JP4240586B2 - Processing method of imide heat-resistant resin film - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for processing an imide-based heat-resistant resin film, and relates to a technical field in which a thick-film imide-based heat-resistant resin film is used by forming a pattern.
[0002]
[Prior art]
Conventionally, as a processing method of an imide-based heat-resistant resin film such as polyimide, a chemical etching method using a concentrated alkaline aqueous solution or an organic alkaline solution such as hydrazine, a processing using a carbon dioxide gas, an excimer laser, a YAG laser, or the like. Methods or processing methods using plasma etching are known, and are used for various applications such as the manufacture of TAB and printed circuit boards. However, some types of basic skeletons of polyimide are difficult to etch, and further, organic alkali compounds such as hydrazine constituting the etching solution are harmful to the human body and are difficult to handle. In addition, laser processing is not often used for large-area batch processing because a single processing area is within the range of the laser diameter.
On the other hand, examples of processing polyimide by plasma etching include processing of a passivation film of LSI in the field of semiconductor manufacturing. The plasma etching method has an advantage that a large area can be collectively processed and etching can be performed regardless of the type of polyimide basic skeleton. In addition, since no harmful chemicals such as hydrazine are used, work safety is excellent.
[0003]
[Problems to be solved by the invention]
In the polyimide processing by plasma etching, a photosensitive resin is generally used as a mask for forming a pattern. However, in the case of plasma etching, the photosensitive resin is also etched together with the polyimide etching, so that the thickness of the polyimide film to be processed is increased. The thickness of the corresponding photosensitive resin layer is required. Therefore, there is a problem that the thickness of the processable polyimide film is limited by the maximum resolution film thickness of the photosensitive resin.
In addition, a photosensitive resin used as a mask for plasma etching has a problem that it is generally expensive because it has a photosensitive group, and is inferior in plasma resistance and heat resistance compared to a non-photosensitive resin.
Therefore, the present invention is a safe processing method for an imide-based heat-resistant resin film by plasma etching, and is intended to provide a processing method in which the amount of expensive photosensitive resin used is reduced.
[0004]
[Means for Solving the Problems]
Invention of the present invention according to claim 1 for solving the problems is the method of processing the imide-based heat-resistant resin film, a protective resin layer for plasma etching (1) the imide-based heat-resistant resin film on 0 A step of forming a thickness of 1 to 100 μm , (2) a step of covering the protective resin layer with a photosensitive resin layer, and (3) a process for processing the imide-based heat-resistant resin film on the photosensitive resin layer by a photolithography method. A step of forming a pattern, (4) a step of removing the protective resin layer exposed by partial removal of the photosensitive resin layer with an etching solution, and (5) an oxygen gas atmosphere of the exposed imide-based heat resistant resin film. characterized in the step of plasma etching in an oxygen gas atmosphere to 0.1~100Pa at ambient temperature pressure, to have a step of peeling the protective resin layer (6) To, the processing method of the imide-based heat-resistant resin film, in. Since it is this processing method, it can process safely, reducing the usage-amount of photosensitive resin.
[0005]
The invention according to claim 2 of the present invention for solving the above-mentioned problems is characterized in that, in the method for processing an imide heat-resistant resin film according to claim 1, the protective resin layer is composed of a novolak phenol resin. . The invention described in claim 3 is the processing method of the imide heat-resistant resin film according to claim 1, wherein the developer used in the photolithography method of the photosensitive resin layer is an etching solution for the protective resin layer. It is also characterized by serving. Because of this processing method, a developer for the photosensitive resin layer and an etchant for the protective resin layer can be used in combination.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Examples of the imide-based heat-resistant resin film processed in the present invention include a single film such as “Kapton” manufactured by Toray DuPont, and a polyimide and metal such as “Upilex” manufactured by Ube Industries, Ltd. A laminated material or a polyamic acid varnish applied to a carrier such as a metal thin film in the form of a film and then thermally cured and imidized can be used. The thickness of the imide heat-resistant resin film can be in a wide range up to about 0.1 to 100 μmt, and is particularly suitable for film processing with a thickness of 1 to 50 μmt.
[0007]
An embodiment of the present invention will be described with reference to FIG.
FIG. 1 is a diagram showing an example of a method for processing a heat-resistant resin film of the present invention. FIG. 1A shows a polyimide film with a copper foil obtained by bonding a copper foil 12 to a polyimide film 11. The processing method for this material will be described below.
Next, as shown in FIG. 1 (b), a non-photosensitive protective resin layer 13 dissolved in an organic solvent or the like to form a varnish is applied on the polyimide film 11 of FIG. Dry to remove. As this protective resin, a resin that is excellent in plasma resistance and heat resistance and can be easily removed by etching later can be used. For example, a novolak phenol resin that is an alkali-soluble resin is suitable. The thickness of the protective resin layer can be in the range of 0.1 to 200 μmt, more preferably set to a thickness of 1 to 100 μmt, depending on the ratio of the plasma etching rate between the imide-based heat resistant resin and the protective resin. Can do. As a method for applying the protective resin varnish, any method can be used as long as it can be applied with a uniform thickness. For example, spin coating, roll coating, dip coating, die coating, and the like should be adopted in consideration of the properties of the varnish. Can do.
[0008]
Next, a photosensitive resin layer 14 is formed on the protective resin layer 13 as shown in FIG. The photosensitive resin layer only needs to be resistant to the etching solution for the protective resin layer. For example, when a novolak phenol resin is used as the protective resin, a casein-bichromate resist or cyclized rubber is used. -Liquid resists such as azide resists and novolac resists, acrylic resin film resists, and the like can be used. The thickness of the photosensitive resin layer is sufficient if it can withstand the etching for patterning the protective resin layer.
[0009]
Moreover, in order to omit the peeling process of the photosensitive resin layer after the plasma etching, it may be a thickness that does not remain after being etched away with the polyimide during the plasma etching, and the thickness is set in the range of 0.1 to 50 μmt. It is preferable to do this. As a method of forming the photosensitive resin layer 14, when a liquid resist is used, methods such as spin coating, roll coating, dip coating, and die coating can be used. When a film resist is used, a roll laminator, a hot press, etc. Can be used. Next, as shown in FIG. 1D, a photosensitive resin layer 14P is formed by exposing, developing, and making a plate for plasma etching to the photosensitive resin layer 14 by photolithography. .
[0010]
Subsequently, as shown in FIG. 1E, the protective resin layer 13 is removed by etching from the opening 15 of the photosensitive resin layer, and both layers 14P and 13 are used for plasma etching of the imide-based heat resistant film. The mask 16 is used. As an etching solution when a novolak phenol resin is used as the protective resin layer, a low-concentration alkaline aqueous solution can be used. When a novolak phenol resin is used as the protective resin and a novolak resist is used as the photosensitive resin, the photosensitive novolak resist developer in the photolithography method of FIG. 1D and the protective resin in step (e) The layer can be used in combination with a novolac phenolic resin etchant and can be processed at the same time, so the process can be shortened.
Next, as shown in FIG. 1 (f), the imide heat-resistant film 11 is plasma etched from the mask opening 17. At this time, the patterned photosensitive resin layer 14P is completely removed by plasma etching, and the protective resin layer 13 is also partially etched.
[0011]
In the above, plasma etching in an oxygen gas atmosphere is performed by generating plasma by adding AC power between the cathode and anode in the vacuum vessel, and placing the plasma etching object in the cathode dark area near the cathode. . In this case, the pressure of the oxygen gas atmosphere is 0.1 to 100 Pa, preferably 3 to 50 Pa at room temperature. The amount of oxygen gas introduced is 1 to 80 cc / min, preferably 10 to 50 cc / min in the standard state. The processing power for plasma discharge is usually 0.05 to 5 kW, preferably 0.2 to 1 kW. The treatment time is 0.1 to 60 minutes, preferably 1 to 40 minutes. It is preferable to use alternating current for the processing power, and the frequency is 100 kHz to 100 MHz, and practically, the industrially assigned frequency is 13.56 MHz.
[0012]
Finally, the protective resin layer 13 is peeled and removed as shown in FIG. When novolak phenol resin is used as the protective resin layer, an aqueous sodium hydroxide solution can be used as the stripping solution. The concentration is 0.1 to 10%, preferably 1 to 5%. The temperature is from room temperature to 80 ° C, preferably from 30 to 60 ° C.
[0013]
【Example】
Example 1
On the polyimide surface of the laminate obtained by bonding a polyimide film with a thickness of 25 μmt to a copper foil with a thickness of 18 μmt, a non-photosensitive novolac phenolic resin dissolved in ethyl cellosolve acetate and applied in a varnish with a spin coater, The film was dried at 100 ° C. for 30 minutes to form a thickness of 50 μmt. This was laminated with a 15 μm thick acrylic resin-based dry film (“SUNFORT” manufactured by Asahi Kasei Co., Ltd.), and then a plate for polyimide film processing was applied, and the plate-dried dry film was heated and cured at 200 ° C. for 3 minutes. I let you. It was immersed in a 1% aqueous potassium hydroxide solution at room temperature, and the exposed novolak phenol resin was removed by etching. As a result, the polyimide film to be plasma-etched was exposed, and a mask pattern 16 of a dry film and a non-photosensitive novolak phenol resin was formed in the other portions.
[0014]
Next, a sample is set in a vacuum vessel of a dry etching apparatus manufactured by Nippon Vacuum Co., Ltd., the pressure inside the vacuum vessel is reduced, and after reaching 0.001 Pa, a mixed gas mainly containing oxygen gas is introduced. While evacuating, oxygen gas was introduced at a flow rate of 50 cc / min. The oxygen gas pressure was maintained at 50 Pa, plasma discharge was performed at a discharge power of 400 W and a frequency of 13.56 MHz, and the polyimide film surface 13 was plasma etched for 40 minutes. The remaining novolak phenol resin was peeled and removed, and it was confirmed that the polyimide film 11 on the copper foil was processed into a desired pattern.
[0015]
(Example 2)
On a polyimide surface of a laminate obtained by adhering a 18 μm thick polyimide film to a 20 μm thick SUS plate, a non-photosensitive novolac phenolic resin dissolved in ethyl cellosolve acetate was applied with a die coater. , And dried at 100 ° C. for 30 minutes to form a thickness of 30 μmt. On this novolak resin layer, a novolac azide-based resist was applied in a thickness of 5 μmt, and a plate for polyimide film processing was applied. At this time, the same chemical solution (1% aqueous potassium hydroxide solution) as that used for developing the novolak-azide resist was used to simultaneously remove the non-photosensitive novolak phenol resin by etching.
[0016]
Next, a sample is set in a vacuum vessel of a dry etching apparatus manufactured by Nippon Vacuum Co., Ltd., the pressure inside the vacuum vessel is reduced, and after reaching 0.001 Pa, a mixed gas mainly containing oxygen gas is introduced. While evacuating, oxygen gas was introduced at a flow rate of 50 cc / min. The oxygen gas pressure was maintained at 50 Pa, plasma discharge was performed at a discharge power of 400 W and a frequency of 13.56 MHz, and the polyimide film surface and the mask surface were plasma etched for 20 minutes. The remaining novolak phenol resin was peeled and removed, and it was confirmed that the polyimide film on the SUS plate was processed into a desired pattern.
[0017]
In the above examples, etc., the etching of the polyimide film is described. However, the present invention is not limited to polyimide, but other imide-based heat-resistant resin films containing an imide ring, such as polyamide imide resin, polyester imide resin, polyamide ester. It can be widely applied to films composed of imide resins, bismaleimide-triazine resins, and the like.
Moreover, it is possible to carry out etching processing advantageously in terms of cost for a wide range of film thicknesses of films and sheets made of these resins.
[0018]
【The invention's effect】
According to the present invention, since the thickness of the processable polyimide film is not limited to the maximum resolution film thickness of the photosensitive resin, it has an advantage that it can be applied to processing of a polyimide film having a wide film thickness. In addition, the resist for plasma etching has a two-layer structure, and physical properties such as plasma resistance and heat resistance are assigned to an inexpensive non-photosensitive protective resin, and the photosensitive resin is used for the role of pattern formation. Since it is not necessary to form a thick resin film, there is an advantage that it is advantageous in terms of cost as compared with plasma etching using an expensive photosensitive resin.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of a method for processing a heat-resistant resin film of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 Polyimide film 12 Copper foil 13 Non-photosensitive protective resin layer 14 Photosensitive resin layer 14P Patterned photosensitive resin layer 15 Photosensitive resin layer opening 16 Plasma etching mask 17 Mask opening

Claims (3)

In the method of processing an imide heat resistant resin film, (1) a step of forming a protective resin layer for plasma etching on the imide heat resistant resin film to a thickness of 0.1 to 100 μm , (2) the protective resin A step of covering the layer with a photosensitive resin layer, (3) a step of forming a pattern for processing the imide-based heat-resistant resin film by photolithography on the photosensitive resin layer, and (4) partial removal of the photosensitive resin layer. (5) removing the exposed imide-based heat-resistant resin film in an oxygen gas atmosphere at an oxygen gas atmosphere pressure of 0.1 to 100 Pa at room temperature. A method for processing an imide-based heat-resistant resin film, comprising: a step of plasma etching; and (6) a step of peeling off the protective resin layer.   The method for processing an imide heat-resistant resin film according to claim 1, wherein the protective resin layer is composed of a novolac phenol resin.   2. The method for processing an imide heat-resistant resin film according to claim 1, wherein a developer used in a photolithography method for the photosensitive resin layer also serves as an etching solution for the protective resin layer.

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