AZ 1512 HS is a thin photoresist designed for fast and reproducible photolithography, with high contrast and high development rate as well as improved substrate adhesion. It is the standard resist choice for photolithography steps with no strict requirements in terms of resolution, sidewall profile or thickness.
- Coating Tools : EVG 150; Sawatec SM-200
- Thickness range [µm]: 1.1 … 2.5
- Minimum CD / typical aspect ratio: ~ 1.5um / AR ~ 1:1
- Substrate topography: Planar or very low
- Recommended for: Wet etching
Process in CMi
! Cleanroom humidity warning !
Control of the relative humidity (RH) in photolithography zones is extremely critical. Stable and reproducible photolithography is expected within 38% to 48% RH range.
- In case of low RH (< 38%), the resist sensitivity and development rate decreases. It is then recommended to increase the exposure dose.
- In case of high RH (> 48%), the resist adhesion decreases. It is then recommended to do an additional bake (>10 minutes @ 150°C) before loading the wafers in the HMDS or coating equipment.
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 AZ 1512 HS spincurve is shown below, as well as process details for both automatic and manual coating.
Available thicknesses: 1.1 um / 1.3 um / 1.5 um / 1.6 um / 2 um / 2.6 um
Available databases (default: 4inch, check with the staff for 6inch):
- AZ1512_1to2um_Std_Dehydrate_x_y
- AZ1512_1to2um_Std_NoDehydrate_x_y (for HMDS-treated wafers)
- AZ1512_1to2um_GlassOnly_Dehydrate_x_y (for transparent wafers)
- AZ1512_1to2um_GlassOnly_NoDehydrate_x_y
- AZ1512_1to2um_Quartz_Dehydrate_x_y (for quartz, stacked glass-silicon wafer or SOI wafers. Softbake temperature is 118°C.)
- AZ1512_1to2um_Quartz_NoDehydrate_x_y
Available recipes:
| Recipe name | Spin speed [rpm] | Softbake time [mm:ss] | PR thickness [µm] |
|---|---|---|---|
| C4_D_1512_1u1_EC | 6000 | 01:30 | 1.1 |
| C4_D_1512_1u3_EC | 4000 | 01:30 | 1.3 |
| C4_D_1512_1u5_EC | 3000 | 01:30 | 1.5 |
| C4_D_1512_1u6_EC | 2800 | 01:30 | 1.6 |
| C4_D_1512_2u_EC | 1800 | 01:30 | 2.0 |
| C4_D_1512_2u6_EC | 1000 | 01:30 | 2.6 |
Spin time is 30 seconds. Softbake is performed at 250µm proximity. Softbake temperature is 110°C for all databases except for “Quartz” (121°C).
- Find the spin-coating speed “XXXX” [RPM] matching your target thickness from the AZ 1512 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: 100°C
- Softbake time: 30” + 30”/um
Exposure
The following table lists the recommend dose “to clear” for AZ 1512 HS coated on silicon wafers. It is recommended to perform a contrast curve / exposure matrix calibration for wafers other than silicon.
| Illumination: | Broadband* | i-line (355-365 nm) | h-line (405 nm) |
|---|---|---|---|
| Equipment: | MABA6, MA6 Gen3 (no filter) | VPG 200, MA6 Gen3 (filter), MJB4 | MLA 150 |
| PR thickness [µm] | Dose [mJ/cm2]+ | Dose [mJ/cm2]++ | Dose [mJ/cm2]+++ |
| 1.1 | 30 | 32 | Refer to Resist Tables |
| 1.3 | 40 | 42 | |
| 1.5 | 47 | 49 | |
| 1.6 | 50 | 52 | |
| 2 | 60 | 64 | |
| 2.6 | 80 | 85 |
* Mercury Lamp, Mask Aligner with UV400 configuration & no filter / + Based on intensity readings from Süss optometer broadband CCD / ++ Based on intensity readings from Süss optometer i-line CCD / +++ Based on MLA150 internal dose measurements
Development
The recommended developer for AZ 1512 HS is AZ 726 MIF (or MF CD 26), an organic solution based upon TMAH.
Development recipes for AZ 1512 HS (identical for all are AZ1512_1to2um_* databases) are listed below:
| Recipe name | PR thickness [µm] |
Total contact time [s] |
|---|---|---|
| D4_HB_1512_1u1_PUD |
1.1
|
40
|
| D4_HB_1512_1u3_PUD |
1.3
|
45
|
| D4_HB_1512_1u5_PUD |
1.5
|
50
|
| D4_HB_1512_1u6_PUD |
1.6
|
55
|
| D4_HB_1512_2u_PUD |
2
|
65
|
| D4_HB_1512_2u6_PUD |
2.6
|
75
|
The developement consists of a short spray dispense followed by puddle method. To maintain a high wafer throughput on the EVG 150, no hardbake is applied for standard AZ1512 recipes.
Development sequences for AZ 1512 HS are listed below:
| Recipe name | PR thickness [µm] | Total contact time [s] |
|---|---|---|
| D4_HB_1512_1u1_PUD |
1.1
|
~42
|
| D4_HB_1512_1u3_PUD |
1.3
|
~48
|
| D4_HB_1512_1u5_PUD |
1.5
|
~54
|
| D4_HB_1512_2u_PUD |
2.0
|
~72
|
| D4_HB_1512_2u5_PUD |
2.5
|
~87
|
Puddle method is used for the development with intermediates spin-clean steps. Hardbake of the resist is applied after the development, at 112°C for 2 minutes.
- Recommended developer: AZ 726 MIF (no dilution needed)
- Development time: 20″-30″/um
- Rinse: H2O 1min
IMPORTANT:
After development, it is mandatory for wafers to go through an additional rinsing step with DI water to avoid backside contamination and damage on equipments (chuck in etcher) in further processing steps. The water baths of the following wet benches can be used free of charge (5 min. billing delay after login):
- Z01 – Plade “Solvent” wet bench
- Z02 – UFT “Resist” wet bench