Members' Profiles

FANUC LTD.
Achievements of the Micromachine Project
and the FANUC ROBOnano Ui Machine
1. Development of Micromachines
Seiuemon Inaba

FANUC Ltd. engaged in the development of ultra
precision micromachining technologies under theguidance of MITI's Micromachine Project (theIndustrial Science and Technology Frontier Program).
Our ultra precision micromachining technologies haverecently enjoyed increased usage in the manufacturingof molds for optical devices, small electroniccomponents, and the like. In this paper, we introduce
some achievements of the Micromachine Project.

Executive Adviser, Honorary Chairman(the First Chairman of Micromachine Center)

Recently, this technology has been used in theultraprecision micromachining of a mold for forming
front-light panels used in cellular phone LCDs.
Another technology for machining rows of evenfiner grooves within microgrooves has become
practical. The use of this technology has expanded indental care.
Technical development has accelerated on thepractical use of ultra precision machining for
microstructures other than ordinary simple grooves.
Mirrors, lenses, and the like applying free-form grooveprocessing made possible by a shaper engraving andhaving multiple focal points for one light source showpromise as a new generation pickup method for CDsand DVDs.

2. Introduction of Ultra Precision Micromachining
TopicsUltra precision micromachining technologies are an
attempt to improve the age-old mechanical processes,
such as cutting and grinding, from a micro to a nanolevel based on our own developed FANUC ROBOnano
Ui machine. A single-crystal diamond tool is used to
cut microstructures, forming a surface roughness atthe nano-level. According to statistics by the Aachen
University of Technology (RWTH Aachen) in Germany,
although 40% of techniques applied in micromachining
use etching methods and 30% cutting and grinding
methods, the cutting and grinding methods are themost precise of existing techniques.
One ultraprecision micromachine technology is themachining of microgrooves, as in diffraction gratings.
Ordinarily, the grooves are arranged at intervals ofmicrons. In addition to their application in scales andthe like, these grooves are used as light focusing
devices and, in terms of applied technologies, haveattracted much attention as molds for manufacturing
light-guiding panels used in liquid crystal displays.

(a) Microgrooves channels formed (b) Integral tri-focal diffraction grating within the light-guiding panel of aa diameter of 2 mm
liquid crystal panel at a pitchof 25 microns
Fig. 2 Examples of ultra precision micromachining

3. Achievements and Future Challenges
It is my belief that the present R&D confirmed thatthe existing diamond processing method achieves
superior surface roughness to lithography and etchingprocesses. This view is already spreading through themicromachining industry and is thought to be one
major achievement of the Micromachine Project that
concluded in March of this year.
At FANUC LTD., we were able to further develop
ultra precision micromachining technologies throughthe ROBOnano Ui machine. It is my hope that this willcontribute to the field of micro and nano technologies.

Fig. 1 The FANUC ROBOnano Ui friction-free ultra
precision nanomachining tool9

Fujikura Ltd.
1. The Challenge of Micromachine Technology
Fujikura has conducted microjoint research for theIndustrial Science and Technology Frontier Program
completed last fiscal year as part of our advanced
technology R&D on functional devices. We developed
technologies for stacking silicon devices in a threedimensional structure by forming through-holeinterconnections in a silicon wafer. Currently, severalof these elemental technologies have been applied toactual devices and are being incorporated in R&D on
practical applications.

Koichi Inada
Senior Managing Director,
Research and Development Headquarters

oxidation layers are currently used, this technology
cannot be employed when a device has already been
formed on the silicon wafer. For this reason, we areattempting to develop a technology capable of forming
an insulating layer on through-hole walls with a highaspect ratio at a low temperature of 400; or less.
Finally, the through-holes are filled with aconductor for forming an electrical connection. As the
aspect ratio of the through-holes increases, thenumber of feasible technologies becomes limited. In
addition to an electroless plating method, we are
currently investigating a molten metal suctioning
method for drawing melted solder into the throughholes. A method that makes it possible to introduce
conducting metal quickly using simple devices canreduce processing costs while improving the airtightseal of the through-hole interconnections.

2. Development of Micromachine Technology
Several element technologies are required to form
through-hole interconnections in silicon wafers. In
following the sequence of the formation process, wefirst form through-holes in the silicon wafer. While weare studying general technologies for forming throughholes, such as deep RIE and laser processing, we arealso forming through-holes with a high aspect ratiousing optical excitation electropolishing. This type ofelectropolishing is one method of wet etching and isdistinctive for its low per-hole cost and ability to form
through-holes at a aspect ratio of 100 or higher, which
is not possible with other methods. Fig. 1 shows across-section of through-holes formed in a siliconwafer by the optical excitation electropolishingmethod. Issues remaining in this process are how to
optimize electropolishing conditions, how to improve
the quality of the through-hole walls, and how toincrease the speed of electropolishing.
Subsequently, an insulating layer must be formedon the walls of the through-holes. Although thermal

525µm

Fig. 2 Filling through-holes with tin by molten metalsuctioning

3. Future Challenges
We would like to continue developing technologies
for forming through-hole interconnections in siliconwafers. In addition, we hope to develop techniques for
applying micromachine (MEMS) element technologies
developed thus far to a wide range of semiconductor
packaging and mounting fields.

Fig. 1 Cross-sectional view of the through-holes10