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▲ [13a-PA3-30] Selective growth and micro patterning of SrRuO3/Ba0.6Sr0.4TiO3/SrRuO3 hetero-epitaxial grown film capacitor by water lift-off process
Keywords:Selective and hetero epitaxial growth, water lift off, micro patterning
[Introduction]
Regarding the miniaturization and high performance of the devices, the microfabrication technology is increasingly important. Generally, oxide is difficult to be etched. It is not easy to establish industrially suitable processing technology. Meanwhile we have developed the water lift off (WLO) process using deliquescence of amorphous calcium oxide (a-CaO) to selectively grow the oxide film at high temperatures.
In this study, we would like to demonstrate selective growth and micro-patterning of hetero-epitaxial oxide films to create film capacitor structure by WLO process. To do so, we have been preparing the capacitor structures of SrRuO3(SRO)/Ba0.6Sr0.4TiO3 (BST)/SRO film capacitor on (100) SrTiO3 (STO) substrate through WLO process.
[Experimental]
Firstly, photoresist was coated and patterned on the STO substrate by photolithography. Then a-CaO film was deposited at room temperature by pulsed laser deposition (PLD) method. After that, a-CaO film was patterned by lift-off using acetone solution. The following was deposition of SRO and BST thin films on (100) STO by PLD, then deposited oxide films were patterned by WLO process using ultra-pure water.
[Results and discussion]
Fig 1, the a-CaO residu was not observed after WLO process. Squared BST films and SRO top and bottom electrodes with size of 20µm in width were successfully created on the STO substrate. This result shows that selective growth of each oxide films can be realized by WLO process.
Fig 2, although weak peak of (110) orientation of SRO and BST were appeared, highly preferred (100) and (200) orientation of SRO and BST films were observed. Micro-patterned SRO and BST films have been hetero-epitaxially grown on (100) STO substrate successfully. Our results suggest that WLO process is possible to realize selective and hetero-epitaxial growth of oxide films.
Regarding the miniaturization and high performance of the devices, the microfabrication technology is increasingly important. Generally, oxide is difficult to be etched. It is not easy to establish industrially suitable processing technology. Meanwhile we have developed the water lift off (WLO) process using deliquescence of amorphous calcium oxide (a-CaO) to selectively grow the oxide film at high temperatures.
In this study, we would like to demonstrate selective growth and micro-patterning of hetero-epitaxial oxide films to create film capacitor structure by WLO process. To do so, we have been preparing the capacitor structures of SrRuO3(SRO)/Ba0.6Sr0.4TiO3 (BST)/SRO film capacitor on (100) SrTiO3 (STO) substrate through WLO process.
[Experimental]
Firstly, photoresist was coated and patterned on the STO substrate by photolithography. Then a-CaO film was deposited at room temperature by pulsed laser deposition (PLD) method. After that, a-CaO film was patterned by lift-off using acetone solution. The following was deposition of SRO and BST thin films on (100) STO by PLD, then deposited oxide films were patterned by WLO process using ultra-pure water.
[Results and discussion]
Fig 1, the a-CaO residu was not observed after WLO process. Squared BST films and SRO top and bottom electrodes with size of 20µm in width were successfully created on the STO substrate. This result shows that selective growth of each oxide films can be realized by WLO process.
Fig 2, although weak peak of (110) orientation of SRO and BST were appeared, highly preferred (100) and (200) orientation of SRO and BST films were observed. Micro-patterned SRO and BST films have been hetero-epitaxially grown on (100) STO substrate successfully. Our results suggest that WLO process is possible to realize selective and hetero-epitaxial growth of oxide films.