Investigation of stress and adhesion of cubic boron nitride films

Deposition of thick cubic boron nitride films — Mechanisms and concepts

“…2), where the ion bombardment is strong enough to destroy the growing film completely. On the other hand it has been shown that bombardment by low energy ions not only generates defects but can also lead to stress relaxation during the thermal spikes caused by the ion impact [33,39]. Reinke et al [33] have shown that from a balance of defect generation and defect relaxation, the stress can be related to the ion energy by…”

“…It is, however, of utmost importance to state that the sp 2 bonded nucleation layer cannot be avoided in practical cases, and that it forms a weak point with respect to the mechanical properties of the entire system [33]. Even if complex, BN-based underlayers as discussed below in Section 4.2 are used, the nucleation layer is formed prior to the nucleation of c-BN [15,16,34].…”

Review of advances in cubic boron nitride film synthesis

“…whether the thermodynamic boundary in the BN system will mimic that of carbon is uncertain. Furthermore, Cardinale et al [229] and Reinke et al [230] have shown that if cBN and hBN have the same ion-induced strain, cBN will have a much higher stress because of its higher elastic modulus. That is, since the effective modulus of the film increases with increasing cBN content, the stress will necessarily increase.…”

“…Usually in these models, however, the spikes are postulated to lzivlder cBN formation, either by relaxing stress or relaxing subsurface density increases through enhanced atomic mobility. The ion bombardment that is critical to cBN synthesis also generates significant compressive stresses in the films [229,230]. In 199 1, McKenzie et al [ 1 I] suggested that cBN forms because the ion-induced stress places the BN material in the cBN-stable region ofthe thermodynamic phase diagram (see Fig.…”

“…Ion irradiation of the polycrystalline cBN produces strain-generating defects. which in turn produce significant residual compressive stress because of the extremely high elastic modulus of the cBN [229,230]. This residual stress, combined with environmental factors.…”