TFTs Process Flow

8/10/2019 TFTs Process Flow

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Process FlowMetal Oxide Thin Film Transistors

Fabrication


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N+ Si wafer

Gate insulator

Active layer

S D

N+ Si wafer

Gate insulator

Active layer

N+ Si wafer

Gate insulator

N+ Si wafer

Thermal oxidation

Spin coating

Shadow mask(Sputter, Evaporator)

Annealing

(FGA, O2)

Cleaning

(DHF 200:1)

Sample & solution preparation

1. Wafer cutting : 1.8 x 1.8 cm

Using the diamond scribe to cut the wafer into square

pieces.

2. Cleaning process:

No. Cleaning solutionTemp.

(C)

Time

(mins.)

1 Acetone 25 5

2 Ethanol 25 5

3 DI Water 25 5

Cleaning solution (acetone, ethanol and DI

water) and ultra-sonic cleaner

3. Using N2gun to dry the wafers


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4. Solution preparation:

Stirring the raw solutions by ultra - sonicator and

mixing machine in 5 mins for each step.

Mixing the solutions with the ratio calculated by theequation below by mixing machine:

CuO/NiOsolution calculation:

CuO/NiO(20%)+MIBK/MEK (+Silicate binder) = a%

% =

100%

N+ Si wafer

Gate insulator

Active layer

S D

N+ Si wafer

Gate insulator

Active layer

N+ Si wafer

Gate insulator

N+ Si wafer

Thermal oxidation

Spin coating


Annealing

(FGA, O2)

Cleaning

(DHF 200:1)

Solutions: CuO(20%), NiO 10%, Silicate

bider, MIBK, MEK, Hybrid binderMicro electronic scales

Mixing machine


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N+ Si wafer

Gate insulator

Active layer

S D

N+ Si wafer

Gate insulator

Active layer

N+ Si wafer

Gate insulator

N+ Si wafer

Thermal oxidation

Spin coating


Annealing

(FGA, O2)

Cleaning

(DHF 200:1)

Mixing Solution Calculating

1. CuO solution

20 % =

+ 100%

% =

+ 100%

Where: MMIBK= MMIBK + MMIBK- MMIBK: Mass of MIBK in the initial solution (CuO 20% + MIBK)

- MMIBK: Mass of MIBK in the subsequent solution (CuO a% + MIBK)- MMIBK: Mass of MIBK which is added to dilute the (CuO 20% +

MIBK) solution to (CuO a% + MIBK) solution

Taking 50g (MCuO+MMIBK) to calculate the solution

= 0.5

In the other hand, we have:

= 2 = 50 2.5 CuO 1% = 47.5g MCuO20%+MIBK= 2.5g CuO 5%

= 37.5g MCuO20%+MIBK

= 12.5g

CuO 10% = 25g MCuO20%+MIBK= 25g


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N+ Si wafer

Gate insulator

Active layer

S D

N+ Si wafer

Gate insulator

Active layer

N+ Si wafer

Gate insulator

N+ Si wafer

Thermal oxidation

Spin coating


Annealing

(FGA, O2)

Cleaning

(DHF 200:1)

Mixing Solution Calculating

1. NiO solution

10 % =

+

100%

% =

+ 100%

Where: MMEK= MMEK + MMEK

Taking 50g (MNiO+MMEK) to mix the solution

= 0.5In the other hand, we have:

= 4.5 = 50 5

NiO 1% = 45g MCuO20%+MIBK= 5g NiO 5% = 25g MCuO20%+MIBK= 25g


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N+ Si wafer

Gate insulator

Active layer

S D

N+ Si wafer

Gate insulator

Active layer

N+ Si wafer

Gate insulator

N+ Si wafer

Thermal oxidation

Spin coating


Annealing

(FGA, O2)

Cleaning

(DHF 200:1)

Spin coater(ACE-200)

Spin Coating:

CuO/NiO deposition by Spin Coating


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N+ Si wafer

Gate insulator

Active layer

S D

N+ Si wafer

Gate insulator

Active layer

N+ Si wafer

Gate insulator

N+ Si wafer

Thermal oxidation

Spin coating


Annealing

(FGA, O2)

Cleaning

(DHF 200:1)

Top electrode depositing by Sputtering or

CVD

1. Applying shadow mask:

2. Depositing by Sputtering or CVD:

Chemical Vapor Deposition System /

Annealing system (FGA, O2)

Sputtering System


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Experimental plan
http://localhost/var/www/apps/conversion/tmp/scratch_4/TFT%20experiment%20plan%20table(modification).xlsxhttp://localhost/var/www/apps/conversion/tmp/scratch_4/TFT%20experiment%20plan%20table(modification).xlsx


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Measurement Methods

1. Sheet resistance measurement by Four-point Probe Station

Sheet resistance measurement on the solution processed NiO TFT

Four-point Probe Station System0.2 0.3 0.4 0.5 0.6 0.7

40

60

80

100

120

140

160

180

Sheetresistance(

G/sq.)

V(V)

0 10 20 30 40 50

40

60

80

100

120

140

160

180

Sheetresistance(

G/sq.)

I(pA)

2. Surface testing by Optical Microscope

Optical Microscope StationOM measurement on the Sputtering

samples


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Measurement Methods

3. Deposition layer thickness by FE-SEM

FE-SEM System Birds eye view FE-SEM images of the CuxO films formed by spin coating

with silicate binder, showing the thickness of 40 - 240 nm CuxO.

4. Composition of the samples by XRD:

X-ray DiffractionSystem

XRD pattern of (CuO 20% + MIBK) and the CuO nano particles from Ditto


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Measurement Methods

5. Samples surface at nanoscale by AFM

Atomic force microscopy system

AFM image if the CuO spin coating sample

which is spun at 6500 rpm

TFTs Process Flow

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