As bonded wafer processing applications become more common, edge-oriented process technologies increase in importance. Axus Technology delivers process development services and process equipment that is used to address edge processing requirements. Depending on the exact process need, edge processing solutions are generally described as Edge Grinding or Edge Trimming applications.
Edge Grinding has always been an essential part of substrate manufacturing and is becoming more common in device processing, as well as for bonded wafer processing. Edge grinding generally provides a rounded or “bullet-nose” profile for silicon, and a “bevel-nose” profile for SiC and Sapphire. This process is also known by the term Edge Profiling. Backgrinding of a substrate can result in a sharp edge on a substrate, similar to when a wafer is first sawn from a boule. The sharp edges are mechanically weak and can lead to edge chipping and wafer breakage. Bonded wafer assemblies can also have sharp or slightly misaligned edges that can benefit from applying an edge grinding process.
The process of edge grinding strengthens the edge of the substrate and minimizes edge flaking, an important factor considering the hundreds of wafer transfer sequences in modern manufacturing. In addition, Edge Grinding can be an effective method for addressing the slight “out of round” nature of bonded substrates. Axus Technology delivers edge grinding processes on tools supplied by several manufacturers. With solutions for a wide range of substrates, from Si and various alternative semiconductor substrates, through SiC and Sapphire, and including bonded assemblies, Axus can deliver the tools with the appropriate process expertise and consumables.
Edge Trimming is generally applied to bonded wafer assemblies. Applying an edge trimming process generally removes a small amount of the diameter of the device wafer but not the carrier wafer. This eliminates the narrow edge area of the device wafer where bonding voids can often occur thus minimizing the area that is most likely to suffer chipping or other process issues. An additional benefit is that the wafer edge is generally the area of the wafer suffering the greatest non-uniformity. Removing this area is often beneficial for subsequent wafer bonding steps.
Axus Technology brings increased value to our customers by adding Edge Trimming to several models of wafer backgrinding tools, including the Strasbaugh 7AF and Strasbaugh 7AA and Disco 850 backgrinders. The result is that users gain the additional edge trimming capability by leveraging a single tool for multiple applications.
Please contact Axus Technology and learn more about this and our many other polishing, grinding, and cleaning process capabilities.