Bulletin of the American Physical Society
68th Annual Gaseous Electronics Conference/9th International Conference on Reactive Plasmas/33rd Symposium on Plasma Processing
Volume 60, Number 9
Monday–Friday, October 12–16, 2015; Honolulu, Hawaii
Session OR2: Plasma Etching I |
Hide Abstracts |
Chair: Michael Liberman, University of California, Berkeley Room: 308 AB |
Thursday, October 15, 2015 10:00AM - 10:30AM |
OR2.00001: In-Plasma Photo-Assisted Etching Invited Speaker: Demetre Economou A methodology to precisely control the ion energy distribution (IED) on a substrate allowed the study of silicon etching as a function of ion energy at near-threshold energies. Surprisingly, a substantial etching rate was observed, independent of ion energy, when the ion energy was below the ion-assisted etching threshold ($\sim$ 16 eV for etching silicon with chlorine plasma). Careful experiments led to the conclusion that this ``sub-threshold'' etching was due to photons, predominately at wavelengths \textless 1700 {\AA}. Among the plasmas investigated, photo-assisted etching (PAE) was lowest in Br$_{2}$/Ar gas mixtures and highest in HBr/Cl$_{2}$/Ar. Above threshold etching rates scaled with the square root of ion energy. PAE rates scaled with the product of surface halogen coverage (measured by X-ray photoelectron spectroscopy) and Ar emission intensity (7504 {\AA}). Scanning electron and atomic force microscopy (SEM and AFM) revealed that photo-etched surfaces were very rough, quite likely due to the inability of the photo-assisted process to remove contaminants from the surface. In-plasma PAE may be be a complicating factor for processes that require low ion energies, such as atomic layer etching. On the other hand PAE could produce sub-10 nm high aspect ratio (6:1) features by highly selective plasma etching to transfer nascent nanopatterns in silicon. [Preview Abstract] |
Thursday, October 15, 2015 10:30AM - 11:00AM |
OR2.00002: Advanced Simulation Technology to Design Etching Process on CMOS Devices Invited Speaker: Nobuyuki Kuboi Prediction and control of plasma-induced damage is needed to mass-produce high performance CMOS devices. In particular, side-wall (SW) etching with low damage is a key process for the next generation of MOSFETs and FinFETs. To predict and control the damage, we have developed a SiN etching simulation technique for CH$_{x}$F$_{y}$/Ar/O$_{2}$ plasma processes using a three-dimensional (3D) voxel model. This model includes new concepts for the gas transportation in the pattern, detailed surface reactions on the SiN reactive layer divided into several thin slabs and C-F polymer layer dependent on the H/N ratio, and use of ``smart voxels'' [1-2]. We successfully predicted the etching properties such as the etch rate, polymer layer thickness, and selectivity for Si, SiO$_{2}$, and SiN films along with process variations and demonstrated the 3D damage distribution time-dependently during SW etching on MOSFETs and FinFETs. We confirmed that a large amount of Si damage was caused in the source/drain region with the passage of time in spite of the existing SiO$_{2}$ layer of 15 nm in the over etch step and the Si fin having been directly damaged by a large amount of high energy H during the removal step of the parasitic fin spacer leading to Si fin damage to a depth of 14 to 18 nm. By analyzing the results of these simulations and our previous simulations [3-4], we found that it is important to carefully control the dose of high energy H, incident energy of H, polymer layer thickness, and over-etch time considering the effects of the pattern structure, chamber-wall condition, and wafer open area ratio. \\[4pt] In collaboration with Masanaga Fukasawa and Tetsuya Tatsumi, Sony Corporation. \\[4pt] [1] N. Kuboi \textit{et al}., Proc. Symp. Dry Process, 2014, p. 29.\\[0pt] [2] N. Kuboi \textit{et al}., presented at AVS 61$^{st}$ Int. Symp. {\&} Exhib., 2014, PS-TuM4.\\[0pt] [3] N. Kuboi \textit{et al}., Jpn. J. Appl. Phys. \textbf{49} (2010) 08JD01.\\[0pt] [4] N. Kuboi \textit{et al}., J. Vac. Sci. Technol. A\textbf{31} (2013) 061304. [Preview Abstract] |
Thursday, October 15, 2015 11:00AM - 11:15AM |
OR2.00003: Conceptual Design of Electron-Beam Generated Plasma Tools Ankur Agarwal, Shahid Rauf, Leonid Dorf, Ken Collins, David Boris, Scott Walton Realization of the next generation of high-density nanostructured devices is predicated on etching features with atomic layer resolution, no damage and high selectivity. High energy electron beams generate plasmas with unique features that make them attractive for applications requiring monolayer precision. In these plasmas, high energy beam electrons ionize the background gas and the resultant daughter electrons cool to low temperatures via collisions with gas molecules and lack of any accelerating fields. For example, an electron temperature of \textless 0.6 eV with densities comparable to conventional plasma sources can be obtained in molecular gases. The chemistry in such plasmas can significantly differ from RF plasmas as the ions/radicals are produced primarily by beam electrons rather than those in the tail of a low energy distribution. In this work, we will discuss the conceptual design of an electron beam based plasma processing system. Plasma properties will be discussed for Ar, Ar/N$_{\mathrm{2}}$, and O$_{\mathrm{2}}$ plasmas using a computational plasma model, and comparisons made to experiments. The fluid plasma model is coupled to a Monte Carlo kinetic model for beam electrons which considers gas phase collisions and the effect of electric and magnetic fields on electron motion. The impact of critical operating parameters such as magnetic field, beam energy, and gas pressure on plasma characteristics in electron-beam plasma processing systems will be discussed. [Preview Abstract] |
Thursday, October 15, 2015 11:15AM - 11:30AM |
OR2.00004: Surface rippling by oblique ion incidence during plasma etching of silicon: Experimental demonstration using sheath control plates Nobuya Nakazaki, Haruka Matsumoto, Koji Eriguchi, Kouichi Ono In the microfabrication of 3D transistors (e.g. Fin-FET), the sidewall roughness, such as LER and LWR caused by off-normal or oblique ion incidence during plasma etching, is a critical issue to be resolved, which in turn requires a better understanding of the effects of ion incidence angle $\theta_{\mathrm{i}}$ on surface roughening. This paper presents surface roughening and rippling by oblique ion incidence during inductively coupled plasma etching of Si in Cl$_{2}$, using the experimental setup as in our previous study [1]. The oblique ion incidence was achieved by sheath control plates, which were placed on and electrically connected to the wafer stage. The plates had slits to vary the sheath structure thereon and to extract ions from plasma to samples on the bottom and/or side of the slits. The results indicated that at $\theta_{\mathrm{i}} \approx $ 40$^{\circ}$ or oblique incidence; ripple structures were formed on surfaces perpendicularly to the direction of ion incidence, on the other hand, at $\theta _{\mathrm{i}} \approx $ 80$^{\circ}$ or grazing incidence, small ripples or slit like grooves were formed on surfaces parallel to the direction of ion incidence, as predicted in our previous numerical investigations [2]. \\[4pt] [1] N. Nakazaki \textit{et al}., J. Appl. Phys. \textbf{116}, 223302 (2014).\\[0pt] [2] H. Tsuda \textit{et al}., J. Vac. Sci. Technol. B \textbf{32}, 031212 (2014). [Preview Abstract] |
Thursday, October 15, 2015 11:30AM - 11:45AM |
OR2.00005: Apparatus and Method to Plasma Etch Inner Surface of the Varied Diameter Cylindrical Structure Janardan Upadhyay, Do Im, J. Peshl, S. Popovic, Anne-Marie Valente-Feliciano, L. Phillips, L. Vuskovic Plasma processing of inner surfaces of cylindrical structures imposes a coaxial method of discharge generation. It is exemplified with a superconducting radio-frequency cavity made of Niobium, which is a cylindrical structure with variable diameter. It was etched using the coaxial RF discharge operated at 13.56 MHz in Ar/Cl$_{2}$ mixture. The cavity is tested on RF performance before and after the plasma etching and the test results are be presented. In the coaxial approach one is faced with the development of a negative self-bias potential on the inner electrode in coaxial plasma, which makes processing of outer wall difficult. The processing of the cylindrical structure with varied diameter has two unique problems of having the variation in plasma sheath asymmetry and the extreme loading effect due to depletion of radical density along the gas flow direction. To overcome these problems, the shape of inner electrode is optimized for asymmetry reduction and a corrugated structure pattern is chosen. Further, a segmented plasma processing method is chosen that includes relative motion of the gas inlet and inner electrode. The coaxial cylindrical discharge was characterized with the help of optical emission spectroscopy and the correlation between plasma parameters and etching rates is presented and discussed. [Preview Abstract] |
Thursday, October 15, 2015 11:45AM - 12:00PM |
OR2.00006: Photoluminescence of GaN Film Exposed to Chlorine-Containing Plasma Daisuke Ogawa, Yoshitsugu Banno, Yoshitaka Nakano, Keiji Nakamura Gallium nitride (GaN) has been an attractive semiconductor material for the application to not only light emitting diodes, but also high power devices. The advantage of the material is that it can be fabricated to maximize the number density of devices a single wafer. In our current technology, we mainly utilize low-temperature plasma for dry etching. In fact, GaN generally requires chlorine-containing plasma for chemical etching. However, the use of plasma has a drawback that can induce unwanted changes on the fabricating devices in some conditions. This is called as plasma-induced damage (PID). We have so far monitored the development of PIDs with photoluminescence (PL) emitted from the GaN surface during argon plasma process. In this time, we exposed a GaN film to chlorine-containing plasma and monitored the PID development. Our PL measurements show that the chlorine-containing plasma almost gave no change in PL property of GaN, while argon plasma gave drastic changes. This is because the speed of etching by chlorine species was faster than the speed of damage creations by plasma. In this presentation, we will show further results of this experiment along with some analyses for the purpose of industrial application. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700