Low thermal budget in situ cleaning and passivation for silicon epitaxy in a multichamber rapid thermal processing cluster tool

Abstract

In this Letter, we report our results on surface preparation, involving in situ cleaning and passivation for low-temperature Si epitaxy in a multichamber cluster tool. The experiments were carried out in a three-chamber reactor which mimics a cluster tool. The results indicate that residual O on the dilute HF-treated Si surface (ex situ cleaned) can be reduced below the detection limit of secondary ion mass spectroscopy (SIMS) by in situ baking at 750°C for 15 s in an ultra-high vacuum environment or in H 2 ( pressure = 240 mTorr). We show that the extremely reactive Si surface can be passivated against recontamination by exposing it to a low-pressure Si 2H 6 environment at the ambient temperature immediately following the in situ clean. When the unpassivated samples are exposed to an air pressure of 10 −6 Torr in the load-lock, O adsorbs on the surface up to 50% of a monolayer within 10 min. Under the same conditions, with passivation, the oxygen levels remain below the detection level of SIMS. Surface passivation will be extremely useful in applications that require wafer transfer between chambers such as in multichamber cluster tools.