Carburo di Silicio: materiale semiconduttore a larga gap per rispondere alla crescente

domanda di energia.

Sviluppo di tecnologie per una microelettronica a base di carburo di siliciopresso il CNR‐IMM UOS di Bologna.

Dott.ssa Roberta Nipotihttps://www.bo.imm.cnr.it/site/node/797

Giovedì 6 marzo 2014 – ore 16.30Aula Newton – Edificio di Fisica

La sorgente delle informazioni contenute in questa presentazione è indicata pagina per pagina . L’assenza di tale indicazione significa che le informazioni contenute nella pagina sono originali oppure già pubblicate in un articolo a firma della relatrice, di tali articoli è allega la lista dal 2013 ad oggi. Ogni utilizzo delle informazioni contenute in questa presentazione dovrà riportare la corretta origine delle stesse.

Carburo di Silicio: materiale semiconduttore a larga gap per rispondere alla crescente domanda di energia.

Sviluppo di tecnologie per una microelettronica a base di carburo di siliciopresso il CNR‐IMM UOS di Bologna.

Dott.ssa Roberta Nipoti

http://www.adsadvance.co.uk/raytheon‐achieves‐uk‐first‐with‐opening‐of‐new‐silicon‐carbide‐foundry.html

0.75 nm

1 nm

1.5 nm

3.23 3.0 2.36 eV band‐gap4H‐SiC 6H‐SiC 3C‐SiC

polytypism

http://www.nanoclub.tw/research/SiC_on_Si/SiC_on_Si_wafer_materials.htm

http://kids.britannica.com/comptons/art‐57434/When‐white‐light‐is‐spread‐apart‐by‐a‐prism‐or

negligible intrinsic carrier concentration

good for a high temperature microelectronics

http://www.ioffe.ru/SVA/NSM/Semicond/SiC/

SiC is good for a robust power electronicsand for harsh environment devices

Modern society is increasingly dependentupon electrical appliances for comfort, transportation, and healthcare, motivating great advances in power generation, power distribution and power management technologies. These advancements owe their allegiance to enhancements in the performance of power devices that regulate the flow of electricity.

B. Jayant BaligaFundamentals of Power Semiconductor Devices2008 (edition with 4H‐SiC news)

Humanity’s Top Ten Problemsfor next 50 years

1. ENERGY2. WATER3. FOOD4. ENVIRONMENT 5. POVERTY6. TERRORISM & WAR7. DISEASE8. EDUCATION9. DEMOCRACY10. POPULATION

2003 6.3 Billion People2050 8-10 Billion People

R. E. Smalley, Nobel Laureate for Chemistry 1996, Rice Universityhttp://en.wikipedia.org/wiki/Richard_Smalley

2008 – 14 Terawatt2050 – 25-30 Terawatt

courtesy of prof. Svensson

ICSCRM2013, Miyazaki , Sept. 29 ‐ Oct. 4, 2013, courtesy of prof. Matsunami

http://www.adsadvance.co.uk/raytheon‐achieves‐uk‐first‐with‐opening‐of‐new‐silicon‐carbide‐foundry.html

CNR ‐ IMM ‐ UOS di Bologna

12

ion implantation

n

pn/p junction

n bulkp doping

n

pn/p junction

p dopingn bulk

chemical deposition + thermal “drive-in”

p dopingn/p junction

n

p

n bulk

RIE + epitaxy + etching

Selected area doping

Measured and computed depth profilesof implanted Al in 4H‐SiC

Good control (≤ 10%) of the fluence (ions cm-2), or total amount of implanted atoms

using multiple implants and different doses, one has a large degree of freedom in designing ion depth profiles

The interplay of channeling and dechanneling

Trajectories of ions movingthrough a crystal maybe random(1), channeled (2), or they maybechanneled at the beginning, thenare dechanneled and becomerandom (3), or, just the oppositeway, i.e. they start as random andthen may become channeledafterwards (4), even along adirection not perpendicular to thesurface. The occurrence andrelative abundance of (1)-(4)events changes with changing thebeam-lattice orientation. Lookingat the depth distribution profile ofions we can observe thecontributions of all these differentpaths.,

(1)

(2)

(3)

(4)

https://www.bo.imm.cnr.it/users/lulli/didattica/index.html

0.0 2.0 4.0 6.0

0.0 2.0 4.0 6.0

–2.0

–1.5

–1.0

–0.5

0.0

dept

h (

m)

1015

1016

1017

1018

1019

1020

SiO2

lateral position ( m)

1019

1018

1017

1016

2D simulation allows to evaluate the phenomenon of lateral under-maskpenetration, which in this case is rather pronounced and may haveconsequences on the electrical behavior of the final device.

G. Lulli, IEEE TRANSACTIONS ON ELECTRON DEVICES 58(1) (2011) 190‐194

il cristallo 4H‐SiC è trasparente alla luce visibile eccetto che nelle aree impiantate dove la luce è assorbita perché l’ordine cristallino

è stato distrutto dal bombardamento degli ioni

Applications: Implantation annealing

Features: Up to 50 mm wafersPyrometer temperature controlAtmospheric and vacuum process capabilityOne purge gas lineUp to 6 gas lines with MFCPC controlVacuum valve and vacuum gauge

Performance: Temperature range: 700°C to 2000°CRamp rate: up to 40°C/s

The Jipelec SiC Furnace has been developed for the rapid thermal annealing process of silicon carbide wafers up to 2000°C.

Modified by IMM‐UOS of Bologna

Resistivity of Al+ implanted 4H‐SiC materials forConventional (CA) and microwave (MWA) annaling: RT data

2000°C MWA and 1950°C CA samples have comparableresistivity values over a large range of implanted Al+concentrations.

This allows us to hypothesizethat for MWA as for CA, the key parameter for the electrical activation of implanted Al+ is the temperature.

Hollow symbols are literature data (Bluet, Negoro, Kimoto, Heera, etc.) Full grey and red symbols are authors’ data (Nipoti et al. JMR 2013 and Apex 2011)

Silicon sublimation and step bunching are supressed by usinga pyrolised resist film (C‐cap)

Atomic Force Microscopy by Cristiano Abonetti

transport characterization of Al+ implanted 4H‐SiC materials

5 mm

Sheet resistance temperature range 10 -700 K

Hall effect 140-700 K

Magnetic field intensity 8000 – 10000 Gauss

HPSI 4H-SiC<0001> 8° off-axis

Si-face

implanted Al+ ion

van der Pauw device

x = 0.36 - 0.39 m

Timpl 400°C

MWA 2000°C/30 sCA 1950°C/5min

C-cap removedby 850°C/15min O2

rms = 0.5 – 2.3 nm

Ti/Al ohmic contacts of not negligible dimension: correction factors

Main features include: current source: 1 nA‐ 100 mA (Keithley 220)magnetic field: 1 Tresistivity range: 10‐4 to 106 Ω.cmTemperature: 273 ‐563 Kcustom software

Hall Effect System

Hall effect system0.8 T

10K ‐ RT

Dipartimento di FisicaUniversità di Parma

Prof. Antonella Parisini

Temperature dependence of the resistivity

Resistivity = measured sheet resistance x thickness of the implanted layer by SRIM2008

Main results:

i) A semiconductor behavior is preserved up to the higher implanted Al concentration of 5 × 1020 cm‐3 because the temperature coefficientis always positive.

ii) an implanted Al concentration of 1.5 × 1020 cm‐3 is sufficient to obtain a p‐type material resistivity in the high 10‐2 Ωcm range at room temperature

2000°C/30s MWAAl implanted concentration in the inset

Temperature dependence of the hole density and mobility in Al+implanted and 4H‐SiC

Arrows indicate the direction of increasing implanted Al concentrationfrom 5 x 1019 cm‐3 to 5 x 1020 cm‐3

2000°C/30s 1950°C/5min

Temperature dependence of the hole density and mobility in Al+implanted and 4H‐SiC

Arrows indicate the direction of increasing implantedAl concentration from 5 x 1019 cm‐3 to 5 x 1020 cm‐3

2000°C/30s

Main results:iii) the temperature coefficients of hole density and hole mobility Arrhenius plots feature a hole transport through intra band states around RT for Al implanted concentration > 3 × 1020 cm‐3

iv) an implanted Al concentration of 1.5 × 1020 cm‐3 is sufficient to obtain a hole density of about 1019 cm‐3 at RT

in progress:Transmission Electron Microscopy

potentially:X‐ray Diffractometry

https://www.bo.imm.cnr.it/site/facilities?q=node/379

Analysis of the hole transport through valence band states in heavy Al doped 4H‐SiC by ion implantationA. Parisini and R. NipotiJ.Appl.Phys.(2013)

1950°C/5min

Diodi p+‐i‐n 4H‐SiC verticali con anodo impiantato Al+

2 cm

Ti/Al contact 2rmetal

Anode 2ran Al 1.5 x 1020 cm‐3

Epi‐layer 25 m n‐type 5 x 1015 cm‐3

Cathode

Ni contact

Standard photo‐lithography for diodes processing

C‐cap and 2000°C/30s MWA

Wafer‐Level Parametric Characterization System

‐ temperature controlled chuck Temptronic TP315B (5” chuck, Tchuck <= 300 °C)‐ current floor 2 x 10‐15 A ‐ max voltage 210 V

n-

n+

p+

Ni

Al/Ti

Forward current –voltagecharacteristic

S. Bellone et al. , IEEE Trans. on Power Electron., Vol. 26, n. 10, pp. 2835−2843 (2011)

Forward current –voltage characteristic

The Arrhenius plot of the zero voltagesaturation current for n= 2 shows a thermal activation energy of 1.7 eV. This feature of theI‐V curves may be attributed to carrierrecombination in the space charge region on defects that had to be very near to the 4H‐SiC mid‐gap, namely the EH7 center, recentlybeing identified as a negative‐U center of thecarbon vacancy .

Reverse current –voltage characteristic

Clearly, two different thermal activation energies can be extracted for the two different families of diodes. Whereas the diode family annealed at 1650°C exhibits a defect with an activation energy of approximately 0.72eV below the conduction band, the diode family annealed at 1950°C shows evidence for a defect with an activation energy of 0.11eV below the conduction band.

In progress:

simulation of SiC p‐i‐n diodes

Dipartimento di Ingegneria ElettronicaUniversità di Parma

Dott.ssa Giovanna Sozzi

Peer reviewed articles in 20131. A. Parisini and R. Nipoti, Analysis of the hole transport throught valence band states in

heavy Al doped 4H‐SiC by ion implantation, J. Appl. Phys. 114, 243703 (2013), doi: 10.1063/1.4852515

2. L. Di Benedetto, G.D. Licciardo, R. Nipoti, and S. Bellone, On the Crossing‐point of 4H‐SiC Power Diodes Characteristics, IEEE Electron Device Letters, doi: 10.1109/LED.2013.2294078

3. R. Nipoti, F. Moscatelli, and P. De Nicola, Al+ implanted 4H‐SiC p+‐i‐n diodes: forward current negative temperature coefficient, IEEE Electron Device Letters, Vol. 34, Issue 8 (2013) 966‐968, doi: 10.1109/LED.2013.2269863

4. F. Pezzimenti, S. Bellone, F.G. Della Corte, and R. Nipoti , Steady‐state simulation of a normally‐off 4H‐SiC trench bipolar mode FET, Materials Science Forum 740‐742 (2013) pp 942‐945, doi: 10.4028/www.scientific.net/MSF.740‐742.942, proceedings of the ECSCRM2012, Saint Petersburg September 2‐7, 2012

5. R. Nipoti, A. Hallén, A. Parisini, F. Moscatelli, and S. Saggio, Al + implanted 4H‐SiC: improved electrical activation and ohmic contacts, Materials Science Forum 740‐742 (2013) pp 767‐772, doi: 10.4028/www.scientific.net/MSF.740‐742.767, proceedings of the ECSCRM2012, Saint Petersburg September 2‐7, 2012

6. R. Nipoti, R. Scaburri, A. Hallén, and A. Parisini, Conventional thermal annealing for a more efficient p‐type doping of Al + implanted 4H‐SiC, J. Mater. Res. 28(1) (2013) 17‐22, DOI: 10.1557/jmr.2012.207

1. A. Nath, Mulpuri V. Rao, Y‐L‐ Tian, A. Parisini, and R. Nipoti, Microwave annealing of high dose Al+ implanted 4H‐SiC: towards device fabrication, J. Electr. Mater.(accepted on December 31, 2013) doi: 10.1007/s11664‐013‐2973‐5

2. N.A. Mahadik, R.E Stahlbush, A. Nath, M.J. Tadjer, E.A. Imoff, B.N. Feygelson, and R. Nipoti, Post‐growth Reduction of Basal Plane Dislocations by High Temperature Annealing in 4H‐SiC Epilayers, Mater. Sci. Forum 778‐780 (2014) pp 324‐327, doi:10.4028/www.scientific.net/MSF.778‐780.324, proceedings of the ICSCRM2013, Miyazachi, September 29 ‐ October 4, 2013

3. A. Nath, A. Parisini, Y‐L‐ Tian, Mulpuri V. Rao, and R. Nipoti, Microwave annealing of Al+ implanted 4H‐SiC: towards device fabrication, Mater. Sci. Forum 778‐780 (2014) pp 653‐656, doi:10.4028/www.scientific.net/MSF.778‐780.653, proceedings of the ICSCRM2013, Miyazachi, September 29 ‐ October 4, 2013

4. U. Grossner, F. Moscatelli, and R. Nipoti, Al+ implanted 4H‐SiC p+‐i‐n diodes: Evidence for post implantation‐annealing dependent defect activation, Mater. Sci. Forum 778‐780 (2014) pp 657‐660, doi:10.4028/www.scientific.net/MSF.778‐780.657, proceedings of the ICSCRM2013, Miyazachi, September 29 ‐ October 4, 2013

5. H.M. Ayedh, V. Bobal, R. Nipoti, A. Hallén, and B.G. Svensson, Formation of carbon vacancies in 4H silicon carbide during high temperature processing, J. Appl. Phys. 115, 012005 (2014), doi: 10.1063/1.4837996

Peer reviewed articles in 2014

CNR ‐ IMM ‐ UOS di Bologna