Process for depositing aluminum nitride (AlN) using nitrogen plasma sputtering

DETAILED DESCRIPTION In accordance with the present invention a novel process for depositing a thin film of aluminum nitride (AlN) is provided.
Simply stated, with the process of the invention an aluminum nitride (AlN) film is deposited in a conventional sputtering apparatus by sputtering an aluminum target with energetic nitrogen ions generated in a nitrogen plasma.
A single gas (i.
e.
nitrogen) is used as both the reactive gas and as the sputtering gas.
The process of the invention is especially suited to semiconductor manufacture for forming an aluminum nitride (AlN) film having a high purity.
One such application, is in the formation of an etchstop layer during semiconductor fabrication.
A representative process sequence can include the following steps: 1.
Device formation on a silicon substrate using standard processes.
2.
Aluminum nitride (AlN) deposition using nitrogen plasma reactive sputtering with nitrogen used as both the reactive gas and as the sputtering gas.
3.
Dielectric or doped oxide deposition.
4.
Photopatterning to define the regions in the oxide layer to be etched at contact etch step.
5.
Contact etch through the oxide layer using reactive ion etch.
The etch will stop on the aluminum nitride (AlN) layer.
Due to the high etch selectivity of aluminum nitride (AlN) to oxide (oxide etches much faster than aluminum nitride), the etch will stop on the aluminum nitride (AlN), leaving the underlying Si junction intact.
6.
Photoresist strip.
7.
Strip off the remaining aluminum nitride (AlN) layer using either wet or dry etch.
8.
Standard processes from then on.
This is but one example wherein an aluminum nitride (AlN) layer can be formed in accordance with the invention during semiconductor manufacture.
Other objects, advantages, and capabilities of the present invention will become more apparent as the description proceeds.