Customized PECVD electric furnace temperature

When customizing PECVD electric furnaces, temperature parameters should focus on the deposition temperature range, temperature control accuracy, temperature uniformity, maximum temperature and equipment compatibility, as well as multi-stage programmable temperature curve settings. The specific analysis is as follows:

1. Core temperature parameter requirements
Sedimentary temperature range
Conventional range: PECVD process allows for substrate temperature adjustment from room temperature to 400 ℃ (some scenarios can be extended to 500 ℃), with common operating temperatures ranging from 200 ℃ to 450 ℃. For example, during polycrystalline silicon coating, the furnace tube temperature is often set at 450 ℃, and the annealing stage temperature can be raised to 500-850 ℃.
Advantages of low-temperature process: By utilizing plasma energy, low-temperature deposition can be achieved (from room temperature to 350 ℃), avoiding damage to substrates (such as plastic substrates) caused by high temperatures. For example, when depositing silicon nitride films on plastic substrates, the process temperature can be controlled below 250 ℃.
High temperature process requirements: If high-temperature annealing treatment is required (such as optimizing the hydrogen atom concentration in polycrystalline silicon layers), the equipment needs to support a temperature range of 600-850 ℃.
temperature control accuracy
Key indicators: Adopting PID control and self-tuning adjustment technology to achieve temperature control accuracy of ± 1 ℃. For example, the continuous PE-CVD coating equipment is equipped with a LCD touch control system that supports 30 programmable temperature curve settings to ensure process repeatability.
Application scenario: Thin film stress optimization requires controlling the film density through the temperature of the lower electrode plate. Every 100 ℃ increase in temperature can increase the film density by 15% -20%, and the temperature control accuracy directly affects the film performance.
temperature uniformity
Importance: The temperature distribution inside the furnace should be uniform, otherwise it may cause uneven film thickness or composition. For example, the photovoltaic industry requires a film thickness uniformity of ≤± 5%, which needs to be achieved through multi-point RF feeding, uniform gas path distribution, and intelligent temperature control systems.
Design points: Large furnaces require zone heating design to reduce temperature differences; Quartz tube furnace needs to be matched with high-purity alumina ceramic fiber furnace to improve heat conduction efficiency.

2. Equipment performance and temperature matching
Maximum temperature and equipment type
Conventional equipment: Most PECVD electric furnaces have a maximum temperature of 1200 ℃ and a working temperature of ≤ 1100 ℃, suitable for conventional thin film deposition (such as SiO ₂, Si ∝ N ₄).
High temperature equipment: Some special equipment (such as 1600 ℃ high-temperature PECVD) can reach a maximum temperature of 1600 ℃ and a working temperature of ≤ 1500 ℃, suitable for the growth of high-temperature materials such as diamond and graphene.
Selection criteria: Select the highest temperature of the equipment based on the target thin film material (such as 500-850 ℃ for polycrystalline silicon annealing) to avoid excessive design or insufficient performance.
Heating system design
Heating element: High temperature resistant and corrosion-resistant materials (such as silicon molybdenum rods and graphite) are selected to extend the service life of the equipment.
Heating rate: Recommended for temperatures below 1000 ℃ ≤ 10 ℃/min, with the fastest heating rate ≤ 30 ℃/min to avoid substrate deformation or film cracking caused by thermal stress.
Cooling rate: above 700 ℃ ≤ 10 ℃/min, to prevent rapid cooling from causing stress concentration in the film.

3. Process compatibility and safety design
Process compatibility
High temperature risk: High temperature may cause interface diffusion between the substrate and the film (such as metal substrate oxidation), and the impact of process temperature on the substrate material needs to be evaluated in advance.
Pressure matching: Under the same flow conditions, precise control of membrane stress within the range of -260MPa to+500MPa can be achieved by adjusting the chamber pressure (positive pressure range -100kPa to 100kPa), ensuring coordinated optimization of temperature and pressure parameters.
safety design
High temperature protection: When the furnace temperature of the equipment is ≥ 200 ℃, it is forbidden to open the furnace to avoid burns; When the temperature of the furnace body is higher than 1000 ℃, the pressure inside the furnace tube should be equivalent to atmospheric pressure to prevent the furnace tube from breaking.
Pressure monitoring: The pressure inside the furnace tube shall not exceed 0.02MPa (absolute pressure), and mechanical pressure gauges and composite vacuum gauges shall be equipped for real-time monitoring.