What gases can be supplied to the rapid temperature rise and fall annealing furnace?

The rapid temperature rise and fall annealing furnace (RTP) can introduce a wide range of gases, mainly divided into three categories: inert protective gases, active process gases, and mixed gases. The specific selection needs to be determined based on material characteristics, process objectives, and equipment compatibility. The following are detailed classification and application instructions:

1.Inert protective gas
Function: Isolate oxygen to prevent material oxidation or contamination; Provide a stable process environment.
Common gases and their characteristics:
Nitrogen (N ₂)
Characteristics: Low cost, easy to obtain, chemically stable, but may react with certain metals (such as titanium) to form nitrides at high temperatures.
Application:
Crystalline silicon solar cells: N ₂ is applied during annealing to prevent silicon wafer oxidation and improve cell efficiency.
Semiconductor packaging: protects chips from oxidation and reduces interface defects.
Case: A photovoltaic company used N ₂ protective annealing to treat PERC cells, resulting in a decrease in the composite current density of the passivation layer.
Argon gas (Ar)
Characteristics: More inert, does not react with most materials, but has a higher cost than N ₂.
Application:
High purity semiconductor materials: such as silicon wafer annealing, to avoid the introduction of oxygen impurities.
Metal film treatment: prevents oxidation of metals such as copper and aluminum at high temperatures.
Case: A certain photovoltaic company uses Ar gas protection annealing in the manufacturing of 7nm chips, which reduces the resistivity of the metal interconnect layer.
Helium (He)
Characteristics: High thermal conductivity, can accelerate temperature homogenization inside the furnace, but the cost is extremely high and prone to leakage.
Application:
High precision temperature control: For example, annealing quantum dot solar cells requires rapid and uniform heating.
Special material processing: such as graphene transfer process to reduce thermal stress.
Case: An electronics company introduced He gas during annealing after graphene growth, which improved the uniformity of grain size.

2. Active process gas
Function: Participate in chemical reactions to achieve material modification or thin film deposition.
Common gases and their characteristics:
Hydrogen (H ₂)
Characteristics: Strong reducibility, capable of removing surface oxide layers of materials, but flammable and explosive, requiring strict safety control.
Application:
Crystalline silicon solar cells: During annealing, H ₂ is used to reduce the silicon oxide on the surface of the silicon wafer, thereby improving the carrier lifetime.
Semiconductor devices: repair ion implantation damage, activate doping elements.
Case: A new material company uses H ₂ annealing in battery manufacturing to passivate and reduce contact resistance.
Ammonia gas (NH3)
Characteristic: Provides a nitrogen source for nitride film growth or material nitriding treatment.
Application:
Gallium Nitride (GaN) Thin Film: During annealing, NH3 promotes GaN crystallization and improves the quality of the film.
Metal surface hardening: such as nitriding treatment of titanium alloys to improve wear resistance.
Case: In the manufacturing of GaN LED chips by a certain optoelectronic company, NH ∝ annealing reduces the dislocation density.
Oxygen (O ₂)
Characteristic: Strong oxidizing property, requiring precise flow control to avoid excessive oxidation.
Application:
Transparent conductive oxide (TCO) film: During annealing, O ₂ is introduced to optimize the crystallinity of ITO film and reduce its resistivity.
Perovskite solar cells: controlling the O ₂ partial pressure promotes the growth of perovskite grains and enhances stability.
Case: A certain nanotechnology company achieved a T80 lifespan of over 10000 hours through O ₂ annealing in the manufacturing of perovskite components.
Silane (SiH ₄)
Characteristics: Flammable and explosive, requiring dilution with inert gas, used for silicon-based thin film deposition.
Application:
Amorphous silicon thin film solar cell: During annealing, SiH ₄ is used to deposit an intrinsic amorphous silicon layer, which increases the short-circuit current of the cell.
Semiconductor packaging: Deposition of silicon oxide as a passivation layer.
Case: A new energy company optimized the bandgap gradient of the absorption layer and improved efficiency through SiH ₄ annealing in copper indium gallium selenide batteries.

3. Mixed gas
Function: Combining multiple gas characteristics to meet complex process requirements.
Common combinations and characteristics:
N ₂+H ₂ (forming gas)
Proportion: Typically 95% N ₂+5% H ₂.
Application:
Semiconductor annealing: simultaneously providing a protective atmosphere and reducing properties, repairing ion implantation damage.
Photovoltaic cells: Annealing the passivation layer on the back of PERC cells reduces the risk of hydrogen explosion.
Case: A solar energy company uses formation gas annealing in battery manufacturing to reduce the composite current density of the passivation layer.
Ar+NH₃
Proportion: Adjust according to the process (such as 70% Ar+30% NH3).
Application:
Nitride film growth: such as AlN film annealing, to improve thermal conductivity.
Metal surface treatment: Nitriding annealing of titanium alloy to form a TiN hard layer.
Case: In the manufacturing of 5G chips, a certain chip company improved the thermal conductivity of the heat dissipation layer through Ar+NH3 annealing.
N₂+O₂
Proportion: Typically 90% N ₂+10% O ₂.
Application:
Optimization of transparent conductive films: such as annealing AZO (aluminum doped zinc oxide) films to balance conductivity and transmittance.
Perovskite battery packaging: controlling the O ₂ partial pressure to promote crystallization of the packaging layer and enhance water vapor barrier properties.
Case: A certain optoelectronic company used N ₂+O ₂ annealing to reduce the water vapor transmission rate in perovskite module packaging.

4. Core principles of gas selection
Material Compatibility
Avoid the reaction between gases and materials to generate harmful substances (such as TiH ₂ generated by H ₂ and Ti at high temperatures, which can cause embrittlement).
Example: Annealing graphite materials should avoid O ₂ to prevent oxidation losses.
Process objectives
Oxidation protection: prioritize N ₂ Ar。
Surface modification: Choose H ₂, NH ∝, O ₂ according to the reaction requirements.
Thin film deposition: Select precursor gases such as SiH ₄ and NH ∝.
Device restrictions
Confirm the gas corrosion resistance of the furnace body material (such as stainless steel 316L resistant to N ₂ Ar， But special treatment is required to resist H ₂ and NH ∝.
Verify the safety of the gas supply system (e.g. H ₂ requires explosion-proof devices, SiH ₄ requires stainless steel pipes).
Balancing Cost and Efficiency
High purity gases (such as 9N grade Ar) have high costs and need to be selected according to process accuracy requirements.
Mixing gases can reduce the usage of a single gas and lower overall costs.

Conclusion: The rapid temperature rise and fall annealing furnace can be equipped with a multi-channel gas supply system to introduce inert gas, active gas, or mixed gas. The specific selection needs to be based on material characteristics, process objectives, equipment compatibility, and cost factors. In practical applications, it is recommended to optimize the gas ratio and flow rate through process experiments to achieve the best annealing effect.