Microstructure evolution in high density AZO ceramic sputtering target fabricated via multistep sintering

Kalvani, Payam Rajabi; Shapouri, Samaneh; Jahangiri, Alireza; Jalili, Yousef Seyed

doi:10.1016/j.ceramint.2019.11.053

Cited by 7 publications

(8 citation statements)

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“…1A), which can translate into less desired functional properties such as lower density and higher resistivity. Furthermore, the Gaussian distribution of the secondary phase particles widens considerably at 1300°C, which hints at possible competing recrystallisation‐exsolution mechanisms that can signal uneven atomic distribution of aluminium in the main phase (Rajabi Kalvani et al ., 2020). However, the variation in the postsputter images is less subtle.…”

Section: Resultsmentioning

confidence: 99%

“…This can hint towards the more homogenous distribution of Al atoms within the target and thus possibly improved sputtering characteristics. As the calling card of Zener pinning, it can be deduced that the severe reduction in secondary phases signals a more homogenous grain distribution, which can be confirmed in the presputter grain size analysis as seen in Figure 1 (according to the results obtained in Rajabi Kalvani et al ., 2020). It would be expected that based on this factor alone, the morphological characteristics would be profoundly different, though electrical characteristics are dependent on other factors as well.…”

Section: Resultsmentioning

confidence: 99%

“…Aluminium‐doped zinc oxide ceramic sputtering target consisting of 98% w/w ZnO submicron precursor with 2% w/w Al 2 O 3 nanopowder (

\sim 8 0 normalnm

) has been fabricated via multistep pressureless sintering at 1100°C, 1200°C and 1300°C, as detailed in our previous work (Rajabi Kalvani et al ., 2020).…”

Section: Methodsmentioning

confidence: 99%

“…(2014) demonstrated a correspondence between fractal analysis and optical properties for magnetron sputterewd zinc sulfide (ZnS) and aluminium‐doped zinc oxide (AZO) thin films, respectively. Since the micromorphology of material with competing phases can provide insight into the chemical and crystal defects (Ţălu et al ., 2018; Papež et al ., 2020; Rajabi Kalvani et al ., 2020), electron microscopy can be a valuable yet accessible tool for the assessment of functional parameters as seen in the aforementioned studies. While many methods for defect characterisation exist, the semiconductor industry is in need of a facile and accessible approach for analysis of optoelectronic devices during and after the fabrication process (Papež et al ., 2020).…”

Section: Introductionmentioning

confidence: 99%

“…Previously, we have demonstrated a novel economic multistep sintering method to fabricate the initial AZO target (Rajabi Kalvani et al ., 2020) which was then installed in the sputtering chamber and utilised for the production of thin films (Rajabi Kalvani et al ., 2019). Submicron zinc oxide together with nanometric alumina powder was used which resulted in the formation of exsolution and recrystallisation effects on the presputtered target.…”

Section: Introductionmentioning

confidence: 99%

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Quantitative SEM characterisation of ceramic target prior and after magnetron sputtering: a case study of aluminium zinc oxide

Jahangiri

Kalvani

Shapouri

et al. 2020

Journal of Microscopy

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Summary Till now electron microscopy techniques have not been used to evaluate the plasma–target interactions undergone during the magnetron sputtering process. The destructive nature of this interaction severely alters the target microstructure. Utilising quantitative microscopy techniques can shed light on the complex plasma and solid‐state processes involved which can ultimately lead to improved functional thin film deposition. As a representative functional material, aluminium‐doped‐zinc oxide (AZO) is an upcoming alternative to conventional transparent electrode wherein the process optimisation is of great importance. In this paper, we evaluate the pre‐ and post‐sputter field emission scanning electron microscopy (FESEM) data for ceramic AZO target fabricated at three final sintering temperatures (1100°C, 1200°C and 1300°C). In all cases, grain boundaries are merged in addition to a visible reduction in the secondary phases which makes segmentation‐based image analysis challenging. Through surface statistics (i.e. fractal dimension, autocorrelation length, texture aspect ratio and entropy) as a function of magnification we can quantify the electron microscopy image of the microstructure. We show that the plasma–microstructure interaction leads to an increase in autocorrelation length, texture aspect ratio and entropy for the optimum AZO ceramic sputtering target sintered at 1200°C. Furthermore, a maximum reduction in fractal dimension span (as determined by exponential regression) is also observed for 1200°C. In addition to the evaluation of plasma effects on sintering, our approach can provide a window towards understanding the underlying thin film growth mechanisms. We believe that this technique can be applied to the defect characterisation of a wide range of polycrystalline ceramic sputtering targets (e.g. ITO, CZTS, GAZO and so on) with the ultimate goal of improving the magnetron sputtering process and the resulting functional thin film. Lay Description Magnetron sputtering allows scientists to make functional thin films on the order of the nanoscale. In this technique, atoms are plucked from a ‘target’ then placed onto a substrate forming a thin nanometric film: all thanks to magnets, a special power supply and the fourth state of matter (plasma). Understanding what is going on and how to make a ‘good’ thin film is important for making better light emitting diodes, solar cells and light sensors. Scientists use electron microscopy to see what is going on in the microstructure of the sputtered thin films to fine tune the sputtering recipe. Here, for the first time, we have applied electron microscopy to see the surface of the microstructure before and after magnetron sputtering. This will help us understanding the plasma–microstructure interaction allowing us to make more informed decisions when fine‐tuning the sputtering process to get improved thin films. This is a case study of aluminium‐doped zinc oxide (AZO) target that could potentially replace indium tin oxide (ITO), which is widely used as a tra...

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

“…Aluminium‐doped zinc oxide ceramic sputtering target consisting of 98% w/w ZnO submicron precursor with 2% w/w Al 2 O 3 nanopowder (

\sim 8 0 normalnm

) has been fabricated via multistep pressureless sintering at 1100°C, 1200°C and 1300°C, as detailed in our previous work (Rajabi Kalvani et al ., 2020).…”

Section: Methodsmentioning

confidence: 99%