Method of manufacturing tape wiring substrate
A method of manufacturing a tape wiring substrate, by which the production cost can be reduced by a simplified manufacturing process. A fine wiring pattern having fine pitches can be formed. The method of manufacturing a tape wiring substrate includes preparing a base film, forming a metal layer on the base film, and processing the metal layer into a wiring pattern using a laser. In addition, the metal layer is partially removed using the laser, and a wiring pattern is formed by a subsequent wet etching.
This application claims priority from Korean Patent Application No. 10-2004-0017943 filed on Mar. 17, 2004 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
BACKGROUND OF THE INVENTION1. Field of the Invention
The present invention relates to a method of manufacturing a tape wiring substrate, and more particularly, to a method of manufacturing a tape wiring substrate, by which a wiring pattern is formed using a laser.
2. Description of the Related Art
According to a recent trend for thin, compact, highly integrated, high speed and multi-pin semiconductor devices, tape wiring substrates have been increasingly employed in techniques of mounting semiconductor chips. The tape wiring substrates are configured so that a wiring pattern layer is formed on a base film made of an insulating material such as polyimide resin. It is possible to apply a tape automated bonding (TAB) technique for bonding leads connected to the wiring pattern layer to bumps previously formed on a semiconductor chip at one time in the tape wiring substrates. The tape wiring substrates are referred to as a TAB tape owing to such a characteristic.
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As described above, in the process of manufacturing the conventional tape wiring substrate, after manufacturing the base film 110, the copper foil 120 is formed thereon and processed into the wiring pattern 125 using photolithographic etching. The photolithographic etching includes a variety of steps, including a PR coating step, an exposing step, a PR developing step, a step of etching the copper foil, and so on.
So many processing steps give rise to an increase in the volume of a production line, and volumes of materials that are consumed regularly, for example, PR, PR developer, copper foil etchant or the like, become increased, thereby inevitably increasing the production cost.
Further, since the light source 132 having a relatively large wavelength of several hundreds of micrometers is used in the conventional photolithographic etching, it is quite difficult to form a micro scale wiring pattern having fine pitches on the copper foil 120.
SUMMARY OF THE INVENTIONTo solve the above-described problems, embodiments of the present invention provide a method of manufacturing a tape wiring substrate, by which production cost can be reduced by a simplified manufacturing process and a fine wiring pattern having fine pitches can be formed.
The above stated embodiments as well as other embodiments of the present invention will become readily apparent to one skilled in the art from the following description.
In accordance with an embodiment of the present invention, there is provided a method of manufacturing a tape wiring substrate comprising preparing a base film, forming a metal layer on the base film, and processing the metal layer into a wiring pattern using laser.
In accordance with another embodiemnt of the present invention, there is provided a method of manufacturing a tape wiring substrate comprising preparing a base film, forming a metal layer on the base film, partially removing an area other than a wiring pattern in the metal layer using laser, and etching the remaining area other than the wiring pattern and forming the wiring pattern.
BRIEF DESCRIPTION OF THE DRAWINGSThe above and other features and advantages of the present invention will become more apparent by describing in detail preferred embodiments thereof with reference to the attached drawings:
Advantages and features of the present invention and methods of accomplishing the same may be understood more readily by reference to the following detailed description of preferred embodiments and the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the concept of the invention to those skilled in the art, and the present invention will only be defined by the appended claims. Like reference numerals refer to like elements throughout the specification.
A flexible printed circuit board (FPC), such as a tape carrier package (TCP) or a chip on film (COF), in which a wiring pattern is formed on a base film, can be used as a tape wiring substrate in an embodiment of the present invention. The tape wiring substrate used in an embodiment of the present invention has a structure in which wiring patterns and inner leads connected thereto are formed on a thin film made of an insulating material such as polyimide resin. The tape wiring substrate used in the embodiment of present invention includes a wiring substrate applying a tape automated bonding (TAB) technique in which bumps previously formed on a semiconductor chip and the inner leads of the tape wiring substrate are bonded at one time. The above-stated tape wiring substrates are provided for illustration only.
Hereinafter, an embodiment of the present invention is explained with reference to
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A method of forming a copper foil as an exemplary layer of the metal layer 320 on the base film 310 includes casting, laminating, electroplating, and so on. In the casting, the base film 310 being in a liquid form is cast on a rolled copper foil, followed by curing. In the laminating, a rolled copper foil is placed on the base film 310 and then thermally compressed. In the electroplating, a seed layer (not shown) is deposited on the base film 310, and immersed in an electrolyte having copper melted therein, followed by applying electricity thereto, thereby forming a copper foil. Here, the seed layer can be formed on the base film 310 by sputtering. The seed layer is preferably made of a material selected from the group consisting of Cr, Ti, Ni, and a combination thereof.
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Preferably, plating of Sn, Au, Ni or solder is performed on a surface of the wiring pattern 325 for the purpose of improving electric characteristics of the wiring pattern 325. Such a method in which plating is performed after coating the solder resist 340 on the wiring pattern 325 is referred to as a post-plating method. Of course, a pre-plating method in which the solder resist 340 is coated after plating on the wiring pattern 325 can be adopted in another embodiment of the present invention.
Hereinafter, a method of forming the wiring substrate using the laser will be described in detail with reference to
Referring to
Here, a laser having a wavelength of 550 nm or less can be generated from the light source 410 so as to embody the wiring pattern 325 having fine pitches. Thus, a source gas of any one selected from the group consisting of ArF, KrF, XeC1, F2, Nd-YAG (neodymium-yttrium aluminum garnet), and CO2 can be used as the light source 410. Further, a laser such as a laser diode can be used.
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Further, as the wiring pattern becomes smaller and smaller, the aperture 430 can be disposed in a path of the laser to increase the resolution of laser radiation pattern. The aperture 430 can be shaped of a dipole, quadrupole, annulus, and so on.
Thus, the laser radiation generated in the light source 410 may be converted into a substantially parallel beam by the fly's eye lens 420 and partially confined by the aperture 430.
The laser radiation passing through the aperture 430 may be irradiated onto the mask 450 through the condenser lens 440. The condenser lens 440 concentrates the laser radiation generated in the light source 410 in a desirable direction. The condenser lens 440 is not directly concerned in forming an image, but increases the uniformity of the laser when the laser is irradiated onto the mask 450.
The laser radiation having reached the mask 450 is diffracted and passes through the projection lens 460 to expose the metal layer 320 formed on the base film 310. Generally, the projection lens 460 transmits laser radiation from the mask 450 to micro-project the image of the mask pattern onto the metal layer 320. A stage 470 supports the base film 310 where the metal layer 320 is formed.
Examples of useful methods of irradiating the laser radiation emitted from the light source 410 onto the metal layer 320 formed on the base film 310 include a step-and-repeat method in which the metal layer 320 is irradiated using a stepper while the mask 450 and the stage 470 stop moving, and a step-and-scan method in which exposure is performed using a scanner while moving the mask 450 and the stage 470 in opposite directions at different moving speeds.
To accurately etch only the metal layer 320 except the wiring pattern 325, which is required to process the metal layer 320 as the wiring pattern 325, and to minimize the base film 310 located under the metal layer 320 from being damaged due to thermal energy generated from the laser, a pulse type layer is preferably used.
A preferred method of emitting laser radiation will now be described by way of example of an ArF excimer laser (wavelength of 193 nm) having a pulse energy of 200 mJ. Here, a method of emitting the laser radiation can vary according to equipment used and processing conditions. It has been shown and described that copper may be used as the metal layer 320 and polyimide may be used as the base film 310, but embodiments of the present invention are not limited to the particular embodiment described below.
In the ArF excimer laser according to an embodiment of the present invention, assuming that an etching rate with respect to copper is about 160 mJ/μm and an etching rate with respect to polyimide is about 16 mJ/μm, a process of the etching metal layer 320 having a thickness of 8 μm into the wiring pattern 325 will now be described.
To etch the metal layer 320 having the thickness of 8 μm, energy of 1280 mJ (=160 mJ/μm×8 μm) is required. Since pulse energy of the ArF excimer laser is 200 mJ, 6.4 pulses (=1280 mJ/200 mJ) is required to etch the metal layer 320 having the thickness of 8 μm. Thus, if the ArF excimer laser of 7 pulse is irradiated onto the metal layer 320, the metal layer 320 other than a portion where the wiring pattern 325 is formed is completely etched, and energy of 120 mJ (=200 μm×0.6) corresponding to 0.6 pulse is irradiated onto the base film 310. Thus, the base film 310 is further etched to a thickness of about 7.5 μm (=120 mJ/16 mJ/μm), which is, however, a negligible etching amount, that is, physical properties of the base film 310 are not adversely affected at all.
When the metal layer 320 is etched using the pulse type laser, the pulse energy of the laser can adjustably change the frequency (usually in a range of 50-300 Hz) and print “energy” (usually in a range of 5-100 W). Thus, in case pulse energy of the laser is properly adjusted, appropriately adjusting the pulse energy can reduce an etching amount of the base film 310 located under the metal layer 320, e.g., polyimide, to a minimum, but not limited to values particularly defined in the above-described embodiment. Rather, the metal layer 320 is etched while minimizing the etching amount of the base film 310 by adjusting the frequency and print energy of the laser according to a material and a thickness of the metal layer 320.
In addition, during forming of the wiring pattern 325 using the laser, the thermal energy may be transferred to not only a contact portion between the metal layer 320 and the laser 330 but also the metal layer 320 or the base film 310 adjacent to the contact portion. The thermal energy may etch the metal layer 320 around the contact portion or may deform the base film 310 under the contact portion. Thus, a refrigerant is preferably supplied to a portion where the metal layer 320 and the laser 330 contact while forming the wiring pattern 325 using laser, thereby preventing the thermal energy from being transferred to the vicinity of the contact portion. As the refrigerant, methylether, ethyl chloride, methyl formate, isobutane, dichloroethylene, methylene chloride, ethylether, ammonia, carbon dioxide, sulfur dioxide, methyl chloride and CFC-based refrigerant (Freon), etc. can be used.
Another embodiment of the present invention will now be described with reference to
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Preferably, in the case of using a copper foil as the metal layer 320, wet etching can be performed using an aqueous solution containing FeCl3, FeCl, and HCl as an etchant. Alternatively, the wet etching can be performed using an aqueous solution containing CuCl2, CuCl, and HCl as an etchant.
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Another preferred method involving laser etching will now be described by way of example of an ArF excimer laser (wavelength of 193 nm) having a pulse energy of 200 mJ. Here, the method using the laser can vary according to equipment used and processing conditions. It has been shown and described that copper is used as the metal layer 320 and polyimide is used as the base film 310, but the present invention is not limited to the particular embodiments described above or below.
In the ArF excimer laser according to another embodiment of the present invention, assuming that an etching rate with respect to copper is about 160 mJ/μm and an etching rate with respect to polyimide is about 16 mJ/μm, a process of etching the metal layer 320 having a thickness of 8 μm into the wiring pattern 625 will now be described.
To etch the metal layer 320 having the thickness of 8 μm, energy of 1280 mJ (=160 mJ/μm×8 μm) is required. Since pulse energy of the ArF excimer laser is 200 mJ, 6.4 pulses (=1280 mJ/200 mJ) is required to etch the metal layer 320 having the thickness of 8 μm. Thus, if the ArF excimer laser of 6 pulses is irradiated onto the metal layer 320, the metal layer 320 other than a portion where the wiring pattern 625 is formed is etched. Thus, the area 622 other than the wiring pattern 625 remains to a thickness of about 0.5 μm, which can be removed by either wet etching or dry etching using plasma.
As described above, the wiring pattern 625 can be formed using the laser 330 without causing damages to the base film 310 by simultaneously performing primarily etching using laser and secondary etching (either wet etching or dry etching).
As described above, according to the illustrative embodiments of the invention, a metal layer can be directly processed into a wiring pattern without using photoresist, unlike in the prior art. Thus, the number of processing steps is reduced and thus the production cost of the tape wiring substrate can be reduced, compared to the prior art.
In concluding the detailed description, those skilled in the art will appreciate that many variations and modifications can be made to the preferred embodiments without substantially departing from the principles of the present invention. Therefore, the disclosed preferred embodiments of the invention are used in a generic and descriptive sense only and not for purposes of limitation.
As described above, according to the method of manufacturing the tape wiring substrate of the present invention, the production cost can be reduced through a simplified manufacturing process and a fine wiring pattern having fine pitches can be formed.
Claims
1. A method of manufacturing a tape wiring substrate comprising:
- preparing a base film;
- forming a metal layer on the base film; and
- etching the metal layer into a wiring pattern using a laser that produces laser radiation that is incident on the metal layer.
2. The method of claim 1, wherein the laser generates from a source gas of any one selected from the group consisting of ArF, KrF, XeC1, F2, Nd-YAG (neodymium-yttrium aluminum garnet), and CO2.
3. The method of claim 1, wherein the laser is a pulse type.
4. The method of claim 1, wherein the laser radiation passes through a beam homogenizer before being incident on the metal layer.
5. The method of claim 1, wherein a refrigerant is provided for the metal layer while etching the wiring pattern.
6. The method of claim 5, wherein the refrigerant is any one selected from the group consisting of methylether, ethyl chloride, methyl formate, isobutane, dichloroethylene, methylene chloride, ethylether, ammonia, carbon dioxide, sulfur dioxide, methyl chloride, and CFC-based refrigerant (Freon).
7. The method of claim 1, wherein the metal layer includes copper.
8. A method of manufacturing a tape wiring substrate comprising:
- preparing a base film;
- forming a metal layer on the base film;
- at least partially removing an area other than a wiring pattern in the metal layer using a laser that produces radiation that is incident on the metal layer; and
- etching the remaining area other than the wiring pattern to form the wiring pattern.
9. The method of claim 8, wherein the laser generates from a source gas of any one selected from the group consisting of ArF, KrF, XeC1, F2, Nd-YAG (neodymium-yttrium aluminum garnet), and CO2.
10. The method of claim 8, wherein the laser is a pulse type.
11. The method of claim 8, wherein the laser radiation passes through a beam homogenizer before being incident on the metal layer.
12. The method of claim 8, wherein a refrigerant is provided for the metal layer while at least partially removing the area.
13. The method of claim 12, wherein the refrigerant is any one selected from the group consisting of methylether, ethyl chloride, methyl formate, isobutane, dichloroethylene, methylene chloride, ethylether, ammonia, carbon dioxide, sulfur dioxide, methyl chloride, and CFC-based refrigerant (Freon).
14. The method of claim 8, wherein the etching is wet etching.
15. The method of claim 14, wherein the wet etching exposes the base film disposed under the area other than the wiring pattern.
16. The method of claim 8, wherein the metal layer includes copper.
17. The method of claim 15, wherein the wet etching is performed using an aqueous solution containing FeCl3, FeCl, and HCl as an etchant.
18. The method of claim 15, wherein the wet etching is performed using an aqueous solution containing CuCl2, CuCl, and HCl as an etchant.
19. The method of claim 8, wherein the forming the metal layer is performed by laminating.
20. The method of claim 8, wherein the forming the metal layer is performed by electroplating.
21. The method of claim 8, prior to the forming the metal layer, comprising forming a seed layer on the base film by sputtering.
22. The method of claim 21, wherein the seed layer is made of a material selected from the group consisting of Cr, Ti, Ni, and a combination thereof.
Type: Application
Filed: Mar 8, 2005
Publication Date: Sep 22, 2005
Inventors: Chung-Sun Lee (Gyeonggi-do), Sa-Yoon Kang (Seoul), Yong-Hwan Kwon (Gyeonggi-do), Kyoung-Sei Choi (Chungcheongnam-do)
Application Number: 11/075,639