Why are wafers (silicon wafers) getting larger?

In the production process of silicon-based integrated circuits, the silicon wafer is one of the key materials. The diameter and size of the wafer play a crucial role throughout the entire manufacturing process. The size of the wafer not only determines the number of chips that can be produced but also has a direct impact on cost, capacity, and quality.

1. Historical Development of Wafer Sizes In the early days of integrated circuit production, the diameter of wafers was relatively small. In the mid-1960s, the diameter of silicon wafers was typically 25 mm (1 inch). With technological advancements and the increasing demand for more efficient production, wafer sizes have continuously grown. In modern semiconductor manufacturing, 150 mm (6 inches), 200 mm (8 inches), and 300 mm (12 inches) wafers are commonly us

This change in size brings significant advantages. For example, a 300 mm silicon wafer has more than 140 times the surface area of a 1-inch wafer from 50 years ago. This increase in surface area has greatly improved production efficiency and cost-effectiveness.

2. Impact of Wafer Size on Yield and Cost

1. Yield Increase
   Larger wafers allow for the production of more chips on a single wafer. Assuming the structural size of the chips (i.e., the design and physical space required) is the same, a 300 mm wafer can produce more than twice as many chips as a 200 mm wafer. This means that larger wafers can significantly boost yield.

2. Cost Reduction
   As the wafer area increases, yield increases, while some fundamental steps in the manufacturing process (such as photolithography and etching) remain unchanged regardless of wafer size. This allows production efficiency to improve without adding process steps. Additionally, larger wafers enable the distribution of manufacturing costs over a greater number of chips, thus reducing the cost per chip.

3. Improvement of Edge Effects in Wafers When the diameter of the wafer increases, the curvature of the wafer edge decreases, which is crucial for reducing edge loss. Chips are typically rectangular, and due to the curvature at the wafer's edge, it may not be possible to accommodate complete chips. In smaller wafers, edge loss is greater due to higher curvature. However, in 300 mm wafers, this curvature is relatively smaller, which helps minimize edge loss.

4. Wafer Size Selection and Equipment Compatibility The size of the wafer affects equipment selection and production line design. As wafer diameters increase, the equipment needed must also be adapted accordingly. For example, equipment for processing 300 mm wafers typically requires more space and different technical support and is generally more expensive. However, this investment can be offset by higher yields and lower per-chip costs.

In addition, the manufacturing process for 300 mm wafers is more complex compared to 200 mm wafers, involving higher-precision robotic arms and sophisticated handling systems to ensure the wafers are not damaged throughout the production process.

5. Future Trends in Wafer Sizes
Although 300 mm wafers are already widely used in high-end manufacturing, the industry continues to explore even larger wafer sizes. Research and development for 450 mm wafers have already begun, with potential commercial applications expected in the future. The increase in wafer size directly enhances production efficiency, reduces costs, and minimizes edge losses, making semiconductor manufacturing more economical and efficient.

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