Peking University Improvement of Multilayer Film Growth for Accelerator Cavity by ECR deposition Jiao, Fei

Peking University Background 1 Present work 2 Future Plan 3 Contents

Peking University Background

Peking University Thin film technics to improve gradient and Q0 Accelerating Field E acc (MV/m) Magnetic field B (mT) Quality coefficient Q 0 Two aspects: Increase gradient: increase H sh Increase the Q 0 : decrease surface resistance

Peking University Accelerating Field E acc (MV/m) Magnetic field B (mT) Quality coefficient Q 0 layer bulk Using multi-layer to increase gradient and Q0 further H0H0 HiHi d A. Gurevich, APL 88, (2006)

Peking University Candidate materials for thin film

Peking University Pit Extrusion Problem : surface defect

Peking University  Dust on substrate  Pin-hole in the pre-layer  Damage from following deposition process Surface defect may be caused by:

Peking University ECR Method: Idea and Plan

Peking University PIIID: Plasma Immersion Ion Implantation and Deposition IBAD: Ion Beam Assisted deposition PLD: Plasma Laser Deposition VAD ： vacuum arc deposition IBA-MBA: Ion beam assisted molecular beam epitaxy MS: Magnetron Sputtering Low energy of deposited particle is preferred to reduce destroy to pre-layer

Peking University source Magnetron sputtering Plasma evaporation Nb+ Low damage of Plasma method

Peking University ECRRF sputtering frenquency2.45GHz13.56MHz Pressure0.05Pa10Pa Electron density Particles energyLess than 30eV<100eV ECR: electron cyclotron resonance Comparison between ECR and RF sputtering Lower pressure, higher electron density, lower particle energy is good for multilayer deposition

Peking University Power supply Microwave transport system Newly designed ECR deposition system Target chamber Deposition chamber benefit No plasma gun pollution Substrate cleaned by plasma No target pollution ECR produce substrate coil

Peking University Deposition Vaccum and magnetic field distrubution

Peking University Target chamber

Peking University characteristic Company Logo  Low energy ： protect the film deposited  Flash evaporation ： high efficiency  cleaness

Peking University Future plan Multilayer film research Single-layer film research Instrument design Investigation H c1 Rs 、 Q0 H c1 R s Plasma transport, control Choose material

Peking University