AVS 62nd International Symposium & Exhibition
    Plasma Science and Technology Thursday Sessions
       Session PS+AP+SE-ThA

Invited Paper PS+AP+SE-ThA3
Conformal Arsenic Doping using a Radial Line Slot Antenna Microwave Plasma Source

Thursday, October 22, 2015, 3:00 pm, Room 210B

Session: Advanced Ion Implantation and Plasma Doping
Presenter: Hirokazu Ueda, Tokyo Electron Limited, Japan
Authors: H. Ueda, Tokyo Electron Limited, Japan
P. Ventzek, Tokyo Electron America, Inc.
M. Oka, Tokyo Electron Ltd.
Y. Kobayashi, Tokyo Electron Ltd.
Y. Sugimoto, Tokyo Electron Ltd.
T. Nozawa, Tokyo Electron Ltd., Japan
S. Kawakami, Tokyo Electron Ltd.
Correspondent: Click to Email
Doping and activation of non-planar topographic structures is important for the fabrication of functional FinFET and nanowire based devices to name a few. Conformal plasma arsenic doping of topographic (fin) structures was achieved using RLSATM microwave plasmas with low temperature annealing. To show that the arsenic concentrations were identical at the fin top and sides, dopant concentrations were measured precisely by TEM and SEM EDX for both plasma doping and subsequent annealing steps. We found that doping using plasmas generated by lower RF bias operation coincident with high microwave power was key to obtaining perfectly conformal arsenic dose/profiles after annealing. The RLSATM microwave plasma facilitates high enough electron density at the plasma generation region to supply enough reactive dopants for sufficient dose. The high plasma density plasma allows for operation in a low RF power and high process pressure regime. This regime yields ions with sufficient flux and energy for dopant integration into and redistribution around the topographic structure. At the same time low enough energy ions can be controllably accessed to ensure fin damage is eliminated. We also demonstrate optimized rf bias power of the microwave RLSATM plasma enables additional control of dopant conformality post SPM wet cleaning step. The wet clean poses a significant challenge for dose retention as cleans tend to remove oxidized or otherwise disordered silicon material. The source of dose retention is shown to be related to dopant transport through a ternary (As-Si-O) oxide layer, segregation effects and the stable nature of the oxide. The presentation will include experimental and computational results related to dose conformality and retention. Comments related to the future of plasma doping technology including advanced materials, metrology and control will round out the presentation.