Etching Of Metal Films Research Articles

Formation of AlFx Gaseous Phases during High Temperature Etching: A Reactive Force Field Based Molecular Dynamics Study

The progress of research focused upon the etching of metal films or substrates using fluorine gases has been restricted by limited information regarding etching reactants and byproducts. Indeed, aspects of the etching mechanism itself remain unclear. In this study, a new reactive force field (ReaxFF) for Al–F was developed to describe the interaction and reactions in Al–F materials. The ReaxFF accurately reproduces the quantum mechanics derived training set for structures and energies of gaseous AlFx molecules and Al–F crystals. Based on this Al–F ReaxFF, the effects of chemical source (F/Al = 1–6) and temperature (1000–1500 K) on the etching product and rate were studied. The formation of gaseous AlFx was revealed in five steps with the fluorine concentration being the prime factor affecting the etching products. Below the critical concentration ratio of F/Al = 3, where the chemical driving force is insufficient, only four of the five steps occur and a AlFx cluster is formed without significant gaseous s...

Low energy selective etching of metal films in oxygen-containing high-density argon plasma

The results of investigating the influence of the ion energy (Ei < 200 eV) on the etching of nanoscale Cu, Pt, Ta, and Ti films in an oxygen-containing high-density argon plasma of low-pressure (P < 0.4 Pa) inductive high-frequency (HF) discharges are presented. It is demonstrated that, in Ar plasma, the selective etching of metal films is achieved at ion energies close to the sputtering threshold. The selectivity of Cu, Pt, and Ta etching with respect to Ti etching increases sharply in Ar/O2 plasma with a small (less than 5%) oxygen addition. Depending on the energy of incident Ar+ ions, the yields of Ta, Pt, and Cu sputtering in Ar plasma are in good agreement with semiempirical calculations.

Modeling and simulation of feature-size-dependent etching of metal stacks

Aspect ratio dependent etching (ARDE) has often been observed in various etching processes. During etching of metal films in a high density plasma reactor, this phenomenon is more prominent. With a high amount of ARDE present, the narrow spaces will not be cleared unless there is enough overetch, which removes an excessive amount of the underlying layers. The main focus of this article is on the understanding of the mechanisms behind metal ARDE. The results from an extensive design of experiments on the subject were utilized for this study. SPEEDIE, the Stanford etching and deposition profile simulator, was used to develop and test appropriate models. The Langmuir adsorption model with added surface recombination of the adsorbed species, both etchants and inhibitors, was used to model the phenomenon. The added surface recombination acts as the major species loss mechanism on the feature sidewalls. The simulation results indicate that a process with inhibitors, which are highly adhesive to the metal surface and which do not like to recombine with the etchants to form volatile products, will lead to a low degree of ARDE. This is in agreement with experimental results which showed that the addition of CHF3 to the Al etch process helps to reduce the ARDE in narrow space regions.

Visible-laser photochemical etching of Cr, Mo, and W

Direct halogen etching of metal films by laser-induced photochemical and thermal processes at submicrometer resolution is described. The regimes in which each of the processes is prevalent are readily observed. In addition to direct definition of metal patterns, the etched metal films serve as durable resist layers for conventional etching processes. Cl2 is photochemically dissociated at low laser power density levels, enabling direct-write etching of Cr, Mo, and W films on fragile substrates. NF3-assisted etching is dominated by thermal reactions.

Local plasma oxidation and reactive ion etching of metal films for ultrafine line pattern inversion and transfer

A new ultrafine line pattern inversion and transfer technique based on local low temperature plasma oxidation and reactive ion etching of suitable metal films, such as aluminum, is presented. The patterned surface oxidized metal film may serve as a surface passivated interconnect or gate structure for integrated semiconductor devices, or be used as an etch mark for underlying layers. As an application a process for patterning self‐aligned two layer gate lines composed of molybdenum silicide and polycrystalline silicon is given. Linewidths as small as 1500 A have been achieved.