Low Temperature Processing Low Temperature Processing of Dielectric Thin Filmsof Dielectric Thin Films

Low Temperature Processing Low Temperature Processing of Dielectric Thin Filmsof Dielectric Thin Films

Chris BrattenChris Bratten

AdvisorsAdvisorsProf. E. SlamovichProf. E. SlamovichProf. H. HillhouseProf. H. Hillhouse

Chris BrattenChris Bratten

AdvisorsAdvisorsProf. E. SlamovichProf. E. SlamovichProf. H. HillhouseProf. H. Hillhouse

Research GoalsResearch GoalsResearch GoalsResearch Goals

Produce thin films of Barium Titanate using Produce thin films of Barium Titanate using hydrothermal synthesishydrothermal synthesis

Verify formation of BaTiOVerify formation of BaTiO33 on substrates using on substrates using x-ray diffractionx-ray diffraction

Determine the dielectric properties of the films Determine the dielectric properties of the films producedproduced

ProcessProcessProcessProcess

Used ½ length glass slides as substratesUsed ½ length glass slides as substrates Cleaned slides using TCA, acetone and Cleaned slides using TCA, acetone and

methanolmethanol Sputtered 2 platinum electrodesSputtered 2 platinum electrodes Deposited a thin film of titanium onto the slides Deposited a thin film of titanium onto the slides

by evaporation to connect the 2 Pt electrodesby evaporation to connect the 2 Pt electrodes

Process Process (cont)(cont)Process Process (cont)(cont)

Samples immersed in Samples immersed in solutionsolution

– 125mL PE bottle125mL PE bottle

– 11MM BaCl BaCl2 2 + NaOH+ NaOH

– 11MM Ba(OH) Ba(OH)22

““Baked” at Baked” at temperatures between temperatures between 60 and 9060 and 90ooC for about 24 C for about 24 hours or morehours or more

Process Process (cont)(cont)Process Process (cont)(cont)

Samples removed from solution in a nitrogen Samples removed from solution in a nitrogen atmosphere (glove box)atmosphere (glove box)

Avoid formation of barium carbonateAvoid formation of barium carbonate Rinsed in a ph=12 solution then placed in Rinsed in a ph=12 solution then placed in

ethanolethanol– Solutions kept warm in ovenSolutions kept warm in oven– Samples taken out of glove box while immersed in Samples taken out of glove box while immersed in

ethanolethanol Samples removed from ethanol and blown dry Samples removed from ethanol and blown dry

with airwith air

Initial ResultsInitial ResultsInitial ResultsInitial Results

……Later on…Later on………Later on…Later on…

ChangesChanges

ProblemsProblemsProblemsProblems

Film adhesionFilm adhesion– Platinum being stripped Platinum being stripped

from slide in solutionfrom slide in solution

– Same for titanium, but Same for titanium, but not as much over not as much over platinumplatinum

Barium CarbonateBarium Carbonate– ContaminantContaminant

– Result of reaction with Result of reaction with carbon dioxide in air or carbon dioxide in air or solutionsolution

ChangesChangesChangesChanges

Switched solutionSwitched solution– 11MM Ba(OH) Ba(OH)22

– Better results, visuallyBetter results, visually

– Still had film loss in solution, but not as much as Still had film loss in solution, but not as much as beforebefore

Stopped depositing platinumStopped depositing platinum– Mostly lost in solutionMostly lost in solution

– Getting rid of an extra stepGetting rid of an extra step

ResultsResultsResultsResults

Capacitance TestingCapacitance TestingCapacitance TestingCapacitance Testing

Tested the 3 best samples based on XRD Tested the 3 best samples based on XRD informationinformation

Used TEM grids as a mask and deposited Used TEM grids as a mask and deposited titanium over the sampletitanium over the sample

Created a grid of electrodesCreated a grid of electrodes Used a LCR meter and probes to test Used a LCR meter and probes to test

capacitance of film between electrodescapacitance of film between electrodes

Capacitance TestingCapacitance TestingCapacitance TestingCapacitance Testing

Sample 10 - Site 3

14.4

14.6

14.8

15.0

15.2

15.4

15.6

15.8

16.0

-600 -400 -200 0 200 400 600

Distance From Origin (micrometers)

Me

as

ure

d

Ca

pa

cit

an

ce

(p

F)

x-axisy-axis

Minimum Recorded Value: 14.015 pFAverage Recorded Value: 15.130 pFMaximum Recorded Value: 15.876 pF

Capacitance TestingCapacitance TestingCapacitance TestingCapacitance Testing

Sample 14 - Site 2

20

25

30

35

40

45

50

0 100 200 300 400 500 600 700 800 900 1000 1100

Distance From Origin (micrometers)

Mea

sure

d C

apac

itan

ce (

pF

)

x-axisy-axis

Minimum Recorded Value: 34.58 pFAverage Recorded Value: 40.59 pFMaximum Recorded Value: 64.90 pF

Capacitance TestingCapacitance TestingCapacitance TestingCapacitance Testing

Sample 17 - Site 1

0

50

100

150

200

250

300

0 200 400 600 800 1000 1200 1400 1600

Distance From Origin (micrometers)

Me

as

ure

d C

ap

ac

ita

nc

e

(pF

)

x-axisy-axis

Minimum Recorded Value: 122.2 pFAverage Recorded Value: 175.7 pFMaximum Recorded Value: 284.2 pF

Capacitance and TemperatureCapacitance and TemperatureCapacitance and TemperatureCapacitance and Temperature

76

78

80

82

84

86

88

90

92

0 50 100 150 200 250 300Measured Capacitance (pF)

Tem

per

atu

re (

deg

rees

C)

Sample 10

Sample 14

Sample 17

Dielectrics and TemperatureDielectrics and TemperatureDielectrics and TemperatureDielectrics and Temperature

76

78

80

82

84

86

88

90

92

0 20 40 60 80 100 120 140 160 180Maximum Calculated r

Te

mp

era

ture

(d

eg

ree

s C

)

Sample 10Sample 14Sample 17

ConclusionsConclusionsConclusionsConclusions

Film qualities with relation to temperatureFilm qualities with relation to temperature– Based on XRD data:Based on XRD data:

Higher Temperatures lead to more BaTiOHigher Temperatures lead to more BaTiO33

– Based on LCR data:Based on LCR data: Too close to callToo close to call

– Generally, a higher temperature will produce a Generally, a higher temperature will produce a better filmbetter film

Fresh solutions lead to better filmsFresh solutions lead to better films Solutions “baked” for more than 24 hours Solutions “baked” for more than 24 hours

showed no major advantage over othersshowed no major advantage over others

Thanks To…Thanks To…Thanks To…Thanks To…

Prof. SlamovichProf. SlamovichProf. HilhouseProf. Hilhouse

MSEE DepartmentMSEE DepartmentPurdue UniversityPurdue University

My Fellow REU StudentsMy Fellow REU Students

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23

45

67

89

01

23

45

67

89

0

5

10

15

20

25

30

35

40

45

50

55

60

65

Mea

sure

d C

apac

itan

ce (

pF)

Position (y) Position (x)

Sample 14: Capacitance Testing Grid

0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 55-60 60-65