The Influence of Fluorinated Silicon Nitride Gate Insulator on Positive Bias Stability toward Highly Reliable Amorphous InGaZnO Thin-Film Transistors

Abstract

For gate insulator of amorphous InGaZnO thin-film transistor, we fabricated fluorinated silicon nitride (SiN:F) film formed by an inductively-coupled plasma enhanced chemical vapor deposition method by utilizing SiF4/N2 as source gases. Threshold voltage shift against electrical stress was successfully suppressed. Chemical analysis revealed that the hydrogen concentration was reduced to 1/10 of conventional SiN film and fluorine was introduced into the interface between the SiN:F film and channel layer. We conclude that the decrease of hydrogen content and introduction of fluorine lead to decrease of electron trap density at the interface and/or the SiN:F film.

Investigating Effect of Postannealing Time on Positive Bias Stress Stability of In–Ga–Zn–O TFT by Conductance Method

“…When the postannealing time was increased from 1 to 5 h, V th after 10 4 s PBS reduced from 4.3 to 3.5 V. In order to investigate the causes of the phenomenon, the density of state (DOS) of the front channel interface (D i ) with the PBS duration was evaluated. Low-high C-V measurement is one of the most popular techniques for analyzing semiconductor/insulator interface properties [13], [20]. However, these capacitancebased extraction methods cannot provide the properties of defects, such as trap time constant, and capture cross section.…”

69.1: Invited Paper: The Advantages of the Self‐Aligned Top Gate Oxide TFT Technology for AM‐OLED Displays

“…Since the first announcement of a-IGZO TFT in 2004 [5], its instability against the bias stress was regarded as a severe problem, and a lot of studies have be done by the worldwide researchers [3,4,[6][7][8][9][10][11][12][13][14][15]. It is well known that the properties of oxide semiconductor are highly dependent on the oxygen content, since oxygen vacancies provide the free carriers.…”

“…To improve the stability against PBTS, many studies have been reported [9][10][11][12]. The effects of the passivation, annealing process, the condition control of the interface between oxide semiconductor and gate insulator, or the hydrogen content control of the neighboring films [7][8][9][10][11][12]. We also try to improve the BTS stability by optimizing the TFT fabricating process.…”

Electrical Performance and Reliability Improvement of Amorphous-Indium-Gallium-Zinc-Oxide Thin-Film Transistors with HfO2 Gate Dielectrics by CF4 Plasma Treatment

“…It is reported that fluorine incorporated into the a-IGZO TFT can effectively improve TFT reliability [ 20 , 21 , 22 , 23 , 24 , 25 , 26 ], because F has several advantages: (i) it has the highest electron affinity among chemical elements, which makes F simple to bond with misoriented metal atoms in the IGZO active layer and reduce the DOS, (ii) compared to hydrogen, F can provide stronger bonding with the metal ion in the active layer to improve the a-IGZO TFT stability [ 27 ], and (iii) extra free electrons can be generated by the fluorine ions by replacing the oxygen sites, due to the difference in electrovalence between the oxygen ion (O 2− ) and the fluorine ion (F − ). The higher electron density induced in the active layer will improve the carrier mobility of the a-IGZO TFT [ 28 ].…”