EP0626019A1

EP0626019A1 - Method of producing a metal film

Info

Publication number: EP0626019A1
Application number: EP93922919A
Authority: EP
Inventors: Hilmar Esrom; Harald Reiss
Original assignee: Heraeus Noblelight GmbH
Current assignee: Heraeus Noblelight GmbH
Priority date: 1992-12-11
Filing date: 1993-10-07
Publication date: 1994-11-30
Also published as: WO1994013854A1; JPH07506876A

Abstract

L'invention se rapporte à un procédé d'obtention d'une couche métallique (2M) recouvrant totalement ou partiellement un substrat (1) constitué d'un matériau organique ou inorganique. La couche métallique (2M) est formée à partir d'un composé chimique présentant un composant métallique. Le composé est d'abord vaporisé, déposé par condensation sur la surface du substrat (1) et décomposé, par irradiation aux UV, pour produire une couche métallique (2M). En vue d'obtenir une homogénéité élevée de la couche métallique (2M) et de former une arête vive, on refroidit le substrat (1), pendant le dépôt du composé chimique et l'irradiation, à une température se situant dans la gamme cryogénique.The invention relates to a process for obtaining a metallic layer (2M) completely or partially covering a substrate (1) made of an organic or inorganic material. The metallic layer (2M) is formed from a chemical compound having a metallic component. The compound is first vaporized, deposited by condensation on the surface of the substrate (1) and decomposed, by UV irradiation, to produce a metallic layer (2M). In order to obtain a high homogeneity of the metallic layer (2M) and to form a sharp edge, the substrate (1) is cooled, during the deposition of the chemical compound and the irradiation, to a temperature in the cryogenic range. .

Description

Process for the production of metallic layers

description

The invention relates to a method for the production of full-area or partial metallic layers according to the preamble of claim 1.

Such methods are used to produce conductor structures on substrates or to form metallic layers which should have a homogeneous structure.

A method for producing a metallic layer is known from EP-A 03 49 946. For this purpose, the solution of an organometallic compound is applied to a substrate. This film is then irradiated with UV radiation and the compound is converted into a metallic layer. What cannot be achieved with this method is a layer with a very homogeneous structure and a very sharp edge structure.

The invention is based on the object of demonstrating a method by means of which metallic layers with a homogeneous structure can be deposited in sharply delimited areas of a substrate surface. This object is achieved by the features of claim 1.

According to the invention, a chemical compound which has at least one metallic component is first evaporated at 400 ° C. and supplied to the surface of a substrate by means of a carrier gas. The substrate is heated to a temperature of _. -196 ° C cooled. It is thereby achieved that the gaseous compound condenses on the surface of the substrate. The chemical compound is adsorbed on the surface of the substrate. Suitable chemical compounds for this purpose are organometallic compounds or metal alkyls. Because of the complex molecular structure, a specific adsorption takes place, in particular on polar adsorbent molecules, that is to say that not only dispersion interactions take place between adsorbate and adsorbent molecules, but also interactions due to permanent electrical moments. This means a preferred lowering of the potential energy of the adsorbate molecules at defined adsorption sites determined by the crystal lattice of the adsorbent. By cooling the substrate according to the invention to a minimum temperature of -196 ° C., the mobility of the adsorbate molecules is sensitively restricted. The thermal energy of the atoms is small compared to the binding energy of complex particles on the surface of a solid. The adsorption is localized because the thermal energy is not sufficient to detach the adsorbed particle from its specific bond. As a result, diffusion and other uncontrolled and undesired transport processes of adsorbate molecules on the surface and all events which are disadvantageous for subsequent deposition process steps, such as reactions between radicals during UV radiation, are prevented. The substrates used can have any geometry. They can be made from all materials that are temperature-resistant down to -200 ° C. The substrate is cooled, for example, with liquid nitrogen. After the condensation of the chemical compound on the surface of the substrate, the surface is irradiated with incoherent UV radiation of a defined wavelength, the substrate being cooled further. A UV high-power radiation is preferably used for this, which, depending on the gas filling, generates UV radiation with a wavelength between 60 nm and 320 nm. A mask can be arranged between the radiation source and the surface of the substrate, which mask is provided with passages at predetermined locations. This means that the layer on the surface is only partially irradiated. With the aid of the mask, certain structures, for example conductor tracks, with an amorphous structure and a very sharp edge structure can be formed on the substrate at predetermined locations. By irradiating the layer, it is decomposed and a metallic layer is formed. The non-irradiated areas can be removed. For this purpose, the substrate is heated, for example, to the sublimation temperature of the layer. As a result, the non-irradiated areas of the layer are evaporated. If this is not possible, the undecomposed areas of the layer are washed off. The desired structures remain on the surface of the substrate, which are provided with extremely sharp edges and have a very high degree of homogeneity.

Further features essential to the invention are characterized in the subclaims.

The invention is explained in more detail below with the aid of schematic drawings.

Show it:

1 shows the structured coating of a substrate,

2 shows the coated substrate according to FIG. 1.

1 shows a flat substrate 1 on the surface IS of which a metallic layer is to be deposited. The substrate is in the embodiment shown here made of aluminum oxide (AI2O3). However, the metallic coating can also be formed on other substrates (not shown here) which are made of an organic or inorganic material which is resistant at least to temperatures of -200 ° C. In the exemplary embodiment shown here, the substrate 1 is cooled to -196 ° C. before being coated with liquid nitrogen (not shown here). Subsequently, a chemical compound with a metal component 2 in the form of an acetylacetonate or a metal alkyl is evaporated at about 440 ° C. and supplied to the surface of the substrate 1 with the aid of a carrier gas. As the substrate is cooled to - 196 ° C, the vaporized compound condenses on the surface and is adsorbed there. In the exemplary embodiment shown here, copper acetylacetonate is deposited on the surface. The thickness of the deposited layer is selected so that the metallic layer 2M to be formed has a thickness between 0.5 and 50 nm after completion. Instead of copper acetylacetonate, it is also possible to apply an organometallic compound whose metal component is palladium. It is also possible to use a metal alkyl which has Al, Ga, In, Si, Ge, Zn or Pb as the metallic component.

As shown in FIG. 1, a UV high-power radiator 3 is arranged at a defined distance above the surface IS to be coated of the substrate. A detailed description of this high-power radiator can be found in EP-OS 02 54 111. The high-power radiator 3 consists of a discharge space (not shown here) which is delimited by a metal electrode (not shown here) and a dielectric (likewise not shown here) and is filled with a noble gas or gas mixture. The dielectric and the second electrode lying on the surface of the dielectric facing away from the discharge space are transparent to the radiation generated by silent electrical discharge. Through this con- structuring and by a suitable choice of gas filling, a large-area high-power radiator for generating incoherent UV radiation with high efficiency is created. With the help of a gas filling made of helium or argon, UV radiation with a wavelength between 60 and 100 nm or 107 and 165 nm can be generated. A xenon gas filling allows the generation of UV radiation with a wavelength between 160 and 190 nm, the maximum being 172 nm. With a gas filling made of argon fluoride or krypton fluoride, UV radiation in the wavelength range between 180 to 200 nm and 240 to 250 nm can be generated. With a gas mixture of xenon and chlorine, the UV lamp can produce a UV wavelength of 300 to 320 nm. If the metallic layer 2M to be formed is to have a defined structure, there can be between the high-power radiator 3 and the surface IS of the substrate

1, a mask 4 can be arranged, which has passages 4D at those points at which a metallic layer is to be formed on the surface IS of the substrate 1. By irradiating the deposited layer 2, it is decomposed and a metallic layer is formed. The substrate 1 is kept at the minimum temperature of -196 ° C. both when the chemical compound 2 is deposited and when the deposited layer 2 is irradiated. If the layer 2 has decomposed, the cooling of the substrate 1 can be ended. The areas of the layer 2 which are not decomposed during the irradiation through the mask 4 now have to be removed from the surface IS. For this purpose, the substrate 1 can, for example, be heated to the sublimation temperature of the chemical compound if it is not made of a temperature-sensitive material. As a result, the areas of layer 2 that have not been decomposed sublimate. What remains in FIG.

2 shown structured metallic layers 2M on the surface IS of the substrate 1.

Claims

1. A process for the production of entire or partial metallic layers (2M) from a chemical compound (2) which has at least one metal component, on a substrate (1) by irradiation with a UV radiation source (3), characterized in that Substrate (1) is cooled to a temperature in the cryotemperature range during defined process steps.

2. A process for the preparation according to claim 1, characterized in that the chemical compound evaporates at 440 ° C and is supplied with a carrier gas to the surface (IS) of the substrate (1) and is separated there by condensation.

3. The method according to any one of claims 1 or 2, characterized in that the substrate (1) during the condensation of the chemical compound on the surface (IS) of the substrate (1) and during the irradiation of the deposited layer (2) the UV radiation is used to cool the liquid nitrogen to a temperature of at least -196 ° C.

4. The method according to any one of claims 1 to 3, characterized in that the deposited layer (2) is completely or partially irradiated with a high-power radiator (3), the UV radiation with a wavelength between 60 nm and 320 nm generated.

5. The method according to any one of claims 1 to 4, characterized in that an organometallic compound or a metal alkyl, in a thickness between 10 and 50 nm is applied to the substrate (1).

6. The method according to any one of claims 1 to 5, characterized in that a chemical compound in the form of palladium or copper acetylacetonate or a metal alkyl having AI, Ga, In, Si, Ge, Zn or Pb as the metallic component at 400 ° C evaporates and is supplied to the surface (IS) of the substrate (1) with a carrier gas in the form of argon.

7. The method according to any one of claims 1 to 6, characterized in that for irradiating the deposited layer (2) a UV high-power lamp (3) with a gas filling made of helium, argon ^" , argon fluoride, krypton fluoride, xenon or a gas mixture Xenon and chlorine is used, which generates incoherent UV radiation in the wavelength range between 60 nm and 320 nm.

8. The method according to any one of claims 1 to 7, characterized in that the chemical compound (2) on the surface (1) of a substrate (1) is deposited, which is made of an organic or inorganic material, which is in the cryogenic temperature range is stable.