Application of experimental tubular CVD electric furnace in the solar cell industry

The application of experimental tubular CVD electric furnaces in the solar cell industry is extensive and critical, mainly reflected in thin film deposition, process optimization, cell structure innovation, low-temperature process advantages, equipment function expansion, and other aspects.

Thin film deposition: The tubular CVD electric furnace is the core equipment for depositing anti reflective and passivation films in solar cell manufacturing. For example, depositing a silicon nitride (SiNx) anti reflection film on the surface of a crystalline silicon solar cell, adjusting the film thickness and refractive index, and utilizing the principle of light interference to reduce surface reflection, can increase the photoelectric conversion efficiency by 1% -2% by allowing more light to enter the interior of the cell. Meanwhile, the hydrogen element in SiNx can passivate lattice defects on the silicon surface, such as dislocations and dangling bonds, reduce carrier recombination, and increase open circuit voltage and short-circuit current.

Process optimization: PECVD technology (plasma enhanced chemical vapor deposition) uses plasma to excite reaction gases, reducing the deposition temperature to 400-500 ℃, while traditional CVD requires above 800 ℃. This low-temperature process avoids thermal damage to silicon wafers and substrate materials caused by high temperatures, and is particularly suitable for the manufacturing of thin and flexible batteries. In addition, radio frequency glow technology generates high-density plasma through high-frequency electric fields (such as 13.56MHz), greatly improving the reaction rate, and the deposition rate can reach 10-50nm/min.

Innovation in battery structure: The tubular CVD electric furnace can deposit various dielectric films, such as SiO ₂, Si ∝ N ₄, Al ₂ O ∝, etc., expanding the design space of battery structures. For example, in PERC cells, the dual function of backside passivation and anti reflection is achieved by depositing a backside Al ₂ O ∝/SiNx stacked film; In TOPCon cells, efficient carrier transport channels are constructed by depositing a tunneling oxide layer (SiO ₂) and a doped polycrystalline silicon layer using PECVD; In HJT cells, intrinsic amorphous silicon (i-a-Si: H) is deposited at the interface of amorphous silicon/crystalline silicon heterojunction to optimize the density of interface defect states.

Advantages of low-temperature process: Low temperature process not only reduces energy consumption, but also avoids the emission of harmful substances at high temperatures, which is in line with the trend of green manufacturing in the photovoltaic industry. Meanwhile, the low-temperature process makes the battery manufacturing process more stable, improving product yield and reliability.

Equipment Function Expansion: The tubular CVD electric furnace is equipped with multi-point RF feeding, uniform gas path distribution, and intelligent temperature control system to ensure film thickness uniformity of ≤± 5%, meeting the needs of large-scale production. In addition, the device also supports advanced functions such as pressure control (positive pressure range -100kPa to 100kPa, supporting low-pressure to atmospheric process switching), temperature curve programming (supporting more than 30 temperature rise and fall programs), etc., to adapt to the process requirements of different film materials.