Quality control method and system on production line for fabricating products

Abstract

Method and system for quality control on a production line. Troubles with quality are prevented by detecting a trend in quality characteristics of the production line or fluctuations in an early stage. The absolute values of the differences between same kinds of the data obtained at given measurement points regarding of the quality control data or the absolute values of the differences between same items of one kind of SPC data are used as a controlled item for detecting a trend in quality control characteristics or fluctuations of the quality control characteristics. The difference between maximum and minimum values of the quality control data at plural measurement points within the same lot or within the same wafer is used as the differences between same kinds of the quality control data, for example. The difference between the average values of measured values taken from two lots processed in succession by the same fabrication step or by the same fabrication apparatus for quality control is used as the difference between items of the SPC data, for example. The absolute values of these differences are managed, based on preset threshold values. If any one of the absolute values of differences exceeds the threshold value, an alarm is issued, and a notice is given to the associated plant section.

What is claimed is:  
     
         1 . A quality control method on a production line including at least one fabricating step for fabricating products including a series of lots, said quality control method comprising: 
 a inspection step for inspecting the fabricating products associated with results of the fabrication step of line;    a storing step for storing data obtained by the inspection step to a memory; and    a management step for managing the variations of the data to manage the quality characteristics of the fabricating products by using the data stored in the memory;    wherein in the management step, the trend in quality is managed by using absolute values of differences between same kinds of the data obtained at given measurement points regarding each of the fabricating products.    
     
     
         2 . The quality control method on the production line as set forth in  claim 1 , wherein in the management step, the trend in quality is managed by using absolute values of differences between maximum and minimum values of same kinds of the data obtained at given measurement points regarding each lot of the fabricating products.  
     
     
         3 . The quality control method on the production line as set forth in  claim 1 , wherein in the management step, the trend in quality is managed by using absolute values of differences between same kinds of the data obtained at given measurement points regarding each of the fabricating products, based on a threshold value and wherein if any one of the absolute values of differences exceeds the threshold value, an alarm is issued.  
     
     
         4 . A quality control method on a production line including at least one fabricating step for fabricating products including plural groups of a series of lots, said quality control method comprising: 
 a inspection step for inspecting the fabricating products associated with results of the fabrication step;    a storing step for storing data obtained by the inspection step to a memory;    a processing step for statistically processing the data stored in the memory to thereby derive statistical data; and    a management step for managing the variations of the statistical data to manage the quality characteristics of the fabricating products;    wherein in the management step, the trend in quality is managed by using absolute values of differences between same items of the statistical data derived from the two groups of the series of lots processed by the fabricating step in succession.    
     
     
         5 . The quality control method on the production line as set forth in  claim 4 , wherein in the management, the trend in quality is managed by using the values of differences between average values derived from the two groups of the series of lots processed by the fabricating step in succession.  
     
     
         6 . The quality control method on the production line as set forth in  claim 4 , wherein in the management step, the trend in quality is managed by using absolute values of differences between same items of the statistical data derived from the two groups of the series of lots processed by the fabricating step in succession, based on a threshold value and wherein if any one of the values of differences exceeds the threshold value, an alarm is issued.  
     
     
         7 . A quality control system on a production line including plural fabricating steps for fabricating products including a series of lots, said quality control system comprising: 
 a quality characteristic data registration-and-processing means for storing data about actual results obtained by inspecting the fabricating products processed by the fabricating steps to a memory, said results including lot name of the products, process step name, product type, and date of processing;    a management condition registration-and-processing means registered with a method of judging whether each lot is defective and with an upper threshold value, a lower threshold value, and a processing method effected when an abnormality takes place;    a quality characteristic abnormality decision means for receiving data about results of inspections on the fabricating products from quality characteristic data registration-and-processing means, and judging the data obtained by the inspections based on the abnormality decision method registered in the management condition registration-and-processing means; and    a notice-and-display means for giving a notice of results of a decision made by the quality characteristic abnormality decision means and displaying the results;    wherein said quality characteristic abnormality decision means acting to manage a trend in quality of said fabricating products, using absolute values of differences between same kinds of data obtained at given measurement points regarding each of the lots.    
     
     
         8 . A quality control system on a production line including plural fabricating steps for fabricating products including plural groups of a series of lots, said quality control system comprising: 
 a quality characteristic data registration-and-processing means for storing data about results and data obtained by inspecting the fabricating products processed by the fabricating steps to a memory and for statistically processing the date to obtain statistical data, said results including lot name of the products, process step name, product type, and date of processing;    a management condition registration-and-processing means registered with a method of judging whether each lot is defective and with an upper threshold value, a lower threshold value, and a processing method effected when an abnormality takes place;    a quality characteristic abnormality decision means for receiving data about the results of inspections on the fabricating products and said statistical data from said quality characteristic data registration-and-processing means, and judging the statistical data by the abnormality decision method registered in said management condition registration-and-processing means; and    a notice-and-display means for giving a notice of results of a decision made by the quality characteristic abnormality decision means and displaying the results;    wherein said quality characteristic abnormality decision means acting to manage a trend in quality of said groups of series of lot, using absolute values of differences between the same items of said statistical data derived from the two groups of the series of lots processed by same fabricating step in succession.