System and method for vacuum deposition
By combining a magnetic substrate carrier and a mask, the problem of unstable mask positioning during deposition on the substrate is solved, achieving efficient and precise pattern deposition, which is suitable for solar cell production and improves production efficiency and quality.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- 梅耶博格(德国)有限公司
- Filing Date
- 2024-12-04
- Publication Date
- 2026-07-10
AI Technical Summary
In the prior art, it is difficult to achieve close fit and stable positioning of the mask during the deposition process on the substrate, resulting in unclear pattern boundaries and easy relative movement during transportation, which affects the deposition quality and efficiency.
A magnetic substrate carrier and mask are used, and the mask is fixed to the substrate by a magnetic field to ensure a tight fit and stable positioning during transportation and deposition. Magnetic materials such as ferromagnetic materials and permanent magnets are used to achieve precise pattern deposition.
It achieves a tight fit between the mask and the substrate, reduces pattern boundary trailing, improves deposition quality and efficiency, is suitable for high-throughput solar cell production, and reduces the risk of mechanical damage and mask waste.
Smart Images
Figure CN122374493A_ABST
Abstract
Description
[0001] This invention relates to a layer deposition system, particularly for depositing at least one localized layer in a plasma-assisted deposition system via a mask that partially obscures a substrate on a substrate carrier, particularly a solar cell. The invention also relates to a method for depositing a localized layer in a plasma-assisted deposition system, wherein the deposition system includes a substrate carrier designed to carry: at least one substrate, particularly a solar cell; and at least one magnetic mask covering the at least one substrate in at least one deposition station, wherein the method includes at least one deposition step in which at least one film is deposited on a localized region of the substrate in which the mask has an opening.
[0002] Vacuum processes are widely used for thin film deposition, such as for depositing silicon layers in amorphous, nanocrystalline, microcrystalline, or polycrystalline states. Silicon-containing gases (e.g., SiH4) are typically used for these layers. Hydrogen can be added to the process gas to improve defect passivation.
[0003] Vacuum deposition processes are typically performed in a reactor chamber at low pressures ranging from approximately one Pa to several thousand Pascals. Deposition can be achieved through evaporation, sputtering, or gas decomposition. The latter process can be achieved through radio wave plasma excitation (also known as PECVD (plasma-enhanced vapor deposition)) or thermal decomposition on a hot surface. These processes can be carried out at elevated temperatures ranging from 100 to 300 °C.
[0004] In certain technologies (e.g., interdigitated back contacts for silicon heterojunction solar cells), it is necessary to deposit localization layer patterns on a substrate. It is known to deposit localized silicon structures on a silicon wafer, which serves as the substrate, using a shadow mask. For example, patent application EP3886185 describes how localized silicon structures can be deposited on a silicon wafer substrate using mechanical masking.
[0005] DE 10 2018 123 523 A1 describes a basic idea in which a mask frame can support interchangeable mask elements in a coating system. However, based on this patent application, these ideas are not feasible because the document does not answer important questions such as how to achieve sufficiently reliable use of the mask or how to achieve sufficient mechanical stability of the mask elements.
[0006] The purpose of this invention is to demonstrate a solution for the masking film deposition process that addresses the problems described above, as well as a suitable machine for the production of industrial solar cells.
[0007] It has been found that in order to obtain a clean structure with defined edges and no trailing in vacuum processes, it is important to make the shadow mask fit tightly to the substrate surface.
[0008] At the same time, it is also important that the movement between the mask and the substrate be minimized, even when the substrate and mask are transported from the loading station to the deposition chamber.
[0009] This problem is solved by a layer deposition system designed, particularly for depositing at least one localized layer in a plasma-assisted deposition system. The layer deposition system includes a movable substrate carrier for receiving at least one solar wafer substrate, the movable substrate carrier being designed for transporting at least one substrate and at least one mask for masking the substrate between a loading station and a deposition station. The movable substrate carrier and / or the mask are magnetically connected. The substrate and the mask on the substrate carrier can be arranged in a mutually aligned manner, and the mask is magnetically attached by the magnetic field.
[0010] The mask may optionally or additionally have permanent magnetic properties and exhibit a magnetic field, especially in the application area where the temperature is below the temperature resistance of the magnet.
[0011] Magnetic materials (especially ferromagnetic materials) used for masks have proven to provide an advantageous solution for these purposes. Using a substrate carrier with a magnetic field, a magnetic shadow mask can be fixed to the substrate and substrate carrier. This prevents relative movement between the substrate carrier, the substrate, and the mask during transport and deposition, and the mask fits snugly against the substrate. The substrate and mask are placed in defined, designated locations; specifically, the mask is perfectly aligned with the substrate. This arrangement or positioning allows for the production of electronic structures, such as the contact structure of an IBC solar cell (the abbreviation IBC stands for "Interdigitated Back Contact"). Positioning requirements include tolerances below the allowable position. The maximum permissible tolerance is in the range of 1 mm, but is typically much lower, for example, 0.5 mm or 0.2 mm. If several depositions are performed sequentially using the mask, the permissible tolerance between the position of the previous mask and the position of the currently used mask can be less than the permissible tolerance of the first mask position relative to the substrate position. To achieve sufficiently accurate positioning within the permissible tolerances, functional regions (especially the base or emitter regions of a solar cell) generated via the mask, as well as special position marks used only for mask positioning, can be used.
[0012] Another advantage of the proposed solution is that the mask conforms uniformly to the substrate. Magnetic adhesion is well-suited for this purpose because it allows the preferably thin mask to be pressed onto the substrate with a uniformly distributed force, exceeding the force exerted by gravity alone. The solution according to the invention, utilizing a thin and lightweight mask, requires no mechanical aids (such as clamps or frames). Therefore, the solution is simple and inexpensive, especially when the machinery required for automated processing is also taken into account.
[0013] Layer deposition systems used to coat solar wafers (which are used to manufacture solar cells) are highly automated machines in the solar energy industry. Such machines require high throughput (typically several thousand substrates per hour). Simultaneously, the manufactured solar cells must be highly efficient; therefore, the area of the solar wafer must be utilized as fully as possible. Furthermore, high yield is required; waste due to mask usage (e.g., due to mask slippage) must be almost completely avoided. Experts who build such layer deposition systems and automate them can use their expertise to ensure that the substrates are loaded onto the substrate carrier with precise positioning, and that the masks are loaded onto and secured to the substrates with precise positioning. Common substrates currently used include square or pseudo-square solar wafers with side lengths in the range of 182 mm or 210 mm, or, for example, split solar wafers with dimensions of 182 mm x 91 mm. The thickness of the Si solar wafer during alignment is typically between 100 µm and 200 µm. Besides solar wafers, other substrates similar to solar wafers (e.g., glass wafers, or thin-film solar cells on glass substrates) can also be coated using such coating systems. Another important requirement for machines used to manufacture solar cells is that the cost per coated substrate must be very low; this requirement excludes the possibility of using expensive machine solutions with different price requirements in other technical fields.
[0014] Contrary to experts’ concerns that the magnetic field of the substrate carrier might interfere with the magnetic field and / or ions that define the plasma deposition process, surprisingly no such negative effects were observed.
[0015] Magnetically attached masks prevent relative movement between the substrate carrier, the substrate, and the mask, thereby minimizing or preventing mechanical damage to the substrate. This is particularly important for already passivated silicon wafers, such as crystalline silicon wafers passivated by an intrinsic amorphous silicon layer for silicon heterojunction solar cells.
[0016] The close fit between the mask and the substrate enables precise pattern deposition with virtually no trailing at the pattern boundaries.
[0017] There are various ways to realize a magnetic field on a substrate carrier.
[0018] Electrical coils can be integrated into the substrate carrier and activated by supplying current. This means that a power source must be connected to the substrate carrier during transport and processing. The electrical coils can be used to turn the magnetic field on and off as needed.
[0019] One possible solution is to integrate permanent magnets into a substrate carrier in a specific pattern to secure the magnetic mask to the substrate and the substrate carrier. These permanent magnets can be manufactured as flat magnets in circular, rectangular, or any other shape. The thickness of the magnets can range from 0.1 to 2 mm. The lateral dimensions of the magnets can range from 5 mm to 200 mm. The material of the permanent magnets should be selected so that it can withstand processing temperatures from 100 to 300 °C. For this purpose, for example, samarium-cobalt alloy-based magnets can be used.
[0020] Another solution is to integrate one or more ferromagnetic plates into a substrate carrier, the plates being composed of a magnetizable material and magnetized to a specific magnetic field strength. The material used for this purpose should have high remanence to maintain the magnetic field across multiple processes. For example, an FeAlNiCo alloy of iron with aluminum, nickel, and cobalt is a material with high remanence. However, other ferromagnetic steels with high remanence and high coercive magnetic field strength can also be used. For example, carbon steel and chromium steel exhibit sufficiently large hysteresis curves in their magnetic behavior and will be used for this purpose in exemplary embodiments.
[0021] Another possible solution is to generate a magnetic field on the substrate carrier by using a magnetizable material on the substrate carrier itself. The substrate carrier is magnetized before use (at least in the area where the magnetic mask is placed on the substrate carrier). For this purpose, a substrate carrier made of a material with high remanence can be used (as described above for integrated boards).
[0022] The orientation of a magnetic field can be unidirectional, meaning that the north or south poles of a magnet or multiple magnets point in one direction (e.g., up or down).
[0023] A magnetic field (with one polarity or the other) can be advantageously guided to the mask.
[0024] Magnetic fields can also be realized in the form of one-dimensional or two-dimensional patterns. Patterns can be achieved through localized changes in magnetic field strength or changes in polarity.
[0025] Magnetic patterns can be achieved through local field intensity fluctuations, either caused by the positioning of individual magnets with specific spacing patterns, or by the local magnetization of a magnetizable substrate or a magnetizable plate attached to the substrate.
[0026] The pattern can be a magnetic field with locally different polarities. Individual magnets can be attached to the substrate in rows with different polarities, wherein, for example, the north poles of the first row of magnets point to a first direction, and the north poles of the second row of magnets point to a second direction opposite to the first direction.
[0027] In some variations, adjacent magnets or magnetized regions in a magnetizable plate have opposite polarities.
[0028] The magnetic field strength measured on the surface of the substrate carrier facing the substrate and the side on which the mask is attached can range between 5 and 100 mT (millitales). The magnetic field strength can advantageously be adjusted according to the thickness of the substrate and / or the mask. This allows for adjustment of the force pulling the mask against the substrate, ensuring that the mask conforms uniformly to the substrate on the one hand, and that the mask can be removed without mechanical overload on the other.
[0029] The substrate carrier may be provided with reference marks and alignment marks or pins to achieve repeatable alignment of the substrate and the mask.
[0030] Magnetic shadow masks (sometimes referred to simply as masks in the following description) (which are held in place, for example, by the magnetic force of a magnetic substrate carrier) can be made of any magnetic material, especially ferromagnetic materials.
[0031] Shadow masks are designed in various implementations as masks for a single substrate or masks for multiple substrates.
[0032] For ease of processing in automated systems, masks with no magnetic field or a low magnetic field of less than 5 mT are preferred. Therefore, ferromagnetic materials (also known as soft magnetic materials) with low remanence or low coercive magnetic field strength are preferred for mask manufacturing.
[0033] It has been found that masks made of Invar alloy (an alloy of approximately 64% to 68% iron and approximately 32% to 36% nickel) represent a preferred material solution. Invar alloy has low remanence and a coefficient of thermal expansion close to that of silicon (Invar alloy: approximately 1.6E-6K⁻¹; silicon: approximately 2.6E-6K⁻¹). This latter property is also important when heated from room temperature of approximately 20°C to process temperatures of 100 to 300°C. In an exemplary embodiment used in the fabrication steps of HJT solar cells, the similar coefficients of thermal expansion of the Invar alloy mask and the silicon substrate reduce the risk of mechanical damage to the passivation layer due to relative movement between the mask and the substrate during heating and cooling cycles.
[0034] Masks can also be coated to protect them from corrosion or mechanical damage. This coating can help extend the lifespan of the mask. This is particularly helpful for removing residual deposited material from the mask during the deposition process. The residual material can be removed, for example, in a chemical etching bath or a plasma-assisted vacuum etching process. The coating can be made of any material that can withstand the removal process. For chemical etching, a metal coating based on nickel (Ni) or chromium (Cr) can be used. Alternatively or additionally, a coating with a filled or purely fluorinated polymer can be applied. In plasma etching processes (e.g., fluorine-based plasma etching processes), a coating with a material such as aluminum or nickel can protect the ferromagnetic base material of the mask.
[0035] The mask can be the same size as the substrate to be masked. The mask can have a larger dimension in at least one direction (X, Y). The mask can also have a smaller dimension in at least one direction (X, Y).
[0036] The mask may also have alignment marks or openings to align the mask with the wafer substrate and / or substrate carrier.
[0037] A deposition system for localized deposition of layers on a substrate has at least one deposition chamber and at least one magnetic substrate carrier.
[0038] The deposition system may also include a loading station where substrates and masks can be loaded onto and unloaded from a magnetic substrate carrier.
[0039] Magnetic substrate carriers can be used to transport substrates with shaded masks placed on them from loading stations to coating chambers.
[0040] In these cases, loading stations are designed to allow for the loading and unloading of masks and substrates. Typically, in industrial layer deposition systems used in solar cell production lines, loading stations are equipped with automated loading equipment. Loading and unloading can be performed separately and sequentially for masks and substrates, or alternatively as a single process for assembling substrate masks.
[0041] A coating chamber is used to house a substrate carrier containing the substrate and a shadow mask during masked deposition of layers on a substrate. The coating chamber is typically a vacuum chamber equipped with a vacuum pump or vacuum pumping system to generate a specific pressure range used during layer deposition. The coating chamber also has means for depositing the layers. The latter can be achieved using an evaporation source activated by thermal heating or by electronic or ionic heating. Alternatively, deposition can be performed using sputtering processes, such as in magnetron sputtering. In other examples, deposition is performed via gas decomposition, which can be either chemical vapor deposition (CVD) (e.g., catalytic hot filament deposition) or plasma-enhanced vapor deposition (PECVD) (where plasma is generated by discharge to support chemical vapor deposition).
[0042] The deposition chamber is also partially equipped with a process gas inlet system to provide the necessary process gases for layer deposition. The deposition chamber may also provide a device for generating plasma to activate the process gas materials used for layer deposition.
[0043] Additionally, the deposition system may be equipped with a loading lock chamber, which allows the magnetic substrate carrier to be transported from the loading station to the deposition chamber without interrupting the vacuum in the deposition chamber.
[0044] The coating system can also be equipped with heating elements (even within the coating chamber) to generate elevated temperatures between 80 and 250°C for processing the substrate. Heating elements can also be installed in other areas of the layer separation system, for example, to preheat the substrate carrier at the loading station and / or loading locking chamber.
[0045] The present invention also includes a method for depositing a localized layer in a plasma-assisted deposition system, wherein the deposition system includes a substrate carrier designed to carry at least one substrate (particularly a solar wafer) and at least one mask covering the at least one substrate in a deposition station, wherein, prior to the deposition step, at least one substrate and at least one mask are positioned and magnetically attached to the substrate carrier in a loading step, wherein the substrate carrier thus loaded is then transported to the deposition location, wherein, during transport and during the deposition step, the substrate carrier and / or the mask emit magnetic fields to hold the substrate and mask in proper position on the substrate carrier. Industrial coating systems in the solar energy industry (such as PECVD coating systems) are equipped with large coating chambers for high machine throughput, in which many substrates can be coated in a short time. For cost and speed reasons, the volume of the separation chamber is designed to be minimized. Therefore, there is almost no space in such coating chambers to achieve mask positioning application. A large space exists outside the coating chamber (e.g., in the loading area), making the positioning of the mask onto the substrate carrier with the substrate a task that experienced automated machine manufacturers can skillfully handle. Due to magnetic attachment, the mask remains in place during transport to the separation point or into the separation chamber, and during the subsequent separation process there. Localized coatings can be applied to designated substrate surface areas through openings in the mask, resulting in a high-quality product at the end of the manufacturing process.
[0046] The substrate carrier in the deposition system can be moved between at least two deposition stations and at least two deposition steps. The substrate carrier, with a mask, can be transported between loading and deposition stations. The loading station can be a loading station, unloading station, and / or transfer station. Transport can be carried out via an intermediate station through which the substrate carrier is moved to one or more stations, and the intermediate station allows for temperature control of the substrate carrier and / or the substrate and / or the mask. Temperature control allows for setting specific temperature ranges. The temperature range can be set, for example, between 100 and 300°C, preferably between 150 and 250°C. This temperature range is also used for depositing amorphous silicon layers and microcrystalline or nanocrystalline silicon layers for the production of heterojunction solar cells.
[0047] The method according to the invention can be carried out in various forms. In one chamber, several coatings can be deposited sequentially on the same mask (e.g., deposition of an intrinsic amorphous silicon passivation layer (i-aSi) followed by a nanocrystalline phosphorus-doped surface field layer (n-ncSi) on an n-doped crystalline Si solar cell). However, coatings can also be distributed to at least two coating chambers, with a substrate carrier holding the substrate and mask sequentially approaching the at least two coating chambers. Dedicated masks can also be used for specific coating chambers, whereby the substrate is bonded to dedicated components before the coating step and separated from them again after the coating step. The coating process may include corresponding loading and unloading steps.
[0048] For example, an intermediate station is a transfer station in which a substrate carrier containing a substrate and a mask is transported between a deposition station and a loading station under vacuum. The transfer station may also be equipped with facilities capable of temperature control of the substrate carrier. The transfer station may also consist of several separate stations in which temperature control and / or venting or ventilation are performed in several stages. In other examples, the intermediate station is: a pretreatment station for surface finishing prior to coating; a post-treatment station for post-treatment of the deposited layer; a measurement station; an intermediate storage facility; and / or others.
[0049] In the layer deposition system according to the invention, the mask can have a foil-like shape, which is used in the layer deposition system without a frame. The attribute "foil-like" describes that one dimension of the mask (i.e., its thickness) is smaller than other dimensions (length and width). This attribute also indicates that the mask has relatively low mechanical stiffness. Although the mask has a foil-like shape, it does not require a frame; it does not need to be stretched within a frame because magnetic holding forces prevent the mask from deforming (e.g., due to layer stress). The foil-like shape provides the following practical advantages: the mask can also be used in coating chambers with minimal dimensions, and the small mask volume also results in low mask weight and correspondingly low mechanical requirements for the coating system.
[0050] The method of this invention is specifically designed for producing localized layers for manufacturing so-called IBC (IBC = interdigitated back contact) solar cells. In this process, portions of the layer are deposited onto a substrate composed of a silicon wafer through a mask. The layer portions are particularly composed of amorphous silicon and / or microcrystalline silicon and / or nanocrystalline silicon.
[0051] From a process engineering perspective, producing local structures (such as the base and emitter contact structures of IBC solar cells) via a shadow mask is a very simple solution because the desired structure already exists immediately after coating. Alternative manufacturing options (such as full surface coating, photoresist coating, photolithography, etching on a photoresist mask, and photoresist ashing) are more complex and expensive.
[0052] In the fabrication process for heterojunction IBC solar cells, several amorphous and / or nanocrystalline and / or microcrystalline layers are deposited onto a crystalline silicon wafer. Various electrical and optical properties of these layers can be tuned via crystallinity. The resulting crystallinity of the deposited layers depends not only on deposition parameters (e.g., pressure, gas composition, plasma power, frequency, temperature) but also, in part, on the locally different substrate surfaces. In some cases, these layers can also be produced as graded layers or multilayers. For cost reasons, the number of different masks used is typically limited to a minimum. If possible, the intrinsic amorphous passivation layer and the nanocrystalline or microcrystalline doped surface field layer are deposited sequentially using the same mask.
[0053] The method according to the invention can be used to deposit a pattern of doped silicon layers onto a silicon substrate in at least one corresponding deposition step. The pattern, for technical purposes, may have a repeating structure (such as black and white squares on a chessboard).
[0054] Such patterns can be used to locally deposit these layers on designated connection surfaces, where these layers contribute to the formation of locally adjacent base and emitter connection surfaces in an IBC solar cell. A solar cell is a bipolar device with a positive and a negative electrode. In a conventional bifacial solar cell, the two electrodes are located on opposite sides of the solar wafer; for example, the entire front side of the solar wafer is the negative and base electrode, and the entire back side of the solar wafer is mostly the emitter electrode. In an IBC solar cell, both the negative and positive electrodes are located on the back side of the solar wafer, where offset patterns of correspondingly coated negative and positive connection regions are connected to ultimately form the negative and positive electrodes in the solar module. The entire solar wafer is typically composed of the semiconductor material silicon, where electron-hole pairs are generated by photons from solar radiation. Thus, in the n-doped base, electrons are connected to the negative terminal of the solar cell via the base connection region, the metal contacts located thereon, and the connection leads attached thereto. Positively charged holes are therefore connected to the positive terminal of the solar cell via the emitter connection region.
[0055] The process according to the invention can be at least one deposition step in an IBC solar cell manufacturing process, in which at least one amorphous silicon layer and / or at least one nanocrystalline silicon layer and / or at least one microcrystalline silicon layer or silicon alloy layer is deposited on a crystalline silicon solar wafer. Such solar cells are also referred to as heterojunction solar cells because the pn junction is realized by materials with different electronic properties, i.e., on the one hand by a crystalline wafer, and on the other hand by deposited layers with different crystallinity and correspondingly different electrical properties. The base junction region and the emitter junction region are preferably each coated with at least two layers, i.e., typically an intrinsic amorphous layer for passivating the wafer surface, and a highly doped layer that collects majority or minority carriers from the absorber layer according to its polarity, and thus promotes the desired carrier separation in the solar cell. Depending on the different coatings, several masks can be used, and a single mask can also be used for several depositions, as long as the same deposition pattern is required in the deposition results.
[0056] In a preferred embodiment, the method according to the invention can be embedded in a particularly efficient manufacturing process for IBC heterojunction solar cells, wherein a pattern of a first type of doped layer is generated on the back side of a silicon wafer substrate by means of a magnetically attached shadow mask. Prior to generating the pattern of the first type of doped layer, a passivation layer is deposited on the entire surface of the back side of the silicon wafer substrate, the passivation layer preferably consisting of an intrinsic, at least partially amorphous silicon layer. A second type of doped layer and the pattern of the first type of doped layer are deposited on the entire surface of the passivation layer. In a further step, a conductive contact structure adjusted according to the pattern is created. A first polarity contact is located in the region of the layer structure created by the mask. A second polarity contact is electrically isolated from the first polarity contact and is located outside the region of the first polarity defined by the mask. This manufacturing process is particularly short and therefore cost-effective.
[0057] Various embodiments of the present invention will be explained below with reference to the accompanying drawings and illustrations.
[0058] image:
[0059] Figure 1 The magnetic field emission substrate carrier, the wafer substrate, and the ferromagnetic mask are shown in a top view.
[0060] Figure 2 The side view shows the substrate carrier, wafer substrate, and ferromagnetic mask that generate the magnetic field.
[0061] Figure 3 Another substrate carrier is shown, which generates a magnetic field and is designed to accommodate more than one substrate and a ferromagnetic mask.
[0062] Figure 4The side view shows a cross-section through various substrate carriers, each with a different magnetic field and integrated individual magnets with different orientations and positions.
[0063] Figure 5 A side view shows a cross-section through various substrate carriers, each having an integrated magnetization plate indicating magnetic poles.
[0064] Figure 6 Cross-sections of various magnetizable substrate carriers made of magnetizable materials are shown through the magnetic poles.
[0065] Figure 7 , Figure 8 and Figure 9 Some of the different possibilities for the two-dimensional arrangement of the magnetic poles of the substrate carrier are shown.
[0066] Figure 10 A PECVD system is shown, which is used to deposit layers by means of a mask magnetically attached to a substrate carrier.
[0067] Figure 1 A substrate carrier 1 is shown, which emits a magnetic field and is designed to house a single wafer-shaped substrate 2 and a single ferromagnetic mask 3 for layer deposition through the mask 3. The substrate carrier here has alignment aids 6 to align the substrate 2 and the mask 3 in areas provided for this purpose. In the illustrated embodiment, the alignment aids 6 consist of needle-like structures in the substrate carrier for mechanical alignment. In other embodiments not shown, the alignment aids are optical marks for visual or optical alignment of the substrate 2 and the mask 3.
[0068] Figure 2 The stack consisting of a magnetic substrate carrier 1 (with alignment aid 6), a wafer-like substrate 2 (specifically referring to half a solar cell) and a ferromagnetic shadow mask 3 is schematically shown in a side view. The magnetic poles of the substrate carrier are marked with the letters N (representing the North Pole) and S (representing the South Pole).
[0069] Figure 3 A magnetic substrate carrier 1 is shown for holding more than one substrate (here, a square solar cell). Alignment aids 6 are used to align the substrates at their individual locations. In one embodiment, masking is achieved with a separate mask for each substrate, or in other embodiments, masking is achieved with a mask covering more than one substrate. In an advantageous solution, a single mask is used to mask all substrates arranged on the substrate carrier 1.
[0070] Figure 4Different embodiments of the magnetic substrate carrier 1 are schematically illustrated. Individual magnets 4 are integrated at localized locations on the base plate 8. The magnets 4 are inserted into openings in the base plate 8 from either the top 9 or the bottom of the substrate carrier 1. In the illustrated embodiments, the magnets 4 are spaced apart in a first embodiment counting from the top, or arranged in a densely packed arrangement adjacent to each other in a second embodiment. Viewed from above, the supporting base plate 8 in the third embodiment consists of an upper portion 8a and a lower portion 8b to integrate the magnets 4 within the interior of the substrate carrier 1. In a fourth embodiment, the magnets 4 are inserted from below into recesses provided for this purpose in the base plate 8.
[0071] Figure 5 Different variations of the substrate carrier 1 are shown, in which the integration of the magnetic plate 5 into the carrier base plate 8 varies. In the example shown, the magnetic plate 5 is unipolar magnetized, having one pole on one side and an opposite pole on the opposite side. An embodiment of the substrate carrier, not shown, designed to hold more than one substrate and more than one mask, has a single magnetic plate for attaching individual masks to their respective substrates. In the lowest embodiment shown, two separate magnetic plates 5 are integrated into the support base plate 8.
[0072] Figure 6 Three embodiments of the magnetic support base plate 8 are shown in cross-sectional side views. In these three embodiments, the magnetizable material of the support base plate 8 is magnetized in different ways, thus forming different support base plates 13, 14, and 15. In addition to the base plate 8, the substrate carrier 1 may also have additional elements (not shown here for clarity). The uppermost support base plate 8 is unipolar magnetized, with its magnetic polarity on one side of the support base plate 13. The base plate 14 is magnetized such that the polarity on one side of the base plate 14 changes in an alternating pattern. In the embodiments of the two upper support base plates 13 and 14, the substrate carrier 1 is only partially magnetized, i.e., in each case, in the area where the mask is attached to the substrate. The substrate carrier 1 of the lowermost depicted support base plate 15 is magnetized over its entire periphery. In embodiments not shown, the size of the magnetized area differs from that shown.
[0073] Figure 7 A top view shows the two-dimensional magnetic polarity pattern of the substrate carrier 1, in which all the north poles of the magnet or magnetization plate 5 or magnetization support base plates 13, 15 point to one side, that is, to the side shown in the view.
[0074] Figure 8 A top view shows a magnetic substrate carrier 1 with a two-dimensional magnetic polarity pattern, wherein the polarity changes in a row pattern and the north and south poles are aligned in rows pointing towards the substrate side.
[0075] Figure 9 A top view shows a magnetic substrate carrier 1 with an additional polarity pattern, which alternatively shows the north and south poles from the magnets to the magnet-to-substrate side. This pattern is typically also produced when the substrate carrier 1 or the support plate 8 is magnetized with locally distributed magnetizing magnets or induction coils. The advantage of this preferred pattern is that the resultant force of all the individual magnets is small, making the mask processing correspondingly easier.
[0076] Figure 10 A PECVD coating system 10 is described, which is used to locally apply layers to a substrate 2 by means of a shadow mask or mask 3. The illustrated PECVD coating system 10 has: a loading station 11 for loading the substrate 2 and mask 3 onto a magnetic substrate carrier 1; and a PECVD deposition chamber 12 for depositing layers onto the magnetic substrate carrier 1, and particularly onto the substrate disposed on the magnetic substrate carrier and onto the mask positioned above the substrate. Here, the loading and unloading of the substrate carrier 1 is performed at the loading station 11; in other embodiments not shown, the layer deposition system has a loading station and an additional unloading station. Those skilled in the art will recognize that the PECVD coating system 10 has many other components, of which only the RF generator 16, vacuum pump 17, and gas supply 18 are illustrated here as examples.
[0077] Figure Labels
[0078] 1. Magnetic substrate carrier
[0079] 2 substrate
[0080] 3. Mask (ferromagnetic)
[0081] 4. Magnets
[0082] 5 magnetized plates
[0083] 6 Alignment aids
[0084] 8 Support base plate
[0085] 8a Upper part of the supporting base plate
[0086] 8b Lower part of the supporting base plate
[0087] 10 PECVD deposition system
[0088] 11 Loading Station
[0089] 12 PECVD deposition chamber
[0090] 13, 14, and 15 are support base plates with different magnetizations.
[0091] 16 RF Generator
[0092] 17 Vacuum Pump
[0093] 18 Gas Supply
[0094] 110 Top of substrate carrier for holding substrate and mask
Claims
1. A layer deposition system (10), particularly for depositing at least one localized layer in a plasma-assisted deposition system, wherein the layer deposition system includes a movable substrate carrier (1) for receiving at least one solar wafer substrate, the movable substrate carrier being intended for transporting at least one substrate (2) and at least one mask (3) for masking the substrate (2) between a loading station (11) and a deposition station (12). The movable substrate carrier (1) and / or the mask (3) have a magnetic field. The substrate (2) and the mask (3) are arranged on the substrate carrier (1) in a mutually aligned manner, and the mask (3) is magnetically attached by the magnetic field between the mask and the substrate carrier.
2. The layer deposition system (10) according to claim 1, wherein the magnetic field of the substrate carrier (1) is generated by a separate magnet (4) integrated into the substrate carrier.
3. The layer deposition system (10) according to claim 1, wherein the magnetic field of the substrate carrier (1) is generated by at least one magnetization plate (5) attached to the substrate carrier (1).
4. The layer deposition system (10) according to claim 1, wherein the magnetic field of the substrate carrier (1) is generated by magnetizing the substrate carrier (1), the substrate carrier being composed of a magnetizable material.
5. The layer deposition system (10) according to any one of claims 1 to 4, wherein the magnetic field of the substrate carrier (1) is unipolar.
6. The layer deposition system (10) according to any one of claims 1 to 4, wherein the magnetic field of the substrate carrier (1) has alternating polarity.
7. The layer deposition system (10) according to any one of claims 1 to 6, wherein the magnetic field of the substrate carrier (1) is concentrated on the area where the substrate (2) and / or the mask (3) are disposed.
8. The layer deposition system (10) according to any one of claims 1 to 7, wherein the mask (3) is used as a shadow mask for more than one substrate (2).
9. The layer deposition system according to any one of claims 1 to 8, wherein the mask (3) is composed of an alloy of 32% to 36% Ni (nickel) and 64% to 68% Fe (iron).
10. A layer deposition system according to at least one of the preceding claims, wherein the mask (3) has a film-like shape and is used in the layer deposition system without a frame.
11. A method for depositing a localized layer in a plasma-assisted deposition system (10), wherein the deposition system (10) includes a substrate carrier (1) designed to carry: at least one substrate (2), particularly a solar wafer; and at least one magnetic mask (3) covering at least one substrate (2) in at least one deposition station (12), wherein the method includes at least one deposition step, wherein in the deposition step, at least one film is deposited on the substrate (2) on a localized region having an opening in the mask (3) of the mask (3). Its features are, Prior to the deposition step, at least one substrate (2) and at least one mask (3) are positioned and magnetically attached to the substrate carrier (1) in the loading step, wherein the substrate carrier (1) thus loaded is then transported to the deposition location, wherein during transport and in the deposition step, the substrate carrier (1) and / or the mask (3) emit a magnetic field to keep the substrate (2) and the mask (3) positioned on the substrate carrier (1).
12. The method according to claim 11, wherein the substrate carrier (1) is moved in the deposition system (10) between at least two deposition stations (12) and at least two deposition steps.
13. The method according to any one of claims 11 or 12, wherein the method is a method for depositing a local confinement layer in the manufacturing process of a solar cell.
14. The method according to any one of claims 11 to 13, wherein the method is used to locally deposit layers on a surface provided for this purpose, wherein these layers relate to the formation of locally adjacent contacts of an IBC solar cell.
15. The method of claim 14, wherein in at least one deposition step of the method, at least one amorphous silicon layer and / or at least one nanocrystalline silicon layer and / or at least one microcrystalline silicon layer or silicon alloy layer is deposited on a crystalline silicon solar wafer.