FABulous AMD

AMD maintains world-class manufacturing facilities (known as FABs) across North America, Europe, and Asia. In every AMD facility, advanced decision making and control technologies are used to optimise, integrate and automate material processing at nearly every stage in the manufacturing process.

Tom Sonderman, director of APM at AMD explained: "in the semi-conductor industry back in the early 90s there was a huge push in making cleanrooms cleaner and cleaner, reducing the particulates per square foot etc, and the reason for this was that historically the pods in which the wafers were made were open. "However, with our 200mm generation of wafer, a new technology came about with enclosed pods, meaning that rather than try and make the whole cleanroom as clean as possible, the idea came about to put the wafers in an environment that was separate from the rest of the cleanroom. The SMIF pods, as they are called, are Class 1 cleanrooms, which works fine, but the question now is centred on how the enclosed pods are interfaced with the tools." Over the past 15 years, experts at AMD have been developing a unique approach, known as Automated Precision Manufacturing (APM). APM-powered fabs are run by a 'central nervous system' consisting of more than 200 AMD patented and patent-pending technologies that allow for dynamic, real-time adjustments to the fab processes. This enables AMD to maximise quality and efficiency, while giving it the ability to introduce rapid, continuous product improvements without slowing production. In recent times it has become standard practice to automate the way materials move within a FAB. The technology, impressive as it is, is only half the equation. It's far more difficult to automate the way decisions are made within the FAB — literally teaching the fab to think for itself. APM has enabled automated decision-making in AMD's FABs at a level that is setting new precedents for the industry. As wafers travel throughout the FAB on their way to becoming product, they pass through a series of tools. Each tool processes the wafers according to a master recipe, developed initially by the process-technology teams. What makes APM unique is that any tool can alter the recipe used for each set of wafers it encounters, based upon information it receives from other tools in the FAB. Through these minute but critical recipe changes, the APM decision making software is designed to simultaneously maximise yield for each wafer and optimise performance for the resulting products. This process also reduces waste in the FAB and lowers costs.

Core intelligence The most marked differences between AMD's strategy and traditional approaches is the intelligence built into the company's three core automation systems: integrated production scheduling; advanced process control; and yield management systems: • integrated production scheduling: advanced logistics and dispatching technology control the flow of materials throughout the FAB, using logic-based decision making and precision tracking. Dynamic, real-time dispatch enables material and product flow to be modulated according to current customer needs or in response to any issues that arise within the FAB; and in AMD's next-generation FABs, APM will be able to anticipate problems and opportunities and adjust production proactively.

Performance parameters Using innovative software and an automated methodology, ADM's advanced process control helps ensure that each tool in the FAB is performing optimally at any given time. Currently, APM allows for control, fault detection, and diagnostics on a wafer-by-wafer basis. In the future, it plans to narrow that focus down to the die level, automatically pinpointing tiny areas on a wafer that could potentially reduce product performance, then adjusting tools throughout the fab to help keep that from happening; • advanced process control enables AMD to integrate transistor-level performance improvements into the FAB recipes approximately once per quarter to continually optimise transistor performance without slowing production. This leads to improvements in performance; • yield management systems: tracking and problem-solving technology is used to identify potential variations or defects on each wafer. Intelligent decision-making software then advises operations to make changes to tool operation throughout the FAB accordingly, thus minimising defective dies and increasing the number of quality yields. Sonderman said it is these components integrated within APM that distinguish the company's manufacturing capabilities: "in a FAB each process is controlled as closely as possible; material has to be moved efficiently throughout the FAB; and good yield enhancement engineering is essential to be able to continuously drive faster yield. Learning occurs as the process constantly changes." A hierarchical architecture to FAB-level control allows complex decision making to be taken out of the hands of the individual. Sonderman said: "we believe in performing late stage r&d in the FAB as this improves the manufacturability of the process, and enables us to leverage the learning capabilities from the previous technology." 300mm manufacturing is the wave of the future for the semiconductor industry, and AMD is perfectly poised to bring its benefits to its customers. The cornerstone of ADM's 300mm strategy will be the APM version 3.0. "It's one thing to run a 300mm FAB, it's another to run a highly efficient 300mm FAB. While 300mm facilities will be able to produce roughly 2.5 times more chips per wafer, the increased wafer-size and chip-design complexities also increase the challenge of ensuring that each of those chips operates within acceptable parameters," said Sonderman. "The wafers got so big that a FOUP (front opening unified pod) was developed as an advancement of the SMIF, which means the wafers can not only be moved from bay to bay, but within a bay. This direct tool delivery, our tool delivery automation, means that the need to have humans present at the tool to make the decisions when the lot arrives diminishes. "The whole system has developed so that automatic systems decide not only what the most efficient way to move the wafer from point A to point B is, but also what to do when it arrives at the tool, in terms of, for example, how it's processed and what recipe it uses."

Lot levels The number of useable chips achieved per wafer is commonly referred to as 'yield.' In future FABs, APM 3.0 will allow AMD to take full advantage of the superior yield potential offered by a 300mm manufacturing environment, dramatically reducing FAB waste and cost by extending the capabilities of APM 2.0, which currently allows for automated recipe control at the lot level. This means that the FAB can automatically adjust the recipe for each lot of 25 wafers to maximise the performance and die yields for that set of wafers. APM 3.0 is designed to take this capability a step forward, enabling true die-level control whereby the master chip-making recipe can be automatically and uniquely adjusted according to information gathered on every one of the hundreds of chips on each of the thousands of wafers in the FAB. While these technologies are cutting-edge, they are ultimately designed to fulfil one simple idea: efficiency in manufacturing The technology allows technicians at AMD to concentrate on what Sonderman calls "more strategic activities. They work in teams and do problem solving as opposed to standing at a tool, directing the process by entering the necessary information."

Lights out The removal of the restriction of having to perform the operations in a large cleanroom environment has moved wafer production away from the emphasis on how the humans will cope with the logistics to how far can a process be automated, and where savings can be made in the production run through using the FOUPs. "We had the phenomenon of contamination-free manufacturing, but didn't realise, at the time that the need for the automation we have seen would bring CFM to the fore in such a way," commented Sonderman. "The CFM now concentrates on the FOUP rather than the cleanroom, which can be downgraded, and the vacuum technology associated around the isolator, rather than the quality of the air in the room." Eventually Sonderman foresees a FAB that is in essence 'lights-out manufacturing'. "All the wafer movement will be automatic, as will the decision making. FAB 30 in Dresden is something like this, but it will also be like mission control at NASA. There will be screens with computer operators at the terminal ensuring the system is working well." The cleanroom production area itself will be entered by humans only when the tools need fixing, and even then they will not necessarily enter the critical area, but will change the broken parts outside the production area, in work bays.