Patent Publication Number: US-2013244343-A1

Title: Method for preparing a thin film device and method for preparing a common mode filter using the same

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates to a method for preparing a thin film device and a method for preparing a common mode filter using the same, and more particularly, relates to a method for preparing an insulation layer from a dry polyimide film and a method for preparing a common mode filter using the same. 
     2. Background 
     In a thin film device, an insulation layer such as polyimide film is widely used to electrically separate the conductive pattern of different layers. In the prior art, the polyimide film is generally formed by spin coating technique, and it is generally desired to make the polyimide film uniform in thickness. 
       FIGS. 1 and 2  illustrate a method for preparing a thin film device  10  according to the prior art. Referring to  FIG. 1 , deposition, lithography, electroplating and etching processes are performed to form a first conductive pattern  13  on a substrate  11 , and a first insulation layer  15  is then formed on the first conductive pattern  13  by spin coating process and thermal treating process. 
     Referring to  FIG. 2 , deposition, lithography, electroplating and etching processes are performed to form a second conductive pattern  17  on the first insulation layer  15 , and a second insulation layer  19  is then formed on the second conductive pattern  17  by the spin coating process and thermal treating process. 
     The first insulation layer  15  formed by the spin coating process can electrically separate the first conductive pattern  13  from the second conductive pattern  17 . However, the surface of the first insulation layer  15  formed by the spin coating process is not planar, which may impede alignment of the lithography process for preparing the second conductive pattern  17 , i.e., influencing the position of the subsequently formed second conductive pattern  17 . In addition, the thickness of the first insulation layer  15  between the first conductive pattern  13  and the second conductive pattern  17  is not uniform, which influences the electrical properties of the thin film device  10 . 
     SUMMARY 
     One aspect of the present invention provides a method for preparing a thin film device with an insulation layer formed from a dry polyimide film and a method for preparing a common mode filter using the same. 
     A method for preparing a thin film device according to this aspect of the present invention comprises the steps of forming a first conductive pattern on a substrate; placing a dry polyimide film on the first conductive pattern; applying a force to the dry polyimide film such that the dry polyimide film fills spaces in the first conductive pattern; and forming a second conductive pattern on the dry polyimide film 
     A method for preparing a common mode filter according to another aspect of the present invention comprises the steps of forming a first conductive pattern on a substrate; placing a dry polyimide film on the first conductive pattern; applying a force to the dry polyimide film such that the dry polyimide film fills spaces in the first conductive pattern; and forming second conductive pattern on the dry polyimide film 
     The foregoing has outlined rather broadly the features of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features of the invention will be described hereinafter, and form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures or processes for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The objectives of the present invention will become apparent upon reading the following description and upon reference to the accompanying drawings in which: 
         FIG. 1  and  FIG. 2  illustrate a method for preparing a thin film device according to the prior art; 
         FIG. 3  to  FIG. 8  illustrate a method for preparing a thin film device according to one embodiment of the present invention; 
         FIG. 9  to  FIG. 18  illustrate a method for preparing a common mode filter in accordance with an embodiment of the present invention; and 
         FIG. 19  to  FIG. 27  illustrate a method for preparing a common mode filter in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 3 to 8  illustrate a method for preparing a thin film device  30  according to one embodiment of the present invention. Referring to  FIG. 3 , deposition, lithography, electroplating and etching processes are performed to form a first conductive pattern  33 A- 33 C with spaces  35  on a substrate  31 . Subsequently, a dry polyimide film  37  is placed on the first conductive pattern  33 A- 33 C, as shown in  FIG. 4 . 
     Referring to  FIG. 5 , a force  25  is applied to the dry polyimide film  37  such that the dry polyimide film  37  fills the spaces  35  in the first conductive pattern  33 A- 33 C. Subsequently, a curing process is performed on the dry polyimide film  37  serving as an insulation layer to electrically isolate the first conductive pattern  33 A- 33 C. 
     In one embodiment of the present invention, the force  25  is applied to the dry polyimide film  37  by a roller or by a hydraulic press through an elastomer  23  such as rubber or diaphragm. In one embodiment of the present invention, the force  25  is applied to the dry polyimide film  37  substantially in a vacuum environment. In one embodiment of the present invention, the force  25  is applied to the dry polyimide film  37  substantially at a temperature between 50° C. and 110° C., which is not lower than the glass transition temperature of the dry polyimide film  37 . In one embodiment of the present invention, the curing process is a thermal treating process performed at a temperature between 160° C. and 370° C. 
     Referring to  FIG. 6 , a patterning process is performed on the dry polyimide film  37  to form a hole  39  exposing a portion of the first conductive pattern  33 B. In one embodiment of the present invention, the patterning process includes lithography process. 
     Referring to  FIG. 7 , fabrication processes including deposition, lithography, electroplating and etching processes are performed on the dry polyimide film  37  to form a second conductive pattern  43 A- 43 C with spaces  45  on the dry polyimide film  37 . In addition, the fabrication processes also form a via  41  connecting the second conductive pattern  43 B and the first conductive pattern  33 B, as shown in  FIG. 7 . Subsequently, the fabrication processes shown in  FIG. 4  and  FIG. 5  are performed to form a dry polyimide film  47  serving as an insulation layer to electrically isolate the second conductive pattern  43 A- 43 C of the thin film device  30 , as shown in  FIG. 8 . 
       FIGS. 9 to 18  illustrate a method for preparing a common mode filter  100  in accordance with an embodiment of the present invention. 
     Referring to  FIG. 9 , a first insulation layer  121  such as the polyimide film is formed on a magnetic substrate  111  by spin coating process. 
     Referring to  FIG. 10 , a lower coil leading layer  113  is formed on the first insulation layer  121  by a thin-film metal deposition process, a photolithography process, an electroplating process and an etching process. In one embodiment of the present invention, the thin-film metal deposition process is a sputtering process. 
     Referring to  FIG. 11 , a second insulation layer  122  is formed from a dry polyimide film on the lower coil leading layer  113  by the fabrication process described in  FIG. 4  and  FIG. 5 , i.e., placing a dry polyimide film on the lower coil leading layer  113  and applying a force to the dry polyimide film such that the dry polyimide film covers the lower coil leading layer  113 . Subsequently, a patterning process is performed on the second insulation layer  122  to form a hole  1221  by the fabrication process described in  FIG. 6 , wherein the hole  1221  exposes a portion of the lower coil leading layer  113 . 
     Referring to  FIG. 12 , a first coil main body layer  114  is formed on the second insulation layer  122  by a thin-film metal deposition process, a photolithography process, an electroplating process and an etching process. In one embodiment of the present invention, the thin-film metal deposition process is a sputtering process. In one embodiment of the present invention, the first coil main body layer  114  includes a conductive pattern with spaces  1141 . 
     Referring to  FIG. 13 , a third insulation layer  123  is formed from a dry polyimide film on the first coil main body layer  114  by the fabrication process described in  FIG. 4  and  FIG. 5 , i.e., placing a dry polyimide film on the first coil main body layer  114  and applying a force to the dry polyimide film such that the dry polyimide film fills the spaces  1141  in the conductive pattern of the first coil main body layer  114 . 
     Referring to  FIG. 14 , a second coil main body layer  115  is formed on the third insulation layer  123  by a thin-film metal deposition process, a photolithography process, an electroplating process and an etching process. In one embodiment of the present invention, the thin-film metal deposition process is a sputtering process. In one embodiment of the present invention, the second coil main body layer  115  includes a conductive pattern with spaces  1151 . 
     Referring to  FIG. 15 , a fourth insulation layer  124  is formed from a dry polyimide film on the second coil main body layer  115  by the fabrication process described in  FIG. 4  and  FIG. 5 , i.e., placing a dry polyimide film on the second coil main body layer  115  and applying a force to the dry polyimide film such that the dry polyimide film fills the spaces  1151  in the conductive pattern of the second coil main body layer  115 . Subsequently, a patterning process is performed on the fourth insulation layer  124  to form a hole  1241  by the fabrication process described in  FIG. 6 , wherein the hole  1241  exposes a portion of the second coil main body layer  115 . 
     Referring to  FIG. 16 , an upper coil leading layer  116  is formed by a thin-film metal deposition process, a photolithography process, an electroplating process and an etching process. In one embodiment of the present invention, the thin-film metal deposition process is a sputtering process. 
     Referring to  FIG. 17 , a fifth insulation layer  125  is formed from a dry polyimide film on the upper coil leading layer  116  by the fabrication process described in  FIG. 4  and  FIG. 5 , i.e., placing a dry polyimide film on the upper coil leading layer  116  and applying a force to the dry polyimide film such that the dry polyimide film covers the upper coil leading layer  116 . 
     Referring to  FIG. 18 , a magnetic material layer  117  is formed on the fifth insulation layer  125  by a screen printing process to complete the common mode filter  100 . 
       FIGS. 19 to 27  illustrate a method for preparing a common mode filter  200  in accordance with an embodiment of the present invention. 
     Referring to  FIG. 19 , a magnetic material layer  212  is formed on a non-magnetic dielectric substrate  211 . In one embodiment of the present invention, the non-magnetic dielectric substrate  211  may includes Al 2 O 3 , AlN, glass, or quartz. In one embodiment of the present invention, the magnetic material layer  212  has high permeability and may includes ferrites such as NiZn ferrite material or MnZn ferrite material. 
     Referring to  FIG. 20 , a first insulation layer  221  such as the polyimide film is formed on the magnetic material layer  212  by spin coating process. 
     Referring to  FIG. 21 , a first coil main body layer  213  is formed on the first insulation layer  221  by a thin-film metal deposition process, a photolithography process, an electroplating process and an etching process. In one embodiment of the present invention, the thin-film metal deposition process is a sputtering process. In one embodiment of the present invention, the first coil main body layer  213  includes a conductive pattern with spaces  2131 . 
     Referring to  FIG. 22 , a second insulation layer  222  is formed from a dry polyimide film on the first coil main body layer  213  by the fabrication process described in  FIG. 4  and  FIG. 5 , i.e., placing a dry polyimide film on the first coil main body layer  213  and applying a force to the dry polyimide film such that the dry polyimide film fills the spaces  2121  in the conductive pattern of the first coil main body layer  213 . Subsequently, a patterning process is performed on the second insulation layer  222  to form a hole  2221  by the fabrication process described in  FIG. 6 , wherein the hole  2221  exposes a portion of the first coil main body layer  213 . 
     Referring to  FIG. 23 , a coil leading layer  214  is formed in the hole  2221  by a thin-film metal deposition process, a photolithography process, an electroplating process and an etching process. In one embodiment of the present invention, the thin-film metal deposition process is a sputtering process, and the coil leading layer  214  in the hole  2221  contacts the first coil main body layer  213 . 
     Referring to  FIG. 24 , a third insulation layer  223  is formed from a dry polyimide film on the coil leading layer  214  by the fabrication process described in  FIG. 4  and  FIG. 5 , i.e., placing a dry polyimide film on the coil leading layer  214  and applying a force to the dry polyimide, thereby isolating the coil leading layer  214 . 
     Referring to  FIG. 25 , a second coil main body layer  215  is formed on the third insulation layer  223  by a thin-film metal deposition process, a photolithography process, an electroplating process and an etching process. In one embodiment of the present invention, the thin-film metal deposition process is a sputtering process, and the second coil main body layer  215  contacts the coil leading layer  214  in the third insulation layer  223 . In one embodiment of the present invention, the second coil main body layer  215  includes a conductive pattern with spaces  2151 . 
     Referring to  FIG. 26 , a fourth insulation layer  224  is formed from a dry polyimide film on the second coil main body layer  215  by the fabrication process described in  FIG. 4  and  FIG. 5 , i.e., placing a dry polyimide film on the second coil main body layer  215  and applying a force to the dry polyimide film such that the dry polyimide film fills the spaces  2151  in the conductive pattern of the second coil main body layer  215 . 
     Referring to  FIG. 27 , a magnetic material layer  217  is formed on the fourth insulation layer  224  by a screen printing process to complete the common mode filter  200 . 
     Although the present invention and its objectives have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. For example, many of the processes discussed above can be implemented in different methodologies and replaced by other processes, or a combination thereof. 
     Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed, that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.