Method for preparing high-precision silver electrode through self-limiting wet etching

Abstract

The invention provides a method for preparing a high-precision silver electrode through self-limiting wet etching. The method comprises the steps of firstly oxidizing surface silver through employinga hydrogen peroxide solution or a diluted APM solution and other oxidation solvents, and stopping the oxidation reaction after the surface silver is completely oxidized; and then etching the surface silver oxide by using dilute nitric acid, wherein the reaction between the dilute nitric acid and the silver is very slow, and after surface silver oxide etching is finished, the etching reaction is ended. The self-limiting etching process is terminated after the etching of the etched object is finished, so that excessive CD loss caused by over-etching is avoided. The self-limiting Ag etching CD loss is related to the Ag film thickness and is about equal to the Ag film thickness. Oxalic acid is a special etching solution for metal oxide and does not react with Ag, so that Ag CD loss cannot be caused when ITO on the upper layer and ITO on the lower layer are etched. By means of the method, the etching CD loss of the Ag electrode can be reduced from one-step wet etching greater than 1 micronto about 0.1 micron, and the requirement for ultrahigh-resolution display is met.

Description

technical field [0001] The invention belongs to the field of new display technologies, in particular to Ag electrodes used in display industries including organic light-emitting diodes, silicon-based microdisplays, and digital micromirror chips, and in particular to a method for preparing high-precision silver electrodes by self-limiting wet etching. Background technique [0002] Because the reflectivity of Ag is as high as 98%, it is widely used in top-emitting organic light-emitting diode devices, but because silver (Ag) can only use wet etching process, CD loss is large (>1μm), so the Ag electrode structure cannot be applied To ultra-high resolution displays such as silicon-based microscopes and digital micromirror devices (DMDs). At present, ultra-high resolution displays mainly use aluminum (Al) electrodes, but the reflectivity of aluminum is low (about 91%), and Al is easy to cause hillocks and pits due to stress concentration and release during the annealing proces...

AI Technical Summary

Problems solved by technology

[0002] Because the reflectivity of Ag is as high as 98%, it is widely used in top-emitting organic light-emitting diode devices, but because silver (Ag) can only use wet etching process, CD loss is large (>1μm), so the Ag electrode structure cannot be applied To ultra-high resolution displays such as silicon-based microscopes and digital micromirror devices (DMDs)

At present, ultra-high resolution displays mainly use aluminum (Al) electrodes, but the reflectivity of aluminum is low (about 91%), and Al is easy to cause hillocks and pits due to stress concentration and release during the annealing process, and the surface flatness Poor; Aluminum has poor conductivity and severe electromigration, especially the resistance becomes larger and larger as the pixel size becomes smaller, electromigration becomes more and more serious, and electrical reliability deteriorates

Ag does not have the problem of poor surface flatness caused by stress changes, and Ag has good conductivity, so the development of high-precision, high reflectivity, and high-conductivity silver electrodes is very meaningful for ultra-high resolution displays.

[0003] At present, the Ag electrode mainly uses the ITO / Ag / ITO structure, and the nitrification mixed acid (nitric acid, phosphoric acid, acetic acid) one-step etching process, the nitrification mixed acid ITO etching rate is slow, the Ag etching rate is fast, and the etching time is long when etching the lower layer ITO. It will lead to a large amount of Ag over-etching; at the same time, because the Ag etching rate of nitrated mixed acid is very fast (300-500A / s), it is difficult to control over-etching, resulting in a large Ag CD loss

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