Q7

mK,μKの世界で量子液体固体の不思議を探求
低温物理学

世界
唯一
超低温度Ｍ
ＲＩ
装
置

松原明 准教授
教授

博士研究員１名
博士課程生１名
修士課程生４名 +世界中の仲間たち
卒業研究生４名

佐々木豊

5mm32006 Kyoto Univ.

核整列固体3Heの世界一クールなMRI像(500μK)

2016 Kyoto Univ.

超流動3Heのカイラルドメイン構造のMRI像
Kasai et al. Phys. Rev. Lett. (2018)

低温物理学研究室の活動・教育方針
理想的物質系ヘリウムを舞台とする基礎物理
シンプルな構成要素（フェルミオンのヘリウム３とボソンのヘリウム４）＋制御された環境 >> 普遍的な物理現象を精密に理解しよう！

研究対象となる物理現象は広範囲（興味次第で広がる）
超流動ヘリウム３の多自由度波動関数の実空間変動，量子渦などトポロジカルな構造体の探索，相転移による位相欠陥の生成と宇宙論の実験的検証，
制限空間・境界条件制御による新奇対称性超流動相の実現，量子界面のダイナミクス，量子相転移，量子乱流，，，，

方針：新しい実験装置を開発して新しい発見に近づく力をつけるために、研究開発力を鍛えます。
研究内容について詳しく知りたい方の研究室訪問歓迎マイクロマシンMEMS/NEMS と基礎物理
ナノ機械系と超流動体はどのように結合するか？
025003-2 González
González
et al.
025003-2
et al.

Instrum.
025003(2013)
Rev.Rev.
Sci.Sci.
Instrum.
84, 84,025003(2013)

FIG. 2. SEM pictures of a typical device. An overall view of an H2 device
FIG. 2. SEM pictures of a typical device. An overall view of an H2 device
Low Temp(2010)
158: 678–684
679sameis shown in the top left figure. The top right figure shows half of theFIG. 1. CAD image of a typical H1 device. NoJ substrateis Physshownin thisis shown in the top left figure. The top right figure shows half of the same
FIG. 1. CAD image of a typical H1 device. No substrate is shown in thisdevice.
Thebottom
left
figureshows
amoredetailed
viewofthespringfigure. The springs also serve as electrical connections from the center plate device. The bottom left figure shows a more detailed view of the spring of offigure. The springs also serve as electrical connections from the center platean H1 device at its anchor point with the substrate. A close up look at theto the external bonding pads on the chip.
an H1 device at its anchor point with the substrate. A close up look at theto the external bonding pads on the chip.
comb-electrode fingers is displayed in the bottom right figure.
comb-electrode fingers is displayed in the bottom right figure.

A Kraus et alusing
a specialized
CAD
softwarecalledL-Edit.
designsusing
a specialized
CAD
softwarecalledL-Edit.
TheThedesignsprevents
damageto thedevice
becausepolysilicon
strucwerethensenttothecompany
forfabrication.
Inthisdamage
to thedevice
becausethe thepolysilicon
strucwere then sent to the company for fabrication. In this pro-pro- prevents
tures
are
notyetmovable.
Afterdicing,thedevices
werecess,followinglayersdepositedon thesubstrate:
three tures are not yet movable. After dicing, the devices were “re-“recess,thethe
followinglayersarearedepositedon thesubstrate:
threeleased”
using
a wetetchingprocedure.
removespolysiliconlayers(Poly0,Poly1,Poly2)
usedas thestructural leased”
using
a wet
etching
procedure.
ThisThisremoves
the thesac-sacpolysiliconlayers(Poly0,Poly1,Poly2)
usedas thestructuralrificial
PSG
layersandfrees
themechanicallyactiveparts.
material,
siliconnitridelayer(Nitride)usedelectrical rificial PSG layers and frees the mechanically active parts.
material,
oneonesiliconnitridelayer(Nitride)
usedfor forelectricalAstandard
processsuggestedbythefoundry
isfollowed
isolation
fromsubstrate,
phosphosilicate
glass(PSG) A standard process suggested by the foundry is followed for for
isolationfromthethesubstrate,
twotwophosphosilicate
glass(PSG)
13etchingis doneimmersingchipsreleasing.
13layers(firstsecondoxide)
as sacrificial
layers,a metal releasing.
TheTheetchingis doneby byimmersing
the thechips
in inlayers(firstandandsecondoxide)
as sacrificial
layers,andanda metal49%hydrofluoric
acid
for
7min.
After
thereleaseprocess,layer(METAL)
used
improved
electricalconnectivity.
hydrofluoric acid for 7 min. After the release process, if iflayer(METAL)
used
for for
improved
electricalconnectivity.
TheThe 49%
thechips
allowedto dryby exposure
to theenvironment,label,material,thicknessof eachlayer
patterned
chips
are areallowed
to dryby exposure
to theenvironment,label,material,andandthicknessof eachlayer
patterned
on onthethe the thesmallplates
comprisingthedevices
might
be pulled
wafer
is listedin Table
I. Theprocess
is carriedout
on 100mm the small plates comprising the devices might be pulled
to- towafer
is listedin Table
I. Theprocess
is carriedon 100mmTwo
Fig. 1out(Coloronline)
typicalwards
NbTi-coatedstructures
mimickingtheaction
vibratingand
wire.stick
Top: NEMS
struc-This
each
other
bycapillarytogether.
(a)wafers
(1–2! cm)it startsheavilydopingsur- wards
otherbyright
capillary
andcoupling
stick together.
Thiswafers(1–2! cm)
andandit starts
by byheavilythethesurturedoping
200 nm thick,length 15 µm.
The eachelectrodeon theenables action
a capacitive
to the vibrating
phenomenon
is calledstiction.
To avoid
thisproblemthechips
facewithphosphorus(9–10!/sq).
Thelayersaredeposited
phenomenon
iscalledstiction.
Toavoid
thisproblem
thechipsdevice.areThedepositedmetal layer is roughly 60 nm thick. Bottom: MEMS structure 5 µm thick, length 1.85 mm.
face with phosphorus (9–10 !/sq). The layers
criticalpointdryer.
After
drying,weredriedusingaCO
2one canpoint
The metal(LPCVD)
layer is roughly
nm thick.
On using
both SEM
pictures,see the dryer.
curvatureAfterinducedby theusingpressurechemicalvapor
deposition
and150weredrying,drieda CO
2 criticalusing
low1.lowpressurechemicalvapor
deposition(LPCVD)andFigure
The fundamental
resonanceofthe Si/Aubeam
as seenthechips
werepackaged
inacustom
designed
20-pinsocket.
internal
stressof themetallic layer
createdduringthefilm
growth[13].
Thisstresshas
aninfluenceon
thepatterned
bya
combination
ofphotolithography
andreactive
the chips were packaged in a custom designed 20-pin socket.
patterned
by a combinationof beamphotolithography
reactivein the reflection
coefficient of thefrom theresonancelinear and(L)position
into
the[14]. The drive
and detection
are also depicted,
seemadetext from the bonding pads on
Electricalconnections
wereionetching(RIE).
PSG
is andused
inmbartheprocessto dope
theconnections were made from the bonding pads on
nonlinear(NL)
regimeat
4.2
KHe
gastopressure.
Leftionetching(RIE).
PSG
is usedin20theprocess
dope
the
dif-dif- Electricalthechip
to thepads
on thepackage
by usinga West-Bond
inset:
circuitdiagramof
the experimental
setup.
The reflected
ferentPolylayerswithphosphorus
byannealing
thewaferatthechip
tothepadson thepackage
by usinga West-Bond
ballballferent Poly
layers with phosphorus by annealing the wafer at
3 mm thick gold wire. Scanning◦wedge wire bonder with 0.025

課題研究Ｑ７－低温物理
課題研究でやること●●●

ゼミ：超伝導・超流動・BECの英文教科書を輪読。
“Superconductivity, Superfluids and Condensates”
実験研究：超流動ヘリウムの不思議な現象を探求する実験の企画・製作・実行を通して、実験研究のデザイン法を学習。
先輩の真似を研究室メンバーと楽しい交流：
せずに新しい花見・宴会・遠足、etc
テーマを追求◎な人：
人と同じことをするより、自ら道を切り開きたい人
一人で静かにしてるより、議論し合うことが好きな人“ものづくり”の腕を磨きたい人△な人：
議論して考えを深めるより、答えだけを知りたい人“寄らば大樹の陰”な人

研究室メンバーとの楽しい活動 中
粛
自 をめ
録
た記のいに
禍しみナ
新し
コロ んと を楽
皆さ る日 す
せ まら
残奴
いなて”
n
し低温研で濃い時間oimr！
eを過ごしましょうF
迎“
歓大熱烈

３世代５０年にわたる研究室OBたちとの交流