AZ 1512 HS

! 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 55
1.3 40 42 65
1.5 47 49 75
1.6 50 52 80
2 60 64 102
 2.6 80 85 124

* 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.

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):

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:

Sequence Number Recipe name PR thickness [µm] Total contact time [s]
0901
D4_HB_1512_1u1_PUD
1.1
~42
0902
D4_HB_1512_1u3_PUD
1.3
~48
0903
D4_HB_1512_1u5_PUD
1.5
~54
0904
D4_HB_1512_2u_PUD
2.0
~72
0905
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

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