WO2002061170A1

WO2002061170A1 - Purification systems, methods and devices

Info

Publication number: WO2002061170A1
Application number: PCT/US2002/002726
Authority: WO
Inventors: Ghassan Jabbour; Joseph Adiletta; Jr. Charles Hayward
Original assignee: Pall Corporation; Arizona Board Of Regents On Behalf Of The University Of Arizona
Priority date: 2001-01-31
Filing date: 2002-01-31
Publication date: 2002-08-08

Abstract

Vapor deposition systems, methods, and apparatuses for in situ purification of vapor deposition materials. A vapor deposition system includes an apparatus for forming a vapor of a vapor deposition material, an arrangement for receiving a substrate on which a vapor is to be deposited, and a permeable purification medium disposed between the apparatus and the arrangement, such that the vaporized vapor deposition material passes through the permeable purification medium before being deposited on the substrate.

Description

PURIFICATION SYSTEMS, METHODS AND DEVICES

BACKGROUND OF THE INVENTION Vapor deposition processes, e.g., physical vapor deposition (PVD) and chemical vapor deposition (CVD) processes, include film deposition processes in which atoms or molecules of a material are vaporized from a solid or liquid source, transported in the form of a vapor through a vacuum or low pressure gaseous environment, and deposited, e.g., condensed, on a substrate. Vapor deposition processes can be used to deposit films of elemental, alloy, and compound materials, as well as atomically dispersed mixtures, and those materials may comprise organics, such as some polymeric materials, or inorganics. Some specific examples include, but are not limited to, zinc, cadmium, silicon monoxide, magnesium fluoride, and aluminum (III) 8-hydroxyquinoline. The deposited films can be single layers or multi-layers of a single material or a mixture of materials and different layers may have different materials. Further, the deposited films can have a uniform or graded composition and/or can be thick or thin deposits. The deposited material can be amorphous, fine or coarse grained, or single-crystal depending on the material and deposition conditions.

In many applications, it is highly desirable that the deposited films be of very high purity. One source of contamination is the gaseous environment in the deposition system. However, the use of vacuum deposition may reduce the level of environmental gaseous contamination. Typically vacuum deposition takes place in the pressure range of 10^" to 10^" Pa (10^"5-10^" torr), depending on the level of contamination that can be tolerated in the resulting deposited film. Another source of contamination is the material to be deposited. The presence of impurities in the vapor deposition material can be a significant problem in certain applications. For example, in the fabrication of semiconductor devices such as organic light emitting devices, material impurities directly affect device operation and reliability. Thus, for many conventional vapor deposition processes it is preferable that the vapor deposition material be purified prior to use in device fabrication. Current methods of purification include traditional separation techniques such as chromatographic methods and vacuum sublimation. However, these purification techniques require highly complex techniques, e.g., several solution-based steps, and/or several sublimation or evaporation steps, which are time and resource consuming. Further, the vapor deposition material may be contaminated after purification by exposure to the ambient environment, for example, during transfer from the site of purification to the site of deposition.

SUMMARY OF THE INVENTION The present invention ameliorates many of the disadvantages of conventional vapor deposition systems and processes and provides many additional advantages, which will be apparent from the description as set forth below.

In accordance with one aspect of the present invention, a vapor deposition system comprises an apparatus for forming a vapor of a vapor deposition material, an arrangement for receiving a substrate on which a vapor is to be deposited and a permeable purification medium disposed between the apparatus and the arrangement. The vaporized vapor deposition material passes through the permeable purification medium, where it is purified before being deposited on the substrate. The permeable purification medium comprises a substantially uniform fibrous medium. hi accordance with another aspect of the invention, a vapor deposition apparatus comprises a container and a permeable purification medium. The container holds a vapor deposition material and has an opening which defines a flow path for vaporized vapor deposition material to exit the container. The purification medium is mounted to the container in the vapor flow path. The purification medium comprises a substantially uniform fibrous medium. hi accordance with another aspect of the present invention, a vapor deposition apparatus comprises a container for holding a vapor deposition material and a purification module. The container has an opening which defines a vapor flow path allowing vaporized vapor deposition material to exit the container. The purification module includes an inlet and an outlet and defines a flow path between the inlet and outlet. The inlet of the purification module communicates with the vapor flow path of the container. The purification module includes a purification medium disposed in the flow path between the inlet and the outlet. h accordance with another aspect of the present invention, a method of vapor deposition comprises forming a vapor from a vapor deposition material, passing the vapor through a permeable uniform fibrous purification medium and depositing the purified vapor onto a surface. hi accordance with another aspect of the present invention, a vapor deposition purification module for purifying a vapor deposition material in a container comprises a housing and a purification element. The housing includes an inlet and an outlet and defines a flow path between the inlet and the outlet. The housing further includes an arrangement operatively associating the housing and the container. The purification element is cooperatively arranged with the housing and disposed in the flow path between the inlet and the outlet. hi accordance with another aspect of the invention, a vapor deposition system comprises a transfer apparatus cooperatively arranged with a heat source to move a vapor deposition material to a position adjacent the heat source. The vapor deposition system further comprises a substrate arrangement for receiving a substrate on which a vapor deposition material is to be deposited and a permeable purification medium disposed between the heat source and the substrate receiving arrangement. The vaporized vapor deposition material passes through the permeable purification medium, where it is purified before being deposited on the substrate.

In accordance with another aspect of the invention, a vapor deposition method comprises, in a sealed environment, moving a quantity of vapor deposition material to a position adjacent a heat source to form a vapor of the vapor deposition material. The method further comprises passing the vapor along a flow path through a permeable purification medium and depositing on the purified vapor on a surface disposed in the flow path.

Embodiments of the present invention provide several advantages over conventional vapor deposition systems and processes. For example, purification of vapor deposition materials may occur at the time of and in the apparatus in which deposition takes place.

This in situ purification results in a significant reduction in the amount of time required to purify the vapor deposition materials and eliminates the possibility of contamination during transfer from a remote purification stage to the deposition stage. Further, providing a purification module including a purification medium communicating with a container containing the vapor deposition material results in a highly effective, uniformly controlled removal of contaminants from vaporized vapor deposition material. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic of an embodiment of a vapor deposition system. Figure 2 is a view of an embodiment of a vapor deposition apparatus. Figure 3 is a schematic of an embodiment of a vapor deposition system.

Figure 4 is a view of an embodiment of a transfer mechanism.

DESCRIPTION OF THE INVENTION Many different vapor deposition systems may embody the present invention. One example of an embodiment of a vapor deposition system 10 is illustrated in Figure 1. The vapor deposition system 10 preferably includes an apparatus 15 comprising a housing 20 and preferably includes a heat source 25 for vaporizing a vapor deposition material 30. The vapor deposition material 30 is preferably contained in a container 35 such as a crucible or a package. The heat source 25 may comprise, for example, resistively heated filaments or an induction heating element, preferably disposed adjacent the container 35.

The container 35 may comprise any material compatible with the vapor deposition material and capable of withstanding the temperatures necessary to vaporize the vapor deposition material 30. For example, a crucible 35 may comprise a glass, ceramic or a metal. The crucible 35 may be defined by a variety of shapes and sizes, but preferably contains the vapor disposition material and includes an opening defining a vapor flow path for the vaporized vapor deposition material to exit. In the illustrated embodiment, the crucible 35 preferably comprises a cylindrical tube having an opening 38 at its top end, the vapor flow path extending from the vapor deposition material 30 through the opening 38. The vapor deposition material 30, which is preferably contained in the crucible 35, may include any suitable material including elemental, alloy, molecular, and compound materials, such as polymeric materials. For example, in applications involving the production of organic light emitting devices, the material to be deposited may comprise aluminum (III) 8-hydroxyquinoline (Alq₃). However, the invention is not intended to be limited by the material to be deposited, but rather may be applicable to the purification of any material used in vapor deposition, e.g., PVD and/or CVD. The amount of vapor deposition material contained in a container may vary depending on factors such as the type of vapor deposition material and the size of the surface on which the material is to be deposited. Preferably the amount of vapor deposition material contained in a crucible may be on the order of milligrams to grams.

Additionally, the apparatus 15 may include means (not shown) for generating a vacuum within the housing 20, for example, in cases in which the vapor deposition material 30 is to be vacuum deposited. Since vacuum deposition typically takes place in the pressure range on the order about 10^" to about 10^" Pa (about 10^" to about 10^" torr), the housing 20 is preferably capable of withstanding such pressures.

The vapor deposition system 10 may also preferably include a sensor 40 for monitoring the rate of deposition. For example, the sensor may comprise a quartz crystal oscillator, in which the vapor is collected, e.g., on the surface of the quartz crystal, causing the oscillation frequency to change. Calibration of the oscillator allows the change in frequency to be related to deposited material mass. By assuming a material density the thickness of the material deposited can be calculated from the change in frequency. The vapor deposition system 10 also preferably includes an arrangement 50 for receiving a substrate 55 on which a vapor is to be deposited. The arrangement 50 preferably includes a fixture 60 which may be stationary or may be capable of movement in order move the substrate 55 during deposition, for example to rotate the substrate 55 to achieve a uniform deposition. The fixture 60 may also include means for heating or cooling the substrate 55 during the deposition. For example, in the illustrated embodiment the fixture 60 may include a cooling water circulation system 65, e.g., a water circulation system, for cooling the substrate 55 to aid in deposition.

A permeable purification medium 70 is preferably disposed between the container 35 and the substrate 55 such that the vaporized vapor deposition material passes through the permeable purification medium 70 before being deposited on the substrate 55. The purification medium 70 maybe positioned adjacent the substrate 55, adjacent the container 35, or positioned some distance between the two. Preferably, the purification medium 70 is spaced from about 1mm or less to about 50mm or more from the vapor deposition material 30. In some applications, it may be preferable to heat the purification medium 70 to avoid premature condensation of the vaporized vapor deposition material on the purification medium 70. In these applications, it may be advantageous to position the purification medium 70 adjacent to or in contact with the container 35 so the heat source 25 disposed adjacent the container 35 may also heat the purification medium 70. Alternatively, a separate heat source may be provided.

The permeable purification medium 70 may comprise any suitable permeable material capable of removing contaminants from the vaporized material prior to deposition. Preferably, the permeable purification medium 70 comprises a porous medium having an effective pore size in the range from about .01 microns or less to about 20 microns or more, more preferably from about 0.01 microns or less to about 10 microns or more, and even more preferably from about .01 microns or less to about 2 microns or more. The purification medium 70 may have a constant or a graded pore structure. hi many preferred embodiments, the permeable purification medium 70 comprises a fibrous medium including a plurality of fibers 75. The fibers 75 may comprise a variety of materials including, for example, glass, quartz, metals, ceramics or polymers. Preferably, the purification medium 70 is uniform, e.g., has a uniform porosity. A uniform purification medium 70 may be achieved in any suitable method, as is known in the art. For example, the fibers 75 are preferably substantially uniform in diameter to provide a substantially uniform pore size. For example, the diameters of the fibers may have a uniform distribution in which most the fibers, e.g., about 80% or 90% or more, have a diameter that is less than about 200% larger than the nominal fiber diameter, preferably less than about 150%o, more preferably less than about 100%, and even more preferably less than about 50%, larger than the nominal fiber diameter. Preferably, the fibers 75 have a nominal diameter of about 3 microns or less, more preferably about 1.5 microns or less, even more preferably about 1 micron or less, e.g., about .6 microns or less. For example, in some embodiments, the purification medium 70 may comprise borosilicate fibers having a nominal diameter of about 2 microns and 90% of the fibers have a diameter of less than about 4.8 microns, or borosilicate fibers having a nominal diameter of about 1 micron and 90% of the fibers have a diameter of less than about 2.3 microns, or alternatively, quartz fibers having a nominal diameter of about 0.9 microns and 90% of the fibers have a diameter of less than about 2.1 microns. The purification medium may comprise materials other than or in addition to fibers. The permeable purification medium 70 may comprise a granular material, a powder, a permeable foam or other porous media, such as a stack of porous sheets. The medium may be treated in any suitable manner to enhance purification. For example, the purification medium maybe surface modified or coated or additional materials, e.g., reactive or sorptive materials, may be combined with the purification medium.

Preferably, the purification medium 70 selected for a particular application is substantially free of contaminants at the temperature used in the application. For example, in some applications, such as the purification and deposition of Alq₃, the deposition occurs at temperatures of from about 180°C to about 350°C and higher and glass or quartz fibers may be preferred. In other applications, the material to be deposited may be vapor deposited at lower temperatures, e.g., room temperature, in which case the medium may comprise a polymeric material or other material. To minimize the contaminants introduced by the materials selected for the purification medium, it may be advantageous to treat the purification medium prior to the purification and deposition of the vapor deposition material 30. A purification medium 70 may be treated in a variety of ways, e.g., by a heat treatment. Heat treatment may be useful for eliminating binders from the medium which may otherwise contaminate the vaporized vapor deposition material. For example, a purification medium 70 comprising glass fibers may be heat treated at any suitable temperature, e.g., about 400°C, for any suitable amount of time, e.g., approximately 2 hours, in any suitable atmosphere, e.g., in a 5% hydrogen, 95%> argon atmosphere, to provide a purification medium which is substantially free of contaminants. In some embodiments, the permeable purification medium 70 may be disposed in a purification module. Many different purification modules may embody the present invention. One example of a purification module 80 is illustrated in Figure 2. The purification module 80 preferably includes an inlet 85 and an outlet 90 and defines a flow path between the inlet 85 and the outlet 90. The purification medium 70 is preferably disposed in the flow path between the inlet 85 and the outlet 90. Preferably, the purification module inlet 85 communicates with the vapor flow path in the container 35, e.g., with the crucible opening 38.

The purification module 80 preferably comprises a housing 95 including an arrangement operatively associating the housing with the container 35, e.g., the opening 38 in the crucible 35. For example, the purification module 80 may be directly or indirectly mounted to a crucible 35 such that the crucible opening 38 communicates with the inlet 85, whereby all vapors exiting the crucible opening 38 are introduced into the purification module housing 95 through the inlet 85. The arrangement which operatively associates the housing and the crucible may be variously configured. In some embodiments, the purification module 80 may be mounted directly to the crucible 35, e.g., it is preferably mounted within or over the crucible opening 38 with a fluid-tight fit. hi the illustrated embodiment, the purification module 80 comprises a housing 95 including a cylindrical shape having an outer diameter which tightly fits within the inner diameter of the crucible opening 38. The housing 95 may then be friction fit inside the crucible 35. An annular ledge 96 preferably extending radially around the outer periphery of the purification module 80 may engage an upper lip of the crucible and further axially locate the purification module within the crucible, ensuring a fluid-tight fit and fixing the distance between the purification medium 70 and the vapor deposition material 30. Alternatively, the housing 95 may have an inner diameter which tightly fits around the outer diameter of the crucible 35. In some embodiments, the fluid-tight fit maybe formed by expansion and/or contraction of the purification module 80 and the crucible 35, respectively, during heating of the vapor deposition material 30, and/or by the incorporation of a gasket between the housing 95 and the crucible 35.

The purification module 80 preferably further comprises a purification element 100. The purification element 100 preferably includes a porous support 105 and the purification medium 70. The porous support 105 may comprise any suitable non- contaminating material with sufficient structural integrity to support the purification medium 70, for example, metal or ceramic. In a preferred embodiment, the porous support 105 comprises a stainless steel mesh.

In some embodiments, the purification element may comprise a purification medium 70 formed directly on the porous support 105 or alternatively the purification medium 70 may be formed separately from the porous support 105. hi some embodiments, the purification medium 70 preferably comprises borosilicate glass fibers or quartz fibers wet- laid directly on the support 105. For example the fibers may be mixed with a suitable carrier liquid, e.g., ultra-pure deionized water, to foi a slurry. Preferably the slurry is poured onto the porous support 105 and the liquid is removed. It may be advantageous to remove the liquid using a vacuum in some embodiments. The slurry composition is preferably determined based on the desired void fraction. In some embodiments, the purification medium 70 preferably has a void fraction of from about 90% or less to about 95%) or more wherein the slurry preferably comprises from about 0.5 to about 8 grams of fiber per liter of ultra-pure deionized water, more preferably about 3 grams per liter of ultra-pure deionized water. The slurry is preferably free from any additives, such as binders or resins. The quantity of the slurry that is applied to the porous support 105 may be determined by any suitable parameter(s), such as desired thickness, weight, density, and void volume of the purification medium 70. The thickness of the purification medium 70 is preferably selected to enhance the removal of contaminants from the vapor deposition material 30 and may vary depending, for example, on the amount of vapor deposition material that is to be heated and passed through the porous medium 70. Preferably, the purification medium 70 has a thickness of from about 0.05 inch or less to about 0.50 inch or more. In the illustrated embodiment, the purification element 100 includes an additional porous support 107 preferably disposed over the purification medium 70. Advantageously, the resulting purification medium 70 has a substantially uniform configuration, which results in substantially uniform purification of the vapor deposition materials.

The purification element 100 maybe disposed in the purification module 80 in a variety of ways. For example, the housing 95 may include a groove, ledge or other support for mounting the element 100 in the housing 95. In the illustrated embodiment, the housing 95 preferably includes an annular ledge 98 disposed around the inner periphery of the housing 95. Additionally, the housing may include a sealing member for securing the purification element 100 in the housing 95. In the illustrated embodiment, the housing includes a ring 99 friction fit in the housing 95 adjacent the additional support 107 for securing the purification element 100 in the housing 95. The purification element 100 may be positioned within the purification module 80 in any suitable location. Preferably, the distance between the purification medium 70 in the purification element 100 and the vapor deposition material 30 is selected to enhance the removal of contaminants from the vapor deposition material 30. The purification medium 70 is preferably spaced from about 1 mm or less to about 50 mm or more from the vapor deposition material 30. Many different vapor deposition methods may embody the present invention. One preferred mode of operation preferably includes forming a vapor of a vapor deposition material and passing the vapor through a penneable purification medium. The vapor may be formed in a variety of ways. The vapor may preferably be formed by heating a crucible 35 containing the vapor deposition material 30. It may also be advantageous, in some embodiments, to heat the permeable purification medium 70, for example, to prevent the deposition of the vapor deposition material 30 on the purification medium 70. Preferably, the vapor is purified as it passes through the permeable purification medium 70. The vapor may contain contaminants from a variety of sources. For example, the vapor deposition material itself may contain contaminants and/or reaction or decomposition of the vapor deposition material, e.g., during heating, may produce contaminants. Contaminants may include, for example, polymeric complex particulates. The vapor may be purified using any suitable purification mechanism including any physical or chemical processes by which contaminants maybe removed, including, for example, by filtration, sorption, e.g., adsorption or absorption, condensation or coalescence. For example, the permeable purification medium may operate as a depth type medium effectively providing, for example, nano-level removal ratings at the low flow rates and low flow volumes encountered in PVD and CVD processes. Purification media that are deep or thick relative to the contaminant size, especially when utilized with low flow rates and small flow volumes, are highly effective at trapping contaminants within and/or on the surface of the medium. All or a portion of the purified vapor that has passed through the permeable purification medium 70 is preferably deposited onto a surface, e.g., a surface of a substrate. In some embodiments, the surface may be stationary. Alternatively the surface may be in motion, e.g., rotated, during deposition, e.g., to achieve a uniform deposition. It may also be advantageous, in some embodiments, to heat or alternatively cool the surface during deposition.

A permeable purification element 100 which preferably includes a uniform purification medium 70, advantageously provides uniform purification of the vapor deposition material. Providing a preferably substantially uniform porous medium results in a highly effective uniform and controlled removal of contaminants from vaporized vapor deposition materials. hi some embodiments, a vapor deposition system preferably includes a transporting apparatus cooperatively arranged with the heat source to move a quantity of a vapor deposition material to and/or from a position adjacent to the heat source to form a vapor from the vapor deposition material and to remove the residue. The apparatus preferably moves the vapor deposition material automatically, to and/or from a position adjacent to the heat source and may comprise a variety of configurations including a mechanical, electrical and/or magnetic configuration. For example, the transporting apparatus may include a robotic arm or a moving carrier which moves the vapor deposition material to and/or from the heat source. The vapor deposition material maybe transported in a container, such as a crucible, or not in a container, e.g., as bulk material on the carrier. Another example of an embodiment of a vapor deposition system 200 is illustrated in

Figure 3. This system 200 may include many elements, such as a housing 20, a heat source 25, an arrangement 260 for receiving a substrate 55, a vacuum generator (not shown), a fixture (not shown), and a sensor (not shown), which may have one or more of any of the features described with respect to other embodiments. The vapor deposition system 200 further includes a transporting apparatus 215 cooperatively arranged with a heat source 25 and the housing 10. For example, the transporting apparatus 215 may be disposed inside the housing 10, e.g., isolated from the substrate 55 by a barrier 225. Much or all of the transporting apparatus 215 is then sealed within the housing 10 and the vapor deposition material 30 is isolated from the ambient environment. Alternatively, the transporting apparatus may be disposed at least partially outside the housing.

The transporting apparatus 215 preferably comprises a dispenser 220 for dispensing the vapor deposition material 30 onto the surface 230 of a carrier 235 which moves the vapor deposition material 30 adjacent to the heat source 25. The carrier 215 may, for example, comprise a conveyor, such as a belt or chain conveyor, or a rotating disk. In some embodiments, the dispenser 220 may dispense the vapor deposition material 30 directly onto the carrier 235 while the carrier is in motion. Advantageously, dispensing the material directly onto a moving carrier results in the formation of a thin layer of vapor deposition material 30 which may result in more uniform formation of the vapor, for example, due to a more even heating of the vapor deposition material. Alternatively, the dispenser 220 may dispense the vapor deposition material 30 onto a carrier 235 which is stationary while the vapor deposition material 30 is being dispensed. After the vapor deposition material 30 has been dispensed, the carrier may then move the vapor deposition material 30 to a position adjacent the heat source 25. The dispenser 220 may comprise any suitable dispenser for dispensing a vapor deposition material, e.g., a screw-type dispenser or a sprayer. As yet another alternative, the dispenser may dispense containers, e.g., crucibles, containing the vapor deposition material onto the carrier.

Cooperatively arranging the transporting apparatus 215 with the heat source 25 to move a quantity of vapor deposition material 30 provides several advantages. For example in some embodiments, after the vapor from a first quantity of vapor deposition material 30 has been vaporized by the heat source 25 and deposited on a surface (e.g., a substrate surface), the residue of the first quantity of material may be moved away from the heat source and a second quantity of vapor deposition material 30 may be moved to a position adjacent the heat source 25 by the transporting apparatus 215, where it is heated and deposited on the substrate. The process may be repeated until the desired degree of deposition on the substrate surface is achieved, hi some embodiments, a transfer mechanism 240 may be cooperatively associated with the substrate arrangement 260 which receives the substrate 55. The transfer mechanism 240 preferably moves substrates 55 to and from a position in which the vaporized vapor deposition material may be deposited onto the substrate. For example, the transfer mechanism 240 may move a substrate 55 into position for the deposition and after deposition remove the coated substrate 55 and transfer another substrate 55 into position for deposition. In some embodiments, the process of both moving the vapor deposition material 30 and substrates 55 into position may be performed repeatedly to efficiently form a plurality of coated substrates.

The substrate transfer mechanism 240 may comprise any suitable configuration for transferring substrates 55. For example, the transfer mechanism may comprise a robotic aπn or a conveyor. In one embodiment, illustrated in Figure 4, the transfer mechanism 240 comprises a rotating disk conveyor 241. hi the illustrated embodiment, the rotating disk conveyor 241 includes four substrates 55, although the rotating disk conveyor 241 may include more than or fewer than four substrates 55. The rotating disk conveyor 241 rotates about a center rod 245 to position a substrate 55 to be received by the substrate arrangement 260. A shielding arrangement (not shown) may be operatively associated with the transporting mechanism to shield the substrate being coated from the substrate which have not yet been coated and the substrates which have been coated. hi the vapor deposition system 200 shown in Figure 3, a permeable purification medium 70 is preferably disposed in the flow path of the vapor of the vapor deposition material, e.g., between the heat source 25 and the substrate 55. For example, the purification medium 70 may be disposed in a purification module which is mounted in an opening in the barrier 245. In some embodiments, the permeable purification medium may be capable of movement. For example, it may be advantageous to replace the permeable purification medium after it has become fouled, e.g., after each substrate is coated. The permeable purification medium may be moved and/or replaced in a variety of ways. A transporting mechanism such as a robotic arm or a carrier may transport the purification medium into and out of the flow path of the vaporized vapor deposition material. For example, in embodiments in which the permeable purification medium is disposed in a purification module, a robotic arm may remove and replace the purification module. Alternatively, a purification module may be cooperatively associated with each container containing vapor deposition material such that when a container containing vapor deposition material is moved adjacent to the heat source by the transporting apparatus, the new purification module is also moved into position. In another embodiment, the permeable purification medium may be disposed on a roll, which may be unrolled to position a new portion of the permeable purification medium in the vapor flow path. Preferably, the fouled permeable purification medium is removed and replaced at the same time the vapor deposition material is being moved and/or at the same time the substrate is being replaced. Most preferably, the permeable purification medium is removed and replaced at some time when a vapor is not being deposited on the substrate. hi some prefened embodiments, the vapor deposition system may be automated. Automated systems provide many advantages, for example, more efficient and less time consuming deposition. Preferably, upon initiation in an automated vapor deposition process, a substrate is moved into a position for deposition and to a quantity of vapor deposition material is moved to a position adjacent the heat source. The vapor is formed from the vapor deposition material, the vapor is passed through the permeable purification medium and deposited on the substrate. Additional quantities of vapor deposition material may be automatically moved by the transporting apparatus adjacent to the heat source and then vaporized and deposited on the substrate until the desired degree of deposition is achieved. The automated system may determine when the desired degree of deposition has been achieved by any suitable method. For example, a sensor monitoring the rate of deposition may provide a signal when the desired level of deposition is achieved. Alternatively, the quantity of vapor deposition material moved adjacent the heat source may signal when the desired degree of deposition is achieved. Once the desired degree of deposition is achieved, the automated system preferably removes the substrate, hi some embodiments, the automated system may automatically move another substrate into position for deposition, and repeat the above process. In some embodiments of an automated vapor deposition system, the penneable purification medium may be periodically removed and replaced. The automated system may include a controller which controls the movement of one or more of the vapor deposition material, the substrates, and the permeable purification medium.

While many different vapor deposition methods may embody the present invention, one preferred mode of operation is performed within a sealed housing . Preferably the vapor deposition material 30, permeable purification medium 70, and substrate 55 are positioned within the sealed housing and the deposition process is performed within the sealed housing to minimize the possibility of contamination. For example, a source of vapor deposition material 30 may be located in the environment of a sealed housing such that the vapor deposition material 30 remains within the sealed housing as it is moved to a position adjacent the heat source 25. Similarly, a supply of substrates may be located in the sealed housing such that a substrate 55 remains within the sealed housing as it is moved by the substrate arrangement 260. i embodiments in which the permeable purification medium is removed and replaced, the sealed housing may contain a supply a permeable purification medium so that the replacement may be carried out within the sealed housing. In some embodiments of the present invention, the vapor deposition system may include more than one anangement for receiving a substrate. Alternatively or additionally, the substrate arrangement maybe capable of receiving more than one substrate. Advantageously, a system including multiple substrate arrangements and/or a substrate anangement capable of receiving more than one substrate allows deposition on multiple substrates simultaneously or sequentially. For example, in some embodiments it may be advantageous to deposit a vapor on one substrate while another substrate is being removed and replaced. The system including more than one substrate may include more than one heat source and/or more than one permeable purification medium. Alternatively, the system may include a single heat source and/or a single permeable purification medium for multiple substrates. All of the references cited herein, including publications, patents, and patent applications, are hereby incorporated in their entireties by reference.

While the invention has been described in some detail by way of illustration and example, it should be understood that the invention is susceptible to various modifications and alternative forms, and is not restricted to the specific embodiments set forth. It should be understood that these specific embodiments are not intended to limit the invention but, on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Claims

WHAT IS CLAIMED IS:

1. A vapor deposition system comprising: an apparatus for fonning a vapor of a vapor deposition material; an arrangement for receiving a substrate on which a vapor is to be deposited; a permeable purification medium disposed between the apparatus and the arrangement, such that the vaporized vapor deposition material passes through the permeable purification medium before being deposited on the substrate, wherein the permeable purification medium comprises a substantially uniform fibrous medium.

2. The vapor deposition system according to claim 1 wherein the substantially uniform fibrous medium includes fibers having a substantially uniform diameter.

3. The vapor deposition system according to claim 1 or 2 wherein the apparatus for forming a vapor includes a heat source which vaporizes the vapor deposition material and a housing containing the heat source.

4. A vapor deposition apparatus comprising: a container for holding a vapor deposition material and having an opening which defines a flow path for vaporized vapor deposition material to exit the container; and a permeable purification medium mounted to the container in the flow path, wherein the permeable purification medium comprises a substantially uniform fibrous medium.

5. A vapor deposition apparatus according to claim 4 wherein the substantially uniform fibrous medium includes fibers having a substantially uniform diameter.

6. The vapor deposition system or apparatus according to claim 1, 2, 3, 4 or 5 wherein the substantially uniform fibrous medium comprises fibers having a nominal diameter of about 3 microns or less.

7. The vapor deposition system or apparatus according to claim 6 wherein the substantially uniform fibrous medium comprises fibers having a nominal diameter of about 1 micron or less.

8. The vapor deposition system or apparatus according to claim 1, 2, 3, 4, 5, 6 or 7 wherein the substantially uniform fibrous medium is substantially free of binder.

9. The vapor deposition system or apparatus according to claim 1, 2, 3, 4, 5, 6, 7 or 8 wherein the substantially uniform fibrous medium has a thickness of from about 0.05 to about 0.50 inch.

10. A vapor deposition apparatus comprising: a container for holding a vapor deposition material and having an opening which defines a vapor flow path for vaporized vapor deposition material to exit the container; and a purification module including an inlet and an outlet and defining a flow path between the inlet and outlet, the inlet communicating with the vapor flow path of the container, the purification module including a purification medium disposed in the flow path between the inlet and the outlet.

11. The vapor deposition apparatus according to claim 10 wherein the purification module is mounted directly to the container.

12. The vapor deposition apparatus according to claim 10 or 11 wherein the purification module is mounted within the container opening.

13. The vapor deposition apparatus according claim 10, 11 or 12 wherein the purification medium is supported by a porous support disposed in the flow path between the inlet and the outlet.

14. The vapor deposition apparatus according to claim 10, 11, 12 or 13 wherein the container includes a vapor deposition material and wherein the purification medium is disposed from about 20 mm to about 50 mm from the vapor deposition material. i

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15. The vapor deposition apparatus according to claim 10, 11, 12, 13 or 14 wherein the purification medium comprises a substantially uniform fibrous medium.

16. A method of vapor deposition comprising: forming a vapor from a vapor deposition material; passing the vapor through a permeable uniform fibrous purification medium; and depositing the purified vapor onto a surface.

17. The method of vapor deposition according to claim 16 wherein forming a vapor deposition material comprises heating a vapor deposition material.

18. The method of vapor deposition according to claim 16 or 17 wherein passing the vapor through a permeable purification medium comprises passing the vapor through a heated permeable purification medium.

19. A vapor deposition purification module for purifying a vapor deposition material in a container comprising: a housing including an inlet and an outlet and defining a flow path between the inlet and the outlet, wherein the housing further includes an arrangement operatively associating the housing and the container; a purification element cooperatively ananged with the housing, wherein the purification element is disposed in the flow path between the inlet and the outlet.

20. The vapor deposition purification module according to claim 19 wherein the arrangement operatively associating the housing and the container mounts the housing within an opening in the container.

21. The vapor deposition purification module according to claim 19 or 20 wherein the purification element comprises a purification medium supported by a porous support.

22. The vapor deposition purification module according to claim 19, 20 or 21 wherein the purification element includes a substantially uniform fibrous purification medium.

23. The vapor deposition purification module according to claim 19, 20, 21 or 22 wherein the purification element is disposed in the housing a distance of from about 20 mm to about 50 mm from the vapor deposition material in the container.

24. A vapor deposition system comprising: an apparatus cooperatively arranged with a heat source to move a vapor deposition material to a position adjacent the heat source; an anangement for receiving a substrate on which a vapor is to be deposited; a permeable purification medium disposed between the heat source and the substrate support anangement such that the vaporized vapor deposition material passes along a flow path through the permeable purification medium before being deposited on the substrate.

25. The vapor deposition system according to claim 24 further comprising a transporting mechanism cooperatively associated with the anangement to move a substrate into or out of a position for deposition.

26. The vapor deposition system according to claim 24 or 25 further comprising a transporting assembly for moving a new purification medium into the vapor flow path.

27. A vapor deposition method comprising: in a sealed environment moving a quantity of vapor deposition material to a position adjacent a heat source to form a vapor of the vapor deposition material, passing the vapor along a flow path tlirough a permeable purification medium and depositing the purified vapor on a surface disposed in the flow path.

28. The method of claim 27 further comprising in a sealed housing moving an additional quantity of vapor deposition material to a position adjacent the heat source to form a vapor from the additional quantity of vapor deposition material.

29. The method of claim 27 or 28 further comprising in the sealed housing moving the surface on which the purified vapor has been deposited out of the flow path of the vapor.

30. The method of claim 27, 28 or 29 further comprising in the sealed housing moving a second surface into the flow path of the vapor.

31. The method of claim 28 further comprising in the sealed housing moving an additional quantity of a vapor deposition material to a position adjacent a heat source to form a vapor from the additional quantity of vapor deposition material, passing the vapor from the additional quantity of vapor deposition material through a permeable purification medium and depositing the purified vapor from the additional quantity of vapor deposition material on the second surface disposed in the flow path.