The Production of Porous Structures on Si, Ge and GaAs by High Dose Ion Implantation
- PDF / 360,833 Bytes
- 6 Pages / 420.48 x 639 pts Page_size
- 20 Downloads / 245 Views
THE PRODUCTION OF POROUS STRUCTURES ON Si, IMPLANTATION.
Ge AND GaAs BY HIGH DOSE ION
J.S. WILLIAMS*, D.J. CHIVERS*t, R.G. ELLIMAN*O, S.T. JOHNSON*, E.M. LAWSON** I.V. MITCHELL*O, K.G. ORRMAN-ROSSITER, A.P. POGANY*, AND K.T. SHORT* *Microelectronics Technology Centre, RMIT, Melbourne 3000 Australia; **AAEC Lucas Heights, Australia; t Present address: AERE Harwell, England ýJoint appointment with CSIRO Division of Chemical Physics, Clayton 3168 Australia: e Permanent address: CRNL Chalk River, Canada.
ABSTRACT This paper presents new data on the previously observed porous structures which can be developed in high dose, ion implanted Ge. In addition, we provide strong evidence to suggest that such porous structures can be formed in high dose, ion implanted Si and GaAs substrates under particular implant conditions. Comparison of the various systems using RBS analysis indicates that heavy ion doses as low 14 2 as 10 Mc- can give rise to such structural modific15 2 ations in GaAs, whereas doses of 10 cMare needed to observe an effect with Ge and doses usually exceed6 2 ing 101 cmare required for Si.
INTRODUCTION Recent studies - 4] have shown that high dose implantation of heavy ions into Ge can lead to near-surface structural modifications which result in the formation of highly porous surface layers under certain implantation conditions. Such porous layers have been identified by both TEML1,4](where the porous layer is observed to be essentially amorphous) and SEM[21. Furthermore, the surfaces of these specimens appear black to the naked eye, even while the samples are still under vacuum in the implantation chamber. Upon exposure to air, the porous structure is found to absorb high concentrations (>20 atom % in some cases) of light impurities such as oxygen and carbon. These porous, contaminated surface layers give rise to a Ge yield deficit in Rutherford backscattering spectra~l,3]and this yield deficit extends over a depth corresponding to the thickness of the implanted layer. Studies to date~l,3,4] have indicated that the degree of porosity is sensitive to the implant temperature, the implant mass and dose. These porous, contaminated layers cannot be recrystallised to good quality single crystal during subsequent furnace heating. In a recent reportL53 we have indicated that the development of porous structures during high dose implantation of Si may also occur under certain bombardment conditions. No such effects have been reported in GaAs studies. In this paper, we report on further experiments in Ge, designed to provide more detail on the temperature dependence of implantation-induced structural modifications and to investigate the subsequent annealing behaviour. We provide strong evidence to suggest that porous, amorphous structures can also occur in both Si and GaAs substrates during high dose implantation, under appropriate conditions.
Mat. Res. Soc.
Symp. Proc. Vol.
27 (1984) QElsevier Science Publishing Co.,
Inc.
206
EXPERIMENTAL In the present study, p-type (100) Ge slices were implanted with 80
Data Loading...