非晶InGaZnO薄膜三极管稳定性：沟道层与钝化层的影响

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"沟道层和钝化层对非晶InGaZnO薄膜三极管的稳定性的影响" 本文是一篇研究论文，探讨了沟道层和钝化层如何影响非晶InGaZnO（a-IGZO）薄膜晶体管的稳定性。InGaZnO是一种广泛应用于显示器和其他电子设备的透明半导体材料，其性能稳定性和可靠性对于器件的长期工作至关重要。作者通过实验比较了具有三种不同沟道层结构的a-IGZO TFT（薄膜晶体管）的电气稳定性。研究中，他们发现与单一沟道层相比，采用双层堆叠沟道结构的a-IGZO TFT在正向和负向栅极偏压应力测试下表现出更低的阈值电压漂移，并且场效应迁移率和亚阈值摆动仅有轻微变化。这意味着双层沟道设计可以提高器件的稳定性。此外，他们还引入了溅射沉积的SiNx薄膜作为钝化层，这一举措显著减少了因栅极偏压应力导致的阈值电压Vth的漂移。进一步的研究表明，钝化层的使用能够减少界面陷阱，这些陷阱通常会降低器件性能并加速稳定性退化。在双层沟道结构的a-IGZO TFT上添加SiNx钝化层后，界面陷阱的数量减少，从而改善了整体的稳定性。这表明，优化沟道层和钝化层的设计是提高a-IGZO薄膜晶体管性能和长期稳定性的关键策略。文章详细介绍了实验方法、结果分析以及可能的物理机制。通过电荷陷阱模型，作者解释了钝化层如何减少电荷捕获，从而增强器件的耐久性。他们还讨论了这种改进可能对未来的显示技术以及其他基于a-IGZO的电子设备的潜在影响。这项工作为理解和优化非晶InGaZnO薄膜晶体管的稳定性提供了一个深入的视角，强调了沟道层结构和钝化层的重要性。这些发现对于提升基于a-IGZO材料的半导体器件的性能和可靠性具有重要的指导意义，有望推动相关技术的发展。

Inﬂuence of channel layer and passivation layer on the stability

of amorphous InGaZnO thin ﬁlm transistors

Runze Zhan

⇑

, Chengyuan Dong

, Po-Tsun Liu

, Han-Ping D. Shieh

a,b

National Engineering Lab for TFT-LCD Materials and Technologies, Department of Electronic Engineering, Shanghai Jiao Tong University, Shanghai 200240, China

Department of Photonics & Display Institute, National Chiao Tung University, Hsinchu, Taiwan

article info

Article history:

Received 29 September 2012

Received in revised form 14 May 2013

Accepted 15 May 2013

Available online xxxx

abstract

The electrical stability of amorphous InGaZnO (a-IGZO) TFTs with three different channel layers was

investigated. Compared with the single channel layer, the a-IGZO TFT with double stacked channel layer

showed the lowest threshold voltage shift with slightly change in ﬁeld effect mobility and sub-threshold

swing under positive and negative gate bias stress tests. Moreover, sputtered SiN

thin ﬁlm was served as

passivation layer where the V

shift in bias stress effect evidently became less. It was found that the pas-

sivated a-IGZO TFT with double stacked channel layer still exhibited the best stability. The results prove

that the stability of a-IGZO TFTs can be effectively improved by using double stacked channel layer and

passivation layer.

1. Introduction

Amorphous oxide semiconductors especially amorphous InG-

aZnO (a-IGZO) are being used as channel materials in thin ﬁlm

transistors(TFTs) for the applications of next generation active ma-

trix ﬂat panel displays because of their advantages including high

mobility, room temperature deposition, excellent uniformity, high

ﬂexibility, and good transparency to visible light, etc. [1]. Recently,

several prototype displays, such as high deﬁnition liquid crystal

displays (LCDs), active matrix (AM) ﬂexible displays, and active

matrix organic light emitting diode (AMOLED) displays, with a-

IGZO TFTs used as driving circuits have been demonstrated [2,3].

Despite of the great progress in the device and process develop-

ment, the instability of a-IGZO TFTs is still a concern for their prac-

tical applications [3,4].

To produce good and stable TFTs, appropriate deposition condi-

tions for channel layer should be considered. For the n-type oxide

semiconductor, it is well known that oxygen plays an important

role in the properties of thin ﬁlms and TFT devices [5–7]. For in-

stance, the electrical stability of a-IGZO TFTs with excess oxygen

in their active layers degrades due to the defects in the channel

layer/gate insulator layer interface and/or acceptor-like defects in

the bulk of channel layer [8,9]. Moreover, because of the instability

induced by ambient effect for the TFTs with exposed back channel,

passivation layer is usually used to improve the stability of oxide

semiconductor TFTs [10–12]. However, the effect of the passivation

process on the performance of channel layer from plasma damage

should be considered in depth.

In this work, the electrical stability of a-IGZO TFTs with three

types of channel layers was investigated. More speciﬁcally, we fab-

ricated a double stacked channel layer with different deposition

conditions and studied their inﬂuence on the performance of TFTs.

The bias stress effect for the TFTs was studied. Furthermore, TFTs

with a sputtered SiN

passivation layer was studied, and the corre-

sponding passivation effect was discussed.

2. Experimental

The TFTs with bottom gate staggered structure, as shown in

Fig. 1, were fabricated on the substrates of n-type silicon (Si) wa-

fers, which were also used as common gate. A 100-nm-thick SiO

layer was grown by thermal oxidation of Si wafer. The channel

layer and source/drain electrodes were patterned using shadow

masks. The fabricated TFTs had a channel length (L) of 200

and width (W) of 1000

m. As a channel layer, a-IGZO ﬁlm was

deposited by RF magnetron sputtering using a target of polycrys-

talline In

ZnO

(In

:Ga

:ZnO = 1:1:1, mol%) at room tem-

perature. A ﬂow rate of 10 sccm for argon and different oxygen

ﬂow rates were used to study the impact of channel layer on the

device performance. Three types of channel layers were studied:

for sample I, a-IGZO (Ar) thin ﬁlm as channel layer was deposited

without oxygen, called as oxygen-poor IGZO ﬁlm; for sample II, a-

IGZO(Ar + O

) thin ﬁlm was deposited with an oxygen ﬂow rate of

2.0 sccm, called as oxygen-rich IGZO ﬁlm; specially, for sample III

with a double stacked channel layer, 20-nm-thick oxygen-poor a-

IGZO(Ar) and 10-nm-thick oxygen-rich a-IGZO(Ar + O

) thin ﬁlms

were served as the front and back channel layers, respectively.

The entire channel thickness for three types of TFTs was 30 nm.

In deposition the total pressure was ﬁxed at 3 m Torr and the RF

http://dx.doi.org/10.1016/j.microrel.2013.05.007

⇑

Corresponding author. Tel.: +86 21 34204371.

E-mail addresses: zhanrz@sjtu.edu.cn, zhanrz@hotmail.com (R. Zhan).

Microelectronics Reliability xxx (2013) xxx–xxx

Contents lists available at SciVerse ScienceDirect

Microelectronics Reliability

journal homepage: www.elsevier.com/locate/microrel

Please cite this article in press as: Zhan R et al. Inﬂuence of channel layer and passivation layer on the stability of amorphous InGaZnO thin ﬁlm transistors.

Microelectron Reliab (2013), http://dx.doi.org/10.1016/j.microrel.2013.05.007

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