The Electrochemical Characteristics of Alkyl Silane Self-Assembly Layers on ITO Film and Application to Etching Process
Date Issued
2009
Date
2009
Author(s)
Huang, Po-Rung
Abstract
Photo-lithography is an important process in the property of LED. There are three major parts in this process : 1. Photo-resist coating 2. Expoursion 3. Development. In fact, it will be finished the process with seven steps in detail. It will be more complex with whole process. In this experiment, we want to use the advantage of SAM to protect the ITO surface during etching process. Therer are three parts in this experiment : 1. Using contact angle, XPS, AFM, cyclic voltammetry and EIS analysis method discusses the property of SAM film with different conditions of SAM reation; 2. In the etchant of amorphous ITO, it analyzes etching rate, OCP and LSV method. It studies the properties of amorphous ITO in diffirent concentrations and types etchant, then finds the relationships between these experiment condition; 3. Combine the suitable condition of part 1 and part 2, using SEM, OCP and tafel method focuses on the level of protecting ITO then uses the BOE etchant to remove SAM on ITO. Furthermore, estimates the possibility of replacing the role of photo-resist.art I : In this experiment, we control two major conditions : 1. SAM chain length 2. The temperature of SAM reaction. From the result of SAM, longer self-assembly molecular owe to arrange in order and condenses tightly very much, cause by the force between each molecular. From the result of AFM and CV analysis, when the experiment of temperature is below Tc, the SAM film owns to perform uiniform.art II : In the process of etching with OXA solution, the etching rate of ITO will increase following the concentration of OXA. When the concentration of OXA is upward 3.4 wt%, the etching rate will approach constant. From tafel analysis method, adding acetic acid (AA) and tartaric acid (TA) , the corrosion potential will decrease from -0.331V to -0.38V. Adding AA and TA, it will change the ITO surface to remove easily, but for etching rate measurement, adding AA and TA will decrease the etching rate of ITO film. Cause of two results, adding chelate will change the proiperty of ITO surface, it will not increase the etching process. For the amount of chelate, when adding 0.34 wt% in OXA solution, it differs with the other one. From these results, choosing the 0.34 wt% chelate undergoes the etching process.art III : Focus on the ITO with protector-SAM in etching process. From tafel analysis result, SAM exists on ITO surface in the etchant will increase the corrosion potential from -0.38V to -0.2~0V. Only OXA 3.4 wt% system, from SEM result, the edge will occur default. If reducing the scale of element, this condition should not be accepted. At OXA 3.4 wt% + AA 0.34 wt% or OXA 3.4 wt% + TA 0.34 wt% condition, the edge of etching performs smooth one. For removal SAM, useing BOE etchant can remove SAM completely and BOE can not hurt ITO surface.
Subjects
Amorphous ITO glass
SAM
Oxalic acid
Wet etching
Type
thesis
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