Patent Publication Number: US-2011064877-A1

Title: Gas supply device, vacuum processing apparatus and method of producing electronic device

Description:
TECHNICAL FIELD 
     The present invention relates to a gas supply device used to introduce a processing gas into a vacuum vessel, a vacuum processing apparatus having the gas supply device in the vacuum vessel and a method of producing an electronic device using the vacuum processing apparatus. 
     BACKGROUND ART 
     In a case where a substrate or the like is undergone film forming processing such as sputtering, vapor deposition, ion plating and plasma polymerization within a vacuum vessel, it is necessary to supply a processing gas into the vacuum vessel. Especially, it is important for a film forming method, which forms a thin film on a substrate by supplying the reactive gas under vacuum atmosphere, to supply uniformly the reactive gas in order to keep uniformity in film quality. 
     As technology of uniformly supplying the reactive gas, there is proposed, for example, sputtering technology using a gas supply pipe formed with a large number of gas outflow ports in a vacuum vessel (see Patent Reference 1). 
     PRIOR ART 
     [Patent Reference] 
     [Patent Reference 1] Japanese Patent Laid-Open No. 3-166366 (FIG. 1, FIG. 2) 
     DISCLOSURE OF INVENTION 
     [Problems to be Solved by the Invention] 
     But, when a large number of gas outflow ports are simply formed in the gas supply pipe as in Patent Reference 1, provision of uniform gas within the vacuum vessel is not satisfactory. Especially, an overall length of the gas supply pipe tends to become long because of a demand for a substrate having a larger area, and there was a problem that the gas cannot be supplied uniformly because of a difference in gas flow rate between portions near to and far from a connection with the gas introducing system. 
     In view of the above circumstances, the present invention provides a gas supply device which can supply the gas uniformly even if the overall length of the gas supply pipe is long and can secure uniformity in film quality, a vacuum processing apparatus provided with the gas supply device and a method of producing an electronic device using the vacuum processing apparatus. 
     [Means for Solving the Problem] 
     The structure of the invention made to achieve the above objects is as follows. 
     Specifically, a gas supply device according to the invention is provided with a gas supply pipe for supplying a processing gas into a vacuum vessel, wherein the gas supply pipe is a double-layer pipe comprising an inner pipe connected to a gas introduction pipe and an outer pipe for covering the peripheral portion of the inner pipe with a gap between them; the inner pipe has a porous sintered body for allowing the passage of the gas in at least a part of it; and the outer pipe has a large number of gas outlet ports for discharging the gas having passed through the sintered body surface into the vacuum vessel. 
     A vacuum processing apparatus according to the invention is provided with a gas supply pipe for supplying a gas into a vacuum vessel for processing a substrate, wherein the gas supply pipe is a double-layer pipe comprising an inner pipe connected to a gas introduction pipe and an outer pipe for covering the outer peripheral portion of the inner pipe with a gap between them; the inner pipe has a porous sintered body for allowing the passage of the gas in at least a part of it; and the outer pipe has a large number of gas outlet ports for discharging the gas having passed through the sintered body into the vacuum vessel. 
     A method of producing an electronic device according to the invention comprises a step of processing a substrate in a vacuum processing apparatus provided with a gas supply pipe for supplying a gas into a vacuum vessel, wherein the gas supply pipe is a double-layer pipe comprising an inner pipe connected to a gas introduction pipe and an outer pipe for covering the outer peripheral portion of the inner pipe with a gap between them; the inner pipe has a porous sintered body for allowing the passage of the gas in at least a part of it; and the outer pipe has a large number of gas outlet ports for discharging the gas having passed through the sintered body into the vacuum vessel. 
     EFFECTS OF THE INVENTION 
     According to the present invention, the gas supply pipe has a double-layer pipe structure, and the gas is diffused in the outer pipe upon passing through the porous sintered body surface of the inner pipe and discharged from a large number of gas outlet ports of the outer pipe. Therefore, even if the gas supply pipe has a long overall length, the gas can be supplied uniformly, and uniformity in film quality can be secured. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A and 1B  are schematic views exemplifying the vacuum processing apparatus of a first embodiment provided with a gas supply device according to the invention. 
         FIG. 2  is a schematic view showing a structure of the gas supply device of the embodiment. 
         FIGS. 3A ,  3 B and  3 C are schematic views exemplifying cross section structures of gas supply pipes of the gas supply device. 
         FIG. 4  is a schematic view exemplifying the vacuum processing apparatus according to a second embodiment. 
         FIGS. 5A ,  5 B and  5 C are schematic views exemplifying the vacuum processing apparatus according to a third embodiment. 
         FIG. 6  is a schematic view exemplifying the vacuum processing apparatus according to a fourth embodiment. 
         FIG. 7  is a schematic view showing a structure of the gas supply device according to another example. 
     
    
    
     MODE FOR CARRYING OUT THE INVENTION 
     Embodiments of the present invention are described below with reference to the drawings, but the present invention is not limited to the embodiments. 
     First Embodiment 
     &lt;Vacuum Processing Apparatus&gt; 
     First, a first embodiment of the vacuum processing apparatus according to the invention is described with reference to  FIGS. 1A and 1B .  FIGS. 1A and 1B  show the vacuum processing apparatus of the first embodiment provided with the gas supply device according to the invention,  FIG. 1A  is a schematic front view, and  FIG. 1B  is a schematic right side view. 
     As shown in  FIGS. 1A and 1B , a vacuum processing apparatus  1  of this embodiment is provided with a vacuum vessel  4  which defines a processing space  3  for a substrate  2 . A substrate support base  5  on which the substrate  2  is placed is provided at the center in the vacuum vessel  4 . For example, the substrate support base  5  is constructed such that it supports the substrate  2  on its placing surface by an electrostatic adsorption method and can be rotated and moved vertically. 
     A cathode unit  6  is disposed on the top in the vacuum vessel  4  in opposite to the substrate support base  5 . The cathode unit  6  is provided with a magnet unit which supports a target on the front surface side of a cathode casing and applies a magnetic field to the target on the back surface side. In addition, an exhaust port  7  which is connected to an unshown exhaust system (exhaust pump) is disposed on the bottom of the vacuum vessel  4  to exhaust the vacuum vessel in order to keep it in a vacuum state. 
     And, a gas supply pipe  21  of a gas supply device  20  to be described later in detail is disposed along a side wall of the vacuum vessel  4  and connected with a gas introduction pipe  22 , and a processing gas containing a reactive gas is supplied through gas outlet ports  26  (see  FIG. 2 ) of the gas supply pipe  21  into the vacuum vessel. The gas introduction pipe  22  is connected to a gas introducing system including a gas source. 
     In this embodiment, the gas outlet ports  26  of the gas supply pipe  21  are formed to face the top wall of the vacuum vessel  4  and directed in the opposite direction from the substrate  4 . Therefore, the flow of the gas supplied through the gas outlet ports  26  of the gas supply pipe  21  collides against the top wall surface of the vacuum vessel  2  to move toward the processing space at the center of the vessel, so that the gas flow becomes more uniform. 
     &lt;Gas Supply Device&gt; 
     A specific structure of the gas supply device  20  of this embodiment is described below with reference to  FIG. 2 .  FIG. 2  is a schematic view showing the structure of the gas supply device of this embodiment. 
     As shown in  FIG. 2 , the gas supply device  20  is a device provided with the gas supply pipe  21  for supplying the processing gas into the vacuum vessel, and the gas supply pipe  21  is a double-layer pipe comprising an inner pipe  23  connected to the gas introduction pipe  22  and an outer pipe  24  which covers the outer peripheral portion of the inner pipe  23  with a space between them. 
     The gas introduction pipe  22  is extended from the gas source and connected to a longitudinal center part of the inner pipe  23  through a longitudinal center part of the outer pipe  24 . The connection to the center part of the inner pipe  23  as described above is to homogenize the gas discharge amount from the gas supply pipe  21 . And, a porous sintered body  25  is partly interposed (intermediate part) in the inner pipe  23  and has a porous sintered body surface which allows the passage of the gas. 
     The outer pipe  24  is formed with multiple gas outlet ports  26  for flowing the gas, which is introduced from the gas introduction pipe  22  into the inner pipe  23  and passed through the sintered body surface, into the vacuum vessel. The gas outlet ports  26  are formed in a large number in the longitudinal direction of the outer pipe  24  and open to the top wall of the vacuum vessel  2  as described above. And, a formation range L of the gas outlet ports  26  of the outer pipe  24  is set to be larger than a width (outer diameter) D of the substrate  2  which is processed in the vacuum vessel. 
     To homogenize the gas discharge amount from the outer pipe  24 , the sintered body surface of the inner pipe  23  is arranged symmetrically on either side of a width-direction center (radial center) of the substrate  2  and positioned at the center of each of right and left portions  24   a  and  24   a  of the outer pipe  24 , which are divided at the connection of the gas introduction pipe  22 . Here, even if the inner pipe  23  has a length merely enough to the sintered body  25 , the gas volume is variable depending on positions within the outer pipe  24 , so that it is necessary to extend the outer pipe  24  in order to homogenize the gas discharge amount. Therefore, when the inner pipe  23  is extended more than the sintered body  25  within the outer pipe  24 , it is not necessarily required to be hollow. 
     An embodiment of a cross section structure of the above-described gas supply pipe  21  is described below with reference to  FIGS. 3A to 3C .  FIGS. 3A to 3C  are schematic views exemplifying cross section structures of the gas supply pipe  21  of the gas supply device  20 . 
     The gas supply pipe  21  exemplified in  FIG. 3A  is an example that a cylindrical porous sintered body  25  is interposed at an intermediate part of the inner pipe  23 . For the sintered body  25 , for example, a metal sintered body obtained by powder metallurgy can be used. As a component metal, it is preferable to use metal such as aluminum or stainless steel (SUS) having heat resistance and corrosion resistance. The sintered body  25  is preferably formed of sintered granules of several micrometers and disposed at the intermediate part of the inner pipe  23  by using a bonding means such as welding such that its pores are not clogged. The outer pipe  24  covers the outer peripheral portion of the inner pipe  23  with an interval between them, and the gas outlet ports  26  are formed in its top. 
     The gas supply pipe  21  of another embodiment exemplified in  FIG. 3B  has the upper half surface of a cylindrical sintered body  25  which is interposed at the intermediate part of the inner pipe  23  covered by a cover member  30  having a half-split short tubular shape. The outer pipe  24  covers the outer peripheral portion of the inner pipe  23  with a gap between them, and the gas outlet ports  26  are formed in the top. In other words, the sintered body surface of the inner pipe  23  within the outer pipe  24  is directed in a direction opposite to the formed side of the gas outlet ports  26  of the outer pipe  24 . In this embodiment, since the upper half surface of the sintered body  25  is covered by the cover member  30  having a half-split short tubular shape, the gas in the inner pipe  23  is supplied to the sintered body  25  and discharged from the sintered body surface toward a direction opposite to the gas outlet ports  26  formed in the outer pipe  24 . Thus, the gas is rectified and readily supplied at a constant flow rate into the vacuum vessel. 
     The inner pipe itself may be formed of a cylindrical sintered body  25  as in the gas supply pipe  21  according to another embodiment exemplified in  FIG. 3C . 
     Using the gas supply pipes  21  having the structures described above maintain a constant flow rate distribution of the processing gas discharged from the gas outlet ports  26  of the outer pipe  24 . It is desirable that the number of the gas outlet ports  26  are larger, but it is normally adequate to have approximately one gas outlet port  26  in each portion at intervals of 50 mm in the longitudinal direction of the outer pipe  24 . And, since the external shape of the gas supply pipe  21  is not complex, its installation place is hardly restricted. A method of adjusting the flow rate to the gas introduction pipe  2  is not limited, but it is desirable to control it by a mass flow controller or the like. 
     As described above, according to the gas supply device  20  of this embodiment, the gas supply pipe  21  has a double-layer pipe structure, and the gas is diffused in the outer pipe  24  upon passing through the porous sintered body surface of the inner pipe  23  and discharged from the large number of gas outlet ports  26  of the outer pipe  24 . Therefore, even if the gas supply pipe  21  has a long overall length, the gas can be supplied uniformly, and uniformity in film quality can be secured. 
     Second Embodiment 
     A vacuum processing apparatus  100  of a second embodiment is described below with reference to  FIG. 4 .  FIG. 4  is a schematic sectional view exemplifying the vacuum processing apparatus of the second embodiment. For description, like component members corresponding to those of the first embodiment are denoted by like reference numerals. 
     As shown in  FIG. 4 , in the vacuum processing apparatus  100  of the second embodiment, unshown substrate entrance and substrate exit are formed in both sides of the vacuum vessel  4  which defines the processing space  3 , and a long substrate (or belt-shaped substrate)  102  is conveyed along rollers  105 . The bottom of the vacuum vessel  4  is provided with an exhaust port  7  which is connected to an exhaust system for exhausting the processing space  3 . 
     And, two cathode units  6  are disposed at upper portions in the vacuum vessel  4  in a direction that the long substrate  102  is conveyed, and continuous film forming processing is performed within the vacuum vessel. The gas supply pipe  21  of the above-described gas supply device  20  for supplying a processing gas containing a reactive gas into the vacuum vessel at the time of the film forming processing is disposed between the two cathode units  6 . The gas supply pipe  21  is extended along a direction (width direction) intersecting at right angles to the longitudinal direction of the long substrate  102 . 
     The gas supply pipe  21  is formed with the gas outlet ports  26  in the top of the outer pipe  24  and discharges the gas toward the top wall of the vacuum vessel  4  (see  FIGS. 3A ,  3 B and  3 C). 
     The vacuum processing apparatus  100  of the second embodiment can use the gas supply device  20  having the structure described above to maintain a constant flow rate distribution of the processing gas discharged from the gas outlet ports  26  of the gas supply pipe  21 . In other words, in the vacuum processing apparatus  100  of the second embodiment, the processing gas supplied from the gas supply device  20  flows without suffering from disturbance of its distribution to the processing space  3  between the target and the long substrate  102 . 
     Third Embodiment 
     A vacuum processing apparatus  200  of a third embodiment is described below with reference to  FIGS. 5A ,  5 B and  5 C. 
       FIG. 5A  is a schematic view of the vacuum processing apparatus of the third embodiment viewed see-through from above.  FIG. 5B  is a schematic sectional view taken along A-A′ of the vacuum processing apparatus shown in  FIG. 5A .  FIG. 5C  is a schematic sectional view taken along B-B′ of the vacuum processing apparatus shown in  FIG. 5A . 
     The vacuum processing apparatus  200  of the third embodiment has a structure that the gas supply pipe  21  of the second embodiment is further surrounded by a shield  40  having a rectangular box shape. In this embodiment, the gas supply pipe  21  has the gas outlet ports  26  formed in the top of the outer pipe  24  and discharges the gas toward the top wall of the vacuum vessel  4  in the same manner as in the second embodiment. According to this structure, the gas supplied from the gas outlet ports  26  of the gas supply pipe  21  collides against the top wall surface of the vacuum vessel  4  and then against the shield  40 , so that the gas is hard to diffuse freely within the vacuum vessel  4 . 
     Among the side walls of the shield  40 , a gap is provided between each side wall which extends in a direction (width direction) intersecting at right angles to the longitudinal direction of the long substrate  102  and the top wall surface of the vacuum vessel  4 . Meanwhile, no gap is provided between the side walls of the shield  40 , which extend in the longitudinal direction (traveling direction of long substrate) of the long substrate  102 , and the top wall surface of the vacuum vessel  4 . Namely, it is configured such that the gas does not flow out from both width-direction ends of the shield  40 . 
     Thus, the flow of the gas supplied from the gas outlet ports  26  of the gas supply pipe  21  collides against the top wall surface of the vacuum vessel  4  and then introduced into the vacuum vessel  4  from only the gap between the side walls of the shield  40  extended in the width direction of the long substrate  102  and the top wall surface of the vacuum vessel  4 . Therefore, the gas flow to only the processing space in the vicinity of the cathode unit  6  becomes more uniform and the gas is supplied there. 
     Since the gas outlet ports  26  of the gas supply pipe  21  are formed in the top of the outer pipe  24  and discharge the gas toward the top wall of the vacuum vessel  4 , the gas flows to the processing space in the vicinity of the two cathode units  6 , which are disposed upstream and downstream in a conveying direction of the long substrate  102 , become equal to each other. 
     The gap between the side walls of the shield  40  extended in the width direction of the long substrate  102  and the top wall surface of the vacuum vessel  4  is desirably of a size not larger than the mean free path of gas molecules being supplied. When the gap is not less than the mean free path of the gas molecules, the gas is diffused in the vacuum vessel  4  and cannot be supplied uniformly from the gaps between the top wall surface of the vacuum vessel  4  and the side walls of the shield  40  extended in the width direction of the long substrate  102  into only the processing space in the vicinity of the cathode unit  6 . 
     Since the mean free path of Ar, O2 and N2 is about 6 mm when a processing pressure is 1 Pa, the gaps between the top wall surface of the vacuum vessel  4  and the side walls of the shield  40  extended in the width direction of the long substrate  102  must be made smaller than 6 mm. 
     Fourth Embodiment 
     A vacuum processing apparatus  300  of a fourth embodiment is described below with reference to  FIG. 6 .  FIG. 6  is a schematic view exemplifying the vacuum processing apparatus of the fourth embodiment. For description, like component members corresponding to those of the first, second and third embodiments are denoted by like reference numerals. 
     In the vacuum processing apparatus  300  of the fourth embodiment, the gas supply pipe  21  of the gas supply device  20  is disposed near each end portion of two cathode units  6  on the side of the side wall in the substrate conveying direction. In this embodiment, the gas outlet ports  26  of the gas supply pipe  21  are also formed in the top of the outer pipe  24 , and the gas is discharged toward the top wall of the vacuum vessel  4  (see  FIG. 4 ). The discharge direction is not limited to the above, but the gas outlet ports  26  may be formed in the outer pipe  24  to face the direction of each target. 
     The vacuum processing apparatus  300  of the fourth embodiment can use the gas supply device  20  having the above-described structure to maintain a constant flow rate distribution of the processing gas discharged from the gas outlet ports  26  of the gas supply pipe  21 . In other words, in the vacuum processing apparatus  300  of the fourth embodiment, the processing gas supplied from the gas supply device  20  flows without suffering from disturbance of its distribution to the processing space  3  between the targets and the long substrate  102 . 
     Although the invention has been described above by reference to the embodiments of the invention, the invention is not limited to the embodiments described above. It is to be understood that modifications and variations of the embodiments can be made without departing from the spirit and scope of the invention. 
     [Another Example of Gas Supply Device] 
     Another example of the gas supply device  20  is described below with reference to  FIG. 7 .  FIG. 7  is a schematic view showing a structure of the gas supply device according to this example. For description, like component members corresponding to those of the gas supply device  20  of the first embodiment are denoted by like reference numerals. 
     As shown in  FIG. 7 , this gas supply device is similar to the gas supply device  20  shown in  FIG. 2  and provided with the gas supply pipe  21  having a double-layer pipe structure comprising the inner pipe  23  connected to the gas introduction pipe  22  and the outer pipe  24  which covers the outer peripheral portion of the inner pipe  23  with a gap between them, but the gas supply pipe  21  has a C-shaped circular shape. And, the gas introduction pipe  22  is connected to the center of a curve length of the inner pipe  23  having the same C shape through the center of a curve length of the outer pipe  24  having the same C shape. A large number of gas outlet ports  26  are formed in the outer pipe  24  to flow the gas, which is introduced from the gas introduction pipe  22  to the inner pipe  23  and passed through the porous sintered body  25 , into the vacuum vessel. The large number of the gas outlet ports  26  are formed at regular intervals in the inner circumferential surface of the outer pipe  24 . 
     When the gas supply device  20  of this example is disposed between the cathode unit  6  and the substrate  2  shown in, for example,  FIG. 1 , the gas can be securely supplied to the space between the cathode unit  6  and the substrate. 
     In this example, the gas outlet ports  26  are formed in the inner circumferential surface of the outer pipe  24 , but the gas outlet ports  26  can also be formed in an outer circumferential surface, a top surface or a bottom surface of the outer pipe  24 . 
     For example, the vacuum processing apparatus according to the embodiments of the invention can also be applied to the vacuum processing apparatus which is used in the film forming process for producing an electronic device such as a large flat-panel display (liquid crystal display), a thin-film solar cell panel, a microinductor or a magnetic recording head. 
     EXPLANATION OF REFERENCE NUMERALS 
     
         
           1 ,  100 ,  200 ,  300 : Vacuum processing apparatus 
           2 ,  102 : Substrate 
           3 : Processing space 
           4 : Vacuum vessel 
           5 : Substrate support base 
           6 : Cathode unit 
           7 : Exhaust port 
           20 : Gas supply device 
           21 : Gas supply pipe 
           22 : Gas introduction pipe 
           23 : Inner pipe 
           24 : Outer pipe 
           25 : Sintered body 
           26 : Gas outlet ports 
           30 : Cover member 
           40 : Shield