Lean randomization and exception handling

Autor: Hermann Weindl, Stephan Melzig, Robert Barlovic, Andreas Becker, Heiko Wagner, Thomas Kowtsch, Sebastian Knappe, Dirk Grossmann, Wolfgang Jackel, Mark Reiche, Raymond Goss, Daniel Zschabitz, Jan Rothe, Uwe Schulze
Rok vydání: 2010
Předmět:
Zdroj: 2010 IEEE/SEMI Advanced Semiconductor Manufacturing Conference (ASMC).
DOI: 10.1109/asmc.2010.5551456
Popis: In recent years, randomization of process order as well as randomization of the wafer map in the cassettes delivering the wafers was increasingly used to be able to correlate yield variations with specific segments of the process flow (see [1] and [2]), as well as to reduce yield influences on specific wafer positions such as top and bottom of the wafer cassette. Many randomization efforts relied on wafer sorter based randomization, which costs cycle time and wafer sorter capacity. In this paper, we describe how randomization of both process sequence as well as wafer map changes can be implemented on process equipment as part of normal processing. This kind of randomization does not add cycle time and does not require wafer sorters and will therefore be called lean randomization. We will also describe some of the most important exceptions that can occur when implementing lean randomization and we will discuss how a fab can deal with those exceptions.
Databáze: OpenAIRE