摘要:
采用等离子增强化学气相沉积法,以氨气和硅烷为反应气体,p型单晶硅为衬底,低温下（200℃）制备了非化学计量比氮化硅（SiN_x）薄膜.在N_2氛围中,于500-1100℃范围内对薄膜进行热退火处理.室温下分别使用Fourier变换红外吸收（FTIR）光谱技术和X射线光电子能谱（XPS）技术测量未退火以及退火处理后SiN_x薄膜的Si-N,si-H,N-H键键合结构和si 2p,N 1_s电子结合能以及薄膜内N和si原子含量比值R的变化.详细讨论了不同温度退火处理下SiN_x薄膜的FHR和XPS光谱演化同薄膜内Si,N,H原子间键合方式变化之间的关系.通过分析FTIR和XPS光谱发现退火温度低于800℃时,SiN_x薄膜内Si-H和N-H键断裂后主要形成si-N键;当退火温度高于800℃时薄膜内Si-H和N-H键断裂利于N元素逸出和si纳米粒子的形成;当退火温度达到1100℃时N_2与SiN_x薄膜产生化学反应导致薄膜内N和Si原子含量比值R增加.这些结果有助于控制高温下SiN_x薄膜可能产生的化学反应和优化SiN_x薄膜内的Si纳米粒子制备参数.
Abstract:
Non-stoichiometric silicon nitride（SiN_x） thin films are deposited on p-type crystalline silicon substrates at low temperature （200℃） using ammonia and silane mixtures by plasma enhanced chemical vapor deposition.The evolutions of Si—N,Si—H and N—H bonding configurations,the variations of Si 2p and N 1s electron binding energy and the ratio R of nitrogen to silicon atoms in SiN_x films annealed at temperature in a range of 500—1100℃are investigated at room temperature by Fourier transform infrared spectroscopy（FTIR） and X-ray photoelectron spectroscopy（XPS）,respectively.The relationship between the evolutions of FTIR and XPS spectroscopy of the samples at different annealing temperatures and the variations of bonding configurations of Si,N and H atoms is discussed in detail.According to the arguments about FTIR and XPS spectroscopy we conclude that when the annealing temperature is lower than 800℃,the breakings of Si—H and N—H bonds in the SiN_x films lead mainly to the formation of Si—N bonds;when the annealing temperature is higher than 800℃,the breakings of Si—H and N—H bonds are conducible to the effusion of N atoms and the formation of silicon nanoparticles;when the annealing temperature equals 1100℃,the N_2 react on the SiN_x films to cause the ratio R of nitrogen to silicon atoms to inerease.These results are useful for controlling the probable chemical reaction in SiN_x films under high annealing temperatures and optimizing the fabrication parameters of silicon nanoparticles embedded in SiN_x films.
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