JP2919106B2 - Polyimide resin composition for laser processing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyimide resin for laser processing.

[0002]

2. Description of the Related Art FIGS. 4 (a) and 4 (b) show, for example, a publication {J.
Electrochem. Soc., Oct. (1990) p2522-2527} is a process diagram showing a conventional polyimide resin removal processing method in the order of processes, and is a light irradiation {Fig. 4 (a)} and a development diagram, respectively. 4 (b)}, patterning or hole formation {FIG. 4 (c)}
And heating {FIG. 4 (d)} step. In the figure, 2
Is a base material, 5 is a mask, 7 is a processed hole, 11 is a polyimide resin, 12 is a photosensitive polyimide precursor, 13 is a crosslinked portion, 14 is a light source, 15 is light, and 16 is a developer.

That is, by irradiating the photosensitive polyimide precursor 12 with light 15 from a light source 14 such as a mercury lamp to crosslink only the irradiated portion 13, the developer 1
6, the dissolving speed is reduced, and the light is selectively removed at the portion shielded by the mask 5. Thereafter, the polyimide precursor 12 to which the photosensitivity has been imparted has the structure of a normal polyimide resin 11 by heat treatment.

FIGS. 5A and 5B show, for example, a publication “Proceedings of LAMP '87 Osaka (May 1987) p5”.
81-584} are process diagrams showing a conventional processing method for removing a polyimide resin shown in FIG. 5 in order of steps, respectively, by laser irradiation {FIG. 5 (a)} and patterning or hole formation {FIG.
(B) Step (1) is shown. In the figure, 3 is a laser, 4 is a laser beam, and 6 is a lens.

That is, the laser beam 4 emitted from the laser 3
Is reduced and transferred to the polyimide resin 11 using the mask 5 and the lens 6. If the energy density of the laser is sufficient to remove the polyimide resin 11, removal processing such as patterning and hole formation is achieved. Further, the polyimide resin 11 in FIG. 5 is, for example, a publication “POLYIMIDES Blackie (19)
90) It is composed of a conventional polyimide resin shown in p2-8｝ and the like, and is synthesized by the following chemical formula 1.

[0006]

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That is, for example, a polyimide resin having a conventional structure is obtained by casting a polyimide precursor solution obtained by polymerizing an acid anhydride and a diamine in a solvent such as N-methylpyrrolidone, followed by dehydration and solvent removal. Here, the acid anhydride shown in FIG. 6 and the diamine shown in FIG. 7 are used.

[0008]

The conventional polyimide resin and its processing method shown in FIG. 4 have no effect of heat damage when a polyimide resin having photosensitivity is used, but have a large film thickness. In addition, it is not possible to crosslink deeply by light irradiation, and the crosslinked portion and the lower layer of the crosslinked portion are also removed at the time of development, and the removal process proceeds isotropically, so that the pattern width or the hole diameter becomes large, and film thinning occurs. As a result, it is difficult to form fine holes having a high aspect ratio and high quality. In addition, in this method, since the polyimide precursor is formed into a polyimide resin by heat treatment or the like after processing the polyimide precursor, there is a problem that shrinkage or deformation occurs during heating, and the price of the polyimide precursor to which photosensitivity has been imparted is high. There were also problems such as lower characteristics than polyimide. In addition, the conventional polyimide resin and its processing method shown in FIG. 5 are laser processing that does not require photosensitivity and can use the polyimide resin after the heat treatment. Conventional polyimide resins have long wavelengths (500 nm
Absorption at short wavelengths (200-300 μm).
nm). In the case of forming fine, high aspect ratio, high quality holes, using a long wavelength laser requires a large amount of energy due to the low light absorption of the material, which may cause thermal damage or damage to the underlying material. There is a variety of problems, such as in the case of using a short wavelength laser.Because the absorption is relatively large when using a short wavelength laser, it is possible to process with small energy and small heat damage and small damage to the underlying material. However, there have been various problems such as an increase in the cost of the laser, and the inability to keep up with the development of accessories such as an optical system.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and enables a fine, high aspect ratio, low damage processing and a short wavelength laser using a relatively inexpensive long wavelength laser. When using is finer than before,
An object is to obtain a polyimide resin composition for laser processing capable of performing high aspect ratio and high quality processing.

[0010]

The first polyimide resin composition for laser processing according to the present invention comprises a continuous carbon 6 member.
It is obtained by dehydrating and condensing a polyimide precursor mixed with a non-dye type aromatic polycyclic compound having only a ring as a skeleton .
In the second polyimide resin composition for laser processing according to the present invention, the non-dye aromatic polycyclic compound has 2 to 6 rings in the first polyimide resin composition for laser processing.

[0011]

Generally, in laser processing, a laser is absorbed by a material in accordance with the absorption coefficient (absorbance per unit length) of the material, and the absorbed energy is used for the processing. Also, when an aromatic polycyclic compound is dispersed in a polyimide resin, it generally has a large absorption coefficient over a wide wavelength range. In the polyimide resin of the present invention, since the aromatic polycyclic compound is dispersed, the absorption coefficient at each wavelength is large, so that the absorption in the depth direction is large, and the laser energy is concentrated on the extreme surface layer. Incidentally, the aromatic polycyclic compound is
Only the continuous 6-membered carbon ring is used as the skeleton.
"Continuation" means that adjacent 6-membered carbon rings share carbon.
I mean This energy instantly sublimates the resin,
Alternatively, the thermal energy is converted into kinetic energy that scatters the decomposed product far away, so that the thermal energy remaining in the polyimide resin is extremely small, and it is difficult to cause thermal damage to the periphery. For this reason, fine and high quality holes can be formed, and anisotropic processing can be performed, so that a high aspect ratio can be achieved by repeating this operation.

[0012]

FIG. 1 is a process chart showing a processing method using a polyimide resin composition for laser processing according to an embodiment of the present invention in the order of steps. In the figure, reference numeral 1 denotes a high light absorption type polyimide resin composition which is a polyimide resin composition for laser processing according to an embodiment of the present invention. The laser beam 4 emitted from the laser 3 is reduced and transferred to the high light-absorbing polyimide resin composition 1 using the mask 5 and the lens 6, and the energy density of the laser is sufficient to remove the high light-absorbing polyimide resin composition 1. If so, removal processing such as patterning and hole formation is achieved. Hereinafter, specific examples of the structure of the high light-absorbing polyimide resin composition 1 according to the present invention will be described, but the present invention is not limited to these examples.

Embodiment 1 Polyimide resin composition for laser processing according to an embodiment of the present invention
1 can be obtained by the following chemical formula 2.

[0014]

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That is, 1 to the weight of the polyimide precursor
About 0% of an aromatic polycyclic compound , anthracene,
It is mixed with N-methylpyrrolidone as a solvent which has been heated to about 80 ° C. in advance, sufficiently stirred, and then mixed with a polyimide precursor which has been heated to about 80 ° C. in advance. As the polyimide precursor, R ₁ was No. ₁ in FIG. The skeleton of the acid anhydride shown in 1,
R ₂ is No. in FIG. 1 is a polyamic acid solution which is a skeleton of the diamine shown in FIG. Then, add this mixture to 8
The coating is applied to the substrate with a spin coater or the like while maintaining the temperature at about 0 ° C. to form a uniform film. The film is prebaked at about 150 ° C. for about 30 minutes, and post-baked at about 300 ° C. for about 90 minutes, and remains in the film. By evaporating N-methylpyrrolidone and reacting a hydrogen group and a hydroxyl group contained in the molecular chain of the polyamic acid with water to form water and desorbing from the molecular chain, a polyimide resin composition for laser processing according to one embodiment of the present invention. Get things . At this time polyimide resin
Because the composition has finely dispersed anthracene,
Since the absorption coefficient for each wavelength is significantly increased, a high light absorption type polyimide resin composition is obtained. The wavelength of the high light-absorbing polyimide resin composition thus prepared was 530 nm.
Was about 2000 cm ^-1 , which was four times that of the conventional polyimide resin of about 500 cm ^-1 . As a result, the laser energy density required for laser processing is reduced, and for example, several J / cm
⁽²⁾ Necessary processing became possible at about several hundred mJ / cm ² , and processing without thermal damage to the periphery with controllability in the depth direction became possible. Further, in drilling with a wavelength of 248 nm, for example, using a KrF excimer laser with a diameter of about 10 to 20 μm, the conventional one that could only obtain a tapered hole became highly anisotropic, and a high aspect ratio became possible. . In the embodiment of the present invention, the effect of anthracene can be expected to be sufficient when the amount of anthracene is about 10% with respect to the weight of the polyamic acid. The degree is preferred.
If it is less than 3%, the effect is difficult to obtain, and if it exceeds 30%, dispersion becomes difficult.

FIGS. 2 (a) and 2 (b) are a sectional view of a processing hole and a laser beam in a depth direction of the processing hole during laser processing using the polyimide resin composition for laser processing according to the embodiment of the present invention. It is a characteristic diagram showing an energy density distribution,
FIGS. 3A and 3B are a cross-sectional view of a processed hole and a characteristic diagram showing a laser energy density distribution in a depth direction of the processed hole when laser processing is performed using a conventional polyimide resin, respectively. Figure E _r is minimum required laser energy density in machining, E _i is a laser energy density given. When the laser is applied to the laser processing polyimide resin composition 1 according to the embodiment of the present invention produced as described above, the absorption significantly increases. Therefore, the conventional polyimide resin 1 shown in FIG.
Compared to 1, the laser energy is absorbed at the extreme surface layer. For this reason, processing with good controllability in small processing units can be performed. Therefore, the aspect ratio can be increased, and even when the laser energy has a spatial distribution, the influence of the tapered processing hole 7 is small. At this time, the amount of heat remaining in the polyimide resin is reduced, and the influence of heat storage due to repeated irradiation is also reduced.

The aromatic polycyclic compound to be mixed with the polyimide precursor according to the present invention may be any as long as it can increase light absorption at a desired wavelength without impairing other characteristics of the polyimide. There is such an aromatic polycyclic compound, and the effect is generally larger as the number of rings is larger. In order to make these compounds more polar,
The aromatic polycyclic compound substituted with a reactive group while maintaining the case
The derivative of the product is more preferable because it is easily soluble in a solvent.

In the above example, the polyimide precursor solution was mixed with the aromatic polycyclic compound, and then heated and solidified to obtain the polyimide resin composition for laser processing according to the example of the present invention. When it is not particularly necessary to mix a group polycyclic compound , it may not be used. For systems where polyimide solutions can be directly obtained,
What is necessary is just to mix and disperse a polycyclic compound . When a solvent is used, the solvent is not particularly limited. For example, N-methylpyrrolidone, which is conventionally used, may be used. The processing hole is not limited to the hole reaching the base material shown in the figure, and may be a hole stopped halfway. Further, the present invention can be applied to a polymer material other than a polyimide resin.

[0019]

As described above, the present invention provides continuous carbon
What was obtained by dehydrating and condensing a polyimide precursor obtained by mixing a non-dye aromatic polycyclic compound having only a six-membered ring as a skeleton , for example, a non-dye aromatic polycyclic compound having 2 to 6 rings By using a laser, it is possible to process fine, high aspect ratio, and low damage even with a relatively inexpensive long wavelength laser.
A polyimide resin composition for laser processing that can perform high aspect ratio and high quality processing can be obtained.

[Brief description of the drawings]

FIG. 1 is a process chart using a polyimide resin composition for laser processing according to one embodiment of the present invention.

FIG. 2 is a cross-sectional view of a processed hole and a characteristic diagram showing a laser energy density distribution in a depth direction of the processed hole at the time of laser processing using the polyimide resin composition for laser processing according to an example of the present invention.

FIG. 3 is a cross-sectional view of a processed hole when laser processing is performed using a conventional polyimide resin, and a characteristic diagram illustrating a laser energy density distribution in a depth direction of the processed hole.

FIG. 4 is a process chart showing a conventional polyimide resin removal processing method in the order of steps.

FIG. 5 is a process chart showing a conventional polyimide resin removal processing method in the order of steps.

FIG. 6 is a diagram showing an example of an acid anhydride used for synthesizing a polyimide resin.

FIG. 7 is a diagram showing an example of a diamine used for synthesizing a polyimide resin.

FIG. 8 is a diagram showing an example of an aromatic polycyclic compound according to the present invention.

[Explanation of symbols]

1 Laser processing polyimide resin set according to an embodiment of the present invention
Product 4 Laser beam 7 Processing hole

Continuation of front page (56) References JP-A-61-192737 (JP, A) JP-A-62-47045 (JP, A) JP-A-63-142030 (JP, A) JP-A-4-189865 (JP) , A) JP-A-4-63870 (JP, A)

Claims (2)

(57) [Claims] 1. A laser processing polyimide resin composition obtained by dehydrating and condensing a polyimide precursor mixed with a non-dyeous aromatic polycyclic compound having only a continuous 6-membered carbon ring as a skeleton . 2. The non-dye type aromatic polycyclic compound having a ring number of 2
The polyimide resin composition for laser processing according to claim 1, wherein