标题: 高介电常数材料二氧化铪在矽基板上之介面特性研究
The Interface Investigation of High-K Material HfO2 on Si Substrate
作者: 陈世璋
Shih-Chang Chen
罗正忠
张鼎张
Jen-Chung Lou
Ting-Chang Chang
电子研究所
关键字: 高介电;二氧化铪;high-k;HfO2
公开日期: 2002
摘要: 根据半导体的微缩定律,随着半导体制造逐渐的微小化,极薄的二氧化矽介电层将伴随着极大的直接穿遂漏电流,而这个直接穿遂漏电流将对元件的功率消耗有严重的影响。在闸极二氧化矽介电层薄到10奈米以下的情况之下,为了解决这严重的直接穿遂漏电流现象,我们将利用高介电系数材料来替换传统的二氧化矽。我们利用高介电系数材料在相同的等效二氧化矽厚度之下,能拥有较大的实际物理厚度以抵挡直接穿遂漏电流。
在众多高介电系数材料之中,二氧化铪是一种非常有潜力的高介电系数材料。它有较高的介电系数,足够高的载子能障,以及在制程上能有着良好的稳定性。在我们的实验过程中,我们发现二氧化铪在实验中所展现的一些特性及现象,这些包括了:漏电流的趋势变化,电容-电压电性分析上的平台现象,界面层增生的问题,以及在电性逼迫之后,发生电子在介电层中被补陷的现象。实验中另一类的试片,是在成长二氧化铪薄膜之前,我们先使用了快速热成长氧化层或高温下(800℃)的氨气来对矽晶片做表面的处理。我们发现这两种表面处理都能改善试片在电容-电压电性分析上的平台现象,其中高温下的氨气表面处理更可以降低试片的漏电流。
而在SILC的电性逼迫测试之下,我们发现电子在介电层中被补陷的程度会随着逼迫时间的累积而越来越严重。有先经过快速热成长氧化层处理的话,其介电质的可靠度将会变得较佳。另外在结构上,若高介电常数材料与矽基板之间有一层界面薄膜层的话,这层界面薄膜层的品质优劣将决定整个介电层崩溃的临界极限。在HfO2薄膜内的漏电传导机制是由Frenkel-Poole发射所主导的。
According to the scalling rules, aggressive scaling has led to silicon dioxide (SiO2) gate dielectrics as ultra thin in state-of-the-art CMOS technologies. As a consequence, static leakage power due to direct tunneling through the gate oxide has been increasing at an exponential rate. As technology roadmaps call for sub-10Å gate oxides within the next five years, a variety of alternative high-k materials are being investigated as possible replacements for SiO2. The higher dielectric constants in these materials allow the use of physically thicker films, potentially reducing the tunneling current while maintaining the gate capacitance needed for scaled device operation.
Hafnium oxide ( HfO2 ) is the most potential high-k material. It has the higher dielectric constant , higher barrier height ( 1.6eV for electrons , and 3.4eV for holes ), and excellent stability. In our experiments, the variation of leakage current , hump in C-V curves, interfacial layer increasing, and electron trapping are observed and investigated in un-surface treatment HfO2 samples. The rapid thermal oxide ( RTO ) and NH3 surface treatments both can improve the C-V curves. Moreover, the lower leakage current is observed in NH3 surface treatment samples.
The results of stress induces leakage current ( SILC ) measurements show the severe electron trapping under the high electric field stress. The reliabilities can be improved by the RTO surface treatment, and the dielectric breakdown much depends on the quality of the interfacial layer. The conduction mechanism in the HfO2 thin film is dominated by the Frenkel-Poole emission.
URI: http://140.113.39.130/cdrfb3/record/nctu/#NT910428087
http://hdl.handle.net/11536/70417
显示于类别:Thesis