Selective Nanomachine Structure Formation Technology
Isao Shimoyama, Professor, Department of Mechano-Informatics, Graduate School of Information
Science and Technology, The University of Tokyo

Tetsuo Kan, Same as above (affiliated with Shimoyama-Matsumoto Lab)
Spectroscope

Modern-day Japanese society has come to place greatemphasis on quality of life (QOL). One indicator of this is thefact that “metabo,” a slang term for “metabolic syndrome”(which refers to a combination of medical disorders that
increase one’s risk for cardiovascular disease and diabetes) has
become a buzzword. Another is that weather reports in Japan
include daily predictions of the amount of pollen that will bedispersed in the atmosphere. There is now great interest inJapan in maintaining health and physical well-being. But inorder to properly manage one’s physical condition on a day-today basis, collection of data regarding the body and thesurrounding environment is indispensable. If MEMS technology
could be used to create this kind of sensor system in a single
integrated microchip, it would open the path to constant realtime monitoring of both the status inside the body and theenvironment outside the body. At the Shimoyama-Matsumoto
Lab of The University of Tokyo, researchers in the “SelectiveNanomachine Structure Formation Technology” project (part ofthe Fine MEMS Project) are working to develop themanufacturing technologies that will be the key to achieving
such miniature sensor systems.
Fig. 1 shows a specific example of a sensor used to monitor
inside and outside the body. A method called Surface Plasmon
Resonance (SPR) is used for sensing. This method is capable ofdetecting biomoleculer interaction in a “label-free” manner byusing the resonance of metal. To construct an SPR sensing
system, technology for manufacturing multiple components
such as the SPR sensor, spectroscopic mechanism, light source
unit, photoreceiver and so on is required. For this reason, thenecessary component manufacturing technologies have been
divided into four main areas and work to develop thesetechnologies is underway.
Surface nanostructure manufacturing
technology using direct
write technology

SPR sensors may use either of two methods: a fixed lightsource wavelength and a variable incident angle, or a fixed
incident angle and a variable wavelength. With the lattermethod, the number of adjustable sections can be decreased,so this method is more suitable for creating smaller andthinner sensors. In this case, however, a filter to separate
light is needed. For this reason, researchers are working todevelop technologies for manufacturing a Fabry-Perot
interferometer with nanosize adjustable gaps (Component
Technology 3).

Light source unit and photoreceiver
The laser diodes and photodiodes used as the light source
unit and photoreceiver are formed on top of compound
semiconductor substrates (GaAs, GaN etc.), and most areprovided in the form of bare chips. Research is underway todevelop methods for precision batch placement ofheterogeneous materials and a large variety of components on asensor substrate (Component Technology 4).
Let us take a look at one achievement of this research: abatch placement technology for a large variety of components.
Fig. 2 shows an overview of the technology as well as
photographs of the results. Up to now, when a large variety ofcomponents were integrated, a serial “pick and place” method
had to be used for each component in sequence. In contrast,
this method allows parallel integration of many different
components at once. An elastic material such as silicon rubber
is used as a stamping material, and the components are picked
off the original substrate all at once in parallel. Transcription iscomplete when the components that have been picked from theoriginal substrate are stamped onto the target substrate for
integration. Furthermore, by repeating this process, it ispossible to transcribe a large variety of components onto thesame substrate, using the same procedure as in multicolor
printing. In this way, three-dimensional integration of multiple
microstructures and transcription of glass nanostructures ontoa MEMS structure are possible. This method shows promise as
an integrated placement technology.

SPR sensor

L/S up to 50 nm
Film thickness 80 nm or more

Si prism3-dimensional curve formation technology using
quantization offset mask etching and surface
planarizing technology

Structure B

Variable wavelength filter

Transcriptionof 1st layer

Transcriptionof 2nd layer

Microstructure integration

Structure ALightsource unit

High luminosity / high density
layout technology using stamping
transcription and self-alignment

Photoreceiver

Adjustable gap
up to 150 nm

Pick up

Planar adjustable nanogap forming technology
and gap drive technology

Mechanism for pickup from substrate
PDMS stamp

SiO2column
breakage

Fig. 1 SPR sensor system
Si structures are createdon the SOI substrate
Sistructure (the structures are supportedby SiO2 columns)

SPR sensor
Normally, an SPR sensor has a metal film (gold, silver etc.)
approximately 50 nm thick deposited on the base of the prism,
etc. Glass is usually used as the material for the prism.
However, if near infrared light is used as the light for the SPR
sensor, it is also possible to use a prism made of silicon.
Researchers are working to develop three-dimensional curveformation technologies to enable the inclined silicon surface tobe machined to any desired angle through a combination ofelectron beam direct write (EBDW) technology and etching
technology (Component Technology 1). Normally a flat film
is used as the metal thin film, but nanosize structures are being
created on the metal film in order to improve SPR performance(Component Technology 2).

Multiple Si structures are integrated on the same substrate

1st layer

2nd layer

Fig. 2 Stamping transcription technology
The project is now in its second year and the research issteadily producing results. The researchers involved in theproject are working steadily with the goal of developing
technologies that will serve as the foundation for next-generation
MEMS technologies, with a view toward practical application.

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