ALD ruthenium thin film using the metal electrode for trench DRAM capacitor has been researched because the film has not only excellent uniformity also high work function energy of deposited films. Although ALD ruthenium has the good properties, growth of ruthenium has some problems. Especially, in the cause of limitation of ALD ruthenium initial growth with incubation time, thicknesses of deposited ruthenium films showed no linear relation with cyclic numbers. This type of problem is becoming a significant subject in ultra-thin films for metal electrode or gate oxide.

In this work, we examined the correlation of initial growth with interface of deposited ruthenium films. Ruthenium films were prepared by Ru(EtCp)₂ as a ruthenium precursor gas and ammonia as a reactant gas alternately. Ruthenium films were deposited as various source precursor injection in order to be unlike adsorption of ruthenium precursor onto substrate. This study deals with composition and structural behaviors of interface between ruthenium and pure silicon substrate. To investigate surface/interface physical property and impurity of deposited films, EDX, HRTEM, AFM, XPS, Rs measurement and RBS were used. Two deposited ruthenium films were compared including differential initial ruthenium source injection replaced commercial 1 with 10 second for investigation of initial ALD growth. Figure 1 shows HRTEM images of ruthenium films with the above process and the ruthenium films were deposited by ALD cyclic number of totally 100.

Figure 1 HRTEM images of ALD ruthenium films with initial injection source pulse cycle (left) including 25 and (right) including 50

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1. Characterization of ruthenium titanium nitride thin films deposited by rf-direct plasma atomic layer deposition
2. Plasma enhanced atomic layer deposition of titanium oxide passivation layers on polymer substrates