Experimental study and computer simulation of collimated sputtering of titanium thin films over topographical features

Abstract

An experimental study and computer simulation of collimated sputtering of titanium (Ti) thin films onto submicrometer trenches is presented. The effect of square grid collimators with aspect ratios varying from 0.5 to 2 has been studied. Simulation of collimated sputtering involves the combination of the simulation of sputter distributions vapor transport model and the simulation by ballistic deposition film growth model. This combination is able to simulate the effect of collimation on the spatial and angular distributions of deposited atoms, and is able to predict the film coverage, deposition rate change, and microstructure of the deposited films. Both experimental and simulation results show that bottom coverage in trenches of aspect ratio 1.2 can be significantly improved from 50% to more than 80% using collimation. However, a penalty is paid by a corresponding decrease in deposition rate down to 15% of the uncollimated value. Additionally, the microstructure (grain size and orientation) is altered by collimation. The good agreement between the simulation and experimental results indicates that the model will be very useful for predicting and optimizing the properties of films deposited by collimated sputtering over topographical features.

Enhancement of Ti+density in high-pressure magnetron sputtering plasmas

“…A number of methods for improving deposition profiles inside fine patterns have been reported. They are collimated sputter deposition [5,6], long-throw sputter deposition [7,8] and ionized physical vapour deposition (IPVD) [2,9]. The common concept of these techniques is to improve the directionality of depositing radicals.…”

Void formation during film growth: A molecular dynamics simulation study

“…Our goal is the clear elucidation of void formation mechanisms and the factors that influence them. Several authors [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] have demonstrated the value of applying detailed atomistic computer simulations to the study of thin film deposition. Simulations based on Monte Carlo ͑MC͒, MD, and ballistic deposition have all been applied for this purpose.…”

“…The atoms are assumed to either reflect from the surface, stick where they hit, or locally relax into the cradle site closest to the point of impact. 3,4 This approach typically neglects the dynamics and transport of the deposited atom once it impinges upon the surface. Liu et al 3 have used the ballistic deposition treatment in the SIMBAD program to study several basic aspects of microstructural formation ͑e.g., grain size, orientation͒ of films grown over topographical features such as grooves in thin film metallization in integrated circuits.…”

An analysis of the role of high energy neutral bombardment in longthrow/collimated sputtering of refractory metal barrier layers

“…[3][4][5] This filter consists of a periodic lattice of holes which filters out the oblique adatom flux and narrows the angular distribution of the flux striking the wafer. The effectiveness of this technique is determined primarily by the geometry of the collimator and its position in the system.…”