ONE PRODUCT / ALL CHAMBERS: PRE-PROCESS

Indicators of pre-process excursions are

• Process instabilities at more than one chamber at the same time
• Dual signature of plasma parameter deviations due to lot splitting at the pre-process.

REASON	DESCRIPTION
Unstable etch process	Hard mask: Erosion of a non-resistant hard mask (from deposition as CVD) can change the process (chemistry) and the plasma parameters. In cases of significant mask erosion or even mask destruction, a large change of process properties (CD, yield ) as well as the plasma parameters can be expected.  Resist mask: The treatment of the resist mask (annealing), developer and the resist charge plays an important role for both the process and its plasma parameters. Why? Fragments of the resist mask are moved into the plasma and add additional organic chemistry to the usually inorganic process written in the recipe.
Example: Hard mask errosion
Unstable deposition process	The edge coverage of a deposition process can be unsufficient due to almost perpendicular side walls (from etching).