Bonded hydrogen in silicon nitride films deposited by remote plasma-enhanced chemical vapour deposition

Abstract

Using FTIR the hydrogen content of silicon nitride films grown by remote plasma-enhanced CVD (RPECVD) has been quantitatively examined. The influences of process parameters on the concentration of bonded hydrogen and on its nature are discussed. It is suggested that the incorporation of Si—H bonds is largely determined by gas-phase processes while that of N—H bonds arises from surface interactions. The preferential type of hydrogen bonding to silicon is found to occur as Si—H₂ whereas for nitrogen N—H appears to be the most likely form of bonding. The total hydrogen content of capacitively coupled RPECVD films is found to be only ca. 9 × 10²¹ cm^–3 at a growth rate ca. 20 times that obtainable by inductively coupled RPCEVD. Therefore there is considerable potential for depositing films with very low total hydrogen content by capacitively coupled RPECVD.