Physical and Electrical Properties of Yttrium Oxide Gate Dielectrics on Si Substrate with NH[sub 3] Plasma Treatment

Abstract

We report on the physical properties and electrical characteristics of Y 2 O 3 gate oxides grown on silicon substrates with NH 3 plasma treatment by reactive radio-frequency sputtering. The interfacial chemistry of the high-k gate dielectric Y 2 O 3 has been investigated on nitrided and un-nitrided Si using X-ray photoelectron spectroscopy. We found that the Y 2 O 3 gate film having NH 3 -based interface layer is very effective in reducing equivalent oxide thickness and leakage current as well as improving film qualities. This NH 3 -nitrided layer is suggested to minimize interfacial YSi x O y formation by limiting the amount of Si available to interact with the Y 2 O 3 layer. These Y 2 O 3 gate dielectrics exhibit excellent frequency dependence and weak temperature dependence of leakage current. They also show negligible charge trapping at high electric field stress.

Effects of post-deposition annealing ambient on Y2O3 gate deposited on silicon by RF magnetron sputtering

“…where A = q 3 m e 8nhm˚B (14) and B = 4(2m) 1/2˚3/2 B 3qh/2n (15) where m e is the free electron mass, m is the effective electron mass in the oxide, and h is Planck's constant. A total of five samples was fitted with FN tunneling model for each of the investigated samples.…”

“…Thus, numerous investigations have been performed to substitute the SiO 2 with high dielectric constant (k) materials, such as HfO 2 [6][7][8], Al 2 O 3 [9], ZrO 2 [10,11], CeO 2 [12], Er 2 O 3 [13,14], and Y 2 O 3 [4,. Of these high-k oxides, Y 2 O 3 is considered as one of the potential candidates for substituting SiO 2 due to its fascinating properties, such as large band gap (∼5.5 eV), large conduction band offset (∼2.3 eV), high-k value (k = 15-18), low lattice mismatch and good thermal stability with silicon [4,[15][16][17][18][19].…”

“…Deposition of Y 2 O 3 films has been done by e-beam evaporation [16,[19][20][21][22][23][24][25][26][27][28], molecular beam epitaxy [29,30], RF magnetron sputtering [31][32][33][34][35], laser ablation [36], RF sputtering [37], reactive RF sputtering [15,38], ion beam sputtering [17,36,[39][40][41], plasma-assisted chemical vapor deposition (CVD) [42,43], pulsed liquid-injection plasma-enhanced metallorganic CVD [4,44], low pressure CVD [45], atomic layer deposition [18,[46][47][48], and ionized cluster beam deposition [49,50] techniques. The quality of deposited Y 2 O 3 film may be attributed to two factors, namely crystallinity of the structure and stoichiometry of the chemical composition.…”

“…The quality of deposited Y 2 O 3 film may be attributed to two factors, namely crystallinity of the structure and stoichiometry of the chemical composition. Depending on the deposition parameters, asdeposited Y 2 O 3 films may emerge in amorphous [4,15,21,23,42,44], epitaxial [20,22,27] or polycrystalline [18,20,46,47] structure. Upto-date, literatures have reported that polycrystalline Y 2 O 3 film deposited by e-beam evaporation technique is better in MOS characteristic than epitaxial crystalline film [20] but is poorer than amorphous film [22].…”

Effects of annealing time on the electrical properties of the Y2O3gate on silicon

“…The utilisation of high-k materials may assist in the reduction of excessive gate leakage current due to the direct tunnelling effect [1][2][3]. Recently, various types of high-k materials, such as HfO 2 [4], Al 2 O 3 [5], ZrO 2 [6], CeO 2 [7], Y 2 O 3 [3,[8][9][10][11][12][13][14][15][16][17][18][19][20], and Er 2 O 3 [21] have been extensively explored as the gate oxide to substitute SiO 2 . Among these gate oxides, Y 2 O 3 turns out to be a potential candidate to replace SiO 2 due to its fascinating properties, such as the high-k value (k ¼ 15-18), large band gap ($5.5 eV), large conduction band offset ($2.3 eV), low lattice mismatch, and good thermal stability with Si [3,[8][9][10][11].…”