Effects of magnetic field on pulse wave forms in plasma immersion ion implantation in a radio-frequency, inductively coupled plasma

Abstract

The time-dependent current wave forms measured using a pulse biased planar electrode in hydrogen radio-frequency (rf), inductively coupled plasma, plasma immersion ion implantation experiments are observed to vary in the presence of an external magnetic field B. Results further indicate that the magnitude of the pulse current is related to the strength and direction of the magnetic field, rf power, and pressure, but the pulse current curves can be primarily correlated with B. The plasma discharges are enhanced in all cases due to magnetic confinement of the electrons, enlargement of the plasma generation volume, and increase in the rf power absorbing efficiency. The plasma density diagnosed by Langmuir probe diminishes in front of the sample chuck with B, whereas the plasma is confined nearby the sidewall of the vacuum chamber at high magnetic field. The high degree of plasma density nonuniformity at high B in front of the sample chuck is not desirable for the processing of planar samples such as silicon wafers and must be compensated. The reduction in the plasma density and plasma density gradient in the sheath can be accounted for by the changes in the pulse current wave forms.