摘要
用密度泛函方法研究了ZrO2在羟基预处理的Si(100)-2×1表面原子层淀积(ALD)初始反应过程的反应机理,ZrO2的ALD过程包括两个前体反应物ZrCl4和H2O交替的半反应.两个半反应都经历一个相似的吸附中间体反应路径.比较单羟基Si表面反应的反应焓变,可以发现双羟基Si表面反应,由于相邻羟基的存在,对ZrCl4的半反应影响较大,尤其是化学吸附能增加明显.而对于H2O的半反应,单、双羟基Si表面反应的能量变化不是很明显.使用内禀反应坐标(IRC)方法,验证了两个半反应存在相似的过渡态结构和反应机理.另外,发现随着温度的升高,吸附络合物的稳定性降低,其向反应物方向的解吸附变得容易,而向产物方向的解离难度增加.
Density functional theory was employed to investigate atomic layer deposition （ALD） mechanism of zirconia on Si（100）-2× 1 surface with single and double hydroxyl groups. The ZrO2 ALD process using ZrCl4 and H2O as precursors involves two alternate deposition half-reactions： ZrCl4 and H20 half-reactions. Both the half-reactions proceeded through an analogous trapping-mediated mechanism. Compared to the singly hydroxylated Si surfaces, the neighboring hydroxyl of the doubly hydroxylated Si surfaces has a major effect on ZrCl4 half-reaction, especially the formation of ZrCl4 intermediate complex, and a minor effect on H2O half-reaction. Both ZrCl4 and H2O half-reactions were found to follow a similar reaction pathway with IRC method. In addition, the intermediate stability was lowered as the surface temperature was raised. However, increasing temperature also enlarged the dissociation free energy barrier, which in turn resulted in increased desorption of adsorbed precursors.
出处
《化学学报》
SCIE
CAS
CSCD
北大核心
2006年第11期1133-1139,共7页
Acta Chimica Sinica
基金
中国博士后科学基金(No.2004035450)
上海市科委基金(No.04JC14013)
河北科技大学科研基金资助项目.
关键词
原子层淀积
密度泛函理论
高介电常数栅介质
氧化锆
atomic layer deposition
density functional theory
high-k gate dielectric
zirconia
