EP-4736219-A1 - WAFER HOLDER

EP4736219A1EP 4736219 A1EP4736219 A1EP 4736219A1EP-4736219-A1

Abstract

A wafer holder and treatment arrangement to be mounted to a vacuum wafer treatment chamber, comprising: • a base arrangement with an annular surface; • a metal circular wafer carrier plate mounted centrally on a drive shaft centered with respect to a center of said annular surface, said drive shaft with the carrier plate being rotatable about a rotational axis Z through said center of said annular surface with respect to and supported by said base arrangement; • a dynamic vacuum seal configuration operatively connected to the drive shaft; • an axial distance setting device mounted lockable to the drive shaft and designed to be rotatably supported by an element of said base arrangement or in or on the floor of a treatment chamber to set a critical distance d c ; • wherein said critical distance d c is defined as a distance in a direction parallel to axis Z between said annular surface of said base arrangement and one surface of said metallic circular wafer carrier plate facing the base arrangement and being in parallel with said annular surface.

Inventors

BREUSS, HUBERT
WALSER, David Meinrad
LUTZ, ALEXANDER
FAZIO, Valerio
BECK, SEBASTIAN
RHYNER, STEFAN

Assignees

Evatec AG

Dates

Publication Date: 20260506
Application Date: 20240606

Claims (1)

CLAIMS 1. A wafer holder and treatment arrangement to be mounted to a vacuum wafer treatment chamber, comprising ^ a base arrangement with an annular surface; ^ a metal circular wafer carrier plate mounted centrally on a drive shaft centered with respect to a center of said annular surface, said drive shaft with the carrier plate being rotatable about a rotational axis Z through said center of said annular surface with respect to and supported by said base arrangement;, ^ a dynamic vacuum seal configuration operatively connected to the drive shaft; ^ an axial distance setting device mounted lockable to the drive shaft and designed to be rotatably supported by an element of said base arrangement or in or on the floor of a treatment chamber to set a critical distance d c ; ^ wherein said critical distance dc is defined as a distance in a direction parallel to axis Z between said annular surface of said base arrangement and one surface of said metallic circular wafer carrier plate facing the base arrangement and being in parallel with said annular surface. 2. The wafer holder and treatment arrangement of claim 1, whereat the base arrangement further comprises an extended, essentially plane surface bordered by a protruding circumferential rim forming said annular surface in a direction towards the one surface of said wafer carrier plate. 3. The wafer holder and treatment arrangement of claim 1 or claim 2, whereat the rim further comprises a circumferential inner rim surface protruding from and bordering the essentially plane surface, whereat a surface of said metal circular wafer carrier plate facing said base arrangement, said extended, essentially plane surface and said inner rim surface commonly define a heater compartment, the heater compartment comprising a multitude of heater lamp tubes arranged in said heater compartment along said extended, essentially plane surface and along said one surface of said metal circular wafer carrier plate, and directed to said one surface of said metal circular wafer carrier plate, and mounted to said base arrangement. 4. The wafer holder and treatment arrangement of one of the forgoing claims, comprising a wafer retaining arrangement to be operationally coupled to said metal circular wafer carrier plate; 5. The wafer holder and treatment arrangement of one of the forgoing claims, whereat at least three wafer supports are mounted extendable and retractable out of or into said annular surface. 6. The wafer holder and treatment arrangement of one of claims 1 to 5, said base arrangement comprising further a bottom plate comprising said annular surface and said dynamic vacuum seal configuration, said seal configuration encompassing in operation a sealing surface of the drive shaft of the wafer carrier plate, whereat the distance setting device is operationally supported rotatably by an element of said bottom plate or an element of said dynamic vacuum seal configuration. 7. The wafer holder and treatment arrangement of one of the forgoing claims, whereat the distance setting device comprises a longitudinally slotted or longitudinally divided hollow body made from a bearing alloy, or at least provided with a dry gliding layer on a gliding surface of a face area of the hollow body, with an internal fine thread to interact with a shaft fine thread on an outer diameter of said drive shaft, and a locking mechanism to clamp the slotted hollow body and/or lock or dismantle the hollow body on or from said fine thread of the drive shaft. 8. The wafer holder and treatment arrangement of claim 7, whereat the locking mechanism comprises at least one threaded connection between two slot sides of the hollow body outside the diameter of the fine thread and parallel to a tangent of the fine thread diameter. 9. The wafer holder and treatment arrangement of claim 7 or claim 8, whereat the slotted hollow body is in the form of a nut comprising said internal fine thread and a thread-free counterbore area, whereat in said thread-free counterbore area of said hollow body a spring and snap-in ball assembly is provided in a radial bore of the body with an opening towards axis Z to interact with respectively elongated, axially directed groves provided in an outer diameter of said drive shaft. 10. The wafer holder and treatment arrangement of one of the forgoing claims, said metal circular wafer carrier plate being electrically isolated from said base arrangement and designed to be electrically connected or capacitively coupled to an electric biasing source. 11. The wafer holder and treatment arrangement of one of the forgoing claims, whereat at least one electric isolator is arranged between said drive shaft and said carrier plate, and a peripheral surface area of said surface facing the base arrangement is arranged in parallel with at least a part of said annular surface of the base arrangement, said peripheral surface area and said annular surface both forming together an essentially circumferential planar capacitor with a defined capacitive gap of said critical distance d c . 12. The wafer holder and treatment arrangement of one of the forgoing claims, comprising a gas outlet- and dispensing-arrangement through and along a wafer carrying surface of said metal circular wafer carrier plate. 13. The wafer holder and treatment arrangement of one of the forgoing claims, whereat said carrier plate comprises a double-walled sleeve-cup mounted with its outer cup- wall on or in a center of said surface facing the base arrangement and with its inner cup-wall electrically isolated on a head of the drive shaft. 14. The wafer holder and treatment arrangement of claim 13, whereat the sleeve-cup comprises a central gas passthrough from a central gas inlet of the drive shaft towards said gas outlet- and dispensing-arrangement, the passthrough comprising or forming an opening towards the space between the double walls. 15. The wafer holder and treatment arrangement of claim 13 or 14, whereat said head of the drive shaft comprises two parallel flanges overlapping in a Z-projection and each oriented to a different end of the drive shaft, with at least one isolator mounted on each flange and fixing elements to mount the sleeve-cup on the drive shaft. 16. The wafer holder and treatment arrangement of one of the forgoing claims, whereat said heater compartment further comprises an inner protective wall circumferential to the drive shaft and/or the sleeve-cup. 17. The wafer holder and treatment arrangement of one of claims 4 to 16, said wafer retaining arrangement is a weight-ring dimensioned so as to reside on the periphery of a wafer. 18. A vacuum treatment apparatus comprising a wafer holder and treatment arrangement according to one of the forgoing claims, the apparatus comprising a vacuum pumping arrangement and at least one target and a target shutter to separate said target from a process space between said target and said wafer carrying surface. 19. The vacuum treatment apparatus of claim 18, comprising at least two targets with respective target shutter(s) and optionally one process shutter to separate all targets at once from said process space. 20. A method of setting a nominal value of a critical distance dc between a base arrangement and a rotatable metal circular wafer carrier plate by an axial distance setting device being designed to amend respective distance values in predefined differential steps, whereat - said distance dc is defined as a distance in a direction parallel to a rotational axis Z, between said base arrangement and one surface of said metallic circular wafer carrier plate facing the base arrangement and/or a corresponding radial extended surface of a component attached to the carrier plate to rotate therewith; - said base arrangement comprises at least an essentially annular surface; - said wafer carrier plate being centrally mounted on a drive shaft being rotatable about rotational axis Z through said center of said annular surface with respect to said base arrangement; - said distance setting device being mounted lockable to the drive shaft and designed to be supported rotatably by an element of said base arrangement, by a housing of a dynamic vacuum seal, or in or on the bottom of a treatment chamber; whereat said setting comprises at least the following steps in the specified sequence: - determining an average distance dcA by measuring distance d c several times in different positions of the wafer carrier plate in relation to the base arrangement, calculating the mean value d cA thereof, comparing it to a nominal distanc dcN, and in case of a difference surmounting a distance value of at least one differential step as predefined: - demounting said drive shaft together with said wafer carrier plate and said distance setting device from the base arrangement; - adjusting said average distance dcA in differential steps as predefined by said distance setting device to the nominal distance dcN in the demounted state and locking the distance setting device on the drive shaft, - mounting said drive shaft together with said wafer carrier plate and said distance setting device to the base arrangement and the drive. 21. The method of claim 20, whereat for said determining of an average distance dcA a weight-ring or a dummy weight is set on the circular wafer carrier plate. 22. A rotary drive shaft and vacuum feedthrough having a vertical rotational axis Z’, a shaft head and a shaft foot, the drive shaft comprising ^ mounting means (62, 67, 68) designed to mount a carrier plate (20) centrally on the head (61) of the drive shaft (60); ^ a power coupling area (75) at or near the foot (75) of the drive shaft (60); ^ an elongated sealing surface (75) round a diameter of the drive shaft (60); ^ an axial distance setting device (30) encompassing a thread diameter of the drive shaft (60) and mounted movable and lockable in an axial parallel direction to axis Z’ to the drive shaft (30), the distance setting device (30) having a gliding surface on a lower face (39) to support the distance setting device and the drive shaft when locked. 23. The rotary drive shaft of claim 22, whereat the distance setting device (30) has an internal thread (32) in engagement with an external thread (72) in the area of the thread diameter of the shaft (60). 24. The rotary drive shaft of claim 22 or 23, whereat the distance setting device (30) has a locking mechanism (35, 36, 36’) to lock a movement of the distance setting device (30) on the shaft. 25. The rotary drive shaft of one of claims 22 to 24, whereat the drive shaft (60) comprises a scaled diameter next to the threaded diameter, the scaled diameter having a circumferential readable scale with axially directed elongated markings (74), and the distance setting device (30) encompasses also the scaled diameter and has scale scanning means (38, 38’, 38’’) to set the distance setting device (30) stepwise from one marking to the next marking.

Description

WAFER HOLDER TECHNICAL FIELD OF THE INVENTION The current invention relates to a wafer holder and treatment arrangement, to a vacuum treatment apparatus and to a method to set a nominal value of a critical distance dc between a base arrangement and a rotatable metal circular wafer carrier plate. The invention further relates to a rotary drive shaft and vacuum feedthrough. DESCRIPTION OF THE RELATED ART Different embodiments of a wafer holder and treatment arrangement for high temperature applications are known from the prior art, e.g. from WO2013/030190 of the present applicant. Such a wafer holder and treatment arrangement, also called chuck in the following, works fine as long as manufacturing tolerances in the range of some tenth of a millimeter for the relevant assembled chuck elements do not influence certain systemic properties of a chuck. However, when certain properties, as an example the capacity of an RF-driven and capacitively coupled chuck depend on such small tolerances resulting from a multitude of assembled elements, large scattering of the desired property may result. Therefore, the present invention discloses a chuck where a tolerance deviation from a geometrical nominal value critical for certain properties of the assembled chuck can be adjusted comfortably. P219517 Definitions: An annular surface as used in the present description includes annular and disclike surfaces with a central hole as well as respective annular and disclike surfaces inter- rupted by recesses, which may be radially elongated or arranged in a radial symmetry along a radius within the annular surface, to accommodate functional elements like fastening means, different types of wafer supports to lift a wafer, media or measuring through holes and the like; A respective definition applies also to the term circumferential plane, rim, surface, boarder, shield or nose comprising also respectively interrupted structures. A respective definition applies also to the term circular wafer carrier plate which may include disc like carrier plates without or with a central hole, e.g. a central back- gas inlet, as well as respective circular plates interrupted by recesses as exemplarily mentioned above. A dynamic vacuum seal, also named dynamic seal or dynamic gasket in the following, is a vacuum seal for sealing a feedthrough, especially a rotary feedthrough of a respectively moving or moved element that is partly in vacuum and partly under atmosphere. Examples are dynamic seals to seal rotating shafts or dynamic gaskets to seal linear moving parts like linear shutters. An essentially plane surface in the sense of the present description is a plane surface which may also comprise electrical connectors, a viewing or measuring window, recesses or sockets to hold certain elements in place in, on or above the plane surface. P219517 SUMMARY OF THE INVENTION It is a task of the current invention to provide a chuck, e.g. a rotating chuck, which can be mounted easily and in high precision. It is a further task of the present invention to provide an assembled chuck allowing a measurement of a certain geometric parameter and adjusting the parameter, when necessary, by a predefined adjustment operation to set the parameter to a nominal value. It is a further task to set certain properties of the chuck by the as mentioned adjustment operation. As an example, it is a task of the present invention to provide means to set the capacity of an RF-chuck easily and precisely by adjusting the distance between a base arrangement and an electrically isolated wafer carrier plate, respectively by adjusting the distance between respective capacitance determining surfaces of the base arrangement and the wafer carrier plate. It is a further task of the present invention to provide means to position rotating parts in a vacuum treatment chamber with high precision towards the chamber or towards certain static installations within the treatment chamber. According to the present invention, at least one of these tasks is solved by a wafer holder and treatment arrangement according to claim 1, by a vacuum treatment apparatus according to claim 19, by a method according to claim 20, and a rotary drive shaft and vacuum feedthrough according to claim 22. At least some of these tasks are solved by an inventive embodiment of a wafer holder and treatment arrangement also P219517 known and named as a chuck in the following, to be mounted to a vacuum wafer treatment chamber, the wafer holder and treatment arrangement (the chuck) comprising: ^ a base arrangement with an annular surface; ^ a metal circular wafer carrier plate mounted centrally on a drive shaft centered with respect to a center of said annular surface, said drive shaft with the carrier plate being rotatable about a geometric axis Z through said center of said annular surface with respect to and supported by said base arrangement; ^ a dynamic vacuum seal configuration operatively connected to the drive sha