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LabAdviser/Technology Research/Fabrication of Hyperbolic Metamaterials using Atomic Layer Deposition/TiO2 Q plates: Difference between revisions

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'''Feedback to this page''': '''[mailto:labadviser@nanolab.dtu.dk?Subject=Feed%20back%20from%20page%20http://labadviser.nanolab.dtu.dk/index.php/LabAdviser/Technology_Research/Fabrication_of_Hyperbolic_Metamaterials_using_Atomic_Layer_Deposition/TiO2_Q_plates click here]'''
<i>This page is written by <b>Evgeniy Shkondin @DTU Nanolab</b> if nothing else is stated. <br>
All images and photos on this page belongs to <b>DTU Nanolab</b> and <b>DTU Electro</b> (previous DTU Fotonik).<br>
The fabrication and characterization described below were conducted in <b>2013-2016 by Evgeniy Shkondin, DTU Nanolab</b>.<br></i>
====Procces flow description====
====Procces flow description====


A 500 μm-thick wafer of silica (SiO<sub>2</sub>) goes through RCA clean and low-pressure chemical vapor deposition (LPCVD) (furnace from Tempress) based on SiH<sub>4</sub> (silane) at 560<sup>◦</sup>C to form a layer of 300 nm of amorphous silicon (Si) [Fig. 1]. The back side of deposited Si was etched using KOH wet etch. In order to remove residues from the etching process, it was performed oxygen plasma cleaning. A CSAR resist was spin-coated to the thickness of 150 nm, followed by exposure of Electron Beam Lithography (EBL) (JEOL JBX-9500 Electron-beam) generating a mask with concentric ring patterns. After development, the wafer was submitted to advanced silicon etch (ASE). To form the trenches of the TiO<sub>2</sub> structures, a thin film of TiO<sub>2</sub> was deposited using the ALD technique in a hot-wall system (Picosun R200), working with 2000 cycles at 150<sup>◦</sup>C [Fig.1]. The precursors used were titanium tetrachloride (TiCl<sub>4</sub>) and H<sub>2</sub>O (supplied by Strem Chemicals Equipment). The process was followed by Ar<sup>+</sup> ion beam etching (IBE) on both sides of the wafer to remove excess of ALD deposited material. At the top most TiO<sub>2</sub> layer the physical sputtering of the sample using Ar<sup>+</sup> ions was performed in order to get access to Si core. On the backside, the Ar<sup>+</sup> ions were used to remove the deposited TiO<sub>2</sub>. Finally, we performed a reactive ion etch on silicon, leaving only the TiO<sub>2</sub> structures. The final system comprehends a base of SiO<sub>2</sub> with nano-structures of TiO<sub>2</sub> on it. Figure 2 shows the image of the system taken using scanning electron microscope (SEM) and conventional optical microscope. Figure 3 illustrates SEM cross-sectional image of the prepared Q-plate.
A 500 μm thick wafer of silica (SiO<sub>2</sub>) goes through RCA clean and low-pressure chemical vapor deposition (LPCVD) (furnace from Tempress) based on SiH<sub>4</sub> (silane) at 560<sup>◦</sup>C to form a layer of 300 nm of amorphous silicon (Si) [Fig. 1]. The back side of deposited Si was etched using KOH wet etch. In order to remove residues from the etching process, it was performed oxygen plasma cleaning. A CSAR resist was spin-coated to the thickness of 150 nm, followed by exposure of Electron Beam Lithography (EBL) (JEOL JBX-9500 Electron-beam) generating a mask with concentric ring patterns. After development, the wafer was submitted to advanced silicon etch (ASE). To form the trenches of the TiO<sub>2</sub> structures, a thin film of TiO<sub>2</sub> was deposited using the ALD technique in a hot-wall system (Picosun R200), working with 2000 cycles at 150<sup>◦</sup>C [Fig.1]. The precursors used were titanium tetrachloride (TiCl<sub>4</sub>) and H<sub>2</sub>O (supplied by Strem Chemicals Equipment). The process was followed by Ar<sup>+</sup> ion beam etching (IBE) on both sides of the wafer to remove excess of ALD deposited material. At the top most TiO<sub>2</sub> layer the physical sputtering of the sample using Ar<sup>+</sup> ions was performed in order to get access to Si core. On the backside, the Ar<sup>+</sup> ions were used to remove the deposited TiO<sub>2</sub>. Finally, we performed a reactive ion etch on silicon, leaving only the TiO<sub>2</sub> structures. The final system comprehends a base of SiO<sub>2</sub> with nano-structures of TiO<sub>2</sub> on it. Figure 2 shows the image of the system taken using scanning electron microscope (SEM) and conventional optical microscope. Figure 3 illustrates SEM cross-sectional image of the prepared Q-plate .




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|-
|-
!1.1
!1.1
|RCA clean
|RCA clean.
|Before Si deposition in LPCVD furnace, the quartz (fused silica) wafers need to be cleaned
|Before Si deposition in LPCVD furnace, the quartz (fused silica) wafers need to be cleaned
|[[Specific_Process_Knowledge/Wafer_cleaning/RCA| RCA]]
|[[Specific_Process_Knowledge/Wafer_cleaning/RCA| RCA]]
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|- style="background:#BCD4E6; color:black"
|- style="background:#BCD4E6; color:black"
!1.2
!1.2
|Low-Pressure Chemical Vapour Deposition (LPCVD) of Si
|Low-Pressure Chemical Vapour Deposition (LPCVD) of Si.
|LPCVD deposition of 300 nm amorphous Si
|LPCVD deposition of 300 nm amorphous Si
|[[Specific_Process_Knowledge/Thin_film_deposition/Furnace_LPCVD_PolySilicon| 6" LPCVD polysilicon furnace (E2)]].  
|[[Specific_Process_Knowledge/Thin_film_deposition/Furnace_LPCVD_PolySilicon| 6" LPCVD polysilicon furnace (E2)]].  
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|-
|-
!1.3
!1.3
|Si anisotropic wet etch  
|Si anisotropic wet etch.
|Removal of the Si from the back side of the wafer.
|Removal of the Si from the back side of the wafer.
| [[Specific_Process_Knowledge/Etch/KOH_Etch|KOH]].
| [[Specific_Process_Knowledge/Etch/KOH_Etch|KOH]].
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|- style="background:#BCD4E6; color:black"
|- style="background:#BCD4E6; color:black"
!1.4
!1.4
|Plasma surface treatment
|Plasma surface treatment.
|To ensure that all organic remainings are gone, wafer is treated by O<sub>2</sub>/N<sub>2</sub> plasma. (Optional step)
|To ensure that all organic remainings are gone, wafer is treated by O<sub>2</sub>/N<sub>2</sub> plasma. (Optional step)
|
|
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|-
|-
!1.5
!1.5
|E-Beam Lithography (EBL)
|E-Beam Lithography (EBL).
|Spin-coating of CSAR resist to the thickness of 150 nm, followed by e-beam exposure.
|Spin-coating of CSAR resist to the thickness of 150 nm, followed by e-beam exposure.
|
|
[[Specific_Process_Knowledge/Lithography/EBeamLithography/JEOL_JBX-9500FSZ|JEOL JBX-9500 Electron-beam]]  
[[Specific_Process_Knowledge/Lithography/EBeamLithography/JEOL_9500_User_Guide|JEOL JBX-9500 Electron-beam]]  
<br clear="all" />
<br clear="all" />
|[[image:Image2_ebeam_on_Si.jpg|250x350px|center]]
|[[image:Image2_ebeam_on_Si.jpg|250x350px|center]]
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|- style="background:#BCD4E6; color:black"
|- style="background:#BCD4E6; color:black"
!1.6
!1.6
|Advanced Silicon Etching
|Advanced Silicon Etching.
|Creating sacrificial silicon template.
|Creating sacrificial silicon template.
|
|
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|-
|-
!1.7
!1.7
|Scanning Electron Microscopy inspection
|Scanning Electron Microscopy inspection.
|The fabricated template inspects by SEM
|The fabricated template inspects by SEM
|
|
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|- style="background:#BCD4E6; color:black"
|- style="background:#BCD4E6; color:black"
!1.8
!1.8
|Plasma surface treatment
|Plasma surface treatment.
|To ensure that all organic remainings are gone, template is treated by O<sub>2</sub>/N<sub>2</sub> plasma. (Optional step)
|To ensure that all organic remainings are gone, template is treated by O<sub>2</sub>/N<sub>2</sub> plasma. (Optional step)
|
|
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|-
|-
!1.9
!1.9
|Atomic Layer Deposition (ALD) of TiO<sub>2</sub>
|Atomic Layer Deposition (ALD) of TiO<sub>2</sub>.
|Deposition carried at 150C.Thickness is approx. 90 nm.
|Deposition carried at 150C.Thickness is approx. 90 nm.
||Equipment used: [[Specific_Process_Knowledge/Thin_film_deposition/ALD_Picosun_R200|ALD Picosun R200]]. Standard recipe used: [[Specific_Process_Knowledge/Thin_film_deposition/ALD_Picosun_R200/TiO2_deposition_using_ALD#TiO2_deposition_on_trenches| TiO2T]] .
||Equipment used: [[Specific_Process_Knowledge/Thin_film_deposition/ALD_Picosun_R200|ALD Picosun R200]]. Standard recipe used: [[Specific_Process_Knowledge/Thin_film_deposition/ALD_Picosun_R200/TiO2_deposition_using_ALD#TiO2_deposition_on_trenches| TiO2T]] .
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|-
|-
!1.11
!1.11
|Scanning Electron Microscopy inspection
|Scanning Electron Microscopy inspection.
|SEM inspection of ALD deposition and IBE etching.
|SEM inspection of ALD deposition and IBE etching.
|
|
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|-
|-
!1.13
!1.13
|Scanning Electron Microscopy inspection of fabricated structure.
|Scanning Electron Microscopy inspection.
|Proof of final result.
|Proof of final result.
|
|
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