Spin Coating Simulator - Tutorial (Print Version)

📖 How to Use This Tutorial:

Print: Click the blue button (top right) → Print or Save as PDF
Navigate: Use browser Find (Ctrl+F) to search topics
Practice: Follow along with the simulator open

📋 Table of Contents

Introduction
Quick Start (60 seconds)
Interface Overview
Material Parameters
Speed Profile (4 Phases)
Environmental Control (PID)
Running a Simulation
Understanding Results
Exporting Data
Practical Examples

1. Introduction

What is Spin Coating?

Spin coating is a process used to apply uniform thin films to flat substrates. A solution is deposited on a substrate which is then rotated at high speed to spread the fluid by centrifugal force.

🎯 Learning Objectives:

Understand how process parameters affect coating thickness
Learn the relationship between viscosity, speed, and thickness
Master environmental control (PID systems)
Perform statistical analysis of coating uniformity
Apply Design of Experiments (DOE) principles

Simulator Capabilities

Feature	Description
🧪 Materials	6 different photoresists (from easy to difficult)
⚙️ Speed Profile	4-phase customizable process
🌡️ Environment	Temperature & humidity control with PID tuning
📏 Measurement	50-point uniformity analysis
📊 Statistics	Average, Std Dev, CV%, Uniformity
📥 Export	CSV & Excel data export

2. Quick Start (60 Seconds)

✨ Follow these steps to run your first simulation:

Step 1: Select Material → Choose AZ 1518 (beginner-friendly)

Step 2: Set Quantity → Enter 100 µL

Step 3: Configure Speed Profile:

Phase 1: 10 rpm, 2 s
Phase 2: 10 → 500 rpm, 5 s
Phase 3: 2000 rpm, 15 s
Phase 4: 3000 rpm, 15 s

Step 4: Set Environment:

Temperature: 22°C
Humidity: 45%
Keep default PID values

Step 5: Click ▶️ START SIMULATION

Step 6: Wait 2-3 seconds for results

Expected Results:

Average Thickness: ~2.5 µm
Uniformity: >95% (Green indicator)
CV%: <2%

4. Material Parameters

Available Materials

Material	Viscosity	Difficulty	Typical Use	Thickness @ 3000 rpm
AZ 1518	25 cP	⭐ Easy	Photolithography	~1.7 µm
S1813	40 cP	⭐ Easy	Standard resist	~2.1 µm
PMMA 950K	35 cP	⭐⭐ Medium	E-beam lithography	~2.0 µm
SU-8 2050	450 cP	⭐⭐ Medium	Thick films, MEMS	~7.0 µm
HSQ	12 cP	⭐⭐⭐ Hard	Nanofabrication	~0.8 µm
Ma-N 2403	18 cP	⭐⭐⭐ Hard	High resolution	~1.0 µm

⚠️ Beginner Tip: Start with AZ 1518 or S1813 for best results

Resin Quantity

Wafer Size	Recommended Quantity
50mm	50-100 µL
100mm	100-200 µL
200mm	200-500 µL

Effect on coating:

More resin (↑) → Thicker coating
Less resin (↓) → Thinner coating

5. Speed Profile (4 Phases)

SPEED (rpm)
    ↑
5000│                              ┌──────────────────┐
    │                              │   Phase 4        │
3000│                     ┌────────┤   DRYING         │
    │                     │        │                  │
2000│                     │ Phase 3│                  │
    │                    ╱│ THIN   │                  │
 500│                   ╱ │        │                  │
    │     ┌──────┐   ╱Phase│        │                  │
  10│─────┤Phase1│ ╱  2   │        │                  │
    │     │SPREAD│RAMP    │        │                  │
   0└─────┴──────┴─────────┴────────┴──────────────────┴───→ TIME
         2s      5s       15s       15s

Phase 1: Deposit (Spreading)

Purpose: Spread the resin across the wafer
Speed: 10-50 rpm (Low speed)
Time: 2-5 seconds
⚠️ IMPORTANT: Speed must be ≥ 5 rpm

Phase 2: Acceleration Ramp

Purpose: Gradually increase speed to prevent splashing
From: 10-100 rpm
To: 500-2000 rpm
Time: 3-10 seconds

Phase 3: Speed Thinning

Purpose: Achieve desired thickness
Speed: 1000-4000 rpm (High speed)
Time: 10-30 seconds
Key: Film thickness is determined mainly in this phase

Phase 4: Final Drying

Purpose: Evaporate remaining solvent
Speed: 2000-5000 rpm (Very high speed)
Time: 10-30 seconds

Phase	Speed Range	Duration	Purpose
1 - Deposit	10-50 rpm	2-5 s	Spread resin
2 - Ramp	10→2000 rpm	3-10 s	Smooth acceleration
3 - Thinning	1000-4000 rpm	10-30 s	Set thickness
4 - Drying	2000-5000 rpm	10-30 s	Evaporate solvent

8. Understanding Results

Statistics Overview (50 measurement points)

Statistic	What It Means	Good Value
Average Thickness (µm)	Mean thickness across all 50 points	Target ±10%
Std Dev σ (µm)	Measure of thickness variation	< 0.1 µm
CV%	Coefficient of Variation = (σ/avg) × 100	< 2%
Min (µm)	Thinnest point measured	Check spec minimum
Max (µm)	Thickest point measured	Check spec maximum
Uniformity (%)	[1 - (Max-Min)/(2×Avg)] × 100	≥ 95%

Uniformity Interpretation

Value	Color	Quality	Use Case
≥ 95%	🟢 Green	Excellent	Production ready
90-95%	🟡 Yellow	Good	Development acceptable
< 90%	🔴 Red	Poor	Not acceptable

Industry Standards:

Production: ≥ 98%
Development: ≥ 95%
Research: ≥ 90%

10. Practical Examples

Example 1: Speed Effect Study

Objective: Understand how speed affects thickness

Run	Phase 3 Speed	Expected Thickness (AZ 1518)
1	1000 rpm	~5.0 µm
2	2000 rpm	~2.5 µm
3	3000 rpm	~1.7 µm
4	4000 rpm	~1.3 µm

Analysis: Create plot with Speed (X-axis) vs Thickness (Y-axis)
Expected: Thickness ∝ Speed^-0.5 (inverse square root relationship)

Example 2: Material Comparison

Objective: Compare all 6 materials at same speed

Material	Viscosity	Expected Thickness @ 3000 rpm
HSQ	12 cP	~0.8 µm
Ma-N 2403	18 cP	~1.0 µm
AZ 1518	25 cP	~1.7 µm
PMMA	35 cP	~2.0 µm
S1813	40 cP	~2.1 µm
SU-8	450 cP	~7.0 µm

Analysis: Plot Viscosity vs Thickness
Expected: Thickness ∝ √Viscosity

Troubleshooting Guide

Common Issues & Solutions

Problem	Possible Cause	Solution
Error: "Phase 1 must be ≥ 5 rpm"	Phase 1 speed too low	Set Phase 1 to 10 rpm or higher
Poor Uniformity (<90%)	Environmental instability	Reduce Kp and Ki, add small Kd (0.05)
Poor Uniformity (<90%)	Insufficient resin	Increase quantity to 100 µL or more
Thickness too high	Speed too low / Temp too low	Increase speed or temperature
Thickness too low	Speed too high / Temp too high	Decrease speed or temperature
Export doesn't work	No simulation run yet	Run simulation first, then export

Quick Reference Card

Default Settings (Beginner)

Parameter	Value
Material	AZ 1518
Quantity	100 µL
Phase 1	10 rpm, 2 s
Phase 2	10→500 rpm, 5 s
Phase 3	2000 rpm, 15 s
Phase 4	3000 rpm, 15 s
Temperature	22°C
Humidity	45%
PID	Kp=4.0, Ki=1.0, Kd=0.0

Key Formulas

Thickness Equation:
h = K × √(η/ρ) / ω
h: thickness, η: viscosity, ρ: density, ω: angular velocity

Viscosity-Temperature:
η(T) = η₀ × exp(-0.03 × ΔT)
ΔT = T - 22°C

Uniformity:
U = [1 - (Max-Min)/(2×Avg)] × 100%

🔬 SPIN COATING SIMULATOR

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