JP4370065B2 - Winding type dry etching method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a winding type dry etching method and apparatus used for forming a via hole in a built-up process in high-density packaging technology.
[0002]
[Prior art]
With the rise of the Internet and other IT industries, electronic communication devices are rapidly becoming more sophisticated and multifunctional. In addition, the demand for small size, light weight, and thinning has become extremely large. Improvements in the performance of electronic devices are supported by the progress of higher integration and systemization of LSIs, but LSIs and electronic component groups alone cannot demonstrate their performance. In order to make an actual device, a printed wiring board (PWB) for connection and a high-density mounting technique are required.
[0003]
Recently, the specific gravity of multilayer printed wiring boards has increased, and among them, multilayer printed wiring boards based on a build-up process have been developed as a business. The build-up process is a process in which a resin layer is formed on a core substrate and an insulating layer and a conductor layer are stacked one by one, such as drilling via holes, connecting by plating, and forming a pattern. Currently, laser and photolithographic methods are mainly used to form via holes in the build-up process.
[0004]
FIG. 12 of the accompanying drawings shows an example of the process flow of the resin-coated copper foil process in the conventional build-up process. As shown to (A), a multilayer board is made into a core base material, and the surface is roughened by the etching etc. for the purpose of adhesiveness improvement. Next, as shown in (B), a resin-coated copper foil is hot-pressed or laminated on a core base material whose surface has been roughened and laminated and adhered. Next, as shown in (C), the laminated copper foil with resin is patterned by photoetching or the like to form a laser conformal mask. Then, as shown in (D), drilling with a laser is performed. After the drilling with a laser, in most cases, the resin surface (smear) remains on the copper surface of the lower layer, and therefore desmear treatment is performed. Next, as shown in (E), a copper layer is formed by electroless plating or electrolytic plating. After that, the second and subsequent layers are processed by patterning the copper foil again by photo-etching, repeating the surface roughening, laminating and bonding the resin-coated copper foil, and the first step.
[0005]
[Problems to be solved by the invention]
When forming a via hole using a laser method in a build-up process, it is necessary to perform alignment accurately, and a complicated and precise operation is required. In addition, as shown in FIG. 12C, a via hole is formed in the copper wiring layer by the laser beam. In this case, the laser beam irradiation is controlled because the hole penetrates when the laser beam is irradiated too much. Therefore, the resin remains (smear). For this reason, desmear treatment is required to remove the residual resin. That is, in the laser method, the degree of freedom in selecting the material to be processed is wide, but the productivity is limited by alignment and step feed. In addition, after the laser treatment, a desmear treatment process is required to remove the residual resin. In addition, the laser equipment used in this main process is cost-effective to maintain the life of the oscillation tube and its performance. Cost increases.
[0006]
Therefore, the present invention solves the above-mentioned problems associated with conventional methods such as the laser processing method that has been used in the formation of via holes in the build-up process of high-density mounting technology, and can deal with various patterns without the need for desmear processing. An object of the present invention is to provide a winding type dry etching method and apparatus capable of reducing the cost of the etching process.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, a film-like processed material is unwound in a vacuum chamber, a winding chamber, an etching chamber, and an intermediate chamber between these chambers. Each of the chambers is provided with an evacuation system for maintaining these chambers at a required pressure difference, and the main rollers are exposed so that a part of the periphery of the main roller on which the film-like processed material is traveling is exposed to the processing chambers Is positioned in the intermediate chamber, the main roller is used as the cathode electrode, the anode electrode is provided in the etching chamber so as to face the main roller, and an etching gas is supplied from the anode electrode side to the etching processing chamber to continuously process the film-like processed material. A winding type dry etching apparatus is provided which is configured to perform plasma etching.
[0008]
In the apparatus of the first invention of the present invention, the anode electrode facing the main roller can be configured as a shower plate that supplies an etching gas to the etching chamber and is applied with a high-frequency potential.
[0009]
Further, according to the second aspect of the present invention, that using the apparatus according to the first aspect of the invention, plasma etching with resin filmy treated coming travels peripheral surface of the main roller by reactivity ion etching discharge A winding type dry etching method is provided.
[0010]
In this method, a high frequency potential can be applied to the anode electrode facing the main roller.
[0011]
In this method, nitrogen gas can be added to the etching gas supplied to the etching chamber.
[0012]
According to the present invention configured as described above, the desmear process that is inevitably associated with the conventional laser processing becomes unnecessary, and can be collectively formed in a large area regardless of the size and size of the via hole compared to the laser method, It can be sufficiently applied to miniaturization of hole diameter and pitch dimension.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 shows an embodiment of an apparatus implementing the present invention. In FIG. 1, reference numeral 1 denotes a vacuum chamber. The vacuum chamber 1 feeds a film-like processed material by partition walls 2 and 3, a winding chamber 1a, an etching processing chamber 1b, and an intermediate chamber between these two chambers. It is partitioned into 1c. The film-like processed material is delivered, the winding chamber 1a is connected to the evacuation system 4a, the etching chamber 1b is connected to the evacuation system 4b, and the intermediate chamber 1c is connected to the evacuation system 4c. In order to prevent this, a desired pressure difference can be secured between the chambers.
[0014]
In FIG. 1, reference numeral 5 denotes a main roller functioning as a cathode electrode, which is centered in the middle of the partition walls 2 and 3, that is, the intermediate chamber 1c. The lower peripheral portion of the main roller 5 is an etching processing chamber 1b. To protrude. Arc-shaped cover members 6, 7 are disposed adjacent to the region extending downward from the side of the peripheral portion of the main roller 5, and the arc-shaped cover member is adjacent to the upper region of the peripheral portion of the main roller 5. 8 is arranged. These arc-shaped cover members 6, 7, and 8 act so as to prevent abnormal discharge.
[0015]
The delivery shaft 9, the take-up shaft 10, and the guide rollers 11, 12, 13, 14 are positioned in the take-up chamber 1 a of the film-like processed product, and the feed shaft 9 or the take-up shaft 10 is illustrated. The film-like processed material 15 is continuously driven on the peripheral surface of the main roller 5 from the feed shaft 9 through the guide rollers 11 and 12 through a driving device that is not connected, and a required etching process is performed. The film-like processed product 15 that has been subjected to a required etching process on the take-up shaft 10 via the guide rollers 13 and 14 is wound up. In this case, although not shown, the main roller 5, the feed shaft 9, the take-up shaft 10, and the guide rollers 11, 12, 13, and 14 are all supported by the support members (not shown) at both ends. The roller assembly is configured such that it can be inserted into and removed from the vacuum chamber 1 from the side of the vacuum chamber 1 along the axial direction of the roller, that is, the direction perpendicular to the paper surface of FIG.
[0016]
Further, a shower plate 16 that functions as an anode electrode is disposed in the etching processing chamber 1 b so as to face the exposed lower peripheral portion of the main roller 5. The shower plate 16 extends along the axial direction of the main roller 5. A desired etching gas is supplied to the etching gas supply source (not shown) via the gas conduit 17 so as to eject the gas toward the exposed lower peripheral portion of the main roller 5. The shower plate 16 is connected to a high frequency power source 18 so that a high frequency potential can be applied. The main roller 5 is connected to a low frequency power source 19 so that low frequency power is applied and RIE discharge is generated.
[0017]
The example which processed the polyimide (PI) film using the illustrated apparatus comprised in this way is demonstrated below.
The maximum width on which the equipment can be attached is 200 mm, the winding speed is 0.1 to 60 m / min, and the temperature of the central main roller 5 can be controlled in the range of -20 to 40 ° C. by the medium. Oxygen (O ₂ ), carbon tetrafluoride (CF ₄ ), and nitrogen (N ₂ ) gas were used as the etching gas and introduced from the shower plate 16 installed at the lower part of the main roller 5. The PI films were Kapton 100H (manufactured by Toray Du-Pont) and Upilex S (manufactured by Ube Industries), each having a thickness of 25 μm.
[0018]
FIG. 2 shows a method for attaching the PI film. Each PI film 20 is masked with a PI tape 21 for measuring a step as shown in FIG. The PI film 20 thus cut is fixed to the window portion opened in the SUS base film 22 having a width of 200 mm and a thickness of 20 μm shown in (B), that is, an opening 23 with PI tape 24 as shown in (C). did. The etching rate was determined by measuring the step with a stylus type surface shape measuring device Dektak 3030.
[0019]
Etching was performed in two ways: RIE discharge in which a low frequency of 400 kHz is applied to the cathode electrode, that is, the main roller 5 side, and a high frequency of 400 kHz and 13.56 MHz to both the cathode side and the anode side, respectively. . The discharge area on the cathode side is about 1000 cm ² .
[0020]
In the case of RIE discharge FIGS. 3 and 4 show changes in the dynamic etching rate with respect to the CF ₄ concentration and the etching pressure for the PI films of Kapton H and Upilex S. FIG. The dynamic etching rate shows a similar tendency for both Kapton H and Upilex S depending on pressure and CF ₄ concentration. As the etching pressure increases, the dynamic etching rate increases and has a peak in the vicinity of 35-40 Pa when CF _{4 is} 50%. Further, both substrates showed the same tendency with respect to the CF ₄ concentration, and the dynamic etching rate increased with the concentration, and the maximum was obtained at 50%. The maximum dynamic etching rates of Kapton H and Upilex S are 1.4 μm · m / min and 1 μm · m / min, respectively, and the static etching rate corresponds to 2.8 μm / min and 2 μm / min.
[0021]
FIG. 5 shows the chemical structure of Upilex S and Kapton H, and FIG. 6 shows the relationship between the chemical structure of PI and Tg (glass transition temperature). Upilex S is a material that does not have an ether bond compared to Kapton H, has a more rigid chemical structure, and has high heat resistance. This stable chemical structure is considered to have an influence on the etching rate, and is generally regarded as a material that is difficult to be scraped. In addition, many reports have been made on plasma etching of polyimide by a mixed gas of O ₂ and CF _{4 in} a stationary state of the substrate. In any report, the amount of CF ₄ is changed, and CF ₄ is in the vicinity of 20%, 40 The maximum etching rate is obtained in the vicinity of%. Most of these have an etching rate of about 1 μm / min, but as a maximum value, 2.7 μm / min is achieved by applying low frequency power of 30% CF ₄ , pressure 106 Pa and 600 kHz to the Kapton substrate. . The experimental results of the present invention are equivalent to this.
[0022]
In the case of dual frequency excitation discharge Next, the experimental results of generating higher density plasma will be described.
FIG. 7 shows the relationship between the low frequency power applied to the main roller 5 and the dynamic etching rate at an etching pressure of 40 Pa and a CF ₄ concentration of 50%. The dynamic etching rate of each PI increased with increasing power, and about 3 μm · m / min for Kapton and about 2 μm · m / min for Upilex were obtained. The static etching rates are 6 μm / min and 4 μm / min, respectively.
[0023]
FIG. 8 shows changes in the dynamic etching rate when high frequency power is applied to the shower plate 16 in addition to the RIE discharge at the main roller 5.
When the high frequency power applied to the shower plate 16 is increased from 0 (the potential of the shower plate 16 is the ground potential) to 900 W, the etching rate is about 2.4 to 2.5 times higher for both Kapton H and Upilex S than the ground value. Was found to be effective. An even higher etching rate can be expected with a power input of 900 W or more.
[0024]
When nitrogen gas is added to the etching gas As for the influence of nitrogen gas on the etching rate of PI, experiments using O ₂ + CF ₄ + N ₂ gas or O ₂ + NF ₃ gas system have been reported, and reaction products by etching It is said that the etching rate is increased because CO ₂ or COF ₂ reacts with nitrogen radicals to generate oxygen or fluorine as etching active species again. FIG. 9 shows the result of measuring the dynamic etching rate by adding N ₂ gas to the O ₂ + CF ₄ gas system. The dynamic etching rate increased with an increase in the amount of N ₂ gas introduced, and was about 1.5 times at 100 sccm. These results are considered to be the effect of the above-mentioned nitrogen radical and the effect of increasing the self-bias due to the increase of plasma impedance.
[0025]
As exemplified above, when a PI film is continuously wound in a roll-up manner using a mixed gas of O ₂ + CF ₄ , the dynamic etching rate is 3 μm in RIE discharge in which low frequency power is applied to the main roller 5.・ According to the fact that m / min is obtained, the etching rate is increased by applying high-frequency power to the shower plate 16 in addition to the RIE discharge at the main roller 5, and is also increased by adding nitrogen gas. It was. Therefore, a desired dynamic etch rate can be achieved by optimally combining these operating conditions.
[0026]
By the way, in the above example, the case of the polyimide film has been described as the object to be treated. However, the same tendency is naturally recognized for other resin films, and the application to the shower plate 16 in the case of the epoxy resin is shown in FIGS. The relationship between electric power and dynamic etching rate and the relationship between nitrogen addition amount and dynamic etching rate are shown.
[0027]
【The invention's effect】
As described above, in the winding type dry etching apparatus according to the present invention, the film-like processed material is sent out in the vacuum chamber, the winding chamber, the etching processing chamber, and the intermediate chamber between these two chambers. Each chamber is provided with an evacuation system for maintaining these chambers at a required pressure difference, and the main rollers are arranged so that a part of the periphery of the main roller on which the film-like processed material travels is exposed to the processing chambers. Positioned in the intermediate chamber, the main roller is the cathode electrode, the anode electrode is provided in the etching chamber facing the main roller, the etching gas is supplied from the anode electrode side to the etching chamber, and the film-like processed material is continuously plasma Since it is configured to perform etching, the running cost can be reduced compared to conventional laser processing equipment. The etching speed can be increased and the cost of the etching process can be reduced. Therefore, when applied to the formation of via holes in the build-up process of high-density mounting technology, the above-mentioned problems associated with conventional methods such as laser processing are eliminated. As a result, the desmear process is not required, and various patterns can be accommodated, and the via hole can be formed in a large area regardless of the shape and size of the via hole.
[0028]
Further, in the winding dry etching method according to the present invention, the resin traveling on the peripheral surface of the main roller by reactive ion etching discharge by applying low frequency power to the main roller using the apparatus of the present invention. Since the film-like processed product is plasma-etched, alignment work and desmear are compared to conventional methods such as the laser processing method used for via-hole formation in the build-up process of high-density mounting technology. No processing is required, the process can be simplified, and various patterns can be handled, and the cost of the etching process can be reduced.
[0029]
In the method of the present invention, when a high-frequency potential is applied to the anode electrode facing the main roller, a higher etching rate can be obtained and productivity can be improved.
[0030]
Furthermore, in the method of the present invention, when nitrogen gas is added to the etching gas supplied to the etching chamber, the dynamic etching rate can be further increased.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating one embodiment of an apparatus embodying the present invention.
FIG. 2 is a schematic diagram showing a method for attaching a polyimide film to be etched.
FIG. 3 is a graph showing changes in dynamic etching rate with respect to CF ₄ concentration and etching pressure for each PI film of Kapton H.
FIG. 4 is a graph showing changes in dynamic etching rate with respect to CF ₄ concentration and etching pressure for each PI film of Upilex S.
FIG. 5 is a diagram showing the chemical structure of Upilex S and Kapton H. FIG. 6 is a table showing the relationship between the chemical structure of PI and Tg (glass transition temperature).
FIG. 7 is a graph showing the relationship between the low frequency power applied to the main roller and the dynamic etching rate in the case of PI.
FIG. 8 is a graph showing a change in dynamic etching rate when high frequency power is applied to a shower plate in the case of PI.
FIG. 9 is a graph showing the relationship between the addition amount of N ₂ gas and the dynamic etching rate in the case of PI.
FIG. 10 is a graph showing the relationship between the applied power to the shower plate and the dynamic etching rate in the case of epoxy resin.
FIG. 11 is a graph showing the relationship between nitrogen addition amount and dynamic etching rate in the case of epoxy resin.
FIG. 12 is a flow diagram showing steps of a resin-coated copper foil process in a conventional build-up process.
[Explanation of symbols]
1: Vacuum chamber 1a: Delivery of processed film, take-up chamber 1b: Etching chamber 1c: Intermediate chamber 2, 3: Partition walls 4a, 4b, 4c: Vacuum exhaust system 5: Main rollers 6, 7, 8 : Arc-shaped cover member 9: Delivery shaft 10: Winding shafts 11, 12, 13, 14: Guide roller 15: Film-like processed material 16: Shower plate 17: Gas conduit 18: High frequency power source 19: Low frequency power source 20 : PI film 21: PI tape 22: SUS base film 23: Opening 24: PI tape

Claims (5)

  A vacuum exhaust system that unwinds a film-like processed product with resin, partitions the vacuum chamber into a winding chamber, an etching chamber, and an intermediate chamber between the two chambers, and maintains these chambers at a required pressure difference. Is placed in each chamber, and the main roller is positioned in the intermediate chamber so that a part of the periphery of the main roller where the film-like processed material travels is exposed to the processing chamber. A winding type characterized in that an anode electrode is provided in the etching chamber, and an etching gas is supplied from the anode electrode side to the etching processing chamber to continuously plasma-treat the film-like processed product with resin. Dry etching equipment.   The winding type dry etching apparatus according to claim 1, wherein the anode electrode facing the main roller is configured as a shower plate that supplies an etching gas to the etching chamber and is applied with a high-frequency potential. A vacuum exhaust system that unwinds a film-like processed product with resin, partitions the vacuum chamber into a winding chamber, an etching chamber, and an intermediate chamber between the two chambers, and maintains these chambers at a required pressure difference. Is placed in each chamber, and the main roller is positioned in the intermediate chamber so that a part of the periphery of the main roller where the film-like processed material travels is exposed to the processing chamber. An etching electrode is provided in the etching chamber, and an etching gas is supplied from the anode electrode side to the etching processing chamber, and a film-type processed product is used to continuously perform plasma etching processing, using a winding type dry etching apparatus , plasma-reactive ion resin with film-like treated coming travels peripheral surface of the main roller by etching discharge etch Retractable dry etching method characterized by graying.   The winding type dry etching method according to claim 3, wherein a high frequency potential is applied to the anode electrode facing the main roller.   The winding type dry etching method according to claim 3 or 4, wherein nitrogen gas is added to an etching gas supplied to the etching chamber.

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