Optical Microscopy SOP (UWaterloo)

Purpose

To inspect patterned wafers using optical microscopy to verify feature quality, alignment, and dimensions after lithography and development.

Supports HackerFab fabrication workflows targeting <10 µm feature sizes using calibrated microscope measurements.

Scope

Applies to:

• Wafers after development

• Lithography calibration wafers

• Feature size verification and process troubleshooting

Equipment & Materials

Equipment

• Optical microscope (AmScope)

• Amscope measurement software

• Microscope stage

• Cleanroom wipes

• Computer for image capture

Materials

• Patterned wafer

• Calibration slide (µm scale)

Safety Precautions

• Handle wafers with tweezers only.

• Avoid touching lens surfaces.

• Do not drop wafers on stage.

• Turn off illumination after use.

Calibration Requirements

Before measuring feature sizes:

1. Use a calibration slide with known µm markings.

2. Calibrate at each magnification level used.

3. Save calibration settings in software.

Procedure

1

Setup

1. Turn on microscope illumination.

2. Select 5x magnification

3. Place wafer on stage.

2

Focus and Locate Pattern

1. Focus using the coarse knob.

2. Adjust fine focus until the pattern is sharp.

3

Inspect Pattern Quality

Check for:

• Clean edges

• No overdevelopment

• Uniform exposure

4

Measure Feature Size

1. Use a calibrated measurement slide.

2. Measure multiple features.

3. Record average feature size.

5

Capture Images

1. Save screenshots at 100% zoom (important for accurate scaling).

2. Include a scale bar.

3. Name the file with the date.

Example: 2026-03-02_HFLogo_8sExposure_4000rpm.png

Expected Results

• Sharp, well-defined patterns.

• Feature sizes within the expected range.

• Verification of lithography calibration.

Troubleshooting

Problem	Cause	Fix
Blurry image	Out of focus	Refocus stage
Wrong feature size	Calibration error	Recalibrate microscope
Uneven patterns	Spin coat issue	Check Spin Coating SOP
Overdeveloped pattern	Too long dev time	Adjust photoresist development SOP

Notes

• Always recalibrate after changing magnification.

• Keep image records for process tracking.

• Use microscopy results to tune exposure dose and spin speed.