1. Field of the Invention
The present invention relates to a method and an apparatus for analyzing a fabrication line of semiconductor devices.
2. Description of the Background Art
FIG. 18 is a block diagram of a fabrication line analysis apparatus in the background-art. The fabrication line analysis apparatus consists of a data analysis system D90 and data management systems C91 to C98. A fabrication process mainly consists of a wafer process and an inspection process for inspection of the products. The wafer process is carried out by fabrication devices A1 to A4. The inspection process is carried out by an electrical characteristic measuring device A5 and product measuring devices A6 to A8. A fabrication line 10 of semiconductor devices includes the devices A1 to A8. Furthermore, the fabrication process further includes an assembly process which is not shown in this figure.
Inspection systems B1 to B4 each include a contamination inspection device and a defect inspection device (not shown). The data management systems C91 to C94 each include a contamination inspection database and a defect inspection database (not shown).
A product wafer is sequentially processed by the devices A1 to A8. The fabrication devices A1 to A4 are each subjected to a periodical inspection before processing the product wafer. The inspection of the devices A1 to A4 is performed as follows: First, the fabrication device A1 processes a monitor wafer (bare wafer). Next, the contamination inspection device of the inspection system B1 inspects contaminations on the processed monitor wafer and the inspection result is given to the data management system C91 to be entered as data in the contamination inspection database. In like manner, the contamination inspection devices in the inspection systems B2 to B4 inspect contaminations on the monitor wafers processed by the fabrication devices A2 to A4 and the inspection results are given to the data management systems C92 to C94 to be entered as data in the contamination inspection databases, respectively.
The defect inspection devices of the inspection systems B1 to B4 inspect defects on the product wafers processed by the fabrication devices A1 to A4 and the inspection results are given to the data management systems C91 to C94 to be entered as data in the defect inspection databases, respectively.
The assembly process is carried out after the processing by the electrical characteristic measuring device A5 before the processing by the product measuring device A6. The product wafer undergoes the assembly process to be in a form of product.
The electrical characteristic measuring device A5 measures the product wafer and the product measuring devices A6 to A8 each measure the product. The measurement results obtained by the measuring devices A5 to A8 are given to the data management systems C95 to C98 to be entered as data in databases thereof (not shown), respectively.
A database D93 stores the data stored in the data management systems C91 to C98 without any processing. An output unit D92 gives a readout from the database D93.
Since an interconnection process is performed at the end of the wafer process, it is difficult to evaluate the product wafer in detail during the wafer process. Therefore, a detailed evaluation of the product wafer is made after the wafer process.
FIG. 19 is a flow chart showing a background-art procedure of evaluating the product wafer in detail. First, the fabrication devices A1 to A4 process the product wafer (Step 901). Next, the electrical characteristic measuring device A5 measures the electrical characteristics of the product wafer (Step 902). An operator judges whether or not there is any failure (nonconforming defect), observing the measurement result given by the output unit D92 (Step 903). If no failure is found, the product wafer undergoes the assembly process to be in a form of product. Subsequently, the product measuring devices A6 to A8 perform plural types of measurements (Steps 904, 906 and 908). The operator judges whether or not there is any failure, observing the measurement result given by the output unit D92 (Steps 905, 907 and 909). If no failure is found, the process ends, and otherwise the operator analyzes the cause of failure (Step 910). The operator performs an electrical measurement of the defective product (Step 911). Further analysis (Step 912) and a remedy of device, product or product wafer (Step 913) are made. If some failure is found, Step 903 is followed by Steps 912 and 913.
As discussed above, the detailed evaluation of the product wafer is made after the wafer process, and accordingly detecting the cause of nonconforming defect and the like is a time-consuming work and a prompt remedy is hard to do.
Furthermore, even if some nonconforming defect is found during the contamination inspection or the defect inspection, it takes much time to find the cause and it is hard to make a prompt remedy.