What Are the Defects of Wafer Dicing?
Wafer Dicing is the process of cutting individual components called die or chips from a wafer. Dicing allows manufacturers of integrated circuits and other semiconductor devices to harvest a large number of dice from a single silicon wafer.
Dicing can be done using a physical blade or laser ablation. It’s important to note that a blade dicing method requires an abrasive blade and can cause chipping and cracking of the die, which leads to lower yields.
In addition, a physical blade can cause vibration during the dicing process that can affect the quality of the chips. Choosing the right blade and optimizing the dicing process can help reduce vibration.
Another dicing technology that doesn’t use a physical blade is plasma dicing. This dicing technology uses a high-intensity plasma to remove material from the wafer’s surface, making it an alternative to both scribing and blade dicing.
Defects from dicing can range from minor flakes of silicon dust to major chipping and cracking of the die. These defects are often difficult to find and may affect the yield of the product.
Chipping and Cracking
Chipping can occur on the front (top) or back (bottom) surface of the wafer during dicing. The rate of chipping is a function of the blade grit, the feed rate and the cooling of the dicing lanes.
When a chipping defect is present, it can interfere with the connection between terminal pads. It can also affect the bond strength of wire bonds to these pads, which can negatively impact the reliability of the chip. Proper blade cooling and coolant nozzle adjustment can prevent this problem.
Other defects can include a hole that was not removed properly during dicing, or a chip that has been glued to the back of the die. These defects can affect the chip’s ability to function correctly, causing it to malfunction.
Dicing can be performed on a variety of wafer materials, including crystalline silicon, copper, gallium arsenide and lithium tantalite. However, the most common type of wafer material is crystalline silicon.
The thickness of a dicing wafer can vary from 100 microns to 30mm. The thickness of the dicing wafer can also be affected by the type of dicing method used.
As the diameter and thickness of dicing wafers increase, the risk of chipping or cracking increases. To prevent this, processes that better control chipping are becoming increasingly necessary.
Some dicing techniques, such as wax mounting and specialized tape, can help prevent bottom-side chipping from occurring. These methods are labor-intensive and can be more expensive than other dicing techniques, but they tend to result in superior bottom-side support.
A dicing technique known as “dicing before grinding” can also reduce the amount of physical damage to a wafer during dicing. This dicing technique is more advanced than the previous blading dicing method.
Dicing is a crucial step in the manufacturing of semiconductor devices. Whether the device is a microelectromechanical system (MEMS) or a traditional integrated circuit (IC), it needs to be accurately diced. Dicing equipment needs to be highly accurate and carefully monitored by experienced operators to avoid damaging the wafer.
