by Debra Vogler, Senior Technical Editor, Solid State Technology
Some speakers at last week’s ISSM conference (Oct. 15-17, Santa Clara, CA) speculated that the industry’s eventual transition to 450mm wafers would offer a chance to reformulate the concept of the fab. Not all IC manufacturers would be in the elite group that would benefit from the transition. However, most chipmakers would welcome the opportunity to add capacity in existing facilities while decreasing cycle times.
As a number of presenters at ISSM made clear, there is a movement in the industry that favors the ability to utilize small-lot (<25 wafers) manufacturing as a way to provide fab agility and drive down cycle times. Aquest Systems believes its vehicle-free transport (VFT) technology, FabEX Transporter, released in May of this year, can change the way existing or new fabs implement automation, and enable both small lots and a possible wafer size transition.
The company’s AMHS technology can be deployed in new fabs, but was also designed to work with existing automation systems, so fabs constrained with current layouts and tools can add capacity without making major changes. Available with straight segments of varying lengths and “turn” segments (0-270° of rotation), stocker and overhead transport (OHT) I/O, the system mounts directly under the OHT. According to the company, the controls leverage current ASIC, VoIP, and Ethernet technologies.
The breakthrough with the VFT concept is the decoupling of transportation with the loading operation — a concept that ISSM presenter Mike Brain, Aquest VP of technology and marketing, sees as one of the ways in which “no-wait manufacturing” can be used to drive down cycle time.
Brain told WaferNEWS that he envisions a time when automation will be tied more closely with process and metrology equipment. A key issue is that fabs, especially foundries, want the flexibility to start <25 wafer lots, but those smaller lots require higher movement capacity, and therefore, more FOUPs handled by equipment front-ends. "Double the number of FOUPs at the same wafer out rate translates to twice as much FOUP traffic," he said. This would cause even more traffic jams with OHTs, he noted. "Today, most people believe that an OHT system could handle 13 wafer lots, but it means putting up double the number of vehicles." It is this traffic congestion that Aquest wants to address with VFT.
Additional AMHS components in the FabEX product line are expected to be released in 1Q08. Brain couldn’t provide details at this time, but acknowledged that these components are also designed to reduce the need for wafers to wait for material handling systems, and for equipment to wait for wafers. — D.V.