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Redistribution of valence and conduction band states depending on the method of modification of SiO2 structure
Physical Chemistry Chemical Physics ( IF 2.9 ) Pub Date : 2017-09-07 00:00:00 , DOI: 10.1039/c7cp04914e
A. S. Konashuk 1, 2, 3 , E. O. Filatova 1, 2, 3
Affiliation  

The effect of introducing porosity and the insertion of methyl groups in SiO4 tetrahedra on the distribution of valence and conduction band states of SiO2 was studied using high-resolution near edge X-ray absorption fine structure spectroscopy (NEXAFS) and soft X-ray photoelectron spectroscopy (XPS). Alignment of NEXAFS spectra and valence band XPS spectra in a common energy scale was performed using binding energies of the initial levels obtained by XPS. It was established that the insertion of methyl groups into SiO4 tetrahedra leads to a significant shift of the top of the valence band EV to smaller binding energies due to the reduction of the electronegativity of the nearest surrounding neighbors of the Si atoms, while introducing porosity changes the position of EV only slightly. The position of the bottom of the conduction band is affected by neither the introduction of porosity nor the insertion of methyl groups. The formation of the π*C[double bond, length as m-dash]C state near the Fermi level, caused by the presence of porogen residues in the structure of organosilicate glass (OSG) and responsible for the leakage currents, was revealed. It was found that high level porosity in OSG films induces a significant variation of Si–O–Si valence angles. A number of Si–O dangling bonds were found in the surface layers of por-SiO2, while methyl groups effectively passivated these dangling bonds in OSG films. The obtained results are important for understanding the regularities of electronic structure formation in SiO2-based low-k dielectrics, which is necessary for the reduction of energy dissipated in semiconductor integrated circuits (ICs).

中文翻译:

价和导带态的重新分布取决于SiO 2结构的改性方法

引入孔隙度的效果和甲基的以SiO插入4四面体在SiO的价带和导带状态的分布2使用高分辨率近边缘X射线吸收精细结构谱(NEXAFS)和软X射线进行了研究光电子能谱(XPS)。使用XPS获得的初始能级的结合能进行NEXAFS光谱和价带XPS光谱在常规能级上的比对。已经确定,甲基插入到SiO 4四面体中会导致价带E V的顶部发生明显移动。由于引入的孔隙率仅略微改变了E V的位置,这归因于Si原子周围最近邻居的电负性的降低,从而使键合能变小。导带底部的位置不受孔隙率的引入或甲基的插入的影响。[双键,长度为m-破折号]揭示了费米能级附近π* C C态的形成,这是由于有机硅酸盐玻璃(OSG)结构中存在致孔剂残基引起的,并且是造成漏电流的原因。发现OSG膜中的高孔隙率会引起Si–O–Si价角的显着变化。在por-SiO 2的表面层中发现了许多Si-O悬空键,而甲基有效地钝化了OSG膜中的这些悬空键。所获得的结果对于理解基于SiO 2的低k电介质中电子结构形成的规律非常重要,这对于减少半导体集成电路(IC)的能量消耗是必需的。
更新日期:2017-09-20
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