Support for use in a weighing device

Abstract

A support for use in a weighing device, the support comprising: a support part for supporting an object during a weight measurement; a mounting part for mounting the support on a weighing device; a thermal break provided between the support part and the mounting part; and an electrically conductive part or electrostatically dissipative part provided around at least part of the thermal break,

Description

[0001] SUPPORT FOR USE IN A WEIGHING DEVICE

[0002] Field of the Invention

[0003] The present invention relates to a support for use in a weighing device, and to a weighing device having such a support.

[0004] Background

[0005] Microelectronic devices are fabricated on semiconductor (e.g. silicon) wafers using a variety of techniques, e.g. including deposition techniques and removal techniques. Semiconductor wafers may be further treated in ways that alter their mass, e.g. by cleaning, ion implantation, lithography and the like.

[0006] Wafer treatment techniques typically cause a change in mass at or on the surface of the semiconductor wafer. The configuration of the changes to the surface are often vital to the functioning of the device, so it is desirable for quality control purposes to assess wafers during production in order to determine whether they have the correct configuration.

[0007] Specialist metrology tools may be used within a production flow so that monitoring is conducted soon after the relevant process of interest and usually before any subsequent processing, i.e. between processing steps.

[0008] Measuring the change in mass of a wafer either side of a processing step is an attractive method for implementing product wafer metrology. It is relatively low cost, high speed and can accommodate different wafer circuitry patterns automatically. In addition, it can often provide results of higher accuracy than alternative techniques. The wafer in question is weighed before and after the processing step of interest. The change in mass is correlated to the performance of the production equipment and / or the desired properties of the wafer.

[0009] The wafer is typically weighed using a weighing device having a pan for supporting the wafer during the measurement. In particular, the wafer is loaded onto the pan of the weighing device and then the wafer is weighed by the weighing device. For example, the weighing device may comprise a load cell and a pan coupled to the load cell. The load cell may measure the weight force of a wafer loaded onto the pan.

[0010] When the wafer is weighed by the weighing device, its temperature may be above an ambient temperature, for example a temperature of the weighing device. Therefore, heat may be conducted from the wafer to the pan, and from the pan to the load cell. This heat may affect the output of the weighing device. For example, a heat load on the load cell of the weighing device from one or more wafers may cause an error in an output of the load cell. This will reduce the accuracy of the weighing device.

[0011] Furthermore, electric charges (electrostatic charges) can exist on the surface (surface charge) of the wafer or within its body (substrate, embedded charge). Electric charges can be caused by a variety of means, e.g. earlier processing or fabrication steps, tribology, contact electrification, etc. When a charged wafer is present on the pan of a weighing device, and the charge on the wafer is not discharged, the charge may lead to an electrostatic force between the wafer and the surroundings. For example, there may be an electrostatic force between the wafer and the load cell of the weighing device, or between the wafer and a measurement enclosure surrounding the weighing device.

[0012] This electrostatic force may cause the weight force measured by the load cell to be erroneously high or low, depending on the direction of the electrostatic force, leading to an error in the weight measurement. For example, where the electrostatic force acts from the wafer towards the load cell, this force will be measured by the load cell together with the weight force of the wafer, and therefore the output of the load cell will not directly correspond to the weight force of the wafer since it will also include the electrostatic force.

[0013] It is therefore advantageous to allow a charged wafer present on the pan of the weighing device to discharge before performing a weight measurement, for example through the weighing device, to prevent such electrostatic forces from causing errors in the weight measurement.

[0014] A weighing pan for a weighing device is described in W02024008435 that allows at least partially controlled discharge of a charged wafer while limiting conduction of heat from the weighing pan to weighing device.

[0015] The weighing pan described in W02024008435 is illustrated schematically in FIG. 1. As shown in FIG. 1 , the weighing pan 1 comprises a pan part 3 for supporting a wafer during a weight measurement. The pan part 3 is configured to contact an underside of a wafer W to support the wafer W.

[0016] The pan part 3 comprises a plurality of pins 4 that protrude from a top surface of the pan part 3 perpendicular to a main plane of the pan part 3. The pins 4 are configured to contact an underside of the wafer W so as to support the wafer W. The pan part 3 and pins 4 are electrically conductive.

[0017] The weighing pan 1 further comprises a leg 5 that extends perpendicularly to the pan part 3. The leg 5 is configured to be received by a weighing device so as to mount the weighing pan 1 on the weighing device.

[0018] The weighing pan 1 further comprises an electrical and thermal insulator part 7 positioned between the pan part 3 and the leg 5. The pan part 3 and the leg 5 are physically separated by the electrical and thermal insulator part 7. Furthermore, the pan part 3 and the leg 5 are electrically and thermally insulated from each other by the electrical and thermal insulator part 7.

[0019] The electrical and thermal insulator part 7 prevents heat from a wafer W on the weighing pan 1 from being conducted to a load cell of the weighing device through the weighing pan 1 , where it may cause an error in the output of the load cell.

[0020] However, as mentioned above, electric charges trapped on a wafer W on the weighing pan 1 can also cause inaccurate measurements by the load cell, due to electrostatic forces between the wafer W and the surroundings. Therefore, to enable discharge of electric charge on the wafer W through the weighing pan 1 to the load cell, the weighing pan 1 comprises a metal spring 9 that electrically connects the pan part 3 to the leg 5. The metal spring 9 is located inside the electrical and thermal insulator part 7 and extends across (i.e. spans) the electrical and thermal insulator part 7.

[0021] The spring 9 is an electrical conductor that allows discharge of electric charge from the pan part 3 to the leg 5, where it can be discharged to the load cell. Therefore, electric charge can be discharged from the wafer W through the weighing pan 1. Typically, the metal spring 9 is a helical spring. Since the spring 9 has a small cross-sectional area, thermal transfer between the pan part 3 and the leg 5 through the spring 9 is low. Therefore, the pan part 3 can be substantially thermally isolated from the leg 5 while still allowing discharge of electric charge on the wafer W from the pan part 3 to the leg 5.

[0022] The load cell is typically electrically connected to earth or ground, such that electric charges discharged to the load cell from the wafer W are discharged to earth or ground.

[0023] The leg part 5 is made of an electrically conductive material, such as stainless steel, so that electric charge can be conducted through the leg part 5 to the load cell.

[0024] The present inventors have realised that, while the above-described arrangement is suitable for many applications, a possible problem can occur whereby electrostatic charges can occur on or in the electrical and thermal insulator part 7. Such electrostatic charges on the thermal insulator part 7 may occur due to handling of the thermal insulator part 7, for example. Such electrostatic charges can cause electrostatic forces between the electrical and thermal insulator part 7 and a weighing device on which the weighing pan 1 is mounted. As discussed above, such electrostatic forces can cause errors in a weight force measured by a load cell of the weighing device.

[0025] The present invention has been devised in light of the above considerations.

[0026] Summary of the Invention

[0027] The present inventors have realised that such electrostatic charges occurring on or in such an electrical and thermal insulator part can be prevented from causing such electrostatic forces, or the effects of such electrostatic forces can be reduced, by shielding or preventing at least some of the charges using electrically conductive material or electrically dissipative material.

[0028] In particular, an electrically conductive part or electrically dissipative part can be provided around at least part of the electrical and thermal insulator part so as to shield or prevent at least some of the charges on or in the electrical and thermal insulator part.

[0029] According to a first aspect of the present invention there is provided a support for use in a weighing device, the support comprising: a support part for supporting an object during a weight measurement; a mounting part for mounting the support on a weighing device; a thermal break provided between the support part and the mounting part; and an electrically conductive part or electrostatically dissipative part provided around at least part of the thermal break. Therefore, in the present invention an electrically conductive part or electrostatically dissipative part is provided around at least part of the thermal break. The electrically conductive part or electrostatically dissipative part can shield or prevent at least some of the charges occurring on or in the thermal break and can therefore prevent or reduce the effect of electrostatic forces caused by such charges.

[0030] The first aspect of the present invention may have any one, or, where compatible, any combination of the following optional features.

[0031] The support may be a pan. The term support may therefore be replaced with the term pan throughout, unless incompatible.

[0032] The pan may be a weighing pan or a balance pan.

[0033] The support part may be a pan part. The term support part may therefore be replaced with the term pan part throughout, unless incompatible.

[0034] The pan part may be a weighing pan part or a balance pan part.

[0035] A weighing device may mean a device for performing a weight measurement on an object.

[0036] A weighing device may mean a device for generating measurement output indicative of the weight of an object.

[0037] A weighing device may mean a device for weighing an object, and / or measuring the weight of an object.

[0038] The support part may be for supporting the object during a weight measurement performed on the object by the weighing device.

[0039] The support part may be configured to support the object during a weight measurement.

[0040] The object may be a wafer, such as a semiconductor wafer.

[0041] The support part may therefore be configured to support a wafer during a weight measurement.

[0042] Supporting an object may mean supporting the weight of the object.

[0043] The support part may comprise a plurality of arms, for example a plurality of horizontal arms that extend radially outwards from a central hub of the support part. For example, there may be three such arms, which may be separated by an angle of 120 degrees between adjacent arms.

[0044] The support part may comprise a plurality of contact elements for contacting the underside of the object supported by the support part. For example, the support part may comprise one or more protrusions, for example one or more bumps or one or more pins, that extend upwards from an upper surface of the support part so as to contact an underside of the object.

[0045] The support part may be referred to as a tripod.

[0046] The support part may comprise, or be made of, a conductive material, for example stainless steel.

[0047] The support part may be covered by a coating, for example a titanium nitride (TiN) coating. The mounting part may be configured to be received by a weighing device to mount the support on the weighing device.

[0048] The mounting part may be a leg or pin or shaft, for example.

[0049] The mounting part may extend perpendicularly, or substantially perpendicularly, to the support part.

[0050] The mounting part may be tapered.

[0051] The mounting part may be a protrusion or protruding part.

[0052] The mounting part may be configured to interface with the weighing device. The mounting part may therefore be referred to as a weighing device interface part.

[0053] The mounting part may be configured to interface with a load cell of the weighing device. The mounting part may therefore be referred to as a loadcell interface part.

[0054] The mounting part may be a loadcell interface pin.

[0055] When an object is loaded on the support part of the support, the weight force may be transmitted to the weighing device through the mounting part.

[0056] The mounting part may be located, or substantially located, on a central longitudinal axis of the support.

[0057] The mounting part may extend along, or substantially along, a central longitudinal axis of the support.

[0058] The mounting part is below the support part when the support is mounted on the weighing device.

[0059] Mounting the support on the weighing device may comprise the support being positioned or located on the weighing device, and / or the support being received by the weighing device (for example the mounting part being received by the weighing device).

[0060] The mounting part may comprise, or be made of, a conductive material such as stainless steel, for example.

[0061] The support is typically located on top of the weighing device, and / or above the weighing device.

[0062] The weighing device may comprise a load cell.

[0063] The load cell may be grounded or earthed (electrically connected to ground or earth).

[0064] The weighing device may comprise a weight force transducer.

[0065] The weighing device may comprise or be an electronic balance.

[0066] The thermal break reduces or prevents conduction of heat or thermal energy between the support part and the mounting part.

[0067] The thermal break has a low thermal conductivity.

[0068] The thermal break may comprise, or be made of, a material with a low thermal conductivity. For example, the thermal break may comprise, or be made of, a material having a thermal conductivity of less than or equal to 1 W / Km. In addition, or alternatively, the thermal break may be shaped and / or sized and / or otherwise configured to control and / or reduce the thermal conductivity of the thermal break. For example, the thermal break may have a length in a direction perpendicular to a plane of the support part that is greater than a width of the thermal break in a direction parallel to the plane of the support part. The length of the thermal break may be greater than or equal to 1.5, or 2, or 2.5 or 3 times the width of the thermal break, for example.

[0069] The thermal break may be elongate in a direction perpendicular to a plane of the support part.

[0070] The thermal break may comprise one or more air gaps that reduce a thermal conductivity of the thermal break.

[0071] The thermal break may comprise a thermally insulating material.

[0072] The thermal break may alternatively be referred to as a thermal barrier or thermal isolation.

[0073] The thermal break may comprise a block, or layer, or plate, or sheet, or piece or part of thermally insulating material.

[0074] The thermal break may be arranged so that conductive heat transfer from the support part to the mounting part is only possible, or substantially only possible, via the thermal break.

[0075] The thermal break thermally isolate or separate the mounting part from the support part.

[0076] The thermal break may comprise, or be made of, plastic.

[0077] The thermal break may comprise, or be made of, an electrostatically dissipative material.

[0078] The thermal break may comprise, or be made of, an electrostatic dissipative (ESD) plastic.

[0079] For example, the thermal break may comprise, or be made of, Vespel SP202 0.35 W / Km, Ketron CA30 0.92 W / Km, or PEEK ELS 0.46 W / Km.

[0080] The plastic may be electrically conductive PEEK (polyether ether ketone), for example.

[0081] The thermal break may be in contact with the mounting part, for example a top end of the mounting part.

[0082] The thermal break may be provided around at least part of the mounting part. For example, the thermal break may be provided around at least a top end of the mounting part, for example around a circumferential surface or side surface of the top end of the mounting part.

[0083] The thermal break may surround at least part of the mounting part. For example, the thermal break may surround a circumferential surface or side surface of at least part of the mounting part.

[0084] The electrically conductive part or electrostatically dissipative part may comprise, or be made of, an electrically conductive material, for example stainless steel, or an electrostatically dissipative material.

[0085] The electrically conductive part or electrostatically dissipative part may be provided in the form of a block or body of material, a layer, or a coating, for example. For example, the coating may comprise one or more of an aluminium coating or a nickel coating. The coating may have a thickness of greater than or equal to 0.5pm and less than or equal to 100pm, for example. However, the electrically conductive or electrostatically dissipative part does not need to have a continuous surface. For example, the electrically conductive or electrostatically dissipative part may instead be in the form of a mesh or grid for example.

[0086] For example, the coating may comprise one or more of titanium nitride or a carbon based coating such as diamond like carbon or amorphous carbon.

[0087] The electrically conductive part or electrostatically dissipative part may be provided around at least part of a circumferential or lateral or side surface of the thermal break.

[0088] The electrically conductive part or electrostatically dissipative part may surround, for example laterally surround, at least part of the thermal break.

[0089] The electrically conductive part or electrostatically dissipative part may surround at least part of a circumferential or lateral or side surface of the thermal break.

[0090] The electrically conductive part or electrostatically dissipative part may be provided over at least part of a top surface of the thermal break.

[0091] Typically, the support part and the mounting part, or at least part of the support part and at least part of the mounting part, are electrical conductors. For example, (at least part of) the support part and / or the mounting part may be made of an electrically conductive material, such as stainless steel.

[0092] The support may comprise an electrically conductive path between the support part and the mounting part. There is therefore electrical continuity between the support part and the mounting part.

[0093] The electrically conductive path may extend through at least part of the thermal break or around at least part of an outside of the thermal break. For example, the electrically conductive path may be arranged inside of at least part of the thermal break, or outside of at least part of the thermal break. The support part and the mounting part may therefore be electrically connected via an electrically conductive path that extends though or around at least part of the thermal break.

[0094] Where the electrically conductive path is arranged around at least part of an outside of the thermal break, the electrically conductive path may be in contact with the outside of the thermal break, or may not be in contact with the outside of the thermal break.

[0095] The electrically conductive path may comprise an electrically conductive element that extends through at least part of the thermal break or around at least part of an outside of the thermal break.

[0096] The electrically conductive element may be an electrically conductive spring, for example.

[0097] The electrically conductive element is made of, or comprises, an electrically conductive material, for example stainless steel.

[0098] The electrically conductive part or electrostatically dissipative part may laterally surround at least part of the thermal break.

[0099] The electrically conductive part or electrostatically dissipative part may extend over at least part of a top end of the thermal break. The thermal break may be enclosed, or substantially enclosed, by the electrically conductive part or electrostatically dissipative part and the mounting part.

[0100] The electrically conductive part or electrostatically dissipative part may comprise a body having a hole in which at least part of the thermal break is received. Therefore, at least part of the thermal break may be surrounded by the body by the at least part of the thermal break being received in the hole in the body.

[0101] The body may comprise a block or piece of electrically conductive material or electrically dissipative material.

[0102] The hole may be on a bottom surface of the electrically conductive part or electrostatically dissipative part. The mounting part may therefore protrude from the bottom surface of the electrically conductive part or electrostatically dissipative part.

[0103] The hole may be a through-hole that extends from a top surface of the body to a bottom surface of the body, and at least part of the thermal break may be received in a bottom portion of the through-hole. The through-hole may be a longitudinal through-hole. The through-hole may form a longitudinal channel or passageway through the body.

[0104] The support part may be attached to the body by a connector that extends into a top portion of the through-hole. The connector may be a screw, and there may be a corresponding screw thread provided on an inside of at least an upper portion of the through-hole.

[0105] The connector may comprise, or be made of, titanium, for example.

[0106] In an alternative arrangement the support part and the body may be integral and / or formed as a single piece, in which case the connector is not required. For example, they may be molded or cast or machined at the same time as a single piece

[0107] The support may comprise an electrically conductive path between the support part and the mounting part that extends through at least part of the thermal break; and the electrically conductive path may comprise an electrically conductive element that is in contact with the connector at a first end of the electrically conductive element, extends through at least part of the thermal break, and is in contact with the mounting part at a second end of the electrically conductive element. The electrically conductive element may have any of the features of the electrically conductive element described above.

[0108] In an alternative arrangement, the electrically conductive path may instead be arranged around at least part of an outside of the thermal break.

[0109] Part of the thermal break may protrude from the hole. The protruding part of the thermal break may form a protruding lip, rim or edge, for example.

[0110] The thermal break may comprise a through-hole, and part of the mounting part may be received in a bottom portion of the through-hole. The part of the mounting part may therefore be surrounded by the thermal break. The electrically conductive element may extend along a top portion of the through-hole of the thermal break to contact the part of the mounting part that is received in the bottom portion of the through-hole of the thermal break. The electrically conductive element and the mounting part may therefore be in contact with each other in the through-hole of the thermal break.

[0111] The thermal break may be in contact with the mounting part. In particular the thermal break may be in contact with the top part of the mounting part.

[0112] The support may further comprise an anti-rotation pin for being received in a corresponding recess of the weighing device.

[0113] The anti-rotation pin may extend perpendicularly to a plan of the support part.

[0114] The anti-rotation pin may be laterally offset relative to the mounting part.

[0115] The anti-rotation pin may be electrically conductive. The anti-rotation pin may comprise, or be made of, an electrically conductive material, for example stainless steel.

[0116] The support may further comprise a further thermal break provided between the support part and the antirotation pin.

[0117] The further thermal break may have any of the features of the thermal break described above, unless incompatible.

[0118] The electrically conductive part or electrostatically dissipative part may be further provided around at least part of the further thermal break. In other words, the same electrically conductive part or electrostatically dissipative part may be provided both around at least part of the thermal break and around at least part of the further thermal break.

[0119] Of course, in other embodiments a separate or different electrically conductive part or electrostatically dissipative part may be provided around the further thermal break.

[0120] The electrically conductive part or electrostatically dissipative part may laterally surround at least part of the further thermal break.

[0121] The electrically conductive part or electrostatically dissipative part may be provided over at least part of a top end of the further thermal break.

[0122] At least part of a bottom end of the further thermal break may be covered by the anti-rotation pin.

[0123] The thermal break may be enclosed, or substantially enclosed, by the electrically conductive part or electrostatically dissipative part and the anti-rotation pin.

[0124] The electrically conductive part or electrostatically dissipative part may comprise a body having a hole in which at least part of the further thermal break is received.

[0125] The hole may be on a bottom surface of the electrically conductive part or electrostatically dissipative part. The anti-rotation pin may therefore protrude from the bottom surface of the electrically conductive part or electrostatically dissipative part. Part of the further thermal break may protrude from the hole.

[0126] The further thermal break may comprise a hole, and part of the anti-rotation pin may be received in the hole.

[0127] The further thermal break may be in contact with the anti-rotation pin.

[0128] The support may be a balance pan.

[0129] The mounting part may be a loadcell interface pin.

[0130] In an embodiment the electrically conductive part or electrostatically dissipative part provided around at least part of the thermal break may comprise an electrically conductive spring. Such an electrically conductive spring provided around at least part of the thermal break may provide at least some shielding of electrostatic charges on the at least part of the thermal break.

[0131] The electrically conductive spring may directly or indirectly electrically connect the support part to the mounting part.

[0132] The electrically conductive spring may extend from the support part to the mounting part.

[0133] The thermal break may comprise a shaft provided between the support part and the mounting part, and the electrically conductive spring may be arranged around an outside of the shaft.

[0134] The present inventors have further realised that one or more of the problems identified above may alternatively be overcome by using a mounting part that is made of, or at least in part made of, a material that is both a thermal insulator and an electrical conductor. In this case, the mounting part will prevent heat / thermal energy from being transferred from the support part to the weighing device, and will allow discharge of charges from the support part to the weighing device. Furthermore, since the mounting part (or the at least part of the mounting part) is electrically conductive, electrostatic charges will not build-up on the mounting part.

[0135] Therefore, according to a second aspect of the present invention there is provided a support for use in a weighing device, the support comprising: a support part for supporting an object during a weight measurement; and a mounting part for mounting the support on a weighing device; wherein the mounting part, or at least part of the mounting part, is both a thermal insulator and an electrical conductor.

[0136] The support according to the second aspect of the present invention may have any of the features of the support according to the first aspect of the present invention, unless incompatible. In particular, the support part and / or the mounting part in the second aspect of the present invention may have any of the features of the support part and / or the mounting part in the first aspect of the present invention, unless incompatible.

[0137] For example, the support part, or at least part of the support part, may be an electrical conductor and may comprise, or be made of, an electrically conductive material, for example stainless steel.

[0138] The support part and the mounting part may be formed as a single piece, for example moulded at the same time from conductive plastic. The mounting part, or at least part of the mounting part, may be made of a material that is both a thermal insulator and an electrical conductor.

[0139] The mounting part, or at least part of the mounting part, may have a thermal conductivity of less than or equal to 1 W / Km and / or an electrical resistance of less than or equal to 1 MOhm.

[0140] The mounting part, or at least part of the mounting part, may be made of conductive plastic or conductive ceramic.

[0141] The mounting part may be shaped and / or sized and / or otherwise configured to control and / or reduce the thermal conductivity of the mounting part. For example, the mounting part may have a length in a direction perpendicular to a plane of the support part that is greater than a width of the mounting part in a direction parallel to the plane of the support part. The length of the mounting part may be greater than or equal to 1.5, or 2, or 2.5 or 3 times the width of the mounting part, for example.

[0142] The mounting part may be elongate in a direction perpendicular to a plane of the support part.

[0143] The mounting part may comprise one or more air gaps that reduce a thermal conductivity of the mounting part.

[0144] The present inventors have further realised that one or more of the problems identified above may alternatively be overcome by using a support part that is made of, or at least in part made of, a material that is both a thermal insulator and an electrical conductor. In this case, the support part will prevent heat / thermal energy from being transferred from the support part to the weighing device, and will allow discharge of charges from the support part to the mounting part. Furthermore, since the support part (or the at least part of the support part) is electrically conductive, electrostatic charges will not build-up on the support part.

[0145] Therefore, according to a third aspect of the present invention there is provided a support for use in a weighing device, the support comprising: a support part for supporting an object during a weight measurement; and a mounting part for mounting the support on a weighing device; wherein the support part, or at least part of the support part, is a thermal insulator and an electrical conductor.

[0146] The support according to the third aspect of the present invention may have any of the features of the support according to the first or second aspects of the present invention, unless incompatible. In particular, the support part and / or the mounting part in the third aspect of the present invention may have any of the features of the support part and / or the mounting part in the first or second aspects of the present invention, unless incompatible.

[0147] For example, the mounting part, or at least part of the mounting part, may be an electrical conductor and may comprise, or be made of, an electrically conductive material, for example stainless steel.

[0148] The support part, or the at least part of the support part, may have a thermal conductivity of less than or equal to 1 W / Km and / or an electrical resistance of less than or equal to 1 MOhm.

[0149] The support part, or the at least part of the support part, may be made of a material that is both a thermal insulator and an electrical conductor. The support part, or the at least part of the support part, may be made of conductive plastic or conductive ceramic.

[0150] The present inventors have further realised that one or more of the problems identified above may alternatively be overcome by providing a thermal break between the support part and the mounting part that is also electrically conductive. In this case, electrostatic charges may not occur in the thermal break and it may not be necessary to provide the electrically conductive part or electrostatically dissipative part provided around at least part of the thermal break as described above.

[0151] Therefore, according to a fourth aspect of the present invention there is provided a support for use in a weighing device, the support comprising: a support part for supporting an object during a weight measurement; a mounting part for mounting the support on a weighing device; and a thermal break provided between the support part and the mounting part, wherein the thermal break is electrically conductive.

[0152] The support according to the fourth aspect of the present invention may comprise any of the features of the support according to the first, second or third aspects of the present invention, unless incompatible.

[0153] The thermal break may comprise, or be made of, a material that is both thermally insulating and electrically conductive, for example any of the materials discussed above in relation to the second aspect of the present invention.

[0154] The support part and mounting part may have any of the features of the support part and the mounting part of the first or second aspect of the present invention.

[0155] According to a fifth aspect of the present invention there is provided a weighing device having the support according to the first, second, third or fourth aspect of the present invention.

[0156] The weighing device may further comprise a load cell, and the support may be connected to, or coupled to, or mounted on, the load cell.

[0157] The invention includes the combination of the aspects and preferred features described except where such a combination is clearly impermissible or expressly avoided.

[0158] Summary of the Figures

[0159] Embodiments illustrating the principles of the invention will now be discussed with reference to the accompanying figures in which:

[0160] Figure 1 is a schematic illustration of a weighing pan previously used by the inventors.

[0161] Figure 2 is a schematic illustration of a weighing pan according to a first embodiment of the present invention. Figure 3 is a schematic illustration of the weighing pan according to the first embodiment of the present invention.

[0162] Figure 4 is a schematic illustration of the weighing pan according to the first embodiment of the present invention coupled to a weighing device.

[0163] Figure 5 is a schematic exploded illustration of the weighing pan according to the first embodiment of the present invention.

[0164] Figure 6 is a schematic exploded illustration of the weighing pan according to the first embodiment of the present invention.

[0165] Figure 7 is a schematic sectional illustration of the weighing pan according to the first embodiment of the present invention.

[0166] Figure 8 is a schematic section illustration of the spacer of the weighing pan according to the first embodiment of the present invention.

[0167] Figure 9 is a schematic sectional illustration of the weighing pan according to the first embodiment of the present invention.

[0168] Figure 10 is a schematic sectional illustration of a weighing pan according to a second embodiment of the present invention.

[0169] Figure 11 is a schematic illustration of a weighing pan according to a third embodiment of the present invention.

[0170] Figure 12 is a schematic illustration of a weighing pan according to a fourth embodiment of the present invention. Detailed Description of the Invention

[0171] 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.

[0172] FIG. 2 is a schematic illustration of a weighing pan 11 (a support) according to a first embodiment of the present invention.

[0173] As illustrated in FIG. 2, the weighing pan 11 comprises a pan part 13 (a support part) for supporting a wafer during a weight measurement.

[0174] The weighing pan 11 may be referred to as a weighing pan assembly, for example. Alternatively, the weighing pan 11 may be referred to as a balance pan or balance pan assembly.

[0175] The pan part 13 is configured to contact an underside of the wafer to support the wafer.

[0176] The pan part 13 may be referred to as a tripod, for example.

[0177] In this embodiment, the pan part 13 comprises three horizontal arms 15 that each extend radially outwards from a central hub 17. The horizontal arms 15 are evenly distributed around the central hub 17 with an angle of 120 degrees between adjacent horizontal arms 15. Of course, in other embodiments the pan part 13 may have a different shape and / or configuration. For example, the pan part 13 may have a different number of arms, or the pan part 13 may not have any arms and may instead have a disc shape or circular shape.

[0178] Each of the horizontal arms 15 comprises a protrusion 19 that protrudes upwards from an upper surface of the horizontal arm 15. The protrusions 19 are arranged at distal ends of the horizontal arms 15 and are configured to contact the underside of a wafer when the wafer is loaded onto the weighing pan 11 , so as to support the wafer. Therefore, when a wafer is loaded onto the weighing pan 11 , the wafer is supported from beneath by the protrusions 19 on the horizontal arms 15.

[0179] In this embodiment, the protrusions 19 are bumps, or mounds, or hemispheres, provided on the upper surface of each of the horizontal arms. Furthermore, the protrusions 19 are integrally formed with the pan part 13. However, in other embodiments other types of protrusion could be used instead of the protrusions 19, for example pins or balls such as silicon carbide (SiC) balls. In some embodiments, the protrusions 19 may be omitted altogether such that the wafer is directly supported by the upper surface of the pan part 13.

[0180] The pan part 13 is electrically conductive. The pan part 13 comprises or is made of an electrically conductive material. For example, the pan part 13 may comprise or be made of stainless steel. Of course, other materials are also possible.

[0181] The pan part 13 may be coated in titanium nitride (TiN), for example to prevent or reduce the transfer of contaminants to wafers supported by the pan part 13. As illustrated in FIG. 2, for example, the pan part 13 is positioned on a spacer 21. The spacer 21 extends perpendicularly to a bottom surface of the pan part 13. The spacer 21 therefore forms a shaft or post of the weighing pan 11.

[0182] At least part of the spacer 21 is arranged along a central longitudinal axis of the pan part 13 that extends through the central hub 17 of the pan part 13.

[0183] The spacer 21 is electrically conductive. The spacer 21 is made of an electrically conductive material. For example, the spacer 21 may comprise or be made of stainless steel. Of course, other materials are also possible.

[0184] The structure of the spacer 21 is described in more detail below.

[0185] As illustrated in FIGS. 2 and 3, a loadcell interface pin 23 extends from a lower or bottom surface of the spacer 21. The loadcell interface pin 23 is adapted for mounting the weighing pan 11 on a load cell. For example, the loadcell interface pin 23 may be configured to be received in a recess of the load cell so as to mount the weighing pan 11 on the load cell. The loadcell interface pin 23 may have a corresponding outer shape to an inner shape of the recess of the load cell. The loadcell interface pin therefore interfaces with the load cell.

[0186] The loadcell interface pin 23 may correspond to, or comprise, a rod or shaft, for example.

[0187] The loadcell interface pin 23 is electrically conductive. The loadcell interface pin 23 comprises or is made of an electrically conductive material. For example, the loadcell interface pin 23 may comprise or be made of stainless steel. As discussed below, a conductive path is provided through the spacer 21 from the pan part 13 to the loadcell interface pin 23, such that electric charges (electrostatic charges) on a wafer loaded onto the pan part 13 can be discharged to the load cell via the loadcell interface pin 23.

[0188] The loadcell interface pin 23 is arranged along a central longitudinal axis of the pan part 13 that extends through the central hub 17 of the pan part 13.

[0189] Therefore, when a wafer is positioned centrally on the pan part 13, the weight force of the wafer will act along the central longitudinal axis of the pan part 13 through the loadcell interface pin 23 to the load cell.

[0190] As illustrated in FIGS. 2 and 3, an anti-rotation pin 25 also extends from the lower or bottom surface of the spacer 21 . The anti-rotation pin 25 is arranged to be positioned in a corresponding recess of the load cell, so as to prevent rotation of the weighing pan 11 around the loadcell interface pin 23 when the weighing pan 11 is mounted on the load cell. The anti-rotation pin 25 may have a corresponding outer shape to an inner shape of the recess of the load cell. The anti-rotation pin 25 may correspond to a rod or shaft, for example. The anti-rotation pin 25 may be cylindrical.

[0191] The anti-rotation pin 25 is spaced apart from the longitudinal axis of the pan part 13 that extends through the central hub 17 of the pan part 13. The anti-rotation pin 25 may therefore be referred to as being off- centre relative to the pan part 13. The anti-rotation pin 25 is also laterally spaced apart from the loadcell interface pin 23. FIG. 4 illustrates the weighing pan 11 mounted on a mounting part 27 of a load cell 29. In particular, the mounting part 27 comprises a first recess for receiving the loadcell interface pin 23 and a second recess for receiving the anti-rotation pin 25.

[0192] The first recess is located on a central longitudinal axis of the mounting part 27, which is a longitudinal axis or measuring axis of the load cell 29. The second recess is spaced apart from the longitudinal axis.

[0193] The mounting part 27 is coupled to a force sensing element of the load cell 29 that is configured to measure a weight force acting on the mounting part 27 from an object loaded on the mounting part 27.

[0194] The mounting part 27 of the load cell 29 is therefore configured so that the load cell 29 measures the weight of an object loaded on the mounting part 27. Therefore, when a wafer is loaded onto the weighing pan 11 , the weight of the wafer will be measured by the load cell 29.

[0195] As illustrated in FIG. 4, the loadcell interface pin 23 is configured such that when the weighing pan 11 is mounted on the load cell 29 there is a gap between the lower or bottom surface of the spacer 21 and an upper or top surface of the mounting part 27 of the load cell.

[0196] FIGS. 5 and 6 are exploded views of the weighing pan 11. As shown in FIGS. 5 and 6, the pan part 13 is secured to the spacer 21 via a fixing screw 31 that passes through the central hub 17 of the pan part 13 into a first opening 33 formed on an upper or top surface of the spacer 21. As discussed below, the first opening 33 is an opening of a first longitudinal channel or passageway or hole formed in the spacer 21 that extends through the spacer 21 from a top or upper surface of the spacer 21 to a lower or bottom surface of the spacer 21. The first opening 33 is internally threaded such that the fixing screw 31 can be screwed into the first opening 33 to secure the pan part 13 to the spacer 21.

[0197] In this embodiment the fixing screw 31 is made of titanium, but of course other materials can be used instead such as stainless steel.

[0198] Furthermore, as shown in FIG. 5, the pan part 13 is further connected to the spacer 21 via a grub screw 35 that is connected to a bottom surface of the pan part 13 and that is received in a second opening 37 formed on the upper or top surface of the spacer 21. As discussed below, the second opening 37 is an opening of a second longitudinal channel or passageway or hole formed in the spacer 21 that extends through the spacer 21 from the top or upper surface of the spacer 21 to the lower or bottom surface of the spacer 21. The second opening 37 is internally threaded such that the grub screw 35 can be screwed into the second opening 37 to connect the pan part 13 to the spacer 21.

[0199] The grub screw 35 connection between the pan part 13 and the spacer 21 may facilitate correct alignment between the pan part 13 and the spacer 21 when the pan part 13 and the spacer 21 are connected together. In particular, it is only possible to connect both the grub screw 35 and the fixing screw 31 to the spacer 21 when the pan part 13 is in a specific orientation relative to the spacer 21.

[0200] However, in other embodiments, the grub screw 35 connection may be omitted.

[0201] Of course, in other embodiments the pan part 13 and the spacer 21 may be integral components formed as a single piece. As illustrated in FIGS. 5 and 6, the weighing pan 11 further comprises a first thermal break 39 and a second thermal break 41.

[0202] As described below, the first thermal break 39 substantially thermally insulates the loadcell interface pin 23 from the remainder of the weighing pan 11. Similarly, the second thermal break 41 substantially thermally insulates the anti-rotation pin 25 from the remainder of the weighing pan 11. Therefore, conduction of heat from the weighing pan 11 to the load cell on which the weighing pan 11 is mounted is significantly reduced by the first and second thermal breaks 39 and 41 , as described below.

[0203] As already discussed above in relation to FIG. 4, a gap is formed between the lower or bottom surface of the spacer 21 and an upper or top surface of the mounting part 27 of the load cell 29 when the weighing pan 11 is mounted on the load cell 29, such that there is no direct conduction of heat between the spacer 21 and the load cell 29. Instead, conduction would only be possible via the load cell interface pin 23 and the anti-rotation pin 25.

[0204] The first and second thermal breaks 39 and 41 are thermal insulators. The first and second thermal breaks 39 and 41 are made of thermally insulating material. For example, the first and second thermal breaks 39 and 41 may comprise or be made of plastic. The plastic may be an electrostatic dissipative (ESD) plastic, which is a type of plastic designed to reduce static electricity. The plastic may be electrically conductive PEEK (polyether ether ketone), for example. The arrangement of the first and second thermal breaks 39 and 41 is described below.

[0205] Of course, other materials can be used for the first and second thermal breaks 39 and 41 , for example a ceramic material.

[0206] In general, the first and second thermal breaks 39 and 41 may each comprise or be a piece or block or sheet or part of thermally insulating material.

[0207] As illustrated in FIGS. 5 and 6, the weighing pan further comprises a spring 43. The spring 43 is electrically conductive. The spring 43 is made of an electrically conductive material, such as stainless steel. As discussed below, the spring 43 provides an electrical connection between the pan part 13 and the loadcell interface pin 23 through the first thermal break 39.

[0208] Of course, in embodiments where the first thermal break 39 is made of an electrically conductive material, the spring 43 may be omitted.

[0209] The specific arrangement of these components is illustrated in FIG. 7. Furthermore, the configuration of the spacer 21 is illustrated in FIG. 8 with the other components removed for clarity.

[0210] As illustrated in FIG. 8, the spacer 21 comprises a body 44 having a first longitudinal channel or passageway or hole 45 formed in the body 44. The first longitudinal channel or passageway or hole 45 extends from an upper or top surface 47 of the spacer 21 to a lower or bottom surface 49 of the spacer 21. The first longitudinal channel or passageway or hole 45 is therefore a through-hole or through- channel. A width or diameter of the first longitudinal channel or passageway or hole 45 changes along the length of the first longitudinal channel or passageway or hole 45 as illustrated in FIG. 8. As discussed above, the fixing screw 31 that passes through the central hub 17 of the pan part 13 is received in the first opening 33, which is an opening of the first longitudinal channel or passageway or hole 45 at the upper or top surface 47 of the spacer 21. The first opening 33 is threaded, such that the fixing screw 31 can be screwed into the first opening 33.

[0211] Furthermore, as illustrated in FIG. 7, the first thermal break 39 is positioned in a lower or bottom portion of the first longitudinal channel or passageway or hole 45 in the spacer 21. In particular, the first thermal break 39 is press-fit into the lower or bottom portion of the first longitudinal channel or passageway or hole 45 through an opening of the first longitudinal channel or passageway or hole 45 at the lower or bottom surface 49 of the spacer 21.

[0212] The first thermal break 39 has a central longitudinal channel or passageway or hole that extends along the length of the first thermal break 39 from a top side of the first thermal break 39 to a bottom side of the first thermal break 39. The longitudinal channel or passageway or hole is therefore a through-hole or a through-channel. The first thermal break 38 may therefore be substantially cylindrical, or ring-shaped, for example.

[0213] As illustrated in FIG. 7, a first end of the loadcell interface pin 23 is received in the longitudinal channel or passageway or hole of the first thermal break 39. In particular, the first end of the loadcell interface pin 23 is press-fit into the longitudinal channel or passageway or hole of the first thermal break 39. The first end of the loadcell interface pin 23 is also located inside the first longitudinal channel or passageway or hole 45 in the spacer 21 , as illustrated in FIG. 7.

[0214] As illustrated in FIG. 7, the first thermal break 39 surrounds a circumferential surface or side surface of the first end of the loadcell interface pin 23. The first thermal break 39 also extends over at least part of the first end of the loadcell interface pin 23. The first thermal break 39 is arranged so that there is no direct contact between the first end of the loadcell interface pin 23 and the spacer 21. The first thermal break 39 therefore thermally insulates the first end of the loadcell interface pin 23, and therefore the loadcell interface pin 23 as a whole, from the spacer 21.

[0215] As illustrated in FIG. 7, substantially the whole of the first thermal break 39 is received in the lower or bottom portion of the first longitudinal channel or passageway or hole 45 in the spacer 21. In particular, only a small part of the first thermal break 39 protrudes beyond the lower or bottom surface 49 of the spacer 21 to form a protruding lip or rim or wall 51 around the opening of the first longitudinal channel or passageway or hole 45 in the lower or bottom surface 49 of the spacer 21. The protruding lip or rim or wall 51 helps to prevent any contact between the loadcell interface pin 23 and the bottom surface 49 of the spacer 21. Of course, in other embodiments the protruding lip or rim or wall 51 may be omitted.

[0216] Therefore, substantially a whole circumferential surface or side surface of the first thermal break 39 is surrounded by the spacer 21. Furthermore, the spacer 21 also extends over at least part of a top end of the first thermal break 39. Since the spacer 21 is electrically conductive, the spacer 21 may shield any electric charges (electrostatic charges) on or in the first thermal break 39 from around the circumference or side surface of the first thermal break 39, and at least partly from above the first thermal break 39. This may prevent such electric charges from causing electrostatic forces between the first thermal break 39 and other components such as a load cell on which the weighing pan 11 is mounted.

[0217] In particular, the spacer 21 forms a conductive shield around substantially the whole circumferential surface or side surface of the first thermal break 39 and at least partly above the first thermal break 39.

[0218] In particular, in the weighing pan 11 of the present embodiment, a circumferential surface or side surface of the first thermal break 39 is shielded by the spacer 21 that surrounds the first thermal break 39, and a top surface of the first thermal break 39 is at least partly shielded by the spacer 21 , therefore reducing the effects of any electrostatic charges formed on or in the first thermal break 39.

[0219] The first thermal break 39 is provided at a bottom portion of the spacer 21 and surrounds the first end of the loadcell interface pin 23. The first thermal break 39 is therefore immediately adjacent to the loadcell interface pin 23. This may minimise transfer of heat to the loadcell interface pin 23 by one or more portions of the weighing pan 11 being heated by air that has been heated by the wafer, for example.

[0220] As illustrated in FIG. 7, the spring 43 is positioned in the first longitudinal channel or passageway or hole 45 in the spacer 21 between the loadcell interface pin 23 and the fixing screw 31. In particular, a first end of the spring 43 contacts a bottom surface of the fixing screw 31 in the first longitudinal channel or passageway or hole 45 and a second end of the spring 43 contacts a top surface of the loadcell interface pin 23. The second end of the spring 43 is received in the longitudinal channel or passageway or hole of the first thermal break 39 so as to contact the top end of the loadcell interface pin 23 that is also received in the longitudinal channel or passageway or hole of the first thermal break 39.

[0221] The spring 43 provides a direct electrical connection between the fixing screw 31 and the loadcell interface pin 23 through the first thermal break 39, and therefore provides an electrical connection between the pan part 13 and the loadcell interface pin 23 through the first thermal break 39. The spring 43 may also, or alternatively, provide an electrical connection between the pan part 13 and the loadcell interface pin 23 via the spacer 21 which is also in contact with the spring 43.

[0222] In particular, an electrically conductive path or electrical continuity is provided from the protrusions 19 of the pan part 13 that contact the wafer (the wafer contact point) through to the loadcell interface pin 23. This electrically conductive path is shown with reference numeral 53 in FIG. 9, which is otherwise the same as FIG. 7. The additional reference numerals in FIG. 7 are omitted in FIG. 9 for conciseness. In particular, the electrically conductive path extends from the protrusions 19, through the body of the pan part 13, through the fixing screw 31, through the spring 43 and through the loadcell interface pin 23.

[0223] The mounting part 27 of the load cell 29 on which the weighing pan 11 is mounted is also electrically conductive. The mounting part 27 is made of an electrically conductive material such as stainless steel. Therefore, an electrical connection is provided to the load cell 29 through the mounting part 27.

[0224] The load cell 29 may be electrically connected to ground or earth, such that electric charges on the wafer are discharged to ground or earth. The electrically conductive path 53 in FIG. 9 therefore continues into the load cell and subsequently to earth or ground.

[0225] As illustrated in FIG. 8, the spacer 21 further comprises a second longitudinal channel or passageway or hole 55 formed in the body 44. The second longitudinal channel or passageway or hole 55 extends from the upper or top surface 47 of the spacer 21 to the lower or bottom surface of the space 21. The second longitudinal channel or passageway or hole 55 is therefore a through-hole or through-channel. A width or diameter of the second longitudinal channel or passageway or hole 55 changes along the length of the second longitudinal channel or passageway or hole 55 as illustrated in FIG. 8.

[0226] As discussed above, the grub screw 35 is received in the second opening 37, which is an opening of the second longitudinal channel or passageway or hole 55 at the upper or top surface 47 of the spacer 21. The second opening is threaded, so that the grub screw 35 can be screwed into the second opening 37

[0227] Furthermore, as illustrated in FIG. 7, the second thermal break 41 is positioned in a lower or bottom portion of the second longitudinal channel or passageway or hole 55 in the spacer 21. In particular, the second thermal break 41 is press-fit into the lower or bottom portion of the second longitudinal channel or passageway or hole 55 through an opening of the second longitudinal channel or passageway or hole 55 at the lower or bottom surface 49 of the spacer 21.

[0228] The second thermal break 41 has a hole (or opening or bore) formed in the lower surface of the second thermal break 41 . The hole extends part way along the length of the second thermal break 41 to form a channel in the second thermal break 41 that is closed at the top end.

[0229] As illustrated in FIG. 7, a first end of the anti-rotation pin 25 is received in the hole or channel of the second thermal break 41. In particular, the first end of the anti-rotation pin 25 is press-fit into the hole or channel of the second thermal break 41. the first end of the anti-rotation pin 25 is also located inside the second longitudinal channel or passageway or hole 55 in the spacer 21 , as illustrated in FIG. 7.

[0230] As illustrated in FIG. 7, the second thermal break 41 surrounds a circumferential surface or side surface of the first end of the anti-rotation pin 25 and covers the first end of the anti-rotation pin 25, so that there is no direct contact between the first end of the anti-rotation pin 25 and the spacer 21 . The second thermal break 41 therefore thermally insulates the first end of the anti-rotation pin 25, and therefore the anti-rotation pin 25 as a whole, from the spacer 21.

[0231] As illustrated in FIG. 7, substantially the whole of the second thermal break 41 is received in the lower or bottom portion of the second longitudinal channel or passageway or hole 55 in the spacer 21. In particular, only a small part of the second thermal break 41 protrudes beyond the lower or bottom surface 49 of the spacer 21 to form a protruding lip or rim or wall 57 around the opening of the second longitudinal channel or passageway or hole 55 in the lower or bottom surface 49 of the spacer 21. The protruding lip or rim or wall 57 helps to prevent any contact between the anti-rotation pin 25 and the bottom surface 49 of the spacer 21. Of course, in other embodiments the protruding lip or rim or wall 57 may be omitted.

[0232] Therefore, substantially a whole circumferential surface or side surface of the second thermal break 41 is surrounded by the spacer 21. Furthermore, at least part of a top surface of the second thermal break is covered by the spacer 21. Since the spacer 21 is electrically conductive, the spacer 21 may shield any electric charges on or in the second thermal break 41 from around the circumference or side of the second thermal break 41 and at least partly from above the second thermal break 41. This may prevent such electric charges from causing electrostatic forces between the second thermal break 41 and other components such as a load cell on which the weighing pan 11 is mounted.

[0233] In particular, the spacer 21 forms a conductive shield around substantially the whole circumferential surface of the second thermal break 41 and at least partly above the second thermal break 41.

[0234] In particular, in the weighing pan 11 of the present embodiment, a circumferential surface or side surface of the second thermal break 41 is shielded by the spacer 21 that surrounds the second thermal break 41 , and at least part of a top surface of the second thermal break 41 is shielded by the spacer 21 , therefore reducing the effects of any electrostatic charges formed on or in the second thermal break 41.

[0235] The second thermal break 41 is provided at a bottom portion of the spacer 21 and surrounds the first end of the anti-rotation pin 25. The second thermal break 41 is therefore immediately adjacent to the antirotation pin 25.

[0236] The weighing pan 11 according to the present embodiment therefore provides thermal breaks between the protrusions 19 that contact the wafer (the wafer contact points) and the loadcell interface pin 23 and the anti-rotation pin 25. These thermal breaks are located immediately adjacent to the loadcell interface pin 23 and the anti-rotation pin 25. Furthermore, the weighing pan 11 according to the present embodiment provides an electrically conductive path / electrical continuity from the protrusions 19 that contact the wafer (the wafer contact points) to the loadcell interface pin 23. Furthermore, the weighing pan 11 according to the present embodiment shields electric charges (electrostatic charges) on the thermal breaks, reducing electrostatic forces that may otherwise be caused by the electric charges.

[0237] Of course, in other embodiments the second longitudinal channel or passageway or hole 55 could be replaced with separate holes or openings in the upper or top surface 47 of the spacer 21 and the bottom or lower surface 49 of the spacer 21 that are not connected together.

[0238] Furthermore, in other embodiments the grub screw 35 and / or the anti-rotation pin 25 and second thermal break 41 and / or the second longitudinal channel or passageway or hole 55 could be omitted entirely.

[0239] In other embodiments different materials can be used to the materials specified above. For example, different conductive materials could be used to the stainless steel mentioned above, for example aluminium.

[0240] Furthermore, in other embodiments the spring 43 could be replaced with an alternative conductive part with relatively poor thermal conductivity, for example a conductive wire.

[0241] Furthermore, the shapes and / or sizes of any of the components may be different to those illustrated in FIGS. 1 to 9.

[0242] FIG. 10 is a schematic sectional illustration of a weighing pan according to a second embodiment of the present invention. In the second embodiment, the weighing pan 59 comprises a pan part 61 that may be the same as the pan part 13 described above. The pan part 61 in the second embodiment may therefore have any of the features of the pan part 13 in the first embodiment described above, unless incompatible. In particular, the pan part 61 comprises the same protrusions 19 as the protrusions 19 described above. The pan part 61 may also comprise the horizontal arms 15 and central hub 17 described above.

[0243] The pan part 61 is electrically conductive. The pan part 61 comprises or is made of electrically conductive material.

[0244] As illustrated in FIG. 10, the pan part 61 is mounted on a spacer 63. The spacer 63 extends perpendicularly to the bottom surface of the pan part 61. The spacer 63 may therefore form a shaft or post of the weighing pan 61.

[0245] At least part of the spacer 63 is arranged along a central longitudinal axis of the pan part 61 that extends through the centre of the pan part 61.

[0246] The spacer 61 is electrically conductive. The spacer 61 is made of an electrically conductive material. For example, the spacer 61 may comprise or be made of stainless steel.

[0247] In this embodiment the spacer 63 is integrally formed with the pan part 61. Of course, in other embodiments the spacer 63 may be attached to the pan part 61 , for example by a fixing screw in the same manner as the fixing screw 31 described above in relation to the first embodiment.

[0248] The spacer 63 has a longitudinal channel or passageway or hole 65 formed in the spacer 63. The longitudinal channel or passageway or hole 65 is open at the bottom end of the spacer 63. The longitudinal channel or passageway or hole 65 is closed at the top end of the spacer 63 where the spacer 63 is integrally formed with the pan part 61.

[0249] The spacer 63 may therefore be cylindrically shaped, or ring-shaped.

[0250] A thermal break 67 is positioned inside the longitudinal channel or passageway or hole 65 formed in the spacer 63.

[0251] The thermal break 67 is a thermal insulator and is made of thermally insulating material. For example, the thermal break 67 may comprise or be made of plastic. The plastic may be an electrostatic dissipative (ESD) plastic, which is a type of plastic designed to reduce static electricity. The plastic may be electrically conductive PEEK (polyether ether ketone), for example.

[0252] As illustrated in FIG. 10, the thermal break 67 is press-fit into the longitudinal channel or passageway or hole 65 through the opening of the longitudinal channel or passageway or hole 65 at the bottom end of the spacer 63.

[0253] The thermal break 67 may extend along the whole length of the longitudinal channel or passageway or hole 65.

[0254] The thermal break 67 has a central longitudinal channel or passageway or hole that extends along the length of the thermal break 67 from a top side of the thermal break 67 to a bottom side of the thermal break 67. The longitudinal channel or passageway or hole is therefore a through-hole or through- channel. The thermal break 67 may therefore be substantially cylindrical, or ring-shaped, for example.

[0255] As illustrated in FIG. 10, the weighing pan 59 further comprises a load cell interface part 69. The load cell interface part 69 comprises a loadcell interface pin 71 and an anti-rotation pin 73 that are integrally formed, or attached or connected together, for example so as to form a unitary part.

[0256] The loadcell interface pin 71 and / or anti-rotation pin 73 may be the same as the loadcell interface pin 23 and / or anti-rotation pin 25 described above, and therefore may include any of the features of the loadcell interface pin 23 and / or anti-rotation pin 25 described above.

[0257] The loadcell interface part 69 is electrically conductive and is made of electrically conductive material, for example stainless steel.

[0258] The shape and positioning of the loadcell interface pin 71 and anti-rotation pin 73 may be the same as that of the first embodiment, such that the weighing pan 59 can be mounted on the same or corresponding load cell 29 to that illustrated in FIG. 4.

[0259] A first end of the load cell interface part 69 is received in a lower portion of the longitudinal channel or passageway or hole of the thermal break 67. In particular, the first end of the load cell interface part 69 is press-fit into the longitudinal channel or passageway or hole of the thermal break 67. The first end of the load cell interface part is also located inside the longitudinal channel or passageway or hole 65 formed in the spacer 63, as illustrated in FIG. 10.

[0260] As illustrated in FIG. 10, the thermal break 67 surrounds a circumferential surface or side surface of the first end of the load cell interface part 69, so that there is no direct contact between the first end of the load cell interface part 69 and the spacer 63. The thermal break 67 therefore thermally insulates the first end of the load cell interface part 69, and therefore the load cell interface part 69 as a whole, from the spacer 63.

[0261] As illustrated in FIG. 10, the whole of the thermal break 67 is received in the longitudinal channel or passageway or hole 65 formed in the spacer 63. Therefore, a whole circumferential surface or side surface of the thermal break 67 is surrounded by the spacer 63. Since the spacer 63 is electrically conductive, the spacer 63 may shield any electric charges (electrostatic charges) on or in the thermal break 67 from around the circumference of the thermal break 67. This may prevent such electric charges from causing electrostatic forces between the thermal break 67 and other components such as a load cell on which the weighing pan 59 is mounted.

[0262] In particular, the spacer 63 forms a cylindrical or ring-shaped conductive shield around the whole circumferential surface or side surface of the thermal break 67.

[0263] In particular, in the weighing pan 59 of the present embodiment, a circumferential surface of the thermal break 67 is shielded by the spacer 63 that surrounds the thermal break 67, therefore reducing the effects of any electrostatic charges formed on or in the thermal break 67. The thermal break 67 extends to a bottom portion of the spacer 63 and surrounds the first end of the load cell interface part 69. The thermal break 67 is therefore immediately adjacent to the load cell interface part 69 and therefore the loadcell interface pin.

[0264] As illustrated in FIG. 10, a spring 75 is positioned in the upper portion of the longitudinal channel or passageway or hole of the thermal break 67. In particular, the spring 75 extends from the first end of the load cell interface part 69 to the top closed end of the longitudinal channel or passageway or hole of the thermal break 67.

[0265] The spring 75 is electrically conductive and is made of an electrically conductive material, such as stainless steel.

[0266] The spring 75 provides an electrical connection between the pan part 61 and the load cell interface part 69, and therefore the loadcell interface pin 71 , through the thermal break 67.

[0267] In particular, an electrically conductive path or electrical continuity is provided from the protrusions 19 of the pan part 61 that contact the wafer (the wafer contact point) through to the loadcell interface pin 71. In particular, the electrically conductive path extends from the protrusions 19, through the body of the pan part 61 , through the spring 75 and through the loadcell interface pin 71.

[0268] In other embodiments different materials can be used to the materials specified above. For example, different conductive materials could be used to the stainless steel mentioned above, for example aluminium.

[0269] Furthermore, in other embodiments the spring 75 could be replaced with an alternative conductive part with relatively poor thermal conductivity, for example a conductive wire.

[0270] Furthermore, the shapes and / or sizes of any of the components may be different to those illustrated in FIG. 10.

[0271] FIG. 11 is a schematic illustration of a weighing pan according to a third embodiment of the present invention.

[0272] In the third embodiment, the weighing pan 77 comprises a pan part 79 that may be the same as the pan part 13 described above. The pan part 79 in the third embodiment may therefore have any of the features of the pan part 13 in the first embodiment described above, unless incompatible. In particular, the pan part 79 comprises the same protrusions 19 as the protrusions 19 described above. The pan part 79 may also comprise the horizontal arms 15 and central hub 17 described above.

[0273] The pan part 79 is electrically conductive and comprises, or is made of, an electrically conductive material.

[0274] Furthermore, the weighing pan 77 further comprises a loadcell interface pin 81 for mounting the weighing pan 77 on a load cell.

[0275] The loadcell interface pin 81 extends perpendicularly to a bottom surface of the pan part 79. The loadcell interface pin therefore forms a shaft or post of the weighing pan 77. The loadcell interface pin 81 is arranged along a central longitudinal axis of the pan part 79 that extends through the centre of the pan part 79.

[0276] In this embodiment, the loadcell interface pin 81 comprises, or is made of, a material that is both a thermal insulator and electrically conductive. Therefore, the loadcell interface pin 81 provides a thermal break between the pan part 79 and the load cell on which the weighing pan 77 is mounted. Furthermore, the loadcell interface pin 81 provides an electrically conductive path between the pan part 79 and the load cell on which the weighing pan 77 is mounted so that electric charges on a wafer loaded onto the pan part can be discharged through the load cell. For example, the load cell may be electrically connected to ground or earth.

[0277] For example, the loadcell interface pin 81 may comprise, or be made of, an electrically conductive plastic. Suitable examples of an electrically conductive plastic include Vespel SP202 0.35 W / Km, Ketron CA30 0.92 W / Km, or PEEK ELS 0.46 W / Km, for example.

[0278] Since the loadcell interface pin 81 is electrically conductive, and is electrically connected to the load cell when the weighing pan 77 is mounted on the load cell, the loadcell interface pin may not have any electric charges (electrostatic charges) on or in the loadcell interface pin 81.

[0279] Of course, the weighing pan 77 may also additionally comprise an anti-rotation pin, which may be connected to the loadcell interface pin 81 , or separately connected to the pan part 79.

[0280] The loadcell interface pin 81 and the pan part 79 may be integrally formed, for example as a single piece, for example, the loadcell interface pin 81 and the pan part may be formed at the same time as a single piece, for example molded at the same time from plastic.

[0281] FIG. 12 is a schematic illustration of a weighing pan according to a fourth embodiment of the present invention.

[0282] In the fourth embodiment, the weighing pan 83 comprises a pan part 85 that may be the same as the pan part 13 described above, for example. The pan part 85 in the fourth embodiment may therefore have any of the features of the pan part 13 in the first embodiment described above, unless incompatible.

[0283] The pan part 85 is electrically conductive and comprises, or is made of, an electrically conductive material.

[0284] Furthermore, the weighing pan 83 further comprises a loadcell interface pin 87 for mounting the weighing pan 83 on a load cell.

[0285] The loadcell interface pin 87 extends perpendicularly to a bottom surface of the pan part 85. The loadcell interface pin therefore forms a shaft or post of the weighing pan 83.

[0286] The loadcell interface pin 87 is arranged along a central longitudinal axis of the pan part 85 that extends through the centre of the pan part 85.

[0287] In this embodiment, the loadcell interface pin 87 comprises a shaft 89 that extends from the pan part 85 at an upper end of the shaft 89. The shaft 89 comprises, or is made of, a material that is both a thermal insulator and an electrical insulator. Therefore, the shaft 89 provides a thermal break between the pan part 85 and the load cell on which the weighing pan 83 is mounted. The shaft 89 may comprise or be made of any of the suitable materials discussed above.

[0288] An electrically conductive part 91 is positioned at the lower end of the shaft 89. In this embodiment the electrically conductive part 91 is in the form of a cone-shaped part with a tip of the cone pointing downwards, but of course this specific shape is not essential. The electrically conductive part 91 is for mounting the weighing pan 83 on the load cell. For example, the electrically conductive part 91 may be received in a correspondingly shaped recess in the load cell.

[0289] Furthermore, an electrically conductive spring 93 is arranged around the shaft 89. In particular, the electrically conductive spring 93 extends along a whole length of the shaft 89 with the shaft received in the central channel of the spring 93. The electrically conductive spring 93 is directly or indirectly electrically connected to both the pan part 85 and the electrically conductive part 91 and therefore directly or indirectly electrically connects the pan part 85 to the electrically conductive part 91.

[0290] Therefore, according to this embodiment, a thermal break is provided between the pan part 85 and the electrically conductive part 91 in the form of the shaft 89. However, an electrical connection through the weighing pan 83 is provided via the electrically conductive spring 93. In particular, when the loadcell interface pin 87 is received in the load cell the pan part 85 will be electrically connected to the load cell via the spring 93 and the electrically conductive part 91.

[0291] Furthermore, since the electrically conductive spring 93 is arranged around the outside of the shaft 89, the electrically conductive spring 93 will provide at least some shielding of electrostatic charges on the shaft 89, thereby reducing the problems caused by such electrostatic charges discussed above. This may be sufficient to reduce the effects of such electrostatic charges to acceptable levels. In particular, such partial shielding of the electrostatic charges may be sufficient for at least some applications.

[0292] In this embodiment, the electrically conductive part 91 may correspond to the mounting part specified in the claims, the shaft 89 may correspond to the thermal break specified in the claims, the pan part 85 may correspond to the support part specified in the claims, and the spring 93 may correspond to the electrically conductive part or electrostatically dissipative part specified in the claims.

[0293] 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.

[0294] 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. 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.

[0295] Any section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.

[0296] 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. 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

28Claims:

1. A support for use in a weighing device, the support comprising: a support part for supporting an object during a weight measurement; a mounting part for mounting the support on a weighing device; a thermal break provided between the support part and the mounting part; and an electrically conductive part or electrostatically dissipative part provided around at least part of the thermal break.

2. The support according to claim 1 , wherein at least part of the support part and at least part of the mounting part are electrical conductors.

3. The support according to claim 2, wherein the support comprises an electrically conductive path between the support part and the mounting part.

4. The support according to claim 3, wherein the electrically conductive path extends through at least part of the thermal break or around at least part of an outside of the thermal break.

5. The support according to claim 3 or claim 4, wherein the electrically conductive path comprises an electrically conductive element that extends through at least part of the thermal break or around at least part of an outside of the thermal break.

6. The support according to claim 5, wherein the electrically conductive element is an electrically conductive spring.

7. The support according to any of the preceding claims, wherein the electrically conductive part or electrostatically dissipative part laterally surrounds at least part of the thermal break.

8. The support according to any of the preceding claims, wherein the electrically conductive part or electrostatically dissipative part extends over at least part of a top end of the thermal break.

9. The support according to any of the preceding claims, wherein at least part of a bottom end of the thermal break is covered by the mounting part.

10. The support according to any of the preceding claims, wherein the thermal break is enclosed, or substantially enclosed, by the electrically conductive part or electrostatically dissipative part and the mounting part.

11. The support according to any of the preceding claims, wherein the electrically conductive part or electrostatically dissipative part comprises a body having a hole in which at least part of the thermal break is received.

12. The support according to claim 11 , wherein the hole is a through-hole that extends from a top surface of the body to a bottom surface of the body, and wherein at least part of the thermal break is received in a bottom portion of the through-hole.

13. The support according to claim 12, wherein the support part is attached to the body by a connector that extends into a top portion of the through-hole.

14. The support according to claim 13, wherein the support comprises an electrically conductive path between the support part and the mounting part that extends through at least part of the thermal break; and the electrically conductive path comprises an electrically conductive element that is in contact with the connector at a first end of the electrically conductive element, extends through at least part of the thermal break, and is in contact with the mounting part at a second end of the electrically conductive element.

15. The support according to any of claims 11 to 14, wherein part of the thermal break protrudes from the hole.

16. The support according to any of the preceding claims, wherein: the thermal break comprises a through-hole; and part of the mounting part is received in a bottom portion of the through-hole.

17. The support according to claim 16 as dependent on claim 14, wherein: the electrically conductive element extends along a top portion of the through-hole of the thermal break to contact the part of the mounting part that is received in the bottom portion of the through-hole of the thermal break.

18. The support according to any of the preceding claims, wherein the thermal break is in contact with the mounting part.

19. The support according to any of the preceding claims, wherein the support further comprises an anti-rotation pin for being received in a corresponding recess of the weighing device.

20. The support according to claim 19, wherein the support further comprises a further thermal break provided between the support part and the anti-rotation pin.

21. The support according to claim 20, wherein the electrically conductive part or electrostatically dissipative part is further provided around at least part of the further thermal break.

22. The support according to claim 21 , wherein the electrically conductive part or electrostatically dissipative part laterally surrounds at least part of the further thermal break.

23. The support according to claim 21 or claim 22, wherein the electrically conductive part or electrostatically dissipative part is provided over at least part of a top end of the further thermal break.

24. The support according to any of claims 20 to 23, wherein at least part of a bottom end of the further thermal break is covered by the anti-rotation pin.

25. The support according to any of claims 12 to 24, wherein the further thermal break is enclosed, or substantially enclosed, by the electrically conductive part or electrostatically dissipative part and the antirotation pin.

26. The support according to any of claims 21 to 25, wherein the electrically conductive part or electrostatically dissipative part comprises a body having a hole in which at least part of the further thermal break is received.

27. The support according to claim 26, wherein part of the further thermal break protrudes from the hole.

28. The support according to any of claims 20 to 27, wherein: the further thermal break comprises a hole; and part of the anti-rotation pin is received in the hole.

29. The support according to any of claims 20 to 28, wherein the further thermal break is in contact with the anti-rotation pin.

30. The support according to any of the preceding claims, wherein the support is a balance pan.

31. The support according to any of the preceding claims, wherein the mounting part is a loadcell interface pin.

32. The support according to any of the preceding claims, wherein the electrically conductive part or electrostatically dissipative part provided around at least part of the thermal break comprises an electrically conductive spring, and wherein the electrically conductive spring directly or indirectly electrically connects the support part to the mounting part.

33. The support according to claim 32, wherein: the thermal break comprises a shaft provided between the support part and the mounting part; and the electrically conductive spring is arranged around an outside of the shaft.

34. A support for use in a weighing device, the support comprising:a support part for supporting an object during a weight measurement; and a mounting part for mounting the support on a weighing device; wherein at least part of the mounting part is a thermal insulator and an electrical conductor.

35. The support according to claim 34, wherein the support part and the mounting part are formed as a single piece.

36. The support part according to claim 34 or claim 35, wherein the at least part of the mounting part has a thermal conductivity of less than or equal to 1 W / Km and / or an electrical resistance of less than or equal to 1 MOhm.

37. The support according to any of claims 34 to 36, wherein the at least part of the mounting part is made of a material that is both a thermal insulator and an electrical conductor.

38. The support according to any of claims 34 to 37, wherein the at least part of the mounting part is made of conductive plastic or conductive ceramic.

39. The support according to any of claims 34 to 38, wherein at least part of the support part is an electrical conductor.

40. A support for use in a weighing device, the support comprising: a support part for supporting an object during a weight measurement; and a mounting part for mounting the support on a weighing device; wherein at least part of the support part is a thermal insulator and an electrical conductor.

41. The support according to claim 40, wherein at least part of the mounting part is an electrical conductor.

42. The support according to claim 40 or 41 , wherein the at least part of the support part has a thermal conductivity of less than or equal to 1 W / Km and / or an electrical resistance of less than or equal to 1 Mohm.

43. The support according to any of claims 40 to 42, wherein the at least part of the support part is made of a material that is both a thermal insulator and an electrical conductor.

44. The support according to any of claims 40 to 43, wherein the at least part of the support part is made of conductive plastic or conductive ceramic.

45. A support for use in a weighing device, the support comprising: a support part for supporting an object during a weight measurement; a mounting part for mounting the support on a weighing device; and32 a thermal break provided between the support part and the mounting part, wherein the thermal break is electrically conductive.

46. A weighing device having the support according to any of the preceding claims.

47. The weighing device according to claim 46, wherein the weighing device further comprises a load cell.

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