A PECVD tube furnace (Plasma-Enhanced Chemical Vapor Deposition Tube Furnace) is a deposition system that combines plasma excitation with a heated tubular reaction chamber. It utilizes high-frequency radio frequency (RF) or microwave power to generate plasma within the reaction chamber, decomposing and activating the precursor gas. This enables thin film deposition even at relatively low substrate temperatures (typically 100–400°C).

Compared to traditional thermal CVD, PECVD offers the following key advantages:

Low-temperature deposition (lower than 200°C)

High deposition rate

Dense film quality and excellent adhesion

Ability to deposit temperature-sensitive substrates (such as plastics and optical polymers)

Typical applications include:

Semiconductor passivation layers (Si₃N₄, SiO₂)

Photovoltaic thin films (a-Si:H, transparent conductive films)

Optical coatings

Hard and wear-resistant coatings (DLC, TiN)

Corrosion protection and barrier films

PECVD Process Principle

The core principle of PECVD is to introduce process gases into a tube furnace and generate plasma using radio frequency (commonly 13.56 MHz) or microwave power. This ionizes and activates gas molecules or free radicals, enabling chemical reactions at relatively low substrate temperatures and deposition as a solid film.

Main Process:

Gas Introduction

Precursor gases (such as SiH₄, NH₃, CH₄, CF₄, etc.) are mixed with inert gases (Ar, He)

Precisely proportioned using a mass flow controller (MFC)

Plasma Excitation

RF or microwave source generates glow discharge in the reaction zone

Generates active species such as electrons, ions, and free radicals

Surface Reaction and Film Formation

Activated species reach the substrate surface, adsorb, and participate in chemical reactions

Forms a dense, uniform film

Byproduct Exhaust

Gaseous byproducts (such as H₂, NH₃, CO₂) generated by the reaction are exhausted via a vacuum pump

Purified by the exhaust gas treatment system before discharge

PECVD Tube Furnace Structure

Heating Furnace

Single/Dual/Triple Zone Heating

PID Temperature Control (±1–±2°C) Accuracy)

Insulation material: Lightweight ceramic fiber

Furnace tube

Commonly used: quartz tube (SiO₂) or corundum tube (Al₂O₃)

Diameter Φ40–150 mm, length 800–1500 mm

Gas system

Multi-channel MFC (0–200 sccm / 0–1 slm)

Gas mixing manifold, needle valve, check valve

Plasma generation system

RF power supply (13.56 MHz, 100–600 W) + matching network

Or microwave power supply (2.45 GHz)

Electrode structure: Parallel plate / annular / coaxial

Vacuum system

Mechanical pump or dry pump

Back pressure valve + capacitance diaphragm vacuum gauge (accuracy ±0.1 mTorr)

Exhaust Gas Treatment

Burner, Acid/Base Scrubber, Activated Carbon Adsorption Tower

Safety System

Gas Leak Detection (H₂, SiH₄, NH₃)

Overtemperature, Overpressure, and Discharge Interlock

Emergency Stop Switch

PECVD Tube Furnace Workflow

Sample Loading: Place the substrate in the center of the furnace tube and secure it to the sample holder.

Evacuation/Displacement: Evacuate to a set vacuum (e.g., 50 mTorr) or replace with Ar/N₂.

Steady-State Temperature Ramp: Heat to a set temperature (100–400°C).

Gas Feed: Turn on the MFC to supply the reaction and carrier gases.

Plasma Start: Turn on the RF/microwave power supply and adjust the power to achieve a stable discharge.

Deposition Reaction: Maintain the set temperature, pressure, gas flow, and power for a period of time.

Shut Off the Plasma/Introduce Inert Gas: Terminate the reaction and prevent oxidation.

Cooling/Sampling: Remove the substrate after cooling to a safe temperature.

PECVD Tube Furnace Technical Parameters

Model	YX-1200P
Rated total power	3.2KW (heating furnace: 2.6KW, radio frequency unit: 0.15KW, vacuum unit: 0.45KW)
Maximum temperature	1200℃
Continuous operating temperature	≤1100℃
Recommended heating rate	≤10°C/min
Temperature measuring element	K-type thermocouple
Heating zone length	Dual independent heating zones: 230mm + 230mm
Furnace tube dimensions	Φ50 x 1900mm
Temperature control method	FFuzzy PID control and auto-tuning, intelligent 30-segment programmable control, over-temperature and burnout alarms
Temperature control accuracy	±1°C
Heating element	Resistance wire
RF power	150W

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