Growth mechanism of hydrogenated amorphous carbon films: Molecular dynamics simulations

Stability of hydrogenated amorphous carbon thin films for application in electronic devices

“…This corroborates the relation between H and sp 2 cluster size, which impact on E T especially in thermal treatment lower than 450 º C as reported [24], [39], [40]. On the other hand, bandgap decreased at region > 450 º C, this can be attributed to changes in sp 3 Again, these results are consistent with published work [7], [23], [41].…”

“…The k values of a-C:H decreases from 2.6 for as-deposited film to 2.5 when annealed at 450 º C, this is a clear indication of the stability of films at temperatures below 450 º C, it decreases to 2.2 at higher annealing temperatures >450 º C. As a result of this, it is justifiable that a-C:H films show a transition at temperatures above 450 º C, which is in accord with other published work [11], [23]. Annealing a-C:H films at temperatures above the transition temperature (450 º C) leads to the graphitization conversion of C-C sp 3 bonded carbon to C-C sp 2 bonded carbon, and therefore leads to the release of compressive stress in the film [31]. Since the dielectric constant is proportional to stress or compactness in the film, the decreased value of k at a temperature above 450 º C results from the stress release in the films or films are becoming less compact [1], [32].…”

“…The temperature above 450 º C will lead to a damage of the structure into a mostly sp 2 bonded network [29]. As increasing hydrogen content in a-C: H deposited at low DC-bias is responsible for the increase in sp 3 fraction [3], higher annealing…”

“…temperatures > 450 º C shows an appreciable reduction in the hydrogen content that will result in the transition of sp 3 to sp 2 fraction due to loss of C-H bonds in sp 3 structures.…”

“…In recent years, hydrogenated amorphous carbon (a-C:H) films have attracted extensive attention because it endowed with a number of distinctive physical prosperities, such as high elastic modulus, extreme mechanical hardness, chemical inertness, and reduced surface roughness, thus making it a valuable unique material for a wide range of applications [1], [2], [3], [4], [5]. Of particular note are its exceptional properties including low-dielectric constant and wide optical bandgap, and these will facilitate the use of a-C:H as a semiconductor and/or low-k insulator thin film in almost all kinds of electronic applications [6], [7].…”