Abstract:
A load simulator and switch are connected to a power source of a plasma processing device. The switch allows the load simulator to be electrically connected to the power source to allow testing of the power source. The switch and load simulator allow the testing of the power source without mechanically removing the power source from the plasma processing device. In addition, the switch allows the connection of the load simulator to the power source while the power source is on, avoiding the requirement of turning off the power source before connecting the load simulator.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to plasma devices. More particularly, the present invention relates to an improved plasma processing device. 
     Plasma processing devices may be used in manufacturing. Plasma processing devices may use power systems to generate and sustain a plasma. 
     To facilitate discussion, FIG. 1 is a schematic view of a prior plasma processing device  10 , comprising a plasma process unit  12 , a pump manifold  14  supporting the plasma process unit  12 , a lower transfer chamber  16  supporting the pump manifold  14 , and a power source  18  connected to the lower transfer chamber  16 . The plasma process unit  12 , pump manifold  14 , and lower transfer chamber  16  collectively form a plasma process module. The plasma process unit  12 , comprises an upper electrode  20  spaced apart from a lower electrode  22 . A lead  24  extends from the lower electrode  22 , through the pump manifold  14  and the lower transfer chamber  16  to provide an electrical connection between the lower electrode  22  and the power source  18 . An example of a power source  18  is a One Box™ radio frequency (rf) power source, which comprises a first generator  28 , a second generator  30 , and a match box  32  electrically connected to the first generator  28  and the second generator  30 . In this example, the first generator  28  provides a 2 MHz output and the second generator  30  provides a 27 MHz output. The match box  32  may provide electrical diagnostics and impedance matching. An output connector  34  extends from the match box  32 . The lead  24  is electrically connected to the output connector  34 , which may be a 5 inch diameter piece of silver coated copper plug and where the lead may be connected to the output connector  34  by a screw or bolt. Nut and bolt sets  36  may provide a mechanical connection to connect the power source  18  to the lower transfer chamber  16 . A bottom cover  38  covers the bottom of the lower transfer chamber  16 . An interlock switch  40  is placed near the cover  38  and is electrically connected to the first generator  28  and the second generator  30 , so that when the cover is removed from the lower transfer chamber  16  the interlock switch  40  causes the first generator  28  and the second generator  30  to be powered down to reduce electrical shock hazards. 
     In the testing of the power source  18  in the prior art, to facilitate discussion, FIG. 2 is a schematic view of a power source  18  of a plasma processing device being tested and FIG. 3 is a flow chart of the testing procedure of the power source  18 . 
     In the testing of the power source  18 , a power source problem may be suspected (step  304 ). The first and second generators  28 ,  30  may be turned off and powered down (step  308 ). The power source  18  may be disconnected from the plasma process module (step  312 ), which might take 15 to 30 minutes. To do this, the bottom cover  38  may be removed from the lower transfer chamber  16  to provide access to nut and bolt sets  36 . The removal of the bottom cover  38  may trigger the interlock switch  40 , which may shut down the generators  28 ,  30  if they are not already turned off. The nut and bolt sets  36  may be removed. Typically a power source  18  may be connected by 6 to 7 nut and bolt sets  36 . In addition, the lead  24  may be disconnected from the output connector  34 . The power source  18  may be moved away from the plasma process module (step  316 ) to create enough space to connect the load simulator  44 , which might take 5-45 minutes. A load simulator  44  connected to a 50 ohm terminator  46  may be connected to the output connector  34  of the power source  18  (step  320 ). The generators  28 ,  30  may be turned on and powered up (step  324 ) which may take 10 minutes, to determine if there are any problems with the power source  18  (step  328 ). Diagnostic instruments within the first and second generators  28 ,  30  or within the match box  32  may be able to determine if the power source  18  is working properly, when connected to the load simulator  44 . 
     If it is determined that the power source  18  is working correctly, then to reconnect the power source, the first and second generators  28 ,  30  may be powered off (step  332 ). The power source  18  may then be disconnected from the load simulator  44  and the power terminator  46  (step  336 ). The power source  18  may then be moved to the plasma process module (step  340 ). The lead  24  may be connected to the output connector  34 . The power source  18  may then be connected to the lower transfer chamber  16  of the plasma process module (step  344 ). The 6 to 7 nut and bolt sets  36  may be used to complete the connection. The bottom cover  38  may be placed on the lower transfer chamber  16  to set the interlock switch  40  so that it is not triggered. The first and second generators  28 ,  30  may the be powered on (step  348 ). 
     The connecting and disconnecting of the power source  18  and the powering up and powering down of the generators may be time consuming and hazardous and may require a high level of expertise to be done correctly. In addition, the connecting and disconnecting of the output connector  34  and the lead  24  may cause the connection between the output connector  34  and the lead  24  to be less reliable. The many steps involved increase the chance of mistakes with high voltage and current devices. 
     In view of the foregoing, it is desirable to provide a simple method and apparatus for testing a power source of a plasma process device. 
     SUMMARY OF THE INVENTION 
     The invention relates, in one embodiment, to a plasma processing apparatus, comprising: a plasma process module; an electrode within the plasma process module; a switch electrically connected to the electrode; a load simulator electrically connected to the switch; a power source electrically connected to the switch, wherein the switch is electrically connected between the power source and the load simulator. 
     The invention relates, in a second embodiment, to a method for testing a generator in a plasma processing device while the generator is running, comprising the steps of: setting the generator to provide a near minimum (which is low or zero) power output, while the generator remains on; through a switch electrically connected to the generator, connecting a load simulator to the generator; increasing the output of the generator; and determining if the generator is providing sufficient power. 
    
    
     These and other features of the present invention will be described in more detail below in the detailed description of the invention and in conjunction with the following figures. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar elements and in which: 
     FIG. 1 is a schematic view of a prior art plasma processing device. 
     FIG. 2 is a schematic view of the prior art plasma processing device as shown in FIG. 1, with a power source which is undergoing testing. 
     FIG. 3 is a flow chart of a power the testing of the power source according to the prior art. 
     FIG. 4 is a schematic view of a preferred embodiment of the invention. 
     FIG. 5 is an enlarged schematic view of the switch of the embodiment illustrated in FIG.  4 . 
     FIG. 6 is a flow chart of the power testing of a power source according to the preferred embodiment of the invention. 
     FIG. 7 is a schematic view of another switch of a preferred embodiment of the invention. 
     FIG. 8 is a schematic view of another embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will now be described in detail with reference to a few preferred embodiments thereof as illustrated in the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without some or all of these specific details. In other instances, well known process steps and/or structures have not been described in detail in order to not unnecessarily obscure the present invention. 
     To facilitate discussion, FIG. 4 depicts a schematic view of a plasma processing device  110  used in a preferred embodiment of the invention, comprising a plasma process unit  112 , a pump manifold  114  supporting the plasma process unit  112 , a lower transfer chamber  116  supporting the pump manifold  114 , and a power source  118  connected to the lower transfer chamber  116 . The plasma process unit  112 , pump manifold  114 , and lower transfer chamber  116  collectively form a plasma process module. The plasma process unit  112 , comprises an upper electrode  120  spaced apart from a lower electrode  122 . A lead  124  extends from the lower electrode  122 , through the pump manifold  114  and the lower transfer chamber  116  to provide an electrical connection between the lower electrode  122  and a first output of a switch  150  mounted within the lower transfer chamber  116 . An input of the switch  150  is electrically connected to the power source  118 . An example of a power source  118  is a One Box™ radio frequency (rf) power source, which comprises a first generator  128 , a second generator  130 , and a match box  132  electrically connected to the first generator  128  and the second generator  130 . In this example, the first generator  128  provides a 2 MHz output, and the second generator  130  provides a 27 MHz output. More generally, the first generator  128  provides an output between 0.1 to 5 MHz, and the second generator  130  provides an output between 10 to 100 MHz. The match box  132  may provide various electrical diagnostics and impedance matching between the first and second generators  128 ,  130  and the plasma created between the upper and lower electrodes  120 ,  122 . An output connector  134  extends from the match box  132 . The switch  150  is electrically connected to the output connector  134 . Nut and bolt sets  136  may provide a mechanical connection to connect the power source  118  to the lower transfer chamber  116 . A bottom cover  138  covers the bottom of the lower transfer chamber  116 . An interlock switch  140  is placed near the cover  138  and is electrically connected to the first generator  128  and the second generator  130 , so that when the cover is removed from the lower transfer chamber  116  the interlock switch powers down the first generator  128  and the second generator  130  to reduce electrical shock hazards. A load simulator  144  is mounted within the lower transfer chamber  116 . The load simulator  144  is electrically connected to a second outlet of the switch  150 . A terminator  146  may be detachably connected to the load simulator  144 . In the preferred embodiment, the terminator  146  is a 25 to 100 Ω terminator. More preferably, the terminator  146  is a 50 Ω terminator. 
     FIG. 5 is a schematic view of the switch  150 . In this preferred embodiment of the invention, the switch  150  is an A to B switch. A movable contact  155  is electrically connected, to the output connector  134 . A first contact  156  is electrically connected to the lead  124 . A second contact  157  is electrically connected to the load simulator  144 . A handle  158  is used to move the movable contact  155  from being in contact with the first contact  156  to being in contact with the second contact  157 , causing the output connector  134  to go from being electrically connected to the lead  124  to being electrically connected to the load simulator  144 . 
     Generally the plasma processing device  10  may be used by placing a substrate on the lower electrode of the plasma process unit. A gas may be flowed into the plasma process unit. The power source  118  provides power to the lower electrode  122 , which may help energize the gas, creating a plasma between the upper and lower electrodes  120 ,  122 . The plasma may be used to process the substrate by etching the substrate or depositing material on the substrate. 
     FIG. 6 is a flow chart of the testing procedure of the power source  118 . In the testing of the power source  118 , a power source problem may be suspected (step  604 ). The output of the power source  118  is lowered, possibly by lowering the output from the first and second generators  128 ,  130 , while the first and second generators  128 ,  130  and the power source  118  remain on (step  608 ). The terminator  146 , preferably a 50 ohm (Ω) terminator is connected to the load simulator  144 , which may take 2 minutes (step  612 ). In the preferred embodiment, a pass through connector allows the connection between the load simulator  144  and the terminator  146  without opening any part of the plasma process module. The handle  158  moves the movable contact  155  of the switch  150 , so that the movable contact  155  moves from the first contact  156  to the second contact  157 , which may take 30 seconds (step  616 ). The switch  150  may be a mechanical switch, an electrical switch, or an electromechanical switch. The handle  158  could be a button that electrically opens a connection between the output connector  134  and the lead  124  and closes a connection between the output connector  134  and the load simulator  144 . The power from the power source  118  may be increased to check for problems with the first and second generators  128 ,  130  and match box  132  (step  620 ). Diagnostic instruments within the first and second generators  128 ,  130  or within the match box  132  may be able to determine if the power source  118  is working properly, when connected to the load simulator  144 . 
     If it is determined that the power source  118  is working correctly, then the power output from the power source  118  may be lowered and the handle  158  is used to move the movable contact  155  of the switch  150 , so that the movable contact  155  moves from the second contact  157  to the first contact  156  (step  624 ). The power terminator  146  is then disconnected from the load simulator  144  (step  628 ). 
     The process for testing the power source  118  is much quicker and easier than the prior art. The use of a switch also may reduce shock hazards from manually disconnecting a power source and from making a mistake during the many extra steps in the prior art. 
     In the preferred embodiment of the invention, the match box takes a 50 ohm input and conditions it to drive a 1 ohm-25j ohm impedance at 27 MHz, and the load simulator takes the 1 ohm-25j ohm impedance at 27 MHz and matches it into a 50 ohm resistor. The match box also takes a 50 ohm input and conditions it to drive a 40 ohm-150j ohm impedance at 2 MHz, and the load simulator takes the 40 ohm-150j ohm impedance at 2 MHz and matches it into a 50 ohm resistor. So the load simulator reverses the match box. 
     FIG. 7 is an alternative embodiment of the switch  150 , where the switch is an A to A and B switch. In this embodiment, the lead  124  is electrically connected to the output connector  134 . A first contact  156  is electrically isolated and a second contact  157  is electrically connected to the output connector. The movable contact  155  is electrically connected to the load simulator  144  and is moved by the handle  158  between the first contact  156  and the second contact  157 . This alternative embodiment may use the same method as shown in FIG.  6 . 
     FIG. 8 illustrates another embodiment, where a load simulator  144  and power terminator  146  are mounted in the housing  200  of the power source  118  instead of within the plasma process module. A switch  150  is also mounted in the housing  200  of the power source  118 , where the switch has an input electrically connected to the match box  132 , a first output electrically connected to the output connector  134  and the lead  124 , and a second output electrically connected to the load simulator  144 . A movable contact  155  of the switch  150  may be moved from a first contact  156 , electrically connected to the lead, to a second contact  157 , electrically connected to the load simulator  144 , to direct the output from the match box  132  from the lower electrode  122  to the load simulator  144 . Since the switch  150  is located on the output side of the match box  132 , the switch  150  is electrically connected between the power source  118  and the lower electrode  122 . 
     More generally the upper electrode  120  and lower electrode  122  form a plasma generation device, in which the upper electrode  120  and lower electrode  122  capacitively excite a plasma. More generally, a plasma generation device may comprise an antenna, which inductively excites a plasma. 
     While this invention has been described in terms of several preferred embodiments, there are alterations, permutations, and equivalents which fall within the scope of this invention. It should also be noted that there are many alternative ways of implementing the methods and apparatuses of the present invention. It is therefore intended that the following appended claims be interpreted as including all such alterations, permutations, and equivalents as fall within the true spirit and scope of the present invention.