X-ray photoelectron spectroscopy measurement of the Schottky barrier at the SiC(N)/Cu interface

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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

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“…[239][240][241][242] For low-k DB materials, there has been some concern regarding what UV curing will do the material properties of the DB given the smaller band-gap and larger absorption coefficient in the UV-VUV spectrum for these materials. 50,243 While exhaustive studies have not been reported, several studies of PECVD a-SiN:H have shown that UV curing leads to hydrogen loss, densification and a decrease in compressive stress (or increase in tensile stress). [244][245][246] Additional studies have shown that UV curing can also result in an increase in paramagnetic defect densities and leakage currents.…”

Section: -122mentioning

confidence: 99%

“…This can be a challenging and conflicting requirement for a-SiN:H and aSiCN:H DB materials that are typically deposited using NH 3 and/or silazane precursors and can contain significant amounts of residual amines after deposition. [41][42][43][44][45][46][47][48][49][50][51] The no amines requirement can also be a challenge for a-SiC:H and a-SiCO:H DB materials that do not incorporate nitrogen in the deposition process, but that may utilize an NH 3 plasma pre-treatment to improve adhesion of the DB to the underlying Cu and low-k ILD surfaces.…”

Section: 318mentioning

confidence: 99%

“…Therefore, low-k forms of these materials were also needed to reduce the impact of the relatively high-k of PECVD a-SiN:H (k = 6.5-7.0). [41][42][43] The low-k DB/CCL/ES materials implemented to date have been primarily carbon doped silicon nitrides (a-SiNC:H) with k values of 4.5-5.8, [44][45][46][47][48][49][50][51] dense oxygen doped silicon carbides (a-SiCO:H) with k values of 4.0-4.8, [52][53][54][55][56][57][58] and pure silicon carbides (a-SiC:H) with k values of 4.0-7.0. [59][60][61][62][63][64][65][66] Similar to low-k ILDs, these materials have proven equally difficult and challenging to integrate with Cu interconnect fabrication processes.…”

mentioning

confidence: 99%

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

King

2014

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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.

“…The XPS measurements were performed after ex-situ transfer to a VG Theta 300 XPS system having a hemispherical analyzer and a monochromated Al anode X-ray source (1486.6 eV). 34 Removal of ex-situ surface contamination and depth profiling was achieved using a 2 keV Ar + ion sputtering beam. A pass energy of 20 eV was utilized for collecting high resolution scans of the B1s, N1s, C1s, and O1s core levels as the Ar + beam sputtered through a portion of the film.…”

Section: N3123mentioning

confidence: 99%

Investigation of the Dielectric and Mechanical Properties for Magnetron Sputtered BCN Thin Films

Prakash

Todi

Sundaram

et al. 2014

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Boron carbon nitride (BCN) thin films were deposited by a dual target DC and RF sputtering technique. The films were deposited using various combinations of nitrogen and argon working gases and B 4 C, BN, and C targets. X-ray photoelectron spectroscopy and Fourier-transform infra-red spectroscopy were utilized, respectively, to investigate the changes in chemical composition and bonding that occurred for films deposited under various N 2 /Ar gas flow ratios and DC/RF target powers. The composition and bonding were correlated to separate measurements of the BCN mass density, dielectric constant, Young's modulus, and hardness. All BCN films were observed to have relatively low mass densities ranging from 2.0-2.5 g/cm 3 . BN rich BCN films were observed to be insulating with relatively low dielectric constants of 3.9-4.6 and Young's modulus and hardness values of 110-150 GPa and 5-13 GPa, respectively. BC rich BCN films were observed to be comparatively leaky dielectrics but did exhibit extreme mechanical properties with Young's modulus and hardness values exceeding in some cases 300 GPa and 30 GPa, respectively. Nanoelectronic metal interconnects have many unique nanoscale electrical, thermal, and mechanical challenges.1-3 While dimensional scaling has produced tremendous improvements in transistor performance, 4 it has produced an opposite effect on the associated metal interconnect leading to increased critical path signal delays and possible degradation of the overall integrated circuit performance.5 As the interconnect signal delays are proportional both to the resistance of the interconnect metal and the capacitance of the insulating interlayer dielectric (ILD), new materials with reduced values of resistivity and dielectric permittivity have been sought to mitigate the negative effects of dimensional scaling.5 Since relatively few materials exhibit a lower resistivity compared to the currently utilized interconnect metal copper (Cu), most materials based interconnect delay reduction efforts have focused on implementing new ILD materials with increasingly lower values of dielectric constant (i.e. low-k).6 Unfortunately, the hybrid inorganic-organic silicate (a-SiOC:H) materials currently utilized as low-k ILDs exhibit reduced electrical, thermal and mechanical properties in addition to reduced values of dielectric permittivity.5-7 These overall reduced properties have severely aggravated a variety of interconnect related reliability issues such as time dependent dielectric breakdown and die cracking during packaging. 2,3Compounds in the boron-carbon-nitrogen phase diagram (such as diamond (C), cubic boron nitride (c-BN), and boron carbide (B 4 C)) are potentially attractive as alternative low-k dielectric materials due to their covalent bonding, short bond lengths, and low atomic mass that leads to a unique combination of low dielectric constant but high thermal and mechanical strength. [8][9][10][11][12] Some of the already prominently reported properties for these materials include good wear resistance, hig...