DD267517A1 - METHOD FOR SELECTIVE LASER METALLIZATION OF PARTIAL CATALYTIC SUBSTRATES - Google Patents

Abstract

The invention relates to methods for the selective laser metallization of partially catalytic substrates and serves for the production of metal layer structures on protective, or oxide layers covered dielectric, semiconductive or metallic substrates by means of laser beams. In a technological step, the laser beam destroys the protective or oxide layer of the substrate, which is in a chemical-reductive gold or silver bath and deposits a metal layer structure.

Description

The method relates to the additive selective Metallabscbeidung from chemical-reductive baths prepared completely or partially for the chemical-reductive metal deposition catalytically active substrates with laser beams. It is applicable in the field of electrical engineering / electronics for the production of electrically conductive structures.

Characteristic of the known technical solutions

In addition to the subtractive technique, additive solutions are known with the aid of adhesive technology. Successively, the surface is covered with a photoresist layer. After a selective exposure, the lacquer layer is partially dissolved by a mask, and the surface not covered with lacquer is chemistically reduced after activation with metal nuclei and optionally electroplated (lift-off technique, for example according to WP 213311).

It is also known to structure a dielectric capping layer by so-called "laser ablation" and then to metallize the opened windows (US 44 32 855) or to etch an existing metal layer with a laser. Laser Ablation "be selectively opened.

The laser ablation allows the production of masks >> us a preferred organic cover layer directly on the surfaces to be coated. There is a risk of the formation of oxides in the case of metallic surfaces, which must be removed before a further coating. In the FdII dielectric surfaces to be coated must be activated before the chemical-reductive deposition, which Edelmetailkeime be required.

It is well known that metallic layers of chemically-reductive (DD 157989) um.I galvanic (US 37075) baths can be selectively deposited on surfaces with laser beams. If other metal layer structures already exist on the surface, a second metallization takes place in the electrolyte used (eg cementation in noble metal octoxylates) or a detachment of the metal layers (eg aluminum layers in acidic or alkaline baths).

Object of the invention

The aim of the invention is to combine the additive and the structured metallized layer deposition in one process step. This is to achieve greater flexibility in terms of structural training.

Explanation of the essence of the charge

The invention has the object lugrunde to provide a method for the selective laser metallization of partially catalytic substrates.

An additive modification of already existing metal layer structures or a selective additive secondary or multiple deposition of metallic material on ready fully or partially catalytically active substrates which are covered by a completely closed protective or oxide layer is to be made possible.

According to the invention the object is achieved in that the covered with a completely closed protective or oxide layer substrates are introduced into a chemical-reductive gold or Silberbcci and irradiated with a programmed laser beam of predetermined power and wavelength in selected areas of the surface.

The laser beam is an argon ion laser with a pulse frequency between 60Hz and Vt 3Hz and with a power density between 10 ^? Wc " ² and 10" WcHrT ² .

The focal length of the laser beam is guided at a speed of ohm.sup.- ¹ with punctiform metal deposition up to 50 .mu.m.sup.- ¹ when the surface of the substrates is sputtered.

Wesen.liehe Bod components in addition to the metals are ammonia as a complexing agent and KNa tartrate.

In the besvrghiten point or the irradiated track wlro through the laser beam did destroyed protective or oxide layer and simultaneously deposited from the bath metal. ^E: re for most applications sufficient layer thickness of the metal deposit on the substrate a layer thickness of about 0,8pm has been found.

If transparent glasses are used as substrates, the laser irradiation can take place through the substrate.

The protective or oxide layer also absorbs the laser radiation in this case, so that, without increasing the power density, the same effects are obtained as when the laser radiation strikes the protective or oxide layer directly.

embodiment

The invention will be explained below with reference to two embodiments.

example 1

A glass substrate with a front Ag-Motallschichtstruktur and covered with Galvanolack to selectively receive additional interconnects. The glass substrate is introduced at room temperature in a chemical-reductive silver bath containing AgNO ₃ as a silver salt, ammonia as a complexing agent and KNa tartrate. Chelaplex was added as a stabilizer.

The bath vessel with the substrate bufindet on a computer-controlled xy-table. The laser beam of an argon ion laser with a pulse frequency of 100 Hz was adjusted to the glass surface. In a Laser.'eistungsdichte of 2.25 · 10 ³ Wcm ~ ² and a Verfahrgesch vindigkeit of the table 20 pms~ 'the Galvanolackschicht were destroyed, while the glass surface is provided with the desired Ag-conducting patterns.

Example 2

A silicon wafer covered with SiO ₂ , which already has aluminum interconnects, is to be additionally provided with gold dots as contact islands. The SiO ₂ -covered disc is introduced into the bath vessel, which is filled with a chemical reductive gold bath according to DD 150762 (but at room temperature). The bath vessel with the substrate is arranged to be movable. After switching on the argon-ion laser ² is destroyed with a pulse frequency of 80 Hz in 1.5 min, the SiO ₂ layer and point-like deposited on the SüiziumsuListrat with a layer thickness of about 0,8pm at a laser power density of 5.5 x 10 ³ Wcm ".

Claims (1)

Process for the selective laser metallization of partially catalytic substrates covered with dense, firmly adhering protective or oxide layers, characterized in that the partial destruction of the S-oxide or oxide layers and the selective metallization of the substrates with a programmed ion argon ion laser the Impulsfrequen. of 60-120 Hz and power density of 10 ² -10 ⁵ Wcm ~ ² with operating speeds of lOpms " ¹ ^ οδΟμηηβ" ¹ and residence times of 20s to 120s for point deposition in chemical reductive gold or silver baths is made. Field of application of the invention