AZ 1512 RESIST PHOTOLITHOGRAPHY Photolithography SOP2.pdf · not needed on a thin film surface or...

AZ 1512 RESIST PHOTOLITHOGRAPHY STANDARD OPERATIONAL PROCEDURES

Bonghoe Kim

EE527 SPRING 2011

SUPERVISOR: PROFESSOR DARLING, R BRUCE

MAY 9, 2011

Department of Electrical Engineering

University of Wahsington

BONGHOE KIM

EE527 SPRING 2011

SUPERVISOR: PROFESSOR DARLING, R BRUCE

MAY 9, 2011

AZ 1512 RESIST PHOTOLITHOGRAPHY 1

AZ 1512 RESIST PHOTOLITHOGRAPHY

STANDARD OPERATIONAL

PROCEDURES

Part I. Experiment Environment

Basic Information

-Laboratory Information: Microfabrication

Laboratory (Room# EEB B025, Electrical

Engineering Building, University of

Washington).

-Emergency Contact: Prof. R. Bruce Darling ([email protected], (206) 543-4707,

226 EEB)

Equipment and Personal Safety Protectors

[Equipment & Protectors]

# Process Step Equipment Use Limitation of Material

Protectors

(For Samples,

For personal)

1 Dehydration Baking Hot plate Fit 3 inch Glass plate Latex Gloves

2 Photoresist Coating Spin-coater Maximum 4 inch wafer Latex Gloves

3 Pre-Baking Hot plate Fit 3 inch Glass plate Latex Gloves

4 Alignment Oriel Aligner Maximum 3 inch wafer Latex Gloves

5 UV-Exposure Oriel Aligner Maximum 3 inch wafer Latex Gloves

6 Development Fume Hood System - Full-face Mask,

Apron, Gloves

7 Post-Baking Hot plate Fit 3 inch Glass plate Latex Gloves

mailto:[email protected]


8 Inspection Microscope - Latex Gloves

-Limitations of Wafer size: Because of limitations of equipment’s capability, wafer size

should be specified for the each process step.

1. Hot Plates

(Dataplate-720)

2. Spin Coater (for Cleaning)

(Specialty Coating Systems Model P6700)

3. Oriel 3 Aligner 4. Timer Integrator for Oriel 3 Aligner

5. 68810 Arc lamp power supply 6. Vacuum Control Box


7. Fume Hood 8. Microscope for Inspection

9. Spin Coater (for Cleaning)


Materials Preparation

[Materials]

-Chemical Materials:

# Materials Purpose Cautions for handling

1 AZ 1512

PHOTORESIST Coating material

Keep the PR bottle clean.

Waste an extra PR in the pipette.

2 AZ 300 MIF

DEVELOPER Removing PR exposed -

3 3 inch Glass Plate Keep Uniform temperature -

4 DI Water Cleaning Use the DI water with over ~17Mohm

to insure quality and electrical features.

5 Acetone Remove Photoresist

Flammable solvent, Keep away from

fire and high temp.

Use the Fume Hood System.

6 Isopropanol Remove remain Acetone -

Expected Hazards & Cautions (at each process step)

# Process Step Hazard

Cause Effect

1 Dehydration Baking High Temperature Burn of Skin

2 Photoresist Coating No vacuum holding Break wafer

Inhalation Carcinogen, blood poison

3 Pre-Baking High Temperature Burn of Skin

4 Alignment Drop mask mount hold cover Break Mask

5 UV-Exposure

UV Exposure

Wrong high voltage cable

connection

Burn of Eyes and Skin

Sparks and explosion

6 Development - -

7 Post-Baking High Temperature Burn of Skin

8 Inspection Let the Lenz hit the sample Scratch the surface of sample


Part II. Operational Procedures (Photolithography)

Introduction

- Photolithography is one of processes used in micro-fabrication work to remove area that is

not needed on a thin film surface or the substrate bulk. It uses light, such as UV, to transfer

a geometric pattern from a photo mask to a light-sensitive chemical "photoresist". AZ 1512

series positive photoresists are established for i, h, and g-line; UV spectrum 310nm ~ 440nm

and broadband resists. AZ 1512 Photoresist can be developed in AZ 300 MIF developers.

The purpose of this Standard Operational Procedure (SOP) is to be directions for high-

efficient Lab process as well as a practical method of laboratory R&D documentation.

STEP 1. Dehydration Baking

- This step is to remove humidity on the surface of substrate. For this step, Hot Plates or

Convection oven can be employed. Equipment 1 as shown above, page 2, is used

dehydration step.

Dehydration Baking

# Process Stages Detailed Actions

1 Turn on the Hot Plate Switch 1. Turn on switch

2 Setting the Temperature of Hot Plate

1. Press ENT

2. Press Plate Temperature

3. Type Desired Temperature 95 deg. C.

4. Press ENT

** Desired Temperature: You should consider

temperature loss by 3-inch Glass Plate (grinded

both sides to get very smooth surface). Type 5

deg. C more temp.

5. Check temperature with Handy Surface

Thermometer.

6. Check the temperature at several points (see

picture below)

7. Q: Is Thermometer indicating the Exact

Temperature you want?

YES (go to next stage)

NO (go to number 2-1)


3 Set up Timer 1. Type 6,0 (for 60 sec) or 1,0,0 (for 1min.)

4 Place the wafer and press start button

on Timer

1. Place the wafer very carefully. (Glass surface is

very smooth, so, the wafer is easy to slip.)

[Simultaneously]

1. Press Start Button on Timer

5 Timer is ringing! Turn off

6 Remove the wafer from the Hot Plate

1. Remove the wafer very carefully.

2. Place the wafer glass slide (for cooling)

3. Cover the wafer (To protect from particles)

STEP 2. AZ 1512 Photoresist (PR) Coating

- Spin PR coating is standard resist application method and one of important processes used

in micro-fabrication work to deposit thin film to protect from exposure of UV light. The

Thickness depends on mainly spin coater speed, acceleration and viscosity of PR.

Equipment 2 as shown above, page 2, is used to deposit thin film.

- Material Information from AZ 1500 Resist Product

Graph 1. 6 inch silicon wafer, static dispense SB: 100 deg. C./60sec

Reference: AZ 1500 Photoresist Data Package (p. 8).


AZ 1512 Photoresist (PR) Coating


1 Open Fume Hood 1. Turn on the Fume Hood and its light.

2 Spin coater Vacuum check

1. Turning the Vacuum Knob (Right side of Fume Hood)

2. As shown above Graph 1., press +/- button to specify

spin RPM, Ramp, and Time for getting desired

thickness.

TABLE 1. AZ 1512 PR Spin coating recipe

Spin RPM Ramp (sec) Time (sec)

Slow coat 100 10 5

Spin 500 5 10

Level out 4000 5 20

Ramp down - 10 -

3. Press the Start and check the vacuum with finger.

(Touch the small hole on the center of chuck)

4. Q: Can you feel the vacuum suction?


NO (go to number 2-1 or fix the vacuum system)

3 Place the wafer (Face-up)

1. Place the wafer carefully (face up).

2. Let the wafer on center of chuck (generally, the chuck

is smaller than wafer size).

3. Check again if the chuck (vacuum) is holding the wafer

or not.

4 Photoresist Preparation 1. Check the PR Expired date.


2. With using pipette, drop the PR material on the silicon

surface carefully to avoid PR bubbles. Also, PR should

be appropriate amount so that surplus PR does not

stain it.

3. Pipette must not be dipped.

4. [Remain PR] Remain PR should be wasted on

aluminum foil around the chuck of spin coater.

5. [PR Bubble] Get rid of PR bubbles from the center of

the wafer surface to the edge.

5 Start PR Spin coating 1. Press the start button to start spin coater.

6 Remove the wafer &

check

1. Turn off the vacuum (Stop button) to remove the wafer

from the chuck.

2. Check the deposited PR condition with Microscope.

3. Q: Is the PR coating acceptable?


NO (go to number 6-recover)

6-recover Strip deposited PR

1. Pour appropriate amount acetone in a Schale or a

beaker.

2. Soak the wafer (use Scooping motion) and then agitate

it (about 40 sec.).

3. Remove the acetone with the spin coater. (Isopropanol)

4. Clean water again with DI water (over ~17Mohm).

5. Dry the backside of wafer.

6. Inspection with Microscope.

7. Q: Is the PR removed appropriately?


NO (go to number 6-recover)

STEP 3. Pre-Baking

- The purpose of this step is to remove the solvent from photoresist. Also, this step make the

deposited photoresist adhere to the wafer surface well.

Pre-Baking



1 Turn on the Hot Plate Switch 1. You do not need to change the setting

condition because the Hot Plate is already set

up in 1st step.


3 Set up Timer


on Timer






STEP 4. Alignment & Exposure (Oriel 3 Aligner)

- The purpose of this step is to change the molecular form of selected area of the PR-coated

substrate. Endurance and carefulness is highly required for this step in order to minimize

misaligns that have influence on electrical characteristics of device. UV-radiation will be

used as light source.

Alignment & Exposure (Oriel 3 Aligner)


1 Warm-up Alignment &

Exposure machine

1. Turn on the UV-light power supply and press start and

wait until the UV-light source is stabilized.

2 Mask Alignment

1. Turning the Vacuum Knob (Right side of Fume Hood)

5. Source Specifications:


-Mercury arc lamp (Cover wavelengths 365nm (i-

line) / 437nm (g-line))

-Exposure power from 200 Watts to 500 Watts

Exposure power 300 Watt

Exposure Time 20 seconds

Initial value of

adjust controller 5.0 (x,y, Θ)

(x,y, Θ) : controller 1, 2, and 3.

D = I*te

D: Exposure dose

I: Optical power density (check periodically, since the

lamp ages)

te: Exposure time, duration of optical radiation.

The Dose-To-Print (DTP) is the required dose to

create a full thickness latent image in the photoresist

and it should be calculated. (Proportional to PR

thickness)

3 Mount Photo-Mask 1. Open the Photo-Mask Cover

2. Place Photo-Mask (L-shape – Top right)


3. Cover the Photo-Mask holder.

4 Mount Wafer

1. Hold and raise the Mask holder up. And keep to grip it

2. Place the wafer on the chuck. (Flat zone down)

3. Cover the wafer with Mask Holder very carefully.

4. Be Careful!!!

Do not drop the Mask Holder! And make sure grip the

Mask Holder!


5. Open the vacuum knob and keep ~30mmg.

6. Rotate the z-axis controller to rise up the chuck until

there is very small gap between mask and wafer. (Do

not contact with each other)

5 Aligning

1. Generally, requires minimum 2 mask alignment marks

on opposite sides of the wafer.

2. The split-field microscope makes alignment easier.

(Oriel 3 Aligner)

3. Align the x, y, and angle between the alignment targets

on wafer created from prior processing step (a) and the

cross hair on mask, open window in chrome through

which mark on wafer can be seen (b).


4. Adjust the position of the wafer (a) with using

controller screws. (x, y, and angle)

5. Slowly close the vacuum level until 5mmHg.

6. Turn on the vacuum control box switch ON.

6 Exposing

1. Set the exposure power and time

Exposure power 300 Watt

Exposure Time 20 seconds

2. Press the UV-light exposure button.

3. Finally, main vacuum box switch OFF, and then open

the cover and take off the wafer from the chuck.

4. Cover the wafer with Mask Holder very carefully.

STEP 5. Development (AZ 300 MIF)

- Development process is to remove the photoresist part with AZ 300 MIF developer

material.

Development (AZ 300 MIF)


1 Material preparation

1. Pour appropriate amount of AZ 300 MIF in a

Schale or a beaker.

2. Soak the wafer (use Scooping motion) and then

agitate it during the immersion time (about 60

sec.)- Over etching.

3. Soak the wafer into DI wafer to rinse for

20seconds.

4. Spin coater Dry (Basic set up condition or 4000

rpm 20sec.)


5. Dry backside with Air spray.(Red Screw-

Middle one)





STEP 6. Post-Baking

- The purpose of this step is to stabilize and solidify the photoresist undeveloped. With using

Hot Plate, post baking process will be achieved by specified condition.

Post-Baking


1 Turn on the Hot Plate Switch 1. You do not need to change the setting

condition because the Hot Plate is already set

up in 1st step.


3 Set up Timer


on Timer







STEP 7. Stripping photoresist

- The photoresist on the wafer should be removed with solvent materials; Acetone. And

Then DI water rinse will be achieved. Finally, Inspection process will be performed to check

the conditions of process.

Stripping photoresist


1 Strip deposited PR

8. Pour appropriate amount acetone in a Schale or

a beaker.

9. Soak the wafer (use Scooping motion) and then

agitate it (about 40 sec.).

10. Remove the acetone with the spin coater.

(Isopropanol)

11. Clean water again with DI water (over

~17Mohm).

12. Dry the backside of wafer.






References

http://cmi.epfl.ch/photo/photo_process/files/az_1500_series.pdf

http://www.artisan-scientific.com/57320.htm

Darling, R. Bruce, Lecture note,

https://www.ee.washington.edu/people/faculty/darling/ee527s11/Photolithography.pdf

[Only Several Picture from] SOP_AZ1512_Photolithography_WangLugo2009, page 3.

http://cmi.epfl.ch/photo/photo_process/files/az_1500_series.pdf

http://www.artisan-scientific.com/57320.htm

https://www.ee.washington.edu/people/faculty/darling/ee527s11/Photolithography.pdf

AZ 1512 RESIST PHOTOLITHOGRAPHY Photolithography SOP2.pdf · not needed on a thin film surface or...

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