Demonstration of Sputtering Atomic Layer Augmented Deposition: Aluminum Oxide–Copper Dielectric–Metal Nanocomposite Thin Films

Abstract

Designing a thin film structure often begins with choosing a specific yet conventional film deposition method. In other words, a film deposition system in which two deposition methods complementary one another are physically yet practically hybridized should lead us to new ways of designing thin film structures with structural complexity controlled at a level that has never been envisioned. This premise inspired us to uniquely combine atomic layer deposition (ALD) and magnetron sputtering (SPU) within a single deposition chamber; the combined film deposition system is referred to as sputtering atomic layer augmented deposition (SALAD). SALAD allows us to take full advantages of both ALD's ensuring precise and accurate delivery of precursors and SPU's offering versatility in choosing a chemical element. A SALAD system was designed based on knowledge obtained by computational fluid dynamics with the goal of conceiving a film deposition system that satisfied deposition conditions distinctive for both ALD and SPU, and a prototype SALAD system was assembled by employing off-the-shelf vacuum components. As a demonstration, the SALAD system was utilized to deposit a unique nanocomposite made of a stack of aluminum oxide thin films by ALD and copper thin films by SPU -AlOx-Cu nanocompositeon a Si substrate. Spectroscopic reflectivity collected on the AlOx-Cu nanocomposite shows unique dispersion features to which conventional effective medium theories used for describing optical properties of composites made of a dielectric host that contains metallic inclusions do not seem to simply apply.

Transfer Matrix Modeling Optical Properties of Short-Period Aluminum Oxide-Copper Multi-Layered Nanocomposites

“…Research involving the intersection of diverse disciplines has often uncovered unique phenomena tied to the quantum characteristics of materials. Giraldo et al stated that the refinement of synthesis techniques is undervalued, yet, engineering methods can produce materials with unprecedented structural intricacies [1]. Thus, Giraldo et al used a hybrid thin-film deposition system, termed sputtering atomic layer augmented deposition (SALAD), which is based on both sputtering, physical vapor deposition (SPU), and atomic layer deposition, chemical vapor deposition (ALD) techniques [1].…”

“…Giraldo et al stated that the refinement of synthesis techniques is undervalued, yet, engineering methods can produce materials with unprecedented structural intricacies [1]. Thus, Giraldo et al used a hybrid thin-film deposition system, termed sputtering atomic layer augmented deposition (SALAD), which is based on both sputtering, physical vapor deposition (SPU), and atomic layer deposition, chemical vapor deposition (ALD) techniques [1]. They used this technique whereas in traditional systems, SPU and ALD operate separately or in cluster tools specifically designed for either SPU or ALD [1].…”

“…Thus, Giraldo et al used a hybrid thin-film deposition system, termed sputtering atomic layer augmented deposition (SALAD), which is based on both sputtering, physical vapor deposition (SPU), and atomic layer deposition, chemical vapor deposition (ALD) techniques [1]. They used this technique whereas in traditional systems, SPU and ALD operate separately or in cluster tools specifically designed for either SPU or ALD [1]. This new approach allows SPU and ALD to function in the same environment, enabling near-simultaneous or consecutive processes, even though these two deposition methods are typically seen as incompatible [1].…”

“…They used this technique whereas in traditional systems, SPU and ALD operate separately or in cluster tools specifically designed for either SPU or ALD [1]. This new approach allows SPU and ALD to function in the same environment, enabling near-simultaneous or consecutive processes, even though these two deposition methods are typically seen as incompatible [1]. This approach shows a novel application that could not be produced before.…”

“…A demonstration of the special capabilities of SALAD is a thin-film configuration, which is made up of aluminum oxide (AlOx) and copper (Cu); in order to emphasize the unique capabilities of SALAD in combining thin-film materials that are typically challenging to prepare using a singular deposition method like SPU or ALD, AlOx, and Cu were specifically selected, as Cu is widely used in ALD [1][2][3][4]. In the SALAD system, using SPU puts down material quickly, making it hard to control the exact thickness, which also varies with applied voltage [1]. ALD, on the other hand, always puts down one atom layer every cycle, so the total thickness is very easy to control [1].…”