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在激光诱导扩散等激光微细加工技术中 ,需要用聚焦激光束照射基片表面 ,以形成局部高温区。为使局部高温区的温度分布满足实验要求 ,对 10 6 μm聚焦连续波CO2 激光束照射下半导体基片的温度上升进行了数值计算。计算中考虑了基片材料对 10 6 μm激光的吸收系数随温度的变化。计算得到了温度上升与基片预热温度、入射激光束功率及曝光面积等参数的关系。结果表明 ,基片初始温度为室温及激光焦斑直径小于 10 0 μm时 ,激光照射形成稳定高温区的最高温度不超过 6 0 0K。增加基片初始温度 ,可以在建立满足要求的温度上升的同时 ,减小基片上高温区分布的面积。在同一初始温度下 ,在基片高温区分布的面积符合实验要求的前提下 ,应尽量使用较大的光斑尺寸和激光功率 ,从而使基片表面热斑的温度分布更易控制。
In laser microfabrication technology such as laser-induced diffusion, it is necessary to irradiate the surface of the substrate with a focused laser beam to form a local high-temperature region. In order to make the temperature distribution in the local high temperature region meet the experimental requirements, the temperature rise of the semiconductor substrate under 10 6 μm focused continuous wave CO2 laser beam irradiation was numerically calculated. In the calculation, the absorption coefficient of the 10 6 μm laser with the substrate material is considered as a function of temperature. The relationship between temperature rise and substrate preheat temperature, incident laser beam power and exposure area were calculated. The results show that when the initial temperature of the substrate is at room temperature and the diameter of the laser focal spot is less than 100 μm, the maximum temperature at which the laser irradiates to form a stable high temperature region does not exceed 600K. Increasing the initial temperature of the substrate can reduce the area of high temperature distribution on the substrate while establishing a temperature rise satisfying the requirements. Under the same initial temperature, under the condition that the area distributed in the high temperature area of the substrate conforms to the experimental requirements, the larger spot size and laser power should be used as much as possible so that the temperature distribution of the hot spots on the substrate surface can be more easily controlled.