Electron beam direct writing technology for printed wiring board

An electron-beam lithography system has been developed which can write electric circuit patterns directly on printed wiring boards from computer-aided design data without making the master and working film masks which are necessary for conventional photolithography. The electron beam is focused to 34 mu m in diameter at an accelerating voltage of 60 kV. The sensitivity of an electrodeposited photoresist to electron-beam exposure is investigated. It is shown that the photoresist is very sensitive to the electron beam and has a threshold dosage of 0.2 mu C/cm/sup 2/. The spatial contours of equienergy density deposited by the electron beam in a 20- mu m-thick resist-copper substrate configuration have been calculated with a Monte Carlo computer method. The geometry of the resist patterns is determined according to the contour line corresponding to about 6*10/sup 18/ eV/cm/sup 3/. It has been confirmed that fine patterns with linewidths less than 100 mu m can be obtained and that this technology is efficient for meeting the constantly growing demand for greater density and shorter turnaround.<
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