JP2014523479A - In-line chemical vapor deposition method and system - Google Patents

Abstract

  An in-line chemical vapor deposition method and system for device fabrication is disclosed. The method includes transporting a web substrate or individual substrates in a deposition chamber comprising a plurality of deposition modules. When passing through the first deposition module, the second deposition module, and the third deposition module, a buffer layer, a window layer, and a transparent conductive layer are deposited on the substrate, respectively. Advantageously, the steps of generating the buffer layer, the window layer, and the transparent conductive layer are performed sequentially in a common vacuum environment within a single deposition chamber to deposit the buffer layer. Conventional chemical bath deposition processes are not used. The method is suitable for the manufacture of various different types of devices, including various solar cells such as copper indium gallium diselenide solar cells.

Description

Related Applications This application is a continuation-in-part of US patent application Ser. No. 12 / 767,112, filed Apr. 26, 2010, entitled “Inline Chemical Vapor Deposition System”. Claims the benefit of the filing date of certain US patent application Ser. No. 13 / 156,465 filed Jun. 9, 2011, entitled “Inline Chemical Vapor Deposition Method and System”. The entirety of these applications is incorporated into this application by reference.

TECHNICAL FIELD The present invention relates generally to systems and methods for chemical vapor deposition. More particularly, the present invention relates to a chemical vapor deposition system for in-line processing of web substrates and discrete element substrates.

  Chemical vapor deposition (CVD) is a process used to deposit semiconductors, dielectrics, metals, and other thin films on the surface of a substrate. In one common CVD technique, one or more precursor molecules, each in the gas phase, are introduced into a process chamber containing a substrate. The reaction of these precursor gases at the substrate surface is initiated or enhanced by applying energy. For example, energy can be applied by increasing the temperature of the surface or by exposing the surface to a plasma discharge or ultraviolet (UV) radiation source.

  The quality of the thin film formed by the CVD reaction that occurs in the gas phase is highly dependent on the uniformity of the precursor gas flow. If the gas flow near the substrate surface is not uniform, good thin film uniformity cannot be obtained and shadowing artifacts due to surface features such as steps and vias. May occur. High-speed processing of wafers and other individual substrates, and high-speed processing of web substrates in roll-to-roll deposition systems are limited by known CVD process systems and methods, and can be used for yield and other factors. Often expensive.

  Atomic layer deposition (ALD) is another technique for depositing a thin film on the surface of a substrate. In the ALD process, a first precursor gas flow is used to react with the substrate surface to produce a monolayer. After terminating the first precursor gas flow, another single layer is generated using the second precursor gas flow. This two-step sequence of “pulsing” the precursor gas (flowing in pulses) is repeated many times until the thin film of single material has the desired thickness. In other approaches of the ALD process, thin films are produced using sequentially more than two precursor gas flows. When each precursor gas is introduced into the reaction chamber, a purge gas may be introduced before the precursor gas to reliably remove the precursor gas introduced before that time. This reduces or prevents unnecessary by-product accumulation. The ALD process can control the film thickness satisfactorily, but it takes time to alternately generate a single layer on the substrate surface and greatly limits the throughput.

Overview In one aspect, the invention features an in-line chemical vapor deposition method for fabricating a device. The method includes transporting a substrate in a deposition chamber having a vacuum environment and comprising a first deposition module, a second deposition module, and a third deposition module. During transport of the substrate in the first deposition module, a buffer layer is deposited on the substrate. A window layer is deposited on the buffer layer during transport of the substrate in the second deposition module. During the transport of the substrate in the third deposition module, a transparent conductive layer is deposited on the window layer.

  In another aspect, the invention features an in-line chemical vapor deposition method for fabricating a device. The method includes transporting a substrate having a metal layer and an absorbing layer at a constant rate in a deposition chamber having a vacuum environment and comprising a first deposition module, a second deposition module, and a third deposition module. including. Each deposition module comprises at least one deposition station comprising a manifold having a first precursor port, a pair of second precursor ports, and a pair of pumping ports. The first precursor port is disposed between the second precursor ports, and the second precursor port pair is disposed between the pumping ports. The first precursor port and second precursor port pair are configured to connect to a first precursor gas source and a second precursor gas source, respectively. The pumping port is configured to connect to an exhaust system for exhausting the first and second precursor gases. The method further includes depositing a buffer layer on the substrate during transport of the substrate within the first deposition module and during transport of the substrate within the second deposition module. Depositing a window layer on the buffer layer and depositing a transparent conductive layer on the window layer during transport of the substrate in the third deposition module.

In yet another aspect, the invention features an in-line chemical vapor deposition system that includes a deposition chamber, a continuous transport system, and first, second, and third deposition modules.
The continuous transport system transports a substrate along a path through the deposition chamber. The first, second and third deposition modules are arranged on a path in the deposition chamber. The first deposition module comprises at least one deposition station for depositing a buffer layer on the substrate, and the second deposition module comprises at least one for depositing a window layer on the buffer layer. The third deposition module comprises at least one deposition station for depositing a transparent conductive layer on the window layer. Each deposition module comprises at least one deposition station with a manifold. Each manifold has a first precursor port, a pair of second precursor ports, and a pair of pumping ports.
The first precursor port is disposed between the second precursor ports, and the second precursor port pair is disposed between the pumping ports. The first precursor port and second precursor port pair are configured to connect to a first precursor gas source and a second precursor gas source, respectively. The pumping port is configured to connect to an exhaust system for exhausting the first and second precursor gases.

BRIEF DESCRIPTION OF THE DRAWINGS The above and further advantages of the present invention can be better understood with reference to the following description taken in conjunction with the accompanying drawings, in which: In the various figures attached, like elements are indicated by like reference numerals. For the sake of clarity, not all constituent elements are labeled in each drawing. The drawings are not necessarily to scale, emphasis instead being placed on illustrating the principles of the invention.
It is a figure which shows one Embodiment of the in-line type CVD system which concerns on this invention. FIG. 4 shows a web substrate being transported through a deposition station manifold, in accordance with one embodiment of the present invention. FIG. 6 shows a web substrate being transported through a manifold of a deposition station according to another embodiment of the present invention. FIG. 4 illustrates a web substrate being transported through a deposition station manifold according to another embodiment of the present invention. 2 is a manifold block diagram of the deposition station (s) shown in FIG. 1 integrated as a single structure, in accordance with one embodiment of the present invention. FIG. It is the figure which looked at the web board | substrate in relative positional relationship with the precursor port and pump port which are shown to FIG. 3A from the top. FIG. 3 is a top perspective view of one embodiment of an integrated deposition station module according to the present invention. FIG. 4B is a perspective view of the integrated deposition station module shown in FIG. 4A as viewed from the bottom. FIG. 4B is a cutaway view of the integrated deposition station module shown in FIG. 4A. FIG. 4 is a diagram illustrating another embodiment of an inline CVD system according to the present invention. FIG. 3 shows an example of a device structure that can be achieved using an embodiment of an in-line CVD system according to the present invention. FIG. 4 is a diagram illustrating another embodiment of an inline CVD system according to the present invention. FIG. 4 is a diagram illustrating another embodiment of an inline CVD system according to the present invention. 2 is a flowchart illustrating an embodiment of an in-line CVD method for fabricating a device.

DETAILED DESCRIPTION The step (s) of the method of the present invention can yield significant results when performed in any order and perform two or more steps simultaneously unless otherwise noted. be able to. Further, the systems and methods of the present invention can include any of the embodiments described herein, or can include any combination of the described embodiments in possible aspects.

  The teachings herein relate to systems and methods for reactive gas phase processing, such as CVD, MOCVD, and Halide Vapor Phase Epitaxy (HVPE) processes. In conventional reactive gas phase processing for semiconductor materials, a semiconductor wafer is mounted on a carrier in a reaction chamber. A gas distribution injector is arranged to face this carrier. In general, an injector includes a gas inlet that receives a plurality of gases or a combination of gases. The injector directs the gas or combination of gases to the reaction chamber. Injectors typically have a showerhead device arranged in a pattern in which the precursor gas reacts as close as possible to each wafer surface to maximize the efficiency of the reaction process and epitaxial growth on the wafer surface. I have.

  Some gas distribution injectors include a shroud so that a laminar gas flow (hereinafter also referred to as “laminar gas flow”) is supplied during the CVD process. One or more carrier gases can be used to assist in the generation and maintenance of laminar gas flow. The carrier gas does not react with the precursor gas and does not otherwise affect the CVD process. A typical gas distribution injector directs precursor gas from a gas inlet toward a target area where a wafer in the reaction chamber is processed. For example, in some MOCVD processes, a gas distribution injector directs a combination of precursor gases including metal organics and hydroxides to the reaction chamber. A carrier gas such as hydrogen or nitrogen or an inert gas such as argon or helium is directed through the injector into the chamber to help maintain laminar flow at the wafer location. The precursor gas (s) mix and react in the chamber to form a thin film on the wafer.

  In MOCVD and HVPE processes, the wafer is typically maintained at an elevated temperature, and the precursor gas is typically kept at a lower temperature when introduced into the reaction chamber. The temperature of the precursor gases, and hence the energy they can use in the reaction, increases as they pass through the hotter wafer.

  One common type of CVD reaction chamber includes a disk-shaped wafer carrier. The carrier has pockets or structural features arranged to hold one or more wafers on the top surface of the carrier. During the CVD process, the carrier rotates about a vertical axis that extends perpendicular to the wafer support surface. The rotation of the carrier improves the uniformity of the deposited material. During rotation, precursor gas is introduced into the reaction chamber from a flow inlet element provided above the carrier. The flowing gas passes down towards the wafer, preferably as a laminar plug flow. As the gas approaches the rotating carrier, the gas is drawn into rotation about the axis by viscous drag. As a result, in the boundary area close to the carrier surface and the wafer, the gas flows around the axis and outwards towards the edge of the carrier. As the gas passes through the edge of the carrier, it flows downward toward one or more exhaust ports. Typically, the MOCVD process is performed while flowing different precursor gases in succession, possibly setting the wafer at various different temperatures, and depositing different layers, each having a different composition, Form.

  CVD processes such as MOCVD and HVPE typically have limited throughput. Conventional systems and methods for CVD processes are not sufficient for high-volume processing of wafers and other individual substrates, and high speed processing of web substrates in roll-to-roll deposition systems that do not use redundant equipment. There are many cases.

  The system and method of the present invention is suitable for in-line CVD processing of web and individual substrates. The systems and methods are particularly adapted to perform high throughput processing to deposit a single layer on a substrate, such as in the fabrication of solar cells and flat panel displays. For example, in some applications, zinc oxide is deposited on a substrate to make a solar cell. Also, for example, in other applications, indium tin oxide is deposited on the substrate as part of the flat panel display fabrication process. As used herein, the substrate (or substrate, substrate) may be a superstrate, ie, a support layer (support layer) that is the first layer of a device that receives incident light. it can. The system provides various advantages compared to conventional deposition systems. The quality of the deposited thin film is improved and the cost of the process equipment is reduced. In addition, the operating costs are lower due in part to the better utilization efficiency of the materials. For example, material utilization efficiency is substantially higher than target material utilization efficiency in conventional sputtering systems.

  FIG. 1 is a diagram illustrating one embodiment of an in-line CVD system 10 according to the present invention. The in-line CVD system 10 includes a web transport system for continuously transporting the web substrate 14 within the deposition chamber 18. The web transport system includes a sending roller 22A and a receiving roller 22B. The delivery roller 22A is a supply source of the web substrate 14 to be processed. The receiving roller 22B receives the web substrate 14 after the deposition is completed, and maintains the web substrate 14 in a roll shape. The auxiliary roller 22C is disposed in the deposition chamber 18 between the sending roller 22A and the receiving roller 22B, and accurately controls the moving path of the web substrate 14. The web transport system transports the web substrate 14 at a substantially constant speed along the path. Optionally, a purge gas may be placed in various chamber locations, or in the payout chamber 20A and the takeup chamber 20B, to keep the chamber walls clean and free of parasitic deposition. Can also be introduced.

  As is known in the art, the deposition chamber 18 is maintained at a low pressure (eg, for a 1 torr LPCVD process) or atmospheric pressure (eg, for an APCVD process). The deposition chamber 18 includes a plurality of deposition stations 26 disposed adjacent to the path of the web substrate 14. In the illustrated embodiment, only three deposition stations 26 are shown for clarity, but those skilled in the art will appreciate that a different number of deposition stations 26 may be provided. . Each deposition station 26 includes a manifold connected to a precursor gas source 28. Each deposition station 26 supplies the precursor gas in a laminar flow between the manifold and the immediate surface of the web substrate 14 so that the precursor gas reacts near the web substrate surface to deposit a thin film. In some embodiments, one or more precursor gases in the laminar flow are excited by an RF or microwave power source following a plasma enhanced CVD (PECVD) process as is known in the art. .

  Unlike a conventional MOCVD reaction chamber, the precursor gas is introduced to the underside of the substrate 14 as a vertical reverse flow, ie, a gas flow that flows up toward the surface to be coated. As a result, contamination by unwanted by-products of the precursor gas reaction that may occur when the precursor gas is used in a downward flow configuration and other effects on the deposition process do not occur.

  The deposition chamber 18 includes heaters for heating the web substrate 14 during the CVD process. In the illustrated embodiment, a heating module 24, such as a radiant heater, is disposed on the opposite side of each deposition station 26 and proximate to the web substrate 14 so that the web substrate 14 is in the desired process. Heated to temperature. In other alternative embodiments, one or more heaters are in thermal contact with the web substrate 14. One skilled in the art will appreciate that other types of heaters can be used for heating the web substrate 14.

  The transport path of the web substrate 14 passes through the manifolds of the deposition stations 26 one after another so that a single layer of the desired thickness of material is deposited before the web substrate 14 reaches the receiving roller 22B. Is configured to do. More specifically, a thin film of material is deposited on the web substrate 14 as the web substrate 14 passes through the first deposition station 26A. Subsequently, the web substrate 14 passes through the second deposition station 26B, and then passes through the third deposition station 26C, where the second and third thin films of the material are deposited. The The thickness of the deposited material layer when it reaches the receiving roller 22B is the sum of the thicknesses of the individual thin films deposited by the deposition station 26 (s). In some embodiments, the properties of these formed thin films differ between one deposited thin film and the next deposited thin film, from the first deposited thin film to the last deposited thin film. Moreover, the deposition temperature or gas vapor composition at each deposition station 26, or both the deposition temperature and gas vapor composition are different from those at the other deposition stations.

  The deposition chamber 18 may comprise one or more in-situ measurement devices for monitoring the deposited layer that is formed during the CVD process. In some embodiments, a measurement device is placed at a location after each deposition station 26 to characterize the deposited layer.

  FIG. 2A is a diagram illustrating the web substrate 14 passing from left to right between the heater 24 and the manifold 30 of one deposition station 26 according to one embodiment. Each manifold 30 includes a precursor port (port “A”) connected to a source of a first precursor gas and a pair of precursor ports (ports) connected to a source of a second precursor gas. "B1" and "B2"). These precursor gas ports are arranged between two pumping ports (“PUMP1” and “PUMP2”). These pumping ports are connected to an exhaust system for exhausting the precursor gas from the deposition chamber 18. The precursor gas supply source 28 may be provided near the deposition chamber 18 or may be provided at a remote location. The material to be deposited during the CVD process can be changed by connecting the precursor port to another precursor gas source 28. Connections can be made manually at each manifold 30. Alternatively, the precursor gas may be reconfigured by a remotely operated gas distribution valve. As a specific example, one precursor gas can be a zinc compound and the other precursor gas can be oxygen. In this case, the deposited layer is composed of a zinc oxide material doped (added) with aluminum, boron, indium, fluorine, silver, arsenic, antimony, phosphorus, nitrogen, lithium, manganese, or gallium, and is a flat panel display. , Used in the manufacture of light emitting diodes (LEDs), organic LEDs (OLEDs) and solar cells. In order to control the band gap and the cut-off characteristics of the transmitted light wavelength, various concentrations of Mg, Cd, Be, Te, S, and other elements can be mixed with zinc oxide to form an alloy.

  During the CVD process, the web transport system moves the web substrate 14 over the deposition station 26 such that the immediate surface 34 of the web substrate 14 is in close proximity to the precursor port and the pumping port. Here, the gap between the adjacent part of the web substrate and the port (s) of the deposition station is small, for example between 0.3 cm and 5 cm. Desirably, this gap is between 0.5 cm and 1 cm. The first precursor gas flows upward from port A and then substantially laminarly flows along surface 34 and flows through the gap toward each of the pumping ports. The second precursor gas flows upward from the precursor port B1, then flows to the left along the surface 34, and mixes with the portion of the first precursor gas that flows toward the pumping port PUMP1. . Similarly, the second precursor gas flowing upward from precursor port B2 flows to the right along surface 34 and mixes with the portion of the first precursor gas that flows toward pumping port PUMP2. .

  The precursor gas (s) mix and react with each other in the common flow region before being removed through the pump port PUMP (s). Thus, above the manifold 30 of each deposition station 26, there are two regions where a reaction occurs to form a thin film. In general, increasing the precursor gas flow rate increases the deposition rate. The web substrate 14 moves continuously so that the entire web surface 34 passes through these two areas of each deposition station 26 during the CVD process.

  Advantageously, the precursor gas (s) are confined to the vicinity of the surface of the web substrate 14 before being evacuated so that the reaction of the precursor gas is restricted to the surface 34 and its adjacent regions. Mix together. Thus, reaction of the precursor gas in other areas of the deposition chamber is prevented and unnecessary deposition and contamination is avoided.

  An alternative configuration of manifold 40 according to another embodiment of the invention is shown in FIG. 2B. In this configuration, the first purge port “PURGE1” is provided between the port A and the port B1, and the second purge port “PURGE2” is provided between the port A and the port B2. Also, two additional purge ports “PURGE3” and “PURGE4” are provided on opposite sides of the pump port. Each purge port supplies a carrier gas that does not react with the precursor gas. The carrier gas assists in the formation and maintenance of a uniform laminar flow of the precursor gas. The reaction between the two precursor gases occurs in a mixed region, similar to the reaction described above with respect to FIG. 2A.

  FIG. 2C is a diagram illustrating a configuration of a manifold 44 according to still another embodiment of the present invention. In this configuration, one purge port “PURGE” is the central port of the manifold 44. A first pair of precursor gas ports A1 and A2 is disposed around the purge port and supplies a first precursor gas for the laminar flow. A second pair of precursor gas ports B1 and B2 surrounds the purge port and the first precursor gas ports A1 and A2 and supplies a second precursor gas for the laminar flow.

  FIG. 3A is a schematic diagram of a manifold of the deposition station 26 shown in FIG. 1 integrated as a single structure, according to one embodiment of the invention. Each manifold 30 is configured similarly to the configuration described above with reference to FIG. 2A, except that adjacent pump ports of adjacent manifolds 30 are combined into a single pump port. FIG. 3B is a top view of the web substrate 14 passing over the precursor gas port and the pump port shown in FIG. 3A. A rectangle drawn with a broken line indicates a position of a port under the web substrate 14.

  Each precursor port and each pump port has a rectangular shape having a length L slightly larger than the width W of the web substrate 14 so that the deposited layer spreads to the end of the web substrate 14. Each manifold 30 has a region A + B in which two precursor gases are mixed in a laminar flow toward the left, and a second region A + B in which two precursor gases are mixed in a laminar flow toward the right. . As the web substrate 14 moves from left to right, a deposited layer is incrementally formed by the mixed precursor gas regions. Desirably, the flow rate of the gas exiting each precursor gas port is constant along the length L of the port so that the variation in the precursor gas ratio within the laminar mixing region is minimized. This minimizes the non-uniformity of the deposited layer.

  In the illustrated example, each manifold 30 has a sequence configuration of precursor gas ports of the “BAB” format. That is, the precursor gas port B is arranged on both sides of one precursor gas port A. In an alternative embodiment, the one or more manifolds have a precursor gas port configuration of the “ABA” format. In other words, in at least one of the manifolds, the sequence of precursor gases provided by the gas port (s) is “inverted”.

  4A and 4B are a top perspective view and a bottom perspective view, respectively, of one embodiment of an integrated deposition station module 50. FIG. 4C is a cutaway view of the module 50. Module 50 includes three deposition stations 26 integrated as a structure. The manifold has a configuration similar to that shown in FIG. 3A, but each pump port “PUMP” is not composed of a single slot, but is composed of three narrow slots arranged at narrow intervals. Is different.

  Each precursor gas port A or B is supplied from a pair of gas channels 54A or 54B provided at the bottom of the module 50 orthogonal to the length direction of these ports. One pump exhaust plenum 58 provided along the bottom of the module 50 is connected to each of the four positions for the three slots of one pump port. The narrow slot of the pump port ensures that the pressure difference between the outside and inside of the pump exhaust plenum 58 is maintained. As a result, intake is uniformly performed along the length direction of the slot, and a better laminar flow is realized.

  FIG. 5 is a diagram showing an in-line CVD system 80 according to another embodiment of the present invention. The CVD system 80 includes a continuous substrate transport system that transports the individual substrates 92 within the deposition chamber 84. For example, the individual substrate 92 can be glass or a sheet of wafer, such as a semiconductor wafer. The CVD system 80 can be used to process semiconductor wafers in the manufacture of solar cells and devices.

  Individual substrates 92 are loaded into the substrate transport system under atmospheric pressure. The substrate transport system includes a plurality of rollers 88. These rollers 88 directly move the substrates 92 as they pass through the in-line CVD system while maintaining the desired positional relationship of each substrate 92 with respect to other substrates 92 and system components. To support. Alternatively, the substrate 92 may be transported using a carrier (s) each holding one or more substrates 92. The carrier may have one or more openings, each opening having an edge extending continuously around the periphery, or an edge configured in a pin shape. For example, the carrier may be configured as one or more “picture frames”, with one substrate 92 being held by gravity in each of the frames. The substrate 92 is placed on the roller 88 or in the carrier by one or more robotic systems or other automated mechanisms known in the art. In one embodiment, the rollers 88 are operated synchronously and continuously so that the transport rate of the substrate 92 is constant within the in-line CVD system. In another embodiment, the rollers 88 or groups of rollers 88 are controlled independently. For example, the rollers 88 in the load lock chamber 96, described below, may be operated continuously or intermittently at one rotational speed, while the rollers in the deposition system are operated at different rotational speeds. it can. The position of the group (s) of rollers 88 within the load lock chamber 96 and the position of the group (s) adjacent to the deposition station 24 ensure that the "handing" of the rollers 88 to the next group is smooth and stable. As shown in the figure, they are arranged at a narrow interval with respect to each other. In other embodiments, the continuous substrate transport system uses other mechanisms known in the art to control the position of the individual substrate 92 (s) throughout the inline CVD system. For example, a continuous substrate transport system can include one or more controllable lead screw mechanisms.

  Desirably, the walls of the deposition chamber 84 are maintained in a clean state free of parasitic deposits by purge gases introduced at various locations within the chamber 84. The purge gas can also be used to keep the rollers 88 clean during the CVD process.

  The individual substrates 92 pass through a first load lock chamber (or isolation chamber) 96A before entering the deposition chamber 84. The load lock chamber 96A, in conjunction with the gate valve 98A, provides a pressure interface between atmospheric conditions when the individual substrate 92 is loaded into the substrate supply mechanism and the vacuum environment of the deposition chamber 84. In one embodiment, the load lock chamber 96A maintains a pressure below atmospheric pressure and above the vacuum level of the deposition chamber 84. In another embodiment, the load lock chamber 96A is connected to a source of purge gas and a vacuum pump so that a pump and purge cycle can be repeatedly performed during the CVD process.

  The substrate supply mechanism is individually implemented within the deposition chamber 184 such that each substrate 92 advances sequentially in close proximity to the plurality of deposition stations 26 and heaters 24 as described above with respect to the web substrate 14 of FIG. The substrate 92 is transported. The deposition station 26 includes a manifold connected to a precursor gas source 28. The manifold is configured to supply at least two precursor gases in a laminar flow between each manifold and the individual substrate 92. Thus, these precursor gases react to deposit a layer on the substrate surface. Optionally, the precursor gas can be excited using an RF power source to enable a PECVD process as is known in the art. The individual substrates 92 sequentially pass through the deposition station (s) 26 so that a desired thickness of material layer is deposited before the substrate passes the final deposition station 26C.

  After completion of the deposited layer, the processed substrate 92 exits the deposition chamber 84 and enters an output load lock chamber (or isolation chamber) 96B. Load lock chamber 96B and gate valve 98B provide a pressure interface between atmospheric conditions at the unloading station and the vacuum environment of deposition chamber 84. In one embodiment, the load lock chamber 96B operates at a pressure between atmospheric pressure and the pressure in the deposition chamber 84. In another embodiment, the load lock chamber 96B is connected to a source of purge gas and a vacuum pump so that a pump-purge cycle can be performed during the CVD process. After the individual substrates 92 exit the load lock chamber 96B, they are transported to an unloading station (not shown), where continuous substrates are obtained by one or more robotic systems or other automated mechanisms known in the art. Removed from the supply mechanism.

  In the system embodiments described above, and in other embodiments of the in-line CVD system according to the present invention, process parameters such as precursor gas flow rate, substrate temperature and transport rate, pump pumping rate, and deposition chamber pressure are: It can be controlled to define the thickness and other characteristics of the deposited material. The present CVD system can be used for a variety of applications and is suitable for single layer deposition in mass production environments.

  The method of in-line CVD processing according to embodiments of the present teachings can be performed using the system shown in FIG. 1 or FIG. The method includes supplying a first flow of a first precursor gas (A) in a first direction along a surface of a substrate (eg, web substrate 14 or individual substrate 92); Supplying a second flow of body gas (A ′) along a surface of the substrate in a second direction. In the first direction along the surface of the substrate, the first flow of the second precursor gas (B) is mixed with the first flow of the first precursor gas (A). Supplied. The second flow of the second precursor gas (B ′) is mixed with the second flow of the first precursor gas (A ′) along the surface of the substrate. Supplied in the direction. The substrate is exposed to the first flow (A and B) in which the surface of the substrate is first mixed with the first and second precursor gases, followed by the first and second precursor gases. Are transported continuously in the second direction so as to be exposed to the mixed second flow (A ′ and B ′).

  Desirably, the substrate is transported at a constant rate during the CVD process. In some embodiments, the substrate is heated during the deposition process. In other embodiments, the method also includes providing a first flow of carrier gas in a first direction and a second flow of carrier gas in a second direction. The carrier gas is comprised of a gas that does not react with the precursor gas and helps maintain a uniform laminar flow of the precursor gas over the entire surface portion where the deposited layer is formed.

  The in-line CVD method of the present invention in which material is incrementally and sequentially deposited on the substrate allows for high production capacity of CVD-processed web substrates and mass production of CVD-processed individual substrates. The composition of the thin film deposited at each deposition station 26 is substantially the same as the thin film deposited at the other deposition station 26. Various process parameters such as transport rate, precursor gas flow rate, and substrate temperature can be controlled to obtain a high quality deposited layer of the desired thickness.

  Other methods of in-line CVD processing according to embodiments of the present teachings can be performed to produce devices such as solar cells having the device configuration illustrated in FIG. Device 100 includes a substrate 104. The substrate 104 can be an individual substrate or a flexible web substrate. By way of example, the individual substrate can be a glass substrate or a wafer, and the web substrate can be a polyimide or metal foil. The device 100 further includes a metal layer 108, such as a molybdenum layer, an absorbing layer 112, such as copper indium gallium diselenide (CIGS), and a buffer layer (or junction partner layer) 116. And a window layer 120 and a transparent conductive layer 124. For example, the buffer layer 116 may be a cadmium sulfide (CdS) layer, a zinc sulfide (ZnS) layer, or an indium sulfide (InS) layer, and the window layer 120 may be an intrinsic zinc oxide (ZnO) layer. It can be. The transparent conductive layer 124 is an indium tin oxide layer or an impurity-added ZnO layer such as an aluminum-added zinc oxide (AZO) layer, a boron-added zinc oxide (BZO) layer, or a gallium-added zinc oxide (GZO) layer. be able to.

  When using conventional techniques, the buffer layer 116 is typically a thin film layer (eg, 50 nm) produced using a chemical bath deposition (CBD) process, and the thin film ZnO layer 120 (eg, , 50 nm) and the transparent conductive layer 124 is typically deposited using a CVD process. More specifically, the device under manufacture is typically sent from the CBD process to the first CVD process and then to the second CVD process. Such an approach typically takes a long time because the CBD and the two CVD process steps are performed independently.

  In accordance with an embodiment of a CVD method for manufacturing a device in-line based on the principles of the present invention, the process steps for generating a buffer layer, a window layer, and a transparent conductive layer are performed in a common vacuum environment of the deposition chamber. It is executed sequentially. CBD deposition of the buffer layer is not necessary and three separate layers are deposited without transporting between different chambers. Therefore, there is no need to return to atmospheric pressure to be performed when moving to a different CVD deposition process.

  FIG. 7 is a diagram illustrating one embodiment of an in-line CVD system 128 for forming a solar cell device on a web substrate 14. Inline CVD system 128 has components similar to those described above in connection with inline CVD system 10 shown in FIG. However, the group of deposition stations 26 used to generate a single layer of material is shown as a single deposition module 132. For example, each deposition module 132 has one or more manifolds similar to the manifolds shown in FIGS. 4A-4C, and these manifolds in the precursor gas module 136 to form a particular layer of material. Connected to precursor gas supply sources. The layer of material that each deposition module 132 deposits is different from the layer of material that is deposited by the other deposition modules 132. A heating module 140 is located within each deposition module 132 from the opposite side of each manifold or group of manifolds in proximity to the web substrate 14 to heat the web substrate 14 to a desired process temperature.

  In the illustrated example, system 128 is configured to produce a device similar to device 100 shown in FIG. More specifically, the first deposition module 132A is configured to deposit a CdS buffer layer, and the second deposition module 132B is configured to deposit an intrinsic ZnO layer and a third deposition. Module 132C is configured to deposit an AZO layer. The number of manifolds, the flow rate of precursor gas flowing into the manifolds, and the temperature of the web substrate should vary between the deposition modules 132 so that each layer deposited by each deposition module 132 is achieved with a desired thickness. be able to. For example, since the AZO layer has a substantially greater thickness than the CdS buffer layer and the intrinsic ZnO layer, the third deposition module 132C will have a greater length than the first two deposition modules 132A and 132B. (Representing that there are more manifolds).

The system 128 changes the precursor gas supplied to one or more deposition modules 132 and changes other process parameters such as web transport speed, substrate temperature, manifold pump exhaust speed, and deposition chamber pressure. By doing so, it can be reconfigured so that device structures with different material layers can be manufactured. As a specific example, using a first deposition module 132A configured to deposit a ZnS layer or an InS layer and a third deposition module 132C configured to deposit a GZO layer or a BZO layer, CIGS solar cell devices can be manufactured. The system 128 can also be configured to create other device layer structures such as a barrier layer (eg, SiO ₂ or Al ₂ O ₃ ) between the substrate and the backside (molybdenum) contact. When this structure is configured on a glass plate substrate, uncontrolled leakage of sodium from the glass can be prevented. Thereafter, controlled sodium addition is performed on top of the barrier layer. The system 128 can also be adapted to create a configuration with fluorinated ZnO or tin oxide (SnO ₂ ) as a transparent conductive layer for amorphous silicon.

  FIG. 8 is a diagram illustrating an in-line CVD system 140 adapted to fabricate solar cells on individual substrates 92. Inline CVD system 140 has components similar to those described above with respect to inline CVD system 80 shown in FIG. 5, but each group of deposition stations 26 that deposit a common material is shown as one deposition module 132. Has been. The system 140 is configured to form three layers on the individual substrate 92 similar to those deposited on the web substrate 14 in the system 128 shown in FIG. The number of manifolds per deposition station 132, precursor gas type and flow rate, substrate temperature, transport rate, and other process parameters are selected to provide different material layers and layer thicknesses.

  Advantageously, in the system 128 of FIG. 7 and the system 140 of FIG. 8, the device can be fabricated by a continuous CVD deposition process that is all performed in one deposition chamber. As a result, fabrication time and fabrication costs are reduced compared to conventional techniques used to fabricate similar devices.

  FIG. 9 is a flowchart illustrating one embodiment of an in-line CVD method 200 for fabricating a device. Referring also to FIGS. 6 and 8, the method 200 includes transporting the substrate 92 (reference numeral 104 shown in FIG. 6) within the deposition chamber 84 at a constant rate (step 210). The substrate 92 may include the metal layer 108 and the absorption layer 112 shown in FIG. A buffer layer 116 is deposited on the substrate 92 while passing through the first deposition module 132A (step 220). The window layer 120 is deposited on the buffer layer 116 while the substrate passes the next deposition module 132B (step 230), and the transparent conductive layer 124 is passed through the third deposition module 132C by the substrate 92. In the meantime, it is deposited on the window layer 120 (step 240). The buffer layer 116, the window layer 120, and the transparent conductive layer 124 can be any of a variety of materials, as described above in connection with manufacturing using the in-line CVD system shown in FIGS.

  Although the method 200 has been described in connection with processing an individual substrate 92 according to the system 140 of FIG. 8, it is understood that other embodiments of an in-line CVD method of fabricating a device in accordance with the principles of the present invention are possible. It will be. For example, a supplemental embodiment for the method 200 of FIG. 9 relates to fabricating a device on a web substrate using, for example, the system 128 of FIG.

  While the invention has been illustrated and described in connection with specific embodiments, those skilled in the art will understand the form and details without departing from the spirit and scope of the invention as defined in the appended claims. It will be understood that various modifications of are possible.

Claims (34)

An in-line chemical vapor deposition method for fabricating a device comprising:
Transporting the substrate in a deposition chamber having a vacuum environment and comprising a first deposition module, a second deposition module, and a third deposition module;
Depositing a buffer layer on the substrate during transport of the substrate in the first deposition module;
Depositing a window layer on the buffer layer during transport of the substrate in the second deposition module;
Depositing a transparent conductive layer on the window layer during transport of the substrate in the third deposition module;
Having a method.   The method of claim 1, wherein each of the deposition modules comprises at least one deposition station having a manifold with a plurality of ports connected to a plurality of precursor gas sources.   The method of claim 1, wherein the substrate is transported through the deposition chamber at a constant rate.   The method of claim 1, wherein the substrate comprises a metal layer and an absorbent layer prior to passing through the first deposition module.   The method of claim 4, wherein the absorbing layer comprises a copper indium gallium diselenide layer.   The method of claim 1, wherein the substrate is a discrete substrate.   The method of claim 6, wherein the individual substrate is a glass substrate.   The method of claim 6, wherein the individual substrate is a wafer.   Transporting the individual substrates within the deposition chamber includes transporting a plurality of individual substrates within the deposition chamber, wherein at least one of the individual substrates is transported simultaneously within each of the deposition modules. The method according to claim 6.   The method of claim 1, wherein the substrate is a web substrate. In order to separate the first, second and third deposition module from each other, between the first deposition module and the second deposition module and between the second deposition module and the third deposition module. Flowing gas to and from the module,
The method of claim 1, further comprising:   The port of each manifold includes a first precursor port, a second precursor port pair, and a pumping port pair, the first precursor port being disposed between the second precursor ports. The second precursor port pair is disposed between the pumping ports, and the first precursor port and the second precursor port pair are respectively a source of a first precursor gas. And a second precursor gas source, and the pumping port is configured to connect to an exhaust system for exhausting the first and second precursor gases. The method described in 1.   The method of claim 1, wherein the buffer layer comprises one of a cadmium sulfide layer, a zinc sulfide layer, and an indium sulfide layer.   The method of claim 1, wherein the window layer comprises an intrinsic zinc oxide layer.   The method according to claim 1, wherein the transparent conductive layer includes one of an aluminum-added zinc oxide layer, a gallium-added zinc oxide layer, a boron-added zinc oxide layer, and an indium tin oxide layer. An in-line chemical vapor deposition method for fabricating a device comprising:
Transporting a substrate having a metal layer and an absorber layer at a constant rate within a deposition chamber, comprising:
The deposition chamber has a vacuum environment and includes a first deposition module, a second deposition module, and a third deposition module;
Each of the deposition modules comprises at least one deposition station comprising a manifold having a first precursor port, a pair of second precursor ports, and a pair of pumping ports;
The first precursor port is disposed between the second precursor ports and the second precursor port pair is disposed between the pumping ports;
The first precursor port and second precursor port pair are configured to connect to a first precursor gas source and a second precursor gas source, respectively;
The pumping port is configured to connect to an exhaust system for exhausting the first and second precursor gases;
Steps,
Depositing a buffer layer on the substrate during transport of the substrate in the first deposition module;
Depositing a window layer on the buffer layer during transport of the substrate in the second deposition module;
Depositing a transparent conductive layer on the window layer during transport of the substrate in the third deposition module;
Having a method.   The method of claim 16, wherein the absorbing layer comprises a layer of copper indium gallium diselenide.   The method of claim 16, wherein the substrate is a discrete substrate.   The method of claim 18, wherein the individual substrate is a glass substrate.   The method of claim 18, wherein the individual substrate is a wafer.   Transporting the individual substrates within the deposition chamber includes transporting a plurality of individual substrates within the deposition chamber, wherein at least one of the individual substrates is transported simultaneously within each of the deposition modules. The method of claim 18.   The method of claim 16, wherein the substrate is a web substrate.   The method of claim 16, wherein the buffer layer comprises one of a cadmium sulfide layer, a zinc sulfide layer, and an indium sulfide layer.   The method of claim 16, wherein the window layer comprises an intrinsic zinc oxide layer.   The method according to claim 16, wherein the transparent conductive layer includes one of an aluminum-added zinc oxide layer, a gallium-added zinc oxide layer, a boron-added zinc oxide layer, and an indium tin oxide layer. An in-line chemical vapor deposition system,
A deposition chamber;
A continuous transport system for transporting the substrate along a path through the deposition chamber;
A first deposition module disposed on a path in the deposition chamber and comprising at least one deposition station for depositing a buffer layer on the substrate;
A second deposition module disposed on a path in the deposition chamber and comprising at least one deposition station for depositing a window layer on the buffer layer;
A third deposition module disposed on a path in the deposition chamber and comprising at least one deposition station for depositing a transparent conductive layer on the window layer;
With
Each of the deposition modules comprises at least one deposition station comprising a manifold having a first precursor port, a pair of second precursor ports, and a pair of pumping ports;
The first precursor port is disposed between the second precursor ports and the second precursor port pair is disposed between the pumping ports;
The first precursor port and second precursor port pairs are configured to be connected to a source of a first precursor gas and a source of a second precursor gas, respectively;
The pumping port is configured to connect to an exhaust system for exhausting the first and second precursor gases;
system.   27. The in-line chemical vapor deposition system according to claim 26, wherein the substrate is an individual substrate.   28. The in-line chemical vapor deposition system according to claim 27, wherein the individual substrate is a glass substrate.   28. The in-line chemical vapor deposition system according to claim 27, wherein the individual substrate is a wafer. The continuous transport system is configured to transport a plurality of individual substrates along a path through the deposition chamber;
At least one of the individual substrates is transported simultaneously in each of the deposition modules;
The in-line chemical vapor deposition system according to claim 27.   27. The in-line chemical vapor deposition system according to claim 26, wherein the substrate is a web substrate.   27. The in-line of claim 26, wherein the at least one deposition station of the first deposition module is configured to deposit one of a cadmium sulfide layer, a zinc sulfide layer, and an indium sulfide layer on the substrate. Chemical vapor deposition system.   27. The in-line chemical vapor deposition system of claim 26, wherein the at least one deposition station of the second deposition module is configured to deposit an intrinsic zinc oxide layer.   The at least one deposition station of the third deposition module is configured to deposit one of an aluminum-doped zinc oxide layer, a gallium-doped zinc oxide layer, a boron-doped zinc oxide layer, and an indium tin oxide layer; The in-line chemical vapor deposition system according to claim 26.

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