1. Field of the Invention
The present invention relates to a coating and developing apparatus including processing modules, a method for operating the coating and developing apparatus, and a storage medium storing a computer program to be used for a coating and developing apparatus.
2. Background Art
A coating and developing apparatus coats a semiconductor wafer as a substrate (hereinafter referred to as a “wafer”) with a resist and develops the resist after exposure. The coating and developing apparatus is provided with many modules and a plurality of transfer arms for transferring the wafers among the modules. Herein, any place or location where a wafer is placed may be interpreted as “module”.
After a carrier storing wafers has been transferred to the coating and developing apparatus, a transfer schedule is set for all wafers in the carrier (which will undergo the same type of process steps) before the wafers are removed from the carrier. The transfer schedule is a schedule specifying modules to which each wafer should be transferred after being removed from the carrier and before returning to the carrier. Since the modules to which each wafer should be transferred have previously been determined as above, transfer arms (for transferring each wafer among the modules) that should be used have also been previously determined before each wafer is removed from the carrier.
The coating and developing apparatus will be explained more concretely below. The coating and developing apparatus is equipped with a processing block which includes resist coating modules for performing the resist coating process and developing modules for performing the developing process, and an interface block which transfers the wafers between an exposure apparatus and the processing block. The interface block includes processing modules for cleaning each wafer before exposure and processing modules for cleaning each wafer after exposure, which is described in JP2010-287686A and JP458492682). As shown in 3P2012-199318A, the interface block may include many transition modules, stacked up, to transfer the wafers among the processing modules, parts of the processing block, and the exposure apparatus. In this case, a plurality of transfer arms share the transfer work to and from the many transition modules.
However, there may be a difference (deviation) in the number of transfer processes (i.e., the number of times of transfer executions) among the transfer arms depending on the aforementioned transfer schedule. For example, the first transfer arm performs the inter-module transfer five times, while the second transfer arm performing the inter-module transfer three times. With such a deviation in the number of transfer processes among the transfer arms, the productivity of the apparatus can be limited by the operation of the transfer arm whose number of transfer processes is the greatest. Further, in order to increase the productivity of the apparatus, the processed wafer should be unloaded from each processing module to allow a subsequent unprocessed wafer to be loaded into the processing module immediately after the completion of the processing in the processing module, so that processing modules can be used efficiently