Wet Etching of a Gallium Indium Zinc Oxide Semiconductor for ThinFilm Transistor Application

Lee, Sanghyuk; Seo, Bo-Hyun; Seo, Jong Hyun

doi:10.3938/jkps.53.2603

Cited by 15 publications

(10 citation statements)

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“…However, it is a challenge to patterning the source/drain (S/D) electrodes directly on the oxide semiconductor layer (back-channeletch, BCE) via wet etch as in a-Si TFTs, because the oxide semiconductors are very weak in most of the wet etchants. 6,7 Thus, the S/D electrodes should be etched via dry etch, 8,9 but the plasma bombardment and the residual ions such as Cl À or F À during dry etch would cause the degradation of the TFT devices. 10,11 Some groups [12][13][14] have reported on adding an etch stopper layer (ESL) which is formed and patterned before S/D electrode deposition to protect the channel during etching of the S/D electrodes, but it will make the processes more complicated and increase the cost.…”

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confidence: 99%

High performance indium-zinc-oxide thin-film transistors fabricated with a back-channel-etch-technique

Lan

et al. 2011

Applied Physics Letters

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Indium-zinc-oxide thin-film transistors (TFTs) with back-channel-etch (BCE) structure were demonstrated. A stacked structure of Mo/Al/Mo was used as the source/drain electrodes and patterned by a wet-etch-method. Good etching profile with few residues on the channel was obtained. The TFT showed a field effect mobility of 11.3 cm2 V−1 s−1 and a sub-threshold swing of 0.24 V/decade. The performance of this kind of TFT was better than that of the TFT with etch-stopper-layer structure, which was proved to be due to the lower contact resistance. The BCE-TFTs fabricated with this method have good prospect due to the advantage of low cost.

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confidence: 99%

High performance indium-zinc-oxide thin-film transistors fabricated with a back-channel-etch-technique

Lan

et al. 2011

Applied Physics Letters

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“…The Mo residues tend to be oxidized in the S/D wet etching. It has been reported that the oxidized Mo residues are able to act as acceptortype defects and induce degradation of the SS value of BCE-type TFTs [4]. where q is the electron charge (1.6x10 -19 C), H is the dielectric constant of the IGZO (here it is assumed H IGZO is the same as H ZnO : 10), H o is the permittivity of free space (8.85x10 -14 Fcm -1 ), E is the applied potential, E FB is the flat band potential, and N is the donor density.…”

Section: Resultsmentioning

confidence: 99%

“…Adding fluorine ions into copper wet etchant is believed to be inevitable step in removing molybdenum residue after copper/molybdenum wet-patterning. Due to the low etch selectivity (less than 1) between the S/D and IGZO layer, the IGZO layer is instantly etched out during the BCE S/D wet patterning step [4]. This results in the poor electrical performance of BCE type IGZO TFTs [5].…”

Section: Objective and Backgroundmentioning

confidence: 99%

P-56: Eco-Friendly Copper Metallization for IGZO and LTPS with New Molybdenum Barrier Layer

Seo

Kim

2016

SID Symposium Digest of Technical Papers

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As copper metallization processes have been widely adopted in the panel display industry, waste treatment costs including those for fluorine ions in copper wet etchant have also dramatically increased. The reduction of fluorine ions in copper metallization processes will be a key eco-friendly business issue in the near future. For this paper, new molybdenum alloy as a copper barrrier layer for IGZO and LTPS applications was developed that can be easily wet-patterned in copper wet etchant without etch residue. First, the effects of metal electrodes on the electrical performance of back channel etching type amorphous In-Ga-Zn-O thin film transistors were studied. Then, a secondary ion mass spectroscopy depth analysis revealed that the detected molybdenum content on the IGZO surface after wet patterning experienced a ten-fold reduction compared to pure molybdenum. In addition, new molybdenum alloy showed better thermal resistance properties compared to pure molybdenum. After the Mo alloy/copper/ Mo alloy tri-layers were annealed at 400 o C for 1 hour, the electrical resistance decreased from 5.7 Pohm-cm to 3.2 Pohm-cm, while the pure molybdenum tri-layer showed a dramatic increase after thermal annealing. The reduced molybdenum residue after wet patterning also influenced the electrical properties of the back channel etching type IGZO TFTs. The mobility measured between 10~14 cm 2 /V.sec and the contact resistance was about 0.5 Mohm. Both value were comparable to reported value.

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“…Other favorable aspects of ZnO include its chemical reactivity to many acids leading to many opportunities for wet chemical etching. Many etching methods using HCl have been reported to develop a rough surface and then induce a light scattering effect, which can significantly improve light trapping (and therefore current photogeneration) [8,9,[18][19][20][21]. HCl etching agent was also used to study the corrosion behavior of ZnO thin films in acid solutions [22].…”

Section: Introductionmentioning

confidence: 99%

Detailed microstructure analysis of as-deposited and etched porous ZnO films

Shang

Thimont

Barnabé

et al. 2015

Applied Surface Science

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ZnO nanostructured materials in thin film forms are of particular interest for photovoltaic or photocatalysis processes but they suffer from a lack of simple methods for optimizing their microstructure. We have demonstrated that microporous ZnO thin films with optimized inter grain accessibility can be produce by radio frequency magnetron sputtering process and chemical etching with 2.75 mM HCl solution for different duration. The as-deposited ZnO thin films were first characterized in terms of structure, grain size, inter grain space, open cavity depth and total thickness of the film by XRD, AFM, SEM, profilometry and optical measurements. A specific attention was dedicated to the determination of the surface enhancement factor (SEF) by using basic geometrical considerations and images treatments. In addition, the porous fraction and its distribution in the thickness have been estimated thanks to the optical simulation of the experimental UV-Visible-IR spectrums using the Bruggeman dielectric model and cross section SEM images analysis respectively. This study showed that the microstructure of the as-deposited films consists of a dense layer covered by a porous upper layer developing a SEF of 12-13 m 2 m −2. This two layers architecture is not modified by the etching process. The etching process only affects the upper porous layer in which the overall porosity and the inter-grain space increase with the etching duration. Column diameter and total film thickness decrease at the same time when the films are soaked in the HCl bath. The microporous structure obtained after the etching process could generate a great interest for the interfaces electronic exchanges for solar cells, photocatalysis and gas sensors applications.

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Wet Etching of a Gallium Indium Zinc Oxide Semiconductor for ThinFilm Transistor Application

Cited by 15 publications

References 0 publications

High performance indium-zinc-oxide thin-film transistors fabricated with a back-channel-etch-technique

High performance indium-zinc-oxide thin-film transistors fabricated with a back-channel-etch-technique

P-56: Eco-Friendly Copper Metallization for IGZO and LTPS with New Molybdenum Barrier Layer

Detailed microstructure analysis of as-deposited and etched porous ZnO films

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