Charge in SiO[sub 2]-Al[sub 2]O[sub 3] Double Layers on Silicon

Abstract

The negative charge in AI-A1203-SiO2-Si double layers was found to be located at the insulator-insulator interface. This charge is independent of the thickness of the A1203 and inversely dependent on the SiO2 thickness. Evidence for a constant voltage drop across the SiO2 during A1203 deposition was found for polycrystalline A1.~O3, N2-deposited and O2-deposited amorphous A1208. It is suggested that the traps at the interface Al~O3-SiO~ are due to oxygen vacancms.Double layer insulators are becoming more and more common in semiconductor technology. One system of particular recent interest is the A12Oz-SiO2 structure.

Crystalline silicon surface passivation by the negative-charge-dielectric Al<inf>2</inf>O<inf>3</inf>

“…[13] presence of AI vacancies in the AI203 film. [14] It was shown that these vacancies are predominantly present at the c-Si/A1203 interface, [15] in excellent agreement with the position of the fixed negative charge density deduced from thickness dependent capacitance voltage measurements by for example Abouaf et al [16] A negative Qf is especially beneficial for the passivation of p-type c-Si as the minority carriers, the electrons, are effectively shielded from the c-Si surface. This is clearly apparent from the fact that the negative charge-dielectric AI203 provides a state-of-the-art level of surface passivation even on highly B-doped p-type c Si surfaces as shown in Fig.…”

Plasma-Assisted ALD for the Conformal Deposition of SiO2: Process, Material and Electronic Properties

“…The latter can also be directly appreciated from the stack with a 30 nm interlayer. Therefore, in addition to the relation given in (3), an alternative, more complex model can be introduced which accounts for a positive charge contribution Q pos at the Si/SiO 2 interface and a negative charge contribution Q neg at the SiO 2 /Al 2 O 3 interface: 49,51 …”

Influence of the SiO2 interlayer thickness on the density and polarity of charges in Si/SiO2/Al2O3 stacks as studied by optical second-harmonic generation

“…Values reported in the literature by Saito et al 41 for the effective charge density in Si/SiO 2 /Al 2 O 3 stacks with dry thermal oxide interlayers in the thickness range 0.7-2 nm are between À2 Â 10 13 and À5 Â 10 12 cm À2 , respectively. Aboaf et al 42 obtained values of $3 Â 10 11 cm À2 for plasma oxidized interlayers in Si/SiO 2 /Al 2 O 3 stacks with a SiO 2 thickness in the range of 23-100 nm. Compared to our data these values from the literature agree very well for both SiO 2 thickness ranges, especially, considering the fact that the interlayers have been prepared using different deposition methods.…”