Dave Chapek, Semitool, Montana, USA

ABSTRACT

Front End Of Line (FEOL) surface preparation is about to grow up, and an entire industry is uncomfortable. The RCA clean is universally recognized as the reference standard in surface preparation.  It has been the core methodology for critical cleaning applications since it was introduced shortly after humanity first oxidized silicon and made planar MOS transistors.  Historically, the surface preparation unit process has demonstrated extraordinary power to disrupt factory operations and degrade product quality, risking incapacitation of the entire factory.  Subsequently, integrated device manufacturers have developed a virtually instinctive fear surrounding surface preparation, resulting in a daunting barrier to change.  We have all been grateful for the intrinsic elegance and functionality of the deceptively simple RCA chemical sequence that has served the industry for decades.
However, the twin forces of change at the heart of Moore’s Law, technology and productivity, are now revealing the limitations of the RCA sequence that has been an essential part of wafer fab operations.  As has been pointed out many times by many people of great accomplishment, we find ourselves facing the necessity of changing the very essence of the batch RCA cleaning sequence from an equipment perspective as processes push into the deep sub-50nm technology realm.
The question is:  What does that mean?