Dennis H. van Dorp

Nanoscale Etching and Reoxidation of InAs

At present, the performance enhancement for Si-based transistors can no longer be guaranteed due to intrinsic mobility issues. The considerably higher electron mobility of III-V compound semiconductors (e.g. InGaAs, InAs, InSb) has led to renewed interest and a following phase in the development of future transistors for the 7-5 nm technology node [1].

Unexpected Pyramid Texturization of n-Type Ge (100) via Electrochemical Etching: Bridging Surface Chemistry and Morphology

We report on the (electro) chemical etching behavior, surface morphology and composition of n-type Ge (100) in acidic halide solutions using various analytical and spectroscopic techniques. The use of an integrated (electro) chemical etching chamber connected to X-ray photoelectron spectroscopy instrument to exclude the effect of oxygen from atmosphere is highlighted.

Nanoscale Etching of GaAs and InP in Acidic H2O2 Solution: A Striking Contrast in Kinetics and Surface Chemistry

In this study of nanoscale etching for state-of-the-art device technology the importance of the nature of the surface oxide, is demonstrated for two III-V materials. Etching kinetics for GaAs and InP in acidic solutions of hydrogen peroxide are strikingly different. GaAs etches much faster, while the dependence of the etch rate on the H+ concentration differs markedly for the two semiconductors. Surface analysis techniques provided information on the surface composition after etching: strongly non-stoichiometric porous (hydr)oxides on GaAs and a thin stoichiometric oxide that forms a blocking layer on InP. Reaction schemes are provided that allow one to understand the results, in particular the important difference in etch rate and the contrasting role of chloride in the dissolution of the two semiconductors.

Towards Atomic-Layer-Scale Processing of High Mobility Channel Materials in Acidic Solutions for N5 and N7 Technology Nodes

In this work the etching kinetics of Ge (100) is studied in acidic solutions containing and oxidizing agent. It is shown that the etch rate in the low etch-rate range is controlled by the concentration of the acid, oxidizing agent and the hydrodynamics of the system. The surface termination during etching has strong impact on the etching kinetics. Finally, we discuss the stability of the Ge (100) surface in water and relate this to the low solubility of the Ge suboxides

Watermark Formation on Bare Silicon: Impact of Illumination and Substrate Doping

The wet cleaning process plays an important role in advanced semiconductor industry. Particularly when bare silicon areas are exposed, wafer drying can result in undesired watermark (WM) residues on the surface [1-2]. In principle there are three components effecting the formation, shape and size of WM. 1) composition of the ambient like oxygen concentration, relative humidity and temperature affect WM formation [3]. 2) liquid: factors such as pH and the amount of dissolved species inside the liquid influence the WM composition. 3) substrate: for silicon for instance: surface passivation is important for WM formation [2]. WMs are composed of silica that is formed during the drying process by oxidation of the silicon surface [1]. Therefore when studying WM formation it is important to understand the mechanism (s) of silicon oxidation and the dissolution.

Cleaning of III-V Materials: Surface Chemistry Considerations

Compound semiconductors based on group III and V elements of the periodic system have high charge carrier mobility and are, therefore, candidates for channel material in future CMOS devices [1]. In order to design wet chemical solutions that lead to appropriate surface pre-conditioning and allow for nanoscale processing and minimal substrate loss, a thorough understanding of the interactions between the substrate and the chemical solutions is needed and the basic etching mechanisms needs to be resolved. The focus of this research is on InP in acidic solutions. ESH aspects are also considered.