Aluminum Etchant Type F

Aluminum Etchant Type F is a stable preparation used to etch aluminum or aluminum-silicon metallizations on silicon devices and in integrated circuit applications. Aluminum contacts are defined and interconnections are formed. Aluminum Etchant Type F is formulated with unique properties easily overcome many of the difficulties experienced in aluminum etch processes such as residue. The aluminum metallization and etching process using photo-lithographic techniques is basic to the semiconductor and microelectronic technology.
The Aluminum Etchant Type F is highly compatible with many of commercial photoresists and permit delineation into high resolution patterns. Metal line width of 1 mil and separations less than 5 microns are feasible. The high resolution is practical with the Aluminum Etchant Type F because lifting of photoresist patterns does not occur and undercutting is minimized.

• Aluminum Etchant Type F should not be used or stored in glass or Pyrex containers.
• Aluminum metallizations up to 25,000 A are vacuum deposited on the silicon slice, coated with a photoresist, and UV exposed using an appropriate photographic mask. The resist is developed to protect the aluminum where interconnections are desired. Then the unprotected areas of the aluminum are removed by etching with the Aluminum Etchant Type F, followed by a water rinse.
• Etching time is dependent upon the etchant temperature and the aluminum film thickness. When etching thick aluminum films, a higher etch rate is required; thus a higher etchant temperature should be used. Likewise, for thinner aluminum films, slower etch rates are desired and a lower etchant temperature should be chosen.
• At a specific etchant temperature, the etching time is given by the following formula:

Etching time (second) + Film Thickness (Å)/ Etch Rate (Å/sec)
where Etch Rate at 25°C 30 Å/sec; at 40°C 80 Å/sec.