Ceram Reveals the Cause of Corrosion during the Manufacture of Semiconductor Devices
The corrosion of semiconductor devices during fabrication or after packaging and shipment can lead to serious yield loss or long term product failure.
The Challenge
In this instance, corrosion occurred on bond pad regions and surrounding line features after wafer storage.
What Ceram Delivered
Ceram experts utilised optical microscopy and Dynamic Secondary Ion Mass Spectrometry (DSIMS) analysis to identify the nature and cause of corrosion.
The optical microscopy (Figure 1) revealed a concentration of corrosion sites and staining around the wafer edge, whilst the SIMS analysis uncovered the presence of ionic residues (Figure 2); including sodium, potassium, fluorine and chlorine in corroded/stained areas. The SIMS contaminant distribution imaging showed high localised concentrations of ionic residues in and around the corrosion sites.
The SIMS mass spectral and imaging analysis confirmed that the ionic residues remained in the wafer edge areas following insufficient washing. Prolonged contact of these residues with the device areas caused corrosion of the titanium silicide which led to formation of titanium oxide (Figure 3), and ultimately wafer rejection.
Value to the Client
Ceram was able to recommend that an improved washing/drying procedure would lead to significant reduction in wafer rejection.
