There's a buzz surrounding the topic of advanced process controls (APC) in the semiconductor manufacturing community; and like many freshly evolving, technologically-based concepts, the terms and applications are almost constantly being re-engineered.
In a nutshell, APC involves observing processes and wafers, and automatically making the changes to a particular process to instantaneously improve the process. The idea stems from Statistical Process Control (SPC), where product data, such as metrology readings, are analyzed to figure out whether a process is deviating from statistical norms.
SPC, however, is only capable of detecting a few deviations, and isn't capable of drilling down to the root cause of the deviation. APC is designed to pinpoint the cause; and, once detected, the product “recipe” can be modified in between runs to minimize process drift, leading to increased tool capability and higher yields.
The idea behind APC has made its way into the semiconductor-manufacturing mainstream, and is considered essential for 130 nm and 300 mm. Many fabs have installed home-grown solutions, while others are in the process of working with partners to help cut the cost of development and institute advanced APC for high-volume 300-mm manufacturing—the AMD, UMC joint venture in Singapore springs to mind.
While APCs are serving as the latest, process-specific weapon in wafer-level contamination control, the next battle will be tying together advanced automation, software, and in-process sensors to give fab managers unprecedented factory-wide control.
This month, APC and e-diagnostic specialist Alan Weber gives CleanRooms' readers a healthy overview of the terms that define APC, as well as an estimation of the time, money and personnel necessary to make it work (page 20). He strongly suggests that fab owners start working with suppliers as true “partners” on the path to APC integration. In a future issue of CleanRooms, Brooks Automation's James Moyne will offer a detailed look into factory-wide APC strategies.
These advanced technologies are going to take time and money on their way to changing how future fabs are designed and managed. We'll be following who picks up the tab and how quickly top management jumps on board as APC proponents make their pitch for further time, people and resources.
Michael A. Levans