LOW THERMAL BUDGET IN-SITU CLEANING AND PASSIVATION FOR SILICON EPITAXY IN A MULTICHAMBER RAPID THERMAL-PROCESSING CLUSTER TOOL

In this Letter, we report our results on surface preparation, involvin g in situ cleaning and passivation for low-temperature Si epitaxy in a multichamber cluster tool. The experiments were carried out in a thre e-chamber reactor which mimics a cluster tool. The results indicate th at residual O on the dilute HF-treated Si surface (ex situ cleaned) ca n be reduced below the detection limit of secondary ion mass spectrosc opy (SIMS) by in situ baking at 750-degrees-C for 15 s in an ultra-hig h vacuum environment or in H2 (pressure = 240 mTorr). We show that the extremely reactive Si surface can be passivated against recontaminati on by exposing it to a low-pressure Si2H6 environment at the ambient t emperature immediately following the in situ clean. When the unpassiva ted 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 extrem ely useful in applications that require wafer transfer between chamber s such as in multichamber cluster tools.