MC PC 62E and AZ P4K-AP are used in CMi as a surface protective coating for dicing and other potentially damaging applications. In April 2025, AZ P4K-AP has been discontinued by its manufacturer Merck, and his replaced by an equivalent formulation from Microchemicals (see spincurves. below).
The resist is not photosensitive and therefore cannot be exposed and patterned.
For adequate protection, please select a layer thickness higher than your device topography. If MC PC 62E (AZ P4K-AP) is not thick enough to cover your topography, any thicker photoresists, such as AZ 10XT-60 can be used instead.
Wafer surface preparation
Usually adhesion of photoresist on inorganic materials is poor resulting in losses of fine structures after development. To solve the issue, silicon wafers are generally treated using the HMDS vapor prime treatment before spincoating the photoresist. Details about the HMDS process and control can be found here: link
Assuming wafers with a clean surface free of organic contamination, the best adhesion will be obtained with the surface preparation recommended in the table:
| Surface material (larger area) | Vapor HMDS | Plasma O2 | Thermal dehydratation |
|---|---|---|---|
| Si | √√ | √ | √ |
| SiO2, fused silica, SiN, Si3N4 | √√ | √ | √ |
| Float glass, pyrex | √ | √√ | √ |
| Metals: Al, Au, Pt, Ti | … | √ | √√ |
| Metals: Ag, Cu, Cr, Fe | … | X | √√ |
| III/V semiconductors (GaN, GaAs) | … | X | √√ |
Legend: √√ Strongly recommended / √ Alternative process / … Not effective / X May affect or destroy underlaying material
Spincoating
The MC PC62E and AZ P4K-AP spincurves are shown below, as well as process details for manual coating.
Available thicknesses: 5 um / 10 um
Coating:
| PR thickness [μm] | PR | Dispense method | Spin speed [RPM] | Spin duration [sec] | Notes |
|---|---|---|---|---|---|
| 5 | MC PC62E | static + ramp to 1500RPM | 4500 | 30 | |
| 10 | MC PC62E | static + ramp to 1500RPM | 1500 | 30 |
Softbake:
| PR thickness [μm] | Bake method | Temperature [°C] | Bake duration [sec] |
|---|---|---|---|
| 5 | proximity – 300um | 120 | 180 |
| 10 | proximity – 300um | 120 | 360 |
Available sequence options:
- HMDS / EC (edge clean)
- Dehydrate / EC
- No treatment / EC
- HMDS / EBR (edge bead removal)
- Dehydrate / EBR
- No treatment / EBR
- Find the spin-coating speed “XXXX” [RPM] matching your target thickness from the AZ P4K-AP spincurve.
- When coating on wafers, use the STD_”XXXX” recipe, which includes a 500 RPM spreading step and 40 seconds of main coating step.
- When coating on small chips, use the CHIP_”XXXX” recipe, which includes 40 seconds of main coating step and a short acceleration at the end to reduce edge bead effects.
- Softbake temperature: 125°C
- Softbake time: 1min/um