Rj Price

Semiconductor surface etching by halogens: Fundamental steps

Abstract The mechanisms underlying the reaction of halogen molecules with Si(100) have been investigated using the surface probes of thermal desorption spectroscopy (TDS) and Auger electron spectroscopy. The formation of a strongly bound monolayer phase followed by a more weakly held silicon halide corrosion phase has been found to occur even at temperatures as low as 100 K. At these low temperatures further adsorption leads to the formation of a molecular physisorbed halogen overlayer. The reaction products from these adsorbed phases have been characterised and are considered in terms of silicon etching processes. The relevance of the data to beam enhanced etching is discussed.

Surface studies of the interaction of Cl2 with InP(100)(4 × 2); an investigation of adsorption, thermal etching and ion beam assisted processes

The reactions of chlorine on the InP(100)(4 × 2) surface have been investigated using LEED, AES and TDS techniques. Chlorine forms a strongly bound chemisorbed monolayer on the semiconductor surface during low gas exposures. At high gas exposures, bulk corrosion sets in and an In-rich chloride film is formed at the interface which desorbs as InCl 3 . The degree of surface segregation which takes place is found to depend on the chlorine dosing pressures employed and the chemistry exhibited is also very sensitive to the state of the semiconductor surface; on In enriched interfaces corrosion takes place some 300 times more rapidly and InCl rather than InCl 3 is the desorbing product. The surface transformations brought about by low energy ion beams are investigated. Ion beam irradiation sputters InCl and P 4 from the chloride layer and converts the chloride rich corrosion scale into InCl. A mechanism for ion beam assisted etching is proposed and the results compared to previous studies.

Adsorption, etching and photo-induced reactions at the Si(100)-CCl4 interface

The adsorption, thermal and photochemical reactions of carbon tetrachloride on Si(100) were investigated using X-ray photoelectron spectroscopy and thermal desorption spectroscopy. Initial CCl4 adsorption is dissociative at 175 K, with CCl4 multilayer formation at higher exposures. Silicon chlorides are the only thermal desorption products above 300 K. The influence of UV radiation on the desorption products is discussed.

In situ x‐ray photoemission studies of the oxidation of Y‐Ba‐Cu films

X‐ray photoemission has been used to investigate the formation of Y‐Ba‐Cu films on Si(100) and as an in situ probe of their subsequent oxidation to yield the associated oxide ceramic. The layers are prepared by coevaporation of the metallic components under ultrahigh vacuum, and pure alloy phases can be deposited at 300 K; reaction with the underlying substrate resulting in loss of Cu and incorporation by Si in the film takes place, however, at higher temperatures. Room‐temperature oxidation stabilizes the film against this interaction and results in the preferential oxidation and surface segregation of barium at the expense of Cu. This segregation process becomes even more apparent during higher temperature (∼600 K) oxidation reactions. Chemical shifts and associated effects in x‐ray photoelectron spectra are used to infer information on the chemical changes that occur in the film as oxidation proceeds. The thin‐film phases prepared in situ in this work reveal a very similar surface composition to bulk s...

Surface spectroscopic and molecular beam studies of the reactions of trimethylaluminium on Si(100)

The reactions of trimethylaluminium leading to the deposition of Al on Si have been studied using LEED, XPS, AES, TDS and molecular beam scattering. Trimethylaluminium is shown to chemisorb on Si(100) subsequently decomposing to produce CH4(g) and contaminated Al layers. Al catalyses the decomposition reaction and opens up a new reaction channel, resulting in the evolution of C2H2(g).

Surface Reaction Mechanisms in the Metallisation and Etching of Semiconductor Materials.

Surface spectroscopic techniques have been used to investigate aluminium deposition form tri-methyl aluminium (TMA) on Si(100), and the etching of InP by chlorine. Thermal reactions and processes stimulated by UV lamps and ion beams are examined. The results are interpreted in the light of the adsorption states which are formed and the surface transformations of chemical states which are observed to occur.

Thermal and ion-beam-induced etching of InP with chlorine

Surface spectroscopic techniques have been used to investigate adsorption and thermal and ion-induced processes at the InP(100)-Cl2 interface. Two adsorption states are identified and etching reactions are interpreted in terms of surface chemical transformations and desorption processes involving these states.