Kinetics and Modeling of Wet Etching of Aluminum Oxide by Warm Phosphoric Acid

Abstract

Aluminum oxide has been used widely in the microelectronic industry for dielectric films. Etching kinetics of vacuum sputtered aluminum oxide films by warm phosphoric acid is studied. The etch rate is found to be constant when the concentration and temperature of the etchant are fixed and the films being etched come from the same deposition batch. Etch rates obtained at different etchant concentrations show that over the industrial range of interest, the kinetics are first order in the hydrogen ion concentration which is a limiting form of a more general site model. Experiments of varying the etching temperature lead to the conclusion that the process is reaction controlled.

Low-temperature spray-deposited indium oxide for flexible thin-film transistors and integrated circuits

“…Following, a 25 nm-thick Al 2 O 3 gate dielectric layer (dielectric constant: 9.5) was deposited by atomic layer deposition (ALD) at 150 C. Gate contact holes through the Al 2 O 3 were patterned by photolithography and wet chemistry. 26 Subsequently, 10 nm/60 nm of Ti/Au were e-beam evaporated and structured into source/drain (S/D) contacts using a lift-off process. Prior to the semiconductor deposition, the substrate was diced into chips of 1.5 Â 1.5 cm 2 .…”

The electrical and physical analysis of Pt gate/Al2O3/p-Si (100) with dual high-k gate oxide thickness for deep submicron complementary metal-oxide-semiconductor device with low power and high reliability

“…Zhou et al reported that the etching rate of the vacuum-sputtered Al 2 O 3 films by warm phosphoric acid (H 3 PO 4 85%, 50°C) was proportional to H ϩ ion concentration. 8 Kikuyama et al reported a relationship between the etching rate and the HF 2…”

“…8,9 Therefore, based on their results, the etching process proceeded by the reactions given in Eqs. 1 and 2 8,9 .…”

“…8,9 Therefore, based on their results, the etching process proceeded by the reactions given in Eqs. 1 and 2 8,9 . Figure 4 shows the average root-mean-square roughness measured by AFM to determine the surface roughness variation as a function of the wet etching conditions.…”

A flexible InGaZnO based 1-bit SRAM under mechanical strain

“…We patterned and etched the semiconductor by standard photolithography (mask 2) and diluted hydrochloric acid [10] (HCl : H 2 O = 1 : 120). To remove the Al 2 O 3 above the gate contact pads, we used photolithography mask 3 and AL-11 aluminium etchant from Cyantek heated to 50 °C [11]. Due to the limited resistivity of a-IGZO against chemical etchants we deposited the upper metal layer (source and drain contacts, interconnects) using a lift off process.…”