Worldwide R&DMicroscale Thermal Engineering
Takayoshi Inoue, Professor,
Department of Mechanical Sciences and Engineering Graduate School of Science andEngineering, Tokyo Institute of Technology
The primary research activities in our laboratory focus
on thermal engineering on a microscale. The researchstaff at the laboratory currently includes AssociateProfessor Osamu Nakabeppu, Research Associate Yuji
Suzuki, and graduate and undergraduate students of thedepartment.
Although we use the simple term "microscale," this issuch an extensive field that we have decided to divide it
into two domains. The first is a domain on the order ofmicrons in which devices, such as microchannels,micromachines, or MEMS, can be treated as continuums.
The second is a molecular-scale domain in which we
consider phenomena on the molecular or quantum level.
Nanotechnology, a term that is frequently heard thesedays, would probably be included in the latter domain.
Below, I introduce two or three examples of studies
conducted in our laboratory.
The first example is a method for measuring
temperatures in microspaces. The most basic activity inthermal engineering research is to measure temperature
distributions in target areas with high accuracy. However,
optical measurements become impossible at a scale lessthan the diffraction limit of light. Accurate temperature
measurements are also difficult when using a probe
because the probe itself affects the measurements. At ourlaboratory, we mounted a temperature sensor andmicroheater on the probe of an atomic force microscopeand set the probe temperature equivalent to the sample
temperature. In this way, we were able to accurately
measure temperatures at a spatial resolution of about 25
nm (Fig. 1). It is believed that a precise technology formeasuring temperatures at a submicron spatial resolution
would be beneficial to the semiconductor industry and thefield of micromachines.
Studies on the flows in microchannels are important
for CPU cooling and µ-TAS technologies. At ourlaboratory, we studied the fabrication of a laminated-type
micro heat exchanger using microchannels, as well as gasabsorption enhancing technology for microchannel flow.
Finally, we also studied a technology for forming ultrashallow junctions in semiconductors as a molecular-level
thermal engineering technology. The line width in theCPU has been decreased to less than 0.1µm. To keep
pace with this, it has become necessary to form extremely
shallow junctions of less than 30 nm. There is demand todiffuse impurities uniformly up to 30 nm and to form asteep concentration gradient at depths greater than 30

Thermopile
T.C.

Cr (0.3µm)
Ni (0.15µm)

260µm
Heater70µm

0Topographic Image

70µm

070µm 0705nm 41.7

00Temperature Image(Active Mode)

70µm
45.7:

Fig. 1 A probe for measuring temperatures inmicrospaces and the temperature distribution
around fine wires electrically heatedDopant implantation

Recrystallization, HomogenizationLaser

20-30nmFig. 2 The formation of an ultra-shallow junction
nm, and also to restore a good crystalline structure. Using
simulations, we have studied the feasibility of forming
such junctions with laser heating.

MICROMACHINE No. 39
MICROMACHINE is published quarterly by Micromachine Center (MMC) to promote the international exchange of
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Date of Issue : May 17, 2002

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