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气相小分子在金属单晶表面上解离化学吸附的机理研究十分活跃.目前描述化学吸附过程有两种不同的机理,即直接解离和前驱态(Precursor)机理.前者认为气相分子与固相表面碰撞能直接解离成碎片吸附于表面上;后者则假设分子入射表面先经中间前驱态再发生解离化学吸附.要深入研究上述不同的吸附机理,分子束技术是一种有效的实验手段,通过测定入射分子束的平动能以及入射角对解离吸附的影响,可以获得有关化学吸附的重要信息.在半导体表面气相化学蚀刻反应中Si-Cl_2体系占有十分重要的地位.我们在文献[4,5]中曾指出Cl_2分子在Si表面上解离吸附是蚀刻反应关键的一步,但是对其吸附机理的深入研究尚未见报道.本文将首次采用超声分子束、角分辨的飞行时间质谱和激光诱导吸附技术,研究Cl_2在Si(111)表面上吸附的平动能效应,并探讨其解离化学吸附的机理.
The mechanism of dissociative chemisorption of gas-phase small molecule on the surface of metal single crystal is very active.At present, there are two different mechanisms of chemical adsorption, namely direct dissociation and Precursor mechanism.The former thought that the interaction between gas phase molecule and solid phase Surface collisions can be directly dissociated into fragments adsorbed on the surface; the latter assumes that the molecular incident surface through the intermediate precursor state again dissociative chemisorption. To study these different adsorption mechanisms, molecular beam technology is an effective experiment Means that important information about chemisorption can be obtained by measuring the translational energy of the incident molecular beam and the influence of incident angle on the dissociative adsorption. The Si-Cl 2 system plays a very important role in the vapor phase chemical etching of semiconductors. It has been pointed out in [4,5] that dissociative adsorption of Cl_2 molecules on the Si surface is a key step in the etching reaction, but further studies on its adsorption mechanism have not been reported yet.In this paper, the first time using ultrasonic molecular beam, angular resolution time of flight mass spectrometry And laser-induced adsorption technology to study the kinetic energy of Cl 2 adsorption on the Si (111) surface and to explore its mechanism of chemical dissociation.