Steady-state direct-current plasma immersion ion implantation using a multipolar magnetic field electron cyclotron resonance plasma source

In semiconductor plasma immersion ion implantation (PIII) applications such as the synthesis of silicon-on-insulator by hydrogen PIII and ion cut, onl y ions arriving at the top surface of the sample stage are important. The i ons implanted into the other surfaces of the sample chuck actually not only decrease the efficiency of the power supply and plasma source but also giv e rise to metallic contamination. In addition, low energy ions introduced b y the initial plasma sheath propagation, pulse rise time, and pulse fall ti me introduce a large surface hydrogen concentration that creates surface da mage and affects the wafer bonding efficacy. We have theoretically demonstr ated direct-current PIII (DC-PIII) which retains the x - y immersion charac teristic while simultaneously reducing this low energy ion component, obvia ting the need for the expensive power modulator, and extending the voltage ceiling that is no longer limited by the vacuum chamber and power modulator . In this article, we describe our hydrogen DC-PIII experiments using a con ducting grid placed between the wafer stage and a multipolar electron cyclo tron resonance plasma source. The grounded grid stops the propagation of th e plasma sheath, thereby removing the vacuum chamber size limitation. Ions are formed in the plasma sustained by an external plasma source above the g rid and accelerated through the lower zone to be implanted into the wafer b iased by only a dc power supply. Atomic force microscopy, hydrogen forward scattering, and secondary ion mass spectrometry analyses indicate uniform h ydrogen PIII into a 100 mm silicon wafer and the surface hydrogen component is indeed reduced significantly compared to conventional pulsed PIII. (C) 2001 American Vacuum Society.