Ultra Violet Lithography Process Part 1
A low-cost microscope projection photolithography system for high-resolution fabrication
Overview
This project demonstrates a high-resolution UV projection system using a DLP470NE digital micromirror device (DMD) and a Nikon Plan Apo VC objective lens for sub-micron lithographic imaging. It is designed for applications that demand precision micro-patterning and optical lithography at near-diffraction-limited resolution.
Aims
- Implement a sub-micron lithographic projector system using a DLP chip and high-NA objective.
- Goal: Achieve 270nm projected pixel pitch at 405nm UV wavelength, with resolving power down to ~329nm.
- Target Application: Microscale fabrication, biomedical microstructures, and lab-on-chip prototyping.
System Specifications
DMD Chip
| Property | Specification |
|---|---|
| Type | DLP470NE (0.47-inch 1080p DMD) |
| Resolution | 1920 x 1080 |
| Pixel Pitch | 5.4 µm |
| Active Area | 5.832 mm (H) x 10.368 mm (W) |
DMD provides high pixel density with fast frame switching, ideal for maskless projection lithography.
Objective Lens
| Property | Specification |
|---|---|
| Model | Nikon Plan Apo VC 20x |
| Magnification | 20x Demagnification |
| UV Correction | Up to 405 nm |
| Numerical Aperture | 0.75 |
| Working Distance | 1 mm |
| Depth of Focus | 0.48 µm |
| Field of View (FOV) | 1.25 mm diameter |
| Theoretical Resolution | (0.61 x λ) / NA = 329 nm (λ = 405 nm) |
With a depth of focus of less than 0.5 µm, focus adjustment is critical for sharp feature transfer.
Projection Calculations
Projected Image Size
Using the 20x demagnification from the objective:
- Projected Height: 5.832 mm / 20 = 0.292 mm
- Projected Width: 10.368 mm / 20 = 0.518 mm
- Diagonal: √(0.292² + 0.518²) ≈ 0.354 mm
This falls well within the 1.25 mm field of view provided by the objective.
Pixel Size and Resolution
- Projected Pixel Size: 5.4 µm / 20 = 270 nm
- Objective Resolving Power: 329 nm @ 405 nm
- Resolution Gap: 329 - 270 = 59 nm resolving mismatch
Projected pixel size is below the diffraction-limited resolution, meaning some features may not resolve cleanly due to the NA and wavelength limits.
Summary Table
| Parameter | Value |
|---|---|
| Projected Image Size | 0.292 mm x 0.518 mm |
| Projected Pixel Size | 270 nm |
| Diffraction-limited Res. | 329 nm (at 405 nm wavelength) |
| FOV of Objective Lens | 1.25 mm diameter |
| Working Distance | 1 mm |
| DOF (Depth of Focus) | 0.48 µm |
Resources
All design files and simulation notebooks will be uploaded soon