New Electron Beam Proximity Effects Correction Approach for 45 and 32 nm Nodes (original) (raw)
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True three-dimensional proximity effect correction in electron-beam lithography
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2006
Proximity effect in e-beam lithography is mainly due to the "nonideal" distribution of exposure ͑energy deposited in the resist͒. The proximity effect correction schemes developed so far employ a two-dimensional ͑2D͒ model, i.e., exposure variation along the resist depth dimension is not considered. The exposure distribution estimated by the 2D model can be significantly different from the actual exposure distribution, especially for the nanoscale patterns. In this article, a three-dimensional ͑3D͒ correction method which uses a 3D point spread function in controlling e-beam dose distribution within each circuit feature in order to achieve a certain desired 3D remaining resist profile after development is described. The dose to be given to each region of a feature is determined based on the estimated remaining resist profile ͑with the emphasis on the sidewall shape͒ through iterations. Simulation results demonstrating the potential improvements by the 3D correction are provided.
25th European Mask and Lithography Conference, 2009
Electron beam direct write lithography is known for its high resolution capabilities, which enables studies ahead of the technology in production. That is why this technique is used for many years in laboratories for R&D. Recently it was shown that electron beam lithography can be integrated within the flows of the microelectronics industry for prototyping applications, low volume production and to support optical lithography for ASIC manufacturing. Moreover recent lithography workshops highlighted that the multi beam solution is identified as one potential technique for next generation lithography techniques to meet the requirements of sub-32nm technological nodes. The present proximity correction methods for electron beam lithography are based on the standard dose modulation principle. However these methods cannot properly ensure a sufficient control of the patterning of the most critical designs. To push the resolution capability of electron beam lithography, a new correction method is proposed. It consists in a multiple pass exposure strategy. For example instead of patterning a line in one pass (standard exposure), the pattern is split in several basic blocks with potential overlaps exposed in several passes and with an adapted dose. Compared to standard exposure, this solution provides an improved process window and a better control of the critical dimensions. We could achieve energy latitude of 22.2% and we improved the line edge roughness by 27% on 45nm dense lines (line width equal to space) with this method.
Development of multiple pass exposure in electron beam direct write lithography for sub-32nm nodes
Photomask Technology 2009, 2009
Electron beam direct write lithography is used in the ASIC manufacturing industry to sustain optical lithography for prototyping applications, low volume production and for the development of the next technological nodes. However the standard proximity effects corrections based on dose modulation are not sufficient to provide the patterning accuracy required for the sub-32nm nodes. New methods are needed to push the resolution capabilities of electron beam lithography. In a previous paper, a new writing strategy based on multiple pass exposure has been introduced. It consists in adding small electron Resolution Improvement Features (eRIF) atop the nominal features. Thanks to this new method, critical lines have been patterned with enlarged energy latitude. In this paper, multiple pass exposure is applied to the sub-32nm nodes. The influence of the design of the eRIF is analysed in detail. The best conditions in terms of dose, size and placement of the eRIF are used to establish a methodology to optimize this new strategy. Using multiple pass exposure, the energy latitude was increased up to about 20% which is three times the energy latitude of the standard exposure. Then the impact of multiple pass exposure on the writing time of the electron beam tool is studied. It appears that a compromise has to be found between the writing time and the improvement of the energy latitude. Finally it is shown that the resolution capabilities of the electron beam lithography can be increased using the multiple pass exposure strategy.
The Validation of Various Technological Factors Impact on the Electron Beam Lithography Process
Advances in Electrical and Electronic Engineering, 2021
One of the most significant processes in micro-and nanoelectronics technology is Electron Beam Lithography (EBL). This technique maintains a leading role in extremely high-resolution structures fabrication process with micro-and nanometer dimensions down to dozens of nanometers. The EBL is a highly complex process and determining fundamental technological factors that affect the final pattern shape is crucial. One of them is the used lithography system, consisting of a substrate and a polymer layer that affects the electron scattering effects. To obtain the required pattern geometry, it is also necessary to properly select the electron beam parameters for given materials. The aim of this work is to discuss the differences in the exposition process for various accelerating voltage (EHT) values. Additionally, the investigation of geometry features and the impact of the exposure dose and the structure dimensions on the final absorbed energy distribution profile in the resist layer is presented and discussed. Numerical studies, using CASINO software and Monte Carlo method, are presented to compare the energy distribution in the polymer that affects the structure formation in the resist layer.
E-beam lithography experimental results and simulation for the 45-nm node
2004
E-Beam Lithography is still the driving technology for semiconductor manufacturing of critical levels at the 45nm node. Mask costs, yields and representation of the mask on wafer are important factors to consider. Mask-less E-beam lithography is being considered, but major manufacturing is still done by scanner technology. Therefore the same emphasis on modeling applied in the 1990's on the wafer is now being applied to mask technologies to drive down costs, improve yields and to develop viable mask to wafer transfer patterns.
Proximity correction of chemically amplified resists for electron beam lithography
Microelectronic Engineering, 1998
A simple experimental method has been developed to extract parameters of ~, I~ and q for proximity correction in electron beam lithography of chemically amplified resists. The method is based on the mcasurelnent of a series of isolated lines with different line widths exposed at a single exposure dose. The measured deviations from noininal line width are fitted into a function, from which the proximity' parameters arc obtained. Proximity parameters for AZPN114 negative chemically amplified resist were derived by the new method and improvements on pattern fidelity and CD control after proximity correction are demonstrated.
Journal of Vacuum Science & Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena, 2011
The authors present a general approach to combine model-based dose modulations and shape modifications into a hybrid proximity effects correction (PEC) scheme for electron beam lithography. The authors simplify this scheme significantly by using an appropriate dose correction strategy. This allows us to use an existing optical proximity correction tool for the shape adjustments. This hybrid PEC scheme is demonstrated by computing corrections for simple test patterns as well as a more complex pattern. The model used corresponds to an electron multibeam tool with an acceleration voltage of 50 kV. It predicts resist contours from a written dose distribution. The authors evaluate the quality of the results both for nominal process conditions and in the presence of process variations. The results are compared against the corresponding results for a correction using only dose modulation. The authors also use the hybrid scheme to compensate intentional overexposure by shape adjustments and include these results in the comparison so that the impact of overexposure on robustness against process variations can be determined. V
Electron beam lithography simulation for high resolution and high-density patterns
Vacuum, 2001
A fast simulator for electron beam lithography, called SELID2+, is applied for the simulation and prediction of the resist pro"le of high-resolution patterns in the case of homogeneous and multilayer substrates. For exposure simulation, an analytical solution based on the Boltzmann transport equation (where all important scattering phenomena have been taken into account) for a wide range of e-beam energies is used. The case of substrates consisting of more than one layer (multilayer) is considered in depth as it is of great importance in e-beam patterning. By combining the energy deposition data from simulation with analytical functions describing the resist development (for the conventional positive-resist PMMA), complete simulation of dense layouts in the sub-quarter-micron range has been carried out. Additionally, the simulation results are compared with experimental ones for dense patterns in the sub-quarter-micron region. By using SELID2+, forecast of resist pro"le with considerable accuracy for a wide range of resists, substrates and energies is possible, reducing in that way the cost of process development. Additionally, proximity e!ect parameters are extracted easily for use in any proximity correction package.
Substrate Effect in Electron Beam Lithography
Advances in Electrical and Electronic Engineering, 2018
Electron Beam Lithography (EBL) process strongly depends on the type of the applied lithographic system, composed of electron sensitive polymers and the substrate. Moreover, applied acceleration voltage changes the volume of Backscattered Electrons (BSE) participation in total energy absorption in resist layers. Proper estimation of energy distribution in used materials, due to electron scattering, is the key in final resist profile calculation and critical parameter in the designing process of the lithography exposure. In the presented paper, the Monte Carlo (MC) simulations of electron beam influence on lithographic system, consisting of positive tone resists (PMMA/MA and CSAR-62) spin coated on different substrates, will be presented. For high accuracy, obtained point spread functions were modelled by double-Gaussian function for Si, GaAs, AlGaN/GaN and InP substrates, respectively. Extracted scattering parameters of forward and backward electrons will be shown and their differences will be discussed. Results of simulated and conducted process of 100 nm metallic path fabrication on mentioned materials will be presented and compared. The practical usage of EBL technique will be shown in the aspect off low resolution application in low energy range of primary electron beam.