走査型プローブ顕微鏡カタログ

走査型プローブ顕微鏡（SPM）関連製品ラインナップ

team nanotec社製 AFMプローブ
巴工業は、世界各国の特徴のあるSPM用関連製品を紹介しています。
現在はイスラエル、ドイツ、オランダ、ブルガリア、USAからの製品を取り扱っております。

近接場光学顕微鏡(NSOM)（イスラエル）

近接場光学の権威であるProf. Aaron Lewisが開発した、Nanonics社製

NSOM/SPMの複合システムおよび、ガラス製NSOM/SPMプローブを取り扱っております。
メーカーです。顕微鏡を始め、様々な分析装置との連動が可能です。

SPM用プローブ

様々な会社の、特徴のあるプローブを取り扱っております。
現在、8社のプローブが販売可能です。

Q-Control/QFMモジュール

Munster大学からスピンオフして設立された、nanoAnalytics社製品を（ドイツ）取り扱っております。こちらは世界で初めてQ-ControlをSPMに応用した製品になり、既存のSPMに組み込んで使用いたします。
Q-Control/QFMモジュールはカンチレバー共振周カーブのQ値
コントロールと、CEモードでの周波数シフトイメージの取得が可能です。

熱測定(SThM)モジュール

Michigan大学からスピンオフして設立された、Picocal社製品を取り扱っております。こちらはポリイミド製熱測定プローブを用い、サンプルの温度分布をトポグラフィと同時に取得できます。
既存のSPMに組み込んで使用いたします。

MultiView NSOM/SPMシステム
特徴●先端が露出しているカンチレバー型光ファイバープローブ、上下方向で光学的にオ－プンな構造になっている3D Flat ScannerTMを採用することにより、市販の光学顕微鏡（正立型、倒立型を問わず）へ容易に組み込むことが可能です。
●AFMと同じフィ－ドバック機構を有するため、NSOM、SPMの同時測定、もしくは顕微光学測定、SPMの同時測定が可能です。
フィードバックには、従来の光テコ法とNanonics社独自のTuning Fork フィード
バックの2種類から選択可能です。
●分光器、顕微ラマン装置、SEM、共焦点レーザー顕微鏡等の他の分析装置と組み合わせることが可能です。
●プローブは、Nanonics社製品以外にも、各種Siカンチレバーも使用可能です。

Nanonics社独自のテクノロジー
3D Flat ScannerTM
厚み7mmで、最大スキャンレンジがXYZ軸ともに70μmというスキャナーです。
ピエゾ素子の配置によりスキャナー中央に24mmの開口が開けられており、上下方向で光学的に オープンな構造になっています。また、厚みが7mmと薄いので、各種装置への組み込みも容易です。

カンチレバー型ガラスプローブ

300-1000μm

50-1500μm
30-500μm

Normal Force Tuning Forkフィードバック

従来のカンチレバーとは異なり、先端が露出しており、またカンチレバーの Tip長が長いので、光学測定に影響を与えずに
スキャンニングが可能です。
Nanonics社では、NSOMプローブ、AFMプローブ、Metal
NanoWireプローブ、中空ナノピペット等特徴のあるプローブをご提供しています。

ガラスプローブに、高Q値のTuning Forkをとりつけ、Normal
Forceフィードバックを行うものです。
これにより、光学的にオープンな構造を保ったまま、 プ
ローブスキャニングが可能となりました。
特徴:

High Q factor
High Force Constant
No Jump to contact
Ultra soft contact
Optically free feedback
Amplitude/Phase Feedback

製品ラインナップ
NSOM/SPMシステム

MultiView4000 Multi Probe NSOM/SPMシステム

1

カンチレバー型光ファイバープローブの特長を最大限に生かした、画期的なモ
ジュール型マルチプローブNSOM/SPMシステムです。ラインナップの中では、最も光学的にオープンな構造で、様々な光学測定との連動が容易です。
Tuning forkフィードバップローブ毎にスキャンモジュールが独立しており、 最大4本までのマルチプローブ測定が可能です。
それぞれのプローブとサンプル部は独立して制御可能です。スキャン
ジュールは後から増設可能です。

モ

基本動作モードはAC modeですが、オプションの光てこフィードバックにより、Contact modeへの対応も可能です（大気中/液中可） 。

MultiVew2000 NSOM/SPMシステム

1
Tuning forkフィードバックを採用したことにより実現した、
プルスキャニング方式のNSOMSPMシステムです。

プローブ/サンプローブ側、サンプル側に3Dフラットスキャナーを2枚組み込んでおり、従来製品にくらべ、コンパクトな構造になっています。基本モードはAC mode （大気中/液中可）です。

MultiView1000 NSOM/SPMシステム

1
光テコフィードバックを採用した、サンプルスキャニング方式のNSOM/SPMシ
ステムです。
基本モードはContact mode、AC mode（大気中/液中可）です。

CryoView2000 NSOM/SPMシステム

1
MultiView2000をベースにした、低温(10K)、高真空下でのNSOM/SPM/共焦点イメージングの同時測定が可能なシステムです。プローブ側、サンプル側に3Dフラットスキャナーを2枚組み込んでおり、プローブ/サンプルスキャニン
グ方式になります。
基本モードはAC mode（大気中/真空中可）です。

NSOM/SPMプローブ
NSOMプローブ(光ファイバー)1
トポグラフィと近接場光イメージングが同時に可能な、カンチレバー型NSOMプ
ローブです。開口径は50nm～300nmまで、50nmピッチで指定可能です。
300nm以上の開口にも対応しています。
型番: CFN-XX(XXは開口径）

ガラスAFMプローブ

1
ガラス製AFMプローブです。先端曲率半径は10nmからで、指定可能です。
また導電コーティング(Cr/Au）も可能です。
型番: CAFP

Hollow Nano Pipette1
中空ガラスキャピラリを加工したナノオーダーのピペットです。ガスや液体を流すだけでなく、加工してNSOMプローブとして使用することもできます。
先端開口径は20nmからです（NSOMは50nmから）
型番: CMP-XX(XXは開口径）TERSプローブ

1
Hollow Nano Pipetteの先端に金属ナノ粒子を取り付けた、TERS用プロー
ブです。
先端の金属はAuもしくはAgで、粒子径は50nmから作成可能です。
型番: CMP-TERS

Glass Insulated Nano Wireプローブ

1
ガラスキャピラリの中にナノワイヤを組みこんだプローブです。用途に応じて
Coaxial/電気化学用/熱電対が作成可能です。
型番: CM

複合測定アプリケーション
AFM/NSOM-SEM

1
広い範囲を高速に、高分解能で観察できるSEMと、3Dイメージングが可能な AFMを組み合わせたアプリケ-ションです。MultiViewシステムはカンチレバー型ファイバープ
ローブを用いてスキャン方向を変えることにより、SEMでは確認できない溝のサイド
ウォールのトポグラフィ像も取得できます。

AFM-Raman/TERS

1
顕微ラマン分光器とMultiViewシリーズを組み合わせたアプリケ－ションです。AFMのフィードバック機構を用いてレンズ－サンプル間距離をnmオーダーで一定に保つこと
により、共焦点レ―ザ―顕微鏡と同様に空間分解能が向上し、 ラマン強度をサンプ
ル表面形状の影響を受けずに正確に測定できます。
また、Nanonics社製Enhanced probeを用いることにより、TERS測定も可能です。
MultiView2000、MultiView4000がこのアプリケーションに適しています。
現在、Renishaw社製品、Jobin Yvon社製品、セキテクノトロン社製品に対応可能です。

Fountain Pen NanolithographyTM Technology

1Nanonics社製カンチレバ－型中空ナノピペットにたんぱく質等の分子を注入し、スキャンすることにより、基板上に分子をnmオ－ダ－の精度で、デポジションさせることが可能です。たんぱく質の変わりに金属のナノパ-ティクルを使用したり、ガスもしくは液体を注入してナノエッチングを行うことも可能です。

屈折率測定アプリケーション

1
微分干渉顕微鏡とAFMフィードバックを組み合わせることにより、サンプルの屈折率分布が測定可能です。
屈折率の分解能は10-4です（測定物の透明度に依存）。
また、測定物の反射率をNSOMで 高分解能に測定を行うことによっても屈折率分布が測定可能です。

Renishaw

MultiView シリーズ比較表

MultiView1000

MultiView2000

MultiView4000

測定モード

AFM

Contact mode
AC modeAC modeAC modeContact mode*（*光てこオプション時）

NSOM

Transmission Illumination
mode
Reflection Illumination
modeCollection mode

Transmission Illumination
mode
Reflection Illumination
modeCollection mode

Transmission Illumination
mode
Reflection Illumination
modeCollection mode

液中測定

AFM/NSOMで可能

AFM/NSOMで可能

AFM/NSOMで可能

その他モードMFM/導電測定/熱測定/Nano fountain
Pen/NanoIndentation

MFM/導電測定/熱測定/Nano fountain
Pen/NanoIndentation/
AFM-Raman/TERS

MFM/導電測定/熱測定/Nano fountain
Pen/NanoIndentation/
AFM-Raman/TERS

ヘッド仕様
スキャン方法サンプル

サンプル/プローブ

サンプル/プローブ

最大スキャン範囲

100μm(XYZ)

100μm(XYZ)

プローブ: 30 μm (XYZ)
サンプル: 100 μm (XYZ)

スキャナー分解能< 0.05 nm (Z)< 0.15 nm (XY)
< 0.02 nm (XY)

< 0.05 nm (Z)< 0.15 nm (XY)
< 0.02 nm (XY)

< 0.05 nm (Z)< 0.15 nm (XY)
< 0.02 nm (XY)

(low voltage mode時)(low voltage mode時)(low voltage mode時)

光てこ法式

Tuning Fork方式

Tuning Fork方式
光てこ方式（オプション）

市販の光学顕微鏡全般（正立、倒立問わず）

市販の光学顕微鏡全般（正立、倒立問わず）

フィードバック方式

顕微鏡仕様
仕様可能な顕微鏡

市販の光学顕微鏡全般（正立、倒立問わず）
正立顕微鏡: 13mm

必要な対物レンズWD

正立顕微鏡: 7mm

正立顕微鏡: 4.8mm（50 X 0.45NAが使用可）（100 X 0.75NAが使用可）（100 X 0.75NAが使用可）

倒立顕微鏡: 制限なし
（油浸レンズ使用可）

倒立顕微鏡: 制限なし
（油浸レンズ使用可）

倒立顕微鏡: 制限なし
（油浸レンズ使用可）

SPM用プローブ
特徴team nanotec社製 AFMプローブ
巴工業は、世界各国の特徴のあるSPM用プローブを紹介しています。
現在はドイツ、オランダ、ブルガリア、USAにある8社の製品を取り扱っており、これらのプローブは市販されているほとんどのSPMで使用可能です。

プローブメーカーラインナップ
Innovative Solution

BudgetSensorsのブランド名で、安価で高品質なSPMプローブを

Bulgaria 社(ブルガリア)

提供しています。

team nanotec社

IBMからスピンオフして設立された、世界で唯一プラズマエッチングで（ドイツ）

プローブを製作しているメーカーです。
高精度のMEMS加工技術を持ち、電子線リソグラフィ用フォトマスク等のビジネスも展開しております。Tip形状はピラミッド形状ではなく、円錐形になります。また特注対応も可能です。

SmartTip社（オランダ）

Twente大学のSystems and Materials for Information Storage グループとの共同開発により誕生したメーカーです。 学内のMESA+ナノ
テクノロジー研究所に隣接したMESA+ TechPark内に設立されています。
磁気測定に特化しており、SmartCoatTMと呼ばれるコーティングを施した
高性能MFMプローブを提供しています。また、長寿命、高品質の化学修飾
プローブも開発中で、2010年に販売開始予定です。 。

Novascan社

化学修飾プローブ、コロイド（パーティクル）プローブを提供して（USA）いるメーカーです。 10年近い実績があります。

Microstar technologies社

1982年に設立され、Diamondプローブのみならず、Diamond Knife、Indenter、Diamond Firamentなど、Diamondを取り扱う経験の豊富なメーカーです。

各社とも特徴のあるプローブを取りそろえております。またカタログに載っていないメーカーもございますので、詳しくは
弊社機能材料部までお問い合わせください。

BudgetSensors SPMプローブ

http://www.budgetsensors.com

BudgetSensors SPMプローブは、安価で高品質なプローブです。
Contact mode用、Intermittent contact mode用(高共振周波数/鄭共振周波数/
低ばね定数）、Force Modulation用の3種類がベースになります。こちらに
各種コーティング、Alignment grooveなどのオプションが選択できます。
主な仕様

Alignment grooves･Tip形状四面体

プローブのホルダー部背面に･Tip曲率半径10nm以下アライメント用グルーブが形成･Tip高さ15um

されているプローブです。

･ハーフコーンアングル

20-25°(正面)25-30°(横)･Rotated Tip

Tip前後が反転している形状で、SPMセット時に前後の角度がほぼ対称

プローブラインナップ

G: Alignment groove付き

プローブタイプ･Contact mode用プローブ

各種コーティング
･反射コートティング(Al)Contact/ContAl/ContAl-G

シリコンナイトライド以外のプローブで･Intermittent contact mode用プロ－ブ
Tap300G/Tap300Al-G (高共振周波数)

ContG/Tap300G/Tap190G/Multi75G

Tap150G/Tap150Al-G (低ばね定数)に対応化･金コ－トプロ－ブ(全面及び背面)

Multi75G/Multi75Al/Multi75Al-G

ContG/Tap300G/Multi75G

MagneticMulti75G New

Cont/Tap300/Multi75に対応化･シリコンナイトライドプロ-ブ･Special･導電コーティングプロ－ブ（Pr/Cr）

Tap190G/Tap190Al-G (低共振周波数)･ Force Modulation用プロ－ブ･ MFMプロ－ブ対応化

全面コート(GB)及び背面コート(GD)より選択

SiNi

AIO / AIO-TL New･ DLCコーティング
ContG/Tap300G/Tap150G/Tap-190G/

一つのプローブに、Cont / Multi / Tap150 / Tap300 のMulti75Gに対応化New

4種類のレバーのついているプローブです。Tiplessも選択可能です。

AIO All-in-One probes
キャリブレーションスタンダード
Height Calibration Standard

TipCheck

正確なナノ・ミクロンオーダーの寸法測定を

SPMプローブのTip先端の状態を評価できるサンプル
です。
良品
摩耗品
破損品

行うための、高品質の較正用サンプルです。
サンプルサイズ

5×5mm

ピッチサイズ:10um(角柱)

ステップハイト:

20nm(HS-20MG)

5um(円形及びLine)
100nm(HS-100MG)
500nm(HS-500M)

Mode

SpringConstant(N/m, typ.)Type

Resonance
Frequency(kHz, typ.)

Quantity
Tip side

Back side

Tap300None

None

10/50/380

Tap300AL

None

Al

10/50/380

None

Au

10/50

Tap300GB

Au

Au

10/50

ElectriTap300

Cr/Pt

Cr/Pt

10/50

Tap300DLC

DLC

Al

10/50

Tap190None

None

10/50/380

None

Al

10/50/380

Tap190DLC

DLC

Al

10/50

Tap150None

None

10/50/380

None

Al

10/50/380

Tap150DLC

DLC

Al

10/50

Multi75

None

None

10/50/380

Multi75AL

None

Al

10/50/380

None

Au

10/50

Multi75GB

Au

Au

10/50

ElectriMulti75

Cr/Pt

Cr/Pt

10/50

Multi75DLC

DLC

Al

10/50

Contact

None

None

10/50/380

ContAL

None

Al

10/50/380

None

Au

10/50

ContGB

Au

Au

10/50

ElectriCont

Cr/Pt

Cr/Pt

10/50

ContDLC

DLC

Al

10/50

Tap300GD
Non-Contact / Intermittent Contact

Coating40

Tap190AL

Tap150AL

48

5

Cantilever

300

190

150

Force Modulation

1 rectangular, Si

Multi75GD
3

75

ContGD

SpecialContact

0.2

13

SiNi

0.27/0.06

30/10

None

Cr/Au

30/100/300

2 trianguler. SiN

MFM

3

75

Co Alloy

Al

10/50

1 rectangular, Si

AIO

None

AIOAl

Al

AIO-TL
AIOAl-TL

0.2/2.7/7.4/
40

15/80/150/
350

None

None
Al

4 rectangular
Si
10/50

4 tiplessrectangularSiteam nanotec社 SPMプローブ

http://www.team-nanotec.de

プラズマエッチングを用いて、高品質のMEMSデバイス、リソグラフィ用フォトマスクと共にSPMプローブの製作/販売しています。

主な仕様･Tip形状

円錐形

カンチレバー標準寸法
l =125 ( ± 15 ) μm; w = 35 ( ±3 ) μm
Typ. stiffness: 40 N/m
Typ. res. frequency: 300 kHz･フルコーンアングル

10°･アスペクト比1:5以上･Tip曲率半径10nm以下･Tip高さ15um･全品SEMによる出荷前検査を行うことにより、仕様を100%保証

I= 225 ( ± 15) μm; w = 35 ( ± 3 ) μm
Typ. stiffness: 0.7 N/m; 3 N/mTyp. res. frequency: 45 kHz ; 75 kHzl = 450 ( ± 20 ) μm; w = 50 ( ± 3 ) μm
Typ.stiffness: 0.2 N/mTyp. res .frequency: 15 kHz

プローブラインナップ
SPMプローブ
ISC

標準プローブ、コーンアングルが全角で10°、アスペクト比 1:5以上

SS-ISC

先端曲率半径5nm以下の、高分解能測定用プロ－ブ
フルコーンアングル: < 5°( 先端から150 nmまでの位置で)、 Tip高さ: > 9 μm

EL-HAR5

メタルカ－バイドをコ－ティングしたプロ－ブ

HSC New

メタルカ-バイドもしくはSiNをコ－ティングした、導電測定、生体材料、ポリマ－等のナノインデンテ－ションに適した、先端が半球状のプロ－ブ(HemiSpherical Cone shaped tip）

LRCH New

広いスキャンレンジでの高さ測定、ナノインデンテーションに適した半球プロ－ブ
曲率半径は250.500/750/1000nm、ばね定数は0.2～750N/mまで対応可

HR-MFM

Co-Alloyをコ-ティングした、高分解能MFMプロ－ブ、コ-ティング厚は25nm/40nmより選択

HR-EFM

Ptをコ-ティングした、高分解能EFMプロ－ブ、コ－ティング厚は25nm

Bio-SC New

Auをコ-ティングした、生体サンプル用プロ－ブ

HR-SCC NewEBIDでSiカンチレバーにカーボンを成長させた、低価格な高分解能測定用カーボンプローブ
曲率半径3nm、Tip長さ>300nm

TNP 30Pt

Ptコートしたタングステンナノプローブ、先端曲率半径は30nm以下

SS-ISC

EL-HAR5LRCH

Bio-SC

HR-SCCCylindrical metrologyプローブ
溝の深さ測定に適したプローブです。同じ直径のまま摩耗していきますので、生産環境での信頼性のある測定が可能です。導電カーボンコートも可能です。
Tip径は15nmから200nmまで取りそろえております。
･角度補正対応可能･Tip曲率半径3°,10°,12°,13°10nm以下･基本カンチレバー寸法
l =125 ( ± 15 ) μm; w = 35 ( ±3 ) μm
Typ. stiffness: 40 N/m
Typ. res. frequency: 300 kHz

Critical Dimension(CD) プローブ
形状の3次元測定に適したプローブです。Tip先端にディスクがついた形状により、垂直方向の側壁も、たとえオーバーハングがついているものでもスキャンできます。
先端径は20nmから850nmまで取りそろえております。
Tip形状はRound、 Triangular、 Rectangular/Squareの3種類になります。
･基本カンチレバー寸法
l =125 ( ± 15 ) μm; w = 35 ( ±3 ) μm
Typ. stiffness: 40 N/m
Typ. res. frequency: 300 kHz
特注プローブお客様の要望に合わせた特注プローブの制作が可能です。最小発注単位は30本～ですが、実績のある形状であれば5本単位からの販売の可能です。一度、お問い合わせください。

製作例 1

製作例 2

Super Sharp tip
on 1000 N/m cantilever)

1.5 MHz cantilever forhigh speed scanning

Tip Characterizer
プローブのTip形状を評価するための高精度に検査するためのSi製サンプルです。6×6mmのSi Chipに、88個のCellがあります。
IVPS

ピッチ測定、側壁測定用標サンプルです。

IVPS100

1cellに5ラインある、ピッチ測定、側壁測定用標サンプルです。

ISNE

鋭いnmオーダーのエッジを持った、Tip形状評価用サンプルです。

IFSR

オーバーハングしているエッジを持った、CDプローブ評価用サンプルです。

IVPS

IVPS100

ISNE

IFSR

SmartTip社 高分解能MFM用プローブ

http://smarttip.nl

磁気記録分野での学術研究・産業の両面にわたる経験に基づき，それぞれのお客様のアプリケーションに最適化したMFMプローブ
を提供しております．

SmartCoatとはSmartCoatは、プローブTip部のピラミッドのー面のみに磁性コートを成膜する技術です。磁性コートはサンプルに対し垂直な面に施されます。

- カンチレバー部からの漏洩磁束による試料への影響を低減- 硬質磁性コーティングプローブで軟質磁性材料の測定が可能

特長- Tip部先端で明瞭で安定した磁性状態

Smart Coat

- 印加磁場中の測定に適している- 磁化方向がサンプルに対し垂直- 先端曲率半径が従来のプローブに比べシャープ-Tipからの磁気モーメントの低減
製品ラインナップ
SmartCoat スタンダードプローブ

SC-35-M/ SC-20-M /SC-10-M
市販のカンチレバーにSmartCoatを施した、標準タイプになります。
カンチレバータイプ: FMR(Nanoworld製)
コーティング材料:
Ni-Co系
コーティング厚:
35nm/20nm/10nm
空間分解能:
25nm以上High density track in MP tape

SmartCoat Lpw Momentプローブ

SC-35-LM/ SC-20-LM /SC-10-LM
軟磁性材料の観察に適したコーティングの採用した
低モーメントプローブです。
カンチレバータイプ: FMR(Nanoworld製)
コーティング材料:
Co系
コーティング厚:
35nm/20nm/10nm
空間分解能:
25nm以上300 nm dot pattern, imaged with CantiCleverhigh resolution probe

CIPTプローブ
CIPT測定用マイクロ12ポイントプローブ
General probe specs (all types)
CIPT装置用の低価格、長寿命、再現性の高いPin pitch distance、
Number of pins 12
取り扱いが容易なセラミックマウント等のLength of pins 10 (± 1.5) μm
特徴をもったプローブです。
Width of pins 600-750 nm
Pin thickness 1 μm
Available types / pin-spacing
Coating Ti/Au
Standard Type (007)
Coating thickness 5/100 (±10) nm
Pitch: 9.6, 9.3, 4.5, 3.0, 1.5, 1.5, 1.5, 1.5, 5.7, 12.4 μm

Narrow Type (004)
Pitch: 4.5, 3, 1.5, 1.5, 1.5, 1.5, 1.75, 2, 2.25, 2.5, 2.75 μm

Wide Type (005)
Pitch: 60, 24, 15, 6, 3, 3, 3, 3, 9, 12, 39 μm

Novascan社 化学修飾/パーティクルプローブ

http://www.novascan.com

化学修飾を施したプロ－ブとカンチレバ－先端にコロイド粒子をマウントしたパーティクルプローブを製造しています。
主な仕様
化学修飾プロ-ブ
市販のAFMカンチレバーに化学修飾を施したプローブです。Novascan社製パーティクル
プローブにも修飾可能です。
修飾可能な材質:
Alkanethiols:
COOH, CH3, NH2, OH, Succinimide
PEG Linkers:
PEG/COOH, PEG/NH2, PEG/Maleimide,
PEG/Biotin
Silanes:
APTES
Others:Biotin/Streptavidin/Neutravidin
パ－ティクルプローブ
tiplessカンチレバーに、コロイド球を接着したプローブです。
材質及びサイズ:
Borosilicate
2/5/10/12/20（μm）
SiO2
0.6/1/2.5/5（μm）
Polystyrene
1/4.5/10/25/45（μm）
Polyethylene
ご確認下さいTungsten
5/10（μm）

化学修飾/パ－ティクルプローブで選択可能なプロ－ブのバネ定数及びコーティング
バネ定数
Si（N/m）:
0.03/0.05/0.08/0.65/0.95/1.75/4.5/7.5/14
SiN（N/m）:0.01/0.02/0.06/0.12/0.12/0.32/0.58
コーティングAu / Nickel / Ag / Pt / Al / Chromium

Potential Applications
Inter-molecular Force Measurement / Chemical Sensing and Detection / Adhesion Forces / Surface Mapping
Hydrophilic/Hydrophobic Interaction / Attractive/Repulsive Regimes / Unbinding Forces

MicaおよびGlass基板
SPMを始めとして、 Confocal Microscopy、TIRF、Protein Binding Studies、Chemical Binding Studies、NSOMなどに用いるガラス/Mica基板です。
AFM グレードMica基板
AFM用基板として用いるMicaです。サイズは1×1cmで、1パッケージ50個入りです。
特注サイズ、Auコーティングを承っています。
化学修飾Mica/Glass基板
以下の材料を修飾したMicaおよびGlass基板です。
Amino Silanized (APTES)
Biotin terminated flexible PEG linker
Au coating with an OH surface
NH3 terminated flexible PEG linker
Maleimide terminated flexible PEG linker
Au coating with a CH3 surface
Au coating with COOH Surface
COOH terminated flexible PEG linker
Au coating with a succinimide surface

Microstar technologies社Diamondプローブ

http://www.microstartech.com/

Si及びSapphire製tiplessカンチレバーに、単結晶Diamond tipを取り付けたプローブです
単結晶Diamond Tip

カンチレバー

Tip形状は”3-SIDED PYRAMID”もしくは”Spike“から選択可能です。

カンチレバーは、SiもしくはSapphireより選択可能です。
Siカンチレバー:
Type MType N
Type P
Type Q

3-SIDED PYRAMID
ｰ Half Angle:
13°/ 9°/ 7°
ｰ Tip高さ:
50-100um（300umまで対応可能)
ｰ 先端曲率半径: <20nm※

以下の4種類より選択可
f=45kHz, L=225um, 1N/m
f=80kHz, L=225um, 4N/m
f=170kHz, L=225um, 40N/m
f=320kHz, L=125um, 40N/m

Sapphireカンチレバー: 以下のパラメータを指定
レバー長さ範囲: 200～1000um
レバー厚み:
14～46um,
ばね定数Type P
f=170kHz, L=225um, 40N/m
Type Q
f=320kHz, L=125um, 40N/m※Half Angle 7°の場合は<5nm
Spike(高アスペクト比）
ｰ Tip幅300nm
ｰ Tip高さ:
1um
ｰ 先端曲率半径: 3-4数nm

その他仕様- Conductive Diamond Tip(Sapphireカンチレバー)
抵抗率=0.04Ω・m- アクセサリー
Veeco Multimode及びDimention/Bioscope用AFM module

SEM Images of Diamond
Tip on Silicon Cantilever

Sapphire Cantilever with
Diamond Tip－Diamond Tipの再先鋭化サービス

Tapping mode image of soft sample of triblock copolymer film using a
diamond probe on silicon cantilever 4 N/m stiffness

HOPG
優れた性能を持つ高配向性結晶黒鉛です。
STM/AFM用標準試料、電極、薄膜成長用基板、黒鉛源、モノクロメータ等に用いられ、最近ではグラフェン形成にも用いられます。
以下の3種類のHOPGをご用意しております。
グレード

サイズ

モザイクスプレッド(°)

GRAS(ZYA)

12 X 12 X 1.5 mmt

0.4±0.1

GRBS(ZYB)

12 X 12 X 1.7 mmt

0.8±0.2

GRHS(ZYH)

12 X 12 X 2.0 mmt

3.5±1.5

nanoAnalytics QFMモジュール

http://www.nanoanalytics.com

nanoAnalytics社製QFMモジュールは市販のSPMに組み込み、FM modeでの動作とQ値制御を同時に可能とするモジュールです。
溶液中、大気中測定のどちらでも対応可能です。
概要
QFMモジュールは、AM(Amplitude Modulation) modeとFM(Frequency Modulation)でQ値制御をおこなうことのできるモジュールです。これにより、SPM プローブがサンプルに影響を与える力を最小化し、溶液中、大気中での柔らかいサン
プルのイメージングを向上させます。
動作モード:･ FM-mode with CE(constant excitation)･ FM-mode with CE and Q-Control･ AM-mode ("tapping") with Q-Control
駆動周波数範囲 : 7-25kHz/25-100kHz/100-500kHz
測定例

The top figure shows a Langmuir-Blodget film (DPPC) in
liquid scanned in CE-mode. The observed height of thelayer structure is significantly larger in case of imaging
with Q-Control.
[D. Ebeling, H. Hölscher, B. Anczykowski, Appl. Phys. Lett. 89, 203511 (2006)]

A tip–sample force curve obtained with a silicon cantileveron an untreated silicon wafer (symbols). The right part ofthe curve is fitted with a force law describing long-range
van-der-Waals forces (solid line). The repulsive part on theleft increases nearly linear with a contact stiffness of
10 N/m (dashed line)[H. Hölscher, B. Anczykowksi, Surf. Sci. 579, 21 (2005)]

In FM-mode with constant-excitation (CE-mode) conservative
and and dissipative tip-sample interactions can be directly
determined. The customized analysis software which isprovided with the QFM-Module enables the user to easily
quantify tip-sample forces.
[H. Hölscher, B. Gotsmann, A. Schirmeisen, Phys. Rev. B 68, 153401 (2003)]

MICROMACHINED THERMAL PROBE AND MODULE
FOR HIGH RESOLUTION THERMAL DIAGNOSTICS BY• Scanning thermal microscopy is an add-on option to the standard AFM system.
• The key element of the SThM is a micromachined thermal probe.
• PicoCal has developed a thermal control circuit unit, ST 50™, that transmits temperature contrast imaging.
• Temperature and topographic data can be gathered simultaneously.
• The ST 50™ thermal unit is easy to interface with an AFM/SPM.
• The probe is interfaced with the module and the module cables plug into the AFM controller.
• The ST50 provides thermal conductivity analysis with a gain of up to x 10,000.

• The probe signal is connected to the INPUT of the module using a BNC cable and the OUTPUT of the module to the AFM
controller.

THERMAL CONDUCTANCE IMAGING

HOT SPOTS
Hot-spotdetection:a)Topo.,b)thermal.

High Resolution Latent Image Pattern Polymide
probe was adequate for mapping 70 nm exposed but
undeveloped contact pattern. Undeveloped
Photoresist-UV113 Thickness: 400 nm, 4 / 400 nm =1%, Scan condition: 0.75 µm/s; 400 lines Sample
provided by Dr. Leo Ocola, Bell Labs.
Li et al. Hilton Head, 2002

Images reveal that the highest amplitude ofthermal waves generated by an operating
nMOSFET is always located at a region
close to the drain area. Hendarto et al. IRPS –SUBSURFACE IMAGING OF Cu WIRESIEEE 2005

Overlay of thermal
on topo. image
shows subsurface
variations. This is
not observable witha topo. scan.
6x6 m area
1 Hz scan rate
Scan conditions:
12 mA, probe 26

144nm

μ

Trenchpreparation
before Cu
deposition.
(SEMATECH
sample)Ω

Topographical
2 µm
Gaitas, Micorscopy andimage of Cu lines
Analysis, 2006
under a natural
200nm subsurface variations of Cu lines
oxide (125 nm
thick, 300nm wide). not visible topographically

PROBE CHARACTERISTICS

Performance
PicoCal Probe
Tip Diameter< 100 nm
Topographical Resolution< 1 nm
Tip Temperature Resolution< 10 mK
Spring Constant< 0.1 N/m
Detectable Thermal Conductance< 3 pW/K
Change• Temperature Range: 0 - 250 C• Nominal Resistance: 20-40 Ohm• Temperature coefficient of resistance 488ppm/C 10%.
• Material: Bolometer made of Cr/Au for the tip and lead sandwiched• between two layers of polyimide, forming a cantilever.
• 250 µm (length) × 50 µm (width) × 3 µm (thickness)• Resonance frequency: 50 kHz±

SUBSURFACE DETECTION(above) A thinlayer ofchromium
detectedthrough 5 µm of
photoresist, notpossible using
an AFM(below). Lee &Gianchandani,
Review of
Scientific
Instruments, Vol.
75, No. 5, 2004

BIOLOGICAL SAMPLES: HELA CELLS
Thermal image
topo
thermalprovidessub-surface
information
Li et al. Hilton Head,
2002

Scanning Thermal Probe

PRICING• Probe retail price: 500/probe + $80 for holder and wirebonding each probe• Circuit module retail price: $ 18,000/unit
Prices are subject to change. We reserve the right to refuse sale to anyone without giving any reason. If
payment has been made, a full refund will be issued and the customer will always be notified of ouractions providing we have valid contact information.

ST50 Module
info@picocal.com
www.picocal.com(734) 972-9348, 913-2608

STHM PROBES

Polyimide Probes for Contact-Mode SPM
Subsurface Thermal Imaging Applications
Angelo Gaitas, PicoCal Inc. and University of Michigan, Ann Arbor, USA
BIOGRAPHYAngelo Gaitas is the president and CEO of PicoCal
Inc. and a research associate in the Electrical Engineering and Computer
Science Department at
the University of Michigan, Ann Arbor. He received an MBA fromthe University of Wisconsin, Madison, andan MS in solid-state physics from the University of London. His research interests
span a variety of scanning probe microscope
techniques for manufacturing applications.

ABSTRACTThis article describes the results obtainedwith a surface micromachined probe forscanning thermal microscopy. The probe
uses polyimide as the structural material
and an embedded thin-film metal resistor as
the sensing element. The typical dimensionsof a probe are 250 µm in length, 50 µm in
width, and 3-10 µm in thickness. The probe
has measured spring constant less than
0.1 N m-1, and about 40  nominal resistance. It offers a tip diameter of 100 nm. The
probe was used to map the spatial variationin thermal conductance of various test samples. Surface and subsurface characteristics
were observed.

KEYWORDS
scanning probe microscopy, atomic force
microscopy, scanning thermal microscopy,
microthermal analysis, polymers, failure
analysis, nanoscience, nanotechnology

ACKNOWLEDGEMENTS
The author would like to thank Prof. Yogesh
Gianchandani, Dr Song Xu and Dr Shamus
McNamara for their valuable contributions
to this paper, and Sematech for providing
samples.

A U T H O R D E TA I L S
Angelo Gaitas,
PicoCal Inc.,
PO Box 131490,
Ann Arbor, MI 48113-1490, USA
Tel: +1 734 913 2608
Email: angelo@picocal.com

INTRODUCTION
Thermal measurements at the nanometerscale are of both scientific and industrial interest. Over the past decade, scanningmicroscopy using thermally sensitive probes
has been used in a variety of applications. For
instance, scanning thermal microscopy (SThM)
has been used for ultralarge-scale integration(ULSI) lithography research and cellular diagnostics in biochemistry [1-3], detecting parameters such as phase changes in polymer
blends [4], Joule heating [5], for measuring
material variations in semiconductor devices[6], and subsurface imaging of metal particles[4]. Furthermore, SThM has been used to perform near-field photothermal microspectroscopy [8]. Finally, it has been used for data
storage and many other applications [9-11].
Various thermal probes have been developed since the invention of scanning thermal
microscopy by Williams and Wickramasinghe
in 1986 [12]. These probes are generally madefrom thin dielectric films on a silicon substrateand use a metal or semiconductor film
bolometer to sense the tip temperature.
Other approaches, using more involved micromachining methods, have also been reported[13]. In a bolometer probe, such as the oneused in this study, the resistor is used as a local
heater and the fractional change in probe resistance is used to detect the temperature and/or
the thermal conductance of the sample [14].
Thermal probes are used to map the spatial
variation in thermal conductance of various
test samples whose subsurface variations are
not detectable topographically. This article
presents a preliminary study of subsurface
imaging on copper wires using a polyimide
thermal probe. The ultimate goal of this effort
is to address the semiconductor industry’s chal-lenge to develop non-destructive in-line viewing of copper voids. The use of SThM holds significant promise to detect defects such as voids
in copper lines in advanced complementary
metal oxide semiconductor (CMOS) processes.
Since copper interconnects are common inadvanced CMOS devices, it is vital for the semiconductor industry to obtain timely information about the quality of the copper electroplating process and related steps.
The use of non-electrical inspection methods for copper electroplating has several limitations. Because copper is opaque, opticalinspection methods are difficult. In addition,
since most of these failures occur on the interior of the copper trace, their detection is alsodifficult with topographic measurement
methods using an atomic force microscope(AFM) or scanning electron microscope (SEM).
While electrical methods are accurate, theyrequire at least two points of contact and special geometries that permit access to both endsof the trace to be measured; this access is usually not available without special test structures. Another option, thermal measurement
methods, can potentially overcome the problems posed by optical, AFM, SEM or electricaltest methods. Such techniques measure theinterior of the copper trace, enabling the nondestructive localized detection of voids in thecopper. Thermal measurements require only asingle point of contact and permit inspectionof all the copper traces, regardless of geometry. Vias may be inspected because the barrier
layer or remaining dielectric material have amuch higher thermal resistance compared tocopper.
Scanning thermal probes fabricated by sixto seven-mask surface micromachining
processes using polyimide as the cantilever

Figure 1:(A) Schematic of the probe die
including the probe cantilever
and tip. Reprinted from [1]with permission.
(B) Scanning electron microscope image of the probe.
Reprinted from [1] with permission.
(C) SEM image of an eightprobe array . Reprinted from[20] with permission.
(D) SEM image of a tip.

Microscopy and Analysis 20(2):S11-S14 (UK), 2006

M I C R O S C O P Y A N D A N A LY S I S S P M S U P P L E M E N T • M A R C H 2 0 0 6

S11

material have been previously reported[1,2,14,15]. These probes have been used fortemperature mapping and subsurface imaging [15], for microcalorimetry applications tomeasure the glass transition temperature in aphotoresist [1,2,14], and for maskless submicrometer thermochemical patterning ofphotoresists [16]. Hendatro et al. [17] used theprobes for the detection of hot-spots in integrated circuits (IC) revealing that the highest
amplitude of thermal waves generated by anoperating nMOSFET (n-type metal-oxide semiconductor field-effect transistor) is located at aregion close to the drain area. Basu et al. [19]have been using the probes for microfluidicsrelated work, namely for high-speed liquidpumping, mixing and particle entrapment inthin layers of oil and water. The probes havebeen arrayed into a multi-probe system forhigher throughput large area scanning [20].
An eight-probe array, such as the one in Figure
1C, has been used to produce composite thermal images of various commercial ICs. Finally,
the probes were used for high-speed contact
mode topography achieving rates of 48 Hz(1.47 mm s-1) and for lateral force scans, suggesting that polyimide is a more suitable structural material for cantilevers used in lateralforce measurements [21].

M AT E R I A L S A N D M E T H O D S
Structure and fabrication
The structure of the polyimide probe is shownin Figure 1. The probe tip diameter used wasless than 100 nm but the probe tip can be further reduced to below 50 nm with oxide sharpening. The probe had a topographical resolution of <1 nm and a spring constant of <0.1 N
m-1. The tip height was 8 µm, and the cantilever’s dimensions were 250 µm  50 µm 
3 µm. The cantilever material was polyimide
with an embedded thin wire of Cr/Au, which
also served as a sensing element. The tip was
also made of Cr/Au. The probe had spatial resolution of less than 100 nm. Thermal conductance changes of the order of 3 pW K-1 havebeen measured. A comparison with a Wollaston wire thermal probe is presented in Table 1.
The probes were microfabricated in a sevenmasking step sequence. Initially, a mold for the
tip was created by anisotropic wet etching ona Si(100) substrate. Then a sacrificial layer was
deposited and patterned, followed by thelower polyimide and the metals. Later, the second polyimide layer was deposited and patterned, followed by a gold layer, which wasused for thermocompression bonding andserved as a mirror. Finally, the probe wasreleased, flipped over, and held in place by athermocompression bond.

Asample to the chuck below, which is held atroom temperature. The simplest interface circuit operates in approximately constant powermode where an open-loop interface circuit isused to gauge the probe resistance change(thermal conductance change), which can becalculated from the output voltage change.
The interface circuit includes a Wheatstonebridge, gain stages, and filters to reduce noise.
The output voltage is plotted for the thermal
image. In the case of thermal conductancecontrast mapping, the change in probe resistance is proportional to the change in output
voltage. The supplied power change is equal
to the conductive heat loss between the tip
and sample, which is proportional to thechange in the thermal conductance of thesample. Thus the change in output voltage
represents the thermal conductance contrastof the sample [1].
Alternatively, the scanning thermal probe
may be operated at a constant tip temperature and the power required to keep the temperature constant is measured (closed-loop
mode – feedback required). This method permits contrast imaging and thermal conductivity measurements to be performed. When the
Wheatstone bridge comes out of balance, an
instrumentation amplifier amplifies thechange in voltage. Subsequently, the change
in voltage is fed into a proportional-integral(PI) controller that provides a compensation
current to keep the bridge balanced. The aver-Interface circuit and setup
There are many methods by which a thermalprobe may be utilized. It can be operated in a
passive manner whereby the tip temperature
attains the localized sample temperature. In
order to map the thermal conductance of samples, the probe is typically operated at an elevated temperature. The varying heat loss ismonitored by its effect on the tip through the

S12 M

I C R O S C O P Y A N D A N A LY S I S S P M S U P P L E M E N T • M A R C H 2 0 0 6

B

Figure 2:
Comparison of original AFM
imaging mode (A) and asimpler system for thermal
measurements in which Z-axis
actuation is eliminated (B).

age probe temperature increases or decreases
with the compensation power, so that theprobe resistance is adjusted by a compensation current through the PI controller until thechange in voltage is zero. By increasing thetemperature control resistance, the probe
resistance is also increased.
An AC thermal dither may be applied to theprobe to improve thermal resolution or to perform thermal capacitance measurements. The
thermal resolution is improved by filtering thesignal through a bandpass filter to reduce thenoise level. Since the thermal wave generated
is an evanescent wave, the AC thermal dither
may be used to control the effective probe
depth. Higher frequencies of operation reduce
the effective probe depth.
AFM systems for thermal probes
The probes may be operated with an AFM system. The thermal information from the probes
was fed to a circuit module such as the one
described above, which in return interfacedwith an AFM controller (Figure 2A). In thesemeasurments the probe was operated in contact mode by scanning a thermal probe tip
across the sample and making measurements
at discrete points. Thermal probes operated incontact mode show improved performance.
By contrast, operation in a tapping or noncontact mode has several disadvantages. First,
the temperature sensitivity of the probe iscompromised because of the large thermal
Figure 3:
AFM images taken without Z-direction feedback.
(A) Scans of a developed UV6 photoresist. The photoresist pattern is
350-nm thick and 500-nm wide.
Reprinted from [1] with permission.
(B) Map of thermal conductance of adeveloped PMMA photoresist on a 4inch silicon wafer. The photoresist pattern was 240-nm thick and 200-nm
wide with a pitch of 400 nm.
Reprinted from [22] with permission.

STHM PROBES
resistance of the air gap. Second, spatial resolution is reduced because the effective sensing
area is enlarged as the distance between thesensor and the sample increases. Third, highstiffness in the probe is required which may
cause damage to soft samples. The use of polyimide probes eliminates these problems.
Moving on from the original approach, a
simpler system has been devised (Figure 2B),
which obtains only thermal information anddoes not require Z-axis feedback. The highcompliance of the probe allows scans of samples with large topographic variations. An X-Ystage controls the position of the probe while
an interface circuit is used between the dataacquisition computer and the thermal probe.
A simple construction is enabled by eliminating Z-axis actuation and the hardware that isneeded for it, such as photodetectors, lasers,
and other electronics. An additional advantage is that the probes can be arrayed forhigh-throughput
large-areascanning(Figure 1C).

Performance

Wollaston wire probe

Polyimide probe

Tip diameter

1 µm<100 nm

Topographical resolution

NA

<1 nm

Temperature resolution

2.5 K<10 mK-1

Thermal conductance<0.23 µW K

<3 pW K-1

Normal spring constant

1-5 N m-1

0.1 N m-1

Table 1:Comparison of characteristics of a Wollaston wire probe [7] and the polyimide thermal probe.
Figure 4:(A) Schematic of a glass substrate with
50-nm thick Cr lines covered by 5 µm of
photoresist.
(B) An AFM scan shows very little
topographical variation.
(C) The Cr lines are clearly visible with athermal probe scan. Reprinted from [15]with permission.

R E S U LT S A N D D I S C U S S I O N
SPM scans
Figure 3 contains scan images obtained without contact force feedback control using thesystem described above and depicted in Figure
2B. Scans of a developed Shipley UV-6 deep
ultraviolet photoresist made without Z-direction feedback are shown in Figure 3A. The
photoresist pattern was 350 nm thick and 500
nm wide. Comparing the line profiles with andwithout Z-direction feedback, the with-feedback operation provided higher signal-tonoise ratios. The fluctuation of the tip-sample
contact area was larger without feedback. Figure 3B shows a thermal conductance map ofdeveloped polymethylmethacrylate (PMMA)on a four-inch silicon wafer. The photoresist
pattern was 240-nm thick and 200-nm widewith a pitch of 400 nm. The scan results
showed that the thermal probe can provide aspatial resolution better than 200 nm without
contact-force feedback control [22].
Subsurface imaging capability is very usefulfor measuring semiconductor devices wheremultiple layers are present and the final IC iscoated with a passivation layer. Thermal
images showing metal lines through a passivation layer were obtained. Results demonstrating the subsurface imaging capability ofthe thermal probe are shown in Figure 4. A
sample containing 50-nm thick chromium lines
on a glass substrate was coated with a 5-µm
thick planarized photoresist, which had a thermal resistivity of 0.193 W m-1 K-1 (Figure 4A). A
topographical image of the sample showedthat the photoresist was uniform and theunderlying Cr layers were not detected (Figure
4B). The thermal image, on the other hand,clearly detected the underlying Cr layers. The
variation in thermal resistance amounted to a
1% change in 1.0  1010 K W-1 and the signalto-noise ratio was in excess of 15, as shown in
Figure 4C [15].
Figure 5 illustrates another example of subsurface mapping. The sample contained
90-nm wide Cu lines covered with 250 to 300-

nm wide and 125-nm thick natural oxide. An
SEM picture of the trench before Cu deposition is shown in Figure 4A. An SEM picture ofa Cu line is shown in Figure 5B. An AFM scan of
the Cu lines covered with a thick layer of oxide
is shown in Figure 5C. Figures 5D and 5E illustrate overlays of thermal scans superimposedon topographical scans and show <300 nm discontinuities in thermal conductance maps
occurring under the natural oxide. These discontinuities were not visible topographically.
The images revealed subsurface information
about the Cu lines, which potentially may berelated to Cu voids. The current through theprobe was 12 mA and the nominal probe resistance was 26 . The area scanned was 6  6µm2 and the scan rate was set at 1 Hz for Fig.
5D and 1.4 Hz for Fig. 5E.
Simulations
Numerical simulations were performed inorder to demonstrate the feasibility of detecting voids in copper lines and to enhance
understanding of the quality and detectabilityof the thermal conductance signal. Thermalscans over copper lines having various types ofvoids with different sizes and locations were
simulated using the Femlab 3 Multiphysics
Modeling package by Comsol [23]. Each simulation yielded maps of the change in thermal

conductance as an area the size of the probetip heated the surface of the simulated copperlines.
The simulated structure was based on Intel’s
130-nm process [24]. The structure consistedof a 400-nm thick lower layer of field oxide,
the bottom of which was held at 0oC. The top
layer was a dielectric, 280-nm thick, 1-µm
wide, and 1-µm long, with a copper feature,
150-nm wide, 150-nm long, and 280-nm thick,located at the center of the dielectric. A void
was simulated in the copper layer and its location and size were varied. A cylindrical thermalprobe with 50-nm diameter resided on top of
the copper and the probe temperature washeld at 100oC at the point of contact with thecopper.
Simulations of features with and without
voids were performed and the heat flux out of
the thermal probe was calculated. The number of bits of resolution in the sensed signal
required in order to detect a particular void
was determined from the difference in thermal resistance with and without a void for aparticular depth. The simulations confirmedthat voids in closer proximity to the surface
and larger voids were easier to detect. The
simulations also indicated that the minimum
number of bits of resolution required todetect most voids was within the performance

M I C R O S C O P Y A N D A N A LY S I S S P M S U P P L E M E N T • M A R C H 2 0 0 6

S13

levels of the scanning thermal microscopy system. For example, a 100-nm diameter void at
140-nm depth would require 8-bit resolution
to be detected, while a 140-nm diameter voidat the same depth would require 6 bits, and a
40-nm diameter void would require 12 bits. In
Figure 6, the X axis represents the ratio of void
depth to void diameter and the Y axis the bits
required to detect a particular void. The twolines represent 70-nm and 140-nm depths. At
a fixed depth, the bits required to detect avoid decrease as the void size increases.

CONCLUSIONSThis article has reviewed a surface micromachined scanning thermal probe that uses polyimide as the structural material and anembedded thin-film metal resistor as the sensing element. The probe tip offers a diameter<100 nm, a topographical resolution of <1
nm, a spring constant of <0.1 N m-1, and canbe used to detect thermal conductancechanges of the order of 3 pW K-1.
The probe was used to map the spatialchange in thermal conductance of various test
samples. Surface and subsurface characteristics were observed. In particular, subsurface
thermal conductance variations in copperlines have been observed. Past simulations
have predicted the feasibility of copper-void
detection by these probes. This work reports
the first experimental demonstration of thermal conductance variations in copper lines
using samples provided by Sematech.

REFERENCES
1. Li, M-H., Gianchandani, Y. B. Sensors and Actuators A 104:
236–245, 2003.
2. Li, M-H. et al. IEEE/ASME Journal of Micro-electromechanical Systems 10(1):3-9, 2001.
3. Ocola, L. E. et al. J. Vac. Sci. Technol. B, 14(6):3974-3979,
1996.
4. Hammiche, A. et al. Meas. Sci. Technol., 7:142, 1996.
5. Luo, K. et al. Appl. Phys. Lett. 68:325, 1996.
6. Lai, J. et al. IEEE Electron Dev. Lett. 16:312, 1995.
7. ThermoMicroscopes, probe model #1615-00, now part of
Veeco Probes, probe model #1615-00/1610-00/CLST-NOMB.
8. Hammiche, A. et al. Applied Spectroscopy 53(7):810-815,
1999.
9. Vettiger, P. et al. IBM J. Res. Develop. 44(3):323-340, 2000.
10. Lerchner, J. et al. Sensors and Actuators B 70:57-66, 2000.
11. Majumdar A. Scanning thermal microscopy. Ann. Rev.
Mater. Sci. 29: 505-585, 1999.
12. Williams, C. C., Wickramasinghe, H. K. Appl. Phys.
Lett.49:1587, 1986.
13. Gianchandani Y., Najafi, K. IEEE Transactions on Electron
Devices 44(11):1857-1868, 1997.
14. Lee, J-H. et al. International Workshop on Thermal
Investigations of ICs and Systems (THERMINIC 2002),
Madrid, Spain, October 2002, pp. 111-116.
15. Lee, J-H., Gianchandani, Y. B. Review of Scientific
Instruments 75(5):1222-1227, 2004.
16. Basu, A. S. et al. J. Vac. Sci. Technol. B, 22(6): 3217-3220,
2004.
17. Hendarto, E. et al. Proceedings 43rd Annual IEEE
International Reliability Physics Symposium, pp. 294-299,
2005.
18. Basu, A. S., and Gianchandani, Y.B. Proceedings IEEE
International Conference on MicroElectroMechanical
Systems, Miami Beach, FL, pp 666-669, 2005.

S14 M

Figure 5:(A) SEM image of cross-section of Cu line in 60-nm dense low-k dielectric film above porous low-k. Courtesy of Sematech.
(B) SEM image of trench preparation before Cu deposition. Courtesy of Sematech.
(C) AFM topographical image of Cu lines under a natural oxide 300-nm wide and 125-nm thick.
(D,E) Overlay thermal scans superimposed on topographical scans with <300 nm discontinuities in thermal conductance maps. These discontinuities
occur under the natural oxide and are not visible topographically. The area scanned was 6 x 6 µm2 and the scan rate was set at 1 Hz (D) or 1.4 Hz (E).

Figure 6:
The number of bits of resolution necessary to detect a void at a given depth is
proportional to the ratio of the void
depth to the void diameter. These simulations assume that the voids exist in a
150 nm x 150 nm x 280 nm feature of
the copper, based on simulations
reported in [23].

19. Basu, A. S., Gianchandani, Y. B. Presented at the 13th
International Conference on Solid-State Sensors, Actuators,
and Microsystems, Seoul, Korea, 2005.
20. McNamara, S. et al. J. Micromech. Microeng. 15:237-243,
2005.
21. Gaitas, A., Gianchandani, Y. B. An experimental study ofcontact mode scan speed constraints for polyimide
cantilever probes. To be published in Ultramicroscopy,
2006.
22. Li, M-H. Surface Micromachined Polyimide Scanning

I C R O S C O P Y A N D A N A LY S I S S P M S U P P L E M E N T • M A R C H 2 0 0 6

Thermocouple and Bolometer Probes. PhD Thesis,
University of Wisconsin, Madison, January 2001.
23. McNamara, S., Gianchandani, Y. B. Systems and Methods
for Thin Film Thermal Diagnostics with Scanning Thermal
Microstructures. USA Provisional Patent, Application No.
unassigned, Assignee: PicoCal Inc., Filed: September 2005.
24. Intel Technology Journal 6(2), May 16, 2002.
©2006 John Wiley & Sons, LtdSensors and Actuators A 104 (2003) 236–245

Applications of a low contact force polyimide shank bolometerprobe for chemical and biological diagnostics
M.-H. Li, Y.B. Gianchandani*
Department of Electrical and Computer Engineering, Center for NanoTechnology, University of Wisconsin, Madison, WI, USA

Abstract
This paper reports on the detection of nano-scale chemical variations in photosensitive polymers and biological variations in cancerous
tumor cells that have been accomplished for the first time using scanning thermal probes that we have developed. It also reports on changes
that have been made over older versions of this probe to help achieve these capabilities. The probe is fabricated by a 6-mask surface
micromachining process using polyimide as the structural material. A unique assembly sequence that involves flipping over the probe
accommodates the future integration of circuitry on the same substrate. The probe has measured spring constant 0.082 N/m for a
250 mm  50 mm  3 mm probe. It offers a tip diameter of 50 nm. Probes are used to study exposed but undeveloped photoresist latentimages in features of 70 nm, the acid diffusion in chemically amplified photoresist during post exposure bake, and HeLa cells. Lateral spatial
resolution of <50 nm, topographic resolution of <1 nm and thermal resolution of <1.2 mK are demonstrated. Wet scanning capability, which
widens the possibility of biochemical applications, is also demonstrated for the first time. The structure, fabrication, and assembly of the probe
and the interface circuit used for these experiments are described.
# 2003 Elsevier Science B.V. All rights reserved.
Keywords: Polyimide shank; Bolometer; Chemical diagnostics

1. Introduction
Scanning thermal microscopy has been explored for anumber of applications, including high resolution temperature mapping, topographical mapping, data storage, photothermal absorption spectroscopy, and subsurface imaging[1–4]. Temperature sensing methods used for scanningprobes have included thermocouples, Schottky diodes, bolometers, and bimorphs [1–12]. A bolometer-type element
which senses temperature by fractional changes in theelectrical resistance provides certain advantages for microcalorimetry applications. In particular, this resistor can beused not only to sense temperature, but to supply heat if
adequate current is passed through it. Since the tip temperature is ultimately influenced by the heat flow between
the tip and the sample, variations in thermal conductanceacross the sample can be mapped by this probe. In essence,the device can be used as a spatially localized microcalorimeter [8,13].
We are developing ultra compliant thermal probes (withspring constant <0.1 N/m) for critical applications in ULSI*Corresponding author. Present address: 1301 Beal Avenue, UM Ann
Arbor, MI 48109-2122, USA. Tel.: þ1-734-615-6407.
E-mail address: yogesh@umich.edu (Y.B. Gianchandani).

lithography research. These include, specifically, mapping
the latent image of exposed but undeveloped photoresist(PR) to measure photo-acid generation and diffusion independently from the developing step [14]. Since they offer
sub-surface mapping capability, thermal probes also facilitate studies of intra-cellular features in bio-related research.
To fulfill our need for these applications, probes must have a
low spring constant to prevent damaging the soft materials,
and provide spatial resolution <100 nm. In addition, topermit scanning in aqueous environments, complete electrical insulation is necessary. Wet scans are particularly
challenging because of enhanced parasitic thermal losses,
the need for complete electrical insulation, and the impact of
surface tension on the ultra compliant probes. These requirements can not be fulfilled by using the commercially available wire probe which is made of bent bare wires, and has ahigh spring constant (5 N/m), limited spatial resolution, andno particular isolation [15].
We have previously reported thermocouple or bolometerprobes fabricated by 6- to 7-mask surface micromachining
processes using polyimide as the shank material, and theapplication of these probes for temperature mapping, subsurface imaging, and the measurement of glass transition
temperature in photoresists [8,9]. This paper reports on
applying these probes to ULSI lithography research,

0924-4247/03/$ – see front matter # 2003 Elsevier Science B.V. All rights reserved.
doi:10.1016/S0924-4247(03)00026-8

M.-H. Li, Y.B. Gianchandani / Sensors and Actuators A 104 (2003) 236–245

particularly for mapping the latent image of exposed but
undeveloped PR to measure photo-acid generation (PAG)
and diffusion independently.1 Wet scanning capability,
which widens the possibility of biochemical applications,is also demonstrated for the first time. This paper also
describes changes that have been made to older versions[8,9] of this probe to help achieve these capabilities. In thefollowing text, Section 2 describes the device structure andfabrication process, Section 3 describes the measurement
theory, and Section 4 describes experimental results thathave been obtained.

2. Structure and fabrication
The basic structure of the probe is similar to that reported
in [8,9], with a thin film bolometer sandwiched between twolayers of polyimide, forming a cantilever. At one end of thecantilever the metal thin film protrudes through an opening
in the lower polyimide layer, where it is molded into apyramidal tip by a notch that was anisotropically wet-etched
into the substrate. The tip and a portion of the probe shank
are then released from the substrate by etching an underlying
sacrificial layer. The released length is then folded over toextend past the die edge for clearance and held in place by anadhesive (Fig. 1). Typical dimensions of the probes after
assembly are 250 mm length, 50 mm width, and 3 mm thickness with Cr/Au (200/2000 Å) for the tip and lead, which
provides bolometer resistance of about 60 O. This flip-overmethod for providing the tip clearance exploits the mechanical flexibility of polyimide, and avoids the dissolution of thesubstrate material from underneath the tip. The polyimide
shank offers both high mechanical compliance and highthermal isolation which are important for scanning soft
samples with low thermal conductivity, such as PR andpolymers.
The present manifestation of the probe (Fig. 2) has anadditional thin evaporated film of gold (Cr/Au: 200/5000 Å)that serves as an AFM mirror and also permits a thermocompression bond to hold the probe after the flip-over step,
eliminating the use of epoxy. This method retains theflatness of the probe and significantly increases yield. The
released probe was manually flipped over, with the two goldpads (Fig. 2a) held together by using micromanipulators on a
hot plate and slowly increasing hot plate temperature to170 8C. The bonding strength is strong enough. No probeshank bounce back, cracking or breakage has been observedin the many 10s of samples that have been assembled in thismanner. Other materials such as using partially curried
photosensitive polyimide (PI2721TM) or indium were also
evaluated, but all show some drawbacks. The partiallycurried polyimide can be attacked by photoresist stripper,
and the indium is attacked by the prolonged HF etching torelease the probe tip. Other self-assembly approaches such
1

Portions of this paper will appear in [12].

237Fig. 1. Schematic of the ultracompliant polyimide thermal probe.

as using surface tension forces [16] and a bimorph for stressmismatch were also studied, but all fail to retain the flatnessof the flipped-over probe due to its fundamental limitation.
Typical dimensions of the probes after assembly are 250 mm
length, 50 mm width, and 3 mm thickness with Cr/Au (200/2000 Å) for the tip and lead, which have probe resistanceabout 60 O. The probe shank length can be easily adjusted
by moving the location of the gold bond pads.
Another critical process step that has been added permits
reduction of the tip diameter to about 50 nm by oxide sharpening the tip notch using the phenomena of the non-uniform

Fig. 2. (a) A scanning thermal probe showing the location of mirror andgold segments for thermocompression bond; (b) a 250 mm long probeflipped over the die edge and held down with a gold thermocompression
bond.

238

M.-H. Li, Y.B. Gianchandani / Sensors and Actuators A 104 (2003) 236–245

Fig. 5. A mounted scanning thermal probe with the base covered with apolyimide (PI2613TM) layer to make it suitable for working in aqueous
environments.

Fig. 3. Close-up of the sharpening tip showing the tip diameter is about
50 nm.

oxide growth [17]. A 4000 Å thick oxide is grown at 950 8C
prior to depositing the sacrificial layer used for releasing theprobe shank from the silicon substrate, which generates a tip
diameter of about 50 nm as shown in Fig. 3.
Since the probe length is only about 300 mm, and thewafer thickness of a 300 wafer is approximately 500 mm, a
small extrusion at the die edge caused by the curvature of thedicing blade can block the laser beam (Fig. 4a). To provide aclear die edge for laser pickup, the probe wafer is bonded to adummy wafer using photoresist, with the front side of thewafer covered by a thin photoresist film to protect the probes

during dicing, and has both wafers diced together as shownin Fig. 4b. A 300 wafer can generate about one thousand dieswith two probes per die.
For operation in aqueous environments, the bond pads andbond wires are covered with a thin layer of polyimide(PI2613TM), leaving the scanning tip as the only exposed
metallic surface (Fig. 5). The polyimide probe provides highthermal probe shank resistance, low spring constant, and an
integrated tip. These advantages make it suitable to study
soft materials such as chemical amplified photoresist for
deep-UV lithography and HeLa tumor cells.

3. Measurement theory
3.1. Interface circuit
Fig. 6 shows an interface circuit used to sense the probe
resistance change as it scans across the sample surface. It
includes a Wheatstone bridge, two gain stages providing
combined amplification of 104, and a low-pass filter with acutoff frequency of 1 kHz to reduce noise. The output
voltage (Vout) is plotted for the thermal image.
When the probe resistance change (DRP ) is much smaller
than the probe resistance (RP ), as in the case of thermal

Fig. 4. (a) Extrusion at die edge blocks the laser; (b) with two wafers
bonded and diced together to provide a clear die edge after dicing, whichallows laser pickup.

Fig. 6. An interface circuit for sensing the probe resistance change.

M.-H. Li, Y.B. Gianchandani / Sensors and Actuators A 104 (2003) 236–245

conductance contrast mapping, the output voltage change(DVout) can be expressed as:
DVout ﬃ 104  Vs  DRP

R1
ðR1 þ RP Þ2(1)

where Vs is the voltage applied to the Wheatstone bridge,
and R1 is a resistance of the Wheatstone bridge as shown in
Fig. 6. The supplied power change (DPp) of the probe
resistor due to the probe resistance change (DRP) is:
Vp2 DRP ðR1  RP Þ
DPp ﬃ
(2)
RP RP ðR1 þ RP Þ
According to Eqs. (1) and (2), the output voltage change(DVout) is linearly proportional to the supplied power change(DPp). Since the supplied power change (DPp) is equal to the
conductive heat loss between the tip and sample, which is
proportional to change in the thermal conductance of thesample, the output voltage change (DVout) represents thethermal conductance contrast of sample.
The probe tip temperature change (DTP) can be calculated
from the output voltage change (DVout), which is:
DTP ﬃ

DVout ðR1 þ RP Þ2
ð104 Vs R1 RP TCRÞ(3)

The temperature coefficient of resistance (TCR) is
3640 ppm/K for Cr/Au (200/2000 Å) thin film. A DVout of
100 mV corresponds to a DTP of 5.657 mK calculated using
the voltage and resistance values shown in Fig. 6. The fullscale DTP is indicated for all thermal scans presented in thispaper. Before a scan, this circuit is adjusted to balance theWheatstone bridge with the probe in contact with the sample
by adjusting the control resistor (Rc) to make the resistanceratio of Rc/R2 equal to RP/R1 so that the output voltage is as
close as possible to 0 V in order to make full use of theavailable dynamic range.
3.2. Thermal conductance contrast mapping
When the probe is operated at a constant tip temperature(TP), and with the sample thickness sufficiently thick compared with the tip diameter, the heat loss (Ps) to the sample
can be expressed as [4]:Ps ¼

2pks aðTP  T0 Þ
1 þ ð2pks aRg Þ(4)The heat loss depends on the contact radius a, the ambient
temperature T0, and the tip-sample thermal contact resistance Rg, as well as the sample conductivity ks. Assumingthat the contact area and the tip-sample contact resistance do
not change during a scan, the heat loss is then directly
proportional to the sample thermal conductivity; i.e. for theimage mapped to depend primarily on the sample thermal
conductivity, it is necessary that 2pks aRg ! 1. This requirement can be satisfied for a commercially available wireprobe with tip diameter in the range of 1 mm when scanning239

samples with low thermal conductivity. For the polyimide
probe, which has tip diameter 50 nm, this constraint issatisfied for virtually any case. Note that under this constraint the thermal probe can even be used to directly
measure the sample thermal conductivity, since the supplied
power will be directly proportional to it [18,19].
For the case of scanning an ultra-thin photoresist patterned on a silicon wafer with thickness comparable to thescan tip diameter, the heat transfer (Ps) between the probe tip
and substrate can be modeled as heat flow through acylinder:Ps ¼

ðTP  T0 ÞA0 ks
H(5)where TP is the probe tip temperature, A0 the tip-sample
contact area, ks the thermal conductivity of photoresist, andH the photoresist thickness. The silicon substrate is a large
heat sink, effectively with a fixed temperature T0. The
thermal conductance image obtained from Vout, which
depends on the heat flow (Ps), contains both topographic
image and thermal conductivity information. To separate theinfluence of topographic variation from (Vout), both of the
topographic and thermal images should be obtained simultaneously. The topographic image is produced by monitoring the deflection of the probe cantilever as in a conventional
AFM by reflecting a laser beam from a mirror placed on theend of cantilever.

4. Measurement results
4.1. Spring constant and spatial resolution
The spring constant (k) is calculated by measuring thethermal fluctuations of the cantilever in the range of 5–
25 kHz with the tip suspended 1 mm away from the sample
surface using a built-in function in the Topometrix system[20–23]. The spring constant is given by:
k¼

akb T
Pn

(6)

where a is a correction factor ( 0.82), kb the Boltzmann
constant, T the ambient room temperature, and Pn the area ofthe power spectrum of the thermal fluctuations of thecantilever. The measured spring constant is 0.082 N/m fora 250 mm  50 mm  3 mm probe. Since the thermal fluctuations of the cantilever is measured by monitoring the tip
motion using the optical-level method of an AFM, and only
the fundamental mode of the thermal fluctuation of thecantilever is detected, the correction factor a is 0.82
[22,23]. If all the thermal fluctuation modes are detected,
the value of the correction factor a will be 4/3. Anothermeasurement is used to verify the linearity of the forcedeflection response of the probe (Fig. 7). The force conversion is determined from the sensor response and the spring
constant.

240

M.-H. Li, Y.B. Gianchandani / Sensors and Actuators A 104 (2003) 236–245

Fig. 7. The measured cantilever deflection versus the piezo displacementof a 250 mm  50 mm  3 mm probe. The cantilever deflection isrepresented in current, since it is determined by the photosensor response(PSPD).

Fig. 8 shows the scan results for same photoresist sample
with z-direction feedback. The topographic image whichuses the laser, and the thermal image which uses the resistor
were obtained at the same time. The photoresist pattern is
350 nm thick, with trench of 500 nm wide in 2 mm pitch.
The low spring constant allows scanning soft material suchas photoresist pattern with feature size of 500 nm easily
even without z-direction feedback (Fig. 9). The output
voltage drops as the probe scanned across the higher
thermal conductivity material (silicon), because the heatloss from the tip to sample increases, which cools down theFig. 9. Thermal image of the same photoresist sample of Fig. 8. No zdirection feedback.

tip temperature, and the corresponding probe resistance. It
should be noted that in the absence of feedback control,
topographic variations on the sample surface would cause
variations in the tip-sample contact force which can potentially affect the image.
Fig. 10 shows the topographic and thermal images of
exposed but undeveloped contact hole patterns in Shipley
UV113TM photoresist patterned with critical dimension of
70 nm with 200 nm pitch. The images were obtained withscan rate of 0.75 mm/s and resolution of 400 lines. The thermalprobe and interface circuit are sensitive enough to detect a
photoresist thickness change only 4 nm, which corresponds toa tip temperature change as low as 1.13 mK. Comparing the
topographic and thermal images of another photoresist sample shown in Fig. 11, the scan results clearly indicate the probe
has spatial resolution of <50 nm, which is comparable to thesmallest currently reported. The topographic resolution is<1 nm.
4.2. Photoresist chemistry
The positive tone chemically amplified photoresist
UV6TM by Shipley, which is suitable for ultra-narrow linewidths ULSI lithography research, behaves as shown in
Fig. 12 [24,25]. Unlike standard PR and PMMA, a photoacid generated by exposure permits catalyzed thermolysis of
the backbone polymer during the post exposure bake (PEB),
which changes the solubility of the exposed regions of theFig. 8. Topographic (top) and thermal (bottom) images of developed
UV6TM photoresist sample with thickness of 350 nm obtained with zdirection feedback.

Fig. 10. Topographic (top) and thermal (bottom) images of exposed but
undeveloped UV113TM photoresist contact holes of 70 nm.

M.-H. Li, Y.B. Gianchandani / Sensors and Actuators A 104 (2003) 236–245

Fig. 11. Topographic (top) and thermal (bottom) images of partial
developed UV113TM photoresist sample show the thermal probe has
spatial resolution of sub-50 nm.

resist and releases isobutylene. The photoresist thickness
decreases in exposed areas where the released isobutylene isevaporated during PEB. Topographic variations and thermal
conductance variations due to the thermolysis of the backbone are mapped simultaneously by using the thermal probe.
Fig. 13 shows the scan results of a 500 nm thick exposed but
undeveloped UV6TM on a 400 silicon wafer. The sample was
exposed using a Leica Cambridge 10.5 EBMF 30 kVelectron
beam lithography system with charge density of 9 mC/cm2,
and then post exposure baked at 130 8C for 4 min. As discussed previously, in chemically amplified photoresist, theFig. 12. The mechanism of chemically amplified photoresist UV6TM. PAG
acid deprotects the backbone during PEB for subsequent dissolution in thedeveloper.

241

Fig. 13. Both of topographic and thermal images of exposed but
undeveloped photoresist-UV6TM of 500 nm thick on 400 Si wafer obtained
simultaneously. Sample was exposed by e-beam with charge density of
9 mC/cm2, and then post exposure baked at 130 8C for 4 min.

photoresist backbone is cleaved during PEB with an accompanying loss in free volume due to the releasing of isobutylene in the exposed area. The resulting change inthickness combined with the chemical change causes theoutput voltage to drop as shown in the thermal image. The‘‘v’’ shape profile shown in the exposed area is due to thedose distribution of the e-beam source [14]. The small
lithography defects shown both on the topographic andthermal images clearly indicate the high spatial resolution
and sensitivity of thermal probe.
As discussed previously, a post exposure bake is usuallyrequired to activate the catalytic reactions. During PEB, acidgenerated by exposure diffuses and can cause pattern sizechanges [14,26,27]. It is therefore important to control the
PEB conditions to suppress the acid diffusion for the criticaldimension control of nanofabrication when using chemical
amplification resist systems. Fig. 14 shows the topographic
and thermal line scans of a trench in exposed but undeveloped Shipley UV6TM photoresist with different duration of
PEB times. As the duration of the 130 8C PEB increases
from 45 to 360 s, both the topographic height change (Dh)and DVout increase. However, the most significant change in
Dh occurs in the 45–90 s period, whereas the most significant change in DVout occurs in the 180–360 s period. As
noted above, the Dh is due to the release of isobutylene anddepends on the acid concentration and the reaction rate ofphotoresist backbone deprotection. The ‘‘v’’ shape profiles
of exposed regions are due to the Gaussian distribution of
the e-beam source of dose profile, and hence, the acid242

M.-H. Li, Y.B. Gianchandani / Sensors and Actuators A 104 (2003) 236–245

Fig. 14. Topographic (left) and thermal (right) line profiles across the exposed photoresist trench with sample of different post exposure bake time. Both of
the topographic height change (Dh) and thermal voltage change (DV) increase as the PEB time increases.

concentration [14]. As the PEB time increases, the ‘‘v’’
shape profile widens due to the acid diffusion. However,since the acid diffusion constant, which depends on theprocess conditions [28], is only about of 50 nm2/s for
UV6TM [26], this change is very small ( 10 nm) [29],particularly when compared to the 500 nm width of the
exposed portion. Since the recommended PEB condition for
130 8C is 90 s, the longer PEB times may deplete thephotoresist backbone, minimizing subsequent changes in
topography. In contrast, other chemical changes may lead to
the DVout increase during the 180–360 s period.
4.3. Biological analysis
A eukaryotic cell contains many membrane-limited compartments knows as organelles (mitochondrion, lysosome,etc.) separated by the cytoplasm, and a nucleus bounded by adouble membrane. The organelles have different cellularfunctions, and have slightly different thermal conductivity

compared with that of cytoplasm. In addition, the temperatures of some organelles are expected to be different. For
example, the mitochondria are the energy generators of thecell. Therefore, the temperature at the mitochondria should
be higher. The thermal probes are capable of mapping both
thermal conductance and temperature variations. Since subsurface variations in these quantities can be detected while
the topography is being mapped as well, the thermal probes
can potentially be useful tools for studying cellular activity
under different conditions. The low spring constant(0.082 N/m), the high thermal isolation, and high spatial
resolution (<50 nm) of the polyimide probes are important
assets in this kind of application. Here, we demonstrated theusage of applying the thermal probe to map the thermal
conductance contrast of fixed HeLa tumor cells, which arewidely used for studying cellular functions [30]. These cells
typically have a diameter of about 30 mm, with a very large
nucleus. The optical, topographic and thermal images of thenucleus of a HeLa cell fixed to a glass slide while undergoingM.-H. Li, Y.B. Gianchandani / Sensors and Actuators A 104 (2003) 236–245

243

Fig. 16. Area (upper) and line scan (lower) thermal images of metal stripes
on a Si substrate obtained without z-direction feedback with the probe andsample immersed in water.

Fig. 15. The optical, topographic and thermal images of the nucleus of a
HeLa cell fixed to a glass slide while undergoing mitosis. The opticalimage was obtained from transmission microscopy. The topographic andthermal images obtained from thermal probes are almost identical since theprobe tip heat loss due to topographic change is dominant.

mitosis are compared in Fig. 15. The optical image wasobtained using transmission microscope (Axiovert 100TV)
with samples in the microscope immersion oil. Since thetopographic variation in such a sample is much larger than
the thermal conductivity difference of the organelles within
it, the thermal image is expected to be similar to the
topography map. The distinctions between these images
are evidence of variations in subsurface conductivity.

tension forces, and to provide a uniform surrounding environment. The spatial resolution and temperature sensitivity
degrade due to the parasitic thermal liquid conductance
between the probe shank and sample. Since the liquid( 1 W/m K) has much higher thermal conductivity thanthat of air (2:6  102 W/m K), the heat transfer between
the probe shank and sample substrate can no longer beneglected.
Fig. 16 presents area and linear thermal scans of metallines on a Si substrate in an aqueous environment. The
sample was 5 mm wide thin film chromel (metal A:
300 nm thick), and Ti/Pt (metal B: 20/100 nm thick) patterned on a Si substrate and isolated from it by a 0.75 mm
thick silicon dioxide layer. The variation in metal films isclearly detectable despite the fact that these scans were
performed without z-axis feedback. This is possible becauseof the ultra compliant nature and high thermal isolation
offered by the probe. We believe this is the first scanningthermal probe that can work in aqueous environment. With
the ability of scanning in aqueous environments, theseprobes can potentially facilitate studies of cellular featuresand functions of living cells in real time to provide otherinformation not provided by AFM, such as the temperature
distribution in a cell that is undergoing mitosis.

4.4. Scanning in aqueous environments
4.5. Performance analysis
Aqueous scans are particularly challenging because ofenhanced parasitic thermal losses between the probe shankand substrate, the need for complete electrical insulation,and the impact of surface tension on the ultra compliant
probes. The probe and mounting platform must be immersedin the liquid along with the sample to circumvent the surface

Table 1 shows the current performance of polyimide
thermal probe with the interface circuit. The probe has tip
diameter about 50 nm, and spatial resolution of sub-50 nm
as shown in Figs. 4 and 11 respectively. According to Fig. 14,
the thermal probe can easily detect output voltage changes

244

M.-H. Li, Y.B. Gianchandani / Sensors and Actuators A 104 (2003) 236–245

Table 1
Current performance of polyimide thermal probe with the interface circuit
Tip diameter (nm)Lateral spatial resolution (nm)
Topographic resolution (nm)
Input referred circuit noise (1 kHz BW) (mV)DR resolution (mO)
Tip temperature resolution (mK)
Detectable thermal conductance change (W/K) (1%)
Detectable thermal conductivity change (W/m K) (1%)

50
<50
<1
<2
<0.25
<1.2
1  1011
2  103

lower than 20 mV. Since interface circuit has voltage gain of
104, this indicates the interface circuit can detect input signal
change lower than 2 mV. Calculated using Eqs. (1) and (3),this also indicates the interface circuit can sense 0.25 mO
probe resistance change or 1.2 mK temperature change inthe probe temperature.
Comparing the line profiles of topographic and thermalscan at unexposed area in Fig. 13, it shows the thermal probe
can easy detect photoresist thickness change lower than 1%(5 variation of 500 nm thick). Since the output voltage is
proportional to the thermal conductance between the tip andsilicon substrate, which is ksA0/H as discussed at Eq. (5), it
implies the thermal probe can also detect thermal conductance change lower than 1%, which is 1:09  1011 W/K(1% of ksA0/H) by assuming that the tip-sample contact area
(A0) is 302 p nm2, and the thermal conductivity of photoresist (ks) is comparable to that of PMMA (0.193 W/m K)[2]. By the same argument, the thermal probe can also detect
the thermal conductivity changes lower than 1%, which is
1:93  103 W/m K.

5. Conclusion
This effort has addressed the development and applications of a polyimide shank thermal probe fabricated by a 6mask surface micromachining. These probes are assembled
with the help of a thermocompression bond between thinfilms that greatly improved yield. A modification of thestructure permits operation in aqueous environments. Typical probe dimensions are 250 mm length, 50 mm width, and3 mm thickness. The probe is ultra-compliant with a spring
constant of 0.082 N/m, and can be further reduced by
reducing the probe width and thickness. It can be operated
without z-direction feedback, even when scanning soft
materials.
The probe has a lateral spatial resolution of sub-50 nm,
and a topographical resolution of <1 nm. Combined with theinterface circuit, the probe can offer tip temperature resolution better than 1.2 mK. The probe has been used to scan
exposed but undeveloped photoresist samples, HeLa cells,
and to study the acid diffusion in photoresist during post
exposure bake. A sample scanned with both of probe andsample immersed in water is also presented. These results
suggest the potential usefulness of the polyimide probe as atool for measuring the cellular activity of living cells inaqueous environments.

Acknowledgements
The authors thank Prof. Cerrina and Dr. Leo Ocola forsupporting the photoresist samples, and Prof. Menon and Dr.
Vainauskas for providing HeLa cell samples. This work was
funded in part by the Semiconductor Research Corporation
contract # 98-LP-452.005. The Center for NanoTechnology,
University of Wisconsin-Madison, is supported in part by
DARPA/ONR grant # MDA 972-00-1-0018, and # MDA
972-99-1-0013. The Synchrotron Radiation Center, University of Wisconsin-Madison, at which some of the experimental facilities are located, is operated under NSF award #DMR-0084402.

References[1] H.K. Wickramasinghe, Scanned-Probe Microscopes, Scientific
American, 1989, pp. 98–105.
[2] A. Hammiche, D.J. Hourston, H.M. Pollock, M. Reading, M. Song,Scanning thermal microscopy: subsurface imaging, thermal mappingof polymer blends, and localized calorimetry, J. Vac. Sci. Technol. B
14 (2) (1996) 1486–1491.
[3] P. Vettiger, M. Despont, U. Drechsler, U. Dürig, W. Häberle, M.I.
Lutwyche, H.E. Rothuizen, R. Stutz, R. Widmer, G.K. Binnig, Themillipede-more than one thousand tips for future AFM data storage,
IBM J. Res. Develop. 44 (3) (2000) 323–340.
[4] A. Majumdar, Scanning thermal microscopy, Annu. Rev. Mater. Sci.
29 (1999) 505–585.
[5] Y. Suzuki, Novel microcantilever for scanning thermal imaging
microscopy, Jpn. J. Appl. Phys. Part 2 35 (3A) (1996) L352–L354.
[6] Y.B. Gianchandani, K. Najafi, A silicon micromachined scanningthermal profiler with integrated elements for sensing and actuation,
IEEE Trans. Electron Dev. 44 (11) (1997) 1857–1867.
[7] T. Leinhos, M. Stopka, E. Oesterschulze, Micromachined fabricationof Si cantilevers with Schottky diodes integrated in the tip, Appl.
Phys. A 66 (1998) S65–S69.
[8] M.-H. Li, Y.B. Gianchandani, Microcalorimetry applications of asurface micromachined bolometer-type thermal probe, J. Vac. Sci.
Technol. B 18 (6) (2000) 3600–3603.
[9] M.-H. Li, J.J. Wu, Y.B. Gianchandani, Surface micromachinedpolyimide scanning thermocouple probes, J. Microelectromech. Syst.
10 (1) (2001) 3–9.
[10] D.-W. Lee, T. Ono, T. Abe, M. Esashi, Fabrication of microprobearray with sub-100 nm nano-heater for nanometric thermal imaging
and data storage, in: Proceedings of the 11th International
Conference On Solid-State Sensors and Actuators (Transducers’01), June 2001, pp. 204–207.
[11] L. Shi, O. Kwon, A.C. Miner, A. Majumdar, Design and batch
fabrication of probes for sub-100 nm scanning thermal microscopy, J.
Microelectromech. Syst. 10 (3) (2001) 370–378.
[12] M.-H. Li, J.-H. Lee, F. Cerrina, A.K. Menon, Y.B. Gianchandani,
Chemical and biological diagnostics using fully insulated ultracompliant thermal probes, in: Proceedings of the Hilton Head 2002,
Solid-State Sensor, Actuator, and Microsystems Workshop, 2–6 June
2002.
[13] D. Fryer, P. Nealey, J. de Pablo, Thermal probe measurements of theglass transition temperature for ultrathin polymer films as a functionof thickness, Macromolecules 33 (17) (2000) 6439–6447.

M.-H. Li, Y.B. Gianchandani / Sensors and Actuators A 104 (2003) 236–245[14] L.E. Ocola, D. Fryer, P. Nealey, J. dePablo, F. Cerrina, S. Kämmer,
Latent image formation: nano-scale topography and calorimetricmeasurements in chemical amplified resists, J. Vac. Sci. Technol. B
14 (6) (1996) 3974–3999.
[15] TM Microscopes, http://www.tmmicro.com, Probe Model no. 1615-00.
[16] R.R.A. Syms, Equilibrium of hinged and hingeless structures rotatedusing surface tension forces, J. Microelectromech. Syst. 4 (4) (1995)
177–184.
[17] S. Akamine, C.F. Quate, Low temperature thermal oxidation
sharpening of microcast tips, J. Vac. Sci. Technol. B 10 (5) (1992)
2307–2310.
[18] F. Ruiz, W.D. Sun, F.H. Pollak, C. Venkatraman, Determination of
the thermal conductivity of diamond-like nanocomposite films usinga scanning thermal microscope, Appl. Phys. Lett. 73 (13) (1998)
1802–1804.
[19] D.I. Florescu, V.M. Asnin, F.H. Pollak, A.M. Jones, J.C. Ramer, M.J.
Schurman, I. Ferguson, Thermal conductivity of fully and partiallycoalesced lateral epitaxial overgrown GaN/sapphire (0001) byscanning thermal microscopy, Appl. Phys. Lett. 77 (10) (2000)
1464–1466.
[20] J.L. Hutter, J. Bechhoefer, Calibration of atomic-force microscopetips, Rev. Sci. Instrum. 64 (7) (1993) 1868–1873.
[21] Topometrix Corporation, User’s Manual Supplement, SPMLabVersion 3.06, 1995, pp. 2–19s.

245[22] J. Bechhoefer, J.L. Hutter, unpublished.
[23] H.-J. Butt, M. Jaschke, Calculation of thermal noise in atomic-force
microscopy, Nanotechnology 6 (1995) 1–7.
[24] R.D. Allen, W.E. Conley, R.R. Kunz, Deep-UV resist technology, in:P. Rai-Choudhury (Ed.), Handbook of Microlithography, Micromachining and Microfabrication, vol. 1, Microlithography, SPIE,
Bellingham, Washington, 1997.
[25] H. Ito, Chemically amplified resists: past, present, and future, SPIE
3678 (1999) 2–12.
[26] D. Kang, E.K. Pavelchek, C. Swible-Keane, The accuracy of current
model descriptions of a DUV photoresist, SPIE 3678 (1999)
877–890.
[27] T. Yoshimura, T. Nakayama, S. Okazaki, Acid-diffusion effect on
nanofabrication in chemical amplification resist, J. Vac. Sci. Technol.
B 10 (6) (1992) 2615–2619.
[28] T. Itani, H. Yoshino, S. Hashimoto, M. Yamana, N. Samoto,
K. Kasama, A study of acid diffusion in chemically amplified deep ultraviolet resist, J. Vac. Sci. Technol. B 14 (6) (1996)
4226–4228.
[29] T.H. Fedynyshyn, J.W. Thackeray, J.H. Georger, M.D. Denison,
Effect of acid diffusion on performance in positive deep ultraviolet
resists, J. Vac. Sci. Technol. B 12 (6) (1994) 3888–3894.
[30] R.L. Warters, O.L. Stone, Histone protein and DNA synthesis in
HeLa cells after thermal shock, J. Cell. Phys. 118 (1984) 153–160.

化学品本部機能材料部第一課〒141-0032 東京都品川区大崎1-2-2 アートヴィレッジ大崎セントラルタワー
Tel: 03-5435-6515 Fax: 03-5435-0071
Web-site: http://www.tomo-e.co.jp E-mail: akobayashi@tomo-e.co.jp
nanotech@tomo-e.co.jp