Manufacturing process of thin film solar cell

Abstract

The invention provides a manufacturing process of a thin film solar cell. Wherein in the substrate pretreatment step, a substrate is preheated in a stepped heating mode, so that the substrate is uniformly heated; in the semiconductor film deposition process, the deposition quality of a light absorption layer is improved by controlling the temperature of a raw material conveying pipe; in the activating annealing process, the substrate temperature is regulated and controlled according to the difference value between the deposition temperature and the activating annealing temperature, and grain recrystallization is fully completed; in the etching process, a reciprocating acid etching liquid spraying mode is adopted, so that the acid etching effect is improved; in the back contact layer deposition process, a suede structure is etched on the surface of the back contact layer by using an acid solution, and good ohmic contact is formed; in the back electrode deposition process, the cell efficiency is improved by depositing a back electrode of a p-doped material; in the laser scribing and packaging process, a light-transmitting hole is etched after a P3 scribing groove is etched, so that the light-transmitting characteristic is enhanced. Through optimal design and innovative combination of the procedures, a brand new thin film solar cell production process is developed.

Description

Technical Field

[0001] This invention relates to the field of semiconductor device (e.g., thin-film solar cell) manufacturing technology, and in particular to a manufacturing process for thin-film solar cells. Background Technology

[0002] CdTe thin-film solar cells are a new generation of photovoltaic materials that are fabricated on glass using semiconductor manufacturing processes and have already been commercialized. Due to their excellent resistance to hot spots, low-light performance, low temperature coefficient, and low carbon footprint, they are widely used in building-integrated photovoltaics (BIPV) and other fields.

[0003] CdTe thin-film solar cells are typically fabricated using a near-space sublimation process. In this process, the CdTe raw material is heated in a deposition chamber and sublimates into a vapor state. The substrate is then heated to a set temperature and conveyed through the deposition chamber, allowing the gaseous CdTe to be deposited onto the substrate surface.

[0004] Prior art: A physical vapor deposition system disclosed in invention patent application number 201780098181.8 includes a crucible for containing raw materials and a substrate holder. The substrate holder is positioned above the crucible and has a rotating shaft structure. The rotating shaft is rotatably supported on the bottom surface of the substrate, and the substrate is transported by rotating two shafts. When the substrate passes over the crucible, the gaseous raw materials moving upward from the crucible are deposited on the bottom surface of the substrate. However, this existing physical vapor deposition system has the following drawbacks: 1. Physical vapor deposition (PVD) systems are equipped with a material chamber that supplies semiconductor material to the crucible. Since the volume of the material chamber needs to match the evaporation rate of the material in the crucible, the material chamber cannot be empty or overflowing. During deposition, heat from the crucible flows to the material chamber, causing instability in its temperature and pressure, which in turn affects the evaporation rate of the material and is detrimental to improving the quality of the deposited film on the substrate. If the PVD system does not have a material chamber, refilling the crucible after the semiconductor material is depleted requires opening the entire equipment, disrupting the vacuum environment. Re-evacuation is then necessary after refilling, which is very time-consuming.

[0005] 2. Physical vapor deposition systems employ a bottom-up evaporation deposition structure. The bottom surface (i.e., the lower surface) of the substrate is the surface to be coated, and the evaporation material is deposited on the bottom surface of the substrate. The rotating shaft used to transport the substrate is in contact with the bottom surface of the substrate. During the transport of the substrate by the rotating shaft, rolling marks are left on the thin film coating on the bottom surface of the substrate, resulting in power loss. In addition, in order to ensure the effective active area of ​​the substrate, the rotating shaft only supports the edge side of the substrate, resulting in low reliability of basic support.

[0006] 3. During the deposition of semiconductor thin films onto the substrate surface, the substrate must be maintained at a temperature lower than the evaporation temperature of the semiconductor source material to ensure proper deposition. The substrate requires cooling during deposition to compensate for the radiant heat from the crucible during transport. Therefore, physical vapor deposition systems must have a static cooler positioned close to the substrate to cool it. The static cooler creates condensation conditions for the gaseous feedstock. After the deposition system has been running for a period of time, a semiconductor thin film will deposit on the surface of the static cooler, wasting semiconductor material and altering the cooling effect on the substrate, ultimately affecting the stability of the deposition system. Therefore, the deposition system needs to have its static cooler cleaned regularly, which will significantly reduce the system's uptime. Summary of the Invention

[0007] In view of the shortcomings of the prior art described above, the applicant's researchers, through long-term, large-team, collaborative, and persistent efforts, have improved the manufacturing process of thin-film solar cells and obtained high-performance thin-film solar cells.

[0008] The manufacturing process for thin-film solar cells provided in this application can solve the following technical problems: improve the quality of semiconductor thin films and enhance the long-term stability and efficiency of thin-film solar cells. To solve this technical problem, the manufacturing process for thin-film solar cells involved in this application adopts the following technical solution.

[0009] A manufacturing process for a thin-film solar cell includes a substrate pretreatment step, a semiconductor thin film deposition step, an activation annealing step, an etching step, a back contact layer deposition step, a back electrode deposition step, laser scribing, and an encapsulation step. In the substrate pretreatment step, the substrate is preheated using a stepped heating method to ensure uniform heating. In the semiconductor thin film deposition step, a light-absorbing layer is deposited on the substrate using CSS technology. A thermal barrier valve is used to allow the material delivery pipe to have different temperatures, improving the deposition quality of the light-absorbing layer. In the activation annealing step, the substrate temperature is adjusted based on the difference between the temperature during deposition and the temperature required for subsequent activation annealing, setting the substrate temperature to 300~500℃ to fully complete grain recrystallization. In the etching step, a reciprocating spraying method of acid etching solution is used to improve the acid etching effect. In the back contact layer deposition process, acid solution etching is used to form a textured structure on the back contact layer, creating a good ohmic contact. In the back electrode deposition process, p-doped material is deposited on the back electrode to improve battery efficiency. In the laser etching and packaging process, P1 grooves are laser-etched on the substrate TCO layer before the semiconductor thin film deposition process and filled with photoresist. P2 grooves are laser-etched on the light absorption layer before the back contact layer deposition process. P3 grooves are laser-etched on the back contact layer and back electrode layer after the back electrode deposition process. Then, the light-transmitting hole is laser-etched to give the battery light-transmitting characteristics.

[0010] In the substrate pretreatment process, the substrate is first cleaned. The substrate can be a glass substrate, metal substrate, plastic substrate, polymer substrate, ceramic substrate, etc., suitable for cadmium telluride thin-film solar cells. A TCO layer, serving as the front electrode layer, has already been deposited on the substrate's surface to be coated. The substrate is then transferred to a vacuum chamber, specifically a vacuum chamber for a semiconductor thin-film deposition system using CSS technology, and includes a preheating station. Preferably, a radiation heater and a conveying device are provided at the preheating station. The radiation heater preheats the substrate to a set temperature, typically the temperature required for deposition. Multiple parallel preheating stations can be arranged along the substrate's movement direction, each equipped with a radiation heater and a conveying device. By independently controlling multiple radiation heaters, the substrate is preheated to the required deposition temperature in a stepped heating manner, resulting in more uniform heating and preventing deformation or cracking due to uneven heating. Finally, the conveying device transfers the substrate to the next station within the vacuum chamber.

[0011] In the semiconductor thin film deposition process, the preheated substrate is conveyed to the deposition chamber within the vacuum chamber. The vacuum chamber of the semiconductor thin film deposition system includes a conveying device, an evaporation source, and a deposition chamber at the deposition station. The deposition chamber has a gas outlet. The evaporation source includes a raw material storage tank and a raw material delivery pipe for storing semiconductor materials, which can be either CdSe or CdTe. The CdSe or CdTe material in the storage tank is conveyed to the deposition chamber via the raw material delivery pipe, where it is heated and evaporated into CdSe or CdTe vapor. Simultaneously, the conveying device conveys the substrate on the side of the deposition chamber with the gas outlet. As the substrate passes through the gas outlet, CdSe or CdTe vapor is deposited onto the surface of the substrate to be coated, thus depositing a semiconductor thin film (i.e., a CdSe layer and a CdTe layer) on the TCO layer of the substrate.

[0012] Preferably, in the semiconductor thin film deposition system, the evaporation source also includes a heat-resistant valve installed on the raw material delivery pipe and an evaporation heater located inside the deposition chamber. The heat-resistant valve divides the raw material delivery pipe into a first feeding section and a second feeding section. The end of the first feeding section away from the heat-resistant valve is connected to a raw material storage tank, and the raw material storage tank, the first feeding section, and the heat-resistant valve are all located outside the deposition chamber. The end of the second feeding section away from the heat-resistant valve is located inside the deposition chamber, and this end has a raw material evaporation opening. The evaporation heater acts on the second feeding section inside the deposition chamber, heating the semiconductor material exposed in the raw material evaporation opening inside the deposition chamber and converting it into a gaseous state. In the evaporation deposition mode, the temperature of the first feeding section is lower than the temperature of the second feeding section. The thermal barrier valve serves two purposes: it transports the semiconductor material from the first feeding section to the second feeding section, and it prevents heat transfer from the second feeding section to the first feeding section. Through the thermal barrier valve on the material delivery pipe and the cooling effect of the cooler on the first feeding section, the temperature of the first feeding section is kept lower than that of the second feeding section. This effectively prevents heat transfer from the second feeding section to the material storage tank, ensuring a constant temperature and pressure for the semiconductor material in the storage tank. This is beneficial for improving the quality of the semiconductor film deposited on the substrate. The semiconductor material in the storage tank is transported to the deposition chamber via the material delivery pipe, replenishing the deposition chamber without opening the entire equipment, thus avoiding disruption of the vacuum environment and improving productivity.

[0013] The raw material evaporation opening is located at the bottom of the deposition chamber, and the raw material storage tank is located above the deposition chamber. The semiconductor material source in the raw material delivery pipe flows downwards to the raw material evaporation opening under gravity. The substrate is conveyed from below into the deposition chamber, with its upper surface being the surface to be coated. Therefore, in the semiconductor thin film deposition process, the TCO layer of the substrate faces upwards, and the gaseous semiconductor material source is deposited from top to bottom onto the TCO layer of the substrate at the gas outlet. During the evaporation, sublimation, and deposition of the semiconductor material source, there is a certain pressure in the deposition chamber. As the semiconductor material source in the raw material evaporation opening evaporates and sublimates, the pressure in the deposition chamber gradually increases. Before the semiconductor gas in the deposition chamber is consumed, the semiconductor material source in the second feeding section no longer feeds into the raw material evaporation opening due to the pressure in the deposition chamber. Subsequently, as the semiconductor gas in the deposition chamber is consumed, the pressure in the deposition chamber gradually decreases. At this time, the semiconductor material source in the second feeding section feeds into the raw material evaporation opening under gravity, continuously supplying semiconductor material into the deposition chamber. By adopting a top-down deposition method, the transfer rollers will no longer contact the substrate surface to be coated or the thin film coating deposited on the substrate, thus preventing rolling marks on the thin film coating, ensuring the quality of the thin film coating, and avoiding power loss caused by it.

[0014] Preferably, the semiconductor thin film deposition system is also equipped with a dynamic cooling device, which is located on the side of the substrate facing away from the deposition chamber. The dynamic cooling device includes a fixed vapor collection tube, a support tube rotatably mounted within the vapor collection tube, and a substrate cooling component and a cleaning heating component mounted on the support tube. The substrate cooling component and the cleaning heating component are distributed circumferentially along the support tube. In evaporation deposition mode, the substrate cooling component faces the substrate, and the cleaning heating component is away from the substrate. The substrate cooling component is on, and the cleaning heating component is off. The substrate is cooled by the substrate cooling component and maintained at the required temperature to compensate for the radiant heat from the deposition chamber, ensuring the deposition quality of the semiconductor thin film. After the semiconductor thin film deposition system has been running for a period of time, due to the condensation conditions provided by the substrate cooling component, some semiconductor gaseous material may deposit on the outer peripheral surface of the vapor collection tube, or even on the surface of other equipment in the vacuum chamber, during the evaporation deposition process. When the amount of deposited material accumulates to a level requiring cleaning, the semiconductor thin film deposition system can activate a self-cleaning mode. At this point, the cleaning heating component is activated, the substrate cooling component is deactivated, and the support tube is driven to rotate slowly. Under the heating action of the cleaning heating component, the semiconductor thin film deposited on the outer peripheral surface of the vapor collection tube and the surfaces of other equipment in the vacuum chamber evaporates and sublimates, achieving self-cleaning. After self-cleaning is completed, the support tube is reset, and the dynamic cooling equipment returns the substrate cooling component to its substrate-facing state.

[0015] In the activation annealing process, an activation solution is first prepared. This solution can be a cadmium chloride solution, or a solution of copper chloride, zinc chloride, and tellurium compounds added to an ammonia solution containing an alkali. The prepared activation solution is then uniformly rolled onto the surface of the light-absorbing layer using a sponge roller or spraying equipment. Preferably, before the activation annealing treatment, the substrate temperature is adjusted to the required activation annealing temperature by cooling or heating, based on the difference between the substrate deposition temperature and the temperature required for subsequent activation annealing, thus more reliably achieving grain recrystallization. Preferably, the deposited substrate is subjected to activation annealing at 300–500°C for 5–30 minutes to form a CdSeTe layer with a Se gradient. Through activation annealing, the grains fully complete the recrystallization process at this temperature, enhancing light absorption, increasing current, and improving power generation efficiency.

[0016] In the etching process, a suitable acid etching solution is selected based on the material to be etched. First, a photoresist pattern is coated onto the surface of the substrate after activation and annealing. Then, the substrate with the photoresist pattern is immersed in the acid etching solution, or the acid etching solution is uniformly sprayed onto the substrate surface using a spraying device. The acid etching solution reacts chemically with the exposed deposited layer on the substrate, gradually dissolving materials such as CdO, thus performing acid etching. The acid etching time is 2-4 seconds. In this application, during the acid etching process, it is preferable to spray the acid etching solution onto the substrate surface using a nozzle. The nozzle moves back and forth during spraying, with the direction of nozzle movement perpendicular to the direction of substrate movement. The nozzle atomizes the acid etching solution, allowing it to be uniformly sprayed onto the surface of the exposed deposited layer, improving the acid etching effect. After etching, the substrate is cleaned with deionized water or other solvents to remove residual acid etching solution and photoresist.

[0017] In the back contact layer deposition process, a copper-doped back contact layer is deposited on the etched substrate surface by sputtering a copper thin film, immersion in a copper chloride solution, or coating with copper-doped carbon paste. The thickness of the back contact layer is 15–25 nm. By preparing a copper-doped back contact layer between the light-absorbing layer and the back electrode layer, the potential barrier between the light-absorbing layer and the back electrode layer can be effectively reduced, forming an effective ohmic contact. Preferably, after the back contact layer is deposited, it is then acid-etched with an acid solution for 10–60 s to create a textured structure on the back contact layer. This facilitates the formation of a good ohmic contact between the back electrode layer and the light-absorbing layer, increasing the photoelectric conversion efficiency of the thin-film solar cell.

[0018] In the back electrode deposition process, a back electrode layer is deposited on the back contact layer using magnetron sputtering. A suitable metal target is selected based on the material requirements of the back electrode layer. The material of the back electrode layer includes one or more of molybdenum, aluminum, and chromium. Preferably, an As-doped metal target is used to deposit the p-doped back electrode. The target and the substrate after back contact layer deposition are placed in a vacuum chamber, and argon gas is introduced into the vacuum chamber. After the magnetron sputtering equipment is turned on, metal atoms on the target are sputtered out under the bombardment of high-energy argon ions, depositing the p-doped back electrode layer onto the surface of the substrate. After deposition, the sputtering power supply and gas supply are turned off, allowing the substrate to cool to room temperature. In the p-doped back electrode, As diffuses from the back electrode layer into the CdSeTe layer of the light absorption layer, forming an As-containing p-doped CdSeTe absorption layer, improving cell efficiency and stability.

[0019] In the laser etching and packaging process, a laser is used to laser-etch P1 grooves on the TCO layer of the substrate before the semiconductor thin film deposition process, and to laser-etch P2 grooves on the light absorption layer before the back contact layer deposition process. After the back electrode deposition process, P3 grooves are laser-etched on both the back contact layer and the back electrode layer, thereby achieving the series connection of cadmium telluride thin-film solar cells. Furthermore, after etching the P1 grooves, photoresist is filled to form an insulating layer. Depending on the wavelength of the light absorbed by the material, near-ultraviolet light is used for the P1 grooves, while green light is used for both the P2 and P3 grooves. Preferably, after laser etching, several light-transmitting holes with a diameter of 40-60 μm are laser-etched on the surface of the substrate after laser etching. These holes extend from the back electrode layer to the substrate, allowing visible light to pass through the thin-film solar cell and enhancing its light transmittance. Afterward, the laser-etched substrate undergoes preliminary performance testing to check current, voltage, power, etc. After passing the tests, butyl adhesive is used to bond EVA to the outermost edge of the substrate to achieve lamination and assembly. After assembly, further testing is conducted to obtain the final cadmium telluride thin-film solar cell product.

[0020] Compared with existing technologies, this application further optimizes the substrate pretreatment, semiconductor thin film deposition, activation annealing, etching, back contact layer deposition, back electrode deposition, laser scribing and encapsulation processes for thin-film solar cell fabrication, thereby comprehensively improving the overall performance of solar cell products. Attached Figure Description

[0021] Figure 1 This is a process flow diagram of the manufacturing process of the thin-film solar cell of this application.

[0022] Figure 2 This is a schematic diagram of the semiconductor thin film deposition system involved in this application.

[0023] Figure 3 This is a schematic diagram of the evaporation source in the semiconductor thin film deposition system of this application.

[0024] Figure 4 This is a schematic diagram of the assembly between the support tube, the substrate cooling component, and the cleaning heating component in the dynamic cooling equipment of the semiconductor thin film deposition system of this application.

[0025] Figure 5 This is a schematic diagram of the structure of a semi-finished cadmium telluride thin-film solar cell, Example 1.

[0026] Figure 6 This is a schematic diagram of the structure of Example 2, a semi-finished cadmium telluride thin-film solar cell. Detailed Implementation

[0027] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0028] The structures, proportions, and sizes depicted in the accompanying drawings are solely for illustrative purposes and to aid those skilled in the art in understanding and reading the invention. They are not intended to limit the scope of the invention. Any modifications to the structure, changes in proportions, or adjustments to size, provided they do not affect the effectiveness or purpose of the invention, should still fall within the scope of the disclosed technical content. Furthermore, the terms "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention's implementation.

[0029] It should also be noted that when a component is referred to as "fixed to" or "set on" another component, it can be directly on the other component or may be connected to an intervening component. When a component is referred to as "connected to" another component, it can be directly connected to the other component or indirectly connected to the other component through an intervening component.

[0030] Furthermore, the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.

[0031] This application relates to a manufacturing process for thin-film solar cells, used in the manufacture of solar cells. For example... Figure 1 As shown, the manufacturing process of the thin-film solar cell involved in this application includes the following steps: Substrate pretreatment process: Provide a substrate 10 with a TCO layer deposited on it, transfer the substrate 10 to a vacuum chamber, and preheat the substrate 10 in the vacuum chamber to the temperature required for deposition; Semiconductor thin film deposition process: such as Figure 2 and Figure 3 As shown, the preheated substrate 10 is transferred to the deposition chamber in the vacuum chamber, and a semiconductor thin film, namely the light-absorbing layer, is deposited on the TCO layer of the substrate 10. Taking the manufacture of cadmium telluride thin-film solar cells as an example, the light-absorbing layer includes a CdSe layer and a CdTe layer. Activation annealing process: The light absorption layer is activated and annealed to form a CdSeTe layer with a Se gradient; Etching process: The substrate after activation and annealing is cleaned with acid solution to remove CdO and other substances from the substrate surface; Back contact layer deposition process: depositing a copper-doped back contact layer on the light absorption layer; Back electrode deposition process: Deposit a back electrode layer on the back contact layer; Laser etching and encapsulation process: P1 groove, P2 groove and P3 groove are laser etched sequentially on the TCO layer, light absorption layer, back contact layer and back electrode layer of the substrate. Finally, the solar cell product is encapsulated.

[0032] The following section explains the technology of each process step by step.

[0033] Substrate pretreatment process like Figure 2 and Figure 3 As shown, a substrate 10 is provided. The substrate 10 is cleaned to remove insulating powder, impurities, etc., thereby improving the adhesion and deposition uniformity of the semiconductor thin film on the substrate 10. Furthermore, the surface of the substrate 10 can be treated with mechanical polishing or chemical mechanical polishing techniques to make its surface smoother, which further improves the adhesion and deposition uniformity of the semiconductor thin film on the substrate 10. The substrate 10 can be any type suitable for use in cadmium telluride thin-film solar cells, preferably a glass substrate, but it can also be a metal substrate (such as a metal foil substrate), a plastic substrate, a polymer substrate, or a ceramic substrate, etc. A TCO layer, which is the front electrode layer, has been deposited on the surface of the substrate 10 to be coated.

[0034] The substrate 10 is transferred to the vacuum chamber 20, which uses a CSS (Silicon-Chip-Semiconductor) semiconductor thin film deposition system. The vacuum chamber 20 provides a vacuum environment and includes a preheating station. The preheating station is equipped with a radiation heater and a transfer device. The radiation heater preheats the substrate 10 to the required deposition temperature, and the transfer device then transfers the substrate 10 to the deposition station within the vacuum chamber 20. The radiation heater can be replaced with an electric heater.

[0035] Preferably, there can be multiple preheating stations, each equipped with a radiant heater and a conveying device. The multiple preheating stations are arranged in parallel along the moving direction of the substrate 10. The radiant heaters at each preheating station are independently adjustable, and the substrate 10 can be preheated to the required deposition temperature in a stepped heating manner, so that the substrate 10 is heated more evenly and the substrate 10 is prevented from deforming or breaking due to uneven heating.

[0036] Semiconductor thin film deposition process The semiconductor thin film deposition process uses a semiconductor thin film deposition system to deposit a light-absorbing layer on the substrate 10. The semiconductor thin film deposition system can be configured for either top-down or bottom-up deposition. Figure 2 The illustrated embodiment employs a top-down deposition method.

[0037] There are two embodiments of the semiconductor thin film deposition system: Embodiment 1 is mainly used to effectively prevent heat transfer from the deposition chamber to the semiconductor material source, ensuring constant temperature and pressure of the semiconductor material source. Embodiment 2 is mainly used to achieve self-cleaning, automatically removing semiconductor material deposited on the surface of the vapor collection tube, ensuring stable operation of the semiconductor thin film deposition system. Embodiments 1 and 2 can be used individually or in combination.

[0038] like Figure 2 As shown, a deposition station is provided within the vacuum chamber 20 of the semiconductor thin film deposition system. Embodiment 1 of the semiconductor thin film deposition system includes a vacuum chamber 20, a transfer device with a deposition station, an evaporation source 40, and a deposition chamber 30. The deposition chamber 30 has a gas outlet 31, and the transfer device is used to transfer the substrate 10 to one side of the gas outlet 31. Specifically, as... Figure 3 As shown, the evaporation source 40 includes a raw material storage tank 41, a raw material conveying pipe 42, a heat-insulating valve 43, a cooler 44, and an evaporation heater 45. The raw material storage tank 41, the heat-insulating valve 43, and the cooler 44 are located outside the deposition chamber 30. The raw material storage tank 41 can adopt a hopper structure. The raw material storage tank 41 stores a semiconductor material source, which is a CdSe material source or a CdTe material source, preferably a powdered material source. The heat-insulating valve 43 divides the raw material conveying pipe 42 into a first feeding section 421 and a second feeding section 422. The heat-insulating valve 43 allows the material source in the first feeding section 421 to be conveyed to the second feeding section 422, while also providing thermal insulation between the first feeding section 421 and the second feeding section 422. The end of the first feeding section 421, away from the heat-insulating valve 43, is connected to the raw material storage tank 41. The second feeding section 422 is located inside the sedimentation chamber 30, and this section has a raw material evaporation opening 423, exposing the material source at the raw material evaporation opening 423 to the sedimentation chamber 30. The evaporation heater 45 acts on the second feeding section 422 inside the sedimentation chamber 30, heating the material source exposed at the raw material evaporation opening 423 to the sedimentation chamber 30 and converting it into a gaseous state. The cooler 44 acts on the first feeding section 421. In the evaporation-deposition mode, the temperature of the first feeding section 421 is lower than the temperature of the second feeding section 422. Preferably, in the evaporation-deposition mode, the temperature of the first feeding section 421 is below 400°C, and the temperature of the second feeding section 422 at the raw material evaporation opening 423 is 750–1000°C.

[0039] At the deposition station, when the semiconductor thin film deposition system deposits CdSe or CdTe onto the surface of the substrate 10 to be coated, the evaporation source 40 provides semiconductor material for deposition into the deposition chamber 30. The material is heated and sublimated into a gaseous state within the deposition chamber 30. Under the combined action of vacuum and heating by the evaporation heater 45, the semiconductor material exposed in the deposition chamber 30 at the raw material evaporation opening 423 is heated and sublimated into gaseous CdSe or gaseous CdTe. Simultaneously, the conveying device at the deposition station transports the substrate 10 from one side of the gas outlet 31 to the deposition station. As the substrate 10 passes through the gas outlet 31, its surface to be coated faces the gas outlet 31. The semiconductor gas in the deposition chamber 30 is then deposited onto the surface of the substrate 10 to be coated via the gas outlet 31, forming a semiconductor thin film on the surface of the substrate 10, i.e., a CdSe layer or a CdTe layer is deposited on the substrate 10.

[0040] When depositing CdSe and CdTe layers on substrate 10, the CdSe layer can be deposited first, followed by the CdTe layer, or the CdSe and CdTe layers can be repeatedly stacked. When depositing the CdSe layer first, followed by the CdTe layer, as shown... Figure 5 As shown, during deposition, a CdSe layer is first deposited to form an N-type semiconductor structure. The thickness of the CdSe layer is 50~300nm, preferably 80~200nm. Then, a CdTe layer is deposited to form a P-type semiconductor structure. The thickness of the CdTe layer is 1~5μm. When the CdSe and CdTe layers are repeatedly stacked, as shown... Figure 6 As shown, a CdSe layer is first deposited, followed by a CdTe layer, and this deposition process is repeated to form a stacked structure of CdSe layers, CdTe layers, CdSe layers, CdTe layers, and so on. The total thickness of each CdSe layer is 50–500 nm, preferably 100–300 nm, and the total thickness of each CdTe layer is 800–3000 nm, preferably 900–2000 nm.

[0041] Furthermore, during the evaporation, sublimation and deposition process of the semiconductor material source, the semiconductor material source in the raw material storage tank 41 is transported to the deposition chamber 30 via the raw material delivery pipe 42. In particular, the heat-blocking valve 43 on the raw material conveying pipe 42 separates the first feeding section 421 and the second feeding section 422 of the raw material conveying pipe 42. The heat-blocking valve 43 serves to both convey the semiconductor material source in the first feeding section 421 to the second feeding section 422 and prevent the heat from the second feeding section 422 from being transferred to the first feeding section 421. Combined with the cooling effect of the cooler 44 on the first feeding section 421, the raw material conveying pipe 42 has different temperature gradients, so that the temperature of the first feeding section 421 is lower than the temperature of the second feeding section 422. Preferably, the temperature of the first feeding section 421 is lower than 400°C, and the temperature of the second feeding section 422 at the raw material evaporation opening 423 is 750-1000°C. This effectively prevents the heat from the continuously heated second feeding section 422 from being transferred to the raw material storage tank 41, ensuring that the semiconductor material source in the raw material storage tank 41 always has a constant temperature and pressure, which is beneficial to improving the quality of the semiconductor thin film deposited on the substrate 10. In addition, the semiconductor material source in the raw material storage tank 41 is transported to the deposition chamber 30 through the raw material conveying pipe 42 to replenish the semiconductor material source in the deposition chamber 30 without opening the entire equipment, thus avoiding damage to the vacuum environment and improving productivity.

[0042] Preferably, the semiconductor thin film deposition system further includes a vapor distributor located inside the deposition chamber 30, through which gaseous CdSe or gaseous CdTe in the deposition chamber 30 is uniformly deposited onto the surface of the substrate 10 to be coated.

[0043] Preferably, the heat-blocking valve 43 should meet the following requirements: the heat-blocking valve 43 should not be blocked when the raw material delivery pipe 42 is filled with semiconductor material, so as to ensure that the semiconductor material in the raw material delivery pipe 42 is delivered to the deposition chamber 30. In the evaporation deposition mode, the delivery rate of the semiconductor material delivered by the heat-blocking valve 43 needs to be higher than the maximum evaporation rate of the semiconductor material in the deposition chamber 30. Therefore, preferably, the heat-blocking valve 43 is a rotary feeder or an on / off valve.

[0044] Furthermore, such as Figure 3 As shown, a feed control valve 46 is also installed on the first feeding section 421. The feed control valve 46 and the heat-insulating valve 43 are connected in series on the raw material conveying pipe 42 along the feeding direction of the raw material conveying pipe 42. When the semiconductor material stored in the raw material storage tank 41 is conveyed, it first enters the first feeding section 421, then passes through the feed control valve 46 and the heat-insulating valve 43, enters the second feeding section 422, and is finally conveyed to the raw material evaporation opening 423 located in the deposition chamber 30. The feed control valve 46 is mainly used to control the feeding rate, so there is no requirement for the heat-insulating function of the feed control valve 46. A rotary feeder or a switch valve is preferred.

[0045] Furthermore, through the cooperation of the feed control valve 46 and the heat-blocking valve 43, self-cleaning can be achieved within the hot end of the raw material conveying pipe 42. After the rotary feeder or switching valve of the feed control valve 46 stops feeding, the remaining semiconductor material in the first feeding section 421 enters the second feeding section 422 through the heat-blocking valve 43, and finally enters the deposition chamber 30 to be evaporated. After running for a period of time, all the semiconductor material filling the second feeding section 422 is evaporated, achieving self-cleaning of the hot end pipe. More preferably, after this, when the rotary feeder or switching valve of the feed control valve 46 stops feeding, the cooler 44, which has a lower temperature, is switched to the heating function, so that all the semiconductor material filling the first feeding section 421 is evaporated. In addition, the raw material conveying pipe 42, which has a raw material evaporation opening 423, is an open pipe, allowing the heat-blocking valve 43 to have the same temperature as or higher than that of the deposition chamber 30, ensuring that the vapor does not condense inside the second feeding section 422. In this embodiment, the temperature of the deposition chamber 30 is 650-750°C, and the temperature of the heat-insulating valve 43 is not lower than 650-750°C.

[0046] Furthermore, based on top-down depositional methods, such as Figure 3 As shown, the raw material evaporation opening 423 on the deposition chamber 30 is located at its bottom. The raw material storage tank 41 is located above the deposition chamber 30. The raw material delivery pipe 42 is vertically arranged, and the semiconductor material source in the raw material delivery pipe 42 flows from top to bottom to the raw material evaporation opening 423 under the action of gravity. The upper end of the raw material delivery pipe 42 is the cold end, and the lower end of the raw material delivery pipe 42 is the hot end. The upper surface of the substrate 10 is the surface to be coated, and the lower surface of the substrate 10 is the conveying support surface. The conveying device includes several rotatable conveying rollers, which are in contact with the lower surface of the substrate 10. During the evaporation and sublimation deposition process of the semiconductor material source, there is a certain pressure in the deposition chamber 30. As the semiconductor material source at the raw material evaporation opening 423 evaporates and sublimates, the pressure in the deposition chamber 30 gradually increases. Before the semiconductor gas in the deposition chamber 30 is consumed, the semiconductor material source in the second feeding section 422 does not feed into the raw material evaporation opening 423 due to the pressure in the deposition chamber 30. Subsequently, as the semiconductor gas in the deposition chamber 30 is consumed, the pressure inside the deposition chamber 30 decreases. At this time, the semiconductor material source in the second feeding section 422 moves towards the raw material evaporation opening 423 under the action of gravity, and is automatically fed. In this way, the semiconductor material source can be automatically and continuously supplied into the deposition chamber 30, realizing continuous feeding of the semiconductor material source.

[0047] Furthermore, by employing a top-down deposition method, the conveyor rollers used to transport the substrate 10 no longer contact the surface of the substrate 10 to be coated or the thin film coating deposited on the substrate 10, thus preventing rolling marks from forming on the thin film coating, ensuring the quality of the thin film coating, and avoiding power loss caused by this. Simultaneously, since the surface of the conveyor rollers that contacts the substrate 10 is an uncoated surface, the conveyor rollers can be positioned in the middle of the lower surface of the supporting substrate 10, rather than being limited to the edge of the lower surface of the supporting substrate 10, effectively supporting the substrate 10 and improving the stability and reliability of the conveyor rollers transporting the substrate 10.

[0048] Furthermore, such as Figure 3 As shown, there are two raw material storage tanks 41. The raw material conveying pipe 42 is a vertically arranged U-shaped pipe, which includes a U-shaped bend section 424 and two straight pipe sections 425 extending straight upward from both ends of the U-shaped bend section 424. The two raw material storage tanks 41 are connected to the two straight pipe sections 425 respectively. Each straight pipe section 425 is equipped with a feed control valve 46 and a heat-insulating valve 43 connected in series. The U-shaped bend section 424 is located inside the deposition chamber 30, forming part of the second feed section 422. The raw material evaporation opening 423 is opened on the U-shaped bend section 424, that is, at the lower end of the U-shaped pipe. By using a U-shaped pipe for the raw material conveying pipe 42, two raw material storage tanks 41 can be connected by one U-shaped pipe. The two raw material storage tanks 41 can store the same semiconductor material source or different semiconductor material sources. One U-shaped pipe can form two independent first feed section 421 and second feed section 422. When different semiconductor materials are stored in the two raw material storage tanks 41, different semiconductor thin films can be deposited on the substrate 10 one after another, thereby improving production efficiency.

[0049] Preferably, the raw material evaporation opening 423 on the U-shaped bend section 424 at the lower end of the U-tube should be set as large as possible to allow rapid evaporation of the semiconductor material source. Figure 3 As shown, two large raw material evaporation openings 423 can be opened on the U-shaped bend section 424, and both raw material evaporation openings 423 are located on the inner circumference of the U-shaped bend section 424.

[0050] In one embodiment, the evaporation of the semiconductor material exposed at the raw material evaporation opening 423 within the deposition chamber 30 can be carried out using a passive heating method. In this case, the evaporation heater 45 is integrated into the inner wall of the deposition chamber 30, and the raw material delivery pipe 42 is a passive heating device. With this configuration, heat is provided from the surrounding area of ​​the semiconductor material exposed at the raw material evaporation opening 423, causing the second feeding section 422 to heat up and reach the evaporation temperature of the semiconductor material within the second feeding section 422, thereby evaporating it into the deposition chamber 30.

[0051] In another embodiment, an active heating evaporation method can be used to evaporate the semiconductor material source at the raw material evaporation opening 423 into the deposition chamber 30. In this case, the evaporation heater 45 is integrated into the second feeding section 422 extending into the deposition chamber 30, making the raw material delivery pipe 42 an active heating device, requiring electrical connection to a power source. This provides the raw material delivery pipe 42 with a superior temperature gradient, significantly increasing the heating temperature of the semiconductor material source at the raw material evaporation opening 423, effectively increasing the deposition rate, and thus improving productivity. Furthermore, when connecting the raw material delivery pipe 42 to the power source, by selecting a suitable electrical connection point and appropriately adjusting the energy flow within the raw material delivery pipe 42, the first feeding section 421 of the raw material delivery pipe 42 can have a lower temperature than the second feeding section 422.

[0052] Furthermore, the raw material delivery pipe 42 can be made of different materials, such as graphite, chlorofluorocarbon, silicon carbide, or metal. Preferably, the first feeding section 421 is a ceramic tube, and the second feeding section 422 is a silicon carbide tube, graphite tube, or metal tube, giving the first feeding section 421 lower thermal conductivity, which is beneficial for achieving a temperature gradient distribution within the raw material delivery pipe 42. In addition, the wall thickness of the raw material delivery pipe 42 is less than 5 mm, and the inner diameter of the raw material delivery pipe 42 is less than 10 mm, enabling the raw material delivery pipe 42 to withstand the large temperature gradient required by the design. The smaller the inner diameter of the raw material delivery pipe 42, the faster the exchange of semiconductor material within the raw material delivery pipe 42, and the faster the rate of energy transfer to the semiconductor material, giving the raw material delivery pipe 42 high-throughput characteristics, thereby reducing the possible risk of blockage within the raw material delivery pipe 42.

[0053] Furthermore, such as Figure 3 As shown, the evaporation source 40 also includes a preheater 47, which is located outside the deposition chamber 30. The preheater 47 acts on the second feeding section 422 outside the deposition chamber 30 to preheat this part of the second feeding section 422, which also makes the raw material conveying pipe 42 have a better temperature gradient, significantly increases the temperature of the semiconductor material source at the raw material evaporation opening 423, effectively increases the deposition rate, and thus improves productivity.

[0054] Furthermore, to meet production demands, at least one evaporation source 40 is provided, and preferably multiple sources are configured. These multiple evaporation sources 40 are arranged side-by-side along the width of the substrate 10. When multiple evaporation sources 40 are configured, they can operate independently, meaning some evaporation sources 40 can be activated while the others remain in standby mode. This allows the semiconductor thin film deposition system to operate more flexibly to meet different production needs. Additionally, the cooler 44 and preheater 47 involved in the multiple evaporation sources 40 can share a single unit, requiring only the configuration of multiple U-shaped tubes and valves. The uniformity of the deposited thin film can be improved by adjusting the evaporation rates of different evaporation sources 40 along the width of the substrate 10.

[0055] like Figure 2 As shown, Embodiment 2 of the semiconductor thin film deposition system includes a vacuum chamber 20 and a dynamic cooling device 50. The dynamic cooling device 50 is disposed inside the vacuum chamber 20 and is positioned on the side of the substrate 10 facing away from the deposition chamber 30. That is, the deposition chamber 30 is located on the upper side of the substrate 10, and the dynamic cooling device 50 is located on the lower side of the substrate 10. The substrate 10 is conveyed through a channel formed between the deposition chamber 30 and the dynamic cooling device 50. Figure 2 and Figure 4 As shown, the dynamic cooling device 50 includes a fixedly installed steam collection pipe 51, a support pipe 52 rotatably mounted in the steam collection pipe 51, and a substrate cooling component 53 and a cleaning heating component 54 installed on the support pipe 52. The substrate cooling component 53 and the cleaning heating component 54 are distributed at intervals along the circumference of the support pipe 52, preferably at intervals of 180 degrees.

[0056] In deposition mode, the substrate cooling component 53 faces the substrate 10, and the cleaning heating component 54 is away from the substrate 10. The substrate cooling component 53 is turned on, and the cleaning heating component 54 is turned off. The substrate 10 is cooled by the substrate cooling component 53 and maintained at the required temperature to compensate for the effect of radiant heat from the deposition chamber 30 on the substrate 10, thus ensuring the deposition quality of the semiconductor thin film.

[0057] After the semiconductor thin film deposition system has been running for a period of time, due to the condensation conditions provided by the substrate cooling component 53, some semiconductor gas in the deposition chamber 30 during the evaporation deposition process is deposited on the outer peripheral surface of the vapor collection tube 51, or even on the surface of other equipment in the vacuum chamber 20. When the amount of deposition accumulates to the point where cleaning is required, the semiconductor thin film deposition system can be adjusted to a self-cleaning mode. At this time, the support tube 52 is driven to rotate slowly, the cleaning heating component 54 is turned on, and the substrate cooling component 53 is turned off. Under the heating action of the cleaning heating component 54, the semiconductor material deposited on the outer peripheral surface of the vapor collection tube 51 and on the surface of other equipment in the vacuum chamber 20 evaporates and sublimates, achieving self-cleaning. After self-cleaning is completed, the support tube 52 is driven to reset, and the dynamic cooling device 50 returns to the state where the substrate cooling component 53 faces the substrate 10. In this way, the stability of the cooling effect of the dynamic cooling device 50 on the substrate 10 can be guaranteed, ensuring the deposition quality of the semiconductor thin film on the substrate 10 and the operational stability of the semiconductor thin film deposition system. In addition, the dynamic cooling device 50 achieves self-cleaning, eliminating the need for periodic passive cleaning and improving the uptime of the dynamic cooling device 50. During the self-cleaning process of the dynamic cooling device 50, the semiconductor materials on the surfaces of the vapor collection pipe 51 and other equipment in the vacuum chamber 20 are reheated and evaporated into the deposition chamber 30, increasing the material utilization rate.

[0058] Furthermore, the steam collecting pipe 51 has high thermal conductivity along its wall thickness direction (i.e., radial direction) and low thermal conductivity along its wall surface direction (i.e., axial direction), effectively reducing energy loss due to heat transfer. Figure 2 As shown, the semiconductor thin film deposition system also includes a heating channel 60 disposed within the vacuum chamber 20 for heating the deposition chamber 30. The temperature of the heating channel 60 is higher than the temperature of the substrate 10.

[0059] Furthermore, such as Figure 4 As shown, the dynamic cooling device 50 includes a thermal insulation component 57 installed on the support tube 52. The thermal insulation component 57 fills the space between the substrate cooling component 53 and the cleaning heating component 54, minimizing the mutual influence between the substrate cooling component 53 and the cleaning heating component 54. Preferably, the substrate cooling component 53 adopts a water-cooled structure, and the cleaning heating component 54 adopts an electric heating structure.

[0060] Furthermore, such as Figure 4As shown, the dynamic cooling device 50 also includes a static mandrel 58 passing through a support tube 52, the static mandrel 58 having an inner cavity. A cooling water connection pipe 59 is introduced into one end of the static mandrel 58, and the cooling water connection pipe 59 passes through the inner cavity of the static mandrel 58 and is connected to the substrate cooling component 53. A heating connection wire 510 is introduced into the other end of the static mandrel 58, and the heating connection wire 510 passes through the inner cavity of the static mandrel 58 and is connected to the cleaning heating component 54. The static mandrel 58 can be made of a conductive material, in which case the heating connection wire 510 is directly connected to the left or right end of the static mandrel 58, and the static mandrel 58 is electrically connected to the cleaning heating component 54.

[0061] In the pretreatment process of substrate 10, substrate 10 is heated to 500°C by an electric heater or a radiant heater, with a heating rate greater than 10°C / min during preheating. Before being conveyed to deposition chamber 30, substrate 10 passes through a uniformly heated thermal buffer. Heating channel 60 heats deposition chamber 30 to a temperature of 655°C, while the top surface of dynamic cooling device 50 facing substrate 10 is cooled to 450°C, thus ensuring that the substrate temperature remains consistently lower than the deposition chamber temperature. This temperature difference between the substrate and the deposition chamber controls the deposition process of CdTe or CdSe, while preventing the CdTe or CdSe layer deposited on the substrate from re-sublimating into gas and entering the deposition chamber. During this process, some CdTe or CdSe gas enters vapor collection pipe 51 and is deposited on its surface. When the CdTe or CdSe layer on the surface of vapor collection pipe 51 reaches a certain thickness, it needs to be cleaned. At this time, the cleaning heating element 54 is heated to 550~700℃, and the support tube 52 in the dynamic cooling device 50 rotates at a low speed, such as 1 revolution per hour, heating and sublimating the CdTe or CdSe layer deposited on the vapor collection tube 51 into gas. The generated CdTe or CdSe gas is returned to the deposition chamber 30 and reused in the deposition process. Thus, not only is the escaped CdTe or CdSe gas collected through the vapor collection tube 51, reducing parasitic contamination in the deposition equipment, but the dynamic cooling device 50 also achieves self-cleaning of the vapor collection tube.

[0062] After semiconductor thin film deposition, the temperature of the substrate needs to be controlled to complete the subsequent activation annealing process. A temperature control station is provided within the vacuum chamber 20 of the semiconductor thin film deposition system. Depending on the difference between the substrate deposition temperature and the temperature required for subsequent activation annealing, a cooling device for cooling the substrate or a heating device for heating the substrate is installed at the temperature control station. When the substrate deposition temperature is higher than the required activation annealing temperature, a cooling device is installed at the temperature control station, and the substrate is cooled to the required activation annealing temperature. When the substrate deposition temperature is lower than the required activation annealing temperature, a heating device is installed at the temperature control station, and the substrate is heated to the required temperature. Subsequently, the substrate is transferred to the activation annealing furnace for activation annealing treatment.

[0063] Activation annealing process In the activation annealing process, an activation solution is first prepared. This solution can be a cadmium chloride solution, or a solution of copper chloride, zinc chloride, and a tellurium-containing compound added to an ammonia solution containing an alkali. The prepared activation solution is then coated onto the surface of the light-absorbing layer. The coating can be done using a sponge roller or a spraying device to uniformly coat the surface of the light-absorbing layer. At a preset activation annealing temperature, the substrate after the semiconductor thin film deposition is subjected to an activation annealing treatment for a preset duration to form a CdSeTe layer with a Se gradient. CdSeTe refers to CdSe... 1-x Te x Preferably, the activation annealing temperature is 300–500°C and the activation annealing time is 5–30 min. During the activation annealing process, the grains fully complete the recrystallization process, which enhances light absorption, increases current, and improves power generation efficiency.

[0064] Furthermore, for Figure 5 In the non-stacked structure shown, during the deposition of the light-absorbing layer, a CdSe layer is deposited first, followed by a CdTe layer. Thus, before the activation annealing treatment, the deposited structure on substrate 10 consists of a TCO layer, a CdSe layer, and a CdTe layer in sequence. After the activation annealing treatment, the CdSe and CdTe layers form a CdSeTe layer with a Se gradient (i.e., CdSe...). 1- x Te x ) and CdTe layer. Therefore, Figure 5 The intermediate product of the cadmium telluride thin-film solar cell shown includes, from bottom to top, a substrate 10, a TCO layer, a CdSeTe layer and a CdTe layer.

[0065] Furthermore, for Figure 6In the stacked structure shown, CdSe and CdTe layers are repeatedly stacked during the deposition of the light-absorbing layer. Before the activation annealing treatment, the deposited structure on the substrate 10 is sequentially: TCO layer, CdSe layer, CdTe layer, CdSe layer, CdTe layer... After the activation annealing treatment, CdSe and CdTe layers are repeatedly stacked to form a CdSeTe layer with a uniform Se concentration (i.e., CdSe...). 1-x Te x ).therefore, Figure 6 The intermediate product of the cadmium telluride thin-film solar cell shown includes, from bottom to top, a substrate 10, a TCO layer and a CdSeTe layer.

[0066] Etching process A suitable acid etching solution is selected based on the material to be etched; in this application, hydrochloric acid is used. First, a photoresist pattern is printed on the surface of the substrate after activation and annealing. Then, the substrate with the printed photoresist pattern is immersed in the acid etching solution, or the acid etching solution is evenly sprayed onto the substrate surface using a spraying device. The acid etching solution reacts chemically with the exposed deposited layer on the substrate, gradually dissolving CdO and performing acid etching. The etching time must be strictly controlled during the etching process; in this application, the acid etching time is 2–4 seconds.

[0067] Preferably, this application employs an acid etching solution sprayed onto the substrate surface, during which the substrate is conveyed. The spraying equipment includes a reciprocating nozzle, the nozzle's movement direction being perpendicular to the substrate's movement direction, employing a reciprocating spraying method. An atomizer is installed within the nozzle to atomize the acid etching solution into extremely small droplets. Therefore, based on the reciprocating nozzle and the nozzle's atomization effect on the acid etching solution, the acid etching solution is uniformly sprayed onto the exposed deposition layer surface, improving the acid etching effect.

[0068] After etching, the substrate is cleaned with deionized water or other solvents to remove residual acid etching solution and photoresist. Furthermore, the etched substrate must be inspected to ensure the accuracy and integrity of the pattern. This can be done using equipment such as optical microscopes or scanning electron microscopes (SEM).

[0069] Back contact layer deposition process A copper-doped back contact layer is deposited on a semiconductor thin film by sputtering a copper thin film, immersing in a copper chloride solution, or coating with copper-doped carbon paste. The thickness of the back contact layer is 15–25 nm.

[0070] Taking the deposition of a back contact layer using a sputtered copper thin film as an example. Before depositing the back contact layer, the etched substrate is ultrasonically cleaned in deionized water. After cleaning, the substrate is heated to 100°C using a hot plate and baked for about 30 minutes to remove impurities and organic residues from the substrate surface. A high-purity copper target is installed, and the cleaned substrate is placed in a vacuum chamber. The vacuum chamber is then evacuated to maintain a preset vacuum level. High-purity argon gas is then introduced into the vacuum chamber to generate plasma. The high-purity argon gas does not chemically react with the copper target or substrate, ensuring the purity of the deposited copper thin film. The magnetron sputtering equipment is then turned on, causing copper atoms on the target to be sputtered out under the bombardment of high-energy argon ions. The sputtered copper atoms move within the vacuum chamber and eventually deposit onto the surface of the substrate, forming a copper thin film, thus completing the deposition of the copper-doped back contact layer. The sputtering power of the magnetron sputtering equipment is between 100 and 500 W, and the flow rate of the high-purity argon gas is 3 to 10 sccm to ensure the thickness and quality of the copper thin film. In addition, before turning on the sputtering equipment, the substrate can be plasma activated and cleaned for about 10 minutes to further clean the substrate surface, improve substrate activity, and increase the adhesion of the copper film to the deposited layer. After sputtering deposition is completed, the sputtering power supply and gas supply are turned off, and the vacuum chamber is allowed to cool naturally or through a cooling system to room temperature to ensure the stability and integrity of the copper film. Finally, the vacuum chamber is opened, and the substrate with the deposited copper film is removed.

[0071] Preferably, an acid solution is used to etch the back contact layer for 10-60 seconds, forming a textured surface that facilitates good ohmic contact and increases the photoelectric conversion efficiency of the thin-film solar cell. The acid etching of the back contact layer is also performed using a spraying method, where a reciprocating nozzle atomizes the acid solution, ensuring it is evenly sprayed onto the surface of the back contact layer.

[0072] Back electrode deposition process First, the substrate after the back contact layer is deposited is ultrasonically cleaned using solvents such as acetone and ethanol, and then dried with nitrogen. A suitable metal target is selected based on the material requirements of the back electrode layer. The back electrode layer material includes one or more of molybdenum, aluminum, and chromium. The target and substrate are placed in a vacuum chamber, and the chamber is evacuated to maintain a preset vacuum level. Then, argon gas is introduced into the vacuum chamber, and the gas pressure inside the chamber is adjusted to a suitable sputtering pressure by regulating the argon gas flow rate. The magnetron sputtering equipment is turned on, causing metal atoms on the target to be sputtered out under the bombardment of high-energy argon ions. The sputtered metal atoms move within the vacuum chamber and eventually deposit onto the surface of the substrate 10, forming a metal thin film, completing the deposition of the back electrode layer. Finally, the sputtering power supply and gas supply are turned off, and after cooling to room temperature, the vacuum chamber is opened, and the substrate with the deposited back electrode layer is removed.

[0073] Preferably, this application employs magnetron sputtering to deposit a back electrode layer on the back contact layer. The thickness of the deposited back electrode layer is 220-250 nm, thereby obtaining a semi-finished cadmium telluride thin-film solar cell. Preferably, the metal target used for depositing the back electrode layer is doped with As to deposit a p-doped back electrode. In this way, As diffuses from the back electrode layer into the CdSeTe layer of the light absorption layer, forming an As-containing p-doped CdSeTe absorption layer, thereby improving the efficiency and stability of the thin-film solar cell.

[0074] In addition, after the back contact layer and back electrode layer are deposited, scanning electron microscopes, X-ray diffraction, atomic force microscopes and other equipment can be used to characterize the surface morphology, crystal structure and thickness of the back contact layer and back electrode layer. The quality of the back contact layer and back electrode layer can also be evaluated by measuring the electrical properties such as resistivity of the back contact layer and back electrode layer, so as to reject unqualified products.

[0075] Laser scribing and packaging processes Using a laser processing platform, P1 grooves are laser-etched on the TCO layer of the substrate before the semiconductor thin film deposition process, P2 grooves are laser-etched on the light absorption layer before the back contact layer deposition process, and P3 grooves are laser-etched on the back contact layer and the back electrode layer after the back electrode deposition process, thereby realizing the series connection of cadmium telluride thin film solar cells.

[0076] Laser etching of the P1 grooves: The substrate 10 is placed on a laser processing platform, and its position is adjusted to ensure that the laser beam is precisely focused on the TCO layer of the substrate 10. The laser beam scans along a preset path, etching P1 grooves into the TCO layer. After etching, photoresist is filled to form an insulating layer. Since the TCO layer has good absorption of infrared light, near-ultraviolet or infrared lasers are preferably used for the P1 grooves, with a wavelength of 1064nm and a pulse energy between 100 and 200mJ, allowing the P1 grooves to penetrate the TCO layer. The P1 grooves divide the TCO layer into multiple independent conductive regions, preparing for subsequent cell cell division.

[0077] Laser etching of the P2 groove: A laser beam scans along a preset path to etch lines into the light-absorbing layer, creating the P2 groove. Since the light-absorbing layer has a high absorption rate for green light, green light with a wavelength of 532 nm and a pulse energy between 50 and 100 mJ is preferred for the P2 groove. The P2 groove divides the light-absorbing layer into multiple sub-cell units. The P2 groove is parallel to the P1 groove but slightly offset in position. During the deposition of the back contact layer, the material of the back contact layer is used to fill the P2 groove.

[0078] Laser etching of the P3 groove: A laser beam scans along a preset path, etching lines on the back contact layer and back electrode layer to create the P3 groove. The P3 groove is parallel to the P2 groove, but slightly offset in position. The P3 groove divides the back electrode into multiple independent electrode regions. After etching the P3 groove, photoresist is filled to form an insulating layer.

[0079] Preferably, after laser scribing is completed, multiple light-transmitting holes with a diameter of 40~60μm are laser-etched on the surface of the substrate after laser scribing. The light-transmitting holes extend from the back electrode layer to the substrate, allowing visible light to pass through the thin-film solar cell and enhancing the light transmittance of the cell.

[0080] Subsequently, preliminary performance tests were conducted on the laser-etched substrate to examine its current, voltage, and power. After passing the tests, butyl adhesive was applied to the outermost edge of the substrate, bonded with EVA, to achieve lamination and assembly. Further testing was performed after assembly to ultimately obtain the cadmium telluride thin-film solar cell product.

[0081] In summary, this invention effectively overcomes the shortcomings of the prior art and has high industrial application value.

[0082] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be within the scope of patent protection.

Claims

1. A manufacturing process for a thin-film solar cell, comprising a substrate pretreatment step, a semiconductor thin film deposition step, an activation annealing step, an etching step, a back contact layer deposition step, a back electrode deposition step, a laser scribing and encapsulation step, characterized in that, In the semiconductor thin film deposition process, the substrate is conveyed to the deposition chamber in the vacuum chamber. The semiconductor material source in the raw material storage tank is transported to the deposition chamber through the raw material delivery pipe, heated and converted into a gaseous state and deposited on the substrate. A semiconductor thin film is deposited on the TCO layer of the substrate. A heat-resistant valve is installed on the raw material delivery pipe.

2. The manufacturing process of the thin-film solar cell according to claim 1, characterized in that: The heat-insulating valve divides the raw material conveying pipe into a first feeding section connected to the raw material storage tank and a second feeding section located in the sedimentation chamber. The second feeding section has a raw material evaporation opening at one end in the sedimentation chamber. The raw material storage tank, the first feeding section and the heat-insulating valve are all located outside the sedimentation chamber. In the evaporation sedimentation mode, the temperature of the first feeding section is lower than the temperature of the second feeding section.

3. The manufacturing process of the thin-film solar cell according to claim 2, characterized in that: The raw material storage tank and the raw material conveying pipe constitute an evaporation source located in the sedimentation chamber. The evaporation source also includes a cooler located outside the sedimentation chamber and an evaporation heater located inside the sedimentation chamber. The cooler acts on the first feeding section, and the evaporation heater acts on the second feeding section inside the sedimentation chamber.

4. The manufacturing process of the thin-film solar cell according to claim 2 or 3, characterized in that: The temperature of the first feeding section is below 400℃, and the temperature of the second feeding section at the raw material evaporation opening is 750-1000℃.

5. The manufacturing process of the thin-film solar cell according to claim 3, characterized in that: The evaporation heater is integrated on the inner wall of the deposition chamber or on the second feeding section inside the deposition chamber.

6. The manufacturing process of the thin-film solar cell according to claim 3, characterized in that: The evaporation source also includes a preheater, which is located outside the deposition chamber and acts on a second feeding section outside the deposition chamber.

7. The manufacturing process of the thin-film solar cell according to claim 2, characterized in that: The first feeding section is a ceramic tube, and the second feeding section is a silicon carbide tube, a graphite tube, or a metal tube.

8. The manufacturing process of the thin-film solar cell according to claim 2, characterized in that: The wall thickness of the raw material conveying pipe is less than 5 mm, and the inner diameter of the raw material conveying pipe is less than 10 mm.

9. The manufacturing process of the thin-film solar cell according to claim 3, characterized in that: There are multiple evaporation sources, which are arranged in parallel along the width of the substrate.

10. The manufacturing process of the thin-film solar cell according to claim 1, characterized in that: The heat-resistant valve is a rotary feeder or a switching valve.

11. The manufacturing process of the thin-film solar cell according to claim 1, characterized in that: A feeding control valve is installed on the raw material conveying pipe. The feeding control valve and the heat-insulating valve are distributed sequentially along the conveying direction of the semiconductor material source in the raw material conveying pipe. The feeding control valve is a rotary feeder or a switching valve.

12. The manufacturing process of the thin-film solar cell according to claim 1, characterized in that: The bottom of the deposition chamber is provided with a gas outlet. The substrate is conveyed by a conveying device on the lower side of the deposition chamber. The conveying device includes several rotatable conveying rollers that act on the bottom of the substrate. In the semiconductor thin film deposition process, the TCO layer of the substrate faces upward, and the gaseous semiconductor material source is deposited from top to bottom on the TCO layer of the substrate from the gas outlet.

13. The manufacturing process of the thin-film solar cell according to claim 1, characterized in that: The raw material storage tank is located above the deposition chamber, and the semiconductor material in the raw material conveying pipe flows from top to bottom into the deposition chamber.

14. The manufacturing process of the thin-film solar cell according to claim 1 or 13, characterized in that: There are two raw material storage tanks. The raw material conveying pipe is a U-shaped pipe, including a U-shaped bend section and two straight pipe sections extending straight from both ends of the U-shaped bend section. The two raw material storage tanks are respectively connected to the two straight pipe sections. Each straight pipe section is equipped with a heat-insulating valve. The U-shaped bend section is located inside the sedimentation chamber and has a raw material evaporation opening.

15. The manufacturing process of the thin-film solar cell according to claim 1, characterized in that: In the semiconductor thin film deposition process, the substrate is cooled by a dynamic cooling device located in a vacuum chamber and positioned on the side of the substrate facing away from the deposition chamber. The dynamic cooling device includes a fixedly mounted vapor collection tube, a support tube rotatably mounted within the vapor collection tube, and substrate cooling components and cleaning heating components mounted on the support tube. The substrate cooling components and cleaning heating components are distributed circumferentially along the support tube. In the evaporation deposition mode, the substrate cooling component faces the substrate, the substrate cooling component is turned on, and the cleaning heating component is turned off; In self-cleaning mode, the cleaning heating component is turned on, the support tube rotates slowly, and the substrate cooling component is turned off.

16. The manufacturing process of the thin-film solar cell according to claim 15, characterized in that: The dynamic cooling device also includes a thermal insulation component installed on the support tube, which fills the space between the substrate cooling component and the cleaning heating component.

17. The manufacturing process of the thin-film solar cell according to claim 15, characterized in that: The vacuum chamber is equipped with a heating channel for heating the deposition chamber, and the temperature of the heating channel is higher than the temperature of the substrate.

18. The manufacturing process of the thin-film solar cell according to claim 1, characterized in that: In the substrate pretreatment process, a stepped heating method is used to preheat the substrate to ensure uniform heating.

19. The manufacturing process of the thin-film solar cell according to claim 1, characterized in that: In the activation annealing process, the prepared activation solution is coated onto the semiconductor thin film of the substrate, and the activation annealing temperature is set to 300-500℃.

20. The manufacturing process of the thin-film solar cell according to claim 1, characterized in that: In the etching process, the acid etching solution is sprayed onto the surface of the substrate after activation and annealing using a reciprocating spraying method.

21. The manufacturing process of the thin-film solar cell according to claim 1, characterized in that: In the back contact layer deposition process, a textured structure is etched onto the surface of the back contact layer using an acid solution.

22. The manufacturing process of the thin-film solar cell according to claim 1, characterized in that: In the back electrode deposition process, a p-doped material is deposited as the back electrode.

23. The manufacturing process of the thin-film solar cell according to claim 1, characterized in that: In the laser etching and packaging process, a laser processing platform is used to laser etch P1 grooves on the TCO layer of the substrate before the semiconductor thin film deposition process, to laser etch P2 grooves on the light absorption layer before the back contact layer deposition process, and to laser etch P3 grooves on the back contact layer and the back electrode layer after the back electrode deposition process. After etching P3 grooves, a light-transmitting hole is etched with a laser to enhance the light transmission characteristics.

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