3D Trajectories, Diffusion, and Interaction

Energies of Ceria Particles on Glass Surfaces

by

Akshay Gowda,1 Jihoon Seo,1 Panart Khajornrungruang,2 Satomi Hamada,3 S.V. Babu1,*

1Center for Advanced Materials Processing, Clarkson University, Potsdam, USA.2Department of Mechanical Information Science and Technology, Kyushu Institute of Technology,

Iizuka-shi, Fukuoka, Japan3Technologies, R&D Division, EBARA Corporation, Fujisawa-shi, Kanagawa, Japan

2

▪ Introduction

▪ Principle of evanescent wave microscopy

▪ Results

▪ Conclusions

▪ Acknowledgements

❖2D and 3D trajectories, Diffusion coefficients and Interaction potentials

❖Cleaning of ceria particles adsorbed at pH 3, pH 5 and pH 7

-Ce-OH + -Si-OH ↔ -Ce-O-Si- + H2O

3J. Seo, J. W. Lee, J. Moon, W. Sigmund, and U. Paik, ACS Appl. Mater. Interfaces, 6, 7388 (2014)

L. M. Cook, J. Non-Cryst. Solids, 120, 152 (1990)

A

B

C

❖ Ceria based slurries in STICMP – high oxide polish rate

❖ Cleaning of ceria particles is challenging due to their high

chemical affinity

watern2 = 1.33

Ө

glassn1 = 1.51

Incident light Reflected light

I(z)

zβ-1

4

Scattered lightto microscope

Scattered light

Glass lens

Objective lens

Tube lens

Mirror

CMOS Sensor Computer

5

Evanescent wave

6

Ceria dispersion

(dmean ~ 140 nm)

7

Potential Energy

Heig

ht

Separation distance

Particle trajectory

10 μm 2 μm

8D. C. Prieve, Adv. Colloid Interface Sci., 82, 93 (1999)

Inte

nsi

ty

PD

F

Pote

ntial Energ

yTime Intensity Height

0.01 0.1 1 101E-5

1E-4

1E-3

0.01

0.1

MSD=5.6E-5 * t0.05

MSD=2.1E-4 * t0.07

pH 3.0

pH 5.0

pH 7.0

MS

D (

m2 )

Time (s)

MSD=2.0E-3 * t0.15

0 40 80 120 160 2000

10

20

30

40

50

60

70

Cou

nts

Displacement (nm)

0 10 20 30 40 500

10

20

30

40

Cou

nts

Displacement (nm)

0 5 10 15 20 25 300

20

40

60

80

Cou

nts

Displacement (nm)

-60 -40 -20 0 20 40 60-60

-40

-20

0

20

40

60

Y (

nm)

X (nm)-200-150-100 -50 0 50 100 150 200

-200

-150

-100

-50

0

50

100

150

200

Y (

nm)

X (nm)-60 -40 -20 0 20 40 60

-60

-40

-20

0

20

40

60

Y (

nm)

X (nm)

Ntotal=500

Δt=20s

Ntotal=500

Δt=20sNtotal=500

Δt=20s(a) (b) (c)

(d) (e)

(f) (g)

9

pH 3 pH 5 pH 7

D=1.4 x10-3 μm2/s D=5.3 x10-3 μm2/s

D=50 x10-3 μm2/s

pH 7

pH 5 pH 3

MSDxy = 4DΔta

10

Glass lens

Particle dispersion

Computer

pH adjusted DI water

Squeeze bottle

2. Particle cleaning

1. Particle adsorption

Conditions-0.005 wt% Ferro ceria dispersion (dmean ~ 140 nm)-Particles adsorbed for 20 minutes

Procedure-Lens covered with ceria particles was washed multiple times.-Each time with 40 mL of pH adjusted DI water for 20s

77 µm

77 µ

m

11

pH 3

c

pH 5

pH 7

DI water at pH 5.5

DI water adjusted to pH 10

DI water adjusted to pH 12

1. Evanescent wave microscopy is a powerful tool to study particle-surface

interactions.

2. Ceria particles at pH 5.0 (D3D = 3.8×10-3 μm2/s) and pH 7.0 (D3D = 45×10-3 μm2/s) exhi

bited faster diffusion near glass surface than at pH 3.0 (D3D = 1.2×10-3 μm2/s)

3. As pH increased from 3.0 to 7.0, the most probable separation distance hmin of ceria

particle from glass surface increased from 11 to 60 nm.

4. Ceria particles adsorbed at higher pH can be more easily cleaned.

5. Charge repulsion is shown to be a key driver towards cleaning performance.

6. While charge repulsion is enough to clean larger ceria particles, it is not efficient in

removing smaller particles

12

THANK YOU!