PMGI & LOR Under Layer Resists

PMGI and LOR resists enable high yield, metal lift-off processing in a variety of applications from data storage and wireless ICs, to MEMS. Used beneath photoresists in a bi-layer stack, PMGI and LOR extend the limits of lift-off processing beyond where single layer resist strategies can reach. This includes very high resolution metallization (< 2.5µm), as well as very thick (>4µm) metallization. These unique materials are available in a variety of formularies to meet virtually any customer need.

Material uses Material attributes

• Metal lift-off processing

• Airbridge fabrication

• Release layers

• Won’t intermix when over-coated with imaging resists
• Single step development of bi-layer stack in TMAH or KOH developers
• High thermal stability: Tg ~190 C
• Removes quickly and cleanly in conventional resist strippers
• Enables sub 0.25µm micron bi-layer resist imaging
• Enables high yield, very thick (>3µm) metal lift-off processing

Bi-Layer Lift-Off Process Lift-Off: An enabling, additive lithographic process
Step 1. LOR or PMGI is coated
Step 2. The imaging resist is coated onto the LOR or PMGI layer. 1. Bi-layer resist pattern
Step 3. The imaging resist is exposed. GaAs Modulator with Al airbridge
Source: Nortel

PMGI used as a sacrificial layer on which the airbridge was built. The PMGI layer was subsequently removed with conventional resist removal processing.
Step 4. The wafer is developed. 2. Metal Deposition
Step 5. Metal Deposition
Step 6. Lift-Off! 3. Clean solvent lift-off