CONDITIONING / ONE PRODUCT: PRODUCT AND PROCESS MIX

Process mix means using recipes with different chemistries in one chamber. This usally leads to first wafer effects.

If a product or process mix is unavoidable, the first wafer effect can be controlled by product management. The optimum of the product or process switch depends on tool and process. The following link shows a comparison of continuous processing or almost dedicated chamber operation.



The deposition of byproducts at the chamber wall and in the vacuum system leads to memory effects - when the underlying chemistry is changed. This is due to diffusion of 'old' byproducts from the pumping system back into the chamber. It takes sometimes more than one wet clean cycle to reach the new chemical equilibrium. The example below shows that about 4000 wafers needed to get a stable process.