Kazunori Saitoh

Submicron pattern fabrication by focused ion beams

A focused ion beam (FIB) technology has many advantages for submicron structure fabrication and other maskless processes. In order to develop 4–16 M(D) RAM, the FIB technology is strongly desired for its capability of submicron lithography without proximity effects.

Practical results of photomask repair using focused ion beam technology

Practical results of photomask defect repair using focused ion beam (FIB) technology are presented. From Auger electron analysis, the deposited carbon film for clear defect repair contains 22% gallium, which is an element of the ion beam. Substrate damage produced by ion beam irradiation can be removed incorporating CHF3+O2 reactive ion etching. Printing results using a 5:1 stepper show that the FIB technology can be applied to photomask production.

Unique resist profiles with Be and Si focused ion beam lithography

The delineation of resist patterns has been investigated for two kinds of ions, Be and Si. Patterns consisting of 0.2 μm lines and spaces were fabricated in 0.7 μm thick resist with good repeatability and accuracy. This shows that the influence of proximity effects can be disregarded. The broadening of patterns was observed for Si exposure because of the more significant influence of recoil atoms. As a special application of focused ion beam lithography, a new process for fabricating a mushroom gate electrode for a GaAs microwave field‐effect transistor (FET) was demonstrated utilizing the particular exposure characteristics of the different ion species.

Electron beam pattern inspection system using digital image processing

An electron beam pattern inspection system (EBIS) using digital image processing is presented. A pattern‐to‐data comparison method is used in this system to detect systematic, random and repeating defects of VLSI circuit patterns. The inspection data are generated from the design data, and transferred from a computer aided design (CAD) system via a computer network. In order to obtain the information of mask or wafer patterns, a low‐energy scanning electron microscope, which has the advantage of avoiding damage to the active devices and not charging the surface, is used. Frame memories are installed to store the inspection data and the actual pattern image. An extra image processor preprocesses the pattern image to obtain high signal‐to‐noise ratio and manipulates these images to extract defects. Two algorithms extracting the defects are studied. Spatial differentiation followed by a thresholding operation is a suitable procedure for the signal with drift.

MR3210 Based on ITRON2 Specification Realtime OS

M32 (GMICRO) series microprocessors, such as M32/100, M32/200 and M32/300, will be the first commercial 32bit microprocessors based on the TRON specification MPU. MR3210 is a realtime operating system (OS) for these microprocessors based on the ITRON2 specification. The MR3210 makes up a series of realtime OS’s with MR3200, which is based on the micro-ITRON specification. Comparing the MR3210 with the MR3200, the MR3210 has better functionality and reliability with some overhead of the code size and the execution time. The MR3210 has a file system called MR3210F, which is based on the ITRON/FILE specification. The ITRON/FILE specification is a subset of the BTRON specification file system.

Electron‐beam inspection technology for x‐ray masks

An electron‐beam inspection system with a capability of detecting quarter‐micron defects has been developed and is applied to the inspection of the x‐ray mask itself. The accuracy of this system is measured and discussed. The distortion of the electron‐beam deflection is 0.08 μm (root‐mean‐square error) within 70×90 μm area in the scan field of 100 μm2. A sample x‐ray mask has Au absorption patterns with the thickness of 0.8 μm on a 2.0‐μm‐thick SiN membrane. An accelerating voltage of 3 kV was found to give a stable signal with a minimum of charging effects. The inspection is performed by means of die‐to‐die comparison scheme. Detection of 0.3 μm defects was demonstrated, indicating the potential of electron‐beam technology for x‐ray mask inspection.

The Evaluation of M32/100’s Bitmap Instructions Used in the Graphic Primitive

Bitmap instructions of the M32/100, a 32-bit microprocessor based on the TRON architecture specification, are designed for bitmap display control. This paper describes their performance evaluation of the bitmap instructions when applied to the Graphic Primitive, which is graphic application software used in the BTRON specification operating system. The bitmap instructions can paint rectangles with a pattern 1.5–2 times faster and move windows 2.7–3.3 times faster than move instructions looped by software on a color display with 8 bits per pixel.

Technologies for electron beam direct writing

Abstract Development time of semiconductor devices which have a large volume of pattern data and fine feature size can be remarkably reduced by a high speed on-line system and an erase electron beam direct writing technology. Pattern data which is performed by a CAD system is converted by a VAX/780 and transmitted to an electron beam exposure system (EBES) through a communication controller at the speed of 1 Mbit/sec. Overlay accuracy less than 0.2 μm is obtained by scanning the alignment marks located at the periphery of a silicon wafer. The marks are fabricated by etching the silicon substrate to 2 μm depth. Radiation effects induced by electron beam irradiation is examined by Monte Carlo simulation. In production of ECL (emitter coupled logic) gate arrays using electron beam direct writing technology, the surface of the silicon nitride (SiN) interlevel insulation layer is coated with a thin conductive layer of TiW in order to avoid the charging phenomenon and the radiation damage caused by electron beam irradiation.

Multimedia applications of microprocessor with embedded DRAM

The M32R/D is a 32-bit microprocessor with a large-capacity on-chip DRAM. It consists of a 32-bit RISC CPU, a 32-bit/spl times/16-bit multiply and accumulator (MAC), either 1-Mbyte or 2-Mbyte DRAM, 4-Kbyte cache memory, and a memory controller. The CPU, DRAM, and cache memory are connected via a 128-bit 66.6 MHz internal bus yielding high performance and low power dissipation. The chip is capable of coping with a with range of applications and thus provides the system designer with great flexibility. For instance, a portable multimedia system can be realized by only three chips: an M32R/D chip, an I/O ASIC chip, and programming ROM. This means that a total system solution can be achieved at a lower cost with higher performance. Personal digital assistants (PDAs) and digital still cameras are such examples.

A Computer-Controlled Experimental FIB System

A focused-ion-beam writing system for experimental use will be described. This system was designed to be simple and to be flexible enough for doing experiments. The system configuration, ion sources, and some considerations regarding alignment signals will be mentioned.