This invention relates to semiconductor vapor phase growing apparatus. So called vapor phase growing apparatus in which vapor phase growth is performed on a semiconductor wafer has called attention in recent years because semiconductor tips are used in various industrial fields. In the vapor phase growing apparatus now being used, a sequence program (hereinafter termed a process program) indicative of the progress of the process in a reaction furnace is excecuted by a system in which the progress of the sequence is designated by a pin board switch or the like, and the flow quantity of the gas used and the furnace temperature are designated by setting variable resistors contained in a control device by an operator.
FIG. 1 is a block diagram explaining the conventional manner of controlling the progress of the process in a reaction furnace with a pin board switch system.
In FIG. 1, pins are inserted into a set panel of a pin board switch according to an order of execution of a process program PPi (i=1-17), and the set panel is constructed such that the sequence times of the process program of the respectively designated orders can be set in the units of hours, minutes and seconds.
To a relay ladder circuit B are applied instructions corresponding to the order of a sequence, that is instructions that make effective the contents of process programs pp2, pp3, pp4, pp6, pp5 and pp6 corresponding to steps 1 , 2 , . . . 6 , 7 so as to give control signals to valves or like means corresponding to respective instructed processes. With such pin board system, however, only the times of respective process sequences can be set, but the flow quantity of the gas used and the furnace temperature must be set with other measures, for example variable resistors.
In addition to the pin board system shown in FIG. 1, a control device utilizing a general purpose sequence controller has also been proposed. In such control device too, the flow quantity and the furnace temperature are not designated by directly programmed data so that such setters as variable resistors are necessary.
Furthermore, in the pin board system described above, only one group of a series of programs corresponding to one cycle of the reaction furnace, that is only one set of pp2.fwdarw.pp3.fwdarw.pp1.fwdarw.pp4.fwdarw.pp6.fwdarw.pp5.fwdarw.pp7 shown in FIG. 1 can be loaded so that in order to operate a plurality of reaction furnaces a plurality of pin board panel units corresponding thereto should be provided. In this regard, since the general purpose controller contains a timer, only a problem of time designation program is involved. Where the general purpose program is used, since its process program is not contructed to designate the gas flow quantity and the furnace temperature, setters of these parameters have been used. Principal reasons are as follows.
1. Although the system program of a general purpose sequence controller is prepared by its maker, just like the pin board system, the decoding items of the content of the process program according to its system program lack the items regarding gas flow quantity used and the reaction furnace designation temperature. For this reason, the gas flow quantity and the furnace temperature are set by such independent setters as variable resistors or the like manipulated by the operator.
2. From the standpoint of the operator, manipulation of the general purpose sequence controller, the ability of directly controlling the gas flow quantity and the furnace temperature are equivalent to those of the pin board system so that the operator can operate the reaction furnace without any caution. Especially, correction of set values can be made readily.
3. From the standpoint of the maker, where manual setters for the gas quantity and the furnace temperature are omitted, it is necessary to modify the system program so as to include a program for correcting the content of the process program as a portion of the system program.