Brad C. Bittel

Defect structure and electronic properties of SiOC:H films used for back end of line dielectrics

Back end of the line dielectrics (BEOL) with low dielectric constants, so called low-k dielectrics, are needed for current and future integrated circuit technology nodes. However, an understanding of the defects which limit reliability and cause leakage currents for these films is not yet developed. We primarily utilize conventional electron paramagnetic resonance (EPR) and leakage current measurements to investigate amorphous hydrogenated carbon doped oxide (a-SiOC:H) dielectrics, the most important in current BEOL technology. The resonance measurements were complemented by transmission Fourier-transform infra-red spectroscopy, x-ray reflectivity, and Rutherford backscattering measurements. Various compositions of a-SiOC:H films were deposited on 300 mm diameter Si (100) wafers. They exhibit a wide range of dielectric constant, composition, and porosity. Variations in deposition method, process chemistry, and post deposition curing were also investigated. We observe a remarkable range of paramagnetic def...

Ultraviolet radiation effects on paramagnetic defects in low-κ dielectrics for ultralarge scale integrated circuit interconnects

The electronic properties of low-κ interlayer dielectric and etch stop layers are important issues in ultralarge scale integrated circuits development. Leakage currents are critical problems that are not well understood. A topic of current interest is ultraviolet curing of these films. We report on electron spin resonance and electrical measurements of low-κ films with and without ultraviolet exposure. This work provides fundamental understanding of the deep level defects likely involved in leakage currents.

Color center formation in vacuum sintered Nd3xY3−3xAl5O12 transparent ceramics

Color center formation was studied in vacuum sintered Nd3xY3−3xAl5O12 transparent ceramics. The primary color centers were F- and F+-centers as evidenced by optical absorption in the 250–400 nm wavelength range and the presence of an electron spin resonance (ESR) line at g=1.9977. Annealing in air at 1600 °C for 10 h reduced the number of color centers to below the detection limit of ESR. Color center formation is controlled by oxidation and reduction of Fe2+/3+ impurities.

Defects and electronic transport in hydrogenated amorphous SiC films of interest for low dielectric constant back end of the line dielectric systems

Back end of line dielectrics with low dielectric constants are needed for current and future integrated circuit technology. However, an understanding of the defects that cause leakage currents and limit reliability in these films is not yet developed. We utilize conventional electron paramagnetic resonance (EPR), electrically detected magnetic resonance (EDMR), and leakage current measurements, complimented by Fourier transform infrared spectroscopy and Rutherford back scattering results, to investigate a-SiC:H dielectrics which have great potential use for back end of line dielectrics. We observe a strong correlation between conventional EPR defect density measurements and leakage currents. There is also a very strong correlation between hydrogen content and both leakage current and EPR defect density. The close correspondence between the EPR results and the leakage currents strongly indicates that the defects observed by EPR are largely responsible for the leakage currents and likely limit the dielectri...

Spin dependent charge pumping in SiC metal-oxide-semiconductor field-effect-transistors

We demonstrate a very powerful electrically detected magnetic resonance (EDMR) technique, spin dependent charge pumping (SDCP) and apply it to 4H SiC metal-oxide-semiconductor field-effect-transistors. SDCP combines a widely used electrical characterization tool with the most powerful analytical technique for providing atomic scale structure of point defects in electronic materials. SDCP offers a large improvement in sensitivity over the previously established EDMR technique called spin dependent recombination, offering higher sensitivity and accessing a wider energy range within the bandgap.

Reliability and performance limiting defects in low-к dielectrics for use as interlayer dielectrics

Reliability issues of low-к dielectric thin films are important problems in present day ULSI development.1–6 Leakage currents in general as well as reliability issues such as time dependent dielectric breakdown (TDDM) and stress induced leakage currents (SILC) are critical problems that are not yet well understood. A topic of current interest is ultraviolet light curing (UV curing) of low-k materials.5,6 An atomic scale understanding of the defects involved in reliability problems of these films is virtually non-existent. We have initiated a study utilizing electron spin resonance (ESR) and electrical measurements which provides some fundamental understanding of the deep level defects likely involved in these reliability problems

Spin dependent charge pumping: A new tool for MOS interface characterization

We have developed a new technique, spin dependent charge (SDCP) pumping which combines the unrivaled analytical power of EPR to identify the atomic scale nature of point defects with charge pumping, a widely used electrical characterization technique used to study interface/near interface defects in MOSFETs. We demonstrate SDCP to be a very powerful tool with potential to be of widespread use to the MOSFET characterization community. We study 4H SiC and Si based MOSFETs that have SiO2 gate dielectrics with a new electrically detected magnetic resonance technique (EDMR). Our SDCP results demonstrate a tremendous improvement in sensitivity over the other EDMR techniques sensitive to interface near interface traps, spin dependent recombination (SDR). Additionally SDCP has the ability to access defects distributed over a wider energy range of the semiconductor bandgap than SDR. Charge pumping is a powerful electronic characterization technique which provides information about the electronic properties interface / near interface traps in MOSFETs. [1–3] However, charge pumping cannot provide information about the atomic scale structure of the interface trapping defects. Conventional electron paramagnetic resonance (EPR) has unrivaled analytical power to identify atomic scale structure of defect centers but cannot not provide a direct connection between defect structure and electronic properties. [4] Combining EPR and charge pumping we develop a tool, spin dependent charge pumping (SDCP), which can directly link electronic properties of defect centers and information about defect structure in a very direct way. SDR has been useful in the study of fully processed MOSFETs. [5–9] SDCP circumvents some of the limitations of SDR, and also offers a very large increase in sensitivity over conventional SDR.

Spin dependent charge pumping: A new tool for reliability studies

We have developed a new technique, spin dependent charge (SDCP) pumping which combines the unrivaled analytical power of EPR to identify the atomic scale nature of point defects with charge pumping, a widely used electrical characterization technique used to study interface/near interface defects in MOSFETs. We demonstrate SDCP to be a very powerful tool with potential to be of widespread use to the MOSFET reliability community.

Electron paramagnetic resonance studies of interlayer dielectrics

Interlayer dielectrics with low dielectric constants are needed for current and future ULSI technology nodes. [1,2] However an understanding of the defects which limit reliability and cause increased leakage currents is not yet developed for these low-k films. As reported previously [3], we have observed several performance limiting defects with electron paramagnetic resonance (EPR) that correlate quite strongly to leakage current measurements. We have recently made significant progress in developing a fundamental understanding of how film composition and processing parameters affect specific defects and how these defects are related to leakage currents. In this new work we utilize EPR and leakage current measurements to investigate over fifty low-k dielectrics with potential use as ILDs and ESLs. Films investigated include various compositions of SiOC, SiO2, SiN, SiCN, and SiC deposited deposition on 300 mm (100) silicon wafers. They exhibit a wide range of dielectric constant, sample chemistry, and density.

Defects in low-κ dielectrics and etch stop layers for use as interlayer dielectrics in ULSI

The electronic properties of thin film low-κ interlayer dielectric (ILD) and etch stop layers (ESL) are important issues in present day ULSI development.1–6 Low-κ ILD and ESLs with dielectric constants significantly less then those of SiO2 and SiN are utilized to reduce capacitance induced RC delays in ULSI circuits. However as the semiconductor industry looks to transition to 16 nm and beyond technology nodes, numerous reliability concerns with low-k materials need to be addressed. In particular, leakage currents, time dependent dielectric breakdown (TDDM) and stress induced leakage currents (SILC) are critical problems that are not yet well understood in ILD. A topic of current interest is ultraviolet light (UV curing) of low-k materials.5,6 We have made electron spin resonance (ESR) and current density versus voltage measurements on a moderately extensive set of dielectric/silicon structures involving materials of importance to low-k interconnect systems. Most of the dielectrics studied involve various compositions of SiOC:H. In addition we have also made measurements on other dielectrics including SiO2, SiCN:H and SiN:H.