Invisible Variations That Define Yield ：Practical Applications of SPC in Semiconductor Manufacturing

·Process Control Methods for High Yield and Stable Volume Production：

1. What Is the Real Risk in Semiconductor Manufacturing?

In semiconductor manufacturing, the most dangerous issues are often not obvious out-of-spec events, but invisible and persistent process variations.

Wafer fabrication involves hundreds to thousands of tightly coupled process steps, each operating within extremely narrow process windows. Even a minor parameter shift can be amplified through downstream processes, eventually resulting in:

• Yield degradation

• Parameter distribution drift

• Large-scale scrapping of high-value wafer lots

This reality determines that the semiconductor industry cannot rely on end-of-line inspection to ensure quality. Instead, it must continuously answer two critical questions during production:

• Is the process stable?

• Is the process still under control?

Statistical Process Control (SPC) exists precisely to address these questions and has become a foundational capability in modern semiconductor manufacturing.