Design, Fabrication and Characterization of a Microwave Resonator ...

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4 Fabrication and Measurement SetupCleaning the substratesThe substrates were ultrasonic-cleaned in each of the following solvents:• Acetone technical• Acetone p.a.• IsopropanolSputtering NiobiumAfter the cleaning process, the substrates are ready to be sputtered with Niobium. Theyare screwed into a specially designed carrier in order deposit Niobium on both sides of thesubstrate for CBCPW, without scratching the Niobium layer.The carrier is then placed in the sputtering chamber and positioned in front of the desiredtarget, in our case Niobium.The sputtering is done with the following parameters:• process pressure: ≈ 2.7 · 10 −3 mbar• argon flow rate: 10 sccm/min• power: 200 W• duration: 5 min + presputtering 60 sDuring presputtering the power stabilizes. With these sputtering parameters we achieve alayer thickness of 200 nm.Spincoat the resistIn the cleanroom the substrate coated with Niobium is cleaned again as describedabove, in order to remove eventually captured particles (e.g. dust). After this, the sample isspincoated with photo resist (AZ 5214E, Microchemicals 2 ). The spin coating is done with4000 rpm for 40 seconds, resulting in a resist thickness of 1.4 µm.Afterwards, the sample is baked for 120 seconds at 110 ◦ C (soft bake) to improve theadhesion of the resist.Mask exposureThe UV-exposure is done with the mask aligner (MJB3, Karl Süss GmbH). Themask is carefully cleaned under flowing acetone and isopropanol and placed in themask holder. The substrate is aligned with the desired resonator structure.We used the high precision modus to have optimum accuracy of the structure on thesample. The samples are exposed with UV radiation for 4 seconds.2 www.microchemicals.com32
4.2 Measurement SetupDevelop ResistThe areas exposed to UV light are then removed in a developer - water solution for2 minutes (developer : H 2 0 = 1 : 1).After development, any developer remaining on the sample is washed away in a waterbath. At the end of this step the coarse structures of the resonator are clearly visible by eye.The samples were always checked under the microscope to see if the optical lithographyprocess was successful and all structures were developed completely. If we were not satisfiedwith the result the sample was cleaned, spincoated and exposed again.Etching and Ashing in RIEWe used an ”Oxford Plasma Lab 80 Plus” Reactive Ion Etching machine. The frequency forproducing the Ion-Plasma is 13.56 MHz. The other parameters are:parameters physical etching ashingduration: 2:00 min 3:00 minflow rates:Ar: 10.0 sccm/min 0 sccm/minSF 6 : 20.0 sccm/min 0 sccm/minO 2 : 0 sccm/min 50.0 sccm/minN 2 :0 sccm/minHe backing:10.0 sccm/minRF forward power: 100 W 100 WICP forward power: 50 W 0 Wchamber pressure: 15 mTorr 30 mTorrtemperature:20 ◦ CTable 4.1: Parameters used in the RIE process.We decided to go for physical etching due to an improvement of the resolution of ourstructures in contrast to the also available chemical etching.After the last step the resonator is cooked in acetone to remove remaining resist andis cleaned again. Now the device is ready for testing and mounted into the measurementsetups.4.2 Measurement SetupThe fabricated devices (Device under test, DUT) were tested in different boxes in the cryostat(described in detail in Figure 4.3):The PCB box was designed by Stefan Nimmrichter in his internship at the Walther-Meißner-Institut.Here, the resonators are glued to a PCB and connected via bonding wires.The Hybrid box was designed and used by Andreas Emmert, a former Diploma studentdesigned originally for CPW hybrids [5]. The connection between the connector pinsand the taperline was established with a droplet of silver glue.33
Page 4 and 5: Contents5.2.3 R27 on Silicon . . .
Page 6 and 7: 1 Motivation and Outlinethe antinod
Page 8 and 9: 2 Theoretical Description of a CPW
Page 14: 2 Theoretical Description of a CPW
Page 19 and 20: 2.2 Including Superconductivity in
Page 21 and 22: 2.2 Including Superconductivity in
Page 23 and 24: 2.3 Microwave Resonators2.3.2 Quali
Page 25 and 26: 2.3 Microwave ResonatorsFigure 2.11
Page 27 and 28: 2.3 Microwave ResonatorsFigure 2.13
Page 29 and 30: 2.4 The Scattering MatrixThe first
Page 31 and 32: 3 Designs Procedure for the Resonat
Page 33 and 34: 3.3 ConnectorsFigure 3.1: Coupling
Page 35: 4 Fabrication and Measurement Setup
Page 39 and 40: 4.2 Measurement SetupFigure 4.3: Me
Page 41 and 42: 4.3 Calibration4.3 CalibrationIn or
Page 43 and 44: 5 MeasurementsThe first part of thi
Page 45 and 46: 5.1 First Experimentsname design W
Page 47 and 48: 5.2 Measurements - Design 1Figure 5
Page 49 and 50: 5.2 Measurements - Design 1The adva
Page 51 and 52: 5.2 Measurements - Design 15.2.2 R2
Page 53 and 54: 5.2 Measurements - Design 1Figure 5
Page 55 and 56: 5.3 Measurements - Yale DesignFigur
Page 57 and 58: 5.3 Measurements - Yale DesignFigur
Page 59 and 60: 5.4 Measurement - Design 2: R36 on
Page 61 and 62: 5.5 Discussion of the Experimental
Page 63 and 64: 5.5 Discussion of the Experimental
Page 65 and 66: 6 SimulationsThis chapter gives a b
Page 67 and 68: 6.1 Simulations in SonnetFigure 6.4
Page 69 and 70: 6.1 Simulations in SonnetFigure 6.5
Page 71 and 72: 6.2 Simulations Done at the Institu
Page 73 and 74: 7 Conclusion and OutlookThree centr
Page 75 and 76: A Specimen OverviewDesigns for Rose
Page 77 and 78: B Masks73
Page 79 and 80: B.2 Mask for Probing StationB.2 Mas
Page 81 and 82: Bibliography[1] INFORMATIK: Quanten
Page 83 and 84: List of Figures2.1 Different realiz
Page 85 and 86: List of Figures6.6 Forward and back
Page 87 and 88:
List of Tables2.1 Values where (2.1
Page 89:
DanksagungVor allem möchte ich mic
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Design, Fabrication and Characterization of a Microwave Resonator ...

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