Anisotropic wet etching

• Post Date:

  Dec 04,2009

• Expiry Date:

  Dec 04,2010

• Detailed Description:

  Some wet etchants etch crystalline
  materials at very different rates
  depending upon which crystal face
  is exposed. In single-crystal
  materials (e.g. silicon wafers),
  this effect can allow very high
  anisotropy, as shown in the figure.
  Several anisotropic wet etchants
  are available for silicon. For
  instance, potassium hydroxide
  (KOH) can achieve selectivity of
  400 between <100> and <111>
  planes. Another option is EDP (an
  aqueous solution of ethylene
  diamine and pyrocatechol), which
  also displays high selectivity for
  p-type doping. Neither of these
  etchants may be used on wafers
  that contain CMOS integrated
  circuits. Both of them etch
  aluminium, commonly used as a
  metallization (wiring) material.
  KOH introduces mobile potassium
  ions into silicon dioxide, and EDP
  is highly corrosive and
  carcinogenic. Tetramethylammonium
  hydroxide (TMAH) presents a safer
  alternative, although it has even
  worse selectivity between <100>
  and <111> planes in silicon than
  does EDP.
  

• Company:

  Suzhou CSE Semiconductor Equipment Technology Co., Ltd.     [ China ]        

• Contact:

  Amy Chang

• Tel:

  +86-18913168552

• Fax:

  +86-18913168552

• Email:

  amychangcse@yahoo.com