Explanation of different chemical mixes          Updated on 10/17/2002
  Silicon (100 or 111)

  Wright etch

  2 3.3% Cu(NO3) - 3 H2O - 2 HNO3  - 50% CrO3 - 2 Acetic 
 (60 mil 48% HF, 30 ml 69% HNO3, 30 ml 5 MCrO3[1 g CrO3/2ml H2O], 60 ml acetic acid)

 Note:Stable for 6 weeks.
 Different types of defects can be observed by varying etch time. 
 Typical 1 min.

 Warning: Extremely carcinogenic.
 Do not dispose in any drain. Must disposed by chemical handler.

  Good for decoration
 

  Silicon (100 or 111)

  Yang Etch

  1 15% CrO3 - 1 HF
 Typical 10-15 min high temp

 Note:Etch can't be stored.

   Silicon (100)

  Secco Etch

   1 4.4% K2Cr2O7 - 2 HF (44g K2Cr2O7 to 1000ml H2O, Nix with 1:2 with 48% HF)
  Typical 8-10 min.

  Note: Etch can't be stored.

   Silicon (100)

  Schmmel Etch

   1 7.5% CrO3 - 2 HF
  Typical 5-15 min.

  Note: Mix immediately prior to use.

   Warning: See warnings for Wright etch.
 

  Silicon (111)

  Sirtl Etch
  1 50% CrO3 - 1 HF (50g CrO3 to 100 ml H2O) with mix 1:1 with 48% HF
  Typical 3-5 min.

  Note: Mix immediately prior to use.

   Warning: See warnings for Wright etch.
 

  Piranha Etch 		    1 H2So4 - 1 H2O2
   Good for TiN2 etch
  BOE (6:1 BOE)    Buffered Oxide Etchant (6 mil Ammonium fluoride - 1mil HF)
  Modified BOE    Anmmonium Fluoride (60%), Phosphoric Acid (80%), Anmmonium Phosphate Dibasic
  Acqua Regia    3 HCL  - 1 HNO3 (3 mil HCL, 3 mil HNO3)
   Typical 10 sec
    Note: Will attack metallization
    Check: Optically
    Good for Au and Pt etch
  Dash Etch    1 HF - 3 HNO3 asetic
  CME   Posophlic 73.8%, Nitric acid 0.83%, Acetic 6.6%(酢酸）
  16-1-1-2 Aluminum etchant
  20 to 1 etchant		   20 to 1 etchant
  (20 mil HF, 1 mil Nitric)  1.5 Sec for oxide defusion poly silicon etch. 
  Good for x-section stain for n-Si
  Poly-Si etchant
  (7-3-1)/(10-40-1)		   7/10 mil acetic, 3/40 mil Nitric, 1 mil HF
  7-3-1 : good for poly Si etch, 10-40-1: good for Dilute poly-Si etch