The interaction between resist and template during the separation process after nanoimprint lithography (NIL) can cause the formation of defects and damage to the templates and resist patterns. To alleviate these problems, fluorinated self-assembled monolayers (F-SAMs, i.e. tridecafluoro-1,1,2,2,tetrahydrooctyl trichlorosilane or FDTS) have been employed as template release coatings. However, we find that the FDTS coating undergoes irreversible degradation after only 10 cycles of UV nanoimprint processes with SU-8 resist. The degradation includes a 28% reduction in surface F atoms and significant increases in the surface roughness. In this paper, diamond-like carbon (DLC) films were investigated as an alternative material not only for coating but also for direct fabrication of nanoimprint templates. DLC films deposited on quartz templates in a plasma enhanced chemical vapor deposition system are shown to have better chemical and physical stability than FDTS. After the same 10 cycles of UV nanoimprints, the surface composition as well as the roughness of DLC films were found to be unchanged. The adhesion energy between the DLC surface and SU-8 is found to be smaller than that of FDTS despite the slightly higher total surface energy of DLC. DLC templates with 40 nm features were fabricated using e-beam lithography followed by Cr lift-off and reactive ion etching. UV nanoimprinting using the directly patterned DLC templates in SU-8 resist demonstrates good pattern transfer fidelity and easy template-resist separation. These results indicate that DLC is a promising material for fabricating durable templates for UV nanoimprint lithography.
This article serves as a reference for the analysis of Fourier transform infrared spectroscopy data from processing plasmas. Until now, there has been a lack of accurate reference data for addressing the problems of species identification and density measurements in cases of increasing gas temperatures. Our results show that, while the integrated absorption cross-sections do not change significantly as temperature increases, the temperature of the absorbing species can be estimated from the rotational band maximum in most cases. Integrated absorption cross-sections for cC 3 F 6 , C 4 F 8 , C 3 F 8 , C 2 F 6 , C 2 F 4 , and CF 4 are presented for all fundamental bands in the 650 cm À1 to 2000 cm À1 region. In addition, the binary combination bands up to 4000 cm À1 are presented for all species. The temperature of each species has been varied to correspond to neutral temperatures commonly found in processing plasmas. V
In the present work, an investigation of the gas and surface phase behavior of ethylene glycol (EG) pulsed discharges is presented. Infrared and optical emission spectroscopy along with time‐resolved electron temperature (Te) and electron density (ne) measurements were employed in these pulsed EG plasmas to study the dynamics of monomer fragmentation and effective chemical feedback from boundary walls. Maximized retention of monomer functionality, (CH2CH2O)n, were seen in polymer deposits when processed at low values of average power (<20 W). This preservation of monomer functionality is attributed to the increase in effective collision time between electrons and EG molecules. Presented results correlated well with proposed ethylene glycol dissociation pathways in the pulsed discharge. magnified image
The time multiplexed deep silicon etch (TMDSE) process is the etch process of choice to make MEMS devices and through wafer vias. It has been used to produce deep trenches and vias at reasonable throughputs. Significant issues remain for the TMDSE process as well as room for improvement even though it has been both experimentally studied and modeled by a wide variety of researchers. This is because it is a highly complex process. Aspect ratio dependencies, selectivity, and the ability to use photoresist masks (instead of SiO 2 ) are examples of remaining issues. The presently obtainable etch rates do not indicate efficient use of the etchant species. In this article, the authors focus on the deposition step in the TMDSE process. While prior research has generally assumed that the deposition step can be adequately modeled as being controlled by a reactive sticking coefficient, they have experimentally examined the deposition step of the process and found that the film growth is dominantly ion-enhanced. The results shown here were obtained in C 4 F 8 plasmas but are also consistent with results found in CHF 3 and C 4 F 6 plasmas. As a result, the deposited film thickness can be larger at the bottom of a high aspect ratio feature than at the top sidewall, which is exactly the opposite of the desired profile. The very nature of the deposition mechanism leads to mask undercut at the same time as feature closing/etch stop.
This paper examines the complex nature of highly polymerizing fluorocarbon plasmas. An inductively coupled modified GEC reference cell is used to look at process rates on SiO 2 , p-Si and Si 3 N 4 samples using various chamber geometries and gas chemistries. In an attempt to understand the process rates, a simple model based on the sticking and etch yield coefficients of radicals and ions is employed. Development of the model requires knowledge of radical flux, ion flux, ion energy and related process rates. These values are determined using in situ spectroscopic ellipsometry, in situ optical emission spectroscopy, in situ Fourier transform infrared spectroscopy and chuck self-bias measurements. Through the use of a variable electrode gap and changing feed gas chemistry, sticking radical densities are controlled almost independently of ions and etching radical densities. This control allows a partial deconvolution of the process rate equation. Estimated values for the upper bound sticking coefficients of fluorocarbon radicals are made. Additionally, values are reported for ion sticking coefficients and the fluorine etch yield coefficient. These values are then used in a basic low ion energy model to compare with experimental process rates.
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