Determining the capacity components of different classes of multi chamber tools

Multi chamber tools offer the benefit of performing multiple processes within a given mainframe. Typical tool configurations range from two to four process chambers attached to a mainframe that share a wafer delivery system and are capable of running a product through multiple chambers while performing multiple process steps. While trying to measure capacity limiting factors on multi chamber tools, three tool classifications arose. The most basic is a simple serial processing tool. Product is loaded exclusively in one place and follows one path through the tool. The second classification has a number of identical chambers and each wafer visits only one chamber on a next available basis. Tools that run next available chamber are analyzed via a full-tool-equivalent (FTE) methodology to combine chamber and mainframe availabilities. The third and most complex classification are multi chamber tools with multiple loading possibilities and multiple paths through the tool. The solution for these tools is the creation of another capacity state to represent the blocked or busy state of individual chambers. As only two lots can typically be loaded on a multi chamber tool at a time, another capacity component ('blocked/busy') was needed to identify time when two lots (or the maximum allowable) are loaded on the tool and nothing else can be loaded. This paper describes the blocked/busy state and how it is used in understanding capacity limiters and improving productivity for multi chamber tools. After first understanding key capacity components for these tools, recommendations can be made for configuration and usage.