Wafer dicing is a critical process within the semiconductor manufacturing. It’s the step where silicon dies are separated from each other. Semiconductor wafer dicing techniques have evolved over time, from traditional blade dicing to more advanced methods such as laser and plasma dicing, each with its own benefits and applications.
Dicing Techniques
Silicon wafer dicing is a critical process in semiconductor manufacturing, where a larger wafer—typically made of materials like silicon or gallium arsenide—is precisely cut into individual ASIC/chips. This process is necessary to create the discrete dies that are then packaged and assembled into semiconductor packaging such as QFN and BGA. Today. manufacturers employ a broad range of dicing techniques.
Wafer dicing methods include mechanical blade dicing, laser dicing, and plasma dicing. The selection of a dicing process depends on several factors such as the type of material, desired cutting speed, production costs, and the impact on manufacturing yield. To protect the wafer surface, wafers are often mounted on UV Tape or attached to a metal frame during the dicing process.
Blade Dicing
Mechanical blade dicing, or simply blade dicing, uses a high-speed rotating blade called a dicing saw. Dicing blades, often made of diamond or other hard materials, make cuts or streets through the wafer’s surface. This traditional method is known for its reliability and is suitable for a wide range of semiconductor materials. The process requires adjusting feed rates and blade types according to the wafer material to minimize thermal damage and improve yield. Blade dicing is often carried out with the wafer mounted on a dicing frame or held in place with a sticky tape, such as UV Tape. While blade dicing is cost-effective and well-established, it can cause wafer chipping and may not be ideal for materials that are brittle or sensitive to mechanical stress.
Laser Dicing
As one can imagine, laser dicing employs a focused laser beam to cut through the wafer. This technique offers a high degree of precision with less physical stress on the material, making it suitable for delicate or hard-to-cut materials like gallium arsenide.
Laser dicing allows for rapid processing and the ability to make intricate cuts but can be more expensive in terms of both equipment costs and operation. Laser dicing methods include stealth dicing, which creates a modified layer inside the material allowing it to be cleanly broken apart, thereby reducing surface damage and increasing yield.
Plasma Dicing
Plasma dicing uses a plasma etching process, which is a dry, chemical-based method that etches the material rather than cutting it with a physical blade or beam. This can result in smoother edges and lower mechanical stress during dicing. The plasma dicing process is known for its ability to create exceptionally narrow streets, thereby saving valuable wafer space and increasing the number of dies per wafer. It can also process an entire wafer—known as single wafer processing—at once, which can increase throughput. Plasma dicing is particularly suitable for wafers with complex or delicate circuit designs and benefits from typically lower production costs. However, the initial investment for plasma dicing systems can be significant, and the process requires specialized equipment and techniques.
In the following picture you can see 2 types of machines for 200mm and 300mm wafers.
Credit Photo: Accretech
Wafer Dicing Process
The process follows several key steps: First, the wafer is cleaned and inspected for impurities or defects that could affect the dicing outcome. Next, the wafer is mounted on a dicing tape that holds it securely during the cutting process, often with a backing material such as a metal frame for additional support. The dicing pattern, determined by the circuit layout, is then programmed into the dicing equipment. The wafer is diced using one of the various available techniques, depending on the material composition, size, and application requirements.
Each cut must be precise to avoid damaging adjacent circuits, and considerations must be made to account for the kerf, the amount of material removed during the cutting process. After dicing, the individual dies are inspected once more before being packaged or subjected to further testing. It’s a process that balances precision with efficiency, seeking to maximize the number of viable dies produced while minimizing waste and damage.
Material Considerations
When dicing wafers, the type of material significantly affects the dicing method chosen. Silicon wafers are the most common, but other materials such as gallium arsenide, sapphire, and silicon carbide also find use in specific applications. Each material presents its own challenges. For instance, materials with higher levels of brittleness are more prone to chipping and cracking and thus might benefit from a non-contact dicing approach such as laser or plasma dicing.
Moreover, the purity and defect density of the material can determine how much stress the wafer can withstand during the process. This, in turn, dictates the need for adjustments in blade type, cutting speed, and process parameters to avoid inflicting damage to the circuits on the wafer.
Wafer Size and Thickness
The wafer’s size and thickness are critical factors in determining the dicing strategy. Generally, wafers can range in size from small diameters like 100mm to larger wafers of 300mm or more. Thicknesses also vary, with ultra-thin wafers requiring more delicate handling to prevent warping or breaking.
Different dicing tools and blades can accommodate these variations in size and thickness. For instance, thicker wafers require deeper cuts and possibly different blade types to ensure a clean separation, while thinner wafers benefit from precision methods like stealth or laser dicing to mitigate any potential damage caused by stress during the cutting process.
Dicing Blades and Equipment
Dicing blades are specially designed for the wafer dicing process, with materials like diamond being a frequent choice due to its hardness and durability. The type of blade used is matched to the wafer material and the desired quality of the cut. Dicing equipment includes advanced machines like dicing saws for mechanical cutting and highly calibrated lasers for the more technologically sophisticated laser dicing method.
A range of equipment is available for different scaling needs, from manual setups for R&D or low-volume production to automated systems capable of handling high-volume manufacturing. With developments in dicing technology, newer systems are now able to integrate inspection and metrology capabilities, further enhancing the efficiency of the dicing process.
Dicing Techniques for Different Materials
Different semiconductor materials require tailored dicing techniques that account for their physical properties. For example:
- Silicon wafers: These can typically be handled with mechanical blade dicing due to their relatively robust nature, but laser dicing is also an option for more complex or thin wafers.
- Gallium Arsenide (GaAs): A material that is more brittle than silicon and may better benefit from processes like laser dicing to reduce mechanical stress.
- Sapphire: Often used in LED production, sapphire is exceptionally hard, making laser dicing techniques, which can precisely cut tough materials without excessive pressure, advantageous.
- Silicon Carbide (SiC): A material commonly found in power devices which is hard and requires advanced dicing blades or lasers capable of delivering high energy to make clean cuts.
Innovations in dicer technology continually expand the capabilities for handling a wider range of semiconductor materials, making the selection of a dicing technique a constantly evolving decision based on the latest advancements in the field.
Wafer Dicing Services
A wafer dicing company is able to provide with wafer dicing services. And very often to be offering a quick turn around service. These wafer dicing companies have the expertise and equipment required to efficiently and accurately dice wafers using the methods described above.
Some wafer dicing companies can also offer a 300mm wafer dicing service, if you are interested in getting a quote, please contact us and we can link to to wafer dicing service company with 300mm capabilities.
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