Trenches filling simulations

Figure 2.25 Solution domain and boundary conditions for trench filling simulations (source Ref. [64]).

Figure 2.37 Trench-filling experiments (data points) are compared with shape change simulations (curves) by tracking the evolving height of the deposit along the trench centerline. A vertical transition such as is evident at 15 s for trenches with an aspect ratio of 4, indicates seam or void formation (source Ref. [12]).

The effect of aspect ratio on superfilling and shape of the deposited copper is shown in Figure 3. On the right, the profile evolution in a 0.2 fim trench with aspect ratio of 2 (i.e. the insulator thickness is 0.4 fim) is shown. Figure 3 on the left shows the deposited copper profile in a 0.2 fim trench but with aspect ratio of 5. The parameters used for these simulations are b=17.8 and p=0.25. Both trenches fill well without voids or seams. However, the line with AR of 5 fills up more abruptly than the line with AR of 2 which fills up more sequentially. There is always a timestep in the high aspect ratio trench after which, the line fills from the bottom up. Also, as expected, the shape evolving in the AR of 2 line is more rounded than the shape of copper deposited in the AR of 5 line. 

Figure 2.31 Simulations of leveling during metal solutions are compared. On the left is the quasideposition in 100 nm wide trenches. The leveling steady-state approach where the steady-state agent is assumed to be a large molecule with a value of the current density was used at every diffusion coefficient of 10 7cm2 s. Filling intermediate step. On the right, a domain occurs in 16 s, on the order of the boundary layer decoupled approach was used in order to assess relaxation time, so care must betaken to properly the impact of the transient effects on feature account for transient effects. Two different filling (source Ref. [302]).

Increasing the initial catalyst coverage to 0.05 3 is predicted to result in near optimal superfilling behavior, as shown in Figure 2.36c. Enrichment at the bottom comers leads to rapid formation of first the V-notch and then the nearly flat bottom. As in the other simulations, the advancing bottom surface accelerates further as it collects catalyst from the eliminated sidewall areas. It also exhibits subtle oscillations in shape associated with the continual translation of catalyst from the sidewalls to the bottom surface. The oscillations are also detailed in the analytical solution of feature filling. The catalyst coverage approaches unity as the bottom surface reaches the top of the trench. 

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