Vapor phase deposition device for the continuous deposition of a thin film layer onto a substrate

Abstract

Device (100) for vapor phase deposition of a sublimated source material as a thin film on a photovoltaic (PV) module substrate (14), the device comprising: a separator head (110); a vessel (116) arranged in the separator head (110), wherein the vessel (116) is designed to receive a granular source material; a heated distributor (124) arranged below the vessel (116), wherein the distributor (124) has several channels (126) formed through it, internal cavities (134) arranged between the channels (126) and heating elements (128) arranged in the internal cavities (134), and the vessel (116) is indirectly heated by the distributor (124) to an extent sufficient for sublimating source material within the vessel (116); a distribution plate (152) arranged below the distributor (124) and at a defined distance above a horizontal conveying plane of an upper surface of a substrate (14) conveyed by the device (100), the distribution plate (152) having a pattern of channels formed through it which further distribute the sublimated source material passing through the distributor (124); and a conveying device (160) for the substrate (14) which is arranged and set up below the distribution plate (152) to convey the substrate (14) through the device (100).

Description

AREA OF INVENTION

[0001] The subject matter disclosed herein relates generally to the field of thin-film deposition, in which a thin film layer, such as a semiconductor material layer, is applied to a substrate. Specifically, the subject matter relates to a vapor deposition device for depositing a thin film layer of a photoreactive material onto a glass substrate in the form of photovoltaic (PV) modules. BACKGROUND OF THE INVENTION

[0002] Thin-film photovoltaic (PV) modules (also known as "solar panels") based on cadmium telluride (CdTe) combined with cadmium sulfide (CdS) as photoreactive components are widely accepted and attracting significant interest in industry. CdTe is a semiconductor material with properties particularly well-suited for converting solar energy (sunlight) into electricity. For example, CdTe has a band gap of 1.45 eV, which allows it to convert more energy from the solar spectrum (sunlight) compared to semiconductor materials with a smaller band gap (1.1 eV) that have historically been used in solar cell applications. Compared to materials with a smaller band gap, CdTe also converts light more efficiently under weaker or diffuse light conditions and therefore exhibits higher energy output over the course of a day or under dimly lit (e.g.,Under cloudy conditions, compared to other conventional materials, it exhibits a longer effective conversion time.

[0003] Solar energy systems using CdTe PV modules are generally considered the most cost-effective of the commercially available systems in terms of cost per watt of power generated. Despite the advantages of CdTe, however, the viable commercial use and acceptance of solar energy as a supplementary or primary source of industrial or residential energy depends on the ability to manufacture efficient PV modules on a large scale and at a low cost.

[0004] Several factors significantly influence the efficiency of CdTe PV modules in terms of cost and energy generation capacity. For example, CdTe is relatively expensive, making efficient use (i.e., minimal waste or rejects) of the material a primary cost factor. Furthermore, the energy conversion efficiency of the modules depends on certain properties of the deposited CdTe film layer. Inconsistencies or defects in the film layer can significantly reduce the modules' energy output, thereby increasing the cost per unit of energy. The ability to process relatively large substrates on an economically viable large scale is also a crucial consideration.

[0005] Close-space sublimation (CSS) is a well-known commercial vapor deposition process for the fabrication of CdTe modules. It is referenced, for example, in US 6,444,043 B1 and US 6,423,565 B1. Within the vapor deposition chamber of a CSS system, the substrate is positioned at a relatively small distance (approximately 2–3 mm) from a CdTe source. The CdTe material sublimates and is deposited on the substrate surface. In the CSS system described in US 6,444,043 B1, the CdTe material is in granular form and is held within the vapor deposition chamber in a heated vessel. The sublimated material moves through openings in a cover positioned over the vessel and deposits onto the stationary glass surface, which is held at the smallest possible distance (1-2 mm) above the cover frame.The cover is heated to a temperature higher than that of the container.

[0006] Although the CSS process has advantages, the associated system is inherently a batch process in which the glass substrate is placed in a vapor deposition chamber, held there for a limited time during which the film layer forms, and then removed from the chamber. The system is better suited for the batch processing of substrates with a relatively small surface area. The process must be interrupted regularly to replenish the CdTe source, which is disadvantageous for large-scale production. Furthermore, the deposition process cannot be easily stopped and restarted in a controlled manner, resulting in significant downtime (i.e., wasted time).waste) of CdTe material during the conveying of the substrates into and out of the chamber, as well as during those steps required to position the substrate within the chamber.

[0007] EP 1 160 880 B1 describes a vapor deposition device for coating a photovoltaic substrate, wherein in one embodiment the device comprises a deposition head, vessels for receiving a source material within the deposition head, and a distributor with channels below the vessels. The distributor is indirectly heated by a halogen lamp, which in turn indirectly heats vessels above the distributor to sublimate the source material. Below the distributor, the substrates are conveyed through the device on a belt conveyor.

[0008] US 2006 / 0219177A1 describes a vapor phase deposition device which, in one embodiment, comprises a deposition head in which a container for a granular source material is provided, a distributor below the vessel which is heated by a temperature control system, and a distributor plate which has channels through which the source material is further distributed over the surface of a substrate placed underneath.

[0009] There is a continuing need in industry for an improved vapor phase separation device for the economically viable large-scale production of efficient PV modules, especially CdTe modules. BRIEF DESCRIPTION OF THE INVENTION

[0010] Some aspects and advantages of the invention are set out in the following description, or may be apparent from the description, or can be ascertained through practical implementation of the invention.

[0011] According to the invention, a device for vapor-phase deposition of a sublimated source material, such as CdTe, as a thin film on a photovoltaic (PV) module substrate is provided. Although the invention is not limited to a specific film thickness, a "thin" film layer is generally considered in the field to be less than 10 micrometers (µm) thick. The device comprises a deposition head and a vessel arranged within the deposition head. The vessel is designed to hold a granular source material, such as granular CdTe. A heated distributor or distributor block is arranged below the vessel and has several channels extending through it. The distributor further comprises internal cavities arranged between the channels and heating elements located within these internal cavities. The vessel is indirectly heated by the distributor to a temperature suitable for sublimating the source material within the vessel.The sublimated source material flows out of the vessel and downwards through the channels in the distributor within a head chamber. A distribution plate is positioned below the distributor at a defined distance above a horizontal plane of the upper surface of a substrate being conveyed through the device. The distribution plate has a pattern of openings through it that further distribute the sublimated source material, depositing it as a thin film of substantially uniform thickness onto the upper surface of the substrate. A conveying device for the substrate is positioned below the distribution plate and configured to transport the substrate through the device. The substrates can be conveyed through the device at a constant (i.e., continuous) linear conveying velocity or throughput rate.

[0012] In a particular embodiment, the vessel has transversely extending end walls that are positioned at a distance from the walls of the separation head, so that the sublimated source material flows primarily out and over the end walls of the vessel and flows downwards as a front and a rear transverse curtain towards and through the distributor. The curtains of sublimated source material can be further distributed transversely and to some extent longitudinally before being deposited on the upper surface of the substrates conveyed through the device. The substrates can be transported through the device at a constant linear conveying speed.

[0013] These and other features, aspects and advantages of the present invention are better understood with reference to the following description and the attached claims, or may be apparent from the description or the claims, or may be discovered through practical implementation of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] A complete and preliminary disclosure of the present invention, which contains the best form thereof, is provided in the description which refers to the accompanying drawings. Fig. Figure 1 is a view of a system that may include embodiments of a vapor phase separation device according to the present invention; Fig. Figure 2 is a sectional view of an embodiment of a vapor phase separation device according to aspects of the invention in a first operational position; Fig. Figure 3 is a sectional view of the embodiment shown in Figure 3. Fig. 2 in a second operational position; Fig. Figure 4 is a sectional view of the embodiment shown in Figure 4. Fig. 2 in conjunction with a substrate conveyor; and Fig. 5 is a top view of the vessel component in the embodiment shown in Fig. 2. DETAILED DESCRIPTION OF THE INVENTION

[0015] Reference will now be made in detail to exemplary embodiments of the invention, one or more of which are illustrated in the drawings. Each example is given for the purpose of explaining the invention and not as a limitation of the invention. Indeed, it will be apparent to those skilled in the art that numerous modifications and alterations can be made to the present invention without departing from the scope or spirit of the invention. For example, features that are shown or described as part of one embodiment can also be used with another embodiment to give yet another embodiment. Accordingly, it is intended that the present invention includes such modifications and alterations if they are within the scope of the appended claims and their equivalents.

[0016] Fig. Figure 1 represents an embodiment of a system 10 which includes a vapor phase separation device 100 ( Fig. 2 to 5) according to embodiments of the invention, which may include components configured for applying a thin film layer to a photovoltaic (PV) module substrate 14 (hereinafter referred to as the “substrate”). The thin film may, for example, be a film layer of cadmium telluride (CdTe). As mentioned, it is generally recognized in the art that a “thin” film layer on a PV module substrate generally measures less than 10 micrometers (µm). It should be noted that the present vapor phase deposition device 100 is not intended for use in the application described in Fig. The system shown in 1 is limited to the system 10 shown, but can be incorporated into any suitable processing line that is set up for vapor phase deposition of a thin film layer onto a substrate 14 of a PV module.

[0017] For reference and to understand an environment in which the vapor phase separation device 100 can be used, the system 10 is shown below. Fig. 1 followed by a detailed description of the device 100.

[0018] With reference to Fig. 1: The exemplary system 10 comprises a vacuum chamber 12 formed by a number of interconnected modules. A combination of a coarse and a fine vacuum pump 40 can be configured with the modules to generate and maintain a vacuum within the chamber 12. The vacuum chamber 12 contains a number of heating modules 16, which form a preheating section of the vacuum chamber through which the substrates 14 are conveyed and heated to a desired temperature before being conveyed into the vapor phase separation device 100. Each of the modules 16 can contain a number of independently controlled heating elements 18, the heating elements forming a number of different heating zones. A single heating zone can contain more than one heating element 18.

[0019] The vacuum chamber 12 also contains a number of interconnected cooling modules 20 downstream of the vapor phase separation device 100. The cooling modules 20 form a cooling zone within the vacuum chamber 12 through which the substrates 14, onto which the thin film of sublimated source material has been applied, are conveyed and cooled at a controlled rate before being removed from the system 10. Each of the modules 20 can contain a forced-cooling system in which a cooling medium, such as chilled water, coolant, gas, or another medium, is pumped through cooling loops (not shown) formed in the modules 20.

[0020] In the illustrated embodiment of system 10, at least one post-heating module 22 is arranged in one conveying direction of the substrates immediately downstream of the vapor phase separation device 100 and upstream of the cooling modules 20. The post-heating module 22 maintains a controlled heating profile of the substrate 14 until the entire substrate has been moved out of the vapor phase separation device 100, in order to prevent damage to the substrate, such as warping or breakage caused by uncontrolled or drastic thermal stresses. If a leading section of the substrate 14 were allowed to cool at an excessive rate upon exiting the device 100, a potentially damaging temperature gradient would be created along the longitudinal direction of the substrate 14. This condition could lead to cracking, breakage, or warping of the substrate due to thermal stress.

[0021] As in Fig. Figure 1 schematically shows a feed device 24 with the vapor phase separation device 100 configured to feed a source material, such as granular CdTe. Within the scope and intellect of the invention, the feed device 24 can assume various configurations and effects a feed of the source material without interrupting the continuous vapor phase separation process in the device 100 or the conveying of the substrates 14 through the device 100.

[0022] Further with reference to Fig. 1: The individual substrates 14 are initially arranged on a load conveyor 26 and then moved into an inlet vacuum lock station comprising a load module 28 and a buffer module 30. A "coarse" (initial) vacuum pump 32 is connected to the load module 28 to generate an initial vacuum, and a "fine" (final) vacuum pump 38 is connected to the buffer module 30 to increase the vacuum in the buffer module 30 substantially to the vacuum pressure within the vacuum chamber 12. Valves 34 (such as slotted slide valves or rotary butterfly valves) are operationally arranged between the load conveyor 26 and the load module 28, between the load module 28 and the buffer module 30, and between the buffer module 30 and the vacuum chamber 12.These valves 34 are actuated sequentially by a motor or other type of actuating device 36 to introduce the substrates 14 stepwise into the vacuum chamber 12 without affecting the vacuum in the chamber 12.

[0023] During operation of system 10, an operating vacuum is maintained in the vacuum chamber 12 by a combination of a coarse and / or a fine vacuum pump 40. To introduce a substrate 14 into the vacuum chamber 12, the load module 28 and the buffer module 30 are initially vented (with the valve 34 between the two modules in the open position). The valve 34 between the buffer module and the first heating module 16 is closed. The valve 34 between the load module 28 and the load conveyor 26 is open, and a substrate 14 is conveyed into the load module 28. At this point, the first valve 34 is closed, and the coarse vacuum pump 32 then creates an initial vacuum in the load module 28 and the buffer module 30. The substrate 14 is then conveyed into the buffer module 30, and the valve 34 between the load module 28 and the buffer module 30 is closed.The fine vacuum pump 38 then increases the vacuum in the buffer module 30 to approximately the same vacuum as in the vacuum chamber 12. At this point, the valve 34 between the buffer module 30 and the vacuum chamber 12 is opened, and the substrate 14 is conveyed into the first heating module 16.

[0024] An outlet vacuum lock station is located downstream of the last cooling module 20 and operates essentially in reverse to the inlet vacuum lock station described above. The outlet vacuum lock station can, for example, include an outlet buffer module 42 and a downstream outlet lock module 44. Sequentially actuated valves 34 are located between the buffer module 42 and the last of the cooling modules 20, between the buffer module 42 and the outlet lock module 44, and between the outlet lock module 44 and the outlet conveyor 46. A fine vacuum pump 38 is located at the outlet buffer module 42, and a coarse vacuum pump 32 is located at the outlet lock module 44. The pumps 32, 38 and the valves 34 are actuated sequentially to convey the substrates 14 stepwise out of the vacuum chamber 12 without loss of the vacuum conditions inside the vacuum chamber 12.

[0025] System 10 also includes a conveyor system designed to move the substrates 14 into, through, and out of the vacuum chamber 12. In the illustrated embodiment, the conveyor system comprises a number of individually controlled conveyors 48, each of the multiple modules containing one associated conveyor 48. It should be noted that the type or arrangement of the conveyors 48 can vary. In the illustrated embodiment, the conveyors 48 are roller conveyors with rotatably driven rollers, controlled to achieve a desired conveying speed of the substrates 14 through the corresponding module and the system 10 as a whole.

[0026] As described, the individual modules and their respective conveyors in system 10 are controlled independently to perform a specific function. For this type of control, each module can have its own independent controller 50, which is configured to control the individual functions of the respective module. The multiple controllers 50 can, in turn, communicate with a central system controller 52, as described in Fig. 1 is shown schematically. The central system control 52 can monitor and control the functions of each of the modules (via the independent controllers 50) in order to achieve an overall desired heating rate, deposition quantity or rate, cooling rate, etc. when processing the substrates 14 by the system 10.

[0027] With reference to Fig. 1: For independent control of each individual conveyor 48, each module can have any type of active or passive sensors 54 that detect the presence of the substrates 14 as they are conveyed through the module. The sensors 54 communicate with the respective module controller 50, which in turn communicates with the central controller 52. In this way, each individual conveyor 48 can be controlled to maintain a suitable distance between the substrates 14 and to convey the substrates through the vacuum chamber 12 at a desired constant conveying speed or throughput.

[0028] The Fig. References 2 to 5 relate to a particular embodiment of the vapor phase separation device 100. In particular, with reference to the Fig. 2 and Fig. 3: The device 100 includes a separator head 110, which forms an inner space in which a container or vessel 116 for receiving a (not shown) granular source material is arranged. As mentioned, the granular source material can be supplied by a feed device or feed system 24 ( Fig. 1) through a supply pipe 148 ( Fig. 4) are provided. The feed pipe 148 is connected to a distributor 144, which is arranged in an opening in an upper wall 114 of the separator head 110. The distributor 144 has a number of discharge openings 146, which are arranged for the uniform distribution of the granular source material in the vessel 116. The vessel 116 has an open top and may contain any configuration of internal ribs 120 or other structural elements.

[0029] In the illustrated embodiment, at least one thermocouple 122 is operationally arranged through the upper wall 114 of the separator head 110 in such a way that it monitors the temperature inside the separator head 110 next to or in the vessel 116.

[0030] The separator head 110 also has longitudinal and end walls 112 as well as side walls 113 ( Fig. 5) on. In particular with reference to Fig. 5: The vessel 116 has a shape and structure such that the transverse end walls 118 of the vessel 116 are spaced apart from the end walls 112 of the head chamber 110. The longitudinal side walls 117 of the vessel 116 lie adjacent to and in close proximity to the side walls 113 of the separator head, so that there is only a very small gap between the respective walls, as shown in Fig. Figure 5 shows that in this setup, sublimated source material flows out of the open top of vessel 116 and downwards as a front and a rear vapor curtain 119 over the transversely extending end walls 118, as indicated by the flow arrows in the Fig. 2, Fig. 3 and Fig. Figure 5 shows that very little of the sublimated source material will flow over the side walls 117 of the vessel 116. The vapor curtains 119 are oriented "transversely" in that they extend across the dimensions of the separator head 110 in the transverse direction, which is generally perpendicular to the conveying direction of the substrates through the system.

[0031] A heated distributor block or distributor 124 is arranged below the vessel 116. Within the scope and intellect of the invention, the distributor 124 can assume a variety of forms and serves to indirectly heat the vessel 116 and to distribute the sublimated source material flowing out of the vessel 116. In the illustrated embodiment, the heated distributor 124 has a two-part structure comprising an upper part 130 and a lower part 132. The part 130 and 132 each have recesses that form cavities 134 when the part 130 and 132 are assembled, as shown in the illustration. Fig. 2 and Fig. Figure 3 shows that heating elements 128 are arranged in the cavities 134. These elements serve to heat the distributor 124 to a degree sufficient for indirect heating of the source material within the vessel 116, thereby causing sublimation of the source material. The heating elements 128 could also be made of a material that reacts with the vapor of the source material. In this respect, the shell elements 130, 132 also serve to insulate the heating elements 128 from contact with the vapor of the source material. The heat generated by the distributor 124 also helps to prevent the sublimated source material from depositing on components of the head chamber 110. Desirably, the coolest component in the head chamber 110 is the upper surface of the substrates 14 being conveyed through it, thus ensuring that the sublimated source material deposits on the substrate and not on components of the head chamber 110.

[0032] Further with reference to the Fig. 2 and Fig. 3: The heated distributor 124 has several channels 126 passing through it. The channels have a shape and arrangement to distribute the sublimated source material evenly to the underlying substrates 14 ( Fig. 4) to distribute.

[0033] In the illustrated embodiment, a distribution plate 152 is arranged below the distributor 124 at a defined distance above a horizontal plane of the upper surface of an underlying substrate 14, as shown in Fig. Figure 4 shows this distance. This distance can be, for example, between approximately 0.3 cm and approximately 4.0 cm. In a particular embodiment, the distance is approximately 1.0 cm. The conveying speed of the substrates under the distribution plate 152 can, for example, be in a range of approximately 10 mm / second to approximately 40 mm / second. In a particular embodiment, this speed can be, for example, approximately 20 mm / second. The thickness of the CdTe film layer deposited on the upper surface of the substrate 14 can vary within the scope and intent of the invention and can be, for example, between approximately 1 µm and approximately 5 µm. In a particular embodiment, the film thickness can be approximately 3 µm.

[0034] The distribution plate 152 has a pattern of channels, such as holes, slots, and the like, passing through it, which further distribute the sublimated source material passing through the distributor 124, so that the vapors of the source material are uninterrupted in the transverse direction. In other words, the pattern of channels is shaped, staggered, offset, or otherwise arranged to ensure that the sublimated source material is completely applied across the entire substrate in the transverse direction, thus avoiding longitudinal traces or strips of "uncoated" areas on the substrate.

[0035] As previously mentioned, a significant portion of the sublimated source material flows out of vessel 116 as a front and a rear vapor curtain, as shown in Fig. Figure 5 shows that although these vapor curtains diffuse to some extent in the longitudinal direction before passing through the distribution plate 152, it should be recognized that a uniform distribution of the sublimated source material in the longitudinal direction is unlikely to be achieved. In other words, more of the sublimated source material is distributed through the end sections of the distribution plate 152 compared to the longitudinally central section of the distribution plate. However, because the system 10 transports the substrates 14 through the vapor deposition device 100 at a constant longitudinal velocity, as explained above, the upper surfaces of the substrates 14 are exposed to the same deposition environment regardless of any unevenness in the vapor distribution in the longitudinal direction of the device 100.The channels 126 in the distributor 124 and the openings in the distribution plate 152 ensure a relatively uniform distribution of the sublimated source material in the transverse direction of the vapor phase separation device 100. As long as a uniform transverse distribution of the vapor is maintained, a relatively uniform thin film layer is applied to the upper surfaces of the substrates 14, irrespective of any unevenness in the vapor distribution along the longitudinal direction of the device 100.

[0036] As shown in the figures, it may be desirable to install a fragment or particle shield 150 between the vessel 116 and the distributor 124. This shield 150 has openings formed through it (which may be larger or smaller than the openings of the distribution plate 152) and serves primarily to retain granular or particulate source material from passing through and potentially impairing the operation of the moving components of the distributor 124, as explained in more detail below. In other words, the particle shield 150 can be configured to act as a "breathing screen" that prevents the passage of particles without significantly disrupting the vapors flowing through the shield 150.

[0037] In particular with reference to the Fig. 2 to 4: Preferably, the device 100 has transversely extending seals 154 at each of the longitudinal ends of the head chamber 110. In the illustrated embodiment, the seals form an inlet slot 156 and an outlet slot 158 ​​at the longitudinal ends of the head chamber 110. The seals 154 are arranged at a distance above the upper surface of the substrates 14 that is smaller than the distance between the surface of the substrates 14 and the distribution plate 152, as shown in Fig. Figure 4 shows that the seals 154 help to retain the sublimated source material in the deposition area above the substrates. In other words, the seals 154 prevent the sublimated source material from "leaking" outwards through the longitudinal ends of the device 100. It should be noted that the seals 154 could be formed by any suitable structure. In the illustrated embodiment, the seals 154 are indeed formed by components of the lower shell element 132 of the heated distributor 124. It should also be noted that the seals 154 can interact with other structures of the vapor phase separation device 100 to fulfill the sealing function. For example, the seals could bear against a structure of the underlying conveyor arrangement in the deposition area.

[0038] It is also possible to provide some type of longitudinally extending sealing structure 155 in the device 100 to create a seal along the longitudinal sides of the device. With reference to the Fig. 2 and Fig. 3: This sealing structure 155 may include a longitudinally extending side element which is generally arranged as close as reasonably possible to the upper surface of the underlying conveying surface in order to prevent outflow of the sublimated source material without friction against the conveying element.

[0039] With reference to the Fig. 2 and Fig. 3: The illustrated embodiment includes a movable closure plate 136, which is arranged above the distributor 124. The closure plate 136 has several channels 138 formed through it, which in a first, in Fig. The operational position of the closure plate 136 shown in section 3 is aligned with the channels 126 in the distributor 124. As shown in Fig. As can be easily seen in Figure 3, the sublimated source material can flow freely through the closure plate 136 and the channels 126 in the distributor 124 for subsequent distribution through the plate 152 in this operational position of the closure plate 136. With reference to Fig. 2: The sealing plate 136 is movable relative to the upper surface of the distributor 124 into a second operating position in which the channels 138 in the sealing plate 136 are not aligned with the channels 126 in the distributor 124. In this position, the sublimated source material is prevented from flowing through the distributor 124 and is essentially contained within the inner volume of the head chamber 110. Any suitable actuating device, generally 140, can be provided to move the sealing plate 136 between the first and second operating positions. In the illustrated embodiment, the actuating device 140 comprises a rod 142 and some type of suitable linkage connecting the rod 142 to the sealing plate 136. The rod 142 is rotated by some type of mechanism located outside the head chamber 110.

[0040] The arrangement of the closure plate 136, which is in the Fig. 2 and Fig. As shown in Figure 3, this is particularly useful in that the sublimated source material can be quickly and easily retained within the head chamber 110 for whatever reason and prevented from passing to the separation area above the conveying unit. This may be desirable, for example, when starting up the system 10, while the concentration of vapors within the head chamber builds up to a suitable level to initiate the separation process. Similarly, during system shutdown, it may be desirable to retain the sublimated source material in the head chamber 110 to prevent the material from depositing on the conveyor or other components of the device 100.

[0041] With reference to Fig. 4: The vapor phase separation device 100 may further include a conveying device 160, which is arranged below the head chamber 110. The conveying device 160 may be specifically configured for the separation process in contrast to the conveyors 48 described above with reference to system 10. Fig.As explained in section 1, the conveying device 160 can, for example, be a closed conveying unit comprising a conveyor with continuous rotation on which the substrates 14 are supported below the distribution plate 152. In the illustrated embodiment, the conveying device 160 is formed from a number of plates 162 that provide a flat, continuous support surface (i.e., no gaps between the plates) for the substrates 14. The plate conveyor is driven in a continuous rotation around chain sprockets 164. However, it should be noted that the invention is not limited to any particular type of conveying device 160 for moving the substrates 14 through the vapor phase separation device 100.

[0042] In a particular embodiment, a vapor deposition process, not claimed as such, includes feeding a source material into a vessel within a deposition head and indirectly heating the vessel with a heat source element to sublimate the source material. The sublimated source material is conveyed from the vessel and downwards within the deposition head through the heat source element. Individual substrates are conveyed beneath the heat source element. The sublimated source material passing through the heat source is distributed over an upper surface of the substrates, such that a front and a rear region of the substrates, in the conveying direction, are exposed to the same vapor deposition conditions to achieve a desired uniform thickness of the thin film layer on the upper surfaces of the substrates.

[0043] In a particular embodiment of the process, the sublimated source material is primarily conveyed from the vessel as a front and a rear curtain extending transversely to the conveying direction of the substrates. These curtains of sublimated source material are guided downwards through the heat source element to the upper surface of the substrates. After passing through the heat source element, the front and rear curtains of sublimated source material may be distributed to some extent longitudinally to the conveying direction of the substrates.

[0044] In yet another special embodiment of the method, the channels for the sublimated source material through the heat source can be blocked by an externally operated locking device, as explained above.

[0045] The embodiments of the method desirablely include the continuous conveying of the substrates at a constant longitudinal velocity during the vapor phase deposition process.

[0046] This written description uses examples to disclose the invention that best represent the invention and enable a person skilled in the art to put the invention into practice, including the manufacture and use of any devices or systems. The patentable scope of the invention is defined by the claims and may include further examples that a person skilled in the art might think of. It is intended that such further examples fall within the scope of the claims if they contain structural elements that do not deviate from the wording of the claims or if they contain equivalent structural elements with only insignificant differences from the wording of the claims.

[0047] A device 100 for vapor phase deposition of a sublimated source material as a thin film onto a photovoltaic (PV) module substrate 14 is provided. A vessel 116 is arranged within a vacuum head chamber 110 and is configured to hold a source material. A heated distributor 124 is arranged below the vessel and has a number of channels 126 passing through it. The vessel is indirectly heated by the distributor to an extent sufficient for the sublimation of source material within the vessel. A distribution plate 152 is arranged below the distributor at a defined distance above a horizontal plane of the substrate conveyed through the device.The distribution plate has a pattern of openings formed through it, which further distribute the source material flowing through the distribution plate onto the upper surface of the underlying substrate. Reference symbol list 10 System 12 Vacuum chamber 14 Substrat 16 Heating module 18 heating element 20 Cooling module 22 After-heating module 24 Feed system 26 load conveyors 28 Load module 30 Buffer module 32 Coarse vacuum pump 34 valve 36 Actuating device 38 Fine vacuum pump 40 vacuum pump 42 Output buffer module 44 Exit lock module 46 discharge conveyors 48 sponsors 50 Control 52 Control Panel 54 Sensor 100 vapor phase separation device, device 110 Separation chamber 112 Front end wall 113 Side wall 114 Upper wall 116 Vessel 117 Side wall 118 End wall 119 Steam curtains 120 rib 122 Thermocouple 124 distributors Channel 126 128 Heating element 130 Upper shell element 132 Lower shell element 134 cavity 136 Closure plate Channel 138 140 actuator 142 bars 144 distributors 146 Delivery opening 148 Supply pipe 150 particle shielding 152 Distribution plate 154 Seal 155 Longitudinal seal 156 Input slots 158 output slots 160 funding facility 162 plate 164 sprocket

Claims

[1] Device (100) for vapor phase deposition of a sublimated source material as a thin film on a photovoltaic (PV) module substrate (14), the device comprising: a separator head (110); a vessel (116) arranged in the separator head (110), wherein the vessel (116) is designed to receive a granular source material; a heated distributor (124) arranged below the vessel (116), wherein the distributor (124) has several channels (126) formed through it, internal cavities (134) arranged between the channels (126) and heating elements (128) arranged in the internal cavities (134), and the vessel (116) is indirectly heated by the distributor (124) to an extent sufficient for sublimating source material within the vessel (116); a distribution plate (152) arranged below the distributor (124) and at a defined distance above a horizontal conveying plane of an upper surface of a substrate (14) conveyed by the device (100), the distribution plate (152) having a pattern of channels formed through it which further distribute the sublimated source material passing through the distributor (124); and a conveying device (160) for the substrate (14) which is arranged and set up below the distribution plate (152) to convey the substrate (14) through the device (100). [2] Device (100) according to claim 1, wherein the vessel (116) has transversely extending end walls (118) and longitudinally extending side walls (117), the end walls (118) being spaced apart from the separator head (110) by a distance, so that the sublimated source material flows mainly as a front and a rear veil (119) extending in a transverse direction over the end walls and downwards through the distributor (124). [3] Device (100) according to claim 1, further comprising a movable closure plate (136) arranged above the distributor (124), the closure plate (136) having several channels (138) through it which, in a first position of the closure plate (136), are aligned with the channels (126) in the distributor (124) to allow the passage of sublimated source material through the distributor (124), the closure plate (136) being movable into a second position in which the closure plate (136) blocks the channels (126) in the distributor (124) to allow the passage of sublimated material through them, and further comprising an actuating device (140) connected to the closure plate (136) to move the closure plate (136) between the first and second positions. [4] Device (100) according to claim 1, wherein the distributor (124) has an upper shell element (130) and a lower shell element (132), the shell elements forming the inner cavities (134) in which the heating elements (128) are arranged. [5] Device (100) according to claim 1, further comprising a distributor (144) arranged in an upper wall (114) of the separator head (110) to distribute the source material in the vessel (116) and a particle shield (150) arranged between the distributor (124) and the vessel (116). [6] Device (100) according to claim 1, wherein the conveying device (160) includes a conveyor with continuous circulation on which the substrates (14) are carried below the distribution plate (152), wherein the conveying device (160) is configured to convey the substrates (14) at a constant linear velocity through the device (100) between an inlet slot (156) and an outlet slot (158), such that in one direction of conveying the substrates (14) through the device (100) a front and a rear section of the substrates (14) are generally exposed to the same vapor phase deposition conditions within the deposition head (110).

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