Lithuanian Journal of Physics article / Lietuvos fizikos žurnalo straipsnis

CHARACTERIZATION OF SILICON NITRIDE LAYERS DEPOSITED IN THREE-ELECTRODE PLASMA-ENHANCED CVD CHAMBER
Tomas Grigaitis^a, Arnas Naujokaitis^a, Saulius Tumėnas^b, Giedrius Juška^a, and Kęstutis Arlauskas^a
^aDepartment of Solid State Electronics, Vilnius University, Saulėtekio 9, LT-10222 Vilnius, Lithuania
E-mail: tomasgrigaitis@gmail.com
^bDepartment of Optoelectronics, Center for Physical Sciences and Technology, A. Goštauto 11, LT-01108 Vilnius, Lithuania

Received 16 December 2014; revised 1 February 2015; accepted 20 March 2015

Two series of amorphous silicon nitride films were deposited using a chemical vapour deposition (CVD) reactor with two and three electrodes. Nitrogen gas and silane diluted with argon mixture (5% SiH₄ + 95% Ar) were used as the working gas. The silicon nitride films were deposited at the same time on CaF₂ and aluminium-coated glass substrates at 300 °C. Changing of the injected gas ratios allowed us to shift the band gap of the films in the 1.85–5.15 eV range. From AFM analysis it was found that the samples deposited in a three-electrode chamber demonstrated lower surface roughness. The electrical measurements revealed that the samples deposited in the three-electrode CVD reactor demonstrated lower leakage current and higher breakdown voltage. The composition of layers was investigated using energy-dispersive X-ray (EDS) and Fourier transform infrared (FTIR) spectroscopies. Additionally, the composition of the deposited films was evaluated from the refractive indexes, which have been estimated by fitting the spectroscopic ellipsometry data using the Tauc–Lorenz model.

Keywords: silicon nitride, plasma deposition, CVD, EDS, FTIR
PACS: 61.43.Er, 81.15.Gh, 85.40.Sz

TRIJŲ ELEKTRODŲ PE CVD KAMEROJE UŽAUGINTŲ SILICIO NITRIDO SLUOKSNIŲ TYRIMAS

Tomas Grigaitis^a, Arnas Naujokaitis^a, Saulius Tumėnas^b, Giedrius Juška^a, Kęstutis Arlauskas^a
^aVilniaus universiteto Kietojo kūno elektronikos katedra, Vilnius, Lietuva
^bFizinių ir technologijos mokslų centro Optoelektronikos skyrius, Vilnius, Lietuva

Silano ir argono (5 % SiH4, 95 % Ar) dujų mišiniai bei azoto dujos buvo naudojami silicio nitrido sluoksnių gamybai dviejų ir trijų elektrodų cheminio garų nusodinimo (CVD) kamerose. Sluoksniai buvo formuojami tuo pačiu metu ant CaF₂ kristalo ir aliuminiu padengto stiklinio padėklo, įkaitintų iki 300 °C. Keičiant injektuojamų dujų santykį silicio nitrido draustinės juostos tarpas kito nuo 1,85 eV iki 5,15 eV. Atominės jėgos mikroskopu nustatyta, kad trijų elektrodų kameroje užaugintų bandinių paviršiaus nelygumas mažesnis. Elektriniai matavimai atskleidė, kad trijų elektrodų kameroje užauginti sluoksniai pasižymi mažesne nuotėkio srove ir aukštesne pramušimo įtampa. Silicio nitrido sudėtis buvo tiriama Rentgeno spindulių dispersijos (EDS) ir Furje spektrometrijos (FTIR) metodais. Naudojant elipsometrinę spektroskopinę analizę ir taikant Tauco–Lorenzo modelį įvertinti sluoksnių lūžio rodikliai, kurie leido nustatyti silicio nitrido sluoksnio sudėtį.

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