Tunable ion flux density and its impact on AlN thin films deposited in a confocal DC Magnetron Sputtering System

Transcription

1 Willkommen Welcome Bienvenue Tunable ion flux density and its impact on AlN thin films deposited in a confocal DC Magnetron Sputtering System XXIV. Erfahrungsaustausch Oberflächentechnologie mit Plasma- und Ionenstrahlprozessen - Mühlleithen / Vogtland, März , Maria Fischer 1, Kerstin Thorwarth 1, Sven Gauter 2, Hans Josef Hug 1, Jörg Patscheider 1 1 Empa, Laboratory for Nanoscale Materials Science, Switzerland 2 Institut für Experimentelle und Angewandte Physik, University of Kiel, Kiel, Germany

2 Outline Motivation & Introduction Results Part A: Plasma Analytics Part B: Thin Film Properties Conclusion

3 Motivation Plasma analytics Plasma control Control of thin film growth through plasma conditions Ref: A. Anders, Thin Solid Films, Volume 518, Issue 15, 31 May 2010, Pages

4 Magnetic Configuration of Single Magnetron Side View Top View Type I Balanced Type II Ref: Window, B., & Savvides, N. (1986). Journal of Vacuum Science & Technology A, 4(2), 196. Ref: CAPST, Sungkyunkwan University, Suwon, South Korea

5 Magnetic Configuration of Single Magnetron Side View Top View Type II Plasma extended towards substrate Interaction of growing film with plasma Ref: Window, B., & Savvides, N. (1986). Journal of Vacuum Science & Technology A, 4(2), 196. Ref: CAPST, Sungkyunkwan University, Suwon, South Korea

6 Confocal Dual Magnetron Sputtering Substrate Magnetrons (unbalanced) Closed Field Open Field

7 Confocal Dual Magnetron Sputtering Substrate Magnetrons (unbalanced) Closed Field Open Field

8 Confocal Dual Magnetron Sputtering Substrate Magnetrons (unbalanced) Closed Field Open Field

9 Plasma Analytics Setup In Situ Coil N 150 L 58 cm R cm B substrate 200 G

10 Plasma Analytics Setup In Situ Coil N 150 L 58 cm R cm B substrate 200 G Plasma Analytics Substrate Holder Langmuir Probe Calorimetric Probe Confocal DCMS ϕ= ϕ Ar 15 sccm (p 5µbar) P 1,2 (Al) 200 W (10W/cm 2 ) d target<->substrate 12 cm Thermocouple

11 Plasma Analytics I Substrate Holder B z = 0 G B z = 45 G Open Field Closed Field Enhancement of ion flux for both configurations Ion flux is the sum of ion flux from individual guns

12 Plasma Analytics II - Langmuir Probe Closed Field Open Field 0 5cm 0 5cm S N S N S N S N S N S N S N S S N S S N S S N S 12

13 Plasma Analytics II - Langmuir Probe Closed Field Open Field 0 5cm 0 5cm Local increase of ion flux density by more than one order of magnitude 13

14 Plasma Analytics III Calorimetric Probe Closed Field Open Field -5cm 0 5cm -5cm 0 5cm S N S N S N S N S N S N S N S S N S S N S S N S 14

15 Plasma Analytics III Calorimetric Probe Closed Field Open Field -5cm 0 5cm -5cm 0 5cm Local increase in energy flux density by more than one order of magnitude. Almost identical spatial profiles to ion current density 15

16 Plasma Analytics IV Temperature back back back Open Field, I coil = -24A I coil [A] Temperature [ C] (open field; P 1,2 (Al) = 200W) T outer T middle T inner T back

17 Motivation Why Aluminum Nitride? Hard (around 20 GPa) Wide bandgap semiconductor (6.2 ev) Optically Transparent ( nm) Piezoelectric (5.15 pm/v for d 33 )

18 AlN Thin Film Properties Setup Reactive Confocal DC Magnetron Sputtering Ar:N 2 15:12 Pressure 5 μbar Power 200 W (10W/cm 2 ) Ion to Neutral Ratio Ion Current Density Varied Parameters A/m 2 Temperature C

19 AlN Thin Film Properties

20 AlN Thin Film Properties [1] Zhi-Ye Qiu et al. (2014), DOI: /rb/rbu007 Stochiometric films Metal non-metal ratio not affected by ion bombardment Oxygen incorporation reduced for higher plasma densities Explanation: Higher reactivity of N 2 in plasma environment No Ar implantation through increased ion bombardment (<0.07 at%,rbs+erda) Low energy ion bombardment!

21 AlN Thin Film Properties with coil without coil (almost) all samples show prefered (002)-orientation

22 AlN Thin Film Properties Tensile Compressive

23 AlN Thin Film Properties 500 T [ C] nm columnar, porous dense j ion [A/m 2 ]

24 Conclusions Variation of ion flux density with additional magnetic field in confocal DCMS. j ion tunable over more than one order of magnitude Considerable influence on temperature Comparison of influence of Ion Bombardment and Temperature on AlN thin film growth (002) orientation: 100 C < T < 500 C 1 < j ion /j neutral < 30 Stress: tensile compressive with increasing j ion Microstructure: columnar, porous dense with increasing j ion

25 Outro