Trace Metal Contamination Detection
The ability to measure surface contamination is becoming more and more important in todays manufacturing line of wafers and semiconductor devices. One very sensitive technology called VPD (Vapor Phase Decomposition) prepares the wafer under test and collects the contamination for analysis down to a level of 1E7 atoms per cm².
Etching the Wafer Surface
The first step (PAD-Fume) uses a chemical reaction chamber, which allows etching of wafers with HF vapor. All system surfaces, which will come in contact with HF vapor, are optimized for ultimate cleanliness and safe handling of HF vapor.
Next step is to collect the contaminants and concentrate them in a small droplet, which is done with the PAD-Scan. It features various scanning patterns, advanced handling of droplets and preparation for the subsequent analysis.
Preparation for Analysis
Final step of the VPD process is the preparation of the droplet for analysis.
For ICP-MS analysis the PAD-Scan places the droplet in a vial, where it is diluted to a predefined volume. It is necessary to increase the volume according to the number of elements to be analyzed. The vials or the vial tray are transferred to the ICP-MS autosampler for analysis.
For TXRF analysis the droplet is placed by the PAD-Scan on a wafer for drying. The wafer is then transferred to the PAD-Dry, where the droplet is dried under vacuum and with moderate heat. This results in a solid residue, which is suitable for analysis by TXRF.