Wafer downsizing is accomplished by entering coordinates into a program that guides the laser cutting. The wafer is cut with either multiple holes or shapes, or the entire wafer itself is cut. Using a wafer’s notch or flat as a starting point allows the wafer to maintain the same orientation after cutting. If the application requires, it is possible to re-cut wafer orientation notches or flats. Laser cut down yields a diameter tolerance of 0.05mm. In order to protect against contaminants during the cutting process, a vacuum collects particles and dust as the laser moves through the wafer. In some applications, a layer of photoresist is placed on the surface of the wafer prior to cutting to further protect it from particles and other contaminants.
The Synova laser microjet uses a 1064nm wavelength laser guided by a high-powered stream of de-ionized water to cut silicon. There is minimal thermal damage to the substrate because the water cools as it guides the laser. This method is particularly advantageous for thin wafers, patterned wafers, and wafers with limited thermal capabilities. The wafer orientation notches can be added or re-cut during processing. A diameter tolerance of +/- 0.2mm is achievable in this process.