PH3 surface chemistry on Si(111)-(7×7): A study by Auger spectroscopy and electron stimulated desorption methods

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Abstract
The adsorption and decomposition of PH3 on Si(111)‐(7×7) was investigated in ultrahigh vacuum by means of temperature programmed desorption, low‐energy electron diffraction, Auger electron spectroscopy (AES), and electron stimulated desorption (ESD) methods. Phosphine adsorbs on Si(111)‐(7×7) at T=120 K with an initial sticking coefficient of S0≂1 through a mobile (extrinsic) precursor state. Some PH3 dissociative adsorption at 120 K is observed. Thermal activation of the adsorbed species results in desorption of a molecular PH3 species up to 550 K. Further heating produces H2(g) desorption at T≂740 K and P2(g) desorption at T≂1010 K, thus indicating that PH3 decomposition has occurred. AES and ESD studies of the adsorbed species reveal that decomposition takes place by the breaking of PH bonds in PHx(a) to form SiH species on the surface for 120 K<T<700 K.