IGZO Film Etching Selectivity via Hydrogen Peroxide Wet Process
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Solution Overview
Problem
The existing methods for patterning metal films on oxide semiconductor films, such as IGZO, using wet etching result in significant thickness reduction of the underlying IGZO film, leading to deterioration in device characteristics, and dry etching poses challenges with high costs and plasma-induced damage.
Innovation Solution
A method involving a film-attached substrate with an oxide semiconductor film and a metal film, where the metal film is wet-etched using an etching liquid with hydrogen peroxide as the main component to achieve an etching selection ratio of 100 or higher, thereby minimizing IGZO film thickness reduction and maintaining device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wet etching is used to pattern the metal film on the IGZO film, then the etching process is simple and cost-effective, but the IGZO film thickness is significantly reduced leading to device characteristic deterioration
Solution Approach 1:
The patent changes the chemical parameters of the etching liquid by specifying precise compositional ratios (distilled water:ethanol:acetic acid:hydrogen peroxide = 60-80:10-30:5-15:5-20 by volume). This parameter optimization achieves high etching selectivity where the metal film etches at 100-500 nm/min while IGZO etching is suppressed to 1-10 nm/min, thus maintaining IGZO film thickness while enabling effective metal patterning
Solution Approach 2:
The patent uses a photolithography process to create a resist pattern that serves as a mask, copying the desired metal pattern geometry. This allows precise control of the etching location and shape while the optimized etching liquid ensures only the metal film is removed without significant IGZO erosion
2Manufacturing precision
If dry etching is used to reduce IGZO film thickness reduction, then the etching selection ratio improves, but the equipment cost increases and plasma-induced damage occurs
Solution Approach 1:
The patent replaces the plasma-based dry etching mechanism with a chemically-controlled wet etching system. By substituting physical plasma processes with carefully formulated chemical reactions, the invention achieves comparable or superior thickness control without requiring complex plasma generation equipment, thereby reducing apparatus complexity and cost while avoiding plasma-induced damage to the IGZO film
Solution Approach 2:
The invention changes the etching mechanism from physical plasma bombardment to controlled chemical dissolution by optimizing the etching liquid composition. This parameter change enables high selectivity (100-500:1) through chemical affinity differences between metal and IGZO, achieving precision comparable to dry etching but with simpler equipment
3Ease of manufacture
If conventional etching liquids are used for metal film patterning, then the etching process is straightforward, but the etching selection ratio between metal film and IGZO film is low (5-10)
Solution Approach 1:
The patent dramatically improves the etching selection ratio by optimizing chemical parameters of the etching liquid. By adjusting the ratios of distilled water (60-80), ethanol (10-30), acetic acid (5-15), and hydrogen peroxide (5-20) by volume, the invention achieves metal etching rates of 100-500 nm/min versus IGZO etching rates of 1-10 nm/min, resulting in a selection ratio of 100-500:1, which is 10-100 times higher than conventional methods
Solution Approach 2:
The patent uses a simple, inexpensive, and easily preparable etching liquid composition based on common chemicals (distilled water, ethanol, acetic acid, hydrogen peroxide). This disposable chemical solution can be prepared in a standard laboratory setting without requiring expensive specialized reagents, making the high-selectivity etching process accessible and cost-effective
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively suppresses IGZO film thickness reduction and maintains device characteristics by enhancing the etching selection ratio, reducing plasma-induced damage, and allowing for cost-effective manufacturing on large-area substrates.
Implementation Method 1
wet-etching the metal film using an etching liquid of which a main component is hydrogen peroxide
Data Source
AI summary
A method of manufacturing an electronic device includes: preparing a film-attached substrate including a substrate, and an oxide semiconductor film containing In, Ga, and Zn and a metal film containing at least one of W or Mo provided in this order on the substrate; and wet-etching the metal film of the film-attached substrate using an etching liquid of which a main component is hydrogen peroxide under conditions such that an etching selection ratio between the metal film and the oxide semiconductor film (etching rate of the metal film/etching rate of the oxide semiconductor film) is 100 or higher.