scholarly journals Ion-Enhanced Etching Characteristics of sp2-Rich Hydrogenated Amorphous Carbons in CF4 Plasmas and O2 Plasmas

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2941
Author(s):  
Jie Li ◽  
Yongjae Kim ◽  
Seunghun Han ◽  
Heeyeop Chae

The sp2-rich hydrogenated amorphous carbon (a-C:H) is widely adopted as hard masks in semiconductor-device fabrication processes. The ion-enhanced etch characteristics of sp2-rich a-C:H films on ion density and ion energy were investigated in CF4 plasmas and O2 plasmas in this work. The etch rate of sp2-rich a-C:H films in O2 plasmas increased linearly with ion density when no bias power was applied, while the fluorocarbon deposition was observed in CF4 plasmas instead of etching without bias power. The etch rate was found to be dependent on the half-order curve of ion energy in both CF4 plasmas and O2 plasmas when bias power was applied. An ion-enhanced etching model was suggested to fit the etch rates of a-C:H in CF4 plasmas and O2 plasmas. Then, the etch yield and the threshold energy for etching were determined based on this model from experimental etch rates in CF4 plasma and O2 plasma. The etch yield of 3.45 was observed in CF4 plasmas, while 12.3 was obtained in O2 plasmas, owing to the high reactivity of O radicals with carbon atoms. The threshold energy of 12 eV for a-C:H etching was obtained in O2 plasmas, while the high threshold energy of 156 eV was observed in CF4 plasmas. This high threshold energy is attributed to the formation of a fluorocarbon layer that protects the a-C:H films from ion-enhanced etching.

MRS Advances ◽  
2017 ◽  
Vol 2 (4) ◽  
pp. 247-252
Author(s):  
Narasimhan Srinivasan ◽  
Katrina Rook ◽  
Ivan Berry ◽  
Binyamin Rubin ◽  
Frank Cerio

ABSTRACTWe investigate the feasibility of inert ion beam etch (IBE) for subtractive patterning of ReRAM-type structures. We report on the role of the angle-dependent ion beam etch rates in device area control and the minimization of sidewall re-deposition. The etch rates of key ReRAM materials are presented versus incidence angle and ion beam energy. As the ion beam voltage is increased, we demonstrate a significant enhancement in the relative etch rate at glancing incidence (for example, by a factor of 2 for HfO2). Since the feature sidewall is typically exposed to glancing incidence, this energy-dependence plays a role in optimization of the feature shape and in sidewall re-deposition removal.We present results of SRIM simulations to estimate depth of ion-bombardment damage to the TMO sidewall. Damage is minimized by minimizing ion energy; its depth can be reduced by roughly a factor of 5 over typical IBE energy ranges. For example, ion energies of less than ∼250 eV are indicated to maintain damage below ∼1nm. Multi-angle and multi-energy etch schemes are proposed to maximize sidewall angle and minimize damage, while eliminating re-deposition across the TMO. We utilize 2-D geometry/3-D etch model to simulate IBE patterning of tight-pitched ReRAM features, and generate etched feature shapes.


1997 ◽  
Vol 467 ◽  
Author(s):  
E. A. G. Hamers ◽  
J. Bezemer ◽  
H. Meiling ◽  
W.G.J.H.M. Van Sark ◽  
W. F. Van Der Weg

ABSTRACTThe measurement of mass resolved ion energy distributions at the grounded substrate in an RF glow discharge allows to determine the ion flux and the ion energy flux towards the surface of a growing hydrogenated amorphous silicon (a-Si:H) layer. This provides the means to study the influence of ions on the structural properties of a-Si:H. Here we focus on the α-γ’ transition as occurs in silane-hydrogen plasmas at an RF frequency of 50 MHz and a substrate temperature of 250 °C. The structural properties of the layers appear to depend on the kinetic energy of the arriving ions. This is supported by measurements of ion fluxes under other deposition conditions and by characterization of the corresponding layers. The influence of ions on the growth is discussed in terms of their flux, and the amount of delivered kinetic and potential energy to the growing film. The measurements suggest that a threshold energy of about 5 eV per deposited atom is needed for the construction of a dense amorphous silicon network.


1997 ◽  
Vol 494 ◽  
Author(s):  
J. Hong ◽  
J. J. Wang ◽  
E. S. Lambers ◽  
J. A. Caballero ◽  
J. R. Childress ◽  
...  

ABSTRACTA variety of plasma etching chemistries were examined for patterning NiMnSb Heusler thin films and associated A12O3 barrier layers. Chemistries based on SF6 and Cl2 were all found to provide faster etch rates than pure Ar sputtering. In all cases the etch rates were strongly dependent on both the ion flux and ion energy. Selectivities of ≥20 for NiMnSb over A12O3 were obtained in SF6-based discharges, while selectivities ≤5 were typical in Cl2 and CH4/H2 plasma chemistries. Wet etch solutions of HF/H2O and HNO3/H2SO4/H2O were found to provide reaction-limited etching of NiMnSb that was either non-selective or selective, respectively, to A12O3. In addition we have developed dry etch processes based on Cl2/Ar at high ion densities for patterning of LaCaMnO3 (and SmCo permanent magnet biasing films) for magnetic sensor devices. Highly anisotropie features are produced in both materials, with smooth surface morphologies. In all cases, SiO2 or other dielectric materials must be used for masking since photoresist does not retain its geometrical integrity upon exposure to the high ion density plasma.


Author(s):  
N. David Theodore ◽  
Juergen Foerstner ◽  
Peter Fejes

As semiconductor device dimensions shrink and packing-densities rise, issues of parasitic capacitance and circuit speed become increasingly important. The use of thin-film silicon-on-insulator (TFSOI) substrates for device fabrication is being explored in order to increase switching speeds. One version of TFSOI being explored for device fabrication is SIMOX (Silicon-separation by Implanted OXygen).A buried oxide layer is created by highdose oxygen implantation into silicon wafers followed by annealing to cause coalescence of oxide regions into a continuous layer. A thin silicon layer remains above the buried oxide (~220 nm Si after additional thinning). Device structures can now be fabricated upon this thin silicon layer.Current fabrication of metal-oxidesemiconductor field-effect transistors (MOSFETs) requires formation of a polysilicon/oxide gate between source and drain regions. Contact to the source/drain and gate regions is typically made by use of TiSi2 layers followedby Al(Cu) metal lines. TiSi2 has a relatively low contact resistance and reduces the series resistance of both source/drain as well as gate regions


2013 ◽  
Vol 341 ◽  
pp. 181-210 ◽  
Author(s):  
S.K. Tripathi

High-energy electron, proton, neutron, photon and ion irradiation of semiconductor diodes and solar cells has long been a topic of considerable interest in the field of semiconductor device fabrication. The inevitable damage production during the process of irradiation is used to study and engineer the defects in semiconductors. In a strong radiation environment in space, the electrical performance of solar cells is degraded due to direct exposure to energetically charged particles. A considerable amount of work has been reported on the study of radiation damage in various solar cell materials and devices in the recent past. In most cases, high-energy heavy ions damage the material by producing a large amount of extended defects, but high-energy light ions are suitable for producing and modifying the intrinsic point defects. The defects can play a variety of electronically active roles that affect the electrical, structural and optical properties of a semiconductor. This review article aims to present an overview of the advancement of research in the modification of glassy semiconducting thin films using different types of radiations (light, proton and swift heavy ions). The work which has been done in our laboratory related to irradiation induced effects in semiconducting thin films will also be compared with the existing literature.


1988 ◽  
Vol 129 ◽  
Author(s):  
Christoph Steinbruchel

ABSTRACTA variety of data for physical etching (i.e. sputtering) and for ion-enhanced chemical etching of Si and SiO2 is analyzed in the very-low-ion-energy regime. Bombardment by inert ions alone, by reactive ions, and by inert ions in the presence of reactiveneutrals is considered. In all cases the etch yield follows a square root dependence on the ion energy all the way down to the threshold energy for etching. At the same time, the threshold energy has a non-negligible effect on the etch yield even at intermediate ion energies. The difference between physical and ion-enhanced chemical etch yields can be accounted for by a reduction in the average surface binding energy of the etch products and a corresponding reduction in the threshold energy for etching. These results suggest that, in general, the selectivity for ion-enhanced etch processes relative to physical sputtering can be increased significantly at low ion energy.


2001 ◽  
Vol 684 ◽  
Author(s):  
Jane P. Chang

Recognizing that the traditional engineering education training is often inadequate in preparing the students for the challanges presented by this industry's dynamic environment and insufficient to meet the empoyer's criteria in hiring new engineers, a new curriculum on Semiconductor Manufacturing is instituted in the Chemical Engineering Department at UCLA to train the students in various scientific and technologica areas that are pertinenet to the microelectronics industries. This paper describes this new mutidisciplinary curriculum that provides knowledge and skills in semiconductor manufacturing through a series ofcourses that emphasize on the application of fundamenta engineeering disciplines in solid-state physics, materials science of semiconductors, and chemical processing. The curriculum comprises three major components:(1)a comprehensive course curriculum in semiconductor manufacturing; (2) a laboratory for hands-on training in semiconductor device fabrication; (3) design of experiments. The capstone laboratory course is designed to strengthen students’ training in “unit operatins” used in semicounductor manufacturing and allow them to practice engineering principles using the state-of-the-art experimental setup. It comprises the most comprehensive training(seven photolithographic steps and numero0us chemical processes)in fabricating and testing complementary metal-oxide-semiconductor (CMOS) devices. This curriculum is recentyaccredited by the Accreditation Board for Engineering and Technology(ABET).


2004 ◽  
Vol 10 (4) ◽  
pp. 462-469 ◽  
Author(s):  
Wolf-Dieter Rau ◽  
Alexander Orchowski

We present and review dopant mapping examples in semiconductor device structures by electron holography and outline their potential applications for experimental investigation of two-dimensional (2D) dopant diffusion on the nanometer scale. We address the technical challenges of the method when applied to transistor structures with respect to quantification of the results in terms of the 2Dp–njunction potential and critically review experimental boundary conditions, accuracy, and potential pitfalls. By obtaining maps of the inner electrostatic potential before and after anneals typically used in device processing, we demonstrate how the “vertical” and “lateral” redistribution of boron during device fabrication can directly be revealed. Such data can be compared with the results of process simulation to extract the fundamental parameters for dopant diffusion in complex device structures.


2020 ◽  
Vol 58 (6) ◽  
pp. 397-402
Author(s):  
Junyoung Park ◽  
Byoungmoon Oh ◽  
Kyongnam Kim

PFC gas is primarily used during the etching process in the manufacture of ULSIs and in cleaning after CVD processes. PFC is classified as a greenhouse gas that stays in the atmosphere for a long time and has a high GWP. High capacity and high integration have been achieved in recent years as semiconductor device structures have been replaced by vertical layer structures, and the consumption of PFC gas has exploded due to the increase in high aspect ratio and patterning processes. Therefore, many researchers have been working on methods to decompose, recover, and reuse the gas after the etching process to reduce the emissions of PFC gas. In this study, etching and recovery processes were performed using C5F8 in L-FC which is in liquid phase at room temperature. Among the L-FCs, C5F8 gas has a high C/F ratio, similar to that of the C4F8 gas, which is a conventional PFC gas. In addition, to confirm its reusability, the recovered C5F8 was injected back into the chamber, and the electron temperature, plasma density, and ion energy distribution were analyzed. Based on these experimental data, the reliability of the etch processes performed with recovered C5F8 gas was evaluated, and the possibility of reusing the recovered C5F8 gas was confirmed.


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