WO2021221648A1

WO2021221648A1 - Method of adjusting a mask arrangement, processing system, and computer-readable medium

Info

Publication number: WO2021221648A1
Application number: PCT/US2020/030655
Authority: WO
Inventors: Anirudh K. ALEWOOR; Prasanna Sampigehalli Narasimaiah; Prasad MADHAVABHOTLA
Original assignee: Applied Materials, Inc.
Priority date: 2020-04-30
Filing date: 2020-04-30
Publication date: 2021-11-04

Abstract

A method of adjusting a mask arrangement for masking a substrate during a layer deposition process is provided. The method includes applying forces to the mask arrangement (110) for reducing a deformation of the mask arrangement based on compensation information previously determined for the mask arrangement and stored in a database (180). Further, a processing system (100) for conducting such a method is described.

Description

METHOD OF ADJUSTING A MASK ARRANGEMENT, PROCESSING SYSTEM, AND COMPUTER-READABLE MEDIUM

TECHNICAL FIELD

[0001] Embodiments of the present disclosure relate to a mask arrangement for masking a substrate in a processing chamber, a system for vacuum processing of a substrate, and a method of adjusting a mask arrangement for masking a substrate in a processing chamber. Embodiments of the present disclosure particularly relate to systems and methods for reducing a deformation of a mask arrangement in a vacuum processing system, particularly in a vacuum deposition system for depositing a material on a substrate.

BACKGROUND

[0002] Several methods are known for depositing a material on a substrate. For example, substrates may be coated by using an evaporation process, such as a physical vapor deposition (PVD) process, a chemical vapor deposition (CVD) process, a sputtering process, or a spraying process. The process can be performed in a processing chamber of a vacuum deposition system, where the substrate to be coated is located. A deposition material is provided in the processing chamber. A plurality of materials, such as organic materials, metals, oxides, nitrides and carbides, may be used for deposition on a substrate. Further, other processes like etching, structuring, annealing, or the like can be conducted in processing chambers of a vacuum processing system.

[0003] Coated substrates may be used in several applications and in several technical fields. For instance, an application lies in the field of organic light emitting diode (OLED) panels. Further applications include insulating panels, microelectronics, such as semiconductor devices, substrates with TFT, color filters or the like.

[0004] OLEDs are solid-state devices composed of thin films including organic molecules that create light. OLEDs can provide bright displays for electronic devices that use less power than for instance light-emitting diodes (LEDs) or liquid crystal displays (LCDs). In the processing chamber, the organic molecules are generated (e.g., evaporated, sputtered, or sprayed etc.) and allowed to condense as thin films on the substrates. The particles pass through a mask having a pattern of small openings to form a plurality of OLED pixels on the substrate.

[0005] For proper material deposition onto a substrate to be coated, a mask arrangement is typically arranged in front of the substrate. Openings in the mask arrangement allow for a targeted deposition of the material. Accordingly, a proper alignment of the mask arrangement and the substrate relative to each other ensures the targeted deposition. However, a proper alignment may not be possible if the mask arrangement is deformed, e.g. due to intrinsic or extrinsic factors such as gravity, tensions in the material or thermal variations. In particular, a deformation of the mask arrangement may lead to a situation in which only a part of the mask openings is correctly aligned relative to the substrate while another part of the mask openings may be shifted relative to a correct relative position, negatively affecting the deposition result. A vertically oriented mask arrangement may be particularly susceptible to local deformations, e.g. due to a gravity-caused sagging of a central part of the mask arrangement. A deformation reduction of a mask assembly is typically time consuming and complex, and already a mask deformation within the range of several microns can deteriorate the deposition accuracy.

[0006] In light of the above, providing systems and methods for more reliably and more quickly adjusting mask arrangements for masking a substrate would be beneficial to overcome at least some of the described problems.

SUMMARY

[0007] In light of the above, a method of adjusting a mask arrangement for masking a substrate in a processing chamber, a processing system, and a computer readable medium or storage are provided according to the independent claims.

[0008] According to one aspect, a method of adjusting a mask arrangement for masking a substrate is provided. The method includes applying forces to the mask arrangement for reducing a deformation of the mask arrangement based on compensation information previously determined for the mask arrangement and stored in a database.

[0009] According to a further aspect, a method of inspecting a mask arrangement is provided, including: holding the mask arrangement at a holding arrangement including a plurality of adjustment elements, determining compensation information for the mask arrangement, wherein the compensation information is indicative of a deformation of the mask arrangement, and storing the compensation information in a database. Particularly, a compensation information for a plurality of mask arrangements may be determined and stored in the database, particularly in a table-format. The compensation information may be indicative of a respective deformation of the plurality of mask arrangements when held in a predetermined orientation at a respective holding arrangement. The method of inspecting the mask arrangement may be conducted before the above method of adjusting the mask arrangement for masking a substrate in a processing chamber.

[0010] According to a further aspect, a processing system is provided. The processing system includes a holding arrangement for holding a mask arrangement. The holding arrangement includes a plurality of adjustment elements configured to apply forces to the mask arrangement. The processing system further includes a database for storing compensation information determined for the mask arrangement, and a controller configured to retrieve the compensation information for the mask arrangement from the database and to control the plurality of adjustment elements based on the retrieved compensation information for reducing a deformation of the mask arrangement.

[0011] In some embodiments, the holding arrangement may be configured for holding the mask arrangement in an essentially vertical orientation. Specifically, the mask arrangement may be held in an essentially vertical orientation at the holding arrangement in the processing chamber.

[0012] According to a further aspect, a computer-readable medium or storage storing compensation information about a plurality of mask arrangements indicative of deformations of the plurality of mask arrangements is provided. The compensation information may be indicative of a respective deformation of the plurality of mask arrangements when held in a predetermined orientation at a holding arrangement, and can be determined for the plurality of mask arrangements by inspecting, e.g. optically inspecting, each mask arrangement of the plurality of mask arrangements.

[0013] In particular, the compensation information may include sets of shift values for controlling a plurality of adjustment elements for obtaining a deformation reduction of the plurality of mask arrangements. In other words, the compensation information may include sets of shift values that allow a reduction of a deformation of the plurality of mask arrangements, when these shift values are used for controlling a plurality of adjustment elements for applying forces to a respective mask arrangement.

[0014] Embodiments are also directed at apparatuses for carrying out the disclosed methods and include apparatus parts for performing each described method aspect. These method aspects may be performed by way of hardware components, a computer programmed by appropriate software, by any combination of the two or in any other manner. Furthermore, embodiments according to the present disclosure are also directed at methods for manufacturing the described apparatuses and methods of operating the described apparatus. Described embodiments include method aspects for carrying out every function of the described apparatuses.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments. The accompanying drawings relate to embodiments of the disclosure and are described in the following:

FIG. 1 shows a schematic view of a processing system according to embodiments described herein;

FIG. 2 schematically illustrates a deformed mask arrangement that is to be adjusted according to methods described herein;

FIG. 3 schematically shows an adjustment for reducing a deformation of a mask arrangement according to methods described herein; and

FIG. 4 shows a flow diagram for illustrating a method according to embodiments described herein.

DETAILED DESCRIPTION OF EMBODIMENTS

[0016] Reference will now be made in detail to the various embodiments of the disclosure, one or more examples of which are illustrated in the figures. Within the following description of the drawings, same reference numbers refer to same components. Generally, only the differences with respect to individual embodiments are described. Each example is provided by way of explanation of the disclosure and is not meant as a limitation of the disclosure. Further, features illustrated or described as part of one embodiment can be used on or in conjunction with other embodiments to yield yet a further embodiment. It is intended that the description includes such modifications and variations.

[0017] Embodiments described herein relate to methods and systems for adjusting mask arrangements. Mask arrangements are for example used in OLED deposition systems. The mask arrangement includes a mask, typically a flexible mask sheet, for masking a substrate in a processing chamber. The mask may have openings allowing for evaporated material to pass through the openings and to be deposited on the masked substrate. Accordingly, e.g. pixels can be deposited on the substrate. A typical mask sheet includes thousands or millions of small openings. Accordingly, a thorough alignment of the mask arrangement and the substrate relative to each other is beneficial for an accurate deposition of the evaporated material on the substrate. However, if the mask arrangement is deformed, e.g. due to material tensions, gravity-caused sagging, temperature variations in the material and/or other factors, an accurate relative alignment of the mask arrangement and the substrate over the whole area of the substrate is difficult to obtain or even impossible.

[0018] A mask arrangement may include a mask frame that supports a flexible mask sheet, e.g. a thin metal sheet, wherein the plurality of mask openings may be provided in the mask sheet. The mask sheet may be supported by the mask frame and may be fixed to the mask frame along a periphery thereof, e.g. by welding, such that the mask sheet is immovably held in position at the mask frame. A fine metal mask or a shadow mask having an area of 1 m² or more, particularly 5 m² or more, and millions of mask openings may be provided as a mask arrangement in some embodiments.

[0019] In a vacuum deposition system, the mask arrangement is subjected to various influences, e.g. different processing conditions, different forces, such as gravity, thermally caused forces due to temperature variations, holding forces due to the holding of the mask arrangement at a holding arrangement, and other forces. These and other influences may lead to a deformation of the mask arrangement as compared to an undeformed state of the mask arrangement in which the mask openings are exactly arranged in a predetermined pattern. Further, intrinsic forces, such as material tensions, may lead to deformations of the mask arrangement as compared to an undeformed state of the mask arrangement. Deformations include, for example, a local bending or a sagging of the mask frame that influences the pattern of the mask openings, or a thermally caused frame expansion or contraction that distorts the pattern of the mask openings. For allowing an accurate alignment of the mask arrangement relative to the substrate over the whole area of the substrate, the mask arrangement should beneficially include as small deformations as possible. For example, a local deformation of the mask arrangement of several microns may already severely distort the pattern of pixels deposited on the substrate. The deformation of the mask arrangement that is compensated according to methods described herein includes at least one or more of the group consisting of: a sagging due to gravity, a deformation of the mask arrangement caused by material tension, and a thermally caused deformation of the mask arrangement. [0020] According to embodiments described herein, a processing system is provided, particularly a vacuum processing system including one or more vacuum processing chambers. The processing system includes a holding arrangement for holding the mask arrangement, particularly in an essentially vertical orientation. The holding arrangement includes a plurality of adjustment elements configured to apply forces to the mask arrangement. The processing system further includes a database for storing compensation information determined for the mask arrangement. Further, the processing system includes a controller configured to retrieve the compensation information for the mask arrangement from the database and to control the plurality of adjustment elements based on the retrieved compensation information to reduce a deformation of the mask arrangement.

[0021] A processing system 100 according to embodiments described herein is schematically shown in FIG. 1. The processing system 100 includes a holding arrangement 101 for holding a mask arrangement 110, particularly in an essentially vertical orientation. The holding arrangement 101 includes a plurality of adjustment elements 125 configured to apply forces to the mask arrangement 110 held at the holding arrangement 101. The forces may be applied to the mask arrangement 110 for reducing a deformation of the mask arrangement. In some implementations, the mask arrangement 110 includes a mask frame 130 and a mask sheet 140 with a plurality of mask openings, the mask sheet being supported on and fixed to the mask frame.

[0022] In some embodiments, the holding arrangement 101 may include a mask carrier 105 for carrying the mask arrangement 110 in the processing chamber. The mask carrier 105 may be configured to transport the mask arrangement 110 through a vacuum processing system, particularly through a vacuum deposition system. The plurality of adjustment elements 125 may be provided at the mask carrier 105 or may alternatively be provided at a mask carrier holder that is provided in the processing chamber and is configured to hold the mask carrier in front of a substrate. In some embodiments, the mask carrier 105 may include a carrier main body and a carrier frame 120 connected to the carrier main body, and the plurality of adjustment elements 125 may be provided at the carrier frame 120.

[0023] The mask arrangement 110 may be held at the mask carrier 105 by mechanical fixing devices, such as clamps or holders, or by an electrostatic or magnetic chucking device. For example, the mask arrangement 110 may be held at the mask carrier 105 by one or more electropermanent magnet devices (EPMs). [0024] According to some embodiments, the holding arrangement 101 may be configured for holding the mask arrangement 110 in an essentially vertical orientation. As used throughout the present disclosure, the term “vertical” or “vertical orientation” is understood to distinguish over “horizontal” or “horizontal orientation”. That is, the “vertical orientation” relates to a substantially or essentially vertical orientation e.g. of the mask arrangement, wherein a deviation of a few degrees, e.g. up to 10° or even up to 15°, from an exactly vertical direction or vertical orientation is still considered as a “essentially vertical orientation”.

[0025] According to some embodiments, the mask arrangement 110 includes the mask frame 130 and the mask sheet 140. The mask arrangement may optionally further include a mask separation device surrounding the mask sheet 140. According to embodiments, the mask arrangement may include one or more mask sheets, the one or more mask sheets being arranged next to each other and/or one above the other. For example, four mask sheets may be arranged such that two respective mask sheets may be arranged next to each other and above the other two mask sheets. The mask separation device may separate the mask sheets. Beneficially, each mask sheet may be individually replaceable, i.e., the mask sheets can be individually removed from the mask frame and replaced by unused mask sheets.

[0026] The processing system 100 according to embodiments described herein further includes a database 180. The database 180 is configured to store compensation information determined for the mask arrangement 110. In FIG. 1, the database 180 is schematically depicted as a box. The compensation information may be determined by inspecting the mask arrangement 110, particularly before the mask arrangement is used in the processing chamber for the masked deposition on the substrate. It is to be understood that the database 180 may be at least partially provided on a virtual memory, for example a cloud memory, or any other volatile or non-volatile memory or storage, or the like. The database 180 may be provided on a computer storage or any other storage medium configured to store and provide data. The processing system may include respective hardware and software for storing and retrieving data in/from the database 180. In implementations, the processing system may include a CPU and a memory providing the database 180.

[0027] In some embodiments, the database 180 may store the compensation information. The term “compensation information” may be understood as specific information generated for one or more mask arrangements and indicative of a deformation of the one or more mask arrangements, particularly when the one or more mask arrangements are held in a predetermined orientation at a holding arrangement, and/or under predetermined external influences. The compensation information can include information about a deformation of the mask arrangement as compared to a target state of the mask arrangement, specifically expressed as local shifts of specific areas of the mask arrangement as compared to target positions of these areas. Particularly, in a 2D-coordinate system defined by the plane of the main surface of the mask arrangement, the compensation information may include information about local shifts of specific areas of the mask arrangement in an y-direction and/or in an x-direction of the ID- coordinate system.

[0028] The compensation information can be determined previously, i.e. before the mask arrangement is used for masking a substrate in the processing chamber, specifically by optically inspecting the mask arrangement. Specifically, the compensation information can be determined outside the processing chamber, e.g. in a mask test stand (“MTS”) or in a mask inspection chamber of the processing system. Optionally, the compensation information can be determined once for the mask arrangement, e.g. before the initial use of the mask arrangement in the processing chamber. For example, the compensation information can be determined by holding the mask arrangement in a predetermined orientation at a holding arrangement, e.g. at the mask carrier 105, and by inspecting positions of specific areas of the mask arrangement in relation to reference positions that indicate the target positions of these specific areas.

[0029] Optionally, the compensation information for the mask arrangement can be periodically determined or can be periodically checked and updated, or replaced by more recent or more accurate compensation information. For example, the mask arrangement may be periodically inspected at a mask test stand, and compensation information stored for the mask arrangement may be periodically updated, if appropriate.

[0030] In some embodiments, the compensation information may include a set of shift values for the mask arrangement. In particular, the set of shift values includes a shift value for some or for all adjustment elements of the plurality of adjustment elements. A “set of shift values” may be understood as a set of input values (e.g. voltages) for the plurality of adjustment elements that causes the adjustment elements to apply forces to the mask arrangement that reduce or even eliminate a deformation of the mask arrangement.

[0031] In some embodiments, which can be combined with other embodiments described herein, determining the compensation information for the mask arrangement may include inspecting the mask arrangement, e.g. in a MTS, for determining a deformation of the mask arrangement and controlling the plurality of adjustment elements of the holding arrangement until the deformation is reduced or eliminated (referred to herein as an “undeformed state” of the mask arrangement). The input values (expressed as any of voltages, currents, forces, positions, distances) applied to the plurality of adjustment elements in the undeformed target state of the mask arrangement may be stored in the database as a “set of shift values”.

[0032] As indicated above, the shift values may be voltage or current values that are to be applied as input values to the plurality of adjustment elements for obtaining the undeformed state of the mask arrangement, or the shift values may be distance values, position values or force values by which the mask arrangement is to be shifted or that are to be exerted by the adjustment elements on the mask arrangement to reduce or eliminate the deformation of the mask arrangement. The parameters that are stored as the shift values may depend on the actuator types of the adjustment elements. For example, if the adjustment elements 125 are piezoelectric actuators, the shift values may be voltage values.

[0033] In some embodiments, the set of shift values may include a number of values corresponding to the number of adjustment elements at the holding arrangement 101. In other words, every shift value may be allocated to one specific adjustment element of the holding arrangement.

[0034] According to some embodiments, a compensation information for a plurality of mask arrangements may be stored in the database. In particular, one set of shift values for each mask arrangement of a plurality of mask arrangements may be stored in the database. In other words, the database may be configured to store one set of shift values for each mask arrangement of a plurality of mask arrangements, e.g. for the plurality of mask arrangements that are to be used in a vacuum deposition system. For example, compensation information for ten or more, particularly thirty or more mask arrangements may be stored in the database. In particular, ten or more, particularly thirty or more sets of shift values may be stored in the database, e.g. in a table-format. Each set of shift values may include one or more, particularly three or more, more particularly six or more shift values.

[0035] Notably, the sets of shift values stored for different mask arrangements are typically different because each mask arrangement may be characterized by specific individual material tensions in the mask frame and mask sheet and/or by slight deviations from a target state due to manufacturing tolerances. Accordingly, it is reasonable to inspect each mask arrangement individually for storing respective individual compensation information for each mask arrangement. Each mask arrangement may be inspected once, before the mask arrangement is used in the processing chamber, or alternatively each mask arrangement may be periodically inspected for updating or checking the compensation information.

[0036] Optionally, the compensation information for the plurality of mask arrangements may be stored in the form of a table, e.g. a look-up table. For example, each column or each line of the table may include shift values for one specific mask arrangement of the plurality of mask arrangements.

[0037] The processing system 100 according to embodiments described herein further includes a controller 170. The controller 170 is configured to retrieve compensation information for the mask arrangement 110 from the database 180 and to control the plurality of adjustment elements 125 based on the retrieved compensation information to reduce the deformation of the mask arrangement 110.

[0038] A first data connection 182 may be provided for connecting the controller 170 to the database 180. The first data connection may be a wireless data connection or a cable connection. The controller 170 may be connected to the plurality of adjustment elements 125, particularly via a second data connection 172. For example, the controller may be connected wirelessly to the plurality of adjustment elements 125. The controller may be configured to retrieve data from the database 180 and to control the plurality of adjustment elements 125 based on data retrieved from the database 180. The data may include the compensation information for the mask arrangement 110. Specifically, the controller may retrieve the compensation information for the mask arrangement 110 from the database 180, and may control the plurality of adjustment elements 125 by applying respective shift values contained in the compensation information or calculated based on the compensation information to the plurality of adjustment elements. Accordingly, the controller may adjust each of the plurality of adjustment elements according to the respective shift value. As a result, the plurality of adjustment elements exert forces on the mask arrangement 110 for reducing or for eliminating a deformation of the mask arrangement.

[0039] According to some embodiments, that can be combined with any other embodiment described herein, the processing system may include a plurality of holding arrangements, particularly a plurality of mask carriers, each mask carrier configured to carry at least one mask arrangement. The plurality of mask arrangements may be transported into two or more vacuum processing chambers of the processing system by the holding arrangements to allow for the processing of two or more substrates at the same time. The plurality of holding arrangements may each carry a mask arrangement, such that a plurality of mask arrangements can be provided in the processing system.

[0040] In some embodiments, the plurality of mask arrangements includes labels for distinguishing the mask arrangements from one another. The labels may include scannable labels, for example selected from the group consisting of a linear barcode, a 2D-barcode, and a QR code. The labels can be optically read, e.g. by a camera or a laser. In order to reduce or eliminate a deformation of a specific mask arrangement of the plurality of mask arrangements provided in the processing system, the label of the specific mask arrangement can be scanned for identifying the specific mask arrangement, and the compensation information stored for the identified mask arrangement may be retrieved by the controller for controlling the plurality of adjustment elements based thereon. The labels may be engraved in the mask arrangements, particularly in the respective mask frames, or may be otherwise attached to or provided at the mask arrangements.

[0041] FIG. 1 schematically shows a label 601 provided on the mask arrangement 110, e.g. on the mask frame of the mask arrangement 110. The processing system 100 may include a scanning device 602, e.g. a camera device or a laser, configured to scan the label 601 for identifying the mask arrangement 110 among the plurality of mask arrangements. In particular, the scanning device 602 may be configured to scan the label 601 of the mask arrangement for identifying the mask arrangement from among the plurality of mask arrangement, and the controller 170 may be configured to retrieve compensation information about the identified mask arrangement 110 from among compensation information stored for the plurality of mask arrangements.

[0042] According to some embodiments, the mask arrangement 110 supported by the holding arrangement may be oriented in a substantially vertical orientation in the processing chamber. The processing system may further include a transport device for transporting the mask arrangement in an essentially vertical orientation into and out of the processing chamber. The holding arrangement may include the plurality of adjustment elements 125 above and/or below the mask frame at the mask carrier 105. The plurality of adjustment elements 125 may be arranged such that forces, e.g. vertical forces, can be applied to the mask frame of the mask arrangement, e.g. for compensating a sagging of a center region of the mask arrangement due to gravity. [0043] According to some embodiments, which can be combined with other embodiments described herein, the compensation information for the mask arrangement is determined by inspecting the mask arrangement outside the processing chamber, particularly in a mask test stand or in a mask inspection chamber. The mask test stand (“MTS”) may include an inspection device for inspecting the mask arrangement. In particular, a deformation of the mask arrangement can be detected by inspecting the mask arrangement. The inspection device may be configured to determine the compensation information for the mask arrangement. In particular, the inspection device may be configured to determine the set of shift values for the adjustment elements of the inspected mask arrangement. The inspection device may be a camera system, a laser system or the like. According to some embodiments, the determined compensation information may be stored in the database 180 for later use.

[0044] The mask test stand may further include a controller for controlling the plurality of adjustment elements of the holding arrangement, and a scanning device for scanning the label of the mask arrangement for identifying the mask arrangement.

[0045] Once the compensation information for the mask arrangement is stored in the database, the controller may automatically retrieve the compensation information from the database and may automatically compensate any deformation of the mask arrangement based on the compensation information before carrying out an alignment of a substrate relative to the mask arrangement in the processing chamber. Accordingly, the process of mask adjustment and alignment in the processing chamber can be accelerated and automatized. For example, after a cleaning of the mask arrangement that is conducted on a regular basis typically under atmosphere outside the vacuum chambers of the processing system, the mask arrangement can be automatically re-adjusted based on the stored compensation information.

[0046] According to some embodiments, the processing system may include one or more vacuum processing chambers adapted for layer deposition therein. The vacuum processing chambers may include a respective deposition source for depositing material on a substrate through a mask arrangement. The processing chamber may be adapted for a deposition process, such as a thermal evaporation process, a PVD process, a CVD process, a sputter process, etc. A substrate may be located within the processing chamber behind the mask arrangement, e.g. in an essentially vertical orientation. The deposition source may be provided in the processing chamber facing a side of the substrate to be coated. The deposition source may provide the material to be deposited on the substrate. [0047] The deposition source may be an evaporation source in some embodiments. The evaporation source may be movable past the mask arrangement and past the substrate during the deposition. Optionally, one or more distribution pipes of the evaporation source may be rotatable.

[0048] According to some embodiments, the deposition material may be chosen according to the deposition process and the later application of the coated substrate. As an example, the deposition material can be an organic material used in the manufacturing of OLEDs. For instance, the deposition material of the deposition source may be a material including small molecules, polymers, and phosphorescent materials. As an example, the deposition material can be selected from the group including: chelates (e.g., Alq3), fluorescent and phosphorescent dyes (e.g., perylene, rubrene, quinacridone derivatives, etc) and conjugated dendrimers.

[0049] The embodiments described herein can be utilized for evaporation on large area substrates. According to some embodiments, large area substrates may have a size of at least 0.67 m² The substrate size can be from about 0.67 m² (0.73x0.92m - GEN 4.5) to about 8 m² or more, particularly from about 2 m² to about 9 m² or even up to 12 m². The mask arrangement typically has an area larger than the area of the substrate, such that the whole substrate is covered by the mask arrangement during deposition.

[0050] According to some embodiments, the holding arrangement 101 may include a plurality of adjustment elements 125, particularly piezo actuators. The plurality of adjustment elements may be arranged at a plurality of positions above and below the mask arrangement 110 when the mask arrangement is held at the holding arrangement 101, such that the plurality of adjustment elements may exert forces on the mask arrangement, e.g. when the mask arrangement is arranged in the processing chamber or when the mask arrangement is arranged in the mask test stand. The plurality of adjustment elements 125 may be provided at the mask carrier 105, and may thus be movable together with the mask carrier 105 through the vacuum processing system. Alternatively, the plurality of adjustment elements 125 may be fixedly provided in the processing chamber and/or may be fixedly provided at the mask test stand, particularly at a mask carrier holder that is configured to hold the mask carrier in a vertical orientation in the processing chamber or at the mask test stand.

[0051] According to some embodiments, the holding arrangement 101 may include between one and ten adjustment elements, particularly from three to nine adjustment elements, more particularly about six adjustment elements. The plurality of adjustment elements may be distributed around the mask frame, e.g. above and below the mask frame and/or laterally with respect to the mask frame. An equal number of adjustment elements may be arranged at the top and at the bottom of the mask frame. For example, three adjustment elements may be arranged above the mask frame and three adjustment elements may be arranged below the mask frame.

[0052] By providing a plurality of adjustment elements along a periphery of the mask frame, forces can be individually applied to a top bar and to a bottom bar of the mask frame of the mask frame, and the deformation of the mask frame can be precisely compensated. Optionally, further adjustment elements may be provided to apply forces to the lateral side bars of the mask frame. Some of the plurality of adjustment elements may be configured to exert a pulling force to the mask frame, and/or some of the plurality of adjustment elements may be configured to exert a pushing force to the mask frame. By pulling and/or pushing the bars of the mask frame, respectively, a target mask frame shape can be restored via the adjustment elements.

[0053] FIG. 2 shows a mask arrangement 310 in an essentially vertical orientation (indicated by arrow 40). As an example, gravity may affect the shape of the mask arrangement 310, e.g. in the vertical direction (indicated by reference numeral 62) and lead to a deformation or bending of at least a part of the mask frame 330 and/or the mask sheet 340. In particular, a top frame element 334 and a bottom frame element 335 of the mask frame, i.e. horizontally oriented mask frame elements, may be affected by gravity. For example, a vertical deformation in a center region of the mask arrangement may be 2.5 microns or more while a mask positioning precision is typically about 2 microns or smaller. The mask sheet 340 can be deformed due to the connection of the mask sheet 340 to the mask frame 330. The deformation in turn leads to an at least local misalignment of the openings in the mask sheet 340 with respect to the substrate, and a quality of the deposited material is deteriorated.

[0054] FIG. 3 schematically shows an adjustment of a mask arrangement with an adjustment element 125 according to method described herein. The adjustment element 125 may include at least one of a motor, a stepper motor, a linear motor, a linear actuator, a piezoelectric actuator, an adjustment screw, an elastic element, and a spring. A linear actuator 423 of the adjustment element 125 may be provided at the holding arrangement 101, e.g. at the mask carrier 105, and may be configured to apply a force on the mask frame 130 of the mask arrangement, e.g. in a vertical direction.

[0055] According to some embodiments, which can be combined with other embodiments described herein, the adjustment element 125 may include a linear actuator 423, e.g. a piezoelectric actuator. In the example illustrated in FIG. 3, the linear actuator 423 of the adjustment element 125 is fixed at the holding arrangement 101, particularly at a carrier frame 120 of the mask carrier 105. The linear actuator 423 may be configured to exert a force on the mask frame 130, particularly on a bracket 424 that is fixed at the mask frame 130, e.g. at an upper or a lower bar of the mask frame. Particularly, the mask frame 130 can be pushed upwardly by the linear actuator 423, e.g. to compensate gravity-caused sagging. Alternatively or additionally, the mask frame 130 can be pushed or pulled downwardly by the actuator. By varying or changing an extension length of the linear actuator 423, the force applied to the mask carrier can be varied or changed. The extension length of the linear actuator 423 can be changed via the controller.

[0056] FIG. 4 is a flow diagram that illustrates such a method of adjusting a mask arrangement for masking a substrate in a processing chamber according to embodiments described herein. The method includes, in box 514, applying forces to the mask arrangement for reducing a deformation of the mask arrangement based on compensation information previously determined for the mask arrangement and stored in a database. The forces may be applied to the mask arrangement with a plurality of adjustment elements, particularly with a plurality of piezoelectric actuators. The forces may be applied to a mask frame of the mask arrangement such that a deformation of the mask frame is reduced or eliminated.

[0057] The compensation information is determined previously by inspecting the mask arrangement. This is schematically illustrated by box 501 of FIG. 4. The inspection may take place in a mask inspection chamber or in a mask test stand (“MTS”) of the processing system. The previously determined compensation information is stored in a database and can be retrieved from the database for later use. In some embodiments, the inspection of the mask arrangement in box 501 takes place once for the mask arrangement before the mask arrangement is used in a vacuum processing chamber for masking a substrate. Once the mask arrangement is inspected and the respective compensation information is stored in the database, deformations of the mask arrangement can be reduced by applying forces on the mask arrangement in accordance with the stored compensation information. Accordingly, deformation reduction can be accelerated since it is not necessary to repeatedly inspect the mask arrangement for determining a deformation, e.g. after every cleaning cycle. Rather, once the compensation information is stored, a renewed inspection of the mask arrangement for reducing a deformation may not be necessary. [0058] After the application of the forces to the mask arrangement in box 514, the mask arrangement may be provided in an undeformed state. Accordingly, in box 515, a substrate can be aligned relative to the undeformed mask arrangement, whereupon the openings of the mask arrangement are provided exactly in front of correct substrate positions over the whole area of the mask arrangement.

[0059] After the alignment in box 515, a material can be deposited on the substrate through the openings of the mask arrangement, e.g. by evaporation. For example, a plurality of pixels can be deposited on the substrate.

[0060] A method according to embodiments described herein may be conducted as follows: In optional box 511, a mask arrangement may be transported into a vacuum processing chamber of a vacuum deposition system, particularly while the mask arrangement is provided in an essentially vertical orientation. The mask arrangement may be held at a holding arrangement, particularly at a mask carrier, wherein the holding arrangement may include a plurality of adjustment elements.

[0061] In box 512, the mask arrangement may be identified among a plurality of mask arrangements by scanning a label that is provided at the mask arrangement, e.g. by a scanning device such as a camera or a laser. The label may be engraved in a frame of the mask arrangement.

[0062] In box 513, the compensation information for the identified mask arrangement may be retrieved from the database. For example, compensation information for a plurality of mask arrangements may be stored in the database in the form of a table, each line or each column of the table including the compensation information for one specific mask arrangement as previously determined by the inspection in box 501. Through the label scan, the current mask arrangement can be identified and the compensation information contained in the respective column or line of the table can be retrieved.

[0063] In box 514, the plurality of adjustment elements can be controlled based on the retrieved compensation information. In particular, the compensation information may include a set of shift values for the mask arrangement, particularly one shift value for each adjustment element. When the shift values (being, for example, voltages that are to be applied to the adjustment elements) are applied to the plurality of adjustment elements, the deformation of the mask arrangement is reduced or eliminated. [0064] It is to be noted that boxes 512, 513, and 514 may also be carried out before the mask arrangement is transported into the processing chamber (i.e. before box 511). For example, boxes 512, 513, and 514 may be carried out in a mask test stand for compensating a deformation of the mask arrangement based on the previously stored compensation values, whereupon the compensated mask arrangement may be transported into the processing chamber for alignment relative to the substrate.

[0065] In box 515, a substrate may be aligned with the compensated mask arrangement in the processing chamber, and, in box 516, deposition on the substrate may take place.

[0066] According to some embodiments described herein, the method may further include mounting the mask arrangement to the holding arrangement. If the holding arrangement includes a mask carrier for carrying the mask arrangement, the mounting may include an integration of the mask arrangement with the mask carrier.

[0067] In the following, the inspection of the mask arrangement in box 501 will be described in further detail:

[0068] Inspection may take place at a mask test stand or a mask test station, e.g. in a mask inspection vacuum chamber or in a mask test stand of the processing system. At the mask test stand, the mask arrangement may be held at a holding arrangement that includes a plurality of adjustment elements, particularly at a mask carrier. The mask arrangement may be held at the mask test stand in a predetermined orientation that corresponds to the orientation of the mask arrangement in the processing chamber, particularly an essentially vertical orientation. Optionally, one or more conditions in the mask test stand (e.g. the temperature, the pressure, the mounting of the mask arrangement) may correspond to the respective one or more conditions when using the mask arrangement for deposition in the processing chamber.

[0069] The mask arrangement may be identified via a scanning of the label.

[0070] The mask arrangement may be inspected. The inspection of the mask arrangement may include checking the positions of specific areas of the mask arrangement, e.g., of the mask frame and the mask sheet, with an optical inspection device, e.g. a camera. These positions may be compared to respective target positions for determining a deviation therefrom. The plurality of adjustment elements may be controlled to apply forces to the mask frame of the mask arrangement until deformations, if any, are reduced or eliminated. Respective control values of the plurality of adjustment elements may be stored as a set of shift values. [0071] According to some embodiments, inspecting the mask arrangement may include determining the compensation information and storing the compensation information in the database. Inspecting the mask arrangement may specifically include determining a set of shift values for the plurality of adjustment elements. The compensation information may include the set of shift values for the mask arrangement including a shift value for some or all adjustment elements of the plurality of adjustment elements.

[0072] The compensation information may be allocated to the label that is provided on the mask arrangement and that serves for identifying the mask arrangement among the plurality of mask arrangements. Particularly, the compensation information for the mask arrangement may be stored in the database together with the label of the mask arrangement or together with an allocation information derivable from the label. Accordingly, the correct compensation information of the mask arrangement can be retrieved later from the database by scanning the label of the mask arrangement and by retrieving the compensation information allocated to the label.

[0073] According to some embodiments described herein, a plurality of mask arrangements may be inspected in box 501. Inspecting may include determining the compensation information for each mask arrangement of the plurality of mask arrangements indicative of the deformation of the respective mask arrangement, and storing the compensation information for each mask arrangement in the database. In particular, a set of shift values for each mask arrangement of the plurality of mask arrangements may be stored in the database. For example, the compensation information for the plurality of mask arrangements may be stored in the form of a table.

[0074] According to some embodiments, that can be combined with any other embodiment described herein, the deformation reduction of the mask arrangement in box 514 can be carried out automatically based on the compensation information stored in the database. Specifically, identifying the mask arrangement based on the label in box 512, retrieving the compensation information for the mask arrangement in box 513, and applying the forces to the mask arrangement based on the compensation information in box 514 may be conducted automatically, e.g. by the controller. Accordingly, when a previously inspected mask arrangement is to be adjusted, e.g. in the processing chamber or in the mask test stand, the controller may automatically compensate a deformation of the mask arrangement. [0075] Advantageously, by automatically adjusting the mask arrangement based on stored compensation information, a repeated inspection of the mask arrangement may not be necessary, or an interval between two inspections can be reduced, such that the overall throughput of the deposition system can be increased. An inspection of the mask arrangement after each mask cleaning process may not be necessary, since the deformation information of the mask arrangement is stored in the database and can be automatically retrieved.

[0076] According to some embodiments described herein, the compensation information stored in the database may be updated on a regular basis and/or may be replaced by more recently determined or more accurate compensation information. Accordingly, an inspection of the mask arrangement may be repeated in order to improve or update the stored compensation information. Updating the database and/or replacing by more recently determined or more accurate compensation information may provide the advantage of constantly improving the deformation compensation of the mask arrangement. Thus, for example, when the characteristics of the mask arrangement (e.g. material tensions in the mask frame) change over time, it may be reasonable to update the compensation information, in order to be able to continuously provide improved deposition results.

[0077] According to one aspect described herein, a computer-readable medium or storage is provided. The computer-readable medium or storage may store compensation information about a plurality of mask arrangements indicative of deformations of the plurality of mask arrangements, particularly wherein the compensation information comprises sets of shift values for controlling a plurality of adjustment elements for obtaining a deformation reduction of the plurality of mask arrangements.

[0078] While the foregoing is directed to embodiments of the disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

1. A method of adjusting a mask arrangement (110) for masking a substrate, the method comprising: applying forces to the mask arrangement for reducing a deformation of the mask arrangement based on compensation information previously determined for the mask arrangement and stored in a database (180).

2. The method according to claim 1, wherein the forces are applied to the mask arrangement with a plurality of adjustment elements (125), particularly with a plurality of piezoelectric actuators.

3. The method according to claim 2, wherein the compensation information comprises a set of shift values for the mask arrangement including a shift value for some or all adjustment elements (125) of the plurality of adjustment elements.

4. The method according to any of claims 1 to 3, wherein compensation information for a plurality of mask arrangements is stored in the database, in particular one set of shift values for each mask arrangement of the plurality of mask arrangements.

5. The method according to claim 4, wherein the plurality of mask arrangements comprise labels (601) for distinguishing the mask arrangements of the plurality of mask arrangements from one another, particularly wherein the labels can be scanned and are selected from the group consisting of a linear barcode, a 2D-barcode, and a QR code.

6. The method of claim 5, further comprising: identifying the mask arrangement among the plurality of mask arrangements by scanning the label of the mask arrangement; and retrieving from the database (180) the compensation information for the identified mask arrangement, whereupon the forces are applied to the mask arrangement based on the retrieved compensation information.

7. The method of any of claims 1 to 6, further comprising, before using the mask arrangement in a vacuum processing chamber: inspecting the mask arrangement for determining the compensation information for the mask arrangement, particularly by determining a deformation of the mask arrangement; and storing the compensation information in the database (180).

8. The method of claim 7, wherein the mask arrangement is inspected in a mask test stand or in a mask inspection chamber.

9. The method according to claim 7 or 8, comprising determining compensation information for each mask arrangement of a plurality of mask arrangements indicative of a deformation of the respective mask arrangement; and storing the compensation information for each mask arrangement in the database (180), particularly in a form of a table.

10. The method according to any of claims 7 to 9, wherein the compensation information stored in the database is updated on a regular basis and/or replaced by more recently determined or more accurate compensation information.

11. The method according to any of claims 1 to 10, wherein the mask arrangement is carried by a mask carrier (105) and comprises a mask frame (130) supporting a mask sheet (140), wherein the forces are applied to the mask frame.

12. The method according to any of claims 1 to 11, wherein the deformation of the mask arrangement comprises at least one or more of the group consisting of: a sagging due to gravity, a deformation of the mask arrangement caused by material tension, and a thermally caused deformation of the mask arrangement.

13. A method of inspecting a mask arrangement, including: holding the mask arrangement at a holding arrangement including a plurality of adjustment elements; determining compensation information for the mask arrangement, wherein the compensation information is indicative of a deformation of the mask arrangement; and storing the compensation information in a database.

14. A processing system, comprising: a holding arrangement (101) for holding a mask arrangement (110), the holding arrangement comprising a plurality of adjustment elements (125) configured to apply forces to the mask arrangement; a database (180) for storing compensation information determined for the mask arrangement; and a controller (170) configured to retrieve the compensation information for the mask arrangement from the database and to control the plurality of adjustment elements based on the retrieved compensation information to reduce a deformation of the mask arrangement.

15. The processing system according to claim 14, further comprising a scanning device (602) configured to scan a label (601) of the mask arrangement for identifying the mask arrangement from among a plurality of mask arrangements, the controller (170) configured to retrieve compensation information for the identified mask arrangement from among compensation information stored for the plurality of mask arrangements.

16. A computer-readable medium or storage storing compensation information about a plurality of mask arrangements indicative of deformations of the plurality of mask arrangements, particularly wherein the compensation information comprises sets of shift values for controlling a plurality of adjustment elements for obtaining a deformation reduction of the plurality of mask arrangements.