Abstract:
A liquid raw material supply unit for a vaporizer is adapted to supply a liquid raw material to the vaporizer that vaporizes the liquid raw material. The unit comprises: a manifold internally formed with a flow passage; and a plurality of fluid control valves mounted on the manifold, wherein the plurality of fluid control valves includes: a liquid raw material control valve for controlling supply of the liquid raw material to the flow passage; a cleaning solution control valve for controlling supply of a cleaning solution to the flow passage; a purge gas control valve for controlling supply of a purge gas to the flow passage; and a first introducing control valve connectable to the vaporizer for controlling supply of a fluid from the flow passage to the vaporizer, the purge gas control valve, the cleaning solution control valve, the liquid raw material control valve, and the first introducing control valve being mounted on the manifold in this order from an upstream side of the manifold, wherein the flow passage is connected to valve ports of the plurality of control valves respectively, the valve ports communicating with valve openings of the respective control valves, and the flow passage is configured to allow the purge gas supplied from the purge gas control valve to directly flow in the valve ports of the cleaning solution control valve and the liquid raw material control valve placed downstream from the purge gas control valve.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a liquid raw material supply unit for a vaporizer for supplying a liquid raw material to the vaporizer. 
         [0003]    2. Description of Related Art 
         [0004]    In recent years, a high-integration design has been demanded for semiconductor memory devices and embedded memory LSIs using capacitors such as DRAM (Dynamic Random Access Memory) and FeRAM (Ferroelectric Random Access Memory). In response to such demands, high dielectric constant materials have to be used for manufacture of semiconductors. The high-dielectric materials are often used in liquid state. In many cases, accordingly, a liquid raw material is supplied to a vaporizer in which the liquid raw material is vaporized, and this vaporized gas is supplied to a reactor. This process therefore needs a liquid raw material supply line for supplying the liquid raw materials to the vaporizer. 
         [0005]    If the liquid raw material remains in the liquid raw material line and the vaporizer, it may result in reaction products which will be deposited in the line and the vaporizer. Such deposits are likely to cause various problems; e.g., they become a particle generation source, leading to a lower yield ratio, they clog control valves and line pipes, or they clog nozzles of the vaporizer. To avoid those problems, the liquid raw material supply line is usually subjected to a cleaning process after supply of the liquid raw material to the vaporizer. In the cleaning process, the liquid raw material remaining in the line pipes and the vaporizer is cleaned or washed with a cleaning solution (by liquid-liquid replacement) and then the cleaning solution is removed from the line pipes and the vaporizer by a purge gas (by liquid-gas replacement). 
         [0006]    An example of the above liquid raw material supply line is arranged as shown in  FIG. 6  that liquid raw material lines  101  and  102  each comprising a valve and pipes for feeding a liquid raw material and a cleaning solution line  103  comprising a valve and pipes for feeding a cleaning solution are connected to a main line  105  with one end connected to a vaporizer and the other end connected to a purge gas line  104 . In this liquid raw material line, a liquid raw material is fed from the liquid raw material line  101  or  102  to the main line  105 , and the liquid raw material fed into the main line  105  is then supplied to the vaporizer. 
         [0007]    For cleaning, here, the cleaning solution is fed from the cleaning solution line  103  to the main line  105 , thereby cleaning the line and the vaporizer through which the liquid raw material has passed with the cleaning solution. After cleaning using the cleaning solution, a purge gas is introduced into the purge gas line  104  to thereby remove the remaining cleaning solution from the liquid raw material supply line. 
         [0008]    Another example of the liquid raw material supply line is shown in  FIG. 7 , which is arranged such that monoblock valves X 1  to X 4  each comprising a plurality of valves are connected to each other through pipes. In this liquid raw material supply unit, a pressurizing gas (e.g., He gas or another inert gas) is fed into a valve V 2  of the monoblock valve X 1  and then enters a liquid raw material tank  121  through a valve V 1  of the monoblock valve X 1  and a valve V 4  of the monoblock valve X 2  to pressurize the liquid raw material to be supplied to the vaporizer through the valve V 1  of the monoblock valve X 2 , and the monoblock valves X 3  and X 4  in order. 
         [0009]    For cleaning, here, when a washing solution is fed into the valve V 1  of the monoblock valve X 1 , the washing solution flows in the monoblock valve X 3  via a valve V 3  of the monoblock valve X 2 . The washing solution then flows in a valve V 2  of the monoblock valve X 3  and a valve V 2  of the monoblock valve X 4  sequentially. By this process, the passages through which the liquid raw material has passed are cleaned. After cleaning using the washing solution, an inert gas such as an Ar gas is introduced as a purge gas into a valve V 3  of the monoblock X 1  to remove the remaining washing solution from the passages. 
         [0010]    However, both the aforementioned liquid raw material supply lines are fundamentally constructed of a plurality of valves and a plurality of pipes. This construction disadvantageously needs a large mounting space, which could impede miniaturization and high integration. 
         [0011]    In the former liquid raw material line, when the cleaning solution is fed into the main line  105  for cleaning, a liquid remaining or staying zone (a dead space) tends to occur in the liquid raw material supply line  101  or  102 . When the purge gas is fed into the main line  105 , on the other hand, a liquid remaining or staying zone (a dead space) is likely to occur in the liquid raw material supply lines  101  and  102  and the cleaning solution supply line  103  respectively. Thus, a replacement rate (or replacement capability) of the residual or remaining liquid (a liquid-liquid replacement rate and a liquid-gas replacement rate) is poor, which needs much time for replacement of the residual liquid, resulting in a longer cleaning time. This also leads to a prolonged cycle time of a semiconductor manufacturing device and hence a lower manufacturing efficiency. Further, the liquid-gas replacement rate is extremely poor with the result that the cleaning solution remaining after cleaning could not be replaced completely by the purge gas. 
         [0012]    In the latter liquid raw material supply line, on the other hand, the time required for cleaning could be shortened (the replacement rate of the residual liquid could be enhanced). However, the monoblock valves X 1  to X 4  used in the line have very complicated flow passages respectively. 
       BRIEF SUMMARY OF THE INVENTION 
       [0013]    The present invention has been made in view of the above circumstances and has an object to provide a liquid raw material supply unit in a miniaturized and integrated design with simple passage configurations, capable of reducing liquid remaining or staying zones, thereby enhancing a replacement rate of residual liquid. 
         [0014]    Additional objects and advantages of the invention will be set forth in part in the description which follows and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims. 
         [0015]    To achieve the above object, the present invention provides a liquid raw material supply unit for a vaporizer, adapted to supply a liquid raw material to the vaporizer that vaporizes the liquid raw material, the unit comprising: a manifold internally formed with a flow passage; and a plurality of fluid control valves mounted on the manifold, wherein the plurality of fluid control valves includes: a liquid raw material control valve for controlling supply of the liquid raw material to the flow passage; a cleaning solution control valve for controlling supply of a cleaning solution to the flow passage; a purge gas control valve for controlling supply of a purge gas to the flow passage; and a first introducing control valve connectable to the vaporizer for controlling supply of a fluid from the flow passage to the vaporizer, the purge gas control valve, the cleaning solution control valve, the liquid raw material control valve, and the first introducing control valve being mounted on the manifold in this order from an upstream side of the manifold, wherein the flow passage is connected to valve ports of the plurality of control valves respectively, the valve ports communicating with valve openings of the respective control valves, and the flow passage is configured to allow the purge gas supplied from the purge gas control valve to directly flow in the valve ports of the cleaning solution control valve and the liquid raw material control valve placed downstream from the purge gas control valve. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    The accompanying drawings, which are incorporated in and constitute a part of this specification illustrate an embodiment of the invention and, together with the description, serve to explain the objects, advantages and principles of the invention. 
           [0017]    In the drawings, 
           [0018]      FIG. 1  is a partially sectional view showing a schematic configuration of a liquid raw material supply unit in a preferred embodiment; 
           [0019]      FIG. 2  is a graph showing test results of a liquid-liquid (salt water-pure water) replacement rate in the case where salt water is supplied from a first liquid raw material supply valve (line); 
           [0020]      FIG. 3  is a graph showing test results of a liquid-liquid (salt water-pure water) replacement rate in the case where salt water is supplied from a second liquid raw material supply valve (line); 
           [0021]      FIG. 4  is a sectional view showing a schematic configuration of a liquid raw material supply unit in a comparative example; 
           [0022]      FIG. 5  is a partially sectional view showing a schematic configuration of a liquid raw material supply unit in another example; 
           [0023]      FIG. 6  is a schematic diagram of a structural outline of a liquid raw material supply line in a prior art; and 
           [0024]      FIG. 7  is a schematic diagram of a structural outline of a liquid raw material supply line in another prior art. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0025]    A detailed description of a preferred embodiment of a liquid raw material supply unit for a vaporizer according to the present invention will now be given referring to the accompanying drawings. The configuration of the liquid raw material supply unit of the present embodiment will be explained referring to  FIG. 1 .  FIG. 1  is a partially sectional view showing a schematic configuration of the liquid raw material supply unit of the present embodiment. 
         [0026]    The liquid raw material supply unit  10  includes a purge gas supply valve  30 , a cleaning solution supply valve  40 , a first liquid raw material supply valve  50 , a second liquid raw material supply valve  60 , and an introducing valve  70  connectable to a drain (hereinafter, referred to as a “drain introducing valve”, which corresponds to a second introducing valve of the present invention), which are fixedly mounted in line on the upper surface of a manifold  20  internally formed with flow passages, as shown in  FIG. 1 . Further, an introducing valve  80  connectable a vaporizer (hereinafter, referred to as a “vaporizer introducing valve”, which corresponds to a first introducing valve of the present invention) is attached to the left side of the manifold  20 . Specifically, the purge gas supply valve  30 , the cleaning solution supply valve  40 , the first liquid raw material supply valve  50 , the second liquid raw material supply valve  60 , the drain introducing valve  70 , and the vaporizer introducing valve  80  are arranged in this order from the upstream side of the manifold  20 . Through a flow passage  21  formed in the manifold  20 , the purge gas supply valve  30 , the cleaning solution supply valve  40 , the first liquid raw material supply valve  50 , the second liquid raw material supply valve  60 , the drain introducing valve  70 , and the vaporizer introducing valve  80  are connected to one another. The flow passage  21  includes V-shaped passages  23 ,  24 ,  25 , and  26 , and a communication passage  27 . Through a flow passage  22  of the manifold  20 , the vaporizer introducing valve  80  is connected to a vaporizer. 
         [0027]    The liquid raw material supply unit  10  is constructed to perform supply of a first liquid raw material and a second liquid raw material to the vaporizer, cleaning of the unit  10  and the vaporizer with a cleaning solution after the supplying of the first and second liquid raw materials, and removal of residual cleaning solution or others by a purge gas after the cleaning. The liquid raw material supply unit  10  comprising the valves  30 ,  40 ,  50 ,  60 ,  70 , and  80  that are mounted on the manifold  20  can achieve miniaturization and high integration. Accordingly, the liquid raw material supply unit  10  can be installed close to the vaporizer. 
         [0028]    The purge gas supply valve  30  is configured to control supply of a purge gas (a nitrogen gas in the present embodiment) to the flow passage  21  of the manifold  20 . In the purge gas supply valve  30 , a valve chamber  31  is connected to a purge gas supply source through a valve chamber port not shown and also connected to the flow passage  21  of the manifold  20  through a valve opening  32  and a valve port  33  opening on a mounting surface (a lower surface). 
         [0029]    The cleaning solution supply valve  40  is configured to control supply of the cleaning solution (THF in the present embodiment) to the flow passage  21  of the manifold  20 . In the cleaning solution supply valve  40 , a valve chamber  41  is connected to a cleaning solution supply source through a valve chamber port not shown and also connected to the flow passage  21  of the manifold  20  through a valve opening  42  and a valve port  43  opening on a mounting surface (a lower surface). 
         [0030]    The first liquid raw material supply valve  50  is configured to control supply of the first liquid raw material (strontium in the present embodiment) to the flow passage  21  of the manifold  20 . In the first liquid raw material supply valve  50 , a valve chamber  51  is connected to a first liquid raw material supply source through a valve chamber port not shown and also connected to the flow passage  21  of the manifold  20  through a valve opening  52  and a valve port  53  opening on a mounting surface (a lower surface). 
         [0031]    The second liquid raw material supply valve  60  is configured to control supply of the second liquid raw material (titanium in the present embodiment) to the flow passage  21  of the manifold  20 . In the second liquid raw material supply valve  60 , a valve chamber  61  is connected to a second liquid raw material supply source through a valve chamber port not shown and also connected to the flow passage  21  of the manifold  20  through a valve opening  62  and a valve port  63  opening on a mounting surface (a lower surface). 
         [0032]    The drain introducing valve  70  is configured to control introduction of a fluid flowing through the flow passage  21  of the manifold  20  into a drain for discharging the fluid from the liquid raw material supply unit  10 . In the drain introducing valve  70 , a valve chamber  71  is connected to the drain through a valve chamber port not shown and also connected to the flow passage  21  of the manifold  20  through a valve opening  72  and a valve port  73  opening on a mounting surface (a lower surface). 
         [0033]    The vaporizer introducing valve  80  is configured to control supply of a fluid flowing through the flow passage  21  of the manifold  20  to the vaporizer. In the vaporizer introducing valve  80 , a valve port  83  opening on a mounting surface (a right surface) and communicating with a valve opening  82  is connected to the flow passage  21  of the manifold  20 , and a valve chamber port  84  communicating with a valve chamber  81  is connected the flow passage  22 . 
         [0034]    Here, the purge gas supply valve  30 , the cleaning solution supply valve  40 , the first liquid raw material supply valve  50 , the second liquid raw material supply valve  60 , and the drain introducing valve  70  are connected to one another through the flow passage  21  of the manifold  20 . To be more specific, adjacent valves, that is, the purge gas supply valve  30  and the cleaning solution supply valve  40 , the cleaning solution supply valve  40  and the first liquid raw material supply valve  50 , the first liquid raw material supply valve  50  and the second liquid raw material supply valve  60 , and the second liquid raw material supply valve  60  and the drain introducing valve  70 , are connected through the corresponding V-shaped passages  23 ,  24 ,  25 , and  26  respectively. 
         [0035]    More specifically, inlets  23   a  to  26   a  and outlets  23   b  to  26   b  of the V-shaped passages  23  to  26  are formed opening on the upper surface of the manifold  20  in such a manner as to communicate with the valve ports  33 ,  43 ,  53 ,  63 , and  73  of the valves  30 ,  40 ,  50 ,  60 , and  70  respectively. In other words, the inlet  23   a  of the V-shaped passage  23  is connected to the valve port  33  of the purge gas supply valve  30  while the outlet  23   b  is connected to the valve port  43  of the cleaning solution supply valve  40 . The inlet  24   a  of the V-shaped passage  24  is connected to the valve port  43  of the cleaning solution supply valve  40  while the outlet  24   b  is connected to the valve port  53  of the first liquid raw material supply valve  50 . Further, the inlet  25   a  of the V-shaped passage  25  is connected to valve port  53  of the first liquid raw material supply valve  50  while the outlet  25   b  is connected to the valve port  63  of the second liquid raw material supply valve  60 . The inlet  26   a  of the V-shaped passage  26  is connected to the valve port  63  of the second liquid raw material supply valve  60  while the outlet  26   b  is connected to the valve port  73  of the drain introducing valve  70 . 
         [0036]    As above, the outlet  23   b  of the V-shaped passage  23  and the inlet  24   a  of the V-shaped passage  24  are formed to open at the same position to be connected to the valve port  43  of the cleaning solution supply valve  40 . In other words, the V-shaped passages  23  and  24  are connected to each other at the outlet  23   b  (or the inlet  24   a ), i.e., at a joint portion with respect to the valve port  43 . Further, the outlet  24   b  of the V-shaped passage  24  and the inlet  25   a  of the V-shaped passage  25  are formed to open at the same position to be connected to the valve port  53  of the first liquid raw material supply valve  50 . In other words, the V-shaped passages  24  and  25  are connected to each other at the outlet  24   b  (or the inlet  25   a ), i.e., at a joint portion with respect to the valve port  53 . The outlet  25   b  of the V-shaped passage  25  and the inlet  26   a  of the V-shaped passage  26  are formed to open at the same position to be connected to the valve port  63  of the second liquid raw material supply valve  60 . In other words, the V-shaped passages  25  and  26  are connected to each other at the outlet  25   b  (or the inlet  26   a ), i.e., at a joint portion with respect to the valve port  63 . 
         [0037]    The valve port  73  of the drain introducing valve  70  and the valve port  83  of the vaporizer introducing valve  80  are connected through the communication passage  27 . With the above configuration, a fluid to be supplied from each of the first liquid raw material supply valve  50 , the second liquid raw material supply valve  60 , the cleaning solution supply valve  40 , and the purge gas supply valve  30  can be supplied to the vaporizer or discharged to the drain by control of the drain introducing valve  70  and the vaporizer introducing valve  80 . 
         [0038]    Operations of the aforementioned liquid raw material supply unit  10  will be explained below. When the first liquid raw material is to be supplied to the vaporizer, the first liquid raw material supply valve  50  and the vaporizer introducing valve  80  are opened while other valves  30 ,  40 ,  60 , and  70  are closed. Thus, the first liquid raw material fed from the first liquid raw material supply valve  50  is allowed to pass through the flow passage  21 , i.e., the V-shaped passages  25  and  26  and the communication passage  27  and flow in the vaporizer introducing valve  80 . The vaporizer introducing valve  80  placed in an open state at this time allows the first liquid raw material flowing in the valve  80  to be supplied to the vaporizer through the flow passage  22 . 
         [0039]    When the second liquid raw material is to be supplied to the vaporizer, the second liquid raw material supply valve  60  and the vaporizer introducing valve  80  are opened while other valves  30 ,  40 ,  50 , and  70  are closed. Thus, the second liquid raw material fed from the second liquid raw material supply valve  60  is allowed to pass through the flow passage  21 , i.e., the V-shaped passage  26  and the communication passage  27  and flow in the vaporizer introducing valve  80 . The vaporizer introducing valve  80  placed in the open state at this time allows the second liquid raw material flowing in the valve  80  to be supplied to the vaporizer through the flow passage  22 . 
         [0040]    For cleaning, the cleaning solution supply valve  40  and the vaporizer introducing valve  80  are opened while the other valves  30 ,  50 ,  60 , and  70  are closed. Thus, the cleaning solution fed from the cleaning solution supply valve  40  is allowed to pass through the V-shaped passages  24 ,  25 ,  26  and the communication passage  27  and flow in the vaporizer introducing valve  80 . The vaporizer introducing valve  80  placed in the open state at this time allows the cleaning solution flowing in the valve  80  to be supplied to the vaporizer through the flow passage  22 . In this way, the cleaning solution is supplied to the passages, the valves, and the vaporizer through which the first or second liquid raw material has passed, thereby cleaning the liquid raw material supply unit  10  and the vaporizer. 
         [0041]    When the cleaning solution is to be supplied, the valve ports  53 ,  63 , and  73  may become liquid remaining zones (dead spaces), but respective volumes are extremely small as compared with a conventional case. The cleaning solution fed from the cleaning solution supply valve  40  to the V-shaped passage  24  flows in the valve port  53  of the first liquid raw material supply valve  50  and then in the V-shaped passage  25 . The cleaning solution flowing in the V-shaped passage  25  flows in the valve port  63  of the second liquid raw material supply valve  60  and then in the V-shaped passage  26 . The cleaning solution flowing in the V-shaped passage  26  flows in the valve port  73  of the drain introducing valve  70  and then in the communication passage  27 . In the above way, the cleaning solution is directly allowed to flow in the valve ports  53 ,  63 , and  73  which may become liquid remaining zones. Accordingly, the cleaning solution collides with the residual liquid staying in the valve ports  53 ,  63 , and  73  sequentially to gradually push out the residual liquid from the valve ports  53 ,  63 , and  73  or dissolve the residual liquid. This makes it possible to efficiently replace the residual liquid by the cleaning solution. Thus, the liquid-liquid replacement rate can be enhanced. Consequently, the first or second liquid raw material remaining in the flow passages of the liquid raw material supply unit  10  can completely be replaced by the cleaning solution in a shorter time than the conventional case. 
         [0042]    Test results of replacement rates of the liquid raw material supply unit  10  of the present embodiment and that of the conventional liquid raw material supply line shown in  FIG. 6  are shown in  FIGS. 2 and 3 .  FIG. 2  is a graph showing the test result of a liquid-liquid (salt water-pure water) replacement rate in the case where salt water is supplied from the first liquid raw material supply valve (line).  FIG. 3  is a graph showing the test result of a liquid-liquid (salt water-pure water) replacement rate in the case where salt water is supplied from the second liquid raw material supply valve (line). 
         [0043]    In the tests, salt water (0.5%) was filled in the flow passage instead of the liquid raw material and then pure water was supplied at a rate of 2 mL/min. Then, water discharged from the supply unit  10  and the conventional supply line through respective supply ports connectable with the vaporizers, was stored by 10 mL, and electric conductivity of the stored water was measured. Based on the previously measured electric conductivity of each of pure water and salt water, the salinity was calculated from the measured electric conductivity. In the tests, the salinity was compared between the both cases until the salt water was diluted to the salinity of 1.0 ppm or below. 
         [0044]    In a comparison between the liquid raw material supply unit  10  and the conventional liquid raw material supply line of  FIG. 6  in regard to a replacement time needed for replacement until the salinity was reduced to 1.0 ppm, as clearly found in  FIGS. 2 and 3 , the liquid raw material supply unit  10  of the present embodiment (a solid line in the graph) shows a superior replacement rate to the conventional liquid raw material supply line (a dotted line in the graph). Specifically, in the case where the salt water was supplied from the first liquid raw material supply line (valve), the replacement time needed until the salinity was reduced to 1.0 ppm was about 90 min. in the liquid raw material supply unit  10 , whereas it was as much as about 220 min. in the conventional liquid raw material supply line, as shown in  FIG. 2 . In the case where the salt water was supplied from the second liquid raw material supply line (valve), the replacement time needed until the salinity was reduced to 1.0 pm was about 70 min. in the liquid raw material supply unit  10 , whereas it was as much as about 170 min. in the conventional liquid raw material supply line. 
         [0045]    The above results reveal that the liquid raw material supply unit  10  of the present embodiment can largely shorten a cleaning time needed for cleaning the liquid raw material supply unit  10 , resulting in a shortened cycle time of a semiconductor manufacturing device, thereby improving production capacity. A consumption amount of the cleaning solution can also be reduced for cutting on costs. 
         [0046]    After completion of the cleaning using the cleaning solution as above, the purge gas supply valve  30  and the drain introducing valve  70  are opened and other valves  40 ,  50 ,  60 , and  80  are closed. Thus, the supply of the cleaning solution from the cleaning solution supply valve  40  is stopped while supply of a purge gas from the purge gas supply valve  30  is started. The purge gas supplied from the purge gas supply valve  30  is discharged from the liquid raw material supply unit  10  via the drain introducing valve  70 . Such supply of the purge gas is intended to completely remove the residual liquid from the liquid raw material supply unit  10  to prevent possible corrosion or other disadvantages. In some instances, the drain introducing valve  70  is closed and the vaporizer introducing valve  80  is opened to supply the purge gas to the vaporizer. 
         [0047]    When the purge gas is to be supplied, similarly, the valve ports  43 ,  53 , and  63  may become liquid remaining zones (dead spaces), but respective volumes are extremely small as compared with the conventional case. The purge gas supplied from the purge gas supply valve  30  into the V-shaped passage  23  flows in the valve port  43  of the cleaning solution supply valve  40  and then in the V-shaped passage  24 . The purge gas introduced into the V-shaped passage  24  flows in the valve port  53  of the first liquid raw material supply valve  50  and then in the V-shaped passage  25 . The purge gas flowing in the V-shaped passage  25  then flows in the valve port  63  of the second liquid raw material supply valve  60  and then in the V-shaped passage  26 . The purge gas flowing in the V-shaped passage  26  then flows in the valve port  73  of the drain introducing valve  70 , passing through the drain introducing valve  70 , and then is discharged outside. 
         [0048]    In the above way, the purge gas is allowed to directly flow in the valve ports  43 ,  53 , and  63  which may become liquid remaining zones. Accordingly, the purge gas collides with the residual liquid staying in the valve ports  43 ,  53 , and  63  sequentially to gradually push out the residual liquid from the valve ports  43 ,  53 , and  63 . Even where the residual liquid has large surface tension, it can be fully replaced by the purge gas. The liquid-gas replacement rate can therefore be enhanced. This makes it possible to completely remove the residual cleaning solution from the liquid raw material supply unit  10 . 
         [0049]    Here, the liquid raw material supply unit  10  of the present embodiment provided with the manifold  20  made of acrylic was checked by a residual liquid condition in each of the valve ports  43 ,  53 ,  63 , and  73 . As an object for comparison with the liquid raw material supply unit  10 , a liquid raw material supply unit using a manifold  20   a  provided with a flow passage configuration as shown in  FIG. 4  was similarly checked by the residual liquid condition in each of valve ports  43 ,  53 ,  63 , and  73 . It should be noted that the manifold  20   a  is formed with a main flow passage  21   a  extending straight in a longitudinal direction of the manifold  20   a , in place of the flow passage  21  of the manifold  20 , and sub-passages  35 ,  45 ,  55 ,  65 , and  75  connecting the main flow passage  21   a  to the valve ports  33 ,  43 ,  53 ,  63 , and  73  of the corresponding valves  30 ,  40 ,  50 ,  60 , and  70 . 
         [0050]    A comparison of the replacement capability (rate) using the purge gas between the liquid raw material supply unit  10  and the liquid raw material supply unit shown in  FIG. 4  obviously indicates that the liquid raw material supply unit  10  had a superior replacement capability to the liquid raw material supply unit as shown in  FIG. 4 . It was specifically found in the liquid raw material supply unit  10  that when the purge gas was supplied to the flow passage  21  of the manifold  20 , the liquid was completely replaced by the purge gas without remaining in the valve ports  43 ,  53 ,  63 , and  73  which may become dead spaces. It was conversely found in the liquid raw material supply unit shown in  FIG. 4  that when the purge gas was supplied to the flow passage  21   a  of the manifold  20   a , the liquid remained in the valve ports  43 ,  53 ,  63 , and  73  which might become dead spaces and the sub-passages  35 ,  45 ,  55 ,  65 , and  75 . Thus, the liquid raw material could not be completely replaced by the purge gas. 
         [0051]    In the liquid raw material supply unit  10  of the present embodiment as described above, the purge gas supply valve  30 , the cleaning solution supply valve  40 , the first liquid raw material supply valve  50 , the second liquid raw material supply valve  60 , and the drain introducing valve  70  are integrally mounted on the upper surface of the manifold  20 , in line in that order from the upstream side of the manifold  20 , and the vaporizer introducing valve  80  is further attached to the left side of the manifold  20 . Thus, the miniaturization and high integration can be achieved. The valve ports  33 ,  43 ,  53 ,  63 , and  73  of the adjacent valves among the purge gas supply valve  30 , the cleaning solution supply valve  40 , the first liquid raw material supply valve  50 , the second liquid raw material supply valve  60 , and the drain introducing valve  70  are connected by the corresponding V-shaped passages  23 ,  24 ,  25 , and  26 . Consequently, the liquid remaining zones may be reduced to only the valve ports  43 ,  53 ,  63 , and  73  at most. In case liquid remains in those valve ports  43 ,  53 ,  63 , and  73 , it can be gradually pushed out sequentially by the replacement fluid (a cleaning solution or a purge gas) supplied from upstream to collide with the residual liquid. This makes it possible to enhance the replacement rate of the residual liquid by the cleaning solution or purge gas. 
         [0052]    The present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. For instance, the aforementioned embodiment exemplified the liquid raw material supply unit  10  with the first liquid raw material supply valve  50  and the second liquid raw material supply valve  60  both being mounted on the manifold  20  for supplying two kinds of liquid raw materials. As an alternative, a unit may be arranged to supply a single kind of a liquid raw material shown in  FIG. 5 , in which the first liquid raw material supply valve  50  is mounted on the manifold  20 , and a passage block  66  is mounted instead of the second liquid raw material supply valve  60  on the manifold  20 . 
         [0053]    While the presently preferred embodiment of the present invention has been shown and described, it is to be understood that this disclosure is for the purpose of illustration and that various changes and modifications may be made without departing from the scope of the invention as set forth in the appended claims.