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Please use this identifier to cite or link to this item: http://hdl.handle.net/10087/7669

Title: Monte Carlo simulation of forming nano-sized dot arrays by electron beam lithography
Other Titles: 電子線描画法を用いたナノドット列形成のモンテカルロシミュレーション
Authors: 張, 慧
チョウ, エ
Keywords: Electron Beam Lithography
Monte Carlo Simulation
Issue Date: Mar-2013
Publisher: 群馬大学工学部
Abstract: Electron beam lithography (EBL) is expected to achieve the formation of very fine dot arrays for bit-patterned media applications due to its resolution capability and placement accuracy. However, the resolution-limiting factors of electron beam lithography (EBL) at the sub-10 nm length scale are not well understood, which has limited our ability to further improve its resolution. Therefore, using the simulation method to analyze the limiting factors of EBL for sub-10 nm patterning is necessary to be done. In order to revealing the limiting factors of high resolution patterning, I focused my study on two main aspects. The first was evaluating the dependence of exposure conditions (such as incident beam energy, resist thickness, resist type, etc.) to reduce the electron beam scattering range. The second aspect was estimating resist profiles with solubility rates based on various developers to determine optimal development contrast. The details of the two aspects were described as follows. The first aspect: Roughly evaluation of the resist profile estimated by critical energy deposition based on energy deposition distribution (EDD) 1) A home-made Monte Carlo simulation of electron-atom scattering was made. 2) The energy deposition distribution was calculated in thin resist layer on Si substrate. 3) The estimation of nano-sized dot arrays based on critical deposited energy in a parameter of incident electron energy, electron beam diameter, resist thickness and resist type were studied. 4) High incident energy beam, small sized Gaussian beam, thin resist film, negative resist were demonstrated that there are benefit to reduce electron beam scattering range and form very fine nano-sized pattern. The second aspect: Precise estimation of HSQ resist profiles by using various developers with different contrast 1) A new development model of calculating resist profiles with solubility rates based on the three-dimensional EDD was proposed. 2) A sharpened nano-dot resist pattern was obtained by selecting a suitable EDD region. 3) The calculated resist profiles by using the new model agrees well with the experiment results. 4) The effects of exposure dosage and solubility rate on contrast of developer were studied. The resist profiles with various contrast developers (γ from 12 to 1) were calculated. We demonstrated that small dosage interval (∆EDD) is an important parameter to improve the resolution. 5) The suitable contrast of developers was determined by evaluating the predicted resist profiles. High contrast developer was effective to form very fine dot pattern with sufficient. 6) The exposure allowance for high contrast resist and low contrast resist was investigated. We demonstrated that high contrast resist has small exposure allowance. It indicted that we should control exposure dosage severely by using high contrast resist for high resolution patterning. As described above, EB exposure and development calculation is demonstrated to obtain very fine resist profile using high energyhigh-energy electron, high contrast developer and negative resist. This indicates that the optimal condition of EB lithography opens new era to control nanometer-sized structures.
Description: 学位記番号:工博甲464
URI: http://hdl.handle.net/10087/7669
Academic Degrees and number: 12301甲第464号
Degree-granting date: 2013-03-22
Degree name: 博士(工学)
Degree-granting institutions: 群馬大学
Appears in Collections:学位論文

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