Mass and bond density measurements for PECVD a-SiCx:H thin films using Fourier transform-infrared spectroscopy

Atomic layer deposited (ALD) high-dielectric-constant (high-k) materials have found extensive applications in a variety of electronic, optical, optoelectronic, and photovoltaic devices. While electrical, optical, and interfacial properties have been the primary consideration for such devices, thermal and mechanical properties are becoming an additional key consideration for many new and emerging applications of ALD high-k materials in electromechanical, energy storage, and organic light emitting diode devices. Unfortunately, a clear correspondence between thermal/mechanical and electrical/optical properties in ALD high-k materials has yet to be established, and a detailed comparison to conventional silicon-based dielectrics to facilitate optimal material selection is also lacking. In this regard, we have conducted a comprehensive investigation and review of the thermal, mechanical, electrical, optical, and structural properties for a series of prevalent and emerging ALD high-k materials including aluminum oxide (Al 2 O 3 ), aluminum nitride (AlN), hafnium oxide (HfO 2 ), and beryllium oxide (BeO). For comparison, more established silicon-based dielectrics were also examined, including thermally grown silicon dioxide (SiO 2 ) and plasma-enhanced chemically vapor deposited hydrogenated silicon nitride (SiN:H). We find that in addition to exhibiting high values of dielectric permittivity and electrical resistance that exceed those of SiO 2 and SiN:H, the ALD high-k materials exhibit equally exceptional thermal and mechanical properties with coefficients of thermal expansion ≤ 6 × 10 -6 / • C, thermal conductivites (κ) of 3-15 W/m K, and Young's modulus and hardness values exceeding 200 and 25 GPa, respectively. In many cases, the observed extreme thermal/mechanical properties correlate with the presence of crystallinity in the ALD high-k films. In contrast, some of the electrical and optical properties correlate more strongly with the percentage of ionic vs. covalent bonds present in the high-k film. Overall, the ALD high-k dielectrics investigated concurrently exhibit compelling thermal/mechanical and electrical/optical properties. The drive to reduce gate leakage currents in highly scaled complementary metal-oxide-semiconductor (CMOS) transistors has led to the exploration and development of a wide variety of high-dielectricconstant (high-k) materials to replace silicon dioxide (SiO 2 ) as the insulating gate dielectric material.1-8 Many of these same high-k materials have found additional applications in future non-CMOS logic and memory storage products such as solid-state electrolytes in resistive switching devices, 9,10 tunnel barriers in spin-transport devices, 11 and as a ferroelectric in magnetoelectric devices. While electrical, physical, and thermodynamic properties have clearly been a key consideration in all of the above applications, thermal properties have become an additional important consideration for higk-k dielectrics as aggressive dimensional scaling of devices has created the need to dissipate ...

Section: Methodsmentioning

confidence: 99%

Review—Investigation and Review of the Thermal, Mechanical, Electrical, Optical, and Structural Properties of Atomic Layer Deposited High-kDielectrics: Beryllium Oxide, Aluminum Oxide, Hafnium Oxide, and Aluminum Nitride

Gaskins

Hopkins

Merrill

et al. 2017

“…307,308 Based on the above SCC model, an additional desired requirement for a DB material would be immunity to SCC. Although a few studies have shown that a-SiC:H and related DB materials can react with ambient H 2 O, [309][310][311] the DCB studies of Matsuda have shown that the fracture energy of a-SiC:H and a-SiCN:H DB materials are insensitive to moisture in humidity levels ranging from 20 to 70%. 168,169 However, the fracture energy for a-SiCO:H DB materials were shown to be sensitive to moisture with the level of sensitivity being dependent on the concentration of Si-O-Si network bonding present in the material.…”

Section: Ecs Journal Of Solid State Science and Technology 4 (1) N30mentioning

confidence: 99%

“…Reductions in dielectric constant are primarily achieved via intentionally introducing controlled levels of nanoporosity through the incorporation of terminal hydrogen or organic groups during film deposition. 310,311 These terminal groups disrupt the SiC, Si 3 N 4 or SiO 2 network structure resulting in a material with increased free volume (and/or porosity). 66 The effective k of the material is then the volume average of the k for the free volume (k = 1) and that for the matrix.…”

Section: Current Status Of Low-k Db/ccl/es Materials and R And Dmentioning

confidence: 99%

Dielectric Barrier, Etch Stop, and Metal Capping Materials for State of the Art and beyond Metal Interconnects

King

2014

131

115

Over the past decade, the primary focus for improving the performance of nano-electronic metal interconnect structures has been to reduce the impact of resistance-capacitance (RC) delays via utilizing insulating dielectrics with ever lower values of dielectric permittivity. The integration and implementation of such low dielectric constant (i.e. low-k) materials has been fraught with numerous challenges. For intermetal and interlayer (ILD) low-k dielectrics, these challenges have been largely associated to integration with metal interconnect fabrication processes and well documented and reviewed in the literature. Although equally important, less attention has been given to other low-k dielectrics utilized in metal interconnect structures that are commonly referred to as low-k dielectric barriers (DB), etch stops (ES), and/or Cu capping layers (CCL). These materials present numerous challenges as well for integration into metal interconnect fabrication processes. However, they also have more stringent integrated functionality requirements relative to low-k ILD materials that serve only a basic purpose of electrically isolating adjacent metal lines. In this article, we review the integration challenges and associated integrated functionality requirements for low-k DB/ES/CCL materials with a focus on the current status and future direction needed for these materials to facilitate both Moore's law (i.e. More Moore) and More than Moore scaling.

“…low-k) SiOC:H, SiCN:H, and SiC:H materials where the k is less than that of SiO 2 and SiN:H respectively. [9][10][11][12][13][14][15][16] Low-k materials are of significant importance to the nanoelectronics industry as a means to reduce parasitic capacitances, power loss, and signal delays in both transistor and interconnect structures. [17][18][19] However, low-k materials typically suffer from reduced electrical, mechanical and thermal properties.…”

mentioning

confidence: 99%

“…12 Unfortunately, most FTIR investigations of low-k and other related materials have been qualitative [10][11][12][13][14][15][16] in nature while only a few have been quantitative. 15,25 In the following study, the author's demonstrate that many of the challenges to performing quantitative FTIR measurements of low-k (and other) materials can be overcome via the combination of proper removal of optical thin film interference effects and multivariate partial least squares (PLS) analysis of the interference free IR spectra.…”

mentioning

confidence: 99%

Complete Elemental Analysis of Low-ka-SiC:H Thin Films by Transmission FTIR Spectroscopy

Milošević¹,

King

2014

Fourier transform infrared (FTIR) spectroscopy is a popular technique for qualitatively investigating the chemical bonding of low dielectric constant (low-k) materials utilized in nanoelectronic Cu interconnects. However, quantitative FTIR analysis of low-k materials with widely varying stoichiometry has proven challenging due to numerous optical interference effects, variations in IR absorption strength with optical constants, and a negligible IR activity for homopolar bonds. In this paper, these challenges are overcome to demonstrate full elemental composition analysis by applying multivariate partial least squares (PLS) modeling to the true IR absorbance spectra obtained using previously described methods for eliminating optical interference effects from thin film FTIR spectra. To demonstrate the validity of this approach, transmission FTIR spectra were collected from a series of low-k a-SiC:H thin films with hydrogen content ranging from 25-60%. The elemental concentrations determined from PLS analysis of the corrected low-k a-SiC:H FTIR spectra were found to be in agreement to within ±5% of results obtained from independent nuclear reaction analysis and Rutherford backscattering measurements. These results demonstrate a clear path for establishing transmission FTIR as a quantitative metrology for full compositional analysis (elemental and chemical bond) for a wide range of thin film materials.