Characterization algorithm of equipment-caused particle trend for LSI yield improvement

We often detect some particles on a wafer as “killer-defects” from inside-wall of a plasma etching chamber. For example, an insufficient cleaning (insufficient by-product removing) condition induces shorter “mean time between cleanings” (MTBC) and a damp (“half-dry”) chamber aggravates corrosion-induced particle outbreak in it [1,2]. The particle outbreak models by mathematical approximation can predict the chamber maintenance opportunity through the equations. This paper suggests some kind of mathematical differential equation models for an LSI yield improvement. These can characterize the particle density trends of wafers under different metal-etching conditions.