ion implantation chamber

An ion implantation chamber is the vacuum system where dopant ions are accelerated and directed into the semiconductor wafer to modify its electrical properties. **Vacuum**: Maintained at 10^-5 to 10^-7 Torr to prevent ion scattering by gas molecules and maintain beam purity. **Major components**: Ion source, mass analyzer magnet, acceleration column, beam scanning system, wafer handling end station. **Beam path**: Ions extracted from source, filtered by mass analyzer, accelerated to target energy, scanned across wafer. **End station**: Where wafer is held during implantation. Includes wafer chuck (cooled or heated), Faraday cup for dose measurement, charge neutralization. **Dose control**: Beam current measured in real-time by Faraday cup. Total dose controlled by integrating current over time. **Uniformity**: Beam scanned across wafer (electrostatic or mechanical scanning) for uniform dose distribution. **Types**: **Beamline**: Traditional architecture with mass analyzer and acceleration tube. **Plasma immersion (PLAD)**: Wafer immersed in plasma, ions extracted by pulsed bias. Higher throughput for high-dose implants. **Energy range**: Low energy (0.2-10 keV) for shallow junctions. Medium (10-200 keV) for wells. High (200 keV - several MeV) for deep implants. **Safety**: High voltage, radiation, toxic gases (AsH3, PH3, BF3) require extensive safety systems.