Aluminum Etchant Type D
TRANSENE Aluminum Etchant is stable, non-toxic preparations used to etch aluminum metallizations on silicon devides and in intergrated circuit applications. Aluminum contacts are defined and interconnections are formed.
This Aluminum Etchant formulated with unique properties easily overcome many of the difficulties experienced in aluminum etch processes.
Metal line width of 1 mil and separations less than 5 microns are feasible. The high resolution is practical with TRANSENE Aluminum Etchants because lifting of photoresist patterns does not occur and undercutting is minimized.
Furthemore, the etchants do not attack silicon, silicon dioxide, silicon nitride or nichrome resistor films. This aluminum etchant is offered for use in microelectronics. Type D is recommended for use on gallium arsenide and gallium phosphide devides to avoid attack of the etchant on the intermetallic compound.
It is also recommended for etching aluminum metallizations on nichrome thin film resistors.
COMPATIBILITY :
| | Al | Au | Cr | Cu | Ni | Si | Si3N4 | SiO2 | Ti | W | GaAs | Ta/TaN |
| Al Type D | Etch | Ok | Slight | Ok | Ok | Ok | Slight | Ok | Ok | Ok | Ok | Ok |
Etch = significant attack / Slight = Slight attack / Ok = No Attack / Surf ox = Surface Oxidation /
Corrode = Surface Corrosion
Selectivity of about 10:1 for "slight" and selectivity > 1000:1 for "ok" or "no attack"
PROPERTIES :
| | Aluminum Etchant Type D
|  |
| Appearance | Light green/yellow |
| Specific Gravity @25℃ | 1.50 |
| Boiling Point | 150℃ |
| Resist Compatibility | Nega & Posi |
| Tank | Glass or polypropylene |
| Etch Rate @ 25℃ | 40 Å/sec |
| Etch Rate @ 40℃ | 125 Å/sec |
| Etch Rate @ 50℃ | 200 Å/sec |
APPLICATION :
• Aluminum metallizations up 25,000Å are vacuum deposited on the silicon slice, coatd with a photo
resist, 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 TRANSENE Aluminum Etchant, 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 sholuld be chosen.
