International Technology Roadmap for Semiconductors 2003の要求清浄度について － シリコンウエハ表面と雰囲気環境に要求される清浄度, 分析方法の現状について －

Different physics-based negative bias temperature instability (NBTI) models as proposed in the literature are reviewed, and the predictive capability of these models is benchmarked against experimental data. Models that focus exclusively on hole trapping in gate-insulator-process-related preexisting traps are found to be inconsistent with direct experimental evidence of interface trap generation. Models that focus exclusively on interface trap generation are incapable of predicting ultrafast measurement data. Models that assume strong correlation between interface trap generation and hole trapping in switching hole traps cannot simultaneously predict long-time dc stress, recovery, and ac stress and cannot estimate gate insulator process impact. Uncorrelated contributions from generation and recovery of interface traps, together with hole trapping and detrapping in preexisting and newly generated bulk insulator traps, are invoked to comprehensively predict dc stress and recovery, ac duty cycle and frequency, and gate insulator process impact of NBTI. The reaction-diffusion model can accurately predict generation and recovery of interface traps for different devices and experimental conditions. Hole trapping/detrapping is modeled using a two-level energy well model.

A Comparative Study of Different Physics-Based NBTI Models

Tropical Forest Insect Pests, first published in 2007, promotes a better theoretical understanding of pest population dynamics, and causes of forest insect outbreaks in the tropics. Covering pests of both natural forests and plantations, it examines the diversity of tropical forest insects; their ecological functions; the concept of pests; and the incidence of pests in natural forests, plantations, and stored timber. General issues on which foresters and forest entomologists hold strong traditional views, such as the severity of pest incidence in plantations vs. natural forests, in plantations of exotics vs. indigenous tree species, and in monocultures vs. mixed plantations are discussed. The final section looks in detail at specific insect pests of the common plantation tree species across the tropics, with recommendations for their control. This is a comprehensive resource suitable for graduate students and researchers in forestry and tropical forest entomology, and for forest plantation managers in the tropics.

Tropical Forest Insect Pests: Ecology, Impact, and Management

Comphy — A compact-physics framework for unified modeling of BTI

A common framework of trap generation and trapping is used to explain Negative Bias Temperature Instability (NBTI) and Positive Bias Temperature Instability (PBTI) DC and AC stress/recovery data. NBTI is explained using trap generation in Si/SiON (IL) interface and SiON (IL) bulk, together with hole trapping in pre-existing bulk SiON (IL) traps. Interface trap generation and recovery can be fully explained using Reaction-Diffusion (RD) model. PBTI is explained using trap generation in SiON (IL)/HK interface and HK bulk, together with electron trapping in pre-existing bulk HK traps. Important similarities as well as differences between N and P BTI are highlighted.

A consistent physical framework for N and P BTI in HKMG MOSFETs

Reaction-Diffusion (R-D) framework for interface trap generation along with hole trapping in pre-existing and generated bulk oxide traps are used to model Negative Bias Temperature Instability (NBTI) in differently processed SiON p-MOSFETs. Time, temperature and bias dependent degradation and recovery transients are predicted. Long-time power law exponent of DC degradation and uniquely renormalized duty cycle and frequency dependent AC degradation data from a wide range of sources are shown to have universal features and a broad consensus across industry/academia. These universal features can also be predicted using the classical R-D framework.

A critical re-evaluation of the usefulness of R-D framework in predicting NBTI stress and recovery

NBTI and PBTI are studied in IL/HK/MG gate stacks having EOT down to ~ 6A and fabricated using low T RTP based thermal IL and a novel IL/HK integration. At equivalent EOT, proposed stacks provide improved NBTI and similar PBTI when compared to conventional Chem-Ox IL based HKMG stacks. EOT scaling achieved by RTP thermal IL scaling shows lower rate of increase in NBTI and PBTI when compared to Chem-Ox IL scavenged stacks. Impact of Nitrogen and role of post HK nitridation are studied. Physical mechanism of improved BTI in proposed stacks is discussed in detail.

HKMG process impact on N, P BTI: Role of thermal IL scaling, IL/HK integration and post HK nitridation

A comprehensive NBTI framework using the H/H2 RD model for interface traps and 2 well model for hole traps has been proposed and used to predict DC and AC experiments. The framework is validated against experimental data from different DC stress and recovery conditions, AC frequency and duty cycle, measurement speed, and across SiON and HKMG devices having different gate insulator processes. Limitations of the alternative 2 stage model framework is discussed.

K. Joshi

Papers

A Comparative Study of Different Physics-Based NBTI Models

A critical re-evaluation of the usefulness of R-D framework in predicting NBTI stress and recovery

A consistent physical framework for N and P BTI in HKMG MOSFETs

HKMG process impact on N, P BTI: Role of thermal IL scaling, IL/HK integration and post HK nitridation

A comprehensive AC / DC NBTI model: Stress, recovery, frequency, duty cycle and process dependence