DE2306278A1 - CAMERA SENSITIVE PHOTOMASKS - Google Patents

Description

AGFA-GEVAERTAG

LEVERKUSEN

PATENT DEPARTMENT

- 7th FEQ. 1073

Camera sensitive photomasks

For the production of microstructures as used in microelectronics are common, high-resolution exposure originals (masks) are required. They consist of a transparent one Support with a layer applied thereon which allows an image-wise controllable exposure of a receiving layer. Such masks mostly have a support made of glass and chromium or gelatin / silver halide as those for image-wise controllable Exposure of a receiving layer applied layer.

You can use masks z. B. after the projection exposure process or by the more commonly used contact copying process. However, this commonly used contact copying has the following major disadvantages:

a) Any dirt present in the layer carrying the image or in the image receiving layer causes copying errors or layer damage (pinholes), and the close contact between the two layers often leads to partial destruction of the mask,

b) the production z. B. a single chrome mask is very time consuming,

c) the z. B, used to make chrome masks Negative photoresists based on partially eyclized polyisoprene are sensitive to oxygen, so that

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an exposure device that works with inert gas (e.g. nitrogen) is necessary, otherwise it cannot be controlled Layer thickness fluctuations occur.

In order to remedy the disadvantages listed under a), the close contact copying process has been developed. Through the between mask However, the small air gap set between the and the image receiving layer (this avoids pinhole formation) is created fuzzy reproductions.

The less used projection exposure is a light-sensitive one Polymer layer required whose sensitivity maximum matches the emission maximum of the one used for its exposure Light source coincides. The known polymers can only be used to a limited extent for this purpose.

In the German Offenlegungsschrift 2 16o 77o a procedure to produce a forming at high speed and also described a layered photomask which has sufficient resolution and which has the disadvantages mentioned of contact copying can be eliminated. The material used Contains a transparent support coated with iron oxide or chromium, on top of which a light-sensitive polymer layer as an etch reserve and finally a thin layer of a photographic silver halide emulsion. According to the pictorial First exposure to light to which the polymer layer is not sensitive and therefore no difference in solubility is caused, but for which the silver halide emulsion layer is sensitive, is developed photographically. Then it is dried and a second exposure is carried out, namely with light of the wavelength that a solubility differentiation of the polymer layer, and then developed by treatment with a suitable solvent. The second exposure takes place with a homogeneous light field in the

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Size of the area to be exposed. Do the removal of the Silver image by removing it in distilled water at 5o ° C or a negative or positive relief image of the original is obtained in dilute hydrochloric acid. As part of it, with a selective etchant that is no longer crosslinkable polymeric photoresist layer covered chromium or iron oxide completely removed. The photoresist layer is removed and you get an exposure mask.

But this process also still has considerable specialist parts. An essential requirement of microelectronics is a high resolution of the photosensitive layers used. Due to the layer structure of the known material, the reflected scattered light is extremely high, so that desired high resolution is greatly reduced.

In addition, the production of the material used is difficult because the hydrophobic polymer layer is coated with the hydrophilic Siu-oerhalide emulsion considerable wetting difficulties occur, causing fluctuations in layer thickness or even incorrect coatings (pinholes) and delamination develop. These difficulties can also be solved by adding Usual wetting agents do not adequately remedy.

The invention is based on the object of a camera-sensitive To develop material for the production of photomasks, which has a sufficient resolving power and in simple Way is producible.

There has now been made a photographic material for the production of photomasks with one on a transparent substrate etchable metal or metal oxide layer located thereon, a light-crosslinkable polymeric photoresist layer located thereon and a light-sensitive silver halide emulsion

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layer found, being in the photoresist layer or a a separate layer disposed between the photoresist layer and the silver halide emulsion layer is contained, the absorption maximum of which is in the wavelength range for which the silver halide emulsion layer is essentially sensitive ..

The concentration of the screen dye can be further within Boundaries fluctuate. It depends on the properties of the photographic material and the desired result. in the In general, concentrations of 0.1-100 mg are preferred 0.4 - 10 mg per 100 g of the polymeric photoresist is sufficient.

The chemical constitution of the screen pigment is only of secondary importance. The best for the particular purpose suitable dye may rsuche easily be determined by the usual routine to the skilled artisan Y _e. When choosing, of course, the desired absorption range and the compatibility of the dye with the other components of the material must be taken into account,

Suitable screen dyes are e.g. B. in the German patent 1 171 267, Offenlegungsschrift 1 447: 030 or the U.S. Patents 3,245,796 and 3,647,447.

Preferably, the screen dye is the polymeric resist layer admitted. In certain cases it may be desirable to place the dye in a special interlayer. The usual hydrophilic or hydrophobic binders can then be used for this purpose. Again, these binders need

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be compatible with those of the other layers. Advantageously the same binder is used for the intermediate layer as in the silver halide emulsion layer, in particular Gelatin.

Also the choice of photopolymerizable or photocrosslinkable Systems for the resist layer is not critical per se. From the large number of known systems, this can be done for the respective Purpose of use can easily be determined by the usual experiments.

It can e.g. B. crosslinkable layers made of polyvinyl alcohol or copolymers with vinyl alcohol units, cyclo rubber or similar polymers with cinnamic acid compounds, organic Azides, carbonyl azides or sulfonyl azides as crosslinking agents be used. The crosslinking groups can be in the form of monomeric compounds or directly on the polymer chain bound to be present. Such systems are described in American patents 2,852,379 and 3,467,518. Reference is also made to American patents 2,687,958; 2.94-0.853; 3, o92,494 and 3,143,423. So-called Positive resists are also for the material according to the invention suitable, for example. to U.S. Patent 3,046,118. Suitable photopolymerizable layers are, for. B. in American patents 2,67o, 286; 2,76o, 863 as well as the German patent applications P 21 25 91 ο or P 21 21 253 described. Photo initiators that can be used for this are in J. C. Bloington's "Radical Polymerization", Academic Press New York (1961). Connections of these Type are z. B. hydrazones, 5-membered nitrogen-containing heterocyclic rings, mercapto compounds, pyrylium

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or thiopyrylium salts, thiooxanthrones, dyes of f-Redoxsy stars, Acridines or phenothiazines, ζ. B. according to German Offenlegungsschrift 2 o27 467. Also suitable are Lophine, e.g. according to British Patents 997,396 and 1,047,569, furthermore Λ, phenylethyl alcohols, polynuclear quinones such as anthraquinone, 2-methylanthraquinone, 2-tert-butylanthraquinone, butyl anthraquinone-2-carboxylate or phenanthrenequinones. Usable initiators are also benzophenone derivatives, e.g. B. according to British Patent 1,242,988 or compounds of the benzoin series such as benzoin, benzoin ether or hydroxy methylbenzoin. Reference is made to the American patents 3,639,321; 3,657,088; 3,6o7,693 or 3,636, o26.

About the difficulty of adhesion between the hydrophilic silver halide emulsion layer and to remove the hydrophobic polymeric resist layer, adhesion-promoting interlayers can be used be applied. Hydrolyzable organosilicon compounds have proven particularly favorable for this purpose. at the production of these adhesion-promoting intermediate layers is the material provided with the resist layer in a Brought atmosphere of dried nitrogen, which is saturated with easily hydrolyzable organosilane. The hydrolyzable Residues of the silane are then hydrolyzed, by placing the plate in a humid atmosphere. When using suitable organosilanes one achieves that the organophilic residues adhere to the resist layer and the after the hydrolysis obtained hydrophilic hydroxyl groups Make the resist layer for the gelatin anchored. Preferred hydrolyzable organosilicon compounds of the following formula are suitable:

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where R and X have the following meaning:

R = alkyl, preferably with up to 3 carbon atoms, in particular Methyl, or aryl, especially phenyl;

2 X = halogen, especially chlorine, or -O-R, where R Alkyl with preferably up to 5 carbon atoms, in particular ethyl, propyl or butyl,

After the support, vapor-deposited with a selectively etchable layer, with the optionally containing the screen dye Photoresist coated and the plate with the help of the

Wetting and adhesion promoting thin intermediate layer for the further processing is prepared, a silver halide gelatin emulsion is produced applied. This layer is applied in the usual way, e.g. B. by opening or To chi e ud em.

Fine-grain silver halide emulsions are preferred preferably silver bromide as the silver halide, if appropriate with a proportion of silver iodide up to 1o mol-f £. The grain size of the silver halide in the layer is preferably in the range under o, 1 / do, especially at around o, o5 yiam, especially those materials are suitable that are exposed to light of a line grid resolve at least 500 lines per mm.

The emulsions can also be chemically sensitized, e.g. with reducing agents such as tin (II) salts, polyamines such as Diethylenetriamine, sulfur compounds as in US Patent 1,574,944 or the book by Mees "! Theory of the Photographic Process "(1954), pages 149 to 161. For chemical sensitization of the specified Emulsions can also use salts of noble metals, such as ruthenium, rhodium, palladium, iridium, platinum or gold

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as in the article by R. Koslowsky, Z. Wiss. Phot., 46, 65-72 (1951). Compounds from the thiomorpholine series, e.g. B. those in the French patent 1 5o6 23o described, or also Polyalkylene oxides, especially polyethylene oxide and derivatives thereof.

The emulsions can also be optically sensitized, e.g. B. with the usual polymethine dyes, such as ne ut ro cyan inen, basic or acidic carbocyanines, mero or rhodacyanines, Hemicyaninen, Styry! Dyes, Oxonolen and the like. Such Sensitizers are described in the work by P. M. Hamer "The Cyanine Dyes and Related Compounds" (1964).

The emulsions can be hardened in the usual way, for example with formaldehyde or halogen-substituted aldehydes that contain a carboxyl group, such as mucobromine- acid, diketones, methanesulfonic acid esters, dialdehydes and the like.

Example 1 .

A vapor-coated with 1ooo AE chromium glass plate of the format 5 x 5 cm was empfindliehen UT-with one, cyclized negative-working, photo-crosslinkable polymers based on polyisoprene ^ (cyclized rubber) used as the photosensitive crosslinkers 2,6-di- (4 ^f azidobenzal) - contains cyclohexanone according to German patent specification 1,079,950, coated in a thickness of 0.6 / u. According to the invention, a dye is added to the casting solution for this resist layer, the absorption maximum of which is in the range of the light used for the first exposure of 546 nm. -

An umbrella dye (according to U.S. Patent 3,702,767) using the following formula:

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GH-CH = C S

-S

C-N "^

C ₂ H ₅

This dye can be dissolved in a solvent such as e.g. B. pre-dissolved cyclohexanone and then diluted with Photolaek thinner will. From this dye solution one sets the casting solution so much that a dye concentration of 1 mg Dye per 100 g of photoresist is achieved.

After 3o minutes drying of the resist layer at 80 ⁰ C a wetting and adhesion promoting monomolecular intermediate layer is applied, in such a manner that the plate is introduced with the dried resist layer in an atmosphere of dried nitrogen that is saturated with the easily hydrolyzable MethylphenyIdichlorsilan Then the chlorine atoms of the silane are hydrolyzed by placing the plate in a humid atmosphere.

Now a fine-grain silver bromide iodide gelatin emulsion sensitized for the green spectral range with a mean grain diameter <.o, o5 / u to that in 0. a. way treated resist layer and then spun on Room temperature dried. As a sensitizing dye for the photographic emulsion, a dye according to U.S. Patents 2,165,338 and 2,263,757 of the following formula are used:

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The camera-sensitive material produced in this way now becomes a Exposure mask processed by using a projection system whose lenses are corrected for light of a wavelength of 546 nm an imagewise first exposure is carried out., The light emerging from the gelatin layer is absorbed by the screen dye contained in the resist layer; this prevents scattered light reflections and thus the highest resolutions are achieved.

After exposure, the photographic development takes place exposed emulsion layer to a silver image as negative or reversal development.

After drying, a diffuse second exposure is carried out with light of about 35o nm, as a result of which the resist layer is hardened at the exposed areas. The silver image is removed by dissolving the gelatine in warm water or dilute hydrochloric acid and the plate is then dried. The processing of the exposed resist layer by spraying the developer - is a gasoline fraction having a boiling range of about 145 - 185 ° C and an aromatic content of about 20% by volume _o - by means of a fine nozzle. After development, the partially swollen varnish copy is treated with butyl acetate »

Then the relief obtained is image for about 30 minutes 120 ° C in order to etch the chrome with sharp contours allow., Finally, the resist relief is in the usual way removed An exposure mask is obtained.

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Example 2

The procedure is as described in Example 1, but the photo-crosslinkable polymer is on without the addition of a dye the chrome-coated glass plate is spun on. After pre-treatment an aqueous gelatin solution is applied to the dried resist layer to improve adhesion according to example 1, which have a diffusion-resistant dye of the formula

H ^ OH = CH

which is present as a non-diffusible silver salt (see U.S. Patent 3,471,293). This has its absorption maximum at 546 nm and is in a concentration of 120 mg Dye used per liter of gelatin solution.

After this layer has dried, the fine grain silver halide emulsion becomes applied and further processed as described in Example 1.

Example 3

Method according to example 1; however, one uses instead of one chrome-vaporized glass plate has a transparent support vapor-deposited with a 1000 AU thick silicon layer.

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Claims (5)

Claims Photographic material with one on 'one transparent Metal, metal oxide or silicon layer located on the substrate, a photo-crosslinkable layer arranged thereon polymeric photoresist layer and a photosensitive Silver halide emulsion layer, characterized in that in the photoresist layer or one between this and the silver halide emulsion layer arranged separate layer contains an screen dye, whose absorption maximum lies in the wavelength range for which the silver halide emulsion layer is essentially is sensitive. 2. Photographic material according to claim 1, characterized in that that the screen dye contained in the resist layer in amounts of 0.1-100 mg per 100 g of polymeric photoresist is. 3. Haotographlsch.es material according to claim 1. "characterized in that that one sensitized chemically and optically Silver halide emulsion layer is included. 4. Material according to claim 1, characterized in that a layer of on the hydrophobic photoresist layer a hydrolyzation product of an organic silicon compound the following formula is included: ^Ri n- ^SiX (4-n)
where mean: R = alkyl or aryl, 2 2 X = halogen or -0-R, where R is alkyl. A-G 1o71 - 12 - 409833/0541 5. Photographic material according to claim 1, characterized in that that the etchable layer consists of chromium or silicon. A-G 1o71 - 13 - 409833/0541