Abstracts of Magazine FUJITSU 2002-3 (VOL.53, NO.2)

Special Issue 1 : FRAM

• Trends of Fujitsu's FRAM Technology

The ferroelectric RAM (FRAM) is a non-volatile memory that uses a ferroelectric thin film and combines the advantages of ROM and RAM. Its fast write cycle, low-voltage operation, and high write endurance as well as its low power consumption make it superior to other types of non-volatile memory, for example, EEPROM and FLASH. Although many semiconductor manufacturers have developed FRAM products, Fujitsu began mass production of 0.5μm-rule, 4 K-byte FRAM as early as 1999. FRAM has mainly been applied to IC cards and FRAM-embedded micro control units (MCU). In the IC card market, there is a growing shift from single-application usage to multiple-application usage; therefore, the memory capacity must be increased. To increase the memory capacity, the cell size must always be reduced, and the design, process, and materials have been improved aggressively for this purpose. This paper describes the trends of our FRAM technology, for example, the trends in design rules, cell size, cell circuit architecture, and cell capacitor structure.

• Sensing Technology for Low-Voltage Operation FRAM

The important requirements for Smart Card LSI chips are low power consumption, nonvolatile storage, and high-speed rewrite operation to reduce processing time. A Smart Card is an IC card that contains a microcomputer, storage circuit, and RF circuit. The ferroelectric RAM (FRAM) has been developed as a nonvolatile memory that satisfies the above requirements. An FRAM embedded in an LSI must operate as a low-voltage peripheral logic IC. We have developed a new FRAM sensing scheme that can read bit-line potentials close to the GND potential. Therefore, unlike the conventional sensing scheme, in which the voltage applied to the cell is divided into a bit-line potential and cell potential, the new sensing scheme can apply a power-supply voltage or its equivalent to the cell capacitor. This scheme allows you to efficiently apply voltage to the cell capacitor, even when the power-supply voltage is low. This paper describes a low-voltage operation FRAM that employs the new sensing scheme.

• Fujitsu's Fabrication Technology for 0.5μm and 0.35μm FRAM

Fujitsu beat the world competition by being the first to ship 0.5μm and 0.35μm FRAM (in February 1999 and August 2001, respectively). The key issue regarding FRAM is how to fabricate ferroelectric capacitors consistently by using the conventional CMOS fabrication process. In this paper, we describe a reproducible PZT deposition technology, a stable PZT etching technology that uses a newly developed ICP etcher, and a dielectric interlayer technology that reduces degradation in the PZT process. We also introduce a new statistical process control system, installed in a plant in Iwate Prefecture, that is expected to achieve a high mass-production yield.

• Security Design of Smart Cards and Secure Devices with Embedded FRAM

For Smart Cards and secure devices to continuously evolve as part of a reliable societal infrastructure, it is essential to establish fundamental technologies that enable us to maintain security. To meet this need, Fujitsu has developed Smart Cards and other high-security devices that use secure ferroelectric RAM (FRAM) memory. This type of memory has an anti-tampering function and is used to keep the keys and parameters needed for encryption/decryption algorithms, modify the keys and parameters for application services, store a high-speed calculation table for encryption/decryption systems, and support a firewall between applications. This paper introduces some of our secure designs that use FRAM technology and describes the many advantages of security designs and encryption/decryption systems that incorporate FRAM memory.

• Development of FRAM-Embedded, Contactless Smart Cards

The growth of e-commerce on the Internet has brought the need for Smart Cards with higher security and multiple functions. These needs have been met by using a high-performance CPU, large-capacity memory, and encryption circuit for protecting data from illegal accesses. In the recent expansion of the Smart Card market, Contactless Smart Cards in particular have rapidly come into wide use because they are easy to use, can perform high-speed processing, and can be used in a wide variety of applications. In keeping with this trend, Fujitsu has produced various FRAM-embedded (ferroelectric-RAM-embedded) LSIs for Contactless Smart Cards.
This paper describes the advantages of using FRAM for the memory of Contactless Smart Cards and introduces our LSI products for FRAM Smart Cards.

Special Issue 2 : Printed Wiring Board

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• Fujitsu's Activities for Printed Wiring Board Technology Products

The ubiquitous (anytime, anywhere) network society consists of many core broadband products such as network systems, mobile communication systems, and high-performance servers and network terminals such as mobile equipment and home network terminals. Printed wiring boards (PWBs) are key components in these products and are therefore growing in importance as the network expands. Fujitsu promotes PWB products in three platforms to meet our customers' requirements. Also, we provide solutions that enable customers to perform processes from design to prototype manufacturing and testing within a short lead-time. Currently, we are focusing on developing leading-edge technologies and expanding advanced production systems so that organizations can share these technologies within the open market and become globally competitive. This paper introduces some of our latest PWB technology products and services and some advanced PWB production systems.

• High-Density Multi-Layer PWBs: MV (Multi-Via) Series

As the functionality and performance of broadband backbone systems such as network systems, mobile communication systems, and high-end servers progress, the demand for high-performance printed wiring boards (PWBs) that enable high-density mounting of fine-pitch and high-pin-count packages such as Ball Grid Arrays (BGAs) and Chip Size Packages (CSPs) for use in UNIX servers, optical transmission devices, and base station equipment is increasing. This paper introduces Fujitsu's MV-3 PWB technology, which combines sequential lamination and a build-up structure. Sequential lamination is used to make high-performance, multi-layer PWBs for mounting high-pin-count packages, and the build-up structure is used to make high-density PWBs for mounting packages closely together. MV-3 has a small stacked-and-buried via structure to make wiring design highly flexible. Also, it only requires two-thirds as many signal layers as a conventional board, which reduces the turn-around time and production costs. This paper also introduces MV-2, which is an MV-3 variation designed for mobile and home network applications.

• High-Density Package Substrates for System LSIs: GigaModule Series

The ever growing volume of digital data that must be handled by servers and Internet routers is strengthening the demand for high pin count packages for mounting gigahertz devices. This paper introduces the three types of GigaModule high-density packages for gigahertz devices. The first type is a flip chip interconnection with peripheral I/Os mounted on a build-up substrate. The second is a flip chip interconnection with area I/Os mounted on a build-up substrate with stacked vias. The third type is a chip mounted on a build-up substrate with stacked vias through a multi-layer thin film that acts as an integral interposer and has 5μm lines and 30μm diameter vias. The customer can select the most suitable package from this line-up according to the number of I/O pins and the required system performance.

• GigaModule-U MCM Package Substrate for Backbone Systems

This paper introduces the GigaModule-U substrate technology for high-capacity and high-reliability systems such as the GS series of global servers. The GigaModule-U is a multi-chip module (MCM) on which bare semiconductor chips are directly mounted to build high-density assemblies. Because these semiconductor chips have fine-pitch input/output terminals, a new fine-line formation technology was required to replace conventional printed wiring board technology. To meet this challenge, Fujitsu developed a new multi-layer, thin-film technology and started using it in volume production in 1995. The GigaModule-U technology provides a 5μm line width and a 7.5μm spacing, which is fine enough for mounting multiple CPU processors in a 104 × 63 mm area. This multi-layer, thin-film technology is suitable for use as a super connect technology.

• Wireless Suspensions for HDDs with GMR: GTRiM Series

Fujitsu has developed the GTRiM technology for making fine electrical traces on a thin, flexible metal strip by using polyimide, which is very stable both thermally and electrically, as an insulating material. This technology is expected to be widely used as a value-added PWB technology in the information equipment market, because the metal has superior characteristics as a mechanical spring and as a thermal radiator. In this paper, we describe two types of GTRiM technologies that have been applied in the mass production of wireless suspensions for the magnetic heads of hard disk drives. The first technology is called GTRiM-α and uses a photosensitive polyimide. The second is called GTRiM-β and was developed to meet requirements for lower cost and superior suspension functions. GTRiM-β uses a non-photosensitive polyimide and involves different processes from GTRiM-α. In this paper, we also describe the process flow charts of the two GTRiM technologies, compare their electrical characteristics, present the results of reliability tests, and look at other possible GTRiM applications.

• Total Solution Services for PWBs

Because the system development cycle is getting shorter, the prototyping process must be speeded up. For printed wiring boards (PWBs), a higher wiring density and also a reduced prototype lead-time are required. This paper introduces the assembly design, simulation, board manufacturing, and component mounting services that Fujitsu provides for the design environment. These services combine the latest in-house and commercially available CAD tools with various simulation methods. Also, we have helped customers reduce their development times by providing a wide range of quick turn-around menus for board and assembly manufacturing.

• Tool-Less PWB Manufacturing System: FJDDI

A quick lead-time for developmental/trial boards and various other boards is a dominant requirement in the printed wiring board (PWB) market. However, we are now approaching the dimensional and positional accuracy limits of the conventional technologies used to manufacture high-density, multi-layer PWBs. The Fujitsu Data Direct Imaging (FJDDI) technology is a new and attractive production system that solves this problem by directly imaging a circuit from manufacturing data with a laser. FJDDI is a core technology of tool-less PWB systems and is effective for manufacturing high-quality, high-accuracy PWBs within a quick lead-time and at low cost. This paper introduces a new DDI-based tool-less PWB system developed by Fujitsu.

• Quick Roll-to-Roll Production System: QRTR

The continuing requirements for low-cost hard disk drives with higher capacities have made the electrical trace integrated suspension (wireless suspension) a very important component and it is now required to have wider functions. In this paper, we introduce the Quick Roll-to-Roll production system (QRTR), which was developed for both the mass production and diversified small-lot production of wireless suspensions. The paper focuses on the following three aspects of this system:
(1) The manufacturing and inspection processes,
(2) the features of QRTR, for example, its system configuration, suitability in mass production, and fine patterning capability, and
(3) the introduction of key equipment for processes such as exposure, sputter, and inspection. This paper also investigates the possibilities of applying QRTR in other products.

• Quality Assurance System for Printed Wiring Boards: Q²UICK

This paper introduces the Q²UICK (pronounced"double quick") quality assurance system for printed wiring boards (PWBs). The system is based on the Q²UICK concept for performing quality activities and constructing a quality assurance system. The new system is designed to help us cope with increasing production volumes by (1) improving basic quality and (2) preventing high numbers of failures. To improve the basic quality, a team for investigating the causes of problems and evaluating the effects of countermeasures was organized and a knowledge database system was constructed to quickly obtain solutions for improving basic quality. To prevent high numbers of failures, the best way is to increase the basic quality of products by improving the manufacturing margin. With Q²UICK and an understanding of quality, which can change from moment to moment, we are building and improving the new system day by day.

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• Pen-Input Handwriting Recognition Modules

The recent popularization of the broadband Internet, cellular phones, PDAs, and e-Japan project has created the need for a new, easy-to-use, data-input technology for conveniently entering information in mobile situations. The pen-input interface, which can easily be used by beginners, is one such interface that is likely to be widely used instead of the conventional keyboard. We have developed handwriting recognition software modules as Windows Active-X controls, with which programmers can easily build high-precision handwriting online recognition into their products. These modules enable interactive handwriting recognition operations such as pen stroke display and recognition candidate selection, as well as useful operations such as word and address searches. This paper explains our new handwriting recognition technology and context processing technique. This paper also describes four software modules: general-purpose recognition module, handwritten word search module, handwritten address search module, and handwritten number (continuous digits) recognition module. We summarize the advantages and disadvantages of the pen-input interface, and discuss effective pen-input applications using these modules.