Oscar Bravo | UNAM Universidad Nacional Autónoma de México (original) (raw)
Papers by Oscar Bravo
American Journal of Medical Genetics Part B-neuropsychiatric Genetics, 2009
Panic disorder (PD) is a debilitating anxiety disorder, characterized by recurrent episodes of in... more Panic disorder (PD) is a debilitating anxiety disorder, characterized by recurrent episodes of intense fear that are accompanied by autonomic and psychological symptoms leading to behavioral impairment. Basic research implicates neuropeptide-signaling genes in the modulation of anxiety and stress. The genes encoding corticotropin releasing hormone receptor 1 (CRHR1), tachykinin receptor 1 (TACR1), gastrin releasing peptide (GRP), and gastrin releasing peptide receptor (GRPR) were selected as candidates for PD based on their biology. Linkage and association analysis in 120 multiplex U.S. PD pedigrees was performed using 21 single nucleotide polymorphisms (SNPs). Parametric and non-parametric linkage tests in pedigrees, for single point and multipoint analysis, revealed limited support for genetic linkage to TACR1 (parametric and non-parametric lod scores ∼1). The family-based association test (FBAT) generated nominal support for allelic association in TACR1 (P = 0.02), and GRP (P = 0.02), findings which must be considered in the light of multiple comparisons. Further exploration of the GRP and TACR1 findings in large case-control PD samples may provide more definitive evidence implicating these loci in the genetic etiology of PD. © 2008 Wiley-Liss, Inc.
The study of low-k TDDB line space scaling is important for assuring robust reliability for new t... more The study of low-k TDDB line space scaling is important for assuring robust reliability for new technologies. Although spacing effects due to line edge roughness (LER) on low-k TDDB lifetime were reported previously (Chen et al., 2007; Lloyd et al., 2007; Kim et al., 2007), there has been a lack of an analytical model with which to link line edge roughness to experimental TDDB data in a simple quantitative format. This work reports a thorough investigation into the low-k SiCOH line LER effect on low-k TDDB covering both experimental results and finite element modeling (FEM) simulations. The maximum electric field intensity as a result of sidewall LER bump was found to depend on the bump curvature. The decrease of low-k line spacing that resulted in a shorter TDDB lifetime even under the same applied electric field was then carefully analyzed. A simple analytical model of the effect of line edge roughness on TDDB failure time reduction is presented. This model was verified by experimental results. Additionally, a method to electrically quantify an overall line edge roughness is introduced.
In this paper, a correlation between the I-V slope at low fields and TDDB voltage acceleration is... more In this paper, a correlation between the I-V slope at low fields and TDDB voltage acceleration is demonstrated for the first time, based on a wide range of data from 32 nm to 130 nm node hardware. The data supports the radicE model, which is based on electron fluence (leakage current) driven, Cu catalyzed, low-k dielectric breakdown. Using this correlation, a fast wafer level screen method was also implemented for process improvement and TDDB reliability monitoring.
Microelectronics Reliability, 2008
a b s t r a c t 14
In the course of Cu/low-k technology development and qualification, low-k time-dependent dielectr... more In the course of Cu/low-k technology development and qualification, low-k time-dependent dielectric breakdown (TDDB) is rapidly becoming one of the most important reliability issues. In order to accurately predict low-k TDDB reliability, it is crucial to clarify the electric field dependence and temperature dependence of time-to-breakdown. In this study, bias-temperature stresses of CVD low-k SiCOH dielectric at the 65nm technology node were conducted over a wide range of fields and temperatures. Based on the extensive long-term test results (longer than one year), it was found that the "square-root of E" (radicE) dependence seems to be the best choice for modeling field dependent TDDB data. It was also determined that the TDDB activation energy is dependent on electric field, and that the field acceleration parameter for the radicE model decreases with increasing temperature. The physical mechanism behind radicE and the role of Cu diffusion during bias-temperature-stress are discussed, and an electron-fluence-driven, Cu-catalyzed SiCOH breakdown model is introduced. Finally, it is emphasized that great care must be taken in evaluating low-k dielectric TDDB when different stress fields and temperatures are used for chip operational lifetime projections
American Journal of Medical Genetics Part B-neuropsychiatric Genetics, 2009
Panic disorder (PD) is a debilitating anxiety disorder, characterized by recurrent episodes of in... more Panic disorder (PD) is a debilitating anxiety disorder, characterized by recurrent episodes of intense fear that are accompanied by autonomic and psychological symptoms leading to behavioral impairment. Basic research implicates neuropeptide-signaling genes in the modulation of anxiety and stress. The genes encoding corticotropin releasing hormone receptor 1 (CRHR1), tachykinin receptor 1 (TACR1), gastrin releasing peptide (GRP), and gastrin releasing peptide receptor (GRPR) were selected as candidates for PD based on their biology. Linkage and association analysis in 120 multiplex U.S. PD pedigrees was performed using 21 single nucleotide polymorphisms (SNPs). Parametric and non-parametric linkage tests in pedigrees, for single point and multipoint analysis, revealed limited support for genetic linkage to TACR1 (parametric and non-parametric lod scores ∼1). The family-based association test (FBAT) generated nominal support for allelic association in TACR1 (P = 0.02), and GRP (P = 0.02), findings which must be considered in the light of multiple comparisons. Further exploration of the GRP and TACR1 findings in large case-control PD samples may provide more definitive evidence implicating these loci in the genetic etiology of PD. © 2008 Wiley-Liss, Inc.
The study of low-k TDDB line space scaling is important for assuring robust reliability for new t... more The study of low-k TDDB line space scaling is important for assuring robust reliability for new technologies. Although spacing effects due to line edge roughness (LER) on low-k TDDB lifetime were reported previously (Chen et al., 2007; Lloyd et al., 2007; Kim et al., 2007), there has been a lack of an analytical model with which to link line edge roughness to experimental TDDB data in a simple quantitative format. This work reports a thorough investigation into the low-k SiCOH line LER effect on low-k TDDB covering both experimental results and finite element modeling (FEM) simulations. The maximum electric field intensity as a result of sidewall LER bump was found to depend on the bump curvature. The decrease of low-k line spacing that resulted in a shorter TDDB lifetime even under the same applied electric field was then carefully analyzed. A simple analytical model of the effect of line edge roughness on TDDB failure time reduction is presented. This model was verified by experimental results. Additionally, a method to electrically quantify an overall line edge roughness is introduced.
In this paper, a correlation between the I-V slope at low fields and TDDB voltage acceleration is... more In this paper, a correlation between the I-V slope at low fields and TDDB voltage acceleration is demonstrated for the first time, based on a wide range of data from 32 nm to 130 nm node hardware. The data supports the radicE model, which is based on electron fluence (leakage current) driven, Cu catalyzed, low-k dielectric breakdown. Using this correlation, a fast wafer level screen method was also implemented for process improvement and TDDB reliability monitoring.
Microelectronics Reliability, 2008
a b s t r a c t 14
In the course of Cu/low-k technology development and qualification, low-k time-dependent dielectr... more In the course of Cu/low-k technology development and qualification, low-k time-dependent dielectric breakdown (TDDB) is rapidly becoming one of the most important reliability issues. In order to accurately predict low-k TDDB reliability, it is crucial to clarify the electric field dependence and temperature dependence of time-to-breakdown. In this study, bias-temperature stresses of CVD low-k SiCOH dielectric at the 65nm technology node were conducted over a wide range of fields and temperatures. Based on the extensive long-term test results (longer than one year), it was found that the "square-root of E" (radicE) dependence seems to be the best choice for modeling field dependent TDDB data. It was also determined that the TDDB activation energy is dependent on electric field, and that the field acceleration parameter for the radicE model decreases with increasing temperature. The physical mechanism behind radicE and the role of Cu diffusion during bias-temperature-stress are discussed, and an electron-fluence-driven, Cu-catalyzed SiCOH breakdown model is introduced. Finally, it is emphasized that great care must be taken in evaluating low-k dielectric TDDB when different stress fields and temperatures are used for chip operational lifetime projections