JPH06857B2 - Photoprocessing of polycyclic fused aromatic polymers - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a polymer that is easily photoprocessed by ultraviolet light, and has a polycyclic fragrance having at least two or more aromatic nuclei such as naphthalene nucleus, anthracene nucleus or biphenyl nucleus in the main chain. The present invention relates to optical processing of group polymers.

In the method of the present invention, (1) photo-oxidative decomposition easily occurs when irradiated with ultraviolet rays.

(2) Photo-oxidative decomposition occurs efficiently when irradiated with an ultraviolet laser.

However, (3) the physical properties of the polymer in the non-irradiated part and the part to which the light does not reach hardly change.

Since it has the characteristics as described above, it can be used for various purposes described below.

I. Photo-resist or intercalating agent for dry etching used in processes such as production of semiconductor integrated circuits, photoelectroforming, chemical etching of metal plates, and production of printed wiring boards (halogen for side chain alkyl group of aromatic nucleus). When a polymer in which is substituted is used, a photoresist for direct etching) II Read only memory (R
Abbreviated as OM)) organic polymer base material (potentially capable of accumulating memory in a direction perpendicular to the surface
OM) III Organic polymer material for fine porous film (ribbon tape material for thermal transfer (used many times) as tape-shaped material, and small material such as contact lens that easily permeates oxygen) Further optical processing Because it is unique and easy, layered processing is possible and, in the state where heat history is hard to remain, it is possible to provide polymer moldings with characteristics such as punching, cutting, surface processing with ultraviolet rays to related industries. .

Relationship with Prior Art In recent years, photo-etching and photo-machining technologies have made rapid progress,
In addition to efforts for miniaturization, many proposals have been made for streamlining processes. For example, N Ueno (Japanese Jou
nal of Applied Physics Vol.20, No.10 October L709〜
L712 (1981)) attempted dry etching of photoresist with deep ultraviolet rays having a wavelength of 180 to 290 nm, and reported that the development step could be omitted.

As photoresist, poly (methylmethacrylate), poly (methylisopropynylketone), A
Deuterium discharge lamp (Deuterium Discharge) was used as the discharge lamp using Z-1350 (Novolak resin improved with naphthoquinone-o-diaside).
Lamp) is used.

Further, as a method of inducing photoetching of the polymer by irradiating the polymer with ultraviolet rays having a wavelength shorter than 220 nm, R.Srinivasan of International Business Machines Corporation (abbreviated as IBM) is used. This is a well-known reaction that is widely known as an effective method for eliciting photodecomposition of organic polymers (Ablative Photo Decompostion).

In Japan, as well, Japanese Patent Publication No. Sho 59-12945, a method of etching polyester, Japanese Patent Publication No. 59-69931, a method of etching polyimide, and Japanese Patent Publication No. Sho 59-105638, a far-ultraviolet patterning method for resist materials, filed by IBM Corporation. Has been done.

However, all of the above prior arts use only deep ultraviolet rays having a wavelength shorter than 290nm, and it is obvious that the organic polymer is a photoprocessing technology for only aliphatic compounds and monocyclic aromatic compounds. Is.

For example, it is specified in the above-mentioned IBM Publication No. 59-12945 that a high-pressure mercury lamp, a xenon lamp and a carbon arc lamp are ineffective for the induced photodecomposition reaction and cannot be used.

In addition, subsequent related reports such as Earl Srinivsan (eg J, Am. Chem. Soc. 1984 , 106, 4288-4290, Journal of Poly
mer Science Polymer Chemistry Edition, Vol.22,2601
~ 2609 (1984)), the polymers that are the subject of research are poly (methyl methacrylate), poly (ethylene terephthalate), polycondensation polyimide of benzenetetracarboxylic acid and monocyclic aromatic diamine, monocyclic aromatic It is limited to the polycarbonate of the system, that is, the polymer of the aliphatic or monocyclic aromatic system.

Polymers that are mainly used as photoresist materials that use ultraviolet rays are: ○ Water-soluble colloidal photoresists (eg poly (vinyl alcohol)) ○ Polycinnamic acid photoresists (eg poly (vinyl cinnamate)) ○ Rings Rubber type photoresist (monocyclic aromatic bisazito)
Both are aliphatic and monocyclic aromatic polymers.

A heterocyclic aromatic compound is used in the quinone diazide photoresist, which utilizes the property that quinone diside releases nitrogen by light. It is a photoresist that utilizes a photoreaction that is essentially different from the photo-oxidative decomposition of UV light.

Further, some of the photosensitive polymers include a polymer containing an anthracene group as a photosensitive group, but all of them relate to a photodimerization type photosensitive polymer and are not photodegradable type polymers.

The influence of the wavelength of ultraviolet rays differs between the aliphatic or monocyclic aromatic polymer and the polycyclic condensed aromatic polymer.
Report of Earl Srinivsan (Journal of Polymer Sci
ence Polymer Chemistry Edition Vol.22,2601 ~ 2609 (1
984)), aliphatic polymers (eg poly (methylmethacrylate) monocyclic aromatic polymers (eg poly (ethylene terephthalate)) are etched by lasers with wavelengths of 248 nm and 308 nm, but with wavelengths longer than 193 nm. It has been reported that the mechanism of its induced decomposition is higher than that of photolysis, and that the more efficient the etching, the more the above-mentioned polymer is decomposed by the thermal decomposition. Therefore, it is suggested that it is difficult to process without heat history.

On the other hand, it is well known to use a low molecular weight polycyclic fused aromatic compound as a photosensitizer. For example, Masataka Murahara et al. (Applied Physics, Vol. 52, p. 83 (1983 etc.) conducted extremely forward-looking research on photo-etching of poly (methyl methacrylate) by excimer laser, and at that time, anthracene, acridine, biphenyl Etc. are used as sensitizers, that is, poly (methylmethacrylate) is dissolved in a solvent, and these sensitizers (10% added) are applied to the substrate, and this is applied at about 100 ° C. I use the baked one for photo etching.
It is said that the sensitizing effect of these low-molecular sensitizers gradually decreases with increasing baking temperature, and the sensitizing effect is completely lost at about 200 ° C. The reason for this is believed to be that these low molecular weight additives are vaporized and diffused together with the solvent used for baking the substrate. It is said that higher baking temperature is indispensable to prevent resist weeping when developing, but low molecular weight sensitizers cannot raise baking temperature, so surface weeping is sufficient. There are drawbacks that cannot be prevented.

The present inventors, based on the above findings, ultraviolet rays from a square lamp,
The present invention has been achieved as a result of an intensive search for an organic polymer that is easily photoprocessed even with a laser emitting a wavelength shorter than 380 nm (the contribution of thermal processing is small) and does not vaporize and dissipate even when the baking temperature is raised. It is a thing.

That is, the present invention provides a polymer containing a polycyclic fused aromatic compound such as a naphthalene nucleus, an anthracene nucleus or a biphenyl nucleus in the skeleton of most of the main chain of a polymer efficiently without being thermally processed by ultraviolet rays. , Is a method of optical processing.

The polycyclic condensed aromatic compound constituting the skeleton of the polymer is a polymer compound characterized by being a condensed aromatic compound such as naphthalene, anthracene, and biphenyl,
Further, an alkyl group (hereinafter abbreviated as R group) in the aromatic nucleus of naphthalene, anthracene, biphenyl and the like, an R group in which halogen is substituted in the side chain R group, a methalkoxy group, a hydroxy group, an aniline group, N (R) ₂ Group, a substituent such as NHCOR group, which causes electron accumulation in an aromatic nucleus, or a nitro group, a sulfone group,
A substituent such as a SO ₂ R group, a cyano group, an aldehyde group, a COR group, a carboxylic acid group, a carboxylic acid ester group, a NH ₃ group or an NR ₃ group which reduces the electron density of an aromatic nucleus, as well as a halogen group or the like. Polymers of polycyclic fused aromatic compounds whose photoprocessing speed is controlled by substituting one or two or more of them are also included in the category of the subject polymer composition of the present invention. The polymer composition may be one synthesized by radical polymerization or polycondensation, and may be a crystalline polymer or an amorphous polymer. You can use crystalline polymer as it is, or use it for optical processing in the uniaxially or biaxially oriented state.
There is no problem in providing it to the market as a final product.

Furthermore, copolymerization with other polymers to the extent that the physical properties of the other polymers are not significantly impaired, or to increase added value,
It cannot be claimed to be outside the scope of the present invention by blending or block polymerizing, adding a photosensitizer, a catalyst such as a dye as a photosensitizer, a salt of a transition metal as a catalyst, or the like. .

For example, even if the target polymer of the present invention is used as a sensitizer even for a few percent to improve the photoetchability of poly (methyl methacrylate) resist, it is within the scope of the present invention. Regarding the molecular weight of the polymer of the present invention, it may be necessary to have a higher molecular weight than the ordinary polymer depending on the purpose of use, but when used as a sensitizer of poly (methyl methacrylate), the baking temperature The molecular weight may be such that it does not vaporize and dissipate.

The ultraviolet light used for the optical processing is so-called ultraviolet light having a wavelength shorter than 380 nm, but light including visible light, for example, mainly sunlight can be used.

When it is desired to perform optical processing over a wide area, sunlight (or light collected by a Fresnel lens or the like) may be used as shown in the first embodiment.

However, industrially using discharge lamps (high-pressure mercury lamps, xenon lamps, oxygen arcs, mercury resonance lamps, etc.) and stacking multiple lamps, it is possible to process a relatively large area with high efficiency. You can do it.

At this time, if a precise pattern is required, the photomask, the aligner for wafer exposure, and other techniques, processes, and equipment used in the integrated circuit process are used to perform almost the same precise processing. You can

When the technology accumulated in the integrated circuit process is applied to the polymer of the present invention, a product highly functionalized can be produced as an example showing the industrial effect of the present invention. That is,
If a photomask having an arbitrary shape pattern is used, the arbitrary pattern can be accurately transferred onto the surface of the target polymer of the present invention, and a thermal history remains in the work piece by injection molding or thermal processing. According to the present invention, it is possible to industrially obtain a product in which the heat history hardly remains, while the product described in (1) can be manufactured.

Furthermore, by continuing the optical processing, a large number of holes having an arbitrary pattern can be processed on the surface of the subject polymer of the present invention to an arbitrary depth, and if desired, perforated.

GORE-TEX, a microporous membrane using polymers,
Fluorophore, Jura Guard, Millipore, Nucleapor, etc. (all of which are brand names) are marketed and evaluated in related industries, and their usage is appropriate to their characteristics.

However, these microporous membranes have the drawback that the shape of the holes cannot be made arbitrary. Therefore, by combining the target polymer of the present invention with the existing technology of generating light having a wavelength shorter than 380 nm and the technology of utilizing it, a microporous membrane having an arbitrary shape can be prepared.

At present, an ultraviolet laser which is technically reaching the perfection range ... A combination of a laser having a wavelength shorter than 380 nm and the target polymer of the present invention is used to obtain a new function. Will be efficiently provided to

These lasers include N ₂ (wavelength 337 nm), XeCl (wavelength
308nm), YAG (1/4 wavelength (4th harmonic) 256nm), K
There are lasers such as rF (wavelength 248 nm) and ArF (wavelength 193 nm). The polymer of interest of the present invention is an extremely suitable polymer as a polymer having almost no thermal history when these laser beams are condensed using an optical system such as a lens and subjected to optical processing such as drilling and cutting. Becomes

Further, a porous film having a large number of fine holes per unit area can be applied if the technology under development of the semiconductor laser printer and related technology-for example, the technology of an optical system such as a polygon mirror and an Fθ lens can be applied. It could be made using macromolecules.

On the other hand, the technology considered to be possible by dispersing the laser light by using a lens or using a discharge lamp with a small output is to modify the surface of the target polymer (for example, to make the hydrophobic property hydrophilic). It is to be.

Another way of combining the ultraviolet laser or discharge lamp with the photomask and the subject polymer of the present invention is to combine a plurality of photomasks.

In this case, the polymer of the present invention provides a plurality of etch holes having different depths depending on the number of photomasks used, in the direction perpendicular to the plane.

Therefore, if a method for reading out etch holes (memory) having different depths is developed, the polymer of the present invention can be used as a ROM substrate in which memory is recorded not only on a plane but also in a vertical direction. Is implied.

Next, the optical processing conditions (temperature, irradiation atmosphere) will be touched upon. If the light processing temperature is high, the light processing speed will be remarkably high. However, in general, it may be in the range of room temperature to 100 ° C. However, in the case of a polymer that is difficult to process, the temperature may be further raised, or irradiation with light having another long wavelength-for example, far infrared rays, infrared rays, carbon dioxide laser, etc. may be used supplementarily.

The optical processing may be performed in air diluted with nitrogen or under reduced pressure if it is desired to reduce the speed, but the higher the oxygen partial pressure in the atmosphere gas, the faster the processing speed in general, and the higher the pressure. It is also preferable to carry out irradiation.

It is reported that in the prior art utilizing only deep ultraviolet rays, the processing speed does not change or does not significantly increase even if the oxygen partial pressure in the irradiation atmosphere is increased. (For example, N Ueno etc. Ja
panese Journal of Applied Physics Vol.20, No10 Octo
ber L709 ~ L712, Earl Srinivsan, etc.Jounal of Pol
ymer Science Polymer Chemistry Edition, Vol.22,2601
~ 2609 (1984)). However, in the polymer of the present invention, the processing speed is remarkably increased by increasing the oxygen partial pressure in the range where oxygen does not significantly change to ozone. This can be one proof that the present invention is a technology different from the prior art.

The light processing can also be carried out by immersing the target polymer of the present invention in an aqueous solution, for example, an alkaline aqueous solution.

Hereinafter, poly (ethylene naphthalate-2.6) (hereinafter referred to as PEN-2.
6) and poly (ethylene terephthalate) (hereinafter abbreviated as PET) as a comparative example.

However, the following examples do not limit or restrict the scope of claims of the polymer composition of the present invention.

Example-1 Photoprocessing with sunlight A biaxially stretched PEN-2.6 film (100 cm x 100 cm x 20.3 µ) of outdoor brand having physical properties as shown in Table 1 was prepared.
A 100 cm × 100 cm slate plate with a hole having a diameter of 1 cm and a slate plate without a hole were sandwiched between the plates, and the surface having the holes was exposed to sunlight while the plate was held vertically.

After 180 days, the film sample was taken out and examined, and it was found that the slate plate had holes completely in the holes.
Therefore, an average of 1100Å Etch was performed per day (sunshine hours).

For comparison, general electric brand biaxially stretched PEN-2.6
Film and biaxially oriented PET film (domestic product of T company)
Was exposed and tested outdoors. In order to examine the physical properties of the remaining film which was not etched by light, the film was tested by exposing it to sunlight. Table 2 shows the results of examining the change in film thickness after 3 months.

Table 3 shows the physical property changes of the PEN-2.6 film before and after the test, and Table 4 shows the physical property changes of the PET film before and after the test.

The PEN-2.6 film has PE at both the secondary dislocation point and the softening point.
It was found that the etching rate by sunlight was 5 times or more higher than that of the T film, although the heat resistance was higher at about 40 ° C. and about 10 ° C., respectively.

As shown in Tables 3 and 4, although the PEN-2.6 film was easily etched by sunlight, the physical properties of the portion which was not etched by light were not significantly changed.

Therefore, the biaxially-stretched PEN-2.6 film exhibits better weather resistance under natural conditions than the biaxially-stretched PET film, although it is easily etched by ultraviolet rays. (Reference: I. Ouchi et al., Proc. 17th Jap
an Congr. Mater. Res., 217 (1974)) Example-2 Optical processing with a high-pressure mercury lamp Biaxially stretched PEN-2 with various thicknesses as shown in Table 5
6 film high pressure mercury lamp (Toshiba H400P400
The change in film thickness was measured by irradiation with W).

This high pressure mercury lamp is 546nm, 436nm, 570nm, 40
It is a lamp that has a characteristic that it is irradiated with light having wavelengths of 2 nm, 313 nm, 302 nm, and 209 nm, and the mutual intensity thereof becomes weaker in the above order.

The distance between the mercury lamp and the film sample was 20 ^cm , the atmosphere was air, and the temperature was maintained at 50-60 ° C.

There is a precision injection molding method as a technology for industrially performing precision processing at a depth of about 1000 Å in the vertical direction to the plane, and it has already been established as a manufacturing method for compact desks and video desks, and many products have already been put on the market. There is.

As shown in Table 5, with a discharge lamp with a wattage of 400 W, the etching rate in the direction perpendicular to the plane is 160-240 Å
Although it is slow as per hour, industrially, discharge lamps of 3 to 6 KW or more are available on the market for xenon short arc lamps, mercury short arc lamps, far ultraviolet lamps and the like. Therefore, PEN-2.6 can be optically processed under economical processing conditions by selecting a suitable lamp from these lamps according to the purpose and properly selecting the optical processing conditions such as temperature and oxygen partial pressure. .

Example-3, Optical Processing by XeCl Excimer Laser A sample was irradiated with a XeCl (wavelength 308 nm) laser through a stainless steel aperture having a 3 mm square hole to conduct a drilling experiment. The irradiation power density was 5.5 MW / cm ² (irradiation energy density was 1.4 g / cm ² after passing through the aperture), the pulse width was 25 ns full width at half maximum, the continuation time was 110 ns, and the repetition frequency (pulse interval) was 10 Hz. It carried out and tested it on the condition which avoids thermal processing as much as possible. The following table shows the number of irradiation shots required to make a hole through the sample.

On the other hand, we tried to irradiate XeCl laser for the purpose of modifying the film surface. Irradiation power density was reduced to 0.6 MW / cm ² (irradiation energy was 120 mg / pulse), pulse width was 20 ns full width at half maximum, repetition frequency was 10 HZ, and beam cross-sectional area was 5 mm.
The sample was directly irradiated at × 20 mm. The samples used were biaxially stretched PEN-2.6 and unstretched PEN-2.6 film.

In the experiment, the number of irradiation shots was changed up to 1000, and it was observed that as the number of irradiation shots increased, the irradiation surface became darker and the color gradually became darker. For reference, the distance between the electrodes was set to 10 mm, and the surface resistance was measured with a simple surface resistance measuring device for each of the films; the number of shots was 100 and 10 ⁶ ohms, and the number of shots was 750 and 10 ⁴ ohms. It was found that the surface resistance value was remarkably reduced.

Example-4, Optical processing of poly (imide) film by ultraviolet rays A water-cooled special discharge lamp with a near-ultraviolet ray transmitting filter of 1.5 KW was used as a light source, and the film sample was placed on a rotary table 150 mm away from the light source, and the temperature was set to 80. Ultraviolet irradiation was carried out for 100 hours while keeping the temperature below ℃. The film thickness and breaking elongation after irradiation were measured and compared with the measured values before irradiation.

When the irradiation energy on the film surface was measured with a UV digital meter, it was 44 ± 1 MW / sec at 365 nm.

From the above table, the poly (imide) of the biphenyl tetracarboxylic acid having a polycyclic fused aromatic nucleus and the diamine has a large reduction in the film thickness after irradiation as compared with the poly (imide) of the benzenetetracarboxylic acid and the diamine. It was also found that the elongation retention rate after irradiation was high.

Example-5 It was found that photoprocessing with KrF excimer laser and poly (imide) with diamine are also easily etched by light. The poly (imide) of this system has two kinds of films on the market, which are said to have different kinds of diamines. (Hereinafter, poly (imide) -A and poly (imide) -B
Abbreviated. The poly (imide) used in Example-4 was
-B. ) Using these poly (imide) s and PEN-2.6 as samples, we carried out experiments with a KrF excimer laser.

In the experiment, the full width of pulse width is 20 ns, the normal repetition frequency (pulse interval) is 1 to 20 Hz, and the irradiation power density is 5 to 10 MW.
The test was conducted in the range of / cm ² . To change the irradiation power density, use a convex lens (focal length 100 mm) if necessary,
Through a stainless steel aperture with a 3mm square hole,
The aperture holes were adjusted to combine to obtain the desired power density.

The test was performed by determining the number of shots required to make a hole through the sample at a given power density and repetition frequency. The results of the test are shown in FIG.

As a result, (1) In irradiation with a discharge lamp, PEN-2.6 and poly (imide)-
There was a significant difference in photoetching property from B, but Kr
There is almost no difference in irradiation with F laser.

(2) For any sample, there is a linear relationship between the depth of etching per pulse and the power density. (3) The number of shots required to make a through hole is almost unchanged even if the repetition frequency (pulse interval) is increased.
(The contribution of thermal processing is small.)

[Brief description of drawings]

The accompanying drawings show the relationship between the depth of etching per pulse and the power density in Example-5 of the present invention.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masahiro Hosoi, Masahiro Hosoi, 3-37-19 Oyama, Sagamihara City, Kanagawa Prefecture, Teijin Limited Plastics Research Institute (72) Inventor, Takatoshi Kuratsuji 77 Kitayoshida-cho, Matsuyama-shi, Ehime (56) References JP-A-56-43332 (JP, A) JP-A-59-78271 (JP, A) JP-A-49-48631 (JP, A) JP-A-45-28892 (JP, A)

Claims (1)

[Claims] 1. A method of photo-processing a polymer containing a polycyclic fused aromatic compound in most of the skeleton of the main chain of a polymer with ultraviolet light.