Ellipsometric Characterization of Si Surface Damage Induced by Sputter Etching

Abstract

Surface characterization using spectroscopic ellipsometry is applied to sputter etched Si surfaces. It is elucidated by spectrum measurement that broadening of the refractive index spectrum occurs due to crystal damage induced by sputter etching. As more damage is introduced by increasing the rf power, the spectrum peaks in n and k are broadened, and especially for the extinction coefficient k. Thus, the extinction value can be a measure of the degree of damage. For crystal damage evaluation, ellipsometric measurement at a wavelength of 4200-4500]~ is effective and reasonable. Comparing the results of ellipsometry with those of RHEED patterns and electrical properties, it is verified that the degree of broadening is compatible with that of blurring in RHEED patterns and increase in leakage current in Schottky type diodes constructed on the etched surfaces. It is concluded that surface quality can be assessed numerically by measuring the change in refractive index.

An Overview of Dry Etching Damage and Contamination Effects

“…Techniques, which offer more potential for routine assessment of dry etching damage, have also been examined. These include ellipsometry (23,24,36), which has been employed in situ, spectroscopic ellipsometry (34,62), and the therma-wave technique (52,63). Some thermawave (TW) data are shown in Fig.…”

“…Dry etching techniques such as reactive ion etching (RIE), magnetron reactive ion etching (MRIE), plasma etching (PE), ion beam etching (IBE), electron cyclotron resonance (ECR) etching, and reactive ion beam etching (RIBE) can cause damage and contamination effects in exposed materials (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14). In fact, damage is often inherent in these processes due to the presence of ion bombardment, which can create bonding damage in semiconductors and insulators (1-9, 11, 13), as well as due to the presence of UV radiation, which can create bonding damage in insulators (10).…”

Characterization and Control of Silicon Surface Modification Produced by CCl4 Reactive Ion Etching

“…When residue layers are present--as they are for some RIE chemistries (1, 15)--they can dominate the electrical characterization of metal-semiconductor contacts to etched Si surfaces. Phenomenologically, they appear, both for n-and p-type Si, as a resistance in series with the contact; this resistance can overshadow electrical property changes occurring in the silicon near-surface regions (14). As we will see, the barrier height changes arising in the near-surface region are clearly observable for CC14etched surfaces, and there is no discernable series resistance caused by the RIE exposure.…”

“…We have seen similar ring RHEED patterns indicative of the formation of polycrystalline silicon for inert gas IBE. Ohira has also used RHEED to characterize inert gas ion etching (14). In that case, a ring pattern was not observed; rather, the pattern was hazy, which is indicative of an amorphous layer.…”

Highly Sensitive Impurity Analysis of GaAs Using SIMS and Chemical Preparation

“…Manuscript submitted June 10, 1985; revised manuscript received Oct. 14, 1985." This was Paper 453 presented at the New Orleans, Louisiana, Meeting of the Society, Oct. [7][8][9][10][11][12] 1984.…”