Time-evolution of film thickness profiles by level set method during CVD multiscale simulation

摘要

Chemical vapor deposition(CVD)is one of the most widely used processes for production of thin solid films.Solving chemical reactions for deposition and mass transfer of the relevant chemical species during CVD is essential to predict film thickness profile and to design an optimal reactor and reaction condition for uniform film formation with high throughput.Because of high conformality of CVD,substrates with three-dimensional(3D)microstructures are commonly used.Therefore,two spaces with extreme different scales are coexist in the reactor,i.e.reactor-scale(macroscale)and microstructure-scale(microscale).However,simulation of these two scales in a single geometry ends up with high computation cost; furthermore stiff gas-phase reactions cannot be solved.Accordingly,coupling two simulations with different scales is a solution.Cheimarios et al.coupled finite volume method at macroscale and ballistic method at microscale [1-2].We recently reported that finite element method(FEM)was also available for microscale as well as macroscale,and thereby proposed a multiscale simulation framework with lower computation cost [3-4].In addition,we employed moving boundary method to reproduce time evolution of microstructural shape due to film deposition [4].It was however not applicable to closing of microstructures,and thus we proposed the use of level set method in this work.Besides,as our previous simulation considered only one trench,we developed a way to simulate multiple trenches.