Diamondlike Carbon Materials as Low-k Dielectrics for Multilevel Interconnects in Ulsi

Abstract

A variety of diamondlike carbon (DLC) materials were investigated for their potential applications as low-k dielectrics for the back end of the line (BEOL) interconnect structures in ULSI circuits. Hydrogenated DLC and fluorine containing DLC (FDLC) were studied as a low-k interlevel and intralevel dielectrics (ILD), while silicon containing DLC (SiDLC) was studied as a potential low-k etch stop material between adjacent DLC based ILD layers, which can be patterned by oxygen-based plasma etchingIt was found that the dielectric constant (k) of the DLC films can be varied between >3.3 and 2.7 by changing the deposition conditions. The thermal stability of these DLC films was found to be correlated to the values of the dielectric constant, decreasing with decreasing k. While DLC films having dielectric constants k>3.3 appeared to be stable to anneals of 4 hours at 400 °C in He, a film having a dielectric constant of 2.7 was not, losing more than half of its thickness upon exposure to the same anneal. The stresses in the DLC films were found to decrease with decreasing dielectric constant, from 700 MPa to about 250 MPa. FDLC films characterized by a dielectric constant of about 2.8 were found to have similar thermal stability as DLC films with k >3.3. The thermally stable FDLC films have internal stresses <300 MPa and are thus promising candidates as a low-k ILD.For the range of Si contents examined (0-9% C replacement by Si), SiDLC films with a Si content of around 5% appear to provide an effective etch-stop for oxygen RIE of DLC or FDLC films, while retaining desirable electrical characteristics. These films showed a steady state DLC/SiDLC etch rate ratio of about 17, and a dielectric constant only about 30% higher than the 3.3 of DLC.

Conditions for forming composite carbon nanotube-diamond like carbon material that retain the good properties of both materials

“…There are some experimental techniques for characterization of DLC, for example, Fourier transform infrared spectroscopy (FTIR), high resolution nuclear magnetic resolution (NMR), electron energy loss spectroscopy (EELS), X-Ray Photoelectron Spectroscopy (XPS), Auger spectroscopy, etc. It also has been reported that by either thermal activation 17,18 or low energetic ion irradiations, 19 the structure of the metastable DLC materials will convert some sp 3 bonds to sp 2 bonds towards graphite-like carbon. 11 Thus a fundamental understanding of carbon hybridization under low energetic carbon atom bombardments is of great interest.…”

Low and Ultralow Dielectric Constant Films Prepared by Plasma‐enhanced Chemical Vapor Deposition

“…In 1997 we reported for the fi rst time low-k DLC fi lms stable up to 400°C [25] and FDLC fi lms with k = 2.3 have been reported elsewhere [27].…”

“…Low-k DLC fi lms have been prepared by RF PECVD in a parallel plate reactor, at pressures of 100-300 mTorr and RF powers of 25-100 W, corresponding to power densities of 0.08-0.31 W/cm 2 , as described in detail elsewhere [25,26]. The RF plasma was sustained with a RF power supply at a frequency of 13.56 MHz.…”

“…FDLC fi lms, generally characterized by lower dielectric constants then DLC, have been deposited from fl uorocarbons, mixtures of fl uorocarbons with hydrogen, or mixtures of fl uorocarbons with hydrocarbons, using parallel plate RF PECVD reactors [26,27] or highdensity plasma reactors [28,29]. Contrary to DLC, low-k FDLC fi lms can be deposited at temperatures up to 400°C and on either electrode of the parallel plate reactor.…”

Electric field and temperature-induced removal of moisture in nanoporous organosilicate films

“…Although many low-k materials in the range of 2.0-4.0 [1][2][3][4][5] have been studied, integration problems and issues like moisture adsorption brought numerous reliability concerns. Methylsilsesquixane ͑MSQ͒ is an attractive candidate for replacement of SiO 2 in future generation ICs because of its inherent low-k ͑2.8͒ and good thermal stability.…”