Advanced monitoring of trace metals applied to contamination reduction of silicon device processing

Metallic contamination has long been known to be a key detrimental factor to device yield, causing degradation of various electrical parameters depending on technology, design and device type [1-4]. Thus, device manufacturing control plans systematically include monitoring of metal contamination and , historically, this has been commonly achieved in-line on monitor wafers through a combination of Total Reflectance X-Ray Fluorescence (TXRF) and post anneal Surface Photo Voltage (SPV). In addition, DLTS (Deep Level Transient Spectroscopy) can be extremely powerful for specie identification [5] but is inherently slow not suitable for usage as a process control tool. On the other hand, VPD (Vapor Phase Decomposition) combined with ICP-MS (Inductively Coupled Mass Spectrometry) or TXRF is known to provide both identification and quantification of surface trace metals at lower detection limits that TXRF alone[6, 8]. We have also shown that VPD ICP-MS on thick oxide could be used for control of ion implant induced contamination [7]. Going further in terms of capability improvement, we are moving to a clean room compatible, automated VPD / ICP-MS running in full automation mode from wafer loading to results data upload. Ultimate detection limits can be reached, down to a few 10 at/cm2 for certain species. In addition, the system is capable, through the use of adequate chemistries to allow monitoring of either surface or bulk contaminants on wafers. In this presentation we will show preliminary data which illustrate the strong capabilities of the system in a R&D and production environment in comparison with TXRF, SPV and manual VPD