Passivation of Ge(100)∕GeO[sub 2]∕high-κ Gate Stacks Using Thermal Oxide Treatments

Abstract

The physical and electrical properties of Ge/GeO 2 /high-gate stacks, where the GeO 2 interlayer is thermally grown in molecular oxygen, are investigated. The high-layer ͑ZrO 2 , HfO 2 , or Al 2 O 3 ͒ is deposited in situ on the GeO 2 interlayer by atomic layer deposition. Detailed analysis of the capacitance-voltage and conductance-frequency characteristics of these devices provides evidence for the efficient passivation of the Ge͑100͒ surface by its thermal oxide layer. A larger flatband voltage hysteresis is observed in HfO 2 -based gate stacks, as compared to Al 2 O 3 gate stacks, which is possibly related to the more pronounced intermixing observed between the HfO 2 and GeO 2 .Inspired by the progress in the development of high-gate dielectrics for Si-based metal-oxide-semiconductor field-effect transistor ͑MOSFET͒ applications, 1 increasing attention is being focused on the feasibility of integrating high-gate dielectrics with germanium ͑Ge͒ because of its intrinsically higher mobility than silicon ͑Si͒. Electrical properties of several high-metal oxides deposited on Ge substrates have been recently reported, including HfO

Atomic Layer Deposition of High-k Dielectric Layers on Ge and III-V MOS Channels

“…For O 2 , the oxidation rate increases with temperature in the temperature range 300-450°C and follows the DealGrove model, as described previously (23 O 3 oxidation shows a maximum rate at ~300°C: the oxidation rate increases when increasing the temperature from 225 to 300°C, and then again decreases slightly when further increasing the temperature to 370°C (Figure 1). The oxidation rate of Ge by atomic oxygen increases with temperature.…”

Comparative study of GeO2/Ge and SiO2/Si structures on anomalous charging of oxide films upon water adsorption revealed by ambient-pressure X-ray photoelectron spectroscopy

“…7 Another approach is to cap the GeO 2 surface by the deposition of high-k dielectric layers. 8,9 Metal-oxide-doped GeO 2 such as yttrium-GeO 2 has attracted interest because of its stronger resistance to liquid water than pure GeO 2 . 10,11 The above studies indicate that GeO 2 is a key material in Ge-based MOSFETs, and it is still necessary to grasp the relationship between the physical/chemical properties of GeO 2 and its dielectric properties.…”

Effective Electrical Passivation of Ge(100) for HfO2 Gate Dielectric Layers Using O2 Plasma

“…[3][4][5] Proper passivation of the Ge surface is required before it can be used as a channel material. Different approaches have been employed for Ge surface passivation including H 2 O prepulsing, 6 thermal oxide treatment, [7][8][9] ozone oxidation, 10,11 atomic O beam, 12 epitaxial Si passivation, 13 and surface nitridation. 14 A relatively low interface trap density (to the low to mid of 10 11 eV À1 cm À2 ) was obtained for various dielectric including Al 2 O 3 , HfO 2 , and ZrO 2 .…”

“…In recent articles, it has been demonstrate that GeO 2 can also act as a promising electrical passivation layer for high-k dielectric deposited by means of atomic layer deposition (ALD). 7,8 However, very large C-V hysteresis ($900 mV) was observed for the HfO 2 gate stack by using thermally grown GeO 2 passivation layer. 7,8 In previous literatures, excellent electrical characteristics in GeO 2 /Ge MOS capacitors (MOSCAPs) grown by electron cyclotron resonance generated oxygen plasma were reported.…”

“…7,8 However, very large C-V hysteresis ($900 mV) was observed for the HfO 2 gate stack by using thermally grown GeO 2 passivation layer. 7,8 In previous literatures, excellent electrical characteristics in GeO 2 /Ge MOS capacitors (MOSCAPs) grown by electron cyclotron resonance generated oxygen plasma were reported. 17 A high quality of germanium oxide was obtained by using atomic oxygen exposure.…”