标题: 具T型闸极与空气边衬之新式多晶矽薄膜电晶体
A Novel Poly-Si TFT with T-Shaped Gate and Air Spacers
作者: 杨宗佑
林鸿志
Yang, Zong-You
Lin, Horng-Chih
电子研究所
关键字: T型闸极;多晶矽;薄膜电晶体;空气边衬;射频元件;T-shaped gate;poly silicon;thin film transistor;air spacer;RF device
公开日期: 2017
摘要: 在本篇论文中提出一种具T型闸极与空气边衬之新式多晶矽薄膜电晶体。我们巧妙的对一以p型多晶矽/n型多晶矽堆叠的双层薄膜闸极,进行高选择比的侧向蚀刻,将下层n型多晶矽薄膜的两侧朝内蚀刻后便形成了T型闸极。此种新的T型闸制程相当简单,并且可以顺利的加入传统的电晶体制程。为了更加降低寄生电阻的影响,我们也引入了可实现自我对准的金属矽化镍制程。此外,在元件完成并盖上保护层后,会因为T型闸极的遮蔽效果而在两侧形成空气边衬。实验的结果显示矽化镍的T型闸极确实可以大幅降低闸极寄生电阻,而空气边衬能够降低闸极与源/汲极之间的寄生电容。新式的T型闸元件透过侧向蚀刻可将通道长度缩短至96奈米,大幅提升了驱动电流与转导。综合上述T型闸制程的优点,采用T型闸制程的多晶矽薄膜电晶体其截止频率相较于采用传统制程的元件提高了两倍以上,达到了12.4GHz。较低的闸极寄生电阻也使T型闸元件的最大震荡频率呈明显的提升。
In this thesis, a novel poly-Si thin-film transistor (TFT) with T-gate and air spacers is proposed and demonstrated with a new process scheme which ingeniously makes use of a highly selective etching to laterally remove the bottom n+ poly-Si in a p+ poly-Si/n+ poly-Si stack and form the T-gate. This T-gate process is simple and can be readily implemented in conventional fabrication flow. In order to further reduce the parasitic resistances, we also introduce Ni self-aligned silicidation (SALICEDE) process in the fabrication. In addition, owing to the shadowing effect of the T-gate, sidewall air spacers can be obtained after the deposition of the passivation oxide. The results confirm that the silicided T-gate can significantly reduce the parasitic gate resistance, while air spacers can reduce the parasitic capacitances between gate and source/drain (S/D). Furthermore, the lateral etching shortens the channel length of the T-gate devices to 96nm, greatly improving the current drive and transconductance. As a consequence, the cut-off frequency (fT) of the T-gate poly-Si TFTs reaches 12.4GHz, which is two times higher than that of the conventional devices. In the meantime, maximum oscillation frequency (fMAX) also receives a great improvement owing to the reduced gate resistance with the T-gate.
URI: http://etd.lib.nctu.edu.tw/cdrfb3/record/nctu/#GT070450112
http://hdl.handle.net/11536/142533
显示于类别:Thesis