Frequency dispersion analysis of thin dielectric MOS capacitor in a five-element model

Abstract

An Al/ZrO2/IL/n-Si (IL: interface layer) MOS capacitor has been fabricated by metal organic decomposition of ZrO2 and thermal deposition Al. We have measured parallel capacitance (Cm) and parallel resistance (Rm) versus bias voltage curves (Cm, Rm–V) at different AC signal frequency (f), and Cm, Rm–f curves at different bias voltage. The curves of Cm, Rm–f measurements show obvious frequency dispersion in the range of 100 kHz–2 MHz. The energy band profile shows that a large voltage is applied on the ZrO2 layer and IL at accumulation, which suggests possible dielectric polarization processes by some traps in ZrO2 and IL. Cm, Rm–f data are used for frequency dispersion analysis. To exclude external frequency dispersion, we have extracted the parameters of C (real MOS capacitance), Rp (parallel resistance), CIL (IL capacitance), RIL (IL resistance) and Rs (Si resistance) in a five-element model by using a three-frequency method. We have analyzed intrinsic frequency dispersion of C, Rp, CIL, RIL and Rs by studying the dielectric characteristics and Si surface layer characteristics. At accumulation, the dispersion of C and Rp is attributed to dielectric polarization such as dipolar orientation and oxide traps. The serious dispersion of CIL and RIL are relative to other dielectric polarization, such as border traps and fixed oxide traps. The dispersion of Rs is mainly attributed to contact capacitance (Cc) and contact resistance (Rc). At depletion and inversion, the frequency dispersion of C, Rp, CIL, RIL, and Rs are mainly attributed to the depletion layer capacitance (CD). The interface trap capacitance (Cit) and interface trap resistance (Rit) are not dominant for the dispersion of C, Rp, CIL, RIL, and Rs.

Error analysis and frequency selection guidelines for three-frequency correction in MOS capacitors

“…After correction, the frequency dispersion at accumulation is fully eliminated. For the depletion and inversion regions, the fiveelement model does not include depletion capacitance and interface traps [19], and the thermal noise is large [13] due to the small number of minority carriers. Consequently, the curves are not consistent in the depletion and inversion regions (having strong fluctuation).…”

“…Two-element models, whether parallel or series, cannot be used for accurate extraction of accumulation capacitance because of serious frequency dispersion and rolloff (or upturn). To extract accumulation capacitance accurately, many equivalent circuit models have been used, including three-element [4][5][6][7][8][9][10][11][12], four-element [13,14], and five-element models [15][16][17][18][19]. For thin dielectric MOS capacitors, an interface layer (IL) is inevitable, and a five-element model with IL has been considered as a reasonable model [16,17].…”

“…For thin dielectric MOS capacitors, an interface layer (IL) is inevitable, and a five-element model with IL has been considered as a reasonable model [16,17]. For the five-element model, we have developed a combined double-frequency C−V plus I−V correction method [18] and three-frequency C−V correction method [19] to extract the accumulation capacitance. Both methods require that there be no frequency dispersion for the five parameters, in principle.…”

“…Both methods require that there be no frequency dispersion for the five parameters, in principle. In practice, the former is suitable for leaky MOS capacitors (DC leakage as dominant conductance mechanism), whereas the latter allows small frequency dispersion in accumulation capacitance and larger dispersion in the other parameters [19]. For two-frequency correction of a typical three-element model, frequency selection guidelines using error propagation have been reported [9].…”

Ferroelectric and strain-tuned MoSe2/Bi2O2Se van der Waals heterostructure with band alignment evolution

“…11,12 In recent years, a large number of 2D vdWH materials have been designed and prepared successfully. [1][2][3][4][13][14][15][16][17][18] Numerous studies showed that the type of band alignment of a heterostructure can be effectively regulated by means of regulating layers, 19 stacking patterns, 20 external stress, 21 electric field, 22 spontaneous polarization, 23 etc. However, it is still challenging to modulate bipolar characteristics in a vdWH material, which could expand its application potential in the multifunctional integration in a single device.…”