(1) Field of the Invention
The present invention relates to a production progress control method for a process such as the fabrication of semiconductor devices, and more particularly to a method for controlling the progress of a plurality of production lots. 
(2) Description of the Related Art
Conventionally, a production progress controlling is effected based on a priority rank table (j) for lots, as shown in FIG.  1A, which table relates to priority ranks assigned to the respective lots and also an in-process lot table (k) for each step, as shown in FIG.  1B, which table relates to the sequence of the priority ranks for lots in each of the steps. 
In the conventional method, the above priority ranks are used as data for con%rolling the production progress.  For each of the steps A, B, C, . . .  X, the lots are arranged in the sequence of their priority ranks and this provides the process start lot table as Shown in FIG.  1B. Based on this table, instructions are given to a person engaged in the work or a transfer control system for carrying out the work in the sequence of priority ranks (in the present example, in the sequence in which the number of priority ranks increases). 
In the conventional production progress control method described above, the process period required for the completion of a given lot is not taken into account as data for determining the priority ranks, so it is not possible to designate a targeted due-in date and time (i.e., date and time for completion) for each of the lots at the start of the work.  A further problem is that, in order to change the targeted due-in date and time, it is necessary to adjust the progress speed of the lots by changing priority levels at each occasion, which results in an increase in steps or man-hours in the lot progress control.