基于Monte Carlo方法的RIE工艺模拟

发布时间：2018-08-04 15:44

【摘要】：反应离子刻蚀(RIE)工艺,是MEMS加工工艺中使用最广泛的技术手段之一。RIE的计算机模拟可以帮助工艺设计者通过改变模拟条件,如射频功率、气体压力、刻蚀温度,得到不同的模拟结果,以此来选择最佳工艺条件。这对于降低MEMS器件设计与研制成本,缩短研发周期,有着非常重要的意义。本文利用流体力学模型及鞘层等效电路模型确定出RF鞘层的特性,包括鞘层的电压及电场的时空分布等。以Monte Carlo方法为基本模拟手段,研究了离子与中性粒子在RF鞘层中的运动过程,得到了到达刻蚀材料表面并对刻蚀有效的粒子流量分布。利用刻蚀速度的计算公式,根据粒子流量分布得到刻蚀材料表面某点处某时刻的局部刻蚀速率。最后通过水平集函数描述刻蚀剖面的初始形貌,通过刻蚀材料表面的速度场,求解Hamilton-Jacobi方程得到刻蚀轮廓的演化过程。通过改变不同的刻蚀条件,得到了刻蚀轮廓随时间的变化图以及不同射频功率下、不同气体下、不同温度下、改变反应气体后的刻蚀模拟轮廓。模拟结果表明：在200W～400W范围内,射频功率的增加,可加快刻蚀速率,进一步增加功率,刻蚀速率反而下降；随着压力的增加,刻蚀速率不断增加,并在15Pa左右达到最大值,随后刻蚀速率不断减小；刻蚀速率与温度成正比。最后将在一定工艺条件下反应粒子刻蚀的模拟结果与实验结果进行了对比,两者吻合的较好。本文的研究表明,水平集算法是一种适合模拟等离子体刻蚀轮廓演化的高效算法,它能够有效地描述等离子体刻蚀仿真过程中出现的各种复杂轮廓,可以很好地满足等离子体刻蚀工艺过程中复杂形貌演化的模拟需求。虽然本文没有将其扩展到三维,但本论文将等离子体刻蚀的微观物理过程引入到了水平集方法中,为将来解决三维等离子体刻蚀过程仿真计算量大的问题提供了一种新的技术思路。
[Abstract]:Reactive ion etching (RIE) process is one of the most widely used techniques in MEMS processing. The computer simulation of rie can help process designers to change the simulation conditions, such as RF power, gas pressure, etching temperature, etc. Different simulation results were obtained to select the best process conditions. This is of great significance to reduce the design and development cost of MEMS devices and shorten the R & D cycle. In this paper, the characteristics of RF sheath are determined by using hydrodynamic model and sheath equivalent circuit model, including the voltage of sheath and the space-time distribution of electric field. The movement of ions and neutral particles in RF sheath was studied by using Monte Carlo method. The particle flux distribution which reached the surface of the etched material and was effective for etching was obtained. According to the particle flow distribution, the local etching rate at a certain point on the surface of the etched material is obtained by using the formula of etching velocity. Finally, the initial morphology of the etching profile is described by the level set function, and the evolution process of the etching profile is obtained by solving the Hamilton-Jacobi equation through the velocity field of the etched material surface. By changing different etching conditions, the etch profile with time is obtained, and the simulated etching profile is obtained under different RF power, different gas, different temperature, changing reaction gas. The simulation results show that in the range of 200W~400W, the increase of RF power can accelerate the etching rate, further increase the power, and decrease the etching rate, and with the increase of pressure, the etching rate increases and reaches the maximum value in 15Pa. Then the etching rate decreases and the etching rate is proportional to the temperature. Finally, the simulation results of reactive particle etching under certain technological conditions are compared with the experimental results, and the results are in good agreement with each other. The research in this paper shows that the level set algorithm is an efficient algorithm for simulating the evolution of plasma etching contour, and it can effectively describe various complex contours in the process of plasma etching simulation. It can well meet the needs of simulation of complex morphology evolution in plasma etching process. Although it has not been extended to three dimensions in this paper, the microphysical process of plasma etching is introduced into the level set method. It provides a new technical idea for solving the problem of large amount of simulation calculation in 3D plasma etching process in the future.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN305.7

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