Characterization of Fogging and Develop-Loading Effects in Electron-Beam Direct-Writing Technology

Abstract

We investigated long-range critical dimension (CD) error factors, such as fogging and develop loading, to improve CD uniformity in electron-beam direct-writing (EBDW) technology. It was found that the impact of both effects reached 20 mm and the CD of the monitor pattern decreased by no less than 10%. Fogging and develop loading were separated by comparing the newly designed test patterns that were exposed using both EB and a krypton-fluoride excimer laser. We confirmed that the impact of fogging and develop loading by arranging dummy patterns with a density of 40% was estimated to be +8.9 and -18.9% in the CD, respectively. Based on success in separating each effect, fogging and develop loading were decreased by applying an antistatic agent and multipuddle development, respectively.

Investigation of non-charging exposure conditions for insulating resist films in electron beam lithography

“…The null-balance method is a method for determining the surface potential of a specimen by measuring the force applied to the cantilever. 8) As shown in Fig. 2, when a grounding electrode is brought close to the surface of a charged specimen, the electrons in the electrode move by electrostatic induction and are attracted to the surface of the specimen regardless of whether it is positive or negative, making it easier to measure the surface potential.…”

“…One of the problems in this regard is the phenomenon of charging of the photomask during EB exposure. [1][2][3][4][5][6][7][8][9][10][11][12][13] Various papers based on Monte Carlo simulations have been reported on scattering by electron irradiation. [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] Our measurements of surface potentials with an electrostatic force microscope (EFM) confirmed the presence of a potential distribution of the order of several V even a few mm away from the EB exposure point.…”

Non-charging Conditions of Insulating Film under Electron Beam Irradiation

“…Figure 1 shows the schematic diagram of our EFM system installed in our scanning electron microscope (SEM) specimen chamber. Using the null-balance method, the surface potential of a specimen was obtained by measuring the force applied to the cantilever [7]. We measured the surface potential of a 300-nm-thick electron resist (FEP171) on 70-nm-thick Cr on a bulk glass substrate with 30 mm × 60 mm.…”

“…After the EB irradiation, the sample bias was returned to 0 V and the surface potential was measured by EFM. As shown in Figure 2, the surface potential distribution of the sample was measured by changing the bias applied to the sample during beam irradiation from −100 V to 100 V. The results, shown in Figure 3, are obtained with a spatial resolution of about 50 μm, which we know to be the finest [7]. This resolution was determined by the width of the cantilever.…”

Measurement of fogging electrons present in scanning electron microscope specimen chamber

“…Various papers have been reported based on experimental and Monte Carlo simulation about scattering and energy loss that occurs locally in the specimen when the specimen is irradiated with the electron beam (EB). [1][2][3][4][5][6][7][8][9] With the improvement of vacuum technology and optimization of experimental conditions, the removal of noise components has progressed with each applied technology, and the nature of the original signal has become clear. Along with this transition, it has become clear that to analyze complex phenomena that occur in the specimen, not only the electron scattering in the specimen but also the influence of electron scattering in the vacuum specimen chamber where the specimen is placed cannot be ignored.…”