DAG810

The DAG810 is a compact automatic grinder for silicon, III/V materials (GaN, GaAs, InP), and various glass types including fused silica, float glass, and pyrex. The DAG810 thins single wafers, stacked wafers, or chips from a few square millimeters up to full 8-inch wafers.^[1]

The DAG810 clamps workpieces to a rotating chuck table. A rotating diamond wheel sweeps across the center of the chuck table. The spindle carrying the wheel moves downward to remove material from the surface of the workpieces. Water cools the workpieces and clears particles and mud generated during grinding. Fine control of the spindle vertical displacement, along with precise angular adjustments with the chuck table, produces a flat ground surface with a total thickness variation (TTV) close to one micron.^[1]

The thickness reduction is accomplished in two or three different phases by decreasing the feed speed of the grinding wheel as the finishing thickness approaches. The DAG810 achieves a grinding speed as high as 30 microns per minute and a surface roughness less than 100 nm. The equipment includes a universal vacuum chuck table for 4-inch, 5-inch, 6-inch, and 8-inch wafers, a mechanical frame clamp for UV-tape mounted wafers or chips, a high-rigidity low-vibration spindle, and dedicated grinding wheels for different materials. Real-time probe-height measurement is available for 4-inch wafers and larger. An LCD touch screen provides operation control. Some manual operations are required: wheel selection and installation, axis initialization, probe-height initialization, wafer thickness measurement, workpiece loading and unloading, and UV-tape mounting, cleaning, and curing.^[1]

The DAG810 is typically employed in a process that includes mounting workpieces on UV-sensitive tape using a manual wafer mounter (Powatec P-200). After grinding, the workpieces are cleaned and dried in an automatic cleaner (Disco DCS1440) that uses atomizing cleaning and fast spinning. The cleaned thin workpieces are then safely released by exposing the tape to UV light using a manual UV irradiation system (Powatec U-200). A technique called Dicing Before Grinding (DBG) can be used: dies are separated by grinding after half-cutting the workpieces to relieve edge stress.^[1]

The DAG810 grinds single wafers of silicon (100 mm to 200 mm diameter), gallium nitride (GaN) on 2-inch wafers, and glass wafers including fused silica, pyrex (borosilicate), and soda-lime glass. The DAG810 also grinds stacked wafers such as pyrex/silicon anodic bonds, silicon/silicon bonds, and silicon/glass bonds. Chips mounted on UV tape, including GaN and silicon chips of various sizes down to a few millimeters, can be thinned. Tested reductions include thinning silicon wafers from 525 µm to 100 µm and from 625 µm to 200 µm, thinning GaN wafers from 320 µm to 100 µm, and thinning stacked silicon to 30 µm or 50 µm.^[1]