Tadaaki Yamauchi

7.3 A 28nm embedded SG-MONOS flash macro for automotive achieving 200MHz read operation and 2.0MB/S write throughput at T i , of 170°C

Accelerated advances in automotive technology, such as sophisticated real-time engine controls for higher fuel efficiency and advanced driver-assistance systems (ADAS), are expanding the application range of Flash MCUs, microcontrollers with embedded Flash memory (eFlash). In addition to consistent demands for faster random access, shorter rewrite time and larger memory capacity in eFlash, there are increasingly intense requirements for robust operations and high data reliability under extremely high junction temperature (Ti,) of 170°C. On the other hand, along with device scaling beyond 40nm generation, the reliability of eFlash systems is constrained by not only eFlash memory cells but also peripheral transistors and metal interconnections. As oxide films in transistor devices and between metal interconnections are getting thinner, their time-dependent dielectric breakdown (TDDB) lifetime is critically degraded, which poses a great challenge in advanced eFlash design. This paper presents 28nm eFlash macros for automotive with four key features. The first feature is a 28nm split-gate (SG)-MONOS cell array with temperature-adjusted overdrive wordline (WL) voltage control to realize both 200MHz random access and more than 10× longer TDDB lifetime of WL drivers. Second, we implement a high-voltage control technique to relax electrical stress on memory cells and peripheral devices by temperature-adaptive step pulse erase control (TASPEC). Third, we achieve high write throughput of 2.0MB/s by source-side injection (SSI) programming with negative back-bias achieving 63% reduction of program pulse time. Finally, we reduce RF noise by 19dB with a spread-spectrum phase-shifted clock-generation technique for over-the-air program updates while achieving a high write throughput.

Automotive low power technology for IoT society

This paper addresses automotive low power technologies in Internet of Things (IoT) societies, where the interaction among cloud information, real-time recognition and vehicle control is a key. High reliability and high performance with low power under the harsh operating conditions are strongly demanded for automotive microcontroller units (MCUs). Our developed embedded Flash (eFlash) and SRAM achieved those required performance at up to Tj=170°C mainly for the vehicle control solution. To perform the highly robust computation in car information applications, the power management involving adaptive voltage scaling and real time power saving are adopted. Moreover other low-power schemes such as multi core CPU system with the easier parallelism and the digitally assisted ADC are introduced.

7.6 A 90nm embedded 1T-MONOS flash macro for automotive applications with 0.07mJ/8kB rewrite energy and endurance over 100M cycles under Tj of 175°C

The computerization of automotive control has expanded the application range of micro controller units (MCUs). A high-end engine-control unit (ECU) requires high-performance Flash MCUs, which integrate high-speed CMOS logic and large high-performance embedded Flash memories (eFlash) [1,2]. There are also broad markets for motor control MCUs: used to control actuators in parts such as seats, windows, and mirrors. In order to integrate analog circuits to control the high voltage (HV) drivers in these parts, those MCUs have been manufactured in Flashless process, and external EEPROM chips are being used. EEPROM chips work as “learning memories” which store the calibration data to optimize analog circuit performance in the field. Replacement of external EEPROM chips by eFlash, resulting in less additional process cost and higher rewrite endurance, is a requirement for more elaborate learning at a higher data sampling rate. In addition to automotive grade reliability under extremely harsh temperature conditions, low power consumption is also a strong requirement as the number of MCUs used in motor control systems is increasing.

Prospect of embedded non-volatile memory in the smart society

Embedded Flash (eFlash) is widely accepted by various applications because of reducing overall costs of system development, production and inventory. Continuous evolution of eFlash such as the split-gate charge-trapping memory has satisfied the most stringent quality requirement for automotive applications. Smart society for offering a better quality of life would diversify NV memory until the establishment of emerging memories. Add-on type eFlash with a few additional masks would replace the stand-alone data flash for adaptive tuning and security over the network. Towards the possible convergence of NV-memory in smart society, emerging memories such as ReRAM and STT-MRAM are progressing. Excellent features of smaller rewrite energy with the extending rewrite cycles could contribute to the outstanding energy saving such as normally-off systems.

A 20uA/MHz at 200MHz microcontroller with low power memory access scheme for small sensing nodes

Motion sensing technology has been applied in a wide range of fields of IoT. In the future, sensor device can be highly expected to be applied in the field of sports, but in order to achieve this, we need to reduce the size and weight while maintaining high performance as shown in Figure 1. It is necessary to sample a signal from the 9D sensor (3-axis gyroscope, 3-axis accelerometer and 3-axis compass) by more than 1 K/s of rate to measure the max speed (over 300km/h) for a detailed motion analysis in the sports, and necessary to provide 100-200MHz performance to CPU. Also, in order to put sensor on the body, we must reduce the size of the battery, which is largest and heaviest parts of all. When a button type battery is used for as a power source, the average current in the system will be less than 10mA during operation. In this paper, by using the following two techniques, we have successfully reduced power consumption during system operation while maintaining the high performance. Those two techniques include low-power parallel cache and cache memory with address-mapped mode. They help reduce power consumption of flash memory, memory system, and overall system respectively. By using these techniques, we have succeeded in reducing power consumption during sensing application operation at 20uA/MHz at 200MHz.

Embedded flash technology for automotive applications

Higher fuel-efficient engine and advanced driver assistance system (ADAS) require the further progress of embedded Flash (eFlash) technology for the automotive microcontroller units (MCUs). Continuous evolution of eFlash has satisfied the automotive requirements for the excellent reliability with the lower failure ratio of single ppm level and the high performance under harsh operating condition. Especially our unique spilt-gate MONOS (SG-MONOS) has been leading the worlds first most cutting-edge eFlash for automotive MCUs since 90nm process node and has been already scaled down to 28nm one, because of its excellent reliability and process scalability. In addition our gate polished structure for the low-profile SG-MONOS enables to implement high performance and power efficient high-K metal gate (HKMG) CMOS transistors, while the conventional stacked floating gate Flash can be hardly applied. As the convergence candidate of eFlash for automotive Flash MCUs, SG-MONOS can contribute to the realization of the future worlds leading green vehicles and autonomous-driving era.

Overview of Embedded Flash Memory Technology

This chapter is dedicated to comprehensively survey representative embedded flash-memory technologies from the memory-cell level to the system level. First, various types of embedded flash-memory cells are briefly overviewed in terms of cell structure, operation principle, and features in terms of characteristics and reliability . Then presented are the basic circuit-design techniques required in embedded flash hard macros under different design constraints from stand-alone flash memories. In addition, system-level design, which plays important roles for function enhancement to meet a wide range of requirements, is also covered. Finally, future prospects of eFlash-memory technologies are briefly summarized.

Technology/circuits joint evening panel discussion semiconductor industry in 2020: Evolution or revolution?

Emerging markets such as IoT, M2M, and Big Data analysis will change the game rules of semiconductor industry in 2020. What kind of business models will be required for the players? It is becoming difficult for the Integrated Device Manufacturers (IDM) to make profits simply by fabricating devices. Not only the hardware, but services or solutions becomes more and more important. On the other hand, big players begins to put great effort on the LSI design and acquire many semiconductor design houses. Will the fabless be the best style in 2020? How foundry business will change? Panelists will present their opinions on this topic and discuss what is semiconductor industry in 2020.

Session 25 overview: Non-volatile memory solutions: Memory subcommittee

Strong market demands of diverse non-volatile memory technologies show continuing increase in density, reliability, and performance. This year the leading edge process node for NAND Flash is scaled down to the minimum feature size of 16nm, and three-dimensional vertical NAND has been demonstrated. In addition, Flash controllers contribute to the higher reliability and performance on such advanced node. Emerging memories such as Resistive RAM (ReRAM) are continuing to show significant performance progress.

Robust VLSI circuit design & systems for sustainable society

In scaled VLSIs, a reliable robust circuit system is essential for the sustainable secure society. The threat to the VLSI system is caused by device, circuit or system issues. This forum provides an overview of the technical challenges as well as recent advances in circuit and system-level reliable VLSI technologies. The forum starts with the overview on the robustness and fault tolerance requirements for microcontrollers in automotive applications. The e-mobility and the new safety norm ISO 26262 affect future requirements on semiconductors. The second talk reviews recent trend of CMOS variability, followed by measured examples on static variations (process) as well as temporal variations (RTN, NBTI). Methods for variability characterization, minimization, and mitigation is also covered. The forum also has three presentations about reliable memory circuits. To enable high-density and low-power SRAMs with robust reliability and fault-tolerance, a variety of energy-efficient, variation-tolerant, and adaptive circuits are reviewed. Embedded non-volatile memory (eNVM) has greatly contributed to the recent growth of MCU market. The current eNVM technologies for highly reliable applications and future directions such as STT-MRAM and ReRAM are presented. The increase of SSD storage capacity drastically increases the total amount of circuits in memory chips inside SSDs. High relaiable SSD controller technologies such as the block device (sector unit Read/Write device) management and the error correcting code are presented. Then, the robust system design is presented. New approaches to thorough test and validation that scale with tremendous growth in complexity and cost-effective tolerance and prediction of failures in hardware during system operation are discussed. The sevnth talk overviews the reliability measures and CMOS failure mechanisms for analog circuits. Simulation techniques to predict performance degradation or device failure is also presented. This forum also highlights the channel coding system which is essential for information transmission and storage. Complex systems for wireless communications require elaborate techniques like iterative (turbo) decoding or advanced algebraic code constructions and decoding algorithms. Finally, the robust energy management is presented for sensor systems and data servers. As a component of energy management, voltage regulators are providing utility beyond power conversion. How voltage regulators play an import role in energy efficient conversion as well as providing information that will help systems manage themselves for maximum utility is discussed.