Improved reliability from a plasma-assisted metal-insulator-metal capacitor comprising a high-k HfO2 film on a flexible polyimide substrate

Abstract

We have used a sol-gel spin-coating process to fabricate a new metal-insulator-metal (MIM) capacitor comprising a 10 nm-thick high-k thin dielectric HfO(2) film on a flexible polyimide (PI) substrate. The surface morphology of this HfO(2) film was investigated using atomic force microscopy and scanning electron microscopy, which confirmed that continuous and crack-free film growth had occurred on the film surface. After oxygen (O(2)) plasma pretreatment and subsequent annealing at 250 degrees C, the film on the PI substrate exhibited a low leakage current density of 3.64 x 10(-9) A cm(-2) at 5 V and a maximum capacitance density of 10.35 fF microm(-2) at 1 MHz. The as-deposited sol-gel film was completely oxidized when employing O(2) plasma at a relatively low temperature (ca. 250 degrees C), thereby enhancing the electrical performance. We employed X-ray photoelectron spectroscopy (XPS) at both high and low resolution to examine the chemical composition of the film subjected to various treatment conditions. The shift of the XPS peaks towards higher binding energy, revealed that O(2) plasma treatment was the most effective process for the complete oxidation of hafnium atoms at low temperature. A study of the insulator properties indicated the excellent bendability of our MIM capacitor; the flexible PI substrate could be bent up to 10(5) times and folded to near 360 degrees without any deterioration in its electrical performance.

Transparent and flexible capacitors based on nanolaminate Al2O3/TiO2/Al2O3

“…Many techniques have been used to deposit dielectric thin films, such as chemical vapor deposition (CVD) [ 16 ], pulsed laser deposition (PLD) [ 17 ], magnetron sputtering [ 18 ], and sol–gel spin coating method [ 19 ]. However, CVD methods usually require a high growth temperature which is not suitable for many flexible substrates.…”

“…In addition, physical damages on the film may be caused by high-energy particles in sputtering or PLD process. In 2009, Meena et al used a sol–gel spin-coating process to deposit HfO 2 films on a Cr/Au-coated flexible polymide substrate at room temperature [ 19 ]. This capacitor device exhibited excellent electrical properties under various bending conditions.…”

High‐Performance Nanostructured Flexible Capacitor by Plasma‐Induced Low‐Temperature Atomic Layer Annealing

“…To the best of our knowledge, our work shows the highest capacitance density and k-value with comparably low leakage current density level (10 −7 A cm −2 ) and decent flexibility (10 mm radius convex bending) compared with other flexible capacitors ever fabricated by ALD techniques and other low-temperature processes directly on flexible substrates including PET, PEN, PI, and PC (Table 1). [39][40][41][47][48][49][50][51] Generally, the flexible capacitor with ALD-processed dielectric layers showed higher capacitance density. For example, Zhang et al [39] fabricated flexible MIM capacitors with a surface area enhancing regime by incorporating Ag NWs into the bottom electrode composite ALD-AZO (Al-doped ZnO)/Ag NWs/sputtered AZO, which exhibited a capacitance density of 10.1 nF mm −2 at 10 kHz.…”

“…To the best of our knowledge, our work shows the highest capacitance density and k ‐value with comparably low leakage current density level (10 −7 A cm −2 ) and decent flexibility (10 mm radius convex bending) compared with other flexible capacitors ever fabricated by ALD techniques and other low‐temperature processes directly on flexible substrates including PET, PEN, PI, and PC ( Table 1 ). [ 39–41,47–51 ] Generally, the flexible capacitor with ALD‐processed dielectric layers showed higher capacitance density. For example, Zhang et al.…”

Gate dielectric surface modification in organic field-effect transistors

“…In the case of Ta 2 O 5 and Compared to other processing routes such as sol-gel, 21,22,207,210,212 sputtering 209,211,214,215,217 and anodization, 21 ALD offers many advantages because of its self limiting chemical reaction: (i) accurate film thickness control (in subnanometer); (ii) good uniformity over large area (up to many inches size) and reproducibility; and (iii) high film quality at low deposition temperature that is well compatible with plastic substrates. 208,213,218 The study on the influence of oxygen plasma on device performance will be carried out through various exposure times for plasma treatment and a series of (negative and positive) gate bias stress measurement. It is found that using plasma-treated HfO 2 realized not only higher mobility but also improved resistance to gate bias stress, as well as the tunability of threshold voltage.…”