1. Wet Oxidation and Hydrogen Incorporation on 4H-SiC (c-face)
Can Xu1, Voshadhi Amarasinghe1, Gang Liu1, Boris Yakshinskiy1,
Sarit Dhar2, Torgny Gustafsson1, Joseph Bloch1 and Leonard Feldman1
1Institute of Advance Materials, Devices and Nanotechnology (IAMDN), Rutgers University
2Department of Physics, Auburn University

2. Motivation
Hydrogen reduces the interface defect density in Si MOS devices.
Effect on SiC?
Questions to answer:
Is there hydrogen at the interface?
Hydrogen vs. defect?
Hydrogen vs. electrical properties?
Dieter K. Schroder, Electrical Characterization of Defects in Gate Dielectrics
Water uptake during device processing
Does hydrogen go into the oxide/interface during device processing?
Does this result in a electrical degradation?

3. Effect of pyrogenic oxidation (H2+O2) on Dit & µFE
Wet oxidation: temperature Dit
M. Okamoto et al. Appl. Phys. Express 5, 2012,

4. Effect of pyrogenic oxidation (H2+O2) on Dit & µFE
Wet oxidation: temperature Dit
Post oxidation H2 anneal: Dit
M. Okamoto et al. Appl. Phys. Express 5, 2012,

5. Effect of pyrogenic oxidation (H2+O2) on Dit & µFE
Wet oxidation: temperature Dit
Post oxidation H2 anneal: Dit
Post oxidation H2 anneal: µFE
M. Okamoto et al. Appl. Phys. Express 5, 2012,

6. Effect of hydrogen anneals on Dit
Effect of H2 annealing at 500° C for Pt gated oxide
Final outcome:
NO anneal reduced higher energy defects closer to Ec
H2 anneal reduce defects deeper into the gap
NO + H2 anneal reduced the defect density throughout the eV range
S. Wang et al. PRL 98 , 2007,

7. Effect of hydrogen anneals on Dit
Effect of H2 annealing at 500° C for Pt gated oxide
Final outcome:
NO anneal reduced higher energy defects closer to Ec
H2 anneal reduce defects deeper into the gap
NO + H2 anneal reduced the defect density throughout the eV range
S. Wang et al. PRL 98 , 2007,

8. Effect of hydrogen anneals on Dit
Effect of H2 annealing at 500° C for Pt gated oxide
Final outcome:
NO anneal reduced higher energy defects closer to Ec
H2 anneal reduce defects deeper into the gap
NO + H2 anneal reduced the defect density throughout the eV range
S. Wang et al. PRL 98 , 2007,

9. Nuclear Reaction analysis (NRA)
Sensitivity to 2 x 1012 atoms/cm2 (0.1% of a monolayer)
Remove p detection
Remove Es
Remove Q =

10. Summary of “D” uptake by 4H-SiC faces vs Si
Interface D content: after annealing dry oxide in D2O at 400° C for 15 hrs
Some text
SiC
Liu et al. Appl. Phys. Lett. 106, 2015,

11. Summary of “D” uptake by 4H-SiC faces vs Si
Flat band voltage shift is proportional to the interface “D”
C-face NO
a-face O2
C-face O2
C-face Ar

12. Relationship between wet oxidation and interface “D” concentration

13. Wet oxidation Oxidation at different temp. using D2O
4H-SiC (000 1 )
4H-SiC (000 1 )
Oxidation at different temp. using D2O
Stripping oxide followed by NRA

14. Wet oxidation The less D retained at the interface during
4H-SiC (000 1 )
4H-SiC (000 1 )
Oxidation at different temp. using D2O
Stripping oxide followed by NRA
Nit ( x 1012)
The less D retained at the interface during
wet oxidation, the better Nit
D content ( x 1013 /cm3)

15. Post oxidation D2 anneal
4H-SiC (000 1 )
4H-SiC (000 1 )
4H-SiC (000 1 )
Wet oxidation at 1000° C
D2 exposure at different temp.
C-V and NRA analysis

16. Post oxidation D2 anneal
4H-SiC (000 1 )
4H-SiC (000 1 )
4H-SiC (000 1 )
Wet oxidation at 1000° C
D2 exposure at different temp.
C-V and NRA analysis
Post oxidation anneal improves the interface, and the
defect density is inversely proportional to the D amount
Nit ( x 1012)
D content ( x 1014 /cm3)

17. Temperature dependent “D” uptake by exposure to D2O from the SiO2(dry)/SiC interface

18. Temperature dependent water uptakeO D O D O D O D D D D D
4H-SiC (000 1 )
4H-SiC (000 1 )
4H-SiC (000 1 )
Stripping oxide
followed by NRA
Oxidation at 1150° C
D2O exposure at different temp.

19. Temperature dependent water uptakeO D O D O D O D D D D D
4H-SiC (000 1 )
4H-SiC (000 1 )
4H-SiC (000 1 )
Stripping oxide
followed by NRA
Oxidation at 1150° C
D2O exposure at different temp.
x wet oxidation D concentration x
850° C wet
D uptake is maximal at 700 °C x
900° C wet
1000° C wet x

20. Temperature dependent water uptakeO D O D O D O D D D D D
4H-SiC (000 1 )
4H-SiC (000 1 )
4H-SiC (000 1 )
Stripping oxide
followed by NRA
Oxidation at 1150° C
D2O exposure at different temp.
x wet oxidation D concentration x
850° C wet x
900° C wet
1000° C wet x
H passivation of Pb defect on Si(111)

21. Effect of NO passivation on “D” uptake

22. Effect of NO passivation on “D” uptake
NO passivation significantly reduce the interface “D” at the SiO2/SiC interface

23. Conclusions
Our quantification of D content with temperature, in combination with electrical measurements, suggest there is a optimum D content, hence the need to control temperature.
D uptake is maximal at 700 °C
At high temperatures: D incorporation during wet oxidation and post dry + D2O annealing similarity suggest that “D” atoms bond to similar sites.
D uptake as function of temperature is consistent with combined “up-take” and “loss” chemical processes, as previously identified for Si, but with characteristic temperatures substantially higher for SiC.

24. Questions and comments

25. Interfacial D content (c-f) vs Vfb