Patent Publication Number: US-9894745-B2

Title: Antenna structure and plasma generating device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This is a divisional of U.S. application Ser. No. 13/990,840, filed on May 31, 2013, with a 371(c) date of Jul. 2, 2013, which is a National Phase of PCT/KR2011/006887, filed Sep. 16, 2011, the entire contents of each of which are hereby incorporated by reference. 
    
    
     TECHNICAL FIELD 
     The inventive concepts described herein relate to a plasma generating device, and more particularly, relate to an antenna structure capable of generating inductive coupling plasma 
     Background Art 
     Large-scaled substrates such as a semiconductor substrate, a flat panel display substrate, a solar cell substrate, etc. may necessitate large-scaled fabricating devices for treating them. A plasma treatment device may be used for various processes such as etching, deposition, ion implantation, material surface treatment, etc. 
     DISCLOSURE 
     Technical Problem 
     The present invention provides an antenna structure capable of forming plasma uniformly. 
     The present invention also provides a plasma generating device capable of forming plasma uniformly. 
     Technical Solution 
     The antenna structure includes four induction antennas which have the same structure, are connected in parallel and are disposed to be overlapped. The induction antennas include an external upper section disposed on a first quadrant of a first layer, an internal upper section connected to the external upper section and disposed on a second quadrant of the first layer, an internal lower section connected to the internal upper section and disposed on a third quadrant of a second layer disposed on a lower part of the first layer, and an external lower section connected to the internal lower section and disposed on a fourth quadrant of the second layer. An RF power is supplied to one end of the external upper section, and the other end of the external lower section is grounded. 
     Advantageous Effects 
     With an embodiment of the present invention, an antenna structure provides inductive coupling plasma stably and uniformly. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1A  is a diagram schematically illustrating an antenna structure according to an embodiment of the present invention. 
         FIG. 1B  is a plan view of an antenna structure of  FIG. 1A . 
         FIG. 1C  is a cross-sectional view taken along a line I-I′ of  FIG. 1B . 
         FIG. 2A  is a diagram schematically illustrating an antenna structure according to another embodiment of the present invention. 
         FIG. 2B  is a plan view of an antenna structure of  FIG. 2A . 
         FIG. 2C  is a cross-sectional view taken along a line II-II′ of  FIG. 2B . 
         FIG. 3A  is a diagram schematically illustrating an antenna structure according to still another embodiment of the present invention. 
         FIG. 3B  is a cross-sectional view of an antenna structure of  FIG. 3A . 
         FIG. 4  is a diagram schematically illustrating an antenna structure according to still another embodiment of the present invention. 
         FIG. 5  is a diagram schematically illustrating a plasma generating device according to an embodiment of the present invention. 
         FIG. 6  is a cross-sectional view of a plasma generating device of  FIG. 5 . 
         FIG. 7  is a diagram schematically illustrating a plasma generating device according to another embodiment of the present invention. 
     
    
    
     MODE FOR INVENTION 
     A large-scaled plasma treatment device has to secure high plasma density, uniformity of plasma density, and process repeatability. Inductive coupling plasma may obtain high plasma. However, it is difficult to secure uniformity of plasma. 
     The present invention will now be described in detail with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. However, the inventive concept is not limited thereto. Rather, embodiments introduced here may be provided such that disclosed contents become thorough and perfect and the spirit of the present invention is sufficiently provided to one skilled in the art. In figures, thickness of layers (or, films) and areas may be exaggeratedly illustrated. Also, in a case where a layer (or, film) is described to be put “on” another layer (or, film) or a substrate, a layer (or, film) may be directly put on another layer (or, film) or a substrate or on another layer (or, film) or a substrate with a third layer (or, film) interposed therebetween. Portions marked by the same reference numbers over the specification may indicate the same constituent elements. 
       FIG. 1A  is a diagram schematically illustrating an antenna structure according to an embodiment of the present invention. 
       FIG. 1B  is a plan view of an antenna structure of  FIG. 1A . 
       FIG. 1C  is a cross-sectional view taken along a line I-I′ of  FIG. 1B . 
     Referring to  FIGS. 1A to 1C , the antenna structure  100  may include four induction antennas  101  which have the same structure, are connected in parallel with one another, and are disposed to be overlapped. Each of the induction antennas  101  may include an external upper section  110  disposed on a first quadrant of a first layer; an internal upper section  112  connected to the external upper section  110  and disposed on a second quadrant of the first layer; an internal lower section  122  connected to the internal upper section  112  and disposed on a third quadrant of a second layer disposed at a lower part of the first layer; and an external lower section  120  connected to the internal lower section  122  and disposed on a fourth quadrant of the second layer. One ends P 1 , P 2 , P 3 , and P 4  of the external upper sections  110  may be supplied with an RF power, and the other ends G 1 , G 2 , G 3 , and G 4  of the external lower sections  120  may be grounded. The induction antennas  101  may be rotated by 90 degrees with respect to a central axis to be overlapped with one another. 
     In the antenna structure  100  according to an embodiment of the present invention, four induction antennas  101  may be electrically connected in parallel with one another. This may allow the antenna structure  100  to have low impedance, so that a high current is applied. Also, each of the induction antennas  101  may be interconnected without disconnection to form a loop. In this case, the induction antennas  101  may substantially form a closed loop to generate a maximal inducted electromotive force. A symmetrical shape of the antenna structure  100  may enable a symmetrical property of plasma in a rotation direction to be improved. Also, external sections  110  and  120  may form plasma outside, and the internal sections  112  and  122  may form plasma inside. Thus, radial uniformity of plasma may be improved. 
     The induction antennas  101  may be supplied with the RF power at the first layer and grounded at the second layer. Also, a current may flow through the induction antennas  101  in one direction such as a clockwise direction or counterclockwise direction. Thus, with the bi-level structure, it is possible to suppress such a phenomenon that a plasma density is locally increased due to capacitive coupling and inductive coupling at a location where the RF power is supplied. 
     The external upper section  110  may have a first curvature radius, and may be disposed at the first quadrant of the first layer. The external upper section  110  may have a metal or metal alloy strip or pipe shape. Desirably, the external upper section  110  may be formed of silver or gold plated copper. The external upper section  110  may have a thickness ranging from several millimeters to dozens millimeters. Desirably, the external upper section  110  may have a thickness ranging from 10 millimeters to 20 millimeters. The external upper section  110  can have a thickness of about several millimeters. One end of the external upper section  110  may be supplied with the RF power. The external upper sections  110  may be symmetrically disposed to form a peripheral area. 
     The internal upper section  112  may have a second curvature radius, and may be disposed on the second quadrant at substantially the same plane as the first layer. The internal upper section  112  may be disposed in an area which is formed by the external upper sections  110 . The first curvature radius may be more than the second curvature radius. A current may flow into the induction antenna  101  in a clockwise direction. The internal upper sections  112  may be adjacent to the external upper sections, and may be disposed continuously in a rotation direction. 
     An upper branch  114  may connect the other end of the external upper section  110  and one end of the internal upper section  112 . The upper branch  114  may be formed of the same material as that of the external upper section  110 . The upper branch  114  and the external upper section  110  may be connected by electric connection means such as bolts and/or welding. The upper branch  114  and the internal upper section  112  may be connected by electric connection means such as bolts and/or welding. 
     A vertical branch  130  may connect the other end of the internal upper section  112  and one end of the internal lower section  122 . The vertical branch  130  may connect the first layer and the second layer. 
     The internal lower sections  122  may be adjacent to the internal upper sections  112 , and may be disposed continuously in a rotation direction. 
     The internal lower section  122  may be disposed at the second layer disposed under the first layer. The internal lower section  122  may be disposed on the third quadrant. An interval between the first layer and the second layer may be several millimeters to dozens millimeters. Desirably, an interval between the first layer and the second layer may be 10 millimeters to 15 millimeters. The internal lower section  122  may have the second curvature radius. An insulator  103  may be disposed between the first layer and the second layer. 
     A lower branch  124  may connect the other end of the internal lower section  122  and one end of the external lower section  120 . 
     The external lower section  120  may be disposed on the fourth quadrant of the second layer. The external lower section  120  may have the first curvature radius. The other end of the external lower section  120  may be grounded. 
     Widths of the internal lower and upper sections  122  and  112  may be wider than those of the external lower and upper sections  120  and  110 . Thus, a plasma generation space formed by the external upper section  110  and the external lower section  120  may be reduced, and a plasma generation space formed by the internal upper section  112  and the internal lower section  122  may be increased. This may mean that plasma uniformity in a radial direction increases. 
     To form large area plasma according to a large scaled plasma generating device, the RF power supplied to the antenna structure may run to nearly several KW to dozens KW. Also, divice&#39;s simplicity may be required. In recent years, to form large area plasma according to a large scaled plasma generating device, the RF power supplied to the antenna structure may run to nearly several KW to dozens KW. Thus, cooling may be required for thermal stability of the antenna structure  100 . Also, device&#39;s simplicity may be required. Thus, the induction antennas  101  may have a pipe shape, and may be cooled by refrigerant such as air or fluid. The refrigerant may flow through insides of the induction antennas  101 . 
       FIG. 2A  is a diagram schematically illustrating an antenna structure according to another embodiment of the present invention. 
       FIG. 2B  is a plan view of an antenna structure of  FIG. 2A . 
       FIG. 2C  is a cross-sectional view taken along a line II-II′ of  FIG. 2B . 
     Referring to  FIGS. 2A to 2C , the antenna structure  200  may include four induction antennas  201  which have the same structure, are connected in parallel with one another, and are disposed to be overlapped. Each of the induction antennas  201  may include an external upper section  210  disposed on a first quadrant of a first layer; an internal upper section  212  connected to the external upper section  210  and disposed on a second quadrant of the first layer; an internal lower section  222  connected to the internal upper section  212  and disposed on a third quadrant of a second layer disposed at a lower part of the first layer; and an external lower section  220  connected to the internal lower section  222  and disposed on a fourth quadrant of the second layer. One ends P 1 , P 2 , P 3 , and P 4  of the external upper sections  210  may be supplied with an RF power, and the other ends G 1 , G 2 , G 3 , and G 4  of the external lower sections  220  may be grounded. The induction antennas  201  may be rotated by 90 degrees with respect to a central axis to be overlapped with one another. 
     In the antenna structure  200  according to an embodiment of the present invention, four induction antennas  201  may be electrically connected in parallel with one another. This may allow the antenna structure  200  to have low impedance, so that a high current is applied. Also, each of the induction antennas  201  may be interconnected without disconnection to form a loop. In this case, the induction antennas  201  may substantially form a closed loop to generate a maximal inducted electromotive force. A symmetrical shape of the antenna structure  200  may enable a symmetrical property of plasma in a rotation direction to be improved. Also, the external sections  210  and  220  may form plasma outside, and the internal sections  212  and  222  may form plasma inside. Thus, radial uniformity of plasma may be improved. 
     The induction antennas  201  may be supplied with the RF power at the first layer and grounded at the second layer. Also, a current may flow through the induction antennas  201  in one direction such as a clockwise direction or counterclockwise direction. Thus, with the bi-level structure, it is possible to suppress such a phenomenon that a plasma density is locally increased due to capacitive coupling and inductive coupling at a location where the RF power is supplied. 
     The external upper section  210  may be bent at a right angle, and may be disposed on the first quadrant of the first layer. The external upper section  210  may have a metal or metal alloy strip or pipe shape. Desirably, the external upper section  210  may be formed of silver or gold plated copper. The external upper section  210  may have a thickness ranging from several millimeters to dozens millimeters. Desirably, the external upper section  210  may have a thickness ranging from 10 millimeters to 20 millimeters. The external upper section  210  can have a thickness of about several millimeters. One end of the external upper section  210  may be supplied with the RF power. The external upper sections  210  may be symmetrically disposed to form a peripheral area. 
     The internal upper section  212  may be bent at a right angle, and may be disposed on the second quadrant at substantially the same plane as the first layer. The internal upper section  212  may be disposed in an area which is formed by the external upper sections  210 . An area occupied by the internal upper section  212  may be wider than an area occupied by the external upper section  210 . A current may flow into the induction antenna  201  in a clockwise direction. The internal upper sections  212  may be adjacent to the external upper sections, and may be disposed continuously in a rotation direction. 
     An upper branch  214  may connect the other end of the external upper section  210  and one end of the internal upper section  212 . The upper branch  214  may be formed of the same material as that of the external upper section  210 . The upper branch  214  and the external upper section  210  may be connected by electric connection means such as bolts and/or welding. The upper branch  214  and the internal upper section  212  may be connected by electric connection means such as bolts and/or welding. 
     A vertical branch  230  may connect the other end of the internal upper section  212  and one end of the internal lower section  222 . The vertical branch  230  may connect the first layer and the second layer. 
     The internal lower sections  222  may be adjacent to the internal upper sections  212 , and may be disposed continuously in a rotation direction. The internal lower section  222  may be disposed at the second layer disposed under the first layer. The internal lower section  222  may be disposed on the third quadrant. An interval between the first layer and the second layer may be several millimeters to dozens millimeters. Desirably, an interval between the first layer and the second layer may be 10 millimeters to 15 millimeters. The internal lower section  222  may be bent at a right angle. 
     A lower branch  224  may connect the other end of the internal lower section  222  and one end of the external lower section  220 . 
     The external lower section  220  may be disposed on the fourth quadrant of the second layer. The external lower section  220  may be bent at a right angle. The other end of the external lower section  220  may be grounded. 
     Widths of the internal lower and upper sections  222  and  212  may be wider than those of the external lower and upper sections  220  and  210 . Thus, a plasma generation space formed by the external upper section  210  and the external lower section  220  may be reduced, and a plasma generation space formed by the internal upper section  212  and the internal lower section  222  may be increased. This may mean that plasma uniformity in a radial direction increases. 
       FIG. 3A  is a diagram schematically illustrating an antenna structure according to still another embodiment of the present invention. 
       FIG. 3B  is a cross-sectional view of an antenna structure of  FIG. 3A . 
     Referring to  FIGS. 3A and 3B , the antenna structure  100   a  may include four induction antennas  101   a  which have the same structure, are connected in parallel with one another, and are disposed to be overlapped. the induction antennas  101   a  may include an external upper section  110   a  disposed on a first quadrant of a first layer  141 ; an internal upper section  112   a  connected to the external upper section  110   a  and disposed on a second quadrant of a second layer  142  disposed at an upper part of the first layer; an internal lower section  122   a  connected to the internal upper section  112   a  and disposed on a third quadrant of a third layer  143  disposed at a lower part of the second layer; and an external lower section  120   a  connected to the internal lower section  112   a  and disposed on a fourth quadrant of a fourth layer  144  disposed at a lower part of the first layer  141 . One end of the external upper section  110   a  may be supplied with an RF power, and the other end of the external lower section  120   a  may be grounded. 
     An upper branch  114   a  may connect the other end of the external upper section  110   a  and one end of the internal upper section  112   a . A vertical branch  130   a  may connect the other end of the internal upper section  112   a  and one end of the internal lower section  122   a . A lower branch  124  may connect the other end of the internal lower section  122   a  and one end of the external lower section  120   a.    
       FIG. 4  is a diagram schematically illustrating an antenna structure according to still another embodiment of the present invention. 
     Referring to  FIG. 4 , the antenna structure  300  may include two induction antennas  301  which have the same structure, are connected in parallel with one another, and are disposed to be overlapped. the induction antennas  301  may include an external upper section  310  disposed over a first quadrant and a second quadrant of a first layer; an internal upper section  312  connected to the external upper section  310  and disposed over a third quadrant and a fourth quadrant of the first layer; an internal lower section  322  connected to the internal upper section  312  and disposed over a first quadrant and a second quadrant of a second layer disposed at a lower part of the first layer; and an external lower section  320  connected to the internal lower section  322  and disposed over a third quadrant and a fourth quadrant of the second layer. One end of the external upper section  310  may be supplied with an RF power, and the other end of the external lower section  320  may be grounded. 
     An upper branch  314  may connect the other end of the external upper section  310  and one end of the internal upper section  312 . A vertical branch  330  may connect the other end of the internal upper section  312  and one end of the internal lower section  322 . A lower branch  324  may connect the other end of the internal lower section  322  and one end of the external lower section  320 . 
       FIG. 5  is a diagram schematically illustrating a plasma generating device according to an embodiment of the present invention. 
       FIG. 6  is a cross-sectional view of a plasma generating device of  FIG. 5 . Referring to  FIGS. 5 and 6 , a plasma generating device may include a vacuum container  50 , a dielectric unit  58  disposed at a part of the vacuum container  50 , and an antenna structure for plasma generation  400   a  and  400   b  disposed on the dielectric unit  58 . The antenna structure  400   a  and  400   b  may include a first antenna structure  400   a  and a second antenna structure  400   b . The first antenna structure  400   a  may be disposed in the second antenna structure  400   b.    
     The first antenna structure  400   a  and the second antenna structure  400   b  may be connected to a power distribution unit  62 . The power distribution unit  62  may distribute a power to the first antenna structure  400   a  and the second antenna structure  400   b . The power distribution unit  62  may be formed of passive elements such as inductors, capacitors, and so on. 
     An RF power  66  may supply a power to the antenna structure  400   a  and  400   b  through an impedance matching network  64  and the power distribution unit  62 . The first antenna structure  400   a  and the second antenna structure  400   b  may be electrically connected in parallel. The antenna structure may include four induction antennas which have the same structure, are connected in parallel with one another, and are disposed to be overlapped. Each of the induction antennas may include an external upper section disposed on a first quadrant of a first layer; an internal upper section connected to the external upper section and disposed on a second quadrant of the first layer; an internal lower section connected to the internal upper section and disposed on a third quadrant of a second layer disposed at a lower part of the first layer; and an external lower section connected to the internal lower section and disposed on a fourth quadrant of the second layer. One end of the external upper section may be supplied with an RF power, and the other end of the external lower section may be grounded. 
       FIG. 7  is a diagram schematically illustrating a plasma generating device according to another embodiment of the present invention. 
     Referring to  FIG. 7 , the plasma generating device may include a vacuum container  50 , a dielectric unit  58   a  disposed at a part of the vacuum container  50 , and an antenna structure for plasma generation  100  disposed on the dielectric unit  58   a.    
     The dielectric unit  58   a  may include a plurality of dielectric portions spaced apart from one another. The antenna structure  100  may include a plurality of antenna structures spaced apart from one another. The antenna structures may be put on corresponding dielectric portions, respectively. 
     With a modified embodiment of the present invention, the antenna structure may be changed with an antenna structure described with reference to  FIGS. 1 to 4 .