Improvement in C-V characteristics of Ge metal-oxide semiconductor capacitor by H2O2 incorporated HCl pretreatment

Abstract

Electrical characteristics of high-κ∕Ge metal-oxide semiconductor (MOS) capacitors pretreated with HCl or HF solutions are investigated, including the effect of H2O2 incorporation. HCl treatment is more effective than HF treatment for decreasing equivalent oxide thickness. H2O2 incorporation into HCl solution leads to dramatic decrease in the capacitance at inversion side. We have confirmed that residual metal impurities are reduced below 1010atoms∕cm2 on the Ge surface after pretreatment with mixed solution of HCl and H2O2. We conclude that decrease in metal impurities at Ge surface is responsible for the superior C-V characteristic of Ge MOS capacitor.

Process temperature dependent high frequency capacitance-voltage response of ZrO2/GeO2/germanium capacitors

“…The observed pinning of the loss peak may be also due to mid-gap-bulk traps at the fixed depth of the crossover point, introduced by metal contaminations. 4 However, the ToF-SIMS measurements with a detection-limit of about 10 15 atoms/ cm 3 for metals ͑Ni, Cu, and Fe͒ provide no evidences of growth temperature dependent metal contamination in the depletion-zone of the bulk, whereat a smallest amount of necessary bulk trap density of Ͼ10 16 atoms/ cm 3 has been reported to reach the observed transition frequency of f c Ϸ 1 ϫ 10 5 Hz of the Zr250C. 16 Thus we assume here, that the observed shortening of R of Zr250C is most likely related to the suffered loss of the interfacial GeO.…”

“…Despite of the successful realization of Ge based MOSFET 2 and numerous improvements concerning MOS capacitors, the device performance reported is still below theoretical predictions, mainly due to insufficient Ge/oxide interface passivation. 3 However, several very capable approaches for Ge surface passivation techniques have been reported, [3][4][5] and superior electrical behavior of the dielectrics by use of atomic layer deposition ͑ALD͒ on interfacial GeO 2 has been observed. 6 Capacitance-voltage ͑C-V͒ measurements are eminently suited to characterize MOS capacitors.…”

Physical properties of Co/n-Ge Schottky contacts

“…Moreover the metal impurities at the germanium surface are not removed with such a cleaning in contrary to what is observed after an HCl cleaning for instance. [20] This may also influence the SBH characterization. Another way to clean the germanium surface is to realize the thermal decomposition of the native oxide layer GeO X as its desorption occurs at 430 • C under high vacuum.…”

Impact of Germanium Surface Conditioning and ALD-growth Temperature on Al[sub 2]O[sub 3]/ZrO[sub 2] High-k Dielectric Stacks

“…Ge-based MOS capacitors may show low frequency capacitance-voltage ͑C-V͒ behavior even at 1 kHz or higher if biased in inversion, as reported by Dimoulas et al 7 By causing frequency dispersion in the inversion regime, this behavior has been attributed to the high intrinsic carrier concentration of Ge and to contamination-induced midgap trap levels in the depletion layer, such as metal impurities like Fe and Cu. 7,8 The specific behavior of the inversion MOS capacitance even at high frequencies is still under investigation. 9 For ALD, several different passivation methods of germanium substrates have been investigated including reoxidation of etched Ge surfaces to GeO 2 and GeON, which appeared to be promising.…”

“…Wet chemical treatments containing deionized ͑DI͒ water, hydrogen peroxide, and hydrohalogenic acids ͓HF, HCl, and hydrobromic acid ͑HBr͔͒ have been reported for this purpose. 3,13,8 In various etching chemistries an underlying GeO x suboxide still remains, which was considered to act as a hydroxylated starting surface for ALD. 13 For HBr, a suboxidefree germanium surface could be achieved without any indication of reoxidation of the surface if exposed to ambient air.…”