Influence of the methyl group on the dielectric constant of boron carbon nitride films containing it

LSI interconnect insulators made using low dielectric constant (low-k) materials are required for high performance devices with a small RC delay. We investigated a boron carbon nitride film containing the methyl group (Me–BCN) using tris-di-methyl-amino-boron (TMAB: B[N(CH3)2]3) gas as a low-k material. In addition, we studied the influence of the methyl group on the dielectric constant (k-value) and the properties of the Me–BCN films. It was found that the k-value of the Me–BCN films decreases with increasing number of C–H bonds due to the methyl group (CH3). The number of O–H bonds due to water incorporation is suppressed by increasing the number of C–H bonds. Consequently, we suggested that a lower k-value can be realized by the suppression of water invasion by a hydrophobic surface due to methyl bonds. Thus, the control of the methyl group is important to achieve a low-k material using Me–BCN films.