Resist charging in electron-beam lithography

Abstract

Electron beam exposure of masks and wafers results in charging of the insulating resist film. This charging results in an electric field which deflects incoming electrons and can be a serious source of pattern placement error in electron-beam lithography. In earlier work (Ingino et al. 1992) the surface potential was found to be positive or even zero under certain conditions. In this study, a model is developed to explain this effect and the surface potential is measured by an independent method, a Kelvin probe non-contacting electrostatic voltmeter. This new study confirms qualitatively the findings of the first study. An area of PBS resist measuring a few square millimeters is exposed using a gaussian focused probe and moved under the Kelvin probe immediately after exposure to measure the surface potential. Thicker resist tended to charge more negatively. The model and experiments confirm early studies that the surface potential is a function of resist thickness, and that there may exist a resist thickness where the surface charge is essentially zero.

Electron beam stimulated field-emission from single-walled carbon nanotubes

“…It is known that these various types generate different levels of external field enhancement. There might even be positive charge accumulation as discovered by Bai et al 3 However, we observed SFE at primary beam energies of up to 20 kV [ Fig. At 2 kV and below (the experiment was done at 2 kV, 1 kV, and 500 V), SFE was very hard to obtain on most of the nanotubes, even though the nanotubes were observed clearly (Fig.…”

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

“…[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. Deviations of tens of nm from the design position of the exposure point due to this potential have been reported to be serious.…”

Non-charging Conditions of Insulating Film under Electron Beam Irradiation

“…There are only a few reports that directly measured the surface potential distribution, and the results with a spatial resolution of several millimeters are published around 1998 by a group led by Pease of Stanford University [11]. Figure 1 shows the schematic diagram of our EFM system installed in our scanning electron microscope (SEM) specimen chamber.…”