Search query: Surface studies of carbon films from pyrolyzed photoresist

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abstract: Abstract Positive and negative photoresists, which are commonly used in the semiconductor industry, were deposited on silicon wafers by spin coating and then pyrolyzed at temperatures of 600 1100degC in an inert environment to produce thin carbon films. Raman spectroscopy, X ray photoelectron spectroscopy (XPS) and scanning probe microscopy involving current sensing atomic force microscopy (CS AFM) were utilized to characterize the properties of the carbon films. Raman spectroscopy showed two broad bands at approximately 1360 cm 1 and 1600 cm 1 which deconvoluted to four Gaussian bands. The origin of these bands is discussed. CS AFM showed that the surface conductance increased with increased pyrolysis temperature, and the results are consistent with measurements by a four point probe method. The XPS spectra revealed the presence of oxygen functional groups (CO and CO) on the carbon surface. The relative fraction of oxygen, O/C ratio, decreased as the pyrolysis temperature increased, in agreement with published results. The full width at half maximum of the C 1s peak obtained by XPS also decreased with increasing pyrolysis temperature.
author_names: Robert Kostecki

Bernhard Schnyder

Dario Alliata

X Song

Kimio Kinoshita

Rudiger Kotz
title: Surface studies of carbon films from pyrolyzed photoresist
year: 2001

abstract: Carbon film electrodes were prepared by pyrolysis of photoresists on silicon wafers at temperatures ranging from 600 to 1,100 C. The physical properties of the carbon films were characterized by scanning and transmission electron microscopies, thermal gravimetric analysis, and four point probe electrical resistivity measurements. The electrochemical properties of the carbon films were investigated by cyclic voltammetry to observe the kinetics of the Fe(CN){sub 6}{sup 4{minus}/Fe(CN){sub 6}{sup 3{minus} redox couple. The carbon film electrodes prepared at temperatures {ge} 700 C showed electrochemical behavior similar to that of glassy carbon. Better electrocatalytic behavior was obtained with carbon films prepared at the higher pyrolysis temperatures, which is attributed to different film compositions at different pyrolysis temperatures. The electrochemical properties of the carbon film electrodes are very stable, exhibiting reproducible behavior even after storing at room temperature in air for 3 months.
author_names: Jae Chul Kim

Xiangyun Song

Kimio Kinoshita

Marc J Madou

Ralph E White
title: Electrochemical Studies of Carbon Films from Pyrolyzed Photoresist
year: 1998

abstract: We report the structural characterization and electric heating performance of carbon thin films (CTFs) which were prepared from negative type SU 8 photoresist by deep UV exposure and following carbonization. The prepared CTFs were found to have pseudo graphitic carbon structures containing partially graphite domains in the amorphous carbon matrix. The CTFs showed a very smooth surface morphology with a roughness of 0.42 nm. The 107 nm thick CTFs exhibited an excellent electric heating performance by attaining a high maximal temperature of 207 degC and a rapid heating rate of 13.2 degC/s at an applied voltage of 30 V. Therefore, the CTFs prepared in this study can be applied as electrode materials for high performance electric heaters.
author_names: Byoung-Min Lee

H G Nam

Hyeong Choi

Sung-Kwon Hong

Young Gyu Jeong

Jae-Hak Choi
title: Electric heating performance of carbon thin films prepared from SU 8 photoresist by deep UV exposure and carbonization
venue: Carbon Letters
year: 2020

abstract: The carbon fiber microelectrode has been used for decades as a neurotransmitter sensor. Recently, new strategies have been developed for making carbon electrodes, including using carbon nanomaterials or pyrolyzing photoresist etched by nanolithography or 3D printing. This review summarizes how chemical and 3D surface structures of new carbon electrodes are optimized for neurotransmitter detection. There are effects of the chemical structure that are advantageous and nanomaterials are used ranging from carbon nanotube (CNT) to graphene to nanodiamond. Functionalization of these materials promotes surface oxide groups that adsorb dopamine and dopants introduce defect sites good for electron transfer. Polymer coatings such as poly(3,4 ethylenedioxythiophene) (PEDOT) or Nafion also enhance the selectivity, particularly for dopamine over ascorbic acid. Changing the 3D surface structure of an electrode increases current by adding more surface area. If the surface structure has roughness or pores on the micron scale, the electrode also acts as a thin layer cell, momentarily trapping the analyte for redox cycling. Vertically aligned CNTs as well as lithographically made or 3D printed pillar arrays act as thin layer cells, producing more reversible cyclic voltammograms. A better understanding of how chemical and surface structure affects electrochemistry enables rational design of electrodes. New carbon electrodes are being tested in vivo and strategies to reduce biofouling are being developed. Future studies should test the robustness for long term implantation, explore electrochemical properties of neurotransmitters beyond dopamine, and combine optimized chemical and physical structures for real time monitoring of neurotransmitters.
author_names: Qun Cao

Pumidech Puthongkham

B Jill Venton
title: Review: New insights into optimizing chemical and 3D surface structures of carbon electrodes for neurotransmitter detection
venue: Analytical methods advancing methods and applications
year: 2019

abstract: The work presented herein describes a fundamental investigations of carbon as electrode material by using the pyrolysis of photoresist to create an optically transparent material. The development of these carbon based optically transparent electrodes (C OTEs) enables investigations of molecular interactions within the electrical double layer, processes that are central to a wide range of important phenomena, including the impact of changes in the surface charge density on adsorption. The electrochemical importance of carbon cannot be understated, having relevance to separations and detection by providing a wide potential window and low background current in addition to being low cost and light weight. The interactions that govern the processes at the carbon electrode surface has been studied extensively. A variety of publications from the laboratories of McCreery and Kinoshita provide in depth summaries about carbon and its many applications in electrochemistry. These studies reveal that defects, impurities, oxidation, and a variety of functional groups create adsorption sites on carbon surfaces with different characteristics. The interest in C OTEs was sparked by the desire to study and understand the behavior of individual molecules at electrified interfaces. It draws on the earlier development of Electrochemically Modulated Liquid Chromatography (EMLC) which uses carbon as the stationary phase. more EMLC takes advantage of changing the applied potential to the carbon electrode to influence the retention behavior of analytes. However, perspectives gained from, for example, chromatographic measurements reflect the integrated response of a large ensemble of potentially diverse interactions between the adsorbates and the carbon electrode. Considering the chemically and physically heterogeneous surface of electrode materials such as glassy carbon, the integrated response provides little insight into the interactions at a single molecule level. To investigate individual processes, they have developed C OTEs in order to couple electrochemistry with single molecule spectroscopy (SMS) Like EMLC, the novel merger of SMS with electrochemistry is a prime example of how a hybrid method can open new and intriguing avenues that are of both fundamental and technological importance. They show that by taking the benefits of total internal reflection fluorescence microscopy (TIRFM) and incorporating carbon as electrode material observations central to the interactions between single DNA molecules and an electrified carbon surface can be delineated. Using TIRFM while applying a positive potential to the electrode, individual molecules can be observed as they reversibly and irreversibly adsorb to the carbon surface. The positive potential attracts the negatively charged DNA molecules to the electrode surface. Dye labels on the DNA within the evanescent wave are excited and their fluorescence is captured by an intensified charge coupled device (ICCD) camera. Results are therefore presented regarding the interactions of {lambda} DNA, 48,502 base pairs (48.5 kbp) HPV 16, 7.9 kbp, and 1 kbp fraction of pBR322 DNA. In addition to the influence of molecular size on adsorption, the fabrication, characterization, and more conventional spectroelectrochemical applications of these novel C OTEs are presented. less
author_names: S K Donner
title: Development of carbon based optically transparent electrodes from pyrolyzed photoresist for the investigation of phenomena at electrified carbon solution interfaces
year: 2007

abstract: The carbon fiber microelectrode has been used for decades as a neurotransmitter sensor. Recently, new strategies have been developed for making carbon electrodes, including using carbon nanomaterials or pyrolyzing a photoresist etched by nanolithography or 3D printing. This review summarizes how chemical and 3D surface structures of new carbon electrodes are optimized for neurotransmitter detection. There are effects of the chemical structure that are advantageous, and nanomaterials are used ranging from carbon nanotubes (CNTs) to graphene to nanodiamond. Functionalization of these materials promotes surface oxide groups that adsorb dopamine, and dopants introduce defect sites good for electron transfer. Polymer coatings such as poly(3,4 ethylenedioxythiophene) (PEDOT) or Nafion also enhance the selectivity, particularly for dopamine over ascorbic acid. Changing the 3D surface structure of an electrode increases the current by adding more surface area. If the surface structure has roughness or pores on the micron scale, the electrode also acts as a thin layer cell, momentarily trapping the analyte for redox cycling. Vertically aligned CNTs as well as lithographically made or 3D printed pillar arrays act as thin layer cells, producing more reversible cyclic voltammograms. A better understanding of how the chemical and surface structure affects the electrochemistry enables rational design of electrodes. New carbon electrodes are being tested in vivo and strategies to reduce biofouling are being developed. Future studies should test the robustness for long term implantation, explore electrochemical properties of neurotransmitters beyond dopamine, and combine optimized chemical and physical structures for real time monitoring of neurotransmitters.
author_names: Qun Cao

Pumidech Puthongkham

B Jill Venton
title: ghts into optimizing chemical and 3 D surface structures of carbon electrodes for neurotransmitter detection
year: 2019

abstract: We report here a novel and simple buckling based multiscale patterning of negative photoresist films which were subsequently pyrolyzed to yield complex micro patterned carbon surfaces. Unlike other polymers, the use of a photoresist layer allows the overall pattern definition by photolithography on which the geometry and length scale of the buckling instability are superimposed. The photoresist film swells anisotropically during developing and buckles after subsequent drying due to the difference in the shrinkage of the hard cross linked layer on top of a softer native pre polymer. We studied the conditions for the formation of a wide variety of complex, fractal buckling patterns as well as directionally aligned zigzag patterns over a large area. For example, the buckling diminished for the films below a critical thickness and after a prolonged UV exposure, both of which eliminate the softer under layer. These patterned carbon substrates are also shown to be biocompatible for the cellular adhesion and viability by using L929 mouse fibroblast cells, thus indicating their potential use in bio MEMS platforms with a conductive substrate. The buckled carbon patterns were found to be a better choice of a substrate for cell growth and viability as compared to flat and simply periodic patterned carbon surfaces.
author_names: Manish M Kulkarni

Chandra Shekhar Sharma

Ashutosh Sharma

Sushma Kalmodia

Bikramjit Basu
title: Multiscale micro patterned polymeric and carbon substrates derived from buckled photoresist films: fabrication and cytocompatibility
venue: Journal of Materials Science
year: 2012

abstract: Hydrogen terminated silicon surfaces play an important role in the integrated circuit (IC) industry. Ultra pure water is extensively used for the cleaning and surface preparation of silicon surfaces. This work studies the effects of ultra pure water on hydrogen passivated silicon surfaces in a short time frame of 120 minutes using fourier transform infrared spectroscopy attenuated total reflection techniques. Varying conditions of ultra pure water are used. This includes dissolved oxygen poor media after nitrogen bubbling and equilibration under nitrogen atmosphere, as well as metal contaminated solutions. Both microscopically rough and ideal monohydride terminated surfaces are examined. Hydrogen terminated silicon is also used as the sensing electrode for a potentiometric sensor for ultra trace amounts of metal contaminants. Previous studies show the use of this potentiometric electrode sensor in hydrofluoric acid solution. This work is able to shows sensor function in ultra pure water media without the need for further addition of hydrofluoric acid. This is considered a boon for the sensor due to the hazardous nature of hydrofluoric acid. Thin carbon films can be formed by spin coating photoresist onto silicon substrates and pyrolyzing at 1000 degrees C under reducing conditions. This work also shows that the electroless deposition of palladium and platinum may be accomplished in hydrofluoric acid solutions to attain palladium and platinum nanoparticles on a this film carbon surface for use as an electrode. Catalysis of these substrates is studied using hydrogen evolution in acidic media, cyclic voltammetry, and catalysis of formaldehyde. X ray diffractometry (XRD) is used to ensure that there is little strain on palladium and platinum particles. Iridium is thought to be a prime candidate for investigation as a new generation copper diffusion barrier for the IC industry. Copper electrodeposition on iridium is studied to address the potential of iridium as a copper diffusion barrier. Copper electrodeposition is studied using a current transient technique to obtain insight into the nucleation and growth mechanism. Copper on iridum was annealed up to 600 degrees C. X ray photoelectron spectroscopy and XRD confirm that electrodeposited copper exists in a metallic state. XRD shows that copper exists in the characteristic face centered cubic (111) form. XRD also confirms the stability of the copper iridium interface with no new peaks after annealing, which is indicative that no interaction occurs. Scanning electron microscopy, and Scotch (r) Tape peel tests confirm the uniformity and strength of copper on iridium even after annealing to 600 degrees C.
author_names: Raymond Chan
title: Interfacial Electrochemistry and Surface Characterization: Hydrogen Terminated Silicon, Electrolessly Deposited Palladium Platinum on Pyrolyzed Photoresist Films and Electrodeposited Copper on Iridium
year: 2003

abstract: Carbon electrodes coupled with electrochemical detection have been used extensively for the investigation of biogenic amines. Herein we report the fabrication and characterization of carbonaceous electrodes prepared from pyrolyzed parylene C (PPC) films. High aspect ratio carbonaceous microelectrodes have been prepared by masking PPC coated pipets with an insulating parylene C film. PPC thin film electrodes were characterized electrochemically, spectroscopically, and with electron microscopy. The procedures described here offer a route to fabrication of thin film carbon electrodes that can be patterned and produced in parallel. These electrodes are similar to carbon electrodes derived from pyrolyzed photoresist films but do not require spin coating or lithography and can readily coat three dimensional surfaces.
author_names: Kirstin C Morton

Celeste A Morris

Maksymilian A Derylo

Rahul G Thakar

Lane A Baker
title: Carbon electrode fabrication from pyrolyzed parylene C.
venue: Analytical chemistry
year: 2011

abstract: In this study, the investigation of surface treatment of chemically inert graphitic carbon microelectrodes (derived from pyrolyzed photoresist polymer) for improving their attachment chemistry with DNA molecular wires and ropes as part of a bionanoelectronics platform is reported. Polymer microelectrodes were fabricated on a silicon wafer using standard negative lithography procedures with negative tone photoresist. These microelectrode structures were then pyrolyzed and converted to a form of conductive carbon that is referred to as PP (pyrolyzed polymer) carbon throughout this paper. Functionalization of the resulting pyrolyzed structures was done using nitric, sulfuric, 4 amino benzoic acids (4 ABA) and oxygen plasma etching and the surface modifications confirmed with Fourier transform infrared spectroscopy (FTIR) Raman spectroscopy, and electron dispersion x ray spectroscopy (EDS) Post surface treatment analysis of microelectrodes with FTIR and Raman spectroscopy showed signature peaks characteristics of carboxyl functional groups while EDS showed an increase in oxygen content in the surface treatment procedures (except 4 ABA) indicating an increase in carboxyl functional group. These functional groups form the basis for peptide bond with aminated oligonucleotides that in turn could be used as molecular wires and interconnects in a bionanoelectronics platform. Post pyrolysis analysis using EDS showed relatively higher oxygen concentrations at the edges and location of defects compared to other locations on these microelectrodes. In addition, electrochemical impedance measurements showed metal like behavior of PP carbon with high conductivity |Z| <1 KO) and no detectable detrimental effect of oxygen plasma surface treatment on electrical characteristic. In general, characterization results taken together indicated that oxygen plasma surface treatment produced more reliable, less damaging, and consistently repeatable generation of carboxyl functional groups than diazonium salt and strong acid treatments.
author_names: Mieko Hirabayashi

Beejal Mehta

Nasim Winchester Vahidi

Ajit Khosla

Sam Kassegne
title: Functionalization and characterization of pyrolyzed polymer based carbon microstructures for bionanoelectronics platforms
year: 2013