FabVantage Methodology Improves Cluster Tool Run Rates
Ed LaBelle, Kevin Sannes, Chris Keith, Brian Dearing, Mark Murphy
Run rate improvement can reduce fab operating costs by increasing the daily wafer output of the installed manufacturing tools. Using a proven methodology and holistic approach, the Applied Materials FabVantage Consulting Group is assisting customers in identifying tool constraints affecting optimum run rate performance. This methodology taps into the extensive resources of Applied Materials—expert consultants, a broad knowledge base and best known methods (BKM’s), and proprietary simulation and emulation software—to quickly identify opportunities to improve run rates for various tool platforms such as PVD, CVD, and etch tools. Run rate improvements of more than 10% have been demonstrated using this methodology. This article discusses the run rate improvements achieved by FabVantage consultants on an Applied Materials cluster tool.
Many factors affect run rates on semiconductor manufacturing equipment. These include recipe step times, sequence path, robot speed and logic, chamber configuration, chamber redundancy, periodic clean frequency and maintenance practices and procedures. Identifying tool bottlenecks and procedural inefficiencies is critical to improving overall tool run rates or wafer output.
Run rate improvement is a complicated and time-consuming task for chip manufacturing facilities running at high capacities. Some may not have access to best practices for operating and maintaining their semiconductor equipment, and most do not have sufficient available tool time to test multiple options for improving run rates.
As part of a consulting engagement with a customer, FabVantage engineers will initiate a comprehensive, methodical assessment process designed to help them quickly find opportunities for optimization of the various factors impacting tool run rate, with as little production disruption as possible.
The FabVantage consulting team first performs a detailed audit of the process, hardware, and maintenance procedures to identify areas for improvement. Based on the findings of the assessment, recommendations for improving the run rate are presented. The FabVantage team then works closely with the customer during the implementation phase of the project to test the recommendations on a golden tool. Once proven on the golden tool, these changes can be ramped to full release for manufacturing, delivering operating efficiencies across the entire tool fleet.
The methodology for FabVantage Tool Output Improvement engagements, summarized in Figure 1, focuses on four areas of investigation: white space improvements, preventive maintenance (PM) optimization, process optimization, and continuous improvement process (CIP) optimization.
|Figure 1. FabVantage engineers methodically investigate multiple tool performance parameters in four key areas for potential run rate improvements. The chart shows normalized tool baseline performance (blue bar) and how FabVantage analysis in each of the four categories can help to improve tool output (green bars).|
Once a project has been approved by the customer, the FabVantage group will form an Assessment Team that consists of experienced Applied Materials process and hardware experts. Subject matter experts (SME’s) and Fault Detection and Classification (FDC) engineers, if needed, will also be part of the Assessment Team. A typical FabVantage assessment will last about four weeks depending on customer schedule and tool availability for performing the assessment. The first week or two of the assessment is the on-site data collection portion of the project and the remaining weeks are for internal FabVantage data review and analysis with SME’s.
The goal of the assessment is to gather information on the current performance of the customer’s tool and use that information to identify appropriate strategies to improve performance of that tool. Planning discussions quickly determine which sequences will be the focus of the run rate improvement, and one or two customer tools are designated as the golden tool(s), on which assessment activities will be performed. The assessment includes an audit of the golden tool(s), and consultants provide to the customer any findings that deviate from Applied Materials best practices or BKM’s, along with recommendations for improving the tool performance based on all assessment findings.
In the implementation stage, based on the findings and recommendations from the assessment, the FabVantage team performs tests to optimize tool performance. These tests can include software simulation and emulations, as well as live wafer runs (see Figure 2). The typical implementation phase can last for several weeks.
|Figure 2. FabVantage teams perform multiple system tests to uncover opportunities for tool performance optimization.|
Cluster Tool Run Rate Improvement Using Software Tools
In a typical FabVantage Run Rate Improvement engagement on an Applied Materials cluster tool, the team will set up the simulator and emulator programs to the same configuration as the customer tools. A mechanical cycle test of typically 4-6 lots will be performed on the golden tool to establish a baseline run rate. The event log from this baseline test will be converted to a replay-simulation readable file and simulation will be conducted with the file. The replay-simulation will output the run rate statistics. The statistics include run rate (throughput), total process time and wafer tact time. The replay-simulation statistics are then used to calibrate the simulator and the emulator to match the golden tool baseline run rate.
The simulator software allows testing of a variety of chamber, recipe and sequence conditions which can improve tool run rate. FabVantage engineers can program customer tool configuration, wafer sequence and recipe information into the simulator. These simulations can be performed very quickly and small or large process changes or “what-if” scenarios can be simulated for multiple lot runs in a few seconds. For example, a 150 wafer cycle test that would normally take 2-4 hours on the customer tool or emulator can be completed in about 5 seconds using the simulator. Small recipe changes can be made and another simulation run completed very quickly to assess results. Varying chamber configurations or group chamber assignment can also be tested without having to locate a tool that has the desired test configuration. The simulator findings for improving run rate are then fed into the emulator for real-time multi-lot testing to corroborate the simulator model.
The emulator software enables the FabVantage consultant to perform virtual simulation runs in real-time, meaning the mechanical cycle tests run at approximately the same amount of time as a real cycle run. Customer tool constants are uploaded to the emulator to provide comparable tool operational performance. As mentioned previously, the emulator is calibrated to closely match the golden tool baseline run rate performance. The main advantage of the emulator is that it allows FabVantage engineers to run different scenarios without consuming valuable customer tool time. This is important because the customer tool under investigation may already be a constraint tool in the fab, so any additional engineering down time to validate run rate improvements impacts wafer-outs.
Once the emulator testing is completed, the run rate scenarios that showed the best improvement are ready to be tested. The baseline test is repeated on the golden tool using the optimized settings which are typically bundled together for a single cascade run. A simple calculation of dividing the optimized run rate by the baseline run rate establishes the value of the run rate improvement.
The Applied Materials FabVantage Consulting Group has successfully completed Run Rate Improvement engagements at multiple customer sites on a wide variety of tool platforms including Endura, Centura, Producer, Mirra/Reflection, and ion implanter systems, demonstrating run rate improvements of more than 10%.
Proven methodology—combined with the broad experience of FabVantage consulting engineers, the depth of the Applied Materials knowledge base and the power of advanced simulator and emulator tools—helps customers quickly and effectively improve tool output and reduce fab operating costs.
For additional information, please contact Avi_Edelstein@amat.com.