On Distributions of Defect States in Low-k Carbon Doped Silicon Dioxide Films in Vicinity of Fermi Level

Abstract

Spectrum of defect states N(E) in vicinity of Fermi level position in carbon-doped hydrogenated silicon dioxide ͑SiOCH͒ low-k films has been experimentally studied by deep level transient spectroscopy ͑DLTS͒ and space charge limited current ͑SCLC͒ techniques. The SiOCH films were deposited by CVD, using 3-methylsilane-oxygen mixture. Good correlation is found between features of defect spectrum obtained by DLTS and the SCLC techniques for the same SiOCH samples. In particular, N(E) peaks at 0.15-0.20 and 0.25-0.30 eV below E c have been detected by both techniques. These peaks are attributed to doubly negatively charged silicon vacancy in hexagonal or rhombohedral SiC-like phases.

An Electrical, Compositional, and Structural Study on Low-k Silsesquioxane Dielectric Thin Films

“…The XRD experiments revealed no peaks from the studied MSQ layers. Thus, the atomic structure of the MSQ films can be considered as totally amorphous, distinct from structure of previously studied hydrogenated carbon-doped silicon dioxide ͑SiOCH͒ films with similar chemical composition 11,12 ͑see the results of the infrared spectroscopy below͒. Figure 1 shows typical experimental SXR data.…”

“…Chemical compositions of amorphous and amorphous-crystalline hydrogenated siliconbased alloys ͑for example, a-Si:H, a-SiC:H, a-SiO:H, a-SiN:H, SiOCH, etc.͒ are quite close to those of the MSQ materials, and the N͑E͒ distribution in such alloys has already been studied carefully. 34,11,12 Dangling bonds of nitrogen atoms are placed at 0.1-0.3 eV below the E c in the defect spectrum of nitrogen-doped hydrogenated amorphous silicon ͑a-Si:H:N͒ films, 35 but higher than the usual position of the Fermi level, E F , in such material. As a result, each nitrogen atom, attached to silicon in the a-Si:H:N material, forms a donorlike fourfold-coordinated N 4+ defect state, and such defects are positively charged in an equilibrium state, because in this state all electron levels ͑including defect ones͒ with energies above the E F are almost empty ͑unfilled with electrons͒, Ref.…”

“…The E c -E F "distance" can be estimated through an activation energy, E a , of the "high-temperature" part of dark dc conductivity ͑or dark current I D ͒. 39,11,12 Implementation of a high-temperature part of the experimental ln͓I D ͑T −1 ͔͒ dependencies allows one to reduce the influence of so-called "statistical shift" on E a values, 39 and improves an accuracy of estimation of the E F position. The ln͓I D ͑T −1 ͔͒ dependencies have been obtained by a DL 8000 spectrometer simultaneously with the measurement of the "main" capacitance DLTS signal in the 20-315 K range ͑see Ref.…”

Electrical Breakdown in Advanced Interconnect Dielectrics

“…Because LK/ULK materials are expected to contain a significant amount of H atoms, the ID-model is well suited to these kinds of very defective dielectrics in comparison to silica gate oxide, where the H content is (or should be) much more limited. What is not explained, however, is the fact that the initial trap generation rate is so high, although low-k dielectrics are known to have a significant density of active defects [391][392][393][394][395][396]. Through his analysis of the trap generation rate through a series of elaborate trap and detrapping experiments, he notes that the rate of trap generation is highest at the beginning of the stress before even the first measurement is made.…”

Regularization Algorithm for DOS Spectrum Deconvolution From C(V) and Q(V) Dependencies of Si Nanowire-Based MOS Structure

“…Gaussian, Lorentian, exponential etc) of the N(E) distribution is known a priory, but its quantitative parameters have to be evaluated based on the appropriate IE. Obvious disadvantage of the 'modeling' approach consists in the requirement to determine N(E) shape before IE solution (12,13). The regularization approach, described in details in Ref.…”