DE102006024175B3 - Light emitting diode primary multi-layer electrodes manufacturing method for e.g. backlight, involves masking epitaxial substrate with magnetizable mask that is hold by magnet, where magnetizable mask has contact windows - Google Patents

Abstract

The method involves cleaning a epitaxial substrate, and allowing to bring the epitaxial substrate into a holder. The epitaxial substrate is masked with a magnetizable mask that is held by a magnet, where the magnetizable mask has contact windows. A series of different metal sources with a primary metal layer is vapour-deposited on the epitaxial substrate. A multi-layer electrode is formed in the contact holes, and the mask is removed. The epitaxial substrate is cleaned with acid such as sulfuric acid, phosphoric acid and hydrochloric acid.

Description

technical area

The The invention relates to a process for the production of primary multilayer electrodes.

State of technology

The LED is an electronic solid state element with a P and N-electrode. If a small current through the two electrodes flows, can the LED lights up. Because the light-emitting diode through the recombination of electrons and holes generates a light that belongs to a cold light, the LED is through a small volume, low power consumption, high reliability and characterized a long life. Therefore, the light emitting diode for e.g. Indicator lamp, backlight, etc. used. The light-emitting diode usually has a two-element substrate, such as a GaP substrate, or a three-element substrate, such as GaAsP substrate, and even a four-element substrate, such as AlInGaP substrate, on.

The Substrate of the light-emitting diode is usually after the Epitaxieverfahren produced. On the substrate, the multi-layer electrodes are produced. How out

6 is apparent, the AlInGaP substrate is first cleaned in step S1. Subsequently, a primary metal layer sequence (eye and Au) is vapor-deposited on the AlInGaP substrate in step S2. Thereafter, a mask is generated by the first lithography in step S3. In step S4, the first wet etching of the metal layer is performed. After the first heat treatment in step S5, a secondary metal layer sequence (Ti and Au) is evaporated in step S6. Thereafter, a mask is generated by the second lithography in step S7. In step S8, the second wet etching of the metal layer is performed. Finally, in step S9, the second heat treatment is performed. As a result, the multi-layered electrodes are produced. The electrodes are in ohmic contact with the material of the substrate. In this manufacturing method, vapor deposition, lithography and wet etching are performed twice, so that the manufacturing process is complicated. In addition, the primary and secondary metal layer sequences may have poor contact. Furthermore, the secondary metal layer sequence can be detached by an external force.

Out US 2005/0191572 A1 is a structured magnetic mask Depositing for LCD, RFID, TFT's and OLED's known wherein as deposition substrates in addition to glass substrates and silicon mentioned is and as deposition materials in addition to semiconductors and dielectrics also called ladder. To avoid sagging the mask, the magnetic mask is to be applied to the deposition substrate by a magnet be stopped.

From the US 4,915,057 For example, an apparatus and a method for producing thin-film structure patterns on a substrate by means of a mask using a mask holder is known.

document US 2002/0025406 A1 relates to the pressing of Abdeckmasken on semiconductor plates at Bedampfungsvorgängen. For this purpose, a nickel mask, against which a semiconductor plate by means Springs is held, as well as another bracket and a magnet intended.

document DE 11 60 107 A relates to a metal mask and its manufacture, wherein a thin film is welded to a rigid frame such that the welds sink into recesses of the film and a close contact of the film to the deposition substrate. do not hinder. This mask may be about 10 microns thick and made of magnetic materials and then stopped by a magnet to the deposition substrate.

document DE 12 87 400 B relates to the vapor deposition of metal layers, such as Au or Al, by vapor deposition through a masking foil.

document GB 1 010 984 A relates to semiconductor devices and methods for their production with differently shaped electrodes by means of deposition through a mask.

document JP 04-137620 A relates to a method for producing electrodes for LED's. After depositing of n- and p-layers and AuGe, eye, Ti and Au, the workpiece is covered with a mask, the only ones surfaces free, where electrodes should remain. Subsequently, the workpiece is in one nitrogen atmosphere heat treated. Thereafter, the Ti is nitrided.

task the invention

Of the Invention is based on the object, a process for the preparation from primary To create multilayer electrodes, which are based on lithography and a wet etching omitted, whereby the manufacturing process is simplified, so that the production costs are considerably reduced.

These Task is performed by a method of o.g. Kind of claim 1 specified method steps solved.

• (a) das Epitaxiesubstrat wird gereinigt,
• (b) das Epitaxiesubstrat wird in einen Halter eingebracht und mit einer magnetisierbaren Maske, die Kontaktfenster aufweist, abgedeckt, wobei die magnetisierbare Maske durch einen Magneten gehalten wird,
• (c) auf dem Epitaxiesubstrat wird eine primäre Metallschichtfolge aus unterschiedlichen Metallquellen aufgedampft, wodurch in den Kontaktfenstern jeweils eine Mehrschichtelektrode gebildet ist, und
• (d) die Maske wird entfernt.

For this purpose, the following method steps are provided according to the invention:

• (a) the epitaxial substrate is cleaned,
• (b) the epitaxial substrate is placed in a holder and covered with a magnetizable mask having contact windows, the magnetizable mask being held by a magnet,
• (c) a primary metal layer sequence of different metal sources is vapor-deposited on the epitaxial substrate, whereby a multi-layer electrode is formed in each of the contact windows, and
• (d) the mask is removed.

The magnetizable mask adheres to the attraction of the magnet on the epitaxial substrate, whereby the epitaxial substrate is stable in the holder lies. After vapor deposition or after step (d) is a heat treatment carried out, thus between the epitaxial substrate and the multilayer electrodes an ohmic contact is created.

Appropriately, The epitaxial substrate is cleaned with chemicals such as acid or alkali.

The Chemicals include sulfuric acid, nitrate, hydrogen peroxide solution, phosphoric acid and Hydrochloric acid.

In A preferred embodiment of the invention is the epitaxial substrate in an oven of 300 ° C up to 1000 ° C introduced and for Heated for 5 to 50 minutes, thus between the epitaxial substrate and the multilayer electrodes an ohmic contact is created.

The Magnetizable mask is preferably a magnetizable, stainless Steel or nickel-iron alloy foil.

The magnetizable mask has a thickness of, for example, 10 microns to 300 microns, in particular of 30 μm.

The Metal sources preferably contain liquid eye, Ti and Au, wherein the metal sources eye, Ti and Au successively on the epitaxial substrate deposited and then covered with a top Au metal layer become.

short Description of the drawings

1 a flow chart of the method according to the invention,

2 a sectional view of the device according to the invention,

3 a flow chart of an embodiment of the method according to the invention,

4 a sectional view of the primary multi-layer electrodes after evaporation,

5 a sectional view of the primary multi-layer electrodes, wherein the magnetizable mask and the holder are removed and

6 a flow diagram of the conventional method.

Ways to execute the invention

The The invention relates to a method for producing primary multilayer electrodes, that dispenses with lithography and wet etching and a holder in conjunction with a magnet and a magnetizable mask used.

1 shows a flowchart of the method according to the invention. First, in step (a), the epitaxial substrate is cleaned with chemicals such as acid or alkali, eg sulfuric acid, nitrate, hydrogen peroxide solution, phosphoric acid, hydrochloric acid or their mixture, to remove oxides, dirt or metal ions on the surface of the epitaxial substrate.

Subsequently, will placed the epitaxial substrate in a holder and with a magnetizable Mask covered (step (b)). Thereafter, a primary metal layer sequence deposited on the epitaxial substrate (step (c)). Finally will the magnetizable mask and holder are removed (step (d)). Thereby the multilayer electrodes are obtained (step (e)).

2 shows a sectional view of a device 10 that has at least one support plate 11 includes, on which a holder 13 is arranged, which has a receiving recess 16 for the epitaxial substrate C. Between the carrier plate 11 and the holder 13 is a magnet 12 which may be an aluminum-iron-boron, samarium-cobalt or oxide magnet. The epitaxial substrate C becomes the receiving recess 16 of the owner 13 introduced and with a magnetizable mask 14 covered, which may be a magnetizable, stainless steel or nickel-iron alloy foil and has a thickness of 10 .mu.m to 300 .mu.m, in particular 30 .mu.m. The magnetizable mask 14 has a plurality of contact windows 15 to form the multilayer electrodes. In a variety of crucibles 31 each becomes a different metal source 30 , such as liquid eye, Ti and Au, added. The crucibles 31 can be arranged in rows or distributed in a ring. 3 shows a flowchart of an embodiment of the method according to the invention. First, the epitaxial substrate is gerei nigt. Subsequently, the epitaxial substrate is placed in the holder 13 introduced and with the magnetizable mask 14 covered by the magnetic attraction of the magnet 12 adheres to the epitaxial substrate C, whereby the epitaxial substrate C stably in the receiving recess 16 of the owner 13 lies. Thereafter, the metal sources eye, Ti and Au are filled in the crucible and sequentially deposited on the epitaxial substrate (vapor-deposited in the present embodiment). The metal sources eye, Ti and Au can also be repeatedly deposited on the epitaxial substrate. In the present embodiment, the metal sources eye, Ti and Au are sequentially deposited on the epitaxial substrate and then covered with an uppermost Au metal layer. Therefore, in the places of the contact windows 15 each a multilayer electrode 40 formed as in 4 shown. Thereafter, the magnetizable mask and the holder are removed, as in 5 shown. Finally, the epitaxial substrate C is placed in an oven with a temperature of 300 ° C to 1000 ° C and heated for 5 to 50 minutes, so that between the epitaxial substrate C and the multi-layer electrodes, an ohmic contact is formed.

There the metal sources almost vertically over the epitaxial substrate is on the epitaxial substrate a deposited homogeneous metal layer. This can be the length and Width of the process chamber enlarged or the bow degree of the shuttle will be reduced so that the metal sources be deposited vertically on the epitaxial substrate.

Claims (10)

Process for the preparation of primary multilayer electrodes with the following steps: (a) the epitaxial substrate is cleaned, (B) the epitaxial substrate is placed in a holder and with a magnetizable mask having contact windows, covered, wherein the magnetizable mask is held by a magnet, (C) on the epitaxial substrate becomes a primary metal layer sequence of different Vapor deposited metal sources, whereby in the contact windows each one Multilayer electrode is formed, and (d) the mask is removed. Method according to claim 1, characterized in that that the epitaxial substrate with chemicals such as acid or alkali, cleaned becomes. Method according to claim 2, characterized in that that the chemicals sulfuric acid, Nitrate, hydrogen peroxide solution, Phosphoric acid and hydrochloric acid are. Method according to claim 2, characterized in that that after step (d) a heat treatment carried out becomes. Method according to claim 4, characterized in that that the epitaxial substrate is placed in an oven of 300 ° C to 1000 ° C and for 5 to Heated for 50 minutes is, so between the epitaxial substrate and the multilayer electrodes an ohmic contact is created. Method according to claim 1, characterized in that that the magnetizable mask is a magnetizable, stainless Steel or nickel-iron alloy foil is. Method according to claim 1, characterized in that the magnetizable mask has a thickness of 10 μm to 300 μm. Method according to claim 1, characterized in that the magnetizable mask has a thickness of 30 μm. Method according to claim 1, characterized in that that the metal sources are liquid Eye, Ti and Au included. Method according to claim 9, characterized in that that the metal sources eye, Ti and Au successively on the epitaxial substrate deposited and then covered with a top Au metal layer become.