Plade Metal

Preliminary and fundamental remarks:



  1. Introduction
  2. Standards at CMi
  3. Modus operandi

I. Introduction

The baths of the Plade Metal in zone 2 are arranged as depicted in figure 1 and they target etching / removal of Aluminum, Titanium and Silicon based layers (polymorphous, amorphous, oxides, nitrides).

Depending on the application, the bath may be fitted with a temperature adjusting system and with a circulating pumping system to activate etching.

FFR: Fast Fill Rinse (rough rinsing)
TT: Trickle Tank (fine rinsing)
Figure 1: Schematic of the Plade Metal bench
Bath N°4567

Circulating bath, heating system.
Diluted HF

Static bath, room temperature.
Reclaim (HF 50%)

Circulating bath.

Bath filled on demand.  
Poly Etch

Static bath, heating system.

Bath filled on demand.  
ApplicationPatterning / Removal of AluminumRemoval of Titanium or of native oxides or of DUV resist residues post-stripping on samples with metallic contentsRemoval of oxides (Thermal, TEOS, LTO or PVD oxide) and nitrides (stoechiometric or low stress)Removal of silicon based layers (amorphous silicon, semi-cristallin silicon and polycrystalline silicon or polysilicon)

II. Standards at CMi

MaterialBath N°ChemicalsMaskEtch rates (nm/min)T (°C)
H3PO4 85% + CH 3COOH 100% + HNO3 70%
Native SiO2
DUV resist residues post-stripping
5Diluted HF
SiO26 Reclaim
SiO2: 1500
Si3N4: 12
SixNy: 4
aSi, PolySi7Poly Etch

III. Modus Operandi

  1. Login on the Plade Metal using zone 2 computer
  2. If applicable, activate the circulating system and the heating system after having checked/changed the set point. If working at room temperature, there is no need to activate the heating system
  3. Adjust the timer according to the etch rate and the wanted result
  4. Load the wafers in one of the dedicated Teflon carrier and put the handle on
  5. Full protection is now required (apron, face shield, chemical gloves) before going further
  6. Once the wanted temperature is reached, open the lid of the bath and gently plunge the carrier into it
  7. Start the timer (with clean hand)
  8. Rinse the gloves and gently clean the bath’s surroundings with a moist paper (several cleanings/rinsings are necessary)
  9. Wait the end of the etching. Remove the individual protective equipment if waiting time is long. Please fill-in a chemical label to inform other users about your running process
  10. If needed, get ready with the individual protective equipment a few minutes before etching is supposed to finish
  11. A buzzer indicates the end; press once on the timer button to stop the buzzer
  12. Open the FFR lid and gently transfer the Teflon carrier from the etching bath to FFR
  13. Activate the FFR button
  14. If applicable, stop the heating system and the circulating system of etching bath
  15. During FFR, rinse the gloves and gently clean the etching bath’s surroundings with a moist paper (several cleanings/rinsings are necessary)
  16. When FFR is finished, switch the Teflon carrier to the Trickle Tank TT
  17. Once resistivity is reached (~12, put the carrier in the spin rinser and dryer SRD (the carrier’s handle must be removed)
  18. A recipe is already selected. Just press STOP and the START
  19. When the SRD is finished, get the wafers back and put the carrier where it belongs
  20. Carefully check the cleanliness of the wetbench before taking off the chemical protection (apron, face shield, chemical gloves)
  21. Perform wetbench logout on zone 2 computer


Any droplets of any kind MUST be removed from the wetbench before leaving it. Suspicious droplets must be cleared using a moist paper (2 to 3 cleanings/rinsings are necessary) and remaining water droplets must be removed with absorbent paper.