Resist Options
Resist coating and vapor priming for etching, lift-off and permanent polymer structures.
- Wafer size
- Up to 4"
- Smallest piece
- 5 × 5 mm
- Coating
- Spin
- Vapor priming
- 75 – 120 °C
- Positive
- Reversal
- Epoxy
- Negative
- PMGI
- Cured epoxy: difficult stripping
- Positive resist softening: 100–130 °C
- Coating nonuniformity near steps, trenches and edges
Materials and thickness
| Material | Thickness per run | Use and notes |
|---|---|---|
| Positive photoresist | 0.5–20 µm | Optical etch mask Formulation determines thickness and resolution. |
| Image-reversal photoresist | 0.7–3.5 µm | Undercut mask Resist grade determines thickness and undercut. |
| Negative epoxy photoresist | 0.5–200 µm | Thick or permanent structures Thick films require suitable exposure and development conditions. |
| PMGI underlayer | 0.1–5 µm | Bilayer lift-off Underlayer thickness must exceed metal thickness. |
Full specifications
- Substrates
- Flat Si, glass, sapphire and compatible film stacks; irregular pieces and steps limit coating uniformity.
- Sample size
- 5 × 5 mm pieces to 100 mm wafers; smaller pieces and 150 mm wafers need compatible holders.
- Thickness range
- Positive: 0.5–20 µm; reversal: 0.7–3.5 µm; epoxy: 0.5–200 µm; PMGI: 0.1–5 µm.
- Process temperature
- Priming: 75–120 °C; epoxy bake: about 95 °C; PMGI: 160–190 °C or higher.
- Materials
- Positive, image-reversal, negative epoxy and strippable negative resists; PMGI lift-off underlayers.
- Conformality
- Spin coating thins over steps and varies near trenches and sample edges.
- Resist formulation determines coating thickness and achievable feature size.
- Cured epoxy resist is difficult to strip; use it where permanent polymer structures are acceptable.
- Adhesion promoters must suit the resist and substrate; epoxy and PMGI often need no primer.
- Positive resist profiles can soften at 100–130 °C; subsequent processing must stay within the mask thermal budget.