Horizontal vacuum diffusion furnace

03-25-2026       Author: KJ technology

The horizontal vacuum diffusion furnace is a key equipment widely used in industries such as semiconductors and photovoltaics. The following provides a detailed introduction from the aspects of structural composition, working principle, characteristics, application fields, and operational precautions:

structural composition

Furnace body: It usually adopts a double-layer water-cooled structure, with the inner layer as the heating area and the outer layer cooled by cooling water to ensure that the temperature on the outer surface of the furnace body is not too high and to maintain the stability of the temperature inside the furnace. The furnace body is generally in a horizontal cylindrical shape.

Heating system: composed of heating elements (such as resistance wires, silicon carbide rods, etc.), insulation materials, and temperature control system. The heating elements are evenly distributed around the furnace to provide the required heat for the diffusion process; Thermal insulation materials reduce heat loss and improve energy utilization efficiency; The temperature control system precisely controls the temperature inside the furnace to ensure the stability of the diffusion process.

Vacuum system: including vacuum pump, vacuum valve, vacuum gauge, etc. Vacuum pumps are used to extract gas from the furnace and create a vacuum environment; Vacuum valves can control the on/off and flow rate of gases; The vacuum gauge monitors the vacuum level inside the furnace in real-time and feeds back the signal to the control system.

Gas supply system: composed of gas source, gas pipeline, flow controller, and gas distribution device. The gas source provides the necessary gases for diffusion, such as phosphorus source gas, boron source gas, etc; Gas pipelines transport gas into the furnace; The flow controller precisely controls the flow rate of gas; The gas distribution device evenly distributes the gas inside the furnace, ensuring the uniformity of diffusion.

Shiyingzhou and transmission system: Quartz boats are used to carry silicon wafers or other samples to be diffused, and they have good high temperature resistance and chemical stability. The transmission system can smoothly feed or pull the quartz boat into or out of the furnace, achieving the loading and unloading of samples.

working principle

Place the silicon wafer to be diffused on a quartz boat in a vacuum environment and send it into a heated furnace. Then, a gas containing diffusion impurities is introduced into the furnace through a gas supply system. Under high temperature, the impurity atoms obtain sufficient energy, decompose from the gas, and diffuse into the silicon wafer, thereby changing the electrical properties of the silicon wafer and achieving doping and other purposes.

A commonly used horizontal diffusion vacuum furnace (click on the image to view product details)

Feature

Good diffusion uniformity: A reasonable furnace structure and gas distribution device ensure that the gas is evenly distributed inside the furnace, and the silicon wafer can uniformly accept the diffusion of impurity atoms during the diffusion process, ensuring the consistency of product performance.

Accurate temperature control: The advanced temperature control system can accurately control the temperature inside the furnace near the set value, with a small temperature fluctuation range, meeting the requirements of high-precision diffusion technology.

Pure vacuum environment: The vacuum system can effectively eliminate air and other impurity gases inside the furnace, reduce the interference of impurities on the diffusion process, and improve the diffusion quality and product purity.

High degree of automation: From the entry and exit of quartz boats, temperature control to gas flow regulation, all operations can be automated, improving production efficiency and reducing manual errors and labor intensity.

Application field

Semiconductor manufacturing: used in the doping process of silicon wafers, such as in the manufacturing of transistors, integrated circuits, etc., impurities such as phosphorus and boron atoms are diffused into the silicon wafer through a diffusion furnace to form structures such as PN junctions, achieving the control of semiconductor conductivity.

Photovoltaic industry: In the production of solar cells, diffusion furnaces are one of the key equipment. By using diffusion technology to form P-N junctions on the surface of silicon wafers, light energy is converted into electrical energy, improving the conversion efficiency of solar cells.

Operation precautions

Equipment inspection: Before each use, carefully check whether each system of the equipment is normal, including whether the vacuum system is leaking, whether the gas supply system pipeline is unobstructed, and whether the temperature control system is accurate.

Parameter setting: According to different process requirements, accurately set parameters such as temperature, time, gas flow rate, vacuum degree, etc., and ensure the stability and accuracy of the parameters.

Sample placement: Place silicon wafers or other samples neatly on a quartz boat to avoid collisions and overlaps between samples and ensure uniform diffusion.

Safety protection: During the operation of the equipment, if the temperature of the furnace body is high, it is necessary to prevent burns; At the same time, some diffused gases may be toxic or flammable, so ventilation and protective measures should be taken to avoid gas leaks causing harm to human health.

Maintenance: Regularly clean and maintain the equipment, remove impurities and residues from the furnace, inspect and replace worn parts, and ensure the normal operation and service life of the equipment.