Patent Abstract:
A method for controlling the deposition of an organic layer in making an organic light-emitting device includes depositing at a deposition zone organic material forming a layer of the organic light-emitting device and providing a movable sensor which, when moved into the deposition zone and is being coated during the depositing step, provides a signal representing the deposition rate and thickness of the organic material forming the layer. The method also includes controlling the deposition of the organic material in response to the signal to control the deposition rate and thickness of the deposited organic material forming the layer, moving the movable sensor from the deposition zone to a cleaning position, and removing organic material from the movable sensor to permit reuse of the movable sensor.

Full Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    Reference is made to commonly assigned U.S. patent application Ser. No. 09/839,886 filed Apr. 20, 2001 entitled “Controlling the Thickness of an Organic Layer in an Organic Light-Emitting Device” by Steven A. Van Slyke et al. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates generally to monitoring and controlling formation of organic layers by physical vapor deposition in making organic light-emitting devices.  
         BACKGROUND OF THE INVENTION  
         [0003]    An organic light-emitting device, also referred to as an organic electroluminescent device, can be constructed by sandwiching two or more organic layers between first and second electrodes.  
           [0004]    In a passive matrix organic light-emitting device of conventional construction, a plurality of laterally spaced light-transmissive anodes, for example indium-tin-oxide (ITO) anodes are formed as first electrodes on a light-transmissive substrate such as, for example, a glass substrate. Two or more organic layers are then formed successively by vapor deposition of respective organic materials from respective sources, within a chamber held at reduced pressure, typically less than 10 −3  Torr. A plurality of laterally spaced cathodes are deposited as second electrodes over an uppermost one of the organic layers. The cathodes are oriented at an angle, typically at a right angle, with respect to the anodes.  
           [0005]    Such conventional passive matrix organic light-emitting devices are operated by applying an electrical potential (also referred to as a drive voltage) between appropriate columns (anodes) and, sequentially, each row (cathode). When a cathode is biased negatively with respect to an anode, light is emitted from a pixel defined by an overlap area of the cathode and the anode, and emitted light reaches an observer through the anode and the substrate.  
           [0006]    In an active matrix organic light-emitting device, an array of anodes are provided as first electrodes by thin-film transistors (TFTs) which are connected to a respective light-transmissive portion. Two or more organic layers are formed successively by vapor deposition in a manner substantially equivalent to the construction of the aforementioned passive matrix device. A common cathode is deposited as a second electrode over an uppermost one of the organic layers. The construction and function of an active matrix organic light-emitting device is described in U.S. Pat. No. 5,550,066, the disclosure of which is herein incorporated by reference.  
           [0007]    Organic materials, thicknesses of vapor-deposited organic layers, and layer configurations, useful in constructing an organic light-emitting device, are described, for example, in U.S. Pat. Nos. 4,356,429; 4,539,507; 4,720,432; and 4,769,292, the disclosures of which are herein incorporated by reference.  
           [0008]    In order to provide an organic light-emitting device which is substantially uniform and of precise thickness, the formation of organic layers of the device has to be monitored or controlled. Such control of vapor deposition of organic layers by sublimation or evaporation of organic material from a source is typically achieved by positioning a monitor device within the same vapor deposition zone in which the substrate or structure is to be coated with the organic layer. Thus, the monitor device receives an organic layer at the same time as the organic layer is being formed on the substrate or structure. The monitor device, in turn, provides an electrical signal which is responsive to a rate at which the organic layer is being formed on the monitor device and, therefore, related to a rate at which the organic layer is being formed on the substrate or structure which will provide the organic light-emitting device. The electrical signal of the monitor device is processed and/or amplified, and is used to control the rate of vapor deposition and the thickness of the organic layer being formed on the device substrate or structure by adjusting a vapor source temperature control element, such as, for example, a source heater.  
           [0009]    Well known monitor devices are so-called crystal mass-sensor devices in which the monitor is a quartz crystal having two opposing electrodes. The crystal is part of an oscillator circuit provided in a deposition rate monitor. Within an acceptable range, a frequency of oscillation of the oscillator circuit is approximately inversely proportional to a mass-loading on a surface of the crystal occasioned by a layer or by multiple layers of material deposited on the crystal. When the acceptable range of mass-loading of the crystal is exceeded, for example by build-up of an excess number of deposited layers, the oscillator circuit can no longer function reliably, necessitating replacement of the “overloaded” crystal with a new crystal mass-sensor. Such replacement, in turn, requires discontinuation of the vapor deposition process.  
           [0010]    In addition, when certain types of organic layers are deposited onto crystal mass-sensor devices there can be a tendency for the layers to start cracking and flaking from the mass-sensor surface after coating thickness build-up on the order of 500-2,000 nanometer (nm). This can cause the crystal mass-sensor to become inaccurate in its coating rate measurement capability at thicknesses well below the aforementioned mass-loading limit.  
           [0011]    In development efforts, several organic light-emitting devices can typically be prepared before a crystal mass-sensor must be replaced due to excessive mass-loading or cracking and flacking of a deposited film.. This does not present a problem in such efforts, since other considerations usually require disruption of vapor deposition by opening the deposition chamber for manual replacement of substrates or structures, replenishment of organic material in relatively small vapor sources, and the like.  
           [0012]    However, in a manufacturing environment, designed for repeatedly making a relatively large number of organic light-emitting devices, replacement of “overloaded” crystal mass-sensors or cracked and flaking organic coatings on crystal mass-sensors would constitute a serious limitation because a manufacturing system is configured in all aspects to provide the capacity of producing all organic layers on numerous device structures and, indeed, to produce fully encapsulated organic light-emitting devices.  
         SUMMARY OF THE INVENTION  
         [0013]    It is, therefore, an object of the present invention to form an organic layer by providing a reusable sensor for controlling the thickness of such layer. This object is achieved in a method for depositing an evaporated or sublimed organic layer onto a structure which will form part of an organic light-emitting device, comprising the steps of:  
           [0014]    a) depositing at a deposition zone organic material forming a layer of the organic light-emitting device;  
           [0015]    b) providing a movable sensor which, when moved into the deposition zone and is being coated during the depositing step, provides a signal representing the thickness of the organic material forming the layer;  
           [0016]    c) controlling the deposition of the organic material in response to the signal to control a deposition rate and thickness of the organic layer formed on the structure;  
           [0017]    d) moving the movable sensor from the deposition zone to a cleaning position; and  
           [0018]    e) removing organic material from the movable sensor to permit reuse of the movable sensor.  
           [0019]    It is an advantage of the present invention that crystal mass-sensors which control the thickness of one or more organic layers in a light-emitting device can be cleaned and reused thereby providing a more efficient manufacturing process. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]    [0020]FIG. 1 is a schematic perspective view of a passive matrix organic light-emitting device having partially peeled-back elements to reveal various layers;  
         [0021]    [0021]FIG. 2 is a schematic perspective view of a manufacturing system suitable for manufacture of a relatively large number of organic light-emitting devices (OLEDs) and having a plurality of stations extending from hubs;  
         [0022]    [0022]FIG. 3 is a schematic section view of a carrier containing a relatively large number of substrates or structures, and positioned in a load station of the system of FIG. 2 as indicated by section lines  3 - 3  in FIG. 2;  
         [0023]    [0023]FIG. 4 is a schematic section view of a vapor deposition station dedicated to forming vapor deposited organic hole-transporting layers (HTL) on a substrate or structure in the system of FIG. 2 as indicated by section lines  4 - 4  in FIG. 2;  
         [0024]    [0024]FIG. 5 is an enlarged schematic section view of a crystal mass-sensor shown in FIG. 4 and associated deposition rate monitor;  
         [0025]    [0025]FIG. 6 shows schematically the sensor of FIG. 4 having formed on one surface a relatively high mass-loading in the form of a number N of layers of organic hole-transporting material wherein such mass-loading of a prior art sensor would cause the associated deposition rate monitor to become unreliable in its reading of deposition rate, or to become inoperative;  
         [0026]    [0026]FIG. 7 shows schematically, positioned within the HTL deposition station of FIG. 2, a movable sensor assembly in accordance with the invention in which a first crystal mass-sensor is operative in a deposition zone while a third sensor is shown positioned proximate a light guide for providing a cleaning flash, with a second sensor depicted after cleaning and in a position to advance into the deposition zone as the first sensor accumulates a relatively high mass-loading;  
         [0027]    [0027]FIG. 7A shows the light guide of FIG. 7 which further includes an optional heater positioned adjacent the tip of the light guide and an optional trap for collecting organic material removed from the sensor by a cleaning flash;  
         [0028]    [0028]FIG. 7B shows schematically the light guide directed obliquely towards the mass-loaded sensor and an optional trap for collecting organic material removed from the sensor by a cleaning flash;  
         [0029]    [0029]FIG. 7C shows schematically an alternative optical cleaning configuration for removing organic material from a sensor in which a cleaning radiation source provides cleaning radiation directed towards a mass-loaded sensor via lenses, a window positioned in the chamber housing, and an optionally heatable mirror;  
         [0030]    [0030]FIG. 8 is a view of the movable sensor assembly of FIG. 7 but showing schematically a heater for cleaning the sensor having the high mass-loading in accordance with the invention;  
         [0031]    FIGS.  9 A- 9 D are schematic plan views of different embodiments of rotatable sensor supports useful in the practice of the invention, with positions of sensors in the deposition zone and sensor cleaning positions indicated in dashed outlines; and  
         [0032]    [0032]FIG. 10 is an enlarged section view of the crystal mass-sensor shown in FIG. 5, but having a radiation-absorbing layer preformed over the sensor surface for enhancing removal in whole or in part of the organic layers on the sensor in the cleaning position, in accordance with the invention.  
         [0033]    The drawings are necessarily of a schematic nature since layer thickness dimensions of OLEDs are frequently in the sub-micrometer ranges, while features representing lateral device dimensions can be in a range of 50-500 millimeter. Accordingly, the drawings are scaled for ease of visualization rather than for dimensional accuracy.  
         [0034]    The term “substrate” denotes a light-transmissive support having a plurality of laterally spaced first electrodes (anodes) preformed thereon, such substrate being a precursor of a passive matrix OLED. The term “structure” is used to describe the substrate once it has received a portion of a vapor deposited organic layer, and to denote an active matrix array as a distinction over a passive matrix precursor. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0035]    Turning to FIG. 1, a schematic perspective view of a passive matrix organic light-emitting device (OLED)  10  is shown having partially peeled-back elements to reveal various layers.  
         [0036]    A light-transmissive substrate  11  has formed thereon a plurality of laterally spaced first electrodes  12  (also referred to as anodes). An organic hole-transporting layer (HTL)  13 , an organic light-emitting layer (LEL)  14 , and an organic electron-transporting layer (ETL)  15  are formed in sequence by a physical vapor deposition, as will be described in more detail hereinafter. A plurality of laterally spaced second electrodes  16  (also referred to as cathodes) are formed over the organic electron-transporting layer  15 , and in a direction substantially perpendicular to the first electrodes  12 . An encapsulation or cover  18  seals environmentally sensitive portions of the structure, thereby providing a completed OLED  10 .  
         [0037]    Turning to FIG. 2, a schematic perspective view of a manufacturing system  100  is shown which is suitable for manufacture of a relatively large number of organic light-emitting devices using automated or robotic means (not shown) for transporting or transferring substrates or structures among a plurality of stations extending from a buffer hub  102  and from a transfer hub  104 . A vacuum pump  106  via a pumping port  107  provides reduced pressure within the hubs  102 ,  104 , and within each of the stations extending from these hubs. A pressure gauge  108  indicates the reduced pressure within the system  100 . The pressure can be in a range from about 10 −2  to 10 −6  Torr.  
         [0038]    The stations include a load station  110  for providing a load of substrates or structures, a vapor deposition station  130  dedicated to forming organic hole-transporting layers (HTL), a vapor deposition station  140  dedicated to forming organic light-emitting layers (LEL), a vapor deposition station  150  dedicated to forming organic electron-transporting layers (ETL), a vapor deposition station  160  dedicated to forming the plurality of second electrodes (cathodes), an unload station  103  for transferring structures from the buffer hub  102  to the transfer hub  104  which, in turn, provides a storage station  170 , and an encapsulation station  180  connected to the hub  104  via a connector port  105 . Each of these stations has an open port extending into the hubs  102  and  104 , respectively, and each station has a vacuum-sealed access port (not shown) to provide access to a station for cleaning, replenishing materials, and for replacement or repair of parts. Each station includes a housing which defines a chamber.  
         [0039]    [0039]FIG. 3 is a schematic section view of the load station  110 , taken along section lines  3 - 3  of FIG. 2. The load station  110  has a housing  110 H which defines a chamber  110 C. Within the chamber is positioned a carrier  111  designed to carry a plurality of substrates  11  having preformed first electrodes  12  (see FIG. 1). An alternative carrier  111  can be provided for supporting a plurality of active matrix structures. Carriers  111  can also be provided in the unload station  103  and in the storage station  170 .  
         [0040]    Turning to FIG. 4, a schematic cross section view of the HTL vapor deposition station  130  is shown, taken along the section lines  4 - 4  of FIG. 2. A housing  130 H defines a chamber  130 C. A substrate  11  (see FIG. 1) is held in a holder  131  which can be constructed as a mask frame. A source  134  is positioned on a thermally insulative support  132 , the source  134  filled with a supply of organic hole-transporting material  13   a  to a level  13   b.  The source  134  is heated by heating elements  135  which are connected via leads  245  and  247  to corresponding output terminals  244  and  246  of a source power supply  240 .  
         [0041]    When a source temperature is sufficiently elevated, the organic hole-transporting material  13   a  will evaporate or sublime and thus provide a deposition zone  13   v  of vapor of organic hole-transporting material, indicated schematically by dashed lines and arrows.  
         [0042]    The substrate  11  as well as a conventional crystal mass-sensor  200  are positioned within the deposition zone, and each of these elements has an organic hole-transporting layer being formed thereon as indicated by the designation  13   f,  shown in dashed outline.  
         [0043]    As is well known in the art, the crystal mass-sensor  200  is connected via a lead  210  to an input terminal  216  of a deposition rate monitor  220 . The sensor  200  is part of an oscillator circuit provided in the monitor  220  and the circuit oscillates at a frequency which is approximately inversely proportional to a mass-loading of the crystal such as by a mass-loading provided by the layer  13   f  being formed. The monitor  220  includes a differentiating circuit which generates a signal proportional to a rate of mass-loading, i.e. proportional to a rate of deposition of the layer  13   f.  This signal is indicated by the deposition rate monitor  220 , and is provided at an output terminal  222  thereof. A lead  224  connects this signal to an input terminal  226  of a controller or amplifier  230  which provides an output signal at an output terminal  232 . The latter output signal becomes an input signal to the source power supply  240  via lead  234  and input terminal  236 .  
         [0044]    Thus, if the vapor stream within the vapor deposition zone  13   v  is temporally stable, the mass build-up or growth of the layer  13   f  will proceed at a constant rate. The rate monitor  220  will provide a constant signal at output terminal  222 , and the source power supply  240  will provide a constant current to the heating elements  135  of the source  134  via the leads  245  and  247 , thereby maintaining the temporally stable vapor stream within the deposition zone. Under stable vapor deposition conditions, i.e. conditions of a constant deposition rate, a desired final thickness of an organic hole-transporting layer  13  (see FIG. 1) is achieved on the structure and on the crystal mass-sensor  200  during a fixed deposition duration, at which time the vapor deposition is terminated by terminating the heating of the source  134 , or by positioning a shutter (not shown) over the source.  
         [0045]    While a relatively simple source  134  is shown in FIG. 4 for illustrative purposes, it will be appreciated that numerous other source configurations can be effectively used to provide evaporated or sublimed vapors of organic materials within a deposition zone. Particularly useful sources are extended or linear physical vapor deposition sources disclosed by R. G. Spahn in U.S. patent application Ser. No. 09/518,600, filed Mar. 3, 2000, and commonly assigned.  
         [0046]    [0046]FIG. 5 is an enlarged schematic section view of the prior art crystal mass-sensor  200  shown in FIG. 4, together with the associated deposition rate monitor  220 . The crystal  204  has a front electrode  205  and a rear electrode  206 . An electrically grounded casing  202  is in electrical contact with the front electrode  205  and via a connection  209  to a shielded portion of the lead  210 . The oscillator-signal-carrying portion of lead  210  is connected to the rear electrode  206  by a connector  207 . Portions of the housing  130 H, the vapor deposition zone  13   v,  and the organic hole-transporting layer  13   f  being formed on the front electrode  205  and front portions of the casing  202  correspond to the respective elements of FIG. 4.  
         [0047]    Generally, the casing  202  of the crystal mass-sensor is water cooled (not shown in the drawings). The water cooling maintains a stable crystal temperature and ensures that the deposition monitoring is accurate and uninfluenced by thermal effects.  
         [0048]    [0048]FIG. 6 shows schematically the crystal mass-sensor  200  of FIG. 4 now having a relatively high mass-loading in the form of a number N of layers of organic hole-transporting material  13 . At such relatively high mass-loading (due to cumulative deposition of layers as N substrates or structures in succession received an organic hole-transporting layer  13 ) the deposition rate monitor  220  may become inoperative or become unreliable in its reading of a deposition rate.  
         [0049]    The monitor  220  may also become unreliable due to cracking, peeling or flaking of portions of the organic material deposited on the sensor at thicknesses lower than a thickness corresponding to N successive layers.  
         [0050]    Turning now to FIG. 7, there is shown one embodiment of a mass-sensor assembly  300  in accordance with the present invention, replacing the single fixedly positioned mass-sensor  200  shown in FIGS. 4, 5, and  6 .  
         [0051]    A rotatably movable sensor support  320  is depicted for illustrative purposes as supporting three crystal mass-sensors  301 ,  302 , and  303 . Sensor  301  is positioned and operative in the vapor deposition zone  13   v  (together with a substrate or structure as shown in FIG. 4) as described previously. A lead is connected to a rear electrode of each crystal (see FIG. 5) and a lead contact  323  (such as, for example, a spring-biased contact) engages a sensor contact  321  (of sensor  301 ) formed on the electrically insulative sensor support  320 .  
         [0052]    The sensor support  320  is rotatably disposed in the housing  130 H of the station  130  (see FIG. 2) via a seal  327 , and can be rotated by a rotator  325  in a manual mode as depicted here, or in an automated indexed rotation mode via a stepper motor or the like.  
         [0053]    While the sensor  301  is operative in the deposition zone, a sensor  303  is shown positioned proximate a light guide  392  which will provide from a cleaning flash unit  390  a flash of radiation sufficiently powerful to remove the multi-layer mass-loading  13  (xN) from this sensor  303  by heat-induced sublimation or evaporation, or to remove an organic deposit which may be partially cracked, peeled or flaked at reduced mass-loading. Such cleaning or removal of organic material from sensor  303  is effected by sublimation or evaporation in a manner substantially equivalent to formation of organic vapors in the vapor deposition zone  13   v  by sublimation or by evaporation of organic material  13   a  from the source  134 . The flash of radiation provided by cleaning flash unit  390  is of a magnitude sufficient to raise the temperature of the organic material deposited on the sensor to a temperature sufficient to initiate sublimation or evaporation of the organic material, but remain below the temperature required to remove the metal electrode on the sensor  303  or to adversely effect the performance of the sensor  303 . Organic materials useful for organic light emitting devices are particularly amenable to this technique because these materials are vaporized at temperatures significantly below the temperatures required to vaporize most inorganic materials such as the electrode materials commonly used for crystal mass sensors. Once the sensor  303  is cleaned, it can be then positioned in the deposition zone  13   v  and be utilized again for monitoring the deposition rate and thickness of the organic layer without opening the deposition chamber  130 C and thereby releasing the vacuum.  
         [0054]    A sensor  302  is shown after cleaning, and in a position on the sensor support to advance into the deposition zone as the sensor  301  accumulates an undesirably high mass-loading.  
         [0055]    A shield  329  is positioned to provide vapor deposition onto one sensor in the deposition zone, and to protect other sensors from vapor deposition.  
         [0056]    It will be appreciated that the light guide  392  is coupled through the housing  130 H via a vacuum-sealed feed-through (not shown). Similarly, all electrical leads enter or exit the chamber  130 C through the housing  130  via a corresponding electrical feed-through. Such feed-through elements are well known in the art of vacuum systems technology.  
         [0057]    The light guide  392  can be an optical fiber cable constructed of a material which transmits light provided by the cleaning flash unit  390 . Alternatively, the light guide  392  can be constructed as a hollow or tubular light-transmissive element.  
         [0058]    In FIG. 7A, the light guide  392  includes an optional heater  392 H positioned adjacent to the tip, or at the tip, of the light guide, and an optional trap  392 T. The purpose of the heater  392 H is to heat the optically active tip area of the light guide  392  so that organic sublimate (removed organic material) vaporized from the surface of the sensor  303  is prevented from depositing on the tip area of the light guide. The trap  392  is used to collect the sublimate and inhibit spreading of such sublimate throughout the chamber  130 C. The trap  392 T may be cooled to enhance condensation of the organic sublimate within the trap.  
         [0059]    [0059]FIG. 7B shows a light guide  392 B in a configuration which can direct light from the cleaning flash unit  390  under an oblique angle towards the mass-loaded sensor. The trap  392 T functions in a manner described with reference to FIG. 7A. The oblique incidence of a cleaning flash on the organic deposits on the mass-sensor  303  can obviate the need for a heater at the tip of the light guide  392 B.  
         [0060]    [0060]FIG. 7C shows schematically an alternative optical cleaning configuration for removing organic material from a mass-sensor. A cleaning radiation source  390 R provides cleaning radiation as a flash or as a timed beam of radiation (for example, a timed beam from a laser light source) which is directed towards the organic deposits on the mass-sensor  303  via a lens or lenses  392 L, a radiation-transmissive window  392 W in the housing  130 H, and a mirror  392 M which can be optionally heated by a heater  392 HM. The trap  392 T is operative as described above.  
         [0061]    Turning now to FIG. 8, there is shown the sensor assembly  300  of FIG. 7 in which the light guide  392  and the cleaning flash unit  390  is replaced by a heater  399  connected to a cleaning heater unit  395  via leads  396  and  398 . An optional trap equivalent in function to element  392 T in FIG. 7 can be included in the sensor assembly of FIG. 8 surrounding the heater  399  to collect the sublimate and inhibit sublimate spreading throughout the vacuum chamber.  
         [0062]    Optionally, the heater  399  can be incorporated into the casing  202  of the mass-sensor. In this case, it is desirable to not water cool the sensor casing at the cleaning position in which the sublimate of organic layers is removed.  
         [0063]    FIGS.  9 A- 9 D are schematic plan views of different embodiments of rotatable sensor supports which are useful in the practice of the invention. Positions of a sensor  301  in the deposition zone are indicated by the location of the shield  329 , shown in dashed outline, and sensor cleaning positions  392  (the light guide  392  of FIG. 7) are also depicted in dashed outline.  
         [0064]    [0064]FIG. 9A shows a mass-sensor assembly  300 A with a rotatable sensor support  320 A having a single sensor  301  supported thereon.  
         [0065]    [0065]FIG. 9B shows a mass-sensor assembly  300 B with two sensors  301 ,  302  disposed on a rotatable sensor support  320 B.  
         [0066]    [0066]FIG. 9C shows a mass-sensor assembly  300 C which provides a rotatable sensor support  320 C adapted to support four sensors  301 ,  302 ,  303 , and  304 .  
         [0067]    [0067]FIG. 9D depicts a mass-sensor assembly  300 D having a circular rotatable sensor support  320 D adapted to support an increased number of sensors, including a sensor  307 .  
         [0068]    [0068]FIG. 10 is an enlarged section view of the crystal mass-sensor shown in FIG. 5, but having a radiation-absorbing layer  391  preformed over the front electrode  205  of the crystal  204  and over front portions of the casing  202 . The radiation-absorbing layer  391  can be a layer of radiation-absorbing carbon or other radiation-absorbing material for enhancing removal in whole or in part of accumulated organic layers on a sensor disposed on a movable sensor support which can be moved from a position in the deposition zone  13   v  to a cleaning position for removal of organic material by a radiation flash (see FIG. 7), by a radiation exposure (see FIG. 7C) or by a heater (see FIG. 8).  
         [0069]    It will be appreciated that a sensor assembly having one or more sensors disposed on a movable sensor support can be effectively incorporated into each one of the vapor deposition stations  130 ,  140 , and  150  of the OLED manufacturing system  100  shown in FIG. 2. Thus, each of these stations can provide monitoring and control of a vapor deposition rate by a conventional mass-sensor and deposition rate monitor, and to provide a reusable sensor or reusable sensors by complete or partial removal of organic material from mass-loaded sensors in a cleaning position along a path of motion of a movable sensor support.  
         [0070]    The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.  
       Parts List  
       [0071]    [0071] 10  organic light-emitting device (OLED)  
         [0072]    [0072] 11  substrate or structure  
         [0073]    [0073] 12  first electrodes  
         [0074]    [0074] 13  organic hole-transporting layer (HTL)  
         [0075]    [0075] 13 (xN) number N of organic hole-transporting layers on mass-sensor  
         [0076]    [0076] 13   a  organic hole-transporting material  
         [0077]    [0077] 13   b  level of organic hole-transporting material  
         [0078]    [0078] 13   v  deposition zone of vapor of organic hole-transporting material  
         [0079]    [0079] 13   f  organic hole-transporting layer being formed  
         [0080]    [0080] 14  organic light-emitting layer (LEL)  
         [0081]    [0081] 15  organic electron-transporting layer (ETL)  
         [0082]    [0082] 16  second electrodes  
         [0083]    [0083] 18  encapsulation or cover  
         [0084]    [0084] 100  OLED manufacturing system  
         [0085]    [0085] 102  buffer hub  
         [0086]    [0086] 103  unload station  
         [0087]    [0087] 104  transfer hub  
         [0088]    [0088] 105  connector port  
         [0089]    [0089] 106  vacuum pump  
         [0090]    [0090] 107  pumping port  
         [0091]    [0091] 108  pressure gauge  
         [0092]    [0092] 110  load station  
         [0093]    [0093] 110 C chamber  
         [0094]    [0094] 110 H housing  
         [0095]    [0095] 111  carrier (for substrates or structures)  
       Parts List (con&#39;t)  
       [0096]    [0096] 130  vapor deposition station (organic HTL)  
         [0097]    [0097] 130 C chamber  
         [0098]    [0098] 130 H housing  
         [0099]    [0099] 131  holder and/or mask frame  
         [0100]    [0100] 132  thermally insulative support  
         [0101]    [0101] 134  source  
         [0102]    [0102] 135  heating element(s)  
         [0103]    [0103] 140  vapor deposition station (organic LEL)  
         [0104]    [0104] 150  vapor deposition station (organic ETL)  
         [0105]    [0105] 160  vapor deposition station (second electrodes)  
         [0106]    [0106] 170  storage station  
         [0107]    [0107] 180  encapsulation station  
         [0108]    [0108] 200  crystal mass-sensor (PRIOR ART)  
         [0109]    [0109] 202  electrically grounded casing  
         [0110]    [0110] 204  crystal  
         [0111]    [0111] 205  front electrode  
         [0112]    [0112] 206  rear electrode  
         [0113]    [0113] 207  connection to rear electrode  
         [0114]    [0114] 209  connection to casing (and to front electrode)  
         [0115]    [0115] 210  lead  
         [0116]    [0116] 216  input terminal  
         [0117]    [0117] 220  deposition rate monitor  
         [0118]    [0118] 222  output terminal  
         [0119]    [0119] 224  lead  
         [0120]    [0120] 226  input terminal  
       Parts List (con&#39;t)  
       [0121]    [0121] 230  controller or amplifier  
         [0122]    [0122] 232  output terminal  
         [0123]    [0123] 234  lead  
         [0124]    [0124] 236  input terminal  
         [0125]    [0125] 240  source (heating) power supply  
         [0126]    [0126] 244  output terminal  
         [0127]    [0127] 245  lead  
         [0128]    [0128] 246  output terminal  
         [0129]    [0129] 247  lead  
         [0130]    [0130] 300  mass-sensor assembly with reusable mass-sensor(s)  
         [0131]    [0131] 300 A configuration of mass-sensor assembly  
         [0132]    [0132] 300 B configuration of mass-sensor assembly  
         [0133]    [0133] 300 C configuration of mass-sensor assembly  
         [0134]    [0134] 300 D configuration of mass-sensor assembly  
         [0135]    [0135] 301  mass-sensor  
         [0136]    [0136] 302  mass-sensor  
         [0137]    [0137] 303  mass-sensor  
         [0138]    [0138] 304  mass-sensor  
         [0139]    [0139] 307  mass-sensor  
         [0140]    [0140] 320  sensor support  
         [0141]    [0141] 320 A configuration of sensor support  
         [0142]    [0142] 320 B configuration of sensor support  
         [0143]    [0143] 320 C configuration of sensor support  
         [0144]    [0144] 320 D configuration of sensor support  
       Parts List (con&#39;t)  
       [0145]    [0145] 321  sensor contact  
         [0146]    [0146] 323  lead contact  
         [0147]    [0147] 325  rotator  
         [0148]    [0148] 327  seal  
         [0149]    [0149] 329  shield  
         [0150]    [0150] 390  cleaning flash unit  
         [0151]    [0151] 390 R cleaning radiation unit  
         [0152]    [0152] 391  radiation-absorbing layer  
         [0153]    [0153] 392  light guide  
         [0154]    [0154] 392 B light guide providing oblique incidence of cleaning radiation on the sensor  
         [0155]    [0155] 392 H heater at tip of light guide  
         [0156]    [0156] 392 L lens or lenses  
         [0157]    [0157] 392 M mirror  
         [0158]    [0158] 392 HM heater for mirror  
         [0159]    [0159] 392 T trap (for collecting organic sublimate)  
         [0160]    [0160] 392 W radiation-transmissive window  
         [0161]    [0161] 395  cleaning heater unit  
         [0162]    [0162] 396  lead  
         [0163]    [0163] 398  lead  
         [0164]    [0164] 399  heater

Technology Classification (CPC): 7