the liquid dispenser apparatus.

[0047] The voltage supply may comprise or be a power supply.

[0048] The voltage supply may be a DC (direct current) voltage supply.

[0049] The voltage supply may comprise a first connector that is configured to be electrically connected to the part and a second connector that is configured to be connected to the reference point.

[0050] The voltage applied by the voltage supply may be adjustable or settable.

[0051] The voltage supply may be directly electrically connected to the part, or indirectly electrically connected to the part.

[0052] The voltage supply may be directly electrically connected to the reference point, or indirectly electrically connected to the reference point.

[0053] The voltage supply may be electrically connected to the part by one or more cables or wires.

[0054] Applying a voltage between the part and the reference point means applying a potential difference between the part and the reference point. At least part of the part may be electrically conductive. In particular, at least part of the part may comprise or be made of one or more electrically conductive materials.

[0055] For example, all of the part may be electrically conductive, for example comprise or be made of one or more electrically conductive materials.

[0056] Alternatively, only part of the part may be electrically conductive, for example comprise or be made of one or more electrically conductive materials. For example, the part may comprise an electrically conductive layer or coating on a substrate or base layer that is not electrically conductive, for example that is an electrical insulator.

[0057] The reference point may be ground, or another part of the liquid dispenser apparatus, or a part of the apparatus for liquid treatment of a wafer-shaped article. For example, the reference point may comprise, or be connected to, a support of the apparatus for liquid treatment of a wafer-shaped article.

[0058] The liquid dispenser apparatus may comprise a liquid dispenser or liquid dispenser part or portion that is configured to dispense the liquid. The liquid dispenser may comprise a nozzle for dispensing the liquid.

[0059] The liquid dispenser may comprise the part. In other words, the part may be a part of the liquid dispenser, and / or may be included in or attached or connected to a housing of the liquid dispenser.

[0060] The part may be attached or connected to the liquid dispenser, for example to a housing of the liquid dispenser.

[0061] The liquid dispenser may comprise a housing or case. The housing or case may include one or more tubes along which the liquid is configured to flow.

[0062] The part may be arranged upstream of the liquid dispenser or downstream of the liquid dispenser.

[0063] Downstream in this context means in the direction of flow of the liquid as the liquid is being dispensed, and upstream in this context means in an opposite direction to the direction of flow of the liquid as the liquid is being dispensed.

[0064] The liquid dispenser apparatus may be configured to be connected to a supply of the liquid. For example, the liquid dispenser apparatus may comprise a connector for connecting the liquid dispenser apparatus to a tube that supplies the liquid to the liquid dispenser apparatus. Alternatively, the liquid dispenser apparatus may comprise the supply of the liquid.

[0065] The liquid dispenser may be configured to be connected to a supply of the liquid. For example, the liquid dispenser may comprise a connector for connecting the liquid dispenser to a tube that supplies the liquid to the liquid dispenser.

[0066] The supply of the liquid may comprise one or more of a tank or other container of the liquid, a pump for pumping the liquid from the tank or other container to the liquid dispenser apparatus or liquid dispenser, and a tube for conveying the liquid from the pump to the liquid dispenser apparatus or liquid dispenser. The supply of the liquid may also comprise a valve for controlling (e.g. preventing or allowing) the flow of the liquid to the liquid dispenser apparatus or liquid dispenser. Alternatively, or in addition, the liquid dispenser apparatus or liquid dispenser may comprise such a valve.

[0067] The liquid may be an etching liquid or a cleaning or rinse liquid, for example.

[0068] The liquid dispenser apparatus or liquid dispenser may comprise a tube for conveying the liquid. For example, the liquid dispenser apparatus or liquid dispenser may comprise one or more such tubes.

[0069] The tube may comprise or be made of perfluoroalkoxy (PFA) or polytetrafluoroethylene (PTFE), for example. However, other materials can be used for the tube. For example, the tube could be made of any non or low conductive material, for example polypropylene or polyvinyl chloride, for example.

[0070] One or more tubes may extend from an input portion of the liquid dispenser apparatus or liquid dispenser to an outlet or nozzle of the liquid dispenser apparatus or liquid dispenser.

[0071] The liquid dispenser apparatus may comprise a nozzle or dispensing portion configured to dispense the liquid. For example, the liquid dispenser apparatus may comprise a liquid dispenser that comprises the nozzle or dispensing portion.

[0072] The part may be located greater than or equal to 0m upstream from a tip of the nozzle and less than or equal to 3m upstream from the tip of the nozzle.

[0073] The part may be located greater than or equal to 0mm upstream from a tip of the nozzle and less than or equal to 300mm upstream from the tip of the nozzle, optionally greater than or equal to 0mm upstream from the tip of the nozzle and less than or equal to 100mm upstream from the tip of the nozzle.

[0074] The nozzle or dispensing portion may be configured to dispense the liquid vertically downwards.

[0075] The liquid dispenser apparatus may comprise a case or housing, for example that houses the tube. For example, the liquid dispenser apparatus may comprise a liquid dispenser that comprises the case or housing.

[0076] The case or housing may have an input connector which is configured to connect the liquid dispenser apparatus or liquid dispenser to a supply of a liquid.

[0077] The liquid dispenser apparatus or liquid dispenser may have an inlet through which the liquid enters the liquid dispenser apparatus or liquid dispenser, for example, the case or housing may have an inlet through which the liquid enters the case or housing.

[0078] The case or housing may have the nozzle or dispensing portion at an end of the case or housing.

[0079] The part may comprise a through-hole or channel through which the liquid is configured to flow. The liquid may therefore flow through the part, so that the liquid contacts the part.

[0080] The part may provide part of a liquid flow path of the liquid dispenser apparatus.

[0081] The part may be or comprise a fitting, or a nozzle, or a tube, or a rod, for example.

[0082] The part may be cylindrical, or tubular, or ring-shaped, or rod-shaped, for example. The liquid dispenser apparatus may comprise a nozzle or dispensing portion configured to dispense the liquid, and the part may be located at or adjacent to the nozzle or dispensing portion. For example, the liquid dispensing apparatus may comprise a liquid dispenser that comprises the nozzle or dispensing portion.

[0083] For example, the part may be located immediately below the nozzle or dispensing portion, so that the liquid passes thorough the part immediately after being dispensed from the nozzle or dispensing portion.

[0084] The voltage supply may be configured to apply a voltage of greater than or equal to -10kV and less than or equal to +1 OkV between the part and the reference point, optionally greater than or equal to -1 kV and less than or equal to +1 kV, optionally greater than or equal to -100V and less than or equal to +100V, optionally greater than or equal to -60V and less than or equal to +60V.A voltage applied between the part and the reference point by the voltage supply may be controllable and / or adjustable and / or variable and / or changeable.

[0085] The voltage supply may be configured to apply a predetermined voltage between the part and the reference point.

[0086] The applied voltage may be set or controlled by a controller or processor of the apparatus, for example.

[0087] Where the part is electrically conductive, it may comprise or be made of electrically conductive perfluoroalkoxy (PFA) or electrically conductive polytetrafluoroethylene (PTFE), for example. However, other electrically conductive materials can be used instead, for example inherently conductive polymers such as polyconjugated aromates, or conductive coatings such as SiC or diamond-like carbon. The part may comprise a conductive coating on a non-conductive substrate.

[0088] Alternatively, in some cases the part may comprise or be made of a low conductive material.

[0089] The electrically conductive PFA or the electrically conductive PTFE may comprise carbon black or carbon nanotubes, for example.

[0090] The liquid dispenser apparatus may be configured to selectively dispense a first liquid and a second liquid.

[0091] The liquid dispenser apparatus may comprise a first part configured to contact the first liquid and a second part configured to contact the second liquid.

[0092] The liquid dispenser apparatus may comprise one or more voltage supplies configured to apply a voltage between the first part and a reference point and to apply a voltage between the second part and a reference point.

[0093] Each of the first part and the second part may have any of the features of the part described above, unless incompatible.

[0094] Each of the one or more voltage supplies may have any of the features of the voltage supply described above, unless incompatible. Selectively dispensing the first and second liquids may mean that dispending of the first liquid can be controlled independently of dispensing of the second liquid, for example.

[0095] The voltage between the first part and the respective reference point and the voltage between the second part and the respective reference point may be the same or different. The respective reference points may also or alternatively be the same or different.

[0096] The first liquid and the second liquid may both be rinse liquids, for example deionised water or isopropyl alcohol. The first liquid may be deionised water and the second liquid may be isopropyl alcohol in one embodiment.

[0097] According to a second aspect of the present invention there is provided an apparatus for liquid treatment of a wafer-shaped article, the apparatus comprising: a support for supporting the wafer-shaped article; and the liquid dispenser apparatus of the first aspect of the present invention arranged to dispense the liquid onto a surface of the wafer-shaped article supported by the support.

[0098] The second aspect of the present invention may include any of the features of the first aspect of the present invention discussed above or below.

[0099] The support may be a chuck.

[0100] The support may be rotatable so as to rotate the wafer-shaped article. For example, the support may be a rotatable chuck, such as a spin chuck. The apparatus may comprise a motor for rotating the support.

[0101] At least part of the liquid dispenser apparatus may be movable over the surface of the wafer-shaped article, in order to dispense processing liquid on different parts of the wafer-shaped article. For example, the apparatus may comprise an X-Y stage, or an X-Y-Z stage, for moving a nozzle of the liquid dispenser apparatus relative to the wafer-shaped article, or at least part of the liquid dispenser apparatus may be pivotable or rotatable over the surface of the wafer-shaped article. For example, a liquid dispenser of the liquid dispenser apparatus may be movable over the surface of the wafer-shaped article.

[0102] The apparatus may further comprise the supply of the liquid connected to the liquid dispenser apparatus and configured to supply the liquid to the liquid dispenser apparatus. Alternatively, the liquid dispenser apparatus may comprise the supply of the liquid.

[0103] The support may comprise a plurality of contact elements configured to contact a peripheral edge of the wafer-shaped article to grip the wafer-shaped article therebetween, and at least one of the plurality of contact elements may be electrically connected to ground.

[0104] All of the plurality of contact elements may be electrically connected to ground.

[0105] The plurality of contact elements may comprise a plurality of pins.

[0106] The plurality of contact elements may comprise a plurality of rotatable gripping pin assemblies.

[0107] The plurality of contact elements may prevent or restrict lateral movement of the wafer-shaped article relative to the support. The at least one of the plurality of contact elements being electrically connected to ground may provide a closed path for current flow in the liquid across the surface of the wafer-shaped article, which may increase modulation of the charge of the surface of the wafer-shaped article by the liquid, for example.

[0108] The at least one of the plurality of contact elements may be electrically conductive. For example, the at least one of the plurality of contact elements may be made of one or more electrically conductive materials.

[0109] The apparatus may further comprise a controller or processor for controlling an operation of the apparatus. For example, the controller may comprise dispensing of the liquid by the liquid dispenser apparatus and / or rotation of the wafer-shaped article by the support.

[0110] According to a third aspect of the present invention there is provided a method of liquid treatment of a wafer-shaped article, the method comprising: dispensing a liquid onto the wafer-shaped article; and applying a voltage between a part in contact with the liquid before the liquid is dispensed onto the wafershaped article and a reference point.

[0111] The third aspect of the present invention may may include any of the features of the first aspect of the present invention discussed above or below.

[0112] The method of the third aspect of the present invention may be carried out using the liquid dispenser apparatus according to the first aspect of the present invention or with the apparatus according to the second aspect of the present invention.

[0113] The method may comprise setting the voltage applied between the part in contact with the liquid before the liquid is dispensed onto the wafer-shaped article and the reference point based on one or more target charge values of the wafer-shaped article at one or more respective radial positions of the wafer-shaped article after the liquid has been dispensed onto the wafer-shaped article.

[0114] The method may comprise setting the voltage applied between the part in contact with the liquid before the liquid is dispensed onto the wafer-shaped article and the reference point based on a target radial charge distribution of the wafer-shaped article after the liquid has been dispensed onto the wafer-shaped article. The target radial charge distribution may indicate wafer charge at different radial positions along a radius of the wafer-shaped article, for example.

[0115] The method may comprise setting a radial position of the wafer-shaped article at which the liquid is dispensed onto the wafer-shaped article based on one or more target charge values of the wafer-shaped article at one or more respective radial positions of the wafer-shaped article after the liquid has been dispensed onto the wafer-shaped article.

[0116] The method may comprise setting a radial position of the wafer-shaped article at which the liquid is dispensed onto the wafer-shaped article based on a target radial charge distribution of the wafer-shaped article after the liquid has been dispensed onto the wafer-shaped article. The target radial charge distribution may indicate wafer charge at different radial positions along a radius of the wafer-shaped article, for example. Of course, the method may comprise setting both the voltage applied and the radial position to achieve one or both of the effects mentioned above.

[0117] The invention includes the combination of the aspects and preferred features described except where such a combination is clearly impermissible or expressly avoided.

[0118] Summary of the Figures

[0119] Embodiments and experiments illustrating the principles of the invention will now be discussed with reference to the accompanying figures in which:

[0120] Figure 1 is a schematic illustration of an apparatus for liquid treatment of a wafer previously used by the present inventors.

[0121] Figure 2 is a schematic illustration of a liquid dispenser apparatus according to an embodiment the present invention.

[0122] Figure 3 is a schematic illustration of an apparatus for liquid treatment of a wafer according to an embodiment of the present invention that includes the liquid dispenser apparatus of FIG. 2.

[0123] Figure 4 is a schematic illustration of a conductive fitting that can be used in an embodiment of the present invention.

[0124] Figure 5 is a graph of experimental data obtained using an embodiment of the present invention.

[0125] Figure 6 is a graph of experimental data obtained using an embodiment of the present invention.

[0126] Figure 7 is a graph of experimental data obtained using an embodiment of the present invention.

[0127] Figure 8 is a schematic illustration of a liquid dispenser apparatus according to an embodiment the present invention. Detailed Description of the Invention

[0128] Aspects and embodiments of the present invention will now be discussed with reference to the accompanying figures. Further aspects and embodiments will be apparent to those skilled in the art. All documents mentioned in this text are incorporated herein by reference.

[0129] FIG. 2 is a schematic illustration of a liquid dispenser apparatus according to an embodiment the present invention. FIG. 3 is a schematic illustration of an apparatus for liquid treatment of a wafer according to an embodiment of the present invention that includes the liquid dispenser apparatus of FIG. 2.

[0130] As illustrated in Figs. 2 and 3, the liquid dispenser apparatus 9 comprises a liquid dispenser 10 for dispensing a liquid onto a surface of a wafer. The liquid dispenser 10 comprises a case (or housing) 11 . The case 11 houses one or more tubes 13 for conveying a liquid. The one or more tubes 13 comprise or are made of perfluoroalkoxy (PFA) or polytetrafluoroethylene (PTFE), for example.

[0131] The case 11 has an inlet 15 which is configured to connect the liquid dispenser 10 to a supply of a liquid. For example, the inlet 15 may comprise a tube which can be connected to a tube of the supply of the liquid. Alternatively, the inlet 15 may be an input connector that can be connected to the supply of the liquid. The supply of the liquid may include a tank of the liquid and a pump for pumping the liquid from the tank to the liquid dispenser 10, for example. The liquid may be an etching liquid or a cleaning or rinse liquid, for example. The supply of the liquid may be part of the liquid dispenser apparatus 9, or external to the liquid dispenser apparatus 9.

[0132] The one or more tubes 13 are connected to the inlet 15 so that when a supply of the liquid is connected to the inlet 15 the liquid is supplied to the one or more tubes 13.

[0133] Alternatively, the one or more tubes 13 may extend from the case 11 to be connected to a supply of the liquid externally to the case 11 , in which case a portion of the one or more tubes 13 that extend from the case 11 may form or provide the inlet 15.

[0134] Alternatively, the one or more tubes 13 may be connected to a supply of the liquid internally to the case 11 , for example by one or more further tubes that extend into the case 11 from the supply of the liquid, in which case the one or more further tubes may form or provide the inlet 15.

[0135] The liquid dispenser 10 further comprises a nozzle 17 (or dispensing portion) at which the liquid is configured to be dispensed. For example, the one or more tubes 13 may terminate at the nozzle 17 so that the liquid is dispensed from a distal end of the one or more tubes 13 at the nozzle 17. The liquid is dispensed vertically downwards from the nozzle 17, so that the liquid then travels vertically downwards to be dispensed on a wafer below the liquid dispenser 10, as discussed below in relation to FIG. 3.

[0136] The liquid dispenser apparatus 9 further comprises an electrically conductive fitting 19 that is arranged at or adjacent to the nozzle 17, for example immediately below the nozzle 17 as illustrated in FIG. 2. The electrically conductive fitting 19 comprises or is made of an electrically conductive material, for example electrically conductive PFA or electrically conductive PTFE. For example, the PFA or PTFE may comprise carbon black to make it electrically conductive. Of course, in other embodiment the electrically conductive fitting 19 may be positioned in a different location. For example, the electrically conductive fitting 19 may be included in the housing 11 , for example connected to the one or more tubes 13. Alternatively, the electrically conductive fitting 19 may be provided at the inlet 15. Alternatively, the electrically conductive fitting 19 may be provided upstream of the liquid dispenser 10 and not directly connected to the liquid dispenser 10. For example, the electrically conductive fitting may be connected to a tube that supplies the liquid from the supply of the liquid to the liquid dispenser 10.

[0137] The electrically conductive fitting 19 has a through-hole (or channel) 21 through which the liquid dispensed at the nozzle 17 is configured to flow before being dispensed onto a wafer below the liquid dispenser 10. The electrically conductive fitting 19 is therefore configured to contact the liquid before the liquid is dispensed onto the wafer. The electrically conductive fitting 19 may be cylindrical, or tubular, or ring-shaped, for example.

[0138] Of course, in other embodiments the electrically conductive fitting may have a different shape, for example rod shaped.

[0139] In other embodiments the electrically conductive fitting 19 may be replaced with a different part, for example a tube, or a rod, or a ring, which may or may not be electrically conductive.

[0140] The liquid dispenser apparatus 9 further comprises a power supply 23 that is electrically connected to the electrically conductive fitting 19 and is configured to apply a voltage between the electrically conductive fitting 19 and ground. The power supply 23 is controllable to apply a predetermined voltage between the electrically conductive fitting 19 and ground. The predetermined voltage may be adjustable, for example in the range of greater than or equal to -1 OkV to less than or equal to -1 OkV, or greater than or equal to - 1 kV to less than or equal to +1 kV, or greater than or equal to -100V to less than or equal to +100V, or greater than or equal to -60V to less than or equal to +60V.

[0141] Of course, the voltage does not need to be applied between the electrically conductive fitting 19 and ground, and instead may be applied between the electrically conductive fitting 19 and a different reference point. For example, the reference point could be another part of the liquid dispenser apparatus 9, or a part of the apparatus 25 discussed below.

[0142] As discussed in more detail below in relation to FIGS. 5 and 6, by applying a voltage between the electrically conductive fitting 19 and ground while the liquid is being passed through the electrically conductive fitting 19, an electric charge of the liquid when the liquid is dispensed on the wafer can be controlled.

[0143] The electrically conductive fitting 19 is electrically isolated from a remainder of the liquid dispenser 10, to avoid any other parts of the liquid dispenser 10 from having the applied voltage. For example, a remainder of the liquid dispenser 10, or at least a part of the liquid dispenser 10 to which the electrically conductive fitting 19 is connected, may be made of an electrically insulating material, for example a non- conductive plastic material. Alternatively, or in addition, the electrically conductive fitting 19 may be connected to another part of the liquid dispenser 10 via a layer of electrically insulating material. Of course, in other embodiments of the liquid dispenser apparatus 9 there may be more than one tube in the case 11 . For example, multiple tubes may be provided, each of which is connected to a different type of liquid, so that different liquids can be dispensed from the liquid dispensed 0.

[0144] In addition, more than one tube may be connected in series in the liquid dispenser apparatus 9 for conveying the liquid in the liquid dispenser apparatus 9, such that it is not essential for the liquid to be conveyed by a single tube in the liquid dispenser apparatus 9.

[0145] In other embodiments the one or more tubes 13 may be replaced with another type of flow path or passageway, for example one or more bores or channels or pipes.

[0146] As mentioned above, in other embodiments the one or more tubes 13 may extend outside of the case 11 to be connected to the supply of the liquid externally to the case 11 . Alternatively, the one or more tubes 13 may be connected to the supply of the liquid internally to the case 11 , by one or more further tubes that extend into the case 11 from the supply of the liquid.

[0147] In addition, or alternatively, in other embodiments the liquid dispenser apparatus 9 may comprise additional parts. For example, the liquid dispenser apparatus 9 may comprise one or more valves for controlling the dispensing of liquid from the liquid dispenser apparatus 9, for example a check valve to reduce dripping from the liquid dispenser apparatus 9. Alternatively, or in addition, one or more valves may be provided externally to the liquid dispenser apparatus 9, for example as part of the supply of the liquid, for controlling the supply of the liquid to the liquid dispenser apparatus 9. The one or more valves may be provided in the liquid dispenser 10.

[0148] In FIG. 2 the electrically conductive fitting 19 is illustrated as being located immediately adjacent to the nozzle 17 of the liquid dispenser 10. In other embodiments, the electrically conductive fitting 19 may be integral to the nozzle 17, or included in the nozzle 17, or may be the nozzle 17. Alternatively, in other embodiments, the electrically conductive fitting 19 may be located elsewhere in the liquid dispenser 10, for example inside the case 11 , or upstream of (before) the liquid dispenser 10. For example, in some embodiments the electrically conductive fitting may be located in the liquid dispenser 10 connected between two tubes of the liquid dispenser 10 so that the liquid flows between the two tubes via the electrically conductive fitting.

[0149] In general, it is preferable for the electrically conductive fitting 19 to be close to where the liquid is dispensed from the liquid dispenser 10, otherwise it is possible that further flow of the liquid through one or more tubes subsequent to the liquid passing through the electrically conductive fitting 19 may lead to further electric charge building up in the liquid before it is dispensed onto the wafer.

[0150] In alternative embodiments, the electrically conductive fitting 19 may be spaced apart from the case 11 rather than connected to the case 11 as illustrated in FIG. 2.

[0151] FIG. 3 is a schematic illustration of an apparatus for liquid treatment of a wafer according to an embodiment of the present invention that includes the liquid dispenser apparatus 9 of FIG. 2. Liquid treatment of a wafer may comprise etching of the wafer, or cleaning or rinsing of the wafer, for example.

[0152] The liquid dispenser apparatus of FIG. 2 is illustrated using the reference sign 9 in FIG. 3 and the other reference signs of FIG. 2 are omitted for conciseness. However, the liquid dispenser apparatus 9 in FIG. 3 includes all the features of the liquid dispenser apparatus 9 in FIG. 2.

[0153] As illustrated in FIG. 3, the apparatus 25 comprises the liquid dispenser apparatus 9 of FIG. 2. The liquid dispenser 10 is connected via a further tube 27 to a supply 29 of the liquid. In particular, the further tube 27 is connected to the input connector 15. The supply 29 of the liquid may include a tank of the liquid and a pump for pumping the liquid from the tank to the liquid dispenser 10, for example. The supply of the liquid 29 may also comprise one or more tubes including the further tube 27 for conveying the liquid to the liquid dispenser 10. The liquid may be an etching liquid or a cleaning or rinse liquid, for example. The liquid dispenser apparatus 9 may comprise the further tube 27 and the supply 29 of the liquid.

[0154] The supply 29 of the liquid may further comprise one or more valves for selectively controlling the supply of the liquid to the liquid dispenser 10. Alternatively, or in addition, the liquid dispenser 10 may comprise one or more valves for selectively controlling the flow of the liquid through the liquid dispenser 10.

[0155] As shown in FIG. 3, the apparatus 25 further comprises a chuck 31 for holding a wafer W. The chuck 31 comprises a series of rotatable gripping pin assemblies 32 that are rotatable around a longitudinal axis thereof to grip an outer edge of the wafer W to hold the wafer W on the chuck 31 . The wafer W may be held spaced apart from an upper surface of the chuck 31 .

[0156] In this embodiment, each of the rotatable gripping pin assemblies 32 is electrically connected to ground.

[0157] Furthermore, in this embodiment, each of the rotatable gripping pin assemblies comprises an electrically conductive pin that contacts a peripheral edge of the wafer. The electrically conductive pin is at least partly made from one or more electrically conductive materials.

[0158] The chuck 31 is mounted on a rotatable shaft 33, which can be driven to rotate by a motor. Therefore, the chuck 31 and thus the wafer W held by the chuck 31 can be driven to rotate. The chuck 31 may therefore be referred to as a spin chuck.

[0159] Typically, the chuck 31 is positioned within a chamber, to isolate the environment around the wafer W from an external environment.

[0160] The liquid dispenser 10 is positioned above the chuck 31 for selectively dispensing liquid onto an upper surface of the wafer W.

[0161] The liquid dispenser 10 may be pivotable or movable linearly to a standby position in which it does not overlie the wafer W, to facilitate loading and unloading of the wafer W on the chuck 31 .

[0162] More generally, the liquid dispenser 10 may be pivotable or movable linearly over the surface of the wafer W so as to position a dispense position of the liquid dispenser 10 above different locations on the wafer W. The apparatus 25 further comprises a controller (or processor) 35 that controls the overall operation of the apparatus 25. For example, the controller 35 may coordinate the action of the motor to rotate the chuck 31 and the action of the liquid dispenser apparatus 9 to dispense liquid from the supply 29 of the liquid onto the wafer W, so that liquid is controllably dispensed onto the surface of the wafer W while the wafer W is rotated.

[0163] Controlling the dispensing of liquid by the liquid dispenser apparatus 9 may comprise one or more of starting operation of a pump in the supply 29 of the liquid to pump the liquid to the liquid dispenser 10 and opening a valve in the supply 29 of the liquid or in the liquid dispenser 10 so as to allow flow of the liquid to or through the liquid dispenser 10.

[0164] The controller 35 may also control the power supply 23 to apply a predetermined voltage between the electrically conductive fitting 19 and ground at least during the dispensing of the liquid by the liquid dispenser apparatus 9.

[0165] A heating arrangement may be provided to selectively heat the wafer W to evaporate the liquid after the liquid treatment of the wafer W. For example, an array of LED heating elements may be located within the chuck 31 and arranged to heat an underside of the wafer W held by the chuck 31 .

[0166] FIG. 4 is a schematic illustration of an electrically conductive fitting 37 that can be used in an embodiment of the present invention. In this embodiment, the electrically conductive fitting 37 is configured to be connected between two components, for example between a first tube and a second tube. In particular, the electrically conductive fitting 37 has a first connector portion 39 and a second connector portion 41 , each of which is configured to be inserted into the open end of a respective tube, or each of which is configured to receive the end of a respective tube. Furthermore, the electrically conductive fitting 37 has a longitudinal through-hole (or channel) 43 through which liquid can flow from a first end of the electrically conductive fitting 37 at which the first connector portion 39 is located to a second end of the electrically conductive fitting 37 at which the second connector portion 41 is located. Therefore, when the first and second tubes are connected to the electrically conductive fitting 37, liquid can flow from the first tube to the second tube through the longitudinal through-hole 43 of the electrically conductive fitting 37.

[0167] Furthermore, while the liquid flows through the longitudinal through-hole 43, the liquid is in contact with the electrically conducive fitting 37. Therefore, when a power supply is electrically connected to the electrically conductive fitting 37 via a cable and a voltage is applied between the electrically conductive fitting 37 and gruond, that voltage is applied to the liquid flowing through the electrically conductive fitting 37.

[0168] Of course, in other embodiments the electrically conductive fitting can have a different configuration to that illustrated in FIG. 4. For example, it is not essential for the electrically conductive fitting to be connected between two tubes, in which case it is not essential for the electrically conductive fitting to have first and second connector portions as in FIG. 4. In addition, or alternatively, in other embodiments the connection between the electrically conductive fitting and one or more tubes may be different to the first and second connector portions illustrated in FIG. 4. FIGS. 5 and 6 illustrate some experimental data obtained using an embodiment of the present invention.

[0169] FIG. 5 illustrates the measured charge of liquid being dispensed from the liquid dispenser (for example the liquid dispenser 10 of FIG. 2) against the voltage applied to the electrically conductive fitting by the power supply. The charge of the liquid was measured using a Faraday cup and a nano coulombmeter. The liquid being dispensed in this case was isopropyl alcohol at approximately 45°C, the flow rate of the liquid was 250-300 ml / min, and the liquid was dispensed into the Faraday cup for a dispense time of 60 seconds

[0170] As illustrated in FIG. 5, with neither ground (GRND) nor a voltage applied to the electrically conductive fitting the dispensed liquid has a relatively large electrical charge, due to the liquid being charged up triboelectrically while flowing through the tube in the liquid dispenser. This is indicated by the “Baseline, no GRND” bars in FIG. 5 (first and last bars). When the electrically conductive fitting is connected to ground (“GRND” bar), the electrical charge of the dispensed liquid is reduced to approximately zero. By applying a negative voltage to the electrically conductive fitting (“-30V” and “-15V” bars) the electrical charge of the dispensed liquid can be controlled to be a negative charge, as illustrated in FIG. 5. Conversely, by applying a positive voltage to the electrically conductive fitting (“+15V” and “+30V” bars) the electrical charge of the dispensed liquid can be controlled to be a positive charge, as illustrated in FIG. 5.

[0171] Therefore, the electrical charge of the dispensed liquid can be controlled to be positive or negative, and the magnitude of the charge can be varied, by appropriately setting the voltage that is applied to the electrically conductive fitting in the embodiments of the present invention.

[0172] FIG. 6 illustrates the dependence of the charge of the dispensed liquid on the voltage applied to the electrically conductive fitting in an embodiment of the present invention. The experimental variables are the same as described above for FIG. 5.

[0173] As illustrated in FIG. 6, there is an approximately linear relationship between the electrical charge of the dispensed liquid and the voltage applied to the electrically conductive fitting. Therefore, by controlling the voltage applied to the electrically conductive fitting, the electrical charge of the dispensed liquid can be precisely controlled to be a desired value.

[0174] Similar experimental data is obtained when using deionised water instead of isopropyl alcohol.

[0175] FIG. 7 illustrates some further experimental data obtained using an embodiment of the present invention. Specifically, FIG. 7 illustrates measured wafer charge (in mV) at different radial positions (in mm) along a radius of a 300mm wafer in different circumstances.

[0176] The three lines labelled “Pre (all together)” in FIG. 7 illustrate the measured wafer charge (in mv) at different radial positions (in mm) before any liquid has been dispensed on the wafer for three different wafers. The charge distributions for these wafers may have been caused by previous processing steps performed on the wafer, for example. The line labelled “Ground” in FIG. 7 shows the measured wafer charge (in mv) at different radial positions (in mm) after liquid has been dispensed on the wafer using a liquid dispenser apparatus similar to that in FIG. 2 in which the electrically conductive fitting 19 is electrically connected to ground.

[0177] The other two lines labelled “+60V” and “-60V” show the measured wafer charge (in mv) at different radial positions (in mm) after liquid has been dispensed on the wafer using a liquid dispenser apparatus 9 according to an embodiment the present invention, with a potential difference of +60V and -60V respectively applied between the electrically conductive fitting 19 and ground by the power supply 23.

[0178] As shown in FIG. 7, the radial charge distribution of the wafer after the liquid has been dispensed on the wafer can be significantly changed by changing the potential difference applied between the electrically conductive fitting 19 and ground by the power supply 23. For example, the radial charge distribution for the “+60V” case is significantly different to the radial charge distribution for the “-60V” case.

[0179] For all of the above lines, the experimental data was obtained by dispensing water as the liquid, for example ultrapure water.

[0180] In addition, for all of the above lines, the wafer is a processed wafer. Specifically, the wafers used to obtain the experimental data were thermal oxide wafers with 1000A thickness of oxide.

[0181] Furthermore, for all of the above lines, the measured wafer charge is the remaining charge on the wafer after the liquid has been dispensed and the liquid subsequently removed from the wafer, for example by spinning and / or heating the wafer. The wafer charge can be measured in different ways, for example using a non-contact probe that detects differences in surface potential.

[0182] With the present invention, it is possible to control the radial charge distribution of the wafer after dispensing of the liquid to be the same as, or close to, a target or desired wafer charge distribution by appropriately setting one or more of (i) the potential difference applied between the electrically conductive fitting 19 and ground by the power supply 23, and (2) a radial position at which the liquid is dispensed on the wafer.

[0183] Fig. 8 is a schematic illustration of a liquid dispenser apparatus according to a further embodiment the present invention.

[0184] As illustrated in FIG. 8, the liquid dispenser apparatus 45 comprises a liquid dispenser 47 for dispensing first and second liquids onto a surface of a wafer. The liquid dispenser 47 comprises a case (or housing) 49.

[0185] The case 49 houses a first tube 51 for conveying a first liquid and a second tube 53 for conveying a second liquid. The first and second tubes 51 , 53 comprise or are made of perfluoroalkoxy (PFA) or polytetrafluoroethylene (PTFE), for example.

[0186] The case 49 further comprises a first inlet 55 which is configured to connect the first tube 51 to a supply of the first liquid. For example, the first inlet 55 may comprise a tube which can be connected to a tube of the supply of the first liquid. Alternatively, the first inlet 55 may be an input connector that can be connected to the supply of the first liquid. The supply of the first liquid may include a tank of the first liquid and a pump for pumping the first liquid from the tank to the liquid dispenser 47, for example.

[0187] The supply of the first liquid may be part of the liquid dispenser apparatus 45, or external to the liquid dispenser apparatus 45.

[0188] The first tube 51 is connected to the first inlet 55 so that when a supply of the first liquid is connected to the first inlet 55 the first liquid is supplied to the first tube 51 .

[0189] Alternatively, the first tube 51 may extend from the case 49 to be connected to a supply of the first liquid externally to the case 49, in which case a portion of the first tube 51 that extends from the case 49 may form or provide the first inlet 55.

[0190] Alternatively, the first tube 51 may be connected to a supply of the first liquid internally to the case 49, for example by one or more further tubes that extend into the case 49 from the supply of the first liquid, in which case the one or more further tubes may form or provide the first inlet 55.

[0191] In addition, as illustrated in FIG. 8, the liquid dispenser 45 further comprises a second inlet 57 which is configured to connect the second tube 53 to a supply of the second liquid. The second inlet 57 and the supply of the second liquid have the same features as the first inlet 55 and the supply of the first liquid described above in this embodiment so are not described further here for conciseness.

[0192] The liquid dispenser 45 further comprises a nozzle 59 (or dispensing portion) at which the first liquid and the second liquid are configured to be dispensed.

[0193] For example, the first tube 51 and the second tube 53 may both terminate at the nozzle 59, so that the first and second liquids are dispensed from distal ends of the first and second tubes 51 , 53 at the nozzle 59.

[0194] The first and second liquids may be dispensed vertically downwards from the nozzle 59, so that the first and second liquids then travel vertically downwards to be dispensed on a wafer below the liquid dispenser 47. Alternatively, the first and / or second liquid may be dispensed at a non-zero angle to the vertical from the nozzle 59.

[0195] The liquid dispenser apparatus 45 is configured to selectively dispense either the first liquid or the second liquid from the liquid dispenser 47. In other words, the first and second liquids may not be dispensed simultaneously. For example, the liquid dispenser apparatus 45 may be configured to selectively control a first pump or valve that controls supply of the first liquid to the first tube 51 and a second pump or valve that controls supply of the second liquid to the second tube 53 in order to selectively dispense the first and second liquids.

[0196] As illustrated schematically in FIG. 8, the liquid dispenser 47 further comprises a first electrically conductive fitting 61 provided in or on or connected to the first tube 51 and a second electrically conductive fitting 63 provided in or on or connected to the second tube 53. Each of the first and second electrically conductive fittings 61 , 63 comprises or is made of an electrically conductive material, for example electrically conductive PFA or electrically conductive PTFE. For example, the PFA or PTFE may comprise carbon black to make it electrically conductive.

[0197] Of course, in other embodiments the first and second electrically conductive fitting 61 , 63 may be positioned in a different location. For example, the first and second electrically conductive fittings 61 , 63 may be included outside of the housing 49, for example at the first and second inlets 55, 57, or at the nozzle 59. Alternatively, the first and second electrically conductive fittings 61 , 63 may be provided upstream of the liquid dispenser 47 and not directly connected to the liquid dispenser 47. For example, the first and second electrically conductive fittings 61 , 63 may be connected to tubes that supply the first and second liquids from the supplies of the first and second liquids to the liquid dispenser 47.

[0198] The first and second electrically conductive fittings 61 , 63 each has a through-hole (or channel) through which the first or second liquid flowing in the first or second tube 51 , 53 is configured to flow while contacting the first or second electrically conductive fitting 61 , 63 before being dispensed from the nozzle 59 onto a wafer below the liquid dispenser 47. The first and second electrically conductive fittings 61 , 63 are therefore configured to contact the first and second liquids respectively before the first or second liquid is dispensed onto the wafer. The first and second electrically conductive fittings 61 , 63 may be cylindrical, or tubular, or ring-shaped, for example.

[0199] Of course, in other embodiments the first and second electrically conductive fittings 61 , 63 may have a different shape.

[0200] In some embodiments, the first electrically conductive fitting 61 may have a different shape and / or be made of a different material to the second electrically conductive fitting 63.

[0201] As illustrated in FIG. 8, the liquid dispenser apparatus 45 further comprises a power supply 23 that is electrically connected to both the first and second electrically conductive fittings 61 , 63 and is configured to apply a voltage between each of the first and second electrically conductive fittings 61 , 63 and ground.

[0202] The power supply 23 is controllable to apply a predetermined voltage between each of the first and second electrically conductive fittings 61 , 63 and ground. The predetermined voltage may be adjustable, for example in the range of greater than or equal to -1 OkV to less than or equal to -1 OkV, or greater than or equal to -1 kV to less than or equal to +1 kV, or greater than or equal to -100V to less than or equal to +100V, or greater than or equal to -60V to less than or equal to +60V.

[0203] Of course, the voltage does not need to be applied between each of the first and second electrically conductive fittings 61 , 63 and ground, and instead may be applied between each of the first and second electrically conductive fitting 61 , 63 and a different reference point. For example, the reference point could be another part of the liquid dispenser apparatus 45, or a part of a further apparatus that includes the liquid dispenser apparatus 45.

[0204] In FIG. 8 the power supply 23 is illustrated schematically as being separately connected to each of the first and second electrically conductive fittings 61 , 63, but instead the power supply 23 could be electrically connected directly to only one of the fittings which could then be electrically connected to the other one of the fittings.

[0205] In an alternative embodiment, the power supply 23 may be replaced with a first power supply that is electrically connected to the first electrically conductive fitting 61 and that is configured to apply a first voltage between the first electrically conductive fitting 61 and ground and a second power supply that is electrically connected to the second electrically conductive fitting 63 and that is configured to apply a second voltage between the second electrically conductive fitting 63 and ground. The first and second voltages may be the same or may be different. Each of the first and second power supplies may otherwise have any of the features of the power supply 23 described above, unless incompatible.

[0206] One of the first and second liquids may be a rinsing liquid, such as deionised water or isopropyl alcohol (IPA). In one embodiment, both the first and second liquids may be different rinsing liquids, for example the first liquid may be deionised water and the second liquid may be IPA.

[0207] The features disclosed in the foregoing description, or in the following claims, or in the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for obtaining the disclosed results, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

[0208] While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention.

[0209] For the avoidance of any doubt, any theoretical explanations provided herein are provided for the purposes of improving the understanding of a reader. The inventors do not wish to be bound by any of these theoretical explanations.

[0210] Any section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.

[0211] Throughout this specification, including the claims which follow, unless the context requires otherwise, the word “comprise” and “include”, and variations such as “comprises”, “comprising”, and “including” will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

[0212] It must be noted that, as used in the specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from “about” one particular value, and / or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and / or to the other particular value. Similarly, when values are expressed as approximations, by the use of the antecedent “about,” it will be understood that the particular value forms another embodiment. The term “about” in relation to a numerical value is optional and means for example + / - 10%.

Claims

Claims:1 . A liquid dispenser apparatus for use in an apparatus for liquid treatment of a wafer-shaped article, the liquid dispenser apparatus being configured to dispense a liquid, the liquid dispenser apparatus comprising: a part configured to contact the liquid; and a voltage supply configured to apply a voltage between the part and a reference point.

2. The liquid dispenser apparatus according to claim 1 , wherein at least part of the part is electrically conductive.

3. The liquid dispenser apparatus according to claim 1 or claim 2, wherein the reference point is ground, or another part of the liquid dispenser apparatus, or a part of the apparatus for liquid treatment of a wafer-shaped article.

4. The liquid dispenser apparatus according to any of the preceding claims, wherein the liquid dispenser apparatus comprises a liquid dispenser that is configured to dispense the liquid.

5. The liquid dispenser apparatus according to claim 4, wherein: the liquid dispenser comprises the part; and / or the part is attached or connected to the liquid dispenser; and / or the part is arranged upstream of the liquid dispenser or downstream of the liquid dispenser.

6. The liquid dispenser apparatus according to any of the preceding claims, wherein the liquid dispenser apparatus is configured to be connected to a supply of the liquid, or comprises the supply of the liquid.

7. The liquid dispenser apparatus according to any of the preceding claims, wherein the liquid dispenser apparatus comprises a tube for conveying the liquid.

8. The liquid dispenser apparatus according to any of the preceding claims, wherein the liquid dispenser apparatus comprises a nozzle configured to dispense the liquid.

9. The liquid dispenser apparatus according to claim 8, wherein the part is located greater than or equal to 0m upstream from a tip of the nozzle and less than or equal to 3m upstream from the tip of the nozzle.

10. The liquid dispenser apparatus according to claim 8 or 9, wherein the part is located greater than or equal to 0mm upstream from a tip of the nozzle and less than or equal to 300mm upstream from the tip of the nozzle, optionally greater than or equal to 0mm upstream from the tip of the nozzle and less than or equal to 100mm upstream from the tip of the nozzle.11 . The liquid dispenser apparatus according to any of the preceding claims, wherein the part comprises a through-hole through which the liquid is configured to flow.

12. The liquid dispenser apparatus according to any of the preceding claims, wherein the part provides part of a liquid flow path of the liquid dispenser apparatus.

13. The liquid dispenser apparatus according to any of the preceding claims, wherein the part is or comprises a fitting, or a nozzle, or a tube, or a rod.

14. The liquid dispenser apparatus according to any of the preceding claims, wherein the voltage supply is configured to apply a voltage of greater than or equal to -1 OkV and less than or equal to +1 OkV between the part and the reference point, optionally greater than or equal to -1 kV and less than or equal to +1 kV, optionally greater than or equal to -100V and less than or equal to +100V, optionally greater than or equal to -60V and less than or equal to +60V.

15. The liquid dispenser apparatus according to any of the preceding claims, wherein: the liquid dispenser apparatus is configured to selectively dispense a first liquid and a second liquid; the liquid dispenser apparatus comprises a first part configured to contact the first liquid and a second part configured to contact the second liquid; and the liquid dispenser apparatus comprises one or more voltage supplies configured to apply a voltage between the first part and a reference point and to apply a voltage between the second part and a reference point.

16. An apparatus for liquid treatment of a wafer-shaped article, the apparatus comprising: a support for supporting the wafer-shaped article; and the liquid dispenser apparatus of any of claims 1 to 15 arranged to dispense the liquid onto a surface of the wafer-shaped article supported by the support.

17. The apparatus according to claim 16, wherein the apparatus further comprises a supply of the liquid connected to the liquid dispenser apparatus and configured to supply the liquid to the liquid dispenser apparatus, or wherein the liquid dispenser apparatus comprises the supply of the liquid.

18. The apparatus according to claim 16 or claim 17, wherein: the support comprises a plurality of contact elements configured to contact a peripheral edge of the wafer-shaped article to grip the wafer-shaped article therebetween; and at least one of the plurality of contact elements is electrically connected to ground.

19. A method of liquid treatment of a wafer-shaped article, the method comprising: dispensing a liquid onto the wafer-shaped article; andapplying a voltage between a part in contact with the liquid before the liquid is dispensed onto the wafer-shaped article and a reference point.

20. The method according to claim 19, wherein the liquid is dispensed onto the wafer-shaped article using the liquid dispenser apparatus according to any of claims 1 to 15.21 . The method according to claim 19 or claim 20, wherein the method is performed using the apparatus for liquid treatment of a wafer-shaped article of any of claims 16 to 18.

22. The method according to any of claims 19 to 21 , wherein the method comprises setting the voltage applied between the part in contact with the liquid before the liquid is dispensed onto the wafershaped article and the reference point based on one or more target charge values of the wafer-shaped article at one or more respective radial positions of the wafer-shaped article after the liquid has been dispensed onto the wafer-shaped article.

23. The method according to any of claims 19 to 22, wherein the method comprises setting the voltage applied between the part in contact with the liquid before the liquid is dispensed onto the wafershaped article and the reference point based on a target radial charge distribution of the wafer-shaped article after the liquid has been dispensed onto the wafer-shaped article.

24. The method according to any of claims 19 to 23, wherein the method comprises setting a radial position of the wafer-shaped article at which the liquid is dispensed onto the wafer-shaped article based on one or more target charge values of the wafer-shaped article at one or more respective radial positions of the wafer-shaped article after the liquid has been dispensed onto the wafer-shaped article.

25. The method according to any of claims 19 to 24, wherein the method comprises setting a radial position of the wafer-shaped article at which the liquid is dispensed onto the wafer-shaped article based on a target radial charge distribution of the wafer-shaped article after the liquid has been dispensed onto the wafer-shaped article.

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