M. K. El-Ghor

Evaluation of Secco etch technique for determination of dislocation densities in SIMOX wafers

The authors report on an extensive study of a Secco etch process for determining dislocation densities that was performed by three different groups using nine SIMOX (separation by implanted oxygen) wafers from the same lot. The average dislocation density across the entire current data set (except transmission electron microscopy, TEM) is 2.2*10/sup 6//cm/sup 2/ with a standard deviation of 1.0*10/sup 6//cm/sup 2/. Most of the data points are in the low 10/sup 6/ dislocations/cm/sup 2/ range, in agreement with the TEM results, and indicate good consistency of results from facility to facility.<<ETX>>

A closed form analytic model for separation by implantation of oxygen oxide growth using a joined‐Gaussian approximation

A closed form analytic solution to the growth characteristics of the separation by implantation of oxygen (SIMOX) buried oxide and silicon film, based on a two‐sided Gaussian approximation to the oxygen implant profile in the SIMOX process, is presented. The model used includes the effects of substrate swelling and sputtering due to the implanted oxygen, as well as the effects of saturation of the oxygen density at the stoichiometric SiO2 level in the implanted region. The results of this investigation show that for typical SIMOX implant conditions currently used in high‐current implanters, the total dose of oxygen required to first reach the saturation level is only slightly dependent on the swelling and sputtering effects associated with the oxygen implantation, and that the deviation of the location of the first saturation point from the commonly used implant range can be significantly affected by the implant profile. In addition, it is shown that a ‘‘natural parameter’’ GNsat, where G is the net growt...

Effect of particles on buried oxide defects in SIMOX material

An array of artificial particles composed of silicon dioxide was created by growing a film of SiO/sub 2/ one micron thick on a wafer surface, then patterning and etching the film to create barriers of various sizes and shapes. Two of the more interesting of these shapes are long lines and individual dots. These lines make it practical to analyze the structures by cross-sectional scanning and transmission electron microscopy. The shape of one of the lines after implantation to a dose of 1.8*10/sup 18/ at an implantation temperature of 630 degrees C is shown.<<ETX>>

An analytic solution to SIMOX oxygen implant profiles using joined half-Gaussian distributions

The authors describe the results of an analytic investigation of SIMOX (separation by implanted oxygen) oxide/silicon profiles using a joined half-Gaussian approximation to the instantaneous oxygen implant distribution. The advantage of this approach over computer-generated solutions is that it provides an easy way to see the effects of variations in the physical parameters of the implant process on variations in the features of the resulting SIMOX materials. These results can then be used to relate variations in SIMOX fabrication parameters to resulting variations in final device performance. It is shown that a dimensionless parameter which can be used to gauge several significant features of the implant process is the product of the extension of the silicon surface due to volume expansion from the implanted oxygen and the saturation value of oxygen in the resulting buried oxide.<<ETX>>

Evolution of Buried Oxide “Pipe” Defects Upon Implantation Through Particles in Simox Material

We have investigated the effect of the presence of oxide particles on the surface of silicon wafers during high energy, high dose implantation of oxygen into silicon. It was found that for single implants with doses of 1.5 × 10 18 /cm 2 or 1.8 × 10 18 /cm 2 , such particles produce a non-continuous buried oxide layer in the as-implanted condition as well as after annealing. Etching results showed that no defects, which formed etchable paths through the buried oxide, were produced for particles with diameters 0.43 um or below for the lower dose and 0.53 um for the higher dose.