Benchmarking Helps 200mm Manufacturers Increase Output and Reduce costs
Sangeeta Dixit and Helen Armer
200mm semiconductor manufacturing fabs must produce parts at the absolute lowest possible cost given the highly competitive markets for the analog, power, MEMs and other widely used products they manufacture.
But there are a number of reasons why achieving cost targets can be difficult. For one thing, such fabs typically run older equipment, including tools purchased from third parties. In addition, sometimes multiple generations of equipment are used for the same application, leading to many possible variations among the tools being used, and some may not even have the latest hardware or software configuration. All this makes it difficult for the fabs to establish realistic goals for tool output improvement, process yield and cost reduction.
Moreover, as technology requirements become more stringent, some 200mm customers need to extend the performance of their tools beyond their design specifications.
The Applied Materials knowledge base has become an enabler for the company’s FabVantage consultants who work with customers to identify, benchmark and resolve a wide variety of tool and fab productivity issues. It comprises benchmark data for 200mm and 300mm tools gathered from the installed base of >25,000 Applied Materials semiconductor production tools.
The knowledge base also includes tool documentation such as equipment and process manuals, schematics, continuous improvement projects (CIPs) as well as Applied Materials best known methods (BKMs) for recipes, process window sensitivity, equipment constants, maintenance procedures, and troubleshooting guidelines.
A recent addition to the knowledge base is a library of sensor and event data collection plans for every tool type, with a sensor prioritization scheme that identifies sensors known to have caused unit process yield losses. These collection plans allow Applied engineers to rapidly identify hardware malfunctions and excursions. Together with our databases of BKMs and lessons-learned, we can quickly get to the root cause of equipment failure and misprocessing.
Benchmarking is the First Step
Benchmarking is typically used during the Discovery stage of a FabVantage consulting engagement to help determine a customer’s gap to world-class performance (see figure 1.) Here are some examples to show how this approach is implemented, and to illustrate its effectiveness.Figure 1. FabVantage phased engagement process
For example, in one case, a 200mm fab was unable to meet output requirements for DPS metal etch. FabVantage consultants benchmarked tool uptime using data from the same tool in comparable fabs running the same application and technology node (e.g., 90nm data from 200mm logic fabs is benchmarked against 90nm data from other 200mm logic fabs, but not against data from the same tool in a NOR fab, or in some other production environment). FabVantage consultants found that the customer’s uptime was below the range that the knowledge base indicated is typically achievable. Additional benchmarking of scheduled (SDT) and unscheduled (UDT) downtimes indicated that the customer’s unscheduled downtime was much higher than the norm for this tool, accounting for most of the uptime entitlement gap. This enabled the FabVantage consultants to quantify the scope for improvement.
A subsequent tool assessment, using many of the knowledge base tools described above, allowed Applied’s consultant to develop an output improvement roadmap for the customer that identified multiple solutions, including BKM maintenance practices, equipment constants and recipe modifications to quickly reduce the UDT.Figure 2. Benchmarking showing scope for unscheduled downtime improvement
Another example of the power of benchmarking comes from the fact that tool documentation in the knowledge base facilitates tool assessments for PMs, system parts, equipment constant settings, recipes, and other key unit process and equipment configurations. Any deviation from BKMs can be investigated and appropriate recommendations made.
In one case a customer was suffering from yield loss due to defects from a Centura Etch tool and had to shut down the tool frequently. Using information from the knowledge base, FabVantage consultants determined that the customer was not using Applied’s recommended maintenance practices, and that this was the root cause of the defects. After implementing BKM electrostatic chuck cleaning procedures and improved procedures for inline detection of defects, the defect levels dropped to acceptable levels (see figure 3).Figure 3. Defect reduction after implementation of FabVantage-recommendations
In another example, a tool assessment at a 200mm IDM revealed cleaning and seasoning routines that were both incorrectly configured and run too frequently. Simply modifying the cleaning and seasoning timing—with no change to the recipes themselves—led to a greater than 10% improvement in system output.
For another customer, Applied’s consultants found that an unconventional faceplate and blocker plate were the root causes of excessive defects on a 200mm Producer Silane tool. Once these were replaced with BKM parts, the defect levels dropped and product yield improved.
In addition, FabVantage consulting services are helping customers increase overall efficiency and output by addressing factory-level issues such as capacity shortages, long cycle times, high wafer costs, line imbalances, high levels of work-in-process (WIP) and high variability, among others. The knowledge base information is leveraged for assessment of their current fab operations practices and gaps to BKM’s. After identifying issues that are having major impacts on fab productivity, a roadmap for improvement is created based upon comparisons of the data collected with benchmarks and best practices. Probable causes for underlying performance gaps then are outlined, and a proposal is presented to the customer.
Applied Fabvantage Workshops Help Identify Opportunities
The Applied knowledge base is also used to develop materials for customized FabVantage workshops, tailored specifically for customers who want to improve their tool performance or transition to newer technology nodes. These workshops are especially useful for 200mm customers. Such workshops include comprehensive information on best practices for process integration, process module development, metrology and process monitoring as well as tool performance optimization.
A Valuable Tool
Enabled by the proven results of our formal benchmarking model, and with the ability to quickly and easily refer to the BKMs, documentation and other information resources relevant to our tools, Applied’s FabVantage consultants are using the knowledge base to help 200mm customers solve difficult production challenges and keep their manufacturing costs as low as possible.
For additional information, contact Sangeeta_Dixit@amat.com.