Dry Etching of Indium Phosphide
- PDF / 858,438 Bytes
- 6 Pages / 420.48 x 639 pts Page_size
- 14 Downloads / 282 Views
DRY ETCHING OF INDIUM PHOSPHIDE P. BOND*, D. SENGUPTA*, KEVIN G. ORRMAN-ROSSITER*, G. K. REEVES* and P. J. K. PATERSON** *Microelectronic and Materials Technology Centre, Royal Melbourne Institute of Technology, GPO Box 2476V, Melbourne 3001, Vic, Australia "**Departmentof Applied Physics, RMIT, GPO Box 2476V, Melbourne 3001, Vic, Australia ABSTRACT Indium Phosphide (InP) based multilayer structures are becoming increasingly important in the semiconductor industry with optoelectronic applications being the main growth area. Mesa type structures with finely controlled width and etch angle, often form the building blocks for many of these photonic devices. Traditional wet etching techniques have often proved to be inadequate for the required anisotropic removal of material. This paper presents the results of etching semi-insulating InP(100) using a combination of an Argon ion beam and a reactive gas, CCI2 F2 (Freon 12). It was found that the etch rate was enhanced by increasing the ion energy and by the addition of CC12 F2 . Auger electron spectroscopy revealed that the increased etch rate was accompanied by an increase in the surface indium concentration and at low ion beam energies carbon build-up retarded the etch rate. The optimum etch angle to fabricate 3psm waveguides was found to be 220 to the surface normal, however Schottky contacts to these structures were unsuccessful. INTRODUCTION The dry etching process [1] is ideally suited for the controlled anisotropic etching required in most optoelectronic devices. This is a low pressure process, which removes surface material via low energy ion sputtering or by the creation and subsequent evaporation (or ion stimulated processes) of volatile compounds formed on the surface from the introduction of a reactive gas species. Usually a combination of these two processes is used. When the reactive gas is introduced via the ion source, the technique is generally known as reactive ion beam etching (RIBE). A major problem in dry etching of InP stems from the fact that most Indium compounds tend to have a lower vapour pressure than corresponding phosphorus compounds [3]. Attempts at (non-reactive) ion beam etching of InP have often resulted in unacceptable surface damage and in some cases the formation of Indium droplets [2]. The alternative RIBE technique has been used successfully with either halogen based [4] or hydrocarbon based reactant gases [5]. By introducing the reactive gas close to the surface a better etch control can be achieved compared to conventional RIBE as the ion flux and the reactant gas flow can be controlled separately, this technique can be called chemically assisted ion beam etching (CAIBE). This paper presents the results of etching semi-insulating InP(100) using a combination of an Argon ion beam and a reactive gas, CCl 2F2 (Freon 12). The effect of gas flow rates and other parameters on the speed and quality of etching was studied. Auger electron spectroscopy (AES) and Rutherford backscattering and channelling (RBS-C) were used to gain information
Data Loading...
