Generating high-efficiency neutral beams by using negative ions in an inductively coupled plasma source

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1 Generating high-efficiency neutral beams by using negative ions in an inductively coupled plasma source Seiji Samukawa a) and Keisuke Sakamoto Institute of Fluid Science, Tohoku University, Katahira, Aoba-ku, Sendai, Miyagi , Japan Katsunori Ichiki Ebara Research Co., Ltd., Honfujisawa, Fujisawa, Kanagawa , Japan Received 10 December 2001; accepted 20 May 2002 To minimize radiation damage caused by charge buildup or ultraviolet and x-ray photons during etching, we developed a high-performance neutral-beam etching system. The neutral-beam source consists of an inductively coupled plasma ICP source and parallel top and bottom carbon plates. The bottom carbon plate has numerous apertures for extracting neutral beams from the plasma. When a direct current dc bias is applied to the top and bottom plates, the generated positive or negative ions are accelerated toward the bottom plate. Most of them are then efficiently converted into neutral atoms, either by neutralization in charge-transfer collisions with gas molecules during ion transport and with the aperture sidewalls in the bottom plate, or by recombination with low-energy electrons near the end of the bottom plate. We found that negative ions are more efficiently converted into neutral atoms than positive ions. The neutralization efficiency of negative ions was almost 100%, and the maximum neutral flux density was equivalent to 4.0 ma/cm 2.A neutral beam can thus be efficiently produced from the ICP source and apertures in our new neutral-beam source American Vacuum Society. DOI: / I. INTRODUCTION Recent ultralarge-scale integration production processes involve fabricating sub-0.1 m patterns on Si wafers. Highdensity plasma sources, such as inductively coupled plasma ICP and electron-cyclotron-resonance plasma, are key technologies for developing precise etching processes. The disadvantages of these technologies include several types of radiation damage caused by the charge buildup of positive ions and electrons 1 4 or by ultraviolet and x-ray photons 5 10 during etching. These are very serious problems that must be overcome in the fabrication of future nanoscale devices. To overcome these problems and achieve accurate nanoscale patterning, a high-performance neutral-beam etching system is required. However, previous neutral-beam sources have not been practical for plasma processing 11,12 because of their low etching rates and low selectivity. As a result, there have been few studies on highly efficient generation of neutral beams with controllable beam energy ranging from a few ten to a few hundred electron volts for high-performance, damage-free etching. We developed a highly efficient neutral-beam source by combining an ICP source and parallel plates supplied with a direct-current dc bias for ion acceleration. In this article, we describe the fundamental characteristics of this new source. II. EXPERIMENT The neutral-beam source we developed consists of an ICP source and parallel top and bottom carbon plates Fig The diameter and length of the quartz tube for the ICP source a Electronic mail: samukawa@ifs.tohoku.ac.jp are 10 and 25 cm, respectively. The process chamber is separated from the plasma chamber by the bottom carbon plate, because carbon has the lowest sputtering yield under highenergy ion bombardment and does not contaminate semiconductor devices. There are many apertures in the bottom carbon plate to extract neutral beams from the plasma in the process chamber. In our experiment, the aperture open area was fixed at 50% within a 100 mm in diameter area of the bottom carbon plate to maintain the same discharge pressure in the ICP source. The aperture diameter and length were changed from 3 to 1 mm and from 5 to 10 mm, respectively, in order to investigate the neutralization efficiency of the extracted neutral beams. To prevent the extraction of electrons from the plasma into the process chamber, especially, in a continuous discharge, a magnetic filter about 100 G could be placed just under the bottom plate. When a magnetic filter is used, only ions both positive and negative are extracted from the plasma into the process chamber. Argon Ar and SF 6 gases were injected into the plasma chamber from the top carbon plate. The radio frequency rf: MHz power was fixed at 500 W peak power for continuous-wave cw and pulsed-plasma operation. The power was modulated at 50 s to generate a large number of negative ions in the pulsed SF 6 plasma. The pressure in the plasma chamber and that in the process chamber were 1 and 0.1 Pa, respectively. In the plasma chamber, the generated ions underwent frequent collisions with gas molecules. Conversely, the extracted beams were transported with a collimated trajectory because of the long mean-free path. When a positive dc bias was supplied to the top carbon plate, the generated positive ions were accelerated from the top plate toward the bottom plate in both cw and pulsed discharges. When a negative dc bias was applied to the top plate, the 1566 J. Vac. Sci. Technol. A 20 5, SepÕOct Õ2002Õ20 5 Õ1566Õ8Õ$ American Vacuum Society 1566

2 1567 Samukawa, Sakamoto, and Ichiki: Generating high-efficiency neutral beams 1567 FIG. 2. Measurement system for neutralization efficiency. The measurement system for neutralization efficiency consisted of a Mo target and an ion deflector. As the motion of the residual ions is distorted by the applied potential at the deflector, the beam neutralization efficiency was calculated using the values for the secondary electron current measured with the deflector both on and off. FIG. 1. Newly developed neutral beam generation system. It consists of an ICP source, and top and bottom carbon parallel plates. There are many apertures in the bottom carbon plate to extract neutral beams from the plasma in the process chamber. a Usually, a magnetic filter was not used. b To prevent the extraction of electrons from the plasma into the process chamber, especially, in the continuous discharge, a magnetic filter about 100 G could be placed just under the bottom plate. negative ions in the pulsed SF 6 plasma were accelerated toward the bottom plate. Most of these ions were converted into neutral atoms by neutralization in the charge-transfer collisions with gas molecules during ion transport. The rest of the ions were neutralized by collisions with gas molecules and the aperture sidewalls while passing through the bottom plate, or by recombination with low-energy electrons near the end of the bottom plate. In this experiment, we investigated the beam current density expressed as an ion-equivalent current and beam neutralization efficiency the proportion of neutral particles in the beam to characterize the performance of the new neutral-beam source. The neutralization efficiency of the negative ions was compared with that of the positive ions in the pulsed SF 6 plasma. The residual ion current density was measured using a Faraday cup under all conditions. To obtain the beam neutralization efficiency, we measured the secondary electron current and temperature increases during the bombardment of a target with ions and energetic neutral particles. The measurement system for the secondary electron current consisted of a Mo target and an ion deflector Fig. 2. Some of the extracted ions and neutral particles passed through the deflector 3 mm into an analyzer for secondary electron currents. The analyzer region did not have differential pumping, because the mean-free path was longer than the beam transport in the analyzer. The secondary electron current was generated by bombarding the Mo target with residual ions and neutral beams of more than 500 ev in the Ar plasma. 14 The current entering the target was measured with the deflector both on and off. Because the motion of residual ions was distorted by the potential of 300 V applied at the deflector, only the neutral particles in the beam bombarded the target. The yield of secondary electrons from a target surface under the bombardment by Ar ions or energetic Ar atoms is well known, 14 and the flux of bombarding ions and neutral particles can be estimated. Consequently, the beam neutralization efficiency was calculated by using the values for the secondary electron current measured with the deflector both on and off. Basically, the Mo target was located 11.5 cm from the bottom carbon plate, but it was moved to other position the position 2 to 15 cm from the bottom plate to investigate the dependence of neutralization efficiency of the distance from the bottom plate. We used this measurement method to compare the neutralization efficiency with the value in a previous report, 11,12 but the method can only be used for Ar ions and Ar atom beams of more than 500 ev. To estimate the neutralization efficiency for lower energy beams of less than 500 ev in Ar and SF 6 plasmas, a calorimeter was used. A small piece of Al foil was bombarded with energetic neutral particles and ions. The temperature of the Al foil was then measured using a JVST A - Vacuum, Surfaces, and Films

3 1568 Samukawa, Sakamoto, and Ichiki: Generating high-efficiency neutral beams 1568 FIG. 3. Measurement techniques and their placement in our neutral-beam system. thermocouple. The speed of the temperature increase was converted into the beam flux. Because the ion deflector was set up on the calorimeter to distort residual ions, the beam neutralization efficiency could also be calculated using the values for the speed of the temperature increase with the deflector on and off. The position of the calorimeter was fixed at 11.5 cm from the bottom carbon plate. From the values of neutralization efficiency (E %) and residual ion current density (I i ma/cm 2 ), the neutral beam flux expressed as an ion-equivalent current I i /(100 E/100) was calculated. Additionally, a quadruple mass spectroscope QMS with an energy analyzer was used to observe the residual ions and beam energy distribution in the process chamber. The QMS sampling aperture was placed 50 cm from the bottom carbon plate. The measurement techniques and their placement relative to the rest of the system are shown in Fig. 3. To investigate the etching characteristics with the new neutral-beam source, nondoped poly-si 1500 A thick was deposited on a substrate, 6 in., in diameter. The substrate was placed 2 cm from the bottom carbon plate in the process chamber. III. RESULTS AND DISCUSSION The ion current density and the beam neutralization efficiency were measured in the Ar plasma by changing the aperture diameter and length in the bottom carbon plate, as shown in Fig. 4. Under these conditions, a magnetic filter 100 G to prevent the extraction of electrons from the plasma into the process chamber was not used. The measurement area was 11.5 cm from the bottom plate. In the plasma source, the plasma density measured by a Langmuir probe was cm 3. A dc bias of 700 V was applied to the top carbon plate, while the bottom plate was connected to ground. Under these conditions, the energy of the residual ions determined by using an ion-energy analyzer ranged FIG. 4. Ion current density and the beam neutralization efficiency in Ar plasma as a function of aperture diameter and aperture length in the bottom carbon plate. The measurement position was 11.5 cm from the bottom carbon plate. The plasma density was measured to be cm 3 and the dc bias of 700 V was supplied to the top carbon plate to obtain high-energy ions of more than 500 ev. from 500 to 650 ev peak energy: 600 ev. We speculate that the incident peak energy of the neutral beams was also around 600 ev. 12 Reducing the aperture diameter and increasing the aperture length in the bottom carbon plate significantly increased the neutralization efficiency. As a result, it also resulted in a decrease in the ion current density. We believe that this was due to an increase in the number of charge-transfer collisions of ions with gas molecules and aperture sidewalls in the bottom plate. The neutralization efficiency was 85%, even when we used a low-aspect aperture, 3 mm in diameter and 5 mm thick. This suggests that most ions around 85% were neutralized during ion transport between the top and bottom plates in the ICP source, and the rest 20% were neutralized in charge-transfer collisions when the ions were passing through the apertures in the bottom carbon plate. When the aperture diameter and length were 1 and 10 mm, respectively, the neutralization efficiency was more than 95%. To clarify the effect of extracted electrons on beam neutralization in the process chamber, the neutralization efficiency was also investigated under the same conditions with a magnetic filter about 100 G just under the bottom plate. We obtained the same efficiency as without the magnetic filter. This suggests that electrons are almost completely confined by the sheath potential in high-aspect apertures, and that only neutral beams can be extracted from the plasma in J. Vac. Sci. Technol. A, Vol. 20, No. 5, SepÕOct 2002

4 1569 Samukawa, Sakamoto, and Ichiki: Generating high-efficiency neutral beams 1569 FIG. 5. Dependence of neutralization efficiency on the distance from the bottom plate in Ar plasma. The plasma density was measured to be cm 3 and the dc bias of 700 V was supplied to the top carbon plate to obtain high-energy ions of more than 500 ev. FIG. 6. Dependence of neutralization efficiency on the top-plate dc bias in Ar and SF 6 plasmas using the calorimeter. The top-plate dc bias was changed from 0 to 700 V. The neutralization efficiency strongly depends on the top-plate dc bias, especially in SF 6 plasma. the process chamber. The calculated neutral flux density was thus equivalent to 1.2 ma/cm 2. This value is larger than the values reported previously for neutral-beam sources even at low beam-acceleration voltages. 11,12 The dependence of neutralization efficiency on the distance from the bottom carbon plate was also investigated without using a magnetic filter Fig. 5. The neutralization efficiency measured 2 cm from the bottom carbon plate in the process chamber was 95%. Because there was no neutralization in the process chamber, neutral beams could only be efficiently produced as a result of ions and neutral particles passing through the ICP source and apertures in the bottom plate. Thus, with this system, extremely high-density neutral beams equivalent to 2.8 ma/cm 2 of around 600 ev can be radiated to a substrate 2 cm from the bottom plate, while maintaining a high neutralization efficiency of more than 95%. For actual etching processes, low-energy neutral beams of less than 100 ev are also required. The dependence of neutralization efficiency on the top-plate dc bias was measured in the Ar and SF 6 plasmas by using a calorimeter Fig. 6.A magnetic filter was not used in this experiment. The dc bias was changed from 100 to 700 V, while the bottom plate was connected to ground. For the Ar plasma with a dc bias of 700 V, the portion of neutralization efficiency due to the temperature increase in the calorimeter corresponded to the portion due to the secondary electron current of the Mo target. This suggests that a calorimeter can be used to calculate the neutralization efficiency under actual process conditions. The neutralization efficiency strongly depended on the topplate dc bias, especially in the SF 6 plasma. We believe the cross-section of ion neutralization changed significantly as a function of the accelerated ion energy, and lower neutralization efficiency was observed in the high-energy region when the top-plate dc bias was more than 300 V. In particular, we speculate that a large number of ions with lower molecular weight F ions caused a strong dependence of neutralization efficiency on the top-plate dc bias in the SF 6 plasma. Even for the SF 6 plasma, we found that lower energy ions when the top-plate dc bias was around 100 V were very effectively with 90% efficiency converted into neutral beams. Under these conditions, the incident energy of the residual ions ranged from 60 to 75 ev peak energy: 70 ev, and the incident energy of the neutral beams is speculated to have been almost the same. In actual etching processes, the beam energy distribution must be precisely controlled by optimizing the pressure and dc bias applied to the top and bottom plates. These results show that high-density, energycontrolled neutral beams can be generated using our system. To compare the neutralization efficiency of negative and positive ions, the top-plate dc bias for the pulsed SF 6 plasma was changed from 700 to 700 V, while the bottom plate was connected to ground Fig. 7. In this experiment, no magnetic filter was used, because we obtained the same neutralization efficiency with a magnetic filter as without one. This suggests that electrons almost completely disappeared FIG. 7. Dependence of neutralization efficiency on top-plate dc bias in pulsed SF 6 plasma. The bottom plate was connected to ground potential. To estimate the neutralization efficiency of lower energy beams in SF 6 plasmas, a calorimeter was used. JVST A - Vacuum, Surfaces, and Films

5 1570 Samukawa, Sakamoto, and Ichiki: Generating high-efficiency neutral beams 1570 FIG. 8. Residual negative ion and its energy distribution in the process chamber using a QMS. The top-plate dc bias was fixed at 100 V. The bottom plate was connected to ground potential. through dissociative attachment in the afterglow of the SF 6 plasma, and that only ions and neutral beams can be extracted from the plasma in the process chamber. The neutralization efficiency strongly depended on the top-plate dc bias: when it was more than 100 V, the neutralization efficiency was no more than 50%. Conversely, when a negative dc bias ranging from 0 to 700 V was applied to the bottom plate, the neutralization efficiency was more than 75% throughout the whole range of bias conditions. Because the positive ion density was almost same as the negative ion density in the pulsed SF 6 plasma due to maintained charge neutrality, these results suggest that negative ions are more efficiently neutralized than positive ions while passing through the ICP and apertures in the bottom plate. Attached electrons can easily be detached from negative ions transported from the plasma chamber to the process chamber. The residual negative ions and their energy distribution were detected using the QMS with an energy analyzer, as shown in Fig. 8. Although it is very difficult for the QMS conditions to directly correspond to the etching conditions on the substrate because of the large difference in the distance from the bottom plate to the substrate and from the bottom plate to the QMS, this result roughly shows what the main species of neutral beams are, and what the order of neutral beam energy is. A large number of F ions peak energy: 15 ev were clearly observed. It is thus possible that the neutral beams were mainly generated by the neutralization of negative ions (F ) in the pulsed SF 6 plasma. The incident energy of the neutral beams was around a few tens of ev. 12 We speculate that the neutral beams consisted mainly of F atoms. Because many kinds of negative ions (SF 6,SF 5,F ) are generated in the afterglow of the SF 6 plasma, we believe that the negative ions with higher molecular weight (SF 6,SF 5 ) were easily neutralized during transport in the plasma and process chambers because of higher collision cross section with molecules. As a result, SF 6 and SF 5 ions could not be detected by the QMS in this experiment. Detecting energetic neutral species by using QMS is very difficult because of the low cross section of electron ionization. Clarifying the species of a neutral beam is a subject for future work, and we FIG. 9. Residual negative ion current density in process chamber by combination of top 100 V and bottom plates dc bias. FIG. 10. Dependence of neutralization efficiency for negative ions on bottom-plate dc bias in pulsed SF 6 plasma. Then, the top-plate dc bias was fixed at 100 V. J. Vac. Sci. Technol. A, Vol. 20, No. 5, SepÕOct 2002

6 1571 Samukawa, Sakamoto, and Ichiki: Generating high-efficiency neutral beams 1571 FIG. 11. Poly-Si etching profile for just etching by combination of top 100 V and bottom 50 V plates dc bias. FIG. 12. Poly-Si etching profile for 100% overetching by combination of top 100 V and bottom 50 V plates dc bias. need a different method to do that. In our experiment, the residual negative ion current was 40 A/cm 2, and the calculated neutral flux density was equivalent to 0.2 ma/cm 2. The flux was four times greater than that of the positive ions in the pulsed SF 6 plasma. Additionally, combinations of top and bottom dc biases were investigated in order to control the beam current and energy. The ion current density was measured with a topplate dc bias 100 V for negative ions and a bottom-plate dc bias 250 to 250 V in the pulsed SF 6 plasma, as shown in Fig. 9. When the top-plate and bottom-plate biases were fixed at 100 and 50 V, respectively, the residual negative ion current had a maximum value of 80 A/cm 2. QMS signals also showed that the F beam flux increased drastically and the peak energy was about 10 ev. By combining top and bottom dc biases, the plasma potential and sheath potential could be controlled, and negative ions could be accelerated efficiently. The neutralization efficiency was more than 98% Fig. 10 and the calculated neutral flux density was equivalent to about 4 ma/cm 2. This value is more than ten times greater than that for previous neutral-beam sources in the lower energy region. We thus found that highefficiency neutral beams can be generated by using negative ions in pulse-time-modulated SF 6 plasma. Under the same conditions, the nondoped poly-si etching characteristics were investigated. A high etching rate of more than 3000 A/min and an extremely high etching selectivity of more than 400 with respect to the underlying SiO 2 were obtained with a low-energy F-atom beam about a few tens of ev in this system. A highly anisotropic etching profile was obtained just after finishing the poly-si etching, as shown in Fig. 11. This result suggests that low-energy F-atom beams are collimated to the substrate. However, 100% overetching resulted in a side etching of 400 A, as shown in Fig. 12. This was caused by a spontaneous reaction of energy-deficient F atoms generated by the collision of the low-energy F-atom beam with the SiO 2 surface during overetching. To efficiently accelerate negative ions mainly F ions and positive ions (SF x ) from the plasma and to increase the F-atom beam energy on the substrate, a rf bias of 600 khz was applied to the bottom carbon plate. During pulse off time in the pulsed SF 6 plasma, a negative surface potential on the bottom carbon plate was almost eliminated and a large amount of negative ions was efficiently generated through the dissociative attachment because the electron temperature and electron density were drastically decreased to less than 0.1 ev and 10 9 cm 3. Then, the low-frequency rf electric field mutually accelerates negative and positive ions from the plasma to the bottom carbon plate. By applying the rf bias at 20 W to the bottom plate, we obtained a highly anisotropic etching profile while maintaining a high etching rate of more than 4500 A/min and a reasonably high etching selectivity of more than 20 with respect to the underlying SiO 2. This suggests that the F-atom beam energy increased and was collimated to the substrate by supplying the rf bias voltage at the bottom plate. We believe that under these conditions, the sidewalls of the poly-si film were protected by thin film, such as that of carbon or oxygen or both sputtered from the mask, from the reactor window, or the bell jar. Thus, a high etching rate of 4500 A/min, a highly anisotropic etching profile, and an extremely high selectivity of 400 could be obtained simultaneously by applying a rf bias of 20 FIG. 13. Poly-Si etching profile by combination of supplying rf bias of 20 W on the bottom carbon plate during bulk poly-si etching and supplying dc bias of 50 V on the bottom carbon plate during over-etching of poly-si. JVST A - Vacuum, Surfaces, and Films

7 1572 Samukawa, Sakamoto, and Ichiki: Generating high-efficiency neutral beams 1572 FIG. 14. Hole currents in SiO 2 films generated by radiating N 2 plasma or N 2 neutral beams. The Al electrode was covered by 300 A thick SiO 2 film. To detect hole currents in the SiO 2 film, the bias voltage of 30Vwas supplied. W to the bottom plate during bulk poly-si etching and a dc bias of 50 V to the bottom plate during the overetching of poly-si, as shown in Fig. 13. The neutral-beam generation system can drastically minimize radiation damage caused by the charge buildup of positive ions and electrons 1 4 or by ultraviolet photons 5 10 during etching. Hole currents were detected in the SiO 2 film 300 A during N 2 plasma irradiation, as shown in Fig. 14. The radiation of ultraviolet photons generates electron-hole pairs in dielectric films. The charge densities then get trapped at the SiO 2 /Si interface, increasing the conductivity of the SiO 2 layer and degrading the device characteristics. When the N 2 plasma was directly irradiated onto the SiO 2 film on the substrate, large hole currents of more than 980 A were detected. In contrast, in the neutral-beam generation process, the hole currents were limited to 60 A because the ultraviolet and x-ray photons were simply absorbed by the bottom carbon plate even under the same plasma-generation conditions. Additionally, the threshold voltage shifts of an antenna metal oxide semiconductor field effect transistor MOS- FET Fig. 15, Al space: 0.4 and 0.8 m, Al antenna ratio: were measured by irradiating the SF 6 neutral beam to investigate the charge buildup damage. The rf power of MHz was fixed at 500 W and the discharge pressure was 1 Pa in this experiment. The neutral-beam generation process eliminated the threshold voltage shifts, as shown in Fig. 15. From these results, we believe that our newly developed neutral beam system enables both high-performance and damage-free etching. FIG. 15. Threshold voltage shift of antenna MOSFET by irradiating SF 6 neutral beams. The antenna space of 0.4 and 0.8 m was investigated to detect electron shading damages. J. Vac. Sci. Technol. A, Vol. 20, No. 5, SepÕOct 2002

8 1573 Samukawa, Sakamoto, and Ichiki: Generating high-efficiency neutral beams 1573 IV. CONCLUSION High-performance neutral beams can be generated by our new ICP source with top and bottom carbon plates. The bottom plate has many apertures for extracting neutral beams from the plasma. When we supplied a dc bias to the plates, the generated positive and negative ions were accelerated toward the bottom plate, and most were efficiently converted into neutral atoms, either by neutralization in charge-transfer collisions with gas molecules and the aperture sidewalls, or by recombination with low-energy electrons near the end of the bottom plate. The neutralization efficiency of the negative ions was almost 100%, and the maximum neutral flux density was equivalent to 4.0 ma/cm 2. We found that negative ions can be efficiently neutralized even under negativebias conditions when they pass through the ICP source and the apertures in the bottom plate. Accurate, damage-free etching processes can be developed by using this neutralbeam generation system. 1 T. Nozawa and T. Kinoshita, Jpn. J. Appl. Phys. Part 1 34, T. Kinoshita, M. Hane, and J. P. McVittee, J. Vac. Sci. Technol. B 14, H. Ootera, Jpn. J. Appl. Phys. 33, H. Ohtake and S. Samukawa, Proceedings of the 17th Dry Process Symposium Institute of Electrical Engineering of Japan, Tokyo, 1995, p K. P. Cheung and C. S. Pai, IEEE Electron Device Lett. 16, J-P. Carrere, J-C. Oberlin, and M. Haond, Proceedings of the International Symposium on Plasma Process-Induced Damage, Monterey, 2000, p T. Dao and W. Wu, Proceedings of the International Symposium on Plasma Process-Induced Damage, Monterey, 1996, p M. Joshi, J. P. McVittee, and K. Sarawat, Proceedings of the International Symposium on Plasma Process-Induced Damage, Monterey, 2000, p C. Cismura, J. L. Shohet, and J. P. McVittee, Proceedings of the International Symposium on Plasma Process-Induced Damage, Monterey, 1999, p J. R. Woodworth, M. G. Blain, R. L. Jarecki, T. W. Hamilton, and B. P. Aragon, J. Vac. Sci. Technol. A 17, T. Mizutani and S. Nishimatsu, J. Vac. Sci. Technol. A 6, F. Shimokawa, J. Vac. Sci. Technol. A 10, S. Samukawa, K. Sakamoto, and K. Ichiki, Jpn. J. Appl. Phys., Part 2 40, L ; S. Samukawa, K. Sakamoto, and K. Ichiki, ibid. 40, L D. B. Medved, Phys. Rev. 129, JVST A - Vacuum, Surfaces, and Films