A boron nitride (BN) film was deposited on an n-type Si wafer at about 500~ by the thermal reaction of diborane and ammonia in nitrogen. The boron diffusion into Si was performed in nonoxidizing ambients both during the deposition of the BN on the Si and the subsequent heat-treatment. To obtain the reproducibility of the boron surface concentration at its solid solubility at the diffusion temperature, the BN has to be covered with SigN4, which is deposited at about 750~ in a silane-ammonia-nitrogen system. No silicon-boride formation at the interface of the BN and Si was confirmed. The resistivity of the BN was determined as p --101a-1014 ~l-cm. The BN can be used not only as a boron diffusion source but also as a surface passivation of integrated circuits when the BN and Si3N4 remained after the boron diffusion.Boron diffusion into Si from CVD-BN films as a diffusion source was reported previously (1). The BN had been deposited in a hydrogen carrier gas at a high deposition temperature range of 700~176 When the BN was used in a practical integrated circuit process, the authors found that less reproducible boron surface concentrations were often observed due to the change of the BN during the boron diffusion heattreatment in nitrogen. In addition, the writers also found that the low temperature deposition of the BN at about 500~ in nitrogen and the over-coat deposition of SigN4 on the BN were effective in maintaining the reproducibility of the boron surface concentrations at its solid solubility.Fair summarized the boron diffusion into Si from various diffusion sources (2). When the boron surface concentration exceeds the intrinsic carrier concentration at a diffusion temperature, the effects of electric field enhancement caused by the increase of donortype vacancies have to be taken into account. Fair's analysis was employed in this work to determine the boron diffusion characteristics from BN in nonoxidizing ambients.In the final section of this report an application of the BN to master slice p-MOS IC is shown, in which the resistivity of the BN was determined, and the BN was used not only as a diffusion source of boron but also as a surface passivation when it remained after the boron diffusion. ExperimentalThe experimental apparatus for the BN and Si3N~ deposition has been described previously (1). A quartz reaction chamber used in this work had an internal width of 35 mm, a height of 20 mm, and a length of 400 mm. The reactant gases used for the BN deposition were high purity diborane (B2H6) diluted to 5% in nitrogen and ammonia (NHs), and those gases for the Si3N4 deposition were high purity silane (SiH4) diluted to 5% in nitrogen and ammonia. The carrier gas was high purity nitrogen.First, the BN was deposited on the n-type (100) Si wafer with a resistivity of 3-5 f~-cm (ND = 0.9-1.5 • 1015 cm-~). The deposition conditions were: (i) a wafer temperature of 500~ and (ii) flow rates of the B2H6-N2, the NI-I3, and the N2 carrier gases of 50, 70, and 2000 cm3/min, respectively. Under those conditions * Electroc...
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